Content:
Presentation type:
ERE – Energy, Resources and the Environment

EGU23-11361 | Orals | ITS3.2/ERE2.8 | ERE Division Outstanding Early Career Scientist Award Lecture

The role of the subsurface in the energy transition – (some of) the (scientific) challenges 

Johannes Miocic

The transition towards carbon-free, renewable based energy systems is a central element to limit global warming and is one of the key societal challenges we are currently facing. The subsurface offers many different pieces for the energy transition jigsaw, from renewable energy from geothermal sources to large volumes of pore-space to permanently sequester carbon dioxide. The subsurface also provides several options for storing renewable energy over seasonal timescales, by storing renewable energy surplus converted into hydrogen and compressed air. As the subsurface can be utilized for many different energy related purposes, it becomes clear that it has to be a crucial part of the energy-transition.  However, most subsurface utilization technologies are not yet used on the scale that is needed for a successful energy transition. One reason for this lies in the incomplete understanding of (geological) processes that occur in the subsurface during, and after, the operation of these technologies. Predicting the performance and the potential of subsurface utilisation in the energy transition can also be hampered by limited data availability and the uncertainties associated with sparse datasets. Here, some of the key geoscience challenges that need to be solved for a timely energy transition are presented and some potential solutions are reviewed. The subsurface can, and must, play an important role in tomorrow’s green energy systems!

How to cite: Miocic, J.: The role of the subsurface in the energy transition – (some of) the (scientific) challenges, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11361, https://doi.org/10.5194/egusphere-egu23-11361, 2023.

ERE1 – Integrated studies

EGU23-592 | ECS | PICO | ERE1.1

Assessment of direct and indirect emissions from the wastewater treatment plant and sludge processing: A case study 

Praveen Kumar Vidyarthi, Pratham Arora, Nadège Blond, and Jean-Luc Ponche

Due to rapid urbanisation and population, a constant supply of clean and fresh water has come under stress. Raw water must be continuously treated and supplied to satisfy the day-to-day needs for potable water for household use. To find a solution to the issue, several governments worldwide have moved their focus to water and sanitation. Large sewage and effluent treatment facilities are continuously working to treat wastewater, which is the most crucial step in addressing the problem of fresh water. Sludge is the main by-product produced by these treatment plants, which creates a challenge when it comes to disposal. The sludge is processed in the treatment facilities before being disposed of, allowing for better waste management. In the treatment process of the wastewater, from the moment the wastewater enters the treatment facility until the sludge is disposed of, there are multiple points at which emissions are produced. These emissions need to be evaluated and dealt with, as they have the potential to significantly impact climate change and the depletion of the ozone layer. The authors have analysed the emissions using several methodologies, including IPCC inventories, life cycle assessment, and many more. The study's findings indicate that a significant quantity of greenhouse gas emissions (directly and indirectly) and air pollutants are emitted during the process of treating wastewater and disposal of sludge.

How to cite: Vidyarthi, P. K., Arora, P., Blond, N., and Ponche, J.-L.: Assessment of direct and indirect emissions from the wastewater treatment plant and sludge processing: A case study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-592, https://doi.org/10.5194/egusphere-egu23-592, 2023.

EGU23-919 | ECS | PICO | ERE1.1

Effect Of Channel Width on Energy Dissipation Efficiency of Stepped Spillway 

Ritusnata Mishra and Chandra Shekhar Prasad Ojha

Abstract:

Experimental investigation on flat stepped spillway were conducted with two different width 0.52m and 0.28m on 26.670 slope under nappe flow regimes. The study assessed the rate of energy dissipation at the toe of the spillway for unit discharge, q, ranging from 0.00954m2/s to 0.078854 m2/s for Froude number (Fr) between 0.5 to 0.85. The stepped chute comprised 10 identical steps having 0.10-m step heights and 0.2-m length. It is observed that the rate of energy dissipation at the step edge was relatively observed to be higher in the wider channel. The energy dissipation rate decreased from 3.81% to 26.135% by decreasing the channel width by 46.15% under same unit discharges. It signifies that the width of channel has certain influence on energy dissipation efficiency of spillway under same slope. Therefore, wider channel should be taken for design of stepped spillway under nappe flow regime. The variation in energy dissipation is due to the variation in mean air concentration between two widths. For further validation of these experimental observations, computational fluid dynamics (CFD) models were also used with k-ɛ turbulence model and0.010 m mesh size. 

Keywords: stepped spillway, energy dissipation, channel width, CFD

How to cite: Mishra, R. and Ojha, C. S. P.: Effect Of Channel Width on Energy Dissipation Efficiency of Stepped Spillway, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-919, https://doi.org/10.5194/egusphere-egu23-919, 2023.

For the formation of oil (PG), a certain geological and geochemical environment of the Earth's Crust is necessary. Geologically, the current PG models are based on a 2-layer model of the Earth's Crust, consisting of Granite and Basalt layers. However, as the drilling of the Kola Superdeep Borehole (SG3) showed, there is no basalt layer on the continents. A model of a 1-layer Earth's Crust was compiled, consisting of a granite layer on the continents and a basalt layer in the Oceans:[1 layer  Мodel of the Earth's Crust Galant (MECG), ( AAPG, Athens 2007; EGU, Vienna 2013,2022;)] сonsist of separated layers of  Granite  and separated layers of  Basalt. This Model of the Earth's Crust Galant (MECG) fundamentally changes the geological and geochemical setting of the Earth's Crust and hence the PG processes. Basalts and Granites are antipodes and therefore fluids migrating from the mantle with the goal of generating oil passing through the Earth's Crust that does not have Basalts but has only Granites will behave differently - respectively. In connection with the change in the geological and geochemical situation, the parameters of the fluid migrating from the mantle will also change: the C-O-H ratio, reactions with the components of the layer, the supply and removal of components, the change in T, the intensity of degassing, the change in the fugacity of O, the depth of the depleted mantle, etc. Since the Kola on the Baltic Shield did not reveal the basalt layer and due to this, the depth [According based on 1 layer Model of the Earth's Crust Galant (MECG), ( AAPG Athens 2007, EGU Vienna 2013)] of the granite layer reaches the mantle deeply and the greater the thickness the thickness of the depleted mantle is greater, from this it can be assumed that the mantle gave up light hydrocarbon components concentrated in the upper horizons of the Lithosphere, and heavy hydrocarbon components still remained in the depleted mantle or are now slowly migrating upward into the granite layer. This may explain that granites contain more light hydrocarbons. Due to the change in the physical and chemical conditions of the Earth's Crust, the PG depth zone changes, expands or localizes, and the composition of the oil changes accordingly. CONCLUSIONS: In connection with the 1-layer model of the Earth's Crust, the energy-material exchange between the domains of the Earth, the Mantle and the Lithosphere changes. Characteristics of the parameters of physic-chemical conditions change. And also the tactics, strategy, philosophy of PG research should change, taking into account the new model of the Earth's Crust.

 

How to cite: Galant, Y.: The Genesis of Oil in connection with a 1-layer Model of the Earth’s Crust, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1002, https://doi.org/10.5194/egusphere-egu23-1002, 2023.

Nano Fe(III) oxide (FO) was employed as an additive material for CO2-aided pyrolysis of spent coffee grounds (SCG) and its impacts on the syngas (H2 & CO) generation and biochar adsorption characteristics were examined. Amendment of FO led to 153 and 682% increase of H2 and CO in pyrolytic process of SCG, respectively, which is deemed to arise from enhanced thermal cracking of hydrocarbons and oxygen transfer reaction mediated by FO. Incorporation of FO successfully created porous structure in the produced biochar. The adsorption tests revealed that the biochar exhibited bi-functional capability to remove both positively charged Cd(II) and Ni(II), and negatively charged Sb(V). The adsorption of Cd(II) and Ni(II) was hardly deteriorated in the multiple adsorption cycles, and the adsorption of Sb(V) was further enhanced through formation of surface ternary complexes. The overall results demonstrated nano Fe(III) oxide is a promising amendment material in CO2-aided pyrolysis of lignocellulosic biomass for enhancing syngas generation and producing functional biochar.

How to cite: Cho, D.-W., Jang, J.-Y., Cheong, Y., and Yim, G.-J.: Co-thermochemical conversion of coffee grounds and nano Fe(III) oxides to fabricate metal-biochar for the simultaneous removal of Sb(V), Cd(II), and Ni(II) from  water, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1700, https://doi.org/10.5194/egusphere-egu23-1700, 2023.

EGU23-2222 | PICO | ERE1.1

Fabrication of PAC sludge-valorized biochars and their practical application to the remediation of methyl arsenic in wetlands 

Jungho Ryu, Young-Soo Han, Dong-Wan Cho, So-Jeong Kim, Yong-Chan Cho, Chul-Min Chon, Joo Sung Ahn, and In-Hyun Nam

This study aims to mitigate As pollution in wetlands by using biochar composites, which are a byproduct of valorizing drinking water treatment sludge (i.e., polyaluminum chloride (PAC) sludge). PAC sludge produced when PAC is used as a coagulant contains various aluminum and iron components because of the high affinity of PAC for heavy metals. Therefore, the valorization of PAC sludge by pyrolysis can be a strategic method to secure environmental safety for sludge utilization by destroying the organic pollutants and immobilizing heavy metals while simultaneously producing biochar composites that can be used as an environmental adsorbent. Biochar composites were fabricated under N2 and CO2 environments, systematically characterized by X-ray diffraction, thermogravimetric, and Brunauer–Emmett–Teller/Barrett–Joyner–Halenda analyses, and tested for the adsorption of As species. Both biochar composites exhibited excellent adsorption performance for both inorganic As (As(III) and As(V)) and organic As (dimethylarsinic acid, DMA). A lab-scale microcosm test showed that ~30% of spiked DMA was removed by biochar and that the total As fixed in the sediment decreased by ~20%. In addition, the As speciation results for the sediment and biochar revealed demethylation of the DMA and reduction of As(V) to As(III) by microorganisms, which was confirmed by a microbial growth batch test. Finally, a large-scale field experiment carried out in an artificial ecological wetland ensured that the addition of biochar could reduce the total amount of As to be immobilized in wetland sediment by 19%. In addition, the presence of biochar could alter the migration trend of As species in plants by reducing the amount of organic As to be fixed in the sediment. The aforementioned results demonstrate the practical feasibility of using PAC sludge-derived biochar as an adsorbent for As species.

How to cite: Ryu, J., Han, Y.-S., Cho, D.-W., Kim, S.-J., Cho, Y.-C., Chon, C.-M., Ahn, J. S., and Nam, I.-H.: Fabrication of PAC sludge-valorized biochars and their practical application to the remediation of methyl arsenic in wetlands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2222, https://doi.org/10.5194/egusphere-egu23-2222, 2023.

EGU23-2351 | PICO | ERE1.1

Water-energy-carbon nexus in Illinois - water supply risk for carbon capture 

Zhenxing Zhang, Elias Getahun, Laura Keefer, Guanping Qie, and Andres Felipe Prada Sepulveda

Recently, University of Illinois has been working on the front-end engineering design (FEED) of carbon capture facilities for several power plants in Illinois. While carbon capture facilities often would need cooling water for operation, the water demand for power plants carbon capture facilities has not received much attention. For the two real-world FEED design projects (the Prairie State Generating Company (PSGC) and the 21st Century Power plant (21CPP)), we comprehensively analyze the water demand and supply risks for the two carbon capture facilities. Both power plants and the associated carbon capture facilities are expected to run for decades and thus climate change would play key role in managing water supply risks which is important for informing the engineering design of water system and cooling system of the carbon capture facilities. Both historic and future hydrologic conditions are examined to determine water supply risks. Future hydrologic conditions are simulated using hydrologic models and global circulation models (GCM) results. The climate scenarios are adopted from the Coupled Model Intercomparison Projection Phase 5 (CMIP5) datasets. Three representative concentration pathways (RCPs), i.e. RCP2.6, RCP4.5, and RCP8.5, are employed for exploring different future carbon dioxide emission scenarios. This work explores the tradeoff between water footprint and carbon footprint of power plants in Illinois and provides scientific information for water management and carbon management and for engineering design of the real-world carbon capture facilities.

How to cite: Zhang, Z., Getahun, E., Keefer, L., Qie, G., and Felipe Prada Sepulveda, A.: Water-energy-carbon nexus in Illinois - water supply risk for carbon capture, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2351, https://doi.org/10.5194/egusphere-egu23-2351, 2023.

Prussian blue analogue (PBA) has been received great attention as a material for radioactive Cs removal because of its high Cs ion adsorption efficiency. In this study, we synthesized PBA with three different transition metal ions (Ni(II), Co(II), and Fe(II) for NiFe-PBA, CoFe-PBA, and FeFe-PBA, respectively) and adjusted their particle sizes and surface areas by controlling the amount of stabilizing agent. They also composited with TiO2 and then compared the efficiencies of Cs ion adsorption under dark or UV light. The larger the surface areas and the smaller the particle size, the better the Cs ion adsorption, and the NiFe, NiFe-TiO2 and FeFe-TiO2 showed additional Cs ion adsorption under UV light irradiation. In particular, NiFe has an adsorption capacity of about 0.8 mmolg-1 and 1.7 mmolg-1 under dark and UV light, respectively, which is a result of about twice the increase in the adsorption capacity by UV light irradiation. In addition, the NiFe-TiO2 nanocomposite shows adsorption capacities of about 0.45 mmolg-1 and 1.5 mmolg-1 under dark and UV light, respectively, which is a result of about three times the increase in the adsorption capacity by UV light irradiation. Photo-induced additional adsorption on NiFe showed even with radioactive 137Cs adsorption. This enhanced Cs ion adsorption of NiFe happens due to photoinduced charge transfer in NiFe molecular, which leads to additional adsorption of Cs ions. This is very meaningful result because it is first study of photo-induced additional removal of Cs on PBAs.

How to cite: Kim, S., Kim, M., and Eun, S.: Photo-induced enhancement of radioactive 137Cs removal by adsorption on Prussian blue analogues, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2500, https://doi.org/10.5194/egusphere-egu23-2500, 2023.

EGU23-3456 | ECS | PICO | ERE1.1

Mathematical modeling of dispersed phase behavior of water-in-oil emulsions in electrostatic crude oil desalters 

Ghazal Kooti, Bahram Dabir, Reza Taherdangkoo, and Christoph Butscher

The produced crude oil from reservoirs usually contains a considerable amount of water which is submitted to large shear rates through production process, and due to the existence of natural surface-active agents in crude oils, stable water-in-oil (W/O) emulsions are formed. Effectively purifying the emulsified crude oil through the electrostatic desalting process plays an important role in reducing its water and water-soluble salts contents, which otherwise exacerbate oil deterioration, equipment corrosion, and catalysts deactivation in subsequent units. The electrostatic desalting process has proved to be an efficient means of separation using electrodes subjected to a high voltage to enhance the coalescence of water droplets. In this study, a mathematical model was developed to simulate the W/O dispersed flow to study the evolution of droplet size distributions in crude oil desalters. The population balance approach was employed to describe the behavior of W/O emulsions in the continuous phase assuming that the process is controlled by two simultaneous physical phenomena; breakage and coalescence of droplets. Experimental results on the W/O system were utilized to validate the mathematical model and the employed numerical technique. The agreement between the developed model and experimental droplet volume size distributions was shown to be satisfactory, confirming the further applicability of the model. The present study can be helpful for optimizing crude oil desalting operating conditions, enhancing efficiency, and decreasing energy and chemical consumption.

How to cite: Kooti, G., Dabir, B., Taherdangkoo, R., and Butscher, C.: Mathematical modeling of dispersed phase behavior of water-in-oil emulsions in electrostatic crude oil desalters, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3456, https://doi.org/10.5194/egusphere-egu23-3456, 2023.

Detection of high pesticide concentrations in sediments and water often leads to prioritizing a site as being ‘at risk’. However, the risk does not depend on pesticide concentration alone, but on other site-specific characteristics also. We developed an indicator that identifies the ‘Level of Concern’ by integrating five such characteristics: (i) pesticide concentrations in surface and groundwater causing risks to ecological health (ii) impacts on human health, (iii) water scarcity, (iv) agricultural production, and (v) biodiversity richness. We applied this framework in an agricultural region of the Lower Ganges Basin in West Bengal, India. We measured concentrations of selected organochlorine pesticides (OCPs) in surface and groundwater within an 8 km2 area in 2019. Of 20 banned and restricted OCPs, 11 were detected as a cause of high risk to ecological health and 10 were detected at concentrations above the Accepted Carcinogenic Risk Limit (ACRL) for humans. In the pre-monsoon, the mean concentrations of ΣOCPs in groundwater and surface water were 126.9 ng/L and 104 ng/L,in the monsoon they were 144.7 ng/L and 138 ng/L, and in the post-monsoon 122.1 ng/L and 147 ng/L respectively. In groundwater, no significant seasonal difference was observed in most pesticides. In the surface water, 7 pesticides were significantly higher in the monsoon and post-monsoon, which may be attributed to increased runoff as well as post monsoon application of OCPs. In September 2022we again measured OCP concentrations in surface water and sediment. The mean concentration of 14 of the 20 measured OCPs were found to be significantly lower in the post-pandemic period compared to the pre-pandemic time. These lower pesticide concentrations may indicate a reduced use of OCPs in agricultural practices during the pandemic. This area was identified as being at the highest Level of Concern, even though the OCP concentrations alone conformed to general guidelines.

How to cite: Ray, S., Mohasin, P., and Chakraborty, P.: Developing an Indicator of Pesticide Pollution Risk: Integrating the site specific water scarcity, biodiversity and impacts on human Health, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7429, https://doi.org/10.5194/egusphere-egu23-7429, 2023.

In recent times, the research trend has shifted towards identifying sustainable energy resources. Bioenergy generation employing wastewater and micro-organisms might be a potential solution to achieve this goal. In microbial fuel cells (MFC), the energy stored in the chemical bonds of contaminants present in wastewater is utilized by the micro-organisms for their metabolism in redox conditions. Furthermore, in this process, free electrons are released into the system, which are captured by the electrodes resulting in the generation of electricity in the external circuit. Hence, the system provides wastewater treatment along with bioenergy generation. However, the system finds difficulty in degrading recalcitrant organic compounds, such as pharmaceuticals and other emerging contaminants, which is possible in constructed wetland (CW) systems. However, CWs require a large footprint area. Recently, combined CW and MFC systems are being used for this purpose due to their resilience and capacity to produce electricity and provide a high level of wastewater treatment. Combined CW-MFC has been found to be more useful than either system alone by complimenting their issues as the redox conditions required for the proper functioning of the MFC system are available in the CW system. Furthermore, the high diversity of micro-organisms present in MFC improves the treatment efficiency of the CW system. This study involves the application of a combined CW-MFC system for the treatment of wastewater and the production of bioelectricity using Lemna minor as macrophyte species. Graphite plates were used as the anode and cathode for electricity production. In order to test the system's effectiveness in terms of removing recalcitrant organic compounds, synthetic wastewater was spiked with 5 mg/L of sulfamethoxazole. The influence of various parameters, such as electrode spacing, the substrate to water depth ratio, and the initial COD concentration of wastewater, was studied. Considerably high removal of around 99% for sulfamethoxazole and 90% for COD removal were observed, along with the production of 133 mV of voltage. It was observed that with the increase in initial COD concentration and substrate to water depth ratio, COD removal also increased. However, an increase in electrode spacing and substrate to water depth ratio after a certain limit showed a negative effect on voltage generation. The entire system could effectively generate bioenergy and treat the sulfamethoxazole-contaminated wastewater.

Keywords- Constructed wetlands, Microbial fuel cell, Lemna minor, Emerging contaminants, Bioelectricity

How to cite: Jain, M., Ghosal, P. S., and Gupta, A. K.: Application of combined constructed wetland- microbial fuel cell system for simultaneous bioenergy generation and treatment of wastewater contaminated with sulfamethoxazole, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8535, https://doi.org/10.5194/egusphere-egu23-8535, 2023.

EGU23-10017 | ECS | PICO | ERE1.1

Inter-regional environmental imbalance under lasting pandemic exacerbated by residential response 

Chunjin Li, Jintai Lin, Lulu Chen, Qi Cui, Yu Liu, Erin E. McDuffie, Mingxi Du, Hao Kong, and Jingxu Wang

Pandemics greatly affect transportation, economic and household activities and their associated air pollutant emissions. In less affluent regions, household energy use is often the dominant pollution source and is sensitive to the affluence change caused by a persisting pandemic. Air quality studies on COVID-19 have shown declines in pollution levels over industrialized regions as an immediate response to pandemic-caused lockdown and weakened economy. Yet few have considered the response of residential emissions to altered household affluence and energy choice supplemented by social distancing. Here we quantify the potential effects of long-term pandemics on ambient fine particulate matter pollution (PM2.5) and resulting premature mortality worldwide, by comprehensively considering the changes in transportation, economic production and household energy use. We find that a persisting COVID-like pandemic would reduce the global gross domestic product by 11.2% and PM2.5-related mortality by 9.5%. The global mortality decline would reach 13.0% had the response of residential emissions been excluded. Among the 13 aggregated regions worldwide, the least affluent regions exhibit the greatest fractional economic losses with no comparable magnitudes of mortality reduction. This is because their weakened affluence would cause switch to more polluting household energy types on top of longer stay-at-home time, largely offsetting the effect of reduced transportation and economic production. International financial, technological and vaccine aids could reduce such environmental imbalance.

How to cite: Li, C., Lin, J., Chen, L., Cui, Q., Liu, Y., McDuffie, E. E., Du, M., Kong, H., and Wang, J.: Inter-regional environmental imbalance under lasting pandemic exacerbated by residential response, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10017, https://doi.org/10.5194/egusphere-egu23-10017, 2023.

EGU23-10512 | ECS | PICO | ERE1.1

Characterization of the social elements involved in socio-environmental conflicts in Mexico. 

Mario Alberto González Lezama, Nelly Ramírez Serrato, Mariana Patricia Jácome Paz, Isaac Hernandez Cedeño, and Luis Gabriel Duquino Rojas

 Socio-environmental conflicts are the result of an alteration in the natural environment that has repercussions on the interests of the social actors involved. The management of any case depends on the stage of the conflict, the interest in taking advantage of the resource, and the group that takes precedence over the change that this would imply. The environmental factors consist of many climatic, social, and economic variables that result in many types of conflict. For this, so many efforts have already been made to map these incidents at the national and international levels. One such mapping was conducted in the environmental justice atlas, an international compendium of environmental issues. However, little is known about the actors involved in such conflicts. The objective of this work is to identify the resistance actors reported by the Environmental Justice Atlas for Mexico and to search for available information on each of them, as well as the estimated or reported location of their headquarters. The main result was a cartographic mapping of the locations of these actors. The Environmental Justice Atlas registers 151 socio-environmental conflicts in Mexico, in which 485 civil organizations are or were in some way expressing their disagreement or rejection of some projects or megaprojects, while the Mexican government has participated with 171 institutions of the three levels of government, and has been judged and partnered in several of these conflicts; 186 state-owned companies representing the private sector have been identified as the ones responsible for affecting the interests of the actors on the territory and resources of their respective states. From this exercise, it was determined that not all actors have public location information, and even if they do have data, it is difficult to locate them, which could suggest a preference for anonymity when opposing different management of the territory and its resources and the awareness of possible risk in doing so.         

How to cite: González Lezama, M. A., Ramírez Serrato, N., Jácome Paz, M. P., Hernandez Cedeño, I., and Duquino Rojas, L. G.: Characterization of the social elements involved in socio-environmental conflicts in Mexico., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10512, https://doi.org/10.5194/egusphere-egu23-10512, 2023.

EGU23-12708 | ECS | PICO | ERE1.1

Negative Emissions based on Photoelectrochemical Methods: Surface Investigation of Potential Catalysts 

Daniel Lörch, Holger Euchner, Aya Mohamed, Peter Bogdanoff, and Matthias May

Mitigating climate change is one of the greatest challenges humanity has to face in the next decades. For this purpose, negative emissions – the active removal of large amounts of carbon dioxide from the atmosphere (~10Gt/a) – are indispensable, meaning that highly efficient methods for carbon dioxide removal have to be developed.1

In our work we aim to design a photoelectrochemical system that uses solar energy to drive a catalytic process that converts carbon dioxide into long term stable storage products such as oxalate or carbon flakes. Here, we present first results of electrochemical and spectroscopic investigations on two promising catalytic processes for carbon dioxide conversion which are based on metallic cerium and a GaInSn–based liquid metal alloy. The determination of the conversion efficiency allows for an estimation of the area demand of a large-scale deployment of our artificial photosynthesis-based process to meet the carbon dioxide reduction goals.

Apart from developing catalytic processes that result in high solar to carbon efficiencies, our work aims to improve the knowledge on the solid/liquid interface between catalyst and electrolyte. This is done by applying a combination of well established electrochemical methods like Cyclic Voltammetry or Chronoamperometry and operando Spectroscopy based on Raman and Reflection Anisotropy Spectroscopy. This is expected to allow for monitoring and controlling changes at the catalytic surfaces, like the formation of potentially catalyst poisoning species such as cerium fluoride. Since surface processes play a crucial role in the carbon dioxide conversion, understanding and controlling them might pave the way for improvements on the conversion efficiency. This would further reduce the area requirements of our system, which in turn would ease the suspected land-use conflict potential caused by climate change mitigation measures.

How to cite: Lörch, D., Euchner, H., Mohamed, A., Bogdanoff, P., and May, M.: Negative Emissions based on Photoelectrochemical Methods: Surface Investigation of Potential Catalysts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12708, https://doi.org/10.5194/egusphere-egu23-12708, 2023.

EGU23-104 | ECS | Orals | ERE1.4

Does the assumption of biogenic carbon neutrality affect decarbonization pathways? Lessons learned from a techno-economic analysis 

Hamed Kouchaki Penchah, Olivier Bahn, Kathleen Vaillancourt, Lucas Moreau, Evelyne Thiffault, and Annie Levasseur

Net-zero emission targets require transitioning to low carbon energy sources (including bioenergy) and large-scale carbon dioxide removal. Aside from direct air capture (DAC), bioenergy with carbon capture and storage (BECCS) and terrestrial carbon removal and sequestration are two available negative emission technologies (NETs) ready for large-scale deployment. Nationally determined contributions endorse bioenergy as an alternative carbon neutral energy source for fossil fuels. However, this carbon neutral assumption is disputed with several studies indicating that it may lead to accounting errors and biased decision-making.

Bottom-up techno-economic energy system models such as the TIMES framework are used to identify and analyze potential decarbonization pathways for countries or regions. However, these models do not include biogenic carbon flows. Biogenic carbon refers to the carbon contained in biomass. One could assume that biogenic carbon is neutral since the amount of carbon emitted into the atmosphere through biomass combustion and the amount of carbon sequestered by plants during their lifetimes are equal. This assumption may be acceptable when the biomass rotation length is short, as in annual crops, and the balance between emissions and uptakes is indeed neutral. The assumption, however, may not remain valid when the sequestration period is lengthy, as in the case of forest trees. This study combines an aspatial, stand- and landscape-level modeling framework (CBM-CFS3) with a bottom-up techno-economic energy system model (NATEM). We use the CBM-CFS3 output to model various forest management strategies that would result in different biomass availability for bioenergy as well as net forest carbon stocks and emissions. This allows us to determine whether and how this biomass will be used in the energy system over time. Besides, we model several forest-based bioenergy and BECCS technologies to allow the energy system to use the available biomass. This is the first time biogenic CO2 flows are being modeled in a thorough energy system model such as TIMES. We show how the assumption of carbon neutrality results in biased decision-making (using different sets of NETs and resources). We demonstrate that the decarbonization effort could be reduced by integrating forest sequestration into the energy system model. We explore how a high sequestration capacity forest management strategy may minimize the need for expensive NETs such as DAC. Moreover, this research highlights the need to adopt the most promising forest management strategy before investing in BECCS.

How to cite: Kouchaki Penchah, H., Bahn, O., Vaillancourt, K., Moreau, L., Thiffault, E., and Levasseur, A.: Does the assumption of biogenic carbon neutrality affect decarbonization pathways? Lessons learned from a techno-economic analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-104, https://doi.org/10.5194/egusphere-egu23-104, 2023.

EGU23-235 | ECS | Posters on site | ERE1.4

Life Cycle Assessment of mitigation measures of greenhouse gas emissions from beef production in England 

Asma Jebari, Adie Collins, Taro Takahashi, Michael RF Lee, Paul Harris, Laura Cardenas, Fabiana Pereyra, and Graham McAuliffe

British and Northern Irish agri-food systems are faced with the challenge of reducing their supply-chain emissions of greenhouse gases (GHGs) such as nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) in line with the UK’s ambition of achieving a cross-sector ‘net zero’ economy by 2050. Approximately 10% of the GHG emissions are generated by agriculture, and approximately 56% of these GHGs are generated by livestock in the form of CH4 from enteric fermentation (eructation primarily) and manure management (i.e., storage and subsequent application as an organic fertiliser). Numerous mitigation strategies, both extant and at prototype stage, are being proposed to reduce GHG emissions from ruminants, with many aimed at reducing enteric CH4 (e.g., methane inhibitors such as 3NOP and ‘wearables’ which break CH4 down into CO2 and water vapour during respiration). Before implementing such practices, it is critical to evaluate their net impact on primary production GHG emissions (i.e., farm-level losses). Thus, a cradle-to-farm gate scale modelling framework combining a process-based model, the RothC Model, with Life Cycle Assessment (LCA) was conducted to explore the benefits and trade-offs of a range of intervention strategies for grazing beef systems in UK.

Mitigation interventions were applied to a baseline ‘business as usual’ scenario using the UK Research Council’s (UKRI) National Capability, the North Wyke Farm Platform utilising high resolution data collected on the world’s most instrumented research fam. Mitigation effects on net GHG emissions were subsequently assessed through an LCA scenario analysis with a view to identifying the most feasible, cost-effective strategies. The interventions assessed included: (i) grazing management (e.g., decreasing inputs of synthetic fertilisers and optimising stocking densities); (ii) manure management practices (e.g., adopting anaerobic digestion technology); (iii) livestock feeding regimes (e.g., dietary modification such as inhibitory supplementation) and breeding practices (, for instance, identifying high-performing breeding animals which have been shown to generate fewer GHGs whilst increasing both throughput and financial provision). Although the results to be presented in this work are currently preliminary, some notable findings with implications for policymakers have been observed already; for example, including carbon uptake from soils in a cradle-to-farmgate analysis can reduce system-wide emissions by ~10% in certain circumstances including climate, soil type, and manure management.

How to cite: Jebari, A., Collins, A., Takahashi, T., Lee, M. R., Harris, P., Cardenas, L., Pereyra, F., and McAuliffe, G.: Life Cycle Assessment of mitigation measures of greenhouse gas emissions from beef production in England, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-235, https://doi.org/10.5194/egusphere-egu23-235, 2023.

EGU23-2264 | ECS | Orals | ERE1.4

Modelling soil organic carbon stocks and greenhouse gases in European forests with multi-model ensembles 

Elisa Bruni, Bertrand Guenet, Rose Abramoff, Stefano Manzoni, Swamini Khurana, and Boris Tupek

State-of-the-art soil models can be used to monitor and predict the evolution of soil organic carbon (SOC) stocks and greenhouse gas (GHG) fluxes at national, sub-national, and supernational levels. This can help predict the effect of disturbances on the soil and facilitate the development of sustainable management practices to prevent further soil degradation and GHG losses under climate change.

However, model simulations are still highly uncertain due to many factors. For instance, the lack of understanding of many soil processes, the way processes are represented in the models, and the parametrization, initialization, and forcing variables used to run them. One way to consider these uncertainties is to use multi-model ensembles, thus simulating the evolution of SOC stocks and GHG fluxes according to models with different structures and mechanistic assumptions.

In this work, we show a webtool that enables the simulation of SOC stocks and GHG gases in European forests under different climate and land-use change scenarios, using a multi-model ensemble. In the absence of on-site measurements, the webtool directly accesses online databases of pedo-climatic data that is required to run the models.

Models also need to be correctly parameterized and evaluated before their application. For that, we build a map of model parameters that can be used to force the models, and which is evaluated on the European LUCAS database. Uncertainties linked to the initialization method used are also discussed.

How to cite: Bruni, E., Guenet, B., Abramoff, R., Manzoni, S., Khurana, S., and Tupek, B.: Modelling soil organic carbon stocks and greenhouse gases in European forests with multi-model ensembles, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2264, https://doi.org/10.5194/egusphere-egu23-2264, 2023.

While Africa has contributed negligibly to global emissions, it stands out as the world's most vulnerable region, owing to the continent's current low levels of socioeconomic growth and, thus, a lack of resources to afford the goods and services required to recover from the worst of the changing climate effects. Temperature and rainfall projections in disaster-prone areas are therefore critical for planning climate change mitigation and boosting our adaptation capacity to respond effectively. This study makes a contribution in this direction by identifying vulnerable areas to warming and drought in Africa, with a particular focus on Morocco—whose conditional goal, which will be attained with international assistance, is rated as "almost sufficient" but is not yet in alignment with the Paris Agreement's goal—, taking into account diverse levels of political efforts to slow down and adapt to climate change, known as the Shared Socio-Economic Pathways (SSPs), using the outputs of the global climate model, HadGEM3-GC31-LL, provided by the Coupled Model Intercomparison Project (CMIP) Phase 6 [1]. Temperature and precipitation projections over Africa indicate significant geographical variability in the twenty-first century. The northern part of Africa (NAF), the Sahara (SAH), and South West Africa (SWAF) are expected to undergo increasing warming, followed by Central Africa (CAF), North East Africa (NEAF), and South-East Africa (SEAF). When compared to other regions, West Africa (WAF) and Central East Africa (CEAF) will have the lowest mean annual temperature values. The SAH, NEAF, and CEAF are projected to get more precipitation than the NAF, WAF, SWAF, and SEAF, which are expected to endure severe drought conditions. The emission scenario has a large influence on the quantity of rain that falls over Central Africa (CAF), which has increased precipitation under the strong forcing scenario. The amount of greenhouse gases emitted globally over the next few decades (i.e., emission scenario) and the level of uncertainty in Morocco's climate sensitivity to those emissions (i.e., climate model, time horizon) will determine the extent of climate change in the next few decades. We estimate that significant reductions in greenhouse gas emissions could limit Morocco's annual average temperature rise to 1.07 °C (resp. 1.72 °C) in the near- (resp. long-) term. However, if these emissions are not greatly decreased, yearly average temperatures may rise by 1.25 °C (resp. 6.25 °C) by the end of the century. Morocco's spatio-seasonal warming pattern is highest in the mountainous areas of the Rif and Atlas Mountains and lessens along the Atlantic and Mediterranean Seas. The findings also point to a significant gradual emergence of humid climate in the South, as well as a migration of aridity to the North, East, and West. 

[1] Bouramdane, A.-A. Assessment of CMIP6 Multi-Model Projections Worldwide: Which Regions Are Getting Warmer and Are Going through a Drought in Africa and Morocco? What Changes from CMIP5 to CMIP6? Sustainability 2023, 15, 690. https://doi.org/10.3390/su15010690

How to cite: Bouramdane, A.-A.: Determining Vulnerable Areas to Warming and Drought in Africa and Morocco Based on CMIP6 Projections: Towards the Implementation of Mitigation and Adaptation Measures, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2456, https://doi.org/10.5194/egusphere-egu23-2456, 2023.

EGU23-2672 | ECS | Orals | ERE1.4

The impacts of ground-mounted solar parks on soil health in the UK 

Lucy Treasure, Alona Armstrong, Stuart Sharp, Simon Smart, and Guy Parker

Soils are a key natural capital asset. Soil health, defined as the capacity of a soil to function as a living system, is a vital component of wider ecosystem processes and functioning, including the flow of multiple ecosystem services. Land use change is an important factor influencing declines in soil health globally. To meet demand for low carbon energy, ground-mounted solar parks (SPs) have expanded rapidly in recent decades, incurring significant land use change, with predictions that UK solar capacity could quadruple by 2050. There is potential for both positive and negative impacts of SPs on soil health - SPs present a relatively unique land use change, in that large areas of land remain physically undisturbed but are shaded by panels. This shading can alter microclimate metrics under panels, including air and soil temperature, soil moisture, photosynthetically active radiation and humidity, which may impact indicators of soil health. Further, the majority of SPs in the UK are developed on former agricultural land, often intensively managed. Arable land use is one of the most detrimental to overall soil health, whilst there is significant evidence supporting the benefits of taking agricultural land out of cultivation, including increased soil carbon, reduced erosion, compaction, and pollution. Considering the land use requirements and microclimatic variation within SPs, it is critical that their impacts on soil health are understood, yet research on solar park-soil impacts remains sparse.

We investigated the impact of location within SPs (under solar panels and in gap areas) and the influence of prior land use (arable and grassland) on physical, chemical, and biological indicators of soil health, to address this knowledge gap and provide one of the first quantifications on the impacts of SP development on soil health.  Preliminary results suggest no difference in indicators with SP prior land use, however bulk density and inorganic phosphorus were significantly lower in gap areas compared to under panels, whilst organic matter and microbial biomass carbon were higher in gap areas. These results suggest that soil health may be degraded under the shade of solar panels.

However, on-site management decisions such as livestock grazing, wildflower planting and mowing regimes likely influence soil health indicator values and vary across SPs. Further, the SPs studied have been operational since 2014, a relatively short time in terms of soil health. As such, further research is required across spatial and temporal scales, considering the impact of SP management actions to accurately infer SP impacts on soil health.

How to cite: Treasure, L., Armstrong, A., Sharp, S., Smart, S., and Parker, G.: The impacts of ground-mounted solar parks on soil health in the UK, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2672, https://doi.org/10.5194/egusphere-egu23-2672, 2023.

EGU23-3063 | Posters virtual | ERE1.4

Protecting global forest to avoid carbon emissions 

Zhangcai Qin

The Glasgow Declaration on forests signed at the recent UN Climate Change Conference (COP 26) committed to halt forest loss by 2030. Over 141 countries and regions, collectively covering over 90% of global forest, endorsed this declaration, making it by far one of the largest forest protection programs in the world. Avoiding forest loss can generally contribute to climate change mitigation, however, the impacts of the declaration on global CO2 emissions reduction is still unclear. Here we show that by stopping global forest area loss, a large portion of deforestation-related CO2 emissions could be reduced, and the socio-economic damage to global society could be largely avoided. Over three quarters of emissions could be reduced over the next three decades, though any delays in implementing the declaration would decrease the avoided emissions. The value of the public goods provided by avoided deforestation could compensate for loss of private goods gained from clearing the land for agriculture. The Glasgow Declaration, if implemented fully and in a timely fashion, could help the world move closer to carbon neutrality.

How to cite: Qin, Z.: Protecting global forest to avoid carbon emissions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3063, https://doi.org/10.5194/egusphere-egu23-3063, 2023.

EGU23-4117 | Posters on site | ERE1.4

Decarbonization and sustainable energy transition to the post-lignite era in Greece 

Efthimios Tagaris, Apostolos Tranoulidis, Rafaella-Eleni P Sotiropoulou, and Kostas Bithas

It has been proved that reaching the objective of complete decarbonization in Greece by the year 2028 is necessary to ensure the stability of the country's power-generating system and Greece's energy security. Since the middle of the 1960s, when lignite reserves were exploited for the purpose of power production, the Region of Western Macedonia, which includes both an industrial and an agricultural sector, has held a unique position within the borders of Greece. However, as a result of a strategy for the transition to a more sustainable energy plan, the majority of plants that were powered by lignite were required to shut down in 2019. A just transition in a post-lignite era requires strategic planning in order to avoid social, economic, and energy issues while simultaneously maximizing the amount of power output that is sustainable. The present study makes use of a SWOT analysis in order to carry out a comprehensive socio-economic analysis for the Region of Western Macedonia. This analysis takes into account all of the primary economic sectors that are present in the region that is being studied, and it discusses the priorities that have been set by the Energy Union in order to achieve its energy goals. Additionally, the study discusses the results of a generalized SWOT analysis that was applied to the specific strategy of the Energy Union, placing special emphasis on the axes requiring further support actions. According to the findings of the study, the Region of Western Macedonia possesses significant advantages and presents a multitude of fresh chances as it makes the transition to a new production model. On the other hand, its unemployment rates are quite high, and its competitiveness and innovation rates are quite poor. The difficulty to locate sufficient employment opportunities is the primary factor contributing to the desertification of the region. When taking into account the aims of the Energy Union, the Region of Western Macedonia follows the priorities of Europe in its transition to the new production model in a satisfactory manner; yet, there is a significant amount of potential for development.

How to cite: Tagaris, E., Tranoulidis, A., Sotiropoulou, R.-E. P., and Bithas, K.: Decarbonization and sustainable energy transition to the post-lignite era in Greece, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4117, https://doi.org/10.5194/egusphere-egu23-4117, 2023.

EGU23-4490 | Orals | ERE1.4

Comparing Life-Cycle Environmental Impacts of Natural Gas-Fired and Renewable Electricity Generation 

Michael Young, Gurcan Gulen, Atta Ur Rehmman, and David Chapman

The mission of the Comparing Electricity Options (CEO) research program at UT Austin is to understand and quantify trade-offs among society’s goals of providing reliable and affordable energy, mitigating climate change, and improving local environments that can sustain a healthy economy for future populations. Our goals are to create tools that support decision makers in the energy and policy sectors with better environmental and economic assessments to manage environmental, social, and governance risks across global supply chains; highlight where innovation can mitigate impacts; and, inform policies that encourage innovation. This is done by conducting a three-phase, data-driven study of natural gas-fired, wind, and solar power plants (including batteries to address intermittencies). We use several methodologies and will develop interactive tools to allow wider audiences to quickly compare alternative scenarios. In Phase 1, which we anticipate will be completed in early 2023, we conduct a life-cycle assessment (LCA) of power plants for 18 impacts covering greenhouse gas and local (PM, SOX, NOX) emissions; land and water use and pollution, biodiversity and ecosystem services, etc. The LCA system boundaries encompass extraction of natural resources, manufacturing of generation equipment, power plant operations, and end-of-life. In Phase 2, which will begin in mid-2023, we investigate electric power grids instead of individual power plants, and aggregate environmental impacts and costs associated with transitioning generation mixes over time, including new transmission and distribution infrastructure. In Phase 3, we use results from Phases 1 and 2 to develop a new cost estimate for electricity at the consumer level that includes environmental and system costs. We show early results from Phase 1 and how environmental impacts are manifested along the global supply chains needed to support energy development, at different times during the 30-year lifespan of the facilities.

How to cite: Young, M., Gulen, G., Ur Rehmman, A., and Chapman, D.: Comparing Life-Cycle Environmental Impacts of Natural Gas-Fired and Renewable Electricity Generation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4490, https://doi.org/10.5194/egusphere-egu23-4490, 2023.

EGU23-4912 | ECS | Orals | ERE1.4

Appropriate solar park management enhances bumble bee populations under different land use scenarios 

Hollie Blaydes, Emma Gardner, Duncan Whyatt, Robert Dunford, Simon Potts, and Alona Armstrong

Land use change for solar parks could provide a unique opportunity to support insect pollinators, such as bumble bees, if located and managed appropriately. Vegetation management can provide floral and nesting resources for bumble bees and well managed solar parks could safeguard suitable bumble bee habitats for up to 40 years. Understanding the potential for solar parks to contribute to bumble bee conservation is growing, but the longer-term roles of solar parks have not yet been considered. To address this knowledge gap, we used a geographic information system (GIS) and a process-based pollinator model to quantify the impact of solar park management on bumble bee density in present day Great Britain and in 2050. Future landscapes were based on state-of-the-art UK-SCAPE CRAFTY-UK scenarios that represent how land use responds simultaneously to climatic and social change. Scenarios range in levels of sustainability and therefore deliver contrasting landscapes that impact bumble bees in both solar parks and the surroundings. In the present day, solar parks managed with resource-rich wildflower margins approximately doubled bumble bee density compared to those managed as turf grass. Moreover, bumble bee density was higher in solar parks surrounded by more floral resources. In future scenarios, the impact of solar park management differed depending on how the surrounding landscape changed. Our findings suggest that solar parks could contribute to bumble bee conservation both now and in the future, potentially becoming more or less valuable habitats depending on land use change.

How to cite: Blaydes, H., Gardner, E., Whyatt, D., Dunford, R., Potts, S., and Armstrong, A.: Appropriate solar park management enhances bumble bee populations under different land use scenarios, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4912, https://doi.org/10.5194/egusphere-egu23-4912, 2023.

EGU23-5329 | ECS | Posters on site | ERE1.4 | Highlight

Change in soil organic carbon content in European mountain forests based on LUCAS soil databases 2009-2018 

Magdalena Gus-Stolarczyk, Anna Bartos, Agata Gołąb, and Łukasz Musielok

Forest ecosystems act as huge reservoirs of organic carbon by binding atmospheric carbon dioxide in the process of photosynthesis. Carbon in forests is stored both in aboveground and belowground biomass as well as in the form of dead organic matter in the soil. This soil organic carbon (SOC) pool may play a particularly important role in mitigating climate change through the long-lasting retention of organic compounds.

Much of Europe's forests are located in the mountains, where low temperatures and high humidity protect dead organic matter from rapid oxidation. In addition, the area covered by forests is increasing due to forest succession in abandoned areas. Both land cover change, as well as tree species conversion, are the factors that can lead to significant changes in SOC content. Thus, the aim of this study was to determine the impact of land use, land-use change, and forestry (LULUCF) on SOC content in European mountain forest ecosystems.

Data on land cover and SOC content in European mountains (areas above 500 m a.s.l.) were obtained from the 2009, 2015 and 2018 Land Use and Coverage Area frame Survey (LUCAS) databases. We compared the SOC content of sites that were under forests in 2009 or 2018, with or without changes in land use or species composition over the designated period. The highest increase in SOC content was noted at sites where conversion from meadow to deciduous forest took place (mean 3.46 g C kg-1 year-1). The SOC content decreased at sites that in the period 2009-2018 were constantly under mixed forests (mean -0.87 g C kg-1 year-1) and under coniferous forests (mean -0.21 g C kg-1 y-1), while at sites located under deciduous forests, the SOC content increased (mean 1.08 g C kg-1 y-1). These results suggest that forestation and maintenance of deciduous forests may have the greatest impact on carbon sequestration in mountain ecosystems in Europe.

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 952327 (HES-GEO).

How to cite: Gus-Stolarczyk, M., Bartos, A., Gołąb, A., and Musielok, Ł.: Change in soil organic carbon content in European mountain forests based on LUCAS soil databases 2009-2018, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5329, https://doi.org/10.5194/egusphere-egu23-5329, 2023.

EGU23-5703 | ECS | Orals | ERE1.4

Long-term impact of land-use change on soil organic carbon in German agriculture 

David Emde, Axel Don, Christopher Poeplau, and Florian Schneider

Land-use change and land management practices alter soil organic carbon (SOC) dynamics in agricultural systems. Changing natural vegetation to agriculture in particular has resulted in a loss of approximately 5% of the current global terrestrial carbon stock. However, this carbon loss is reversible. Increasing the area of grassland is, therefore, an increasingly discussed climate change mitigation option since grasslands often store similar SOC stocks to natural vegetation. However, the time it takes for cropland to return to its pre-cropland carbon state after conversion to grassland is far from certain. Using soil and land-use history data gathered during the German Soil Inventory as well as from historical land use maps, this study therein aims to answer two questions: i) how does land-use change affect SOC stocks in agricultural systems; and ii) how long does it take for agricultural lands to reach a new SOC equilibrium following land-use change. By substituting space for time and accounting for differences in site properties via stratification, our results challenge the established “slow in, fast out” paradigm. At a national scale, topsoil SOC is lost relatively slowly when grassland is converted to cropland, and gained relatively quickly when cropland is returned to grassland. Further, neither direction of SOC change agreed with the 20 years’ timescales on which current emission reporting and climate mitigation policy is based, and SOC stocks were influenced by land-use changes for more than 100 years.

How to cite: Emde, D., Don, A., Poeplau, C., and Schneider, F.: Long-term impact of land-use change on soil organic carbon in German agriculture, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5703, https://doi.org/10.5194/egusphere-egu23-5703, 2023.

EGU23-5983 | ECS | Orals | ERE1.4 | Highlight

A multi-objective approach to design integrated multi-energy systems for efficient and sustainable decarbonization at the regional level 

Marco Tangi, Simona Ruggeri, Matteo Troncia, and Alessandro Amaranto

The decarbonization of the energy sector is among the highest priorities in the European Union’s effort to reduce its greenhouse gas (GHGs) emissions, avoid the worst effects of rapid climate change, and transition to a more sustainable economy. Multi-energy systems (MESs) have emerged as powerful and flexible solutions to integrate renewable energy sources (RES) in the energy grid and support the decarbonization of heating and transport. In MESs, multiple energy vectors and sectors that are traditionally planned and operated independently like electricity, heating and cooling, fuel and transport are coupled with each other at various levels, from demand to storage and generation, with the aim of increasing the efficiency, resilience, and sustainability of the whole system.  
The transition to carbon-neutral energy systems may come with significant costs, especially in areas where the social and economic opportunities are tied to carbon-intensive activities or where the land-use change to accommodate RES carries significant environmental and social impacts. In these contexts, where multiple stakeholders with competing objectives are involved, multi-objectives modeling tools can be used to support decision-makers in identifying the most suitable technical configuration of MESs to fulfill the decarbonization and economic goals while considering the needs of the territory involved and the assets and resources already available. 
This work presents a novel approach to identifying optimal solutions when designing MES under multiple competing environmental, economic, technological, and social objectives. We use the multi-scale energy systems modeling framework CALLIOPE to simulate the optimal management of a MES with high temporal resolution under a specific system configuration. These configurations are explored via a Multi-objective Evolutionary Algorithm, to extract Pareto-optimal MES designs and highlight synergies and trade-offs between multiple objectives. 
The new framework is applied to the Sulcis Iglesiente (SI) Province in Sardinia, Italy; a territory that already faces severe socio-economic challenges which are at risk of being exacerbated by the planned phase-out of the local coal power plant. Together with the economic end emission targets, the analysis includes objectives such as land-use allocation for renewables, air quality, and local job opportunities and losses. 
The resulting MES configurations, as expected, highlight a strong conflict between the maintenance of the previously carbon-intensive assets and the reduction of GHGs emissions. From the demand side, substituting fossil fuel boilers with heat pumps to exploit the excess electricity production that follows the expansion of the already existing renewable resources pool (mainly via new on-shore wind turbines) represents a good solution to increase efficiency and reduce the overall carbon footprint. However, from the generation side, fully compensating for removing the fossil fuel-based power plant would require massive investment in on-the-ground photovoltaic, and wind turbines (off-shore and on-shore), which may be too costly in terms of investment, surface allocation and landscape degradation. 

How to cite: Tangi, M., Ruggeri, S., Troncia, M., and Amaranto, A.: A multi-objective approach to design integrated multi-energy systems for efficient and sustainable decarbonization at the regional level, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5983, https://doi.org/10.5194/egusphere-egu23-5983, 2023.

EGU23-7116 | ECS | Orals | ERE1.4

Reconciling differences in CO2 emissions and removals from LULUCF by separating natural and land-use CO2 fluxes at the country level 

Clemens Schwingshackl, Wolfgang A. Obermeier, Selma Bultan, Giacomo Grassi, Josep G. Canadell, Pierre Friedlingstein, Thomas Gasser, Richard A. Houghton, Werner A. Kurz, Stephen Sitch, and Julia Pongratz

Anthropogenic and natural CO2 fluxes on land constitute substantial CO2 emissions and removals but are usually not well distinguished in national greenhouse gas inventories (NGHGIs) submitted to the United Nations Framework Convention on Climate Change (UNFCCC). Instead, countries frequently include natural and indirect human-induced CO2 fluxes on managed land in their estimates of CO2 fluxes from land use, land-use change, and forestry (LULUCF), mostly due to methodological constraints. Comparisons of anthropogenic LULUCF flux estimates from global models and from NGHGI reports thus reveal a substantial gap. Globally, this gap could be successfully reconciled by considering the different definitions used by global models and by NGHGI reports. Recent improvements in LULUCF flux modelling enable such a reconciliation now also at the country-level.

We separate natural and land-use-related CO2 fluxes from NGHGI reports in eight countries using global models to assess and improve the attribution of land CO2 fluxes to direct anthropogenic activities. In most investigated countries, the gap between model-based and report-based CO2 flux estimates is reduced (by up to 70%) if natural and indirect human-induced CO2 fluxes on managed land are considered. This confirms that the methodological discrepancies between NGHGI reports and global model estimates of LULUCF emissions are primarily due to differing estimation and reporting definitions, which need to be considered when accounting for country contributions to global climate mitigation targets. Further examinations show that remaining differences are linked to country-specific discrepancies between model-based and report-based estimates, such as incomplete reporting by countries, uncertainties in historical land-use dynamics, and model limitations. Moreover, most countries report the areas considered as managed without explicit information on their location, which prevents a precise spatial identification necessary for a detailed comparison of natural fluxes in managed forests with model-based estimates.

Reconciling estimates of LULUCF fluxes in individual countries by separating natural and land-use-related CO2 fluxes at national scales provides an important step toward a transparent assessment of LULUCF fluxes from NGHGI reports and supports a fair burden sharing of climate mitigation across countries.

How to cite: Schwingshackl, C., Obermeier, W. A., Bultan, S., Grassi, G., Canadell, J. G., Friedlingstein, P., Gasser, T., Houghton, R. A., Kurz, W. A., Sitch, S., and Pongratz, J.: Reconciling differences in CO2 emissions and removals from LULUCF by separating natural and land-use CO2 fluxes at the country level, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7116, https://doi.org/10.5194/egusphere-egu23-7116, 2023.

EGU23-7344 | ECS | Orals | ERE1.4

Mercury Emissions under Different Climate Pathways 

Flora Maria Brocza, Robert Sander, and Peter Rafaj

Global anthropogenic mercury (Hg) emissions are a long-lived hazard to human and environmental health. Targeted efforts to ban anthropogenic uses and trade and other releases of mercury and its compounds are underway through the UN Minamata Convention on Mercury [1]. However, more than half of Hg emissions in 2015 were linked to unintentional release via the combustion of fossil fuels (especially coal) and industrial activities such as metals production. Thus, in addition to mercury-specific policies and interventions, global action on climate change and the accompanying transition in energy systems, as well as the demand for metals and cement are important drivers of future mercury emissions.

The Greenhouse Gas – Air Pollution Interactions and Synergies (GAINS) model is an integrated assessment model that explores cost-effective multi-pollutant emission control strategies which aim at maximizing impacts of improved local and global air quality and emissions abatement. Hg-GAINS, as developed by Rafaj et al. [2] is one of few models which currently represents all anthropogenic mercury emission sources on a sector-by-sector basis. A recent update enhances representation of the co-benefits for mercury emissions from particulate matter (PM) and SO2 controls and extended the representation of Hg-specific control technologies. Climate and energy policy is represented through exogenous inputs into the model.

We quantify the relative importance of climate policy, co-benefits from PM and SO2 controls and technological mercury pollution control measures by comparing six scenarios of global mercury emissions in 5-year steps from 2010 up to 2050. Three energy scenarios from IEA World Energy Outlook 2022 (A - “Stated Policies (STEPS)”,  B - “Advanced Pledges (AP)”,  C - “Net Zero Emissions (NZE)”  [3]) are combined with two strategies of mercury emission control (1 - Current Legislation (CLE) , assuming technical mercury control compliant with the Minamata convention and national emission standards, relying mainly on co-benefits from PM and SO2 control; 2 - Maximum Feasible Reduction (MFR), assuming utilisation of the most efficient Hg-specific technologies and measures across all sectors). The share of Hg emissions from fossil fuel combustion is decreasing significantly in the Net Zero scenario (NZE-CLE) by 2050. Additionally, stringent air pollution policy reduces Hg emissions from this sector globally in all energy CLE scenarios. However, material and metal demand, driven by the deployment of renewable energy, as well as population growth both lead to a net increase of Hg even in NZE-CLE, which can only be resolved by applying stringent MFR controls for mercury (NZE-MFR).


[1] UNEP (2019). Minamata Convention on Mercury. Text and Annexes. www.mercuryconvention.org.

[2] Rafaj, P., Bertok, I., Cofala, J., and Schöpp, W. (2013). Scenarios of global mercury emissions from anthropogenic sources. Atmospheric Environment, 79:472–479.

[3] International Energy Agency (2022). World Energy Outlook 2022.

How to cite: Brocza, F. M., Sander, R., and Rafaj, P.: Mercury Emissions under Different Climate Pathways, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7344, https://doi.org/10.5194/egusphere-egu23-7344, 2023.

EGU23-9861 | ECS | Orals | ERE1.4

Improving LULUCF carbon emissions/removals estimates for Flanders, Belgium, through high-resolution prediction of land use based on a machine learning approach 

Ellen Van De Vijver, Dries Luts, Joris Pieters, Kasper Cockx, Peter Willems, and Stijn Vanacker

The quality of national and regional estimates of carbon emissions/removals under the LULUCF sector directly depends on the quality of the used input data for land use and land use changes, and their associated carbon stocks and emission/removal factors. The increasingly strict European regulations for greenhouse gas (GHG) emission reporting and the growing importance of the LULUCF sector in climate action plans and policies provide clear incentives to strive for continuous improvement of LULUCF datasets, including their spatial and temporal resolution.

The region of Flanders, Belgium, is characterized by relatively heterogeneous land use, which is monitored at a high spatial resolution resulting in the triennial production of a detailed land use map (18 categories, raster map with cell size of 10 by 10 meters). However, the estimation of LULUCF carbon emissions/removals currently relies on a different, less detailed land use dataset (5 categories, regular grid of 6799 points each representing an area of approximately 2000 by 1000 meters). The use of the latter dataset is motivated by the adoption of a similar approach over the three regions of Belgium, to guarantee the consistent integration of regional carbon emissions/removals estimates into the national GHG inventory. Apart from the general limitations of a sample-based dataset, this LULUCF land use dataset provides insufficient detail to grasp the effect of LULUCF-related policies and measures, undermining the use of derived carbon emissions/removals estimates for policy evaluation and development at the level of Flanders.

To overcome the issues related with spatial (and temporal) resolution of the current LULUCF land use dataset, we tested a machine learning approach to integrate four more detailed data sources available for Flanders in order to predict the corresponding LULUCF land use at a resolution of 10 meters. More specifically, we used the land use file, the land use map, the land cover map, and the dataset of registered agricultural parcels as input data in a multinomial logistic regression, considering a search neighbourhood with a 10-m radius around an original LULUCF land use data point. The model was created based on input data for two years, namely 2012 and 2015. Of the original LULUCF dataset, 70% of the data points was used for training of the model, leaving 30% for validation. In a first test, a prediction accuracy of approximately 90% was achieved. After manual correction of the original LULUCF dataset, the accuracy improved to 94%.

Although the approach proved successful for the prediction of the LULUCF land use for the individual years considered, less satisfying results were found when using the predictions to derive the land use change between these years: a land use change was estimated to occur at 8% of the total area of Flanders, while this was only 2% and 4% based on the original dataset before and after manual correction. Considering the major significance of the land use change area in the estimation of carbon emissions/removals, further research is required to adjust the methodology in order to guarantee the prediction of a consistent land use time series.

How to cite: Van De Vijver, E., Luts, D., Pieters, J., Cockx, K., Willems, P., and Vanacker, S.: Improving LULUCF carbon emissions/removals estimates for Flanders, Belgium, through high-resolution prediction of land use based on a machine learning approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9861, https://doi.org/10.5194/egusphere-egu23-9861, 2023.

EGU23-10215 | ECS | Posters virtual | ERE1.4

Forest Restoration Potential in China: Implications for Carbon Capture 

Xin Jiang

When it comes to mitigating the damaging effects of deforestation and the adverse effects of rising carbon dioxide concentrations in the atmosphere, reforestation is an environmentally responsible and effective strategy. China, which has one of the most significant rates of afforestation in the world, has increased its forest cover from 16.6% when it was last measured twenty years ago to 23.0% when it is next measured in 2020. However, there is uncertainty regarding the maximum potential forest coverage that can be achieved through tree planting and restoration. We developed a random forest regression model to map the potential tree coverage across China. The model links environmental factors with the types of forests that are most appropriate. After removing already-forested areas, urban areas, and agricultural land covers and uses, we estimate that there is a total of 67.2 million hectares of land that is currently available for tree restoration. This is a 50% increase over the current understanding of the available land. The establishment of a forest on these lands would result in the creation of 3.99 gigatons of new carbon stocks both above and below ground, which would be an important contribution toward the goal of reaching carbon neutrality. This potential is geographically unbalanced, with the largest restorable carbon potential being located in the south-west (29.5%), followed by the north-east (17.2%), and then the north-west (16.8%). The results of our study highlight the importance of coordinating the planting of trees in reforestation efforts with the uneven distribution of potential carbon storage. Reforestation should provide other environmental services in addition to acting as a biological mitigation strategy to partially offset carbon dioxide emissions caused by the burning of fossil fuels. These services include the restoration of degraded soils, conservation of biological diversity, revitalization of hydrological integrity, localized cooling, and improvement in air quality. Instead of concentrating solely on the act of planting trees, we believe it is more beneficial for forest restoration efforts to concentrate on the ecosystem as a whole rather than just the trees themselves.

How to cite: Jiang, X.: Forest Restoration Potential in China: Implications for Carbon Capture, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10215, https://doi.org/10.5194/egusphere-egu23-10215, 2023.

Expansion of a development area can have a negative impact on ecosystems by decreasing or fragmenting habitats. As awareness of the importance of biodiversity and ecosystem services grows, ecosystem service evaluations are receiving increased attention. The geography surrounding the city of Incheon is ecologically valuable because its mudflats and coastal terrain make it ecologically diverse. It is a wildlife habitat and breeding site for endangered species as designated by the Ramsar Convention on Wetlands in 2014, and the subject of disputes between advocates of ecological protection and those favoring human development. This study used the InVEST model to analyze the changes in the ecosystem services in accordance with the agreement on the IFEZ. An analysis showed that the carbon fixation was reduced by 40% due to the development led by the agreement, leading to a decrease in carbon storage of 793,586.25 Mg of C. This study suggests that the value of ecosystem services and expansion of conservation areas should be considered as part of ecological research under economic free trade agreements. Lastly ecological changes associated with IFEZ designation should be examined, and maintenance and management of carbon storage to restore climate controls and the valu-ation of biodiversity should be considered by developers and government officials.  In the natural environment ecology the EIA for development, biodiversity, dominance, natural environment, cultural assets, and protected species are investigated. It is judged that it will be a meaningful study by applying the quantitative evaluation methodology of ecosystem services for the planned development area. Afterwards, it is judged that it can be used as basic data in making development pol-icy decisions through qualitative and quantitative evaluation along with other environ-mental fields by utilizing ICT and AI methods, which are related methodologies according to the 4th industrial revolution.

How to cite: Choi, J. and Lee, D. K.: Analysis of spatio-temporal carbon fixation change in Incheon, Korea, as a result of free trade Agreement, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10316, https://doi.org/10.5194/egusphere-egu23-10316, 2023.

EGU23-11668 | ECS | Posters on site | ERE1.4

The Hot Spot analysis of Land use and Land cover changes (LULCC) in South Korea and North Korea 

Whijin Kim and Woo-Kyun Lee

Land use and land cover changes (LULCC) as a part of ecosystems has a significant impact on carbon budget. According to IPCC, approximately 23% of carbon was emitted from the human activities in agriculture, forestry and other land use (AFOLU) from 2007 to 2016. However, land cover includes crucial sector for carbon stock, as well. The land cover consists of five categories which are used area, agricultural land, forest, grass, wet land, and barren. Among these categories, forest counts because of its capacity of carbon sequestration. It is essential to manage the land use and land cover changes effectively since it has lots of influences on carbon cycles. Also, the sustainable management of land use and land cover changes could contribute to reducing the carbon emissions such as preventing deforestation and revegetation. Therefore, this study aims at analyzing the frequent land use change region using hot spot analysis in South Korea and North Korea and estimating the carbon emission and removals from land cover changes. First of all, we tracked the land cover changes at 10 years interval from 1980s to 2010s and identified the general trends. The changed area and ratio of each land cover were varied in both countries, but they had similar characteristics which is land cover changes from forest to cropland and from cropland to forest. It occurred for last four decades. To define the which region has been changed, the hot spot analysis was utilized. The change from forest to cropland appeared in southwest region of North Korea, major agriculture land. On the other hand, the transition from agriculture land to forest seemed to be minor, but the distinguished figure was created during the 2000s to 2010s change. The carbon emission was estimated at the hot spot area and these repeated changes led to additional carbon emission. This study would contribute to preventing the land cover changes frequent by defining the region to be managed.

How to cite: Kim, W. and Lee, W.-K.: The Hot Spot analysis of Land use and Land cover changes (LULCC) in South Korea and North Korea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11668, https://doi.org/10.5194/egusphere-egu23-11668, 2023.

EGU23-12710 | ECS | Orals | ERE1.4

Eddy covariance CO2 flux data for supporting local climate change mitigation policies. 

Luca Tuzzi, Marta Galvagno, Gianluca Filippa, Edoardo Cremonese, Alessio Collalti, Luca Franzoso, Enrico Tomelleri, Riccardo Scodellaro, Laura Sironi, and Roberto Colombo

Under the Paris Agreement, countries are encouraged to preserve and enhance existing carbon sinks, especially forests, thereby including the LULUCF (Land Use, Land Use Change and Forestry) sector in international climate mitigation targets. In particular, Europe has set the target to reach climate neutrality, i.e. a balance between anthropogenic emissions by sources and removals by sinks, by 2050. A prerequisite to reach these goals is an accurate and credible estimation of both these large fluxes. However, recent works highlighted the uncertainty related to the quantification of the land sector mitigation potential, one of the most challenging emission sectors. Moreover, the definition of climate mitigation policies often occur at the local level, where details on CO2 removals from forests and other land uses are traditionally lacking. Indeed, local authorities  (e.g. cities and Regions) can be more effective in the transition to a sustainable economy compared to higher level authorities such as Nations.

In this study, we tested a data-driven method based on eddy covariance (EC) data to quantify the current LULUCF role to the regional carbon sink of the Aosta Valley Region (Italy), by the integration of different approaches. Our model is based on eddy covariance measurements of CO2 fluxes, MODIS NDVI (250m), daily gridded meteorological variables at 100m spatial resolution, and a land cover map at 250m spatial resolution. A Random Forest model was used to up-scale the point eddy covariance data to the Regional level, by testing different sets of drivers (air temperature, VPD, Snow (presence/absence), NDVI, solar radiation,...). Our model was then compared to independent data derived from the National Forest Inventory (NFI), and a process-based model. Preliminary results show that forests and other ecosystems of the Region remove nearly 70% of the total anthropogenic emissions in this area. The discrepancies between the different methods will be discussed by exploring the different advantages and flaws and the spatio-temporal variability of the different approaches. Such an assessment of the local carbon budget and its uncertainties will provide a solid base for Climate-smart management of the territory and thus for reaching the carbon neutrality targets.

How to cite: Tuzzi, L., Galvagno, M., Filippa, G., Cremonese, E., Collalti, A., Franzoso, L., Tomelleri, E., Scodellaro, R., Sironi, L., and Colombo, R.: Eddy covariance CO2 flux data for supporting local climate change mitigation policies., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12710, https://doi.org/10.5194/egusphere-egu23-12710, 2023.

EGU23-13952 | ECS | Posters on site | ERE1.4

Comparison of the Life Cycle Analysis of inert electrodes and the Hall-Heroult process in aluminum production 

Bethany Bronkema, Gudrún Sævarsdóttir, and David C. Finger

Comparison of the Life Cycle Analysis of inert electrodes and the Hall-Heroult process in aluminum production

 

Bethany Bronkema bethanyb@ru.is Guðrún Arnbjörg Sævarsdóttir gudrunsa@ru.is

David C. Finger davidf@ru.is

 

To be presented orally at EGU2023 – April 23rd-28th.

  • Reykjavik University, School of Science and Engineering, Department of Engineering, Reykjavik, Iceland

 

The global production of pure aluminum consumes substantial amounts of energy and alone produces around 1.1 billion metric tonnes of carbon dioxide emissions (CO2, eq) each year, or around two percent of global emissions. The Hall-Heroult process is currently the only industrial process for primary aluminum production, producing up to two tonnes of CO2 per tonne of pure aluminum by electrolysis in a molten salt electrolyte using carbon anodes. However, the use of inert electrodes represents a low-carbon alternative to the Hall-Heroult process as direct emissions can be significantly reduced, lowering the CO2, eq footprint and the ecotoxicity of aluminum production. However, a transition to inert anodes implies a redesign of current electrolysis cells to optimize the energy requirement of the new process. In this study, we performed a life cycle analysis to compare the ecological footprint of the aluminum production process with inert electrodes and the Hall-Heroult process. The life cycle assessment was conducted using GaBi software linked to the ecoinvent database and complemented with primary data. We calculated the ecological footprint for five scenarios: i) using inert electrodes with a 13.5 kWh per kilogram of aluminum energy requirement, ii) using a 17 kWh per kilogram of aluminum energy requirement, iii) using Icelandic grid electricity (primarily renewable hydropower), iv) using a global energy mix (primarily based on fossil energy), and v) and “best case scenario” in which a renewable source of energy is assumed for the refinement stage preceding the smelting stage. Each of these scenarios were then compared with the ecological footprint for the Hall-Heroult process using carbon anodes. The preliminary results reveal that the energy mix always has the highest impact on the ecological footprint in the earlier refinement and electrolysis stages. However, using inert electrodes in smelters powered with renewable electricity can significantly lower the carbon footprint and ecotoxicity of aluminum production.

How to cite: Bronkema, B., Sævarsdóttir, G., and Finger, D. C.: Comparison of the Life Cycle Analysis of inert electrodes and the Hall-Heroult process in aluminum production, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13952, https://doi.org/10.5194/egusphere-egu23-13952, 2023.

EGU23-14564 | ECS | Orals | ERE1.4

Historical and future perspectives of agricultural land abandonment and carbon sequestration 

Stephen M. Bell, Alexander V. Prishchepov, Calogero Schillaci, Daniel Goll, and Philippe Ciais

For as long as agriculture has existed, agricultural land abandonment (ALA) has been a globally relevant land use change. Depending on the timescale considered and the definitions and methods used, spatial estimates of historical ALA range in the several hundreds of millions of hectares. ALA implies the spontaneous recovery of ecosystem properties towards pre-disturbance states. Because agricultural lands are often degraded and carbon depleted, the natural ability of abandoned agricultural lands to act as carbon sinks has been, and will continue to be, a significant component of the terrestrial carbon cycle. Here, we provide a brief snapshot of the history of ALA, its drivers, and its known ecosystem carbon impacts from ancient times to the present, especially since the mid-20th century. We then explore the current and future implications of ALA-derived carbon sequestration in Europe, focussing on soil organic carbon based on synthesized published data (chronosequences and paired plots) and land surface model estimates. The majority of abandoned agricultural lands serve as carbon sinks, but there are clear scenarios where carbon may be lost or unchanged even after several years post-agriculture. Our results show that management of abandoned agricultural lands must consider multiple factors such as past land use practices (e.g., croplands vs pastures, past crop types, etc.), future land use management practices (e.g., natural or assisted restoration), local climate variables, and the present soil quality and carbon stock to ensure steady carbon sequestration following agricultural cessation. To avoid lost opportunities for climate change mitigation, ALA requires dedicated research and policy attention because: 1) it is a widespread, ongoing global land use change; 2) it does not always result in carbon sequestration; 3) its carbon gains are often lost in the first few decades when agriculture is re-established; 4) and it can facilitate wildfires which can also reverse carbon gains.

How to cite: Bell, S. M., Prishchepov, A. V., Schillaci, C., Goll, D., and Ciais, P.: Historical and future perspectives of agricultural land abandonment and carbon sequestration, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14564, https://doi.org/10.5194/egusphere-egu23-14564, 2023.

EGU23-14986 | ECS | Orals | ERE1.4

The relationship  between spatial variation of greenhouse gases intensity and agri-environmental variables in Oil Palm plantations 

Lisma Safitri, Marcelo Galdos, Andy Challinor, and Alexis Comber

Oil palm (OP) plantations account for 1.7 % of global CO2 emissions. Numerous studies have focused primarily on greenhouse gas (GHG) emissions from peatlands, constituting 20% of total OP area in the two largest OP producing countries, Indonesia and Malaysia. Few studies have investigated the potential for reducing GHG emissions in OP plantations. Strategies to reduce emissions and sequester carbon must consider how different practices affect production and the environment. Understanding the spatial distribution of GHG intensity and how the environment affects GHG intensity is therefore key to sustainable oil palm production.

GHG intensity was used as a metric to map the potential for sustainable OP plantations. GHG intensity represents the GHG emissions / removals (ton C ha-1) per unit of oil palm yields (ton ha-1). The approach for analysing the change in GHG emissions/ removals, referred to as the IPCC tier 1 method, is based on changes in soil organic carbon due to C and N emissions in drained peatlands and the associated change in aboveground biomass due to land use change. Changes in GHG intensity were investigated spatially for a case study in an industrial OP plantation located in Riau Province, Indonesia, from 2015 to 2019. Linear regression was used to analyse the relationships between GHG intensity and agri-environmental variables including NDVI, NPP, GPP, evapotranspiration, soil moisture in the root zone, soil moisture in deeper layer, C and N emissions from organic soils, and soil organic carbon (SOC).

The results show that around 90% of the new oil palm plantations in 2019 were converted from timber plantation, swamp scrubland, and bare land in 2015. Consequently, biomass growth from land use change acted as a carbon sink in this period. However, drained organic soils contributed significantly to GHG emissions. The change in GHG intensity in OP plantation in this study varied spatially from emitting (0.19 to 4.10 Ton C eq Ton-1 yields) to removing the GHG (0.23 to 2.40 Ton C eq Ton-1 yields). Among the environmental variables, NDVI and soil moisture showed the strongest relationship with GHG emissions/ removals (R2 = 0.23,   p value = < 2.2e-16) and yields (R2 = 0.2   p value = < 2.2e-16) in OP plantations.

These initial findings are advantageous for spatially identifying potential OP plantations that remove or emit GHG. Understanding the relationship between GHG emissions/removals and yields to environment variables provides insight into monitoring and enhancing OP sustainability, both from production and environmental perspectives. Future work will examine non-linear approaches to better model this relationship. 

 

 

How to cite: Safitri, L., Galdos, M., Challinor, A., and Comber, A.: The relationship  between spatial variation of greenhouse gases intensity and agri-environmental variables in Oil Palm plantations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14986, https://doi.org/10.5194/egusphere-egu23-14986, 2023.

EGU23-15110 | ECS | Orals | ERE1.4

Maximizing Ecosystem Services through Grassland Restoration and Adaptive Management in Solar Parks 

Mirjam Blecha, Michael Obriejetan, and Rosemarie Stangl

Keywords: Renewable energy, photovoltaics (PV), ecological restoration, ecosystem services, management strategies

The drive for renewable energy has resulted in a heightened focus on expanding sustainable energy systems, with solar PV playing a crucial role in this transition. While large-scale solar parks are met with controversy due to potential land-use conflicts and negative effects on the environment, they also present an opportunity for multifunctional land use. To address these concerns, an integrated research project in Austria was launched to develop strategies for integrating solar parks ecologically and maximizing ecosystem services through grassland restoration and adaptive management. Additional data and analysis will be used to improve the ecological integrity and biodiversity of solar parks and explore opportunities for combined agricultural use. By focusing on expanding renewable energy systems, solar PV in particular, and developing strategies for integrating them ecologically, we can address the global climate crisis and species extinction while also creating systems that are beneficial for both the environment and society in the long term.

However, specific and local conditions of solar parks must be considered in implementation and management. A monitoring system was set up to continuously record data on vegetation, local climate, and soil conditions, including measurements of soil water content, solar radiation, vegetation height, and plant species. Preliminary results show distinct effects of panel areas on several environmental factors, with the greatest impact on radiation and air temperature, also impacting the species composition in the area beneath and between panels.

How to cite: Blecha, M., Obriejetan, M., and Stangl, R.: Maximizing Ecosystem Services through Grassland Restoration and Adaptive Management in Solar Parks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15110, https://doi.org/10.5194/egusphere-egu23-15110, 2023.

EGU23-15480 | ECS | Posters on site | ERE1.4

Water limits to curb climate change through large scale afforestation in the tropics and impacts on water availability for food production 

Livia Ricciardi, Paolo D'Odorico, Nikolas Galli, Davide Danilo Chiarelli, and Maria Cristina Rulli

Tree restoration plays a key role in curbing climate change by storing carbon. However, the impacts these strategies have on water resources is still unclear. While more and more areas are afforested every year, the extent to which these trees can grab rainwater and displace it from other uses while inducing water scarcity should be further investigated. Here, we examine the hydrological limits to tree restoration in tropics and the impacts of these strategies on water availability locally and downstream. We consider tropical biomes as case study since water is the main limiting factor to plant growth there. First, we use the spatially distributed agro-hydrological model WATNEEDS to evaluate the tree water requirement in suitable and available areas for tree restoration at pixel scale. Available areas for tree restoration are shrub areas not yet occupied by agricultural purposes or urbanization. Then, we compute the hydrological balance for different land use scenarios starting from present conditions (i.e., current land use) to tree restoration with and without yield gap closure (i.e., expansion of irrigation on currently rainfed areas).

We find that more than one third of suitable and available areas for tree restoration are in zones at high water stress for the plant, where rain alone can meet just up to the 40% of plant water requirement. Here, tree restoration causes substantial increase in water scarcity conditions, especially in the Horn of Africa and in Oceania. When accounting for both tree restoration and agricultural yield gap closure, water scarcity on these areas is exacerbated. Here, more than half of suitable and available areas for tree restoration will experience water scarcity conditions for at least six months per year.

It appears clear how competition for water resources reduces the benefits of tree restoration practices as plant growth is overall constrained by the lack of water.

How to cite: Ricciardi, L., D'Odorico, P., Galli, N., Chiarelli, D. D., and Rulli, M. C.: Water limits to curb climate change through large scale afforestation in the tropics and impacts on water availability for food production, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15480, https://doi.org/10.5194/egusphere-egu23-15480, 2023.

EGU23-16644 | ECS | Orals | ERE1.4

Assessing the impact of electric four-wheelers on the environment 

Anmol Jain, Eeshan Bhaduri, and Arkopal Kishore Goswami

According to the United Nations Environment Programme (UNEP), the transportation sector contributes approximately one-quarter of all energy-related greenhouse gas emissions. The increasing use of personal vehicles (PVs), especially conventional fuel-based four-wheelers, is significantly worsening the air quality index (AQI). Furthermore, the COVID-19 pandemic, during which social distancing was promoted as a preventative measure, has increased the propensity of PV use. As such, efforts to decarbonise transport have to be emphasised, wherein the adoption of electric vehicles (EVs) could play a crucial role. It is worth mentioning that European Union has been the global frontrunner for EV adoption with about 20% of its new vehicle stock being electric, while India is bridging the gap fast with its respective EV share being nearly 11%.

However, EVs per se might not be able to bring about changes in the existing scenario, as a substantial share of the electricity demand is met (for example, more than half of India’s production) through non-renewable energy sources. In such a situation, higher adoption of EVs would lead to increased demand for electricity, resulting in more emissions from thermal power plants, thus offsetting the reductions in tailpipe emissions. As such, this study analyses the environmental benefits of electrifying the passenger 4-wheeler transport sector by - (1) optimising the share of renewable energy sources (RES) and (2) facilitating higher shared usage of electric vehicles. While the existing studies largely focus on ownership and usage aspects of personal-use EVs, very few estimates the impact of the transition of different passenger commercial EV fleets and their emission implications for various RES utilisation. The present research aims to empirically assess demand for car-based travel alternatives (personal car, ride-hailing/ sharing, and taxi) while illustrating plausible electrification scenarios, considering emissions at sources. Such emissions are estimated through life cycle assessment (LCA) of vehicle operations and at power generation sources, i.e., thermal power plants. The current study considers vehicle level LCA including majorly three stages- (1) manufacturing, (2) operation, and (3) decommissioning-recycling, whereas the LCA at power generation sources was carried out at four stages- (1) upstream, (2) fuel cycle, (3) powerplant function and (4) downstream. This approach aids in developing a comparable emission estimate for EVs vis-à-vis conventional vehicles. At the same time, it presents a true view of EV’s emission reduction potential incorporating the RES transition effect.  

Data regarding user behaviour and choice towards the aforementioned four-wheeler-based alternatives have been collected using questionnaire surveys in Kolkata, India, and a multinomial logit model is developed. Subsequently, the model is used to develop scenarios for estimating the likely effects of electrification on travel choices. Finally, the LCA method, including exergy analysis and battery degradation, is used to calculate the impact of such travel choices on energy use and decarbonisation. The study is expected to provide empirical evidence for the viability of EV deployment in India and the benefits of switching to EVs with an increased share of RES in power generation.

Keywords: Electric vehicle (EV); Vehicular emissions; Lifecycle assessment (LCA); Renewable energy sources (RES)

How to cite: Jain, A., Bhaduri, E., and Kishore Goswami, A.: Assessing the impact of electric four-wheelers on the environment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16644, https://doi.org/10.5194/egusphere-egu23-16644, 2023.

EGU23-17078 | ECS | Orals | ERE1.4 | Highlight

Trade-off scenarios in energy transition: The impact of social preferences and ecosystem services 

Boris Salak, Marcel Hunziker, Adrienne Grêt Regamey, Reto Spielhofer, Ulrike Wissen Hayek, and Felix Kienast

The siting of large energy facilities is a major challenge in countries where environmental and landscape issues related to outdoor recreation, place attachment, or tourism are publicly discussed, as the choice of the "optimal" location always depends on perspective. To allow informed decisions by policy makers, landscape research should provide data on current and potential future land use, public perceptions of landscapes and energy infrastructure etc. Decision support tools can convey this information to end users and help them to mimic tradeoffs between landscape issues and renewable energy development. However, these trade-offs often focus on techno-economic aspects and ignore environmental and social aspects. In this presentation, an optimization technique (MARXAN) is applied to mimic siting of renewable energy in Switzerland. Each potential energy site has costs in terms of ecosystem services and social preferences. MARXAN optimizes the selection of these sites to produce a given energy output at the lowest cost. It is shown that when focusing on the (often) common techno-economic approach, ecological costs peak while social costs are moderate compared to ecologically and socially oriented siting strategies. When siting incorporates ecosystem service costs, both spatial stress (claimed square kilometers of landscape for renewable energy infrastructure development) and social impacts peak, and when social costs are incorporated, both spatial and ecosystem service impacts turn out to be quite moderate. The results highlight the implications of a potential paradigm shift by showing the impact of integrating ecological and social information to provide informed decision support.

How to cite: Salak, B., Hunziker, M., Grêt Regamey, A., Spielhofer, R., Wissen Hayek, U., and Kienast, F.: Trade-off scenarios in energy transition: The impact of social preferences and ecosystem services, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17078, https://doi.org/10.5194/egusphere-egu23-17078, 2023.

EGU23-17242 | ECS | Orals | ERE1.4

Mapping peat layer thickness using machine learning and aerial laser scanning data 

Janis Ivanovs and Andis Lazdiņš

The surface of the earth's surface together with the granulometric composition of the soil are among the main parameters that determine the flow and accumulation of surface and underground water. Poorly drained and wet soils are important for biodiversity, water exchange, various chemical and biological processes, as well as for organic carbon accumulation. This research was done within the framework of the project Demonstration of climate change mitigation potential of nutrients rich organic soils in Baltic States and Finland (OrgBalt) and its purpose is to map the thickness of the organic layer on a national scale for the territory of Latvia. The mapping was done using machine learning methods and NFI sample plot data on peat layer thickness, ALS laser scanning data and other additional data were used as training data. As a result, a raster map was obtained, which depicts the depth of the peat layer in three different classes - No peat, peat layer thickness from 1 to 20 cm and peat layer thickness more than 20 cm. The accuracy of the machine learning classification algorithm reaches 0.88, while the kappa value is 0.74. Separately by different classes, the sensitivity of the model is 0.94 for the first class, 0.63 for the second class and 0.81 for the third class.

How to cite: Ivanovs, J. and Lazdiņš, A.: Mapping peat layer thickness using machine learning and aerial laser scanning data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17242, https://doi.org/10.5194/egusphere-egu23-17242, 2023.

Reliable determination of the soil organic carbon stock (SOCS) and its time trend at field scale is a key condition to value soil organic carbon (SOC) sequestration as a negative emission technology (NET) at farm level. Limiting the stock estimation to 30 cm depth is acceptable on the range of some decades (Balesdent et al., 2018). The carbon stock, however, is not directly estimated from the SOC content. SOC content must be multiplied by the bulk density (BD) of the corresponding layer. BD determination is time consuming and tedious to determine, and changes with time due to soil swelling with water, soil tillage, and changes in SOC. Therefore, the changes in SOCS must be monitored on an equivalent soil mass (ESM) basis, by referring to the sampled soil mass of the previous sampling rather than to a constant depth layer. Corrections of the mass, simplification of the soil mass determination overcoming the BD determination issue, as well as a simplified one-layer method have been proposed (Wendt and Hauser, 2013). However, this simplified ESM method requires the sampling and analysis of at least two layers for sampled mass correction. Moreover, the field volume percentage of the coarse (> 2 mm) fraction must be determined and removed from the sampled layer volume, which is not well documented. On the other hand, and to our best knowledge, private companies providing SOCS certificates sample the soils at constant depth using mechanical gauges that do not allow to control the quality of the extracted core. Finally, the errors associated with these different technical options needs to be clarified.

This study was performed using samples collected in 60 fields from different farms of the Swiss Leman-Lake region. It aimed at providing a full reliable methodology to determine SOCS at field scale, while solving the remaining issues, namely to determine the errors associated to the different parameters estimated and to simplify the ESM one-layer method to decrease the sampling and analytical costs. The minimum detectable change was determine (i) for sampling performed using the mechanical gauges at constant depth, (ii) for the ESM one-layer method as described in (Wendt and Hauser, 2013), (iii) the additional error introduced by coarse fraction estimation and gauge diameter and (iv) a simplification of the one-layer ESM method taking into account local average properties of the soil below the 0-30 cm sampled layer.

How to cite: Boivin, P. and Lemaître, T.: Determination of carbon stocks in arable land: errors, improvement of the one-layer equivalent soil mass method and associated minimum detectable change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17576, https://doi.org/10.5194/egusphere-egu23-17576, 2023.

China has promised that CO2 emissions per GDP in 2030 would decrease by 60% to 65% than that in 2005, and proposed the goal of achieving carbon neutral by 2060. In order to fulfill these goals, Carbon Emissions Trading (CET) and Tradable Green Certificates (TGC) have been implemented in the power industry during the ‘13th five-year’ period. We firstly simulate the combined effects of TGC and CET on the electricity market from 2020 to 2026. Further, we build a policy synergy model to explore the optimization relationship between TGC and CET systems. The results show that, the power supply structure can be optimized under TGC and CET systems. The growth rate of CO2 emissions from the power industry will slow down, accelerating peaking CO2 emissions of the power industry. The national CO2 emissions reduction goal (1.185–1.037 tons /RMB 10,000 yuan by 2030) is expected to be achieved. There may be policy redundancy between TGC and CET systems. It is determined by how to set renewable energy objective and CET quota objective. Under multiple policy objectives, the key is to obtain the policy synergy intervals for staged optimization. Finally, we propose some suggestions on the improvement of TGC and CET mechanisms, and combined implementation and optimization of multiple emission reduction policies.

How to cite: Feng, T.: Induction mechanism and optimization of tradable green certificates and carbon emission trading acting on electricity market in China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1993, https://doi.org/10.5194/egusphere-egu23-1993, 2023.

Energy system analysis has been widely used to imply technologically and economically plausible energy-system transition pathways for national net-zero emissions targets. Undermining the feasibility of such energy system analysis results are the highly-resolved mapping, sector-by-sector, of the timing and spatial distribution of changes in energy infrastructure, capital investment, employment, air pollution, land use, and other key outcomes at local level. A successful net-zero transition must be accomplished with supplementary supply of factors of production (e.g., human capital, natural capital, investment etc.) to enable such low-carbon transition. Using Princeton’s net-zero America study as example, we find that each net-zero pathway results in a net increase in energy-sector employment and delivers significant reductions in air pollution, leading to public health benefits that begin immediately in the first decade of the transition. We also conclude that each transition pathway features historically unprecedented rates of deployment of multiple technologies. Impacts on landscapes, incumbent industries and communities are significant and planning will need to be sensitive to regional changes in employment and local impacts on communities.

How to cite: Zhang, C.: Linking energy system analysis with factors of production analysis: A US case study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3084, https://doi.org/10.5194/egusphere-egu23-3084, 2023.

EGU23-3817 | ECS | PICO | ERE1.5

The carbon cost of mitigating air pollutant emissions from coal-fired power plants in China 

Pengfei Zhang, Kuishuang Feng, Li Yan, Yaqin Guo, Bei Gao, and Jiashuo Li1
  • With the largest pollution-intensive coal-fired power plant (CFPP) fleet in the world, China has widely distributed air pollutant control devices (APCDs) to improve air quality. These APCDs are effective in mitigating air pollutants, at the same time, consume substantial carbon-intensive electricity from CFPPs. Nevertheless, the carbon cost of clean coal-fired power remains unexplored. Therefore, by collecting plant-level information, we quantified CO2 emissions induced by APCDs’ power consumption from China’s CFPPs. We show that from 2000 to 2020, CO2 emissions induced by APCDs in China’s CFPPs increased from 1.48 Mt to 51.7 Mt, and the ratio of power consumed by the APCDs to the total power generation increased from 0.12% to 1.19%. In 2020, the wet limestone-gypsum flue gas desulfurization device dominated the carbon emissions with a percentage of 80%, followed by the dust removal device’s 13% and denitration device’s 7%, respectively. Scenario analysis demonstrates that Inner Mongolia, Shanxi, and Shandong are the hotspots of APCD CO2 emissions in the future. The lifetime of CFPPs is an important factor affecting the scale of future APCD CO2 emissions. Our study underscores the urgency of a comprehensive assessment of environmental policies and urges the necessity of synergetic management of air pollutants and carbon emissions.

How to cite: Zhang, P., Feng, K., Yan, L., Guo, Y., Gao, B., and Li1, J.: The carbon cost of mitigating air pollutant emissions from coal-fired power plants in China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3817, https://doi.org/10.5194/egusphere-egu23-3817, 2023.

EGU23-4023 | ECS | PICO | ERE1.5 | Highlight

Tracing metal footprints through global renewable power value chains 

Rao Fu, Kun Peng, Peng Wang, Honglin Zhong, Xi Liu, Kuishuang Feng, and Jiashuo Li

The globally booming renewable power industry has stimulated an unprecedented interest in metals as key infrastructure components. Many economies with different endowments and levels of technology participate in various production stages and cultivate value in global renewable power industry production networks, known as global renewable power value chains (RPVCs), complicating the identification of metal supply for the subsequent low-carbon power generation. Here, we use a value chain decomposition model to trace the metal footprints (MFs) and value-added of major global economies’ renewable power sectors. We found that the MFs of the global renewable power sector increased by 47% during 2005—2015. Developed economies occupy the high-end segments of RPVCs while allocating metal-intensive (but low value-added) production activities to less developed economies. The fast-growing demand for renewable power in developed economies is a major contributor to the embodied metal transfer increment within RPVCs, which is partly offset by the declining metal intensities in less developed economies. Therefore, it is urgent to establish a metal-efficient and green supply chain for upstream suppliers as well as downstream renewable power installers for transition in the power sector across the globe.

How to cite: Fu, R., Peng, K., Wang, P., Zhong, H., Liu, X., Feng, K., and Li, J.: Tracing metal footprints through global renewable power value chains, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4023, https://doi.org/10.5194/egusphere-egu23-4023, 2023.

EGU23-4171 * | PICO | ERE1.5 | Highlight

Material footprint assessment of hydropower plants 

Ling Shao, Yunlong Pan, Yuwen Chu, and Zi Wu

Hydropower is the largest renewable source of electricity generation. However, the construction and operation of hydropower plants may cause significant material footprints. This study provides a systems accounting framework for evaluating the life-cycle material footprint of a hydropower plant. It is based on the hybrid method as a combination of the process analysis and the input-output analysis. A case study for a typical pumped storage hydropower plant (NPSHP) is carried out to demonstrate the framework. 12 metals (bauxite and aluminum ores, copper ores, gold ores, iron ores, lead ores, nickel ores, PGM ores, silver ores, tin ores, uranium and thorium ores, zinc ores, and other non-ferrous metal ores) and 8 minerals (building stones, chemical and fertilizer minerals, clays and kaolin, gravel and sand, limestone & gypsum & chalk & dolomite, salt, slate, and other minerals) are included.  The results can be helpful to promote a sustainable energy transition by incorporating material planetary boundaries into renewable energy systems.

How to cite: Shao, L., Pan, Y., Chu, Y., and Wu, Z.: Material footprint assessment of hydropower plants, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4171, https://doi.org/10.5194/egusphere-egu23-4171, 2023.

Low-carbon power transition, key to combatting climate change, brings far-reaching effects on achieving Sustainable Development Goals (SDGs), in terms of resources use, environmental emissions, employment, and many more. Here we assess the potential impacts of power transition on multiple SDGs progress across 49 economies under six socio-economic-climate scenarios. We find that the low carbon power transition under Representative Concentration Pathway (RCP) 2.6 scenarios could lead to approximately 10% improvement in global SDG index score from 65.30 in 2015 to 71.62-71.64 in 2050. However, the improvement would be significantly decreased to 1.91%-4.98% and 3.42%-5.24% under RCP6.0 and RCP4.5 scenarios, respectively. Power transition could improve the overall SDG index in most developed economies under all scenarios while undermine their resources-related SDG scores. The power transition induced changes in international trade would improve developed economies’ SDG progress, but jeopardize that of developing economies which usually serve as resource hubs to meet the demand for low carbon power transition in developed economies. 

How to cite: Peng, K.: Low carbon transition of global power sector may enhance sustainable development goals, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4310, https://doi.org/10.5194/egusphere-egu23-4310, 2023.

EGU23-4592 | ECS | PICO | ERE1.5

Growing Terbium Shortage Urges Radical Green Mining of Heavy Rare Earths 

Wei Chen, Peng Wang, and Wei-Qiang Chen

China’s supply of terbium and other heavy rare earth elements (HREEs) are critical to global sustainable transition. However, their supply chain and corresponding bottlenecks remain unclear. Here we present the first deep-dive analysis of China’s terbium supply chain and trade flows from 1990 to 2018, as well as its future potential trends through 2040. We identify a growing terbium shortage along with its fast-increasing demand to meet various sustainable applications, particularly for electric vehicles (EVs) and wind power (nearly half in 2018). In sharp contrast to previous views, we uncover that the lack of available green mining technology under rigorous environmental regulations, rather than China’s production quota, is currently the main constraint of terbium supply, given only 25% of its quota was exhausted in 2018. Moreover, this supply gap is expected to increase six-fold over the next 20 years to meet China’s EVs and wind power ambitions. Our further analysis reveals the present widely-advocated approaches (including material substitution, reduction, and recycling), will alleviate only around 56% of such shortages, which urges radical green mining breakthroughs to overcome environmental constraints in both China and other HREEs supply countries.

How to cite: Chen, W., Wang, P., and Chen, W.-Q.: Growing Terbium Shortage Urges Radical Green Mining of Heavy Rare Earths, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4592, https://doi.org/10.5194/egusphere-egu23-4592, 2023.

EGU23-5194 | PICO | ERE1.5

Carbon footprint scenarios for electricity mix in China 

Jin Yang and Lin Tang

The biggest increase in carbon emissions took place in the power sector, accounting for more than 40% of global carbon emissions. Identifying critical sectors of carbon emissions in the upstream power sector and mapping out emission reduction pathways are core components of achieving supply chain-wide carbon reductions in China. However, the path to achieving supply chain-wide carbon reductions in China from the provincial perspective is still unclear. This study quantifies the embodied carbon emissions of different power generation technologies by region using a multi-regional input-output-based hybrid approach. The critical upstream sectors that indirectly drive or transport large amounts of carbon emissions through supply chains are identified using both consumption-based and betweenness-based methods. The changes in supply chain-wide carbon emissions of the power sector by region under different emission reduction policy scenarios are also examined. The results indicate that the solar power sector brings the highest carbon reduction benefits, with an average carbon intensity of 1.25 t/10000 yuan. Significant differences in embodied carbon intensity across provinces for the same type of power generation sector are observed, and there is a mismatch between current installation and carbon reduction targets in the coal-fired and wind power sectors. Critical sectors of carbon emissions in the upstream power sector are concentrated in the energy sector and energy-intensive sectors, while the electrical machinery and equipment sector is also key to alleviating environmental pressures as an important upstream carbon transmission sector. Besides, the implementation of the "Replacing Small Generation Units with Large Ones" policy at the provincial level, especially in northwest China, and “further enhancing the supply capacity of clean energy” can effectively promote the emission reduction of the whole supply chain in the power sector. The results presented in this paper may provide a reference for the provincial government to rationally plan future low-carbon transformation paths of the power sector.

How to cite: Yang, J. and Tang, L.: Carbon footprint scenarios for electricity mix in China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5194, https://doi.org/10.5194/egusphere-egu23-5194, 2023.

EGU23-8314 | ECS | PICO | ERE1.5 | Highlight

Life-cycle CO2 and Air Pollutant Emission Assessment of China’s Cement Industry under Planetary Boundaries 

Xingrui Cai, Chaoyue Zheng, Jing Meng, and Xuejun Wang

China is the world’s largest cement producer and consumer, contributing 58% of the world’s total cement production in 2020. The cement industry in China is associated with 4–5% of China’s total energy production and contributes 10–15% of national total CO2 emissions, ranking second only to the power industry, and also significant air pollutant discharges such as SO2, NOx and particulate matter (PM). Since China’s energy and environmental policies for the cement industry usually focus on specific energy/environment effects and a single manufacturing process, this study described the cradle-to-gate lifecycle covariation relationship of these effects and analyzed the potential transgression magnitude to related planetary boundaries to assist in designing low carbon and pollution industrial transition in Chinese cement industry. The multi-regional decomposition analysis model, the LMDI decomposition, and the SDA method were employed to identify the driving factors such as energy intensity, manufacturing technology, economic structure, intermediate demand and structure, and total demand. We found that the Chinese cement industry not only causes massive emissions directly but also imposes environmental burdens on other sectors through up- and downstream supply chains, especially in eastern and central regions. Scope 1 and 2 emissions decreased sharply for CO2, SO2, and PM thanks to stricter environmental regulations, but Scope 3 emissions of CO2 increased by approximately 30%, contributed by energy intensity and economic structural change. Although total emissions basically presented decline trends, several national and regional planetary boundaries might be transgressed under downscaling principles based on population, and gross value added. This work improves our understanding of lifecycle carbon emissions and pollution and related total environmental burden in terms of planetary boundaries, thus offering references for the implementation of energy conservation and environment policies in the Chinese cement industry.

How to cite: Cai, X., Zheng, C., Meng, J., and Wang, X.: Life-cycle CO2 and Air Pollutant Emission Assessment of China’s Cement Industry under Planetary Boundaries, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8314, https://doi.org/10.5194/egusphere-egu23-8314, 2023.

EGU23-16498 | ECS | PICO | ERE1.5

Drivers of global carbon emissions 1990-2014 

Cuncun Duan

The identification of the drivers of carbon emissions is fundamental for carbon reductions at the national level. In this study, structural decomposition analysis (SDA) is applied to 112 countries in the world from 1990 to 2014. Carbon dioxide emissions are decomposed into six driving factors: population, fuel mix, energy intensity, production structure, consumption patterns, and consumption volume. Then, the contributions of five final consumers and the six driving factors to the total carbon dioxide emissions are quantified. Based on the CO2 emissions intensity and the CO2 emissions growth rates, 112 countries are classified into 4 groups and the effects of all driving factors vary significantly among groups. Energy intensity is the most significant factor that negatively influences the total carbon emission in all groups. Fuel mix and production structure show potential positive effects on reducing carbon emissions in Group 2 (e.g. the USA, Greece, Italy) and Group 3 (e.g. Germany, the UK, Sweden), but they increase the carbon emissions in Group 1 (e.g. China) and Group 4 (e.g. Indonesia, Thailand, Pakistan). Consumption volume results in a dramatic increase in the carbon emissions in all groups, which implies that the increasing purchasing power of households and government is the most notable obstacle to carbon dioxide mitigation. Population growth accelerates the carbon emissions in developing countries in Group 4. Thus, the race between household consumption volume growth and energy intensity reduction is vital for carbon emission mitigation in Group 4.

How to cite: Duan, C.: Drivers of global carbon emissions 1990-2014, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16498, https://doi.org/10.5194/egusphere-egu23-16498, 2023.

ABSTRACT

Metal pollution is a global environmental issue and considers one of the most serious problems in coastal environments. Present work aimed to document the distribution, ecological risk, and the potential sources of heavy metals (HMs) in coastal sediments of Ras Abu Ali Island, Arabian Gulf, Saudi Arabia. V, Fe, Sr, Al, As, Hg, Sb, Cd, Co, Mn, Ni, Zn, Cr, Pb, Cu were determined in 34 coastal sediment using Inductively Coupled Plasma - Atomic Emission Spectroscopy (ICP - AES) and several pollution indices, and multivariate analysis were applied. The lower HM levels were recorded in the medium to coarse sized samples in the northern part of the study area faced to the open sea. The average values of Ni, Zn, Cu, As, Pb, and Cr were less than the sediment quality guideline (SQG) and the background continental crust. Most applied pollution indices revealed minor enrichment, low contamination and low risk for all HMs, except Sr, which indicated extremely severe enrichment and very high contamination. Sr is incorporated in calcite and aragonite of the invertebrate skeletons and sorbed in hydrated form by clay minerals. The petrochemical wastes from nearby Al-Jubail industrial city, Zn refineries, and intensive use of phosphate fertilizers might be the potential anthropogenic sources of Sr in the study area.

Keywords: Heavy metals, Pollution index, Coastal sediment, Strontium, Ras Abu Ali Island.

 

How to cite: Alkahtani, K. and El-Sorogya, A. S.: Contamination and environmental risk assessment of heavy metals in coastal sediments of Ras Abu Ali Island, Saudi ArabiaKhaled Al-Kahtanya and Abdelbaset S. El-Sorogya, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-54, https://doi.org/10.5194/egusphere-egu23-54, 2023.

EGU23-1411 | ECS | Orals | ERE1.7

What about human behavior? The case of urbanization and rice in Africa 

Koen De Vos, Charlotte Janssens, Liesbet Jacobs, Benjamin Campforts, Esther Boere, Marta Kozicka, Petr Havlík, Lisa-Marie Hemerijckx, Anton Van Rompaey, Miet Maertens, and Gerard Govers

Concurrent with an extensive population growth, the African continent has experienced a vast urbanization trend over the last decades. In 2000, around 35% of the population resided in urban areas. By 2020, this share has increased to around 44% and is projected to increase even further by 2050 following the Shared Socioeconomic Pathways (SSP) scenarios. Besides an important effect on local land use through urban expansion, this also affects food systems by shifting dietary patterns away from traditional diets towards imported or convenient goods. This is particularly the case for rice, which is predominantly imported from Southeast Asia, India, or Pakistan, and is gaining in popularity in African urban diets because of the low effort needed for cooking or storage – giving it a strong advantage over other staple crops. This dietary shift will alter trade dynamics, increase the pressure on local resources such as land, water, and fertilizer use, and subsequently also on biodiversity. In studies investigating the influence of urbanization, either the direct effect of urban expansion on land cover or the effects of dietary changes on demands are investigated, but rarely a combination or comparison of both. Particularly in impact studies or applications that focus on the synergy between water, land, and food-related issues, the dimension of human behavior, such as consumer preferences, is often overlooked.

In this study, we provide an initial projection of the expected future effects of both sprawl and shifting preferences for rice caused by urbanization on rice availability, land – and input use, rice-specific emissions, and trade dynamics. By combining micro-level data from household surveys stemming from the Living Standards Measurements Study (LSMS) with the partial equilibrium Global Biosphere Management Model (GLOBIOM) at an African scale, we were able to identify the relative contribution of land cover effects stemming directly from urban expansion and indirectly from dietary shifts caused by rural-urban migration and a divergence in income between urban and rural areas.

We indicate that while urban expansion only has a limited effect at the continental scale, the omission of any dietary shifts caused by urbanization substantially underestimates projections of African rice demand (by around 8% under an SSP2-scenario). This also results in subsequent underestimations of impacts on land use, trade dynamics, and rice-specific methane emissions. By this, our study exemplifies that consumer preferences are an essential component to understanding urbanization impacts, and that, by extension, human behavior is important to consider in impact and nexus studies.

How to cite: De Vos, K., Janssens, C., Jacobs, L., Campforts, B., Boere, E., Kozicka, M., Havlík, P., Hemerijckx, L.-M., Van Rompaey, A., Maertens, M., and Govers, G.: What about human behavior? The case of urbanization and rice in Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1411, https://doi.org/10.5194/egusphere-egu23-1411, 2023.

EGU23-2258 * | Orals | ERE1.7 | Highlight

Feeding 10 billion people and achieving negative emissions within Planetary Boundaries – insights from global modelling 

Dieter Gerten, Johanna Braun, Jannes Breier, Sibyll Schaphoff, Fabian Stenzel, and Constanze Werner

This talk will present key results from a suite of comprehensive simulations performed with a configuration of the LPJmL biosphere model able to represent the dynamic and spatially detailed status of terrestrial Planetary Boundaries (PBs, i.e. guardrails describing maximum tolerable levels of land-system change, biosphere degradation, freshwater use and nitrogen leaching to avoid Earth system destabilisation).

An application of the PB simulator addresses the question how much food could be supplied globally while respecting these multiple PBs, and to what degree this supply could be increased through transformative actions towards more sustainable food production and consumption patterns. A further application demonstrates the potential to achieve ‘negative emissions’ through dedicated biomass plantations (as a measure to limit transgression of the climate change PB) within these PBs. A main finding is that almost half of current food production is environmentally unsustainable in that it depends on PB transgressions. Subsequent simulations show that the same amount of food presently produced under these unsustainable conditions, and even up to about 50% more, could be provided without violating the PB constraints in any place. This would be sufficient to feed around 10 billion people. The required underlying transformations of the food system are rather radical though: ambitious prerequisites are more efficient use of freshwater and nitrogen fertiliser in many places, reallocation of rainfed and irrigated cropland to areas where that would still be acceptable from a PB point of view, halving of food losses, dietary shifts towards lower shares of animal-based products, and (importantly) combinations thereof.

While this poses grand challenges regarding transformation of world agriculture and optimisation of resource use, currently debated methods to achieve ‘negative emissions’ via large-scale deployment of biomass plantations are likely to require large areas as well as freshwater and nutrients on their own. We will show that the option space for such measures is therefore actually very limited, if the terrestrial PBs were to be maintained. In addition, PB interactions such as ongoing and aggravating climate change including more frequent and intense droughts may seriously affect both the food production and negative emissions potentials. A conclusion is that quantitative robust understanding of these major tradeoffs and dilemmas requires even more comprehensive and integrated nexus studies bringing together the relevant aspects in a consistent PB modelling framework, not least also accounting for the social dynamics underlying the required transformations in the real world.

How to cite: Gerten, D., Braun, J., Breier, J., Schaphoff, S., Stenzel, F., and Werner, C.: Feeding 10 billion people and achieving negative emissions within Planetary Boundaries – insights from global modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2258, https://doi.org/10.5194/egusphere-egu23-2258, 2023.

Arsenic (As) pollution has become a global concern due to its toxic and carcinogenic nature. Even at relatively low concentrations, arsenic can cause acute and chronic human toxicity. In the current study, samples of groundwater, soil at three depths (top, 50cm, and 150 cm), and grains were collected from a humid sub-tropical region in India encompassing Ballia, Deoria, and Mau districts in the state of Uttar Pradesh. All the samples were analyzed for arsenic employing Inductively Coupled Plasma Mass Spectrometry (ICPMS-MS). 60.3% of groundwater samples exceeded the Bureau of Indian Standards (BIS) permissible limit of 10 μg/l. 40% of soil samples were above the mean background concentration for arsenic in the soil as indicated by the Indian Agricultural Research Centre (IARC), i.e., 5 mg/kg. Further, Human Health Risk Assessment (HHRA) was evaluated in four stages: hazard identification, dose-response assessment, exposure assessment, and risk characterization. HHRA estimates the nature, magnitude, and probability of arsenic impacts in the present and the future. Chronic Daily Intake rate (CDI) was determined to assess the exposure, which depends on the mobility of arsenic in groundwater→soil→crop system. The gradual increase in arsenic contamination in groundwater, mostly used in irrigation, finds its way to the food chain either via drinking or cooking, which is a matter of concern for humans. For risk assessment, Total cancer risk (TCR) and Hazard Index (HI) were computed. Finally, the study estimated the cancerous and non-cancerous risks from arsenic toxicity in groundwater-soil-crop system to human adults and children. The cancerous risk for arsenic contamination was in the order of adults>children due to long-term exposure to arsenic by adults. In contrast, the non-cancerous risks for adults and children exceeded the threshold value of 1 provided by the U.S. Environmental Protection Agency (USEPA), specifying a high health risk rate (children>adults). Apparently, children are more sensitive to chemicals in comparison to the adaptability of adults, and hence, they are most affected. It is envisaged that studies like this, which examine scenarios of elevating probabilities of health risks in children and adults from arsenic-contaminated groundwater, soil, and crops, would enable more rational and decisive actions from the concerned stakeholders for arsenic management in the future.

How to cite: Dhamija, S. and Joshi, H.: Assessment of Human Health Risks from Arsenic Contamination in Groundwater-Soil-Crop System of a Humid Sub-Tropical Region in India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2526, https://doi.org/10.5194/egusphere-egu23-2526, 2023.

EGU23-3963 | Posters virtual | ERE1.7 | Highlight

A Resource Nexus concept - Definition, design, and practice 

Floor Brouwer

The nexus has gained importance in assessing interlinkages between related resources and is critical to achieving broader policy goals such as the Sustainable Development Goals (SDGs) or targeted objectives related to biodiversity and climate. Creating awareness of such interactions offers a basis to seek synergies that might be created. Guided by an extensive literature review and a consultation of nexus experts, the presentation will summarize the main features of the nexus and an overview of essential resources that are critical for consideration in a Resource Nexus concept. Definitions of the nexus provided in the literature typically relate to focused and often limited approaches. Moreover, some steps are presented to advance the concept in Resource Nexus assessments. In light of the latter, an effort is made to propose a more robust definition of the Resource Nexus for its application and operationalization for policy support.

 

How to cite: Brouwer, F.: A Resource Nexus concept - Definition, design, and practice, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3963, https://doi.org/10.5194/egusphere-egu23-3963, 2023.

EGU23-4253 | ECS | Posters on site | ERE1.7

Water-Energy-Food Nexus Analysis at Basin Level to Improve the Resources Availability and Accessibility Sources 

Krishna Mondal, Chandranath Chatterjee, and Rajendra Singh

Water, Energy and Food (WEF) are considered global security, prosperity, and equity pillars. These resources are fundamentally linked: food production requires both water and energy; pumping, treating, and transporting water requires energy; energy production requires water, which faces numerous challenges, including growing population density, rapid urbanisation, economic growth, poverty, hunger, changing diet habits and climate changes. In this study, we have developed a spatially distributed (block-scale) WEF-Nexus model with the help of the Modified Pardee-RAND Water-Energy-Food Security Index (MPRWEFSI) equation to meet the basin-scale WEF challenges. The Pardee RAND WEF security index has been modified by considering the industrial and agricultural water requirement, renewal energy and water sources, modern farm equipment uses, hunger index, etc. The developed model can produce the resources availability, accessibility and security indexes. We have tested the model in the Kangsabati river basin for 2011. The estimated values of the water, energy, and food subindex reveals that the Jaypur block (1.0) had the highest water security, the Bipur-II block (0.865) had the highest energy security, and the Jhargram block (1.0) had the highest food security. Conversely, the Jhalda-II block (0.65) has the lowest water security, the Kharagpur-I block (0.52) has the lowest water security, and the Purulia-I block (0.56) has the lowest water security. Furthermore, Jaypur (0.92) and Jhalda-II (0.63) had the highest and lowest overall WEF nexus index. The result also shows that the basin's water, energy, and food availability indexes are 0.88, 0.91 and 0.65, accessibility indexes are 0.92, 0.60, and 0.98, and security indexes are 0.89, 0.73 and 0.79, respectively. The overall WEF nexus Index of the basin is 0.80. Although the availability and accessibility of resources are in a considerable range, different schemes and policies are needed to achieve a hundred per cent resources availability, security, and security. Likewise, basin-scale WEF management will ensure better management of WEF resources holistically and equitably. This study will be helpful in influencing the policy and resource planning process.

Keywords: Resources Availability, WEF-Nexus, Pardee RAND, Basin-scale

 

How to cite: Mondal, K., Chatterjee, C., and Singh, R.: Water-Energy-Food Nexus Analysis at Basin Level to Improve the Resources Availability and Accessibility Sources, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4253, https://doi.org/10.5194/egusphere-egu23-4253, 2023.

EGU23-6277 | ECS | Posters virtual | ERE1.7

Integrating Water-Energy-Food-Ecosystems (WEFE) Nexus Indicators and SDGs 

Chrysaida-Aliki Papadopoulou and Nikolaos Mellios

The Water-Energy-Food-Ecosystems (WEFE) nexus represents a concrete system the components of which are inextricably linked with direct and indirect interlinkages. Complexity is the main characteristic describing this complicated system of interactions that affects the effective management of available resources at both physical and policy level. Thus, sectorial approaches have been proved rather insufficient and a holistic rationale is now suggested, placing emphasis on the systemic nature of the WEFE nexus. The achievement of SDGs and relevant sub-targets is also significantly affected by the sustainable use of resources as the core dimension of SDGs reflects the urgent need for the adoption of a more sustainable and resource-efficient pattern of development. This study elaborates on WEFE nexus indicators supporting sustainability in line with the priorities having been set by SDGs. Such indicators focus on issues strongly related to the several WEFE sectors such as flood alleviation, hydropower production, exploitation of biomass, rural/agricultural development, water quality protection, securing of environmental flow, food production and land use changes under climate change conditions. Moreover, the spatial dimension is taken into consideration as, according to the literature, the successful implementation and achievement of SDGs presupposes their specialization and adaptation to local needs and characteristics (e.g. country or regional level). Land use change in time (%), GHG emissions emanating from agriculture and livestock (%), crop yields (cereals, vegetables, etc.) (%), use of pesticides/fertilizers (kg) and water available for environmental flow (%) are among the proposed indicators. It should be mentioned that such indicators correspond to more than one SDG as emphasis was placed on covering as many aspects of SDGs as possible.

How to cite: Papadopoulou, C.-A. and Mellios, N.: Integrating Water-Energy-Food-Ecosystems (WEFE) Nexus Indicators and SDGs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6277, https://doi.org/10.5194/egusphere-egu23-6277, 2023.

EGU23-8580 | Orals | ERE1.7

Doubling protected land area may be inefficient at preserving the extent of undeveloped land and could cause substantial regional shifts in land use 

Alan Di Vittorio, Kanishka Narayan, Pralit Patel, Katherine Calvin, and Chris Vernon

Projection of land use and land cover change is highly uncertain yet drives critical estimates of carbon emissions, climate change, and food and bioenergy production. We use new, spatially-explicit land availability data in conjunction with a model sensitivity analysis to estimate the effects of additional land protection on land use and cover. The land availability data include protected land and agricultural suitability and are incorporated into the Moirai land data system for initializing the Global Change Analysis Model (GCAM). Overall, decreasing land availability is relatively inefficient at preserving undeveloped land while having considerable regional land use impacts. Current amounts of protected area have little effect on land and crop production estimates, but including the spatial distribution of unsuitable (i.e., unavailable) land dramatically shifts bioenergy production from high northern latitudes to the rest of the world, as compared to uniform availability. This highlights the importance of spatial heterogeneity in understanding and managing land change. Approximately doubling current protected area to emulate a 30% protected area target may avoid land conversion by 2050 of less than half the newly protected extent while reducing bioenergy feedstock land by 10.4% and cropland and grazed pasture by over 3%. Regional bioenergy land may be reduced (increased) by up to 46% (36%), cropland reduced by up to 61%, pasture reduced by up to 100%, and harvested forest reduced by up to 35%. Only a few regions show notable gains in some undeveloped land types of up to 36%. Half of the regions can reach the target using only unsuitable land, which would minimize impacts to agriculture but may not meet conservation goals.

A.V. Di Vittorio, K.B. Narayan, P. Patel, K. Calvin, C.R. Vernon (2022). Doubling protected land area may be inefficient at preserving the extent of undeveloped land and could cause substantial regional shifts in land use. GCB Bioenergy, 00:1-23. http://doi.org/10.1111/gcbb.13016

How to cite: Di Vittorio, A., Narayan, K., Patel, P., Calvin, K., and Vernon, C.: Doubling protected land area may be inefficient at preserving the extent of undeveloped land and could cause substantial regional shifts in land use, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8580, https://doi.org/10.5194/egusphere-egu23-8580, 2023.

EGU23-10381 | ECS | Orals | ERE1.7

Spatial patterns of land use & land cover changes surrounding Colombian water reservoirs 

Caroline Salomão, Jonas Alsleben, Philippe Rufin, and Patrick Hostert

Hydropower dams can induce spatial and temporal changes in land and water systems in terms of resource access and use. Regardless of the main purpose of these dams (that is, to produce energy), analyzing these changes by the lenses of the water-energy-food nexus helps us to identify the synergies and trade-offs between these components in the watershed context. Changes  in land & water systems happen in different times (dam’s construction and operation), spatial scales and, in many cases, are also influenced by national political-economic context. Colombia is moving towards peace agreements in recent years, and this process already showed impact in the patterns of land and water uses, especially by agricultural systems. This new scenario can create or consolidate some local and national socioeconomic characteristics, adding inequalities beyond the dam’s construction. This work focuses on the land cover and land use transitions surrounding two dams in the Magdalena basin, Betania-Quimbo and Hidrosogamosso. This basin is responsible for 70% of the national energy production, it concentrates the production of important food/energy value chains for the local and global market and possess high biodiversity. Both dams were built in 2009 and started operations after 2015, so Landsat satellite images were used to build the land use & cover maps in 2009, 2015 and 2021 for 7 classes (rice, palm oil, pasture, forest, water surface, temporary and permanent crops and others). Due to the intensity of clouds and high altitudes, Colombia is one of the most difficult regions in the world to build these maps, and for this reason global, or even local, mapping available turn out to be unrealistic. A random forest model was chosen, and, as variables, indexes and spatial temporal metrics using 176 bands in total. To extract the pixel information for training and testing the model, a stratified random sample was run using different secondary maps, and after that, we used Google Earth for visual verification (1196 observation for all years). For the accuracy assessment just the sample from the current year was used. The model was run in Google Earth Engine. The model achieved a similar overall accuracy in all years (79%), and for certain agricultural systems a high accuracy, such as the case of palm oil with100% accuracy in 2021 and 2015, despite reaching 70% in 2009. Accuracy for rice was also high: 95%, 84% and 88% in 2021, 2015 and 2009 respectively. Pasture achieved a medium accuracy: 78% (2021): 83% (2015); and 71% (2009). Water surface achieved a high accuracy.For water surface: 100% in 2021 and 2015, and 97% in 2009. The Forest category reached a medium-high accuracy: 81%, 88% and 77% in 2021, 2015 and 2009 respectively. Land use and Land cover maps of areas impacted by dams is of high importance to support decisions that will be implemented via instruments such as Basin Management Plans or compensatory schemes.

How to cite: Salomão, C., Alsleben, J., Rufin, P., and Hostert, P.: Spatial patterns of land use & land cover changes surrounding Colombian water reservoirs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10381, https://doi.org/10.5194/egusphere-egu23-10381, 2023.

EGU23-10490 | ECS | Orals | ERE1.7

Integrating SWAT and Participatory System Dynamics Modelling for analyzing the WEF Nexus: the Tarquinia plain case study 

Marwah Yaseen, Ivan Portoghese, Raffaele Giordano, Alessandro Pagano, Vito Iacobellis, Silvia Vanino, Tiziana Pirelli, Stefano Fabiani, and Valentina Baratella

A safe access to water, energy, and food that does not impact the state of ecosystems and natural resources are needed for human well-being as well as for economic and environmental sustainability. As natural resources availability is threatened by a multiplicity of stressors (including e.g. climate change), the interconnections and interdependencies among resources become stronger and more critical to investigate. Sustainable resources use thus requires a holistic ‘Nexus’ approach, which can contribute to reduce conflicts among sectors and create more synergies compared to a silo approach to water, energy, food, and ecosystems realms.

The importance of active stakeholder engagement in the management of natural resources is also increasingly acknowledged, although there is a lack of participation in policy planning phases and in the decision-making processes. When models are developed to support resources planning and management, the involvement of stakeholders from early stages is crucial to include their knowledge in model building, to tailor the model according to their needs, and to ensure that the potential implications of actions are correctly represented. This ultimately guarantees ownership of modelling results.

System Dynamics Modelling (SDM) includes a multiplicity of tools and methods to describe, model, simulate, and analyse dynamically complex systems taking jointly into account both scientific information (e.g. from sectoral models) and stakeholders’ knowledge and perception. SDM has gained attention, in the recent scientific literature, in Nexus studies. Specifically, the use of qualitative SDM tools (such as Causal Loop Diagrams – CLDs) allows the analysis of the system behaviour based on a conceptual (mental) model focusing on linkages and feedback loops. Quantitative simulation models (stock-and-flow diagrams) use equations to quantify linkages between different types of variables over time. Stock and flow diagrams benefit from the information deriving from sectoral models, such as hydrological models, although the integration with such models has been limitedly explored to date.

The present work proposes an approach based on the use of SDM tools for the development of an integrated model supporting the analysis of a complex Nexus system. Particular attention is given to the analysis of the interdependencies between water quantity, quality, and management, and to the implications of irrigation and agricultural practices for the state of the environment. The main elements of innovation are: i) the coupling between SDM, built in a participatory form with the key stakeholders in the study area, and the Soil and Water Assessment Tool (SWAT); ii) the combination scientific and stakeholder knowledge to appraise the socio-economic and ecological effects of the various management situations co-designed with the stakeholders. Reference is made to one of the pilot areas of the LENSES project (PRIMA Foundation, GA n. 2041), namely the Tarquinia plain watershed, located in Central Italy, an area with a relevant environmental value, but characterized by intensive irrigated agriculture with severe impacts on water and ecosystems.

 

How to cite: Yaseen, M., Portoghese, I., Giordano, R., Pagano, A., Iacobellis, V., Vanino, S., Pirelli, T., Fabiani, S., and Baratella, V.: Integrating SWAT and Participatory System Dynamics Modelling for analyzing the WEF Nexus: the Tarquinia plain case study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10490, https://doi.org/10.5194/egusphere-egu23-10490, 2023.

EGU23-11213 | ECS | Orals | ERE1.7

Water- Energy- Food- Ecosystem Services (WEFE) nexus assessment in the context of climate change: a literature review and conceptual model development for the Adige River basin (Italy). 

Beatrice Sambo, Silvia Cocuccioni, Fabio Carnelli, Stefano Terzi, Anna Sperotto, Silvia Torresan, Massimiliano Pittore, Marc Zebisch, and Andrea Critto

Water, Energy, Food and Ecosystems are inextricably linked within a complex system (“the WEFE Nexus”) dominated by interactions, feedback, and scale effects. The analysis of the WEFE nexus is increasingly relevant in both academic and policy discussion; since its systematic approach could contribute addressing some fundamental EU challenges and policies, supporting the achievement of multiple Sustainable Development Goals.

Existing studies are still focused on dual interactions between sectors (e.g. water-energy, water-food) and don’t fully consider the ecosystem services components, despite their importance is widely recognized. There are still some challenges on how to use heterogeneous and sector-specific data and large climate projection datasets within the nexus concept.

The aim of this analysis is to explore how the WEFE nexus components and their interactions have been examined in recent scientific literature, and how they can be conceptualized in the Adige River basin (Italy), in order to identify synergies and trade-offs among different resources and uses.

Firstly, an in-depth state-of-the-art review on the main methodologies which allow the full integration of ecosystem services and climate change effects was undertaken for publications in the time frame 2010-2022. The review focused on i) how complex interlinkages among the sub-sectors of the WEF nexus and Ecosystem Services are modeled and how researchers operationalized these interlinkages in current conceptual frameworks; ii) how the spatial (from source to sea) and temporal dynamics of nexus are changing under future scenarios of climate and socio-economic changes; iii) which are the recent applied tools, methods and models which allow to operationalize the WEFE nexus behaviors and to support decision-making policies. The review shows that the interrelations among the WEFE sectors within conceptual frameworks are mainly modeled by qualitative methods (e.g. causal loops, multi-criteria decision analysis); while the spatio-temporal dynamics are mainly assessed by quantitative approaches (e.g. System Dynamics, Bayesian Networks). Furthermore, ecosystem services and climate change are mainly considered as external drivers influencing the WEF nexus sectors rather than a nexus component.

Based on the collection and review of peer-reviewed, grey literature and newspaper articles dealing with the water management topic, a first conceptualization of the sectors involved in the WEFE Nexus for the Adige River basin was performed. The framework, finalized with expert-based discussions in the context of two local stakeholders’ workshops, allowed the identification and qualitatively characterization of the relations among the WEFE sectors as well as the pressures by external components on the system (i.e. climate and socio-economic drivers). Five levels of conceptualization have been conceived to represent the main dynamics for each nexus’ sectors (i.e. water, energy, food, and ecosystem services) and their overall interactions.

The results of the analysis are part of the Horizon2020 project NEXOGENESIS, and pave the way for the application of a complex science methodology able to disentangle the role of ecosystem services and climate change in the frame of the nexus approach

How to cite: Sambo, B., Cocuccioni, S., Carnelli, F., Terzi, S., Sperotto, A., Torresan, S., Pittore, M., Zebisch, M., and Critto, A.: Water- Energy- Food- Ecosystem Services (WEFE) nexus assessment in the context of climate change: a literature review and conceptual model development for the Adige River basin (Italy)., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11213, https://doi.org/10.5194/egusphere-egu23-11213, 2023.

EGU23-11836 | ECS | Orals | ERE1.7

Participatory System Dynamics modelling for Water-Energy-Food Nexus characterization and for supporting the analysis of management measures 

Virginia Rosa Coletta, Alessandro Imbò, Alessandro Pagano, Umberto Fratino, and Raffaele Giordano

There is a growing awareness on the existence of dynamic interdependencies between the Water-Energy-Food sectors that cannot be ignored in identifying sustainable sectoral and cross-sectoral policies. In addition, the increasing demand for resources creates trade-offs that are exacerbated by the impacts of climate change, such as drought and flood with increasing frequency and magnitude. The Water-Energy-Food Nexus approach is a powerful concept to address the interrelationships of resource systems and move towards better coordination and utilisation of natural resources, considering existing trade-offs and promoting positive synergistic impacts. However, the incorporation of this approach into policies is making slow progress. This means that a gap exists between science (Nexus thinking) and policy (Nexus doing). 

The present work, carried out in the framework of the REXUS project (H2020, GA 101003632), aims to develop a process, strongly based on the use of participatory approaches, to support decision‐makers in designing sustainable and actionable forward-looking solutions that increase resilience across sectors. Integrated modelling based on System Dynamics is used for this purpose. In fact, it i) accounts for real-world complexities; ii) allows for future scenarios development and analysis, with clear options for policymakers; iii) allows for the integration of stakeholders’ knowledge.

Specific reference is made to one of the REXUS pilots, namely the Isonzo‐Soca watershed between Italy and Slovenia, for which current cross‐border flow regulation agreements are insufficient to guarantee a good status of ecosystem services in the Italian territory. The participatory System Dynamics modelling approach is combined with results of sectoral models, hydropeaking indicators, and ecosystem services indicators for a clear framing of the problem and its effects on the system. Through stakeholder engagement, some strategies for limiting sectoral conflicts are co-designed and fed into the System Dynamics simulation model to assess their effects on the system - and on different aspects (social, environmental, economic, etc.) - under various multidimensional future scenarios. The approach, organised in several steps, is based on a common framework replicable in different study contexts.

How to cite: Coletta, V. R., Imbò, A., Pagano, A., Fratino, U., and Giordano, R.: Participatory System Dynamics modelling for Water-Energy-Food Nexus characterization and for supporting the analysis of management measures, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11836, https://doi.org/10.5194/egusphere-egu23-11836, 2023.

EGU23-15793 | ECS | Orals | ERE1.7 | Highlight

Modelling The Water-Energy-Food-Ecosystem Nexus Using Data-Driven Methods 

Elise Jonsson, Claudia Teutschbein, Thomas Grabs, Andrijana Todorovic, Andreina Francisco, and Malgorzata Blicharska

Attaining resource security in the water, energy, food, and ecosystem (WEFE) sectors is paramount in order to fulfill many of the sustainable development goals. To obtain a holistic understanding of this WEFE nexus and assess the impacts of policy decisions, climate change, and other interventions, a system dynamics approach to modelling has been encouraged. Due to the multiscale, nonlinear nature of this nexus and a recent data deluge in the WEFE sectors, we propose the use of data-driven methods, which rely on dimensionality reduction and machine learning algorithms to find low-rank patterns and parsimonious models in big data sets. As these methods have proven highly successful within other scientific disciplines, we evaluate the prospect of using a data-driven approach to address key issues in nexus research based on analogous case studies from these disciplines. Specifically, we address three key issues with nexus modelling: model discovery, extreme events, and scenario analysis. We first consider how to identify nonlinear dynamical equations from chaotic, noisy, multiscale, and variable-deficient measurements using algorithms like SINDy and HAVOK, which have already been employed on a multitude of physical, biological, and chemical systems. We then investigate how to model the cascading impacts of extreme events on the nexus based on data-driven models of disease outbreak, as well as rapid model recovery after an unprecedented extreme event. Finally, we look into how to employ data-driven control, using case studies in flight control and drug intervention modelling, for the purpose of assessing how policy decisions, climate change, or population growth may be evaluated when modelling the nexus. This can provide tools for stakeholders to see what systemic impacts their decisions might have, and how they can attain synergies between the WEFE sectors. While many studies have conceded that nexus modelling is highly individualized based on the selected region, sectors, and data availability, this overview highlights that a generalized systematic approach to nexus modelling may still be possible, despite these challenges.

How to cite: Jonsson, E., Teutschbein, C., Grabs, T., Todorovic, A., Francisco, A., and Blicharska, M.: Modelling The Water-Energy-Food-Ecosystem Nexus Using Data-Driven Methods, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15793, https://doi.org/10.5194/egusphere-egu23-15793, 2023.

EGU23-16010 | ECS | Posters on site | ERE1.7

Gender gaps in the Water-Energy-Food and Ecosystems Nexus 

Bianca Maria Rizzo, Enrica Caporali, and Xenia Schneiderand

Water, energy, food and ecosystems are four elements of paramount importance in achieving global human well-being leading to poverty reduction and sustainable social and economic development.

New global challenges brought about by increasing resource scarcity, climate change and environmental degradation are leading to an ever-increasing tightening of living conditions for men and women. 

These difficulties exacerbate conflicts, damaging economic development and leading to the death and forced displacement of millions of people each year. Women are the most affected by all these dramatic situations because they exacerbate gender inequalities and reinforce gender gaps. 

At the same time, it is widely recognized that there is a strong relationship between gender and sustainability in consumption, food production and ecosystem management.  

A Water-Energy-Food and Ecosystems Nexus approach which considers gender issues as important elements of the socio-economic environment, is proposed here for a sustainable management of resources. Men and women are affected differently by the lack of resources and have different roles in using and managing them, so it is crucial to have a gender perspective and to investigate gender issues while transitioning to WEFE-Nexus..

The approach is based on the analysis of 1) factors that contribute to a situation of gender inequality and 2) gender issues that impair a holistic transition towards WEFE-Nexus., i.e., a situation in which men and women do not have the same rights, responsibilities, and opportunities regarding the use and management of WEFE resources.

A thorough understanding of gender issues at various levels requires gender-disaggregated data. Only with this kind of data can policy makers be aware of the existing situation and can design gender-sensitive policies and strategies. In addition, gender-specific datasets linked to WEFE-Nexus are important to understand what differences arise from gender-specific productive roles, different perspectives of resources, access, and decision-making mechanisms with respect to resource management and use.

The preliminary analysis developed on 4 Mediterranean countries, namely Italy, Spain, Egypt, and Tunisia, in addition to a different availability of gender disaggregated data, reveals a significant gender gap in decision-making in the water, energy, food, and ecosystem sectors. All are dominated by men, especially in the most relevant job positions. This means that women are hardly involved in shaping policies or innovative resource management systems whose lack affects them most. The root cause of these gaps has been identified as a lack of awareness of the topic. Gender issues are considered irrelevant to the achievement of sustainable resource management. This often causes an underestimation of the effects that gender dynamics have on the achievement of this outcome. 

Having scientists who are aware of gender issues in their field and able to understand and analyze them in different contexts is the first step to having research that makes a real contribution to achieving gender equality by providing gender-disaggregated data and gathering the perspectives of all relevant actors and actresses.

How to cite: Rizzo, B. M., Caporali, E., and Schneiderand, X.: Gender gaps in the Water-Energy-Food and Ecosystems Nexus, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16010, https://doi.org/10.5194/egusphere-egu23-16010, 2023.

With increased water scarcity due to anthropocentric and natural causes, the trade-offs and synergies intrinsic to efficiently allocating water resources to various competing uses have become more polarized. Realizing the importance of an integrated approach in water governance, the Water-Energy-Food-Ecosystems (WEFE) Nexus can be used as a multi-level and cross-sectoral approach that advocates the EU water economy and, in addition, relies on ecological and social considerations. The goal of this work is to propose, design and foster the adoption of integrated, innovative and inclusive Nexus-smart water governance schemes and institutional settings to promote a secure water future in the EU, resilient to climate change. This work follows an evidence-based approach to propose, assess and optimize a set of WEFE Nexus smart methods in six different case studies reflecting various cross-sectoral, multi-level and multi-stakeholder water governance contexts. To achieve this goal and monitor water governance in the EU we provide a set of Nexus-smart socio-economic and environmental indicators that reflect the cross-sectoral and multi-level nature of water use.  We also propose and develop economic instruments and business models that support robust water management under cross-sectoral competition. 

How to cite: Vrachioli, M.: Resilient water governance under climate change within the WEFE Nexus (RETOUCH Nexus project), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16792, https://doi.org/10.5194/egusphere-egu23-16792, 2023.

EGU23-741 | ECS | Posters on site | ERE1.8

Trade-driven relocation of Greenhouse gas emission in India 

Shekhar Goyal and Udit Bhatia

The green revolution enhances crop yield, significantly contributing to many low-income countries' socio-economic development. However, increasing crop yields might raise crop residue burning, leading to adverse human health and environmental consequences. Recent studies show that international trade affects the global distribution of Agricultural Greenhouse Gas (AGHG) emissions, air pollution, and public health. Domestic Interstate Trade (DIT) has similar effects on AGHG within the country but has yet to be comprehensively investigated. Large-scale open burning of crop residue further contributes to severe haze pollution in Indian cities, affecting national climate goals. Given the critical importance of food security, further reducing AGHG remains challenging. While there has been an increasing focus on AGHG, limited attention has been paid to its consumption-based drivers. We found that DIT exacerbates the health burdens of air pollution in Indian states based on regional wind patterns. Here, by tracing the consumption-based accounting of emissions, we evaluated the consequences of agricultural DIT on the emission potential of India. Our preliminary results show that though residual crop burning pollutes nearby regions, it is driven by consumption-based demands. These results suggest that DIT structure readjustment according to emission losses is needed for India while targeting trade intensification strategies. Our findings are relevant to national efforts to reduce emission losses in India. 

 

How to cite: Goyal, S. and Bhatia, U.: Trade-driven relocation of Greenhouse gas emission in India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-741, https://doi.org/10.5194/egusphere-egu23-741, 2023.

EGU23-1556 | ECS | Orals | ERE1.8

Key trends and opportunities in water footprints of crop production 

Oleksandr Mialyk, Martijn J. Booij, Rick J. Hogeboom, and Markus Berger

Crops consume the majority of green and blue water worldwide which, in many areas, affects water availability and state of ecosystems. Hence, it is important to understand the recent dynamics in crop water footprints (WF, m3 t-1). Here, we analyse the global WF of more than 150 crops during 1990–2019 simulated with a global gridded crop model ACEA at 5 x 5 arc minute resolution. Our results indicate the overall decreasing trends in unit WF across all crop groups. However, these reductions are insufficient to curb the increase in total water consumption, which is mostly driven by the growing demand for oil crops. The WF dynamics vary among regions due to a combination of multiple environmental and socio-economic factors. Thus, it is possible to identify key challenges and opportunities in WFs of crop production. Addressing them may benefit water and food security while making the global food system more sustainable.

How to cite: Mialyk, O., Booij, M. J., Hogeboom, R. J., and Berger, M.: Key trends and opportunities in water footprints of crop production, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1556, https://doi.org/10.5194/egusphere-egu23-1556, 2023.

EGU23-2393 | ECS | Orals | ERE1.8

Efficiency of dietary sustainability and its global transition 

Pan He, Zhu Liu, Klaus Hubacek, Giovanni Baiocchi, and Dabo Guan

Global diets consume tremendous natural resources while causing multiple environmental and health issues. As the world faces challenges of adequate nutrition security with concomitant climate and environmental crises requiring urgent action, policies need to improve the efficiency of devoting environmental input of the food systems for health benefits. Here we evaluate the global transition of such efficiency in the past two decades represented by health benefits obtained by per unit of 4 key environmental inputs (GHG emissions, stress-weighted water withdrawal, acidifying emissions, and eutrophying emissions) in 195 countries. We find that the efficiency of each environmental input follows an N-shaped curve along the Socio-Demographic Index (SDI) gradient representing different development levels. The efficiency first increases by benefiting from the eliminated stunting with a larger abundance of food supply, then decreases driven by climbing environmental impacts from a shift to animal products, and finally starts to slowly grow again as countries shift toward a healthier diet. Our efficiency indicator offers an improved understanding of nutritional transitions in terms of environmental impacts and a useful way to monitor the transition of dietary patterns, set up policy targets, and evaluate the effectiveness of specific interventions.

How to cite: He, P., Liu, Z., Hubacek, K., Baiocchi, G., and Guan, D.: Efficiency of dietary sustainability and its global transition, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2393, https://doi.org/10.5194/egusphere-egu23-2393, 2023.

EGU23-3940 | ECS | Orals | ERE1.8 | Highlight

Sustainability trade-offs for equity and climate interventions in global food systems: The case of cocoa in Ghana 

Sophia Carodenuto and Marshall Adams

Despite widespread attempts to ‘eat local,’ many of the lifestyle factors in the Global North rely on the production of agrifood commodities that can only be grown in tropical ecosystems, far from the dominant geographies of consumption. Chocolate, coffee, and palm oil represent a handful of consumer goods that are described as ‘tropical forest risk commodities,’  whose production threatens some of the last remaining biodiversity hotspots and stable carbon sinks. This research assesses the trade-offs between dominant approaches to poverty reduction in tropical forest landscapes – regions where global land use change is concentrated as forests are converted to agrifood commodity production areas to produce consumer goods that are core to global food systems. After Côte d’Ivoire, Ghana is the second largest exporter of cocoa (the main ingredient in chocolate). Ghana’s economy is highly cocoa-dependent, and cocoa provides livelihoods for about a quarter of the population, especially in rural areas where alternative incomes are limited. Although the cocoa sector contributed an estimated US$2.71 billion in government revenues in 2017, many cocoa producers live below the national poverty line.

Policy responses to balance the trade-offs between global food production, climate change, and socioeconomic development have recently come to the fore in Ghana – the world’s second largest producer of cocoa. In 2019, the Government of Ghana introduced the Living Income Differential (LID), which requires buyers to pay an additional US$400 per ton of cocoa on top of the floor price. With low farmer incomes identified as a critical driver of multiple sustainability issues in Ghana’s cocoa sector, this differential is meant to be directly transferred to cocoa farmers in response to the persistent challenge of poverty in cocoa farming communities. Using the Q methodology, we engaged over 50 stakeholders from various levels (international policy experts, cocoa sector stakeholders in Ghana, and cocoa farmers) to understand how LID is perceived, including its potential to transform the rural poverty complex embedded in Ghana’s cocoa supply chain. While the LID is lauded for increasing producer price across the board, our findings indicate that the lack of regard for farmer diversity (i.e., tenure rights, sharecroppers, and caretakers), farm size, and land management strategies (agroforestry versus clearing forest to establish farms) risks undermining the ability of this pricing mechanism to reduce farmer poverty as a way to foster sustainability in the sector. Further, the LID is siloed from on-going sustainability governance efforts in the sector, such as zero deforestation cocoa. If the LID is delivered to farmers across the board without any quid pro quo for how cocoa is produced, the policy’s unintended consequences may include increasing deforestation in the short term, while lowering the world market price of cocoa in the long term as cocoa supply increases. We conclude with policy implications on why different perspectives matter in managing sustainability trade-offs in deforestation frontiers. This study provides important insights for understanding how to achieve multiple sustainability goals together.

How to cite: Carodenuto, S. and Adams, M.: Sustainability trade-offs for equity and climate interventions in global food systems: The case of cocoa in Ghana, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3940, https://doi.org/10.5194/egusphere-egu23-3940, 2023.

EGU23-4584 | ECS | Posters on site | ERE1.8

Enhanced excreta-based biochar: a novel source of organic fertilizer in the Guatemalan highlands 

Benjamin Wilde, Mona Mijthab, Raluca Anisie, Federico La Blasca, Estefani Gonzalez, and Johan Six

Communities in the highlands of Guatemala are currently struggling with insufficient access to effective sanitation. Water born solutions, often referred to as the “flush and forget model” of human excreta management, cannot be adequately delivered to the rapidly growing peri-urban regions growing across the area. The consequences of the insufficient collection and treatment of this waste are worsening human and environmental health outcomes. Concurrently, smallholder farmers in the region struggle to supply their soil with sufficient quantities of plant nutrients to avoid growing yield gaps. Even when capable of utilizing required amounts of chemical fertilizers, there is no clear option available to maintain soil organic carbon; typically relied upon organic inputs such as animal manure are available in only insufficient quantities.

To deal with the sanitation challenge facing communities in the region, Mosan, an NGO based in the Lake Atitlan region of Guatemala has, for the last several years, piloted a novel approach to sanitation provision. Utilizing an on-site urine diversion system that focuses on the capture, processing, and valorization of excreta, this resource-oriented approach, in addition to providing households with the means to safely manage generated excreta, yields a novel organic fertilizer. Using two treatment processes, alkaline dehydration for urine and pyrolysis for the feces, Mosan can produce an enhanced biochar product that could have the potential to sustainably improve soil health and fertility for small holder highland farmers in the region. Working in partnership with Mosan and Vivamos Mejor, and agricultural development organization based in Guatemala, the Sustainable Agroecosystems group at ETH Zurich has been testing the potential of this novel source of organic fertilizer.

Over the last eighteen months, this interdisciplinary team of researchers, community activists, and farmers has managed two experimental sites in the region. The first focused on the incorporation of enhanced biochar into a potting mix used to grow tree seedlings used for reforestation efforts in the region. The second, a participatory farmer field trial, was designed to compare the yield increases of maize fertilized with enhanced biochar to that grown with chemical fertilizer (urea). In addition to observing no significant differences in the growth performance of the seedlings, or the yield increases of the maize grown with the excreta-based biochar compared to the standard alternatives, our team also observed positive changes to several soil physical and chemical properties in the field trial. Given these results, we argue that a socio-technical transition towards a circular rural-urban system, one predicated on nutrient capture and reuse of currently underutilized organic waste sources such as human excreta, would simultaneously improve human and environmental health outcomes in urban areas, while also increasing long term soil health and fertility in outlying rural ones.

How to cite: Wilde, B., Mijthab, M., Anisie, R., La Blasca, F., Gonzalez, E., and Six, J.: Enhanced excreta-based biochar: a novel source of organic fertilizer in the Guatemalan highlands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4584, https://doi.org/10.5194/egusphere-egu23-4584, 2023.

EGU23-5975 | ECS | Orals | ERE1.8

Restructuring the Indian agricultural system toward sustainability and lower environmental costs 

Udit Bhatia, Shekhar Goyal, and Rohini Kumar

The evolving international conflicts have a rippling effect on global food security, forcing nations to impose new trade laws to increase their domestic supply at reduced prices and promote the need to develop local and regional food systems to reduce transboundary dependence. While aiming to become a major global food supplier, India faces significant domestic food security risks. India has achieved food security through injudicious fertilizer application on the domestic front. Past agricultural policies, while primarily focusing on maximizing production, paid less attention to their environmental consequences. India feeds 17.1% of the world's population, with 10.7% of the world's arable land: this will further increase with increasing national and international food trade. Sustainably feeding the growing population has garnered considerable attention; however, its national implementation still needs to be improved. The current intensive agricultural practices operate at low water, nutrient, and nutritional efficiencies, demanding high input for high output. As a result, Nitrogen, Phosphorus losses are high, and groundwater resources are depleting in some areas. The vexing question is how to produce sufficient food in the existing regions with minimum inputs and reduced environmental impact. For this, India must reconfigure its current cereal crop production and interstate crop distribution system by reducing nutrient pollution losses, greenhouse gas emissions, and water consumption while sufficing its increasing nutritional demand. Using a state-of-the-art framework from agricultural sciences, network, and resource optimization, our study provided ways toward national assessment of Indian staple crop system redesign for future sustainable intensification.  Further, by incorporating interstate trade within this restructured system, we try to understand how India's cereal crop redistribution will impact domestic food security. Thus to limit the environmental burden of the growing consumer demand, we optimized crop distribution and domestic trade patterns within the parameters of minimizing nitrogen and phosphorus losses. This realistic multi-dimensional framework will help India and other nations identify sustainable food security solutions. 

How to cite: Bhatia, U., Goyal, S., and Kumar, R.: Restructuring the Indian agricultural system toward sustainability and lower environmental costs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5975, https://doi.org/10.5194/egusphere-egu23-5975, 2023.

EGU23-6115 | ECS | Posters on site | ERE1.8

Climate change alters the global diversity of food crops 

Sara Heikonen, Matias Heino, Mika Jalava, and Matti Kummu

Climate change has already impacted the productivity of important food crops. The projected increasing temperatures and changing precipitation patterns affect the climatic suitability of food production areas. Changes in climatic suitability require adaptive actions on farms and will likely alter the potential volume and diversity of food crop production globally.

Existing research has mostly analysed the impacts of climate change on the four staple crops: wheat, rice, maize, and soybean. However, other food crops contribute more than 50% to the global calorie and protein supply and therefore constitute a crucial element of food security. Moreover, these crops might succeed in more diverse climate conditions than the staple crops. If climate change narrows the production potential of the staple food crops, other food crops could become even more important for global food security in the future. Therefore, to comprehensively understand the implications of climate change on food crop production, there is need for analysis on a diverse set of food crops.

In this study, we delineate suitable climate conditions for 27 major food crops using historical climatic data and examine the effect of future changes in climate suitability on food crop production volume and diversity. We define the crop-specific suitable climate conditions utilizing the Safe Climatic Space concept, based on global gridded datasets on biotemperature, precipitation, and aridity in 1970–2000 as well as crop production in 2010. Then, using future climate parameter data, we project changes in global climate suitability for the 27 food crops. The analyses cover five global warming scenarios from +1.5 °C to +5 °C.

The preliminary results indicate that the global food crop production potential on the current croplands will decrease for most crops in all five global warming scenarios. Furthermore, the potential diversity of food crops will decrease significantly at low latitudes but increase in other areas. In all five scenarios, areas near the equator will become unsuitable for most studied crops. On the other hand, on the current extent of cropland, the potential production area of especially oil crops and starchy roots will expand in the northern hemisphere.

For many crops, there is distinct difference in the magnitude of lost production and diversity potential between global warming of +2 °C and +3 °C, highlighting that it is important to restrict global warming at the very maximum to +2 °C. The results of this study could provide insights for agricultural adaptation to climate change by illustrating opportunities for geographically shifting or expanding production in regions where climate suitability is projected to change. Further, the results could identify potential substitute crops for regions where climate conditions might become unsuitable for the currently cultivated food crops.

How to cite: Heikonen, S., Heino, M., Jalava, M., and Kummu, M.: Climate change alters the global diversity of food crops, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6115, https://doi.org/10.5194/egusphere-egu23-6115, 2023.

EGU23-6434 | Orals | ERE1.8

Energy and fertiliser price rises are more damaging than food export curtailment from Ukraine and Russia for food prices, health and the environment 

Peter Alexander, Almut Arneth, Roslyn Henry, Juliette Maire, Sam Rabin, and Mark Rounsevell

Higher food prices arising from restrictions on exports from Russia or Ukraine have been exacerbated by energy price rises, leading to higher costs for agricultural inputs such as fertiliser. Using a scenario approach with a global land use and food system model (LandSyMM), we quantify the potential outcomes of increasing agricultural input costs and the curtailment of exports from Russia and Ukraine on human health and the environment.  We show that, combined, agricultural inputs costs and food export restrictions could increase food costs by 60-100% from 2021 levels, potentially leading to undernourishment of 60-110 million people and annual additional deaths of 400 thousand to 1 million people if the associated dietary patterns are maintained. In additional to lower yields, reduced land use intensification arising from higher input costs would lead to agricultural land expansion of 130-349 Mha by 2030, with associated carbon and biodiversity loss. The impact of agricultural input costs on food prices is larger than that from curtailment of Russian and Ukrainian exports. Restoring food trade from Ukraine and Russia alone is therefore insufficient to avoid food insecurity problem from higher energy and fertiliser prices. While the Black Sea Grain Initiative has been a welcome development and has largely allowed Ukraine food exports to be re-established, the immediacy of these issues appears to have diverted attention away from the impacts of fertiliser prices. While fertiliser prices at the start of 2023 have come down from the peaks of mid-2022, they remain at historically high levels.  Our results suggest the costs and lower crop yields achieved through reduced fertiliser use will drive high food price inflation in 2023 and beyond. More needs to be done to break the link between higher food prices and harm to human health and the environment.  

This study demonstrates how modelling can be used to explore the complexity and interlinked nature of the globalised food system and to quantifying the trade-offs and synergies for health and environmental outcomes of difference scenarios.

How to cite: Alexander, P., Arneth, A., Henry, R., Maire, J., Rabin, S., and Rounsevell, M.: Energy and fertiliser price rises are more damaging than food export curtailment from Ukraine and Russia for food prices, health and the environment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6434, https://doi.org/10.5194/egusphere-egu23-6434, 2023.

Extreme weather often causes crop losses with sharp fluctuations in agricultural prices, which imposes negative impacts on sustainable agricultural development. Greenhouse farming is regarded as an effective measure against extreme weather. Thus, it requires a better understanding of the growing complexity of agri-food systems involving greenhouse environmental and societal tradeoffs under climate variations. Considering high energy consumption of greenhouses, this study aims at adopting machine learning with IoT-big data mining to innovatively develop a smart greenhouse environmental control service model under the nexus between meteorology, water, energy, food, and greenhouse environmental control while exploring pathways to low-carbon greenhouse cultivation. The proposed model will be applied to greenhouses in Taiwan for evaluating cross-sectoral synergies and environmental benefits. The results are expected to support greenhouse owners and authorities to make the best use of resources of water, energy, and food through the optimal environmental operation on greenhouse cultivation under extreme climatic events for achieving sustainable development goals (SDGs) and move towards green economy.

How to cite: Hsia, I.-W. and Chang, F.-J.: Machine Learning-Enabled Smart Greenhouse Environmental Control Service Model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6494, https://doi.org/10.5194/egusphere-egu23-6494, 2023.

Agriculture is a key to the Zambian economy, contributing 20% to the country’s GDP and 12% to the national export earnings. However, climate change has a negative impact on Zambian agriculture production. In line with its Vision 2030 to have an efficient, competitive, sustainable and export-led agriculture sector, Zambia is aiming to improve irrigated agriculture through large investment in irrigation. Considering climate change and variability, it is important to adopt best water and nutrient management practices for sustainable use of agricultural resources. Maize being the major staple crop of Zambia, a study was carried out to improve irrigation management by optimizing water and nitrogen use efficiency for maximum maize productivity at field level under varying water and fertilizer applications. To achieve this goal, our study used and adapted nuclear (neutron probe) and isotope (15N and 13C) techniques to the Zambian agro-ecological conditions. Drip irrigation was used as the targeted system. The experiment was implemented based on three water application levels, i.e., deficit (50% and 75% Evapotranspiration) versus optimal (100% Evapotranspiration)and three nitrogen (N) levels (140 kg.ha-1, 112 kg.ha-1 and 84 kg.ha-1, widely practiced being 112 kg.ha-1). Maize was grown as a sole crop, under drip irrigation, in rotation with a legume over the dry season of Zambia in 2021 and 2022. For both years, maize yield was ranging between 2 and 7 ton.ha-1. Results showed that deficit irrigation can be practiced without a significant negative impact on yield (with higher N levels showing significantly higher yields under deficit irrigation) and nitrogen use efficiency. The total N yield and agronomic water use efficiency were significantly higher, up to 1.5 and 3 times respectively, under deficit irrigation as compared to the optimal. Intrinsic water stress (d 13C results) was higher, though not statistically significant, under deficit irrigation. Thus, considering climate change and sustainable use of resources, deficit irrigation should be considered as the option to achieve higher yield and food security.

How to cite: Mwape, M., Said, H., Phiri, E., Heiling, M., Dercon, G., and Resch, C.: Understanding the interaction between maize water use efficiency and nutrient uptake in irrigated cropping systems, a basis for predicting and improving Zambia’s productivity in a changing climate, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6729, https://doi.org/10.5194/egusphere-egu23-6729, 2023.

EGU23-7963 * | ECS | Orals | ERE1.8 | Highlight

Healthier diets, healthier planet? Quantifying the biodiversity pressure of fruit and vegetable consumption in South Africa, India, and the UK 

Abbie Chapman, Carole Dalin, Sara Bonetti, Rosemary Green, Genevieve Hadida, Tafadzwa Mabhaudhi, and Pauline Scheelbeek

Eating more fruits and vegetables lowers risk of non-communicable diseases. Globally, people are not eating the recommended amounts of these foods; consumption must increase to improve human health. However, in general, areas of cropland are associated with lower biodiversity than natural land (e.g., forests and grasslands). Converting natural land to cropland for agriculture therefore risks biodiversity loss which, in turn, risks lowering crop yields because biodiversity supports food production via pollination and pest control. Herein lies a trade-off. As the world seeks to eat more healthily, more fruits and vegetables will be produced to meet demand. Here, we share our research into this trade-off between healthy diets and biodiversity conservation.

To quantify the biodiversity pressure associated with healthy fruit and vegetable crops, we made use of freely available data on: species distributions (IUCN, 2013); fruit and vegetable production, yield, and harvested area (Monfreda et al., 2008); and international trade of fruits and vegetables (FAOSTAT; Dalin et al., 2017). Previous research into cropland-biodiversity relationships has typically grouped land-cover types into ‘cropland’ and ‘natural land’, without considering the impacts of specific crops on biodiversity (except for major commodities, like cocoa, and staples, like maize). We have developed a new suite of biodiversity-pressure metrics for specific crops which can be measured globally. These metrics enable us to quantify the species potentially impacted for each unit of crop in both a consumer country and its trade-partner countries. The new measures facilitate quantitative comparisons among specific crops and countries for the first time. Using these new measures, we compared the biodiversity pressures associated with the production and consumption of 54 different fruits and vegetables. We mapped the origin of crops consumed in the UK, South Africa, and India, and quantified associated biodiversity pressures relative to food produced and imported.

Contrary to previous research considering the relative impacts of food crops on climate change and water resources, biodiversity pressure due to fruit production is not always higher than that due to vegetables. The most important factors associated with increased biodiversity pressures include the country of production and the amounts being produced. We did not identify a single suite of crops standing out as particularly unsustainable across all three focal countries. This is significant, as it emphasizes the importance of trade in influencing sustainability. For some crops, domestic production would have a lower biodiversity pressure than importing from trade partners (e.g., UK-grown tomatoes). In such cases, the domestic production of fruits and vegetables should be promoted in conjunction with biodiversity-friendly farming practices. In other cases, domestic production of a crop is associated with a higher biodiversity pressure than the crop’s biodiversity pressure when produced overseas (e.g., UK-grown cherries). Our findings are particularly important in the context of changing trade patterns since the early 2000s, where countries like the UK have been increasingly sourcing fruits and vegetables from abroad. Our results could therefore inform policies aimed at tracing the environmental impacts of food-supply chains in the UK, India, and South Africa.

How to cite: Chapman, A., Dalin, C., Bonetti, S., Green, R., Hadida, G., Mabhaudhi, T., and Scheelbeek, P.: Healthier diets, healthier planet? Quantifying the biodiversity pressure of fruit and vegetable consumption in South Africa, India, and the UK, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7963, https://doi.org/10.5194/egusphere-egu23-7963, 2023.

EGU23-10063 | Orals | ERE1.8

Risk of deforestation and potential greenhouse gas emissions from vegetable oils’ expansions for food use 

Maria Vincenza Chiriacò, Nikolas Galli, Monia Santini, and Maria Cristina Rulli

The global production of vegetable oils exceeds 200 million tonnes per year, with almost 40% for food use, and around 330 M hectares occupied by oil crops. The most produced is palm (40% if palm kernel oil is included), followed by soybean oil (28%), rapeseed oil (12%) and sunflower oil (9%). Some of these oil crops, particularly oil palm plantations and soy cultivations, are among the main drivers of global land use changes (LUC) and deforestation. In particular palm oil has been one of the most highly criticized due to the link between oil palm cultivation expansion and the loss of primary tropical forests, observed in recent decades. This issue has generated two different responses in the food sector: some players decided to produce and/or use deforestation-free palm oil. Other actors chosen to replace palm oil with other vegetable oils, such as soybean, rapeseed and sunflower oil.

Considering the importance of a proper land management in view of the food-ecosystems-resources nexus, this study assesses the potential LUC and the related GHG emissions that can occur by using sustainable palm oil or replacing it with the other oils for food use. 

A methodology was developed to assess the potential GHG emissions from the LUC due to alternative oil crops expansion at detrimental of high carbon content areas, such as forests or perennial croplands, and the GHG emissions from the production process though a Life Cycle Assessment (LCA).

Under the scenario of 100% replacement of palm and palm kernel oil globally, the extra-land needed to produce the additional alternative oils was determined in their three top producer countries using yield data from literature. An expansion algorithm considering suitability and distance from roads and existing oil crops was developed to determine the potential LUC which may occur in the selected countries. The potential GHG emissions from deforestation and other LUC were calculated from the carbon stock data of the FAO Forest Resource Assessment and IPCC; the field production of the four oils was reconstructed to calculate anthropogenic GHG emissions using relevant LCA existing databases. 

Results show that deforestation-free palm oil is the less impacting in terms of GHG emissions per oil ton thanks to its far highest oil yield. Replacing sustainable palm oil with any other alternative oil is never a favourable solution (Fig. 1), entailing a potential GHG emissions increase from 0.94-0.96 Mg CO2  per ton of palm oil replaced by sunflower oil produced in Ukraine or in Russia (where deforestation is unlikely), to 4.38 Mg CO2 per ton of palm oil replaced by soybean oil produced in Brazil, up to 13.65 Mg CO2 per ton of palm oil replaced by soybean oil produced in Argentina.

 

Figure 1. GHG emissions in Mg CO2eq t-1 from LCA (blue bars) and LUC (green bars) with 100% palm oil replacement. Based on national trends and forest policies, potential deforestation can be likely (full green), likely with limitation (dense dots), likely with offset (oblique lines), unlikely (scattered dots). Vertical lines for palm oil include deforestation.

 

How to cite: Chiriacò, M. V., Galli, N., Santini, M., and Rulli, M. C.: Risk of deforestation and potential greenhouse gas emissions from vegetable oils’ expansions for food use, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10063, https://doi.org/10.5194/egusphere-egu23-10063, 2023.

EGU23-11242 | ECS | Posters on site | ERE1.8

Effect of urease inhibitor and biofertilizer on nitrous oxide emission 

Rayehe Mirkhani, Christian Resch, Georg Weltin, Lee Kheng Heng, Jason Mitchell, Rebecca Clare Hood-Nowotny, and Gerd Dercon

Conventional agricultural practices are heavily dependent on nitrogen fertilizers, which can have negative impacts on the environment through ammonia volatilization and nitrous oxide emission. Previous studies have shown that the use of urease inhibitors or biofertilizers may help reduce such impacts.

A field experiment was established by the Joint FAO/IAEA Centre at the experimental station of the University of Natural Resources and Life Sciences (BOKU) located east of Vienna (Austria) to determine the effect of urease inhibitor and biofertilizer on nitrous oxide (N2O) emission, in wheat cropping systems. A randomized complete block design including five treatments and four replicates was used in this study. The treatments were: T1 (control treatment - without N fertilizer), T2 (Urea only), T3 (Urea+Urease Inhibitor (UI)), T4 (Urea+Biofertilizer), T5 (Urea+UI+Biofertilizer). All treatments received 50 kg N ha-1 at tillering stage (GS 31), except T1. In this study N-(n-butyl) thiophosphoric triamide (nBTPT) or “Agrotain” was used as UI and Azotobacter chroococcum (“AZOTOHELP”) was applied as biofertilizer.

Soil N2O gas fluxes were measured using the static chamber method, eight times between 3 to 84 days after fertilizer application. Gas sampling was performed at the same time each day of measurement, between 8:00 and 10:00 h, to minimize diurnal variation and better represent the mean daily fluxes. A PVC chamber (24 cm height and 24 cm diameter) was inserted into the soil 5 cm deep. The chamber was composed of two separate parts joined together with an airtight rubber. Gas samples were taken at 0 and 30 minutes after closing the chambers using a 500 mL syringe. The gas sample was then immediately transferred from the syringe to a pre-evacuated 1L gas sampling bag with multi-layer foil. Nitrous oxide in the gas samples was analysed using off-axis integrated cavity output spectroscopy (ICOS, Los Gatos).

The statistical analysis showed that UI and biofertilizer had a clear and significant effect on nitrous oxide emission. However, this effect was only observed during the first week after the fertilizer application. Further, the results showed that the highest N2O emission, within this week after adding urea fertilizer, was under the U+UI treatment, which was significantly higher by about 139, 91,79% compared to the Urea+Biofertilizer, Urea, Urea+UI+Biofertilizer treatments, respectively. No significant difference was observed between the other Urea, Urea+Biofertilizer and Urea+UI+Biofertilizer treatments in this period. Although not significantly (p < 0.05), N2O emission was higher in Urea+UI+Biofertilizer treatment compared to the Urea+Biofertilizer treatment.

Due to the ability of UI to reduce ammonia volatilization, we assume that pollution swapping from ammonia volatilization to nitrous oxide emission occurred, explaining the stimulus of UI on nitrous oxide emission. The lower N2O emission in the treatments receiving biofertilizer, compared to the one with no biofertilizer, may be caused by the ability of Azotobacter to reduce N2O emission by N2O-fixation, N2 fixation and reduction of N2O to N2.  

How to cite: Mirkhani, R., Resch, C., Weltin, G., Heng, L. K., Mitchell, J., Clare Hood-Nowotny, R., and Dercon, G.: Effect of urease inhibitor and biofertilizer on nitrous oxide emission, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11242, https://doi.org/10.5194/egusphere-egu23-11242, 2023.

EGU23-11440 | ECS | Orals | ERE1.8

The potential to increase resilience by replacing feed imports with domestic food system by-products 

Vilma Sandström, Matti Kummu, and Florian Schwarzmueller

Many of the key feedstuff, such as oilseed meals or fishmeal, used in livestock and aquaculture production are highly traded commodities in global agricultural markets. The dependence on these imported inputs creates vulnerabilities to the production countries when disturbances on global trade flows occur. Increasing the feed use of the available food system by-products offers a solution to decrease the dependency and increase food system circularity and resilience. In this global study we combine trade data from various sources of the material flows in feed trade and estimate for the first time the potential to replace the imported feeds with a more efficient use of food system by-products from domestic production. The results highlight the materials and areas with most potential to guide and inform decisions when looking for solutions in the transition towards more sustainable food systems.

How to cite: Sandström, V., Kummu, M., and Schwarzmueller, F.: The potential to increase resilience by replacing feed imports with domestic food system by-products, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11440, https://doi.org/10.5194/egusphere-egu23-11440, 2023.

EGU23-12259 | ECS | Posters on site | ERE1.8

Effect of urease inhibitor and biofertilizer on wheat yield and related crop parameters 

Corinna Eichinger, Rayehe Mirkhani, Lee Kheng Heng, Jason Mitchell, Rebecca Clare Hood-Nowotny, and Gerd Dercon

Agricultural production must increase by 50% to support about 9 billion people by 2050. Previous studies show that integrated crop-soil management strategies can improve cereal yield by 30% without increasing nitrogen use. Sustainable practices and the application of environmentally friendly technologies can help to reach this point by improving resource use efficiency and increasing yield. For this purpose, the effect of urease inhibitor and biofertilizer were evaluated in this study as environmentally friendly technologies that can increase cereal grain yield.

In the spring of 2022, a field experiment was established at the experimental station of the University of Natural Resources and Life Sciences (BOKU), located in the east of Vienna, to determine the effect of urease inhibitor and biofertilizer on wheat production. A randomized complete block design including five treatments and four replicates was used in this study. Each main plot was 9 by 9 meters, and a buffer zone of 1.5 meters was implemented between each of the individual main plots. The treatments were: T1 (control treatment - without N fertilizer), T2 (Urea only), T3 (Urea+Urease Inhibitor (UI)), T4 (Urea+Biofertilizer), T5 (Urea+UI+Biofertilizer). All treatments received 50 kg N ha-1 at tillering stage (GS 31), except T1. In this study N-(n-butyl) thiophosphoric triamide (nBTPT) or “Agrotain” was used as UI and Azotobacter chroococcum or “AZOTOHELP” was applied as biofertilizer. To determine wheat yield (grain and straw), a 1.5 by 8 meter area was harvested in each main plot (9 by 9 meters). To measure other parameters including the number of tillers per square meter, 1000-grain weight (g), plant height (cm), spike length (cm) and numbers of grains per spike, a 1m-by-1m area was harvested within each main plot for all treatments.

The highest grain and straw yields were observed in the Urea+UI+Biofertilizer treatment, with a grain yield of about 20, 11, 8% higher, compared to the Urea, Urea+UI and Urea+Biofertilizer treatments, respectively. However, a significant difference in grain and straw yields was only observed between Urea and Urea+UI+Biofertilizer treatments. The grain and straw yields in the Urea+UI and Urea+Biofertilizer treatments were not significantly different from both Urea and Urea+UI+Biofertilizer treatments. The number of grains per spike and the weight of 1000-grain in the Urea+UI+Biofertilizer treatment showed an increase of about 20 and 11% respectively, compared to the Urea treatment, but these increases were not significant. Plant height in treatments that received nitrogen fertilizer was not affected by fertilization treatments, but spike length was affected. This study suggests that the use of urea fertilizer coated with urease inhibitor in combination with biofertilizer is a promising way for sustainable crop production in the lowlands of Austria.

How to cite: Eichinger, C., Mirkhani, R., Kheng Heng, L., Mitchell, J., Hood-Nowotny, R. C., and Dercon, G.: Effect of urease inhibitor and biofertilizer on wheat yield and related crop parameters, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12259, https://doi.org/10.5194/egusphere-egu23-12259, 2023.

EGU23-12478 | ECS | Orals | ERE1.8

Tracing the water footprint of food losses the in trade network: the case of wheat 

Francesco Semeria, Francesco Laio, Luca Ridolfi, and Marta Tuninetti

Food loss and waste is increasingly becoming a topic of great public concern: in 2011, FAO presented the estimate that around one third of the world’s food was lost or wasted every year and SDG 12 (“Sustainable consumption and production”) from Agenda 2030 includes among its targets to “halve per capita global food waste” and to “reduce food losses”. The impact on environmental resources is significant: in particular, 24% of total freshwater resources used in food crop production are lost in the different stages of food loss and waste. While in high-income countries food is mainly wasted at the consumer level, low-income ones record losses concentrated in the agricultural and post-harvest stages. Globally, food markets are telecoupled and globalized, so wasted food has effects on water resources in the whole supply chain, propagating along the trade network up to the countries of initial production, where water resources have been utilized, often through irrigation, altering the local hydrological cycle. The reconstruction of such network is one of the most challenging aspects of tracing the impact of food waste on water resources. The difficulties are due to the numerous food re-exports and nested supply chains, to the different origins of food waste (from production to distribution and consumption), and to the marked variability of the country-specific unit water footprints. As a key hypothesis, we assumed that in each country the ratio between imports and domestic production would be the same in both domestic consumption and exports, to cope with re-export feedbacks in the network. Focusing on the emblematic case of wheat and its derivatives (e.g., flour, bread, pasta), we were able to reconstruct the complex global network that connects losses and wastes at any stage along the supply chain with the corresponding wasted water resources.

Our results show that, for most countries, the network is very extensive and involves many states around the world. For example, in 2016 over 20 foreign countries employed their water resources to produce wheat which in turn was wasted as bread in Italy at the consumer level, accounting for around 15% of the bread’s water footprint (870 m3/t).  This highlights how much water resources are now globalized and that the waste of food in a country can impact even very distant water resources. We also quantify the contribution of each waste component, from agriculture’s field losses to consumers’ household wastes. For Italy, 54% of losses related to bread are at the consumption stage, while only 6% occur at the agricultural stage. Eventually, we present how the relative importance of each component varies, depending on the network of countries involved in the production, storing, processing, distribution and consumption of food.

How to cite: Semeria, F., Laio, F., Ridolfi, L., and Tuninetti, M.: Tracing the water footprint of food losses the in trade network: the case of wheat, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12478, https://doi.org/10.5194/egusphere-egu23-12478, 2023.

EGU23-12940 | Posters on site | ERE1.8

An evaluation of smartphone applications for LAI estimation to facilitate canopy state assessment in vineyards 

Georgios Ovakoglou, Ioannis Navrozidis, Vasileios Pyrgiotis, Nikos Kalatzis, and Thomas Alexandridis

Crop development and foliar density as expressed with Leaf Area Index (LAI) is an important source of information for disease prevention. Canopy density in vineyards has been correlated with disease incidence, mainly concerning the impact of high density on intra-canopy ventilation and levels of humidity. LAI data can be used together with other data sources, such as temperature, humidity, rainfall etc., to enhance disease predictive models and continuous monitoring of crops. To improve the crowdsourcing aspect of data collection from farmers and agronomists capturing in-field observations, this study was implemented aiming to evaluate LAI smartphone applications. The applications selected for testing and evaluation were smart fLAIr (https://sys.cs.uos.de/smartflair) and VitiCanopy (https://viticanopy.com.au), selected based on their applicability, subscription pricing, user-friendliness and continued support from the developers among all available Android applications. The smartphone applications were evaluated against LiCOR 2200C plant canopy analyzer (https://www.licor.com/env/products/leaf_area/LAI-2200C) to demonstrate the measurement accuracy of each. Sampling for this experiment was carried out in four plots (25 points/plot, 100 total) applying gaiasense smart farming services (https://www.gaiasense.gr/en/gaiasense-smart-farming), located in two irrigated commercial vineyards in Stimagka, southern Greece. The collected samples were representing various canopy states considering foliar density. Sampling took place during early morning hours (after sunrise) for the first two plots, while the remaining two plots were sampled after midday to early afternoon hours (before sunset). All sampling locations were recorded with geo-tagged photographs. A cap-view of 45o under clear-sky conditions was used for LiCOR2200C measurements and atmospheric scattering correction was applied, following a 4A measurement sequence protocol as described in the instruction manual (https://licor.app.boxenterprise.net/s/fqjn5mlu8c1a7zir5qel). FV2200 software (https://www.licor.com/env/support/LAI-2200C/software.html) was used to process the LiCOR dataset. Statistical analyses were performed after excluding 10% of total acquired samples as outliers. The results show that VitiCanopy has greater accuracy compared to fLAIr with a correlation coefficient of 0.65 over 0.25, while producing overestimated LAI values (mean diff = 0.74, p<0.0001). On contrast, fLAIr generated slightly underestimated LAI values (mean diff=-0.24, F=0.0155). Per plot analysis showed that measurements acquired earlier during the day (first two plots) provided higher correlation values (0.39<r<0.64), while those acquired after midday scored lower (r<0.12). This comes in agreement with relevant literature, suggesting that the ideal light conditions for accurate LAI measurements (under clear-sky conditions) is the earliest possible after sunrise. Although correlation values remained low to moderate (0.07<r<0.64), findings indicate that VitiCanopy performs more accurately than fLAIr and can be used as an alternative to costly and sophisticated equipment, however caution should be taken while standardising the optimal atmospheric/lighting conditions. This insight can be useful for disease predictive models, as well as farmers and agronomists who seek an accessible way to monitor LAI, potentially leading to spatially variable spraying applications. Future plans include the integration of LAI measurements as an additional parameter within the gaiasense’s Smart Farming solution aiming to enhance information richness of the existing operational pest infestation risk index calculation algorithms for vineyards.

This work was supported by EU-H2020 project ‘Resilient farming by adaptive microclimate management’ (STARGATE – 818187).

How to cite: Ovakoglou, G., Navrozidis, I., Pyrgiotis, V., Kalatzis, N., and Alexandridis, T.: An evaluation of smartphone applications for LAI estimation to facilitate canopy state assessment in vineyards, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12940, https://doi.org/10.5194/egusphere-egu23-12940, 2023.

EGU23-15016 | Orals | ERE1.8

A novel tool implementation to estimate the Land Use Sustainability for crops production under different climate change scenarios 

Joan Miquel Galve, Jesús Garrido-Rubio, José González-Piqueras, Anna Osann, Alfonso Calera, Maria Llanos López, Esteban Henao, David Sánchez, Jesús Puchades, Antonio Jesús Molina, Christina Papadaskalopoulou, Marina Antoniadou, and Dimitris Tassopoulos

The sustainability of crop production regarding different climate change scenarios will compromise actors and activities involved in agri-food systems. Furthermore, sustainable development was defined by the World Commission on Environment and Development as the ability to meet present demands without compromising the needs of future generations. In parallel, according to the Food and Agriculture Organization (FAO), land evaluation is the process of projecting land use potential based on its characteristics, and it has been the principal approach used worldwide to manage land use planning. Its use today is required due to changing needs and pressures from decision-making policies or agricultural market tendencies among others, so a rational use of natural land is a crucial goal for economic development. However, future climate change scenarios will modify the actual crop development conditions and must be tackled.

This paper presents two case studies at the river basin scale to determine the Land Use Suitability (LUS) analysis that is performed according to the FAO framework, thus, areas that are the most suitable for crops using GIS and multicriteria methodology that involves actual and future climatic conditions under different climate change scenarios, crop management practices and edaphological conditions for different crops. The tool developed generates a product that classifies areas suitable for a particular crop from a collection of maps and their corresponding thresholds. The approach involves standardizing the suitability maps, assigning relative importance weights to the suitability maps, and then combining the weights and the standardized suitability maps to obtain a suitability score.

In this paper, the wheat crop LUS at the Júcar River Basin (42,735 Km2, located in Spain) and the cotton LUS at the Pinios River Basin 11,000 km2, located in Greece) are evaluated. Once the LUS is estimated, a collection of yearly thematic maps over both river basins is ready for use by local stakeholders, regarding different climate change scenarios (RCP 4.5 and RCP 8.5).

These results are part of the EU Horizon 2020 project REXUS (Managing Resilient Nexus Systems Through Participatory Systems Dynamics Modelling), in which local stakeholders, from farmers to land use managers, are collecting and evaluating the information. Our final goal is to provide spatial information for future climate change scenarios that increase land-use knowledge and enhance decision-making policies.

How to cite: Galve, J. M., Garrido-Rubio, J., González-Piqueras, J., Osann, A., Calera, A., López, M. L., Henao, E., Sánchez, D., Puchades, J., Molina, A. J., Papadaskalopoulou, C., Antoniadou, M., and Tassopoulos, D.: A novel tool implementation to estimate the Land Use Sustainability for crops production under different climate change scenarios, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15016, https://doi.org/10.5194/egusphere-egu23-15016, 2023.

EGU23-15056 | ECS | Orals | ERE1.8

Usage of by-products and residues of the food system in livestock diets leads to savings in global land and water resources 

Camilla Govoni, Paolo D'Odorico, Luciano Pinotti, and Maria Cristina Rulli

Animal foods play an important role in human nutrition providing essential micro and macronutrients. In addition, animal-source foods cover 16% of the global food supply, so contribute to global food security. However, livestock consumes about 70% of the global agricultural land and one-third of the freshwater available for agriculture, thus fueling the debate on the competition between the food and the feed sector for the use of increasingly scarce natural resources. Several studies suggest that more efficient management in the food system can reduce competition and increase the global food supply without further pressure on resources. Here we propose a strategy consisting in the replacement of energy-rich food-competing feeds, such as cereals and tubers, with agricultural by-products and residues. Thus, we analyze both the current impact on land and water use for animal-source foods and the natural resources (i.e. land and water) saving associated with the replacement. To this aim, we collected data on regional feed use and the potential replacement of these feeds with actually available by-products and residues. Then, the collected data are combined with countries-specific crop yields and a dynamic spatially distributed and physically based agro-hydrological model to analyze the difference in the land and water use between the current baseline condition and the substitution scenario. Considering the replacement of five major cereals and cassava estimated to range between 11% to 16% of their feed use, the potential amount of fertile land and green water volume that could be saved ranges from 10% to 14%, while from 11% to 17% for the blue water volume. While Eastern Asia and North America would reduce their energy-rich feed crop consumption the most, would be Southern, Eastern, and South-Eastern Asia, and Eastern Europe that would benefit the most from the use of agricultural by-products and residues to save land and green water resources. As far as blue water is concerned, the highest savings are expected to occur in Asia, where cereal production is traditionally irrigated, although linked to unsustainable water withdrawals. Furthermore, the effect of trade on the consumption of natural resources, namely virtual land and water trade, is also explored, with feed crop production relocated through virtual resource flows. While Eastern Europe, Northern America, and South America appear as net land and green water exporters, Eastern and Western Asia and Southern Europe appear as net importers, and Western Europe, instead, as both an importer and exporter region through feed trade. On the other hand, Asia and Northern America appear to be net freshwater exporters. As the demand for livestock products grows over the next half-century, any strategy aimed at curbing the demand for primary commodities and making the food system more resilient has the benefit of reducing environmental impacts on both local and distant areas of the world but also the trade dependency of countries, in a time where global food security is threatened by several factors.

How to cite: Govoni, C., D'Odorico, P., Pinotti, L., and Rulli, M. C.: Usage of by-products and residues of the food system in livestock diets leads to savings in global land and water resources, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15056, https://doi.org/10.5194/egusphere-egu23-15056, 2023.

EGU23-15211 | ECS | Posters on site | ERE1.8

SEDIMENT REUSE FROM TROPICAL RESERVOIRS: assessing the suitability of sediment material for soil improvements and impacts of the practice on plant growth 

Braga Brennda, Arlena Bronsinsky, Saskia Foerster, and Pedro Medeiros

Due to the high rainfall variability in the Brazilian semi-arid region and the occurrence of long periods without rain, society has adopted techniques to cope with drought, with focus on the construction of surface reservoirs. However, silting is causing a decrease in the water storage capacity of those structures, reducing their depth, increasing water losses by evaporation and contributing to the degradation of water quality by adsorbed pollutants. In a context where mitigating solutions are necessary, removal of the nutrient-enriched sediment from the reservoirs’ beds and their subsequent reuse for soil fertilization have been proposed. To assess the potential of the sediment as fertilizer, maize plants were grown under controlled conditions in a greenhouse, considering: i) soil from the region where the sediment was collected with no amendments, ii) soil with 100% of the nitrogen recommendation provided by mineral fertilizer (iii) soil with sediment from São Nicolau reservoir (iii), soil with sediment from São Joaquim reservoir (iv). We observed higher relative chlorophyll content, plant growth and biomass production of maize plants from the soil with added sediment, with a similar behavior to plants growing in the soil with chemical fertilizer. We also found that the silt improves soil structure by increasing the water retention capacity of the soil. We have previously evaluated that this technique is economically feasible and can present savings of up to 30% in relation to traditional fertilization, depending on the characteristics of the sediment. However, sediments from the same hydrographic region may present high spatial variability in their physicochemical characteristics. Therefore, it is relevant to map the spatial distribution of the sediment characteristics. Recently, we demonstrated that diffuse reflectance spectroscopy might be useful to characterize sediments at lower costs and efforts than by laboratory analyses: for instance, regression models for electrical conductivity and clay content performed in the range of good to very good in the study region. A further promising approach is the application of spaceborne imaging spectroscopy to estimate the concentration of elements such as sodium, the electrical conductivity, the content of clay and organic matter in the sediment. The derived information can be used for informed decisions in the application of sediment reuse practice. For example, if the electrical conductivity of the sediment is higher than 4 dS/m, addition of sediment to the soil may prevent plant growth and, therefore, its reuse is not recommended. Thereby, sediment reuse can also potentially promote de-silting of reservoirs, reducing the carbon footprint associated with traditional fertilization and improving the water quality of small reservoirs, the main source of water supply for rural families, by removing nutrients that could return to the water column. In addition, the use of sediments may represent an alternative to increase agricultural production, being less susceptible to market price variation than commercial fertilizers. The CAPES/PROBRAL and the Deutscher Akademischer Austauschdienst (DAAD) are acknowledged for the financial support.

How to cite: Brennda, B., Bronsinsky, A., Foerster, S., and Medeiros, P.: SEDIMENT REUSE FROM TROPICAL RESERVOIRS: assessing the suitability of sediment material for soil improvements and impacts of the practice on plant growth, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15211, https://doi.org/10.5194/egusphere-egu23-15211, 2023.

EGU23-15582 | ECS | Orals | ERE1.8

Sustainable agricultural strategies to address limited freshwater availability and meet food demand in the Nile River Basin 

Martina Sardo, Maria Cristina Rulli, and Davide Danilo Chiarelli

Providing healthy food from a sustainable food system, while satisfying the demand of a growing population, is one of the major challenges of the century.  The limited agricultural land and water represent the main boundaries to meet the food demand of a growing population (Davis et al., 2014, 2017). Moreover, availability of natural freshwater is expected to furtherly decline in future due to climate change (Rodell et al., 2018) – especially in arid regions – and, thus, there is an urgent need to reshape the agricultural system to sustainably feed a global population approaching 9 billion people in the next century (Godfray et al., 2010).

Food security in the Nile Basin is strictly related to the availability of freshwater resources, which are increasingly threatened by climate change and future demographic trends. Currently, food production is insufficient to meet the population food demand, and all Nile countries are currently net food importers. Healthy food is also needed to address malnutrition within the poorest rural communities in the Nile countries. Countries in the Basin are highly affected by undernourishment - linked low dietary energy - iron-deficiency-induced anemia and diabetes. The agricultural sector is the largest consumer of the Nile waters and, thus, the state of the food system has profound implications for attaining water security in the Nile Basin (NBI, 2020).

In this study we suggest a sustainable agricultural strategy to enhance sustainable a food system within the Nile River Basin. We couple the WATNEEDS hydro-agrological (Chiarelli et al., 2020) model with a linear optimization algorithm to reshape the current cropland with the aim of producing more healthy food, with several benefits for the ecosystem (e.g., reduced irrigation water consumption) and human health. Cropland redistribution can be coupled with agricultural intensification and diet shift generating, at the meso-scale, benefits in terms of irrigation water savings and increase in food self-sufficiency. We first evaluated the amount of irrigation water and the crop production related to the current crop distribution and second, we identified potential differences in food production and water consumption between the current and optimized crop distributions. We use the WATNEEDS model to quantify spatially distributed crop water requirements, - namely blue and green water requirements - which are the volumes of water needed to compensate crop water losses through evapotranspiration. Our results show that crop redistribution increases food availability and, thus, the percentage of population sustained sustainably with the local agricultural production, reducing the pressure on the currently available renewable freshwater resources of the Nile.

How to cite: Sardo, M., Rulli, M. C., and Chiarelli, D. D.: Sustainable agricultural strategies to address limited freshwater availability and meet food demand in the Nile River Basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15582, https://doi.org/10.5194/egusphere-egu23-15582, 2023.

EGU23-15681 | Orals | ERE1.8

Coffee Agrosystems and Climate Change 

Raniero Della Peruta, Valentina Mereu, Donatella Spano, Serena Marras, and Antonio Trabucco

Coffee is one of the most important agri-food systems from a global economic point of view. Most of the production takes place on small and medium-sized farms and is the main source of income for many rural families in several developing countries. Areas suitable for coffee production are very biodiverse and ecologically important, thus negative impacts should be minimized.
Coffee production requires special environmental and climatic conditions. Current and future climate changes could cause problems for a sustainable production and result in lower yields. To overcome these problems, it is necessary to investigate the effectiveness of possible adaptation measures, such as intercropping with other tree species that can provide more shade to coffee plants and favour environmental sustainability. 
In order to study how such modifications could improve the resilience and sustainability of coffee production, the use of process-based models can be very useful. The DynACof model was developed specifically to simulate coffee farming systems, including phenological development, physiological processes related to flower and fruit production, carbon allocation, the effect of water availability, light and temperature, as well as management. We tested the DynACof model on some study areas in Mexico, Brasil and Rwanda and verified that the yield predictions were in line with the observations. We then developed a modelling tool where the model can be applied to entire geographical areas in a spatially explicit manner, using global climatic and soil datasets.
We used this tool to simulate yields in Latin America and Africa, both for the period 1985-2014 and for the period 2036-2065 using climate projections. Comparing the two periods, the model predicts a decrease in yields of about 28% in Latin America and about 12% in Africa. We then simulated specific management options (e.g. agroforestry shading vs intensive monocropping) to assess their efficacy in enhancing environmental sustainability and resilience to climate risks. These impact analyses will be crossed with socio-economic indicators for a more comprehensive climate risk assessment to support adaptation recommendations.

How to cite: Della Peruta, R., Mereu, V., Spano, D., Marras, S., and Trabucco, A.: Coffee Agrosystems and Climate Change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15681, https://doi.org/10.5194/egusphere-egu23-15681, 2023.

EGU23-15686 | Orals | ERE1.8

Elucidating climate change adaptation potential of improved maize (Zea mays L.) varieties with crop modelling 

Abel Chemura, Ponraj Arumugum, Eresi Kutesa Awori, and Christoph Gornott

The threats to crop yields are projected to increase under climate change and one of the most promising adaptation measures is for farmers to adjust their crop varieties over time to minimize climate risk. An improved or modern variety is a new variety of a plant species which produces higher yields, higher quality or provides better resistance to plant pests and diseases while minimizing the pressure on the natural environment. Selecting best maize varieties for various sites is also a good agricultural practice that can increase current yields in many low-productivity areas.  In this study, we aimed at identifying the climate change buffering potential of improved maize varieties using a spatialized DSSAT model using a case study across Uganda. We calibrate the model with observed weather data and then replace the weather files with climate projections from the ISIMIP3b. Model evaluation showed that the model performance was satisfactory with a correlation  coefficient (r) of 0.89, coefficient of determination (R2) of 0.79, index agreement (d) of 0.83 with observed yields. The impact of climate change on maize yield show spatial and temporal disparities with general trends showing that they worsen with time (2030 to 2090) and scenario (SSP1-RCP2.6 to SSP3-RCP7.0). At the national level, we project a yield loss of 6.2% (SSP1-RCP2.6) and 4.4% (SSP3-RCP7.0), by around 2030, 8.6% (SSP1-RCP2.6) and 14.3% (SSP3-RCP7.0) by around 2050, and 8.8% (SSP1-RCP2.6) and 26.8% (SSP1-RCP7.0) by around 2090. Switching to an improved variety results in at least double the maize yield under current climatic conditions (113.2%) compared to the current varieties, with maize yield exceeding 10 t/ha in the south-western, western and eastern parts of the country.  This positive yield effect was realized across all grids but substantially varied from around 10% to 500% yield change. Comparing the effect of climate change with an improved variety versus with a conventional variety shows it is always better to use an improved variety under climate change (positive effect), especially under worse case climatic conditions(2.9% and  8% yield buffering by 2090 under  SSP1:RCP2.6 and SSP3:RCP7.0 respectively) at national level. We therefore conclude that improved maize varieties offer a more durable solution to adapt to climate change and seed systems should therefore be strengthened to increase access to improved maize varieties for farmers.

How to cite: Chemura, A., Arumugum, P., Awori, E. K., and Gornott, C.: Elucidating climate change adaptation potential of improved maize (Zea mays L.) varieties with crop modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15686, https://doi.org/10.5194/egusphere-egu23-15686, 2023.

EGU23-16211 | ECS | Posters on site | ERE1.8

Management Options to Improve Drought Resilience in Sugar Beet 

Sabrina Santos Pires, Gernot Bodner, and Christine Stumpp

Weather-extreme events are increasingly common due to climate change, with longer periods of drought and periods of strong rainfall. Drought periods are a problem in agriculture with several crops suffering from qualitative and quantitative yield reduction depending on the crop growth stage. Sugar beet (Beta Vulgaris) makes up 20% of sugar production worldwide and is the main source of sugar in temperate regions, with a recent increase in its use for biofuel production. The search for drought-resistant varieties of sugar beet with lower water requirements is expanding, however substantial variability in drought resistance regarding yield and quality has not been found so far. The goal of this study was to develop strategies to improve yield security in sugar beet cultivation under low water availability conditions. Therefore, two field experiments were established at sites representative of Austrian sugar beet production (Oberhausen, Marchfeld; Guntersdorf, Weinviertel) over the course of two years, 2020 and 2021. The experiments involved combining breeding strategies (variety selection) with agronomic approaches (soil management, land cover, irrigation, fertilization) to investigate the sugar beet's response to water stress and assess the performance of different sugar beet varieties, leading to a more climate-resilient sugar beet crop. Direct methods of measuring soil hydraulic properties (e.g. via soil moisture sensors) and plant properties (e.g. stomata density and conductance) with stable isotope analysis for carbon and water were combined. As a result, a significant yield increase was found in irrigated plots. Nitrogen fertilization had a detrimental effect when applied extensively. A yield increase was obtained by soil coverage with wooden chips in both years and sites. Furthermore, the choice of variety also played an essential role, especially regarding the trade-off between drought resistance and yield.

How to cite: Santos Pires, S., Bodner, G., and Stumpp, C.: Management Options to Improve Drought Resilience in Sugar Beet, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16211, https://doi.org/10.5194/egusphere-egu23-16211, 2023.

EGU23-16316 | Orals | ERE1.8 | Highlight

Cross-border environmental impacts of agri-food systems and potential solutions towards sustainability: a case study of trade between Europe and Africa. 

Ertug Ercin, Brecht D’Haeyer, Corjan Nolet, Emrah Alkaya, Didem Mahsunlar, Tolga Pilevneli, and Goksen Capar

Some nations and regions, such as the European Union (EU), use food ingredients and agri-food products that are not produced within their borders while being essential for their food security and food systems. This product flow through international trade means that these regions are connected to water resources outside their borders. It also means they create subsequent environmental and social effects in the original production locations, a phenomenon called ‘cross-border impacts”.  For example, these imports can be a substantial part of existing problems of water depletion and pollution in producing regions since every step in the food system such as growing, harvesting, transportation, production, packaging, and retail consume and pollute water. Furthermore, agricultural production in exporting regions provides the lion’s share of greenhouse-gas emissions from the food systems.

This study first maps the cross-border environmental footprints of agri-food systems in Europe (water and carbon footprints) along the supply chain of major imported agri-food products from Africa. Second, it determines the vulnerability of these agri-food systems to climate change. Third, it identifies potential solutions to minimize the vulnerabilities and environmental impacts of the agri-food systems that are connecting Europe and Africa.

The study shows that the cross-border environmental impact of European agri-food systems on Africa is largely related to imports of oranges, potatoes, grapes, tangerines, and tomatoes. For example, the water footprint of this trade is approximately 5 km3 per year.  These products originate from water-scarce areas such as North Africa (Egypt, Morocco) and South Africa. Furthermore, climate change will reduce water availability in these regions, e.g., 20% less water is expected in North African countries by 2050.

Minimization of food loss and waste along the supply chain of the Europe-Africa trade is investigated as a potential solution to reduce the environmental footprint of this trade. It is found that around a 30% reduction in water footprint can be achieved by eliminating food waste at the consumer level in Europe. Further reductions in environmental impacts can be achieved if manufacturing and transportation losses are minimized as well, up to 10% and 20% reductions in the water footprint and carbon footprint, respectively. Another solution to reduce the footprint of agri-food systems is to source relevant products locally instead of importing from Africa. This option significantly reduces carbon footprints (up to 60%) but not much for water footprints (around 10% reduction). For some food items such as oranges, more water can be saved if they are imported from Africa rather than locally produced in Europe.

This study concludes that the sustainability of agri-food systems has a cross-border dimension, which is mostly neglected in national policies of sustainable production and consumption. The sustainability of such imported agri-food products can be understood by assessing their environmental impacts at production locations. Improving production efficiencies at exporting regions (e.g., reduction of production losses and waste) and minimizing waste of these products at consumer levels can help reduce the environmental consequences of this trade and help achieve our sustainability goals.

How to cite: Ercin, E., D’Haeyer, B., Nolet, C., Alkaya, E., Mahsunlar, D., Pilevneli, T., and Capar, G.: Cross-border environmental impacts of agri-food systems and potential solutions towards sustainability: a case study of trade between Europe and Africa., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16316, https://doi.org/10.5194/egusphere-egu23-16316, 2023.

With increasing global demand for oil and gas, the exploration of unconventional resource plays (shale oil and gas) continues to gain relevance. Such plays could be significant for maximising the production value in proven geological basins, allowing the exploration of a cleaner fossil fuel. Unconventional resources could play a part in the energy transition to lower-impact CO2 fuels while meeting current energy security needs.

For several decades, the UK North Sea has been a prolific oil and gas province, with numerous conventional oil and gas discoveries sourced predominantly by the Kimmeridge Clay Formation (KCF). In this study, we have used 3-D geostatistical modelling of the distribution of key geochemical and geomechanical properties for the KCF to investigate the potential of shale oil and gas plays within Quadrant 15 in the Outer Moray Firth region of the UK North Sea.

The utilized geochemical and geomechanical property logs were generated from sixteen selected drilled wells using machine learning and established property equations, while the top and base KCF structural depth maps used for modelling were created using grid- and isopach creation tools in Zetaware's Trinity software, an existing Base Cretaceous Unconformity (BCU) map of the UK North Sea and well top information from 58 wells within the study area.

The geostatistical property maps created for the KCF in Schlumberger’s Petrel software were then normalised and integrated to identity sweet spots for potential shale oil/gas exploitation, after the application of various cut-offs using standard industry thresholds for unconventional resources.

The modelling results suggest that the KCF show good potential for shale oil and gas exploitation within the central part of the Witch Ground Graben and limited areas of the Piper Shelf and Claymore-Tartan Ridge in the study area.  Further investigations on maturity, saturation and producibility will be conducted by 3-D basin modelling.

How to cite: Akinwumiju, A.: Sweet-spot mapping of the Kimmeridge Clay Formation in the UK North Sea for unconventional resource exploitation using a geostatistical modelling approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-63, https://doi.org/10.5194/egusphere-egu23-63, 2023.

EGU23-543 | ECS | Orals | ERE1.9

Subsurface mechanical modeling of Krishna Godavari basin using petrophysical properties of the rocks by utilizing 3D seismic and well log data sets 

Gagandeep Singh, Anjeeta Rani, William K. Mohanty, and Aurobinda Routray

Three-dimensional seismic data and well-log data analysis deliver complete information on the petrophysical characteristics of reservoir rock and its fluid content. The current study shows the combined interpretation of 3D seismic data and well log responses such as gamma ray, delay time (DT)- P wave and S wave, resistivity, neutron, density, and lithology logs from eight wells under the research area of Krishna-Godavari (KG) basin. The main target of the paper is focused on the prominent positive topographic features in the bathymetry data and on the porous and fractured/faulted hydrocarbon rocks. Fluid/gas migration characteristics like acoustic voids, chimneys, and turbid layers may be seen in the present mounds. Coherence, dip, curvature, and saliency attributes are used to enhance the discontinuities within the seismic volume. After then, well logs were used to identify the hydrocarbon-bearing zones. Finally, the seismic to well tie step was initiated, and the complete earth model of the given data was generated.

The goal of this paper is to describe the offshore KG basin reservoir areas, in a qualitative way using 3D seismic and well log data and its possible correlation with facies. The possible data and wells information are conjugated with other attributes, which are relatively recent methods in this field study, yet it is crucial to reducing geological uncertainty and predicting facies. The characterization of reservoirs using only the seismic volume (impedance dependent data) characteristics is difficult due to the shally environment of the area, which might obscure reservoir identification. As a result, combining a variety of techniques and data is important for better understanding geological settings and identifying meaningful geological features in the shally environment of the KG basin.

How to cite: Singh, G., Rani, A., Mohanty, W. K., and Routray, A.: Subsurface mechanical modeling of Krishna Godavari basin using petrophysical properties of the rocks by utilizing 3D seismic and well log data sets, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-543, https://doi.org/10.5194/egusphere-egu23-543, 2023.

EGU23-1319 | ECS | Posters on site | ERE1.9

Effects of Thermal Shocks on Cement for CCS under Confined and Unconfined Conditions 

Kai Li and Anne Pluymakers

In wells for carbon capture and storage (CCS), fractures can develop in the cement due to strong thermal shocks upon pressurized CO2 injection into the subsurface. The network of these fractures forms leakage pathways that can impair well integrity, and thus impede successful geological storage of CO2. In this study, we investigate how thermal shocks affect cement integrity under unconfined and confined conditions. Solid cylindrical samples (Φ3 x 7 cm) and samples of the same size but with a hole (Φ4 mm) in the middle are used. All samples are prepared using class G cement with 35% BWOC silica flour by Halliburton AS Norway, in accordance with API specification 10B-2. In unconfined experiments, we either quench the solid sample into cold water or inject cold water through the hollow-cylindrical sample to induce thermal shocks. In confined experiments, we mount the hollow-cylindrical sample in a triaxial deformation setup with confining pressure and axial stress, then inject cold water to induce the shocks. Before the shocks in all experiments, samples have been heated to 130°C. The temperature of the water is 5°C to achieve a strong thermal shock as possible. We produce eight cycles of thermal shock in all experiments. To study the extent of cracking, we use a micro-computed tomography (μ-CT) scanner to characterize the network of pores and fractures in the cement before and after experiments.

Under unconfined conditions, fractures develop in cement after thermal shocks in both quenching and injecting-through experiments. Both experiments generate sufficient thermal stresses to cause cracking in cement. In quenching, multiple fractures are initiated at different orientations. However, by injecting cold water through the sample, only one longitudinal fracture is created. This fracture is intersected with the injecting hole, where most thermal stresses are built up. The volume ratio of pores and fractures in samples increases to 2.74% by quenching and 1.84% by injecting through respectively, from 0.38%. Compressive strength decreases from 97.9 MPa for intact samples to 53.9 MPa after quenching, and 83.6 MPa after the injecting-through experiment. Under confined conditions, we carry out injecting-through experiments to bring about thermal shocks under 1.5 and 10 MPa confining pressure. We haven’t observed any failure in cement integrity under either confinement. Instead, compressive strength increases by 6.2% and 7.2%, and the volume ratio of pores and fractures decreases by 7.7% and 18.2% after the experiment under the confinement of 1.5 and 10 MPa, respectively. This means the presence of confining pressure not only hinders the adverse effects of thermal stresses on cement integrity but also compacts the samples. Higher confining pressure causes more compression to the sample, then resulting in greater strength.

How to cite: Li, K. and Pluymakers, A.: Effects of Thermal Shocks on Cement for CCS under Confined and Unconfined Conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1319, https://doi.org/10.5194/egusphere-egu23-1319, 2023.

EGU23-1627 | Orals | ERE1.9

Viscosity-reducing and Biosurfactant-producing Bacterial Consortia Isolated from Low-permeability Reservoir in Ordos Basin 

Ziwei Bian, Zena Zhi, Xiangchun Zhang, Yiqian Qu, Lusha Wei, Yifei Wu, and Hanning Wu

Many bacteria have been proved to change physical (viscosity, wettability, and tension), and compositions of crude oil, which can make it easier for oil to be released from rock pores and achieve the purpose of improving recovery, which is called Microbial Enhanced Oil Recovery (MEOR). Our team has previously isolated six emulsified and viscosity-reducing bacteria (Bacillus. sp.) in low permeability layers (Chang 4+5 and Chang 6) of Ordos Basin. However, environmental tolerance of the strains is limited, and the components of crude oil used by the strains were also different. The combination of strains of different species and genera may enhance the effects of single bacteria, surpass the tolerance upper limit, and optimize the viscosity reduction and degradation. Therefore, in this study, it is extremely necessary to study the bacterial consortium. Two consortia were obtained and each consortium consisted of three bacterial strains and was designated as Consortium A (51+61, 61+H-1, 51+H-1; A-ALL) and Consortium B (34(2)+42, 34(2)+A-3; 42+A-3. B-BLL). The performance of the mixed strains was evaluated by the analysis of change in emulsification rate, crude oil composition, viscosity, and the tolerance (temperature, salinity, and pH) though GC-MS, rotational rheometer, and other methods. The results showed that bacterial consortiums had higher alkali resistance and could survive temperatures of 55 °C and salinity of 50 g/L in comparison to single bacterium. The emulsification rate was 22%-48%. Consortium B has better effects than Consortium A. The viscosity reduction rate of the Consortium A after 7 days was exceeded 30% as a whole, and the rate of Consortium B was more than 35%. The crude oil of Consortium B is basically non-stick to flask. Compared with single bacteria, the utilization components of crude oil to bacteria are still different, including both long chain hydrocarbons and short chain hydrocarbons. However, the proportion of long chain n-alkanes is further reduced compared with that of single bacteria, and the highest ratio is reduced by 23.81% (B-ALL). Overall, the bacterial consortium outperforms the single strain in terms of tolerance, viscosity reduction, and degradation, which further optimizes the application of MEOR.

How to cite: Bian, Z., Zhi, Z., Zhang, X., Qu, Y., Wei, L., Wu, Y., and Wu, H.: Viscosity-reducing and Biosurfactant-producing Bacterial Consortia Isolated from Low-permeability Reservoir in Ordos Basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1627, https://doi.org/10.5194/egusphere-egu23-1627, 2023.

EGU23-1648 | ECS | Posters on site | ERE1.9

The CO2 storage in coal seams at the influence of coal fines migration 

Qian Wang, Jian Shen, Paul.W.J. Glover, and Piroska Lorinczi

Abstract: the pressure of the coal seam decays to a certain value due to the production of CH4, the production wells are switched to CO2 injection wells. The injection of CO2 can improve the CH4 recovery and realize the CO2 geological storage.The reverse migration of coal fines produced in the CH4 development stage can be caused by CO2 injection, which blocks the pore-thorats and fractures in coal seams and increases the difficulty of CO2 injection. We carried out experiments on coal fine migration and CO2 injection and storage at reservoir conditions on the simulated coal seam, which was a composite core composed of different types of coal. We focus on the migration of coal fine in simulated coal seam and the impact on CO2 storage. The experiment results show that, the permeability of the combined core, which is composed of proppant fractured coal, fractured coal and matrix coal in turn, decreases by 40.6% after being injected with 300ml of coal fine suspension with a concentration of 1g/1L. This is due to the deposition or capture of coal fines during the suspension injection, resulting in surface adsorption, bridging blockage, and direct blockage in the pore space, which seriously damaged the connectivity of the coal pore space. The proppant fractured coal can filter 77.1% of the coal fines in the suspension, and the fractured coal rock can filter the remaining 23.9% of the coal fines. The average CO2 storage capacity and CO2 storage efficiency of the composite core increased by 4.47 cm3·g-1 and 10.8%, respectively after subsequent CO2 injection into the composite core. The corresponding injection pressure difference also increased by 32.5%, and a CH4 recovery improvement of 13.6% is obtained.The migration and balockage of coal fines lead to the most significant improvement of CO2 storage in fractured coal (14.4%), followed by proppant fractured coal (10.3%), and the worst improvement of CO2 storage in matrix coal (3.4%). The migration of coal fines improves the CO2 storage effect in fractured coal seams to a certain extent, but increases the difficulty of CO2 injection, which is not conducive to the CO2 storage of the reservoir.

Keywords: CO2 storage, coal seams, coal fines migration, proppant fracture

How to cite: Wang, Q., Shen, J., Glover, P. W. J., and Lorinczi, P.: The CO2 storage in coal seams at the influence of coal fines migration, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1648, https://doi.org/10.5194/egusphere-egu23-1648, 2023.

EGU23-2016 | Posters on site | ERE1.9

GEOMODELATOR – from static geologic models to structured grids for numerical simulations 

Benjamin Nakaten and Thomas Kempka

Conversion of static geologic models into numerical simulation grids is a pre-requisite to undertake site-specific assessments of geologic subsurface utilisation in terms of risk assessments, design and operational optimisations as well as long-term predictions.

GEOMODELATOR is a Python-based Open Source software package which enables modellers to translate static geologic models into regular structured simulation grids with element partitions following a complex model geometry.

For that purpose, geologic models generated by means of Geographic Information Systems (GIS), Computer-Aided Design (CAD) or other specific geologic modelling software packages are integrated in form of point cloud data together with the desired structured simulation grid geometry.

GEOMODELATOR maps geometric features such as lithologic horizons, faults and any kind of other geometric data by 3D Delaunay triangulation onto the pre-defined grid element centres, and provides the modeller with Visualization Toolkit (VTK) data and Python numpy arrays for visual model inspection and their direct application in numerical simulations, respectively.

The present contribution shows the application of GEOMODELATOR to different numerical simulation studies addressing fluid flow as well as transport of heat and chemical species in geological subsurface utilisation.

How to cite: Nakaten, B. and Kempka, T.: GEOMODELATOR – from static geologic models to structured grids for numerical simulations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2016, https://doi.org/10.5194/egusphere-egu23-2016, 2023.

EGU23-2535 | ECS | Orals | ERE1.9

Composition of pure shale oil with medium-high maturity 

Ming Li, Ming Wang, and Jinbu Li

Continental shale oil can be divided into two categories according to vitrinite reflectance of kerogen: medium-high maturity (Ro > 0.9%) and medium-low maturity (Ro ≤ 0.9%). Due to high ratio of gaseous (C1-5) and light hydrocarbons (C6-14), high GOR and overpressure of the shale section, medium-high maturity shale oil has commercially productivity, which is considered as the target of unconventional resources in China. Shale oil composition is the basic and key parameter for resource evaluation, prediction of favorable areas, well location and field development plan. However, in shale oil composition research projects, the samples used and the analytical methods are quite different, and evaluation standard has not been established, which has restricted the exploration and exploitation of continental shale oil in China.

To understand this effect, we took the first member of Qingshankou Formation (Late Cretaceous) in Songliao Basin in eastern China as the target section. The section develops pure shale oil at a burial depth of 2000-2500m, with vitrinite reflectance of kerogen (Ro) of 1.20%-1.70% and high clay minerals content (40 wt%-60 wt%). We performed four sets of experiments on molecular composition of shale oil, including oil produced from shale section, the full-closure coring shale, the conventional coring shale and extracted hydrocarbons of shale with chloroform. The crude oil and saturated hydrocarbons (extracted hydrocarbons) separated by chromatographic column were directly analyzed by gas chromatography. The full-closure coring and conventional coring shale samples were conducted TG-GC (thermogravimetry-gas chromatography) experiment, where the powder samples were thermally desorbed at 300 ℃ for 3 minutes.

The experimental results show that carbon number of n-alkanes in crude oil is 4–38. The carbon number of n-alkanes in full-closure coring shale is 1–26, and it contains a large amount of gaseous and light hydrocarbons, accounting for up to 60 wt%–80 wt%. It is worth noting, however, that due to the loss of gas and light hydrocarbons in conventional coring, the carbon number of n-alkanes in conventional coring shale is 11–26, and the main peak carbon is 13–16. In the process of shale placement in core library, extraction and concentration, a large amount of hydrocarbons are lost. Through chromatographic analysis, carbon number of n-alkanes in saturated hydrocarbons is 15-38, and the main peak carbon is 18–22. C15- components are totally lost in extraction (Figure 1).

The comparison data we assembled show that shale oil components obtained from different samples vary significantly, especially for medium-high maturity shale containing large amounts of gaseous and light hydrocarbons. The heavy hydrocarbon components (C15+) can be determined by combining the produced oil with extracted hydrocarbons, and the gaseous and light hydrocarbons retained in shale can be determined by combining the produced oil with TG-GC analysis for full-closure coring shale. Pressure-retained coring or full-closure coring is indispensable for obtaining shale oil components in place.

Figure 1 (a) Gas chromatogram of oil produced from shale section; (b) TG-GC chromatogram of conventional coring shale sample; (c) TG-GC chromatogram of full-closure coring shale sample; (d) Gas chromatogram of saturated hydrocarbon extracted from shale sample.

How to cite: Li, M., Wang, M., and Li, J.: Composition of pure shale oil with medium-high maturity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2535, https://doi.org/10.5194/egusphere-egu23-2535, 2023.

EGU23-3107 | ECS | Orals | ERE1.9

Stereoscopic Development Adjustment Mode for Enhanced Oil Recovery in Mature Multi-Layer Oilfield 

Lingbin Lai, Cunyou Zou, Zhibin Jiang, Haibin Su, Xuyang Zhang, Songlin Li, and Hualing Zhang

After a long period of water flooding development, oilfields will enter the production stage of "high water cut, high recovery degree, and low oil recovery rate". On the one hand, due to the displacement effect of the water injection, some oil layers already reached the water flooding limit. On the other hand, due to the effect of reservoir heterogeneity, dominant seepage channels, and imperfect injection-production well pattern, some oil layers are enriched with a large amount of remaining oil. Unbalanced production of reservoirs and difficulty in development and adjustment are common problems in mature oilfields. Mature multi-layer oilfields generally develop many sets of oil-bearing layers vertically. After a long water injection period, the water-flood law and the remaining oil distribution are complex, and the production of different well patterns or strata varies greatly. Through strata and well pattern reorganization, combined with the evaluation results of water flooding adjustment potential, some reservoir engineers and researchers established a stereoscopic development adjustment mode for enhanced oil recovery in mature multi-layer oilfields. This paper summarizes the main technologies of stereoscopic development adjustment mode for enhanced oil recovery in mature multi-layer oilfields. The main technologies of stereoscopic development adjustment mode include research on the remaining oil distribution, evaluation of water flooding adjustment potential, selection of tertiary oil recovery methods, reorganization of strata and well pattern, and optimization of timing from water flooding to tertiary oil recovery, etc. For strata with low water flooding adjustment potential, the tertiary oil recovery well pattern is reorganized and tertiary oil recovery is adopted to improve oil recovery. For strata with large water flooding adjustment potential, the water drive well pattern is reorganized and water flooding development is used to excavate the remaining oil. As for strata with general water flooding adjustment potential, the tertiary oil recovery well pattern is reorganized and water flooding development is used to excavate the remaining oil first, and then transfer to tertiary oil recovery at the proper time. The stereoscopic development adjustment mode is applied to test block K of Q reservoir which is a mature multi-layer oilfield. After stereoscopic development adjustment, the development effect of test block K meliorates. It is estimated that the EOR will be increased by more than 8% after stereoscopic development adjustment in test block K.

How to cite: Lai, L., Zou, C., Jiang, Z., Su, H., Zhang, X., Li, S., and Zhang, H.: Stereoscopic Development Adjustment Mode for Enhanced Oil Recovery in Mature Multi-Layer Oilfield, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3107, https://doi.org/10.5194/egusphere-egu23-3107, 2023.

EGU23-3408 | Orals | ERE1.9

Optimising the drilling process for geothermal wells using legacy oil field data and machine learning 

Andrew Kingdon, Matthew Arran, Mark Fellgett, Shahin Jamali, Henning Knauer, and Kevin Mallin

Deep geothermal heat represents a massive opportunity to provide low-carbon district heating for towns and cities. Space heating represents a large percentage of total energy use in Northern Europe; nearly 40% of all UK energy use (BEIS, 2022) is for heating, predominantly from natural gas. Global pressures on the international gas market and the urgent need to decarbonise the heating system to deliver NetZero highlight the need for identifying renewable heat sources to replace gas.

However, finding reliable high temperatures requires drilling to several-kilometres depth. Achieving sustainable heat supply, without depletion, means that wells must intersect deep permeable strata which are impossible to detect from the surface. Well prognosis is therefore heavily reliant on data from legacy drilling. Drilling is always an expensive process and any operational issues can impose significant additional costs, as rigs capable of drilling such boreholes have rental rates of many €1000s per day. Even when the drilling is completed, financial returns are slow and reaching profit takes years. Therefore, reassuring investors requires de-risking such projects through mitigating avoidable additional costs.

Digital data from wells penetrating many kilometres are needed for understanding subsurface processes. Only small numbers of deep geothermal wells have been drilled, so the best alternatives are legacy hydrocarbon exploration boreholes; these are good analogies for geothermal wells as they rely on permeability at depth. Such legacy hydrocarbon data are increasingly openly available through National Data Repositories (NDR) and/or Geological Survey Organisations. 

The EU Horizon programme funded OptiDrill project (101006964) is using legacy well data to optimise the drilling process, by linking drilling parameters with petrophysical data to understand the constraints upon the drilling processes. This will allow causes of interruptions to drilling and unnecessary down-time to be assessed and hopefully eliminated.

NDR archives have been trawled for modern drilling and logging data that admits optimal analysis. An Isolation Forest machine-learning algorithm was used to analyse Measurement-While-Drilling derived Rate-of-Penetration data and geophysical log data, identifying zones of anomalous responses quickly and without supervision. Examination of newly available daily drilling reports (DDR) data, from the NDR, allows these anomalous responses to be associated with breaks in drilling operations and their causes to be understood. This allows both refinement of the anomaly-detection algorithm for the identification of drilling problems, and differentiation between problems caused by drilling or geological issues and those caused by operational and logistical difficulties (e.g. procurement delays). Where drilling issues are identified these can be used to develop remediation strategies for future wells drilled in similar conditions, through revised drilling programmes and optimised well designs that minimise avoidable drilling operations such as unnecessary round trips etc.

How to cite: Kingdon, A., Arran, M., Fellgett, M., Jamali, S., Knauer, H., and Mallin, K.: Optimising the drilling process for geothermal wells using legacy oil field data and machine learning, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3408, https://doi.org/10.5194/egusphere-egu23-3408, 2023.

Reservoir heterogeneity is one of the key geological problems in the process of oil and gas exploration and development of clastic rocks. Understanding reservoir heterogeneity is imperative to improve the effectiveness of exploration and development. The primary porosity calculation model proposed by the authors in the previous study is used to calculate the primary porosity of samples from modern braided river sands and sandstone outcrops of braided sand bodies, and the primary porosity heterogeneity (PPH) model of the braided sand body is established. The architectural-elemental structures of braided sand bodies have obvious control effects on the distribution of its primary porosity heterogeneity. The central braided channel and braid bars have strong primary physical properties; the primary porosity is high and always greater than 38%. The contact areas between the braided channel and braided bars have a low value of primary porosity and are always lesser than 33%. The distribution characteristics of the present porosity of braided river reservoirs are also influenced by sedimentary architecture. To compare the relationship between PPH, present porosity heterogeneity (pPH), and sedimentary architecture (SA), the images of PPH, pPH, and SA were digital, graying, and normalized. The digital image Q-Q plots of the distribution probability of PPH, pPH, and SA are calculated. The results show that: the Q-Q plots of the probability distribution of present porosity and architectural-elemental structures (or lithofacies) can reflect the influence and degree of primary porosity and diagenesis on the present heterogeneity of the reservoir. The Q-Q plots of distribution probability primary porosity and present porosity identify the distribution areas; the points are always distributed on different lines. The line ‘y = x’, is derived from compaction and primary porosity; the line ‘y = ax, a > 1’, is derived from diagenesis, which is unfavorable to the reservoir porosity preservation (such as cementation); the line ‘y = ax, a < 1’ is derived from diagenesis, which is beneficial to reservoir porosity preservation (such as dissolution). Based on the Q-Q plots of distribution probability, the influence from primary porosity and diagenesis can be quantitatively analyzed. The influence of primary porosity on pPH in braided sand bodies of Ahe formation (Kuqa depression), middle Jurassic fluvial sandstone (Datong basin), and Karamay Formation (Junggar basin) were 19%, 90%, and 10%, respectively. A quantitative probability distribution Q-Q model of reservoir PPH and pPH is effective for reservoir physical modeling.

How to cite: Yiming, Y., Liqiang, Z., Shuai, J., and Zuotao, W.: The primary porosity heterogenetic model of braided river sandstone reservoirs and its influence on the present porosity heterogeneity in the Kuqe depression, Tarim basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6856, https://doi.org/10.5194/egusphere-egu23-6856, 2023.

EGU23-7034 | Posters on site | ERE1.9

Study on Hydraulic Resistance Damage Law of External Liquid Intrusion in Tight Sand Conglomerate Reservoir 

Jianbang Wu, Shenglai Yang, and Qiang Li

In geological resource exploitation engineering such as reservoir development, the intrusion of foreign liquid will cause water lock damage to the formation rock structure, which affects the effect of reservoir transformation such as CO2 sequestration. The tight sand conglomerate reservoir is characterized by high content of expansive clay minerals, high capillary pressure, small pore throat, and serious heterogeneity, which leads to serious water lock damage. The extent, mechanism and reasonable prediction of damage are the concerns of the engineering community.
In view of this problem, this study uses the laboratory long core experiment method based on nuclear magnetic resonance (NMR) monitoring to simulate and study the reservoir damage law before and after the invasion of foreign liquid into the formation. The damage distance of liquid resistance and influencing factors were studied, and a prediction model was established. The long core experiment used drilled natural cores with a total length of 45 cm that were spliced from short cores with a diameter of 2.5 cm. A total of five pressure points were set up at 10 cm intervals to monitor the pressure gradient. The pressure gradient changes along the long core after saturated oil and water intrusion were tested separately. A new method of calculating the range and degree of water lock damage zone based on pressure gradient was established. According to the damage control factors obtained from the experimental study, the prediction model of water lock damage with the transformation from multiple nonlinear problems to linear problems is established by using permeability, porosity and content of water-sensitive clay minerals as input conditions.
The results show that the physical property of reservoir plays a decisive role in the damage distance of liquid resistance. The foreign liquid intrudes into the formation has obvious characteristics of "three zones", and the "pressed liquid stop zone" is the main factor controlling the damage degree of liquid resistance. Physical property, lithology and expansibility clay mineral content together constitute the 0-1 judgment value to determine the time-varying damage of fluid resistance in reservoir. The accuracy of the established multiple nonlinear regression prediction model of liquid resistance damage is greater than 80%, which can be used to quantitatively predict the liquid resistance damage degree of underground reservoir when it is difficult to conduct indoor simulation experiments in the evaluation of water intrusion damage degree.

How to cite: Wu, J., Yang, S., and Li, Q.: Study on Hydraulic Resistance Damage Law of External Liquid Intrusion in Tight Sand Conglomerate Reservoir, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7034, https://doi.org/10.5194/egusphere-egu23-7034, 2023.

EGU23-8226 | ECS | Posters on site | ERE1.9

Hydrogeochemical impacts of pumped hydropower storage in open-pit lignite mines 

Tobias Schnepper, Michael Kühn, and Thomas Kempka

Large-scale energy storage is becoming more important due to the increase in electricity generation from renewable sources and the related grid balancing requirements. In this context, Pumped Hydropower Storage (PHS) in former open-pit lignite mines can substantially contribute to energy supply safety. Assuming an average storage capacity of 150 MW per open-pit mine, PHS could generate a power output of at least 6 GW in European mines which will be abandoned in the next two decades. Experiences from mine-flooding across Europe demonstrate that hydrogeochemical processes can become a critical environmental and economic factor for the realisation of such projects. Depending on sulphide and oxygen availability, buffer capacities and dilution processes, mine waters with increased acidity as well as elevated sulphate and metal concentrations can pose a threat to adjacent ecosystems, groundwater resources and the installed PHS infrastructure.

We present a generic parameter study by means of numerical simulations to predict changes in the mine water composition as a result of PHS operation in different hydrogeochemical settings. Published datasets on hydrogeochemical, hydrogeological and technical conditions with a focus on German mines were applied for model parametrisation. A reaction path model was developed that accounts for initial mine flooding, inflows and outflows as well as pumping and release cycles between the two reservoirs. The simulations were run until chemical equilibrium was achieved in the lower reservoir.

Simulation results indicate that the long-term availability of buffer capacities in the reservoir water and adjacent sediments determine the development of acidic or neutral mine waters. Sulphate concentrations are mainly influenced by dilution processes, emphasizing the relevance of considering additional in- and outflows. Depending on these fluxes as well as oxygen availability and initial sulphide concentration in the mine sediments, the time to reach chemical equilibrium in the lower reservoir varies significantly from several weeks to months. Furthermore, the dissolution of sulphides and carbonates as well as the precipitation of iron (oxy)hydroxides may affect the properties of the open-pit slope sediments. Their long-term stability may be altered, based on their initial mineral concentration and hydraulic conductivity.

In summary, potential impacts on water quality in the PHS reservoirs have been investigated under different hydrogeochemical settings. We conclude that, under specific boundary conditions such as the availability of sufficient buffer capacities and dilution by controlled inflows and outflows, PHS operation in abandoned open-pit coal mines can be realised from an environmental perspective.

How to cite: Schnepper, T., Kühn, M., and Kempka, T.: Hydrogeochemical impacts of pumped hydropower storage in open-pit lignite mines, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8226, https://doi.org/10.5194/egusphere-egu23-8226, 2023.

EGU23-8407 | ECS | Orals | ERE1.9

Multi-salinity core flooding study in clay-bearing sandstones, a contribution to geothermal reservoir characterisation 

Daniela Navarro-Perez, Quentin Fisher, Piroska Lorinczi, Samuel Allshorn, and Carlos Grattoni

Geothermal reservoir characterisation benefits from the oil and gas petrophysics experience in areas such as porosity and permeability estimation, rock-fluid interactions etc.. Permeability is the crucial parameter in assessing water transmissibility with geothermal reservoirs. Permeability impairment is a key worry due to rock-fluid interactions within the reservoir life cycle management. The laboratory techniques help in recreating the reservoir conditions and determining formation damage. Uncertainty increases for tight geothermal reservoirs (permeability < 1 mD), which often contain significant amounts of clay that reacts with water or ionic species during hydraulic fracturing used in Enhanced Geothermal Systems.

Clay-bearing sandstones are complex reservoirs since their clay minerals actively interact with water, causing formation damage by clay swelling and migration mechanisms. Core flooding experiments study the clay minerals' behaviour in different water conditions - e.g. salinity, electrolytes species, pH, and temperature - helping to understand the impact of clays on reservoir quality and identifying optimal conditions to reduce formation damage.

A multi-salinity experiment was undertaken to study the clay effect of three tight clay-bearing sandstones, samples A, B and C, of different reservoir provenance. Sample A has a core porosity of 18%, gas permeability of 1.28 mD, and 15.5%v/v of XRD clay minerals and kaolinite as the primary group. Sample B has a core porosity of 20.2%, gas permeability of 0.56 mD, and 37%v/v of XRD clay minerals and chlorite as the primary group. Sample C has a core porosity of 18.8%, the gas permeability of 1.95 mD, and 36.3%v/v XRD clay minerals and mica as the primary group. The experiment consisted of flooding brine with constant inflow at different salinities and monitoring the rock resistance, pressure drop, and outlet brine conductivity. High- and low-salinity batteries were flooded, ranging from 200,000-75,000 and 50,000-0 ppm NaCl respectively, at a constant room temperature of 21⁰C. In addition, the brine permeability was measured in steady- and unsteady-states techniques, and pore size distribution was NMR scanned at each run per battery.

Permeability impairment increased in all samples. Samples A (kaolinite) and C (mica) show a staggered increase in the salinity range. In contrast, sample B (chlorite) shows a peculiar upside-down trend in the low-salinity range. Clay migration was detected in the last brine runs since fines grain were released in the outflow. NMR T2 distribution shows a bimodal pore distribution for samples B and C, and the pore-throat connectivity rearranges as salinity decreases in both samples, indicating a clay swelling mechanism. The cation-exchange capacity (CEC) of samples A and C resulted in 3.7 and 3.6 meq/100g, respectively, and sample B was 71.5 meq/100g. CEC values are directly related to the clay mineral content. The highest CEC (sample B) relates to the upside-down permeability impairment with clay swelling. This investigation contributes to the geothermal reservoir characterisation in understanding how the water salinity controls the clay effect in tight clay-bearing sandstone reservoirs.

How to cite: Navarro-Perez, D., Fisher, Q., Lorinczi, P., Allshorn, S., and Grattoni, C.: Multi-salinity core flooding study in clay-bearing sandstones, a contribution to geothermal reservoir characterisation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8407, https://doi.org/10.5194/egusphere-egu23-8407, 2023.

EGU23-9352 | ECS | Posters on site | ERE1.9 | Highlight

Repurposing of idle wells from the oil and gas industry into deep borehole heat exchangers 

Nora Koltzer, Johannes Schoenherr, Maximilian Sporleder, Sebastian Andreas Steininger, Marcel Halm, Michael Kettermann, and Florian Wellmann

The motivation behind this study is to repurpose idle wells from hydrocarbon exploration and production to provide heat for end users being located near the idle well. This is possible by prolonging the value-added chain of idle wells from the gas and oil industry by re-completion as geothermal closed loop wells. This is the most efficient way to produce green energy without drilling new wells by saving the carbon emission and costs of building a new geothermal well.

With this feasibility study we quantify the concept of re-completing idle wells in the North German Basin (NGB) into deep coaxial borehole heat exchangers. With numerical models of two typical geological settings of the NGB and two different completion schemes it was possible to simulate the thermal performance over a lifetime of 30 years. The calculated heat extraction rates are in the range of 200 kW to 400 kW with maximum values of up to 600 kW. This is higher than from already installed deep borehole heat exchangers. Sensitivity analyses demonstrate that flow rate, injection temperature and the final depths of re-completion are the most impacting parameters of thermal output determination.

In the final project stage, the heat demand around two exemplary boreholes was mapped and possible heating networks were simulated. The initial production costs for heat are comparable to other renewable energy resources like biomass and - depending on distance between source and user – well competitive against current gas prices. These calculations highlight not only the environmental valuable motivation behind the concept of repurposing idle wells but could also save capital expenditures for the geothermal industry.

Using a vacuum isolated tubing characterized by very low thermal conductivity of 0.02 W/(m*K), would make it possible to use the geothermal resources even more efficiently from idle wells. This project highlights the major potential of usable geothermal resources in already installed deep wells. The application has almost no geological risk, as the concept is independent of reservoir uncertainties like permeability and reservoir fluid composition, drilling risks are skipped completely and it is realizable at any location.

How to cite: Koltzer, N., Schoenherr, J., Sporleder, M., Steininger, S. A., Halm, M., Kettermann, M., and Wellmann, F.: Repurposing of idle wells from the oil and gas industry into deep borehole heat exchangers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9352, https://doi.org/10.5194/egusphere-egu23-9352, 2023.

Power-to-Methanol is considered as an additional option to Power-to-Gas to convert surplus energy from renewable sources and the electric grid into storable energy carriers. In this context, methanol is an alternative fuel to power combustion engines, and it can be applied to produce chemical feedstock such as formaldehyde required for polymer production, hydrocarbons, gasoline and olefines, as well as gasoline additives and especially as an energy carrier and carbon sink.

As long-term storage of energy carriers is required to realise the transition of the energy sector to renewable sources scheduled in the European Union, the fact that storage of methanol requires less operational and safety efforts compared to natural gas or hydrogen is a significant benefit, i.e. methanol does not require any compression prior to its injection into geologic subsurface reservoirs, while being biodegradable and of generally low environmental toxicity. Existing hydrocarbon transport and storage infrastructure can be directly applied to transport and store methanol in the geologic subsurface. In this context, a major concern besides methanol biodegradability is its high miscibility with water, potentially resulting in relevant storage losses that may favour uneconomic storage operations in active groundwater aquifers. Hence, the present study aims at a quantitative assessment of the mixing behaviour of methanol and water based on a reference numerical simulation benchmark previously applied to investigate that of CH4 stored in a CO2 cushion gas within a depleted natural gas reservoir (Oldenburg et al., 2003, Ma et al., 2019, and others). For that purpose, the TRANSPORTSE numerical simulator (Kempka, 2020), applicable to simulate fluid flow as well as transport of heat and reactive transport of chemical species (Kempka et al., 2022) is used in the present study. Mixing ratio-dependent density and viscosity changes as well as different reservoir dipping angles are considered to determine the chemical storage efficiency in view of mixing losses. Simulation results demonstrate that methanol fraction-driven variations in fluid density and viscosity of up to 20 % and 30 %, respectively, as well as the relatively low diffusion coefficients compared to those of gases result in low mixing degrees of both liquid components. Structural geological features need to be considered in the selection of methanol storage sites, since these directly affect the spatial extent of the mixing region, and thus methanol recovery efficiency.

 

Kempka, T., Steding, S., Kühn, M. (2022) Verification of TRANSPORT Simulation Environment coupling with PHREEQC for reactive transport modelling. Advances in Geosciences, 58, 19-29. https://doi.org/10.5194/adgeo-58-19-2022

Kempka, T. (2020) Verification of a Python-based TRANsport Simulation Environment for density-driven fluid flow and coupled transport of heat and chemical species. Advances in Geosciences, 54, 67-77. https://doi.org/10.5194/adgeo-54-67-2020

Ma, J., Li, Q., Kempka, T., Kühn, M. (2019) Hydromechanical Response and Impact of Gas Mixing Behavior in Subsurface CH4 Storage with CO2-Based Cushion Gas Energy & Fuels 33 (7), 6527-6541. https://doi.org/10.1021/acs.energyfuels.9b00518

Oldenburg, C. M. (2003) Carbon Dioxide as Cushion Gas for Natural Gas Storage. Energy Fuels 17(1), 240−246. https://doi.org/10.1021/ef020162b

How to cite: Kempka, T.: Mixing behaviour of methanol stored in depleted hydrocarbon reservoirs to support the European Union energy transition, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9383, https://doi.org/10.5194/egusphere-egu23-9383, 2023.

One of the main challenges in soil science lies in the passage from heterogeneous soil structure to a quantified multi-scale 3D model. Here a new approach to quantify the microbial distribution relating to soil pore structure is presented. Characterising 3D microbial soil structural in digital porous media is not found and most soil process models tend to assume a homogenous spatial distribution of microbes. We measured the in situ spatial distribution of bacteria in arable soils across scales from sub-micrometers to metres and here we describe further progress to quantify and explicitly model the 3D microbial distributions, based on a stochastic Bayesian approach to predict spatial variation in the underlying bacterial intensity measure. A 3D higher order Multi-Markov chain model is introduced to model complex geometry of real soil structure and associated microbial distribution. In this study, Markov random fields are used to construct multiscale 3D Pore Architecture Models (PAM). The binary structure of PAM has been successfully used to predict multiphase flow behaviour in porous media such as hydrocarbon bearing reservoir rocks, we explore further to use such a new multi-components scheme in modelling pore structure incorporating with microbial spatial distribution, the multicomponent Markov chain model, which is a stationary multiple higher order Markov chain. The models parameterisation is based on high resolution SEM images of soil that have been prepared in a manner that preserves the microbial community information in situ. Based on the quantified 3D multiscale soil structure associated with microbial distribution components, the accurate reactive flow of microbial degradation can be simulated to predict environmental impact of microbial activates in the field. A variety of examples of structures and bacterial distribution created by the models are presented.

How to cite: Wu, K.: A new 3D multicomponent markov chain model incorporating multi-scale soil structure with microbial distribution, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9593, https://doi.org/10.5194/egusphere-egu23-9593, 2023.

EGU23-9686 | ECS | Orals | ERE1.9

Geologic Controls on the Genesis of the Arctic Permafrost and Sub-Permafrost Methane Hydrate-bearing System in the Beaufort–Mackenzie Delta 

Zhen Li, Elena Chabab, Erik Spangenberg, Judith Schicks, and Thomas Kempka

The Canadian Mackenzie Delta (MD) is a river-mouth depocentre and the second-largest Arctic delta. It exhibits high resources of prospected sub-permafrost gas hydrates (GHs), mainly consisting of thermogenic methane (CH4) at the Mallik site, which migrated from deep source rocks. The objective of the present study is to confirm the sub-permafrost GHs formation mechanism proposed by Li et al. (2022a), stating that CH4-rich fluids were vertically transported from deep overpressurized zones via geologic fault systems and formed the present-day GH deposits in the shallower Kugmallit Sequence since the Late Pleistocene. Given this hypothesis, the coastal permafrost began to form since the early Pleistocene sea-level retreat, steadily increasing in thickness until 1 Million years (Ma) ago. Observations from well-logs and seismic profiles were used to establish the first field-scale static geologic 3D model of the Mallik site. A framework of equations of state to simulate the formation of GHs and permafrost (Li et al., 2022a, 2022b) has been developed and coupled with a numerical simulator for fluid flow as well as the transport of chemical species and heat in previous studies. Here, numerical simulations using the proven thermo-hydro-chemical simulation framework were employed to provide insights into the hydrogeologic role of the regional fault systems in view of the CH4-rich fluid migration and the spatial extent of sub-permafrost GH accumulations during the past 1 Ma. The simulated ice-bearing permafrost and GH interval thicknesses, as well as sub-permafrost temperature profiles, are consistent with the respective field observations, confirming our previously introduced hypothesis. In addition, simulation results demonstrate that the permafrost has been substantially heated to 0.8–1.3 °C, triggered by the global temperature increase of about 0.44 °C (IPCC, 2022) and further accelerated by Arctic amplification from the early 1970s to the mid-2000s. Overall, the good agreement between simulations and observations demonstrates that the present modeling study provides a valid representation of the geologic controls driving the complex permafrost-GH deposit system. The model’s applicability for predicting GH deposits in permafrost settings can provide relevant contributions to future GH exploration and exploitation activities.

References

IPCC, 2022: Climate Change 2022: Impacts, Adaptation, and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [H.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B. Rama (eds.)]. Cambridge University Press. Cambridge University Press, Cambridge, UK and New York, NY, USA, 3056 pp., doi:10.1017/9781009325844.

Li, Z., Spangenberg, E., Schicks, J. M. & Kempka, T. Numerical Simulation of Coastal Sub-Permafrost Gas Hydrate Formation in the Mackenzie Delta, Canadian Arctic. Energies 15, 4986 (2022a). https://doi.org/10.3390/en15144986

Li, Z., Spangenberg, E., Schicks, J. M. & Kempka, T. Numerical Simulation of Hydrate Formation in the LArge-Scale Reservoir Simulator (LARS). Energies 15, 1974 (2022b). https://doi.org/10.3390/en15061974

 

How to cite: Li, Z., Chabab, E., Spangenberg, E., Schicks, J., and Kempka, T.: Geologic Controls on the Genesis of the Arctic Permafrost and Sub-Permafrost Methane Hydrate-bearing System in the Beaufort–Mackenzie Delta, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9686, https://doi.org/10.5194/egusphere-egu23-9686, 2023.

In the past decades, boreholes were drilled all over the world for the purpose of hydrocarbon prospection. Data from these boreholes are a very valuable resource, that can be used in current geological, geothermal and hydrogeological studies. Since the process of drilling is both expensive and disturbing to the environment the possibility of incorporating data that already exists in the current studies is always worth consideration. However, in the case of older boreholes quality of data is not on par with modern standards which limits its usefulness, especially in the case of data from boreholes drilled in thin-bedded rock formations.

Resistivity logs are one of the main logs used both in hydrocarbon prospection and other applications such as geological, geothermal and hydrogeological studies. Resistivity logs measured by older generations of logging tools are characterized by significantly lower vertical resolution in comparison to logs measured by newer logging tools which affect the quality of the interpretation. However, the information averaged in the process of logging can be partially restored in the process of iterative inversion.

The focus of the presentation is on the utilization of open-source global optimization software in the process of inversion of resistivity well logs. Since inverse problems encountered in geophysics tend to be on the difficult side, relatively simple optimization schemas that often can be found in open-source software are not always giving good results. Therefore, in the presentation, a few methods that allow adapting those algorithms to the problem of inversion of well logs are discussed. The performance of the inversion procedure is validated on synthetic data and real data from the borehole where resistivity logs were measured by different generations of logging tools in the same depth intervals, which allows for comparison of the inversion results to logs measured by modern equipment.

 

The research was funded by the National Science Centre, Poland, grant number 2020/37/N/ ST10/03230.

How to cite: Wilkosz, M.: Adaptation of open-source global optimization software to the process of iterative inversion of resistivity well logs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10004, https://doi.org/10.5194/egusphere-egu23-10004, 2023.

EGU23-11350 | ECS | Orals | ERE1.9

New Insights into Underlying Mechanisms of CO2 Wettability and Residual Saturation from Laboratory Measurements of Multi-Phase Zeta Potential in Supercritical CO2-Rock-Brine Systems 

Miftah Hidayat, Jan Vinogradov, Mohammad Sarmadivaleh, Stefan Iglauer, David Vega-Maza, and Jos Derksen

Measurements of the zeta potential using streaming potential method are frequently used to characterise flows in subsurface settings owing to a broad range of applications of this petrophysical property; examples include CO2 geological storage, hydrocarbon reservoirs, geothermal sources and freshwater aquifers. Many experimental studies of the zeta potential have been carried out covering a wide range of parameters including different rock mineralogy, brine concentration and composition, and temperature to understand the impact of each parameter. The capability of the streaming potential method to be used on intact rock samples, single-/ and multi-phase flows, wide range of salinity, pressure and temperature makes the method suitable for representation of typical subsurface conditions. However, none of previous studies reported high multi-phase measurements at high pressure conditions typical for deep reservoirs. To adequately represent subsurface conditions of carbon geological storage sites, the minimum experimental pressure of 7.38 MPa and minimum temperature of 31 °C, consistent with the supercritical-CO2 (scCO2), need to be used. Obtaining stable measurements of the streaming potential under these conditions is extremely challenging. We report a detailed design of a high-pressure experimental system and experimental protocol for multi-phase streaming potential measurements that were carried out on scCO2-sandstone-brine systems at temperature of 40 °C, pressures ≤10 MPa and with a variety of aqueous solutions.

The obtained results demonstrate for the first time that the multi-phase zeta potential correlates with the measured scCO2 residual saturation and rock’s wetting state interpreted from other parameters. Moreover, our results unambiguously identify for the first time the polarity and likely magnitude of the scCO2-brine interfacial zeta potential. Our findings improve the current understanding of the complex wetting behaviour of scCO2 and provide important experimental data for numerical (surface complexation, molecular dynamics), analytical (DLVO) or combined models.

How to cite: Hidayat, M., Vinogradov, J., Sarmadivaleh, M., Iglauer, S., Vega-Maza, D., and Derksen, J.: New Insights into Underlying Mechanisms of CO2 Wettability and Residual Saturation from Laboratory Measurements of Multi-Phase Zeta Potential in Supercritical CO2-Rock-Brine Systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11350, https://doi.org/10.5194/egusphere-egu23-11350, 2023.

Inland salinisation due to the upwelling of highly mineralised deep waters formed by leaching of Upper Permian salt diapirs is a typical phenomenon in the North German Basin. In the German State of Brandenburg, the local absence of the regionally most important aquiclude, the Lower Oligocene Rupelian Clay, separating deep saline waters from the overlying freshwater aquifers, is considered to be the main cause of local salinisation in the freshwater column.

The present study uses density-driven 3D flow and transport simulations to assess saltwater upwelling across Quaternary window sediments in the Rupelian for an area in southeastern Brandenburg with detectable salt concentrations in the freshwater column. Previous simulations along a 55 km long transect in Brandenburg using a 2D model have already demonstrated the potential negative impact of groundwater extraction, the use of the deep subsurface as a storage reservoir or lower precipitation rates and decreasing groundwater levels as a consequence of global climate change on the degree of upper aquifer salinisation (Chabab et al., 2022; Tillner et al., 2016; Wetzel et al., 2016).

The presented simulation results show that 3D flow strongly affects the temporal and spatial distribution of upper aquifer salinisation due to the varying extent of layers and erosion windows in the Rupelian Clay. The location of groundwater extraction sites, hydraulically conductive faults and spatial variations in groundwater recharge additionally influence the location and degree of shallow aquifer salinisation, and must therefore be carefully considered. Depending on topographic gradients and density variations occurring due to differences in pressure and temperature, convective cells with descending flow and freshwater lenses in the saltwater column also develop locally. We show that 3D flow simulations are essential for site-specific analysis to represent the dynamics of the system with many different hydrogeologic interacting and controlling factors.

 

Literature

Chabab, E., Kühn, M., Kempka, T. (2022): Upwelling mechanisms of deep saline waters via Quaternary erosion windows considering varying hydrogeological boundary conditions. Advances in Geosciences, 58, 47-54.

Tillner, E., Wetzel, M., Kempka, T., Kühn, M. (2016): Fault damage zone volume and initial salinity distribution determine intensity of shallow aquifer salinisation in subsurface storage. Hydrology and Earth System Sciences, 20, 1049-1067.

Wetzel, M., Kühn, M. (2016): Salinization of Freshwater Aquifers Due to Subsurface Fluid Injection Quantified by Species Transport Simulations. Energy Procedia, 97, 411-418.

How to cite: Chabab, E., Kühn, M., and Kempka, T.: Saltwater upwelling quantified by density-driven 3D flow and transport simulations for a study area in Brandenburg, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12741, https://doi.org/10.5194/egusphere-egu23-12741, 2023.

EGU23-12843 | ECS | Posters on site | ERE1.9

Coupling approach in shallow, unconfined aquifers in the Po Plain area: A preliminary study for future ground monitoring purposes. 

Celine Eid, Christoforos Benetatos, and Vera Rocca

The use of the coupling approach in analyzing the interaction between the flow field and the stress field in shallow, unconsolidated aquifers allows a better description of the involved phenomena. We perform our study on an area in the Po Plain (northern Italy) in the province of Bologna in Emilia-Romagna based on intended future studies on ground movements due to the superposition of shallow water production with deep underground gas storage.

The static geological model of the alluvial sediments, locally exceeding 500 meters of thickness, is developed via a stochastic approach in order to manage the high degree of uncertainty in the system spatial continuity and heterogeneities. Corresponding water production data and piezometric measurements are collected for simulating the dynamic behavior of the shallow aquifer. The high uncertainty in water production data are managed considering a maximum and minimum scenarios on the basis of punctual well measurements and regional trend information. Correlation law between petrophysical parameters and deformation variables are derived for technical literature. The coupling technique is then applied and some sensitivity analysis are developed to assess the effects of the correlation laws. The results are finally compared with the output from the uncoupled techniques.

How to cite: Eid, C., Benetatos, C., and Rocca, V.: Coupling approach in shallow, unconfined aquifers in the Po Plain area: A preliminary study for future ground monitoring purposes., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12843, https://doi.org/10.5194/egusphere-egu23-12843, 2023.

The decarbonization of communities and their energy supply is considered as a contemporary priority path forward, although it poses many challenges. In this scenario, geothermal energy can cover a pivotal role in the energy transition and in a wider spread of renewable energies. Moreover, the possibility to reuse or modifying existing wells for geothermal purposes is becoming a hot and promising topic. In Italy, there are more than 8000 abandoned/inactive on-shore wells drilled for hydrocarbon exploration subsequently abandoned either for the end of the resource (exhausted well) or for sterility (barren well). This can represent a huge opportunity for geothermal energy exploitation. The drilled borehole available data, collected during the exploration activity, provide useful information about the sub-surface reservoirs, highly reducing the mining risk level, and allowing direct and low cost access to the sub-surface heat energy.

This work aims to analyse the feasibility of the retrofitting of abandoned oil and gas wells focusing on the Italian territory, proposing a selection methodology of wells starting from raw data collection. We want to evaluate which could be the best technical solutions for the retrofitting of an inactive oil&gas well considering the closed loop geothermal options, both coaxial and deep-U heat exchangers options. We decided to concentrate on the closed loop solution for the retrofitting because of its low environmental impact due to the absence of fluid exchange with the surrounding underground, despite the lower efficiency, compared to a system that involves the extraction of fluids from the subsoil.

A database, that collects data of wells drilled since the middle of 1900, provide by public information, is used, applying a first filter by considering the following discriminant parameters: the depth (more than 1000 m), the Bottom Hole Temperature (BHT), higher than 65°C, and the nearness of possible end-users. After this operation a set of 541 wells has been obtained.  A focus on the status of the well has been performed,  such as vertical or deviated and the availability of a litho-stratigraphic data to thermally characterize the rock formations around the well.  Then, the measured temperature data was analysed to figure out the distribution of geothermal gradient and to identify different situations in terms of temperature at national scale, that could be selected later as representative case studies of high, medium and low enthalpy geothermal plant.  Moreover, the Horner plot approach have been adopted for computing equilibrium temperature at depth after drilling, obtaining the real temperatures for each well. The proximity to possible heat stakeholders was then assessed using a GIS system.

How to cite: Facci, M., Di Sipio, E., and Galgaro, A.: Energy transition and Deep Geothermal solution role: a screening procedure for the retrofitting and reuse of ex Oil&Gas wells as deep closed-loop borehole heat exchangers in Italy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14599, https://doi.org/10.5194/egusphere-egu23-14599, 2023.

EGU23-15410 | Posters on site | ERE1.9

Sparse image domain wavefield tomography for low-cost CCS monitoring in repurposed hydrocarbon fields 

Sjoerd de Ridder, Afsaneh Mohammadzaheri, Alexander Calvert, and Mikael Lüthje

Seismic time-lapse (4D) imaging has been considered as a key solution to monitor CO2 reservoirs. However, traditionally this technology requires dense data acquisition to produce high-resolution images. It is anticipated that monitoring will be required for more than 50 years after CCS operations cease and the monitoring phase is profit-negative. Developing cheaper 4D seismic imaging techniques is necessary. Historical knowledge of the subsurface structure in and near abandoned hydrocarbon fields, could reduce the dense data requirement of 4D imaging.

Here we present preliminary results of 4D seismic (image-domain) wavefield tomography (IDWT) using pre-stack gathers from a sparse monitoring acquisition. IDWT uses short-offset data to exploit primarily kinematic changes rather than amplitude changes. IDWT minimises the shift between baseline and monitor migrations by optimising the monitor velocity model. Pre-stack IDWT, unlike post-stack methods, can use individual shot gathers to calculate the migration images. This property is beneficial when using sparse data acquisition permitting reliable measurement of shifts between monitor and baseline. Knowing the structure of the subsurface, we can design sparse acquisition surveys for seismic deployment, to minimize uncertainty in target areas. 

We create synthetic models based on Tyra gas field, a prospective future repository of CO2 in the Danish sector of North Sea and simulate CCS and subsequent leakage scenarios. The presence of CO2 in the reservoir, as well as the effect of reservoir pressure on the overburden stress-state, changes the seismic velocity structure of the reservoir and the overburden. These velocity changes cause an apparent depth (or time) shift when migrating the data.

How to cite: de Ridder, S., Mohammadzaheri, A., Calvert, A., and Lüthje, M.: Sparse image domain wavefield tomography for low-cost CCS monitoring in repurposed hydrocarbon fields, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15410, https://doi.org/10.5194/egusphere-egu23-15410, 2023.

Coaxial Deep Borehole Heat Exchanger (DBHE) provides an alternative way to extract geothermal energy by circulating a working fluid without producing geofluids or performing injection processes. It can be used to avoid induced seismicity issues caused by injection operations in hydrothermal doublets or to repurpose damaged or non-productive wells. A detailed numerical model is required to accurately capture as well the thermo-hydraulic processes within the DBHE and the cooling effects in the surrounding reservoir. This numerical model is often high dimensional. For a real-time monitoring purpose and optimization study, a direct numerical simulation with this model is computationally intractable.

In this study, we use a physics-based machine learning method to reduce the computational cost of the performed forward model run. The physics-based machine learning method here is based on the non-intrusive reduced-basis method which expresses a physical solution in a linear combination of basis functions and weights. It is a model-order reduction technique that is mathematically proven to produce physically consistent predictions. The structure of the physics is maintained in basis functions and a machine learning model is deployed to calculate the weight for each basis function.

We show the advantages of using the physics-based machine learning method by applying it to the planned coaxial DBHE in Eden (Cornwall, UK). The forward simulation is performed using the open-source simulator GOLEM, a finite-element (FE) based simulator that is built within the MOOSE framework. In this study we provide a running time comparison between the FE simulations and the physics-based machine learning simulations. We will also evaluate the accuracy of the physics-based machine learning predictions towards the FE solutions. Here, we would like to emphasize the significant computational speed-up that allow us to obtain new temperature and pressure state predictions in real-time context and to perform optimization with numerous iterations.

How to cite: Teza, D., Santoso, R., Koltzer, N., Degen, D., Bennett, T., and Wellmann, F.: Physics-based machine learning for modeling thermo-hydraulic processes in a coaxial deep borehole heat exchanger, considering an explicit reservoir-wellbore representation: A case study of Cornwall, UK , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16369, https://doi.org/10.5194/egusphere-egu23-16369, 2023.

EGU23-16627 | Posters on site | ERE1.9

CCS Reservoir Characterisation using Carbon Quantum Dots 

Paul Glover

Efficient use of new CCS resources depends critically on their characterisation. This is as true for CCS reservoirs that are deep aquifers or reservoirs that have previously been exploited as oil or gas reservoirs. Conventional pre-existing or newly commissioned reservoir characterization methodologies, such as well logs, 3D and 4D seismic reflection and cross-well electromagnetic imaging are limited in their scope and resolution. For CCS, the  crucial characterisation is that of the connectivity of the pore network. Carbon quantum dots (CQDs) are inert carbon nano-particles less than 10 nm in diameter. They can be made easily from environmentally-friendly stock materials and remain stable in aqueous solution no matter the pH or salinity, unlike conventional nanoparticles. In fluorescence spectroscopy CQDs demonstrate a strong absorption in the UV region with peaks at 228 nm and 278 nm. Their fluorescence spectra occupy the visible spectrum and are related to the stimulating frequency. These optical properties allow the number of particles to be ascertained easily and their small size allows them to be pervasive in the porous medium. Consequently, CQDs are ideal for use as a conservative tracer. Core and bead–pack tests have shown that almost 100% of the injected CQDs can be recovered from the porous medium indicating that there would be no damage to the CCS resource by their use. Breakthrough curves (BTCs) can be used to calculate the porosity and connectivity of water saturated rocks and the water saturation and connectivity of rocks from previously exploited hydrocarbon reservoirs at temperatures up to 80oC. Indeed it is possible that CQDs could be used to monitor quantitatively the emplacement of CO2 along the injection path. Although these CQDs have an attenuated performance in carbonate rocks, surface coatings are expected to resolve this question. Surface functionalisation will also allow the properties of the reservoir, such as temperature to be measured by altering the frequency of the emerging CQDs.

How to cite: Glover, P.: CCS Reservoir Characterisation using Carbon Quantum Dots, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16627, https://doi.org/10.5194/egusphere-egu23-16627, 2023.

EGU23-16672 | Posters on site | ERE1.9

Unconventional Fractal Modelling and Simulation of Heterogeneous and Anisotropic Reservoirs 

Paul Glover, Mehdi Yaghoobpour, Piroska Lorinczi, Wei Wei, Li Bo, and Saddam Sinan

One strategy for reducing global greenhouse gas emissions as the world progresses towards net zero is to extract more hydrocarbons from existing resources. Conventional modelling and simulation of heterogeneous and anisotropic reservoirs consistently and significantly underestimates production, sometimes by as much as 70%.

We now understand that many reservoir properties are fractal, such as porosity, grain size and permeability. While water saturation and capillary pressure have distributions which arise from fractally-distributed microstructural properties. Recent work has resulted in the development of the fractal theory of Archie’s laws, providing fractal dimensions underlying both the cementation and saturation exponents that is consistent with the n-phase Archie’s law theory.

The significant underestimation of production by conventional reservoir models can be overcome by the use of advanced fractal reservoir models (AFRMs) which take account of the fractal distribution of key petrophysical properties such as porosity, grain size, cementation exponent, permeability, water saturation and capillary pressure. These models employ existing and interpolated data across an extended range of scales and take account of variability less than the 50 m seismic resolution limit. AFRMs provide production profiles that are much closer to actual production profiles.

This presentation describes briefly the AFRM approach to the modelling and simulation of heterogeneous and anisotropic reservoirs, showing how AFRMs can be generated easily to match an imposed degree of heterogeneity and anisotropy, or can be conditioned to represent the heterogeneity and anisotropy of the target reservoirs. We describe how AFRMs can be generated and normalised to represent key petrophysical parameters, how AFRM models can be used to calculate permeability, synthetic poroperm cross-plots, water saturation maps and relative permeability curves, and how AFRMs which have been conditioned to represent real reservoirs provide a much better simulated production parameters than the current best technology.

Generic AFRM modelling and simulation show that total production, production rate, water cut and the time to water breakthrough all depend strongly on heterogeneity and anisotropy. Counter to expectation, optimal production is obtained from placing both injectors and producers in the most permeable areas of heterogeneous reservoirs. Furthermore, modelling with different degrees and directions of anisotropy shows how hydrocarbon production depends critically on anisotropy direction, which changes over the lifetime of the reservoir.

AFRMs are ultimately only useful if they can be conditioned to real reservoirs. We have developed a method of fractal interpolation to match AFRMs to reservoir data across a wide scale range. Results comparing the hydrocarbon production characteristics of such an approach to a conventional krigging approach show a remarkable improvement in the modelling of hydrocarbon production when AFRMs are used; with AFRMs in moderate and high heterogeneity reservoirs returning values always within 5% of the reference case, while the conventional approach often resulted in systematic underestimations of production rate by over 70%.

Although more work needs to be done on this new approach to reservoir modelling, initial results indicate that it has the potential for improving the accuracy of modelling and simulation in heterogeneous and anisotropic reservoirs by an order of magnitude or more.

How to cite: Glover, P., Yaghoobpour, M., Lorinczi, P., Wei, W., Bo, L., and Sinan, S.: Unconventional Fractal Modelling and Simulation of Heterogeneous and Anisotropic Reservoirs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16672, https://doi.org/10.5194/egusphere-egu23-16672, 2023.

EGU23-17292 | Posters on site | ERE1.9

Molecular simulation of stripping of crude oil by CO2 in tight reservoirs 

Qian Wang, Jian Shen, Bai Jie, Paul W.J. Glover, and Piroska Lorinczi

Tight oil reservoirs are often oil-wet and contain surface adsorbed layers of hydrocarbon. Improvement of production lies in part in the ability to produce this adsorbed oil for its own sake and to unblock small pores that can improve the relative permeability of the reservoir. In this paper we have used molecular modelling and simulation first to study the formation of adsorbed oil films made from n-alkanes of 5 different molecular weights (nC7, nC12, nC18, nC22, nC25) on an hydroxylated ->-SiO2 surface, and then to examine the process of stripping oil from these layers using carbon dioxide, nitrogen and water. It was found that all n-alkanes but nC12 formed a monolayer oil film, while nC12 formed a three-layer oil film. Molecular weight, length and flexibility of the n-alkane were all factors in oil film formation. It was found that flooding with CO2 is able to strip all of the modelled n-alkanes from the α-SiO2 surface effectively. The time required to strip the n-alkane was longer for n-alkanes with higher molecular weights. The stripping process was divided into three stages: (i) CO2 diffusion and dissolution, (ii) competitive adsorption, and (iii) oil film push-off. A fourth stage was recognized only for light n-alkanes, and which involved the dissolution of CO2 in mobilized n-alkane, leading to improvements in its mobility. Comparative simulations using nC12 showed that N2 and H2O exhibit no efficacy in stripping n-alkanes from surface adsorbed oil films. The efficacy of CO2 was attributed to (i) it being a polar molecule that is attracted to the hydroxylated silica surface, (ii) its miscibility in n-alkanes, and (iii) that it is in a supercritical state at reservoir conditions. The failure of N2 arises because it is a non-polar molecule with no affinity for the surface and exists as an immiscible gas at reservoir conditions. Water was ineffective, because, though polar, it is immiscible in the oil layer and so cannot access the rock surface. Consequently, CO2-flooding is expected to be particularly effective in improving production from tight oil-wet clastic reservoirs.

Key words: tight reservoir; pore throats; CO2 flooding; oil film stripping; molecular simulation

How to cite: Wang, Q., Shen, J., Jie, B., Glover, P. W. J., and Lorinczi, P.: Molecular simulation of stripping of crude oil by CO2 in tight reservoirs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17292, https://doi.org/10.5194/egusphere-egu23-17292, 2023.

Underground coal fire (UCF) is a disaster associated with coal mining activities which occurs in almost all main coal-producing countries. UCF not only burns up massive coal resource, but also causes damages and pollutions to local eco-environment, such as the land subsidence, the contamination to soil and nearby water resource, the pollution to air, and so on. In this presentation, the author attempts to illustrate a comprehensive understanding to UCF from micro and macro perspectives, including the mechanism of UCF occurrence and propagation, the monitoring and early warning of UCF, the efficient advanced materials depressed the UCF and the UCF’s impact on local eco-environment, which is helpful to understanding well of UCF. Methods and technologies which were employed in this study include analyses of the remote sensing data, the TG data, the C13- NMR data, the HRTEM data, the FTIR data, the XRD and XPS data, etc. Necessary models for quantifying UCF occurrence and propagation were established by analyzing the process of UCF. And a novel method was proposed by analyzing the distribution of surface temperature coupled with the NDVI data and InSar data. Some inhibitors were used in this study to depress the proceeds of coal oxidation which is useful to control the UCF. In addition, considering the UCF’s impacts on local eco-environment, coal-fire-induced heavy metal contamination to soil also were investigated which show that the heat effect is a major factor influences the distribution of heavy metal. Finally, strategies were suggested to carry out the restoration of UCF sites after it was extinguished.

Keywords: Underground Coal Fire; Mechanism of Occurring and Propagating; Remote Sensing; Inhibitor; Eco-environment Impact

How to cite: Zeng, Q.: Causes, Monitoring, Extinction, and Eco-environmental Impacts of Underground Coal Fires: A Comprehensive Perspective, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-914, https://doi.org/10.5194/egusphere-egu23-914, 2023.

EGU23-1643 | Orals | ERE1.12

Underground coal fires – A global post-mining catastrophe 

Robert Finkelman and Henry Dodds

Uncontrolled coal fires are a universal coal mining and post-mining concern. Efforts to extinguish these fires are often unsuccessful and these fires can result in major catastrophes such as the abandonment of the town of Centralia Pennsylvania in the U.S. and displacement of many thousands of villagers in India. The physical threat of these fires, often a result of coal mining, is a serious issue that has taken the lives of people in the U.S., Asia, and Africa. However, an equally though more insidious issue is the long-term health impacts of the emissions of these uncontrolled coal fires. Recent studies in the Jharia region of India has shown that villagers living about one mile from active coal fires reported twice as many health concerns as villagers living about five miles away. Yet, there are many villages in this region and elsewhere where people are living in immediate proximity to these fires. Studies of the gases emitted from these fires and condensates formed from the escaping gases document the mobilization of potentially toxic gases such as benzene, xylene, toluene, methane, carbon monoxide and elements such as As, Se, Hg, F, Pb, Sb. An SEM/EDX study of a small (30mm X 20mm) piece of condensate collected from an active underground coal fire just meters from a village revealed several generations of deposition with at least 30 phases containing ammonia, B, F, Al, Si, S, Cl, Fe, Cu, Zn, As, Se, Br, Mo, Cd, I, Ba, Pb, and Bi. Clearly, more attention should be paid to this post mining catastrophe to minimize the health problems and deaths resulting from these uncontrolled coal fires.

How to cite: Finkelman, R. and Dodds, H.: Underground coal fires – A global post-mining catastrophe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1643, https://doi.org/10.5194/egusphere-egu23-1643, 2023.

EGU23-1693 | Posters on site | ERE1.12

Spatial Assessment of Asbestos Mine Remediation Effect Using Airborne Hyperspectral Imaging System 

Yongsik Jeong, Jaehyung Yu, Lei Wang, and Hyun-Cheol Kim

This work investigated an abandoned asbestos mine (AAM) remediation project in CA, US. Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) hyperspectral data were used to assess the mine treatment effect. The distribution of AAM and restored area were evaluated before and after remediating based on the spectral analysis and model for indicating naturally occurring asbestos (NOA) and encapsulation (remediation). We developed NOA, host rock, and encapsulation indices by binary logistic regression modeling using hyperspectral bands. The detection models statistically selected visible-near infrared (VNIR) regions rather than shortwave infrared (SWIR) ranges. The models-based classification accuracy was approximately 84%. Notably, the detection accuracy of non-treated and treated areas was increased to about 90% excluding the host rock index. The NOA and encapsulation indices showed that they can be efficiently applied to asbestos occurrence/remediation. The remote sensing data revealed that the whole AAM area was increased by ~5% by the remediation process, and the restoration activity reduced asbestos exposure by ~32%. This work would be contributed to providing an intuitive and realistic-spatial understanding of the planning and managing remediation project.

How to cite: Jeong, Y., Yu, J., Wang, L., and Kim, H.-C.: Spatial Assessment of Asbestos Mine Remediation Effect Using Airborne Hyperspectral Imaging System, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1693, https://doi.org/10.5194/egusphere-egu23-1693, 2023.

Modelling oxygen-limited and self-sustained smoldering propagation is of significance for prevention of underground coal fire hazards. However, coupling oxidative reaction and oxygen transport in multi-scale porous media has been still a challenging issue and the conventional models have been questioned by inadequacy of TG-scale kinetic parameters applied to bed-scale propagation. In this work, an analytic expression of oxidative reaction rates limited by oxygen transport was derived from the conservation equations of oxygen species transport in gas and solid. Along with the Darcy air flow driven by thermal buoyancy, the oxygen-limited and self-sustained smoldering propagation of underground coal fires was modeled in this work. The model was compared with laboratory experiments and the conventional model. Results show that the proposed model well predicts the oxygen-limited and self-sustained smoldering propagations of underground bituminous and anthracite coal fires. The predictability of the proposed model is better than the conventional model in spite of great effort to modify kinetic parameters best fitting with experimental data. It is validated that the proposed model addresses the two puzzled issues in the conventional model with respect to buoyancy-driven, oxygen-limited, and self-sustained smoldering propagation of underground coal fires. This work may help to develop green countermeasures to mitigate underground coal smoldering fires.

How to cite: Song, Z.: Modelling oxygen-limited and self-sustained smoldering propagation of underground coal fires driven by thermal buoyancy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1959, https://doi.org/10.5194/egusphere-egu23-1959, 2023.

In the coal fire control project, the multiple water injections used to extinguish coal fires and the coal fires that reignite can cause many forms of ground collapse to occur, threatening project safety. Therefore, studying the thermal damage and capturing disaster signals of sandstone, a main weight bearer in coal measure strata, exposed to heating-cooling, cycles is critical to ensure the engineering safety. In this work, the coal-measure sandstones from Urumqi, Xinjiang and Yulin, Shaanxi, China, were collected. For the sandstones from Urumqi, China (Type A sandstone), the samples were first heated to 800 °C, and cooled using water, heated to a setting temperature (100 °C, 200 °C, 300 °C, 400 °C, 500 °C, 600 °C, 700 °C and 800 °C), and cooled using water again. The ultrasonic p-wave velocity, density and water absorption of the sandstones were tested. Uniaxial compression tests and shear tests were conducted on the sandstones. The thermal damage in sandstones were analysed using rock energy theory. For the sandstones from Yulin, China (Type B sandstone), the X-ray diffraction test, scanning electron microscope test and uniaxial compression experiment with AE monitoring were carried out for the raw sandstone and the sandstone exposed to 800 °C and water cooling twice (cooling shock sandstone), respectively. The results show that, for the type A sandstone, compared with the mechanical strength of the sandstone at room temperature, the mechanical strength of the sandstone exposed to 800 °C for the first time is decreased by less than 20%. When the sandstone is exposed to high temperature again, the critical threshold temperature is 400 °C. When the temperature exceeds 400 °C, the thermal damage aggravated again and the mechanical strength rapidly degraded. For the type B sandstone, the results showed that the crack density and volume of cooling shock sandstone increased by 8.79% and 2.69%, respectively, and p-wave velocity decreased by 51.83%, compared with those of the raw sandstone. The mechanical strength of cooling shock sandstone decreased, including a 50.68% reduction in elastic modulus. The AE attenuation coefficient α=(1-Ec/E0) /kc, related to the elastic modulus and the crack change rate, was derived, which providing an approach to count the attenuation of AE signal caused by thermal damage for cooling shock sandstone. Increasing the preamplifier amplification factor is feasible to improve the accuracy for monitoring the fracture of cooling shock sandstone in coal-fire control project.

How to cite: Ge, S., Shi, B., Zhang, S., Deng, J., and Wu, C.: Effect of thermal damage on capturing fracture signal of high temperature sandstone subjected to cooling shock from the coal fire control project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3848, https://doi.org/10.5194/egusphere-egu23-3848, 2023.

EGU23-4239 | Orals | ERE1.12

residual space distribution law in long-wall old mining  area 

Zhi Guo, Wei Lu, Yongqiang Zhou, Meng Zhang, Changlong Liao, and Changxiang wang

Grouting treatment in old goafs is an effective method to achieve sustainable development of mining areas after coal seam mining. Due to the concealment of the old goaf and the lack of historical information, it is difficult to directly obtain the distribution of the residual void in the old goaf. In this study, the residual void distribution law of the longwall old goaf area was studied through similar material simulation test, gangue compression test and stress arch theory. The results showed that the collapse zone can be divided into regular collapse zone and irregular collapse zone. Fissure zone and regular collapse zone have few grouting voids due to the closing effect. Due to the different forms of crushing, the irregular collapse zone has large voids and was difficult to completely close with the passage of time, which is the key area of grouting treatment. For the longwall old goaf area that has reached full mining, the stress relief zone was formed at both ends of the open-off cut and the stop-mining line, and the stress recovery zone and the stress stabilization zone were formed in turn close to the middle of the goaf area. The evolution process of stress arch and fracture arch in the stope can be divided into two stages and three periods. The first stage: the development stage of fracture arch and stress arch, that is, the stress relief and stress recovery period of broken gangue in the goaf. The second stage: the fracture arch and stress arch formation stage, that is, the stress stabilization period of broken gangue in the goaf area. On the basis of the above research, the concept of residual void equivalent height was proposed, and its calculation formula was given, and furthermore, the formula for the estimation of grouting volume was given. The height of the irregular collapse zone was 0.915~0.975 times of the coal seam mining thickness, the residual void equivalent height was about 0.3 times the mining thickness (take its upper limit value), and the residual void equivalent height in insufficiently collapsed area was 0.5 times the mining thickness.

How to cite: Guo, Z., Lu, W., Zhou, Y., Zhang, M., Liao, C., and wang, C.: residual space distribution law in long-wall old mining  area, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4239, https://doi.org/10.5194/egusphere-egu23-4239, 2023.

Abstract: Atmospheric pressure fluctuation is one of the most important factors affecting the climate environment and gas emission in the fire area. In order to obtain the influence rule of the surface atmospheric pressure change on the gas sampling and abnormal emission in the mine closed goaf, the No. 1 coal mine in Dananhu, Xinjiang was taken as the research object. Using Fourier transform and Fisher harmonic analysis and other methods, the influence of the periodic variation of atmospheric pressure on the gas leakage and outflow in the closed goaf was studied. The results showed that there were three atmospheric pressure periods of 15.2d, 1d and 182.2d, and the probability was greater than 95%. The time period with the highest number of atmospheric pressure peaks was 7:00-8:00, which accounted for 20.2% of total occurrence number in a day. And the time periods with the highest number of atmospheric pressure trough were 2:00, 15:00 and 16:00, accounting for 27.4%. The peak-to-trough transition time was mainly concentrated around 6h, and the diurnal variation curve of atmospheric pressure was mainly bimodal. The atmospheric pressure change rate was mostly concentrated in 10~50 Pa/h. It was determined that the distance that the gas sampling pipe was pre-laid into the inner side of the closed wall should be greater than 44.4m, and the CO concentration and atmospheric pressure in the closed goaf were both periodic and negative with atmospheric pressure. The research results have important guiding significance for the disaster warning and environmental protection of the goaf.

How to cite: Shao, Z. and Tan, B.: Research on the effect of periodic wide atmospheric pressure change on CO emission in closed goaf, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4676, https://doi.org/10.5194/egusphere-egu23-4676, 2023.

The coal-fire gases are the main actors in terms of element and heat transfer within burning post-mining waste heaps (BPWHs). Although they mainly comprise CO2 and water, they can locally be enriched in dimethyl (di)sulfide (as much as 15000 ppm, Bytom site), thiophene, SO2, H2S; 1,1- and 1,2-dichloroethane, dichloromethane and other halocarbons; chlorobenzene, ammonia, pyridine, HCN, numerous NOx, (iso)cyanogen halides, and triazine-based and imine-type compounds, AsH3, PH3, SiF4, and SF6, to mention some. Metals are most likely transported as neutral hydroxides, and/or carbonyl, nitrosyl, and hydride complexes, while iodine - as I2, iodosomethane, iodocyanoacetylene, and - alongside with Br and Cl - as halocarbons. Occurrence of exotic gases is possible considering their transient nature. The most recent proposal compounds include HNC, formaldoxime isocyanate, peroxyethyl nitrate; tetrafluoro-p-xylylene, perfluorinated p-benzyne, CHClF, HCFBr, 1,2,4-trixolane, thioacetaldehyde, thiocarbonyl fluoride, bromomethane, dithio-p-benzoquinone, monomethylsilane, and titanacyclopropene (e.g., Kruszewski, 2021). Still, the image of the coal-fire exhalative processes is not full. Here, crystal chemistry of some major minerals deposited within exhalative vents of the Upper Silesian Coal Basin heaps is presented. Chemistry of godovikovite - the major component of the Czerwionka-Leszczyny sulfate crust - is [(NH4)0.94K0.04Ca0.01Mg0.01]Σ1.00(Al0.90Fe0.09Ti0.01)Σ1.00[(SO4)1.99 (n=24); it thus bears 8 mol% sabieite and 3% steklite end-members. The local sabieite's formula is [(NH4)0.96K0.03Mg0.01]Σ1.00(Fe0.58Al0.40Ti0.02)Σ1.00(SO4)2.00. Chemistry of millosevichite from sulfate crust of Radlin is expressed as  (Al1.73Fe0.19Ca0.07K0.02Na0.01Mg0.01Ti0.01)Σ2.04[(SO4)2.97(PO4)0.01]Σ2.98 (n=16), while that for its minor Fe-analogue mikasaite is (Fe1.38Al0.51K0.04Ca0.03Ti0.02Na0.02)Σ2.00[(SO4)2.90(PO4)0.02]Σ2.92 (n=3). The local dolerophanite is likely stabilized by iron: (Cu1.96Fe0.03)Σ1.99O1.03(SO4)0.98 (n=15). Locally, a Fe-rich variety is observed, its chemistry being, possibly, (Cu1.26Fe0.65Na0.04K0.03Al0.02)Σ2.00[(SO4)0.95(SiO4)0.01]Σ0.96(O0.99Cl0.01)Σ1.00 (n=5). Dolerophanite is associated with honey-yellow crystals with the (Cu3.85Fe0.15)Σ3.00O1.33(SeO3)0.96(SO4)1.93 (n=6) formula, likely representing a new mineral species. So is true for a Cu-I-S species and a iodobismuthate (known both at Radlin and Rydułtowy), the forming abundant inclusions in extremely (Br,I)-enriched salammoniac. The wealth of the heap's exhalative zones is "completed" by (NH4)3XCl5 (X = Zn, Fe, Mg, Mn, Cu), a sodium thiosulfate pentahydrate, a potassium sodium dithionate chloride, an ammonium sulfate nitrate, and a phosphimate (tetra-μ-imidocyclotetraphosphate). Both the above halogen-bearing gaseous species and minerals result from transformation of the pore-contained post-mining brines.

Kruszewski, Ł., 2021. Burning Coal-Mining Heaps as an Organochemical Laboratory: Interesting Trace Compounds and Their Potential Sources.  Chapter 3, in: Organic Compounds, Las Vegas, Nevada, USA, ISBN: 978-93-87500-41-9, 38 pp., openaccessebooks.com/organic-compounds.html

How to cite: Kruszewski, Ł.: Gas-phase element transfer, rare mineral deposition, and other exhalative phenomena associated with coal fires in heaps: the state of art based on the data from the Upper Silesian Coal Basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6008, https://doi.org/10.5194/egusphere-egu23-6008, 2023.

EGU23-6557 | ECS | Posters virtual | ERE1.12

Semi-enclosed experimental system for coal spontaneous combustion for determining regional distribution of high-temperature zone of coal fire. 

Jingyu zhao, Hanqi Ming, Shiping Lu, Xiaocheng Yang, Yueyan Xiao, Xinrong Jiang, and Rui Li

Temperature variation and gas generation at different depths and positions in the coal combustion process were studied to determine the propagation and evolution of high temperature regions in the process of coal spontaneous combustion. This study selected coal samples from Mengcun, Shaanxi Province, People’s Republic of China, and developed a semi-enclosed experimental system (furnace) for simulating coal combustion. The thermal mass loss of coal samples under various heating rates (5, 10, and 15 °C/min) was analyzed through thermogravimetric analysis, and the dynamic characteristics of the coal samples were analyzed; the reliability of the semi-enclosed experimental system was verified through the equal proportional method of fuzzy response. The results revealed that the high-temperature zone was distributed nonlinearly from the middle to the front end of the furnace, and the temperatures of points in this zone decreased gradually as the layer depth increased. The apparent activation energy of the coal samples during combustion first increased and then decreased as the conversion degree increased. Furthermore, the proportion of mass loss and the mass loss rate in the coal samples observed in the thermogravimetric experiment was consistent with that observed in the first and second stages of the experiment conducted using the semi-enclosed system. The research findings can provide a theoretical basis for the prevention and control of high-temperature zones in coal combustion.

How to cite: zhao, J., Ming, H., Lu, S., Yang, X., Xiao, Y., Jiang, X., and Li, R.: Semi-enclosed experimental system for coal spontaneous combustion for determining regional distribution of high-temperature zone of coal fire., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6557, https://doi.org/10.5194/egusphere-egu23-6557, 2023.

Exploitation of coal mining is an important part for economic development, but the exploitation of coal mining will bring a serious impact on the local ecological environment. Ecological restoration is an effective method to improve the ecological environment in the mining areas. The first step of ecological restoration in post-mine is  to rebuild a sustainable mine-soil system. Fine soil overburden is often used in reconstructing soil profiles to provide habitat for vegetation restoration. Fine soil overburden will change the infiltration and evaporation of soil water. However, the understanding of the infiltration and evaporation of soil water is still an ongoing challenge. In this study, four groups of clay soil thicknesses (25 cm, 20 cm, 15 cm and 10 cm) were set up to simulate the overburden fine soil in post-mine ecological restoration, to study the influence of cover fine soil thickness on soil water infiltration and evaporation. The results showed that: a) the correlation between cover clay soil thickness and wetting front migration velocity was negative, namely, the thicker the cover clay soil thickness, the slower the wetting front migration velocity, and the smaller the average infiltration velocity is. However, the amount of water holding in thick overburden clay soil was more than the thin overburden clay soil. b) The overlying clay soil would improve soil water evaporation, but it wasn’t significant(p>0.1) with the thickness. The amount of soil water evaporation was low than the amount of water infiltration in thick overburden clay soil, so, the thick overburden soil could hold more water for the vegetation utilization. c) With the progress of soil water evaporation, the rate of evaporation was decreased with the increase of clay soil cover thickness. The greater the soil cover thickness, the stronger the soil water retention capacity. From the experimental result, the thick clay soil cover could remain more water, and is more suitable for vegetation establishment in post-mining restoration.

How to cite: chengzhi, L.: Influence of soil overburden thickness on water infiltration and evaporation characteristic in post-mine restoration, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7056, https://doi.org/10.5194/egusphere-egu23-7056, 2023.

EGU23-7139 | Posters virtual | ERE1.12

Correlation analysis of the change law of index gas and active functional groups in the process of high-temperature spontaneous combustion of minerals in the Fushun West Mine. 

Jia-Ming Chang, Jing-Yu Zhao, Jia-Jia Song, Ting-Hao Zhang, Gai Hang, Zhao-Long Chi, and Chen Wang

The spontaneous combustion of underground minerals causes huge property losses and ecological damage. Coal and oil shale are co associated minerals in the Fushun West Mine, and both have the ability of oxidative spontaneous combustion. To study the effect of microstructure changes on the macroscopic gas product concentration during the mineral oxidation spontaneous combustion process in the Fushun West Mine, this study used a high-temperature temperature-programmed test to obtain the change trend of gas product concentration in different oxidation stages of minerals. Using Fourier transform infrared spectroscopy (FTIR) technology, the changes in active functional groups of surface molecules during the process of mineral oxidation and spontaneous combustion were identified. Finally, using the gray correlation degree, correlation analysis between the concentration of gas products and the concentration of active functional groups in different oxidation stages was carried out. The key reactive functional groups affecting mineral spontaneous combustion were identified. The essential reason for the change in the gas product was revealed.

How to cite: Chang, J.-M., Zhao, J.-Y., Song, J.-J., Zhang, T.-H., Hang, G., Chi, Z.-L., and Wang, C.: Correlation analysis of the change law of index gas and active functional groups in the process of high-temperature spontaneous combustion of minerals in the Fushun West Mine., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7139, https://doi.org/10.5194/egusphere-egu23-7139, 2023.

EGU23-7247 | ECS | Orals | ERE1.12

PostMinQuake: analysis of post-mining induced micro-seismicity in former European hard coal regions. 

Paloma Primo Doncel, Tobias Rudolph, and Stefan Möllerherm

Underground mining operations, in which large amounts of rock are extracted, can induce seismic events. Furthermore, draining the water to prevent it from flowing into the mining works is necessary for hard coal mines. Once mining stops, the pumping rates of groundwater decrease or is no longer necessary, allowing the water level to return to its state prior to the construction of such mines. During the post-mining phase in hard coal regions, induced micro-seismicity represents a risk for future land use. The EU-PostMinQuake project, funded by the Research Fund for Coal and Steel (RFCS), aims to study the dependency of such events and the rising water table in hard coal basins to detect and manage the risks of post-mining seismicity. This contribution shows the relation between water and seismicity in four former underground hard coal mines located in Czech Republic, France, Germany and Poland.

How to cite: Primo Doncel, P., Rudolph, T., and Möllerherm, S.: PostMinQuake: analysis of post-mining induced micro-seismicity in former European hard coal regions., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7247, https://doi.org/10.5194/egusphere-egu23-7247, 2023.

Accurate identification of high temperature area of coal fire is the premise of coal fire control, coal fire monitoring is the test of coal fire control effect, coal fire detection and monitoring are the key and difficult points of coal field fire fighting engineering. This report first introduces the characteristics of high temperature anomalies in coal fire areas, Abnormal characteristics include: abnormal temperature, spontaneous potential, magnetic field intensity, resistivity, gas content. and then proposes targeted detection and monitoring methods on this basis. Commonly used methods include: Temperature measurement method, thermal infrared remote sensing method, natural electric field method, magnetic method, high density resistivity method, transient electromagnetic method, gas component measurement method, radon gas measurement method, and so on. Finally, comprehensive comparative analysis is adopted to achieve the purpose of identifying and monitoring the fire area.

How to cite: Yuan, Y.: Introduction of detection and monitoring methods in coal field fire, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7322, https://doi.org/10.5194/egusphere-egu23-7322, 2023.

EGU23-8255 | Posters virtual | ERE1.12

Study on the Flow Field Variation in Fracture Channel of Coalfield Fire 

Qing-Wei Li, Hui-Pan Fan, Li-Feng Ren, Yang Xiao, and Qiang Zeng

The coalfield fire area is widespread in the world. Numerous coal resources have been destroyed because of the large-scale coalfield fires. Meanwhile, toxic and harmful substances, such as carbon monoxide, carbon dioxide, methane, sulfide, and nitrogen oxide, etc., are numerously generated. All of them threat the local ecological environment and the economic development. The occurrence and evolution processes are complex, challenging the scientific prevention and control for coalfield fire. Gas transport mechanism is one of the key points that influence coalfield fire evolution and its efficient prevention and control. This investigation mainly pays attention to the flow filed in underground coalfield fire area. Combining physical test and numerical simulation, the transition law of the main air supply channel in underground coalfield fire area is studied, and the distribution characteristics of flow field in the channels are revealed. These are of great significance for revealing the evolution process of coalfield fire.

How to cite: Li, Q.-W., Fan, H.-P., Ren, L.-F., Xiao, Y., and Zeng, Q.: Study on the Flow Field Variation in Fracture Channel of Coalfield Fire, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8255, https://doi.org/10.5194/egusphere-egu23-8255, 2023.

EGU23-10406 | ECS | Posters virtual | ERE1.12

Intelligent coordinated control technology of dust-gas in underground excavation face in highly gas mine, China 

Yong Cao, Yang Xiao, Zhenping Wang, and Qingwei Li

As a chronic hazard, coal mine dust is widely distributed in mines around the world, especially in China, and the number of cases of pneumoconiosis caused by coal mine dust remains high every year. In highly gas mines, excavation work is at risk of exceeding gas concentrations, which could cause gas-coal explosions under certain conditions. The underground excavation face of the high gas mine urgently needs to solve the gas overrun problem caused by dust prevention and control work. In this work, gas-coal dust monitoring and early warning technology was used, to establish a treatment concept combining intelligent wind control and dust removal and gas overrun prevention and control. Via numerical simulation with FLUENT, to determine the air volume ratio of gas over limit prevention and control, the optimal dust removal air volume ratio, and applied in the field. The results indicated that the intelligent wind control technology had a excellent prevention effect on the problem of dust-gas coexistence.

How to cite: Cao, Y., Xiao, Y., Wang, Z., and Li, Q.: Intelligent coordinated control technology of dust-gas in underground excavation face in highly gas mine, China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10406, https://doi.org/10.5194/egusphere-egu23-10406, 2023.

As a new green chemical inhibitor, ionic liquids can inhibit spontaneous combustion of coal by dissolving and destroying the active structure in coal. In order to investigate the influence of ionic liquids with different concentrations on the molecular structure and the characteristics of low temperature oxidation kinetics of coal at oxygen-poor environment, taking Wucaiwan coal sample in Zhundong mining area as the research object, the molecular structure model of Wucaiwan coal in Zhundong mining area is constructed, and 1-(2-hydroxyethyl)-3-methylimidazole tetrafluoroborate [HOEtMIm] [BF4] ionic liquid is selected. The effect of ionic liquid on coal is investigated from macroscopic and microscopic levels by means of NMR carbon spectroscopy, X-ray photoelectron energy, infrared spectroscopy, thermogravimetry and X-ray diffraction. The results show that different concentrations of [HOEtMIm] [BF4] ionic liquids increase the ignition temperature point and the maximum weight loss rate temperature point of coal samples. The percentage of weight loss in the rapid oxidation stage and the whole combustion process of spontaneous combustion decreases with the increase of ionic liquid concentration. Compared with coal samples treated with other concentrations, the coal samples treated with 15% ionic liquids show good stability, and the fluctuation range of combustion characteristics parameters is small, which shows that high concentration ionic liquids can effectively reduce the influence of temperature on coal samples. Different stages of coal spontaneous combustion oxidation follow different reaction mechanism. The activation energy of the coal samples treated with different concentrations of [HOEtMIm] [BF4] ionic liquids did not change obviously in the evaporation and desorption stages of water, and the flame retardant effect was mainly shown in the oxygen absorption and weight gain stages and thermal decomposition stages. Higher concentration of ionic liquids can make aliphatic, oxygen-containing functional groups and side chains in coal structure fall off , so that the macromolecules of coal are arranged more closely, and the arrangement of organic carbon atoms tends to be oriented and regular gradually. The concentration of ionic liquids changed the polymerization degree of coal macromolecules, and the concentration of ionic liquids was proportional to the polymerization degree of coal macromolecules.

How to cite: Hao, R. and Zeng, Q.: Effect of Ionic Liquids with Different Concentrations on Molecular Structure and Combustion Performance of Coal, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10504, https://doi.org/10.5194/egusphere-egu23-10504, 2023.

Dust suppressant is an important way to improve the efficiency of wet dust removal,but the dust suppressant currently used in mine is generally chemical dust suppressant,which faces challenging problems of low interfacial activity, high cost, poor degradation,as well as environmental pollution and other issues. To synthesis biological dust suppressant (BDS), a new idea of microbial fermentation technology is proposed. Response surface optimization method was used to explore optimal fermentation conditions. These results show that BDS can be produced to the maximum capacity under the conditions of temperature =37.56℃, pH =7.99, rotating speed =220 r/min, inoculant =2.17%, and liquid loading =59.89 ml.XRD, FTIR and HPLC-MS/MS were adopted to explore the structural features of BDS. Its molecular structure shows a cyclic lipopeptide. The wettability was tested with interface rheometer and we found its good wetting ability under the concentration of 0.06wt‰ compared with chemical dust suppressant. At the same time, dust reduction performance was studied with self-developed test system and BDS showed good performance in dust reduction efficiency. Its application prospects are broad, which may open a new situation for green and efficient control of mine dust.

How to cite: Wang, H. and Zhang, Q.: Basic research on application of green dust suppression materials in mines, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10676, https://doi.org/10.5194/egusphere-egu23-10676, 2023.

EGU23-16711 | Orals | ERE1.12

Utilization of coal wastes in municipal waste landfill reclamation – a Katowice-Wełnowiec case study, Poland 

Justyna Ciesielczuk, Monika J. Fabiańska, Magdalena Misz-Kennan, Jolanta Pierwoła, and Anna Abramowicz

Coal mining produces a huge amount of waste which is stored in dumps located in close vicinity of coal mines and settlements. As organic matter is still present in deposited claystones, mudstones, sandstones, carbonates, and conglomerates, they are susceptible to self-heating, causing environmental problems. However, these wastes can also be utilized to reduce the amount of waste and the number of dumps.

The municipal waste landfill, operating from 1991 to 1996 for the Katowice town in Wełnowiec district, in Upper Silesia Coal Basin, Poland, was reclaimed with coal wastes. In total, a rubbish dump collected about 1.6 million tonnes of urban waste, composed of ca. 22.5% of coal waste, ca. 21.5% of municipal waste, ca. 40% of building waste and the remainder of composting plant waste. The residents living next to the dump complained about unpleasant odours. This is why it was decided to reclaim the municipal waste landfill and form a multi-barrier system composed of 0.3 m of compacted coal mine wastes, 0.5 m of clays, 0.1 m of sand, 0.3 m of gravel, 0.6 m of uncompacted coal mine waste mixed with soil, and 0.4 m of humus on the top. In 2001, it was decided to exploit biogas (methane) from the dump, and a total of 39 boreholes were drilled. Unfortunately, the rehabilitation caused self-heating and self-ignition to occur, and the first intense fire broke out in the eastern part of the northern slope in November/December 2008, emanating harmful components to the soil, air, and groundwater.

We proved geophysically, that properly planned reclamation has never been performed. Much more coal wastes with much higher organic matter content were deposited on the dump without any packing and fire-preventing measures. The most intensive fire expanded at the northern slope and appeared as hot spots in the eastern and southern parts. The temperature was elevated exceeding 80oC in these places preventing plants from growing. The highest measured temperature reached 770oC at 0.3 m subsurface. Vents and fissures which emit hot exhalations containing water vapour, carbon mono- and dioxide, methane, and other light hydrocarbons were encrusted by exhalating minerals. There the dump surface was permeated with water and bitumen formed in pyrolytical conditions in a self-heating zone located deeper within the dump.

Geophysical methods revealed up to 26 m of municipal waste covered by the irregularly distributed material of varying thickness and composition instead of a designed 2.2-m-thick multi-barrier system. The real thickness of coal wastes used for reclamation of the municipal Wełnowiec dump was documented and amounts from 1 to 8 m. The consequence is intensive burning and the necessity of prevention. Where the volume of coal waste is not adequate for thermal activity, no thermal activity was noticed. Where the volume is only just sufficient, small hot spots (< ~20m in diameter) appear and wane. Where the volume of coal waste used in rehabilitation was much greater than planned, as on the northern slope of the dump, burning could spread for many years and require professional firefighting to stop it.

How to cite: Ciesielczuk, J., Fabiańska, M. J., Misz-Kennan, M., Pierwoła, J., and Abramowicz, A.: Utilization of coal wastes in municipal waste landfill reclamation – a Katowice-Wełnowiec case study, Poland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16711, https://doi.org/10.5194/egusphere-egu23-16711, 2023.

The intracontinental High Atlas Mountains are the result of multiple tectonic events, from Late Permian-Early Mesozoic Pangea breakup to Cenozoic Africa-Eurasia convergence. Prior to the Cenozoic inversion event, the South Atlas Fault Zone (SAFZ), which surrounded the High Atlas from the south, witnessed for the growth of multiple basins during the Liassic rifting in the eastern segment of the belt. The present work aims to shed light on the development of the Beni Bassia Liassic basin through two faults components of the SAFZ, the E-W J. Amalou faulted anticline (ridge) and Garn Talou fault from the South. Preliminary investigations based on the combination of field data and satellite images reveal significant results regarding the evolution of the basin. In the Beni Bassia Basin, the Ouchbis-Pleinsbachian Formation is an alternating layer of conglomerate limestones and marls, containing olistoliths over 10 meters in length, resulting from the destruction of the underlying platform of the Idikel-Sinemurian Formation. This huge breccia developed at the foot of steep faults on the southern margin of the basin, during the acceleration of the Liassic rifting. During the Cenozoic deformation and uplift of the Eastern High Atlas, bedding directions of Jurassic formations denote progressive changes from E-W in the northwestern to approximately NW-SE to N-S in the southeastern part of the basin. Similarly, the dip direction changes from dipping towards the south to dipping southwest to westward, indicating a dextral movement due to NNW-SSE regional shortening driven by the plates convergence. Other smaller-scale structures confirm dextral transpression kinematics at several places east of the High Atlas, including easterly detachments recorded in Lower Jurassic carbonates. Further investigations are planned to quantify the stress, strain and mechanisms involved in the configuration of the Liassic basin and the subsequent Cenozoic transpression.

Keywords: Eastern High Atlas, South Atlas Fault Zone, Beni Bassia Basin, Jurassic, Inversion, Transpression.

How to cite: Es-sabbar, I., Amrouch, K., Soulaimani, A., and Skikra, H.: Cenozoic inversion of the Lower Jurassic Beni Bassia Basin in the Eastern High Atlas (Morocco): effect of the right lateral transpression along the South Atlas Fault Zone (SAFZ), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2104, https://doi.org/10.5194/egusphere-egu23-2104, 2023.

EGU23-2858 | ECS | Posters virtual | ERE1.13

Upper Crust structural evolution of the Alpine orogeny in an intracontinental belt: Western High Atlas (WHA) Mountains, Morocco 

Salih Amarir, Khalid Amrouch, Mhamed Alaeddine Belfoul, and Hamza Skikra

The Atlas system is an intracontinental chain established upon a Paleozoic substratum by the inversion of Triassic basins starting in the late Mesozoic-early Cenozoic. The inversion of the chain is related to the Atlas rift system that was influenced by the opening of the Central Atlantic in the West and the Tethys in the north. This was coeval with a regional exhumation following the Alpine shortening responsible for the continuous uplifting of the chain since Late Cretaceous. The structural history and chronology of events are still matter of debates. To contribute to this, we focus on the Western High Atlas (WHA) aiming a retro enactment of the paleo-stresses states, by analyzing deformation structures at various scales. The geological data were collected at different stratigraphic levels: from the contact Paleozoic basement/Mesozoic cover interface to the Triassic detrital formations of the Argana corridor in the east, to the Jurassic-Cretaceous and Cenozoic plateaus in the west. Preliminary results highlight two major tectonic events: (1)- a first extensive event, with sub-horizontal minimal principal stress σ3 oriented NW-SE, that is linked to the Central Atlantic basin opening. This event is characterized by pull apart basins structured into horsts and grabens. (2)- a second compressive event, marked by NE-SW to NNE-SSW shortening. The later is subdivided into two episodes: i- an early post-rift episode (Middle-Late Jurassic to Early Cretaceous), marked by stylolites and meso-structures that occurred at the beginning of the main uplifting stage. ii- a late compression episode, characterized by a maximum principal stress σ1 mainly oriented NNE-SSW to NNW-SSE, starting at the late Cretaceous and accelerating during the Tertiary, simultaneously with the Africa-Europe collision.

Keywords: Paleo-stress, Structural analysis, Atlas rift system, Tectonic inversion, Western High Atlas Morocco, Alpine orogeny.

How to cite: Amarir, S., Amrouch, K., Belfoul, M. A., and Skikra, H.: Upper Crust structural evolution of the Alpine orogeny in an intracontinental belt: Western High Atlas (WHA) Mountains, Morocco, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2858, https://doi.org/10.5194/egusphere-egu23-2858, 2023.

EGU23-2949 | ECS | Posters virtual | ERE1.13

Reconstructing the Pre-Alpine cycle of Moroccan Atlas system before the inversion phase 

Mouad Ankach, Khalid Amrouch, and Mohamed Gouiza

The Wilson Cycle (ca. 250-300 Ma) is driven by plate tectonics, and is expressed by the opening of oceanic basins, which are subsequently closed to form orogens. Morocco has experienced several orogenic cycles: e.g., Eburnean, Pan-African, Hercynian (Variscan) and Alpine (Atlasian). The last Wilson Cycle that shaped the geology of Morocco is the Alpine Cycle (300-0 Ma). It started by the dismantlement of the Pangea Supercontinent leading to the opening of the Atlantic Ocean and the Atlas rift system. The latter was subsequently aborted and inverted into a fold-and-thrust belt during the Cenozoic, due to the opening of the South Atlantic and the convergence between Africa and Iberia-Europe. The Atlas system of NW Africa includes two intracontinental ranges, the High and Middle Atlas extending ENE-WSW and NE-SW, respectively. It is a key piece in the Pangea breakup puzzle, as its evolution captures the kinematic of the African plate during Mesozoic to Cenozoic times. Several studies have examined the structural and stratigraphic architectures of the Atlas system during the rifting phase, by removing the Alpine inversion along palinspaticly reconstructed 2D sections. However, little was done to investigate the crustal structure and the amount of crustal stretching during the Triassic to Jurassic extension. This work aims to reconstruct the pre-alpine architecture of the Atlas system and link it directly with the evolution of the crust. Our goal is to provide insights into the amount of crustal thinning that took place during the Mesozoic rifting in the Atlas domain and constrain the strain distribution within the African plate during the dismantlement of the Pangea.

Key words: Wilson cycle; Atlas system; Pangea; Break up; Inversion; Pre-Alpine cycle.

How to cite: Ankach, M., Amrouch, K., and Gouiza, M.: Reconstructing the Pre-Alpine cycle of Moroccan Atlas system before the inversion phase, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2949, https://doi.org/10.5194/egusphere-egu23-2949, 2023.

EGU23-5266 | ECS | Posters on site | ERE1.13

Stress and strain patterns related to the inversion of the High Atlas aborted rift 

Hamza Skikra, Khalid Amrouch, Abderrahmane Soulaimani, and Salih Amarir

The Moroccan High Atlas is an Alpine fold belt formed by the structural inversion of Mesozoic rift basins during the Late Cretaceous-Cenozoic. The involvement of mantle-related thermal mechanisms is anticipated to account for the anomalously elevated orogen and surrounding plateaus and basins. In the range’s Western portion, the Marrakech High Atlas displays the most pronounced basement exposure at the range scale. Recent studies highlighted the role of thick-skinned tectonics thrusting and folding during the basin inversion. Although several works brought considerable insights into the actual understanding of the High Atlas structural evolution, there is still an ambiguity regarding the kinematics, paleostresses, and tectonic regime associated with the basin inversion. In the present work, we examine the paleostresses history of the High Atlas fold belt through analyses of mesostructures i.e. striated faults planes, micro-shear fractures/veins, tensile fractures/veins, stylolites and mesoscale folds, in the northern and southern borders of the Marrakech High Atlas. The aim of this work is to illustrate the tectonic complexity of orgenic belts developed in an intracontinental setting far from the plates’ collision boundaries.

How to cite: Skikra, H., Amrouch, K., Soulaimani, A., and Amarir, S.: Stress and strain patterns related to the inversion of the High Atlas aborted rift, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5266, https://doi.org/10.5194/egusphere-egu23-5266, 2023.

EGU23-5478 | Posters on site | ERE1.13 | Highlight

How to create the highest manganese ore grade in the world? A geodynamic story in the Atlas of Morocco. 

Augustin Dekoninck, Jocelyn Barbarand, Gilles Ruffet, Yves Missenard, Nadine Mattielli, Rémi Leprêtre, Abdellah Mouttaqi, Omar Saddiqi, Michèle Verhaert, and Johan Yans

The Imini mining district (Morocco) hosts the largest manganese (Mn) ore deposits of North Africa (~120.000 T in 2016). The area is world recognized for hosting several epigenetic karst-type high-grade manganese deposits in a 10-15 meters thick Cenomanian-Turonian dolostone unit. These unconventional Mn oxide deposits occur along a belt of ~25-30 km in the southern foreland of the intraplate Atlasic belt of Morocco. This is due to two laterally extensive ore bodies of nearly pure pyrolusite-rich manganese ores (72-88 wt.% MnO2) and a third discontinuous medium-grade coronadite-rich Mn ore (40–48 wt.% MnO2)(Dekoninck et al., 2016a, b; Gutzmer et al., 2006). Our recent works allowed precise dating and geodynamic reconstructions of the ore deposit genesis. The ore depositions occurred during (i) late Cretaceous to late Paleocene (~ 92 Ma, ~ 78–82 Ma, ~ 65–67 Ma and ~58 Ma), (ii) late Eocene (c. 36 Ma), and (iii) early Burdigalian to early Serravalian probably in two pulses at c. 19–20 Ma and c. 13 Ma (Dekoninck et al., 2021, 2023). This multistage deposition coincides with three geodynamic events linked to the uplift of the Atlas. The late Cretaceous uplift of the Atlas created the required hydraulic head to sustain (1) fluid-rock interactions between O2-poor acidic ground waters and the Triassic series source, (2) migration of the metal-rich low-temperature hydrothermal fluid from the rock source and (3) overpressure fluid in the Imini depositional site. The vanishing of Triassic series above the Imini anticline forced these hydrothermal fluids to mix with oxygenated ground and alkaline waters resident in the karst system and precipitated the Mn oxides. The N70°-oriented Atlasic tectonic structure controls the orientation of these epigenetic karst-hosted Mn deposits. The late Eocene – Early/Middle Miocene uplifts generated additional supplies and/or in-situ remobilizations of the primary late Cretaceous medium-grade ore to form the high-grade pyrolusite-rich ore.

References

Dekoninck et al. 2023 (accepted). Mineralium Deposita. Dekoninck et al. 2016. Mineralium Deposita 51, 13-23. Dekoninck et al. 2016. in: Mineral Deposits of North Africa. Springer International Publishing, Cham, pp. 575–594. Dekoninck et al. 2021. Mineralium Deposita 59, 935–956. Gutzmer et al. 2006. Economic Geology 101, 385–405.

How to cite: Dekoninck, A., Barbarand, J., Ruffet, G., Missenard, Y., Mattielli, N., Leprêtre, R., Mouttaqi, A., Saddiqi, O., Verhaert, M., and Yans, J.: How to create the highest manganese ore grade in the world? A geodynamic story in the Atlas of Morocco., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5478, https://doi.org/10.5194/egusphere-egu23-5478, 2023.

EGU23-8854 | ECS | Posters on site | ERE1.13 | Highlight

Integrated Workflow for Petroleum System Analysis: Application to the East Beni Suef Basin, Egypt 

Ahmed Yousef Tawfik, Robert Ondrak, Gerd Winterleitner, and Maria Mutti

Integrating geological and 2D basin modeling of the East Beni Suef Basin, located in north-central Egypt, allows extending burial and thermal history modeling into the deeper parts of the basin, which are not explored by drilling activities thereby evaluating the hydrocarbon potential of the actual kitchen areas. In addition, this regional approach allows us not only to study the hydrocarbon generation potential of the deeper kitchen area but also the migration and accumulation history of the basin. The East Beni Suef Basin (EBSB) is an extensional rift basin, which was initiated following the opening of the NeoTethys and Atlantic oceans and the associated tectonic motion of Africa with respect to Eurasia during the Early Cretaceous. Its stratigraphy comprises five main rock units of mixed siliciclastic-carbonates ranging from the Albian to the Eocene from base to top as follows: Kharita Formation, Bahariya Formation, Abu Roash Formation, Khoman Formation, and Apollonia Formation. The Upper Cretaceous Abu Roash Formation is divided into seven members based on the siliciclastic to non-clastic ratio and includes the main petroleum system elements of the basin, where the carbonate “F” Member is the source rock, while the siliciclastic portions of the “E” and “G” members constitute the reservoir rocks. This study aims to gain insight into the geological evolution of the EBSB and to improve our understanding of its Upper Cretaceous petroleum system, in terms of burial and thermal histories, source rock maturity, and hydrocarbon generation, migration, and accumulation. Thus, an integrated geological and basin modeling workflow was employed, making use of two basin-wide seismic sections, crossing the EBSB in SW-NE and NW-SE directions, and three boreholes with well data. The interpreted 2D seismic lines served as the basis to define the geometrical and structural framework and the development of the subsequent 2D basin modeling of the basin. Modeling results indicate that the Abu Roash “F” source rock maturity ranges from the early oil window at the basin margins to the main oil window in the center. The main phase of hydrocarbon generation occurred during the Eocene after trap formation in the Late Cretaceous. Generated hydrocarbons have migrated both laterally and vertically, most likely from the central part of the basin toward the basin margins, particularly eastward to the structural traps. The model predicts low accumulation rates for the EBSB, which are caused by the ineffective sealing capacity of the overburden rocks and normal faults. In addition to the proven kitchen for the charging of the Abu Roash “E” reservoirs, an additional kitchen to the west of the basin is suggested for the Abu Roash “G” reservoirs. The results of this work can better elucidate the present-day distribution of the Upper Cretaceous accumulations in the EBSB for further successful exploration activities.

How to cite: Tawfik, A. Y., Ondrak, R., Winterleitner, G., and Mutti, M.: Integrated Workflow for Petroleum System Analysis: Application to the East Beni Suef Basin, Egypt, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8854, https://doi.org/10.5194/egusphere-egu23-8854, 2023.

EGU23-12569 | Posters on site | ERE1.13

GIS-based morphotectonic and geomorphometric assessment for the Moroccan High Atlas mountain ranges, Morocco. 

Athanasios V. Argyriou, Hamza Skikra, Khalid Amrouch, and Abderrahmane Soulaimani

The geomorphological and tectonic processes being responsible for the control of the mountain ranges geometry is feasible to be assessed through geomorphological and morphotectonic indices. Those indices are dependent on tectonic or erosional processes and other factors influencing the development of the landforms. Tectonic geomorphology applications using satellite-based remotely sensed data, such as Digital Elevation Models (DEMs), can highlight specific geomorphic features capable to provide useful information and knowledge towards the evaluation of the regional tectonic activity in mountain ranges. This study examines the Moroccan High Atlas mountain range by using morphotectonic and geomorphometric indices such as the channel steepness index, amplitude of relief index, stream length gradient index, swath profiles, local relief and hillslope mapping to determine the distribution of the tectonic activity variations. Through those indices the evaluation of the geomorphic responses to tectonics takes place by highlighting the relationships between tectonic activity, rock resistance, stream channel slope, active or recent vertical displacements. The outcomes of the geomorphometric and morphotectonic investigation highlight the presence of considerable geomorphic variations across the main fault zones featuring the orogen’s anatomy, while tectonic activity seems to be a major factor controlling and shaping the Moroccan High Atlas mountain range landscape. The methodological framework of this study could be developed into a low-cost technique for assessing seismic hazard, offering a valuable tool towards assessing disaster risk reduction activities, whereas in conjunction with other factors the georesources exploration. 

 

Acknowledgements

The corresponding author acknowledges the 'EXCELSIOR': ERATOSTHENES: Excellence Research Centre for Earth Surveillance and Space-Based Monitoring of the Environment H2020 Widespread Teaming project (www.excelsior2020.eu). The 'EXCELSIOR' project has received funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement No 857510, from the Government of the Republic of Cyprus through the Directorate General for the European Programmes, Coordination and Development and the Cyprus University of Technology.

How to cite: Argyriou, A. V., Skikra, H., Amrouch, K., and Soulaimani, A.: GIS-based morphotectonic and geomorphometric assessment for the Moroccan High Atlas mountain ranges, Morocco., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12569, https://doi.org/10.5194/egusphere-egu23-12569, 2023.

EGU23-1054 | ECS | Posters on site | ERE1.14

Assessing the climate change risk to underwater cultural heritage: the EU-funded WATERISKULT project 

Luigi Germinario, Isabella Moro, and Claudio Mazzoli

The impact of climate change on cultural assets represents a topical subject of scientific research, although spotlighting heritage sites on land while often neglecting the vulnerability of the underwater world. The WATERISKULT project (https://wateriskult.geoscienze.unipd.it), funded by the European Union under the Marie Skłodowska-Curie Actions, aims at filling that gap. The project will provide the first quantitative assessment of the risk to underwater cultural heritage, with a focus on archaeological stone, a material part of countless remains of ancient cities and ship cargoes sunken in the oceans. This contribution introduces WATERISKULT by presenting its layout and first research activities, based on an interdisciplinary approach (including petrography, oceanography, analytical chemistry, marine biology, hydraulic engineering, and underwater archaeology) and a mixed field and laboratory experimentation. The key-factors of climate change under investigation involve ocean acidification, sea level rise, ocean warming, and extreme weather events. Moreover, the causes and effects of current deterioration of archaeological stone materials are being explored, considering the Mediterranean Sea as pilot area. The research results are expected to help assessing the observed and predicted decay trends of underwater heritage sites, constrained by the diverse characteristics of the component materials and submarine environments.

How to cite: Germinario, L., Moro, I., and Mazzoli, C.: Assessing the climate change risk to underwater cultural heritage: the EU-funded WATERISKULT project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1054, https://doi.org/10.5194/egusphere-egu23-1054, 2023.

EGU23-2440 | ECS | Orals | ERE1.14

Extreme rainfall risk and climate change impact assessment for Edinburgh World Heritage sites 

Shane O'Neill, Simon Tett, and Kate Donovan

Change in climate extremes and the increased risk associated with human-induced global warming is apparent. Less apparent is the impact such changes may have on vulnerable systems in our society. Climate change impact assessments using state-of-the-art climate models coupled with damage information can offer actionable insight for stakeholders to better protect vulnerable systems.

Cultural heritage is an example of a system that is vulnerable to climate change, especially built cultural heritage which is directly exposed to changing climate extremes. In the UK, significant development has been achieved to better understand the potential change in climate extremes following the release of UK Climate Projections 18 (UKCP18), however, understanding of risk posed by these climate extremes to built cultural heritage is poorly constrained. How to assess and quantify this risk is in its infancy.

We have developed a new methodology building on previous work by cultural heritage experts - the Cultural Heritage Climate Risk Assessment (CHCRA) framework. The CHCRA framework focuses on combining stakeholder engagement and high-resolution climate models to develop site-specific projections of potential damage to cultural heritage assets. This integrated framework when applied with adequate information allows estimation of expected damages to cultural heritage assets through the 21st century.

We applied the CHCRCA framework to cultural heritage buildings in the Edinburgh World Heritage Site, Scotland, considering one-day extreme rainfall events. This pilot study used UKCP18 2.2 km resolution climate projections alongside qualitative and quantitative damage data obtained from multiple sources.

Importantly, UKCP18 2.2 km model is a Convection Permitting Climate Model with the ability to better represent extreme rainfall events. Furthermore, expert elicitation through interviews with practitioners from cultural heritage organisations within Edinburgh were carried out to obtain damage information specific to cultural heritage buildings in the Old and New Town Edinburgh (ONTE), part of the Edinburgh World Heritage Site. A damage function was derived based on expert elicitation and other sources.

Key findings include annual expected damage per year increases from 0.6% in the baseline period (1981-2000) to 1.5% in 2021-40 and 2.3% in 2061-80. A three-to-four-fold increase in annual expected damage to cultural heritage buildings in the ONTE is expected towards the end of the 21st century.

This is the first application of the CHCRA framework. This pilot study considered only one climate stressor, extreme one-day rainfall events. Damage at built cultural heritage is likely exacerbated and accelerated by other climate stressors, as well as non-climate related factors such as poor maintenance. Furthermore, damage caused by pluvial and/or fluvial flooding mechanisms were not taken into consideration, as well as no consideration given to reduction in risk due to adaptive measures.

This study provided insight into the changing risk posed by an impactful climate stressor to cultural heritage buildings in the ONTE. The study highlights the importance of stakeholder engagement from the outset when carrying out a climate change impact assessment. Further work may benefit from considering a more wide-ranging array of climate stressors to capture synergistic damage processes.

How to cite: O'Neill, S., Tett, S., and Donovan, K.: Extreme rainfall risk and climate change impact assessment for Edinburgh World Heritage sites, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2440, https://doi.org/10.5194/egusphere-egu23-2440, 2023.

EGU23-3237 | ECS | Orals | ERE1.14

Impact Assessment of Pollution and Climate-Induced Damage on Historic Centre of Rieti (Italy) 

Alessandro Sardella, Linda Canesi, Nisha Prashanth Setty, Raffaela Gaddi, and Alessandra Bonazza

The conservation and protection of cultural heritage, seen in its broadest definition, face ongoing and new challenges as a result of the impacts of slow and extreme climate changes. Therefore, there is the need of further studies and the development of improved methods in order to support decision makers and public authorities in preparing plans to manage and mitigate the correlated risks.

The present contribution aims at analysing and assessing the impacts of pollution and climate change induced extremes on the built heritage located in the historic centre of Rieti (Italy). This research has been conducted in the framework of the Interreg Central Europe Project STRENCH (STRENgthening resilience of Cultural Heritage at risk in a changing environment through proactive transnational cooperation, 2020–2022) and the National Italian Project "Piano Straordinario di Monitoraggio e Conservazione dei Beni Culturali Immobili'', coordinated by the Ministry of Culture. First, the pollutants data (NO2, SO2, O3, PM2,5 and PM10) extracted from air quality monitoring station at Rieti (IT0867A) were analysed and interpreted in accordance with the limiting values mandated by Italian law (legislative Decree 155 of 2010) for the characterization of air quality. Further, surface recession of carbonate stones for the period of 2011-2021 was calculated using Lipfert (1989) and Kucera et al. (2007) damage functions. Then, the “Risk Mapping tool for Cultural Heritage Protection” (https://www.protecht2save-wgt.eu/) was exploited: time series based on earth observation data (e.g. Copernicus C3S reanalysis and NASA GPM IMERG products), historical changes based on EOBS dataset and future hazard maps at territorial level based on outputs from regional and global climate models (EURO-CORDEX initiative) were investigated.

Obtained results reveal that a constant slight decline trend of pollutants annual average is shown over the years from 2011 to 2019. During 2020, lower values for each pollutant component were observed, partially attributed to the lockdown caused by the Covid19 pandemic. It was also observed that each investigated gaseous pollutant and PM fractions were within the limits regulated by the Italian Law.

Regarding the surface recession analysis, it was observed that it has been decreasing over the past 10 years from 2010 with slight increases occasionally. Also here, a decline in 2020 attributed to the lockdown is clearly observable. Moreover, most of particles contributing to PM can be certainly attributed to vehicular traffic, among anthropogenic sources, and are therefore in the fine fraction.

Finally, climate future projections, with spatial resolution of 12x12km, show a general increase of the changes of the extreme indices taken into consideration (R20mm and Rx5day); the biggest variations are typically foreseen for the far future (2071-20100), under the pessimistic scenario (RCP 8.5), highlighting a high likelihood of heavy rain and flooding risk in the area of Rieti.

How to cite: Sardella, A., Canesi, L., Prashanth Setty, N., Gaddi, R., and Bonazza, A.: Impact Assessment of Pollution and Climate-Induced Damage on Historic Centre of Rieti (Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3237, https://doi.org/10.5194/egusphere-egu23-3237, 2023.

EGU23-5424 | Posters on site | ERE1.14

Characterization of the carbonate rocks of the Calcari di Cagliari Formation using a combined petrographic, geomatic and geophysical approach. 

Giuseppe Casula, Silvana Fais, Francesco Cuccuru, Maria Giovanna Bianchi, and Paola Ligas

The methods and the tools aimed at characterizing and analysing the carbonate materials used in the historic built heritage often follow different ways according to the different branches of applied research involved in the knowledge process. In this framework, the 3D digital models both of in situ architectural elements and of significative samples of rocks used as building materials can play an important role in relating different data and disciplines aimed at the prevention and conservation of the Cultural Heritage. Although the 3D geomatic and geophysical digital models represent privileged tools of the diagnostic analysis, they must be supported by the knowledge of the textural characteristics of the rocks under investigation with petrographic analyses. In order to study the stone materials heavily used in the historic built heritage and analyse their vulnerability to the conditions in their environment, it can be beneficial to study appropriately prepared samples and make as many measurements as necessary with different techniques. Moreover, some analyses are destructive and there is a limit to the number of samples that can be sacrificed. For this reason, in the analysis of rock samples, non-destructive techniques are constantly being improved. In this study, using a suitably implemented integrated methodology we analysed in detail samples of the carbonate rocks of the Calcari di Cagliari formation represented by Pietra Cantone, Tramezzario and Pietra Forte lithologies, mainly used in the past as construction materials for the buildings of the Historical Centre of Cagliari (Italy). Our methodology is represented by an integration of the geomatic survey carried out by structure-from-motion (SfM) digital close-range photogrammetry and the seismic tomography normally used for the in situ inspection adapted to laboratory tests on samples of the above lithologies using ultrasonic frequency signals. The rigorous metric of the geomatic 3D models was used to implement the ultrasonic survey by which internal characteristics and physical properties of the studied material are detected thanks to the spatial variations of the longitudinal velocity obtained after the tomographic inversion. The geomatic and geophysical data were complemented by an accurate analysis of the above carbonate materials by optical and scanning electron microscopy in order to detect their textural characteristics and especially the nature and distribution of their porosity. The microscopy analyses were integrated by mercury intrusion porosimetry (MIP) to obtain further information on the pore network, particularly on the effective porosity, pores-throat diameters/radii, permeability and tortuosity of the investigated materials. All the above parameters were found to affect the geomatic and geophysical behaviour of the carbonate materials. The integration of the multi-technique data produced in this study contributes to better understand the interaction between the investigated materials and the environment.

Acknowledgements

This work was supported by Regione Autonoma dellaSardegna (RAS) (Sardinian Autonomous Region), Regional Law 7th August 2007, no. 7, Promotion of scientific research and technological innovation in Sardinia (Italy), Resp. Sc. S.Fais.

How to cite: Casula, G., Fais, S., Cuccuru, F., Bianchi, M. G., and Ligas, P.: Characterization of the carbonate rocks of the Calcari di Cagliari Formation using a combined petrographic, geomatic and geophysical approach., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5424, https://doi.org/10.5194/egusphere-egu23-5424, 2023.

Built heritage, which gives identity to the urban fabric and fosters the collective memory of the community, is at risk of deterioration due to climate stressors. These stressors result from rapid urbanisation, covering surfaces with hard materials, and a disconnection from nature.

Today, nature-based solutions have become a growing trend as a way to reconnect with nature and mitigate the impact of climate change. Green infrastructures (GI), in particular, offer numerous environmental and social benefits, especially in dense urban areas, including improved air quality, reduced heat island effect, increased biodiversity and improved stormwater management, and stress-reducing and restorative effects on individuals.

Although built heritage sites form an important part of the urban fabric, they are often excluded from this green transition due to the risk of invasive species damaging historic buildings' structural and aesthetic integrity. Therefore, there is a lack of research analysing rigorously designed examples of GI in a historical context.

This study aims to narrow the focus to the sociocultural perception and acceptance of GI in a historical context. We will analyse spatial-perceptual patterns and socio-cultural motivations behind the deliberate use of GI in this context, using biophilic design principles and architectural perception theories as frameworks. Using GIS monitoring as a methodology, we will map and collect inventory data on real-life examples of GI applied to historical buildings in Belgium-Antwerp. The goal is to understand the correlations between spatial-perceptual factors and the use of GI in built heritage contexts.

How to cite: Kale, E., De Groeve, M., and De Kock, T.: Exploring the Socio-Cultural Compatibility of Green Infrastructures in Built Heritage Contexts: A Case Study in Antwerp (Belgium), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5685, https://doi.org/10.5194/egusphere-egu23-5685, 2023.

EGU23-5786 | ECS | Posters on site | ERE1.14

Pore-scale investigation of salt weathering in building heritage materials: combining AFM nano-indentation measurements and multiscale modeling. 

Clément Mathieu, Jérôme Wassermann, Pierre M. Adler, Sébastien Péralta, Jean-Louis Gallias, Ronan L. Hébert, and Philippe Bromblet

Salt weathering is a main cause of damage in building heritage materials. Despite the large amount of research on this topic, the mechanism of damaging processes remains not fully understood in particular at the pore scale where the salt crystallization and dissolution occur. For this reason, we propose an innovative approach combining damage proxy measurements at pore-scale using Atomic Force Microscopy (AFM), Raman spectrometry and multi-scale numerical modelling, performed during weathering cycles. Imbibition-evaporation cycles are performed on carbonate stones (Savonnières and Saint Maximin limestones) with a 0.1 mol/L sodium sulfate solution at controlled room temperature and relative humidity. The stone samples are especially designed for the measurements at the pore-scale. Cylinder of 1.6 cm diameter and 1.5 cm thickness have been coated with very viscous epoxy resin. Then the two sides of the cylinder have been polished to obtained two free surfaces that allow the fluid circulation in the sample and the measurements. After each weathering cycle, nanoindentation experiments are performed on representative areas of several hundreds of square micrometers in order to monitor the mechanical properties evolution. A force of the µN order is applied in order to stay in the elastic deformation regime. Young modulus values can be then deduced from the slope of the force curves that occurs during the cantilever deflection. With this method, the effect of salt weathering on the mechanical properties of stone minerals is investigated at the pore scale and with no impact of the measurement on the phases structure (reversible indentations). The AFM results are then coupled with chemical Raman mapping to identify the present phases and assign them their mechanical properties. The obtained experimental data are then used in numerical modeling, to generate a numerical Young modulus field with the same properties than the experimental field. Finally, a new medium with higher dimensions will be generated to compare the results with the macro-scale observations on building heritage stones. AFM characterization shows that changes occurred on the topography of the samples between the first and the third alteration cycles. They are of the order of several tens of nanometers and correspond either to salt crystals deposits or in some cases to the loss of material that took place between the second and the third cycle. A decrease of the Young modulus is observed after each cycle that is of the order of 2 GPa between the first and the second cycles. More significant changes are observed after the third cycle especially in some areas where a decrease up to 3 to 4 GPa is estimated.

How to cite: Mathieu, C., Wassermann, J., Adler, P. M., Péralta, S., Gallias, J.-L., Hébert, R. L., and Bromblet, P.: Pore-scale investigation of salt weathering in building heritage materials: combining AFM nano-indentation measurements and multiscale modeling., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5786, https://doi.org/10.5194/egusphere-egu23-5786, 2023.

EGU23-5956 | Posters on site | ERE1.14

Obtaining pore size distribution of porous stone using non-Newtonian fluids 

Martin Slavík and Martin Lanzendörfer

The characteristics of the pore space are considered a key factor in susceptibility of the stone to various weathering processes. The pore size distribution can be determined by a number of methods such as mercury intrusion porosimetry or computed topography. None of them is without disadvantages, namely the mercury intrusion porosimetry – despite being very popular – is the object of some critics due to the harmful effects of the mercury. Within the last decade, there has been a growing interest in the use of non-Newtonian fluids for obtaining the pore size distribution of the porous materials (see, e.g., Abou Najm and Atallah, 2016; Rodríguez de Castro et al., 2016). The principle exploits the behaviour of non-Newtonian fluids whose viscosity changes with shear rate. This is manifested by the fact that saturated flow of different fluids under different hydraulic gradients is distributed differently in the pore space. Therefore, conducting a set of saturated flow experiments with different fluids and/or under different hydraulic gradients allows – using a numerical model – to determine an approximation of the pore size distribution.

Our goal is to test feasibility of determining the pore size distribution using saturated flow experiments with low-concentration water-xanthan solutions (<1 g/l) under relatively small hydraulic gradients (<5). We have now completed a set of laboratory experiments for three types of sandstone and we are performing a sensitivity analyses of the parameters used in the numerical model. The presented approach is low-cost, easy-to-use and can serve as an alternative to mercury intrusion porosimetry in geoscience and various cultural heritage studies.

 

The research is funded by the Czech Science Foundation [21-27291S].

 

References:

Abou Najm, M.R., Atallah, N.M., 2016: Non-Newtonian Fluids in Action: Revisiting Hydraulic Conductivity and Pore Size Distribution of Porous Media. Vadose Zone Journal, 15(19), 1–15.

Rodríguez de Castro A., Omari, A., Ahmadi-Sénichault, A., Savin, S., Madariaga, L-S., 2016: Characterizing Porous Media with the Yield Stress Fluids Porosimetry Method. Transport in Porous Media, 114, 213–233.

How to cite: Slavík, M. and Lanzendörfer, M.: Obtaining pore size distribution of porous stone using non-Newtonian fluids, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5956, https://doi.org/10.5194/egusphere-egu23-5956, 2023.

EGU23-6252 | ECS | Orals | ERE1.14

Investigations of shallow aquifer groundwater systems of a Gallo-roman anthropized site using earth tide analysis 

Elijah Edet Nkitnam, Alexis Maineult, and Jérôme Wassermann

The prospect for the sustainability of the Gallo-Roman archeological site located in Genainville (France), where relics and artifacts dated to the 2rd century CE have been excavated is threaten by groundwater ingression. The in-situ building heritage materials and structures comprising a two cellea temple and an amphitheater made of limestones, are submitted all days to rising and changing groundwater levels; water being the main agent or vector of damage processes (salt weathering or freeze-thaw cycles). As part of a multi-disciplinary effort to support archeological expeditions and conserve the site structures. We report the results of groundwater monitoring and hydrogeological studies as well as tidal subsurface analysis executed to quantitatively evaluate hydraulic and geo-mechanical characteristics of the subsurface sequences toward a nondestructive approach. Continuous groundwater level data recorded in three wells in the archeological site were decomposed into constituent events that impact the observed fluctuations. The groundwater levels and barometric pressure data were acquired at 60 seconds intervals to study the response of the aquifer to strain and stress prevalence at the site. Using the method of regression deconvolution, the response to barometric pressure was disentangled from the measured water levels. Theoretical Earth tides parameters were computed using the PyGtide code, based on the ETERNA PREDICT program, at intervals of 1 minute. Harmonic analysis of the raw and filtered data using the classical Fast Fourier transform (FFT), and Singular Spectral Analysis (SSA) identify M2, S2, K1 and O1 tidal constituents as the dominant amplitudes. The SSA technique has the advantage of resolving the events into individual strands compare to the spectra of the composite data produced by the FFT. Hence, an event decomposed in the data is isolated in terms of it frequency and amplitude, and visualized. The K1 and S2 harmonic constituents were present in the filtered and raw data sets with different amplitudes. The amplitude response method was used to compute the poroelastic properties of the aquifer and characterize the subsurface heterogeneity. The model identified a semi-confined aquifer as the main groundwater storage system in the site.

Keyword: Heritage site, groundwater ingress, harmonic constituents, hydraulic properties

How to cite: Nkitnam, E. E., Maineult, A., and Wassermann, J.: Investigations of shallow aquifer groundwater systems of a Gallo-roman anthropized site using earth tide analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6252, https://doi.org/10.5194/egusphere-egu23-6252, 2023.

EGU23-8060 | Orals | ERE1.14

Comparison of different kinds of models to simulate the alteration of medieval stained glass as a function of climate and pollution 

Aurélie Verney-Carron, Loryelle Sessegolo, Roger-Alexandre Lefèvre, and Peter Brimblecombe

A large number of stained glass windows were installed from the 13th century. During the Middle-Ages, most of glass pieces have a Si-K-Ca composition with a relatively low SiO2 content, but high content of K2O and CaO.  This chemical composition means that medieval stained glass deteriorates during environmental exposure, from climate and environmental pollution. These alterations are manifested in the form of an alteration layer and secondary phases (mainly gypsum or syngenite). The alteration layer is generally depleted in K and Ca, but rich in Si, Al and Fe. Its thickness varies up to 300 µm after 6 or 7 centuries of alteration. In order to reconstruct the alteration history and predict the deterioration of stained glass windows in the future, it is necessary to determine alteration rates as a function of the climate and environmental parameters.

Several methodologies can be used to achieve this. First, short-term exposures or laboratory experiments can assess the first stages of the alteration and short-term kinetics. From these results, dose-response functions (DRF) were established for sheltered and unsheltered rain conditions. They correlate relevant environmental factors (temperature, rain quantity, rain pH, relative humidity, SO2 concentration) with the response of the materials in terms of alteration layer thickness. The second methodology consists in laboratory experiments that aim at parametrizing kinetic laws as a function of specific parameters (temperature, pH of rain, and relative humidity). These kinetic parameters do not directly consider pollution, but they can be extrapolated over long periods and can be inputs to geochemical models. In this study, we have compared both methodologies to simulate the alteration of a model stained glass at different European sites (using data from the ICP-Materials program). Both models give good results, but the geochemical model tends to underestimate the alteration at polluted sites. This indicates that the pollution via the concentration in SO2 for example should be included to improve the model.

How to cite: Verney-Carron, A., Sessegolo, L., Lefèvre, R.-A., and Brimblecombe, P.: Comparison of different kinds of models to simulate the alteration of medieval stained glass as a function of climate and pollution, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8060, https://doi.org/10.5194/egusphere-egu23-8060, 2023.

Moisture and salts cause considerable damage to built and rock-hewn heritage. Rock moisture is a key factor for numerous decay processes, but there is limited knowledge of salt and moisture distribution because measurements of spatial and temporal moisture distribution still remain challenging. The medieval cave town of Uplistsikhe (Georgia) is hewn out of very soft Lower Miocene sandstone and is a typical example of a heritage site suffering from progressive decay. We present data on moisture and salt distribution derived from a multi-method approach, including microwave sensor monitoring (MW-mon; continuously over 2 yrs), microwave handheld sensors (MW), 2D-resistivity profiles (ERT), rock sampling by drilling, and salt extraction by paper pulp poultices (PPP).

Microwave monitoring was applied for the first time (to our knowledge) in a long-term monitoring of heritage sites. We used equipment from hf-sensor (Germany) with two types of microwave reflectivity sensors penetrating approx. 7 cm and 13 cm deep, respectively. The sensors were installed inside and outside of two prominent caves (Grand Hall and Long Hall). MW, ERT, PPP and drilling were carried out in four caves (the two mentioned plus Blackberry Hall and Teatron). Careful laboratory calibration using samples from the site was necessary to produce quantitative results for MW-mon, MW and ERT.  

MW-mon showed pronounced annual fluctuation with highest moisture saturation occurring in summer. The moisture maximum in the caves lags 2 months behind the spring precipitation maximum and might be partly caused by air humidity condensation amplified by salts. Heavy rainfall events cause additional moisture pulses by seeping through the rock or by capillary rise. Spatial moisture distribution derived from MW shows relatively dry rock outside the caves and different patterns of moisture ingress into the caves: Capillary rise from the base, ingress through fractured or otherwise water-permeable areas of the roofs or back walls. The spatial patterns are confirmed by ERT; however, calculated moisture saturation differs between MW and ERT due to electrical conductivity effects of salty pore water.

All drill samples from the caves are significantly saltier on the respective surfaces, which points to the rate of evaporation being smaller than the outward migration of salts. Outside the caves, flaking of thicker layers (several cm) point to deeper layers of salt concentration caused by higher evaporation from the surface; flaking at the "lips" above the caves is probably also amplified by stronger temperature and moisture fluctuations. The main ions everywhere are  Ca2+ and SO42- (subordinate K+) while at the strongly flaking surfaces of Grand Hall, Na+, Cl- and NO32- are also present. Summing up, the results show very diverse and complex patterns of moisture and salt distribution at an apparently homogeneous site.

How to cite: Sass, O. and Fruhmann, S.: Spatiotemporal rock moisture distribution at the medieval cave town of Uplistsikhe, Georgia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8442, https://doi.org/10.5194/egusphere-egu23-8442, 2023.

EGU23-11011 | Posters on site | ERE1.14

Evaluation of salt weathering equations. – a review 

Chiaki Oguchi

Salt weathering of building stone is a major cause of loss of historic structures. Many geoheritage sites including stone heritage and geomorphosites have been damaged by this process. In nearly two centuries, research and observation relating salt weathering have accumulated. These studies could be organized focusing on theories, mechanisms, experimental methods, and research tools. This presentation introduce by reviewing many, though not enough, studies to summarize the research history of salt weathering, including the results of subsequent studies, especially focused on an important mechanism of salt weathering, crystallization pressure. Since the concept of crystallization was first proposed in the early 20th century, many equations have been proposed. However, in order to apply them correctly, it is important to consider the type of salt weathering and the surrounding environment, as well as the type and properties of salt and rock (rock properties), and to select and apply the proposed model according to the situation. Although salt weathering studies have been done in a wide variety of research fields, appropriate collaboration among disciplines will lead to meaningful conservation and will be used for practical problems in the future.

How to cite: Oguchi, C.: Evaluation of salt weathering equations. – a review, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11011, https://doi.org/10.5194/egusphere-egu23-11011, 2023.

EGU23-11840 | Posters virtual | ERE1.14

Smart IoT sensors as part of a holistic solution for improving resilience and sustainable reconstruction of historic areas 

Dr. Antonis Kalis, Nikos Mitro, and Dr. Angelos Amditis

Although Climate Change (CC) has already been reported to have a significant impact on historical areas hosting Cultural Heritage (CH) sites, it is still challenging to assess quantitatively and qualitatively the impact of various climatic and other parameters on the CH sites, since the specific climatic conditions at their vicinity, and the emanating effects on their structure, are difficult to grasp due to cost and regulatory barriers. In the framework of the HYPERION EU project, we address this problem by providing a holistic solution for improving resilience and sustainable reconstruction of historic areas, which integrates the use of smart IoT devices, called Smart Tags, designed to provide environmental measurements close to monuments, with a number of state-of-the-art of technologies, services and tools (e.g. advanced ML, IoT, satellite and terrestrial imaging, social networking, event, material decay and business continuity modelling), in order to develop a single decision support system which aspires to become the cornerstone for resilience and reconstruction planning for historic areas in the future.

How to cite: Kalis, Dr. A., Mitro, N., and Amditis, Dr. A.: Smart IoT sensors as part of a holistic solution for improving resilience and sustainable reconstruction of historic areas, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11840, https://doi.org/10.5194/egusphere-egu23-11840, 2023.

EGU23-11948 | ECS | Orals | ERE1.14

Selection of relevant black crusts samples as ancient air pollution archives 

Mathilde Ropiquet, Aurélie Verney-Carron, and Anne Chabas

Since the Industrial revolution and due to increasing anthropogenic emissions, the composition of the atmosphere has been modified, leading to climate change and pollution. The impacts of pollution were depicted through paintings and writing from the beginning of the 19th century, but pollution measurements are relatively recent. In order to obtain ancient air pollution data, proxies in urban area need to be found.

Black crusts formed on limestone and marble monuments in urban area seem to be a good candidate as local proxy. Mainly composed of gypsum (CaSO4.2H2O), they are a chemical alteration pattern resulting from the reaction of the dissolution of the calcite (CaCO3) of the stone and of sulfation by sulphur dioxide (SO2) from the atmosphere. Particulate matter accumulates in the newly formed gypsum layer in sheltered area from the rain, thus giving the black crust a passive sampler potential.

To use black crusts as past air pollution archives, samples were collected at Père Lachaise cemetery (Paris) on ancient, dated (1820-1887) and unrestored limestone or marble tombs. Different types of analyses were performed to study sample morphology (by Optical Microscope), particulate matter (by Scanning Electron Microscopy) and chemical composition (especially major elements and trace metals by ICP-AES, LA-ICP-MS). Results underline two important features to use black crusts as past air pollution archives. First, the low variability of chemical composition of black crusts from Père Lachaise cemetery highlights that the black crusts are representative of the site and register the background pollution. Then, the morphology (laminar vs. dendritic) of black crusts is a key parameter to sample black crusts as the stratigraphy is much better preserved in laminar black crusts.

How to cite: Ropiquet, M., Verney-Carron, A., and Chabas, A.: Selection of relevant black crusts samples as ancient air pollution archives, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11948, https://doi.org/10.5194/egusphere-egu23-11948, 2023.

EGU23-12449 | ECS | Orals | ERE1.14

The technical relationship between vertical greening and built heritage 

Marie De Groeve, Eda Kale, Scott Allan Orr, and Tim De Kock

Built heritage is rich in cultural and economic values and is an essential part of urban environments. These buildings are abundant in city centres that have been the site of development for several centuries. This has produced a dense environment, exhibiting strong urban heat island effects. Green initiatives are increasingly being implemented to mitigate current climate stressors and improve the health and well-being of residents. However, built heritage is often excluded from these approaches due to concerns about their impact on materials and structural integrity, which is poorly understood. 

This research scopes the technical compatibility of vertical greening with built heritage in an urban environment regarding the degradation of historic building materials. Vertical greening here is understood to include plants, rooted in the ground, growing along a vertical surface by either attaching themselves to the façade or trellising. Investigating the impact of vertical greening on the local microclimate by monitoring case studies, lab experiments and analysing current literature can help us understand how vertical greening affects common forms of degradation caused by salts, frost, bio-activity and air pollution. Each method has its own approach to understanding the relationship of vertical greening with built heritage and is complementary to the others. The lab experiments explore the three main factors impacted by vertical greening such as temperature and relative humidity, incoming solar irradiation and precipitation exposure. Temperature and relative humidity are inseparably connected with each other and therefore analysed together. The impact of vertical greening on the aforementioned environmental parameters is investigated separately to provide better insights into those microclimatic changes that determine the risk of weathering of historic building materials.

How to cite: De Groeve, M., Kale, E., Orr, S. A., and De Kock, T.: The technical relationship between vertical greening and built heritage, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12449, https://doi.org/10.5194/egusphere-egu23-12449, 2023.

EGU23-12934 | ECS | Posters on site | ERE1.14

Microclimatic monitoring of the plaster casts of the Trajan’s Column in the Museum of Roman Civilisation (Rome) 

Federica Bubola, Eleonora Balliana, Chiara Coletti, Claudia Cecamore, Claudio Parisi Presicce, and Claudio Mazzoli

In recent years, the control of the micro-climate in museum environments or in historical buildings has assumed a role of great importance for the protection of the artefacts exhibited and for planning cost-effective and strategic preservation policy. The process of degradation indeed, defined as a result of progressive and cumulative material decay, strongly depends by environmental variables and their changes. Rapid changes and/or strong gradients in temperature and/or relative humidity, are the main causes of internal stress and of material surface detachments. Compared to new museums, historical ones often do not dispose of ideal conservation parameters, and they need specific conservation environments, considering the so-called historical climate, i.e. the microclimate to which the Cultural Heritage has adapted over the time. This is the case of the Museum of Roman Civilisation (Rome), which has been closed since 2014 and hosts a huge and valuable collection of plaster casts, such as those of the Trajan’s Column made by Napoleon III in 1861-1862 and gifted from Vatican City to Rome City Hall in 1953. In view of the imminent museum reopening and restoration, it is essential to define the actual level of microclimate quality, compared to the expected one, considering also economic and regulatory aspects and the future welfare of the artefacts. The research is focused on the response of the materials to the micro-climate by evaluating the incidence of temperature and relative humidity, presumably the main chemical and physical degradation factors for the plaster casts. A multidisciplinary diagnostic approach (i.e. Hyperspectral Imaging, Raman Spectroscopy, Infrared Spectroscopy) is also planned to characterise the constituent materials, to suppose the manufacturing techniques of the casts and to identify the degradation forms. The analysis of the complex interaction between the dynamics of the climate and the need for the conservation of the artefacts under conditions of maximum stability represents the starting point for proposing a sustainable restoration of the Trajan’s Column plaster casts of the Museum of Roman Civilisation and a future exhibition project that will allow their valorisation and exposure.

How to cite: Bubola, F., Balliana, E., Coletti, C., Cecamore, C., Parisi Presicce, C., and Mazzoli, C.: Microclimatic monitoring of the plaster casts of the Trajan’s Column in the Museum of Roman Civilisation (Rome), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12934, https://doi.org/10.5194/egusphere-egu23-12934, 2023.

EGU23-13158 | Posters on site | ERE1.14

The use and vulnerability of medieval masonries in Balaton region, Hungary 

Ákos Török, Bendek Logó, and Annamária Kis

The geology of the region strongly influences the construction materials of Medieval structures and, consequently, the available raw materials. The current study focuses on the use and vulnerability of various lithotypes and renders in a Medieval Ruined Chuch in West Central Hungary, close to Lake Balaton. The church was constructed in the 13th century and was rebuilt in several periods using various lithotypes and renders. The identification of primary lithologies followed the generation of point clouds by Terrestrial Laser Scanner and the drawing of walls. More than ten various stone types were found, including Jurassic cherty limestone, cemented Triassic limestone (Muschelkalk), basalt tuff, basalt, red Permian sandstone, grey Tertiary sandstone, highly porous Miocene limestone, and travertine. The properties of stones and condition assessment were made by using non-destructive on-site strength tests such Schmidt hammer and Duroskop. Micro-drilling technique was also applied to assess the strength parameters of renders: medieval lime-based mortars, 20th-century portland cement based mortars. Small samples were also taken for laboratory analyses. Our studies suggest that the application of portland cement bearing renders in the 20th century caused significant damage to the structure, accelerating weathering processes. Medieval lime mortars are relatively durable and show smaller-scale alterations. The use of various lithotypes leads to differential weathering of the structure. The long-term preservation of this building depends on the use of appropriate renders and the refurbishment of wall sections that are structurally unstable.

How to cite: Török, Á., Logó, B., and Kis, A.: The use and vulnerability of medieval masonries in Balaton region, Hungary, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13158, https://doi.org/10.5194/egusphere-egu23-13158, 2023.

EGU23-13243 | Orals | ERE1.14

IT support for climate resilient cultural heritage - examples from the KERES project 

Jürgen Moßgraber, Tobias Hellmund, and Lola Kotova

Not only ecosystems are particularly sensitive to extreme weather as a result of climate change. Historical buildings, museum’s collections and historical gardens can also be affected by extreme weather conditions. Assessing the extent to which cultural assets are endangered by such weather and climate events is an interdisciplinary task that requires the collaboration of climate scientists together with cultural heritage managers, monument conservators, restorers and engineers. However, this discussion is currently hardly taking place in Germany, both on a scientific and on policy levels.

Therefore, the BMBF-funded project KERES addresses the following questions:

  • What safety risks of our cultural heritage are caused by extreme weather events?
  • Which practical solutions need to be addressed and managed the current and emerging impacts of climate change on cultural assets in Germany?

In close cooperation with the relevant stakeholders and potential users, such as the Prussian Palaces and Gardens Foundation (SPSG), Fraunhofer IOSB is building a web-based knowledge platform that combines the research results and best practices for adaptation and mitigation measures of the historical buildings and historical parks property. This aims to create the greatest possible degree of user orientation so that the knowledge platform can be used sustainably in the long term. This platform is able to collect and integrate multisource information in order to effectively provide complete and updated situational awareness and decision support for innovative measurements improving cultural heritage resilience, in particular new solutions for maintenance and conservation. It is based on the open source; easily configurable and extendable. It can be accessed by the wide range of users via the web interface.

Several levels of data integration, aggregation and linking are aggregated:

  • integration of expert knowledge,
  • connection of sensors for comprehensive monitoring

and reporting,

  • data analysis of complex processes with an open interface

for easy integration of new algorithms,

  • semantic and geographic linking of analysis data and
  • multiple domain information.

The backbone of this information network is an ontology, which connects the data of the different domains, like cultural heritage, climate change, environmental data, crisis management, regulations, sensor data management, buildings, materials and many more. The platform is flanked by two other applications, such as a planning tool for the evacuation of art objects:

  • This is a tool for creating route maps for the fire brigade to evacuate cultural objects.
  • The decision-maker supports finding individual measures against damage caused by climate change.

The applications for preventive and reactive measures to deal with potential or acute damage situations are examined as well. The designed methods are tested for five case studies including historical buildings and historical gardens in Germany.

How to cite: Moßgraber, J., Hellmund, T., and Kotova, L.: IT support for climate resilient cultural heritage - examples from the KERES project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13243, https://doi.org/10.5194/egusphere-egu23-13243, 2023.

EGU23-13666 | Orals | ERE1.14

Global warming evidence in long-term temperature monitoring of heritage karstic caves 

François Bourges, Bruno Lartiges, Frédéric Perrier, Dominique Genty, Rémi Losno, Stéphane Bonnet, Vincent Regard, Stéphanie Touron, Faisl Bousta, Frédéric Girault, and Pascal Foucher

The outstanding preservation of Paleolithic decorated caves is related to the buffering properties of their karstic environment. However, long-term monitoring of air/wall temperatures and gas compositions has recently revealed disruption signs in cave microclimates that had been maintained stable for hundreds of centuries.

High precision and continuous temperature data records are currently monitored in various prehistoric caves in the South of France. Such operations have been promoted since the late 1990s by the French government for risk assessment and conservation.

The most striking feature is the positive drift of underground temperatures (air and wall) which is now obvious in most sites except for Niaux Cave (> 300 m undersurface) and in the deepest parts of Mas-d’Azil and Chauvet Caves (> 50 m undersurface). In tourist caves (Pech-Merle, Mas-d’Azil, Gargas, Villars), the positive thermal trends could not be related to the energy increase brought by visitors which number is now stable, nor to the lighting systems whose energy demand was strongly reduced. In addition, the underground thermal drift nearly starts at the same time in many caves with uncertainties of +/- 1 year: 2012 for Chauvet with +0.4 °C/decade, 2011 for Pech Merle with +0.32 °C/decade, 2011 for Marsoulas Cave with +1.09 to +0.36 °C/decade from the entrance to the deep gallery, 2011 for Gargas with +0.69 °C, +0.54 °C and +0.36 °C for the deeper station. It is worth noting that a 0.3-0.4 °C thermal drift is consistent with that predicted from global warming in these regions.  The thermal drifts were already in progress when monitoring began in Villars Cave in 1996 (+0.17 °C to +0.39 °C/decade), in Mas-d’Azil in 2012 and in Bruniquel in 2015. Marsoulas (+1.09 °C/decade) and Mas-d’Azil (more than +1 °C/decade in 6 of the 16 stations) present a much higher drift rate compared with that of surface, which suggests a thermal amplification process.

As measurements are performed in heterothermal zones, the long-term thermal drifts are modulated by persisting smoothed and out-of-phase yearly variations. A notable exception is the case of Bruniquel main gallery where the temperature records show a quasi-linear increase. In that case, the decadal evolutions of temperature +0.31 °C, +0.175 °C, and +0.24 °C, are not related to the depth of monitoring stations (32 m, 55 m, and 38 m, respectively) nor to their distances from the entrance. In 2018, those drift rates induced a permanent inversion of thermal gradient in the main gallery. In Gargas, the drift rate is more pronounced in the outer parts of the karst body, thus inducing a continuous evolution of the thermal gradients within the galleries.

Such underground microclimate disruption of patrimonial caves is a warning signal of direct threat on the preservation of remains. Karst physical organization and its related underground environment are themselves legacies of past climates; the current functioning of transfer zones of karst aquifers which includes the caves, are directly dependent on the outside climate. A more comprehensive approach and modelling of possible tipping points are urgently needed for conservation issues.

How to cite: Bourges, F., Lartiges, B., Perrier, F., Genty, D., Losno, R., Bonnet, S., Regard, V., Touron, S., Bousta, F., Girault, F., and Foucher, P.: Global warming evidence in long-term temperature monitoring of heritage karstic caves, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13666, https://doi.org/10.5194/egusphere-egu23-13666, 2023.

EGU23-13699 | ECS | Posters on site | ERE1.14

Assessing weathering damage in Arenitic Rock using Non-Destructive Testing: the case study of the stone coats of arms of Palazzo Ricasoli in Florence 

Eugenio Segabinazzi, Teresa Salvatici, Irene Centauro, Sara Calandra, and Carlo Alberto Garzonio

Assessing weathering damage in Arenitic Rock using Non-Destructive Testing: the case study of the stone coats of arms of Palazzo Ricasoli in Florence 

The conservation of architectural heritage often involves studying the effects of weathering on stone materials exposed to polluted environments with characteristics unfavorable to their preservation. The decay phenomena that occur in urban environments can lead to destructive effects on stone material, resulting in the need for specific analysis to assess the mechanical properties of these artifacts. 

In this study, we analyzed three stone coats of arms that decorate the facade of Palazzo Ricasoli in Florence using non-destructive diagnostic techniques (NDTs) to assess their degree of weathering.  

Palazzo Ricasoli is a historic Renaissance palace, located in the center of Florence, that features three stone coats of arms on its façade that are currently in critical condition, showing signs of very advanced degradation. The stone of which they are composed is a type of local sandstone rock commonly used in Florentine historical architecture. 

To investigate the properties of the material we used in situ techniques, such Sonic test and 3D scanning. The results obtained with these techniques were then compared with those obtained from laboratory analysis of micro-samples using methods such as Fourier transform infrared spectroscopy (FTIR), X-ray Diffraction (XRD), X-ray Fluorescence (XRF), and optical microscopy.  

Using NTDs we were able to gather data and insights on the mechanical properties of weathered rock used in historical buildings, obtaining crucial information that can be used to develop appropriate and detailed conservation strategies to ensure the long-term stability of these materials in their environmental conditions.

How to cite: Segabinazzi, E., Salvatici, T., Centauro, I., Calandra, S., and Garzonio, C. A.: Assessing weathering damage in Arenitic Rock using Non-Destructive Testing: the case study of the stone coats of arms of Palazzo Ricasoli in Florence, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13699, https://doi.org/10.5194/egusphere-egu23-13699, 2023.

EGU23-14025 | Posters on site | ERE1.14

Climate change impact of salt weathering on vernacular and archaeological cultural heritage building materials in Europe and Latin America 

Beatriz Menendez, Julian Esteban Cantillo, and Benjamin Quesada

Salts are widely present in all porous building materials. Their chemical composition, degree of hydration and crystalline phase as well as their abundance and location in the building are highly variable. In addition, these parameters depend on the type of material, the location and environmental factors such as climate, air pollution or groundwater composition.  The crystallization of salts inside porous materials depends on the nature of the solutions present in the pores and the conditions under which it occurs. Environmental, climatic and pollution conditions have changed in the past and continue to change today.

In this work we will estimate the changes of the potential salt weathering in vernacular cultural heritage in Europe and archaeological sites in Latin America, in particular in the selected regions of the European project SCORE (Sustainable COnservation and REstoration of built cultural heritage 2021-2024). In order to determine how future climatic conditions may affect salt weathering in these sites, climatic conditions in different models, based on scientific literature, will be used. Salt weathering will be estimated for different salts: Na2SO4, NaCl, and mixture of salt.

For temperatures between 0 and 30 ° C, the solubility of sodium chloride is almost constant (around 26% by mass) while that of sodium sulfate is very variable (between 5% and 20% by mass). Changes in temperature will induce precipitation/dissolution more easily for sodium sulphate than for sodium chloride. Similar conclusions can be drawn for changes in relative humidity in the case of crystals. In the case of sodium sulphate, the crystalline phase changes between the anhydrous salt (thenardite) and the decahydrated salt (mirabilite) and the deliquescence will depend on both temperature and relative humidity. In the case of sodium chloride with a single degree of hydration at temperatures above 0°C, the deliquescence is almost independent of temperature, with a relative humidity of almost constant equilibrium around 75%. In general, salts that have only one state of hydration have a lower capacity of degradation than salts with several phases of hydration. Phase diagrams will be employed to quantify the weathering induced by thee salts.

In nature as well as in buildings, it is common to find associations of salts more than pure salts, which complicates the study of the dependence of salt crystallization on environmental conditions. The variety of salts that can be formed by crystallization of solutions containing several different anions and cations is extremely important. The behavior of mixed solutions is much more complicated than that of solutions containing a single species of cation and anion. For complex solutions, the crystallization pathways as a function of composition and environmental conditions cannot be directly deduced from that of the salts taken separately. Thermodynamic models can be very useful for modeling the sequence and conditions of salt crystallization in a solution. We used the ECOS-RUNSALT model to calculate the evolution of salt volume as a function of temperature and relative humidity conditions to estimate the weathering produced by complex solutions.

How to cite: Menendez, B., Esteban Cantillo, J., and Quesada, B.: Climate change impact of salt weathering on vernacular and archaeological cultural heritage building materials in Europe and Latin America, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14025, https://doi.org/10.5194/egusphere-egu23-14025, 2023.

EGU23-15431 | Posters virtual | ERE1.14

The Loggiato dei Cappuccini in Comacchio (Italy): assessment of degradation and state of conservation. 

Elena Marrocchino, Lorenzo Ferroni, Rino Manfrini, Maria Grazia Paletta, and Chiara Telloli

Cultural heritage is an irreplaceable component of a country's socio-cultural and economic capital, valuable for community cohesion and for the creation and enhancement of social capital, economic impact and environmental sustainability [1-4]. Unfortunately, the vulnerability of cultural heritage has increased over time and its exposure to a series of slow and sudden natural and man-made hazards threatens its existence.

Comacchio is a small municipality in the province of Ferrara (Emilia-Romagna region in north-eastern Italy), in the southern part of the present-day Po River estuary. It is an early medieval settlement, mainly known for the presence of several Etruscan settlements in its territory [5]. Comacchio is the result of continuous variations in sea level and the Po River, the extent of subsidence phenomena, and finally human activity over the last five thousand years.

The Loggiato dei Cappuccini has always been a symbol of the town of Comacchio for its simple and pleasant aesthetic characteristics, for the shelter it can offer from the weather and the summer sun, for its secluded position with respect to the town centre and for its connection with the sanctuary of the Virgin Mary in Aula Regia, which has always been venerated here [6,7].

This study aims to enhance the Capuchin Loggia through an analysis of the monument's state of conservation. The research started with a historical analysis of the maintenance and restoration work that the monument has undergone over time. Subsequently, macroscopic observation and bibliographic research also analyzed the current degradation morphologies and their causes. The proposed analysis campaign may be used by the Municipality of Comacchio to plan future rehabilitation and restoration works aimed at the conservation of the historical-cultural heritage.

References

  • Cultural Heritage Counts for Europe. Full Report of the EU Project “Cultural Heritage Counts for Europe: towards a Eu-ropean Index for Cultural Heritage”, 2015. https://www.europanostra.org/our-work/policy/cultural-heritage-count s-europe/
  • Culture 2030 Indicators: Thematic Indicators for Culture in the 2030 Agenda. United Nations Educational, Scientific and Cultural Organization, 2019. http://uis.unesco.org/sites/default/files/documents/publication_culture_202 0_indicators_en.pdf
  • Transforming our world: the 2030 agenda for sustainable development. Resolution A/RES/70/1, United Nations General Assembly, United Nations, 2015. https://sustainabledevelopment.un.org/post2015/transformingourworld/publication
  • Romão, X.; Bertolin, C. Risk protection for cultural heritage and historic centres: Current knowledge and further research needs. Int J Disaster Risk Reduc, 2022, 67, 102652,
  • Gelichi, S. L’Isola del Vescovo, Firenze, Edizioni all’insegna del Giglio s.a.s., 2009.
  • Alberti, A. Segnali di una ritrovata cultura della manutenzione urbana e architettonica a Comacchio, FE. Quaderni di soprintendenza : Qds, 2001, 5.
  • Zamboni, A. La fabbrica dei pesci dietro il loggiato dei Cappuccini e la sede amministrativa delle Valli Comunali di Comacchio. In: Anecdota, Quaderni della Biblioteca L.A. Muratori Comacchio, Ferrara, Gabriele Corbo Editore, 2001, 1/2, 1.

How to cite: Marrocchino, E., Ferroni, L., Manfrini, R., Paletta, M. G., and Telloli, C.: The Loggiato dei Cappuccini in Comacchio (Italy): assessment of degradation and state of conservation., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15431, https://doi.org/10.5194/egusphere-egu23-15431, 2023.

EGU23-16553 | ECS | Posters on site | ERE1.14

Porosity evolution of granitic rocks used for the bridge construction 

Vendula Natherová, Richard Přikryl, Daniela Řimnáčová, Martin Racek, and Jiřina Přikrylová

Granitic rocks are generally ranked to very low porosity (open porosity of fresh, non-weathered granite should be below 1 vol. %) and durable rocks. Favourable physical properties dictate their choice for monumental works and important infrastructural projects such as bridges.

Current study focuses on detailed analysis of porosity evolution in granitic rocks used for the construction of two road bridges (making part of cultural heritage of the Czech Republic) over the Vltava River in Prague (Bohemian capital) in the second half of 19th c. After 120-150 service, many of the stone ashlars of load-bearing parts exhibit quite extensive decay phenomena; however, mostly close to the exposed surfaces. In order to understand causes of decay, several tens of samples obtained from decayed surfaces and from original source quarries were studied by various methods, namely mercury intrusion porosimetry (MIP) and optical and scanning electron microscopy.

Based on the results, porosity of granites in the stone masonry significantly increased compared to that of source rocks: two principal types of granites show open porosity 0.53-0.82 vol. %, and 1.03-1.15 vol. % respectively. In the case of granitic samples from studied bridges, their open porosity ranged from 2.13 to 6.42 vol. %. Most of the pores rank to coarse pores and macropores (according to IUPAC terminology), content of mesopores is negligible.

Significant increase of porosity reflects dynamics of decay process in a specific microclimate in Vltava River valley and polluted atmosphere of the city. However, pre-quarrying history of granites is another important factor: the examined rock types belong to the oldest members of the Central Bohemian Plutonic Complex of Variscan age, and numerous discrete hydrothermal alteration phenomena present in the studied rocks can promote their susceptibility to decay as well.

How to cite: Natherová, V., Přikryl, R., Řimnáčová, D., Racek, M., and Přikrylová, J.: Porosity evolution of granitic rocks used for the bridge construction, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16553, https://doi.org/10.5194/egusphere-egu23-16553, 2023.

The PARADeS project uses participatory approaches to contribute towards enhancing Ghana’s national flood disaster risk reduction and management strategy. The project was initiated by practitioners from Ghana and the problem setting was developed during a definition phase of the project. When the project started, commitment and strong partnership and involvement of partners were already established - a prerequisite for collaborative and non-extractive research.

Multiple workshops and focus group discussions were ‘successfully’ conducted in collaboration with our local partners. Despite the sound basis of the project (e.g. shared goal(s), strong and committed partnership), we experienced challenges before, during and post fieldwork. In this contribution, we particularly reflect and focus on including and managing different types of participants. On the one hand, we engaged with representatives from different governmental institutions and non-governmental organizations with mostly academic background during the workshops. On the other hand, flood-affected urban and rural citizens with strongly differing educational backgrounds and socio-economic assets elaborated on their flood experiences during the focus group discussions. Here, three main themes and challenges arose:

  • Selection of participants: Identifying blind spots of researchers and local partners, e.g. the risk of missing out marginalized voices,
  • Expectations management: Coping with expectations of participants and communicating own room of action, and
  • Feedback processes: Preventing extractive research by feedbacking information relevant to the participants

During the session, these themes are discussed using the guiding principles for fieldwork with participants (see Rangecroft et al. 2020) by highlighting ethics, communication, power dynamics and positionality. For this, we share our experiences and lessons learned e.g. how we deal with the problem of getting a gender balanced participant list or how we manage unexpected structures of focus groups. Furthermore, we would like to share our uneasiness when, for example, a focus group discussion turned into a community talk or unrealistic though understandable expectations were raised. By sharing our successes and pitfalls, we would like to contribute to a broader discussion on how to improve fieldwork, prepare for surprise and, especially, to meet expectations of participants, partners and researchers without compromising each other’s needs and integrity. 

 

Rangecroft, S., M. Rohse, E. W. Banks, R. Day, G. Di Baldassarre, T. Frommen, Y. Hayashi, B. Höllermann, K. Lebek, E. Mondino, M. Rusca, M. Wens and A. F. Van Loon (2020). "Guiding principles for hydrologists conducting interdisciplinary research and fieldwork with participants." Hydrological Sciences Journal: 1-12.

How to cite: Höllermann, B. and Ntajal, J.: Managing participants, expectations and surprises during fieldwork – Experiences from collaborative flood risk management in Ghana, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-207, https://doi.org/10.5194/egusphere-egu23-207, 2023.

EGU23-851 | ECS | Orals | EOS4.1

Organisational preparedness for the physical risks of climate change in the UK 

Denyse S. Dookie, Declan Conway, and Suraje Dessai

Understanding local perceptions of preparedness, risk and response to climate change is important for effective adaptation-focused actions and policy design. While there have been national surveys of the public’s concern, organisational perspectives are less studied. This research presents findings of a national survey of UK-based organisations’ perceptions about adapting to a changing climate. The survey covers awareness among organisations of climate change, its physical risks and how organisations are taking action to prepare for perceived risks. Administered in spring 2021, our survey summarises the insights of 2,400 respondents in roles related to organisational planning. The majority of respondents (69%) were from the private sector, while others came from public health authorities, local authorities, public educational establishments, and third sector or charitable organisations. 58% of respondents identified the effects of climate change as a concern. While the survey results support a picture of UK organisations taking steps to prepare for similar extreme weather events in the future, action is strongly informed by dealing with the effects of extremes already experienced. There is a much lower proportion of organisations taking measures to deal with the physical risks of future climate change. In terms of future action, organisations perceived a strong role for leadership from government and collective responsibilities for adaptation, signalling a need to recognise this in efforts to promote adaptation. These findings, though UK-centric, provide insight to societal responses, options and pathways, especially at the organisational level for the less widely studied private sector, as noted in IPCC AR6 WGII Chapter 13: Europe. 

How to cite: Dookie, D. S., Conway, D., and Dessai, S.: Organisational preparedness for the physical risks of climate change in the UK, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-851, https://doi.org/10.5194/egusphere-egu23-851, 2023.

Professional experiences led geoscientists initially to put together epistemic-moral hybrids [1], e.g. The Cape Town Statement on Geoethics  [2]. Then, combining geosciences and political philosophies more comprehensively, geo-philosophical assessments of human practices as part of the Earth System emerged [3] [4]. These assessments describe the Human-Earth Nexus amalgamating insights into (i) the dynamics of the Earth System; (ii) socio-historical features of human societies; (iii) philosophical appraisals of socio-political choices.

Scholars of the history of science recently developed a theory of the evolution of knowledge [5] [6] [7]. Applied to societies experiencing anthropogenic global change, they discern the concept of an ergosphere to depict the essence of the Human-Earth Nexus. “With their rapidly evolving culture, humans have introduced an “ergosphere” (a sphere of work, as well as of technological and energetic transformations) as a new global component of the Earth system, in addition to the lithosphere, the hydrosphere, the atmosphere, and the biosphere, thus changing the overall dynamics of the system.“ [6, p. 7].

The historians’ theory of evolution of knowledge offers geoscientists notions (e.g. borderline problem, economy of knowledge, and external representation) for assessing human practices, e.g. (i) a ‘borderline problem’ defined as: “problems that belong to multiple distinct systems of knowledge. Borderline problems put these systems into contact… (and sometimes into direct conflict) with each other, potentially triggering their integration and reorganisation” [7, p427]; (ii) an ‘economy of knowledge’ defined as: “societal processes pertaining to the production, preservation, accumulation, circulation, and appropriation of knowledge mediated by its external representation” [7, p.429]; (iii) an ‘external representation’ defined as: “any aspect of the material culture or environment of a society that may serve as an encoding of knowledge” [7, p. 224].

Concluding: (i) taking a geo-philosophical perspective means, per se, specifying a borderline problem, an economy of knowledge, and an external representation; (ii) the theoretical findings of the history of science offer a standardised methodology for geo-philosophical studies, namely asking: What borderline problem? What economy of knowledge? What external representation? Responses will discern sharper the socio-historical features of geo-philosophical topics, be it geoheritage or the Human-Earth-Nexus.

[1] Potthast T (2015) Toward an Inclusive Geoethics—Commonalities of Ethics in Technology, Science, Business, and Environment. In: Peppoloni MW (ed) Geoethics. Elsevier, pp 49–56

[2] Di Capua G, Peppoloni S, Bobrowsky P (2017) The Cape Town Statement on Geoethics. Ann Geophys 60:1–6. https://doi.org/10.4401/ag-7553

[3] Di Capua G, Bobrowsky PT, Kieffer SW, Palinkas C (2021) Introduction: geoethics goes beyond the geoscience profession. Geol Soc London, Spec Publ SP508-2020–191. https://doi.org/10.1144/SP508-2020-191

[4] Bohle M, Marone E (2022) Phronesis at the Human-Earth Nexus: Managed Retreat. Front Polit Sci 4:1–13. https://doi.org/10.3389/fpos.2022.819930

[5] Rosol C, Nelson S, Renn J (2017) Introduction: In the machine room of the Anthropocene. Anthr Rev 4:2–8. https://doi.org/10.1177/2053019617701165

[6] Renn J (2018) The Evolution of Knowledge: Rethinking Science in the Anthropocene. HoST - J Hist Sci Technol 12:1–22. https://doi.org/10.2478/host-2018-0001

[7] Renn J (2020) The Evolution of Knowledge - Rethinking Science for the Anthropocene. Princeton University Press, Oxford, UK

How to cite: Bohle, M.: Takings from the History of Science for Geo-philosophical Studies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1204, https://doi.org/10.5194/egusphere-egu23-1204, 2023.

EGU23-1385 | Posters on site | EOS4.1 | Highlight

An expanded definition of geoethics 

Giuseppe Di Capua and Silvia Peppoloni

Geoethics incorporates instances, categories, concepts, principles, and values already present in the cultural debate, and develops an original theoretical and interdisciplinary framework that merges reflections and considerations that animate philosophical, political, sociological, economic, and (geo)scientific discussions. Geoethics analyses critically and rationally theoretical and practical issues of local and global importance (from climate change, to defense against geohazards and the use of geo-resources), in order to guide social stakeholders towards more inclusive, sustainable, and ecologically-oriented choices.

Geoethics can be qualified as:

  • universal and pluralist (it defines an ethical framework for humanity, in the awareness that the respect of the plurality of visions, approaches, tools is essential to assure dignity to all agents and to guarantee a wide range of opportunities for developing more effective actions to face common threats).
  • wide (its issues and reflections cover an extensive variety of themes);
  • multidisciplinary (its approach favors cooperation and overcoming the sectoral languages of the individual disciplines, to reach the intersection and integration of knowledge);
  • synthetic (it expresses a position of synthesis, definable as ecological humanism, between various existential concepts and different conceptions regarding the nexus between human being and Earth system);
  • local and global (its topics of interest concern both local and regional dimensions, as well as the global one related to the entire Earth system);
  • pedagogical (it proposes a reference model to cultivate one's ethical dimension, to reach a greater awareness of the value of human identity, not in terms of exercisable power over the other by oneself, but of respect of the dignity of what exists);
  • political (it criticizes the materialism, egoism, and consumerism of capitalism, prefiguring a profound cultural change of economic paradigms, and supports the right to knowledge as the foundation of society).

By contributing to change the perception of the nexus between the human being and the Earth system and consequently the social and legal structures of the organization of human communities, geoethics defines educational and political horizons for reaching a global reform of society (Peppoloni and Di Capua 2021: https://doi.org/10.3390/su131810024).

Based on these considerations, the definition of geoethics, as included in the Cape Town Statement on Geoethics (Di Capua et al. 2017: https://doi.org/10.4401/ag-7553) and internationally adopted, can find a new, broader formulation, which also describes better its theoretical structure and operational logic:

Geoethics is a field of theoretical and applied ethics focused on studies related to human-Earth system nexus. Geoethics is the research and reflection on principles and values which underpin appropriate behaviors and practices, wherever human activities interact with the Earth system. Geoethics deals with ways of creating a global ethics framework for guiding individual and social human behaviors, while considering human relational domains, plurality of human needs and visions, planetary boundaries, and geo-ecological tipping points. Geoethics deals with the ethical, social, and cultural implications of geoscience knowledge, education, research, practice, and communication and with the social role and responsibilities of geoscientists.

How to cite: Di Capua, G. and Peppoloni, S.: An expanded definition of geoethics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1385, https://doi.org/10.5194/egusphere-egu23-1385, 2023.

EGU23-1391 | Posters on site | EOS4.1

Proposal of ethical guidelines for the European Research Infrastructure EPOS 

Silvia Peppoloni and Giuseppe Di Capua

In the science and technology domain, common methods, procedures, and protocols (rules allowing to make science) guarantee the quality and reliability of scientists’ and technicians’ work. When those rules are adequately followed, there should not arise any problems in deciding what is the best action to take while carrying out research and technological activities. But this is not enough to ensure that activities are conducted ethically.

Ethics influences personal and collective conduct and thereby shapes relationships and resulting outcomes. Research institutions/networks/organizations and their operators have societal responsibilities since their activities may have an impact on stakeholders, partners, and general end users with consequential effects on the economy, society, culture, public policy or services, health, the environment, or quality of life that goes way beyond a purely academic impact. Science, technology, and ethics are closely interconnected and they mutually influence the subject of their analyses and reflections. Thus, research and technological activities have to consider ethics to develop their full potential.

The mission of EPOS is “To establish and underpin a sustainable and long-term access to solid Earth science data and services integrating diverse European Research Infrastructures under a common federated framework.” This mission encapsulates ethical aspects that must be considered by the EPOS community (scientists, technicians, and data providers, who have different roles and therewith responsibilities within the EPOS community) and that are reflected in EPOS’ goals (https://www.epos-eu.org/about-epos).

In the EU H2020 EPOS-SP project, we developed first draft of the ethical guidelines for the EPOS community, that considers the following EPOS key-concepts:

  • multidisciplinary research;
  • integrated use of data, models, and facilities;
  • appropriate legal solutions;
  • common and shared data policy;
  • open access policy;
  • transparent use of data;
  • mutual respect of intellectual property rights.

The ethical guidelines are essential for establishing an informal “contract” between all members of the EPOS community for managing the relationships within the research infrastructure and with partners by defining principles and values to be shared for building a community of purposes, that is a set of individual and institutional subjects who share an organization, a language, a mission, goals to be achieved, a working method and operational tools.

These guidelines shall ensure that the research conducted within EPOS and services operated in this context are done in an ethical way.

The ethical guidelines are an orienting document for the implementation of the EPOS ERIC’s (European Research Infrastructure Consortium) tasks towards its reference community and stakeholders and are preparatory to the drafting of the final version of the EPOS ERIC ethical guidelines on which to develop subsequent ethical codes for managing specific activities or issues concerning EPOS activities.

How to cite: Peppoloni, S. and Di Capua, G.: Proposal of ethical guidelines for the European Research Infrastructure EPOS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1391, https://doi.org/10.5194/egusphere-egu23-1391, 2023.

EGU23-2805 | Posters on site | EOS4.1

Study on the effective disaster risk management and communication for resilient community 

Mo-Hsiung Chuang, Kuo-Chen Ma, and Yih-Chi Tan

This 27th United Nations Climate Change Conference clearly pointed out that global warming is progressing. The threat of climate change and extreme disasters will increase rapidly, and the risk of community disasters will increase significantly. Therefore, effective disaster risk management and risk communication can enable community residents in disaster potential areas to understand disaster risks and build disaster prevention organizations, which has become a Practitioner in Disaster Risk Management. This study aims to explore training methods for resilient Communities. These include community environment diagnosis map making, including natural disaster risk and vulnerability discussion and disaster prevention map drawing, and secondly, how to train resilient community to conduct disaster risk control and disaster management measures before or during disaster events and recovery periods. Finally, combine the geographic information of the public sector and volunteers to conduct public-private cooperation to build disaster risk management and practice with resilient communities as the key players.

How to cite: Chuang, M.-H., Ma, K.-C., and Tan, Y.-C.: Study on the effective disaster risk management and communication for resilient community, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2805, https://doi.org/10.5194/egusphere-egu23-2805, 2023.

EGU23-3462 | Posters on site | EOS4.1 | Highlight

How to collectively engage in reducing the carbon footprint of a research lab? 

Jean-Philippe Vidal, Céline Berni, Marina Coquery, Alexandre Devers, Leslie Gauthier, Claire Lauvernet, Matthieu Masson, Louise Mimeau, and Martin Turlan and the RiverLy Downstream team

This communication aims at testifying how individual commitments of researchers can be combined to engage a whole research lab – in this case INRAE RiverLy – in a carbon transition path. INRAE RiverLy is an interdsciplinary research unit for the management and restoration of river systems and their catchments. In 2020, a group of RiverLy people started questioning the downstream impacts of their research practices. An official internal action called RiverLy Downstream was thus launched to address these issues. A first lab-scale carbon accounting for the year 2019 was performed thanks to the GES 1point5 tool (https://apps.labos1point5.org/ges-1point5). It showed a large contribution of air travel to the total carbon footprint. Further carbon accounting for 2020 and 2021 however highlighted the even larger impact of purchases (equipment, consumables, etc.) thanks to newly implemented features in GES 1point5. An open “climate day” was organized in the lab in September 2022 for (1) raising awareness through a general-public-oriented tool, (2) provide live feedback from other research labs engaged in a carbon transition, and (3) collectively identify propositions of local actions on different themes: purchases, travels, premises, computing, food, and research activities. These propositions fed a lab-wide survey that will help defining a few carbon footprint reduction scenarios based on their social acceptability. These scenarios will then be submitted to the lab board for implementation. The whole process benefited from rich interactions with INRAE national to regional strategy for reducing its environmental footprint (https://www.inrae.fr/en/corporate-social-responsibility-inrae), and with the French national initiative Labos1point5 (https://labos1point5.org/).

How to cite: Vidal, J.-P., Berni, C., Coquery, M., Devers, A., Gauthier, L., Lauvernet, C., Masson, M., Mimeau, L., and Turlan, M. and the RiverLy Downstream team: How to collectively engage in reducing the carbon footprint of a research lab?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3462, https://doi.org/10.5194/egusphere-egu23-3462, 2023.

EGU23-4066 | Posters on site | EOS4.1

Supradisciplinary approach: a (geo)ethical way of producing knowledge and guiding human actions in the XXI Century. 

Eduardo Marone, Martin Bohle, and Rika Prieser

Once upon a time, super-specialization and intra-disciplinary approaches were highly rated, although implying divisions of knowledge1. How to challenge such epistemic boundaries? The disciplinary methodology for creating knowledge is important, particularly when subject to solid quality control. However, it is often faulty when handling broad complex systems, such as Natural or Social ones, despite scholars building elaborated methodologies, such as multi-, inter, trans-, and cross-disciplinary practices2. They provided insights and knowledge generation, although showing limitations3,4,5 (epistemic, field domination, egos, etc.).

Geoethics, looking into appropriate behaviours and practices wherever human activities interact with the Earth system6, is an example of the above, which requires overcoming limitations of disciplinary approaches by aiming at supradisciplinary7: engaging with a subject matter across a range of discourses/fields without giving rise to an interdisciplinary hybrid or sui generis discipline.

Exploring what a supradisciplinary practice means, a networkn of scholars proposes a tactic to assemble fellows from the People Sciences and the Natural Sciences: (i) A respectful epistemic trespassing8 allows crossing traditional disciplinary boundaries, and applying proper supradisciplinary collaboration seems more ethical than other methodologies. (ii) Organizing the team under a rhizomatic structure9 does not allow any scientific field hierarchy, avoiding the dilemma of preferring transdisciplinary approaches versus interdisciplinary or multidisciplinary ones and vice versa. Epistemic trespassing is a powerful tool for creating new supradisciplinary knowledge, avoiding the usual hyper-protection (and egos) related to any disciplinary epistemic backyards. It must be considered that supradisciplinary collaboration depends strongly on the quality of the given scientific problem and the proper promotion of the needed epistemic metamorphosis, which seems a more ethical and efficient way of producing knowledge.

 

1 Klein, J. T., & Miller, R. C. (1983). The Dialectic and Rhetoric of Disciplinary and Interdisciplinary. Issues in Interdisciplinary Studies.

2 Van den Besselaar, P., & Heimeriks, G. (2001). Disciplinary, multidisciplinary, interdisciplinary: Concepts and indicators. In ISSI (pp. 705-716).

3 Okamura, K. Interdisciplinarity revisited: evidence for research impact and dynamism. Palgrave Commun 5, 141 (2019). https://doi.org/10.1057/s41599-019-0352-4

4 Editorial. How to avoid glib interdisciplinarity. Nature 552, 148 (2017). DOI: https://doi.org/10.1038/d41586-017-08465-1

5 Kotter, R., Balsiger, P. W., Bailis, S., & Wentworth, J. (1999). Interdisciplinarity and transdisciplinarity: a constant challenge to the sciences. Issues in Interdisciplinary Studies.

6 Peppoloni, S., Bilham, N., & Di Capua, G. (2019) Contemporary Geoethics Within the Geosciences. In: Exploring Geoethics. Springer International Publishing, Cham, pp 25–70

7 Balsiger, P. W. (2004). Supradisciplinary research practices: history, objectives and rationale. Futures, 36(4), 407-421.

8 Ballantyne, N. (2019). Epistemic trespassing. Mind, 128(510).

9 Deleuze, G., & Guattari, F. (1987) [1980]. A Thousand Plateaus. Translated by Massumi, Brian. University of Minnesota Press. p. 21. ISBN 0-8166-1402-4.

n The Network: Alexandra Aragão, Alessia Rochira, Anamaria Richardson, Antony Milligan, Bruno Costelini, Carlos A.S. Batista, Carlos Murillo, Carsten Herrmann-Pillath, Claire A. Nelson, Cornelia E. Nauen, Eduardo Marone, Francesc Bellaubi, Jas Chambers, Javier Valladares, Luis Marone, Martin Bohle, Nic Bilham, Paul Hubley, Rika Preiser, Sharon Stein, Silvia Peppoloni, Vincent Blok, Will Steffen.

How to cite: Marone, E., Bohle, M., and Prieser, R.: Supradisciplinary approach: a (geo)ethical way of producing knowledge and guiding human actions in the XXI Century., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4066, https://doi.org/10.5194/egusphere-egu23-4066, 2023.

EGU23-4384 | ECS | Posters on site | EOS4.1

Social safety in the field – preparing the students, our future colleagues 

Kalijn Peters, Steye Verhoeve, and Wiebe Nijland

Watching the documentary ‘The Leadership’ led to a consentient discussion amongst colleagues. In this documentary a group of female scientists set off on a cruise to learn about and experience leadership. Personal experiences, what happens on board and statistics about social safety, show that feeling socially safe and included is still an issue amongst (female) scientists, especially when working in the field. The significantly high numbers of female field scientists in STEM research having experienced discrimination, gender inequality and (sexual) harassment cannot be ignored, so we decided this subject has to be embedded in our bachelor curriculum.

In order to enhance social safety in our earth sciences program, we set up a workshop on this subject for our bachelor students as part of a 15ECTS fieldwork course. In the field, students are physically and mentally challenged, while operating in an often unfamiliar environment, working in bigger and smaller groups, for longer periods of time and integrating all they have learned over the past year(s). With the many challenges this encompasses, they will likely face the boundaries of their comfort zone. This makes them more vulnerable and increases the risk of creating an unsafe working, studying/living environment. However, when treated with care, these experiences can have a significant positive impact on the students personal growth and become beneficial to their professional skills and learning.

The workshop we designed starts with discussing daily practicalities and individual responsibilities, including sanitary hygiene and proper field-equipment, and continues with professional attitude, an exercise on group dynamics, how to function in a team that is not your own choice, and getting to know your teammates in a playful manner. We finish with the discussion of (sexual) harassment, providing tools to become an active bystander, and giving the students case studies of socially (un)safe settings in the field. They present these case studies to each other on how they would react, reflecting on their own capabilities and responsibilities.

After this first year, student evaluations and discussions with field staff point out that this is a valuable part of the fieldwork. For example the staff could more easily refer to some manners discussed in the workshop, and the students could recognize the case studies and use this to tackle unsafe situations at an earlier stage. We now continue with optimizing the existing workshop, and would like to exchange experiences about this subject with colleagues to enhance improvement of social safety and personal growth in the field for both students and teaching staff.

How to cite: Peters, K., Verhoeve, S., and Nijland, W.: Social safety in the field – preparing the students, our future colleagues, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4384, https://doi.org/10.5194/egusphere-egu23-4384, 2023.

The unprecedented acceleration of human extractions of living and mineral resources particularly after WWII and their wasteful transformation in an expanding technosphere is now estimated to exceed living matter[1]. This fossil fuel driven acceleration has led to exceeding planetary boundaries in several dimensions [2], including the on-going mass extinction of species particularly in the warming and overfished ocean. Catch reconstructions since the beginnings of global statistics in 1950 are revealing the extent of unsustainable extractions from the ocean[3]. Two decisions at global negotiations in 2022, one on harmful fishing subsidies and the landmark target 3 on the protection of 30% of ocean and land by 2030, have potential to slow down the excesses and gradually rebuild fully functional ecosystems. How can scientists enhance their contribution towards shifting the emphasis to implementation? We know from cognitive science, e.g. that excessive car speed and other forms of sensory overload stress humans and reduce quality of life while also harming the environment[4]. Yet even in the face of evidence, it has often been impossible to act decisively on this evidence. Similarly, it has so far been been difficult to overcome widespread cognitive dissonance about climate change and species extinctions in the ocean. Contrary to widely held beliefs, here it is postulated that different attitudes are not impervious to scientific information and learning. Historically these judgemental processes are not fixed, even when reinforced by social norms[5]. However, the accumulation of facts and their presentation in the scientific literature is not enough to bring about what may be considered desirable behavioural change. This is reflected in considerable effort put into policy briefs and other dissemination formats in recent years, including video and social media e.g. by the IPCC. Art of hosting and collective leadership are other proven approaches for building understanding and trust necessary to develop robust solutions through enabling collective action. In their various context-adapted formats they have been successfully deployed for joint learning and action in settings as diverse as largely illiterate small-scale fishing communities and government organisations. They could benefit research and academic institutions in their search for promoting more stakeholder engagement and fostering greater inter- and transdisciplinarity.

[1] Elhacham, E., Ben-Uri, L., Grozovski, J. et al. Global human-made mass exceeds all living biomass. Nature 588, 442–444 (2020). https://doi.org/10.1038/s41586-020-3010-5

[2] Steffen, E., Richardson, K., Rockstroem, J. et al. Planetary boundaries: Guiding human development on a changing planet. Science 347(6223) (2015). DOI: 10.1126/science.1259855

[3] Pauly, D. & Zeller, D. Catch reconstructions reveal that global marine fisheries catches are higher than reported and declining. Nature Commun. 7, 10244 (2016). doi: 10.1038/ncomms10244

[4] Knoflacher, H. Zurück zur Mobilität! Anstöße zum Umdenken. Ueberreuter, Wien (2013)

[5] Sparkman, G., Howe, L., Walton, G. How social norms are often a barrier to addressing climate change but can be part of the solution. Behavioural Public Policy 5(4), 528-555 (2021). DOI: https://doi.org/10.1017/bpp.2020.42

How to cite: Nauen, C. E.: Art of hosting approaches with greater participation of scientists can support robust solutions for increased societal resilience, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4421, https://doi.org/10.5194/egusphere-egu23-4421, 2023.

EGU23-4443 | Posters on site | EOS4.1

Minerals as lenses to illustrate the relationships between Geology and colonialism 

Selby Hearth and Carrie Robbins

When the core ideas of Geology were being developed in the 19th century, geologists used colonial expeditions for transport, access, data, and -- critically -- specimens. Mineral specimens were sent from colonized and mined localities around the world to centralized collections in Europe and European settler states, forming diverse repositories of minerals, rocks, and fossils that geologists could then draw on without having to leave their home country. The accumulation of these specimens contemporaneously spurred the growth of museums and formed the collections at the heart of object-based pedagogy. As curators of these collections today, how can we use these specimens and their histories to illustrate these connections? This presentation will examine how the Bryn Mawr Mineral Collection is using mineral specimens in cataloging, display, and teaching to provoke reflection on this critical social dimension of our science. One of these strategies has been to recruit student research into mine sites and the provenance and provenience of individual specimens. Activating historical collections in this way helps make them relevant to today’s students. It also helps students recognize that geo-colonialism is not restricted to the past. Lithium, cobalt, and other rare minerals will be central to the production of batteries and anti-carbon technologies for the new “green economy” in the coming decades. It is important that mineral collections begin to use specimens to teach broader social histories of mining, extraction, and Western colonial relationships so that differential distributions of power are taken into account.

How to cite: Hearth, S. and Robbins, C.: Minerals as lenses to illustrate the relationships between Geology and colonialism, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4443, https://doi.org/10.5194/egusphere-egu23-4443, 2023.

Scientists remain citizens and human beings. As so, they keep their critical mind and have visions for society and opinions on related crucial issues. The climate and ecological crisis makes no exception and has become the subject of more and more discussions among scientific communities. The bond between scientific research and societal issues can be seen in the common practice of national funding agencies asking scientists to explicitly define the societal values of their research activities (the so-called “knowledge utilization”). On such occasions, scientists need to prove that their findings will bring parts of technical, scientific, social, or even political solutions to a range of stakeholders, including decision-makers. Such a peculiar position raises many issues. In democracies, scientists and other experts are usually asked to remain neutral and only provide scientific and technical knowledge to support decision-makers (i.e., governments) who will make the decision.

The question of neutrality has particularly animated scientific communities for decades. May we, as scientists, activate only the rational part of our brains when doing science and activate the emotional one when we return to our daily personal and civic life? Should we remain neutral at all costs? When "business as usual" means making the ecological and social crisis more profound, does the concept of neutrality even exist? Is that ethical if doing nothing means supporting "business as usual"? Or should we admit that this is neither doable nor desirable?

In this paper, we suggest that being neutral and inactive is neither doable nor desirable for the sake of science and society. First of all, scientists are people, and their actions cannot remain completely value-free or independent from societal influences. Instead, the notions of objectivity, scientific rigor, and transparency, which all make part of scientific integrity, may be much more relevant to define good research practices. As long as these practices are followed, many ways of communicating with peers, stakeholders, and the public sphere may be considered, from appeased recommendations to stakeholders all the way down to (illegal) civil disobedience, as those may only differ by their degree of engagement in reporting the same facts. To which the ethics of responsibility should be added: we must say what we know (Resnik and Elliot, 2016).

We collected several testimonies from scientists from the earth and climate sciences engaged in activism and civil disobedience. The description of the several types of intellectual trajectories will help us understand how scientists connect their values to science and how, at their scale, their vision helps them disseminate science to improve societies and reduce their impacts on global changes.

Resnik, D. B. and Elliott, K. C.: The Ethical Challenges of Socially Responsible Science, Accountability in Research, 23, 31–46, https://doi.org/10.1080/08989621.2014.1002608, 2016.

How to cite: Lassabatere, L., Kuppel, S., and Vitón, Í.: Engaged scientists and the question of neutrality and integrity: illustrative intellectual trajectories of geoscientists, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5456, https://doi.org/10.5194/egusphere-egu23-5456, 2023.

EGU23-5570 | ECS | Orals | EOS4.1

Decarbonising conference travel: testing a multi-hub approach 

Sabrina Zechlau, Stefanie Kremser, Andrew Charlton-Perez, Jadwiga Richter, Jose Santos, Julia Danzer, and Stefanie Hölbling

As the global research enterprise grapples with the challenge of a low carbon future, a key challenge is the future of international conferences. An emerging initiative which combines elements of the traditional in-person and virtual conference is a multi-hub approach. Here we report on one of the first real-world trials of a multi-hub approach, the World Climate Research Programme/Stratosphere-troposphere Processes And their Role in Climate (WCRP/SPARC) General Assembly held in Qingdao-Reading-Boulder during the last week of October 2022. Based on travel surveys of participants, we estimate that the multi-hub approach reduced the carbon footprint from travel of between a factor of 2.3 and 4.1 times the footprint when hosting the conference in a single location. This resulted in a saving of at least 288 tCO2eq and perhaps as much as 683 tCO2eq, compared to having the conference in one location only. Feedback from participants, collected immediately after the conference, showed that the majority (85%) would again attend another conference in a similar format. There are many ways that the format of the SPARC General Assembly could have been improved, but this proof-of-concept provides an inspiration to other groups to give the multi-hub format a try.

How to cite: Zechlau, S., Kremser, S., Charlton-Perez, A., Richter, J., Santos, J., Danzer, J., and Hölbling, S.: Decarbonising conference travel: testing a multi-hub approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5570, https://doi.org/10.5194/egusphere-egu23-5570, 2023.

Paul Crutzen’s concept of the Anthropocene in Nature in 2002 stressed that “a daunting task [lay] ahead for scientists and engineers to guide society towards environmentally sustainable management” and that “this will require appropriate human behaviour at all scales”. The proposal by the Anthropocene Working Group of the International Commission on Stratigraphy’s Subcommission on Quaternary Stratigraphy for an ‘Anthropocene Epoch’ with an isochronous mid-20th century start has been recently challenged by another group of researchers. Mindful of the diachronous impacts of human evolution, they favor a much longer and still ongoing ‘Anthropocene Event’.

In sync with IUGS goals to promote public understanding of the Earth and contribute to international policy decisions, the Anthropocene debate offers an unprecedented opportunity for the geoscience profession to become proactively relevant to the UN’s next-step vision for Planet Earth. Arguably, its 2015-2030 agenda of 17 Sustainable Development Goals each focused on a facet of society and the environment needs a more holistic successor with realistic thinking about sustainability, “one of the most overused and ill-defined words in conversations about the environment” in the view of Andrew Revkin at Columbia University’s Earth Institute. Ideally, the UN’s successor plan would be aligned with the interdependent subsystems of the Earth-Human System and propelled by transdisciplinary involvement of the sciences and humanities.

Echoing an observation by Stanley Finney and Lucy Edwards in GSA Today in 2016 that the terms Anthropocene and Renaissance have similar characteristics as “richly documented, revolutionary human activities”, an ‘Anthropocene Renaissance’ would highlight the need for greater harmony among and between environmental and societal movements. In this vision, the past-framed ‘Anthropocene Event’ underpins the future-framed ‘Anthropocene Renaissance’ as a boldly integrated effort to ‘protect our planet’, one of twelve commitments made by world leaders in 2020 at the UN’s 75th Anniversary Meeting. In a profile of the Anthropocene debate in The New York Times on 18 December 2022, the conclusion featured my interview: “I always saw it not as an internal geological undertaking but rather one that could be greatly beneficial to the world at large”. The UN’s ‘Summit of the Future: Multilateral Solutions for a Better Tomorrow’ will take place in New York City on 22-23 September 2024.

 

 

 

 

How to cite: Koster, E.: Defining the Anthropocene for the greatest good as an Event-based Renaissance, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6182, https://doi.org/10.5194/egusphere-egu23-6182, 2023.

EGU23-6356 | Posters on site | EOS4.1

Ma Terre en 180 Minutes: a transition support system to build decarbonization scenarios in the academic community. 

Nicolas Champollion and the Ma Terre en 180 Minutes team

A growing portion of scientists realized the need to not only alert about climate change, but also change their professional practices. A range of tools have emerged to promote more sustainable activities, yet many scientists struggle to go beyond simple awareness-raising to create concrete transition actions. This study proposed the use of a new game-based transition support system called " Ma Terre en 180 Minutes ", which is, to our knowledge, the first tool developed by and for the academic community. It has been designed to build scenarios of greenhouse gases (GHG) emissions reduction in the academic community, and present its deployment during the year 2021, including six hundred participants from 9 countries and 50 cities.

 

After the phase 1, called awareness, that aims to build a common scientific background about the context (global warming, its causes and consequences, planetary boundaries) and challenge (50% reduction of our carbon budget by 2030), the participants, with the phase 2 called role-playing, immerse themselves into fictional characters, to simulate the behavior of real research groups. Phase 1 and 2 are separated by a few days interphase helping participants to embody their fictional characters and be comfortable with the virtual research group they will simulate, as well as having time to perform their personal carbon footprint. Finally, an important final phase after the game-playing phase 2 take place to discuss, analyze and assess the results of phase 2.

 

Results show clear pathways for GHG reductions between 25 and 60%, and a median reduction of 46%. The alternatives allowing the greatest reduction are video communication tools (36%), followed by mutualization of professional activities and voluntary cancellation or reduction, thatrepresents 22 and 14% of reduction, respectively. The remaining 28% of reduction is composed by the use of trains as a transport alternative, the relocation of professional activities, the duration extension of some missions, etc… In addition, the analyses pointed out the importance of guided negotiations to bring out some alternatives such as relocation, local partners and computing optimization. An added value of this transition support system is that the information it collects (anonymously) will be used to answer pressing research questions in climate change science and environmental psychology regarding the use of serious games for promoting changes in attitudes and behaviors towards sustainability, and including broader questions on how network structures influence “climate behavior”, knowledge, and the governance of the commons.

How to cite: Champollion, N. and the Ma Terre en 180 Minutes team: Ma Terre en 180 Minutes: a transition support system to build decarbonization scenarios in the academic community., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6356, https://doi.org/10.5194/egusphere-egu23-6356, 2023.

EGU23-7063 | Posters virtual | EOS4.1

The evolving Code of Conduct at the National Institute of Geophysics and Volcanology of Italy: a participatory process to combine law compliance and geoethics principles 

Giuliana Rubbia, Daniele Bravi, Valeria De Paola, Sergio Gurrieri, Maria Valeria Intini, and Silvia Peppoloni

According to the current legislation of Italy (e.g., Law No. 165/2001) public organizations must have a code of conduct in place, which specifies and complements the General Code of Conduct for public employees, embedding issues that are typical for the specific context. 

The Authority aimed at disseminating a culture of integrity and legality, the Italian National Anti-Corruption Authority (ANAC), provided a set of directives over time that specifies key actors and procedures, drafting methods, and fundamental principles that the Code must contain.

In this framework, public research institutes are no exception. At the National Institute of Geophysics and Volcanology of Italy (INGV) an interdisciplinary working group with diverse experiences and profiles has been created and committed to reviewing the current code of conduct and proposing a new one.

The drafting process progressed through a thorough examination of fundamental principles and compliance with laws, on the one hand, and with an in-depth analysis of areas of application in the context of the institute and its activities. 

Once drafted, the first version has been proposed for provisional approval by the Board of Administrators (CdA), and submitted for stakeholder consultation.  INGV personnel commented on the first version, expressed their concerns, and proposed various amendments. These comments have all been addressed, partially or completely accepted, or refused; an updated version has been created and submitted for a further round of approval by the Independent Evaluation Body (OIV), a body assessing the performance, clearness, and integrity of the administrative action.

The values on which the Code is structured refer to four geoethical domains: 1) the individual dimension, which concerns the ethical action of each individual recipient of the Code in the context of his/her specific work activity; 2) the interpersonal/professional dimension, which refers to relationships with colleagues; 3) the societal dimension, which includes relations with all the various components of society; and d) the relationship with the natural environment, which includes actions aimed at minimizing negative impacts on ecosystems and promoting eco-sustainable behaviors. Moreover, the code benefits from the principles expressed in the European Code of Conduct for Research Integrity and the European Charter for Researchers.

At present, the Code contains both ethical and legal norms, i.e. both principles underpinning appropriate behaviors and rules, which if violated give rise to sanctions.  Code recipients are called to observe them in order to ensure workplace well-being, quality of research and services, prevention of corruption phenomena, compliance with the constitutional duties of diligence, loyalty, impartiality, care of the public interest, and achievement of INGV institutional goals. The Code will be updated according to the structure of a new General Code of Conduct to be issued by the Italian Government.

How to cite: Rubbia, G., Bravi, D., De Paola, V., Gurrieri, S., Intini, M. V., and Peppoloni, S.: The evolving Code of Conduct at the National Institute of Geophysics and Volcanology of Italy: a participatory process to combine law compliance and geoethics principles, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7063, https://doi.org/10.5194/egusphere-egu23-7063, 2023.

EGU23-7377 | Posters on site | EOS4.1

For a sustainable future: a survey about geoethics and 2030 Agenda among the Italian geosciences community 

Elena Egidio, Andrea Gerbaudo, Manuela Lasagna, Francesca Lozar, and Marco Davide Tonon

The annual Congress of the Società Geologica Italiana (SGI) and Società Italiana di MIneralogia e Petrologia (SIMP), held in Turin in September 2022 and dedicated to Geosciences for a sustainable future, has been the occasion to critically think on the role of the Geosciences for our society and planet, on the position geoscientists deserve and the role they must take in the formation of citizens, protection from natural hazards and preservation of cultural and natural heritage. In continuation of our previously published work Are we ready for a sustainable development? A survey among young geoscientists in Italy , the present study broadens the sample analyzed to include the entire Italian community of geoscientists and aims to highlight: 1) The relevance of the ethical aspects connected to the work of professionals and scholars, in accordance with the values of geoethics; 2) the most widely held views about the connections between the Earth Sciences and the 17 Sustainable Development Goals of the UN 2030 Agenda; 3) which initiatives have been put in place by Italian Earth Sciences departments on education for sustainability and which can be the best strategies for developing sustainability education related to geoscience issues. Based on 230 answers to a questionnaire with open and closed questions sent to the participants at the Congress, the results show that the Italian geocommunity has great awareness of the ethical implications of its work and research, in particular of the responsibility towards the environment; despite this consciousness, the average level of knowledge about the 2030 Agenda and its goals is still scarce. To fill this gap, the need for sustainability education initiatives in departments is recognized as urgent, as well as the use of inter- and transdisciplinary educational approaches that can train scholars and professionals capable of addressing the complex challenges of our time.

How to cite: Egidio, E., Gerbaudo, A., Lasagna, M., Lozar, F., and Tonon, M. D.: For a sustainable future: a survey about geoethics and 2030 Agenda among the Italian geosciences community, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7377, https://doi.org/10.5194/egusphere-egu23-7377, 2023.

This communication aims at presenting how transitions are being made at different organizational scales at INRAE (French National Research Institute for Agriculture, Food and Environment): (1) at the scale of a research lab through the perspective of a sustainable development contact person, (2) at the scale of a regional research centre through the perspective of the sustainable development regional manager, and (3) at the national and institutional level with the view of the sustainable development director of INRAE. The overall institutional context is first introduced to further develop viewpoints of the three persons involved on the on-going transitions, the strengths of the implemented approach, but also the points of attention. This communication aims at triggering exchanges on how to make sustainable development reach all organizational levels while ensuring a global coherence, and notably across all professions including administration staff, scientists, engineers, etc.

How to cite: Gauthier, L., Vidal, J.-P., and Carnet, A.: How to make a sustainable development approach successful across all scales of a research institute? Crossed views at INRAE, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7600, https://doi.org/10.5194/egusphere-egu23-7600, 2023.

EGU23-7601 | Orals | EOS4.1

Reducing environmental impact at NERSC (Bergen, Norway). 

Julien Brajard and Christine Due Sivertsen

NERSC is a non-profit research foundation established in Bergen (Norway) in 1986. Besides cutting-edge research in climate science, the NERSC has for a long time been very attentive to the working conditions, diversity, inclusion, and environmental impact of its activities.

In this poster, we will present the different efforts taken at the NERSC initiative to take the path of reducing its environmental impact, especially the GHG footprint, of its activities. We have divided the analysis into big compartments including the travels, the numerical computations, the field campaigns, and the premises. For each compartment, we are in the process to assess the GHG emissions, and some actions have already been taken to already minimize the impacts, for example, a travel policy, and opportunity campaigns.

In addition to the details of the work done by NERSC for reducing GHG emissions, we will reflect on challenges and problems encountered while taking those actions, some being general to the scientific or geoscience field (e.g., travel injunction), others being specific to NERSC (fundings, geographic location, low-carbon electricity).

Finally, we will draw perspective to the experience, and try to bring recommendations into the debate, such as a better inclusion of climate impact in the European research calls.

How to cite: Brajard, J. and Sivertsen, C. D.: Reducing environmental impact at NERSC (Bergen, Norway)., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7601, https://doi.org/10.5194/egusphere-egu23-7601, 2023.

EGU23-7612 | ECS | Orals | EOS4.1

My earth in 180 minutes: A transition support system for reducing the carbon footprint in Academia. Experimental design for evaluating its impact on academic practices 

Claudia Teran-Escobar, Nicolas Becu, Nicolas Champollion, Nicolas Gratiot, Benoit Hingray, Géremy Panthou, and Isabelle Ruin

Some practices embedded in academic culture (international conferences, scientific instruments...) are  important sources of greenhouse gases (e.g., van Ewijk & Hoekman, 2021). Although the scientific community have started to propose ways to reduce the impact of international conferences (e.g., Warner et al., 2022), collective efforts should be pursued to reduce the carbon footprint of the entire academic world. Serious games have been used in the encourage climate change attenuation practices (Fernández Galeote et al., 2021). Nevertheless, to our knowledge, the deployed evaluations have only measured the changes on knowledge and not on actual practices.

My Earth in 180 Minutes (ME180, https://materre.osug.fr/) is a collaborative role-playing game aiming at raising awareness, stimulating interactions in groups and constructing scenarios of professional carbon footprint reductions with multiple stakeholders. The game sessions place staff (researchers, technical and administrative staff, etc.) in a situation of social interaction in which each person plays two characters (inspired from real life observations) of a research team needing to reduce its carbon footprint by 50%. The game allows to build scenarios to reproduce as much as possible the complexity of interactions and the level of inequality existing within academic world. With 85 games played between November 2020 and June 2021, My Earth in 180 Minutes collaborative workshop has shown robust results, in particular Academia’s capacity to reduce its own carbon footprint and propose concrete alternatives: video communication, mutualization and reduction of professional activities (Gratiot et al., 2022).

This communication will describe the methods designed to a) evaluate the effectiveness of the serious game “My Earth in 180 Minutes” in academic practices and b) investigate the factors (e.g., career status, family engagements) that enable or constrain changes in academic practices.

The protocol for a future study is described. Participants working in French research centres (N = 970) will be recruited and randomly split in two groups: a) a group who will participate to the ME180 workshop, or b) control group using another approach for discussing about Academic carbon footprint. Participants will complete online surveys about their professional practices (air travelling, commuting ...) and about the psychological, institutional and, sociodemographic factors related to these practices (intention towards reducing professional air travelling, number of children). The surveys will be repeated six times over the 2 years of the study: before the experiment, one, 6, 12, 18 and 24 months after the beginning of the study. Data will be analysed by using mixed linear methods.

We expect that carbon footprint reduction and related practices would be more important in the ME180 group. Mediation and moderation analysis will be used to identify psychological, institutional and, sociodemographic factors (career status, intention to change practices) that may facilitate or block the transition of professional practices.

The previous deployments of “My earth in 180 minutes” help in identifying Academic transition paths (Gratiot et al., in revision). The present study will allow to assess the effects of ME180 in Academic carbon footprint reduction to provide insights about the obstacles and levers of carbon footprint reduction in academia.

How to cite: Teran-Escobar, C., Becu, N., Champollion, N., Gratiot, N., Hingray, B., Panthou, G., and Ruin, I.: My earth in 180 minutes: A transition support system for reducing the carbon footprint in Academia. Experimental design for evaluating its impact on academic practices, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7612, https://doi.org/10.5194/egusphere-egu23-7612, 2023.

EGU23-8072 | Orals | EOS4.1 | Highlight

Hydrogeoethical questions related to urban groundwater management: the case of Kabul city, Afghanistan 

Mohammad Salem Hussaini, Asadullah Farahmand, and Manuel Abrunhosa

Groundwater resources are largely invisible and unknown to most people. Hence, unauthorized appropriation of groundwater is not obvious, and its impacts are less evident. It can be said that it is an invisible geo-resource but its impacts and problems are visible to mankind, even if often its source is not recognized. Kabul, the capital of Afghanistan, is the fifth fastest-growing city in the world and rapid population growth and urbanization have created huge pressure on groundwater resources. As a result of a lack of surface water storage and the seasonal variability of river flows, Kabul is among the world's most water-stressed cities as it depends almost entirely on groundwater. The findings of scientific studies reveal that extensive groundwater depletion and degradation of groundwater quality in Kabul city is largely due to anthropogenic factors and it is likely to rapidly continue in the future, particularly in densely populated areas of the city. Here, ethics can play an important role because human behavior is among the main factors creating the problems. So, hydrogeoethical concepts can be assessed and discussed, especially for urban groundwater where human needs (social ethics) and environmental dynamics (environmental ethics) both should be respected. In this study, the most vital questions related to ethical aspects of groundwater management in Kabul city are extracted. To achieve the questions, the water ethics principles and ethical criteria were evaluated concerning the condition of groundwater and the society of Kabul city, as an exercise of applied hydrogeoethics. Finally, six questions are obtained as the result of this study. The response to these critical questions could be a key to solving many dilemmas related to groundwater management in an urban concept. It is recommended to groundwater managers and policymakers explore the answer to these questions and consider the findings in the policies, strategies, and regulations, particularly in urban regions.

The questions are as follows:

1) What is the level of contribution, obligation, responsibility, honesty, trust, and respect among geoscientists, and engineers related to groundwater management?

2) What kind of regulation is adequate for the management of over-abstraction urban groundwater; top-down or self-regulation or a mix of both?

3) How education and communication can shape moral motivation for city residents to better groundwater management?

4) What is the level of participation of public media (TV, radio, newspapers, etc.) in awareness-raising campaigns related to groundwater conditions?

5) Can groundwater abstraction from the deep aquifer (groundwater mining) be an ethical and sustainable policy concerning future generations and environmental ethics?

6) How consideration of gender equity and women's participation can be effective in the management of groundwater?

How to cite: Hussaini, M. S., Farahmand, A., and Abrunhosa, M.: Hydrogeoethical questions related to urban groundwater management: the case of Kabul city, Afghanistan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8072, https://doi.org/10.5194/egusphere-egu23-8072, 2023.

EGU23-8173 | ECS | Posters on site | EOS4.1 | Highlight

The specific responsibility of geoscientists in the midst the climate and ecological crises: a need to address personal and institutional dissonances 

Odin Marc, Elodie Duyck, Laurent Lassabatère, Iñigo Viton, and Marthe Wens

The climate and ecological crises question the role and responsibility of scientists and scientific institutions as producers and conveyers of knowledge. Decades of thorough reporting, efforts at communication towards policy makers, and strong-worded scientific warnings, have not yet lead to policy changes significant enough to reduce greenhouse gas emissions and halt environmental degradation. This questions whether geoscientists and scientific institutions should remain distanced from the political and societal implications of their research work, or if on the contrary they have a responsibility to lead by example and to use their position to press for urgent action on the climate and ecological crisis. 

We argue that the failure of governments and international institutions to address these crises at the appropriate scale gives scientists and scientific institutions a responsibility to be more than mere producers of knowledge.  Indeed, doing “science as usual” while warning of the ever growing urgency to act on the climate and ecological crisis risks is widening the already-existing dissonance between, on the one hand, our stated raison d’être and discourses and on the other hand, our everyday practice and institutional mechanisms ; effectively undermining our impact on the broader society.

We first discuss the issue of scientific institutions and the scientific community at large not yet leveling with the urgency to address the climate and ecological crises. A prominent example is that despite repeated campaigns for universities to severe ties with the fossil industry, most  are still accepting sponsoring and research funding from fossil companies, which contributes to the legitimization of companies that have been and are still actively opposing effective climate action. While some universities are taking initiatives to limit carbon intensive behavior such as flying, serve plant-based food as a standard, stop accepting polluting companies on campuses, or include climate education in all curriculums, these are still individual initiatives, dependent on the voluntary mobilization from student and staff.

 We then argue that we, as geoscientists, can not only lead by example with individual changes to our lives, but can also have a strong impact when engaging in collective action, pressing our universities and governments to enact strong climate and environmental policies. Public engagement of universities, of other scientific institutions, and of scientists can amplify and legitimize the voice of the climate and environmental movements in a mutually beneficial science-society approach, notably because the former produce the very scientific knowledge empowering these movements.  We propose to discuss recent examples, including from our own experience, of the impact of scientists engaging in demonstrations and civil disobedience as part of environmental groups, at the ethical level, but also regarding consequences within and outside of academic circles.

How to cite: Marc, O., Duyck, E., Lassabatère, L., Viton, I., and Wens, M.: The specific responsibility of geoscientists in the midst the climate and ecological crises: a need to address personal and institutional dissonances, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8173, https://doi.org/10.5194/egusphere-egu23-8173, 2023.

EGU23-8259 | Posters on site | EOS4.1

Geoethics values clarification: A playable poster 

David Crookall and Pimnutcha Promduangsri

Values underlie geoethics and geoscience, especially climatology.  Can we understand or build geoethics without reference to values?  Are values and geoethics driven by beliefs, or should values remain unchanged despite changing beliefs?  Those are some of the questions that we may ask when considering ethics in life, in the geosciences and in climate change and action.  Values include honesty, compassion, quality, patience, objectivity, truth, respect, individualism, justice, power, peace and beauty.  How are these related to geoethics?  Often an ethical dilemma stems from two or more underlying value conflicts, such as individual identity and social value.  It is not easy to understand the principles and dynamics of such relations.

One way into this quagmire is by using a values clarification exercise or game (VCE or VCG).  A VCE can be a useful geoethics literacy tool to help people explore the complexities of such relationships, to allow them to express their own ideas, to confront their ideas with those of others and to gain a rich understanding of their own values that underlie geoethics.  Undorf and colleagues (eg, https://doi.org/10.5194/egusphere-egu22-12732, https://doi.org/10.1007/s10584-022-03435-7) have adopted a philosophical approach.  We take an easier approach, that of interactive, participatory gaming.

We have designed and used VCEs and VCGs in a variety of cultural and social settings and with encouraging results.  Our poster will outline our prior experience and allow you to participate, albeit superficially, in a VCE.  Please come to see us during the poster session, and be sure to bring along one or two friends so that you can play; three players is better than two.  Also bring some paper and a pen.

How to cite: Crookall, D. and Promduangsri, P.: Geoethics values clarification: A playable poster, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8259, https://doi.org/10.5194/egusphere-egu23-8259, 2023.

EGU23-8402 | ECS | Orals | EOS4.1

The share of research infrastructure in comprehensive greenhouse gas budget for five French Earth and Space Science laboratories 

Odin Marc, Sylvain Biancamaria, Solene Derrien, François Gheusi, Jürgen Knödleser, Sylvain Kuppel, Marion Maisonobe, Arnaud Mialon, Pierrick Martin, Florian Pantillon, Luigi Tibaldo, and Florence Toublanc

To maintain global warming below 1.5°C the last IPCC report indicates global greenhouse gas (GHG) emissions should be reduced by 45% and 80% before 2030 and 2050, respectively, reaching an average of 2 tCO2e.pers-1.yr-1 on Earth. Although responsibilities vary, substantial reductions must be implemented across all aspects of society including academia. It can even be argued that, given its role in informing and alerting the public about climate and ecological change, the scientific community should have a leading role and demonstrate exemplarity in terms of reducing its environmental impact.

Here, we present a broad-scope GHG budget of five laboratories of the Observatoire Midi-Pyrénées in France, in 2019. The studied laboratories comprise 90 to 260 staff members each, with study fields encompassing the solid Earth and the environment, the superficial biosphere, oceanography and glaciology, atmospheric physics and chemistry, as well as astronomy and astrophysics.

To assess GHG emissions, we follow standard procedure (see Mariette et al., Environ. Res.: Infrastruct. Sustain., 2022) in which anyactivity data’ quantifying the usage of a given resource (e.g., in kWh of electricity, or km travelled by aircraft) is multiplied with an appropriate emission factor’ quantifying the unitary carbon footprint of the resource (e.g., electricity production or air-travel). The quantified budget thus includes infrastructures usage, professional travel and expenses and an estimation of the GHG footprint of research infrastructures, in particular scientific satellites. For the latter, we adapted the methodology of Knödleser et al. (Nature Astronomy, 2022), in which the GHG footprint is estimated based on the launch mass or cost of the mission and the share attributable to a given lab depends on the fraction of world author affiliated with the lab who have published articles referring to the satellite, as extracted from the Web of Science database.

We find that emissions related to the lab facilities (electricity, heating, air conditioning and waste) and to individual habits (commuting and lunch meals) both reach about 1 tCO2e.pers-1.yr-1. Unsurprisingly, professional trips significantly contribute to the overall budget (2-6 tCO2e.pers-1.yr-1) and are largely dominated by long-haul air travel. However, services and equipment equally contribute with more than 3-5 tCO2e.pers-1.yr-1. These numbers vary between the studied labs but higher (lower) values for services and equipment tends to compensate for lower (higher) values for professional trips. Furthermore, for three out of five laboratories observational data from research infrastructures represents the largest share of the emissions, with about 5-10 tCO2e.pers-1.yr-1. Although this last estimate is subject to large uncertainty and shows discrepancies between research fields, it suggests that current GHG budget should include at least a first order estimate of the footprint of research infrastructures and adapt reduction strategies accordingly.

How to cite: Marc, O., Biancamaria, S., Derrien, S., Gheusi, F., Knödleser, J., Kuppel, S., Maisonobe, M., Mialon, A., Martin, P., Pantillon, F., Tibaldo, L., and Toublanc, F.: The share of research infrastructure in comprehensive greenhouse gas budget for five French Earth and Space Science laboratories, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8402, https://doi.org/10.5194/egusphere-egu23-8402, 2023.

EGU23-8683 | Orals | EOS4.1 | Highlight

The Knowledge Hub on Sea Level Rise and the science-based European Seas assessment reporting 

Nadia Pinardi, Bart van den Hurk, Jose A. Jimenez, Gundula Winter, Giulia Galluccio, Sandy Bisaro, Angelique Melet, Roderick van de Wal, Kristin Richter, Jan-Bart Calewaert, Bernd Bruegge, Lavinia G. Pomarico, Michael Depuydt, Thorsten Kiefer, and Petra Manderscheid

Nine European countries under the umbrella of the Joint Programming Initiatives on Climate (JPI Climate) and on Oceans (JPI Oceans) have set up a joint Knowledge Hub on Sea Level Rise. The ambition is to provide easy access to usable knowledge on regional-local sea level change in Europe, regularly updated as a series of periodic assessments. It will complement existing global and national assessments by providing additional geographical and contextual detail, tailored to regional, national and European policy development and implementation.

As its key product, it will deliver by the end of 2023 its first European Assessment Report on Sea level rise hazards and impacts, co-designed with European Sea stakeholders. The co-design framework is based on consultation workshops, questionnaires and a final Conference in Venice that enabled to discuss at large the regional and local end-user needs.

Based on the latest available science provided by  the IPCC AR6 WGI and II reports and using the most advanced knowledge on sea level rise from European services and research done at the national level, the Assessment report will allow to downscale to the European Seas the SLR impacts and devise adaptation strategies. We will present the user needs that were revealed by the stakeholder consultations and plan to provide a peek into the content of the first draft of this first Assessment Report.

How to cite: Pinardi, N., van den Hurk, B., Jimenez, J. A., Winter, G., Galluccio, G., Bisaro, S., Melet, A., van de Wal, R., Richter, K., Calewaert, J.-B., Bruegge, B., Pomarico, L. G., Depuydt, M., Kiefer, T., and Manderscheid, P.: The Knowledge Hub on Sea Level Rise and the science-based European Seas assessment reporting, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8683, https://doi.org/10.5194/egusphere-egu23-8683, 2023.

Local climate change risk assessments and climate resilient adaptation are best supported by a quantitative integration of physical hazards, exposures and vulnerabilities that includes the characterization of uncertainties. However, it is challenging to take into account the complex information of climate change projections and uncertainties in participatory risk assessments with decision-makers. We propose to use Bayesian Networks (BNs) for this task. Bayesian Networks are a cutting-edge integrated modelling approach for combining qualitative and quantitative knowledge in uncertain and complex domains, such as climate change impacts on water. To quantify potential future hazards of climate change on water, it is state-of-the-art to rely on multi-model ensembles to integrate the uncertainties of both climate and impact modelling. At the same time, local expert knowledge needs to be integrated in local climate change risk assessments. We show how to integrate freely-available output of multiple global hydrological models into BNs, in order to probabilistically assess risks for water supply. To this end, a roadmap to set up BNs and apply probability distributions of risk levels under historic and future climate and water use in a participatory manner was co-developed with water experts from Spain and the Maghreb. Multi-model information on hydrological variables was computed by three global hydrological models driven by the output of four global climate models for four greenhouse gas emissions scenarios. The output of projected relative changes of hydrological hazards was pre-processed using MATLAB, taking into account local information on water availability and use, to set up the BN. Results show that the method is useful for probabilistically computing climate change impacts on water stress and to assess potential adaptation measures in a participative process with stakeholders and decision-makers. Local water experts positively evaluated the BN application for local climate change risk assessments. While requiring certain training, the presented approach is suitable for application in the many local risk assessments necessary to deliver efficient and successful climate resilient adaptation.

How to cite: Kneier, F., Woltersdorf, L., and Döll, P.: Participatory Bayesian Network modelling to assess climate change risks and adaptation regarding water supply: integrating multi-model ensemble hazard information and local expert knowledge, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8861, https://doi.org/10.5194/egusphere-egu23-8861, 2023.

EGU23-8882 | Posters on site | EOS4.1

How to reduce the carbon footprint of Earth and Space Science? Potential strategies based on a comprehensive greenhouse gas budget for five French labs 

Florian Pantillon, Sylvain Kuppel, Sylvain Biancamaria, Solene Derrien, François Gheusi, Jürgen Knödlseder, Marion Maisonobe, Odin Marc, Arnaud Mialon, Pierrick Martin, Luigi Tibaldo, and Florence Toublanc

To maintain global warming below 1.5°C the last IPCC report indicates global greenhouse gas (GHG) emissions should be reduced by 45% and 80% before 2030 and 2050, respectively, reaching an average of 2tCO2e.pers-1.yr-1 on Earth. Recent estimates of the carbon footprint of universities and research centers accounting for indirect emissions often exceed 10tCO2e.pers-1.yr-1.

Here we find similar or higher values (10-30tCO2e.pers-1.yr-1) for the year 2019 for five research labs encompassing the solid Earth and the environment, the superficial biosphere, oceanography and glaciology, atmospheric physics and chemistry, and astronomy and astrophysics. These values are derived through a common procedure (see Mariette et al., 2022) in which any activity data quantifying the usage of a given resource (e.g., in kWh or km) is multiplied by an appropriate emission factor quantifying the unitary carbon footprint of the resource (e.g., electricity production or air travel). Our budget quantifies the share of emissions from local facilities (about 1tCO2e.pers-1.yr-1), lunch meals and commuting (about 1tCO2e.pers-1.yr-1), professional trips (2-6tCO2e.pers-1.yr-1), services and equipment (3-5tCO2e.pers-1.yr-1), and the use of observational data from research infrastructures, in particular scientific satellites (up to 10tCO2e.pers-1.yr-1; derived similarly to Knödlseder et al., 2022).

These numbers imply radical changes to make scientific activity sustainable and have strong implications on potential strategies to reduce GHG emissions. For example, a predominant discussion in the literature in the past years focused on avoiding air travel. However, in our case, shifting all national travels to train or halving the number of plane trips would reduce the total emissions by a fraction only. Similarly, any strategy targeting local building efficiency or individual habits will little influence the budget. In contrast, reducing or changing practice for services and equipment may have stronger impact but requires collective thinking, especially for research infrastructures that are planned and managed at national and international levels.

The sheer magnitude of our GHG emissions questions the degree of reduction that can be achieved without redirection of scientific activity. We present and discuss examples of changes such as shifting to interdisciplinary research including social sciences, focusing on archived data, relocating field work, or engaging more with students and society.

How to cite: Pantillon, F., Kuppel, S., Biancamaria, S., Derrien, S., Gheusi, F., Knödlseder, J., Maisonobe, M., Marc, O., Mialon, A., Martin, P., Tibaldo, L., and Toublanc, F.: How to reduce the carbon footprint of Earth and Space Science? Potential strategies based on a comprehensive greenhouse gas budget for five French labs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8882, https://doi.org/10.5194/egusphere-egu23-8882, 2023.

EGU23-9299 | ECS | Orals | EOS4.1

From informal to institutional science-society-policy interactions: Introducing a climate advisory board in Frankfurt, Germany 

Georg Sebastian Voelker, Ralf Becherer, Carmen Junge, and Thomas Seifert

Climate change may be the most severe crisis humanity has faced to date. Both the social and natural sciences have well understood the causes and effects of climate change as well as the possible mitigation and adaptation measures. However, implementations of both mitigation and adaptation measures generally fall behind the goals defined by the Paris agreement.

With increasing political awareness and progressing federal climate protection legislation in Germany communal politics is facing the challenge of charting explicit paths to net carbon neutrality. Due to diverse social and geographic settings as well as different existing infrastructures solutions have to be tailored to the local conditions. Local climate advisory panels are a common and if well constructed an effective way to support the local administration in the necessary transformation.

Here we report on the successful efforts lead by the local group of the Scientists for Future in Frankfurt, Germany, to aid the city hall in establishing a communal climate advisory panel. Early stakeholder communication, broad alliances with local climate protection initiatives and the shared experience of the Scientists for Future network were key to successfully establish an institutionalized science-society-policy interface to permanently support local climate action activities.

How to cite: Voelker, G. S., Becherer, R., Junge, C., and Seifert, T.: From informal to institutional science-society-policy interactions: Introducing a climate advisory board in Frankfurt, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9299, https://doi.org/10.5194/egusphere-egu23-9299, 2023.

EGU23-10073 | Posters virtual | EOS4.1

Teaching Geosciences through practical activities to enhance global citizenship education in schools with a high dropout rate 

Ester Piegari, Giovanni Camanni, Daniela Flocco, Maurizio Milano, Nicola Mondillo, and Umberto Riccardi

Most students living in disadvantaged areas do not trust that their school education will have much bearing on their future and become disaffected from school as early as in lower secondary school.

We here report the results of teaching Geosciences through several practical activities carried out in suburban schools characterized by a high dropout rate. The lectures were given in the framework of the STEM project Next Land, which has the overarching goal of instilling interest towards scientific topics into young students and promoting the role of scientific education for sustainable development.

We propose a sequence of four laboratory activities on the subject of natural calamities (e.g. earthquakes and tsunamis), which are based on the use of both manual and IT skills.

The didactical experimentation has been conducted on 21 seventh-grade classes (age ~12) involving about 350 students from the area of Naples (Southern Italy). The final aim of the teaching is to test the potential of the Geosciences in generating attitudes and behaviours of solidarity and responsible global citizenship.

All the proposed activities try to make students aware that they are part of a connected global system, therefore through these lectures we attempt to help these young students to put in perspective their local reality in a larger one.

How to cite: Piegari, E., Camanni, G., Flocco, D., Milano, M., Mondillo, N., and Riccardi, U.: Teaching Geosciences through practical activities to enhance global citizenship education in schools with a high dropout rate, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10073, https://doi.org/10.5194/egusphere-egu23-10073, 2023.

Existential and Global Catastrophic Risk, defined by Beard et al 2020 as risk that may result in the very worst catastrophes “encompassing human extinction, civilizational collapse and any major catastrophe commonly associated with these things.” As such, it has been the topic of work by many philosophers as we move into a world where humans have more and more power over the world around us.

However, geoscientists have typically neglected the study of these risks, and have in turn been neglected in the field of existential risk studies. I will discuss the ethical importance of reducing existential risk from a variety of different ethical frameworks, and how this links to the concepts in geoethics. I will then discuss some of the opportunities for geoscientists to contribute to the reduction of these risks, including some of the work that has been done by geoscientists to identify and reduce existential risk and increase civilisational resilience, as well as how methodological expertise of different geoscience disciplines can contribute to the growing corpus of theoretical work around existential risk.

How to cite: Futerman, G.: The Ethics and Role of Geoscientists in Existential Risk Studies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10097, https://doi.org/10.5194/egusphere-egu23-10097, 2023.

Minerals occupy a unique position as specimens yielding scientific information, objects with aesthetic and monetary value, and substances necessary for modern society. Aside from minerals in industrial use, a broad range of people are interested in minerals such as geologists, gemologists and jewelers, and people involved in minerals as collectors’ items including miners, dealers, private and institutional collectors, curators -- even art collectors and anthropologists. Traditionally, we have taken the extractive nature of these minerals for granted with little discussion of where and how they are obtained.

Adherence to legalities, disclosure of information, and personal and institutions responsibility are among ethical considerations. Legal considerations include how a mineral specimen is obtained in its initial extraction, its movement through opaque supply chains, export and import requirements, and ownership transfer. Disclosure issues range from curators and institutions maintaining and relaying accurate information about a mineral’s authenticity, sourcing, and history. What ethical responsibilities do individuals and institutions possess to ensure acquisition policies that address these issues? And, finally, as mineral extraction becomes a more pressing issue in the world’s move from a fossil-fuel economy, where does ethics lie in educating the public in the role minerals play in the environment and society?

Some of these questions raise issues which, in their complexity, have no apparent or easy solution. This paper presents the results of a literature survey on ethics of mineral specimens and raises questions for geoscientists.

How to cite: Eriksson, S.: Things we just don't talk about:  ethics in mineral collection, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10191, https://doi.org/10.5194/egusphere-egu23-10191, 2023.

EGU23-10946 | Posters on site | EOS4.1

Research in Volcanology: where, when, and by whom? A global bibliometric analysis 

Susanna F. Jenkins, Geoffrey A. Lerner, George T. Williams, Elinor S. Meredith, and Jenni Barclay

The global and transdisciplinary nature of volcanology means that research takes place across institutions in a wide variety of locations around the world. The concentration of volcanic activity within certain regions means that researchers frequently conduct research outside their own borders. Collaboration between international and local researchers has the potential to produce mutual benefit and improve research. For local scientists, international collaboration can provide niche expertise that may not be currently available in the region where the volcano is located, in addition to resources, analyses, or equipment. For international researchers, in addition to different scientific perspectives, collaboration with local scientists can provide vital knowledge of local and regional information, access to field sites, and greater research relevance to the communities and organizations the research is often intended to benefit.

Despite these noted benefits, there is often a lack of inclusivity of local scientists in international research. In this study we use a bibliometric approach to understand who is doing and leading volcanic research, and in which countries the research is taking place. We assessed the metadata of ~24,000 volcanological works from 1901-2021 with 768 volcanoes identified across 68 countries. Our evaluation of affiliations shows that 40% of articles that name a volcano do not include any authors affiliated with the volcano’s country. We also look at case studies of island territories to explore to what extent local scientists are involved in doing research compared to the mainland or foreign countries. We find that only 23% of studies on volcanoes located on island territories have an author affiliated with the territory. Our assessment of bibliometric data provides insights and support for ongoing conversations on the inclusiveness of international research, both spatially and temporally, and can be used to identify geographical areas for improvement, as well as trends in inclusion and leadership.

How to cite: Jenkins, S. F., Lerner, G. A., Williams, G. T., Meredith, E. S., and Barclay, J.: Research in Volcanology: where, when, and by whom? A global bibliometric analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10946, https://doi.org/10.5194/egusphere-egu23-10946, 2023.

EGU23-11580 | Orals | EOS4.1

Geoethics: hammering out an interdisciplinary conversation 

Bethany Fox, Kate Dawson, Vicki Trowler, Sophie Briggs, Ruth Massey, Alexandra Fitzsimmons, Tania Marshall, Christina Riesselman, and Anna Davidson

Geoethics is not just a matter of geoscience, but involves complex transdisciplinary concerns with social, economic and cultural implications. Because of this, both geoethicists within geosciences and those working in social sciences and humanities are increasingly calling for dialogue across disciplinary silos. Drawing from our work on the British Academy funded interdisciplinary project, ‘Mining for Meaning: the Geoethics of Extractive Industries,’ we trace out what an interdisciplinary engagement with Geoethics might look like. As an earthly ethics that necessarily stretches beyond geological considerations to consider the socio-natural, cultural-spiritual and political-economic, any engagement with Geoethics demands conversations that bring geoscientific understandings into more explicit dialogue with ideas from the social sciences and the geohumanities (though not exclusively). Acknowledging the very real challenges of doing interdisciplinary work - from distinct understandings about research, knowledge and results, to disciplinary-specific technical terminology - we set out the core ideas underpinning Geoethical approaches in these domains. This lays important groundwork for crafting meaningful and indeed ethical conversations that stretch across these disciplines, but crucially, avoids the mining of other disciplines for useful concepts and metaphors, without due regard for their context, history and technical meaning – a form of disciplinary extractivism in itself. Animated by this anti-extractivism, the paper presents a reading of how the earth, ethics, knowledge and practices are understood from within the geosciences, social sciences and geohumanities respectively, charting out what we hope to be a useful frame of reference for working across these disciplines. We then use this analysis as the bedrock for discussing the potential of cross-disciplinary conversation. By critically responding to the relative strengths, limitations and offerings of each discipline’s conceptualisation of geoethics, we bring to the fore important interdisciplinary frictions, overlaps and potential collaborative directions. Taken together, we suggest that this two-part analysis offers scope for crafting meaningful conversations necessary for an interdisciplinary Geoethics. 

How to cite: Fox, B., Dawson, K., Trowler, V., Briggs, S., Massey, R., Fitzsimmons, A., Marshall, T., Riesselman, C., and Davidson, A.: Geoethics: hammering out an interdisciplinary conversation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11580, https://doi.org/10.5194/egusphere-egu23-11580, 2023.

EGU23-11656 | Orals | EOS4.1

Traveling for academic research : patterns, determinants and mitigation options 

Olivier Aumont, Tamara Ben Ari, Jérôme Mariette, Laurent Jeanneau, Aymeric Spiga, Gaelle Lefort, Philippe-e Roche, Alexandre Santerne, and André Estevez-Torres

In the midst of climate change, academic travels - one salient aspect of the carbon footprint of research activities - are at the center of a growing concern. Mitigation options often focus on two dimensions : (i) decreasing the frequency of attendance to conferences and (ii) modal shift in transport. Here, we analyze professional travel in academia from a unique database compiling about 100 000 travels from about 150 research labs across a large array of disciplines and localities in France to detail the structure, patterns and heterogeneity of national and international research travels for research purposes. We estimate the mitigation potential of a series of options encompassing but not limited to institutional options. We show that, if short distance traveling (typically below 1000 km) are largely dominant in number, their relative mitigation potential via modal shift is small (i.e., below 15%). On the other hand, long distance traveling, which is often associated with international collaborations or field work hold a much larger mitigation potential but question the very nature of research activities. We propose ambitious sobriety options to robustly decrease travel-induced GHG emissions in academia and discuss their acceptability in the context of the French public research system.

How to cite: Aumont, O., Ben Ari, T., Mariette, J., Jeanneau, L., Spiga, A., Lefort, G., Roche, P.-E., Santerne, A., and Estevez-Torres, A.: Traveling for academic research : patterns, determinants and mitigation options, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11656, https://doi.org/10.5194/egusphere-egu23-11656, 2023.

EGU23-12019 | ECS | Posters on site | EOS4.1

Development of a Web Based Decision Support System to Provide Relevant Climate Indicators for Climate Change Adaption 

Lorenz König, Mike Teucher, Katrin Ziegler, Daniel Abel, Torsten Weber, Heiko Paeth, and Christopher Conrad

The African continent faces various challenges and numerous risks due to current and future climate change. To strengthen the resilience of West African societies in the sectors of agriculture, food security, water and risk management, adaption measures need to be implemented in time. In the WASCAL-LANDSURF project, an earth system model for West Africa is developed to enable high-resolution regional climate change information. The obtained data must be accessible to the public so that interested stakeholders and smallholders can incorporate them into their decision-making processes.
To realize this, a web based spatial decision support system (SDSS) is developed with state-of-the-art open-source technologies to give information on climate change as well as relevant cross-sector indicators. For successful co-development, stakeholder workshops were held to identify important key functionalities and indicators that need to be implemented. The SDSS will be multilingual and easy to use to ensure an extensive range of applications. Users will have the possibility to familiarize themselves with the Web Portal by means of different guides in order to ease the entry into the SDSS. The current prototype supports map and diagram visualization and selection of various indicators and climate data, as well as query functionalities for different West African regions. Many other functionalities, such as the possibility to download data and statistical outputs of selected indicators, will be integrated soon. The final web portal will give users the opportunity to include climate indices in a simple and clear way into their decision-making process to strengthen their resilience towards climate change.

How to cite: König, L., Teucher, M., Ziegler, K., Abel, D., Weber, T., Paeth, H., and Conrad, C.: Development of a Web Based Decision Support System to Provide Relevant Climate Indicators for Climate Change Adaption, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12019, https://doi.org/10.5194/egusphere-egu23-12019, 2023.

EGU23-12106 | Orals | EOS4.1

Taking Stock of Greenhouse Gas Emissions in the Geosciences: an Example from GFZ Potsdam 

Christoph Sens-Schönfelder, Friedhelm von Blanckenburg, and Knut Kaiser

The basis of all serious efforts to reduce greenhouse gas emissions is an inventory of the emissions caused by the various activities of an organisation. The Greenhouse Gas Protocol provides the guideline for establishing such an inventory. The German Research Centre of Geosciences GFZ Potsdam used these guidelines to estimate its greenhouse gas emissions for 2019. Besides the estimation of quantities (e.g. travel distances or hotel nights) which is an administrative challenge, the specific emissions per unit of quantity -- the Global Warming Potential -- play a crucial role. Unequivocal accounting of emissions from construction work is another task of great complexity.  A compilation and standardisation of these values within the research community would greatly simplify the compilation of GHG inventories and help to improve their comparability. Controversy inevitably will arise regarding the design of mitigating measures, like purchase of electricity and heat from renewable sources (which generates extra costs) the compensation of emissions (of which the effectiveness is contested), and even to shifting scientific activities away from those with high greenhouse gas footprints (which may conflict with scientific needs). Building awareness for emissions caused by academic activities and careful communication of mitigation options comprise the first necessary steps en route to low (or net-zero)-emission science.

How to cite: Sens-Schönfelder, C., von Blanckenburg, F., and Kaiser, K.: Taking Stock of Greenhouse Gas Emissions in the Geosciences: an Example from GFZ Potsdam, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12106, https://doi.org/10.5194/egusphere-egu23-12106, 2023.

EGU23-12452 | ECS | Orals | EOS4.1 | Highlight

The ethics of volcano geoengineering 

Lara Mani, Mike Cassidy, and Anders Sandberg

Volcano engineering is the practice of altering the state of volcanic systems and/or volcanic eruptions to exploit them or mitigate their risk. Past and current examples of volcano engineering are limited but include drilling crater walls to drain volcanic lakes, channeling and bombing lava flows, siphoning off CO2 rich volcanic lakes, and cooling lava flows with seawater. There have also been several incidental examples of drilling into magma reservoirs in search for geothermal resources in Hawaii, Iceland, and Kenya. While not causing anything more damaging than the loss of drill bits or forcing the use of alternative holes, this demonstrates that humans are increasingly able to reach volcanic plumbing systems. As the pursuit of high temperature and enhanced geothermal energy increases as the world strives for renewable energy and critical metal resources, it is also likely that such contacts will become more common. We must accept, therefore, that despite the controversial nature of this topic, geoengineering of volcanic systems is an inevitable consequence of such exploration in the coming century. Since we possess the technological and engineering potential to perturb volcanic systems, the question we ask here is, should we? Do we have the scientific knowledge to do so? What are the potential benefits to future humanity? And, what are the ways it could do more harm than good? We highlight that while volcano geoengineering has significant potential benefits, the risks and uncertainties are too great to justify its use in the short term. Even if we do not decide to conduct volcano geoengineering, we believe there is a strong ethical case to support research into the efficacy and safety of volcano geoengineering going forwards. In this work, we lay out a series of protocols and practices based on the ethical arguments to be followed should humanity decide to conduct volcano geoengineering in the future.

How to cite: Mani, L., Cassidy, M., and Sandberg, A.: The ethics of volcano geoengineering, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12452, https://doi.org/10.5194/egusphere-egu23-12452, 2023.

EGU23-13681 | ECS | Orals | EOS4.1

Engaging stakeholders for the co-creation of Climate Services. Beyond ERA4CS INDECIS project  

Jon Xavier Olano Pozo, Anna Boqué Ciurana, and Enric Aguilar

INDECIS (Integrated approach for the development across Europe of user-oriented climate indicators for GFCS high-priority sectors: agriculture, disaster risk reduction, energy, health, water, and tourism) was a project part ERA4CS, an ERA-NET initiated by JPI Climate, and funded by FORMAS (SE), DLR (DE), BMWFW (AT), IFD (DK), MINECO (ES), ANR (FR) with co-funding by the European Union Grant 690462). INDECIS main produced different outcomes, such as software packages, improved datasets and a large number of scientific papers (see www.indecis.eu). 

 

Even though INDECIS formally ended in July 2021, the knowledge gained continues to pay off. This communication will synthetically show how we took advantage of the methodology for the engagement of stakeholders developed in INDECIS (Font et al. 2021). The co-creation methodology developed in the frame of INDECIS has served as a starting point for the development of further research, transfer, and empowerment actions of stakeholders for decision-making related to climate change in four main axes: in research, in leading international research and transfer projects in collaboration with industry, in local projects developed in partnership with industry, users and administration and, knowledge transference to high schools, bachelor degree and technical training to professionals. 

 

The research has continued through a doctoral dissertation based on co-creating a climate service for surfing (see Boqué Ciurana, 2022). It is also continued by developing more indices for tourism and tourism sites to face climate change effects through mitigation measures in the TURLIT-ODS project (see: http://turlit.eu). This project is a local scale project where with users, private actors, and administration, we try to define the optimal conditions to develop sport water activities in Calafell, Costa Daurada, Spain. 

 

With the industry, in collaboration with a private organization, we engage stakeholders in the infrastructure sector to co-define climate risk indices to manage risk and investments. In this project, through co-creation workshops developed with local agents from both the company (technical) and the administration and other sectorial actors, indices are being computed to assess the climate risk of mobility infrastructures (railways and highways). 

 

The co-creation methodology has been adapted to develop high school co-creation processes to empower young people with tools to fight climate change and misinformation (see EMPOCLIM project: http://www.empoclim.cat ). In the same way, the Geography, Sustainability, and Territorial Analysis bachelor at the Rovira i Virgili University, offers a subject (6 ECTS) to develop essential skills and competences for developing climate services based on the engagement of local stakeholders and co-creation. 

 

Last but not least. Updating the quality control and data homogenization software has allowed the development of training for NMHs in Colombia, Peru, and Chile in the frame of the ENANDES project. In this training, we added lectures and practices to capacity-building staff in co-creating climate services with local users. 

 

How to cite: Olano Pozo, J. X., Boqué Ciurana, A., and Aguilar, E.: Engaging stakeholders for the co-creation of Climate Services. Beyond ERA4CS INDECIS project , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13681, https://doi.org/10.5194/egusphere-egu23-13681, 2023.

EGU23-13694 | Orals | EOS4.1

Reducing the carbon footprint of a public research laboratory in Geosciences. Assessing a reduction strategy built with laboratory members after a 3-year experimentation 

Thierry Pellarin, Nicolas Champollion, Nicolas Gratiot, Claudia Teran-Escobar, Isabelle Ruin, Geremy Panthou, Benoit Hingray, Gilles Delaygue, Eliot Jager, Alexis Lamothe, Guillaume Piton, Guillaume Evin, Juliette Blanchet, Nathalie Philippon, Armelle Philip, Patricia Martinerie, and Ghislain Picard

The Institute of Environmental Geosciences (IGE) is a public research laboratory in Earth and Environmental Sciences with a staff of about 300 people, which conducts research on climate, the anthropisation of our planet and environmental risks, combining glaciology, hydrology, oceanography, mechanics, atmospheric sciences and human sciences. An important part of its activity consists of field experiments in remote sites (Antarctica, Asia, South America, Africa), numerical simulations using significant computer resources (several million CPU hours/year), using expensive and sometimes energy intensive scientific equipment (e.g. 170 m² of cold rooms).

In 2019, the laboratory collectively decided to adopt a strategy to reduce its Carbon Footprint (CFP) by 7% per year in order to achieve a 50% reduction by 2030 and thus to comply with the objectives of the Paris Agreement. The first CFP budget (2018 and 2019, using the GES1point5 tool) showed a predominance of emissions from professional travels (~640 tCO2e out of 1850 tCO2e, i.e. 2.6 tCO2e/person). In this context, the strategy consisted in defining CO2 budgets for each of the 8 research teams of the IGE on the basis of the 2018/2019 emissions, imposing a 10% reduction per year from 2020. Given the pandemic in 2020 and 2021, the reduction targets for professional travel were easily achieved (-81% and -64%) and the reduction in 2022 was -39% compared to 2018/2019 instead of the targeted -27%.

For all emission items (commuting, professional travel, heating, electricity, digital computing, purchasing, refrigerants), the reduction was -45% in 2020, -30% in 2021 and -15% in 2022. To consider the evolution of the number of people in the laboratory (and in the teams), the mean individual CFP has been defined as the ratio between the CO2 emissions and the number of people in the laboratory. The IGE's mean individual CFP was 7.22 tCO2e/person in 2018/2019 and 5.45 tCO2e/person in 2022 (for a target of 6.0 tCO2/person). It should be 3.61 tCO2e/person in 2030.

The strategy (the long-term reduction trajectory and the team-based reduction objectives) is well received by the IGE laboratory staff, even if some staff are still reluctant to any form of reduction. To ease its implementation and check whether it is being kept, a bimonthly monitoring of the teams’ emissions and the mean personal CFP was set up. The IGE also proposes participation in awareness-raising tools (La Fresque du Climat, Ma Terre en 180'). Significant changes in travel habits have followed. For instance, out of the 30 members of the IGE who come to the EGU in Vienna each year, 90% came by plane and 10% by train (a 20-hour long journey) in 2018/2019, and this ratio was 25% by plane and 75% by train in 2022.

To achieve our objective, further actions need to be identified to reduce the "purchase" and "digital computing" emission posts. What will help is that the insulation of the buildings was initiated in 2022, and the cold rooms which emitted a very strong greenhouse gas (refrigerant gas R508b) were changed in 2022 for a model operating with CO2.

How to cite: Pellarin, T., Champollion, N., Gratiot, N., Teran-Escobar, C., Ruin, I., Panthou, G., Hingray, B., Delaygue, G., Jager, E., Lamothe, A., Piton, G., Evin, G., Blanchet, J., Philippon, N., Philip, A., Martinerie, P., and Picard, G.: Reducing the carbon footprint of a public research laboratory in Geosciences. Assessing a reduction strategy built with laboratory members after a 3-year experimentation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13694, https://doi.org/10.5194/egusphere-egu23-13694, 2023.

EGU23-13910 | Orals | EOS4.1 | Highlight

Social production of ignorance – the role for geoscientists in addressing “undone science” 

Fiona Johnson, Philippa Higgins, Martin Andersen, Kirsty Howey, Matthew Kearnes, Stuart Khan, and Greg Leslie

In this presentation we discuss the role of geoscientists and engineers in advocating for improved civic science that can minimise the impacts of industrial and mining activities on the environment and downstream communities, with a particular focus on water-related impacts. We argue that, if not carefully designed, data collection, analyses and communication by geoscientists does not always contribute to the wider public good because the issues that communities care about are not addressed – so called “undone science”. A case study, focusing on the environmental impacts of the McArthur River mine (MRM) in a remote part of the Northern Territory, Australia, is used to highlight key issues that should inform civic science and lead to better outcomes for communities and the environment.

Despite thousands of pages of “data” about the MRM project and its impacts, we argue that this project is an example of the social production of ignorance – because the knowledge of the communities most impacted by the mine’s activities is not improved by the reporting and impact assessments associated with the project. Based on a temporal synthesis of independent monitoring reports of the McArthur River Mine which covered the period from 2007 to 2018, we identify three main lessons for improving civic science. Firstly, without adequate baseline monitoring prior to development, data collection during a project cannot satisfactorily assess impacts of a development. Baseline data is particularly important when seasonal and interannual variability is high. Baseline and ongoing monitoring programs should be co-designed with the community, so that what matters to the community is monitored (e.g. culturally important sites, contamination in animal species relevant to the community). Secondly, geoscientists and engineers need to partner with social scientists and local community organisations to ensure that communities are effectively informed about the impacts of development, focusing on the impacts that matter to communities, not just the impacts that are conveniently measured. Finally regulatory processes need to be improved to ensure that problems identified by geoscientists and engineers are addressed.

How to cite: Johnson, F., Higgins, P., Andersen, M., Howey, K., Kearnes, M., Khan, S., and Leslie, G.: Social production of ignorance – the role for geoscientists in addressing “undone science”, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13910, https://doi.org/10.5194/egusphere-egu23-13910, 2023.

EGU23-14085 | Posters virtual | EOS4.1

Carbon footprint and reduction initiatives in a French geosciences laboratory 

Laurent Jeanneau, Emilie Jardé, Anne-Laure Argentin, Annick Battais, Thomas Bernard, Alexandre Coche, Marion Fournereau, Frédérique Moreau, and Laure Guerit

The impact of our productivist societies on our environment is now clearly demonstrated. It is illustrated in particular by the alteration of biogeochemical flows, the erosion of biodiversity, the chemical pollution of environments, the anthropisation of soils, the alteration of the water cycle, the acidification of the oceans and climate change.

As higher education and research staff working at the interface between science and society, we are aware of the need for an environmental transition that can only be achieved by reducing our greenhouse gas emissions and our environmental impact. We do not believe that the content of our research justifies any form of exemption and are aware of the benefits of being exemplary. As a research lab, we are committed to participating in limiting the increase in the Earth's average temperature, ideally targeted at less than 1.5°C compared to the pre-industrial period. This objective requires achieving carbon neutrality by 2050.

From 2021 the Sustainable Development & Social Responsibility working group of the research laboratory “Géosciences Rennes” has been created (i) to determine the C footprint by using GES1.5 (Research Consortium labo1.5), (ii) to communicate and raising staff awareness of the climate emergency, (iii) to propose indicators for reducing the carbon footprint, (iv) to convey a message to the supervisory authorities to work on the various reduction items.

The calculated C footprint includes heating of buildings, electricity, purchase of goods and services, scientific missions and commutes. Between 2019 and 2021, the C footprint was 879, 520 and 708 T CO2eq, which corresponds to 5.8, 3.6 and 5.1 T CO2eq/person. The purchase of goods and services was the main item, representing 48 ± 8 % (mean ± SD) of the C footprint. Scientific missions represented 14 ± 9 % of the C footprint. Sanitary restrictions due to the covid pandemy induced a drastic decrease of the C footprint of scientific missions from 220 T CO2eq in 2019 to 43 T CO2eq in 2020.

Thanks to the GES1.5 toolkit, it is possible to identify the main emission items for a given laboratory and to design and quantify specific actions to collectively reduce the C footprint. These data were the corner stone of collaborative workshops to invent our low-carbon laboratory. This presentation will feature the data and the process of collective decision in “Géosciences Rennes” laboratory. These results highlight that achieving the European Union targets will require a rethinking of the way we do science. 

How to cite: Jeanneau, L., Jardé, E., Argentin, A.-L., Battais, A., Bernard, T., Coche, A., Fournereau, M., Moreau, F., and Guerit, L.: Carbon footprint and reduction initiatives in a French geosciences laboratory, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14085, https://doi.org/10.5194/egusphere-egu23-14085, 2023.

EGU23-14481 | Orals | EOS4.1

Project VECTOR – researching challenges to mining in Europe through a robust ethics structure. 

Chris Stockey, Sarah Gordon, Rose Clarke, and Emily Lewis and the VECTOR Partnership

VECTOR (Vectors to Accessible Critical Raw Material Resources in Sedimentary Basins) is an EU Horizon and UKRI co-funded research project assessing the social, technical, and environmental challenges to mining critical raw materials in Europe. Our commitment to geoethics is informed by the diverse partnership’s research expertise and our social science research. We will incorporate these learnings into all subsequent research and outreach programmes to promote good practice. Our dedicated ethics structure ensures that we put this commitment into practice. This approach to project ethics is a first for a Horizon Europe project.

Plans for decarbonisation presented in the EU Green Deal include achieving Net Zero by 2050 and reducing net greenhouse gas emissions by at least 55% by 2030 (compared to 1990 levels). Meeting the supply of renewable energy needed to achieve these goals requires a sharp increase in production, and a more responsible use, of critical raw materials. Recycling alone cannot meet the projected demand. Sourcing raw materials from inside the EU, where suitable environmental, social, and political regulations could be implemented, may be instrumental in securing an ethical provision of metals. However, mineral projects face complex social, environmental, and technical challenges in the EU. VECTOR will explore these challenges through social- and geoscience research, integrating the results of both research streams into easy-to-understand resources.

The VECTOR consortium is committed to ensuring the highest level of ethical standards during the project, with respect to both conduct and outputs. To put this commitment into practice, the VECTOR consortium has appointed an Ethics Advisor, responsible for advising the project on ethical matters and Chairing an Independent Ethics Committee, which will bring subject matter expertise to ethical deliberations. The Ethics Advisor and the Independent Ethics Committee sit within an ethics governance framework that interacts with, but is independent of, the Project governance framework. This ensures that ethical matters arising during the course of the Project are considered by expert, neutral third parties who are not otherwise directly invested in the Project, and that their advice is given due weight in Project decision making processes and practically implemented. This approach is a first for a Horizon Europe project, and one we hope will set the bar for strong ethical project management across the Horizon universe.

This will also be informed by our social science research to understand how stakeholders balance the ethical, social, economic, political, and environmental consequences of sourcing critical raw materials. The aim is to understand how levels of social acceptance influence attitudes, decisions and policy acceptance. Insights gained from this will inform good practice standards in our other research and be used to develop outreach tools targeting all stakeholder groups, informing their future decision making. These include policy makers and the much-overlooked public, as well as continued professional development pathways for geoscientists.

Taken together, our ethics structure and social science research provide a robust geoethics framework that will evolve with our new understandings and inform our work to investigate a socio-environmentally sustainable supply of raw materials.

How to cite: Stockey, C., Gordon, S., Clarke, R., and Lewis, E. and the VECTOR Partnership: Project VECTOR – researching challenges to mining in Europe through a robust ethics structure., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14481, https://doi.org/10.5194/egusphere-egu23-14481, 2023.

EGU23-14915 | ECS | Posters on site | EOS4.1

Is maximizing spatial resolution worth the computational cost? 

Yomna Eid and Edzer Pebesma

Link: https://docs.google.com/document/d/15788dfGPL5ehDaDsO7BsOKoGk3Bk7g2epKQ58HiYZVM/edit

The core of the modern data revolution is data centers: “the central nervous system of the 21st century,” [1] housing networking and storage equipment, and servers that enable services such as cloud computing. They consume increasing quantities of energy not only to run their operations, but also to cool down their servers. With advances in cloud computing and the growth of Internet services use, data centres are estimated to have the fastest growing carbon footprint from across the whole ICT sector.

Although the opportunities and risks of Big Data are often discussed in the geosciences, most of the literature and initiatives surprisingly neglect a crucial risk for sustainable development: the fact that the data revolution hampers sustainable development because of its environmental footprint. Therefore, the ability to quantify and project data centre energy use is a key energy and climate policy priority.

Remote sensing products present one of the highest storage-capacity demands, with imagery archives spanning petabytes. High- and very high-resolution remote sensing imagery has emerged as an important source of data for various geoscientific analysis, most of which are highly computationally taxing. With this trend in increasing spatial and temporal resolution, a crucial question remains - is the accuracy and overall quality of analysis results significantly impacted by substituting the standard high-resolution product with a less computationally-intensive, coarser-resolution one?

Emerging products such as the World Settlement Footprint [2] and Dynamic World [3] land use land cover maps, which are produced at very high temporal resolution (5 day) and spatial resolution (10 m). A generally accepted attitude is that developing products at higher resolutions is a legitimate scientific goal. However, the interest is often not which 10 m pixel changes land use and when exactly this happens, but rather how many pixels change land use over a larger area (a country, or basin) and over a larger time period (e.g. by year over a decade). For a few high resolution products we evaluate and report how such aggregated target quantities computed from lower spatial and temporal resolution data change the quality (accuracy) of the final product, and which resolutions still seem acceptable.

[1] Lucivero, F. Big Data, Big Waste? A Reflection on the Environmental Sustainability of Big Data Initiatives. Sci Eng Ethics 26, 1009–1030 (2020). https://doi.org/10.1007/s11948-019-00171-7

[2] Marconcini, M., Metz-Marconcini, A., Üreyen, S. et al. Outlining where humans live, the World Settlement Footprint 2015. Sci Data 7, 242 (2020). https://doi.org/10.1038/s41597-020-00580-5

[3] Brown, C.F., Brumby, S.P., Guzder-Williams, B. et al. Dynamic World, Near real-time global 10 m land use land cover mapping. Sci Data 9, 251 (2022). https://doi.org/10.1038/s41597-022-01307-4

How to cite: Eid, Y. and Pebesma, E.: Is maximizing spatial resolution worth the computational cost?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14915, https://doi.org/10.5194/egusphere-egu23-14915, 2023.

EGU23-15941 | Orals | EOS4.1 | Highlight

The UK Climate Resilience Programme (2019-2023) 

Suraje Dessai, Kate Lonsdale, Jason Lowe, Rachel Harcourt, and Peter Walton

Even with the successful implementation of the Paris agreement, a certain amount of climate change is now unavoidable over the next few decades and high warming levels by the end of the century cannot be ruled out. Therefore, urgent action is needed to build resilience and accelerate adaptation to climate variability and change. Informing the extensive range of actions needed to manage climate risks, reduce damage without exacerbating existing inequalities, and realise emerging opportunities, is a critical scientific and societal challenge. The UK has been at the forefront of climate adaptation policy with the Climate Change Act 2008 requiring the UK Government to conduct a five-yearly Climate Change Risk Assessment (CCRA) and National Adaptation Programme. Another important recent driver amongst UK organisations has been compliance with the Task Force on Climate-Related Financial Disclosures. The UK Climate Resilience (UKCR) Programme emerged as a response to these policy and societal needs. It aims to enhance the UK’s resilience to climate variability and change through frontier interdisciplinary research and innovation on climate risk, adaptation and services, working with stakeholders and end-users to ensure the research is useful and usable.

The UK Climate Resilience Programme, led by UK Research and Innovation and the UK Met Office and running from 2019 to 2023, has funded over 50 projects worth £19 million. It is part of the Strategic Priorities Fund initiative which provides research funding to develop strategically important research for the national government. Topics central to the programme’s research agenda have included improved characterisation and quantification of climate risks, enhanced understanding of the management of climate risks, and the development and delivery of climate services. Amongst its achievements, the programme has: developed a set of future UK socio-economic scenarios to be used alongside climate scenarios, delivered a step change in climate change risk assessment capability, and produced a roadmap for the development and implementation of UK climate services. It has funded arts and community based projects and pioneered an embedded researchers scheme in which the researcher collaborates with a host organisation to address their real world needs. The programme has also developed a more coherent community of climate resilience researchers and practitioners in the UK.

In this talk we will provide an overview of the programme, focusing on the nexus between UKCR–funded research, and UK policy and practice. For example, we will consider how the national CCRA process shaped the programme’s research agenda while at the same time the availability of research sets the parameters of risk assessments. We will also provide examples of co-production undertaken by researchers and practitioners and comment on what can be achieved in terms of societal resilience when there is collaboration on shared objectives. This programme is unique in dedicating significant time, funding and other resources to researching national resilience while working in close partnership with the national government. We anticipate that our learnings from this process will be of interest to other researchers, as well as policy makers and practitioners who work with researchers on climate resilience issues.

How to cite: Dessai, S., Lonsdale, K., Lowe, J., Harcourt, R., and Walton, P.: The UK Climate Resilience Programme (2019-2023), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15941, https://doi.org/10.5194/egusphere-egu23-15941, 2023.

EGU23-15959 | Posters on site | EOS4.1 | Highlight

Changing the narrative: the hidden histories of British colonial mineral exploitation in Africa 

Dr Munira Raji, Dr Rebecca Williams, Dr Anya Lawrence, Dr Nicholas Evans, Professor Trevor Burnard, Dr M. Satish Kumar, Keely Mills, Steven Rogers, Catharine Souch, George Jameson, Jacqui Houghton, and Natasha Dowey

At the height of colonial Europe, during the late 18th century, many of the principles, theories, laws and practices that shape the (Western) academic discipline of Earth Science were established. However, during this imperial production of knowledge, there was little reference to or acknowledgement of any pre-existing geological knowledge. The legacy of colonialism is perpetuated through many modern Earth Science practices and education activities, and the influence of this legacy adds to the perception of Earth Science as a white, western-dominated subject and the erasure and dismissal of other geological knowledge. This project explores the unacknowledged local geological knowledge and labour upon which the foundational institutions of Earth Science are built and how this legacy creates modern-day exploitation, unethical behaviour and inequity in our discipline. 

 

We uncover some of the hidden histories of colonial mineral exploitation, including the role of British geologists and geological institutions in expanding colonial rule in Africa and how local geological knowledge and local guides underpinned the activities of the colonial geological surveys. British mineral exploitation in Africa started in the seventeenth century with a series of expeditions by pioneer British geologists and prospectors into South Africa's interior to make preliminary observations and geological surveys for minerals. More expeditions to other parts of Africa followed in the eighteenth century. During the late eighteenth century, many of the principles, theories, laws and practices that shaped the academic discipline of Earth Science were established in parallel to colonial expansion. The British Empire sustained a programme of exploratory geological surveys and activities directly linked with mapping the geological features to locate and discover economic mineral resources to fuel the British economy and industrialise the British Empire. Exploitable deposits of coal, copper, iron and limestone's essential smelting flux were vital for the long-term development of steamship lines, railways, and industry. 

 

At the end of the First World War, the British government promoted and intensified geological surveys in several British Empire territories – Uganda, Sierra Leone and Nigeria in 1918, Tanzania in 1925 and Kenya in 1933. Some pioneer British geologists were heralded for their pioneering work and credited with the discovery of economically significant minerals in Africa. Our archival investigation reveals many of these mineral resources were already used and mined locally and that local knowledge underpinned these resource 'discoveries' and local people were used as field assistants, guides, carriers, labourers, and camp guides. These pioneer geologists relied on the colonial structure to obtain information from natives central to fieldwork, mineral investigation, and discoveries. Still, history has omitted the contributions of the natives involved in these mineral discoveries and the acknowledgement of any local geological knowledge. Perhaps it is time to change the narrative from one of discovery to one of exploitation. As a discipline, by reckoning with the colonial legacy of our past, we can seek to normalise working with local knowledge and knowledge outside the boundaries of (western) Earth Science, leading to ethical,  equitable, interdisciplinary work, better preparing the discipline for current global challenges.

How to cite: Raji, D. M., Williams, D. R., Lawrence, D. A., Evans, D. N., Burnard, P. T., Kumar, D. M. S., Mills, K., Rogers, S., Souch, C., Jameson, G., Houghton, J., and Dowey, N.: Changing the narrative: the hidden histories of British colonial mineral exploitation in Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15959, https://doi.org/10.5194/egusphere-egu23-15959, 2023.

EGU23-16302 | Orals | EOS4.1 | Highlight

An Ethical Framework for Climate Intervention Research and Potential Scaling 

Billy Williams, Brooks Hanson, Raj Pandya, Janice LaChance, and Mark Shimamoto

Climate change is a global threat. As such, scientific and technology organizations and funders are increasingly devoting attention and resources to climate intervention research and, in some cases, already pursuing large-scale testing. Climate intervention measures include carbon dioxide removal and solar radiation management. The U.S. National Academy of Sciences and many other authoritative bodies have called for "a code of conduct" and governance structure to guide the research, potential scaling and possible deployment of these intervention measures.  This presentation will discuss a global initiative facilitated by AGU to help establish and gain support for an ethical framework to help guide such efforts, and to include various practical, ethical and governance considerations of potential climate intervention technologies to be considered before deciding potential scaled deployment of such measures – including climate justice considerations and representation.  Preliminary ethical framework modules and global engagement processes currently underway will be discussed.

How to cite: Williams, B., Hanson, B., Pandya, R., LaChance, J., and Shimamoto, M.: An Ethical Framework for Climate Intervention Research and Potential Scaling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16302, https://doi.org/10.5194/egusphere-egu23-16302, 2023.

EGU23-16734 | Orals | EOS4.1

Impact of the COVID19 crisis on changes in business travel and the associated carbon footprint. Case study of a French scientific research institute. 

Christophe Peugeot, Grolleau Dany, Play Caroline, Sultan Benjamin, Hernandez Valeria, Janicot Serge, and Tramblay Yves

The French National Research Institute for Sustainable Development (IRD) is a multidisciplinary academic organisation working in partnership with countries in the Mediterranean and intertropical zone. Through sustainability science, IRD is committed to achieving the Sustainable Development Goals. Because of its missions, the IRD has a particular footprint linked to the activities of its agents (2100 employees in 2020) and partners, who travel between France and the rest of the world.

The COVID19 health crisis has forced changes in work habits. This study aims to analyze the impact of these changes on carbon emissions. All business trips of IRD employees and partners in the period 2017-2022 were collected in an anonymized database (aboout 67,000 entries), which describes trips, mode of transportation, reasons for travel, and traveler status.

The annual number of trips dropped sharply during the health crisis, from an average of 14,000/year in 2017-2019 to less than 6,000 in 2022 (-60%). Associated carbon emissions dropped by 70%. Starting in 2021, the number of trips increased to about 90% of pre-covid levels in 2022. However, while the share of air travel in total travel has decreased slightly in 2022 compared to 2017-2019, the share of car travel has increased sharply over the past three years, at the expense of train travel, which remains less used than before COVID. On a finer scale, the share of each mode of transport (and therefore the associated footprint) differs markedly according to the regions in which the research teams work, depending on the type of activity and the modes of transport available (e.g. rail travel mainly in Europe, field campaigns mainly by car).

The analysis highlights that the few trips authorized in 2020 and 2021 were primarily for overseas field activities or mobilities, to and from France. These activities, which cannot be replaced by videoconferencing and which constitute the core of IRD's activity, have been prioritized. The widespread use of videoconferencing has reduced the need for travel, especially for meetings and conferences. This is likely accompanied by an increase in virtual meetings, the associated footprint of which is not assessed here.

Traveling less, using videoconferencing when possible, or pooling several objectives for a single trip are trends that seem to emerge from our analysis. It is interesting to note that they are consistent with the actions proposed by research teams engaged in footprint reduction strategies, as highlighted for example by the serious game "Ma Terre en 180'" or the national survey of the Labo1point5 group.

Our analysis, with only one year without travel restrictions (2022), must be consolidated over a longer period (at least 3 years) to assess the sustainability of practice changes and their impact on IRD's carbon footprint. These results will serve as guidelines to define the necessary actions to reduce the environmental footprint of IRD research activities.

How to cite: Peugeot, C., Dany, G., Caroline, P., Benjamin, S., Valeria, H., Serge, J., and Yves, T.: Impact of the COVID19 crisis on changes in business travel and the associated carbon footprint. Case study of a French scientific research institute., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16734, https://doi.org/10.5194/egusphere-egu23-16734, 2023.

We desire to know out of different motivations. According to Aristotle, scientists can feel happy or eudaimon when they fulfill the final cause of humans, reasoning, by providing knowledge. Freud argued that infants start to learn in order to distinguish between conditions that cause them pain or pleasure. We want to increase chances of achieving desired outcomes and avoiding undesired outcomes of our decisions by understanding causalities between events and predicting future events. In Geoscientific contexts, we may want to understand nature in order to satisfy different desires such as physical and psychological comforts, ethical dignity and continuation of existence, which are inseparable from but also conflict often against each other. We seek optimal decisions by means of the Geoscientific knowledge amidst the conflicting desires and natural conditions that hamper the desires.

All formations in the universe and all our perceptions are impermanent. Buddhism views that the course of life in which one is born, ages, gets ill and dies is suffering, if one clings to satisfactions, existence or non-existence as they are impermanent. A human being is seen in Buddhism as an ever-changing flux comprised of body (rupa in Pali language), senses (vedana), perceptions (sanna), volitions (sankhara) and consciousness (vinnana), or the five aggregates (khandha). Lasting peacefulness can be experienced when one understands the impermanence of its five aggregates, or selflessness (sunnata), which is a goal of Buddhist practices.

From this Buddhist perspective, satisfactions of material needs provided by Geoscience do not last permanently. Geoscience may help humans satisfy their basic needs, but the standards of basic needs seem to be ever-growing, influenced often by materialism which overlooks spiritual sources of happiness and technocentric hopes for sustainability in the future. According to Buddhism, our experiences and actions (kamma) condition our perceptions, volitions and habits, and reifying them as constant or substantial leads us to assume that certain desires ‘ought’ to be met as basic living standards. However, such standards are subjective judgements that cannot be justified by factual propositions in ‘is’ forms.

It can be satisfying for scientists to perform their professional tasks of providing knowledge required for fulfilling the human needs. However, epistemic and aleatory uncertainties in Geoscience can frustrate their desire to know. Geoscientists may suffer from the frustration, if they cling to their tasks and desires, failing to see satisfactions as impermanent and uncertainties as natural processes.

It is important to note that Buddhism does not compel dogmatically ascetic life styles or nihilistic worldviews but suggests ways to cease suffering. The Threefold Training (ethics, mindfulness and wisdom), the practice methods of Buddhism, can be applied in pursuing Geoscience as opportunities to experience lasting peacefulness. Scientists can create peaceful conditions by helping others with their knowledge, and let go of their reification and desires through mindfulness and the Buddhist ontology. Studying human desires and providing honest information about uncertainties and physical boundaries of satisfying the desires would be also parts of the practice.

How to cite: Jung, H.: Buddhist thoughts on frustration of the desire the know in Geoscience, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17116, https://doi.org/10.5194/egusphere-egu23-17116, 2023.

EGU23-17583 | Orals | EOS4.1

Inform international institutions for interdisciplinary development strategies linking nutrition enhancement and climate change adaptation 

Giulia Galluccio, Chiara Trozzo, Monia Santini, Marta Antonelli, and Océane Espin

Climate change and malnutrition, that includes undernutrition as well as micronutrient deficiency and overweight, are among the greatest issues in the 21st century. Acting in synergy, each of these dynamics aggravates the effects of the other, creating complex and compounding impacts that increase particularly the vulnerability of the poorest people. This so-called climate and nutrition nexus can be broadly described as the fact that climate change poses a serious threat to global nutrition security, while current food systems are contributing significantly to this warming dynamic and malnutrition is reducing people’s ability to cope with the induced changes. Therefore, climate information and science are crucial to inform both international funding institutions (especially their investment portfolios) and local decision-makers in the design and selection of comprehensive, effective and innovative strategies and actions to adapt and cope with climate change and therefore advance sustainable development at all scales.

Regarding this topic, we carried out a consultancy project funded by the ASAP II programme of the International Fund for Agricultural Development (IFAD) to inform its investment portfolio on the design and implementation of interdisciplinary development strategies linking nutrition enhancement and climate change adaptation. We reviewed and analysed 7 selected IFAD ‘climate related and nutrition-sensitive projects’ in Latin America and the Caribbean. The identification of best practices and lessons learned to be cultivated, scaled-up and even mainstreamed in future projects will encourage the sustainable transformation of the food systems, increase the climate resilience of the population and fight inequalities in the region.

Our work was articulated in three stages. Firstly, a wide literature review of scientific articles and other relevant documents published to date on the climate and nutrition nexus has been carried out, as well as a review of all related project documentation. This primary data collection and analysis has been complemented by conducting semi-structured interviews with key stakeholders from the projects. As part of this study, a two-day peer-to-peer sharing event was organised to assess the know-how accumulated by the participants and aimed to create an environment conducive to the exchange of knowledge and experiences, as well as to present and validate preliminary research results.

Our results are compiled in a practical guidebook that focuses on 9 main themes. The analysis allowed us to identify adaptation knowledge and solutions coming directly from the field and tested during the projects. The added value of considering the climate and nutrition nexus is to point out the numerous co-benefits of actions and practices which can both contribute to climate change mitigation and adaptation, and to the promotion of sustainable agricultural systems and healthy diets. The majority of the solutions identified concern: the consideration of the most vulnerable communities and populations, and in particular the empowerment of women, youth and indigenous people; governance and organisation from the global scale with South-South cooperation to the household level; and finally, the use of information from both traditional knowledge and more technical studies, as well as the implementation of climate-smart and nutrition-sensitive agriculture practices.

How to cite: Galluccio, G., Trozzo, C., Santini, M., Antonelli, M., and Espin, O.: Inform international institutions for interdisciplinary development strategies linking nutrition enhancement and climate change adaptation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17583, https://doi.org/10.5194/egusphere-egu23-17583, 2023.

Geomorphological mapping is one of the primary research methods used to collect data on glacial landforms and reconstruct glaciological processes. The most common approach is a combination of field-based and remote mapping using data obtained from various sensors. However, one of the crucial methodical problems is collecting remote sensing data in the appropriate spatial resolution for the analyzed landform, which directly affects the data collection time and costs. This study aims to find the optimal resolution of digital elevation models (DEMs) to map subtle glacial landforms: kame terraces, eskers, flutes, and push moraine. Such landforms contain valuable information about the glacial process–form relationships, however, are often too subtle to be recognized on satellite data, and therefore more detailed data (e.g., UAV-based) are required. By “optimal”, we mean the resolution high enough to enable recognition of the landforms mentioned above, and at the same time, as low as possible to minimize the time spent on data collection during the fieldwork.

To find out the optimal resolution, we used detailed (0.02 – 0.04 m ground sampling distance [GSD]) DEMs of the glacier forelands in Iceland (Kvíárjökull, Fjallsjökull and Svinafellsjökull), created based high-resolution images from an unmanned aerial vehicle (UAV). The DEMs were resampled to 0.05, 0.10, 0.15, 0.20, 0.30, 0.40, 0.50, 1.00 and 2.00 m GSD and selected glacial landforms were mapped independently by two operators and cross-checked. The results indicate that 2.0 m resolution is insufficient to properly recognize landforms such as pushed moraines or flutes; however, it can be sufficient to detect kame terraces and major glacifluvial channels. For general mapping of locations of forms such as annual pushed moraines or fluting, the 0.5 m resolution is required. However, to obtain geomorphometric characteristics of the landforms (e.g., height, width, volume) resolution between 0.1 and 0.2 m is necessary. Finer resolution (better than 0.05 m GSD) does not increase the ability to detect landforms or better characterize their geometric properties; however, in some cases might be useful to obtain information about clast characteristics. The experiment proved that decimeter-scale spatial resolution is sufficient for mapping of some geomorphological forms (annual pushed moraines, flutes), which allows for planning UAV missions at a higher elevation above the ground and, therefore, minmizing the duration of field surveys. Moreover, some of the more prominent landforms (e.g., kame terraces, larger moraines) can be successfully detected from aerial or satellite-based DEMs (e.g. freely available ArcticDEM) with a resolution of 2.00 m, the use of which reduces the costs of field research to a minimum.

This research was funded by the National Science Centre, Poland, Grant Number 2019/35/B/ST10/03928.

How to cite: Śledź, S. and Ewertowski, M.: Optimal resolution of UAV-based digital elevation models (DEMs) for mapping of selected subtle glacial landforms, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-151, https://doi.org/10.5194/egusphere-egu23-151, 2023.

EGU23-3292 | Posters on site | GI6.1

CO2 concentration and stable isotope surveys in the ambient air of populated areas of La Palma (Canary Islands) by means of mobile Delta Ray measurements using an electrical car 

Nemesio M. Pérez, María Asensio-Ramos, José Barrancos, Eleazar Padrón, Gladys V. Melián, Fátima Rodríguez, Germán D. Padilla, Violeta T. Albertos, Pedro A. Hernández, Antonio J. Álvarez Díaz, Héctor de los Ríos Díaz, David Afonso Falcón, and Juan Cutillas

Anomalous CO2 degassing of volcanic origin was observed by the end of November 2021 in the neighborhoods of La Bombilla and Puerto Naos, located in the western flank of La Palma, about 5 km distance southwestern of the 2021 Tajogaite eruption vents (Hernández et al., 2021). In this study zone, continuous monitoring of CO2 concentration in the outdoors ambient air at 200 cm from the surface has reached a daily average of maximum and mean values about 28,000 and 10,000 ppm, respectively. We started recently to perform CO2 concentration and stable isotope surveys in the outdoors ambient air of Puerto Naos at 140 cm from the surface by means of a Delta Ray analyzer installed in an electrical car which was driving through the streets of Puerto Naos. This instrument is a high performance, mid-infrared laser-based, isotope ratio infrared spectrometer (IRIS) which offers the possibility of performing simultaneous determination of δ13C and δ18O in CO2 at ambient concentrations with a precision as low as 0.05‰. One major advantage of IRIS techniques with respect to more traditional ones (e.g., isotopic ratio mass spectrometry -IRMS-) is the possibility to perform (semi)continuous measurements at high temporal resolution. Since October 2022, seven surveys have been performed at Puerto Naos making up a total of about 600 measurements. The observed CO2 concentrations and the δ13C-CO2 values in the outdoors ambient air ranged from 420 to 3,500 ppm and from -9.0 to -3.2 ‰ vs. VPDB, respectively. Survey data analysis showed a good spatial correlation between relatively high CO2 concentrations with δ13C-CO2 values less 13C-depleted (i.e., volcanic CO2). These observations highlight that stable isotope surveys allow to evaluate the impact of volcanic degassing on the air CO2 concentration and provide valuable results to identify the volcanic CO2 gas hazard zones.

Hernández, P. A., Padrón, E., Melián, G. V., Pérez, N. M., Padilla, G., Asensio-Ramos, M., Di Nardo, D., Barrancos, J., Pacheco, J. M., and Smit, M.: Gas hazard assessment at Puerto Naos and La Bombilla inhabited areas, Cumbre Vieja volcano, La Palma, Canary Islands, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7705, https://doi.org/10.5194/egusphere-egu22-7705, 2022.

How to cite: Pérez, N. M., Asensio-Ramos, M., Barrancos, J., Padrón, E., Melián, G. V., Rodríguez, F., Padilla, G. D., Albertos, V. T., Hernández, P. A., Álvarez Díaz, A. J., de los Ríos Díaz, H., Afonso Falcón, D., and Cutillas, J.: CO2 concentration and stable isotope surveys in the ambient air of populated areas of La Palma (Canary Islands) by means of mobile Delta Ray measurements using an electrical car, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3292, https://doi.org/10.5194/egusphere-egu23-3292, 2023.

EGU23-3620 | ECS | Posters on site | GI6.1

SO2 emissions during the post-eruptive phase of the Tajogaite eruption (La Palma, Canary Islands) by means of ground-based miniDOAS measurements in transverse mode using a car and UAV 

Oscar Rodríguez, José Barrancos, Juan Cutillas, Victor Ortega, Pedro A. Hernández, Iván Cabrera, and Nemesio M. Pérez

Throughout the 85 days that lasted the Tajogaite eruption at Cumbre Vieja volcano (La Palma, Canary Islands, Spain), observations of SO2 emissions were made using ground-based instruments, in transverse mode, static scanners and on-board drones, as well as by numerous satellite instruments. The initial estimates of the total SO2 emission from the eruption were 2.4 Mt from TROPOMI and 1.2 Mt from the traverse data. These measurements formed part of the official monitoring effort, providing insights into the eruption’s evolution and informing the civil defence response throughout the eruption (Hayer C. et al., 2022; Albertos V. T. et al., 2022). Once the Tajogaite eruption was over, we continued performing a SO2 monitoring release to the atmosphere by the Tajogaite volcanic vent since the low ambient concentrations of SO2 make it an ideal volcanic gas monitoring candidate even during the post-eruptive phase. SO2 measurements had been carried out a using a car-mounted and UAV-mounted ground-based miniDOAS measurements throughout this post-eruptive phase. About 80 measurements of SO2 emission rates were performed from December 15, 2021 to December 17, 2022. The standard deviation of the estimated values obtained daily was ~ 20%. The range of estimated SO2 emission values has been from 670 to 17 tons per day, observing a clear decreasing trend of SO2 emissions during the post-eruptive phase. During the first month of the post-eruptive phase, it was observed that the average value of the estimated SO2 emission was about 219 tons/day, while it dropped to 107 tons/day during the second and third month after the end of the Tajogaite eruption. This average value continued decreasing during the fourth month of the post-eruptive phase, about 67 tons/day, and recently measurements provide an average SO2 emission value of 13 tons/day. These relatively low observed SO2 emissions during the post eruptive of the Tajogaite eruption phase seems to be clearly related to shallow magma cooling processes within the Tajogaite volcanic edificie.

Hayer, C., Barrancos, J., Burton, M., Rodríguez, F., Esse, B., Hernández, P., Melián, G., Padrón, E., Asensio-Ramos, M., and Pérez, N.: From up above to down below: Comparison of satellite- and ground-based observations of SO2 emissions from the 2021 eruption of Cumbre Vieja, La Palma, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12201, https://doi.org/10.5194/egusphere-egu22-12201, 2022.

Albertos, V. T., Recio, G., Alonso, M., Amonte, C., Rodríguez, F., Rodríguez, C., Pitti, L., Leal, V., Cervigón, G., González, J., Przeor, M., Santana-León, J. M., Barrancos, J., Hernández, P. A., Padilla, G. D., Melián, G. V., Padrón, E., Asensio-Ramos, M., and Pérez, N. M.: Sulphur dioxide (SO2) emissions by means of miniDOAS measurements during the 2021 eruption of Cumbre Vieja volcano, La Palma, Canary Islands, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5603, https://doi.org/10.5194/egusphere-egu22-5603, 2022.

How to cite: Rodríguez, O., Barrancos, J., Cutillas, J., Ortega, V., Hernández, P. A., Cabrera, I., and Pérez, N. M.: SO2 emissions during the post-eruptive phase of the Tajogaite eruption (La Palma, Canary Islands) by means of ground-based miniDOAS measurements in transverse mode using a car and UAV, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3620, https://doi.org/10.5194/egusphere-egu23-3620, 2023.

EGU23-3819 | Posters virtual | GI6.1

Using tunable diode laser (TDL) system in urban environments to measure anomalous CO2 concentrations: the case of Puerto Naos, La Palma, Canary Islands 

José Barrancos, Germán D. Padilla, Gladys V. Melián, Fátima Rodríguez, María Asensio-Ramos, Eleazar Padrón, Pedro A. Hernández, Jon Vilches Sarasate, and Nemesio M. Pérez

Carbon dioxide (CO2) is a colourless and odourless gas. It is non-flammable, chemically non-reactive and 1.5 times as heavy as air; therefore, may accumulate at low elevations. CO2 is a toxic gas at high concentration, as well as an asphyxiant gas (due to reduction in oxygen). Irritation of the eyes, nose and throat occurs only at high concentrations. Since the Tajogaite eruption ended on December 13, 2021, high concentrations of CO2 up to 20% (200.000 ppmv) have been observed inside of buildings of the neighborhoods of La Bombilla and Puerto Naos (La Palma, Canary Islands), which are located about 5 km distance from the Tajogaite eruption vent. Anomalous concentrations of CO2 are manily detected in the ground-floor and basement of the buildings in Puerto Naos, and the distribution of relatively high CO2 concentrations  is not homogeneous or uniform throughout the Puerto Naos area (Hernández P.A. et al, 2022).

The purpose of this study was to use the Tunable Laser Diode (TDL) absorption spectroscopy method to monitor the indoor CO2 concentration of the ground-floor of one of the buildings of Puerto Naos. A CO2-TDL was installed on 9 January 2022 and continues measuring the CO2 concentration along an optical path of about 6 meters. During the period January-March 2022, daily averages of CO2 concentrations from fifteen-minute data ranged from 5000 to 25000 ppmv reaching values up to 40000 ppmv (4%). Over time, a clear decreasing trend of the indoor CO2 concentration has been observed at this observation site and the daily CO2 averages from fifteen-minute data during the last 3 months (October-December 2022) ranged from 1000 to 2500 ppmv. This clear decreasing trend over time has not been observed at other observation sites where the concentration of CO2 inside buildings is being monitored. This observation indicates the complexity of the problem and the need to install a dense network of sensors to monitor CO2 for civil protection purposes.

 

Hernández, P. A., Padrón, E., Melián, G. V., Pérez, N. M., Padilla, G., Asensio-Ramos, M., Di Nardo, D., Barrancos, J., Pacheco, J. M., and Smit, M.: Gas hazard assessment at Puerto Naos and La Bombilla inhabited areas, Cumbre Vieja volcano, La Palma, Canary Islands, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7705, https://doi.org/10.5194/egusphere-egu22-7705, 2022.

How to cite: Barrancos, J., Padilla, G. D., Melián, G. V., Rodríguez, F., Asensio-Ramos, M., Padrón, E., Hernández, P. A., Vilches Sarasate, J., and Pérez, N. M.: Using tunable diode laser (TDL) system in urban environments to measure anomalous CO2 concentrations: the case of Puerto Naos, La Palma, Canary Islands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3819, https://doi.org/10.5194/egusphere-egu23-3819, 2023.

EGU23-3834 | Posters on site | GI6.1

Modeling outdoor dispersion of CO2 at Puerto Naos (La Palma, Canary Islands) 

Luca D Auria, Alba Santos, Pedro A. Hernández, Gladys V. Melián, Antonio J. Álvarez Díaz, María Asensio-Ramos, Alexis M. González Pérez, and Nemesio M. Pérez

The 2021 Tajogaite eruption in Cumbre Vieja volcano (La Palma, Canary Islands), which started on Sep. 19, 2021, and lasted 85 days, caused extensive damages because of the lava flows and ash fall. However, since the middle of Nov. 2021, some areas located about 5 km SW of the eruptive center started to be affected by intense diffuse CO2 emission. Among them are the urban centers of La Bombilla and Puerto Naos (Hernández et al., 2022). These emissions prevented the population of these two centers from returning to their houses because of high  concentrations of CO2 in indoor and outdoor environments.

In this work, we model the CO2 dispersion process in Puerto Naos to obtain hazard maps with the maximum CO2 concentrations which can be reached in the town in the outdoor environment. To achieve these results, we combined field observations with numerical modelling. Field surveys were realized in low wind conditions, measuring the CO2 concentration with portable sensors  at 15 and 150 cm from the ground at measurement points spaced approximately 10 m from each other along the streets of Puerto Naos.

We realized numerical modelling using the software TWODEE-2, a code for modeling the dispersion of heavy gases based on the solution of shallow water equations (Folch et al., 2009). For this purpose, we used a detailed digital topographic model, including the edifices of Puerto Naos. Using a trial-and-error approach, we determined the gas emission rates from a set of discrete source points in no-wind conditions. Subsequently, we repeated the numerical modelling, keeping the same sources and simulating all the realistic wind conditions in terms of direction and intensity. For each simulation, we determined the maximum CO2 concentration at different elevations from the ground. This allowed obtaining a hazard map with the maximum CO2 outdoor concentrations for each part of the town

The main results highlight that the outdoor environment is affected by a dense layer of CO2, whose flow is strongly conditioned by the urban infrastructures. Furthermore, we evidenced how even light winds can change the gas concentration pattern radically in a few minutes, evidencing the possibility of sudden changes in the CO2 concentration outdoors with no warning.

Folch A., Costa A., Hankin R.K.S., 2009. TWODEE-2: A shallow layer model for dense gas dispersion on complex topography, Comput. Geosci., doi:10.1016/j.cageo.2007.12.017

Hernández, P. A., Padrón, E., Melián, G. V., Pérez, N. M., Padilla, G., Asensio-Ramos, M., Di Nardo, D., Barrancos, J., Pacheco, J. M., and Smit, M.: Gas hazard assessment at Puerto Naos and La Bombilla inhabited areas, Cumbre Vieja volcano, La Palma, Canary Islands, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7705, https://doi.org/10.5194/egusphere-egu22-7705, 2022.

How to cite: D Auria, L., Santos, A., Hernández, P. A., Melián, G. V., Álvarez Díaz, A. J., Asensio-Ramos, M., González Pérez, A. M., and Pérez, N. M.: Modeling outdoor dispersion of CO2 at Puerto Naos (La Palma, Canary Islands), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3834, https://doi.org/10.5194/egusphere-egu23-3834, 2023.

EGU23-5223 | Orals | GI6.1

Event-oriented observation across scales and environmental systems: MOSES started operation. 

Ute Weber and Claudia Schuetze and the MOSES-Team

The novel observing system „Modular Observation Solutions for Earth Systems (MOSES)“, is an initiative of the Helmholtz Association of German Research Centers that aims at investigating the interactions of short-term events and long-term trends across environmental systems. MOSES is a mobile and modular infrastructure and its component measuring systems are managed by the participating research centers. By quantifying energy, water, nutrient and greenhouse gas states and fluxes during events such as heat waves, droughts, heavy precipitation, floods, rapid thaw of permafrost or of ocean eddies, and subsequently along the related event chains, the system delivers data to examine potential long-term impacts of these events and to gain a better understanding of extreme events that are expected to increase in frequency and intensity in a changing climate. In order to obtain comprehensive data sets, a cross-system approach is followed, covering the atmosphere, land surface and hydrosphere. These event-related data sets complement long-term and/or large scale data sets of established national and international monitoring programs and satellite data such as TERENO, ICOS, eLTER, SENTINEL, etc. After a 5-year setup period, MOSES was successfully put into operation in 2022 (Weber et al., 2022, https://doi.org/10.1175/BAMS-D-20-0158.1).

While long-term trends are typically assessed with stationary observation networks and platforms specifically designed for long-term monitoring, proven event-oriented observation systems and strategies are still missing. Event-oriented observation campaigns require a combination of a) measuring systems that can be rapidly deployed at “hot spots” and in “hot moments”, b) mobile equipment to monitor spatial dynamics in high-resolution, c) in situ measuring systems to record temporal dynamics in high-resolution, and d) interoperable measuring systems to monitor the interactions between atmosphere, land surface and hydrosphere. We will present the observation system and the observing strategy on examples from two past test campaigns: 1) The “Swabian MOSES campaign” of 2021 that captured the formation and evolution of supercells, hail and heavy precipitation and the resulting local flash floods (Kunz et al., 2022, https://doi.org/10.3389/feart.2022.999593). 2) The MOSES campaign of 2019 that captured the historical low flow situation along the Elbe River and into the German Bight (e.g., Kamjunke et al., 2021, https://doi.org/10.1002/lno.11778). As an outlook, upcoming national and international campaigns and potential future deployments will be presented.

How to cite: Weber, U. and Schuetze, C. and the MOSES-Team: Event-oriented observation across scales and environmental systems: MOSES started operation., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5223, https://doi.org/10.5194/egusphere-egu23-5223, 2023.

EGU23-5684 | ECS | Posters on site | GI6.1

Random Forest Classification of Proterozoic and Paleozoic rock types of Tsagaan-uul area, Mongolia 

Munkhsuren Badrakh, Narantsetseg Tserendash, Erdenejargal Choindonjamts, and Gáspár Albert

The Tsagaan-uul area of the Khatanbulag ancient massif in the Central Asian Orogenic Belt is located in the southern part of Mongolia, which belongs to the Gobi Desert. It has a low vegetation cover, and because of this, remotely sensed data can be used without difficulty for geological investigations. Factors such as sparse population and underdeveloped infrastructure in the region further create a need for combining traditional geological mapping with remote sensing technologies. In existing geology maps of the area, the formations are lithologically very diverse and their boundaries were mapped variously, so a need for a more precise lithology-based map arouse.

This study investigated combinations of fieldwork, multispectral data, and petrography for the rock type classification. A random forest classification method using multispectral Sentinel-2A data was employed in order to distinguish different rocks within Proterozoic Khulstai (NP1hl) metamorphic complex, which is dominated by gneiss, andesite, sandstone, limestone, amphibolite, as well as the Silurian terrigenous-carbonate Khukh morit (S1hm) formation, Tsagaan-uul area. Based on the ground samples collected from field surveys, ten kinds of rock units plus Quaternary sediments were chosen as training areas. In addition, morphometric parameters derived from SRTM data and band ratios used for iron-bearing minerals from Sentinel 2 bands are selected as variables in the accuracy of classification. The result showed that gneisses were recognized with the highest accuracy in the Khulstai complex, and limestones and Quaternary sediments were also well predicted. Moreover, the tectonic pattern was also well recognized from the results and compared to the existing maps provided a more detailed geological image of the area. This study emphasized the need for samples as baseline data to improve the machine learning methods, and the method provides an appropriate basis for fieldwork.

 

How to cite: Badrakh, M., Tserendash, N., Choindonjamts, E., and Albert, G.: Random Forest Classification of Proterozoic and Paleozoic rock types of Tsagaan-uul area, Mongolia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5684, https://doi.org/10.5194/egusphere-egu23-5684, 2023.

EGU23-5689 | Posters on site | GI6.1

Post-earthquake geoenvironmental changes in landslide-affected watersheds in Atsuma, Hokkaido (Japan) 

Yuichi S. Hayakawa, Tennyson Lo, Azim Zulhilmi, Xinyue Yu, and Xiaoxiao Wang

Following drastic changes in geoenvironmental components by coseismic landslides in mountainous watersheds, more gradual changes can be observed in the elements, including bare-land surface conditions, sediment connectivity, and vegetation recovery on sloping terrains. Such geoenvironmental changes may continue for years to decades, with complex interrelationships among various geomorphological and ecological factors. Their assessments are also crucial for local to regional environmental management. After the occurrence of numerous coseismic landslides triggered by the 2018 Hokkaido Eastern Iburi Earthquake in northern Japan, geomorphological and geoecological changes were explored using optical and laser sensors on uncrewed aerial systems. Morphological characteristics of the landslide-affected slopes in the watersheds were assessed with structure-from-motion multi-view stereo photogrammetry and light detection and ranging topographic datasets, while vegetation recovery on the slopes was examined with visible-light and near-infrared images. Although spatial relationships among morphological developments, sediment mobility, and vegetation recovery were not clearly observed, their general temporal trends may be correspondent. Dominant processes affecting the morphological developments are supposed to be frost heave in the cold climate and non-frequent high-intensity rainfalls, and these can be conditioning vegetation growth. Such local changes will be further examined on a wider, regional scale. 

How to cite: Hayakawa, Y. S., Lo, T., Zulhilmi, A., Yu, X., and Wang, X.: Post-earthquake geoenvironmental changes in landslide-affected watersheds in Atsuma, Hokkaido (Japan), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5689, https://doi.org/10.5194/egusphere-egu23-5689, 2023.

EGU23-5750 | Posters on site | GI6.1

Aseismic creep and coseismic dislocation at an active fault in volcanic area: the case of Ischia Island 

Stefano Carlino, Nicola Alessandro Pino, Lisa Beccaro, and Prospero De Martino

Understanding the fault dynamics in volcanic areas is not a simple task, mainly due to both the heterogeneity of volcanic structures and the local stress distribution. The presence of high temperature-high pressure geothermal fluids and relative high strain rates, and the occurrence of viscous processes in the deeper part of the volcano further contribute to generate complex patterns of strain load and release, possibly with aseismic creep and differential movements along the faults.

We present the case of an active fault located Casamicciola Terme town – in northern area of the volcanic caldera of Ischia Island (Southern Italy) – where repeated destructive earthquakes occurred at least since 1769, even causing thousands of victims in a single event, with the last one striking in 2017. To assess a possible mechanism leading to the activation of the Ischia main seismogenic fault, its cyclic nature and the related hazard, we performed a joined analysis of the ground vertical movements, obtained from cGPS (2001-present), DInSAR (2015-2018) time-series, and levelling data of the island (1987-2010). The geodetic data indicate that Casamicciola seismogenic fault is characterized by a complex dynamic, with some pre- and post-seismic aseismic dislocation, along sectors that move differentially, in response to the long-term subsidence of the island. Based on the ground deformation rate and on the distribution of degassing areas, we speculate that fluid pressure variations may have a major role in modulating the apparent non-stationarity of the Ischia stronger earthquakes. Furthermore, we suggest that a punctual monitoring of the distribution in space and time of the aseismic creep could provide clues on the state of strain of the seismogenic fault.

How to cite: Carlino, S., Pino, N. A., Beccaro, L., and De Martino, P.: Aseismic creep and coseismic dislocation at an active fault in volcanic area: the case of Ischia Island, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5750, https://doi.org/10.5194/egusphere-egu23-5750, 2023.

EGU23-6832 | ECS | Orals | GI6.1

Quantifying karstic geomorphologies using Minkowski tensors and graph theory: Applications to SLAM Lidar data from carbonate caves in Northern Bavaria (Germany) 

Rahul Prabhakaran, Ruaridh Smith, Daniel Koehn, Pierre-Olivier Bruna, and Giovanni Bertotti

Karstification is a ubiquitous feature in carbonate rocks. The origins can be hypogenic or epigenic based on the source of the reacting fluids. The presence of karstified lithologies and their spatial heterogeneity poses a major risk in subsurface energy utilization goals (hydrocarbons, geothermal etc). Such dissolution features tend to organize as spatial networks, with their evolution controlled by a complex interplay of several factors, including natural mineralogical variations in host rocks, effects of pre-existing structures, directional history of palaeo-flow paths, and competition between convective transport and dissolution. Accurate quantification of the spatial distribution of karst is difficult owing to resolution issues in 3D data such as seismic and ground penetrating radar. Recent advances in Simultaneous Location and Mapping (SLAM) Lidar technology have made possible to acquire karst cave passage geometries at very high-resolution with relative ease compared to conventional terrestrial lidar. In this contribution, we present a unique dataset of more than 80 caves, scanned using SLAM lidar, in Jurassic carbonates from northern Bavaria, Germany. We introduce a methodology for robustly deriving morphometrics of karstic caves using Minkowski tensors and spatial graph theory. The method is based on a combination representation of cave passage skeletons as spatial graphs and 2D passage cross-sections using Minkowski functionals. The enriched topological representation enables detailed analysis of internal spatial variation within a single cave and also comparison with cave geometries from other caves. We derive a typology of cave systems based on the degree of structural control on karstification using the database.

How to cite: Prabhakaran, R., Smith, R., Koehn, D., Bruna, P.-O., and Bertotti, G.: Quantifying karstic geomorphologies using Minkowski tensors and graph theory: Applications to SLAM Lidar data from carbonate caves in Northern Bavaria (Germany), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6832, https://doi.org/10.5194/egusphere-egu23-6832, 2023.

EGU23-7265 | Posters on site | GI6.1

Low Power, Rugged Edge Computing provides a low cost, powerful solution for on the ground remote sensing in extreme environments 

Nicholas Frearson, Terry Plank, Einat Lev, LingLing Dong, and Conor Bacon

Ground based remote sensing devices increasingly incorporate low cost single board computers such as a Raspberry Pi to capture and analyze images and data from the environment. Useful and cheap as these devices are, they are not designed for use in extreme conditions and as a consequence often suffer from early failure. Here we describe a system that incorporates a commercially available rugged Edge Computer running embedded Linux that is designed to operate in remote and extreme environments. The AVERT system  (Anticipating Volcanic Eruptions in  Real Time) developed at Columbia University in New York and funded by the Moore Foundation uses solar and wind powered Sensor nodes configured in a spoke and hub architecture currently operating on two volcanoes overseen by the Alaska Volcano Observatory in the Aleutian Islands, Alaska. Multiple Nodes distributed around the volcanoes are each controlled by an Edge Computer which manages and monitors local sensors, processes and parses their data via radio link to a central Hub and schedules system components to wake and sleep to conserve power. The Hub Edge Computer collects and assembles data from multiple Nodes and passes it via satellite, cellular modem or radio links to servers located elsewhere in the world or cloud for near real-time analysis. The local computer enables us to minimize local power demand to just a few watts in part due to the extremely low power sleep modes that are incorporated into these devices. For instance, a Node incorporating a webcam, IRCam, weather station, Edge Computer, network switch, communications radio and power management relays draws only 4.5W on average. In addition, this level of local computing power and a mature Linux operating environment enables us to run AI algorithms at source that process image and other data to flag precursory indicators of an impending eruption. This also helps to reduce data volume passed across the network at times of low network connectivity. We can also remotely interrogate any part of the system and implement new data schemes to best monitor and react to ongoing events. Future work on the AI algorithm development will incorporate local multisensor data analytics to enhance our anticipatory capability.

How to cite: Frearson, N., Plank, T., Lev, E., Dong, L., and Bacon, C.: Low Power, Rugged Edge Computing provides a low cost, powerful solution for on the ground remote sensing in extreme environments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7265, https://doi.org/10.5194/egusphere-egu23-7265, 2023.

EGU23-8673 | Orals | GI6.1

Are they radon or random signals? Analysis of time series of 222Rn activity concentrations in populated areas of La Palma (Canary Islands, Spain) 

Antonio Eff-Darwich, Germán D. Padilla, José Barrancos, José A. Rodríguez-Losada, Pedro A. Hernández, Nemesio M. Pérez, Antonio J. Álvarez Díaz, Alexis M. González Pérez, Jesús García, José M. Santana, and Eleazar Padrón

Radon, 222Rn, is a radioactive constituent of the surface layer of the atmosphere. The analysis of the temporal and spatial variations in the flux of radon across the soil–air interface is a promising tool to study geo-dynamical processes. However, many of these variations are induced by external variables, such as temperature, barometric pressure, rainfall, or the location of the instrumentation, among others.

Anomalous CO2 degassing has been observed since the end of November 2021 in the neighborhoods of La Bombilla and Puerto Naos, located in the western flank of La Palma, about 5 km distance southwestern of the 2021 Tajogaite eruption vents (Hernández et al. 2022). In order to complement these observations with other independent parameters, a set of radon monitoring stations have been deployed in that area. In an attempt to filter out non-endogenous variations in the radon signal, we have implemented time-series numerical filtering techniques based on multi-variate and frequency domain analysis. A background level for radon emissions at various locations could therefore be defined, by which correlations between radon concentration, gaseous emissions and dynamical processes could be carried out. Some preliminary results corresponding to the first 3 months of data (october-december 2022) are presented.

Hernández, P. A., Padrón, E., Melián, G. V., Pérez, N. M., Padilla, G., Asensio-Ramos, M., Di Nardo, D., Barrancos, J., Pacheco, J. M., and Smit, M.: Gas hazard assessment at Puerto Naos and La Bombilla inhabited areas, Cumbre Vieja volcano, La Palma, Canary Islands, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7705, https://doi.org/10.5194/egusphere-egu22-7705, 2022.

How to cite: Eff-Darwich, A., Padilla, G. D., Barrancos, J., Rodríguez-Losada, J. A., Hernández, P. A., Pérez, N. M., Álvarez Díaz, A. J., González Pérez, A. M., García, J., Santana, J. M., and Padrón, E.: Are they radon or random signals? Analysis of time series of 222Rn activity concentrations in populated areas of La Palma (Canary Islands, Spain), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8673, https://doi.org/10.5194/egusphere-egu23-8673, 2023.

EGU23-8795 | ECS | Orals | GI6.1

Integration of Seismic and Quasi-Static Signals for Improved Volcanic Monitoring 

Joe Carthy, Alejandra Vásquez Castillo, Manuel Titos, Luciano Zuccarello, Flavio Cannavò, and M. Carmen Benitez

The time scale of ground displacement at volcanoes varies between short, sub second seismic events, to days, months or even years. This study is focused on data from seismic and GNSS stations located around Mount Etna. The GNSS and seismic stations operate at different time scales. Data from these different time scales is extracted and combined in order to better understand the subsurface dynamics. The overall aim of this research is to improve volcanic forecasting and monitoring. It does this in a novel way by applying signal processing and machine learning techniques to the rich dataset.

Mount Etna offers an interesting case study as it is a widely monitored volcano with a variety of sensors and with a rich pool of data to analyse. Additionally the volcanic dynamics at Mount Etna are complex. This is a volcano where there is a variety of different sub-surface dynamics due to the movement of both deep and shallow magma. This allows for rich insights to be drawn through the combination of different signal types.

This study looks at combining the information obtained from the seismic array at Mount Etna, with the information obtained from various GNSS stations on the volcano. The seismic array has been able to capture ground velocity data in the frequency range 0.025 Hz to 50 Hz from a range of stations at different locations across the volcano. The GNSS stations measure ground displacement with a sampling frequency of 1 Hz, and they allow for longer term ground dynamic analysis.

We analyse different seismic events, and relate the type and number of the seismic events to the long term ground deformation that we see in the recorded GNSS data. Where links between the two signal types have been identified, research is ongoing to establish a direct connection with known volcanic activity on Mount Etna. This will help establish what the relationship that we are seeing signifies. This integration of data from different types of sensors is a significant step into bridging the gap between seismic and quasi-static ground displacement at active volcanoes and should open the path toward more in depth volcanic monitoring and forecasting.

How to cite: Carthy, J., Vásquez Castillo, A., Titos, M., Zuccarello, L., Cannavò, F., and Benitez, M. C.: Integration of Seismic and Quasi-Static Signals for Improved Volcanic Monitoring, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8795, https://doi.org/10.5194/egusphere-egu23-8795, 2023.

EGU23-10069 | ECS | Orals | GI6.1

Vredefort impact site modelling through inhomogeneous depth weighted inversion. 

Andrea Vitale and Maurizio Fedi

We are showing an application of the 3D self-constrained depth weighted inversion of the inhomogeneous gravity field (Vitale and Fedi, 2020) of the Vredefort impact site.

This method is based on two steps, the first being the search in the 3D domain of the homogenous degree of the field, and the second being the inversion of the data using a power-law weighting function with a 3D variable exponent. It does not involve directly data at different altitudes, but it is heavily conditioned by a multiscale search of the homogeneity degree.

The main difference between this inversion approach and the one proposed by Li and Oldenburg algorithm (1996) and Cella and Fedi (2012) is therefore about the depth weighting function, whose exponent is a constant through the whole space in the original Li and Oldenburg and Cella and Fedi approaches, while it is a 3D function in the method which we will discuss here.

The model volume of the area reaches 20 km in depth, while along x and y its extension is respectively 41 by 63 km. The trend at low and middle altitudes of the estimated β related to the main structures is fitting the expectations because the results relate to two main structures, which are geometrically different: the core is like a spheroid body (β ≈ 3) and the distal rings are like horizontal pipes or dykes (1 < β < 2).

With a homogeneous depth weighting function, we recover a smooth solution and both the main sources, the main core and the rings of the impact, are still visible at the bottom of the model (20 km). This is not in agreement with the result by Henkel and Reimold (1996, 1998), which, based on gravity and magnetic inversion supported by seismic data, proposed a model where the bottom of the rings is around 10 km and the density contrast effect due to the core structure loses its effectiveness around 15 km.

Instead, using an inhomogeneous depth weighting function (figure 28) we can retrieve information regarding the position at depth of both core and distal ring structures that better fits the above model. In fact, the bottom of the distal ring structure, that should be around 10 km according to Henkel and Reimold (1996, 1998), is recovered very well using an inhomogeneous depth weighting function, while in the homogeneous case we saw that the interpreted structure was still visible at large depths.

In addition, also the core structure is shallower compared to the homogeneous approach and seems more reliable if we compare it with the model of Henkel and Reimold (1996, 1998).

Instead, the inhomogeneous approach presented in this paper leads naturally us to a better solution because it takes into account during the same inversion process of the inhomogeneous nature of the structural index within the entire domain.

How to cite: Vitale, A. and Fedi, M.: Vredefort impact site modelling through inhomogeneous depth weighted inversion., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10069, https://doi.org/10.5194/egusphere-egu23-10069, 2023.

EGU23-11065 | ECS | Posters on site | GI6.1

The Dynamics of Climate Change Science and Policy in Panama: A Review 

Gustavo Cárdenas-Castillero, Steve Paton, Rodrigo Noriega, and Adriana Calderón

The local studies and reports indicate that the temperature of Panama has increased by approximately 1°C since the 1970s. More evidence shows a constantly rising sea level in the Guna Yala archipelago, coral bleaching on both coasts, and increasingly more frequent and extreme precipitation events throughout Panama. This study includes an analysis of over 400 scientific publications made by researchers from multiple centres and more than 20 Panamanian official reports due to Panama's mandate and duties under the international climate accords. To summarise the results, the studies were gathered according to the climate change effects by Panamanian locations and analysed posteriorly using Rstudio and ArcMAP. The results indicate a significant increase in climate change research beginning in 2007.

This study identified and examined the essential findings per hydroclimatic region, showing the trends, limitations, collaborations, and international contributions. Climate change research in Panama includes some of the longest-term meteorological, hydrological, oceanographic, and biological studies in the neotropics. The most significant number of identified climate change-related studies were conducted, at least in part, in the Barro Colorado Natural Monument located in central Panama. Other frequently used sites include Metropolitan Natural Park, Soberania Park, the Panama Canal Watershed and the Caribbean coast of Colón and Bocas del Toro, primarily due to research conducted by Smithsonian Tropical Research-affiliated investigators. The tropical forests of Panama are some of the bests studied in the world; however, research has been concentrated in a relatively small number of locations and should be expanded to include additional areas to achieve a more complete and comprehensive understanding of climate change will impact Panama in the future.

How to cite: Cárdenas-Castillero, G., Paton, S., Noriega, R., and Calderón, A.: The Dynamics of Climate Change Science and Policy in Panama: A Review, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11065, https://doi.org/10.5194/egusphere-egu23-11065, 2023.

EGU23-12050 | Orals | GI6.1

Stress field analysis from induced earthquakes caused by deep fluid injection: the 2013 St. Gallen (Switzerland) seismic sequence. 

Bruno Massa, Guido Maria Adinolfi, Vincenzo Convertito, and Raffaella De Matteis

The city of St. Gallen is located in the Molasse Basin of northeast Switzerland. Mesozoic units of the substratum are affected by a fault system hosting a hydrothermal reservoir. In 2013 a deep geothermal drilling project started in an area close to the city. During a phase of reservoir stimulation, a sequence of more than 340 earthquakes was induced with a maximum magnitude ML 3.5. Stress inversion of seismological datasets became an essential tool to retrieve the stress field of active tectonics areas. With this aim, a dataset of the best constrained Fault Plane Solutions (FPSs) was processed in order to qualitatively retrieve stress-fields active in the investigated volume. FPSs were obtained by jointly inverting the long-period spectral-level P/S ratios and the P-wave polarities following a Bayesian approach (BISTROP). Data were preliminarily processed by the Multiple Inverse Method to evaluate the possible dataset heterogeneity and separate homogeneous FPS populations. The resulting dataset was then processed using the Bayesian Right Trihedra Method (BRTM). Considering that hypocentral depths range between 4.1 and 4.6 km b.s.l., in order to emphasize depth-related stresses, we performed a first step of raw stress inversion procedure splitting the data into five subsets, grouping events located inside 100-m depth ranges. Once the presence of stress variations with depth has been excluded, the second step of fine stress inversion procedure was performed on the entire dataset. The stress-inversion procedure highlights an active stress field dominated by a well-constrained NE low-plunging σ3 and a corresponding NW low-plunging σ1. The corresponding Bishop ratio confirms the stability of the retrieved attitudes. Results are in good accordance with the regional stress field derived from regional natural seismicity. Additionally, the retrieved, dominant, stress field is coherent with the regional tectonic setting.

This research has been supported by PRIN-2017 MATISSE project (No. 20177EPPN2).

How to cite: Massa, B., Adinolfi, G. M., Convertito, V., and De Matteis, R.: Stress field analysis from induced earthquakes caused by deep fluid injection: the 2013 St. Gallen (Switzerland) seismic sequence., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12050, https://doi.org/10.5194/egusphere-egu23-12050, 2023.

EGU23-13693 | ECS | Orals | GI6.1

Assessing the transfer factors (TFs) of contaminants from soil to plants: the case study of Campania region (Southern Italy) 

Lucia Rita Pacifico, Annalise Guarino, Gianfranco Brambilla, Antonio Pizzolante, and Stefano Albanese

The presence of potentially toxic elements (PTEs) derived from anthropogenic sources in soil represents a serious issue for animal and human health. These elements can easily move from the geological compartment to the biological compartment through to the food chain. (Jarup, 2003).

The geochemical knowledge of a territory allows to assess the degree of contamination of the environment, to locate the sources of environmental hazard and, possibly, to manage the anomalous concentrations of the PTEs in environmental matrices with the purpose of eliminating or minimizing their negative impact on the health of living beings. (Reimann et al. 2005).

Several studies have been already carried out to determine the distribution patterns of PTEs in the soil of Campania region (Southern Italy) (De Vivo et al., 2022) but little is known about the transfer processes of contaminants from soils to agricultural products.

In light of above, we present the results of a new study whose purpose was to determine the Transfer Factors (TFs) of PTEs from soil to a series of agricultural products commonly grown in Campania.

Considering the complex geological and geomorphological settings of the region and the diffuse presence of an historical anthropization related to the industry, agriculture, and urbanization, TFs were calculated for a relevant number of fruit and vegetable samples (3731 specimens). They were collected across the whole regional territory to detect differences between analysed species and to highlight the spatial changes in TFs occurring for individual species.

The TFs were calculated starting from the quasi-total (based on Aqua Regia leaching) and bioavailable (based on Ammonium Nitrate leaching) concentrations of PTEs in 7000 and 1500 soil samples, respectively.

Preliminary results show that TFs determined for the various agricultural species vary in space and in amount independently from the original elemental concentrations in soils. High values of TFs are found in areas where PTE concentrations in soil are low and vice versa, thus suggesting that multiple regression and multivariate analyses could be performed to investigate if some additional chemical and physical characteristics of soil (pH, grainsize, OM, etc.) could have a relevant weight on the transfer processes of contaminant from the soil to the plant life.

 

References

Järup L. 2003. Hazards of heavy metal contamination. Br. Med. Bull. 68, 167–182.

Reimann C., de Caritat P. 2005. Distinguishing between natural and anthropogenic sources for elements in the environment: regional geochemical surveys versus enrichment factors. Science of The Total Environment, Volume 337, Issues 1–3, pages 91-107.

De Vivo B. et al. 2022. Monitoraggio geochimico-ambientale dei suoli e dell'aria della Regione Campania. Piano Campania trasparente. Volume 4. Aracne Editore, Genzano di Roma.

How to cite: Pacifico, L. R., Guarino, A., Brambilla, G., Pizzolante, A., and Albanese, S.: Assessing the transfer factors (TFs) of contaminants from soil to plants: the case study of Campania region (Southern Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13693, https://doi.org/10.5194/egusphere-egu23-13693, 2023.

EGU23-13853 | Posters on site | GI6.1

Analysis and Modelling of 2009-2013 vs. 2019-2022 Unrest Episodes at Campi Flegrei Caldera 

Raffaele Castaldo, Andrea Barone, De Novellis Vincenzo, Pepe Antonio, Pepe Susi, Solaro Giuseppe, Tizzani Pietro, and Tramelli Anna

Geodetic modelling is a significant procedure for detecting and characterizing unrest and eruption episodes and it represents a valuable tool to infer volume and geometry of volcanic source system.

In this study, we analyse the 2009–2013 and the ongoing 2019-2022 uplift phenomena at Campi Flegrei (CF) caldera in terms of spatial and temporal variations of the stress/strain field. In particular, we investigate the characteristics of the inflating sources responsible of these main deformation unrests occurred in the last twenty years. We separately perform for the two considered periods a 3D stationary Finite Element (FE) modelling of geodetic datasets to retrieve the geometry and location of the deformation sources. The geometry of FE domain takes into account both the topography and the bathymetry of the whole caldera. For what concern the definition of domain elastic parameters, we take into account the Vp/Vs distribution from seismic tomography. In order to optimize the nine model parameters (center coordinates, sferoid axes, dip, strike and over-pressure), we use the statistical random sampling Monte Carlo method by exploiting both geodetic datasets: the DInSAR measurements obtained from the processing of COSMO-SkyMed and Sentinel-1 satellite images. The modelling results for the two analysed period are compared revealing that the best-fit source is a three-axis oblate spheroid ~3.5 km deep, similar to a sill-like body. Furthermore, in order to verify the reliability of the geometry model results, we calculate the Total Horizontal Derivative (THD) of the vertical velocity component and compare it with those performed directly on the two DInSAR dataset.

Finally, we compare the modelled shear stress with the natural seismicity recorded during the 2000-2022 period, highlighting high values of modelled shear stress at depths of about 3.5 km, where high-magnitude earthquakes nucleate.

How to cite: Castaldo, R., Barone, A., Vincenzo, D. N., Antonio, P., Susi, P., Giuseppe, S., Pietro, T., and Anna, T.: Analysis and Modelling of 2009-2013 vs. 2019-2022 Unrest Episodes at Campi Flegrei Caldera, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13853, https://doi.org/10.5194/egusphere-egu23-13853, 2023.

EGU23-15127 | ECS | Orals | GI6.1

Multiscale magnetic modelling in the ancient abbey of San Pietro in Crapolla 

Luigi Bianco, Maurizio Fedi, and Mauro La Manna

We present a multiscale analysis of magnetic data in the archaeological site of San Pietro in Crapolla (Massa Lubrense, near Naples, Italy). The site consists of the ruins of an ancient abbey. We computed the Wavelet Transform of the Gradiometric measurements and decomposed the data at different scales and positions by a multiresolution analysis, allowing an effective extraction of local anomalies. Modelling of the filtered anomalies was performed by multiscale methods known as “Multiridge analysis” and “DEpth from eXtreme Points (DEXP)”.  The first method analyses a multiscale dataset at the zeroes of the first horizontal and vertical derivatives besides the potential field data themselves (ridges).  The Wavelet Transform Modulus Maxima  lines converged to buried remains. The field, scaled by a power law of the altitude (DEXP transformation) allowed estimates of source depths at its extreme points. The depth estimations for the buried structures obtained from the two methods are very close each other and fairly agree with those from the modelling of GPR anomalies. On the basis of these results, an archaeological excavation followed our indications and brought to light ancient walls.

How to cite: Bianco, L., Fedi, M., and La Manna, M.: Multiscale magnetic modelling in the ancient abbey of San Pietro in Crapolla, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15127, https://doi.org/10.5194/egusphere-egu23-15127, 2023.

EGU23-15190 | Orals | GI6.1

Synthetic aperture radar burst overlapped interferometry for the analysis of large ground instabilities: Experiments in volcanic regions. 

Antonio Pepe, Andrea Barone, Pietro Mastro, Pietro Tizzani, and Raffaele Castaldo

This work presents an overview of some applications of synthetic aperture radar (SAR) interferometry technology for the detection and analysis of large ground displacements occurring in volcanic areas, with the aim to retrieve the three-dimensional (3-D) ground displacement field (up-down, east-west, north-south). Specifically, the work summarizes and investigates the potential of Bursted Overlapped Interferometry (BOI) that properly combined can allow the retrieval, at different scales of resolution and accuracies, of the north-south components of the ground deformations, which are usually not available considering conventional SAR interferometry techniques. In this context, the almost global coverage and the weekly revisit times of the European Copernicus Sentinel-1 SAR sensors permit nowadays to perform extensive analyses with the aim to assess the accuracy of the BOI techniques. More recently, Spectral Diversity (SD) methods have been exploited for the fine co-registration of SAR data acquired with the Terrain Observation with Progressive Scans (TOPS) mode. In this case, considering that TOPS acquires images in a burst mode, there is an overlap region between consecutive bursts where the Doppler frequency variations is large enough to allow estimating and compensating for, with great accuracy, potential bursts co-registration errors. Additionally, and more importantly, in the case of non-stationary scenarios, it allows detecting the ground displacements occurring along the azimuthal directions (almost aligned along north-south) with centimeter accuracy. This is done by computing the difference between the right and left interferograms, i.e., the burst overlapped interferogram, and relating it to the ongoing deformation signals.

This work aims to apply the BOI technique in selected volcanic and seismic areas to evaluate the impact of this novel technology for the analysis of quantifying, over small, covered regions, the accumulated ground displacements in volcanic areas. In such regions, the interest is on quantifying the accuracy of integrated BOI systems for the retrieval of 3-D displacements. To this aim, we selected as a test site the Galapagos Island and we analyze with BOI the north-south ground displacements. At the next EGU symposium, the results of the BOI analyses will be presented, thus also providing comparative analyses with the results obtained from the use of potential field method applied on the ground displacements in volcanic areas. More specifically, by adopting this technique, we are able to estimate independently the north-south components of the ground displacement by exploiting the harmonic properties of the elasticity field.

How to cite: Pepe, A., Barone, A., Mastro, P., Tizzani, P., and Castaldo, R.: Synthetic aperture radar burst overlapped interferometry for the analysis of large ground instabilities: Experiments in volcanic regions., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15190, https://doi.org/10.5194/egusphere-egu23-15190, 2023.

EGU23-16132 | ECS | Orals | GI6.1

Multiscale imaging of low-enthalpy geothermal reservoir of the Phlegraean Fields caldera from gravity and resistivity data. 

Maurizio Milano, Giuseppe Cavuoto, Alfonso Corniello, Vincenzo Di Fiore, Maurizio Fedi, Nicola Massarotti, Nicola Pelosi, Michele Punzo, Daniela Tarallo, Gian Paolo Donnarumma, and Marina Iorio

The central‐eastern sector of the Phlegraean Fields caldera, southern Italy, is one of the most intensely studied and monitored volcanic active area of the word. This area reveals typical characters of a high‐ enthalpy geothermal systems. However, recently the presence of two different geothermal reservoirs has been outlined: one located in the central sector dominated by highly active vapours generated by episodic arrival of CO2‐rich magmatic fluids and the other one located in the eastern sector (Agnano zone) characterized by a shallow (400-500 m b.s.l.) still hot reservoir, heated by the upward circulation of deep no magmatic hot vapor.

In this study we present preliminary results deriving from the integration of different geophysical surveys carried out in the Agnano plain area, in the frame of the GEOGRID research project. We acquired high-resolution gravity data along two parallel profiles and we investigated the depth, shape and density contrast of the subsurface structures by the CompactDEXP (CDEXP) method, a multiscale iterative imaging technique based on the DEXP method. The resulting density models, together with DC resistivity and stratigraphic data, outlines the presence of a complex morphology of the Agnano subsoil characterized by a horst-graben structure. The importance of the structural lines identified by geophysical data, is also confirmed by the alignment of correlate outcropping thermal waters.

How to cite: Milano, M., Cavuoto, G., Corniello, A., Di Fiore, V., Fedi, M., Massarotti, N., Pelosi, N., Punzo, M., Tarallo, D., Donnarumma, G. P., and Iorio, M.: Multiscale imaging of low-enthalpy geothermal reservoir of the Phlegraean Fields caldera from gravity and resistivity data., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16132, https://doi.org/10.5194/egusphere-egu23-16132, 2023.

In the wake of Chernobyl and Fukushima accidents radiocesium has become a radionuclide of most environmental concern. The ease with which this radionuclide moves through the environment and is taken up by plants and animals is governed by its chemical forms and site-specific environmental characteristics. Distinctions in climate and geomorphology, as well as 137Cs speciation in the fallout result in differences in migration rates of 137Cs in the environment and rates of its natural attenuation. In Fukushima areas 137Cs was found to be strongly bound to soil and sediment particles, its bioavailability being reduced as a result.  Up to 80% of the deposited 137Cs on the soil were reported to be incorporated in hot glassy particles (CsMPs) insoluble in water. Disintegration of these particles in the environment is much slower than of Chernobyl-derived fuel particles. The higher annual precipitation and steep slopes in Fukushima contaminated areas are conducive to higher erosion and higher total radiocesium wash-off. Typhoons Etou in 2015 and Hagibis in 2019 demonstrated the pronounced redistribution of 137Cs on river watersheds and floodplains, and in some cases natural self-decontamination occurred. Among the common features in 137Cs behavior in Chernobyl and Fukushima is a slow decrease in 137Cs activity concentration in small, closed, and semi-closed lakes and its particular seasonal variations: increase in summer and decrease in winter.

How to cite: Konoplev, A.: Fukushima and Chernobyl: similarities and differences of radiocesium behavior in the soil-water environment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1081, https://doi.org/10.5194/egusphere-egu23-1081, 2023.

After the Fukushima nuclear accident, atmospheric 134Cs and 137Cs measurements were taken in Fukushima city for 8 years, from March 2011 to March 2019. The airborne surface concentrations and deposition of radiocesium (radio-Cs) were high in winter and low in summer; these trends are the opposite of those observed in a contaminated forest area. The effective half-lives of 137Cs in the concentrations and deposition before 2015 (0.754 and 1.30 years, respectively) were significantly shorter than those after 2015 (2.07 and 4.69 years, respectively), which was likely because the dissolved radio-Cs was discharged from the local terrestrial ecosystems more rapidly than the particulate radio-Cs. In fact, the dissolved fractions of precipitation were larger than the particulate fractions before 2015, but the particulate fractions were larger after 2016. X-ray fluorescence analysis suggested that biotite may have played a key role in the environmental behavior of particulate forms of radio-Cs after 2014. 

Resuspension of 137Cs from the contaminated ground surface to the atmosphere is essential for understanding the long-term environmental behaviors of 137Cs. We assessed the 137Cs resuspension flux from bare soil and forest ecosystems in eastern Japan in 2013 using a numerical simulation constrained by surface air concentration and deposition measurements. In the estimation, the total areal annual resuspension of 137Cs is 25.7 TBq, which is equivalent to 0.96% of the initial deposition (2.68 PBq). The current simulation underestimated the 137Cs deposition in Fukushima city in winter by more than an order of magnitude, indicating the presence of additional resuspension sources. The site of Fukushima city is surrounded by major roads. Heavy traffic on wet and muddy roads after snow removal operations could generate superlarge (approximately 100 μm in diameter) road dust or road salt particles, which are not included in the model but might contribute to the observed 137Cs at the site.

The current presentation based on the two published papers: Watanabe et al., ACP, https://doi.org/10.5194/acp-22-675-2022 (2022) and Kajino et al., ACP, https://doi.org/10.5194/acp-22-783-2022 (2022). The presenters would like to thank all of the co-authors of the two papers for their significant contributions.

How to cite: Kajino, M. and Watanabe, A.: Eight-year variations in atmospheric radiocesium in Fukushima city and simulated resuspension from contaminated ground surfaces in eastern Japan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1607, https://doi.org/10.5194/egusphere-egu23-1607, 2023.

EGU23-2540 | Posters on site | GI2.2

Hydrological setting control 137Cs and 90Sr concentration at headwater catchments in the Chornobyl Exclusion Zone 

Yasunori Igarashi, Yuichi Onda, Koki Matsushita, Hikaru Sato, Yoshifumi Wakiyama, Hlib Lisovyi, Gennady Laptev, Dmitry Samoilov, Serhii Kirieiev, and Alexei Konoplev

Concentration-discharge relationships are widely used to understand the hydrologic processes controlling river water chemistry. We investigated how hydrological processes affect radionuclide concentrations (137Cs and 90Sr) in surface water in the headwater catchment at the Chornobyl exclusion zone in Ukraine. In flat wetland catchment, the depth of saturated soil layer changed little throughout the year, but changes in saturated soil surface area during snowmelt and immediately after rainfall affected water chemistry by changing the opportunities for contact between suface water and the soil surface. On the other hand, slope catchments with little wetlands, the water chemistry in river water is formed by changes in the contribution of "shallow water" and "deep water" due to changes in the water pathways supplied to the river. Dissolved and suspended 137Cs concentrations did not correlate with discharge rate or competitive cations, but the solid/liquid ratio of 137Cs showed a significant negative relationship with water temperature, and further studies are needed in terms of sorption/desorption reactions. 90Sr concentrations in surface water were strongly related to water pathways for each the catchments. The contact between surface water and the soil surface and the change in the contribution of shallow and deep water to stream water could changes 90Sr concentrations in surface water for in wetland and slope catchments, respectively. In this study, we revealed that the radionuclide concentrations in rivers in Chornobyl is strongly affected by the water pathways at headwater catchments.

How to cite: Igarashi, Y., Onda, Y., Matsushita, K., Sato, H., Wakiyama, Y., Lisovyi, H., Laptev, G., Samoilov, D., Kirieiev, S., and Konoplev, A.: Hydrological setting control 137Cs and 90Sr concentration at headwater catchments in the Chornobyl Exclusion Zone, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2540, https://doi.org/10.5194/egusphere-egu23-2540, 2023.

EGU23-2561 | Posters on site | GI2.2

Dispersion of particle-reactive elements caused by the phase transitions in scavenging 

Kyeong Ok Kim, Vladimir Maderich, Igor Brovchenko, Kyung Tae Jung, Sergey Kivva, Katherine Kovalets, and Haejin Kim

A generalized model of scavenging of the reactive radionuclide 239,240Pu was developed, in which the sorption-desorption processes of oxidized and reduced forms on multifraction suspended particulate matter are described by first-order kinetics. One-dimensional transport-diffusion-reaction equations were solved analytically and numerically. In the idealized case of instantaneous release of 239,240Pu on the ocean surface, the profile of concentrations asymptotically tends to the symmetric spreading bulge in the form of a Gaussian moving downward with constant velocity. The corresponding diffusion coefficient is the sum of the physical diffusivity and the apparent diffusivity caused by the reversible phase transitions between the dissolved and particulate states. Using the method of moments, we analytically obtained formulas for both the velocity of the center mass and apparent diffusivity. It was found that in ocean waters that have oxygen present at great depths, we can consider in the first approximation a simplified problem for a mixture of forms with a single effective distribution coefficient, as opposed to considering the complete problem. This conclusion was confirmed by the modeling results for the well-ventilated Eastern Mediterranean. In agreement with the measurements, the calculations demonstrate the presence of a maximum that is slowly descending for all forms of concentration. The ratio of the reduced form to the oxidized form was approximately 0.22-0.24. At the same time, 239,240Pu scavenging calculations for the anoxic Black Sea deep water reproduced the transition from the oxidized to reduced form of 239,240Pu with depth in accordance with the measurement data.

How to cite: Kim, K. O., Maderich, ., Brovchenko, ., Jung, . T., Kivva, ., Kovalets, ., and Kim, .: Dispersion of particle-reactive elements caused by the phase transitions in scavenging, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2561, https://doi.org/10.5194/egusphere-egu23-2561, 2023.

EGU23-3049 | ECS | Posters on site | GI2.2

Changes in Air Dose Rates due to Soil Water Content in Forests in Fukushima Prefecture, Japan 

Miyu Nakanishi, Yuichi Onda, Hiroaki Kato, Junko Takahashi, Hikaru Iida, and Momo Takada

Radionuclides released and deposited by the 2011 Fukushima Daiichi Nuclear Power Plant accident caused an increase in air dose rates in forests in Fukushima Prefecture. It has been reported that air dose rates increase during rainfall, but we found that air dose rates decreased during rainfall in forests in Fukushima. This is said to be due to the shielding effect of soil moisture. This study aimed to develop a method for estimating changes in air dose rates due to rainfall even in the absence of soil moisture data. Therefore, we used the preceding rainfall (Rw), an indicator that also takes into account past rainfall; we calculated Rw in Namie-Town, Futaba-gun, Fukushima Prefecture from May to July 2020, and estimated air dose rates. In this area, air dose rates decreased with increasing soil moisture. Furthermore, air dose rates could be estimated by combining Rw with a half-life of 2 hours and 7 days, and by considering hysteresis in the absorption and drainage processes. The coefficient of determination (R2) exceeded 0.70 for the estimation of soil water content at this time. Furthermore, good agreement was also observed in the estimation of air dose rates from Rw (R2 > 0.65). The same method was used to estimate air dose rates at the Kawauchi site from May to July 2019. Due to the high water repellency of the Kawauchi site, the increase in soil water content was very small and the change in air dose rate was almost negligible when soil water content was less than 15% and rainfall was less than 10 mm. This study enabled the estimation of soil water content and air dose rate from rainfall and captured the effect of rainfall on the decreasing trend of air dose rate. Therefore, in the future, This study can be used as an indicator to determine whether temporary changes in air dose rates are caused by influences other than rainfall. This study also contributes to the improvement of methods for estimating external dose rates for humans and terrestrial animals and plants in forests.

How to cite: Nakanishi, M., Onda, Y., Kato, H., Takahashi, J., Iida, H., and Takada, M.: Changes in Air Dose Rates due to Soil Water Content in Forests in Fukushima Prefecture, Japan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3049, https://doi.org/10.5194/egusphere-egu23-3049, 2023.

Wet scavenging modeling remains a challenge of the atmospheric transport of 137Cs following the Fukushima Daiichi Nuclear Power Plant accident, which significantly influences the detailed spatiotemporal 137Cs distribution. Till now, numerous wet deposition schemes have been proposed for 137Cs, but it is often difficult to evaluate them consistently, due to the limited resolution of meteorological field data and detailed differences in model implementations. This study evaluated the detailed behavior of 25 combinations of in- and below-cloud wet scavenging models in the framework of the Weather Research and Forecasting-Chemistry model, using high-resolution (1 km × 1 km) meteorological input. The above implementation enables consistent evaluation with great details, revealing complex local behaviors of these combinations. The 1-km-resolution simulations were compared with simulations obtained previously using 3-km-resolution meteorological field data, with respect to the rainfall pattern of the east Japan during the accident, atmospheric concentrations acquired at the regional SPM monitoring sites and the total ground deposition. The capability of these models in reproducing local-scale observations were also investigated with a local-scale observations at the Naraha site, which his only 17.5 km from the Fukushima Daiichi Nuclear Power Plant. The performance of the ensemble mean was also evaluated. Results revealed that the 1-km simulations better reproduce the cumulative rainfall pattern during the Fukushima accident than those revealed by the 3-km simulations, but showing with spatiotemporal variability in accuracy. And rainfall below 1 mm/h is critical for the simulation accuracy. Those single-parameter wet deposition models that rely solely on the rainfall showed improvements in performance in the 1-km simulations relative to that in the 3-km simulations, because of the improved rainfall simulation in the 1-km results. Those multiparameter models that rely on both cloud and rainfall showed more robust performance in both the 3-km and -1km simulations, and the Roselle–Mircea model presented the best performance among the 25 models considered. Besides rainfall, wind transport showed substantial influence on the removal process of atmospheric 137Cs, and it was nonnegligible even during periods in which wet deposition was dominant. The ensemble mean of the 1-km simulations better reproduces the high deposition area and the total deposition amount is closer to the observations than the 3-km simulation. At the local scale, the 1-km-resolution simulations effectively reproduced the 137Cs concentrations observed at the Naraha site, but with deviations in peak timing, mainly because of biased wind direction. These findings indicate the necessity of a multi-parameter model for robust regional-scale wet deposition simulation and a refined wind and dispersion model for local-scale simulation of 137Cs concentration.

How to cite: Zhuang, S., Dong, X., Xu, Y., and Fang, S.: Modeling and sensitivity study of wet scavenging models for the Fukushima accident using 1-km-resolution meteorological field data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4152, https://doi.org/10.5194/egusphere-egu23-4152, 2023.

EGU23-4697 | ECS | Orals | GI2.2

Quantifying the riverine sources of sediment and associated radiocaesium deposited off the coast of Fukushima Prefecture 

Pierre-Alexis Chaboche, Wakiyama Yoshifumi, Hyoe Takata, Toshihiro Wada, Olivier Evrard, Toshiharu Misonou, Takehiko Shiribiki, and Hironori Funaki

The Fukushima-Daiichi Nuclear Power Plant (FDNPP) accident trigged by the Great East Japan Earthquake and subsequent tsunami in March 2011 released large quantities of radionuclides in terrestrial and marine environments of Fukushima Prefecture. Although radiocaesium (i.e. 134Cs and 137Cs) activity in these environments has decreased since the accident, the secondary inputs via the rivers draining and eroding the main terrestrial radioactive plume were shown to sustain high levels of 137Cs in riverine and coastal sediments, which are likely deposited off the coast of the Prefecture. Accordingly, identifying the sources of sediment is required to elucidate the links between terrestrial and marine radiocaesium dynamics and to anticipate the fate of persistent radionuclides in the environment.

The objective of this study is to develop an original sediment source tracing technique to quantify the riverine sources of sediment and associated radionuclides accumulated in the Pacific Ocean. Target coastal sediment cores (n=6) with a length comprised between 20 and 60cm depth were collected during cruise campaigns between July and September 2022 at the Ota (n=2), Niida (n=1) and Ukedo (n=3) river mouths. Prior to gamma spectrometry measurements, sediment cores were opened and cut into 2 cm increments, oven-dried at 50°C for at least 48 hours, ground and passed through a 2-mm sieve.

Preliminary results regarding the spatial and depth distribution of radiocaesium in these samples show a strong heterogeneity, with highest radiocaesium levels (up to 134 ± 2 and 4882 ± 11 Bq kg-1 for 134Cs and 137Cs, respectively) found in coastal sediment cores located at the Ukedo river mouth. On the opposite, no trace or low levels of Fukushima-derived radiocaesium were found in the Niida and in one sediment core of the Ota River mouths. Additional measurements will be conducted to determine the physico-chemical properties of this sediment, in order to select the optimal combination of tracers, which will then be introduced into un-mixing models. This increase knowledge will undoubtedly be useful for watershed and coastal management in the FDNPP post-accidental context.

How to cite: Chaboche, P.-A., Yoshifumi, W., Takata, H., Wada, T., Evrard, O., Misonou, T., Shiribiki, T., and Funaki, H.: Quantifying the riverine sources of sediment and associated radiocaesium deposited off the coast of Fukushima Prefecture, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4697, https://doi.org/10.5194/egusphere-egu23-4697, 2023.

EGU23-4925 | Posters on site | GI2.2

Verification of reproductivity of 137Cs activity concentration in the database by an ocean general circulation model 

Daisuke Tsumune, Frank Bryan, Keith Lindsay, Kazuhiro Misumi, Takaki Tsubono, and Michio Aoyama

Radioactive cesium (137Cs) is distributed in the global ocean due to global fallout from atmospheric nuclear tests, release from reprocessing plants in Europe, and supply to the ocean due to the Fukushima Daiichi Nuclear Power Plant accident. In order to detect future contamination by radionuclides, it is necessary to understand the global distribution of radionuclides such as 137Cs. For this purpose, the IAEA is compiling a database of observation results (MARIS). However, since the spatio-temporal densities of observed data vary widely, it is difficult to obtain a complete picture from the database alone. Comparative validation using ocean general circulation model (OGCM) simulations is useful in interpreting these observations, and global ocean general circulation model (CESM2, POP2) simulations were conducted to clarify the behavior of 137Cs in the ocean. The horizontal resolution is 1.125° longitude and 0.28° to 0.54° latitude. The minimum spacing near the sea surface is 10 m, and the spacing increases with depth to a maximum of 250 m with 60 vertical levels. Climatic values were used for driving force. As a source term for 137Cs to the ocean, atmospheric fallout from atmospheric nuclear tests was newly established based on rainfall data and other data, and was confirmed to be more reproducible than before. Furthermore, the release from reprocessing plants in Europe and the leakage due to the accident at the Fukushima Daiichi Nuclear Power Plant were taken into account. 2020 input conditions were assumed to continue after 2020, and calculations were performed from 1945 to 2030. The simulated 137Cs activities were found to be in good agreement, especially in the Atlantic and Pacific Oceans, where the observed densities are large. On the other hand, they were underestimated in the Southern Hemisphere, suggesting the need for further improvement of the fallout data. 137Cs concentrations from the Fukushima Daiichi Nuclear Power Plant accident in March 2011 were generally in good agreement, although the reproducibility remained somewhat problematic due to insufficient model resolution. In other basins, the concentration characteristics were able to be determined, although the observed values were insufficient. Radioactivity concentrations of atmospheric nuclear test-derived 137Cs may continue to be detected in the global ocean after 2030. The results of this simulation are useful for planning future observations to fill the gaps in the database.

How to cite: Tsumune, D., Bryan, F., Lindsay, K., Misumi, K., Tsubono, T., and Aoyama, M.: Verification of reproductivity of 137Cs activity concentration in the database by an ocean general circulation model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4925, https://doi.org/10.5194/egusphere-egu23-4925, 2023.

EGU23-4947 | ECS | Posters on site | GI2.2

Vertical distribution of radioactive cesium-rich microparticles in forest soil of Hamadori area, Fukushima Prefecture 

Takahiro Tatsuno, Hiromichi Waki, Naoto Nihei, and Nobuhito Ohte

A lot of radionuclides were scattered after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. Previous studies showed that there were FDNPP-derived radioactive cesium-rich microparticles (CsMPs) with the size of a few μm in the soil and river water around Fukushima Prefecture[1]. CsMPs have high radioactive cesium (Cs) concentration per unit mass, therefore they can be one of the factor in overestimating the Cs concentration in samples. Because Cs in CsMPs may not react directly with clay particles unlike the Cs ion in liquid phase, it is considered that CsMPs work as Cs carrier in soils[2]. However, unlike ionic Cs and Cs adsorbed onto clay particles, the distribution and dynamics of CsMPs in soils have not been clarified. In this study, we investigated vertical distribution of CsMPs in the forest soil and the soil properties in Fukushima Prefecture, Japan.

Soil samples were collected from the forest in the difficult-to-return zone, approximately 10 km away from the FDNPP. The undisturbed soil samples were collected from 0-35 cm soil depth at 5 cm intervals using core sampler to investigate soil properties. Furthermore, litter samples on the surface soil layer were collected. Using these samples, the vertical distribution of Cs concentration in the soil and Cs derived from CsMPs were investigated. Cs concentration in samples placed in 100 mL of U8 container was measured using a germanium semiconductor detector. Cs derived from CsMPs was evaluated using an Imaging plate with reference to the method ffor quantification of CsMPs[3].

Like Cs adsorbed on the soil, CsMPs were also mostly distributed in the soil surface layer between o and 5 cm of soil depth. We considered that straining may be one of the mechanism of CsMPs retention on the soil surface. Bradford et al. (2006) [4] showed that straining might be a significant mechanism for colloid retention when the average particle size in the porous medium is less than 200 times larger than the colloidal particle size. In this study, assuming the CsMPs size of approximately 1 µm, the average particle size of the soil collected from surface layer 0-5 cm was less than 200 times that of CsMPs. However, the average particle size decreased in deeper layer than 5 cm, therefore, it was considered that straining mechanism could be stronger.

This work was supported by FY2022 Sumitomo Foundation and FY2022 Internal Project of Institute of Environmental Radioactivity, Fukushima University.

 

References

[1] Igarashi, Y. et al., 2019. J. Environ. Radioact. 205–206, 101–118.

[2]  Tatsuno, T et al., 2022. J. Environ. Manage. 329, 116983.

[3] Ikehara et al., 2018. Environ. Sci. Technol. 52, 6390–6398.

[4] Bradford et al., 2003. Environ. Sci. Technol. 37, 2242–2250.

How to cite: Tatsuno, T., Waki, H., Nihei, N., and Ohte, N.: Vertical distribution of radioactive cesium-rich microparticles in forest soil of Hamadori area, Fukushima Prefecture, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4947, https://doi.org/10.5194/egusphere-egu23-4947, 2023.

EGU23-5042 | ECS | Posters on site | GI2.2

Changes in 90Sr transport dynamics in groundwater after large-scale groundwater drawdown in the vicinity of the cooling pond at the Chornobyl Nuclear Power Plant 

Hikaru Sato, Naoaki Shibasaki, Maksym Gusyev, Yuichi Onda, and Dmytro Veremenko

Migration of long-lived radioactive 90Sr introduced by nuclear accidents and radioactive waste requires long-term monitoring and protection management due to its half-life of 28.8 years and high mobility in water. Presently, 37 years have passed since the largest worldwide 90Sr contamination was released and deposited around the Chornobyl Nuclear Power Plant (ChNPP). In the vicinity of the ChNPP, the water level of the cooling pond (CP) has declined since May 2014 following the decommissioning phase of the Unit 3 reactor. The drawdown of the CP lowered the groundwater level in a massive vicinity (about 70 km2), and the change in the groundwater system due to the drawdown has caused concerns about possible changes in 90Sr concentrations in water and transport dynamics to the Pripyat River. Therefore, this study evaluated how 90Sr transport dynamics were influenced due to changes in the groundwater flow system from 2011 to 2020 based on observed data and results of the groundwater flow simulation in the CP vicinity.

The numerical simulation was conducted from 2011 to 2020 on monthly time-step using USGS MODFLOW with PM11 GUI and calibrated to groundwater heads measured at monitoring wells. In the location between the CP and the Pripyat River, estimated pore velocities near the river were reduced compared to velocities before the CP drawdown due to the decrease in the hydraulic gradient between the CP and the river. Decrease in groundwater velocity results decrease in groundwater discharge and delay of 90Sr transport. Therefore, the amount of 90Sr transported from the CP to the river is smaller than the period prior to the CP drawdown. The reduced 90Sr transport is expected to have less impact on the radioactivity in the river water even in the Pripyat River floodplain northwest of the CP where 90Sr concentrations significantly increased after the CP drawdown. In addition, the measured and simulated changes in groundwater flow direction and velocity suggested the possibility of 90Sr accumulation at the floodplain caused by stagnant groundwater from reduced velocity and additional 90Sr infiltration from surrounding ponds located at the Pripyat River floodplain. Therefore, enhancing the current monitoring of 90Sr concentrations near the floodplain would be needed for long-term monitoring and protection management to prevent the risk.

How to cite: Sato, H., Shibasaki, N., Gusyev, M., Onda, Y., and Veremenko, D.: Changes in 90Sr transport dynamics in groundwater after large-scale groundwater drawdown in the vicinity of the cooling pond at the Chornobyl Nuclear Power Plant, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5042, https://doi.org/10.5194/egusphere-egu23-5042, 2023.

The 3D model THREETOX was applied for the long-term simulation of the planned release of radioactively contaminated water from Fukushima storage tanks to marine environment. Two radionuclides were considered: 3H that has the largest activity in tanks and 129I that can caused the largest dose of radiation to human. The constant release rate of 3H equal to 22 TBq/y according to TEPCO estimations and the constant release rate of 129I equal to 361 MBq/y according to estimations from the current study were used in the simulations.

The THREETOX model used monthly averaged currents from the KIOST-MOM model. A dynamic food web model was included in the THREETOX model. In the model, organisms uptake the activity directly from water and through the food chain. The food chain consists of phytoplankton, zooplankton, non-piscivorous (prey) fish, and piscivorous (predatory) fish. In case of 129I, macro-algae was also considered. The modelling area covers Fukushima coastal waters and extends for 1600 km from the coast to the East. From North to South this area extends for 1300 km.

From model results, we can see how contamination will spread along the coast in different seasons. For example, in summer time the currents near the coast are directed to the North that leads to contamination of the Sendai Bay. This means that at different points along the coast, the concentration of radionuclides can periodically change according to currents that change during the year. Calculated concentrations of activity at several points along the coast of Japan, which correspond to largest cities in the area of interest, were extracted from model results. For example, calculated concentration of 3H in water in Tomioka point, which is quite close to FDNPP, sometimes can exceed 200 Bq/m3. In Soma point, the concentration will exceed 50 Bq/m3, while in point Iwaki-Onahama – 20 Bq/m3 at some moments of time. In other points, the calculated concentration of 3H in water will not exceed 10 Bq/m3 that is less than background concentration 50 Bq/m3. Concerning 129I, its maximum concentration in water will be around 10-3 – 10-2 Bq/m3 in points close to FDNPP and around 10-4 Bq/m3 in points further from the NPP that is around 100 000 times less than the calculated concentrations of 3H.

Calculated concentrations of OBT (organically bounded tritium) in predatory and prey fish are less than 0.01 Bq/kg in all points except FDNPP point where it is around 0.02 Bq/kg. This value is 10 times less than measured concentration of OBT in fish (0.2 Bq/kg) that was made in 2014 in the coastal area near the damaged NPP. Calculated concentrations of 129I in predatory and prey fish are in the range 10-6 – 10-4 Bq/kg in all considered points. Concentrations of 129I in macro-algae are about 100 times higher due to ability of iodine to accumulate in macro-algae. 

How to cite: Bezhenar, R., Takata, H., and Maderich, V.: Transport of H-3 and I-129 in water and their uptake by marine organisms due to the planned release of Fukushima storage water, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6019, https://doi.org/10.5194/egusphere-egu23-6019, 2023.

EGU23-6026 | Orals | GI2.2

Dynamic change of dissolved Cs-137 from headwaters to downstream in the Kuchibuto River catchment 

Yuichi Onda, Taichi Kawano, Keisuke Taniguchi, and Junko Takahashi

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on March 11, 2011 resulted in the release of large amounts of radioactive cesium-137 (137Cs) into the environment. It is important to characterize the Cs-137 dynamics throughout the river from the headwaters to the downstream. Previous studies have suggested the importance of dissolved forms of Cs-137 in organic matter in small watersheds and dissolved forms in suspended solids in large watersheds. Since the concentration of suspended-form Cs has been shown to decrease significantly after decontamination in evacuated areas (Feng et al. 2022), this rapid decrease in suspended-form Cs-137 concentration can be used to determine the cause of dissolved-form Cs. Therefore, we attempted to evaluate whether the dissolved Cs-137 was derived from organic matter or suspended solids by comparing data before and after decontamination.

 The objective of this study is to compare the decreasing trends of Cs-137 concentrations in decontaminated and undecontaminated areas based on long-term monitoring of suspended solids, dissolved solids, and coarse organic matter Cs-137 concentrations since 2011. The study area includes four headwater basins and four river basins (eight sites in total) in the Kuchibuto River watershed in the Yamakiya district of Fukushima Prefecture, located approximately 35 km northwest of the FDNPP.

In the Kuchibuto River watershed, a large inflow of decontaminated soil with low Cs-137 concentrations due to an increase in the amount of bare land caused by decontamination resulted in a rapid decrease in the concentration of suspended-form 137Cs in the decontaminated area in the headwaters and in the upper reaches of the river. However, no clear effect of decontamination was observed in the concentrations of dissolved Cs-137 and Cs-137 in coarse organic matter. Comparison of the slopes of Cs-137 concentrations in the suspended, dissolved, and coarse organic matter showed that the slope of the dissolved form was similar to that of the coarse organic matter in the source watersheds, and similar to that of the SS in the downstream watersheds. These results suggest that the contribution of dissolved Cs-137 from organic matter in small watersheds and that from suspended solids in large watersheds is significant.

How to cite: Onda, Y., Kawano, T., Taniguchi, K., and Takahashi, J.: Dynamic change of dissolved Cs-137 from headwaters to downstream in the Kuchibuto River catchment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6026, https://doi.org/10.5194/egusphere-egu23-6026, 2023.

EGU23-10093 | Posters on site | GI2.2

Riverine 137Cs dynamics and remoralization in coastal waters during high flow events 

Yoshifumi Wakiyama, Hyoe Takata, Keisuke Taniguchi, Takuya Niida, Yasunori Igarashi, and Alexei Konoplev

Understanding riverine 137Cs dynamics during high-flow events is crucial for improving predictability of 137Cs transportation and relevant hydrological responses. It is frequently documented that the majority of 137Cs is exported during high-flow events triggered by intensive rainfall. Studies on 137Cs in coastal seawater suggested that a huge high-flow events resulted in high dissolved 137Cs concentration in seawater. Different temporal patterns of 137Cs concentrations in river water are found in the existing literature on 137Cs dynamics during high-flow events. Although such differences may reflect catchment characteristics, there is no comprehensive analysis for the relationships. This study explores catchment characteristics affecting 137Cs transport via river to ocean based on datasets obtained by sampling campaigns during high-flow events. 137Cs datasets obtained at 13 points in 6 river water systems were subject to the analysis. The analyses intended to explore relationship between catchment characteristics (scale and land use composition) and 137Cs dynamics in terms of variations in concentration, fluxes, and potential remobilization in seawater. We could not find any significant correlations between the parameters of catchment characteristics and mean values of normalized concentrations of 137Cs and apparent Kd. However, when approximating 137Cs concentrations and Kd value as a power function of suspended solid concentration (Y=α X^β), the power of β in the equations for dissolved 137Cs concentration and Kd showed negative and positive correlations with the logarithm of the watershed area, respectively, and the positive β was found when the catchment area was on the order of 100 km2 or larger and vice versa. This indicates that the concentration of dissolved 137Cs tends to decrease with increased water discharge in larger catchments for smaller catchments. These results suggest that the temporal pattern of dissolved 137Cs concentrations depends on watershed scale. 137Cs flux during a single event ranged from 1.9 GBq to 1.1 TBq and accounted for 0.00074% to 0.22% of total 137Cs deposited in relevant catchments. Particulate 137Cs flux accounted for more than 92% of total 137Cs flux, except for Ukedo River basin with a large dam reservoir. R-factor, an erosivity index in the Universal Soil Loss Equation model family, is a good parameter for reproducing sediment discharge and particulate 137Cs flux. Efficiency of particulate 137Cs flux, calculated by dividing the flux by R-factor of event, tended to be high in catchments with relatively low forest cover. Desorption ratio of 137Cs, obtained by 1-day shaking experiment of SS in seawater, ranged from 2.8 to 6.6%. The ratio was almost proportional of ratio of exchangeable 137Cs. The estimated amounts of desorbed 137Cs, obtained by multiplying particulate 137Cs and the desorption ratios, were greater than direct flux of dissolved 137Cs. Reanalysis of riverine 137Cs dataset in high flow events is revealing relationship between catchment characteristics and 137Cs dynamics. Further analyses, such as evaluation of decontamination impacts and inter-catchment comparisons of 137Cs fluxes, are required for better understanding.

How to cite: Wakiyama, Y., Takata, H., Taniguchi, K., Niida, T., Igarashi, Y., and Konoplev, A.: Riverine 137Cs dynamics and remoralization in coastal waters during high flow events, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10093, https://doi.org/10.5194/egusphere-egu23-10093, 2023.

EGU23-10539 | Posters on site | GI2.2 | Highlight

Long-term dynamics of 137Cs accumulation at an urban pond 

Honoka Kurosawa, Kenji Nanba, Toshihiro Wada, and Yoshifumi Wakiyama

It is known that the semi-enclosed water area such as pond and dam reservoir is readily subject to 137Cs accumulation because of the secondary inflow from the catchment area. We present the long-term monitoring data of the 137Cs concentration in bottom sediment and pond water in an urban pond located in the central area of Koriyama City, Fukushima Prefecture to discuss the 137Cs dynamics of the urban pond. The pond was decontaminated by the bottom sediment removal in 2017. The bottom sediment core and pond water were collected in 2015 and 2018-2021. The inflow and outflow water were collected in 2020-2021. The river water around the pond was collected in 2021. The bottom sediment and water samples were measured for 137Cs concentration, particulate size distribution, and N and C stable isotopes. Compared between 2015 and 2018, the 137Cs inventory and 0-10 cm depth of 137Cs concentration in the bottom sediment at 7 points were decreased by 81 % (mean 1.50 to 0.28 MBq/m2) and 85 % (mean 31.5 to 4.8 kBq/kgDW), respectively. Although mean 137Cs inventory in bottom sediment did not drastically change during 2018-2021, its variability became wider. Points with increased 137Cs inventory in bottom sediment showed year-by-year increase in thickness of layer with concentrations higher than 8 kBq/kgDW, a criterion for considered decontamination. The 137Cs concentration in suspended solids (SS) in pond water was lowered after decontamination, although it still remained above 8 kBq/kgDW. The 137Cs concentrations in SS of inflow water were also high, exceeding 8 kBq/kgDW. The 137Cs concentration in SS of the river water around the pond was higher when it passed through the urban area, suggesting that the inflow of particles from urban origin maintained high 137Cs level in the pond. 

How to cite: Kurosawa, H., Nanba, K., Wada, T., and Wakiyama, Y.: Long-term dynamics of 137Cs accumulation at an urban pond, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10539, https://doi.org/10.5194/egusphere-egu23-10539, 2023.

EGU23-10868 | Posters on site | GI2.2

Estimation of annual Cesium-137 influx from the FDNPP to the coastal water 

Shun Satoh and Hyoe Takata

Due to the accident at the Fukushima Daiichi Nuclear Power Plant (1F) in March 2011, radionuclides were introduced into the environment, and one of the release pathways to the ocean is the direct discharge from the 1F (on-going release). This was mainly caused immediately after the accident, but even now, the on-going release is continuing. In this study, firstly we estimated the on-going release of 137Cs from 1F over 10 years after the accident, using the TEPCO’s 137Cs monitoring results in the coastal area around 1F. Secondly, change in the monitoring data related to countermeasures by TEPCO (e.g. construction of iced walls) to reduce the introduction of contaminated water into the ocean or detect 137Cs in nearby seawater, so their effects on the on-going release estimation were also discussed. A box model including inside and outside of the port was assumed for the area around 1F, and the amount of 137Cs in the box was estimated (estimated value: modeled data). Then, the difference between the estimated value and the amount of 137Cs obtained from actual observed concentrations (measured value: monitoring data) was calculated. The result showed that the measured value was higher than the estimated value, suggesting the on-going release from 1F. As for decrease in monitoring data after the countermeasures, it is implied that the estimation of rate of on-going release has been reduced by the countermeasures.

How to cite: Satoh, S. and Takata, H.: Estimation of annual Cesium-137 influx from the FDNPP to the coastal water, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10868, https://doi.org/10.5194/egusphere-egu23-10868, 2023.

EGU23-11671 | Posters on site | GI2.2

Changes in Cs-137 concentrations in river-bottom sediments and their factors in Fukushima Prefecture rivers 

Naoyuki Wada, Yuichi Onda, Xiang Gao, and Chen Tang

The Fukushima Daiichi Nuclear Power Plant accident (FDNPP) in 2011 resulted in the release of large amounts of Cs-137 into the atmosphere. Cs-137 deposited on land was mainly distributed in forests, but some of it has been discharged to the sea through rivers. The dissolved and suspended forms of Cs-137 in rivers have been focused on, and it is known that the discharge mechanism and concentration formation of Cs-137 differ depending on the land use in the river basin. On the other hand, there are few cases that focus on the dynamics of Cs-137 in river bottom sediments. River-bottom sediment is less likely to flow downstream than suspended sediments, so contamination in the downstream area may be long-term.
We will clarify the migration mechanism of Cs-137 in rivers including river-bottom sediment.Therefore, we will analyze data collected from 2011 to 2018 in 89 watersheds in Fukushima prefecture. In analyzing the data, we removed sampling points with brackish water using electrical conductivity and corrected for particle size to standardize the surface area of particles that absorb Cs-137.As a result, it was found that unlike dissolved and suspended forms, the Cs concentration in river-bottom sediments can increase within the initial year. This is related to the average initial deposition in the watershed and the amount of initial deposition at the river-bottom sediment sampling sites, with a tendency to increase with relatively higher initial deposition in the upstream area. It was also known that the decrease in suspended Cs concentration was more pronounced when anthropogenic activities in the watershed were more active, but there was no clear relationship between land use in the watershed and changes in river-bottom sediment Cs concentration. This indicates that suspended sediment Cs concentrations are controlled by initial deposition to suspended sediment production sources, whereas river-bottom Cs concentrations are controlled by multiple factors such as sediment traction and Cs supply from river water.

How to cite: Wada, N., Onda, Y., Gao, X., and Tang, C.: Changes in Cs-137 concentrations in river-bottom sediments and their factors in Fukushima Prefecture rivers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11671, https://doi.org/10.5194/egusphere-egu23-11671, 2023.

EGU23-12670 | ECS | Orals | GI2.2

Minimizing the loss of radioactively contaminated sediment from the Niida watershed (Fukushima, Japan) through spatially targeted afforestation. 

Floris Abrams, Lieve Sweeck, Johan Camps, Grethell Castillo-Reyes, Bin Feng, Yuichi Onda, and Jos Van Orshoven

Government-led decontamination of agricultural land in the Fukushima accident (2011) region has lowered the on-site radiation risk considerably. From 2013 to early 2017, 11.9% of the land in the Fukushima disaster affected Niida watershed in Japan was remediated through topsoil removal. However, this resulted in a 237.1% increase in suspended sediment loads in the river for 2016 compared to 2013.  In contrast, sediment loads decreased by 41% from 2016 to 2017; this can be attributed to the effect of natural vegetation restoration on sediment yield and transfer patterns (Bin et al., 2022). Since radiocaesium firmly binds to the clay minerals in the soil, it is inevitably transported along with the sediments downstream to the river systems. These observations confirm that rapid, spatially targeted interventions, such as revegetation, e.g., through afforestation, have the potential to decrease the magnitude and period of increased exports of contaminated sediments. The CAMF tool (Cellular Automata-based Heuristic for Minimizing Flow) (Vanegas et al., 2012) was originally designed to find the cells in a raster representation of a watershed for which afforestation would lead to a maximal reduction of sediment exports with minimal effort or cost while taking sediment flow from cell to cell into account. In our research, we adapted the CAMF tool to account for the radiocaesium budgets associated with the transported sediments. We applied the approach to the Niida catchment, where land-cover changes in upstream decontaminated regions are detected using drone imagery and linked to increased sediment loads in the Niida river using long-term river monitoring systems. For example In 2014, agricultural land (18.02 km2) was one of the major land uses in the regions where decontamination was ordered, resulting in increased sediment loads from 2014 to 2016. By recognizing both the on- and off-site impacts of the remediation interventions and their temporal dynamics, the modified CAMF tool offers scope for supporting the formulation of spatio-temporal schemes for the remediation of agricultural land. These schemes aim to decrease the radiation risk for downstream communities and minimize the potential recontamination of already decontaminated sites.

How to cite: Abrams, F., Sweeck, L., Camps, J., Castillo-Reyes, G., Feng, B., Onda, Y., and Van Orshoven, J.: Minimizing the loss of radioactively contaminated sediment from the Niida watershed (Fukushima, Japan) through spatially targeted afforestation., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12670, https://doi.org/10.5194/egusphere-egu23-12670, 2023.

EGU23-13366 | Orals | GI2.2

Similarity of long-term temporal decrease in atmospheric Cs-137 between Chernobyl and Fukushima 

Kentaro Akasaki, Shu Mori, Eiichi Suetomi, and Yuko Hatano

We compare the atmospheric concentrations of Cs-137 after a decade between Chernobyl and Fukushima cases. We plotted 8 datasets on log-log axes (5 cases in Chernobyl and 3 cases Fukushima) and found that they appear to follow a single function.

There have been measured the atmospheric concentration after the Chernobyl accident for more than 30 years [1]. On the other hand, several teams of Japanese researchers have been measured in Fukushima and its vicinity for almost 10 years. [2][3] In this study, we compare 5 sites in Chernobyl (Pripyat, Chernobyl, Baryshevka, Kiev, and Polesskoe) and 3 sites in Fukushima (FDNPP O-6 and O-7, Univ. Fukushima).

We adjust the magnitude of the data because it depends on the amount of the initial deposition. After the adjustment, we plot the 8 cases on a log-log plot. We found that the 8 cases collapse together, with the power index of -1.6. Namely,

C(t) ~ t^{-1.6}.               …(1)

Incidentally, we have been proposed a formula which reproduce the long-term behavior of atmospheric concentration at a fixed location as

C(t) = A exp(-bt) t^{-4/3}    …(2)

where A is a parameter which relates to the amount of the initial deposition and b as the reaction rate of all the first-order reactions (including the radioactive decay rate, the vegetation uptake rate, the runoff rate, etc). We will investigate the difference in the power-law index in Eq. (1) and (2). The parameter b is highly dependent on the environment. When we take a proper value of b, the apparent decrease of the concentration will change from t^{-4/3}. We may make the apparent power-index close to -1.6.

 

[1] E. K. Garger, et al., J. Env. Radioact., 110 (2012) 53-58.

[2] A. Watanabe, et al., Atmos. Chem. Phys. 22 (2022) 675-692.

[3] T. Abe, K. Yoshimura, Y. Sanada, Aerosol and Air Quality Research, 21 (2021) 200636.

How to cite: Akasaki, K., Mori, S., Suetomi, E., and Hatano, Y.: Similarity of long-term temporal decrease in atmospheric Cs-137 between Chernobyl and Fukushima, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13366, https://doi.org/10.5194/egusphere-egu23-13366, 2023.

EGU23-13486 | ECS | Posters virtual | GI2.2

Distributions of tritium in the marine water and biota around Rokkasho Reprocessing Plant 

Satoru Ohtsuki, Yuhei Shirotani, and Hyoe Takata

For decommissioning of Fukushima Daiichi Nuclear Power Station (FDNPS), it is one of the biggest problems to treat the radioactive contaminated stagnant water in the building. It is difficult to remove H-3 from the contaminated water by only Advanced Liquid Processing System (ALPS) treatment. Thus, the Japanese Government announced to release the ALPS treated water containing H-3. To predict the alteration of the dose rate of the marine biota by the change of H-3 concentration in marine water after the release of ALPS water, it is necessary to understand the dynamics of H-3 in marine ecosystem. In this study, we studied the behavior of H-3 in the marine environment (water and biota) off Aomori and Iwate prefectures from FY2003 to FY2012, as the background data of the Pacific Ocean along the coast of the North East Japan. To clarify the dynamics of H-3 in marine biota, we compared H-3 and Cs-137. Excluding the period of the intermittent test operation of the Rokkasho Reprocessing Plant (FY2006-FY2008), the concentration of H-3 in seawater, tissue free water tritium (TFWT) and organically bound tritium (OBT) were 0.052-0.20 Bq/L with a mean of 0.12±0.031 Bq/L, 0.050-0.34 Bq/kg-wet with a mean of 1.1±0.039 Bq/kg-wet and 0.0070-0.099 Bq/kg-wet with a mean of 0.042±0.019 Bq/kg-wet, respectively. Before the FDNPS accident (FY2003-FY2010), Cs-137 concentration in seawater and marine biota were 0.00054-0.0027 Bq/L with a mean of 0.0016±0.00041 Bq/L and 0.022-1.8 Bq/kg-wet with a mean of 0.090±0.037 Bq/kg-wet, respectively. Concentration Ratio (CR), the ratio of the concentration of marine biota and seawater for TFWT, was to be 0.34-2.37 with a mean of 0.97±0.31 in all spices, meaning the concentration of marine biota was almost equal to seawater. For Cs-137, CR were 46-78 with a mean of 56±22. We compared CRs for TFWT of Gadus macrocephalus, Lophius litulon and Oncorhynchus keta with those of Cs-137. Comparing CR-TFWT and CR-Cs-137 for these three species, Spearman-R was <0.4 and p was >0.05, indicating that the dynamics of TFWT and Cs-137 in marine ecology is decoupled.

How to cite: Ohtsuki, S., Shirotani, Y., and Takata, H.: Distributions of tritium in the marine water and biota around Rokkasho Reprocessing Plant, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13486, https://doi.org/10.5194/egusphere-egu23-13486, 2023.

EGU23-15515 | Posters on site | GI2.2

137Cs transport flux to surface water due to shallow groundwater discharge from forest hillslope 

Yuma Niwano, Hiroaki Kato, Satoru Akaiwa, Donovan Anderson, Hikaru Iida, Miyu Nakanishi, Yuichi Onda, Hikaru Sato, and Tadafumi Niizato

Groundwater systems and surface water can interact in a complex manner that influences catchment discharge, which then becomes more complex in forest slopes. A large amount of Radioactive cesium (137Cs) deposited on forests due to the Fukushima Daiichi Nuclear Power Plant accident remains in terrestrial environments and is transported downstream as suspended or dissolved forms by surface water. Generally, the concentration of dissolved 137Cs in surface water increases especially during runoff. While the leaching behavior of 137Cs from contaminated forest materials and soils to surface water has been heavily studied, the influence of 137Cs concentration in shallow groundwater systems in forest slopes have not been investigated. Therefore, detailed hydrological observations of groundwater on a forest hillslope will enable quantitative analysis of the influence of groundwater flow on the formation of dissolved 137Cs concentrations in surface water during base flow and during runoff. Our results showed that the dissolved 137Cs concentration in surface water increases during water discharge. The average concentration of dissolved 137Cs in shallow groundwater was 0.64 Bq/L, which was higher than that in surface water (average 0.10 Bq/L). Furthermore, it was also observed that a part of the shallow groundwater on the slope moves toward the river channel at the time of water runoff. This suggests that shallow groundwater may have flowed into the surface water during the outflow and contributed to the increase of 137Cs in the surface water. In this study, the contribution of groundwater in forest slopes to the dissolved 137Cs concentration in surface water was estimated using the hydrodynamic gradient distribution of groundwater in forest slopes and the measured dissolved 137Cs concentration in groundwater.

How to cite: Niwano, Y., Kato, H., Akaiwa, S., Anderson, D., Iida, H., Nakanishi, M., Onda, Y., Sato, H., and Niizato, T.: 137Cs transport flux to surface water due to shallow groundwater discharge from forest hillslope, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15515, https://doi.org/10.5194/egusphere-egu23-15515, 2023.

EGU23-2006 | ECS | Orals | HS5.7

Soft-linking climate-land-water-energy assessment and planning models for sustainable development in rural Africa: preliminary results from the LEAP-RE RE4AFAGRI project 

Giacomo Falchetta, Muhammad Awais, Edward Byers, Vittorio Giordano, Gregory Ireland, Francesco Semeria, Marta Tuninetti, Adriano Vinca, and Ackim Zulu

In rural areas of Africa most communities live in poverty and lack access to services such as electricity and clean cooking fuels, water supply that is safe for human use, sufficient and nutritious food, crop irrigation systems, and appliances and services that can foster income generation. Promoting sustainable development requires an integrated understanding and planning along such dimensions. In the context of the RE4AFAGRI (“Renewables for African Agriculture”) project of  LEAP-RE (Long-Term  Joint  Research  and  Innovation  Partnership  on  Renewable  Energy between  the European Union and the African Union), four models representing land-water-crop-food-energy requirements and dynamics (WaterCROP, M-LED, OnSSET and MESSAGE-NEST) are calibrated and soft-linked. The ultimate aim is to enable a multi-scale, multi-sectoral assessment and planning of technologies and policies that can promote integrated sustainable development in the region. Here we present preliminary results for a set of scenarios in the country-study of Zambia. Results can inform both public decision-makers and private companies engaging in those sectors. The approach and open-source modelling platform are readily scaled and adapted to other countries and regions.

How to cite: Falchetta, G., Awais, M., Byers, E., Giordano, V., Ireland, G., Semeria, F., Tuninetti, M., Vinca, A., and Zulu, A.: Soft-linking climate-land-water-energy assessment and planning models for sustainable development in rural Africa: preliminary results from the LEAP-RE RE4AFAGRI project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2006, https://doi.org/10.5194/egusphere-egu23-2006, 2023.

EGU23-3075 | Orals | HS5.7

Water-energy-food-ecosystem nexus governance: methodological aspects of the assessement of supportive and restrictive contexts 

Isabelle La Jeunesse, Caro E. Mooren, Stefania Munaretto, Frank Hüesker, Claudia Cirelli, Ingrid Canovas, Eva Sievers, and Kaoutar Mounir

Managing water resources in a sustainable way means, a fortiori in the context of increasingly visible climate change impacts, taking into account decisions made by other sectors having a significant effect on the availability and quality of water. Water quality and quantity are often affected by the energy sector on the one hand, and agriculture and food production on the other. Moreover, ecosystem requirements, such as minimum ecological flows or water quality, should always be considered. Thus, facing climate change impacts calls for increasing water-energy-food-ecosystems nexus considerations.

This being said, how can managers of these natural resources and stakeholders using them consider intersectoral coherence needs? Are these needs only theoretical or are they reflected by concrete actions in practice? Last but not least, how to assess the state of WEFE nexus governance in territories?

In order to address these questions, the present paper describes the methodological aspects of the WEFE nexus governance assessment tool (NXGAT) co-developed in the NEXOGENESIS project (H2020-funded). This tool assesses the state of the WEFE nexus governance in catchments. The goal of the NXGAT is to highlight what is actually supportive and what is actually restrictive to WEFE nexus governance.

The NXGAT is the first step in the WEFE nexus governance approach (Hüesker et al., 2022 ; Mooren et al., 2022) aiming at developing WEFE nexus policies. The NXGAT lays the foundation for cross-sectoral dialogue by both raising awareness and identifying solutions for more WEFE nexus governance.  The NXGAT assesses five dimensions (levels and scales; actors and networks; problem perspectives and goal ambitions; strategies and instruments; and responsibilities and resources) and five qualities (extent, coherence, flexibility, intensity of action, and fit) of the governance system. The tool is implemented in the Lielupe transboundary catchment (Lithuania-Latvia) by a team of transdisciplinary experts during face-to-face interviews. Interviewees are selected to cover the multi-scalar levels of all sectors.

The results of the implementation in the Lielupe transboundary catchment provide preliminary results on the efficiency of the method and the importance of the preparatory phases of the field investigation. The implementation of the NXGAT contributed to both underline blockages and leverages to urge for more intersectoral governance in this case study.

How to cite: La Jeunesse, I., Mooren, C. E., Munaretto, S., Hüesker, F., Cirelli, C., Canovas, I., Sievers, E., and Mounir, K.: Water-energy-food-ecosystem nexus governance: methodological aspects of the assessement of supportive and restrictive contexts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3075, https://doi.org/10.5194/egusphere-egu23-3075, 2023.

Nexus research is advancing from knowledge creation towards public awareness and inclusiveness for civil society, public-private partnerships, and knowledge partners. Nexus research was mainly focused on a better understanding of interlinkages between the relevant resources at stake (e.g., water, energy, food, and ecosystems), the focus is increasingly searching for building communities, training, and career development. 

Research on the WEFE nexus increasingly aims to create platforms building capacity among institutions, knowledge partners, and capacity development. Educational and learning programs are developed by hot spots of the nexus. Expanding transdisciplinary research methods could facilitate building a community and network of nexus professionals. Capacity development and awareness are also critical for the successful planning and implementation of nexus practices. Some successful examples of knowledge creation for inclusiveness are shared.  The presentation will identify some key enablers and measures to advance the nexus in practice. Nexus research benefits from advancing along this route.

 

How to cite: Brouwer, F.: Nexus research for sustainability and inclusiveness in practice, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4370, https://doi.org/10.5194/egusphere-egu23-4370, 2023.

EGU23-5114 | Posters on site | HS5.7

Analysis of Transboundary Water-Food Nexus based on Physical-Virtual Water and Food Trade Network 

Sanghyun Lee, Makoto Taniguchi, Naoki Masuhara, Seung-Hwan Yoo, and Yun-Gyeong Oh

This study aimed to analyze the interaction among watershed, food-producing, and food-demanding areas through the connected system of physical-virtual water flows and local food networks in terms of the transboundary water-food nexus, even though they might not be geographically connected. Here, we analyzed the potential food network of local rice among 47 prefectures in Japan using the gravity model and estimated the physical-virtual water flows (PVWFs) by lining the physical water flow in food-producing areas and virtual water flow embedded in the food network. Through in-and out-degree centralities of the food network, we found that the results of degree centrality revealed which prefecture was more influenced by the changes in self-supply ratios (SSRs) of local rice. As all prefectures intended to increase consumption of local rice that was produced in their area, the scale of the food network was reduced, as shown by the decrease in in-and out-degree centralities. Based on the food network, we analyzed the dependency of food-demanding areas on each watershed based on a connected system of PVWFs. In a case study of the Kansai region, the northern watershed directly affected Hyogo, which was also indirectly influenced by Osaka in terms of PVWFs. In the food network with 20% SSR, the PVWF was estimated to be 189.17 x 106 m3·yr-1 from the northern watershed to Osaka in the food-producing area of the northern watershed, showing higher interaction of Osaka with the northern watershed than with other watersheds.

How to cite: Lee, S., Taniguchi, M., Masuhara, N., Yoo, S.-H., and Oh, Y.-G.: Analysis of Transboundary Water-Food Nexus based on Physical-Virtual Water and Food Trade Network, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5114, https://doi.org/10.5194/egusphere-egu23-5114, 2023.

EGU23-5826 | ECS | Orals | HS5.7

Systems Innovation Approach: stakeholders’ involvement for a climate resilient region, a Living Lab at the Main River basin 

Teresa Pérez Ciria, Raul Wood, Marion Zilker, Gunnar Braun, and Ralf Ludwig

Climate change poses major challenges globally and is likely to exacerbate competition for water, land, and energy resources. In the Main River Basin (Germany), this will have considerable consequences for agriculture, forestry, water, and energy management. At present, most adaptation measures are sector-focused, but the challenges are interconnected. The region is at risk for being pushed beyond its resilience threshold and therefore, a holistic and multi-sectoral strategy is urgently needed to achieve a new level of responsiveness to cope with climate change impacts.

The co-design and co-production of science-driven technical, social, and cross-sectoral innovations and governance is required to build new and climate resilient transformation pathways. A systemic transformation of the region requires time and broad societal support, which must be considered when formulating development paths. To address these challenges, Systems Innovation Approach (SIA) is implemented. This method aims at going beyond the immediate problems to better understand the underlying patterns, and how we can learn and adapt as the system continues to change. The Main River basin is one of the nine pilot areas of the EU funded ARSINOE project (Climate-resilient regions through systemic solutions and innovation) that are implementing innovative technological approaches. Stakeholders’ engagement is ensured through the so-called Living Labs. In the ARSINOE project, Living Labs are a participatory research tool often used in planning, product design and innovation which brings together a collective of key stakeholders to explore a focal issue. Living Labs act as open innovation spaces which foster co-creation with users and the focus is to better solve stakeholder needs.

Through a series of workshops supported by SIA tools (mental mapping of interconnected challenges, future common vision using Sustainable Development Goals (SDGs) as guiding principles, backcasting) we have created an open atmosphere with committed participants that are willing to collaborate to tackle future climate challenges in the Main River region. This contribution presents our successful experience turning research into practice, lessons learnt and challenges we faced to ensure the participants’ engagement.

The presented study is supported by the project ARSINOE (GA: 101037424), funded under EU’s Horizon 2020 research and innovation programme.

How to cite: Pérez Ciria, T., Wood, R., Zilker, M., Braun, G., and Ludwig, R.: Systems Innovation Approach: stakeholders’ involvement for a climate resilient region, a Living Lab at the Main River basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5826, https://doi.org/10.5194/egusphere-egu23-5826, 2023.

Measures that aim to reduce greenhouse gas emissions also have impacts on achieving other Sustainable Development Goals (SDGs). Given the enormous challenge of achieving the goals of the Paris Agreement and the SDGs, insight into these impacts provides information on how to improve feasibility of climate change mitigation measures by maximizing the co-benefits and managing the risks of possible trade-offs across SDGs. In this paper, we explore the impact of twenty promising climate mitigation measures on achieving the other SDGs for eleven world regions. Using the IMAGE modelling framework, the paper explores the GHG emissions reduction potential of these measures aggregated by sector under three scenarios. Based on peer-reviewed articles, the impact of the measures on other SDGs is assessed for the top three sectors with the highest GHG reduction potential in each region. We conclude that the number of synergies between the selected climate change mitigation measures and other SDGs dwarf the number of trade-offs in all regions. The magnitude of these synergies and trade-offs, however, varies by regional and socio-economic context. In high- and middle-income regions, the mitigation measures show few trade-offs that are generally associated with technology choices that could aggravate inequality and impact biodiversity. In low-income regions, some measures, especially land-use related ones, could interfere with efforts to reduce poverty, end hunger and improve well-being, if not complemented by additional policies that aim to protect the poor from increasing food and energy prices.

How to cite: Dagnachew, A. and Hof, A.: Climate change mitigation and SDGs: modelling the regional potential of promising mitigation measures and assessing their impact on other SDGs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7411, https://doi.org/10.5194/egusphere-egu23-7411, 2023.

EGU23-7541 | ECS | Orals | HS5.7

Towards climate resilience: paving dynamic adaptation pathways for regional climate change hot-spots 

Dionysios Nikolopoulos, Iosif Spartalis, Christodoulos Pantazis, Nikos Pelekanos, Georgios Moraitis, Klio Monokrousou, and Christos Makropoulos

Climate change is one of the biggest challenges of recent times, with worldwide economic, societal, and environmental impacts. In response to these challenges, the European Union (EU) proposed the EU Green Deal which sets a blueprint that commits on transforming the EU into the first climate neutral continent by 2050. To this end, innovative solutions for climate-change adaptation and mitigation measures must be implemented in regional and local scales. The H2020 Green Deal project IMPETUS aims to develop and validate a coherent multi-scale, multi-level, cross-sectoral adaptation framework for climate change, paving the way towards a climate-neutral and sustainable future. This will be achieved by building on resilience knowledge and by co-designing together with local communities and stakeholders, innovative packages of methodological, technical, governance and financial solutions. Two such solutions developed within the project are a) the strategic resilience and multi-hazard management tool for identifying dynamic climate adaptation pathways and b) the climate change hot-spot identification and prioritization tool. Through a co-creation approach, stakeholders identify region-specific indicators and metrics of interest that describe climate risk exposure, vulnerability, and adaptation capacity. The hot-spot analysis based on these metrics utilizes collections of spatiotemporal datasets, including future climate scenarios and projections, that describe key parameters from the human and climate dimensions, able to identify hot-spots associated with different climatic and socioeconomic futures. The hot-spot explorer tool is an EU-wide web service and can be used as a screening tool for policymakers to prioritize regions for development of regional adaptations pathways, using the dynamic adaptation pathways tool. A regionally suitable pallet of intervention measures is identified from stakeholder engagement. The pallet is stress-tested for assessing regional climate resilience, under a multitude of different future scenarios, with the objective to generate pathways of progressive implementations of intervention packages that improve the specified indicators and metrics. Some of the intervention options are also operationalized in pilot case studies within the project, such as the employment of sewer mining units in the wastewater system of East Attica for water reuse. The pathways are dynamic and adaptative to changing future conditions, as there are a) key monitored parameters for a region with alarms associated to decision points involving intervention measure implementations, and b) a contingency response module that supports stakeholders to select interventions from different pathways. These tools engage policymakers and stakeholders in order to identify climate change hot-spots within EU, prioritize them, identify suitable intervention measures, and analyze their regions to generate strategic plans for adaptation pathways towards the common climate resilience goal.

Acknowledgement

This work is supported by IMPETUS research project, which received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement  No. 101037084.

How to cite: Nikolopoulos, D., Spartalis, I., Pantazis, C., Pelekanos, N., Moraitis, G., Monokrousou, K., and Makropoulos, C.: Towards climate resilience: paving dynamic adaptation pathways for regional climate change hot-spots, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7541, https://doi.org/10.5194/egusphere-egu23-7541, 2023.

EGU23-9994 | ECS | Orals | HS5.7

Bringing knowledge closer to practice: an inferential analysis of EU climate change policies and measures 

Nikos Pelekanos, Dionysios Nikolopoulos, Georgios Moraitis, and Christos Makropoulos

In the context of climate change, European Member States are committed to developing policies and taking corresponding adaptation measures. In this direction, every two years, the European Environment Agency (EEA) publishes an extensive dataset related to climate policies and measures (PaMs) reported in Europe and generated by European research projects, with the aim of improving and disseminating the information covering all actions aimed at reducing GHG emissions. In this study, an inferential data analysis is conducted on the PaMs dataset, setting as the variable of interest the reported quantified GHG emissions savings of each PaM and inferring its variance through a set of related explanatory qualitative factors (i.e., type of measure, sector of policy, related entities, implementation period etc.) together with their higher-level interactions. This is achieved by employing a number of widely used statistical techniques for the analysis of multi-factor data, such as regression analysis, hypothesis testing, influence diagnostics and variable selection methods to (a) investigate the significance and effect of the factors in relation to GHG emissions and (b) model the relationships between the variables of interest. The resulting analysis aims to obtain practical insights from a retrospective view of a wide number of PaMs and generalize their response in a descriptive and explicable way. This will allow the interested parties to gain interpretable feedback from existing measures applied in practice and subsequently ‘feed back’ new knowledge on climate adaptation decision making.

This work is supported by IMPETUS research project that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 101037084.

How to cite: Pelekanos, N., Nikolopoulos, D., Moraitis, G., and Makropoulos, C.: Bringing knowledge closer to practice: an inferential analysis of EU climate change policies and measures, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9994, https://doi.org/10.5194/egusphere-egu23-9994, 2023.

EGU23-10472 | ECS | Posters virtual | HS5.7

Scenario discovery with an integrated assessment model to identify robust, policy-relevant scenarios for capacity expansion in Latin America 

Jacob Wessel, Jonathan Lamontagne, Gokul Iyer, and Thomas Wild

The ongoing global transition to a deeply decarbonized electricity system represents a complex problem. Deep uncertainty in the future pathways of power system capacity expansion and interactions across sectors has led stakeholders to seek out robust methods capable of informing multi-scale, multi-sector tradeoffs among policy pathways within the energy-water-food nexus. In this study, scenario discovery is applied to a large scenario ensemble generated using a global-scale integrated assessment model with a regional focus on Latin America. Scenario discovery is a powerful method for identifying robust, policy-relevant scenarios from large, many-dimensional ensembles of model realizations. Here, ten uncertain sensitivity factors consistent with previous analyses are varied within the model configuration, representing technological costs and efficiencies, advanced electrification, institutional factors, and national climate pledges, among others. The resulting scenario ensemble maps out the impacts of a combinatorial time-evolving uncertainty space defined by these sensitivity factors, using generation mix, electricity cost, energy burden, and energy intensity as power system performance metrics. Additional metrics are utilized to explore cross-sectoral implications of scenarios. The scenario discovery analysis identifies the key global drivers of regional outcomes in Latin America, as well as tradeoffs and synergies regarding climate change mitigation and the future evolution of the Latin American electric power system. Our results underscore the importance of considering coupled systems and the advantages of large-scale scenario ensembles in capacity expansion analyses.

How to cite: Wessel, J., Lamontagne, J., Iyer, G., and Wild, T.: Scenario discovery with an integrated assessment model to identify robust, policy-relevant scenarios for capacity expansion in Latin America, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10472, https://doi.org/10.5194/egusphere-egu23-10472, 2023.

EGU23-11101 | ECS | Orals | HS5.7

Supply and demand assessment and mismatch analysis of ecosystem services to support sustainable land management 

Jiwon Kim, Mina Hong, Sol-E Choi, Cholho Song, Chul-Hee Lim, Yun Eui Choi, and Woo-Kyun Lee

Due to the land degradation, the land use conflicts have intensified, and there is an increasing necessity to adapt sustainable land management. Sustainable land management deals with the demands for land in terms of not only human society but also the nature conservation and biodiversity. To persue and realize sustainable land management, the indicators and evaluation system are necessary, and ecosystem services has emerged as the proper indicator for sustainable land management. This study focused on the balance between the demand and supply of ecosystem services. If the balance between them was maintained or supply exceeded demand, the land can be assessed to be managed sustainably. In this study, CO2 sequestration, Heat mitigation, and water provision were assessed as ecosystem service in South Korea. The supply of each ecosystem service was evaluated by using related models which had been developed and used widely in previous studies. The demand of each ecosystem service was defined based on specific figures which had already suggested as policy goals in South Kroea in purpose of drawing social consensus. Afterwards, the ecosystem services supply and demand ratio (ESDR) were calculated to show the balance between supply and demand quantified by region. As a result, the exessive demand for CO2 sequestration service was found compared to supply. The supply of heat mitigation service was found to be sufficient for the demand nationwide. However, in specific areas such as cities, the demand was higher than the supply. In the case of water provision service, the national demand was being met by some regional suppliers. Through these results, it is possible to find out the ecosystem services that need to be supplemented spatially and regionally, and ultimately, it is expected to support the establishment of urban space, green space, and environmental planning at the regional and national levels.

How to cite: Kim, J., Hong, M., Choi, S.-E., Song, C., Lim, C.-H., Choi, Y. E., and Lee, W.-K.: Supply and demand assessment and mismatch analysis of ecosystem services to support sustainable land management, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11101, https://doi.org/10.5194/egusphere-egu23-11101, 2023.

EGU23-12105 | Orals | HS5.7

A probabilistic framework to assess resilience in regional water systems - exploring the impact of circular water strategies 

Dimitrios Bouziotas, Dionysios Nikolopoulos, Panagiotis Dimas, Jos Frijns, and Christos Makropoulos

Contrary to the ‘make-use-dispose’ linearity seen in conventional resource management, circular economy design principles have been proposed as an  alternative that reduces waste and promotes efficiency. These principles find use in water as well, offering an alternative against centralized water systems planning and management. Despite the intrinsic links between circularity and resilience, few studies have advanced the identification and discussion of linkage beyond a theoretical or conceptual level. Moreover, few studies have estimated resilience with a probabilistic approach to include the inherent future uncertainty located simultaneously at source and demand level. In this study, a probabilistic framework to assess resilience for regional systems across multiple domains (drinking water, wastewater and drainage) is presented. The framework is based on stress-testing using an urban water cycle model, paired with reliability-based Key Performance Indicators (KPIs) that describe system resilience for each domain and for several different stress-testing factors (stressors). For its practical implementation, the framework is then applied to the provincial case study of Delfland, the Netherlands, where different circular water strategies are evaluated in terms of their overall resilience, (a.) firstly deterministically to explore the impact of individual stressors, and (b.) probabilistically to evaluate system performance against future uncertainty. The results quantitatively demonstrate that circular water options lead to water systems of increased resilience. The more circular dimensions are addressed through interventions and management strategies, the more robust resilience profiles become across different urban water cycle domains, thus securing regional water systems against future uncertainty.

How to cite: Bouziotas, D., Nikolopoulos, D., Dimas, P., Frijns, J., and Makropoulos, C.: A probabilistic framework to assess resilience in regional water systems - exploring the impact of circular water strategies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12105, https://doi.org/10.5194/egusphere-egu23-12105, 2023.

EGU23-12166 | ECS | Posters on site | HS5.7

Enabling far-reaching living labs through regional Digital Twins 

Georgios Moraitis, Christodoulos Fragkoudakis, Spyridon Tsattalios, Dionysios Nikolopoulos, Nikos Pelekanos, Klio Monokrousou, and Christos Makropoulos

The current and future landscape of our societies is predominantly governed by urgent (and interconnected) resilience challenges such as climate change adaptation, resource efficiency and sustainable WEFE nexus management. To overcome those challenges, the European Union (EU) has set the blueprints of transformational changes with the European Green Deal, that builds on research and innovation to meet the objectives. Despite advances in the field, the uptake pace of relevant innovations is often hindered by the narrow communication paths among research, public administration and citizens -who are the end beneficiaries. This work utilizes the capabilities of Digital Twins (DT) to connect hard and soft sensors with environmental and infrastructure models at regional scale, to create a central hub for related data and knowledge to be turned into action in a co-creation process. By building on existing data driven platform initiatives by the Ministry of Environment and Energy and the Decentralized Administration of Attica, we build the DT of the Region of Attica to provide: (i) access to relevant datasets (environmental, climatic, uses of resources etc.), (ii) access to relevant climate adaptation services (e.g. climate services, services to farmers, services to municipalities), (iii) links to local and regional Communities of Practice (CoP) and (iv) a repository for demonstrations of climate adaptation innovations within the region. This knowledge collaboration scheme forms a living lab constellation that allows rapid and far-reaching sharing, accumulation, transformation, and co-creation of knowledge among the administration parties and local case studies’ stakeholders. Like ancient sailors who used constellations to navigate along route, our modern societies can use the living lab constellations of the regional DT to chart evidence-based pathways towards climate resilience and sustainable WEFE management. This dynamic and expandable ecosystem aims to speed up the introduction of climate adaptation innovations, connect knowledge and bring research closer to practice by allowing for a re-wiring of culture, where science and co-creation are perceived as necessary for successful policy making. 

Acknowledgment: This work is supported by IMPETUS research project that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 101037084.

How to cite: Moraitis, G., Fragkoudakis, C., Tsattalios, S., Nikolopoulos, D., Pelekanos, N., Monokrousou, K., and Makropoulos, C.: Enabling far-reaching living labs through regional Digital Twins, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12166, https://doi.org/10.5194/egusphere-egu23-12166, 2023.

EGU23-12376 | Orals | HS5.7

On building a general framework for assessing food security risk under probabilistic socioeconomic scenarios 

Georgios Papayiannis, Phoebe Koundouri, Achilleas Vassilopoulos, and Athanasios Yannacopoulos

Food security is a key issue in sustainability studies. In this work, a general framework for providing detailed probabilistic socioeconomic scenarios as well as predictions concerning food security is proposed. Our methodology builds (a) on the Bayesian probabilistic version of world population prediction model and (b) on the dependencies of food needs and food system capacities on key drivers, such as population, gross domestic product (GDP) and other socioeconomic and climate indicators. In this perspective, the concept of the recently developed convex risk measures involving model uncertainty is employed for the construction of a risk assessment framework in the context of food security. The proposed method provides within and across the various probabilistic scenarios predictions and evaluations for food security risk. Our methodology is illustrated by studying food security and quantifying the occurring risk in Egypt and Ethiopia up to the year 2050, in the combined context of the Shared Socioeconomic Pathways (SSPs) and the Representative Concentration Pathways (RCPs).

How to cite: Papayiannis, G., Koundouri, P., Vassilopoulos, A., and Yannacopoulos, A.: On building a general framework for assessing food security risk under probabilistic socioeconomic scenarios, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12376, https://doi.org/10.5194/egusphere-egu23-12376, 2023.

EGU23-12746 | ECS | Posters virtual | HS5.7

Water-Energy-Food nexus in Algeria; Ain Temouchent case study 

Leila Mostefaoui

Given the complexity of the interactions between water, energy, and food, any alteration to one sector can have impacts on the other sectors of the system.(Sušnik et al., 2018).Scientists are increasingly recognizing the need for an integrative approach to planning and managing resources. Hoff explained that several factors have influenced the demand for water, energy, and food, and listed the following; population growth, sustainable development, climate change, degradation, and scarcity of resources.(Hoff & Ulrich, 2017)

Algeria is ranked 1st among the Arab countries which have exceeded two-thirds of the way to achieving the SDGs (Dahan et al., 2019.), but according to Hoff (Hoff & Ulrich, 2017), the countries in the MENA region have not made remarkable progress in adopting the nexus approach due to several constraints such as lack of experience and insufficient management planning. ((Hoff & Ulrich, 2017).  As part of establishing the nexus approach in Algeria, we have selected the region of Ain Temouchent as a case study known for its agricultural vocation.

Ain Temouchent is located on located in the northwestern of Algeria, 520 km from the capital Algiers, and a hundred kilometers from the border Moroccan. And limited: to the North, by the Mediterranean Sea, to the South West, by Tlemcen, to the South East, Sidi Bel Abbes, and, to the east, by Oran. The region area is about 2,376 km² with a façade sea of 84 km and the population is over 406,000. The agricultural sector represents 15.22%, and the construction sector employs 14.19% of the employed population. The region of Ain-Temouchent is characterized by a Mediterranean climate with a hot summer and a temperate winter. The intensification of agricultural production in this region has led to the overexploitation of groundwater resources, and the establishment of a combined cycle thermal power station has accentuated its path towards a more considerable development, following its satisfaction in electrical energy. The establishment of a reverse osmosis desalination plant (Benisaf Water Company) with a production capacity of 200,000m3/day significantly alleviated the crisis situation, but its energy consumption and environmental impact raise several questions

Considering all these segments, one of the objectives of the study is to determine the key links between segments of the Nexus and understand the dynamics between them using System Dynamics Modeling. ((Aliyev et al., 2019))

This work aims to determine the links between water, food, and energy and to analyze the dynamics between them, also to propose solutions and recommendations for developing effective policies for the region.

 

How to cite: Mostefaoui, L.: Water-Energy-Food nexus in Algeria; Ain Temouchent case study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12746, https://doi.org/10.5194/egusphere-egu23-12746, 2023.

EGU23-12902 | Orals | HS5.7

Experiences from storm surge flood damage modelling driven by local decision makers 

Martin Drews, Kirsten Halsnæs, Per Skougaard Kaspersen, and Bodil Ankjær Nielsen

A large part of the current research on flood damage costs build on a similar methodological framework across studies that integrates climate data (hazard), flood modelling (exposure), damage cost assessments (impact) and calculate risks as the product of the likelihood of events and their consequences. A key question here is how relevant such a methodological framework is in relation to the perspectives of decision makers on establishing safe standards for investments in climate change adaptation in the context of the large uncertainties surrounding both estimates of the extreme event probability and on the damages of these. Particular issues that are often raised by decision makers are related to how extreme precipitation and storm surge levels could be, and on how well the damages of such events are represented in damage estimates recognizing the limitations of monetary evaluations as well as risk preferences of decision makers.

The paper is addressing how the gap between conventional approaches applied to hazard and impact modelling and the needs and practice of decision makers can be diminished based on the experiences with the development and application of a detailed object based spatial DamageCost Model for storm surges. The model has been widely applied by Danish local governments as a basis for developing adaptation plans. Soon after the first version of the model was released, local Danish governments took over leading the model development from a user perspective in a close ongoing dialogue with DTU and the engineering consultants LNH Water, which through several projects, including the EU ARSINOE project continue to support further technical development and model use.

Experiences from how the model development have been inspired by decision maker perspectives gained through model use are reported based on case studies for the Danish cities of Esbjerg, Odense, and Aabenraa.

How to cite: Drews, M., Halsnæs, K., Skougaard Kaspersen, P., and Ankjær Nielsen, B.: Experiences from storm surge flood damage modelling driven by local decision makers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12902, https://doi.org/10.5194/egusphere-egu23-12902, 2023.

EGU23-13100 | ECS | Orals | HS5.7

Enhancing the resilience of intermittent water supply systems in Khan Younis, Gaza Strip. Knowledge transfer and lessons learned from the Gaza H2.0 project 

Andrea Cominola, Ivo Daniel, David Tilcher, Ahmed J. S. Alasmar, Rami M. M. Ziara, and Giovanni Pedron

Future water security in Palestine is challenged by the compound effect of water scarcity, operational inefficiencies in water supply infrastructure, and the unstable geo-political setting. Among these factors, water losses represent a major challenge to the environmental sustainability and financial stability of water resources management in the area. The Palestinian Water Authority estimated the amount of non-revenue water (NRW) in the Gaza Strip to approximately 35.7 million cubic meters in 2018. This is equivalent to a direct loss of 37.6% of the total water supplied, further indirectly implying inefficient use of water-related energy and resources to treat and distribute water.

Water loss reduction and more sustainable water supply are key priorities in Khan Younis, the second most populated city in the Gaza Strip. Water supply and sanitation services in Khan Younis are managed by the Khan Younis Municipality (KYM). The KYM water distribution system is currently operated with an intermittent water supply scheme based on empirical and expert-based knowledge. The water loss rate in Khan Younis is rather uncertain and different estimates exist. However, the average water consumption from data provided by KYM in early 2021 was estimated to 74.7 liters per capita per day (lcd), which resides in the range recommended by the World Health Organization to meet the basic water needs, while the daily amount of water supplied via the distribution network was on average 99.5 lcd, indicating a NRW rate of approximately 25%.

In this work, we discuss lessons learned from the ongoing EU funded project “Gaza H2.0: Innovation and water efficiency” which aims at promoting efficient and sustainable water supply and demand, along with knowledge transfer to enhance resilience against water scarcity in the Gaza Strip. First, we analyse the gaps between research and practice which emerged in the project while updating the hydraulic model of the KYM water distribution. A rich body of literature highlights that building and calibrating a hydraulic model of a water distribution network is not a straightforward task that depends greatly on available data, calibration techniques, and modeler’s expertise. This was proven true for building the KYM water distribution network model, as an up-to-date inventory of network components was not available and only limited historical data were recorded. Thus, an extensive surveying campaign was run in 2021 via the installation of 51 pressure sensors logging data with a 1-min frequency throughout the 27 distribution zones in the network. As a result, sufficient measurement data was recorded to perform an initial calibration of the hydraulic model. However, some components of the network remain ungauged. We will thus discuss lesson learned and propose recommendations to enhance hydraulic model calibration for KYM and similar networks. Second, we will describe and discuss the strategies planned and invoked during the Gaza H2.0 project to foster knowledge transfer to and increase involvement from all stakeholders. These actions aim to guarantee the long-term sustainability of the technological solutions proposed in the project, such that they can serve as a starting point to address future climate and infrastructure challenges.    

How to cite: Cominola, A., Daniel, I., Tilcher, D., Alasmar, A. J. S., Ziara, R. M. M., and Pedron, G.: Enhancing the resilience of intermittent water supply systems in Khan Younis, Gaza Strip. Knowledge transfer and lessons learned from the Gaza H2.0 project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13100, https://doi.org/10.5194/egusphere-egu23-13100, 2023.

EGU23-13219 | Orals | HS5.7

Opportunities and Challenges in the Efficient Exploiting of Land, Energy and Water Resources within the Volta and Tana Basins in Africa 

Frank Ohene Annor, Viktoria Martin, Eric Antwi Ofosu, Carlos Guerrero Lucendo, Boniface Akuku, Rafatou Fofana, Nick van de Giesen, and Edo Abraham

The design of strategic investments in water, energy and food (WEF) infrastructures is challenging because the size, location, technology mix and pace of development is made uncertain by multiple factors. For example, the return on investment, which comes long after building a hydropower dam, is made uncertain by local, regional and global climate and socio-economic factors. This is exacerbated by the challenges associated with the impacts of climate change, especially in sub-Saharan Africa (SSA) where it is difficult to model these impacts, hence leading to high levels of uncertainty in future scenarios (2050 and beyond).

Long-term investment planning and system operations for energy, depend on and compete with other sectors for, the availability of water (for hydropower and cooling thermal plants) and land resources (e.g. for biofuel production and arability). The efficient exploitation of land, energy and water resources and their synergised use for economic development therefore require an multidimensional integrated optimisation approach co-created with stakeholders in dialogue. This starts with planning followed by prioritised investments based on local, national and regional needs in the energy, agricultural and water sectors. This is mostly lacking in SSA at the moment. We gathered a selected group of experts in Accra, Ghana in November 2022 with a broad mix of experiences and expertise in the energy, water and agricultural sectors, who shared deeper insights and values of the need for integrated WEF planning to begin tackling challenges and opportunities identified in the Volta Basin in West Africa (starting with Ghana) and the Tana basin in Kenya. The main challenge identified was the disjointed planning of WEF infrastructures due to different financing mechanisms and siloed sectoral thinking; and participants raised emerging opportunities for planning infrastructure through transnational and regional cooperation  as well as the need to build on existing and new initiatives devoid of entrenched political goals.

In this contribution, we will present some of the main findings from the meeting in Accra and share knowledge on how transparent WEF modelling can be contextualised for local operational relevance, and through co-creation, how interactive engagement tools can be used for planning, policy- and decision-making.

Keywords: WEF modelling, sub-Saharan Africa, WEF Infrastructures, Investment Planning, Optimisation

The work leading to these results has received funding from the European Horizon Europe Programme (2021-2027) under grant agreement No.101083763 (EPIC Africa). The opinions expressed in the document are of the authors only and in no way reflect the European Commission’s opinions. The European Union is not liable for any use that may be made of the information.

How to cite: Annor, F. O., Martin, V., Ofosu, E. A., Lucendo, C. G., Akuku, B., Fofana, R., van de Giesen, N., and Abraham, E.: Opportunities and Challenges in the Efficient Exploiting of Land, Energy and Water Resources within the Volta and Tana Basins in Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13219, https://doi.org/10.5194/egusphere-egu23-13219, 2023.

EGU23-14318 | ECS | Orals | HS5.7

Investigating the potential role of pumped hydro storage in the Ethiopian energy system transitions to 2050 using OSeMOSYS 

David de Vries, Jagruti Ramsing Thakur, Viktoria Martin, Frank Annor, and Edo Abraham

Ethiopia’s energy demand is expected to increase sevenfold in the coming 30 years, resulting in increased variable renewable electricity (VRE) production by solar PV and wind. Energy storage acts as a buffer that mitigates the effects of over- or under-capacity in production by VRE. With 97% of global bulk energy storage, pumped hydro storage is the most widely used and mature energy storage technology. With its long operational life, high round-trip efficiency (80%) and stable cost trajectory, it is a competitive option for many VRE-rich (future) energy systems. However, barriers to pumped storage include heavy technical, site-specific restrictions, long construction times and high initial capital investment requirements.

This study investigates if Ethiopia’s energy pathways benefit from adding pumped hydro storage, suitable regions for PHS, and to what extent storage would increase system resilience. The long-term energy planning tool OSeMOSYS is used, which allows for detailed investigation into system dynamics whilst parallelly minimising costs. OSeMOSYS enabled the investigation into Ethiopia by looking at an extensive host of techno-economic specifications and supply and demand dynamics from the electrification of transport and integration of variable renewables to residential cooking demands.

This research studies thirteen scenarios which are separated into three main categories: Base Case (3), Emission Penalty (EMI) (6) and Varying Wind Capacity and Seasonality (WND) (6). The base case introduces pumped storage to the energy pathways, and the EMI scenario characterises three pathways for carbon pricing. In the WND scenario, wind power’s capacity factor and seasonality are altered to investigate the potential effects of using more accurate local data or prioritising some supply zones on the energy system configuration. Additionally, the most favourable locations for solar PV and wind are combined with potential PHS locations to find optimal sites for storage construction.

The results of the research show that pumped hydro storage is adopted into the energy system in all scenarios, following both a diurnal and seasonal (dis)charge pattern. Variable renewable integration increases by an average of 10% from the addition of storage (78 GWh). The emission penalty increases the electrification of residential cooking demand and boosts VRE penetration but does not integrate storage integration further than the base case due to reaching the upper limit of the storage capacity set in the planning experiments.

Pumped hydro storage was found to increase the resilience of the modelled energy systems to climate-driven seasonal uncertainties and prices due to fossil fuel and carbon price uncertainties by making them less dependent on fossil fuels, decreasing vulnerability for potential emission penalties, and seasonal capacity fluctuations. The introduction of PHS was also found not to increase overall system costs, making it, combined with the stable levelised cost of storage and high maturity, a prime candidate for large-scale energy storage in Ethiopia.

How to cite: de Vries, D., Ramsing Thakur, J., Martin, V., Annor, F., and Abraham, E.: Investigating the potential role of pumped hydro storage in the Ethiopian energy system transitions to 2050 using OSeMOSYS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14318, https://doi.org/10.5194/egusphere-egu23-14318, 2023.

EGU23-15624 | ECS | Posters on site | HS5.7 | Highlight

How effectively (or not) can science and research be turned into adopted solutions and policies? 

Elena Matta, Andrea Cominola, Chrysi Laspidou, Aitor Corchero Rodriguez, Marco Micotti, Manuel Pulido Velázquez, Matteo Giuliani, and Andrea Castelletti

How to create an impact on policies, operations, and society across the interdisciplinary sectors in which we - as researchers - are involved? Managing the Water-Energy-Food-Ecosystem (WEFE) nexus and pursuing climate resilience is the core task of several European (EU) projects and is in the highest interests of our society. The European Commission’s research funding programs attempt to address a large range of topics and offer unique opportunities for scientists to create a tangible impact on the environment and society.

We are currently involved in different EU projects, including AWESOME (PRIMA), which aims at managing the WEFE nexus across sectors and scales in the South Mediterranean exploring innovative technologies such as soilless agriculture in the Nile Delta; CLINT (H2020), which is developing Machine Learning (ML) techniques to improve climate science in the detection, causation, and attribution of extreme events to advance climate services; IMPETUS (H2020), whose efforts are dedicated on the elaboration of climate data space enhanced with ML algorithms to support the elaboration of climate policies; REACT4MED (PRIMA), which focuses on combating land degradation and desertification by improving sustainable land and water management through the identification of local good restoration practices and their potential upscaling; Gaza H2.0: Innovation and water efficiency (EuropeAid), which aims at promoting efficient and sustainable water supply and demand as well as knowledge transfer to enhance resilience against water scarcity in Gaza; GoNEXUS (H2020), which is developing an evaluation framework to design and assess innovative solutions for an efficient and sustainable coordinated governance of the WEFE nexus; NexusNet (COST), which creates the network and the community of WEF nexus advocates for a low-carbon economy in Europe and beyond; NEXOGENESIS (H2020), which focuses on streamlining water-related policies with artificial intelligence and reinforcement learning; MAGO (PRIMA), which builds web applications for water and agriculture in the Mediterranean; BIONEXT (HEU), which is interlinked with the Intergovernmental Panel on Biodiversity and Ecosystem Services and aims at creating transformative change through nexus analysis.

Despite the efforts of the scientific community, there is still a gap between research and practice. Researchers face difficulties in engaging stakeholders and decision-makers to jointly explore and shape the developed solutions, as well as to truly adopt them. The large-scale implementation of suitable technological solutions might require time and financial resources beyond the project’s lifetime and capacity. The lack of follow-ups and collaboration among projects with similar aims can be some of the reasons lying behind. Also, the complexity of finding open data in data-scarce regions makes results less trustable in the eyes of international agencies, while the pressure of publishing often turns research tasks into pure academic exercises. To what extent does the European strategy work? Is it only gaining scientific advances or also leading to local policy changes? Engaging important local actors (e.g., ministries), small-medium enterprises and societal members in the project consortia, empowering scientists by ensuring feedback loops with local governmental agencies, including the human dimension into modelling, and running effective capacity-building campaigns can be some food for thoughts to shape new strategies.

How to cite: Matta, E., Cominola, A., Laspidou, C., Corchero Rodriguez, A., Micotti, M., Pulido Velázquez, M., Giuliani, M., and Castelletti, A.: How effectively (or not) can science and research be turned into adopted solutions and policies?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15624, https://doi.org/10.5194/egusphere-egu23-15624, 2023.

EGU23-15642 | ECS | Posters on site | HS5.7

Developing policy recommendations to support innovation in soilless agriculture within the Nile River Basin: A participatory approach using Multi-Actor Working Groups 

Lydia Stergiopoulou, Ebun Akinsete, Nouran El-Said, and Phoebe Koundouri

Increasing demand for energy, food and water in the Mediterranean along with the decline of freshwater availability due to climate change necessitate the exploration of options for producing more food with less water, land and energy. Innovations in soilless agriculture aim to address this challenge by exploring novel approaches towards food production including aquaponics and hydroponics. However, inadequate and inefficient legislation and policy frameworks are ill equipped to provide the support necessary for the successful uptake and scale out of these new technologies.  This paper examines the implementation of soilless technologies in the water-stressed Nile River Basin. By applying a stakeholder-centered participatory approach developed by the project which takes into consideration the Water-Energy-Food- Ecosystem (WEFE) Nexus, we present targeted policy recommendations for the development of soilless agriculture in the region which inherently embed the views of key local stakeholders. 

How to cite: Stergiopoulou, L., Akinsete, E., El-Said, N., and Koundouri, P.: Developing policy recommendations to support innovation in soilless agriculture within the Nile River Basin: A participatory approach using Multi-Actor Working Groups, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15642, https://doi.org/10.5194/egusphere-egu23-15642, 2023.

EGU23-15664 | ECS | Posters on site | HS5.7

Establishment of Rural Living Area Boundary for Sustainable Agri-Food System 

Jeongwoo Han, Kihwan Song, and Jinhyung Chon

In general, rural areas are declining due to urbanization and climate change, which affects the agri-food system centered on rural residents. For agri-food systems, the size and connectivity of regional systems are important, and the boundaries of people living in rural areas must be clearly defined. To effectively respond to these problems, the Republic of Korea proposed a policy plan for rural areas. However, there are issues with this approach since it is based on a legal spatial unit—meaning rural residents are not receiving the full breadth of intended benefits. It is necessary to readjust the spatial boundaries by aligning them more closely with the extent of the rural residents' living radius and the standards for services. This study aimed to establish the concept of a living area as it relates to rural areas, present criteria for setting the range and dimensions of a living area, and to then apply it to case studies. The target area was Muju-gun, Korea. It contains rural areas that face various problems such as population decline and aging. First, the concept of the rural living area was established based on insights gained from relevant literature reviews. The rural living area concept was defined as “a unit or range of spaces where rural residents can receive services to live and to support economic activities.” Second, building on the concept of the rural living area, the Muju-gun population, living service facilities, road networks, and watershed items were established, while relevant maps were collected. These materials were leveraged to conduct a network analysis. The closest facility analysis was performed and a network map was developed by overlaying the population and living service facilities with 12 key sectors (childcare, education, welfare, culture, physical education, health, medical care, commerce, finance, administration, transportation, and rest) and using the road network connecting them. Third, the range of living zones classified in order of size (small/medium/large) and by key sector in Muju-gun was derived. Excluding any missing values, a total of 30 Muju-gun living area ranges were drawn and presented. It was asserted that this was due to the fact that life service facilities in Muju-gun vary based on sector and size. The results of this study are particularly meaningful in that they presented a range based on the information that rural residents live in reality, and not an administrative district superimposed by the Republic of Korea—which reflects the existing legal standard unit. Since the derived range was based on the actual living range of rural residents, we expect efficient policy utilization in the planning and management of the agri-food system.

This work was carried out with the support of “Cooperative Research Program for Agriculture Science and Technology Development(Project No. PJ0171102022)” Rural Development Administration, Republic of Korea.

How to cite: Han, J., Song, K., and Chon, J.: Establishment of Rural Living Area Boundary for Sustainable Agri-Food System, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15664, https://doi.org/10.5194/egusphere-egu23-15664, 2023.

EGU23-16116 | Orals | HS5.7

AquaPlan: Bridging the gap between research and practice in crop-water modeling 

Timothy Foster, Thomas Kelly, Ryan Avery, and Kathryn Berger

Crop-water simulation models are powerful tools to support efficient and sustainable agricultural water use and management globally. However, uptake of these tools beyond the research community in policy and industry has traditionally been constrained by the complexity and closed-source nature of model codes, which limit ability for models to be adapted and applied to address complex real-world agricultural water management challenges. In this talk, we present AquaPlan, an interactive web-based tool crop management tool that enables farmers, businesses, and governments to make more informed decisions about water management, irrigation investments, and climate risks. AquaPlan combines a state-of-the-art open-source crop-water model, AquaCrop-OSPy, with global weather and soil datasets to enable users to conduct rapid on-the-fly assessments of field and regional-scale crop yield and water demands anywhere in the world. The tools also integrates future climate projections from CMIP6 models, providing insights to support efforts to enhance long-term resilience of agriculture and food supply chains to climate change. In this talk, we will present a range of use cases of AquaPlan, highlight how these kinds of interactive tools can strengthen uptake of models developed by researchers in water management policy, practice, and business.

How to cite: Foster, T., Kelly, T., Avery, R., and Berger, K.: AquaPlan: Bridging the gap between research and practice in crop-water modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16116, https://doi.org/10.5194/egusphere-egu23-16116, 2023.

EGU23-16319 | ECS | Orals | HS5.7 | Highlight

Political instability influence on hydropower planning in Africa: a continental scale analysis 

Teresa Bonserio, Angelo Carlino, Matteo Giuliani, and Andrea Castelletti

As many developed countries prepare their transition to net zero emissions energy systems, Africa must plan a substantial expansion of its energy production sources, to meet the growing demand driven by increasing population and energy access. Among the existing capacity expansion potential, hydropower plays an important role in providing clean and cheap electricity. Yet, large hydropower schemes bring many negative social, environmental, and geopolitical externalities.

Least-cost optimization models constrained to satisfying predefined energy demands are used for large-scale energy system planning. Multi-objective optimization models can also incorporate environmental impacts in energy system planning, for instance by constraining the optimal solutions on GHG emissions or geomorphologic connectivity losses. However, these traditional techno-economic approaches overlook governance considerations, which are relevant to energy security, especially in unstable and conflictual political contexts. In fact, concerns about political instability are ranked among the main investment risks for foreign investors in developing countries. The subject becomes even more significant in transboundary river basins, where institutional stability and the absence of conflicts are crucial for effectively building and operating large hydropower projects.

To assess the political risks associated with the hydropower sector, we examine six pathways of energy generation for the African continent, from 2020 to 2050, developed using the OSeMOSYS-TEMBA energy system model. The model considers more than 600 existing and future hydropower projects in all countries of continental Africa, including available information for each individual power plant. Moreover, it incorporates ISIMIP2b scenarios to integrate coherently final energy demands, land-use change, and climate impacts on water availability.

For each scenario considered, the political risk deriving from the associated electricity generation and exchange patterns is characterized at the country-level using six energy-related dimensions. The more vulnerable transboundary river basins are then selected by intersecting the countries with high energy-related political risk and regions with high hydro-political conflict based on existing literature. We use a worst-case perspective for these basins and assume that electricity generated from planned or existing hydropower projects would not be exchanged between co-riparian countries due to the lack of cooperation. Finally, the impacts on the energy system are re-evaluated for the resulting cost-optimal energy system reconfiguration, and the difference with the fully connected solution is assessed.

Our results show that integrating political stability in energy system planning can produce precise spatial information about potential risks. Indeed, the lack of cooperation in transboundary river basins affected by high political instability can emphasize pre-existing vulnerabilities. Since this issue severely influences decisions related to energy planning on a continental scale, energy analysts can improve energy security using these results to design capacity expansion robust to political shocks.

How to cite: Bonserio, T., Carlino, A., Giuliani, M., and Castelletti, A.: Political instability influence on hydropower planning in Africa: a continental scale analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16319, https://doi.org/10.5194/egusphere-egu23-16319, 2023.

In recent years, research on the water-energy-land (WEL) nexus has grown significantly not least because of the highly interconnectedness of the respective domains, but also for the crucial nature-economy interactions that underpin the future of our planet. With climate change and biodiversity crises looping, our conventional siloed biophysical and economic models are no longer adequate at providing prudent guidance to the interrelated sustainability questions. A new approach is urgently needed to tackle the issues of nature and the economy. In this research, we are developing a global-scale dynamic system model of nature, macroeconomy and finance that gives guidance on the crucial policy questions on the WEL nexus and biodiversity dynamics. We provide a critique of the existing modeling approaches, our novel conceptualization for a multidimensional model - with crucial elements, interactions, and underlining theories - which provides insights into the underlying source of biodiversity loss and the trade-off between different economic activities to safeguard livelihoods and achieve the so-called ‘nature positive’ pathways.

How to cite: Ilyas, A.: Reconceptualizing macroeconomic dynamics of water-energy-land for nature positive development pathways, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16496, https://doi.org/10.5194/egusphere-egu23-16496, 2023.

This research investigates the interconnections between water, energy, and land systems in the context of a long-term assessment of transition paths to achieve the Sustainable Development Goals (SDGs). It highlights the importance of integrated methods and addresses the complexity, interdependence, and uncertainty of climate change's impacts on natural systems and technology in the water, energy, and land sectors. The research utilizes two Integrated Assessment Models (MESSAGEix-GLOBIOM and IMAGE) to assess the long-term resources, supply, and demand of these sectors, together with the regional and sectoral reforms required to achieve the SDGs. It demonstrates how various locations and sectors would be affected by climate feedback under various climate mitigation scenarios. 

The study concludes that changes in water availability, that influence agriculture, water and sanitation access, hydropower potential, and power plant cooling technologies, constitute the largest proportion of climate impacts and the prime source of uncertainty. Furthermore, scenario analysis is used to understand the relationship between the SDGs and climate impacts in the absence of climate policies. The findings demonstrate that considerable progress towards the trajectories of the nexus SDGs resulted in strong synergies and interactions across the energy-water and land nexus components, irrespective of climate factors. Additionally, the study demonstrates that ambitious and healthy dietary modifications and a reduction in food waste can result in a decrease in global food demand, irrigation withdrawals, and emissions. Changes in the land sector can reduce overall SDG policy costs and energy and water expenditures, while strengthening the needs of the poor. Improving wastewater treatment and establishing more efficient water management technologies has socioeconomic and environmental advantages and can alleviate stress on freshwater withdrawals in locations that are water stressed. 

The study also shows that some regions, such as the Middle East and South Asia, are more vulnerable to climate impacts on the water sector and may require more extensive investments in water efficiency. In addition, it stresses that supplying households with electricity and clean cooking services can stimulate energy demand in emerging economies, but widespread adoption would require an increase in household incomes, notably in South Asia and Sub-Saharan Africa. Overall, the study highlights the importance of exploring the effects of climate change on natural and technological systems in the water, energy, and land sectors, as well as the relevance of implementing a coordinated strategy to achieving the Sustainable Development Goals. It also demonstrates the inter - dependencies and potentials of various sectors to achieve the SDGs while addressing the challenges they face because of climate change. 

How to cite: Awais, M., Vinca, A., Byers, E., Fricko, O., Frank, S., Krey, V., and Riahi, K.: Leveraging Integrated Assessment Models to access climate feedbacks on Water, Energy, and Land Systems: An Evaluation of Regional and Sectoral Transformations for Achieving the Sustainable Development Goals , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16585, https://doi.org/10.5194/egusphere-egu23-16585, 2023.

EGU23-16592 | ECS | Posters virtual | HS5.7

Climate mitigation using wood in the Netherlands: a modelling approach from family home to national scale 

Jaap Bos, Jikke van Wijnen, Angelique Lansu, and Winnie Leenes-Gerbens

Abstract

Forests mitigate climate change by storing CO2 as wood and providing wood for products with a long economic residence time. This study examined the extent to which common Dutch homogeneous forests can contribute to climate mitigation if the harvested wood is processed into products. A model was set up which calculates the CO2 stock in the atmosphere for varying residence times of harvested wood in the economy and also determines the influence of this residence time on the optimal harvest age. Existing yield tables of Dutch homogenous forest were used as input data. This study showed that homogeneous forests in the Netherlands can extract a maximum of between 7 and 17 Mg of CO2 per hectare annually, depending on the tree species. For all tree species, the CO2 extracted from the atmosphere approaches this maximum as the residence time in the economy increases. The optimum felling age is not fixed, but varies depending on the economic residence time. The construction of 660,000 wooded single-family homes until 2050 with a lifetime of 150 years will remove an average of 1,5 Tg from the atmosphere annually. If the total forest area in the Netherlands is used to store wood in the economy for 150 years, an average of almost 6 Tg will be extracted annually. This is relatively low compared to the annual Dutch CO2 emissions of 150 Tg, but it is an option that fits well into the mix of other options that can contribute to climate change mitigation.

How to cite: Bos, J., van Wijnen, J., Lansu, A., and Leenes-Gerbens, W.: Climate mitigation using wood in the Netherlands: a modelling approach from family home to national scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16592, https://doi.org/10.5194/egusphere-egu23-16592, 2023.

EGU23-17268 | Orals | HS5.7

Inclusive Outscaling of the Agricultural Land Afforestation Agro-ecosystem REstoration ACTions in Heraklion, Greece 

Ioannis Daliakopoulos, Irene Christoforidi, Ioannis Louloudakis, Dimitrios Papadimitriou, and Thrassyvoulos Manios

Land degradation and desertification are considered major threats for the present and future of Mediterranean arid and semiarid agro-ecosystems (Daliakopoulos et al., 2017). Long-term anthropogenic pressure on forest and agricultural lands, combined with abiotic factors and the global trend of accelerated dryer climate and dryland expansion, create an uncertain and unstable living environment which has been demonstrated to increase poverty and force domestic and even cross-border migration. While our understanding and the flow of information about these threats is unprecedented, challenges persist and uptake of good practices by stakeholders is hindered by constraints and barriers both biophysical and socioeconomic (Daliakopoulos, 2022). For example, in one of the pioneer institutional initiatives aiming to enhance long-term forest resources and combat soil erosion and desertification by promoting forestry as an alternative form of land use, the Agricultural Land Afforestation (ALA) Program (Regulation 2080/92) introduced compensations for the income loss incurred during the non-productive period of afforested agricultural land. However, awareness about the Program by landowners, and the overall effectiveness of afforestation both in forestation success and in reducing soil erosion remains uncertain (Arabatzis et al., 2006; Nunes et al., 2011). In this context, the premise of the REACT4MED Project is that massive and effective land restoration actions need not only to make sense from an environmental point of view, but to also be socially acceptable, economically viable (Daliakopoulos & Keesstra, 2020), and have measurable impact, thus combining good practices with organic and inclusive transformation of all social actors. Here we present an overview of the effectiveness of the former ALA in the REACT4MED Pilot Area of Heraklion and outlines the supporting actions, both top down and bottom up, planned during the REACT4MED Project to increase the effectiveness of the forthcoming ALA Program by combining good practices with organic and inclusive transformation of all social actors.

References

Arabatzis, G., Christopoulou, O., & Soutsas, K. (2006). The EEC Regulation 2080/92 about forest measures in agriculture. International Journal of Ecodynamics, 1(3), 245–257. https://doi.org/10.2495/ECO-V1-N3-245-257

Daliakopoulos, I. N. (2022). Sustainable Soil and Water Management for Combating Land Degradation and Desertification and Promoting Mediterranean Ecosystem Restoration: The REACT4MED Concept. Third World Conference on the Revitalization of the Mediterranean Diet, 28.

Daliakopoulos, I. N., & Keesstra, S. (2020). TERRAenVISION: Science for Society. Environmental issues today. Science of the Total Environment, 704. https://doi.org/10.1016/j.scitotenv.2019.135238

Daliakopoulos, I. N., Panagea, I. S., Tsanis, I. K., Grillakis, M. G., Koutroulis, A. G., Hessel, R., Mayor, A. G., & Ritsema, C. J. (2017). Yield Response of Mediterranean Rangelands under a Changing Climate. Land Degradation & Development. https://doi.org/10.1002/ldr.2717

Nunes, A. N., de Almeida, A. C., & Coelho, C. O. A. (2011). Impacts of land use and cover type on runoff and soil erosion in a marginal area of Portugal. Applied Geography, 31(2), 687–699. https://doi.org/10.1016/J.APGEOG.2010.12.006

Acknowledgements

This work has received funding from REACT4MED: Inclusive Outscaling of Agro-Ecosystem Restoration Actions for the Mediterranean. The REACT4MED Project (grant agreement 2122) is funded by PRIMA, a program supported by Horizon 2020.

How to cite: Daliakopoulos, I., Christoforidi, I., Louloudakis, I., Papadimitriou, D., and Manios, T.: Inclusive Outscaling of the Agricultural Land Afforestation Agro-ecosystem REstoration ACTions in Heraklion, Greece, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17268, https://doi.org/10.5194/egusphere-egu23-17268, 2023.

Of all the natural resources available to humankind, water holds a prominent place, particularly because of its importance for human livelihood. Savelugu district in northern Ghana is characterized by unpredictable rainfall patterns with periodic and perennial water shortages. The distance people travel to fetch water and the person-hours spent in search for water affect productivity, economic livelihood, and health and education benefits. Provision of potable water supply to these communities is expected to bring not only health, education benefits but also increase in sanitation and hygiene practices. Static water levels (SWLs) of 19 wells in the study area were collected, analyzed and compared to the initial SWLs measured when the wells were immediately drilled and constructed. The SWL data was subjected to paired samples T-test (with α = 0.05). From the results, there was significant difference in the SWL immediately after drilling and construction (µ = 12.15, σ = 7.50) and SWL after at least 10 years (µ = 17.81, σ = 10.29); t (18) = -3.7, P = 0.002. Lowered groundwater levels were recorded in all wells measured. This can lead to drying up of some of the wells whose difference between the current SWL and well depth is close. There must be strong advocacy, development and implementation of IWRM plans to help address the problem of inadequate WASH in the study area.

How to cite: Acheampong, A.: Lowering of groundwater levels and their effect on Water, Sanitation and Hygiene services in the Savelugu District, Northern Region of Ghana, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-139, https://doi.org/10.5194/egusphere-egu23-139, 2023.

Agriculture, in general, has a long production cycle and is affected by many endogenous and exogenous uncertainty factors. Changes in rainfall patterns, maximum or minimum temperature, types and amounts of fertilizer input, timing, availability of irrigation water, and soil quality can drastically change the agricultural yield. In developing countries such as India, where more than half of countries population is engaged in agriculture, and the whims of nature may affect the agricultural output, it is essential to check how the entire agricultural system reacts to the changes in climatic parameters and anthropogenic practices. This study analyses agricultural trends in four primary staple crops, trends in climatic parameters, and anthropogenic inputs in Indian districts. Significant trends were detected and quantified using the non-parametric Mann-Kendall (MK) test, modified MK test, and Theil-Sen estimator at a 5% significance level. Spearman’s correlation test is used to determine the contributing factors to the changes in agricultural yield. Rice, Wheat, Pearl Millet, and Maize yields have shown significant increasing trends in a large number of the districts. Despite decreases in the gross cropped area in the majority of the districts, the trends in production are mostly positive. According to Spearman’s Rho correlation test, the increase in fertilizer consumption in most districts and the increase in crop-wise irrigated land in many districts are the significant reasons for the increase in yields. The rainfall did not change much compared to maximum and minimum temperatures at both the annual and seasonal levels. Although there were significant climatic changes in the last three decades, the correlation with agricultural yield is mostly insignificant.

How to cite: Sarkar, N. and Ray, S.: Analysis of Agricultural and Climatic trends in Indian Districts and finding the contributing factors in recent Indian Agricultural Outputs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-653, https://doi.org/10.5194/egusphere-egu23-653, 2023.

EGU23-1916 | ECS | PICO | HS7.3

Modeling the potential of management options to reduce irrigation demand in Western Switzerland 

Malve Heinz, Christoph Raible, Bettina Schaefli, and Annelie Holzkämper

European Agriculture is experiencing the consequences of summer droughts and heatwaves in form of quality and quantity losses for numerous crops and feed production. Water availability for irrigation in the vital summer and fall months is decreasing and therefore, irrigation will most likely not be able to sufficiently mitigate the effects of droughts and heat in the future. Thus, approaches that reduce the need for irrigation are required. We investigate potential water-use reduction strategies based on a modelling framework applied to a selected case study in Western Switzerland, the Broye catchment. The region is characterized by intensive agricultural use and drought-related irrigation bans in summer. In the first step of our project, we quantify the total irrigation demand under current and future climate conditions using the soil-water-atmosphere-plant model SWAP. SWAP mainly simulates water and solute flow in soil as well as vegetation growth by solving a set of equations such as the Richards equations. Irrigation demand is quantified by applying this 1D model to the full range of climatic, soil and land use conditions prevailing in the selected catchment. The model calculates both the irrigation requirements and the yield of various irrigation-intensive crops currently grown in the region, such as potatoes, maize, or sugar beet. In a second step, we use the model to assess the efficiency of different management options to reduce the water demand, such as mulching, organic amendments, biochar application, different tillage methods or the cultivation of better-adapted crops. In future work, we will couple the field-scale model to a catchment-scale rainfall-runoff model to assess the impact of a large-scale application of such measures on the water balance of the catchment.

How to cite: Heinz, M., Raible, C., Schaefli, B., and Holzkämper, A.: Modeling the potential of management options to reduce irrigation demand in Western Switzerland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1916, https://doi.org/10.5194/egusphere-egu23-1916, 2023.

EGU23-2603 | PICO | HS7.3

Rainwater harvesting as climate change adaptation strategy for durum wheat production in Sardinia 

Francesco Viola, Roberto Deidda, Salvatore Urru, and Elena Cristiano

The Mediterranean region is widely recognized as a climate change hotspot, where, mainly due to the increase of CO2 concentration, both historical records and future climate models’ projections reveal an increase of the daily average temperature and a reduction of the mean annual precipitation, with less frequent but more intense rainfall events. These changes could have strong impacts on the durum wheat production, and consequently to the food chain that derives from it. Water availability is expected to be the main limiting factor in the durum wheat growth, which is usually rainfed in Mediterranean region. On the other hand, CO2 increase may act as a counterbalance factor, by increasing the water use efficiency. In this work, within the framework of the H2020 European Union project ARSINOE (“Climate-resilient regions through systemic solutions and innovations”), we investigated the possibility to adapt durum wheat production to climate changes, compensating the rainfall reduction with emergency irrigation derived from a rainwater harvesting system, with the aim to keep constant the durum wheat production or alleviate the yield reduction. The Aquacrop model, a crop growth model developed by FAO’s Land and Water Division, has been calibrated to reproduce the actual durum wheat production in the Campidano region in Sardinia (Italy), implementing the local climate and soil characteristics. The model has been then used to simulate the crop production in correspondence of different bias corrected future climate scenarios, which foreseen an average rainfall reduction and increase of average temperature and CO2 concentration in the atmosphere. A rainwater harvesting system to collect rainfall from the rooftops or impervious surface within the cultivated area (100m2/ha) has been designed and the volume for potential emergency irrigation has been estimated year by year. Preliminary results show the importance of implementing rainwater harvesting systems to provide emergency irrigation and sustain durum wheat production in a context of climate changes.

Acknowledgments

This project has received funding from the European Union’s Horizon H2020 innovation action programme under grant agreement 101037424.

How to cite: Viola, F., Deidda, R., Urru, S., and Cristiano, E.: Rainwater harvesting as climate change adaptation strategy for durum wheat production in Sardinia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2603, https://doi.org/10.5194/egusphere-egu23-2603, 2023.

With the impact of climate change and the main rainfall seasons in Taiwan are concentrated in the plum rain season from May to June and the typhoon season from July to September each year.There are significant differences in rainfall and spatial and temporal distribution between the wet season and the dry season,the droughts will occur and even lead to severe water shortages, such as the worst drought in half a century in 2021.From a macroscopic spatial scale, for example, the El Niño phenomenon and solar activity may have a certain impact on the overall climate and water resources of the earth.Therefore, this study analyzes the correlation between rainfall and large-scale influencing factors such as sunspots, El Niño-Southern Oscillation,and uses machine learning models to predict and classify rainfall under different conditions,the prediction accuracy rate through historical data can reach 89.9% , with sunspots as the most significant factor. It is hoped that relevant units can provide reference for water resources management and planning.

How to cite: Weng, Z.-H. and Lin, Y.-C.: Establishing a macroscopic-scale rainfall climate and water resources estimation model by machine learning method, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3008, https://doi.org/10.5194/egusphere-egu23-3008, 2023.

EGU23-3528 | ECS | PICO | HS7.3

Effects of heat and drought stress and their co-occurrence on winter wheat yields in Germany under climate change 

Rike Becker, Bernhard Schauberger, Ralf Merz, Stephan Schulz, and Christoph Gornott

In our changing climate, heatwaves and droughts and their spatio-temporal co-occurrences are likely to intensify. This will inevitably challenge future agricultural production and calls for adaptation strategies to protect future yields. To find suitable climate adaptation strategies for Germany’s major staple crop - winter wheat - it is important to know how heat stress, drought stress or their compound effects drive wheat yield failures. The principal aim of this study is, therefore, to quantify the impacts of heat, drought, and their compound effects on winter wheat yields in Germany, in a spatially and temporally discrete manner.

To address our aim, we develop a statistical crop-climate model for the time period 1991-2019 at the county level. We first create agroclimatic proxies for heat stress, drought stress and their compound effects and use these to construct a separate time series model with the addition of time-dependent interaction terms. Our approach constructs separate regression models for each county, based on common elements that allow for comparing and jointly interpreting individual models.

Preliminary results show that more than 50% of Germany’s wheat yield variability can be explained by climate effects. Compound effects of heat and drought stresses are responsible for approx. 42% of the variability in Germany’s winter wheat yields. Drought stress alone explains approx. 7%, with higher impacts in the east of the country, and heat stress alone explains approx. 3% of the year-to-year yield variability, with higher impacts in the north-west of Germany. The results confirm the importance of compound effects and underline their dominating impacts on winter wheat yields, when compared to individual heat and water stress impacts – a finding which should guide future adaptation strategies. Furthermore, our study shows that heat stress is becoming increasingly important for wheat yield failure in Germany – alone and in conjunction with moisture stress.

In conclusion, we suggest that climate change adaptation strategies for winter wheat in Germany should focus on combined measures against drought and heat extremes. While the increase of multi-stress resilience should be the main goal for entire Germany, north-western areas should prioritize strategies to increase heat resilience and eastern areas should prioritize strategies to increase drought resilience.

How to cite: Becker, R., Schauberger, B., Merz, R., Schulz, S., and Gornott, C.: Effects of heat and drought stress and their co-occurrence on winter wheat yields in Germany under climate change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3528, https://doi.org/10.5194/egusphere-egu23-3528, 2023.

current legislation requires the inspection and calibration of operational survey radiation monitoring instruments used in nuclear medicine and radiotherapy departments as well as in any field that uses ionizing radiation sources. As a result, Morocco's national secondary standard dosimetry laboratory provides reliable calibration results with high accuracy while adhering to national and international radiation protection standards and covering the various measurement ranges, using the attenuators offered by the automated Gamma G10 irradiator or the validated beam qualities produced by the X-ray irradiator type X80-320kV as required. The measurements’ reliability was demonstrated by participation in a comparison program launched by the International Atomic Energy Agency (IAEA).

This work aims to develop a digital graphical user interface designed for the calibration of measuring instruments in radiation protection through the programming language Python, which serves to facilitate the establishment of all operations and calculations related to the determination of calibration factors and measurement uncertainties according to the ISO 4037 standard in a minimum time that allows to process several instruments during the day with high accuracy, while minimizing the sources of errors, this interface allows the recording of calculations as well as the establishment and electronic archiving of the calibration certificate in pdf format ported from PHP FPDF.

How to cite: Belhaj, O. E., Boukhal, H., and Belhaj, S.: Digital graphical user interface as a facilitator for the calibration of radiation monitoring instruments according to ISO 4037:2019 at the national secondary standard dosimetry laboratory of morocco, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4503, https://doi.org/10.5194/egusphere-egu23-4503, 2023.

Groundwater is an essential source of water in Taiwan, and its long-term overuse has resulted in water resource problems that have become a potential crisis in the Zhuoshui River Basin. This overuse of groundwater may also lead to subsidence, which can have significant consequences for the area and its infrastructure. The lack of complete observations of groundwater extraction in Taiwan due to historical factors has made it difficult to accurately understand and manage the amount of water being taken, particularly for agricultural purposes.In view of this, this study uses time series data from 87 agricultural groundwater wells in Huwei Town, Yunlin County from January 2016 to July 2017, and time series data on agricultural well electricity usage in the Changshui River Basin, combined with other attribute data, to understand farmers' water pumping behavior using data mining methods and to estimate the amount of water taken in the Huwei area using machine learning.This study obtained the spatial and temporal distribution of groundwater withdrawals in the Huwei area in 2018.

How to cite: Tseng, Y. K. and Yu, H. L.: Using Time Series Data and Machine Learning Estimating Agricultural Groundwater Extraction in Huwei Town, Taiwan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5173, https://doi.org/10.5194/egusphere-egu23-5173, 2023.

EGU23-5551 | ECS | PICO | HS7.3

Probabilistic modelling of water distribution networks and resilient reduction of leakages: Large scale application to the city of Patras in western Greece 

Athanasios V. Serafeim, George Kokosalakis, Roberto Deidda, Nikolaos Th. Fourniotis, Irene Karathanasi, and Andreas Langousis

Modeling of leakages in Water Distribution Networks (WDNs) is a vital task for all water related professionals and experts towards the development of management practices and strategies, which aim at the reduction of water losses (leakages) and the associated financial cost and environmental footprint. In the current work we develop an integrated, theoretically founded, and easily applicable probabilistic framework for resilient reduction of leakages in WDNs, which combines: a) a set of conceptually and methodologically different probabilistic approaches for minimum night flow (MNF) estimation in WDNs based on statistical metrics (Serafeim et al., 2021 and 2022a), and b) a combination of statistical clustering and hydraulic modeling techniques for the rigorous and user unbiased partitioning of WDNs into pressure management areas (PMAs) or district metered areas (DMAs), which seeks for minimization of leakages while maintaining an acceptable level of the network’s hydraulic resilience (Serafeim et al., 2022b). The efficiency of the introduced framework is tested via a large-scale real-world application to the water distribution network of the City of Patras, the largest smart water network (SWN) in Greece, which covers an area of approximately 27 km2 and serves more than 213000 consumers (based on data from the Hellenic Statistical Authority and the Municipality of Patras), with more than 700 km of pipeline grid (mainly HDPE and PVC pipes).

Acknowledgements

The research work was supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the “First Call for H.F.R.I. Research Projects to support Faculty members and Researchers and the procurement of high-cost research equipment grant” (Project Number: 1162).

References

Serafeim, A.V., Kokosalakis, G., Deidda, R., Karathanasi I. and Langousis A (2021) Probabilistic estimation of minimum night flow in water distribution networks: large-scale application to the city of Patras in western Greece, Stoch. Environ. Res. Risk. Assess., https://doi.org/10.1007/s00477-021-02042-9.

Serafeim, A.V., G. Kokosalakis, R. Deidda, I. Karathanasi and A. Langousis (2022) Probabilistic Minimum Night Flow Estimation in Water Distribution Networks and Comparison with the Water Balance Approach: Large-Scale Application to the City Center of Patras in Western Greece, Water, 14, 98, https://doi.org/10.3390/w14010098.

Serafeim, A.V., G. Kokosalakis, R. Deidda, N. Th. Fourniotis and A. Langousis (2022) Combining statistical clustering with hydraulic modeling for resilient reduction of water loses in water distribution networks: Large scale application to the city of Patras in Western Greece, Water, 14(21), 3493. https://doi.org/10.3390/w14213493.

 

How to cite: Serafeim, A. V., Kokosalakis, G., Deidda, R., Fourniotis, N. Th., Karathanasi, I., and Langousis, A.: Probabilistic modelling of water distribution networks and resilient reduction of leakages: Large scale application to the city of Patras in western Greece, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5551, https://doi.org/10.5194/egusphere-egu23-5551, 2023.

EGU23-5567 | PICO | HS7.3

A probabilistic approach for detection and classification of PRV malfunctions in the water distribution network of the city of Patras in western Greece 

Anastasios Perdios, George Kokosalakis, Nikolaos Th. Fourniotis, Demetris Pantzalis, and Andreas Langousis

Effective management of water losses in water distribution networks (WDNs) still remains a demanding task, as the temporal and spatial variability of water resources under changing climatic conditions and the increasing needs for drinking water may lead to freshwater shortages. In this context, pressure management strategies are widely adopted in an effort to reduce the water losses in the supply and distribution parts of water networks and, consequently, deescalate their environmental footprint. Installation of pressure reducing valves (PRVs) at critical locations of WDNs plays a central role in pressure regulation strategies, as PRVs reduce the upstream pressure to a set outlet pressure (i.e., downstream of the PRV), usually referred to as set point. Perdios et al. (2022) developed a novel statistical framework and applied it to an existing pressure management area (PMA) of the city of Patras in western Greece, aiming at early detection of PRV malfunctions that may significantly influence network’s operation and the corresponding lifetime of related infrastructure. The results showed that the suggested methodology allows reliable detection of critical malfunctions at least 2 days prior to flow disruptions. Ιn this study, we calibrate and implement Perdios et al. (2022) statistical framework, using pressure data for a 4-year period from 01/Jan./2017 to 26/Nov./2020 from several important PMAs of the WDN of the city of Patras, aiming towards better understanding of the causes of the malfunctions, by decomposing the observed pressure deviations from the set point to systematic and random error components.

Acknowledgements

The research work has been conducted within the project PerManeNt, which has been co-financed by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation under the call RESEARCH – CREATE – INNOVATE (project code: T2EDK-04177).

Reference

Perdios A., G. Kokosalakis, N. Th. Fourniotis, I. Karathanasi and A. Langousis (2022) Statistical framework for the detection of pressure regulation malfunctions and issuance of alerts in water distribution networks, Stoch. Env. Res. Risk Asses., https://doi.org/10.1007/s00477-022-02256-5

How to cite: Perdios, A., Kokosalakis, G., Fourniotis, N. Th., Pantzalis, D., and Langousis, A.: A probabilistic approach for detection and classification of PRV malfunctions in the water distribution network of the city of Patras in western Greece, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5567, https://doi.org/10.5194/egusphere-egu23-5567, 2023.

EGU23-10057 | ECS | PICO | HS7.3

Building a smart green system to control water leakage and monitor drinking water quality in the water supply system of Paramythia city, Greece: the case of SMASH project 

Angelos Chasiotis, Stavroula Tsitsifli, Konstantinos Panytsidis, Vegard Nilsen, Nikolaos Mantas, Dimitrios Theodorou, Thomas Kyriakidis, Stefanos Chasiotis, Maria Bousdeki, Elissavet Feloni, Harsha Ratnaweera, Panagiotis Nastos, and Malamati Louta

Water leakage is acknowledged as one of the most important issues that drinking water supply systems are facing worldwide. Non-Revenue Water is estimated to 346 million m3 per day and its cost/value is estimated to 39 billion USD per year. At the same time drinking water quality is jeopardized from the water intake points to the consumer’s tap, even during normal operating conditions.

ICT support water utility operators to improve the operational capacity of their water supply system. A smart green system to control water leakage and monitor drinking water quality in the water supply system of Paramythia city will be built in the context of SMASH project. It consists of: (a) IoT system comprising three local control stations, installed in selected parts of the water supply network, monitoring water quantity&quality parameters in real time; (b) the hydraulic simulation model of the water supply system of Paramythia; (c) a virtual sensors system, which will be used for water quality prediction; (d) a Decision Support System (DSS) for leakage detection and optimal management of water supply system parameters in an automated manner.

The DSS will detect and locate water leakages within the DMA zone and inform the operators for excessive values in drinking water quality parameters. The DSS will use as inputs the data from the IoT system, will interact with the hydraulic simulation model, and obtain the water quality data from the virtual sensors. All these data will be processed by the DSS logic in the backend subsystem. The IoT and the hydraulic simulation data, based on the digital twin of the water supply system, are used for the calculation of specific performance indicators related to water leakage, such as well-known IWA indicators: water losses, ILI, etc. Calculating the divergences between the PI values observed & the ones representing the optimal operation of the water network without leakages and setting appropriate thresholds, the DSS will detect the leakage, while several different scenarios will run in hydraulic simulation. The frontend subsystem of the DSS will be able to visualize the water distribution network, statistical values of water quantitative & qualitative parameters. It will provide alarms in case of leakage or exceedance of water quality parameters’ values and it will show the leakage location in a map. The architecture of the smart green system, currently under development, is depicted in Fig.1.

Figure 1. The DSS for the water parameters management in the water supply system

Keywords: Drinking water; water quality; leakage; virtual sensors; smart system; decision support.

Acknowledgement: This work is co-financed by EEA Grants 2014 – 2021 and Greek Public Investments Program.

  • Liemberger, R., & Wyatt, A. (2019). Quantifying the global non-revenue water problem. Water Supply19(3), 831-837.
  • Antzoulatos G., Mourtzios C., et al (2020), Making urban water smart: the SMART-WATER solution. Water Science & Technology, 82(12), 2691–2710.
  • Alegre, H., Baptista, et al (2016). Performance indicators for water supply services. 3rd IWA publishing.

How to cite: Chasiotis, A., Tsitsifli, S., Panytsidis, K., Nilsen, V., Mantas, N., Theodorou, D., Kyriakidis, T., Chasiotis, S., Bousdeki, M., Feloni, E., Ratnaweera, H., Nastos, P., and Louta, M.: Building a smart green system to control water leakage and monitor drinking water quality in the water supply system of Paramythia city, Greece: the case of SMASH project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10057, https://doi.org/10.5194/egusphere-egu23-10057, 2023.

By calculating the water demand and programming a fine irrigation project, the management and cultivating efficiency of traditional agriculture can be greatly improved. Taking rotational irrigation for example, the efficiency of irrigation can be maximized by adjusting water distribution routes, irrigation area allocation, and irrigation schedule planning. However, in actual operation, some problems are often encountered, such as how to persuade farmers and promote the designed irrigation project, and the negotiation of various stakeholders. Generally, due to the complexity of the irrigation design model, it is impossible to have an effective and immediate communication or presentation. Therefore, this study introduces the Bayesian network to presents the key points of the irrigation project after simplifying the relationship. In addition to being simpler for stakeholders to understand, it is also possible to adjust various parameters in time to obtain rough estimation results.

The research area of this study is a 100-hectare farmland, which is located in Kinmen County, Taiwan. For many years, local farmers have only relied on precipitation to cultivate sorghum, wheat and other crops. However, the precipitation in Kinmen is semiarid and unstable. In the past five years, the annual rainfall has been lower than the average in previous years, which directly led to a very bleak crop harvest. Therefore, we hope to establish an irrigation project in Kinmen, using recycled water as the water source to provide local farmers with a reliable water source.

The Bayesian network used in this study is a directed acyclic graphical (DAG) model based on conditional probability and Bayesian theorem to express the possible relationship between variables. In terms of operation, the different influencing factors in the research topic are converted into nodes, and the relationship between nodes is given by different conditional probabilities. This study uses GeNIe to establish a Bayesian network that can be used to estimate water profit and loss and other results. This Bayesian network can be divided into four sub-blocks, which are the relevant data of the irrigation area, the water demand, the water supply, and the final result calculation. Therefore, when the stakeholders are negotiating the irrigation project, they can discuss the different estimation results by adjusting each node of the first three sub-blocks.

How to cite: Su, Y. and Yu, H.-L.: Application of Bayesian Network in Analysis and Management of Agricultural Water - Taking Kinmen for Example, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10515, https://doi.org/10.5194/egusphere-egu23-10515, 2023.

Assessing the Sustainability in Water Use under
Different Agricultural Management Planning
in Yeongsan-River Basin, South Korea

 

Yujong Jeong1, Hyun-woo Jo1, YanYan1, Minwoo Noh1, Woo-Kyun Lee1*

 

1 Department of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea

*E-mail: leewk@korea.ac.kr

(Address: Korea University, Anamro 145, Seongbukgu, Seoul 02841, Republic of Korea)

 

Abstract:

From the past, South Korea has been experiencing high level of water stress as reported by WRI, in 2013, and chronically imbalanced spatiotemporal water allocation. Yeongsan-river basin, where the biggest national breadbasket is located, is facing unequal water allocation among different water uses and inefficient water management under episodic water shortage conditions. Therefore, the main objective of this study was to analyse current water management and allocation scheme, and to evaluate 3 different agricultural management plans in terms of efficiency and equity. The Soil and Water Assessment Tool(SWAT) was applied to simulate the hydrological process and crop yield in the basin. The model was calibrated and validated using observed outflows to set adequate system parameters for the entire watershed. Crop water productivity and spatial-temporal-sectoral water distribution are utilized as the indices to evaluate different agricultural strategies. The results suggested that there was potential to improve both crop productivity and water allocation at the same time with the suggested plannings. Crop water productivity increased in all three strategies in order of on-farm management measures (precise agriculture), crop diversification (replacing rice to beans) and agroforestry (mixing trees and crops). The crop water productivity of on-farm measurement ranges from 5t/L to 13t/L and rises about 20% on average. In addition, it is found that applying the combination of different agricultural management measures could achieve better water allocation in terms of space and time, and between agriculture and ecosystem. The outcomes of this study can serve scientific-evidence policy and decision-making systems for sustainable agricultural society and ecosystem.

KeywordsHydrological Modelling, SWAT, Crop water productivity, Water allocation, Agricultural Management Planning, Yeongsan-River Basin

Acknowledgements: This work was supported under the framework of international cooperation program managed by the National Research Foundation of Korea (No. 2021K2A9A1A02101519).

 

 

How to cite: Jeong, Y.: Assessing the Sustainability in Water Use under Different Agricultural Management Planning in Yeongsan-River Basin, South Korea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10943, https://doi.org/10.5194/egusphere-egu23-10943, 2023.

EGU23-10953 | ECS | PICO | HS7.3

Leveraging Hydroclimate and Earth Observation to Predict Grain Production in Sub-Saharan Africa 

Donghoon Lee, Frank Davenport, Shraddhanand Shukla, Laura Harrison, Greg Husak, Chris Funk, Michael Budde, James Rowland, Amy McNally, and James Verdin

The importance of forecasting agricultural production in Sub-Saharan Africa (SSA) is increasing for the management of agricultural supply chains, market forecasting, and targeting of food aid. In particular, agricultural forecasts enable governments and humanitarian organizations to respond more effectively to shocks in food production and price spikes resulting from extreme droughts. In this study, we use hydroclimate, earth observations (EO) and machine learning to develop an operational, sub-national grain production forecast system for a number of SSA countries, including food-insecure regions where rapid response is critical. Before creating the forecast, we collect and organize crop production data from the Famine Early Warning Systems Network in order to identify trends and variability in agricultural technology, climate, and vegetation. In addition, we demonstrate the capability of hydroclimate and EO data to capture favorable or unfavorable crop development conditions during the growing season. In addition, we demonstrate a unique capability that explains how EO characteristics influence current grain production forecasts, thereby enhancing the forecasts' reliability and efficacy. This research lays the groundwork for the development of a large-scale, operational crop yield forecasting system that will provide actionable predictions of food shocks for famine early warning and guide advanced preparedness and response strategies.

How to cite: Lee, D., Davenport, F., Shukla, S., Harrison, L., Husak, G., Funk, C., Budde, M., Rowland, J., McNally, A., and Verdin, J.: Leveraging Hydroclimate and Earth Observation to Predict Grain Production in Sub-Saharan Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10953, https://doi.org/10.5194/egusphere-egu23-10953, 2023.

EGU23-11183 | ECS | PICO | HS7.3

Implications of 1.50C global warming for agricultural productivity over a global rice exporting region in Central India 

Shoobhangi Tyagi, Sandeep Sahany, Dharmendra Saraswat, Saroj Kanta Mishra, Amlendu Dubey, and Dev Niyogi

Water, food, and energy security are the major climate risks of global warming. The Paris Agreement proposed an ambitious target of limiting the rise in global mean surface temperature to well below 20C, and preferably to 1.50C, compared to the pre-industrial era. However, the implication of this policy discourse on the agricultural system is imperative for ensuring food security in the face of global warming. This research focuses on understanding the changes in water availability and rice productivity under 1.50C global warming over a global rice-exporting semi-arid watershed in Central India. Towards this goal, the mean climate under 1.50C of global warming was computed for 21 Coupled Model Intercomparison Project Phase 6 (CMIP6) Global Climate models (GCMs). For each GCM, the corresponding changes in blue-green water availability and rice productivity at 1.50C warming period were estimated under two global warming scenarios (SSP2-4.5 and SSP5-8.5) based on the semi-distributed Soil and Water Assessment Tool (SWAT). Results suggest that the green and blue water is projected to change by ~ -20% to 10 and ~ -50 to 20%, respectively. The rice yield is projected to reduce in the range of 5% to 50%, with an increase in local temperature (~10C) and a decrease in local precipitation (~20%) being the limiting factor. This study provides useful information on when the 1.50C global warming could reach and how it can affect the agricultural productivity of semi-arid watersheds across different global warming scenarios. This study will help develop appropriate strategies to reduce/alleviate the impacts of global warming and foster food security at the watershed-scale.   

How to cite: Tyagi, S., Sahany, S., Saraswat, D., Mishra, S. K., Dubey, A., and Niyogi, D.: Implications of 1.50C global warming for agricultural productivity over a global rice exporting region in Central India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11183, https://doi.org/10.5194/egusphere-egu23-11183, 2023.

        Due to climate change, Taiwan's rainfall has become unstable in recent years, leading to short rainy seasons and low rainfall. In 2021, a severe drought occurred due to the lowest rainfall on record. Groundwater is essential for agricultural development, but less than 10% of wells are legal. Improper or excessive use of groundwater resources can cause serious disasters, such as sea intrusion and land subsidence. However, if the government and farmers extract groundwater effectively and sustainably, it will bring more flexibility to water management.

        In this study, a land subsidence model was conducted based on geological conditions and groundwater level. This study analyzes multi layer compaction monitoring well profiles, and further finds the correlation among the two main factors and subsidence. The goal of this study is to visualize which areas are more suitable for using groundwater and assist the government in water resource management. This study focuses on the Choshui river alluvial fan in Taiwan. A risk map of land subsidence for this area is made by evaluating two main factors, geological conditions and groundwater level.

How to cite: Su, S.-H. and Yu, H.-L.: Assessment of Land Subsidence based on Geological Conditions, Groundwater Levels in the Choshui River Alluvial Fan, Taiwan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11879, https://doi.org/10.5194/egusphere-egu23-11879, 2023.

EGU23-12693 | ECS | PICO | HS7.3

Photo-driven processes for the removal of biotoxins derived from Harmful Microalgal Blooms 

Javier Moreno-Andrés, Sandra Lage, Ana Catarina Braga, Leonardo Romero-Martínez, Asunción Acevedo-Merino, Enrique Nebot, and Pedro R Costa

Harmful Algal Blooms (HABs) are increasing in frequency and magnitude globally. These episodes are associated with the generation of biotoxins, which pose a potential risk to human and animal health. Biotoxins notably affect aquaculture activities and shellfish production, which has a clear impact on food and human health. Consequently, it is sometimes necessary to close the harvesting areas until the organisms are decontaminated. These natural detoxification mechanisms depend largely on the type of toxin and physiology of the organism, resulting in lengthy processes that can cause severe economic losses to aquaculture activities. As the main goal of this communication, we propose a technological alternative for the degradation of marine biotoxins through the implementation of UV technology as a treatment for agricultural, environmental, and health-related purposes. Therefore, advanced photochemical processes should be evaluated for the efficient degradation of marine biotoxins. The toxin selected was okadaic acid (OA), which is a very stable diarrheal toxin (DSP) and has a great impact on shellfish production areas, e.g. on the Portuguese coast. First, irradiation experiments were performed under UV-A, UV-B, and UV-C irradiation. In general, the concentration remained similar after different UV exposures, indicating that there was no observable photodegradation of OA after 3 h of UV irradiation, detecting a maximum degradation of 19.5% (± 0.95) in the UV-C region, suggesting that OA is clearly resistant to UV photodegradation. Second, the combined UV/H2O2, UV/HSO5, and UV/S2O82 − processes were tested. Two different UV sources were evaluated: LED and low-pressure lamps (LP), performing OA exposure in distilled water and seawater, with a maximum UV exposure of 3 h. In general, a clear degradation of OA is observed in photochemical processes in distilled water, with a slight decrease in efficiency in the UV/H2O2 process with an LED irradiation source. In the case of UV/S2O82 − and UV/HSO5, both the LP lamp and LED achieved a total degradation of OA. In the case of the marine matrix, the effect is clearly inhibited for the UV/H2O2 process; however, for UV/ HSO5, salinity does not seem to affect OA degradation, obtaining practically 100% removal. The study of new UV-LEDs would favor aquaculture activities by increasing sustainability and health safety. Likewise, the results obtained might provide the basis for a possible scale-up of technological processes specifically designed for the minimization of marine biotoxins.

How to cite: Moreno-Andrés, J., Lage, S., Braga, A. C., Romero-Martínez, L., Acevedo-Merino, A., Nebot, E., and Costa, P. R.: Photo-driven processes for the removal of biotoxins derived from Harmful Microalgal Blooms, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12693, https://doi.org/10.5194/egusphere-egu23-12693, 2023.

EGU23-15429 | ECS | PICO | HS7.3

Effect of distance of crop canopy temperature observations on Crop Water Stress Index 

Aditi Yadav, Hitesh Upreti, and Gopal Singhal

The need for water management in the agriculture sector, which is a 70% consumer of global water resources, is imperative. For the same, a plant-based index called crop water stress index (CWSI) is widely being adopted for irrigation scheduling. An empirically derived CWSI is dependent on three parameters of canopy temperature (Tc), air temperature (Ta), and relative humidity (RH).This study was conducted by performing controlled crop experiments in the arid region of Uttar Pradesh state of India, which aims to evaluate the significance of height of Tc observations, taken from March to April 2022, on CWSI calculations for the wheat crop.This has been done by observing theTc by aiming the wheat crop from the top of the crown at two distances of 10 cm and 100 cm, respectively. Handheld remote sensingdevice known as infrared thermometeris used for the observation of canopy temperature. Variation in the height from 10 cm to 100 cm leads to a variation in the field of view from 51.28 sq. cm to 5128 sq. cm. The effect of enhanced area and the involvement of extra soiland vegetation pixels can be understood by this work. Five different irrigation regimes have been provided to study the effect of change in height for Tc observations. The regimes consist of five plots 1,2,3,4, and 5 with soil moisture depletion by the following percentage respectively: 50% in drip irrigation, 25% in drip irrigation, unregulated flood irrigation, 50% in flood irrigation, and no irrigation plot.Plot 2 has been used to formulatea lower baselinefor CWSI calculations. A lower baseline represents a non-water-stressed condition of the crop where the crop is provided with sufficient irrigation treatment leading towards negligible stress conditions. The lower baseline equations used for CWSI assessment for 10 cm and 100 cm height are -1.287(VPD) -2.19 and -1.214(VPD)-1.738, respectively. VPD represents vapor pressure deficit which is a function of Ta and RH. Upon increasing the height from 10 cm to 100 cm, Tc increased by 2.1%, 2.7%, 0.6%, 0.9%, and 1.3% for plots 1,2,3,4, and 5, respectively. This change in temperature led to a decrease in CWSI by 21.8%,36.4 %,9.2%, and 12.2% in plots 1, 2, 3, and 4 respectively. An increase in CWSI by 5.8% for a rise of 1.3% in Tc for plot 5 was also noted. Further coefficient of determination R2 was observed between CWSI at 10 cm height and CWSI at 100 cm height for all plots. It was observed to be 0.65, 0.50, 0.93, 0.93, and 0.87 for plots 1, 2, 3, 4, and 5, respectively. This study shows the effect of observation distance of crop canopy temperature on CWSI that can lead to the development of sampling procedures meant for CWSI studies.

How to cite: Yadav, A., Upreti, H., and Singhal, G.: Effect of distance of crop canopy temperature observations on Crop Water Stress Index, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15429, https://doi.org/10.5194/egusphere-egu23-15429, 2023.

Agricultural water use comprises the major part of the total water consumption in many countries, and Taiwan is no exception. However, urbanization and industrialization have triggered the competition for water among different sectors. Water is transferred to satisfy the daily need and industrial need, especially the need of high-tech industries, from the agricultural sector. Groundwater hence becomes an alternative water resource for agriculture, but the over-exploitation of groundwater resources also leads to some problems such as environmental degradation and land subsidence, and climate change has worsened the situation in the recent years.

In Taiwan, groundwater is one of the vital water resources for irrigation, especially when the first crop rice begins being cultivated in the late dry season in central Taiwan. Yunlin County located in central Taiwan is chosen as the study area, which is now facing severe issues about groundwater over-exploitation and suffering from land subsidence threatening the safety of Taiwan High Speed Rail. Because of the high water consumption, groundwater extraction from agriculture is deemed to be the major cause of the land subsidence and should be well monitored and reduced. However, farmers’ pumping behaviors are highly related to the national water allocation policy, food policy and the socioeconomic factors in the rural area. The top-down agricultural water management might not be sufficient and sustainable. Hence, in this study, we propose a participatory framework for agricultural water management using a Bayesian network. The framework tries to incorporate the main factors that affect decision making among different stakeholders, including the Water Resources Agency, Irrigation Agency, Agriculture and Food Agency, farmers, etc., and represent the causal relationship among factors through Bayes’ theorem, or the conditional probability tables (CPTs). The CPTs are constructed based on data, literature reviews and interviews with stakeholders. The key issues concerning different stakeholders are considered in the framework as well, such as surface water shortage for agriculture, land subsidence, and sustainability of agriculture in Yunlin. The network can be used to hold discussions with stakeholders and show the interactions of their decisions among others. The aim of this framework is to facilitate the discussions and formulate the strategies for sustainable agricultural water management with the aid of the intuitive and transparent structure of the Bayesian network.

How to cite: Lee, S.-Y. and Yu, H.-L.: Using Bayesian network to build a participatory framework for sustainable agriculture water management in Yunlin, Taiwan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15459, https://doi.org/10.5194/egusphere-egu23-15459, 2023.

Irrigation plays a crucial role in alleviating the negative effects of drought on crop production. However, increasing competition for water by other sectors, such as industry and domestic use, increases the pressure on available water supplies. Under these circumstances, agricultural producers must be able to manage their available supplies efficiently to optimize irrigation water use. The objective of this research is to develop a decision support system (DSS) for optimizing irrigation scheduling for cotton production using Deep Reinforcement learning (DRL). Our approach uses multiple DRL algorithms that enable an intelligent agent to learn cotton irrigation needs in an interactive environment by trial and error using feedback from its past actions and experiences. Aquacrop is used as an environment (cotton field) simulator and is coupled with a DRL model to simulate crop yield for different actions taken by the agent. Our proposed software estimates the daily irrigation needs of a 7-acre crop field irrigated by a center pivot system located at Clemson University's Edisto Research and Education Center (REC), near Blackville, South Carolina. This new system enables a closed-loop control scheme to adapt the DSS to local perturbations such as soil moisture and rainfall variabilities.

How to cite: Umutoni, L.: An Intelligent Irrigation Decision Support System for Optimizing Cotton Water Use, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16787, https://doi.org/10.5194/egusphere-egu23-16787, 2023.

EGU23-142 | ECS | Posters on site | HS8.1.1

Aggregation Kinetics and Stability of Biodegradable Nanoplastics: Effects of Weathering and Proteins 

Yingxue Yu, Markus Flury, Anton Astner, Douglas Hayes, Tahsin Zahid, and Indranil Chowdhury

Plastic pollution caused by conventional plastics has promoted the development and application of biodegradable plastics. However, biodegradable plastics do not degrade readily in water, instead, they can generate countless micro- and nanoplastics. Compared to microplastics, nanoplastics are more likely to cause negative impacts to the aquatic environment due to their smaller size. The impacts of biodegradable nanoplastics highly depend on their aggregation behavior and colloidal stability, which still remain unknown. Here, we studied the aggregation kinetics of polybutylene adipate co-terephthalate (PBAT) nanoplastics in both NaCl and CaCl2 solutions before and after artificial weathering. We further studied the effect of proteins on aggregation kinetics with both negatively charged bovine serum albumin (BSA) and positively charged lysozyme (LSZ). We found that divalent cations (Ca2+) destabilized PBAT nanoplastics more aggressively than monovalent cations (Na+); weathering stabilized PBAT nanoplastics profoundly, with no aggregation observed in NaCl nor in CaCl2; both BSA and LSZ promoted the aggregation of pristine PBAT nanoplastics, with LSZ showing more pronounced effect. These results suggest that biodegradable nanoplastics, especially weathered biodegradable nanoplastics, are highly stable in the aquatic environment.

How to cite: Yu, Y., Flury, M., Astner, A., Hayes, D., Zahid, T., and Chowdhury, I.: Aggregation Kinetics and Stability of Biodegradable Nanoplastics: Effects of Weathering and Proteins, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-142, https://doi.org/10.5194/egusphere-egu23-142, 2023.

EGU23-196 | ECS | Posters on site | HS8.1.1

Foam Composition and Surfactant Sources in an Urban Foaming Lake: A Comprehensive Analysis 

Reshmi Das, Chanakya Hoysall, and Lakshminarayana Rao

Foaming of surface water bodies is a common concern of many major metropolitan cities globally. These hideous and persistent foams disturb aquatic ecosystems and also emit an obnoxious stench. These foams also overflow onto the surrounding roads, causing pedestrians discomfort and traffic disruption. Even though foaming of the aquatic system is a widespread phenomenon, it is not entirely scientifically understood yet. The central unexplored question in this domain is - what compounds make up a foam? To answer this question, it is vital to understand the physics of foaming, the properties of a compound that helps in foaming, and its chemical/physical influence on the distribution of other compounds and species in a water body.

 Foam is caused by surface-active compounds called surfactants. In aquatic environments, the surfactants may be either endogenous or anthropogenic in origin. In nutrient-rich waterbodies, decaying plants and microorganisms can be a potential endogenous source of surfactants. Commercially used surfactants in households and industries find their way into the aquatic ecosystem through untreated effluents discharged after anthropogenic activities. These foams, by the mechanism of foam fractionation, also tend to enrich many organic and inorganic compounds into the foam phase. Enrichment might lead to precariously high concentrations of surface-active contaminants in the foam phase, which would otherwise be within acceptable levels in bulk lake water. Thus, foam not only has surfactants but also has other enriched chemical compounds in it.

This work aims to identify those compounds in foam, focusing on sewage-fed Bellandur lake in India, which has been infamous for foaming for the past decade and understand their environmental implications. Bellandur Lake has anionic surfactant concentrations reaching up to 20 mg/l and surface tension as low as 45 mN/m. The Lake is eutrophied, with chlorophycean algae concentration reaching up to 13.8×107 cells/mL of Lake water. The scope of this study is as follows:

  • to assign relative flux to surfactants from various sources and identify the most significant contributor to foaming events;
  • to estimate the relative difference in concentrations of contaminants in bulk liquid and foam phase and predict the possibility of an impending threat, if any.

This study thus provides an opportunity for a better understanding of the foaming pattern, which is essential to prevent the occurrence of such foaming events in future.

How to cite: Das, R., Hoysall, C., and Rao, L.: Foam Composition and Surfactant Sources in an Urban Foaming Lake: A Comprehensive Analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-196, https://doi.org/10.5194/egusphere-egu23-196, 2023.

EGU23-813 | Posters on site | HS8.1.1 | Highlight

Identifying wastewater pollutants from pharmaceutical residues and xenobiotic contaminants in Indian secondary cities 

Shubham Kumar, Indra Mani Tripathi, and Pranab Kumar Mohapatra

Emerging contaminants are becoming more prevalent in the environment. The consequences of emerging contaminants on the urban environment and living being's health are poorly understood by society. Pharmaceutical compound removal is not considered in designing a conventional sewage treatment facility. Instead, they were primarily concerned with organic and bacterial removal. Molecules containing xenobiotics whose physicochemical characteristics, such as small molecular size, water solubility, ionizability and volatility, make it challenging to identify, quantify, and degrade these complex chemicals. In the present study, we will take samples from Surface Water (SW) and Wastewater Treatment Plants (WTP) in the fast-growing Indian secondary cities (Bhopal, Bhuj and Kozhikode). We use analytical methods, including High-Performance Liquid Chromatography (HPLC) and Gas Chromatography (GC) coupled with Mass Spectrometry (MS) to identify these compounds. The mentioned techniques have the potential to characterise complex environmental chemicals at low concentrations. In addition, Wetlands Construction can be an alternative and affordable technology for emerging compound treatment that performs satisfactorily for a variety of sewage types, including domestic sewage and wastewater. Our study identifies the contaminants present in the environment and the most popular analytical techniques for identifying and quantifying these compounds. We also present some potential solutions for the treatment of compounds by fusing several other technologies. This shows that in order to lessen or stop the deposition of these compounds into the environment, sewage treatment technologies need to be investigated and combined.

How to cite: Kumar, S., Tripathi, I. M., and Mohapatra, P. K.: Identifying wastewater pollutants from pharmaceutical residues and xenobiotic contaminants in Indian secondary cities, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-813, https://doi.org/10.5194/egusphere-egu23-813, 2023.

With the increasing research on particles and biocolloids in terrestrial and aquatic systems, the transport and deposition of particles and biocolloids in porous media has become an important research topic. Based on the transport and deposition experiments of heavy metal pollutants and suspended-colloidal particles (SPs) in porous media, a nonlinear attachment-detachment model with adsorption hysteresis is proposed, which uses an adsorption function and scanning desorption isotherms to model the deposition effect of SPs. The reaction rate constant related to hysteretic characteristics essentially reflects the nonequilibrium hydrodynamic process during the transport of SPs. Static deposition tests and column experiments with pulse injection are used to calibrate the transport parameters. Column penetration experiments are performed under variable injection concentrations and seepage velocities. The results show that there is good agreement between simulated and experimental breakthrough curves (BTCs).

This model shows that increasing or decreasing the seepage velocity results in substantial changes in the penetration concentration of SPs, which is closely related to the adsorption hysteresis and the deposition dynamics of SPs. When the injection concentration is increased, the effluent concentration clearly increases, which reflects a nonlinear deposition process. In contrast, with a decrease in the injection concentration, the release effect of the already deposited SPs prolongs the penetration process, which is also related to the hysteresis. Previously proposed linear attachment-detachment models probably result in an overestimation of the adsorption capacity of porous media.

How to cite: Bai, B., Wu, H., and Bai, F.: A nonlinear attachment-detachment model with adsorption hysteresis for suspension-colloidal transport, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1194, https://doi.org/10.5194/egusphere-egu23-1194, 2023.

The wide application of industrial and consumer product leads to the ubiquitous presence of PFOA (an anionic surfactant) in natural environments. PFOA could interact with microplastics (one emerging pollutants abundant in environments) and the transport of both PFOA and microplastics thus might be altered. The cotransport behaviors of PFOA with micron-sized plastic particles (MPs) with different surface charge (both negative and positive surface charge) in porous media in both 10 and 50 mM NaCl solutions were investigated in present study. Both types of MPs (negatively charged carboxylate-modified MPs (CMPs) and positively charged amine-modified MPs (AMPs)) could adsorb PFOA onto MPs surfaces which decreased PFOA transport with MPs co-present in suspensions under both solution conditions examined. PFOA had diverse impact on the transport behaviors of CMPs and AMPs. Specifically, PFOA decreased the transport of CMPs, while increased the transport of AMPs when PFOA was copresent in suspensions. The mechanisms driving to the changed transport of two types of MPs induced by PFOA were found to be different. The decreased electrostatic repulsion of CMPs due to the adsorption of PFOA onto CMPs surfaces led to the decreased transport of CMPs when PFOA was copresent. The increased electrostatic repulsion due to the adsorption of PFOA onto AMPs surfaces as well as the steric repulsion induced by suspended PFOA caused the enhanced AMPs transport with PFOA in solutions. The results of this study show that when PFOA and microplastics are copresent in natural environments, their interaction with each other will alter their transport behaviors in porous media, and the alteration is highly correlated with the surface charge of MPs.

How to cite: Rong, H. and Tong, M.: Cotransport of PFOA with Different Electrically Charged Plastic Particles in Saturated Porous Media, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1651, https://doi.org/10.5194/egusphere-egu23-1651, 2023.

The release of microplastics (MPs) especially those with sizes less than 10 μm from effluent of wastewater treatment plants (WWTPs) is one of the major sources of plastics into aquatic environment. To reduce the discharge of MPs into environment, it is essential to further enhance their removal efficiencies in WWTPs. In present study, to boost the removal performance of MPs in sand filtration systems (units that commonly employed in WWTPs to remove colloidal pollutants), six types of biochar fabricated from three raw biomass materials (i.e. lignin, cellulose, and woodchips) at two pyrolysis temperatures (400 °C and 700 °C) was respectively amended into sand columns as thin permeable layer. We found that adding all six types of biochar into sand columns as thin permeable layer could greatly improve the retention of MPs with the diameter of 1 μm under either slow (4 m/d) or fast flow rates (160 m/d) due to the high adsorption capability of biochar. Woodchip-derived biochar exhibited the highest MPs retention performance, which was followed by cellulose-derived biochar and then lignin-derived biochar. Moreover, for biochar derived from three raw biomasses, increasing pyrolysis temperature could improve MPs retention performance. The direct observation of real-time plastics retention processes on different types of biochar via a visible flow chamber showed that woodchip-derived biochar especially that fabricated at 700 °C exhibited more MPs trapping processes relative to lignin and cellulose-derived biochar due to their more complex surface morphology. Thus, the highest MPs retention performance was achieved in sand columns with amendment by 1 wt% woodchip-derived biochar fabricated at 700 °C. More importantly, we found that for these modified sand filtration column systems, complete MPs removal could be achieved in real river water and actual sewage water, in multiple filtration cycles, longtime filtration process (100 pore volumes injection) as well as with interval flow conditions. Moreover, biochar could be regenerated and reused as thin permeable layer to effectively remove MPs. The results of this study clearly showed that biochar especially woodchip-derived biochar fabricated at 700 °C had the potential to immobilize MPs especially those with small sizes in WWTPs.

How to cite: Hsieh, L. and Tong, M.: Addition of biochar as thin preamble layer into sand filtration columns could improve the microplastics removal from water, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1771, https://doi.org/10.5194/egusphere-egu23-1771, 2023.

EGU23-2118 | Posters on site | HS8.1.1

Transport of thiophanate methyl in porous media in the presence of titanium dioxidenanoparticles 

Constantinos V. Chrysikopoulos, Anthi S. Stefanarou, Vasileios E. Katzourakis, and Anastasios A. Malandrakis

This study investigates the transport of pesticide thiophanate methyl (TM) as well as the co-transport of TM and titanium dioxide (TiO2) nanoparticles in a water saturated column packed with quartz sand under various water conditions. Several ionic strengths (Is) (1, 10, 50 and 100 mM) and pH (3, 5, 7, 10) values were examined. The results from the transport experiments  were fitted and analyzed with the use of the ColloidFit software, while the results from cotransport experiments were fitted with a modified mathematical model of Katzourakis and Chrysikopoulos (2015). The results suggested that the lowest mass recovery rate was for the co-transport experiments with the addition of NaCl. It was shown that TM has a weak affinity for sand but a relatively strong affinity for TiO2 at high Is and acidic pH. Furthermore, salinity was shown to have significant effects on TM removal.

How to cite: Chrysikopoulos, C. V., Stefanarou, A. S., Katzourakis, V. E., and Malandrakis, A. A.: Transport of thiophanate methyl in porous media in the presence of titanium dioxidenanoparticles, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2118, https://doi.org/10.5194/egusphere-egu23-2118, 2023.

EGU23-2570 | ECS | Orals | HS8.1.1

Zinc nanoparticles combat boscalid-resistance in Alternaria alternata 

Anastasios Malandrakis, Nektarios Kavroulakis, and Constantinos Chrysikopoulos

The potential of ZnO nanoparticles (NPs) to control Alternaria alternata isolates resistant to the succinate dehydrogenase inhibitor (SDHI) boscalid was evaluated both in vitro and in vivo. ZnONPs could effectively inhibit mycelial growth and suppress disease symptoms in both boscalid sensitive (BOSC-S) and resistant (BOSC-R) isolates. A high synergistic effect against BOSC-S and BOSC-R isolates was observed when ZnO-NPs was combined with boscalid both in vitro and when applied in artificially inoculated tomato fruit. The positive correlation between nanoparticles and their ionic counterpart ZnSO4 and the neutralization of the ZnO-NPs fungitoxic action in the presence of EDTA suggested that zinc ion release is the most probable fungitoxic mechanism of ZnO-NPs. The disruption of cellular ion homeostasis mechanisms by zinc NPs could account for the enhanced effectiveness of ZnO-NPs against A. alternata  compared to ZnSO4. ATP-dependent ion efflux and ROS production could contribute to the fungitoxic action of ZnO-NPs as indicated by bioassays with ATP- and antioxidant-inhibitors. Boscalid acting as a “capping” agent for ZnO-NPs, significantly reducing NPs mean size, probably accounted for the synergy observed against BOSC-S and BOSC-R isolates. Concluding, ZnO-NPs are effective against A. alternata both alone or in mixtures with boscalid, and can be used as an effective, eco-compatible anti-resistance tool for reducing the environmental footprint of synthetic fungicides.

How to cite: Malandrakis, A., Kavroulakis, N., and Chrysikopoulos, C.: Zinc nanoparticles combat boscalid-resistance in Alternaria alternata, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2570, https://doi.org/10.5194/egusphere-egu23-2570, 2023.

EGU23-2785 | ECS | Orals | HS8.1.1

Thermal impact of underground car parks on groundwater 

Maximilian Noethen, Hannes Hemmerle, Susanne Benz, Kathrin Menberg, Jannis Epting, Philipp Blum, and Peter Bayer

In addition to the continuous increase of groundwater temperatures due to global warming, heat losses from infrastructure, (underground) buildings and geothermal use lead to thermal anomalies on regional to local scales. Often, these local heat accumulations (hot spots) of groundwater temperatures are associated with underground car parks (UCP). They represent sizeable infrastructures that are typical for densely built-up areas and are numerous in many cities. Unlike regular basements, they often reach beneath the groundwater table and heat up due to frequent traffic. They therefore act as heat sources for groundwater. By analysing long-time data from 31 sites in Germany, Austria, and Switzerland, we discovered seasonally varying heat flux intensities and even directions. While all UCPs heat the groundwater during the warm period, most UCPs cool the groundwater in the cold period. Only few act as continuous heat source all year round. We also discuss characteristics and their influence on the temperature such as the type of use (public/private) and the depth of the UCP. Furthermore, we present the results of a spatial analysis of heat fluxes and flows from over 5000 UCPs in Berlin, Germany. By discussing the range of heat fluxes and the hydrogeological conditions that lead to regional differences, we demonstrate the role of UCPs for subsurface urban warming. The results show that about 40 % of Berlin’s total heat flow from UCPs occurs in the “Mitte” district, where the density of UCPs is highest and the distance to the groundwater table is typically below 4 m. Finally, the knowledge gained about subsurface heat sources can help improve urban thermal groundwater management and highlights the potential for recovering waste heat from UCPs through geothermal applications.

How to cite: Noethen, M., Hemmerle, H., Benz, S., Menberg, K., Epting, J., Blum, P., and Bayer, P.: Thermal impact of underground car parks on groundwater, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2785, https://doi.org/10.5194/egusphere-egu23-2785, 2023.

EGU23-3082 | ECS | Posters on site | HS8.1.1

Numerical modeling of flow in a phosphogypsum stack. Case of salt-marshes, Huelva, SW Spain. 

Franco Coscia, Enric Vázquez-Suñè, and Estanislao Pujades

Phosphogypsum is a waste that results when fertilizer is obtained from phosphate through a wet chemical process. Phosphogypsum waste can entail negative consequences for the environment and human health since it is enriched in radionuclides from U-decay series and metal impurities. Phosphogypsum wastes are commonly accumulated in large stockpiles that are exposed to weathering processes. These stockpiles are located near the plants where phosphate is processed, which are usually located in coastal areas. This is the case of a phosphogypsum stack on the western side of the Tinto River estuary (Huelva, SW Spain), where the piles were directly settled on the marshland without using any isolation from 1968 to 2010. Here, in addition to the potential environmental impacts, the effect of the phosphogypsum wastes on human health are a source of concern since the piles are located near the city of Huelva (Spain). In this context, it is of paramount importance to assess the phosphogypsum leachate percolation into underlaid aquifer systems and the release of pollutants to the Tinto River.

This investigation aims at building a complex coupled hydro-chemical numerical model accounting with variable density to quantify how the pollutants are released to the environment. The first step has consisted in developing the flow numerical model that has been calibrated by fitting the piezometric head oscillations as a result of recharge processes and sea tide oscillations. The good fitting obtained during the calibration process (normalized RMS when comparing simulated and observed piezometric heads is less than the 10%) allows affirming that the estimated hydraulic parameters are accurate, and are consistent with the literature reviewed. Furthermore, the numerically calculated mass balance is consistent with the conceptually estimated one, the differences were as expected. Thus, the model allows simulating the flow processes and modelling predictive scenarios. The next steps will consist in implementing variable density and hydro-chemical, and possibly, hydromechanical processes.

This study, which uses numerical modelling, is intended to be useful for future work related to restoration measures and provides new insights into the water balance along with the complex processes occurring at the site.

How to cite: Coscia, F., Vázquez-Suñè, E., and Pujades, E.: Numerical modeling of flow in a phosphogypsum stack. Case of salt-marshes, Huelva, SW Spain., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3082, https://doi.org/10.5194/egusphere-egu23-3082, 2023.

Groundwater located in peri-urban areas may be impacted by many pollutants from different types of point or diffuse sources. About 40% of Brazil's waste is disposed of inappropriately in open dumps and constitutes a risk of contamination for aquifers. In the metropolitan region of the city of Salvador in northeastern Brazil, approximately 9,800 tons of solid waste are generated daily. This research aimed to delineate areas for the implementation of landfills and protection of peri-urban groundwater in Salvador and other catchments in northeastern Brazil. An integration of Boolean and fuzzy logic was performed using GIS, while the Analytic Hierarchy Process was used in a Multi Criteria Decision Analysis technique to generate the weights of the factors and criteria for the fuzzy model. From this methodology, two preliminary models were generated, one using the Boolean logic and the other the fuzzy logic. The first used restrictive criteria established by Brazilian legislation applied to fifteen factors/themes. In the second model, non-restrictive criteria were applied to eleven factors/themes based on technical knowledge and literature. The integration of the maps and the crossing of the models demonstrates that 6% of the studied areas are classified as highly adequate; 16% as adequate; 8% not suitable; and 70% are areas with total restrictions for locations of landfills and protection of aquifers.

How to cite: Leal, L., Purificação, C., Klammler, H., and Hatfield, K.: GIS‐based multi-criteria decision analysis for suitable locations of landfills and protection of peri-urban groundwater catchments: a case study in northeastern Brazil, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4754, https://doi.org/10.5194/egusphere-egu23-4754, 2023.

EGU23-5588 | ECS | Posters on site | HS8.1.1 | Highlight

What are the driving factors affecting urban groundwater quality? A multi-tracer approach for the assessment of Vienna’s shallow aquifers 

Eva Kaminsky, Constanze Englisch, Christian Griebler, Cornelia Steiner, Gregor Götzl, Kay Knoeller, Hans Sandén, Gregor Laaha, and Christine Stumpp

Urban shallow groundwater is highly impacted in terms of hydrogeology and water quality by anthropogenic activities and infrastructure, such as heating and cooling, surface sealing, leaking sewage pipes, and underground buildings. For a sustainable management of urban water resources, a better understanding of biogeochemical processes and its dynamics on a spatial and temporal scale in the urban subsurface is needed. So far, data sets including a critical minimum number of key parameters and an appropriate resolution in space and time have often been missing. Here, we introduce a multi-tracer approach applied to assess the shallow aquifers in Vienna. Water samples were collected twice, in autumn 2021 and spring 2022, respectively, from 150 groundwater wells in the city limits of Vienna. A comprehensive set of parameters (e.g. major ions, nutrients, heavy metals, water and nitrate stable isotopes) were analyzed to evaluate the spatial and seasonal variations in water origin and quality. Statistical analysis revealed that driving factors influencing groundwater quality include aquifer properties, interactions between groundwater-surface water, and redox conditions. A combined interpretation of conservative tracers indicated zones influenced by surface water - groundwater interactions that also influenced the water chemistry. Microbial anaerobic processes govern groundwater quality. In particular, contamination of nitrate from septic water and manure is locally reduced by denitrification, as proven by compound-specific isotope analysis, improving water quality. At the same time, other anaerobic processes, such as iron and manganese reduction, sulfate reduction, and methanogenesis deteriorate water quality. Finally, groundwater temperatures, up to 27°C, were observed close to urban underground infrastructure, hinting at subsurface buildings and surface sealing as stressors in shallow groundwater. In conclusion, our high resolution spatial sampling with the large set of parameters will not only allow a better understanding of groundwater quality dynamics, but also allows to evaluate effects to groundwater biodiversity and develop predictive mathematical models.

How to cite: Kaminsky, E., Englisch, C., Griebler, C., Steiner, C., Götzl, G., Knoeller, K., Sandén, H., Laaha, G., and Stumpp, C.: What are the driving factors affecting urban groundwater quality? A multi-tracer approach for the assessment of Vienna’s shallow aquifers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5588, https://doi.org/10.5194/egusphere-egu23-5588, 2023.

EGU23-7356 | Orals | HS8.1.1

A holistic view of water sources in Kyiv, Ukraine using tap water, surface water, groundwater, and precipitation hydrogen (𝛿2H) and oxygen (𝛿18O) stable isotope ratios 

Andrea Erhardt, Elizabeth Avery, Olena Samonina, Lidiia Kryshtop, Iryna Vyshenska, and Alan Fryar

The water supply for Kyiv (Ukraine) is a seasonally and spatially variable mixture of both ground and surface water. This water supply is vulnerable to the effects of climate change, pollution, and geopolitical conflict. Climate change has resulted in changing precipitation patterns, potentially altering the balance between ground and surface water utilization. Additionally, the ongoing conflict makes a holistic understanding of water resources and pathways critical for water management. This study uses water stable isotopes as tracers for water sources and the importance of different reservoirs in water management.

For this study tap water, surface water, groundwater, and precipitation were collected over 14 months (2019-2020) in Kyiv and nearby Boryspil, Brovary, and Boyarka and measured for hydrogen (𝛿2H) and oxygen (𝛿18O) stable isotope ratios. Precipitation data was used to capture seasonal variability in storm trajectories and create a meteoric water line. These results were then compared to surface, ground, and tap water to capture water sources and residence times.

The stable isotope values from the tap water for each district show a general seasonal trend in water sources, with more groundwater used in the supply in the winter for most districts. Spatially, groundwater use increases from south to north in the left-bank districts in Kyiv city and groundwater use generally decreases from south to north in the right-bank districts. As precipitation patterns shift and temperatures increase, the reliance on particular water sources may need to shift as well.

 Overall, 𝛿2H and 𝛿18O data provide a baseline expectancy for current water use throughout the year and, from this, deviations can be assessed early. A holistic view of the water system will be critical to assess changes due to infrastructure damage and/or other impact on water management in the Kyiv region.

How to cite: Erhardt, A., Avery, E., Samonina, O., Kryshtop, L., Vyshenska, I., and Fryar, A.: A holistic view of water sources in Kyiv, Ukraine using tap water, surface water, groundwater, and precipitation hydrogen (𝛿2H) and oxygen (𝛿18O) stable isotope ratios, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7356, https://doi.org/10.5194/egusphere-egu23-7356, 2023.

Abandoned mines can play a new role in renewable energy production and storage in combination with fifth-generation heating and cooling networks. Obviously, the underground potential must be matched with the uses/productions of heat and cold by surface activities. Therefore, this will be considered here only in highly urbanized areas or in economic and industrial areas.

Flooded abandoned mines form highly heterogeneous aquifers that are artificially and locally highly permeable around former underground works (i.e., tunnels, galleries, mined extraction zones, wells, shafts). Thermal energy storage (ATES) systems, using heat pumps and an open loop with a groundwater pumping and re-injection doublet, are thus challenging and uncertain in such a variable underground environment. Hot water is pumped in the deepest parts of the open network, and cold water can be re-injected in the shallower parts (i.e. in shallower galleries or fractured rocks). A seasonal inversion could be planned for cooling the buildings during the summer season. However, the true geometry of the interconnected network made of old open galleries and shafts can be highly complex and partially unknown. Indeed, high-velocity water flow and heat transport are expected in this network inducing potentially a full or partial bypass of the fractured and porous rock massif.

A hydrogeological characterization of the old mined zones for detailed simulations of the groundwater flow and associated heat transport is thus a needed step allowing to assess the actual feasibility of a given project. The simulated short-, mid-, and long-term temperature evolution in pumping and injection zones will consist of key information for designing and dimensioning the whole geothermal project and assessing future efficiency and impact. Depending on the degree of precision required, which is dependent on the level of reduction of uncertainties associated with the geothermal project, the hydrogeological baseline issues can be very significant, challenging scientists in different areas of quantitative hydrogeology:

  • conceptualization in a simple model of the often unknown complexity/heterogeneity of the galleries network conjugated to those of the mined geological formations;
  • simulation of temperature-dependent variable-density groundwater flow and coupled heat transport;
  • combining high-velocity ‘pipe-like’ water flows (in the shafts and galleries) and porous/fractured groundwater flow (in the rock matrix);
  • simulation of different transient scenarios to assess evolutions in the long term.

As an illustration, a simplified but realistic situation is simulated showing the influence of the highly different heat/cold transport in the galleries and shafts, compared to the propagation in the porous/fractured rocks. Indeed, the different temperature evolutions allow anticipating the temperature changes affecting the future (short-, mid-, and long-term) efficiency of a geothermal system as well as possible environmental impacts.

Real cases in relation to future projects should ideally be simulated using the most detailed approaches, with true data. Those baseline hydrogeological data are not easy to obtain but they are the guarantee of reliable predictions and therefore that the financial risk is reasonable.

Dassargues A., 2018. Hydrogeology: groundwater science and engineering, 472p. Taylor & Francis CRC press, Boca Raton.

How to cite: Dassargues, A. and Orban, P.: Hydrogeological baselines for geothermal energy and heat storage in old flooded coal mines in urban areas, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7715, https://doi.org/10.5194/egusphere-egu23-7715, 2023.

EGU23-7878 | Orals | HS8.1.1 | Highlight

Potential and limitations of silica encapsulated DNA particles for hydro(geo)logy 

Jan Willem Foppen and Thom Bogaard

Artificial DNA as a tracer in environmental applications has received increased attention in environmental science. In the last few years, we have been looking at the transport of silica encapsulated DNA particles (SiDNA), which we injected instantaneously or as a function of time in various saturated groundwater and surface water laboratory set-ups. These included batches, columns, sand tanks, open pipes, trenches, flumes, etc. The overarching aim of all these experiments was to understand SiDNA transport behaviour, to quantify the mass balance and to assess tracer-like capabilities of SiDNA. Our work indicated that in most applications, the shape of the breakthrough curve in terms of time to rise and time to peak were similar to the breakthrough curve of a conservative tracer. Specifically, SiDNA could be used to quantify dispersion in surface water transport, and to determine aquifer parameters, like hydraulic conductivity and porosity in multi-tracer experiments. However, this was accompanied by some uncertainty as in most applications, injected mass recoveries were less than 100% due to losses as a result of settling, river bed interactions, interactions with particulate matter (in surface water applications), straining, kinetic attachment and detachment (in groundwater applications). 
We conclude that SiDNA can be used when mass balance issues are relatively unimportant, for instance in case of complex flow path analyses or source tracking applications, whereby encapsulated artificial DNA with different DNA strands can be injected in several locations or can be added to the source. Currently, we think large scale field applications of SiDNA are still limited, due to required specific knowledge and analytical infrastructure, relatively high costs and limited SiDNA production scale. Once these issues are tackled, a truly unique multi-tracer will enrich the toolbox of hydrologists.

How to cite: Foppen, J. W. and Bogaard, T.: Potential and limitations of silica encapsulated DNA particles for hydro(geo)logy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7878, https://doi.org/10.5194/egusphere-egu23-7878, 2023.

EGU23-8241 * | ECS | Orals | HS8.1.1 | Highlight

300 years of organic pollution recorded in an urban speleothem (Paris, France) 

Julia Garagnon, Yves Perrette, Emmanuel Naffrechoux, and Edwige Pons-Branchu

The preservation of water resources and the limitation of pollution are an environmental central issue in the current intense anthropization context. Considered as sensitive recorders of past changes, speleothems offer an under investigated natural archive for the reconstruction of water quality. Urban speleothems have recently been used to show the impact of urbanization over the water quality using inorganic trace elements. Speleothems thus represent a promising archive of water quality on short and long-time scales. However, they have never been used to trace organic pollution. Within the organic and anthropogenic proxies, polycyclic aromatic hydrocarbons (PAHs) are commonly used in water quality analysis. These persistent organic pollutants (POPs) are mainly due to anthropogenic emissions. The use of speleothem to trace the variations in quantity and quality of organic matter, including organic pollutant as PAHs, over the last centuries, is unprecedented.

For this purpose, high resolution (10 µm) solid phase UV fluorescence imaging analyses were crossed with chemical analyses (PAHs, Non Purgeable Organic Carbon (NPOC)) carried out on low weight samples (a few mg to g) from a Parisian aqueduct flowstone. Solid-phase fluorescence imaging, although poorly applied yet to speleothems, is a non-destructive technique. To obtain quantitative information, solid phase spectroscopy is coupled with liquid phase compound analysis and NPOC analysis. Due to their low concentration, the analysis of PAHs required a long development phase. The protocol consists of an extraction and analysis process using high performance liquid chromatography coupled with a fluorescence detector. The first results reveal the presence of PAHs for 300 years in runoff water with an increase, in particular in heavy molecular weight PAHs, over the last two decades. These data will be crossed with modelled imaging of quantitative variations in organic matter. This work opens the way to a better long term understanding of the impact of anthropization on transfer of pollutants in subsurface waters.

How to cite: Garagnon, J., Perrette, Y., Naffrechoux, E., and Pons-Branchu, E.: 300 years of organic pollution recorded in an urban speleothem (Paris, France), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8241, https://doi.org/10.5194/egusphere-egu23-8241, 2023.

Nanoscience and nanotechnology have revolutionized many sectors of the industry with the development of novel materials and technologies. With the increasing use of nanomaterials in products and applications, the presence of nanoparticles in the environment, such as in soil, sediments, water, air, and biota, is inevitable. Understanding of the physical and chemical processes and environmental conditions that govern the fate and behavior of nanomaterials in the environment is essential to strengthen the environmental and human health security. This study discusses the role of physical and chemical processes and environmental conditions on the fate, transport, behavior, transformation, and toxicity of metal based nanoparticles and their environmental impacts, with a focus on terrestrial and aquatic systems, as well as plants and microorganisms. Research on the interactions of nanomaterials with the environment and biological systems will allow the development of models contributing to advancing knowledge on the behavior and fate of nanoparticles in the environment and assessing their potential risk in the environment.

How to cite: Darnault, C.: Nanomaterial Interactions with the Environment and Biological Systems: Implications for Soil, Water, Plants, and Microorganisms, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10830, https://doi.org/10.5194/egusphere-egu23-10830, 2023.

EGU23-10883 | Posters on site | HS8.1.1

The influence of microplastics on the dry end of the soil-water retention curve 

Hannes Laermanns, Markus Rolf, Susanne Forche, Elena Castrucci, Alexander Stelzer, and Christina Bogner

Most studies focus on the detection of microplastic particles in different compartments of the environment. While impacts of microplastics on aquatic systems have already a wide acceptance in public, the research on microplastics in terrestrial systems is quite young. Our study aims to decipher the consequences of microplastics on the soil-water retention curve beyond the wilting point. Using a dew point WP4C hygrometer, we measured water retention curves of loess and sand samples with added microplastics, namely amorphous biopolymer, polystyrene in two sizes and three different types of UV-aged particles. All the different microplastics were added in concentrations of 0.1 wt.%, 0.5 wt.%, and 4.5 mg/kg. Reference samples without microplastics were prepared as well. For the analysis, we fitted the Webb model and calculated the water content at the wilting point and the slope of the soil-water retention curve. Our preliminary results did not show any significant differences between the different microplastics and their concentrations, however, the lowest slope and highest water content at pF 4.2 were observed in the samples without microplastics. Furthermore, the results indicated a greater variability with increasing size of microplastic particles.

How to cite: Laermanns, H., Rolf, M., Forche, S., Castrucci, E., Stelzer, A., and Bogner, C.: The influence of microplastics on the dry end of the soil-water retention curve, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10883, https://doi.org/10.5194/egusphere-egu23-10883, 2023.

EGU23-11717 | ECS | Posters on site | HS8.1.1

Surrogate-based implementation of sewer network structures into numerical heat transport models: First results of the Basel-City case study 

Martin Binder, Felicia Kossek, Christian Engelmann, and Jannis Epting

Adequate management strategies are critically required to increase the resilience and long-term availability of groundwater resources in the light of progressive climate change and accelerating urbanization. Here, robustly parameterized numerical models, designed for simulating water flow as well as solute and heat transport processes in the hydrogeological subsurface, are powerful and widely established tools supporting decision making and planning.

Among other applications related to more general quantity- and quality-related questions, these numerical tools can be also used, e.g., for investigating the current thermal state of the subsurface and occurring changes due to artificial and natural influences. Models designed for this very specific task should include at least all major artificial objects (e.g., underground car parks, tunnels, buildings, sewer networks) which thermally contribute to the overall groundwater heat regime. For instance, the heat exchange between the subsurface and sewer systems may significantly contribute to the subsurface urban heat island effect and should, therefore, be implemented. However, fully three-dimensional implementations of sewer networks (typically with hundreds of kilometers of pipes) are mostly out of question when applying such numerical models, since it would be associated with large computational demands and increasing numerical instabilities.

To overcome this limitation, the focus of our ongoing research is to evaluate the suitability of an adaptive surrogate method to be coupled to existing numerical heat transport models. This method is based on linking expected thermal exchange rates between small subsurface objects (e.g., sewer pipes) and their surrounding area, which depend on site-specific parameters (e.g., surface-groundwater table distance, pipe dimensions, shapes and materials), with the spatial elements of an existing model mesh, e.g., as area-averaged heat sources or sinks. Numerical heat conduction simulations performed on pipe scale while employing seasonally changing ambient and sewer conditions point towards the importance of considering both stationary (such as materials) and transient input datasets (such as temperature fluctuations) in this linking process. The collection and pre-processing of both dataset types is performed in separate workflows employing standardized geographic information system (GIS) software. Based on these input datasets, heat flux calculations can be done either employing the numerical code itself (if the model code allows user-defined calculations) or, again, in a GIS-assisted step (in order to further reduce the computational demand during the runs of the numerical model).

The conceptual workflow, first results as well as expected advances and limitations of this surrogate approach will be critically discussed using the example of the well-documented heat transport case study of ‘Basel-City’. Among others, the aforementioned stationary and transient input datasets, and based on that, processed vertical heat fluxes will be presented for selected areas of the Swiss canton.

How to cite: Binder, M., Kossek, F., Engelmann, C., and Epting, J.: Surrogate-based implementation of sewer network structures into numerical heat transport models: First results of the Basel-City case study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11717, https://doi.org/10.5194/egusphere-egu23-11717, 2023.

EGU23-12562 | ECS | Orals | HS8.1.1

Microplastics in sediment deposited along the Seine River after a major flood event (February 2021) 

Nadia Bouzid, Remi Bizeul, Anthony Foucher, Sophie Ayrault, Olivier Evrard, Rachid Dris, Bruno Tassin, and Jonnhy Gasperi

Depending on hydrodynamic conditions, river sediments act as a sinks or a sources of microplastics through deposition and remobilisation processes. During flood events, the increase of river flow leads to an increase in the resuspension of bottom sediments and bank erosion processes and favoring the microplastic transportation. Previous work conduced in the Seine river catchment in 2018 has shown that floods, which occur for only 15% of the annual time, contributed to 40% of the total microplastic flux. Therefore, at the end of a flood period, with the decreasing in water level, some flow regimes allow the deposition of contaminated sediments carried by the river on the banks.

This study presents the characterization and quantification of microplastics in ten samples lag deposits collected along the Seine river after the February 2021 flood event. Microplastics from 10 to 500 µm were analysed in replicate samples using two methods (FTIR microspectroscopy and Pyr-GC/MS). In order to characterize the origin of the sampled sedimentary deposits a fingerprinting approach based on the measurement of radionuclides activity (137Cs, 210Pbex and 7Be) was carried out. A mixing model was applied to discriminate old and recent sediments and their origin from the surface (e.g. soil erosion) or subsurface (e.g. bank erosion). High concentration levels of microplastics, ranging from 8,000 to 50,000 items/kg, were observed mainly characterised by FTIR microspectroscopy as PP, PE, PS and PVC. All the samples analysed show a similar size distribution with a majority of particles below 100 µm. PP is the most abundant polymer found. The quantification by Pyr-GC/MS provided masses consistent with microspectroscopy results ranging from 200 to 14,000 µg PP/kg of dry sediment.  An increase in microplastic contamination between the upstream and the downstream part of the Paris area was observed. In this study, the relationships between sediment characteristics and microplastic contamination could not be demonstrated. Further work is needed to verify whether a more marked relationship can be observed in major events where a clearer variation in sediment sources is observed between the upper and lower parts of the Paris area.

How to cite: Bouzid, N., Bizeul, R., Foucher, A., Ayrault, S., Evrard, O., Dris, R., Tassin, B., and Gasperi, J.: Microplastics in sediment deposited along the Seine River after a major flood event (February 2021), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12562, https://doi.org/10.5194/egusphere-egu23-12562, 2023.

EGU23-12881 | Posters on site | HS8.1.1

Processes affecting the behaviour of persistent, mobile, and toxic substances in a riverbank filtration system 

Estanislao Pujades, Carmen Sáez, Olha Nikolenko, Laura Scheiber, Arianna Bautista, Marinella Farré, and Anna Jurado

Riverbank filtration (RBF) consists in forcing surface water to infiltrate and flow through an aquifer by means of a pumping well located near a surface water body. RBF aims to take advantage of the filtration capacity of aquifers to improve the water quality by removing a wide range of pollutants, including contaminants of emerging concern, by combining of physical, chemical and biological processes. However, the efficacy of RBF for eliminating substances that are considered persistent, mobile, and toxic (PMT), or very persistent and very mobile (vPvM), is expected to be low due to the high mobility of these substances. PMT and vPvM compounds, which are accumulated in the water cycle, are harmful to humans and the environment. For this reason, the processes affecting PMT and vPvM substances during RBF processes deserve to be deeply investigated.

This study aims at investigating the processes affecting PMT and vPvM substances in a site that behaves similarly to a RBF system. The study site is located in Sant Adriá del Besòs (Barcelona, Spain), where a constant pumping to drain an underground parking lot forces the water from the Besòs river to infiltrate and travel up to 230 m through the aquifer. Groundwater samples were collected from the river, and a set of piezometers aligned along the groundwater flow line between the Besòs river, and the underground parking lot allowed monitoring of the water at different stages after its infiltration. The samples were analysed by liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) and PMT and vPvM were determined by a suspected screening approach.

This investigation provides new insights into the processes affecting PMT and vPvM substances and will have tremendous implications for determining groundwater quality in managed aquifer recharge contexts.

How to cite: Pujades, E., Sáez, C., Nikolenko, O., Scheiber, L., Bautista, A., Farré, M., and Jurado, A.: Processes affecting the behaviour of persistent, mobile, and toxic substances in a riverbank filtration system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12881, https://doi.org/10.5194/egusphere-egu23-12881, 2023.

EGU23-12959 | Posters on site | HS8.1.1

Organic contaminants of emerging concern (OCECs) in urban aquifers affected by geothermal exploitations 

Anna Jurado, María Alejandra Villa, Marc Teixidó, Nicola Montemurro, Sandra Pérez, Jan Willem Foppen, and Estanislao Pujades

Water shortage is expected to exacerbate because of the increase pressure on water resources due to climate change and the growing population. It is deemed necessary to take advantage of all the available freshwater resources to cover the growing demand, especially in urban areas. However, urban aquifers are commonly contaminated by a wide range of organic contaminants of emerging concern (OCECs). OCECs, which comprise natural and synthetic compounds, are potentially hazardous to the environment and human health. Therefore, the processes controlling the behaviour of OCECs must be investigated to determine when and how the urban resources can be used safely and to design remediation strategies against them. The removal rate of OCECs depends on the temperature and redox conditions of groundwater that may be affected by anthropogenic activities like the exploitation of the geothermal potential of aquifers. The behaviour of some OCECs has been investigated in the context of managed aquifer recharge (MAR). However, the water range in MAR is lower than that expected around geothermal exploitations, and the behaviour of OCECs under similar conditions to that found around geothermal facilities should be evaluated. We have investigated the removal of 12 OCECs reported in the aquifers of Barcelona (Spain) by using batch experiments under different redox conditions and temperatures (25°C and 35°C). The results show that the removal rate of OCECs depends on the temperature, suggesting that the impact of geothermal exploitations must be considered when investigating the fate and evolution of OCECs in urban aquifers. Unexpectedly, it was observed that the removal rate could also decrease with the temperature, which may be related to the proliferation of different communities of bacteria depending on the temperature. Overall, this investigation supports the idea that it is possible to design geothermal facilities to promote the removal of OCECs.

How to cite: Jurado, A., Villa, M. A., Teixidó, M., Montemurro, N., Pérez, S., Foppen, J. W., and Pujades, E.: Organic contaminants of emerging concern (OCECs) in urban aquifers affected by geothermal exploitations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12959, https://doi.org/10.5194/egusphere-egu23-12959, 2023.

EGU23-14782 | ECS | Posters on site | HS8.1.1

Efficiency of activated sludge process for reduction of antibiotics from municipal wastewater  

Moushumi Hazra, Himanshu Joshi Joshi, and Bhanu P. Vellanki

With time, a lot of change in the nature of impurities, especially a surge in emerging contaminants in urban wastewater has been observed due to changing lifestyle, uncontrolled and mismanaged urban sprawl, increasing pollution and disease burden, and easy access to antibiotics. Conventional sewage treatment plants have thus faced challenges in treating emerging pollutants such as antibiotics, with variable success as reported in few studies.  Antibiotics are persistent in the environment and result into development of antimicrobial resistance. The concentration of antibiotics reportedly varies from µg/L to ng/L in raw/treated sewage which is generally dependent upon differences in environmental/social factors as well as treatment technology. The present study was conducted with the purpose of identifying the role of activated sludge process (ASP) in a standalone mode as well as in a hybrid mode duly integrated with upflow anaerobic sludge blanket reactor (UASB) in removal of antibiotics from the raw sewage. The antibiotics were analysed with a Liquid Chromatography Mass Spectrometer (LCMS), and the removal efficiencies were compared for both the treatment systems. The concentration of selected antibiotics in raw/treated sewage of the hybrid UASB-ASP varied in the range of 0.92-79025.9µg/L and 0.03-3439µg/L respectively. It was observed that the concentration of erythromycin was very less inspite of being used as a wide spectrum antibiotic against gram positive/gram-negative bacteria causing upper and lower respiratory diseases. An apparent reason could be that it is mainly metabolised by human liver and only 5% is excreted in active form. Also, low concentration of sulfamethoxazole and enrofloxacin were detected in the ranges 0.04-0.92µg/L and 0.03-0.94µg/L respectively in the raw/treated sewage. Notably, even these concentrations could also inhibit bacterial growth by altering microbial production of folic acid and induce antimicrobial resistance at sub lethal concentration. The removal efficiency for UASB-ASP for selected antibiotic was between 51.09% to 95.87% indicating an efficient reduction. Low concentration of sulfamethoxazole and enrofloxacin was observed within the range of 0.15 – 0.21 g/L and 0.007 – 0.01 µg/L in the raw/treated sewage of ASP. Negative removal (increased concentration in the treated sewage) was observed for erythromycin and ciprofloxacin, apparently because of resistance to degradation. The reduction of sulfamethoxazole, enrofloxacin, tetracycline was 27%, 52%, 65% where trimethoprim demonstrated maximum removal of 88% in ASP.  The hybrid UASB-ASP performed better than the standalone ASP with respect to reduction of all antibiotics, indicating that ASP can perform more efficiently when integrated with other technologies alongwith addition of a proper dosing of chlorination. Risk associated with the selected antibiotics from sewage treatment plant to the receiving environment (both water/soil) was quantified employing hazard quotient (HQ) using predicted no effect concentration (PNEC) values derived from literature. HQ for sulfamethoxazole was calculated to be above 1, and higher values were observed for trimethoprim (in the range of 589-628), and tetracycline (in the range of 405-722) indicating potential environmental concern for aquatic environment/soil, whichever may be of concern. No risk seemed to appear for indirect human exposure to enrofloxacin as indicated by the calculated values of HQ (0.004-0.02).

 

How to cite: Hazra, M., Joshi, H. J., and Vellanki, B. P.: Efficiency of activated sludge process for reduction of antibiotics from municipal wastewater , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14782, https://doi.org/10.5194/egusphere-egu23-14782, 2023.

EGU23-16939 | Orals | HS8.1.1 | Highlight

Transport and Removal of Stormwater Vehicle-Related Contaminants in Laboratory Columns 

María Alejandra Cruz Bolaños, Jiaqui Xu, Jan Willem Foppen, and Marc Teixidó Planes

Stormwater runoff capture can provide means of flood control and augmentation of local water supplies. However, urban stormwater is considered a major transport vector of contaminants, primarily from vehicle-related sources. Unfortunately, conventional green infrastructures fail to consistently remove the contaminant dissolved fraction – in particular persistent, mobile, and toxic (PMT) organic pollutants. We investigated the transport and removal of stormwater vehicle-related trace organic contaminants, such as 1H-benzotriazole, N'N-diphenylguanidine, and hexamethoxymethylmelamine utilizing continuous-flow sand columns amended with granulated activated carbon (GAC) and wheat-straw produced biochar (WSP550). All the pollutants were subjected to nonequilibrium interactions in sand-only (control) and GAC/biochar-amended sand columns, with kinetic effects on transport. The Langmuir sorption kinetics model could well describe the observed breakthrough curves, which assumes the saturation of sorption sites that might occur in infiltration systems with DOM fouling. Furthermore, we found that GAC amendments can attenuate the contaminants significantly better with faster adsorption kinetics and higher sorption capacity than the biochar. Based on the optimized sorption parameters, we concluded that HMMM had the lowest affinity in both carbonaceous adsorbents. These column results corroborated observations from preliminary batch experiments. Based on the case study simulation, the amendments of pyrogenic carbonaceous adsorbents could improve vehicle-related organic contaminant removal and exhibit a service life of more than a decade in a green infrastructure. Overall, our research contributes to improving polar organic pollutant removal technologies in environmental applications.

How to cite: Cruz Bolaños, M. A., Xu, J., Foppen, J. W., and Teixidó Planes, M.: Transport and Removal of Stormwater Vehicle-Related Contaminants in Laboratory Columns, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16939, https://doi.org/10.5194/egusphere-egu23-16939, 2023.

EGU23-16985 | ECS | Posters virtual | HS8.1.1 | Highlight

Predicting bacterial transport through saturated porous media using an automated machine learning model 

Fengxian Chen, Bin Zhou, Liqiong Yang, Xijuan Chen, and Jie Zhuang

Escherichia coli, as an indicator of fecal contamination, can move from manure-amended soil to groundwater under rainfall or irrigation events. Predicting its vertical transport in the subsurface is essential for the development of engineering solutions to reduce the risk of microbiological contamination. In this study, we collected 302 datasets from 39 published papers addressing E. coli transport through saturated porous media and trained an automated machine learning model (H2O AutoML) to predict bacterial transport. Bacterial concentration, porous medium type, particle size, ionic strength, pore water velocity, and column length were used as input variables while the first-order attachment coefficient and spatial removal rate were set as target variables. The six input variables have low correlations with the target variables, namely, they cannot predict target variables independently. However, with the automated machine learning model, input variables can effectively predict the target variables. Among 20 candidate models, Gradient Boosting Machine showed the best performance. Among the six input variables, pore water velocity, ionic strength, particle size, and column length were more important than bacterial concentration and porous medium type. This method of using historical literature data to train automated machine learning models provides a new avenue for predicting the transport of other contaminants in the environment.

How to cite: Chen, F., Zhou, B., Yang, L., Chen, X., and Zhuang, J.: Predicting bacterial transport through saturated porous media using an automated machine learning model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16985, https://doi.org/10.5194/egusphere-egu23-16985, 2023.

Previous studies with coarse-resolution global climate models (GCMs) have widely shown that extensive deforestation in the Amazon leads to a reduction in precipitation, with a potential irremediable loss of the rainforest past a critical threshold. However, precipitation in the Amazon region is of convective nature and thus has to be parameterized in coarse-resolution GCMs, limiting confidence in the results of such studies. To bypass this limitation, this study aims to investigate the impact of Amazon deforestation on precipitation in global climate simulations that can explicitly represent convection. The simulations are conducted with the ICON-Sapphire atmosphere-only model configuration run with a grid spacing of 5 km for two years. To understand the impacts of Amazon deforestation, we compare the results of a complete deforestation simulation with a control simulation. Results show no significant change in precipitation during the wet season and a slight decrease of precipitation during the dry season in the deforested simulation. Precipitation decreases due to decreased evapotranspiration are compensated by enhanced moisture convergence.

How to cite: Yoon, A.: The impact of Amazon deforestation on rain system using a storm-resolving global climate model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1304, https://doi.org/10.5194/egusphere-egu23-1304, 2023.

The current crisis state of the planet, commonly called the Anthropocene, emerged as the result of the Great Acceleration in human consumption and environmental impact which followed the Second World War in the middle of the 20th c. There is growing evidence suggesting that similar acceleration dynamics, characterised by exponential growth in human environmental impact, occurred locally or regionally at earlier stages in human history. It is, however, difficult to identify, quantify, and confirm such cases without high-resolution, well-dated historical or paleoenvironmental data. In this presentation, I review three cases of well-documented Anthropocene-like accelerations, from Roman Anatolia, medieval Poland, and early modern Greece. In all of these cases, it was political consolidation, even if short-lived, as well as economic integration, that created the social tipping point triggering exponential acceleration of human environmental impact. All of these acceleration phases also collapsed once the underlying social dynamics was no longer present.

How to cite: Izdebski, A.: Social tipping points of Anthropocene acceleration dynamics in European history, from Roman times to the Little Ice Age, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3151, https://doi.org/10.5194/egusphere-egu23-3151, 2023.

Many aspects of anthropogenic global change, such as land cover change, biodiversity loss, and the intensification of agricultural production, threaten the natural biosphere. Implications of these specific aspects of environmental conditions are not immediately obvious, so it is hard to obtain a bigger picture of what these changes imply and distinguish beneficial from detrimental human impacts.  Here I describe a holistic approach that provides a bigger picture and use it to understand how the terrestrial biosphere can be sustained in the presence of increased human activities.  This approach focuses on the free energy generated by photosynthesis, the energy needed to sustain both the dissipative metabolic activity of ecosystems and human activities, with the generation rate being set by the physical constraints of the environment.  One can then distinguish two kinds of human impacts on the biosphere: detrimental effects caused by enhanced human consumption of this free energy, and empowering effects that allow for more photosynthetic activity and, therefore, more dissipative activity of the biosphere.  I use examples from the terrestrial biosphere to illustrate this view and global datasets to show how this can be estimated.  I then discuss how certain aspects of modern technology can enhance the free energy generation of the terrestrial biosphere, which can then safeguard its sustenance even as human activity increasingly shapes the functioning of the Earth system.

Note: Presentation is based on this manuscript (https://arxiv.org/abs/2210.09164), accepted for publication in the INSEE journal.

How to cite: Kleidon, A.: How to sustain the terrestrial biosphere in the Anthropocene? A thermodynamic Earth system perspective, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3251, https://doi.org/10.5194/egusphere-egu23-3251, 2023.

EGU23-3443 | Orals | CL3.2.6 | Highlight

Regional Climate Expected to Continue to Change Significantly After Net-Zero CO2 Emissions Reached 

Andrew H. MacDougall, Josie Mallett, David Hohn, and Nadine Mengis

The Zero Emissions Commitment (ZEC) is the expected temperature change following the cessation of anthropogenic emissions of climate altering gases and aerosols. Recent model intercomparison work has suggested that global average ZEC for CO2 is close to zero. However there has thus far been no effort to explore how temperature is expected to change at spatial scales smaller than the global average. Here we analyze the output of nine full complexity Earth System Models which carried out standardized ZEC experiments to quantify the ZEC from CO2. The models suggest that substantial temperature change following cessation of emissions of CO2 can be expected at large and regional spatial scales. Large scale patterns of change closely follow long established patterns seen during modern climate change, while at the regional scale patterns of change are far more complex and show little consistency between different models. Analysis of model output suggest that for most models these changes far exceed pre-industrial internal variability, suggesting either higher climate variability, continuing changes to climate dynamics or both. Thus it appears likely that at the regional scale, where climate change is directly experienced, climate disruption will not end even as global temperature stabilizes. Such indefinite continued climate changes will test the resilience of local ecosystem and human societies long after economic decarbonization is complete. Overall substantial regional changes in climate are expected following cessation of CO2 emissions but the pattern, magnitude and sign of these changes remains highly uncertain.

How to cite: MacDougall, A. H., Mallett, J., Hohn, D., and Mengis, N.: Regional Climate Expected to Continue to Change Significantly After Net-Zero CO2 Emissions Reached, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3443, https://doi.org/10.5194/egusphere-egu23-3443, 2023.

EGU23-5233 | Posters on site | CL3.2.6

Association for Trans-Eurasia Exchange and Silk-Road Civilization Development 

Likun Ai, Juzhi Hou, Haichao Xie, Yanbo Yu, and Fahu Chen

Spanning more than 6,400 kilometers across Eurasia, the Silk Road played a key role in facilitating exchanges in economy, culture, politics, and religions between East and West. The ancient Silk Road was one of the most important passages for trans-Eurasia exchange and human migrations, which could be traced back to 5000-4000 years before present. To deepen understanding of the effects of environmental changes in shaping the long-term trans-Eurasia exchanges and Silk Road civilization, the Trans-Eurasia Exchange and Silk-Road Civilization Development (ATES) was launched by a group of scientists with background of climate, hydrology, environment, archaeology in 2019. There are about 118 scientists from 10 countries that with different background have joined the ATES so far. ATES now has a President, and three coordinators in the secretariat, and all the alliance members are allocated to the 5 Working Groups (WG) based on their background and research interests. The main scientific issues for the ATES are: 1) Routes and driving forces of ancient human migrations across Eurasia in the Paleolithic; 2) Relationship between the food globalization, development of agro-pastoralism in Eurasia and human migration in the Neolithic; 3) Mechanisms of establishment, shift and demise of routes and key towns along the ancient Silk Road; 4) Effects of environmental changes on the rise and fall of the Silk Road civilization as to the trans-Eurasia exchanges in terms of economy, technology and culture. What does it tell us about the future of ongoing climate change? ATES aims to set an international platform to exchange multi-discipline knowledge and the latest research achievement on the ancient Silk Road, including exchanges of culture, science, and technology along the roads, perceptions of climate change, and socio-economic development in different historical periods along the Silk Road, and effects of environmental changes on the rise and fall of the Silk Road civilization.

ATES welcomes institutes and scientists worldwide to initiate and launch relevant research programs and projects with the ATES community. By establishing several joint research and education centers with partners, ATES facilitates and supports field observations, research, and capacity building. Training of Young Scientists is one of the main tasks for ATES capacity building, which includes the training workshops and field learnings organized by ATES and its partners. In order to strengthen the interaction of the ATES community, and to enhance the exchange of new achievements and insights of the interdisciplinary study on the evolution of trans-Eurasia exchanges and Silk Road civilization, the ATES Silk Road Civilization Forum invites a world-renowned scientist to give a special lecture on the focused topic every 3 months. ATES will organize parallel sessions and side meetings in the big events such as AGU, EGU, Conference of the Parties of the UNFCCC, UNCBD, ANSO conference, et al. ATES partners and other institutes are welcome to join in organizing the above meetings.

How to cite: Ai, L., Hou, J., Xie, H., Yu, Y., and Chen, F.: Association for Trans-Eurasia Exchange and Silk-Road Civilization Development, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5233, https://doi.org/10.5194/egusphere-egu23-5233, 2023.

EGU23-5722 | ECS | Orals | CL3.2.6 | Highlight

Recurrent droughts increase risk of cascading tipping events by outpacing adaptive capacities in the Amazon rainforest 

Nico Wunderling, Arie Staal, Frederik Wolf, Boris Sakschewski, Marina Hirota, Obbe A. Tuinenburg, Jonathan F. Donges, Henrique M.J. Barbosa, and Ricarda Winkelmann

Since the foundational paper by Lenton et al. (2008, PNAS), tipping elements in the climate system have attracted great attention within the scientific community and beyond. One of the most important tipping elements is the Amazon rainforest. Under ongoing global warming, it is suspected that extreme droughts such as those in 2005 and 2010 occur significantly more often, up to nine out of ten years from the mid to late 21st century onwards (e.g. Cox et al., 2008, Nature; Cook et al., 2020, Earth’s Future).

In this work, we quantify how climates ranging from normal rainfall conditions to extreme droughts may generate cascading tipping events through the coupled forest-climate system. For that purpose, we make use of methods from nonlinear dynamical systems theory and complex networks to create a conceptual model of the Amazon rainforest, which is dependent on itself through atmospheric moisture recycling.

We reveal that, even when the rainforest is adapted to past local conditions of rainfall and evaporation, parts of the rainforest may still tip when droughts intensify. We uncover that forest-induced moisture recycling exacerbates tipping events by causing tipping cascades that make up to one-third (mean+-s.d. = 35.9+-4.9%) of all tipping events. Our results imply that if the speed of climate change might exceed the adaptation capacity of the forest, knock-on effects through moisture recycling impede further adaptation to climate change.

Further, we use a network analysis method to compare the four main terrestrial moisture recycling hubs: the Amazon Basin, the Congo Rainforest, South Asia and the Indonesian Archipelago. By evaluating so-called network motifs, i.e. local-scale network structures, we quantify the fundamentally different functioning of these regions. Our results indicate that the moisture recycling streams in the Amazon Basin are more vulnerable to disturbances than in the three other main moisture recycling hubs.

How to cite: Wunderling, N., Staal, A., Wolf, F., Sakschewski, B., Hirota, M., Tuinenburg, O. A., Donges, J. F., Barbosa, H. M. J., and Winkelmann, R.: Recurrent droughts increase risk of cascading tipping events by outpacing adaptive capacities in the Amazon rainforest, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5722, https://doi.org/10.5194/egusphere-egu23-5722, 2023.

EGU23-7871 | Posters on site | CL3.2.6 | Highlight

Is the current methane growth event comparable to a glacial/interglacial Termination event? 

Euan Nisbet, Martin Manning, David Lowry, Rebecca Fisher, and James France

Atmospheric methane shows very sharp growth since 2006. Growing evidence for methane's main sink, atmospheric OH, being relatively stable implies a major increase in methane emissions is occurring. Methane's synchronous isotopic shift to more negative d13C(CH4) values means the increase is primarily driven by rapid growth in emissions from biogenic sources, such as natural wetlands and agriculture. Recent acceleration in the increase is also strong evidence that it is too large to be caused primarily by anthropogenic sources. Instead, much of the growth may come from large-scale climate-change feedbacks affecting the productivity and balance between methanogenic and methanotrophic processes in tropical and boreal wetlands. Emissions from tropical wetlands in particular may be larger and more influenced by climate shifts than hitherto realised. If so, even despite the Global Methane Pledge, achieving the goals of the UN Paris Agreement may be much harder than previously anticipated.

Modelling indicates that, for scale and speed, the biogenic feedback component of methane's growth and isotopic shift in the 16 years from 2006-2022 is comparable to (or greater than) phases of abrupt growth and isotopic shift during glacial/interglacial terminations, from Termination V (about 430 ka BP) to Termination I that initiated the Holocene. These were rapid global-scale climate shifts when the Earth system reorganised from cold glacial to warmer interglacial conditions.  Methane's recent 2006-2022 growth in biogenic sources may be within Holocene variability, but it is also a possibility that methane may be providing the first indication that a very large-scale end-of-Holocene reorganisation of the climate system is already under way: Termination Zero.

How to cite: Nisbet, E., Manning, M., Lowry, D., Fisher, R., and France, J.: Is the current methane growth event comparable to a glacial/interglacial Termination event?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7871, https://doi.org/10.5194/egusphere-egu23-7871, 2023.

EGU23-9387 | ECS | Posters on site | CL3.2.6

Robustness of critical slowing down indicators to power-law extremes in an Amazon rainforest model 

Vitus Benson, Jonathan F. Donges, Jürgen Vollmer, and Nico Wunderling

Critical slowing down has recently been detected as an indicator of reduced resilience in remotely sensed data of the Amazon rainforest [1]. Tropical rainforests are frequently hit by disturbances such as fire, windthrow, deforestation or drought, which are known to follow a heavy-tailed amplitude distribution. Early warning signals based on critical slowing down are theoretically grounded for systems under the influence of weak, Gaussian noise. Hence, it is not imminent that they are applicable also for systems like the Amazon rainforest, which are influenced by heavy-tailed noise. Here, we extended a conceptual model of the Amazon rainforest [2] to study the robustness of critical slowing down indicators to power-law extremes. These indicators are expected to increase before a critical transition. 

We find the way by which such an increase is detected is decisive for the recall of the early warning indicator (i.e. the proportion of critical transitions detected by the indicator). If a linear slope is taken, the recall of the early warning signal is reduced under power-law extremes. Instead, the Kendall-Tau rank correlation coefficient should be used because the recall remains high in this case. Other approaches to increase robustness, like a high-pass filter or the interquartile range, are less effective. In [1], reduced resilience of the Amazon rainforest was determined through an increase in the lag-1 autocorrelation measured by the Kendall-tau rank correlation. Hence, if there was a resilience loss, they can correctly detect it even in the presence of relatively strong power-law disturbances. However, we also quantify the false positive rate, that is, how often a resilience loss is measured if the model represents a stable rainforest. At a significance level of 5% (1%, 10%) for the early warning signal detection, the false positive rate is approximately 10% (5%, 15%). For strong heavy-tailed noise, this false positive rate can deteriorate to as high as 25% (15%, 35%). This indicates, that increasing critical slowing down may not always be caused by an approaching critical transition, a false positive detection is possible.

 

[1] Boulton, C.,  Lenton, T.  and Boers, N.: “Pronounced Loss of Amazon Rainforest Resilience since the Early 2000s”. Nature Climate Change 12-3 (2022).

[2] Van Nes, E., Hirota, M., Holmgren, M. and Scheffer, M.: “Tipping Points in Tropical Tree Cover”. Global Change Biology 20-3 (2014).

How to cite: Benson, V., Donges, J. F., Vollmer, J., and Wunderling, N.: Robustness of critical slowing down indicators to power-law extremes in an Amazon rainforest model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9387, https://doi.org/10.5194/egusphere-egu23-9387, 2023.

EGU23-9954 | ECS | Posters on site | CL3.2.6

Climate tipping risks under policy-relevant overshoot temperature pathways 

Tessa Möller, Ernest Annika Högner, Samuel Bien, Carl-Friedrich Schleussner, Johan Rockström, Jonathan F. Donges, and Nico Wunderling

The risk of triggering multiple climate tipping points if global warming levels were to exceed 1.5°C has been heavily discussed in recent literature. Current climate policies are projected to result in 2.7°C warming above pre-industrial levels by the end of this century and will thereby at least temporarily overshoot the Paris Agreement temperature goal.

Here, we assess the risk of triggering climate tipping points under overshoot pathways derived from emission pathways and their uncertainties from the PROVIDE ensemble using PyCascades, a stylised network model of four interacting tipping elements including the Greenland Ice Sheet, the West Antarctic Ice Sheet, the Atlantic Meridional Overturning Circulation, and the Amazon Rainforest.

We show that up until 2300, when overshoots are limited to 2°C, the upper range of the Paris Agreement goal, the median risk of triggering at least one element would be less than 5%, although some critical thresholds may have been crossed temporarily. However, the risk of triggering at least one tipping element increases significantly for scenarios that peak above the Paris Agreement temperature range. For instance, we find a median tipping risk in 2300 of 46% for an emission scenario following current policies. Even if temperatures would stabilize at 1.5°C after having peaked at temperatures projected under current policies, the long-term median tipping risks would approach three-quarters.

To limit tipping risks beyond centennial scales, we find that it is crucial to constrain any temperature overshoot to 2°C of global warming and to stabilize global temperatures at 1.0°C or below in the long-term.

How to cite: Möller, T., Högner, E. A., Bien, S., Schleussner, C.-F., Rockström, J., Donges, J. F., and Wunderling, N.: Climate tipping risks under policy-relevant overshoot temperature pathways, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9954, https://doi.org/10.5194/egusphere-egu23-9954, 2023.

EGU23-10044 | ECS | Orals | CL3.2.6 | Highlight

The Impact of Solar Radiation Modification on Earth System Tipping Points and Threshold Free Feedbacks 

Gideon Futerman and Claudia Wieners

The modification of the climate by Solar Radiation Modification (SRM) could be a potentially important human-Earth System interaction in the Anthropocene, having potentially beneficial and adverse impacts across climatic and human indices. SRM would likely interact with Earth system resilience in many ways, with our paper exploring SRM’s interaction with Earth System tipping point which has been extremely underexplored in the literature thus far.

SRM would likely be able to reduce global mean surface temperature quickly, although its broader climate imprint, especially on precipitation and local climatic conditions, is not the same as reversing greenhouse gas emissions. Its cooling effect suggests that SRM can help stop us from hitting those tipping elements that are most temperature-dependent, while the situation is more complex for tipping elements which strongly depend on other factors such as precipitation or regional climate changes. This more complex picture could have important implications for the role (or lack of) that SRM could and ought to play in improving Earth system resilience in the Anthropocene.

We review the available literature about the influence of SRM on the tipping elements and threshold free-feedbacks identified by McKay et al. (2022), as well as reviewing the impact of SRM on relevant climatic conditions that could contribute to tipping of each element, to give an assessment of the potential beneficial or adverse impact of SRM and identify key uncertainties and knowledge gaps. We will also briefly assess how these impacts may differ with different methods of deployment and with the termination of SRM.

How to cite: Futerman, G. and Wieners, C.: The Impact of Solar Radiation Modification on Earth System Tipping Points and Threshold Free Feedbacks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10044, https://doi.org/10.5194/egusphere-egu23-10044, 2023.

EGU23-10864 | Posters on site | CL3.2.6

Towards the Anthropocene peatlands and forests – old-growth forest loss in Western Poland initiated peat growth and peatland state shifts 

Mariusz Lamentowicz, Sambor Czerwiński, Monika Karpińska-Kołaczek, Piotr Kołaczek, Mariusz Gałka, Piotr Guzowski, and Katarzyna Marcisz

During European states’ development, various past societies utilized natural resources, but their impact was not uniformly spatially and temporally distributed. Considerable changes resulted in landscape fragmentation, especially during the Middle Ages. Changes in state advances that affected the local economy significantly drove the trajectories of ecosystems’ development. The legacy of significant changes from pristine forests to farming is visible in natural archives as novel ecosystems. Here, we present two high‑resolution, densely dated multi‑proxy studies covering the last 1000 years from peatlands in CE Europe. In that case, the economic activity of medieval societies was related to the emerging Polish state and new rulers, the Piasts (in Greater Poland) and the Joannites (the Order of St. John of Jerusalem, Knights Hospitaller). Our research revealed rapid deforestation and subsequent critical land-use transition in the high and late Middle Ages and its consequences on the peatland ecosystem development. The shift from the old-growth forests correlates well with raising the local economy, deforestation and enhanced peat initiation. Along with the emerging landscape openness, the wetlands switched from wet fen with open water to terrestrial habitats. Both sites possess a different timing of the shift, but they also show that the catchment deforestation caused accelerated terrestrialization. Our data show how closely the ecological state of wetlands relates to forest microclimate. We identified a significant impact of economic development and the onset of intensive agriculture processes near the study sites. Our results revealed a surprisingly fast rate at which the feudal economy eliminated pristine nature from the studied area and led to intensive nature exploitation in the Anthropocene. In consequence, its activities led to the creation of novel peatlands types.

How to cite: Lamentowicz, M., Czerwiński, S., Karpińska-Kołaczek, M., Kołaczek, P., Gałka, M., Guzowski, P., and Marcisz, K.: Towards the Anthropocene peatlands and forests – old-growth forest loss in Western Poland initiated peat growth and peatland state shifts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10864, https://doi.org/10.5194/egusphere-egu23-10864, 2023.

EGU23-13587 | ECS | Posters virtual | CL3.2.6

Model hierarchies and bifurcations in QE monsoon models 

Krishna Kumar S and Ashwin K Seshadri

The convective quasi-equilibrium (CQE) framework has been successfully employed in the past to build intermediate complexity models accounting for the interaction of convection and large-scale dynamics (Neelin and Zeng, 1999, JAS). As a consequence, these models find use in the study of monsoon circulations, which also experience abrupt onset among several other intriguing features. While some low-order simplifications of CQE based Quasi-equilibrium tropical circulation model (QTCM) yields insights into the mechanisms of monsoon dynamics, they are restricted in the range of processes accounted for. A hierarchy of models, on the other hand, would serve well to study monsoon dynamics and various influences. While the existence of bifurcations or 'tipping-points' in monsoon dynamics has been studied for certain simple models, a thorough investigation of this possibility across a hierarchy of models is absent. Such a hierarchy of models would provide an understanding of effects of different simplifying assumptions on dominant balances in the momentum and thermodynamic equations and resulting nonlinear dynamics, including the choice of precipitation parameterizations. This study explores a hierarchy of such models of varying complexity, based on the QTCM equations. The potential occurrence of bifurcation phenomena are considered, along with their sensitivity to various parameter changes, in the context of the role of different nonlinearities present in these models. The study builds on recent results interpreting the suppression of bifurcation phenomena in these models, as a result of shifts in equilibrium branches and consequently their physical relevance. The hierarchy of models approach, in this context, reconciles apparent contradictions between bifurcations being observed in the simplest models and the evidence from more complex models as well as observations, while identifying robust phenomena.

How to cite: Kumar S, K. and Seshadri, A. K.: Model hierarchies and bifurcations in QE monsoon models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13587, https://doi.org/10.5194/egusphere-egu23-13587, 2023.

EGU23-13620 | Orals | CL3.2.6

The Western Amazon social-ecological system at risk of tipping: A transdisciplinary modelling approach 

Benjamin Stuch, Rüdiger Schaldach, Regine Schönenberg, Katharina Meurer, Merel Jansen, Claudia Pinzon Cuellar, Shabeh Ul Hasson, Christopher Jung, Ellen Kynast, Jürgen Böhner, and Hermann Jungkunst

The Amazon rainforest is a tipping element of the global climate system due to its high carbon storage potential and its flying rivers providing rain for South America. Studies suggest that land use and land cover change (LUCC) in the Amazon, i.e. deforestation, strongly disturb regional convectional rain pattern, which could lead to an increase of drought frequencies and intensities. Under increasing drought stress, the evergreen tropical rainforest may transform into a seasonal forest or even a savannah ecosystem. Such a transformation would likely activate the Amazon tipping element and may affect global climate change by triggering other critical tipping elements of the global climate system.  

Here we present our transdisciplinary research approach in the Western Amazon rainforest developed in context of the PRODIGY research project. We apply a social-ecological system approach to account for the dynamic interactions and feedbacks between people and nature, which could either stabilize or self-enforce regional tipping cascades. For example, regional land users may suffer declining yield and net primary production from decreasing precipitation. Land users may compensate the drop in production/income e.g. by cultivating more land or seeking for other income sources. As a response, deforestation could increase which may drive a self-enforcing feedback loop that further decrease precipitation.

In a participatory process, together with regional stakeholders we develop land use related explorative scenarios. Preliminary results from the scenario exercise show that future agricultural production increases in all scenarios (crops between 20% and 200% and livestock between 0% and 300%). In the first modelling step, these  changes drive the regionally adjusted spatial land system model LandSHIFT. Simulation results indicate that deforestation increases in all scenarios depending on the production technology and the reflexivity of institutions establishing appropriate management options.

In an integrated modelling step, the calculated LUCC maps serve as input to a regional climate model (WRF), which simulates respective changes in regional temperature and precipitation. Then, temperature and precipitation changes are applied to the biogeochemical model CANDY to simulate the impact (of regional deforestation) on crop yields, Net Primary Production (NPP) and changes in soil C and N cycling. In an iterative process, the yield and NPP responses are fed back to the land-use change model to simulate the required land use adaptations, accordingly. By closing the feedback loop between deforestation, climate, yield and NPP as well as respective land use adaptation, we are able to simulate a cascade of endogenous key process in the regions social ecological system. The integrated modelling results will support the stakeholders in identifying key measures/options/policies that could increase resilience of the regional social-ecological system to prevent crossing destructive regional tipping points.

How to cite: Stuch, B., Schaldach, R., Schönenberg, R., Meurer, K., Jansen, M., Pinzon Cuellar, C., Ul Hasson, S., Jung, C., Kynast, E., Böhner, J., and Jungkunst, H.: The Western Amazon social-ecological system at risk of tipping: A transdisciplinary modelling approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13620, https://doi.org/10.5194/egusphere-egu23-13620, 2023.

Microbial communities in freshwater lake sediments play a crucial role in regulating geochemical cycles and controlling greenhouse gas emissions. Many of them exhibit a highly ordered structure along depth profile. Besides redox effect, sediment stratification could also reflect historical transition. Dam construction dramatically increased in the mid-20th century and is considered one of the most far-reaching anthropogenic modifications of aquatic ecosystems. Here we attempted to identify the effect of historical dam construction on sediment microbial zonation in Lake Chaohu, one of the major freshwater lakes in China. The damming event in AD 1962 was coincidentally labeled by the 137Cs peak. Physiochemical and sequencing analyses (16S amplicon and shotgun metagenomics) jointly showed a sharp transition occurred at the damming-labeled horizon which overlapped with the nitrate-methane transition zone (NMTZ) and controlled the depth of methane sequestration. At the transition zone, we observed significant taxonomic differentiation. Random forest algorithm identified Bathyarchaeota, Spirochaetes, and Patescibacteria as the damming-sensitive phyla, and Dehalococcoidia, Bathyarchaeia, Marine Benthic Group A, Spirochaetia, and Holophagae as the damming-sensitive classes. Phylogenetic null model analysis also revealed a pronounced shift in microbial community assembly process, from a selection-oriented deterministic community assembly down to a more stochastic, dispersal-limited one. These findings delineate a picture in which dam-induced changes to the lake trophic level and sedimentation rate generate great changes in sediment microbial community structure, energy metabolism, and assembly process.

How to cite: Zhou, X. and Ruan, A.: Dam construction as an important anthropogenic modification triggers abrupt shifts in microbial community assembly in freshwater lake sediments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14360, https://doi.org/10.5194/egusphere-egu23-14360, 2023.

EGU23-14772 | Posters on site | CL3.2.6

Sustainable Pathways under Climate Variability 

Kira Rehfeld and the SPACY research group members

External forcings and feedback processes of the Earth system lead to timescale and state-dependent climate variability, causing substantial surface climate fluctuations in the past. Particularly relevant for future livelihoods, changing variability patterns could also modify the occurrence of extreme events. However, spatiotemporal mechanisms of climate variability are poorly understood. Likewise, the societal implications are weakly constrained, particularly variability’s potential to drive sustainable transformation. The SPACY project investigates climate variability from past cold and warm periods to future scenarios. One research focus is how forcing mediates climate fluctuations. Bridging the gap between Earth system models and palaeoclimate proxies, we study vegetation and water isotope changes. A second focus is exploring sustainable pathways under climate variability, addressing potential interactions between artificial carbon dioxide removal and surface climate, among others.

 

In particular, we validate the ability of climate models to represent potential climate variability changes. Here, we focus on isotope-enabled simulations with dynamic vegetation. We find that models exhibit less local temperature and water isotope variability than paleoclimate proxies on decadal and longer timescales. Simulations with natural forcing agree much better with proxy records than unforced ones. The mean local temperature variability decreases with warming. Furthermore, we analyze potentials and limitations of terrestrial hydroclimate proxies. This includes water isotopes in speleothems and ice cores and vegetation indicators derived from pollen assemblages.

Transferring our understanding to the future, we contribute to mitigation and sustainable transitions. Weather and climate extremes determine losses and damages, but their impact on socioeconomic development is poorly examined. We scrutinize damage parametrization of economic models regarding the ability to consider variability. While large-scale sequestration of atmospheric carbon dioxide is paramount to mitigation targets, its representation in climate models is insufficient. Accounting for feedbacks of carbon dioxide removal (CDR) requires model experiments with modified land surfaces. We develop CDR representations of “artificial photosynthesis” in Earth system models. Pollen records benchmark the simulated climate–carbon dioxide–vegetation interactions. This supports modeling endogenous societal land use decisions in the future.

Our work continues to improve the understanding of long-term climate predictability. The combined knowledge from past climate studies and comprehensive modeling for future scenarios underlines the relevance of changing boundary conditions for a future within planetary boundaries.

 

 

How to cite: Rehfeld, K. and the SPACY research group members: Sustainable Pathways under Climate Variability, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14772, https://doi.org/10.5194/egusphere-egu23-14772, 2023.

EGU23-16944 | ECS | Orals | CL3.2.6

Socio-Political Feedback on the Path to Net Zero 

Saverio Perri, Simon Levin, Lars Hedin, Nico Wunderling, and Amilcare Porporato

Anthropogenic emissions of CO2 must soon approach net zero to stabilize the global mean temperature. Although several international agreements have advocated for coordinated climate actions, their implementation has remained below expectations. One of the main challenges of international cooperation is the different degrees of socio-political acceptance of decarbonization.

In this contribution, we interrogate a minimalistic model of the coupled human-natural system representing the impact of such socio-political acceptance on investments in clean energy and the path to net-zero emissions. Despite its simplicity, the model can reproduce complex interactions between human and natural systems, and it can disentangle the effects of climate policies from those of socio-political acceptance on the path to net zero. Although perfect coordination remains unlikely, as clean energy investments are limited by myopic economic strategies and a policy system that promotes free-riding, more realistic decentralized cooperation with partial efforts from each actor could still lead to significant emissions cuts.

Since the socio-political feedback on the path to net zero could influence the trajectories of the Earth System for decades to centuries and beyond, climate models need to incorporate better the dynamical bi-directional interactions between socio-political groups and the environment. Our model represents a first step for incorporating this feedback in describing complex coupled human and natural systems.

How to cite: Perri, S., Levin, S., Hedin, L., Wunderling, N., and Porporato, A.: Socio-Political Feedback on the Path to Net Zero, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16944, https://doi.org/10.5194/egusphere-egu23-16944, 2023.

EGU23-17342 | ECS | Orals | CL3.2.6

Systematic assessment of climate tipping points 

Sina Loriani, Boris Sakschewski, Jonathan Donges, and Ricarda Winkelmann

Tipping elements constitute one high-risk aspect of anthropogenic climate change - after their critical thresholds are passed, self-amplifying feedbacks can drive parts of the Earth system into a different state, potentially abruptly and/or irreversibly. A variety of models of different complexity shows these dynamics in many systems, ranging from vegetation over ocean circulations to ice sheets. This growing body of evidence supports our understanding of  potential climate tipping points, their interactions and impacts.

However, a systematic assessment of Earth system tipping points and their uncertainties in a dedicated model intercomparison project is of yet missing. Here we illustrate the steps towards automatically detecting abrupt shifts and tipping points in model simulations, as well as a standardised evaluation scheme for the Tipping Point Model Intercomparison Project (TIPMIP). To this end, the model outputs of taylored numerical experiments are screened for potential tipping dynamics and spatially clustered in a bottom-up approach. The methodology is guided by the anticipated setup of the intercomparison project, and in turn contributes to the design of the TIPMIP protocol.

How to cite: Loriani, S., Sakschewski, B., Donges, J., and Winkelmann, R.: Systematic assessment of climate tipping points, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17342, https://doi.org/10.5194/egusphere-egu23-17342, 2023.

EGU23-17397 | ECS | Posters virtual | CL3.2.6

Is Arctic Permafrost a Climate Tipping Element? – Potentials for Rapid Permafrost Loss Across Spatial Scales 

Jan Nitzbon, Thomas Schneider von Deimling, Sarah Chadburn, Guido Grosse, Sebastian Laboor, Hanna Lee, Norman Julius Steinert, Simone Maria Stuenzi, Sebastian Westermann, and Moritz Langer

Arctic permafrost is yet the largest non-seasonal component of Earth's cryosphere and has been proposed as a climate tipping element. Already today, permafrost thaw and ground ice loss have detrimental consequences for Arctic communities and are affecting the global climate via carbon-cycle–feedbacks. However, it is an open question whether climatic changes drive permafrost loss in a way that gives rise to a tipping point, crossing of which would imply abrupt acceleration of thaw and disproportional unfolding of its impacts.

Here, we address this question by geospatial analyses and a comprehensive literature review of the mechanisms and feedbacks driving permafrost thaw across spatial scales. We find that neither observation-constrained nor model-based projections of permafrost loss provide evidence for the existence of a global-scale tipping point, and instead suggest a quasi-linear response to global warming. We identify a range of processes that drive rapid permafrost thaw and irreversible ground ice loss on a local scale, but these do not accumulate to a non-linear response beyond regional scales.

We emphasize that it is precisely because of this overall linear response, that there is no „safe space“ for Arctic permafrost where its loss could be acceptable. Every additional amount of global warming will proportionally subject additional land areas underlain by permafrost to thaw, implying further local impacts and carbon emissions.

How to cite: Nitzbon, J., Schneider von Deimling, T., Chadburn, S., Grosse, G., Laboor, S., Lee, H., Steinert, N. J., Stuenzi, S. M., Westermann, S., and Langer, M.: Is Arctic Permafrost a Climate Tipping Element? – Potentials for Rapid Permafrost Loss Across Spatial Scales, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17397, https://doi.org/10.5194/egusphere-egu23-17397, 2023.

EGU23-17457 | ECS | Orals | CL3.2.6 | Highlight

Indicators of changing resilience and potential tipping points in the automotive industry 

Joshua E Buxton, Chris A Boulton, Jean-Francois Mercure, Aileen Lam, and Timothy M Lenton

Through innovation and wider socio-economic processes, large sections of the economy have been known to rapidly (and often irreversibly) transition to alternative states. One such sector currently undergoing a transition is the automotive industry, which is moving from a state dominated by internal combustion engines to one characterised by low-emission vehicles. While much research has focused on early warning signals of climate and ecological tipping points, there is much to be done on assessing the applicability of these methods to social systems. Here we focus on the potential for tipping points to occur in the sale of electrical vehicles in various markets, including Norway and the UK. Early indicators that this new state is being approached are considered through the use of novel data sources such as car sales, infrastructure announcements and online advert engagement. We then map out the socio-technical feedback loops which may drive these tipping points. Consideration is also given to the resilience of the wider automotive industry to previous economic shocks. 

How to cite: Buxton, J. E., Boulton, C. A., Mercure, J.-F., Lam, A., and Lenton, T. M.: Indicators of changing resilience and potential tipping points in the automotive industry, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17457, https://doi.org/10.5194/egusphere-egu23-17457, 2023.

EGU23-1477 | ECS | Orals | SSP1.4

Microplastic Interaction with Soil Water - Visualization and Quantification with Neutron and X-ray Imaging 

Andreas Cramer, Pascal Benard, Kaestner Anders, Mohsen Zarebanadkouki, and Andrea Carminati

Soil is considered the largest sink of microplastics (MP) in terrestrial ecosystems. Among the expected effects of MP as hydrophobic surface addition is the likelihood that MP enhances soil water repellency. So, crucial for MP fate in soils is the interaction between MP and water. If MP is translocated by water flow and, vice versa, MP impacts water flow, to what extent? Water flow on the pore scale will be impacted with feedbacks on transport and retention of MP. However, we don’t know the extent of and conditions under which MP are transported through porous media and, if deposited, how they interplay with soil water dynamics. We hypothesize that: (i) isolated MP are displaced and translocated by air-water interfaces and (ii) local accumulation of MP is facilitated by bypassing water flow. To approach this question, neutron and x-ray imaging of MP and water in soils was utilized.

Dual neutron and x-ray imaging at the beamlines ICON (Paul-Scherrer-Institute) during repeated wetting-drying cycles was applied to trace MP-water interactions in aluminum cylinders filled with sand (0.7-1.2 mm) and MP (PET, 20-75 µm) in gravimetric contents of 0.35, 1.05 and 2.10%. The contents refer to static contact angle estimations of the mixtures resembling < 90°, 90° and > 90°. First, simultaneous neutron and x-ray tomography captured the initial dry MP configuration in samples. Subsequently, neutron radiographies of deuterated water flow through the sample of 1 ml min-1 were recorded for 200s. After drying, repeated tomography gave insights into MP translocation.

Neutron and x-ray imaging results showed that regions of major MP content are water repellent. Water flow bypasses and MP is mainly retained. Resultant air entrapments lead to reduced water contents. In regions of minor MP content water can infiltrate. Here, the air-water interface collects isolated MP and shifts their distribution towards an enhanced accumulation.

Extrapolation of these results to natural soil systems suggests that vertical transport of MP can be limited especially at hotspots of high MP contents. Water bypasses here. This might limit the water dependent degradation processes of MP due to reductions in hydrolysis, coating and colonization by microorganisms even elongating the process of natural attenuation.

How to cite: Cramer, A., Benard, P., Anders, K., Zarebanadkouki, M., and Carminati, A.: Microplastic Interaction with Soil Water - Visualization and Quantification with Neutron and X-ray Imaging, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1477, https://doi.org/10.5194/egusphere-egu23-1477, 2023.

EGU23-2559 | ECS | Posters on site | SSP1.4

Leaching of carbon, metals, and additives from microplastics to water 

Katerina Novotna, Lenka Cermakova, and Martin Pivokonsky

The occurrence of microplastics (MPs) has been evidenced worldwide in various aquatic environments, and while quite many studies have been devoted to the quantification and characterisation of these MPs, the knowledge of potential leaching from MPs to water is yet limited. In the current study, a range of different MPs prepared from consumer plastic products were soaked in water for 12 weeks, and variable composition of the water leachates was continuously analysed. Majority of investigated MPs released substantial amounts of dissolved organic carbon, with the maximum of approximately 65 mg per g of MPs after the 12 weeks, and some MPs also released dissolved inorganic carbon. Additionally, up to 10 other elements were detected in individual leachates – including metals (Al, Ba, Ca, Fe, K, Mg, Mn, Na, Zn) and one metalloid (Si). Out of those, Ca, K, and Na occurred most frequently, while Ca reached the highest values (up to approximately 2.5 mg per g MPs). In general, the overall highest leaching was observed in the case of MPs comprising polyurethane, polyvinyl chloride, and acrylonitrile-butadiene copolymer as the main polymers. Another general observation is that the leaching was usually most rapid during the first few weeks of MP contact with water. Further, in order to provide a better insight into composition and properties of the leachates, non-target analysis was conducted, and dozens of chemical individuals were tentatively identified in the leachates. Considering that the amounts of some elements released from MPs were quite high, and that some of the tentatively identified compounds are considered harmful to human health and/or to the environment, the leaching from MPs to ambient water might be important from different perspectives, including toxicology as well as fluxes of carbon and metals.

How to cite: Novotna, K., Cermakova, L., and Pivokonsky, M.: Leaching of carbon, metals, and additives from microplastics to water, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2559, https://doi.org/10.5194/egusphere-egu23-2559, 2023.

EGU23-2560 | ECS | Posters on site | SSP1.4

Investigating microplastics at two drinking water treatment plants within a river catchment 

Lenka Cermakova, Katerina Novotna, and Martin Pivokonsky

Microplastics (MPs) are emerging globally distributed pollutants of aquatic environments. Nowadays, MPs are being detected in seas, oceans and freshwater bodies worldwide, even in very remote areas. Studies have reported also the occurrence of MPs in potable water. Despite the potential adverse effects on human health are still largely unknown, the presence of MPs in drinking water deserves more attention. Besides the need for elimination of MPs in natural environments, it is necessary to focus also on their fate and removability at drinking water treatment plants (DWTPs) that pose a barrier for MPs to enter water for human consumption. In our study, we decided to provide unique insight into the occurrence of MPs at two different DWTPs situated on the same river but differing in treatment technology. Quantification and characterization of MPs ≥ 1 μm was conducted not only in raw and treated water but also after each technological treatment step. The results showed that the content of MPs varied greatly between the DWTPs. There were 23 ± 2 and 14 ± 1 MPs L−1 in raw and treated water, respectively, at the upstream DWTP. By contrast, 1296 ± 35 and 151 ± 4 MPs L−1 were found in raw and treated water, respectively, at the downstream DWTP. The majority (>70%) of MPs were smaller than 10 μm, and irregular fragment shape prevailed over fibres. Cellulose acetate, polyethylene terephthalate, polyvinyl chloride, polyethylene, and polypropylene were the most frequently occurring materials. Total removal of MPs of 88% was achieved at the DWTP with a higher initial MP number and more complicated treatment technology consisting of coagulation-flocculation-sedimentation, deep-bed filtration through clay-based material, and granular activated carbon adsorption. These steps contributed to MP elimination by 62%, 20%, and 6%, respectively. These results contribute to filling the knowledge gap regarding the removability of different types of MPs by distinct drinking water treatment technologies operating under ordinary conditions.

How to cite: Cermakova, L., Novotna, K., and Pivokonsky, M.: Investigating microplastics at two drinking water treatment plants within a river catchment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2560, https://doi.org/10.5194/egusphere-egu23-2560, 2023.

EGU23-2670 | ECS | Posters on site | SSP1.4

Soil susceptibility to wind erosion drives the abundance of microplastics in remote Scottish soils 

Tereza Pavlíková, David Pavlík, Jan Divíšek, and Daniel Nývlt

Microplastics have been found in various places, including not only densely populated areas of China or Germany but also remote high-altitude places like the Himalayas or the Pyrenees. However, the remoteness of a place is not determined only by its altitude. The Outer Hebrides (Scotland), with a low population and minimum industry, are remote in terms of direct pollution. This study aims to analyse the occurrence and spatial distribution of microplastics in soils of the Outer Hebrides to discover the factors driving the abundance of microplastics and to find how much more or less are remote Scottish soils polluted with microplastics than inland soils of populated areas.

In the Isle of South Uist, 123 topsoil samples were collected along the western coastline and in four transects through the isle in the west-east direction. In total, 63 samples were analysed using an optical microscope to quantify the plastic microfibres visually using a semi-automatic algorithm. The amounts of microfibres were statistically processed, and their distribution was modelled for the entire archipelago.

More microplastics are present in inland soils with loamy soil texture, denser vegetation and denser roots (median = 36,900 microfibres/L) than in coastal soils with sandy soil texture, sparse vegetation and low root density (median = 3,580 microfibres/L). Their abundance is mainly influenced by soil texture, vegetation density, and root density.

With the south-western prevailing wind direction, we assume that most microfibres enter the island from the Atlantic Ocean, and the wind transports the microfibres inland to the east. Wind deflates the microfibres from coastal soils, and microfibres are deposited in inland soils. The inland soils are less susceptible to wind erosion, and the microfibres accumulate there.

Thus, the remoteness of the Outer Hebrides does not guarantee low microplastic pollution. Contrarily, the Hebridean soils are extensively more polluted than most so far studied sites. The level of pollution is comparable to only a few studies where the abundance of microplastics in the soils is similar, e.g. Beijing (China), Lower Rhine basin (Germany) or Coimbra (Portugal). However, these sites are much more populated and interconnected, which suggests a great contribution of microplastic pollution from Atlantic Ocean and a great magnitude of wind transport processes in the Outer Hebrides.

How to cite: Pavlíková, T., Pavlík, D., Divíšek, J., and Nývlt, D.: Soil susceptibility to wind erosion drives the abundance of microplastics in remote Scottish soils, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2670, https://doi.org/10.5194/egusphere-egu23-2670, 2023.

EGU23-2997 | Posters on site | SSP1.4

The circularity of marine microplastics under the influence of climate change 

Chihhao Fan and You-Yi Lee

Since plastics were first made in the early 20 century, global plastic production has increased dramatically and annual plastic use reached 460 million metric tons (Mt) in 2019. Although the advent of plastics creates miraculous economic achievements, it brings about severe pollution at the same time. As the life cycle of plastic use worldwide is still in linear form, mismanaged plastic waste might break into microplastics and accumulate in the environment. Rivers are the main route by which plastics enter the ocean. The process may take years or decades for microplastics to reach the ocean. The ocean surface currents were responsible for the transport of plastic waste and the ocean is its ultimate destination. This study correlated the fate of marine microplastics with economic growth under the influence of climate change. Taking 1960 as a benchmark, the trend of world GDP growth coincided with the growth of annual plastic production, indicating that economic growth heavily relies on plastic-related industries. Plastics emit a high amount of greenhouse gas (GHG) through their life span, enhancing the negative impact of climate change, causing the faster weathering process to form microplastics, and further enabling the leakage into the aquatic environment. According to the OECD statistics, 1.7 Mt of plastics entered the ocean system in 2019, reaching the total accumulation of 30 Mt of plastic waste since 1970. Global warming over past decades enhances the Earth's ocean currents which induced the acceleration of ocean plastic distribution. The accelerated ocean transportation may increase plastic accumulation at the garbage patches within five gyres and the Arctic Ocean which are ultimate sinks for plastic waste in the ocean. The abundance of microplastics in the ocean interferes with the carbon fixation capacity of the ocean, forming a nexus implication between climate change, ocean currents, and marine plastic redistribution. The accumulation of marine microplastic is suggested to be a factor in aggravating the impact of climate change. To deal with the dilemma, economic growth should be decoupled with the massive use of plastic utilization to reduce plastic production and GHG emission. Moreover, higher plastic waste recycling is urgently needed to prevent extra microplastics from entering the ocean.

How to cite: Fan, C. and Lee, Y.-Y.: The circularity of marine microplastics under the influence of climate change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2997, https://doi.org/10.5194/egusphere-egu23-2997, 2023.

EGU23-4405 | Orals | SSP1.4 | Highlight

The Plastic Underground: Are Microplastics in the Subsurface a Ticking Time Bomb for Soil and Groundwater Ecosystems? 

Stefan Krause, Uwe Schneidewind, Mohammad Wazne, Anna Kukkola, Iseult Lynch, Lee Haverson, Liam Kelleher, Grace Davies, Andre-Marie Dendievel, Brice Mourier, Florian Mermillod-Blondin, Zoraida Quiñones-Rivera, Laurent Simon, Julia Reiss, Dan Perkins, Anne Robertson, and Jesus Gomez-Velez

Increasing volumes of mismanaged plastic waste have resulted in millions of tons of plastics entering the environment. While recent research has made substantial progress in determining the fate and transport of microplastics (MP) in river systems and their subsequent discharge to the worlds oceans, much less is known about the subsurface fate of MP as they enter soils, (riverine) sediments and global groundwater resources. Initial studies have identified MP in selected groundwater samples and there is great interest to understand entry pathyways of MPs into soils, in particular through agricultural pathways. The mechanisms of MP release from agricultural sources such as seed and agrochemical encapsulations or sewage sludges as well as the total quantity, spatial distribution, residence time scales as well as the impact of MP on soils and subsequently groundwater ecosystems are completely unknown. There is hence a critical need to study the role of soils and groundwater systems as a long-term sink for plastic pollution, including the development of legacy risks.

Here we identify the significance of various entry pathways for MP into subsurface ecosystems, integrating experimental and model based quantifications of MP transport through streambed sediments with quantifications of MP inputs into agricultural soils through irrigation with river water. We present first results of MP impacts on the functioning of subsurface ecosystem services, by the particular example of MP exposure impacts on the behaviour of bioturbating invertebrates and the subsequent consequences for sediment biogeochemical cycling in order to draw attention to the potential risks for vital soil and groundwater ecosystem services.

We complement this site specific mechanistic process understanding with global estimates of mismanaged plastic waste accumulation in river basins to quantify MP catchment wide loads available for leakage into soils and present first results of our recently started participatory approach that aims to develop a baseline of MP pollution in aquifers across the world. Such baseline data is imperative to increase our understanding of MP fate and transport processes, MP uptake by groundwater organisms and the interaction of MP with nutrients and potential co-contaminants. Our specifically tailored protocol allows for standardized MP sampling in boreholes, springs or wells across a wide range of geological settings and land cover classes. We invite and encourage the community to contribute to this global effort in order to enable estimates of the magnitude and expected time scales of soil and groundwater MP contamination.

How to cite: Krause, S., Schneidewind, U., Wazne, M., Kukkola, A., Lynch, I., Haverson, L., Kelleher, L., Davies, G., Dendievel, A.-M., Mourier, B., Mermillod-Blondin, F., Quiñones-Rivera, Z., Simon, L., Reiss, J., Perkins, D., Robertson, A., and Gomez-Velez, J.: The Plastic Underground: Are Microplastics in the Subsurface a Ticking Time Bomb for Soil and Groundwater Ecosystems?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4405, https://doi.org/10.5194/egusphere-egu23-4405, 2023.

EGU23-4586 | ECS | Orals | SSP1.4

Spatial distribution and historical trend of microplastic pollution in sediments from enclosed bays of South Korea 

Soeun Eo, Sang Hee Hong, Young Kyoung Song, Youna Cho, Gi Myung Han, and Won Joon Shim

Seafloor sediment is an important sink for microplastics, and vertical profile of microplastic accumulation in a sediment core can provide historical pollution trend. However, microplastic pollution in coastal sediment has not been addressed well, and a few studies have investigated the trends of microplastic pollution in age-dated core sediments. In this study, the microplastics in surface sediments in urban, aquafarm and reference areas of South Korea were analyzed to evaluate the pollution characteristics of microplastic according to different sea area use patterns. In addition, the historical trend of microplastic pollution was investigated in core sediments in the urban and aquafarm areas. The abundance of microplastics in surface sediment were in order of urban area (6,887 ± 6,100 particles/kg d.w.), aquafarm area (5,121 ± 2,428 particles/kg d.w.), and reference area (2,474 ± 522 particles/kg d.w.). Polymer types were diverse in the urban area, and expanded polystyrene used for buoys was dominant in the aquafarm area. Fragment type microplastic was dominant in all three areas, and the proportion of fiber was higher in urban and aquafarm areas than in reference area. The polymer composition of fiber was different in urban (polyester 51% and polypropylene (PP) 29%) and aquafarm areas (PP 84% and polyamide 13%). These results support that the characteristics of microplastic pollution well reflect the sea area use patterns. Historical trend of microplastic pollution has increased since the 1980s and the increasing rate steeply increased around the early and mid-2000s in both the core samples. Their increasing trend reflected the influence of population or surrounding input sources (i.e. effluent discharge amount of a wastewater treatment plant). The clear increasing trend of historical microplastic pollution up to now indicates that more efforts is highly required to reduce the microplastic pollution. 

How to cite: Eo, S., Hong, S. H., Song, Y. K., Cho, Y., Han, G. M., and Shim, W. J.: Spatial distribution and historical trend of microplastic pollution in sediments from enclosed bays of South Korea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4586, https://doi.org/10.5194/egusphere-egu23-4586, 2023.

EGU23-5676 | ECS | Orals | SSP1.4

Microplastic distribution characteristics and storage in a multi-species saltmarsh 

Yan Zhang, Yanting Wang, Xiaogang Chen, Peiyuan Zhu, Siyuan Jing, and Ling Li

Plastic has greatly changed modern society, and it has become an indispensable material in our daily lives. Microplastics are now regarded as the serious environmental threats due to the management limitations. Saltmarshes are one of the most productive ecosystems on earth and a high-efficiency blue carbon sink. As an emerging contaminant, the load, transport and fate of microplastics are largely neglected in saltmarshes. Here, we firstly measured the mass concentration of microplastics in the sediment cores of a multi-species saltmarsh by pressurized liquid extraction and modified double-shot pyrolysis gas chromatography-mass spectrometry. The major microplastics in saltmarsh sediments were polyethylene (PE), polyvinyl chloride (PVC), and polypropylene (PP). The microplastic mass concentration in the sediment of Scirpus mariqueter was greater than Phragmites australis and mudflat. As artificial carbon, carbon content of microplastics accounts for 1.15% of total organic carbon. Overall, the results suggest that saltmarsh vegetation can efficiently drive the microplastic settling and retention. Therefore, the microplastic distribution characteristics in saltmarsh can be effected by the vegetation types and their distribution pattern.

How to cite: Zhang, Y., Wang, Y., Chen, X., Zhu, P., Jing, S., and Li, L.: Microplastic distribution characteristics and storage in a multi-species saltmarsh, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5676, https://doi.org/10.5194/egusphere-egu23-5676, 2023.

EGU23-6323 | ECS | Posters on site | SSP1.4

The impacts of climate change on eroding coastal historic landfills 

Shudan Xue, Kate Spencer, and Stuart Grieve

Impacts of climate change – sea level rise, more frequent storms and coastal flooding will exacerbate coastal erosion, resulting in the erosion of coastal historic landfills. These historic landfills are particularly vulnerable to such erosion as they typically have no lining or leachate management, limited information of the proportion and/or types of waste mixtures they contain and inaccurate records of their location and waste volumes. There are over 1200 coastal historic landfills in England alone, and over 10,000 such sites are at risk of release both solid waste and soluble contaminants across Europe. The contaminated matrix and solid wastes make landfills a major sink and source of microplastics and heavy metal, posing a threat to the coastal and marine environment.

We investigated heavy metal and microplastic pollution on the beach and foreshore in three coastal historic eroding landfills, East Tilbury (n = 32 samples), Lynemouth (n = 33 samples), Northam Burrows Tilbury (n = 33 samples), UK. Samples were collected every 50 meters along the shoreline, with 100g of surface soil from the landfill edge, and 1kg of beach and intertidal sediment collected from each transect. The metal concertation was measured with handheld X-ray Fluorescence (XRF). Microplastics were density separated with a zinc chloride solution (1.5 g cm−3), after the samples were dried and digested with hydrogen peroxide. The extracted microplastics were recorded under stereomicroscope at 50× magnification with a digital camera, and characterized with Fourier-transformed infrared (ATR-FTIR) spectroscopy.

This study is one of the first few to investigate the impacts of eroding historic landfill. Our preliminary findings suggest that eroding landfill are releasing significant amounts of microplastics and heavy metal pollution. These findings will be crucial to assess the impacts of eroding landfills, identify solutions and raise public attention to this environmental problem.

How to cite: Xue, S., Spencer, K., and Grieve, S.: The impacts of climate change on eroding coastal historic landfills, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6323, https://doi.org/10.5194/egusphere-egu23-6323, 2023.

EGU23-9164 | ECS | Orals | SSP1.4 | Highlight

River plastic during floods: Amplified mobilization, limited river-scale dispersion 

Tim van Emmerik, Roy Frings, Louise Schreyers, Rahel Hauk, Sjoukje de Lange, and Yvette Mellink

Plastic mobilization, transport, and retention dynamics are influenced by hydrological processes and river catchment features (e.g. land-use, vegetation, and river morphology). Increased river discharge has been associated with higher plastic transport rates, although the exact relation between the two can vary over time and space. The precise role of an extreme discharge event on plastic transport is however still unknown. Here, we show that fluvial floods drive floating macroplastic transport and accumulation in river systems. We collected observational evidence during the (return period of 200 years) along the Dutch part of the Meuse. Upstream plastic transport multiplied by a factor of over 100 compared to non-flood conditions (3.3x105 vs 2.3x102), making the Meuse . Over one-third of the annual plastic transport was estimated to occur within the six-day period of extreme discharge (>3,200 m3/s). Towards the river mouth, plastic transport during the flood decreased by 90%, suggesting that the Plastic transport and accumulation on the riverbanks decreased significantly along the river, corroborating the river's function as a plastic reservoir, rather than conduit for plastic towards the ocean. We demonstrate the crucial role of floods as drivers of plastic transport and accumulation in river systems. Floods amplify the mobilization of plastics, but the effects are local and the river-scale dispersion is limited. We anticipate that our findings serve as a starting point for improving global estimates of river plastic transport, retention, and export into the sea. Moreover, our results provide essential insights for future large-scale and long-term quantitative assessments of river plastic pollution. Reliable observations and a fundamental understanding of plastic transport are key to designing effective prevention and reduction strategies.

 

Link to preprint

Tim van Emmerik, Roy Frings, Louise Schreyers et al. River plastic during floods: Amplified mobilization, limited river-scale dispersion, 08 August 2022, PREPRINT (Version 1) available at Research Square [https://doi.org/10.21203/rs.3.rs-1909246/v1]

How to cite: van Emmerik, T., Frings, R., Schreyers, L., Hauk, R., de Lange, S., and Mellink, Y.: River plastic during floods: Amplified mobilization, limited river-scale dispersion, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9164, https://doi.org/10.5194/egusphere-egu23-9164, 2023.

EGU23-10534 | ECS | Orals | SSP1.4

Greenland in the Anthropocene: an archive of microplastic pollution 

Karla B Parga Martinez, Thorbjørn J Andersen, Vitor da Silva, Jakob Strand, and Nicole R Posth

Glacimarine sediment results from glaciers weathering the rock exporting silt and clay into the ocean. Such fine sediments are also exported from the Greenlandic Ice Sheet where new sources of plastic pollution like seasonal ice thawing may be releasing microplastics (MP) back to the environment. MP could be then transported to the seafloor via sediment burial and incorporated into the layers of the geological record. However, the purification and extraction of MP from such a fine-grain matrix is challenging, as the small grains remain in suspension and can form aggregates. In order to look for a footprint of the Anthropocene in Greenland, a sediment core was analyzed to generate a record of MP by comparing a pre- and post-plastic boom period. Using 210Pb and 137Cs dating, the chronology was established from 1861 to 2015 ±5 yrs bridging the plastic boom of the 1950s. Using a 4-step methodology developed for fine-grain matrices, MP particles were characterized via FT-IR imaging. QC/QA protocols were applied throughout the process to reduce the risk of contamination. More than 1000 particles were found in total ranging from 20 µm to 600 µm and going as far back as 1930. Nine polymer types were found, the most common being PE and PP accounting for 84% of all particles. This is the first sediment record of MP pollution in the Arctic, which shows that once thought pristine regions have in fact being polluted for a long time, which in turn implies that the impact might be greater than previously thought. In addition, this long-term accumulation in Greenlandic marine sediment could be compared to global horizons in the search for markers of the Anthropocene.

How to cite: Parga Martinez, K. B., Andersen, T. J., da Silva, V., Strand, J., and Posth, N. R.: Greenland in the Anthropocene: an archive of microplastic pollution, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10534, https://doi.org/10.5194/egusphere-egu23-10534, 2023.

EGU23-11173 | Posters on site | SSP1.4

Comparison Studies for Surface Water Visual Survey and Surface and Water-Column Trawl for Floating and Suspended Marine Plastic Debris 

Won Joon Shim, Yu Lee Jang, Soeun Eo, Jongwook Jeong, Song Yong Ha, Gi Myung Han, and Sang Hee Hong

A visual survey using a vessel is a representative method to assess the degree of pollution of floating plastic debris in marine environments. However, the visual survey may more easily miss plastic items on and just below water (e.g. plastic bags) than above water (e.g. PET bottles). In addition, there are very limited comparison studies for floating plastic debris on the water surface and suspended plastic debris in the water column. None of the studies quantitatively determined the difference in detection rate by visual and surface trawl surveys. The aim of this study is to evaluate what could be relatively missed and underestimated by surface water visual surveys.

Floating plastic debris was monitored by visual and trawl surveys (depth of 0.5 m) in three coastal areas (rural area, GJ; aquafarm area, JH; urban and near river mouth area, SY) of Korea over the four seasons in 2022. In addition, during the visual survey of floating plastic debris in a fishing area (GH), near the river mouth of Han River, a shrimp beam trawl was used to collect plastic debris in the water column (water depth of 10 m) except for thin surface and bottom layer over three seasons in 2022. The seasonal patterns and composition of floating plastic debris in the surface water of JH, GJ, and SY were similar between the visual and trawl surveys. But, the mean densities of most plastics obtained from trawl surveys were 3 to 7 times higher than those from visual surveys. In particular, it was hard to detect small-sized, submerged, or dark-colored fishing gear with the visual survey. Patches with small items can increase the uncertainty of the visual survey. Therefore, visual surveys may underestimate the amount of marine plastic debris above and just below the water.

Various types of floating plastic debris were observed by visual survey in the surface water of GH: plastic bags/sheets (54%), expanded polystyrene pieces (18%), plastic containers (4%), strapping (3%), plastic bottles/caps (3%), discarded fishing gear (1%), and other hard plastic pieces (14%). In the water column of GH, however, plastic bags/sheets (93%) predominated and followed by strapping (4%), discarded fishing gear (1%), and other plastics (1%). These results indicate that plastic bags/sheets and strapping would mainly submerge in the water column, but expanded polystyrene pieces, plastic containers, plastic bottles/caps, and other hard plastic pieces are more likely to float rather than sink. Thus, the application of only visual surveys for plastic pollution monitoring in water may largely miss and underestimate the plastic items transported on and below water such as plastic bags and sheets.

How to cite: Shim, W. J., Jang, Y. L., Eo, S., Jeong, J., Ha, S. Y., Han, G. M., and Hong, S. H.: Comparison Studies for Surface Water Visual Survey and Surface and Water-Column Trawl for Floating and Suspended Marine Plastic Debris, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11173, https://doi.org/10.5194/egusphere-egu23-11173, 2023.

EGU23-12344 | ECS | Posters on site | SSP1.4

The submarine Congo Canyon as a conduit for microplastics to the deep sea 

Florian Pohl, Lars Hildebrandt, Joey O’Dell, Peter Talling, Megan Baker, Fadi El Gareb, Jacopo La Nasa, Francesca De Falco, Marco Mattonai, Sean Ruffell, Joris Eggenhuisen, Francesca Modugno, Daniel Proefrock, Ed Pope, Ricardo Silva Jacinto, Maarten Heijnen, Sophie Hage, Stephen Simmons, Martin Hasenhündl, and Catharina Heerema

The increasing plastic pollution of the world’s oceans represents a serious threat to marine ecosystems and has become a well-known topic garnering growing public attention. The global input of plastic waste into the oceans is estimated to be approximately 10 million tons per year and predicted to rise by one order of magnitude by 2025. More than 90% of the plastic that enters the oceans is thought to end up on the seafloor, and seafloor sediment samples show that plastics are concentrated in confined morphologies and sedimentary environments such as submarine canyons. These canyons are occasionally flushed by powerful gravity-driven sediment flows called turbidity currents, which transport vast volumes of sediment to the deep sea and deposit sediment in deep-sea fans. As such, turbidity currents may also transport plastics present in the canyon and bury plastics in deep-sea fans. These fans may therefore act as sinks for seafloor plastics. Here we present a comprehensive dataset showing the spatial distribution of microplastics in seafloor sediments from the Congo Canyon, offshore West Africa. Multicores taken from 16 locations along the canyon, sampled different sedimentary sub-environments including the canyon thalweg, canyon terraces, and distal lobe. Microplastics were extracted from the sediments by density separation and the polymer type, size, and shape of all individual microplastic particles were analysed using laser-direct infrared-spectroscopy (LDIR). Microplastic number concentrations in the sediments of the distal lobe are significantly higher than in the canyon, indicating that the Congo Canyon system is a highly efficient conduit for microplastic transport to the deep sea. Moreover, microplastic concentrations of >20,000 particles per kg of dry sediment were recorded in the lobe, which represent some of the highest ever recorded microplastic number concentrations in seafloor sediments. This shows that deep-sea fans can serve as hotspots and potential terminal sinks for seafloor microplastics.

How to cite: Pohl, F., Hildebrandt, L., O’Dell, J., Talling, P., Baker, M., El Gareb, F., La Nasa, J., De Falco, F., Mattonai, M., Ruffell, S., Eggenhuisen, J., Modugno, F., Proefrock, D., Pope, E., Silva Jacinto, R., Heijnen, M., Hage, S., Simmons, S., Hasenhündl, M., and Heerema, C.: The submarine Congo Canyon as a conduit for microplastics to the deep sea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12344, https://doi.org/10.5194/egusphere-egu23-12344, 2023.

EGU23-14119 | ECS | Orals | SSP1.4

Transport and trapping of microplastics in coral reefs: a physical experimental investigation 

Robert Houseago, Freija Mendrik, Christopher Hackney, and Daniel Parsons

Biodiverse coastal ecosystems are vulnerable to microplastic (<5 mm) pollution due to inputs from riverine and shoreline sources which pose ecological threats and have repercussions for social ecosystem services. These ecosystems may contain an aquatic canopy covering the bed, such as seagrass meadows or coral reefs that can trap particles. Despite field measurements revealing the accumulation of plastic debris in a variety of aquatic canopies, the transport and dispositional processes that drive microplastic trapping within such canopies is barely understood. Here, we investigate for the first time the prevalence of biofilmed microplastic retention by sparse and dense branching coral canopies in a hydraulic flume under unidirectional flow. Corals were replicated through 3D-printing using a scan of a staghorn coral Acropora genus, a branching coral that encompasses one-fifth of extant reef-building corals, globally.

Trapping mechanisms by coral canopies were identified, and include: a) interception of particles with the coral acting as a barrier and microplastics and settling to the bed; b) settling of microplastics on the branches or within the structure of the coral and c) accumulation in the downstream region of individual corals. Trapping efficiency was found to depend on bulk velocity and canopy density, with up to 99% of microplastics retained across the duration of the experiments. Surprisingly, sparse reefs may be as vulnerable to microplastic trapping and contamination as denser canopies under certain flow velocities, with the latter found to retain only up to 18% more microplastics than in sparser conditions. Flow velocity profiles provide insights into the relationships between canopy hydrodynamics and microplastic trapping and distribution. The results indicate coral reefs may form areas of accumulation for microplastic pollution through their observed high trapping efficiency that may otherwise have been transported greater distances.

How to cite: Houseago, R., Mendrik, F., Hackney, C., and Parsons, D.: Transport and trapping of microplastics in coral reefs: a physical experimental investigation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14119, https://doi.org/10.5194/egusphere-egu23-14119, 2023.

EGU23-14286 | ECS | Posters on site | SSP1.4

Paradise lost: Microplastic pollution on a remote coral island, Vietnam 

Freija Mendrik, Christopher Hackney, Vivien Cumming, Nguyen Hung, Sebastian Hennige, and Daniel Parsons

Despite microplastic pollution now being ubiquitous in natural environments, there remains several unknowns in terms of which zones may act as microplastics sinks. Coral reefs are the most ecologically diverse marine ecosystem, supporting 25% of all ocean species, and have high socio-economic value, offering ecosystem services such as coastal protection and tourism. However, the average cover of tropical reefs has declined by 50-75% in nearly all global regions over the last 30-40 years due to a range of anthropogenic stressors. There is growing evidence that coral reefs can entrap plastics and that microplastic (>5 mm) pollution threatens coral physiology. However, there is a lack of understanding as to the occurrence, accumulation, spatial distribution and impacts of microplastic pollution on coral ecosystems. It is, therefore, necessary that more research is undertaken within coral reefs to understand microplastic contamination levels and ensure effective mitigation measures are in place.

The islands of Con Dao, Vietnam, are 90 km from the Mekong Delta coast and are a designated national park, with a 14,000 ha marine protected area that conserves endangered wildlife and a diverse range of coral that support hundreds of fish species. Although considered pristine, Con Dao it is influenced by the Mekong River, which is one of the top contributors to marine plastic waste worldwide, posing an increasing risk to this biodiversity hotspot. Understanding the volumes and impacts of microplastic pollution in this area will allow insight into the levels of exposure and risk coral reefs in Southeast Asia, including the highly biodiverse Coral Triangle, have from increasing plastic pollution.Here, the occurrence and spatial distribution of microplastics in water and sand samples from Con Dao is presented. Reef health is also provided through photogrammetry whereby 3D reconstruction of reef sites allows analysis of coral cover and diversity, in addition to structural complexity, which is strongly correlated to reef health indicators including biodiversity, especially within tropical reef ecosystems. Potential sources of microplastics are also discussed through polymer identification by FT-IR analysis.

How to cite: Mendrik, F., Hackney, C., Cumming, V., Hung, N., Hennige, S., and Parsons, D.: Paradise lost: Microplastic pollution on a remote coral island, Vietnam, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14286, https://doi.org/10.5194/egusphere-egu23-14286, 2023.

EGU23-14881 | ECS | Posters virtual | SSP1.4

Modelling the Uptake and Exchange of Microplastics in Marine Ecosystems using a Novel, Integrated System of High-Resolution Numerical Models 

Róisín Coyle, Jennifer McKinley, Gary Hardiman, Matthew Service, and Ursula Witte

Microplastics (mPs), defined as plastic particles that are less in 5mm in size, are ubiquitous within the marine environment. They are difficult to remove from natural water streams and persist for long periods of time, breaking down into continually smaller particles. Since the diversity of organisms that can ingest plastic particles increases as the particle size decreases, microplastics have been identified as an emerging contaminant of concern in the marine environment and the determination of the potential ecological harm caused by mPs is a key objective of the EU Marine Strategy Framework Directive (MSFD 2008/56/EC). However, the completion of a comprehensive risk assessment of this marine pollutant is prevented by the current lack of consensus on the processes influencing mP transport, uptake and exchange in the marine environment. For example, the processes driving the transport of mPs with buoyant polymers to the deepest part of the ocean are surrounded in uncertainty. The potential for mPs to accumulate within organisms and consequently the significance of trophic transfer as an uptake route for mPs is also unclear, particularly at lower trophic levels where contrasting arguments have formed on the risk of trophic transfer of mPs via zooplankton.

In this study, an integrated system of numerical models has been proposed to improve our understanding of mP processes in the marine environment by simulating the transport and ecosystem uptake and exchange of mPs at lower trophic levels in the northwest European continental shelf region. The continued refinement of the mathematical models will be presented, including the results of tests undertaken to evaluate the efficacy of empirical models for the calculation of the vertical settling velocity of irregularly-shaped particles from the perspective of mP transport modelling. Based on the current availability of data on mP distribution and uptake by lower trophic level organisms in the study area, the feasibility of model implementation will be examined as well as the significance of this research in providing information required by policy makers to complete risk assessment and implement suitable management strategies for marine mP pollution.

How to cite: Coyle, R., McKinley, J., Hardiman, G., Service, M., and Witte, U.: Modelling the Uptake and Exchange of Microplastics in Marine Ecosystems using a Novel, Integrated System of High-Resolution Numerical Models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14881, https://doi.org/10.5194/egusphere-egu23-14881, 2023.

EGU23-16232 | Orals | SSP1.4

Depositional patterns of microplastics in a meandering river: a case study of the Leie River, Belgium 

Maarten Van Daele, Ben Van Bastelaere, Maaike Vercauteren, Inka Meyer, and Jana Asselman

Following the discovery of microplastics (MPs) in river sediments, the number of MP studies on rivers and other freshwater systems has increased rapidly, revealing that MPs are omnipresent in all freshwater environments. The abundance of MPs in freshwater sediments seems to be affected by population density, urban centers, water flow velocity, water catchment size and position and type of sewage and waste management. However, not all of these relations are consistent. For example, while many studies report good correlations between MP source regions (highly populated and industrialized areas) and MP abundance in river sediments, others do not. This is in contrast to the concentrations in the water itself, for which better links with MP source areas were found. What all these studies have in common, is their large-scale approach, in which sediment samples are obtained over distances of tens to thousands of kilometers along the river; and at each site sediments are than retrieved either from the deepest part of the channel or from the river bank (depending on the study). Here, we study MP distribution in a section of the meandering Leie River, in a rural area, a few kilometers upstream of the city of Ghent (Belgium). Multibeam bathymetry and side-scan sonar images allowed selecting three undisturbed across-channel transects where surface sediments were retrieved. Sediment samples were analyzed for MP content, organic-matter content and grain size of the clastic fraction. Overall the MP concentrations are much (up to an order of magnitude) lower in the thalweg compared to samples near the river banks, resulting in an asymmetric distribution at the bend apex, where the thalweg approaches the outer banks. Furthermore, MP concentrations show strong correlations with the organic matter content and grain-size parameters as expected form hydrodynamic sorting. Exceptions to these correlations are the outer bank samples, where MP concentrations are lower than predicted from sedimentological characteristics. We attribute this to the more erosive character of the current in the thalweg near the outer banks, which inhibits MP deposition, but exposes fine-grained and organic-rich flood plain sediments. We highlight that the different hydrodynamic conditions across a river channel greatly influence MP distribution (with an order of magnitude), but in a sedimentologically predictable manner. Care should thus be taken in environmental studies, as local variability in MP concentration across a river bed may be larger then the large-scale variability.

How to cite: Van Daele, M., Van Bastelaere, B., Vercauteren, M., Meyer, I., and Asselman, J.: Depositional patterns of microplastics in a meandering river: a case study of the Leie River, Belgium, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16232, https://doi.org/10.5194/egusphere-egu23-16232, 2023.

EGU23-66 | ECS | Posters virtual | GD9.1

The time and geodynamics for the final large-scale lateral accretion of the southern Central Asian Orogenic Belt 

Hai Zhou, Guochun Zhao, Yigui Han, Donghai Zhang, and Xianzhi Pei

During Carboniferous time, tremendous juvenile arc crust was formed in the southern Central Asian Orogenic Belt (CAOB), although its origin remains unclear. Our work presented zircon U-Pb-Hf and whole-rock geochemical and Sr-Nd isotopic data for a suite of volcanic and pyroclastic rocks from the Khan-Bogd area in southern Mongolia. These Carboniferous pyroclastic rocks generally have some early Paleozoic zircons, probably derived from the granitic and sedimentary rocks of the Lake Zone and the Gobi-Altai Zone to the north, indicative of a continental arc nature. In addition, they have a main zircon U-Pb age of ca. 370–330 Ma, positive Hf and Nd isotopes, and mafic-intermediate arc affinity, similar to the coeval arc magmatism. Moreover, the pyroclastic rocks of the northern area have more mafic and older volcanic components with depositional time (ca. 350–370 Ma; Visean and Bashkirian stages) earlier than that in the southern area (mainly ca. 350–315 Ma; Serpukhovian and Bashkirian stages). Combining a preexisting northward subduction supported by the available magnetotelluric data with a slab rollback model of the main oceanic basin of the Paleo-Asian Ocean (PAO) during Carboniferous and Triassic times, we infer that the Carboniferous arc magmatism was probably derived from a backarc ocean triggered by slab rollback. Thus, the juvenile arc volcanism of Mongolia, together with other areas (e.g., Junggar) in the southern CAOB, represented a significant lateral accretion that terminated after the Carboniferous due to a significant contraction of the PAO. This research was financially supported NSFC Project (42102260, 41890831, 42072267, and 41972229), Hong Kong RGC GRF (17307918), and HKU Internal Grants for Member of Chinese Academy of Sciences (102009906) and for Distinguished Research Achievement Award (102010100).

How to cite: Zhou, H., Zhao, G., Han, Y., Zhang, D., and Pei, X.: The time and geodynamics for the final large-scale lateral accretion of the southern Central Asian Orogenic Belt, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-66, https://doi.org/10.5194/egusphere-egu23-66, 2023.

EGU23-343 | ECS | Posters on site | GD9.1

Seismicity and active tectonics:  New insights from Sikkim Himalaya 

Mita Uthaman, Chandrani Singh, Arun Singh, Abhisek Dutta, Arun Kumar Dubey, and Gaurav Kumar

The Himalayas, which formed as a result of the impactful collision of the Indian plate with Eurasian plate, is a tectonically complex and seismically active region. It has been a hotspot for many great earthquakes in the past. The continued collision coupled with the complex structural features has led to the persistent seismic activity of the region. The progressive collision led to the formation of distinct tectonic units bounded by thrust faults. The northeastern state of Sikkim in India, which is sandwiched between Nepal and Bhutan in the Himalayas, has been prone to frequent great earthquakes. The deployment of a dense seismic network consisting of 27 broadband seismometers, across Sikkim Himalayas and the northern part of West Bengal, since April 2019 has enabled us to monitor the seismic activity in the study region.

Here, we present a study which aims at understanding the seismotectonic activity of the study region using local earthquakes (epicentral distance < 200km) recorded by the network between April 2019 and September 2022. The progressively improved relocation of local earthquakes recorded in the study region shows a diffuse cloud of micro-seismicity concentrated along a diagonal region extending from north of Assam in the southeast to south of Tibet in the northwest. From south to north we have observed clusters of earthquakes with a gradual increase in their hypocentral depths.

The upper-crustal earthquakes (~0-25km) are located near the down-dip end of the locked part of the Main Himalayan Thrust (MHT), along which India underplates Tibet. We also observe prominent lower crustal earthquakes at depths greater than 30 km. These earthquakes are possibly originating at the junctions of different blocks in an imbricated crust in response to active shortening. We also observe a mid-crustal seismicity pattern following the DCFZ (Dhubri-Chungthang Fault Zone), supporting observations from earlier studies. Striking variations are observed in the faulting mechanisms and orientation of stress axes along the north-south and east-west profiles, and also with depth. We plan to further investigate if these variations imply the presence of possible segmentation, its depth, extent, surface expression and determine its relation to the geodynamics of the region. Integrating the results obtained from the various studies and interpreting them will help in delineating the seismotectonic activity of the study region. Quality data recorded by the dense network will further complement in enhancing the resolution of the results obtained.

How to cite: Uthaman, M., Singh, C., Singh, A., Dutta, A., Kumar Dubey, A., and Kumar, G.: Seismicity and active tectonics:  New insights from Sikkim Himalaya, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-343, https://doi.org/10.5194/egusphere-egu23-343, 2023.

EGU23-349 | ECS | Orals | GD9.1

Cretaceous magmatism from the Sava-Vardar Zone of the Balkans 

Kristijan Sokol, Dejan Prelević, and Ana Radivojević

Кеy words: Upper Cretaceous magmatism, Sava Vardar Zone, Adria, basalts

The complex geodynamic evolution of the northernmost Neotethys is the subject of a long-living controversy. The most perplexing issues are related to the waning stage(s) of the Tethyan ocean(s) in the Balkans and the timing of the Europe-Adria collision. Some authors consider this collision to have occurred in the Late Jurassic, whereas others envisage that have happened at the end of the Cretaceous along the Sava-Vardar Zone. The second model assumes this zone contains a relic suture between Africa- and Europe-derived units.

Late Cretaceous magmatism along the Sava-Vardar Zone includes several centers of small-volume transitional to alkaline Na-basalt (with subordinate rhyolitic rocks) and rare ultrapotassic lavas. This volcanism occurs in both Europe- and Africa- derived units of the collisional zone. The geochemical and isotope compositions of the Late Cretaceous lavas suggest that they are not a part of dismembered ophiolite sequences, but represent intracontinental magmas derived from variably enriched mantle sources. The transitional to alkaline Na-basaltic lavas show a clear “within plate” geochemical signature with typical mantle-like 87Sr/86Sri, 143Nd/144Ndi and 206Pb/204Pbi ratios with relatively high HFSE/LILE ratios, and without orogenic geochemical signatures such as high LILE/HFSE ratios, positive Pb and negative Ti–Nb–Ta anomalies, whereas the ultrapotassic lavas are lamprophyres demonstrating enriched 87Sr/86Sri, 143Nd/144Ndi and 206Pb/204Pbi ratios, LILE enrichment, and orogenic geochemical signatures. A broad range of MREE/HREE ratios in these locations suggests polybaric mantle melting.

Our working melting model is that the mafic melts were generated as a continuum with low-degree melting in the asthenospheric mantle within the garnet stability field and high-degree melting of the freshly metasomatized lithospheric mantle in the spinel stability field. The ultimate trigger of the mantle melting along the Sava-Vardar Zone should be localized extension during transtensional tectonics, in a system of pull-apart basins (Köpping et al., 2019).

Acknowledgments: This research was financed by the Science Fund of the Republic of Serbia through project RECON TETHYS (7744807).

Köopping, J., Peternell, M., Prelevi_c, D., Rutte, D., 2019. Cretaceous tectonic evolution of the Sava-Klepa Massif, Republic of North Macedonia e results from calcite twin based automated paleostress analysis. Tectonophysics 758. https://doi.org/10.1016/j.tecto.2019.03.010.

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How to cite: Sokol, K., Prelević, D., and Radivojević, A.: Cretaceous magmatism from the Sava-Vardar Zone of the Balkans, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-349, https://doi.org/10.5194/egusphere-egu23-349, 2023.

The majestic Himalayan-Tibetan mountains raised due to doubling of the continental crust during the India-Asia collision, which is commonly assumed to occur by under-thrusting of the Indian crust directly below the Asian crust. However, this model implies rheologically weak subducting and upper plate lithospheres and, thus, a collision system that is unable to support a high plateau and whose deformation style is inconsistent with the gross structural and metamorphic architecture of the Himalayan-Tibetan system. Numerical models show that collision between relatively stiffer plates generates strain and metamorphic structures as well as elevations more similar to those observed, but crustal doubling occurs by stacking the subducting crust underneath the rigid upper plate mantle lithosphere. A marked mantellic signature in fluids outflowing the suture zone, the geochemistry of south Tibetan mantle xenoliths, and long wavelength buckling of the Tibetan lithosphere further support the presence of intra-crustal mantle between the Indian and Asian continental crusts. Reconciling the available geophysical evidence with this new model of crustal doubling in the Himalayan-Tibetan range will entail profound implications for our understanding of mountain building during continental subduction and collision.

How to cite: Sternai, P.: Intra-crustal mantle underneath the Himalayan-Tibetan range, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1665, https://doi.org/10.5194/egusphere-egu23-1665, 2023.

EGU23-2259 | Posters on site | GD9.1

Frequency dependent attenuation and relative site response of western Tibet 

Chandrani Singh, Ashwani Kant Tiwari, Eric Sandvol, Shirish Bose, Namrata Jaiswal, Niptika Jana, and Arun Kumar Gupta

We have formulated frequency dependent Lg and Pg attenuation tomographic models to investigate the
crustal Q values and its tectonic implications beneath western Tibet. The frequency dependent
behaviour of both Lg and Pg are studied for the frequency bands of 0.2-0.6, 0.6-1.0 and 1.0-1.4 Hz at
central frequencies of 0.4, 0.8, and 1.2 Hz, respectively, implementing both Two-Station Method
(TSM) and Reverse Two-Station Method (RTSM). The amplitudes of both the waves are fundamentally
sensitive to the crustal structures and are controlled by both scattering and intrinsic attenuation. The
frequency dependent characteristics of QLg and QPg are consistent in nature for the region. Moderate to
high Q values evident in the Lhasa terrane could supplement the trace of underthrusting Indian
lithosphere beneath the region. The average Q values for both Lg and Pg increase with increasing
frequency. The frequency dependent parameter η shows quite high values, for both the waves using
TSM and RTSM, which may indicate strong heterogeneities present in the crust. Subsequently, relative
site responses at each station are studied using RTSM for the central frequencies of 0.4, 0.8, and 1.2
Hz. Weak to negative site responses are mostly dominant in western Tibet. Relative site responses are
found to vary with frequency which could be associated with the sampling depth. We found no
correlation of site responses with the elevation.

How to cite: Singh, C., Tiwari, A. K., Sandvol, E., Bose, S., Jaiswal, N., Jana, N., and Gupta, A. K.: Frequency dependent attenuation and relative site response of western Tibet, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2259, https://doi.org/10.5194/egusphere-egu23-2259, 2023.

EGU23-2463 | Posters on site | GD9.1

Seismic constraints on the nature and geometry of the downwelling Indian crust beneath Sikkim Himalaya 

Arun Singh, Gaurav Kumar, Chandrani Singh, M. Ravi Kumar, Mita Uthaman, Dipankar Saikia, and Arun Kumar Dubey

  The exact role of subducting Indian continental crust in the formation of Himalaya-Tibet collision zone remains enigmatic. The mass budget estimates describing shortening across the orogen is partly derived from the observations made from seismic imaging of deep earth. Here using data from 38 broadband seismic stations covering Sikkim Himalaya, we produce high resolution seismic images in order to fill the crucial gaps in our understanding of the formation of Himalayan collision zone. We have used 11,594 high quality receiver functions using earthquakes of magnitude >5.5 in the distance range of 30-100°. Our data demonstrates a highly imbricated and heterogeneous crust beneath Sikkim Himalaya. The Main Himalayan thrust responsible for large scale earthquakes in the Himalayan collision zone is not so vivid in the migrated images, but is observed intermittently. The main cluster of earthquakes at shallower depths linked to the Main Himalayan thrust is marked by low amplitude arrivals. Overall trend suggests a gently dipping Moho attaining crustal depths of ∼60 km beneath Higher Himalaya compared to ∼40 km in the Himalayan foredeep. Moho as we see in this segment of Himalaya is with possible offsets and overlapping segments. Imbrication is well reported in the Himalayan orogenic wedge forming upper crust, we also observe this in the lower crust indicating lithospheric imbrication in response to collision. Interestingly, the lower crustal clusters of earthquakes fall at the juncture of offsets in the Moho. The offset positions at lower crustal depths seem more prone to earthquakes in response to active shortening. Seismic images reveal differences in amplitude of receiver functions and presence of conversions at deeper depths in the lithospheric mantle across Dhubri-Chungthang Fault Zone, possibly related to the segmentation of Himalaya.  

How to cite: Singh, A., Kumar, G., Singh, C., Kumar, M. R., Uthaman, M., Saikia, D., and Dubey, A. K.: Seismic constraints on the nature and geometry of the downwelling Indian crust beneath Sikkim Himalaya, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2463, https://doi.org/10.5194/egusphere-egu23-2463, 2023.

EGU23-2521 | Orals | GD9.1

Early Indosinian magmatism in the West Qinling orogen and its tectonic implication 

Meng Wang, Xianzhi Pei, Zuochen Li, Ruibao Li, Lei Pei, Youxin Chen, Chengjun Liu, and Shaowei Zhao

The West Qinling Orogen (WQO), which is bounded by the Qilian Orogenic Belt, Qaidam Block and the Songpan-Ganzi Block, is the western extension of the Qinling Orogenic Belt, and experienced complex tectonic evolution processes, involving the opening, subduction and closure history of the Proto- and Paleo-Tethys Oceans. The WQO features widespread Indosinian magmatic rocks, which are crucial to constrain the tectonic evolution of the WQO. The Indosinian magmatic rocks were formed mainly in two stages, 250 to 240 Ma and 225 to 210 Ma. The Early Indosinian magmatic rocks (250 to 240 Ma) are mainly distributed in the west and middle northern WQO. In comparison, the Late Indosinian magmatic rocks are mainly exposed in the eastern WQO, but also in the western WQO and the Bikou terrane. Controversy has existed for a long time on the petrogenesis and tectonic setting of the Early Indosinian magmatic rocks. We selected four respective plutons, including the Heimahe pluton, the Ren’ai pluton, the Daerzang pluton and the Ganjiagongma pluton. Detailed field investigation, petrology, LA-ICP-MS zircon U-Pb dating, zircon Lu-Hf isotope analyses, whole rock geochemistry and Sr-Nd isotope analyses, and mineral EPMA analyses were conducted for the studied plutons. The studied plutons were emplaced between 246 to 241 Ma according to zircon U-Pb dating results. Based on detailed studies on petrology, geochronology and geochemistry, we emphasis the significance of magma mixing in the petrogenesis of the Early Indosinian granitic rocks. The high Mg# signature of the Early Indosinian granitic rocks were generated by magma mixing between mafic and felsic magmas, but not result of direct fractional crystallization of mafic rocks. The granitic rocks with high Sr/Y values in the WQO, represented by the Ganjiagongma pluton, were not derived from thickened continental crust. No evident continental thickening occurred in the WQO during the Early Indosinian. Combining with regional geological evidence, we propose an alternative tectonic model to explain the evolution history of the WQO during the early Mesozoic. The A’nimaque-Mianlue ocean subducted northward with low angle, then the subducted slab rolled back during the Late Permian to Middle Triassic, and the ocean closured in the Late Triassic. This model can explain the spatial and temporal distribution characteristics of the magmatic rocks and sedimentary rocks, as well as Late Triassic uplift and deformation event in the WQO.

How to cite: Wang, M., Pei, X., Li, Z., Li, R., Pei, L., Chen, Y., Liu, C., and Zhao, S.: Early Indosinian magmatism in the West Qinling orogen and its tectonic implication, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2521, https://doi.org/10.5194/egusphere-egu23-2521, 2023.

EGU23-2622 | Orals | GD9.1

Synced deformation of the Talesh-Alborz-Kopet Dagh belt and formation of the Iranian Plateau 

Yang Chu, Bo Wan, Ling Chen, Wei Lin, Morteza Talebian, Xiaofeng Liang, and Liang Zhao

Plate convergence has continued for over 25 Myr after the Arabia initially collided with the Eurasia, causing vast intracontinental deformation within the Central Iran Block at the southern margin of the Eurasia. During the same period, the Iranian Plateau grew as tectonic stress from continental collision propagated northwards, accompanied by strong deformation, crustal shortening and rapid rock exhumation, but the process of the plateau formation remains less discussed. From west to east, the Talesh-Alborz-Kopet Dagh (TAK) situates at the northern front of the Iranian Plateau and suffers intense folding and thrusting that creates the highest mountain range in Iran, so its tectonic evolution history carries important clues for the building of the current plateau.

To better constrain the spatial and temporal patterns of deformation and exhumation, we carried out comprehensive structural analysis and new geochronology-thermochronology dating for the TAK. As a first order feature of the collision zone, the TAK records an immediate response to the initial collision. Oligocene deformation is well documented but unevenly exhumed different segments of the belt along-strike. The Talesh and westernmost Alborz preserves late Neoproterozoic basement rocks (~570 Ma) and old, Mesozoic zircon U-Th/He ages (150-90 Ma), acting as a relatively rigid part resistant to Oligocene deformation. In contrast, the main part of Alborz was remarkedly shortened by folds and thrusts and exhumed rapidly, while the Kopet Dagh shows a simply folded belt dominated by box folds in deca-kilometer scale. All the TAK experienced enhanced exhumation since 20 Ma, peaked at the Late Miocene, suggesting the deformation was synced around 7 Ma when the internal tectonic organization along the belt and within the Central Iran Block had been much reduced. This Late Miocene switch reflects a reorganization of Arabia-Eurasia plate convergence. The causes could include that elevation increased to a level at which the Iranian Plateau was built and resisted further thickening, or internal heterogeneity was decreased and the whole region began to evolve as a single tectonic unit, causing deformation to be accommodated in other regions. The growth model of Iranian Plateau can also enlighten us on how Tibetan Plateau developed and expanded at its early stage.

How to cite: Chu, Y., Wan, B., Chen, L., Lin, W., Talebian, M., Liang, X., and Zhao, L.: Synced deformation of the Talesh-Alborz-Kopet Dagh belt and formation of the Iranian Plateau, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2622, https://doi.org/10.5194/egusphere-egu23-2622, 2023.

EGU23-3799 | Orals | GD9.1

NW Iran under pressure: Cristallization and metamorphic ages of the Shanderman eclogites. 

Daniel Pastor-Galán, Tatsuki Tsujimori, Alicia López-Carmona, and Keewook Yi

The Tethyan oceans are the internal sotry-tellers of the amalgamation, tenure and break up of Pangea. All tethyan oceans have been mostly consumend and only remnants of them occur now along the margins of the Atlantic, Mediterranean, Black and Caspian seas, as well as in the Alpine-Himalayan and adjacent orogens. The Rheic (~500 to ~300 ma, some-times Ran or Proto-Tethys) closed during the amalgamation of Pangea and the Neo-Tethys (~270 to ~20 ma) is the main witness of its break-up. The Paleotethys is the ocean that shared an internal position during most of Pangea’s tenure. There is no consensus about its origin, some suggest that opened during the latest stages of Pangea’s amalgamation (Devonian-Carboniferous) whereas others considert it a remnant of the mostly subducted Rheic ocean after Gondwana-Laurussia collision.

We have studied the Shanderman eclogites (NW Iran) and put them into their context within other HP rocks in the area because they a potential candidate to represent the Paleotethys ocean. They are metamorphosed oceanic rocks (protolith oceanic tholeiitic basalt with MORB composition). Eclogite occurs within a serpentinite matrix, accompanied by mafic rocks resembling a dismembered ophiolite. The eclogitic mafic rocks record different stages of metamorphism during subduction and exhumation.

In this contribution we will show the new petrological, geochemical and geochronological results from this eclogites to shed light on the evolution of the tethyan oceans during the Paleozoic. The protolithic oceanic crust of Shanderman crystallized ~350 Ma, metamorphic age suggest that this piece of ocean subducted soon after forming, representing, perhaps, a subduction initiation or a ride-subduction event. We also found a metasomatic event at ~280 ma. Considering its relation with other HP rocks in Iran, we interpret that the Shanderman ophiolites are not a fragment of the Paleotethys but a fragment of the Rheic (Ran/Prototethys) ocean.

How to cite: Pastor-Galán, D., Tsujimori, T., López-Carmona, A., and Yi, K.: NW Iran under pressure: Cristallization and metamorphic ages of the Shanderman eclogites., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3799, https://doi.org/10.5194/egusphere-egu23-3799, 2023.

EGU23-3845 | Posters on site | GD9.1

Orogenic Gold Mineralization and its Relationship to Tectonic Evolution of the Kalamaili Area, East Junggar, Northwest China 

Xuexiang Gu, Yongmei Zhang, Zhanlin Ge, Weizhi Chen, and Liqiang Feng

There are many lode gold deposits and occurrences in the Kalamaili area of the East Junggar, Northwestern China. The deposits are confined to a narrow zone between the regional NW- to NWW-trending Kalamaili and Qingshui-Sujiquan shear zones and are structurally controlled by secondary, high-angle faults of the regional shear zones. The orebodies occur in the Middle Devonian and Lower Carboniferous strata that are largely composed of zeolite to lower greenschist facies clastic sedimentary and pyroclastic rocks. Gold mineralization occurs as auriferous quartz-sulfide±tourmaline veins/veinlets and disseminated ores in the immediate altered wall rocks. The ore mineralogy is relatively simple and dominated by quartz with minor to trace amounts of sulfides (pyrite and arsenopyrite, typically <5% in volume), sericite, calcite, and gold. The hydrothermal alteration halos are characterized by a proximal, 0.5–5 m wide zone composed mainly of quartz-sericite (-tourmaline)-sulfide (-gold) and a distal, several to tens of meters wide zone with a calcite-chlorite-epidote assemblage. Hydrothermal processes essentially involve a pre-ore stage of barren quartz, a main-ore stage of quartz-sulfide-gold (±tourmaline), and a post-ore stage of barren quartz-calcite (±sericite).

Fluid inclusion microthermometry, stable isotopes, and hydrothermal zircon U-Pb dating were combined to constrain the nature and source of ore fluids, the timing of mineralization, and the mechanism of gold precipitation. The ore-forming fluid of the main-ore stage is uniformly characterized by a medium to high homogenization temperature (mostly 240° to 330℃), low salinity (typically <6 wt % NaCl equiv), reduced, and CO2-rich-H2O-NaCl±CH4 fluid. The hydrogen and oxygen isotope data (δ18OH2O=+8.4 to +17.3‰, δDH2O=–99 to –62‰) indicate a metamorphic origin for the mineralizing fluid. The majority of δ34S values of the sulfides range between 0 and +10‰ with a mean of +2‰ (n=62), indicative of a largely sedimentary rock reservoir of sulfur in the ore-forming fluids. LA-ICP-MS U-Pb isotope dating of the hydrothermal zircons from auriferous quartz veins yielded a weighted mean 206Pb/238U age of ~313 Ma.

Combined geological and geochemical evidence indicates that the transition from compressional to transcurrent deformation during the late- to post-orogeny in the late Carboniferous played a vital role for the gold-bearing fluid flow along regional shear zones and subsequent channeling into the second- and third-order faults. On a deposit scale, fault-valve behavior during seismic fault activity is a key mechanism that caused episodic changes in fluid pressure and the resultant phase separation of ore fluids and precipitation of gold. Sulfidation of wall rocks due to fluid-rock interaction is another important mechanism for the gold precipitation. Later since the Permian, the N-S compression resulted in uplift and exhumation of the East Junggar terrane and deformation of the orebodies. Target gold exploration in this region is suggested to focus on the northeast side of the Kalamaili fault zone, where there exist suitable faults that connect with the first-order fault zones at depth and lead to focused fluid flux into depositional sites at shallower levels.

How to cite: Gu, X., Zhang, Y., Ge, Z., Chen, W., and Feng, L.: Orogenic Gold Mineralization and its Relationship to Tectonic Evolution of the Kalamaili Area, East Junggar, Northwest China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3845, https://doi.org/10.5194/egusphere-egu23-3845, 2023.

Epithermal base and precious veins are typically structurally controlled, and structures are fundamental to fluid flow and mineralization in hydrothermal deposits. In recent mineral explorations in east Kerman, especially in the northeast of the Shahr-e Babak area, it was found that structures play a key role in the mineralization of epithermal gold deposits. Shahr-e Babak epithermal gold deposit is located at 30°27'54.80'' N, 54°31'47'' E in the southeast of the Sanandaj Sirjan Zone, east of Kerman. The lithological outcrops of the Shahr-e Babak deposit area consist of Cretaceous felsic to mafic intrusive and extrusive rocks, Eocene micrite limestone and sandstone intruded by hornblende diorite, granodiorite, and microgranite stocks and dykes. Gold mineralization with an average grade of 1.5 g/t, is associated with anomalous Ag, Mo, Pb, and Sb and is usually concentrated in jasperoids with argillic and silicification alteration halos which are < 120 m in length and average about 10 m in width within east-west trending structures.  

The Shahr-e Babak deposit area is located in a restraining bend of the Shahr-e Babak fault. There is a strike-slip duplex and E-W trending fault lens with an approximate 5×7 kilometers area related to the young movements of the Shahr-e Babak fault. For these reasons, the rocks in the deposit area have been ruptured and crushed which are not associated with extensive hydrothermal alterations. According to measurements, faults can be divided into three main groups. The first group is the main faults with 80–90-degree trending, the second group consists of faults with 100–120-degree trending and the last category is minor faults with NE-SW and NW-SE trending. A combination of field observations, measurements of faults and fractures, and drill core logging indicates that gold-bearing jasperoids are formed along strike-slip faults with a 100–120-degree trend in lens-shaped fault zones that change in thickness with depth. 

The recent discovery of the Shahr-e Babak epithermal gold deposit, located on a restraining bend of the Shahr-e Babak fault, highlights the exploration potential for epithermal gold mineralization in East Kerman. In addition, undiscoverable epithermal gold deposits may be hidden below the regionally extensive Quaternary cover.

How to cite: Shafiee, S., Niroomand, S., and Soleymani, M.: Identifying the Role of Structures in the Mineralization of Shahr-e Babak Epithermal Gold Deposit: Implications for Epithermal Gold Exploration in East Kerman, Southeastern Iran, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3961, https://doi.org/10.5194/egusphere-egu23-3961, 2023.

High-pressure and ultrahigh-pressure minerals tend to be preserved in mafic and ultramafic metamorphic rocks, such as eclogites and garnet amphibolites, rather than felsic rocks. Generally, the garnet amphibolites preserve particular porphyroblastic and corona textures that provide important information of geological processes. Therefore, identification of garnet amphibolite might hint that subduction or collision processes were likely to have occurred.

The Yili Block is one microcontinent in southwest of Central Asian Orogenic Belt, with Precambrain basement rocks exposed in the northern and southern margin. The Middle to Late Ordovician arc-type magmatic rocks were identified in the northern margin of the Yili Block with a subduction-related calc-alkaline affinity infer that the southward subduction of the Junggar Ocran beneath the Yili Block, but the record of coeval metamorphism is rarely reported. The Toksai garnet amphibolites idientified from the Wenquan Group in the northern margin of Yili Block records a clockwise P-T-t path. Its near isothermal depressive retrogressive metamorphism was typical characteristic of the Western Alps P-T path, recording the process of subduction and collision. The protolith belongs to tholeiite, with high TiO2 and low K2O+Na2O contents (3.10~3.89 wt.%, 0.76~2.01 wt.% respectively), enrichment of large ionic lithophile elements and depletion of high field strength elements, and enrichment of rare earth elements, showing the geochemical characteristics of tholeiite in intra-continental rift setting (Th/Ta=1.70~2.76, Ta/Hf=0.23~0.37). The geochemical characteristics reveal that the magmatic rocks derived from an OIB-like mantle source. The garnet amphibolites also has low contents of MgO (4.82~6.40 wt.%), Cr (70.8~224 ppm), Ni (9.68~65.7 ppm) and low values of Mg# (34.0~41.3), Nb/U (14.3~36.3), Nb/Ta (9.70~16.2), indicating that their protolith are not primitive magma, were formed by separate crystallization of different mineral phases with a small amount of crustal contamination. The zircon U-Pb dating results suggest that the garnet amphibolites protolith was formed in the middle to late Neoproterozoic, and the metamorphic age is end of Late Ordovician (450~440 Ma). The zircon and monazite from surrounding rocks also record the coeval tectonic thermal event. Consequently, it is inferred that the protolith of the garnet amphibolites may have formed in an intraplate rifting setting as a result of the breakup of Rodinia, and indicating that the Yili Block maybe a continental fragment separated from the Tarim Block during the middle to late Neoproterozoic. In the Middle to Late Ordovician, the Wenquan Group as a part of Aktau-Wenquan contineantal domain was involved in the continental–arc collision and continuing accretion in north of the Yili/Kazakhstan Block with the southward subduction of the Junggar–Balkhash oceanic lithosphere, and experience high amphibolite facies metamorphism in the end of Ordovician.

How to cite: Chen, Y., Wang, M., and Pei, X.: Chronology, geochemistry, metamorphic evolution and its tectonic implications of the Toksai garnet amphibolites in the northern margin of Yili Block, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4041, https://doi.org/10.5194/egusphere-egu23-4041, 2023.

EGU23-4091 | ECS | Orals | GD9.1

Late Mesozoic continental arc in East China Sea: Constraints from detrital zircons 

Yuling Deng and Changhai Xu

The Late Mesozoic subduction of Izanagi beneath East Asia formed large-scale intraplate magmatism in SE China and subduction mélanges from SW Japan to eastern Taiwan (Müller et al., 2016; Wang et al., 2008; Wakita and Metcalfe, 2005), but the accompanying arc remains uncertain. The East China Sea (ECS) is settled between the intraplate and trench, in which previous studies have found some arc indications (Xu et al., 2017). ECS domains share a unified basement with, or are regarded as an exotic microcontinent of Cathaysia block, which is still up for debate.

Discerning delta facies and litharenite types of sediment samples support a typical proximal environment of Lishui-Jiaojiang sag, SW ECS. As its provenances, nearby Zhemin and Yandang swells provide Late Mesozoic voluminous felsic suites with minor metabasite materials. We conducted LA-ICP-MS U-Pb zircon dating and trace element analyses of proximal sandstones in the SW ECS to track a Jurassic to Cretaceous magmatic arc, which advantages over the use of a few drilled igneous rocks. Newly acquired data reveal an evolved magmatic arc in SW ECS from Jurassic to Cretaceous (200–86 Ma), which developed predominantly in episodes of 150–124 Ma and 124–102 Ma. Arc magmatism exhibits characteristics of low-T and continental zircon types, yielding high Th/U, U/Yb, Sc/Yb, and Th/Nb ratios and low Nb/Yb and Nb/Hf ratios. Trace elements U and Th in arc zircons indicate a decline in subduction fluids addition due to slab rollback and a rise in lower crustal addition owing to fluid-fluxed crustal melting from Jurassic to Cretaceous.

The swells of Yushan, Zhemin, Haijiao, and Hupijiao outline a Late Mesozoic magmatic arc in the West ECS. This magmatic arc, in conjunction with the SE China intraplate, and subduction mélanges, spatially forms a Late Mesozoic trench-arc-intraplate architecture in response to the Izanagi subduction beneath East Asia. Its identified tectonic scenarios mainly include slab strike-slip subduction (200–170 Ma), slab stagnation and intraplate foundering (170–150 Ma), slab rollback and removal of the thickened arc root (150–102 Ma), and trench retreat with arc migration (102–86 Ma). Detrital zircon data suggest that the West ECS and Cathaysia block share a unified basement that formed at ca. 2.44 Ga and ca. 1.85 Ga, which was reworked at ca. 780 Ma, ca. 442 Ma, and ca. 240 Ma. The West ECS magmatic arc evolved on this Cathaysia-type basement.

Keywords: magmatic arc; detrital zircon; Late Mesozoic; Izanagi subduction

 

 

Müller, R.D., et al., 2016. Ocean basin evolution and global-scale plate reorganization events since Pangea breakup. Annual Review of Earth and Planetary Sciences, 44(1), 107138.

Wakita, K., and Metcalfe, I., 2005. Ocean plate stratigraphy in East and Southeast Asia. Journal of Asian Earth Sciences, 24(6), 679–702.

Wang, Y.J., et al., 2008. Sr-Nd-Pb isotopic constraints on multiple mantle domains for Mesozoic mafic rocks beneath the South China Block hinterland. Lithos, 106(3–4), 297–308.

Xu, C.H., et al., 2017. Tracing an Early Jurassic magmatic arc from South to East China Seas. Tectonics, 36, 466–492.

How to cite: Deng, Y. and Xu, C.: Late Mesozoic continental arc in East China Sea: Constraints from detrital zircons, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4091, https://doi.org/10.5194/egusphere-egu23-4091, 2023.

EGU23-4201 | ECS | Orals | GD9.1

Reassessment of the Phanerozoic net crustal growth: U–Pb and Hf zircon data for the Central Asian Orogenic Belt 

Ariuntsetseg Ganbat, Tatsuki Tsujimori, Daniel Pastor-Galán, and Alexander Webb

The Central Asian Orogenic Belt (CAOB) consists of several continental blocks, was assembled during the Phanerozoic, and preserves large volumes of Phanerozoic granitoids with juvenile Nd and Hf isotope characteristics, and thus regarded as the largest site of Phanerozoic continental growth on Earth. Nonetheless, it remains disputed whether the significant crustal additions occurred during the Phanerozoic. We compiled available zircon U–Pb geochronological and Hf-in-zircon isotopic data for granitoids from the orogenic segments of CAOB. Using this data, we estimated the percentage of juvenile versus evolved crustal portions in different Phanerozoic time slices of the CAOB.     

The areal distribution of Hf isotopic information shows a younging trend in the Hf model age and radiogenic Hf values from northeast to southwest. For many orogenic segments of the CAOB, the range of hafnium isotope signatures for the granitoids shifted towards more radiogenic compositions over time. We interpret these findings to indicate that the lower crust and lithospheric mantle beneath the CAOB continental blocks were largely removed during continuous oceanic subduction and replaced by juvenile crust. Melts of this crust display the radiogenic hafnium signature. The juvenile versus evolved crustal portion estimations in different time slices show that the crustal growth has taken place in a steady-state mode, and the rate of the radiogenic crustal generation is close to overall global averaged rates of crust generation. It follows that Phanerozoic net crustal growth in accretionary orogens, as exemplified by the CAOB, may have been overestimated as it has been compensated by crustal destruction.

How to cite: Ganbat, A., Tsujimori, T., Pastor-Galán, D., and Webb, A.: Reassessment of the Phanerozoic net crustal growth: U–Pb and Hf zircon data for the Central Asian Orogenic Belt, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4201, https://doi.org/10.5194/egusphere-egu23-4201, 2023.

EGU23-4461 | Posters on site | GD9.1

Thermochronologic constraints on exhumation associated with the Main Pamir Thrust 

Edward Sobel, Jonas Kley, Johannes Rembe, Rasmus Thiede, Johannes Glodny, Lennart Grimm, Maximilian Rometsch, Asil Newigy, Nowrad Ali, Wafaa Altyeb, and Daniela Espinoza Tapia

The Pamir orogen forms the northwest prolongation of the Tibetan plateau. The most important surficial structure bounding the northern and northwestern margin is the Main Pamir Thrust (MPT); however, despite the importance of the structure, surprisingly little is known about the displacement history of the fault. Together with the younger, foreland-oriented Pamir Frontal thrust system (PFT), displacement estimates range from 50 to over 300 km. The larger estimates are based on the estimated Cenozoic northward indentation of the Pamir with respect to Tibet as well as the length of the intracontinental Pamir seismic zone. However, recent work suggests that some of the indentation predates the Cenozoic or is related to an original Paleozoic embayed paleogeography and other studies have suggested that the seismic zone is not related to intracontinental subduction. Shortening estimates in the hanging walls of the MPT and PFT suggest more modest amounts: between 30 and 75 km in the north, with higher values for SE-NW shortening in the Tadjik depression.

Constraining the onset of deformation has proven challenging. Most publications suggest a late Oligo-early Miocene onset age. Cenozoic stratigraphic sequences are unfossiliferous and poorly dated. We have attempted to resolve this question by collecting samples for thermochronologic analysis from many locations along the arcuate margin. In general, zircon (U-Th-Sm)/He (ZHe) samples yield ages between ~60 and 17 Ma. Many are likely to be partially reset. Ages are slightly older in the east, which could reflect an overall westward increase in exhumation. The relatively small amount of exhumation in the north supports our structural interpretation that the MPT there has a low dip angle and might not have produced pronounced topography. Apatite fission track (AFT) and apatite (U-Th-Sm)/He (AHe) are often much younger; often between <15 and 10 Ma in the MPT hanging wall and < 10 Ma in the footwall. These younger ages may reflect the activation of a second pulse of exhumation linked to motion along the PFT. We are modeling these data sets using QTQt to try to better constrain the exhumation history of the fault system. In turn, these should help constrain shortening estimates.

How to cite: Sobel, E., Kley, J., Rembe, J., Thiede, R., Glodny, J., Grimm, L., Rometsch, M., Newigy, A., Ali, N., Altyeb, W., and Espinoza Tapia, D.: Thermochronologic constraints on exhumation associated with the Main Pamir Thrust, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4461, https://doi.org/10.5194/egusphere-egu23-4461, 2023.

The active deformation field between northern Tibet and central Mongolia is dominated by diffuse sinistral transpressional reactivation of the southern Altaids Phanerozoic terrane collage.   The angular relationship between NE-directed SHmax and pre-existing basement trends is the dominant control on Quaternary fault kinematics.  Along Tibet’s northern margin, the Altyn Tagh system is widening northwards by transpressional duplexing.  The Nanjieshan and Sanweishan comprise sinistral oblique-slip thrust ridges within a regional asymmetric flower structure centered on the Altyn Tagh Fault.  In the southern Beishan, interconnected lensoidal domains of transpressional and transtensional faulting are subtly indicated by Quaternary fault scarps, low-relief rejuvenated landscapes and alluvial sedimentation.  The SE Beishan and western Hexi Corridor region contain numerous Late Quaternary fault systems including the Heishan-Jinta'Nanshan sinistral strike-slip corridor and the Helishan-Longshoushan fault array that connects eastwards with the transtensional grabens of the Yabrai and Langshan in the eastern Alxa Block.  Further north, the Paleozoic terrane collage of the Gobi Corridor was repeatedly reactivated during the Permo-Triassic, Jurassic, Cretaceous and Neogene.  Late Cenozoic reactivation was likely facilitated by thermal weakening of the crust due to Jurassic-Miocene volcanism, and diffuse Cretaceous rifting and crustal thinning.  Although terrane boundaries and other faults are reactivated in many areas, thrust and oblique-slip reactivation of WNW striking shallowly dipping sedimentary bedding and metamorphic fabrics is equally important.  Conversely, modern E-W trending strike-slip faults in the Gobi Altai typically crosscut older basement trends. In the Altai and Gobi Altai, the Late Cenozoic fault array has created a transpressional  basin and range physiographic province.  Coalescence of separate ranges into topographically continuous mountain belts in the Altai, Gobi Altai and easternmost Tien Shan is an important mechanism of transpressional mountain building not predicted by classical plate tectonic models.  Throughout the vast deforming region north of Tibet, tectonic loading is shared amongst a diffuse fault network challenging assumptions about earthquake recurrence intervals and seismic hazard forecasting.

How to cite: Cunningham, D., Yang, H., and Zhang, J.: Late Cenozoic Crustal Reactivation of the North Tibetan Foreland, Western Hexi Corridor, Beishan, and Gobi Corridor: Implications for Intraplate Fault Networks, Mountain Building Processes and Earthquake Hazards in Slowly Deforming Regions of Central Asia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4597, https://doi.org/10.5194/egusphere-egu23-4597, 2023.

EGU23-4737 | ECS | Posters on site | GD9.1

Geophysical evidence of large-scale silica-rich fluid flow above the continental subduction interface 

Yuantong Mao, Liang Zhao, Marco Malusà, Stefano Solarino, Silvia Pondrelli, Baolu Sun, Coralie Aubert, Simone Salimbeni, Elena Eva, and Stéphane Guillot

Continental subduction zones are crucial tectonic settings where subducted slabs exchange crustal materials with the mantle, and geochemical changes occur with the participation of fluids at increasing temperatures and pressures. The occurrence of pervasive networks of quartz veins in exhumed sections of the Alpine subduction wedge provides evidence for major silica-rich fluid circulation in the shallowest levels of the subduction zone. However, the occurrence of silica-rich fluids at greater depths above the subduction interface remains speculative.

Rocks involved in the subduction zone experience variable temperature and pressure conditions and show a wide range of densities and seismic velocities that are not necessarily correlated. An integrated analysis of seismic velocities, Vp/Vs ratios and rock densities may provide a viable tool to detect compositional variations in the Earth’s interiors and infer the impact of large-scale fluid flows on the intrinsic physical properties of subducted rocks. We tackle this issue from a geophysical perspective, by applying H-κ stacking, receiver function analysis, and waveform and gravity modelling. We found a belt of high Vp/Vs ratios >1.9 in the rear part of the Alpine subduction wedge, consistent with a partly serpentinized upper-plate mantle, and a belt of unusually low Vp/Vs ratios <1.7 in the frontal part of the subduction wedge that we interpret as the effect of a pervasive network of silica-rich veins above the subduction interface. Laboratory experiment shows that Vp/Vs ratios are generally higher for serpentinite (2.0-2.2), and much lower for quartz (1.46-1.48).

Our results suggest a dominant role of silica-rich fluids in the subduction wedge. These silica-rich fluids rose within the subduction wedge until the change in ambient conditions precipitated the formation of a widespread network of quartz veins, as observed in the field. And this pervasive quartz-vein network changes the physical properties of the subduction-wedge rocks, implying a major impact on rheology favoring crustal deformation during continental subduction.

How to cite: Mao, Y., Zhao, L., Malusà, M., Solarino, S., Pondrelli, S., Sun, B., Aubert, C., Salimbeni, S., Eva, E., and Guillot, S.: Geophysical evidence of large-scale silica-rich fluid flow above the continental subduction interface, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4737, https://doi.org/10.5194/egusphere-egu23-4737, 2023.

EGU23-5179 | Posters on site | GD9.1

New constraints on the geological evolution of the SE corner of the Arabian Plate (NE Oman) 

Wilfried Bauer, Joachim Jacobs, Ivan Callegari, Andreas Scharf, and Frank Mattern

The Saih Hatat Dome is a tectonic window in northeastern Oman with a NW-SE extension of <95 km and an E-W extension of <50 km, rimmed by the allochthonous Samail Ophiolite and the underlain nappes composed of sedimentary rocks from the Neo-Tethyan Hawasina Basin. Rocks within the window were affected by an upper Cretaceous high- to ultra-high pressure/low-temperature eclogite- and blueschist-facies metamorphism.

Stratigraphically, the Saih Hatat Dome contains a several kilometer thick basal (“Autochthonous A”) sequence from what is believed Cryogenian Hatat schists to the Ediacaran Hiyam dolostone, unconformably overlain by 3400 m Cambro-Ordovician siliciclastics. This basal sequence is separated by a so-called ‘Hercynian’ unconformity from Permian to Jurassic overall shelf carbonates (“Autochthonous B”). In the eastern part of the window, intense Cretaceous deformation and metamorphism makes it difficult to identify this stratigraphic subdivision.

New U-Pb zircon LA-ICP-MS data from a quartzdiorite dyke, intruding the basal part of the Hatat schists gave a crystallization age of 845 +2/-4 Ma. Thus, the basal part of the Hatat schists is Tonian in age and older than the Cryogenian/Ediacaran strata of the nearby Jebel Akhdar Dome and Huqf area, 40 km to the west and 300 km to the south, respectively.

Two blueschist-facies tuffites from eastern Saih Hatat contain concordant detrital zircons, ranging in age between c. 530 and 2872 Ma with age clusters around 750 to 850 Ma and 1010 to 1164 Ma. The latter ages are not known from a source on the Arabian Plate and might be derived from an Indian source.

Based on the new results, we suggest a subdivision of the Saih Hatat stratigraphy with a Tonian accretionary wedge (Hatat schist) which might be coeval with igneous intrusion from the Ja’alab area, an Ediacaran carbonate platform, and a Cambrian sedimentary basin, unconformably overlain by upper Cambrian/Ordovician quartzites.

How to cite: Bauer, W., Jacobs, J., Callegari, I., Scharf, A., and Mattern, F.: New constraints on the geological evolution of the SE corner of the Arabian Plate (NE Oman), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5179, https://doi.org/10.5194/egusphere-egu23-5179, 2023.

EGU23-5946 | ECS | Posters virtual | GD9.1

Slab geometry and a diffuse plate boundary beneath Sumatra: constrained using a new receiver function analysis method 

Mingye Feng, Ling Chen, Shengji Wei, Xin Wang, Xu Wang, and Zimu Wu

Geometry and structure of the subducting plate boundary are key to understanding geodynamic processes of subduction and related geological phenomena. Located between the obliquely converging Indo-Australian and Sunda plates, the Sumatran subduction zone is featured by a strongly deformed slab coupling with the overlying plate, and complicated slab-mantle interactions, leading to frequent occurrence of great megathrust earthquakes (e.g., 2004 Mw9.2 and 2005 Mw8.7 events) and extremely intensive magmatism (e.g., Toba supervolcano). Previous seismic studies reveal a rugged slab surface with seamounts, and slab folding and tearing beneath Sumatra, both of which govern the features of earthquake rupture and magma generation associated with fluid release and mantle wedge hydration. However, the details of the slab geometry (e.g., along-strike variation of dip direction and dip angle) and the “slab dehydration-mantle hydration” process across the subducting plate boundary remain poorly known, due to limited data coverage and resolution of these studies.

To better reveal the geometry of the slab and the feature of “slab dehydration-mantle hydration” during the oblique subduction, in this study, we develop a Dip Direction Searching (DDS) method to constrain the dipping structure of slab and the nature of the slab upper boundary. In this method, we estimate dip directions of velocity discontinuities by grid search based on the back azimuthal variation of radial receiver functions (RFs). DDS is a single-station-based method thus applicable in the areas with sparse seismic instruments. Synthetic tests demonstrate that the DDS method has higher resolution (with uncertainty of several degrees) in dip direction estimation than traditional RF analysis approaches and is applicable to the cases with strong white noise contamination, incomplete/uneven back azimuthal coverage, <5%-10% crustal and mantle anisotropy, and their compound effects. The method also provides constraints on the thickness and depths of dipping layers.

Applying the DDS method, we find a dipping Low Velocity Layer (LVL) commonly beneath the forearc areas and constrain its depths, thickness, and dip directions. The depth and dip direction estimates are highly consistent with the Slab2 model, indicating that the LVL is at the subducting plate boundary. We interpret the lower boundary of the LVL as the subducting oceanic Moho, which is less deformed so its dip direction can represent the dip direction of the whole slab. The slab dip direction gradually increases from 47±5.3˚ in southern Sumatra to 70±10.7˚ in northern Sumatra, indicating an along-strike bending of slab, which is possibly related to the oblique subduction. We find that the dip directions at the upper and lower boundaries of the LVL differ up to 23˚ beneath central Sumatra, indicating the two boundaries are locally unparallel. The thickness of the LVL is estimated to be 10-14 km, larger than those of regular oceanic crusts (~7 km). These observations imply that the LVL is composed by not only the oceanic crust but also a low-velocity serpentinized mantle layer at the top. Therefore, the upper boundary of the LVL represents the serpentinization front, indicating a diffuse plate boundary.

How to cite: Feng, M., Chen, L., Wei, S., Wang, X., Wang, X., and Wu, Z.: Slab geometry and a diffuse plate boundary beneath Sumatra: constrained using a new receiver function analysis method, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5946, https://doi.org/10.5194/egusphere-egu23-5946, 2023.

Abstract:

The development of faults governs the kinematics of continental deformation. The Songliao Basin, located at the central part of late Mesozoic lithospheric thinning province in East Asian region, experienced intense rifting during Early Cretaceous epoch and formed an intricate syn-rift fault system. However, the geometric and kinematic relationships inherent in the fault system have not yet been satisfactorily explained, hampering the understanding of basin formation and related marginal plate tectonic processes. Here, theories for polymodal faulting were applied to evaluate the faulting evolution of the Songliao Basin, based on which a quantitively deformation reconstruction was developed. Our reconstruction shows that the basin formation during the syn-rifting period was subdivided into three main stages: late Valanginian–Barremian(133-118.2Ma) initiation of extension, Aptian(118.2-113.9M) extension climax, and Albian(113.9-100.5Ma) extension wanning and initiation of post-extensional subsidence. The deformation of the Songliao Basin is spatially heterogeneous. Faulting analyses revealed a three-dimensional strain filed with a dominating horizontal ESE-WNW extension, a minor horizontal near N-S extension, and a large vertical shortening in the Northern Songliao Basin (NSL). The 3-D non-plane strain with non-zero intermediated extension(ε2) magnitude controlled the synchronous displacement of a NNE–SSW-striking fault set and a NNW–SSE-striking fault set in orthorhombic pattern to create the characteristic rhomboidal fault geometry. Whereas, the Southern Songliao Basin (SSL) deformed under a 2-D plane strain filed with a horizontal ESE-WNW extension and vertical shortening. The plane strain condition is interpreted as a special case with no intermediated strain(ε2), and produces a pair of near N-S-striking fault sets in conjugate symmetry. Our results illustrate that this particular three-dimensional deformation result in the intricate fault system in the Songliao Basin and that the fault geometry is controlled by the ratios of the principal strains, especially the relative magnitude of the intermediate strain. We argue that the three-dimensional strain field in the NSL reflected the trench retreat in the Paleo-Pacific subduction zone and the gravitational collapse of the thickened lithosphere, and that the extension of the SSL is merely the consequence of the trench retreat.

Keywords:

Songliao Basin, three-dimensional strain, orthorhombic fault, syn-rift deformation, quantitative reconstruction

How to cite: xing, H.: Late Mesozoic rift evolution and deformation reconstruction of the Songliao Basin, northeastern China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6117, https://doi.org/10.5194/egusphere-egu23-6117, 2023.

The stratigraphy of the southern half of Afghanistan has been studied and the timing of first order events have been established in some detail. By contrast, the structural evolution has not been treated with the same discernment. We here report the existence of a marginal fold and thrust belt within the Logar Syncline (western Afghanistan) that was detached along a décollement surface at the base of the Cambrian, mainly between Zargaran dolomites and polymictic conglomerates filling the underlying depressions. The basement consists of Pan-African magmatic and metamorphic rocks including volcanic tuffs making up the Loy Khwar Series. Some of this material has been worked into the conglomerates of the Loy Khwar. The overlying sedimentary package reaches from the Cambrian to the Permian and has been deformed into concentric folds. Nowhere do these folds expose the underlying Pan-African basement which crops out in the extreme SW, in a kind of root zone wherein the décollement separating the sedimentary package from the basement seems to root. Having a décollement within dolomites seems unexpected due to their presumed strength but a similar case has been reported from the Keystone Thrust of the Sevier Belt in Nevada. This phenomenon seems to be more widespread than previously thought.

How to cite: Lom, N. and Şengör, A. M. C.: The discovery of a Palaeozoic décollement in SW Afghanistan: orogenic events along the Tethyan edge of Gondwana-Land, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6614, https://doi.org/10.5194/egusphere-egu23-6614, 2023.

EGU23-7091 | ECS | Orals | GD9.1

Cenozoic Southwestern Tian Shan: Timing of Mountain Building, Intra-montane Basin Inversion, and Relation to Lithospheric Mantle Indentation 

Florian Trilsch, Sanaa Reuter, Ratschbacher Lothar, Shadi Ansari Jafari, Raymond Jonckheere, Birk Härtel, Christoph Glotzbach, and Bastian Wauschkuhn

Cenozoic reactivation of the Paleozoic thick-skinned fold-thrust belt of the southwestern Tian Shan has—as the Afghan-Tajik Basin inversion—been interpreted to reflect Indian mantle-lithosphere indentation underneath the Pamir. New low-temperature thermochronologic data, i.e. apatite fission-track (AFT), apatite (AHe), and zircon (ZHe) (U-Th)/He ages, reveal the exhumation history of the SW-Tajik Tian Shan along two N-S-transects. We date the reactivation and explore its temporal and spatial variations. Three domains emerged. In the Central Domain (Zeravshan-Gissar and Vashan), AFT data—aided by Raman-spectroscopic chemical-composition discrimination of detrital apatite samples and vitrinite-reflectance temperature estimates—record a ~10-13 Ma onset of shortening and >4 km exhumation. The Northern Domain, where the N-Zeravshan Fault constitutes a major Cenozoic structural divide reactivating the Paleozoic Zirabulak Suture, exhumed from <4 km, but apatite AHe ages outline a similar reactivation history as in the Central Domain. The synchronous structural reactivation implies rapid shortening propagation from the Pamir indenter across the Afghan-Tajik fold-thrust belt into and across the Tian Shan. In the Southern Domain (Gissar Batholith), ~7‒9 Ma AFT and ~4 Ma AHe ages suggest a southward shortening propagation from the northern Domains and anew thrust generation. In the hanging wall of major thrusts, ~3‒7 Ma-old AFT ages record significant and persistent exhumation but ZHe data limit it to <6 km. Most of the Southern and Central Domains cooled monotonously but temperature-time models indicate northward-decreasing reheating by syn-orogenic deposition, consistent with stratigraphic data.

How to cite: Trilsch, F., Reuter, S., Lothar, R., Ansari Jafari, S., Jonckheere, R., Härtel, B., Glotzbach, C., and Wauschkuhn, B.: Cenozoic Southwestern Tian Shan: Timing of Mountain Building, Intra-montane Basin Inversion, and Relation to Lithospheric Mantle Indentation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7091, https://doi.org/10.5194/egusphere-egu23-7091, 2023.

EGU23-7378 | ECS | Posters on site | GD9.1

Towards understanding the crustal response of slab tearing and detachment: inferences from the Dinarides-Hellenides transition 

Nikola Randjelovic, Liviu Matenco, Maja Maleš, Nemanja Krstekanic, Uros Stojadinovic, Branislav Trivić, and Marinko Toljić

Convergence zones are often characterized by numerous subduction- to collision-related dynamics in many orogenic areas worldwide. Processes such as continental indentation, extrusion and slab roll-back can occur simultaneously along orogens as a consequence of different rates of convergence. Such along-strike variability accross the orogen can lead to migration of deformation from partly detached slab to the still active oceanic or continental subduction. These conditions create slab tearing often followed by rotation, rapid roll-back of the attached slab and/or exhumation of previously buried crust in the upper plate above the already detached slab. The main mechanism that explains transition from slabs with contrasting kinematics to the crustal level strain partitioning is still not fully understood.

One very good example of strain partitioning associated with indentation, slab-detachment and slab-tearing is the junction between the Dinarides and Hellenides in southeastern Europe. Following the Jurassic – Eocene closure of the Neotethys Ocean and subsequent Adria – Europe collision, the Dinarides - Hellenides orogen has recorded a significant extensional deformation. This extension was driven by the Oligocene – early Miocene slab detachment of the Dinarides slab, while the Hellenides segment continued its evolution until the present day.

We have performed a field kinematic and structural study in the less understood area of Montenegro near Dinarides - Hellenides transition to determine the influence of Oligocene – early Miocene deformation on Dinarides composite nappes. The results imply that Oligocene – early Miocene slab detachment followed by slab tearing was accommodated in crustal domain by bi-directional extension associated with the exhumation of mid-crustal levels in the footwall of both orogen-parallel and orogen-perpendicular faults, reactivation of inherited Cretaceous-Paleogene nappe contacts and formation of extensional klippen.

How to cite: Randjelovic, N., Matenco, L., Maleš, M., Krstekanic, N., Stojadinovic, U., Trivić, B., and Toljić, M.: Towards understanding the crustal response of slab tearing and detachment: inferences from the Dinarides-Hellenides transition, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7378, https://doi.org/10.5194/egusphere-egu23-7378, 2023.

EGU23-7625 | Orals | GD9.1

Sinking-slab triggered formation of the giant Ordos basin in central China 

Neng Wan, Shaofeng Liu, and Zhang Bo

The giant Late Triassic Ordos basin, developed along northern Tethyan margin where prolonged terrane amalgamation and accretion occurred, is characterized by rapid subsidence rate along its southwestern margin, but slow and uniform subsidence rate within its interior. Its formation mechanism still remains poorly understood. Here, we use flexural simulation and 4D-geodynamic modeling to explore the potential role of basin adjacent mountain belts and deep mantle processes towards basin subsidence, respectively. Flexural backstripping of stratigraphic record spanning from 245-201 Ma, along two SW-NE trending well sections perpendicular to the southwestern margin of Ordos basin clearly demonstrates that there were long wavelength anomalous subsidence components, here termed residual subsidence, in addition to those induced by thrust loads and sediment loads. From 245-201 Ma, residual subsidence increases from 0 m to ca. 500 m and gradually decreases from southwest towards northeast. Our results indicate that basin adjacent thrust loads could act as the dominant driver for subsidence of foredeep but have limited control towards basin interior. Other mechanism is required to explain the basin-wide anomalous residual subsidence. Long-wavelength nature of residual subsidence and its general agreement, regarding both the magnitude and trend, with dynamic topography predicted by an independently designed geodynamic model suggest that the anomalous subsidence component might be of dynamic origin. We attribute this excess residual subsidence as dynamic subsidence induced by the sinking slab beneath North China plate during and after the oblique closure of Mianlue ocean between North China plate and South China plate. We argue that the Ordos basin is triggered by subduction related mantle processes while modulated by flexural loading along its margin. Our findings may also shed light on formation mechanisms of other giant basins with similar settings in East Asia.

How to cite: Wan, N., Liu, S., and Bo, Z.: Sinking-slab triggered formation of the giant Ordos basin in central China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7625, https://doi.org/10.5194/egusphere-egu23-7625, 2023.

Since Late Palaeozoic, the North China Block (NCB) experienced a unique tectonic process in which sequential plate subduction and collision took place around this once stable and rigid craton. Due to this multi-direction convergent setting and its small size, the NCB was characterized with intensive intracontinental deformation and associated depositional processes and magmatism during Mesozoic. However, conflicting debates on the timing and kinematics of the intracontinental deformations are still open to the geologist community and hamper the understanding of the driving forces. Our works focus on the syn-tectonic depositions, including syn-tectonic conglomerates and growth strata, in Mesozoic sedimentary basins in the Yanshan belt of northern NCB, and the high-precision zircon U-Pb geochronological data. Previously reported stratigraphic levels of regional unconformities and isotopic ages of igneous rocks in the Yanshan belt were also compiled in this study. Our results suggest that during Middle Triassic-earliest Jurassic (ca. 240-195 Ma), the northern NCB was dominated by nearly N-S compressional regime, leading to formation of large-scale E-W-trending thrust faults and basement-cored buckles. A significant magmatic lull was also witnessed within this period (ca. 210-195 Ma). This N-S crustal shortening was believed to be related with collision between the NCB and the Songliao-Nenjiang terrane along the Solonker suture. During Middle Jurassic-Early Cretaceous (ca. 172-135 Ma), the Yanshan belt underwent strong NW-SE contraction and gave rise to NE-SW-striking thrust faults, asymmetric folds, and reactivation of previous E-W thrust faults with prominent dextral component. Both deformation, deposition, and magmatism showed a westward younging trend in the Yanshan belt during Early Jurassic-Early Cretaceous (ca. 180-140 Ma), indicating their westward migration. However, magmatism turned to migrate toward east after that. All these lines of evidences could be integrated in a tectonic model with westward flat-slab subduction of the Paleo-Pacific/Izanagi plate beneath the East Asian continent. Early Jurassic witnessed an imported and profound transition from closure of the paleo-Asian Ocean to the subduction of the Paleo-Pacific Ocean plate.

How to cite: Lin, C. and Liu, S.: Mesozoic intracontinental deformations of the northern North China Block in a multi-direction convergent setting, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7701, https://doi.org/10.5194/egusphere-egu23-7701, 2023.

EGU23-7851 | ECS | Orals | GD9.1

Devonian Andean-type orogeny in the southern Dunhuang block (NW China): Petro-structural, geochronological and metamorphic P−T constraints 

Jérémie Soldner, Yingde Jiang, Pavla Štípská, Karel Schulmann, Chao Yuan, Zongying Huang, and Robert Anczkiewicz

The Dunhuang block in NW China preserves Archean to Paleoproterozoic basement rocks that are exposed alongside Paleozoic magmatic and metamorphic rocks. Although both subduction-accretion and collisional processes have been proposed for the formation of Paleozoic metamorphic rocks, links between their metamorphic ages, P−T evolution and deformational history remains ambiguous. Here we present zircon and in-situ monazite U−Pb geochronology linked to P−T modelling of metapelites from the Hongliuxia belt in the southern Dunhuang block. Oriented inclusion trails in garnet from metapelites reveal rare relics of an S1 fabric. The earliest continuous metamorphic fabric is an originally steep N-S striking foliation S2. This fabric was further reworked by upright folds F3 associated with development of an ubiquitous steep, mainly south-dipping, E-W striking axial planar foliation S3. The Bt−Ms−St−Pl−Qz−Tur−Ilm assemblage forming inclusions in garnet is assigned as the D1-M1a event whereas the foliation S1b in metapelites is associated with Grt–Ky–St–Bt–Ms–Pl–Qz–Rt assemblage. The Grt−Ky−St aligned parallel to the S2 matrix in low-strain domains are considered as remnants of a dismembered M1 assemblage, while the S2 foliation is characterized by the Grt–Sil–Bt–Pl–Qz–Rt–Liq in high-strain domains. The S3 foliation is associated with the Grt–Sil–Bt–Ms–Pl–Qz–Kfs–Chl–Ilm assemblage. Altogether, metapelites record similar clockwise P–T evolution an early prograde (M1a) stage starting at 4.5–5 kbar and 500–550°C, metamorphic peak (M1b) stage at ~8 kbar and 700–725°C, decompressional heating to ~6 kbar and ~750°C (M2) and a retrograde stage to 4.5–5.5 kbar and 500–550°C (M3). Zircon U−Pb geochronological investigations suggest that metapelites from the basement record metamorphic ages of 1847 ± 11 Ma and 404 ± 15 Ma.  In-situ U–Pb dating of monazite combined to monazite trace-element composition analysis further suggest that the rock burial most likely started at c. 410 Ma, peak-P conditions M1b were reached at 400–395 Ma, M2 heating occurred at c. 390 Ma and M3 retrogression occurred between c. 384 and 353 Ma. The D1-M1 burial event reflects either underthrusting of the basement below the supra-subduction active margin system or propagation of the deformation front to the south of the Dunhuang block. The D2-M2 event is a consequence of thermal relaxation following crustal thickening, possibly accompanied by convective lithospheric thinning, whereas D3-M3 reflects exhumation during shortening of the system. Combined with the available regional data, it is suggested that the Devonian multi-stage tectono-metamorphic evolution described in the study area corresponds to a polyphase Andean-type deformation of the active margin of the Dunhuang block. Such a process can be regarded as a response to a progressive relocation of the Dunhuang block alongside with the Tarim-North China Collage in the Devonian.

 

Funding: This research is part of the project No. 2021/43/P/ST10/02996 co-funded by the National Science Centre and the European Union Framework Program for Research and Innovation Horizon 2020 under the Marie Skłodowska-Curie grant agreement No. 945339, as well as the President’s International Fellowship Initiative for Postdoctoral Researchers of the Chinese Academy of Sciences, grant No. 2021PC0013.

How to cite: Soldner, J., Jiang, Y., Štípská, P., Schulmann, K., Yuan, C., Huang, Z., and Anczkiewicz, R.: Devonian Andean-type orogeny in the southern Dunhuang block (NW China): Petro-structural, geochronological and metamorphic P−T constraints, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7851, https://doi.org/10.5194/egusphere-egu23-7851, 2023.

EGU23-8253 | ECS | Posters on site | GD9.1

Seismic imaging of the lithospheric structures in the Iranian Makran subduction zone 

Zimu Wu, Ling Chen, Haiqiang Lan, Morteza Talebian, Xu Wang, Yifan Gao, Jianyong Zhang, Yinshuang Ai, Mingming Jiang, and Yingjie Yang

The Makran subduction zone (MSZ) is located in between the Zagros mountain belt to the west and Himalayan orogen to the east, forming a transition from oceanic subduction to continental collision on both sides along the Tethyan orogenic belt. The Arabian oceanic plate, a narrow remnant of the Neotethys ocean, is subducting northward beneath the Eurasian plate in Makran. Such a unique tectonic setting makes the MSZ an ideal place to investigate the geodynamic processes in response to subduction-collision transition. Since most of the Neotethys has already dived into the deep mantle and the associated geological records are not always well preserved due to the strong collision, the MSZ also provides a special opportunity to explore the evolution history of the Neotethys in a more direct way.

To better understand the deep dynamics of the subduction-collision transition and evolution of the Neotethys, we investigated the lithospheric structure, especially the depth variation of the lithosphere-asthenosphere boundary (LAB), across the Iranian MSZ by S-wave receiver function (SRF) imaging. The teleseismic data used were acquired from 67 broadband stations that were operational from March 2017 to September 2018 in southeastern Iran. This temporary array constitutes the third phase of seismic observations under the “China-Iran Geological and Geophysical Survey in the Iranian Plateau” project.

Our SRF migration images show clear structural variations of both the upper and lower plates in the MSZ. In the upper plate in the southeastern Iranian plateau, we image a thin lithosphere (70-90 km) with monotonic decrease in LAB depth from the plateau interior to the arc region. This arc-ward thinning is probably caused by the focused thermal and chemical erosion at the LAB by arc magmatism. The LAB of the subducting slab is imaged at ~110-90 km depth near the coast but with an unexpected ~20-km deepening along the trench-parallel direction. Assuming a 25-km-thick accretionary wedge (deduced from active-source data), the observed ~85-65-km-thick slab is consistent with the thermal predictions for a mature oceanic lithosphere. However, the trench-parallel LAB step can hardly be explained by the age difference of the Neotethys but may be a result of the Cretaceous plate-mantle plume interaction. The plume-modified slab could be characterized by low density and high viscosity, and thus play an important role in forming low-angle (<10°) subduction beneath the present-day Makran fore-arc region. Our results also suggest that the thin overriding lithosphere is a persistent feature in both the MSZ and the neighboring continental collision/subduction zone, which favors the idea that the vertical-axis rotation and possible convective thinning dominate the evolution of central-east Iranian microblocks during the late Cenozoic. In addition, we detect an east-dipping structure at 70-90 km depth beneath the Zagros-Makran border, perhaps indicating a relatively sharp contact relationship between the oceanic and continental portions of the Arabian plate. These new observations imply a much more complex tectonic evolution than previously envisaged in the MSZ and adjacent subduction-collision transitional area, which deserves future studies to understand the continuous process from Neotethys subduction to continental collision.

 

How to cite: Wu, Z., Chen, L., Lan, H., Talebian, M., Wang, X., Gao, Y., Zhang, J., Ai, Y., Jiang, M., and Yang, Y.: Seismic imaging of the lithospheric structures in the Iranian Makran subduction zone, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8253, https://doi.org/10.5194/egusphere-egu23-8253, 2023.

EGU23-8755 | ECS | Posters virtual | GD9.1

Crustal Deformation of Biga Peninsula and Structural Controls on Porphyry Cu-Au and Epitermal Au Mineralization in Kirazlı Gold Deposit (Türkiye) 

Mehmet Çam, İlkay Kuşcu, Nuretdin Kaymakcı, and Mehtap Karcı

Kirazlı porphyry Cu-Au and epitermal Au mineralization is located in Biga peninsula where the region hosts numerious porphyry- and epithermal- style Au mineralizations within the Tethyan orogenic belt. Crustal deformation in the region is resulted by Cretaceous collusion during the closure of northern branch of Neotethys Ocean, related subduction, post-collusion, Cenozoic extension and following dextral strike-slip deformation regime which is emerged during the westward migration of Anatolian plate. The study includes regional fault mapping, slip data collection from regonal and district scale faults for paleostress analysis, oriented surface sampling of vein hosted deformational zones and micro-structural thin section examinations of oriented samples. Paleostress findings and fault orientations indicates two seperate character of deformations as nearly E-W trending extensional fault systems and subsequent NE-SW striking, steeply dipping dextral strike-slip faults with accompanying NNW-SSE trending left-lateral strike slip and ENE-WSW trending dextral strike-slip and oblique-slip faults. Later tectonic phase related with N-E Dextral strike-slip faults establishes the main deformational trend with accompanying district scale  R (synthetic) ENE-WSW trending dextral and NNW-SSE trending R' (antithetic) sinistral strike-slip faults. Slip data related to  E-W and ENE-WSW faults indicate that these faults are subjected to both N-S trending extensional and NE-SW trending dextral strike-slip tectonic regime. The petrographic and textural studies of oriented thin sections resulted in identification of two predominant vein directions as ENE-WSW and NNW-SSE of porphyry mineralization within the project area. ENE-WSW trending syntaxial, streched-blocky quartz bearing veins indicates multiple N-S extension and crack-seal events and postdated by NNW-SSE trending quartz veins. Also the veins with same orientation which were observed during field studies share similar orientations.

This study presents the early results off Ph.D. thesis "Crustal Extension and its Relationship to Porphyry Cu-Au and Epithermal Au Mineralization in the Kirazlı Gold Deposit (Çan, Çanakkale, Türkiye)" and supported by Alamos Gold Inc..

How to cite: Çam, M., Kuşcu, İ., Kaymakcı, N., and Karcı, M.: Crustal Deformation of Biga Peninsula and Structural Controls on Porphyry Cu-Au and Epitermal Au Mineralization in Kirazlı Gold Deposit (Türkiye), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8755, https://doi.org/10.5194/egusphere-egu23-8755, 2023.

EGU23-9971 | Orals | GD9.1 | Highlight

The Pacific basal mantle structure could be older than the African one 

Nicolas Flament, Omer Bodur, Simon Williams, Andrew Merdith, Dietmar Muller, John Cannon, Michael Tetley, Xianzhi Cao, and Sabin Zahirovic

Plate tectonics shapes Earth’s surface and is linked to motions within its deep interior. Cold oceanic lithosphere sinks into the mantle, and hot mantle plumes rise from the deep Earth, leading to volcanism. Volcanic eruptions over the past 320 million years have been linked to two large structures at the base of the mantle presently under Africa and the Pacific Ocean. This has led to the hypothesis that these basal mantle structures could have been stationary over geological time, in contrast to observations and models suggesting that tectonic plates, subduction zones, and mantle plumes have been mobile and that basal mantle structures are presently deforming. Here we reconstruct mantle flow from one billion years ago to the present day to show that the history of volcanism is statistically as consistent with mobile basal mantle structures as with fixed ones. In our reconstructions, cold lithosphere sank deep into the African hemisphere between 740 and 500 million years ago, and from 400 million years ago the structure beneath Africa progressively assembled, pushed by peri-Gondwana slabs, to become a coherent structure as recently as 60 million years ago. In contrast, the structure beneath the Pacific Ocean was established between 400 and 200 million years ago. These results confirm the link between basal mantle structures and surface volcanism, and they suggest that basal mantle structures are mobile, and aggregate and disperse over time, similarly to continents at Earth’s surface. This implies that the present-day shape and location of basal mantle structures may not be a suitable reference frame for the motion of tectonic plates.

How to cite: Flament, N., Bodur, O., Williams, S., Merdith, A., Muller, D., Cannon, J., Tetley, M., Cao, X., and Zahirovic, S.: The Pacific basal mantle structure could be older than the African one, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9971, https://doi.org/10.5194/egusphere-egu23-9971, 2023.

The plate tectonic history of the Pacific Ocean and its predecessor ocean, Panthalassa, are challenging regions on Earth to reconstruct during the Mesozoic-Cenozoic eras. More than 95% of Pacific-Panthalassa crust has been subducted into the Earth’s interior since the Jurassic, and this has created extensive (>9000 km length) plate reconstruction gaps between the Pacific and Eurasia/Laurasia. Here we build four contrasted NW Pacific-Panthalassa global plate reconstructions and assimilate their velocity fields into the global geodynamic models using the code TERRA: Andean-style subduction along East Asia following the corrected ‘R’ Matthews et al. (2016); and, three models that include intra-oceanic subduction within Pacific-Panthalassa with increasing tectonic complexity.   We compare our predicted present mantle structure, synthetic geoid and dynamic topography to Earth observations. P-wave tomographic filtering of predicted mantle structures allows for more explicit comparisons to global tomography.

All three plate reconstructions that include NW Pacific-Panthalassa intra-oceanic subduction fit better to the observed long-wavelength geoid and residual topography.  Correlations between modeled and imaged mantle structure do not systematically favor any single model, and this is attributed to limited tomographic resolution within the central Pacific mantle relative to variability in our modeled mantle structures.  Taken together, our results robustly show the likelihood of intra-oceanic subduction within NW Pacific-Panthalassa.  This presents a challenge to popular plate models of Andean-style subduction along East Asia, which are deeply-embedded into most published plate tectonic, geodynamic and geologic studies.  Our geodynamic models predict significant (>2000 km from Mesozoic to present) southeastwards lateral slab advections within the lower mantle that would confound ‘vertical slab sinking’-style restorations of ancient subduction zones.  Plate reconstructions that can better incorporate intra-oceanic subduction within Pacific-Panthalassa may improve our knowledge of past global CO2, mantle flow, and dynamic topography histories.

How to cite: Wu, J., Lin, Y.-A., and Colli, L.: NW Pacific-Panthalassa intra-oceanic subduction during Mesozoic-Cenozoic times from mantle convection and geoid models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10007, https://doi.org/10.5194/egusphere-egu23-10007, 2023.

EGU23-10233 | ECS | Orals | GD9.1 | Highlight

Strong variability in the thermal structure of Tibetan Lithosphere 

Bing Xia, Irina Artemieva, Hans Thybo, and Simon Klemperer

We present a model of thermal lithospheric thickness (the depth where the geotherm reaches a temperature of 1300°C) and surface heat flow in Tibet and adjacent regions based on the new thermal-isostasy method. The method accounts for crustal density heterogeneity, is free from any assumption of a steady-state lithosphere thermal regime, and assumes that deviations from crustal Airy-type isostasy are caused by lithosphere thermal heterogeneity. We observe a highly variable lithospheric thermal structure which we interpret as representing longitudinal variations in the northern extent of the subducting Indian plate, southward subduction of the Asian plate beneath central Tibet, and possible preservation of fragmented Tethyan paleo-slabs. Cratonic-type cold and thick lithosphere (200-240 km) with a predicted surface heat flow of 40-50 mW/m2 typifies the Tarim Craton, the northwest Yangtze Craton, and most of the Lhasa Block that is likely refrigerated by underthrusting Indian lithosphere. We identify a ‘North Tibet anomaly’ with thin (<80 km) lithosphere and high surface heat flow (>80-100 mW/m2). We interpret this anomaly as the result of removal of lithospheric mantle and asthenospheric upwelling at the junction of the Indian and Asian slabs with opposite subduction polarities. Other parts of Tibet typically have intermediate lithosphere thickness of 120-160 km and a surface heat flow of 45-60 mW/m2, with patchy anomalies in eastern Tibet. While different uplift mechanisms for Tibet predict different lithospheric thermal regimes, our results in terms of a highly variable thermal structure beneath Tibet suggest that topographic uplift is caused by an interplay of several mechanisms.

How to cite: Xia, B., Artemieva, I., Thybo, H., and Klemperer, S.: Strong variability in the thermal structure of Tibetan Lithosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10233, https://doi.org/10.5194/egusphere-egu23-10233, 2023.

A range of interpretations of regional geology have led to diverging models describing the elusive predecessor marginal basin to the South China Sea, with significant implications for interpreting regional extrusion tectonics and volcanic episodes. Interpretations contrast between the presence or absence of the Proto South China Sea, while models arguing for a Proto South China Sea also diverge in the geodynamic origin of the marginal sea as either 1) a trapped piece of Cretaceous-age proto Pacific (namely, Izanagi) crust, or 2) sourced from back-arc opening along the east Asian margin.

I will provide a comparison of proposed models for the Proto South China Sea, and I will argue that the existence of a Proto South China Sea, including in the region north of Borneo, is a necessity for reconciling multiple and independent geological and geophysical constraints. First, a back-arc basin along east Asia in the Late Cretaceous helps explain tectonic subsidence curves, the presence of Late Cretaceous ophiolites on Mindoro, and also the abandonment of Andean-style arc volcanism on the South China continental margin. Second, regional basin histories and even the tectonic structure of Luzon Island and northwest Borneo suggest continental or arc fragments from east Asia were accreted in both settings. And finally, the ~50 to 20 Ma subduction-related volcanic history on Borneo, the presence of mapped sutures, evidence of subducted slabs in seismic tomography, requires significant south-dipping subduction of a Proto South China Sea. However, interpretations of a number of features, including the Billiton Depression, the Bentong-Raub Suture, and the West Baram Line on Borneo, and the origin of the Natuna Islands granites continue to provoke continued divergence in models for the region.

I will present an updated plate tectonic reconstruction in GPlates that incorporates recent spatial and temporal constraints, such as the west-east division of Luzon island (South China and Pacific affinity, respectively), and the timing of Proto South China Sea back-arc opening, closure, and accretion events. To test the new model, I show that the model conforms to plate kinematic constraints (such as reasonable convergence rates, and associated arc volcanism). In addition, I present new forward models of mantle flow in CitcomS, and compare the predictions to high-resolution P-wave tomography models (e.g. MIT-P08, UU-P07).

Although more geochronological and geochemical constraints are needed to establish the nature and age of the sutures on northwest Borneo, a clearer tectonic model for this area is essential in guiding mineral exploration – as established models have proposed there has been no subduction in this region since ~100 Ma. The new model presented here argues that subduction ceased much more recently, likely by ~20-15 Ma, coinciding with the arrival of the Dangerous Grounds block in the northern Borneo Trough, choking subduction, triggering the Sabah Orogeny, the eruption of Sintang-area adakites (related to slab break-off), and the abandonment of seafloor spreading in the South China Sea at ~15 Ma. Reconciling these interpretations will improve our understanding of paleogeography, basin evolution, sedimentary provenance, and regional geodynamics.

How to cite: Zahirovic, S.: The geological, tectonic, and geodynamic fingerprint of the elusive Proto South China Sea back-arc basin in northern Borneo, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10720, https://doi.org/10.5194/egusphere-egu23-10720, 2023.

EGU23-10968 | ECS | Orals | GD9.1

Sedimentary Basins of Kazakhstan and Occurrence of Copper and Uranium: A Geological Overview and Tectonic Analysis 

Azam Soltani Dehnavi, Reimar Seltmann, and Fereshteh Shabani

 

Several sedimentary basins (out of 15 basins) in Kazakhstan are characterized by the association of sandstone-type uranium and sedimentary-hosted copper mineralization with oil, gas or coal fields. In central Kazakhstan, the Chu-Sarysu basin (along with Syr-Darya basin), both hosting a multicolored clay–gravel–sandstone sequence, are famous for roll-front type uranium deposits. The Chu-Sarysu basin is also the host of the world-class historical giant deposit of Dzhezkazgan (22 million metric tons) sandstone-hosted copper (by-product of rhenium) as well as smaller deposits of Zhaman-Aibat and the Zhilandy group. The Teniz depression, located in the northern Chu-Sarysu basin, is also prospective for the occurrence of sedimentary copper. Both basins share lithological and structural peculiarities significant to mineralization. The Teniz and Chu-Sarysu basins originated during the development of the Altaid Orogen (Wilhelm, et al., 2012). The Chu-Sarysu and Teniz basins are characterized by a continental-marine-continental depositional cycle from Devonian to Permian. The base of basins includes Early to Middle Devonian intermediate volcanic and volcanoclastic rocks grading upward into Late Devonian red beds (Box et al., 2012; Cossette et al., 2014). The Early Carboniferous is marked by the deposition of lagoonal to marginal-marine salt-bearing strata, which is overlain by Late Carboniferous to Permian alluvial-lacustrine red beds, and a shale-limestone sequence. Both Chu-Sarysu and Teniz basins endured the folding of rocks in the Permian, generating dome-and-basin forms. Both basins are marked by parallel strike-slip lineaments likely related to Permian Kazakhstan oroclinal bending, resulting in a back-arc/rift-graben development. The localization of most of the Cu deposits at the Chu-Sarysu basin is adjacent to the intersection of F2 anticlines (N-NW-trending) with the syn-depositional folding F1 anticlines (E-NE-trending) within the zones of sandstone bleaching. The F1 anticlines locally trapped petroleum fluid deposits. These structures are the pathway of the flow of dense ore brines across the petroleum-bearing anticlines, resulting in ore sulfide deposition via two fluids mixed. Satellite images display the same structural pattern in the Teniz basin, which can assist to narrow down the prospecting regions for copper occurrences. Since the sedimentary-hosted copper systems are complicated in terms of the mineralization events, the comparison of the two basins enables to generate valuable information related to depositional patterns and to guide exploration. Also, non-genetic special relationship between uranium and copper can be postulated.

 

References

Box, S. E., Syusyura, B., Seltmann, R., Creaser, R. A., Dolgopolova, A., & Zientek, M. L., 2012, Dzhezkazgan and associated sandstone copper deposits of the Chu-Sarysu Basin, Central Kazakhstan. Econ. Geol. Sp. Publ, 16, p. 303-328.

 

Cossette, P.M., Bookstrom, A.A., Hayes, T.S., Robinson, G.R., Jr., Wallis, J.C., and Zientek, M.L., 2014, Sandstone copper assessment of the Teniz Basin, Kazakhstan: U.S. Geological Survey Scientific Investigations Report 2010–5090–R, 42 p.

 

Wilhem, Caroline, Windley, B.F., and Stampfli, G.M., 2012, The Altaids of Central Asia—A tectonic and evolutionary innovative review: Earth-Science Reviews, v. 113, p. 303– 341.

How to cite: Soltani Dehnavi, A., Seltmann, R., and Shabani, F.: Sedimentary Basins of Kazakhstan and Occurrence of Copper and Uranium: A Geological Overview and Tectonic Analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10968, https://doi.org/10.5194/egusphere-egu23-10968, 2023.

EGU23-11327 | ECS | Orals | GD9.1

Paleoelevation Reconstruction of Subduction Zones in Eastern Pacific Continental Margins Quantitatively with Igneous Geochemistry 

Bingxi Liu, Simon Williams, Guochun Zhao, Shan Yu, and Dongchuan Jian

Reconstructing past episodes of mountain building from the geological rock record is one of the main challenges for unravelling the ancient physical geography of Earth’s surface. Mountains and mountain ranges, often situated at convergent plate margins, play a pivotal role in many fields of the Earth, climate, and biological sciences. Established methods for quantifying past elevations traditionally relied on sedimentary rocks, but in recent years, alternative approaches have emerged on the basis that geochemical signatures of magmatic rocks formed in convergent settings correlate with crustal thickness or elevation. These correlations allow for empirical relations of igneous whole-rock ratios such as La/Yb and Sr/Y with Moho depth for modern convergent settings, which can then be used to estimate ancient crustal thickness or paleoelevation. Since a relatively large number of igneous samples are available for pre-Cenozoic times compared to other paleoelevation proxies, these methods have the potential to allow quantitative mapping of past topographic change for times where existing maps are largely based on a qualitative approach.

Here, we investigate the application of paleoelevation estimates derived from geochemistry using the Pacific margin of South America as a case study. We investigate their consistency with independent indicators of past elevations such as stratigraphy, stable isotopes, fossils etc. for Cenozoic samples along the Andean margin. For older times, we compare the estimated paleoelevations with other aspects of the geological record, as well as equivalent values from global paleogeography models widely used in climate modelling studies, to evaluate the extent to which these models are consistent with the igneous geochemical proxies. We derive paleoelevation estimates according to different data filtering schemes, showing that a major consequence of the choice of geochemistry filter is the number of data points left after the filtering. We find that the igneous geochemical proxies yield elevations broadly consistent with traditional results for the Cenozoic, though our results do not resolve some of the rapid uplifts recorded by other proxies. In deeper time, we show that igneous geochemistry quantifies changes in elevation related to documented phases of crustal thickening and thinning, and is thus likely to allow improvements to existing maps of paleotopography. 

How to cite: Liu, B., Williams, S., Zhao, G., Yu, S., and Jian, D.: Paleoelevation Reconstruction of Subduction Zones in Eastern Pacific Continental Margins Quantitatively with Igneous Geochemistry, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11327, https://doi.org/10.5194/egusphere-egu23-11327, 2023.

EGU23-12290 | Orals | GD9.1

Lithium pegmatites of the Kalba-Narym Belt, East Kazakhstan: Geological overview 

Gleb Smirnov, Reimar Seltmann, and Azam Soltani Dehnavi

The Kalba-Narym Belt is part of the Central Asian Orogenic Belt (CAOB) and formed due to the
continental collision between Kazakhstan and Siberian plates in the Late Paleozoic. Several
plutons comprising the Kalba-Narym granitic batholith are considered post-orogenic. The
commonly accepted theory claims that these intrusive bodies might have been formed due to
the far-spreading influence of the Tarim mantle plume (Khromykh et al., 2019). However, the
volcanic facies, that are normally associated with plume-related activities are present only
sporadically in the Kalba-Narym area, which may imply that the heat source is plume-unrelated
and instead linked to mafic underplating and uplift processes of the crust. Amongst the variable
intrusive rocks formed in this region, highly-fractionated pegmatites are particularly important
but nevertheless remain poorly understood with origin controversially discussed. The
mineralized pegmatites are associated with Phase 1 granites of the Kalba complex, with a
40Ar/ 39Ar age of 297 to 290 Ma (Kotler et al., 2021). The formation of pegmatites, driven either
by the differentiation of granitic melts or by anatectic melting processes, was likely
supplemented by the inputs of volatiles and rare metals with fluids. The rocks of the best-
known pegmatite occurrences located near Asubulak village, such as Yubileynoye and Krasny
Kordon deposits, can be categorized as LCT pegmatites, including three main zones based on
mineralogical and geochemical assemblages of a) microcline-albite with pollucite and petalite
(Ta, Cs, Be, Sn), b) microcline-albite with spodumene (Ta, Nb, Cs, Li, Be, Sn), and c) spodumene-
albite (Li, Ta, Nb, Sn) (D'yachkov et al., 2021).
Apart from the mineralized pegmatites, there are known occurrences of barren pegmatites,
which creates an opportunity for comparison with the mineralized pegmatites specifically via
contrasting geochemical signatures. Aiming at a proper understanding of the pegmatite
genesis, mineralization mechanisms and geochemical approach on a bigger regional scale of the
Greater Altai may open up unique perspectives for the future exploration of the region.
Therefore, this presentation provides an overview and re-evaluation of the detailed geological
characteristics of the Kalba-Narym Belt, continuous into Chinese Altai, and the processes
involved in rare-metal pegmatite mineralization.

References:
D'yachkov, B. A., Bissatova, A. Y., Mizernaya, M. A., Zimanovskaya, N. A., Oitseva, T. A.,
Amralinova, B. B., Aitbayeva, S. S., Kuzmina, O. N., &amp; Orazbekova, G. B. (2021). Specific
Features of Geotectonic Development and Ore Potential in Southern Altai (Eastern
Kazakhstan). Geology of Ore Deposits, 63(5), 383–408.
https://doi.org/10.1134/s1075701521050020


Khromykh, S. V., Oitseva, T. A., Kotler, P. D., D’yachkov, B. A., Smirnov, S. Z., Travin, A. V.,
Vladimirov, A. G., Sokolova, E. N., Kuzmina, O. N., Mizernaya, M. A., &amp; Agaliyeva, B. B.
(2020). Rare-metal Pegmatite Deposits of the Kalba Region, Eastern Kazakhstan: Age,
Composition and Petrogenetic Implications. Minerals, 10(11), 1017.
https://doi.org/10.3390/min10111017

Kotler, P., Khromykh, S., Kruk, N., Sun, M., Li, P., Khubanov, V., Semenova, D., &amp; Vladimirov, A.
(2021). Granitoids of the Kalba Batholith, Eastern Kazakhstan: U–PB Zircon Age,
Petrogenesis and Tectonic Implications. Lithos, 388-389, 106056.
https://doi.org/10.1016/j.lithos.2021.106056

How to cite: Smirnov, G., Seltmann, R., and Soltani Dehnavi, A.: Lithium pegmatites of the Kalba-Narym Belt, East Kazakhstan: Geological overview, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12290, https://doi.org/10.5194/egusphere-egu23-12290, 2023.

EGU23-12729 | ECS | Orals | GD9.1

Detection and (re)location of earthquakes using Jammu And Kashmir Seismological NETwork 

Sk Shamim, Ayon Ghosh, Supriyo Mitra, Keith Priestley, and Sunil Kumar Wanchoo

Broadband waveform data from the recently established Jammu And Kashmir Seismological NETwork (JAKSNET) has been used to detect and locate earthquakes in the Jammu and Kashmir (J&K) Himalaya. Continuous data recorded by the network between 2015 and 2018 has been used for the analysis. The Coalescence Microseismic Mapping (CMM) algorithm is used to detect and locate hundreds of earthquakes, not reported in regional and global catalogs. These earthquakes are then relocated using a probabilistic relocation method of NonLinLoc (NLL). This produced a subset of earthquakes within 200 km of the network and having spatial uncertainty of less than 10 km. Most of the earthquakes are located beneath the Lesser and Higher Himalaya, with depth less than 25 km. A few earthquakes have depths between 30-60 km and lie across the entire region. The shallow earthquakes occur within the Himalayan wedge and define the locked-to-creep transition (unlocking) zone on the Main Himalayan Thrust. These earthquakes occur in clusters in the Jammu-Kishtwar segment, immediately south of the Kishtwar window, beneath the Kashmir Valley and in the NW Syntaxis, surrounding the 2005 (Mw 7.6) Kashmir earthquake source zone. These events provide the first evidence of the MHT locked segment beneath J&K Himalaya. The deeper events are within the underthrusting Indian crust, which reveal that the entire Indian crust is seismogenic. Double-difference algorithm is being used to improve the relative location of the shallow events to study possible clustering of earthquakes in the MHT.  

How to cite: Shamim, S., Ghosh, A., Mitra, S., Priestley, K., and Wanchoo, S. K.: Detection and (re)location of earthquakes using Jammu And Kashmir Seismological NETwork, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12729, https://doi.org/10.5194/egusphere-egu23-12729, 2023.

EGU23-13519 | ECS | Posters on site | GD9.1

Effects of strain- vs. strain-rate-dependent faults weakening for continental corner collision: insight from 3D thermomechanical models 

Luuk van Agtmaal, Attila Balazs, Dave May, and Taras Gerya

Geological and geophysical observations have highlighted the multi-stage deformation history of the continental lithosphere. Such inherited heterogeneities, observed from microscopic to kilometre-scales, lead to important mechanical weakening for the subsequent development of orogens. This strain-weakening may be frictional (fault gauge, filled veins), ductile (banding, recrystallisation, etc) or caused by changes in grain-size, and largely determines the response of the lithosphere to stresses (Bercovici & Ricard, 2014). Representing the microstructural weakening mechanisms with the relatively low resolution of regional and global numerical modelling studies has been a longstanding challenge. Mechanisms are often grouped into an “effective” plastic strain weakening implementation, where the frictional strength decreases with increasing accumulated strain. Alternatively, materials can be modelled to weaken depending on the local strain-rate (Ruh et al., 2014), which is characteristic for e.g. coseismic frictional weakening of faults. Here we show key differences of strain- vs. strain-rate-dependent faults weakening in terms of orogenic strain propagation patterns in numerical models of a corner collision setting, based on the eastern corner of the India-Eurasia collision. The numerical model I3ELVIS (Gerya & Yuen, 2007) consists of a finite-difference, marker-in-cell method coupled to a diffusion-advection-based finite-difference surface process model, FDSPM (Munch et al., 2022). We highlight key differences between the results of a model with strain-rate-dependent weakening, and a model with conventional strain-dependent weakening based on accumulated strain. The former shows significantly sharper shear zones, as well as a higher number of thrust faults that are relatively evenly spaced, which is more realistic in natural collision zones. 

 

Gerya, T. V., & Yuen, D. A. (2007). Robust characteristics method for modelling multiphase visco-elasto-plastic thermo-mechanical problems. Physics of the Earth and Planetary Interiors, 163(1), 83–105. https://doi.org/10.1016/j.pepi.2007.04.015

Bercovici, D., & Ricard, Y. (2014). Plate tectonics, damage and inheritance. Nature, 508(7497), 513–516. https://doi.org/10.1038/nature13072

Ruh, J. B., Gerya, T., & Burg, J.-P. (2014). 3D effects of strain vs. Velocity weakening on deformation patterns in accretionary wedges. Tectonophysics, 615–616, 122–141. https://doi.org/10.1016/j.tecto.2014.01.003

Munch, J., Ueda, K., Schnydrig, S., May, D. A., & Gerya, T. V. (2022). Contrasting influence of sediments vs surface processes on retreating subduction zones dynamics. Tectonophysics, 836, 229410. https://doi.org/10.1016/j.tecto.2022.229410

 

How to cite: van Agtmaal, L., Balazs, A., May, D., and Gerya, T.: Effects of strain- vs. strain-rate-dependent faults weakening for continental corner collision: insight from 3D thermomechanical models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13519, https://doi.org/10.5194/egusphere-egu23-13519, 2023.

EGU23-13642 | ECS | Orals | GD9.1 | Highlight

The Dynamics of the India-Eurasia Collision: A Suite of Faulted Viscous Continuum Models Constrained by New High-Resolution Sentinel-1 InSAR and GNSS Velocities 

Jin Fang, Greg Houseman, Tim Wright, Lynn Evans, Tim Craig, John Elliott, and Andy Hooper

Block versus continuum description of lithospheric deformation in the India-Eurasia collision zone has been hotly debated over many decades. Here we apply the adapted two-dimensional (2-D) Thin Viscous Shell (TVS) approach explicitly accounting for displacement on major faults in Tibet (Altyn Tagh, Haiyuan, Kunlun, Xianshuihe, Sagaing, and Main Pamir Thrust Faults) and investigate the impact of lateral variations in depth-averaged lithospheric strength. We present a suite of dynamic models to explain the key observations from new high-resolution Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) as well as Global Navigation Satellite System (GNSS) velocities. Comparisons between calculated and observed velocity and strain rate fields indicate: (a) internal buoyancy forces from Gravitational Potential Energy (GPE) acting on a relatively weak region of high topography (~2,000 m) contribute to dilatation of high plateau and contraction on the margins; (b) a weak central Tibet (~1021 Pa s relative to far-field depth-averaged effective viscosity of 1022 to 1023 Pa s) yields the observed long-wavelength eastward velocity variation away from major faults; (c) slip resistance on faults produces strain localization and clockwise rotation around the Eastern Himalayan Syntaxis (EHS). We discuss the tectonic implications for rheology of the lithosphere, distribution of geodetic strain, and partitioning of active faulting and seismicity in light of our best-fit geodynamic solutions.

How to cite: Fang, J., Houseman, G., Wright, T., Evans, L., Craig, T., Elliott, J., and Hooper, A.: The Dynamics of the India-Eurasia Collision: A Suite of Faulted Viscous Continuum Models Constrained by New High-Resolution Sentinel-1 InSAR and GNSS Velocities, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13642, https://doi.org/10.5194/egusphere-egu23-13642, 2023.

EGU23-14244 | ECS | Posters virtual | GD9.1

The birth of the Mesotethys ocean recorded in the Southern Pamir Triassic basalts  

Jovid Aminov, Denis Mikhailenko, Sharifjon Odinaev, Mohssen Moazzen, Guillaume Dupont-Nivet, Yunus Mamadjanov, Aleksandr Stepanov, Jovid Yogibekov, and Sohibnazar Ashuraliev

The Pamir orogen, the western extension of the Tibetan plateau, formed and uplifted due to Mesozoic terrane amalgamation and Cenozoic India-Asia collision. The Mesozoic history of the amalgamation of Gondwana-derived Cimmerian terranes to the southern margin of Eurasia that produced the crust of the Pamirs is poorly understood. The birth and demise of an oceanic basin that divided Central and Southern Pamir in the early Mesozoic is an example of a gap in the knowledge of Pamir orogen formation throughout the Mesozoic and Cenozoic eras. Termed Mesotethys, this ocean likely originated in the early Permian when the Cimmerian super-terrane broke from Gondwana's northern limit. Geochemistry of early Permian basalts suggests this rifting event was driven by a plume that generated a seamount or series of seamounts that accreted to the Central Pamir before the Mesotethys closed in the late Triassic. Vestiges of the Mesotethys are preserved in the Rushan - Pshart suture zone.   This zone comprises Permian and Triassic marine sedimentary strata and thick layers of volcanic rocks, including the late Triassic basalts. This volcano-sedimentary sequence is intruded by the late Triassic – early Jurassic granites that have subduction-related affinity marking the closure of the Mesotethys. The current work focuses on the geochemical markers of late Triassic volcanism to evaluate whether a plume-related magmatic activity was responsible for the creation of the Mesotethys Ocean.

Our preliminary geochemical results indicate that the SiO2 content of basalts is low, ranging from 36.5 to 47.7 wt.%, which classifies the rocks as mafic and ultramafic. The rocks' TiO2 concentration is exceptionally high, ranging from 1.9 to 4.4 wt.%, which is not typical of arc-related basalts and instead resembles oceanic island basalts. Concentration of Al2O3 (7.5-18.8 wt.%), Fe2O3 (8.3-16.3 wt.%), MgO (2.7 – 14.9 wt.%) and CaO (2.5 – 12.4 wt.%) likewise fluctuate in a large range. Alkalis also vary across a wide range (K2O: 0.2 – 3.1 wt.%; Na2O: 1.4 – 5.5 wt.%) and add up to values (1.7 – 7 wt.%) that define the majority of the examined samples (11) as alkali basalts, with three samples plotting below the sub-alkaline – alkaline dividing line. The rocks' relatively high P2O5 (0.2 to 0.6 wt.%) may further reflect their OIB affinity. Normalized to the primitive mantle, trace element patterns on spidergrams reveal a small enrichment of Large-Ion Lithophile Elements and depletion of High-Field Strength Elements. However, positive anomalies in Nb (14.3 – 29 ppm) and Ti rule out subduction as the cause of the rocks' formation. Moreover, high ratios of Nb/La (1.1–1.7) and La/Yb (6.9–15) also support the non-subductional origin of the basalts. Thus, our collected geochemical data reveal a striking similarity to the basalts of oceanic islands.

 

How to cite: Aminov, J., Mikhailenko, D., Odinaev, S., Moazzen, M., Dupont-Nivet, G., Mamadjanov, Y., Stepanov, A., Yogibekov, J., and Ashuraliev, S.: The birth of the Mesotethys ocean recorded in the Southern Pamir Triassic basalts , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14244, https://doi.org/10.5194/egusphere-egu23-14244, 2023.

EGU23-14296 | ECS | Orals | GD9.1

The devastating 2022 M6.2 Afghanistan earthquake: challenges, processes and implications 

Sofia-Katerina Kufner, Lidong Bie, Ya-Jian Gao, Mike Lindner, Hamidullah Waizy, Najibullah Kakar, and Andreas Rietbrock

On June 21th, a Mw6.2 earthquake struck the Afghan-Pakistan-border-region, an area dominated by partitioned deformation related to the India-Asia collision. Despite its moderate size, 1150 deaths were reported, making the event the deadliest earthquake of 2022 so far. We investigate the event’s rupture processes, aiming to understand what made it that fatal. Our InSAR-constrained slip model and regional moment-tensor inversion reveal a sinistral rupture with maximum slip of 1.8 m at 5 km depth on a N20°E striking, sub-vertical fault. Field observations confirm fault location and slip-sense. Based on our analysis and a global comparison, we suggest that not only external factors (e.g. time of the event and building stock) but also fault-specific factors made the event excessively destructive. Surface rupture was favored by the local rock anisotropy (foliation), coinciding with the fault strike. The distribution of Peak Ground Velocity was governed by the sub-vertical fault. The maximum slip was large compared to other events globally and might have resulted in peak-frequencies coinciding with the resonance-frequency of the local one-story buildings. More generally, our study demonstrates the devastating impact of moderate earthquakes, being small enough to be accommodated by many tectonic structures but large enough to cause significant damage.

How to cite: Kufner, S.-K., Bie, L., Gao, Y.-J., Lindner, M., Waizy, H., Kakar, N., and Rietbrock, A.: The devastating 2022 M6.2 Afghanistan earthquake: challenges, processes and implications, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14296, https://doi.org/10.5194/egusphere-egu23-14296, 2023.

EGU23-14406 | Posters on site | GD9.1

Kinematics of the Pamir orogeny on a lithospheric scale 

Jonas Kley, Edward R. Sobel, Thomas Voigt, Johannes Rembe, and Rasmus Thiede

The south-dipping Benioff zone beneath the Pamir mountains marks the youngest, active slab accommodating India-Asia convergence near the western edge of the Indian indenter (75° E). Seismic tomography suggests the existence of two older slabs farther south, both interpreted as Indian lithosphere detached and sinking: the Tethys slab, broken off around 46 Ma concomitant with early collision and the more northerly and shallower Indian slab, detached around 25 Ma at the longitude considered here (Replumaz et al. 2010). The total length of the three slabs is about 1300 km (Tethys 600 km, India 300 km, Pamir 400 km), substantially less than the distance of more than 2000 km that India has moved north since 46 Ma. This discrepancy implies that either the tomographic record of subduction is incomplete or that Indian mantle lithosphere has underthrust (thin?) Asian lithosphere, with the stacked lithospheres unresolvable by tomography. As a consequence, the rate of slab lengthening and the age of slab initiation in the Pamir are poorly constrained. The absence of asthenosphere between the Pamir slab of Asian provenance and supposedly Indian mantle lithosphere above it suggests that India´s leading edge is advancing at the same rate as rollback of the Pamir slab. This rate could be as high as full India-Asia convergence at ca. 35 mm/yr (Kufner et al. 2016) or as low as present-day Pamir-foreland convergence at 15 mm/yr, corresponding to ages of the 300-400 km long slab of 9-12 Ma or 20-27 Ma. The wide range of possible ages makes it difficult to tie slab initiation to specific geologic events during the Pamir orogeny. Other evidence suggests that the direction and rate of India-Asia convergence may be poor predictors of mantle lithospheric motion above the slab: The shortening direction in the Tajik foreland thrust belt is WNW, and foreland shortening decreases northeastward from a maximum of 150 km in the Tajik belt to 75 and 30 km in the Alai Valley and westernmost Tarim. Slab length follows a similar trend, with a steeply east-dipping Benioff zone in the west and a more gently south-dipping one in the north, traced by earthquakes to depths of 250 km and 150 km, respectively. Also, the longest, NE-striking segment of the slab is relatively straight in map view and parallel to the axis of thickest crust (Schneider et al. 2019). These observations are difficult to reconcile with northward convergence. Instead, they suggest overall northwestward convergence during the Pamir orogeny. We speculate that this could be due to westward deflection at depth of an Indian lithosphere promontory interacting with the NW-trending edge of thick Tarim lithosphere.

Kufner, S.-K., et al. (2016). Deep India meets deep Asia: Lithospheric indentation, delamination and break-off under Pamir and Hindu Kush (Central Asia). Earth and Planetary Science Letters 435: 171-184.

Replumaz, A., et al. (2010). Indian continental subduction and slab break-off during Tertiary collision. Terra Nova 22: 290-296.

Schneider, F. M., et al. (2019). The Crust in the Pamir: Insights from Receiver Functions. Journal of Geophysical Research: Solid Earth 124(8): 9313-9331.

How to cite: Kley, J., Sobel, E. R., Voigt, T., Rembe, J., and Thiede, R.: Kinematics of the Pamir orogeny on a lithospheric scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14406, https://doi.org/10.5194/egusphere-egu23-14406, 2023.

EGU23-14762 | ECS | Posters virtual | GD9.1

Understanding Magma Nature of Post-Collisional Alkaline Granites Around Uludag (NW, Turkiye): Implications for New Geodynamic Scenarios 

Huseyin Kocaturk, Mustafa Kumral, Ali Tugcan Unluer, Mustafa Kaya, Merve Sutcu, Zeynep Doner, Huseyin Sendir, and Amr Abdelnasser

Magmatic Suite around Uludag Massif contains some alkaline (A-type or highly fractionated felsic I-type) granites that developed in post-collisional plate tectonic conditions. Their genesis involved by Eocene calc-alkaline and Oligocene strongly peraluminous granite magmatism. Their emplacement is linked to strike-slip shear movements and/or extension that occur after the Neo-Tethys collisional events. These granites are spatially related to the Izmir-Ankara Suture Zone (IASZ). The majority of these alkaline granites are formed by middle or lower crustal anatexis, extracted melt restite of I-type granites. Previously non-melted mafic meta-tonalites are considered to represent their source rocks. The mechanism for the required high melting temperatures will be well explained by our new model. However, models based on partial delamination of the base of the lithosphere or asthenospheric upwelling due to steepening and breaking of the subducted Tethyan oceanic slab are still consistent. As is the case for many well-known post-collisional regimes, transpressional to transtensional and/or moderately extensional tectonism predominates throughout to region. Although crustal thickening does not appear evident as in the notable arcs and microcontinent collisions, uplifting of particular regions associated with post-collisional calc-alkaline granite emplacement is observable. Understanding the nature of post-collisional highly fractionated granites around Uludag will extend the view of how Western Anatolia was affected by Alpine Orogeny in the Tethyan Realm. The challenge is drawing the geochemistry line for the tectono-magmatic setting between post-collision to post-orogenic. Describing the nature of alkaline magmatism through late-stage orogeny to intra-plate setting may need to be more precise because of trace elements' overprinting. However, a holistic view of the magmatism and source rocks points out a synchronous crustal growth and crustal rework. Our new possible geodynamic scenario suggests crust–mantle decoupling combined with slab retreat results in thinning of the lithospheric mantle. The 75-80 km decoupling depth calculated from obducted blueschists of Tavsanlı Zone confirms the plate motions controlled thermal relaxation temperature is enough at the base of the lithosphere for the geotherm-induced magma generation for the Tavsanlı Zone.

How to cite: Kocaturk, H., Kumral, M., Unluer, A. T., Kaya, M., Sutcu, M., Doner, Z., Sendir, H., and Abdelnasser, A.: Understanding Magma Nature of Post-Collisional Alkaline Granites Around Uludag (NW, Turkiye): Implications for New Geodynamic Scenarios, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14762, https://doi.org/10.5194/egusphere-egu23-14762, 2023.

Gneiss dome records the deformation and tectonothermal evolution of orogenic belt and lithosphere, which provides a perfect window for studying of collisional orogenic process and tectonic evolution. The North Himalayan Gneiss Domes, trending East-West, as one of the important tectonic units of the Himalayan orogen, experienced deep materials uplifting and lateral flow. Based on the above observations, we suggest that the RBD experienced 4 periods of tectonothermal evolutions (D1-D4) and 2 stages of tectonic background transformations. (1) D1: Crustal thickening, regional metamorphism and anatexis occurred during plate collision in the Eocene (46.3-40.6 Ma). (2) D2: Partial melting of middle-lower crust result in the development of channel flow which reduced the rheology of the middle-lower crust and led to the onset of the STDS and crustal thinning in the early Miocene (26.1-21.0 Ma). Therefore, the tectonic background transformed from N-S compression to N-S extension (the first tectonic background transformation). (3) D3: The ongoing of the STDS contribute to the decompression melting, small-scale diapirism and accompanied magmatic emplacement. The activity of the NSTRs started at mid-Miocene (12.0-10.2 Ma), the tectonic background shifted from N-S extension to E-W extension (the second tectonic background transformation). (4) D4: +With NSTRs’ activity peaking in the late Miocene (8.7-7.6 Ma), further crustal thinning, decompression melting and leucogranite intrusion occurred under extensional condition, which result in the contact metamorphism, and established the final tectonic framework, geometry, and thermalstructure of the RBD. The tectonothermal evolution of the RBD supports the middle-lower crustal channel flow orogenic model.

Fluid inclusion and oxygen isotope data for quartz veins in the Ramba Dome in the North Himalayan Gneiss Domes show limited variations in individual quartz veins, but δ18Oquartz values vary from 12.07 to 18.16‰ (V-SMOW) among veins. The corresponding δ18Ofluid values range from 7.71 to 13.80‰, based on equilibrium temperatures obtained from fluid inclusions. From the footwall to the detachment zone, δ18Ofluid values exhibit a broadly decreasing trend and indicate that the STDS dominated the fluid flux pathway in the crust, with more contributions of meteoric water in the detachment zone. We further quantified the contribution of meteoric fluids to 8–27% using a binary end-member mixing model. These data imply that the fluids were predominantly metamorphic/ magmatic in origin, and were mixed with infiltrating, isotopically light, meteoric water during extensional detachment shearing of the STDS. Based on the above research, we propose that metamorphic dehydration of lower crust and atmospheric precipitation "stimulate" new activity of Himalayan mountain building.

How to cite: Bo, Z.: The multistage extensional structure and excitation mechanism of Himalayan orogeny, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15394, https://doi.org/10.5194/egusphere-egu23-15394, 2023.

EGU23-16615 | Orals | GD9.1

Crustal Structure of the Jammu and Kashmir Himalaya 

Supriyo Mitra, Swati Sharma, Debarchan Powali, Keith Priestley, and Sunil Wanchoo

We use P-wave receiver function (P-RF) analysis of broadband teleseismic data recorded at twenty stations spanning the Jammu-Kishtwar Himalaya, Pir Panjal Ranges, Kashmir Valley, and Zanskar Ranges in Northwest Himalaya, to model the seismic velocity structures of the crust and uppermost mantle. Our network extends from the Shiwalik Himalaya (S) to the Tethyan Himalaya (N), across major Himalayan thrust systems and litho-tectonic units. We perform depth–Vp /Vs (H-K) stacking of P-RF, common conversion point (CCP) stacking along 2D profiles and joint inversion with surface wave dispersion data. H-K analysis reveals increasing average crustal thickness from the foreland (∼40 km) to the hinterland (∼65 km), with felsic- to-intermediate (Vp /Vs of 1.71–1.80) average crustal composition. In CCPs the Indian crust Moho is marked by a large positive impedance contrast boundary, and the Main Himalayan Thrust (MHT) by a negative phase, indicating a low velocity layer (LVL). The underthrust Indian crust (between the MHT and Moho) has an average thickness of ∼40 km and the Moho dips northward at ∼7–9◦ . Moho flexure (or possible off-set) are observed in across-arc profiles, beneath the Shiwalik Himalaya, Higher Himalaya and the Kishtwar window. The Moho is remarkably flat at ∼55 km beneath the Pir Panjal Ranges and the Kashmir Valley. North of the Kishtwar window (E) and Kashmir Valley (W) the Moho dips steeply underneath the Tethyan Himalaya/Zanskar Ranges from ∼55 km to ∼65 km. The MHT LVL is at a depth of ∼8 km beneath the Shiwalik Himalaya, and dips gradually northeast at ∼7–9◦ , to reach a depth of ∼25 km beneath the Higher Himalaya. The MHT is marked by a frontal ramp beneath the Kishtwar window (E) and north of the Kashmir Valley (W). The MKT, MBT and MCT are marked by LVLs which splay updip from the MHT. To study the 3D variation of the crustal structure, we grid the region into 0.1◦ square grids and jointly model the P-RFs within each grid with Rayleigh wave dispersion data, obtained from regional tomography. The 3D models obtained from this analysis provide variations in Vs and Moho depth. The Kashmir Valley and Zanskar Ranges are underlain by the highest average crustal Vs followed by the Pir-Panjal Ranges. These are also regions of the thickest crust. The Shiwalik Himalaya is underlain by the slowest average Vs , with lateral variations along the MKT, Reasi Thrust and the Kotli Thrust. These are also regions of thinnest crust (~40 km). A remarkable lower Vs region extends SW-NE from Jammu to the Kishtwar window, along the reentrants of the MHT, MBT and MCT. This marks a strong E-W lateral variation in crustal Vs , Moho depth and a possible lateral ramp on the MHT, also highlighted by small-to-moderate earthquake clusters.

How to cite: Mitra, S., Sharma, S., Powali, D., Priestley, K., and Wanchoo, S.: Crustal Structure of the Jammu and Kashmir Himalaya, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16615, https://doi.org/10.5194/egusphere-egu23-16615, 2023.

EGU23-17000 | Posters virtual | GD9.1

Paleo-Tethyan ocean evolution in the East Kunlun Orogen, northern Tibetan plateau 

Ruibao Li, Xianzhi Pei, Zuochen Li, Lei Pei, Guochao Chen, Zhanqing Liu, Youxin Chen, Chengjun Liu, and Meng Wang

The East Kunlun Orogen on the northern margin of the Tethyan orogenic system records a history of Gondwana dispersal and Laurasian accretion. Based on a synthesis of sedimentary, structural, lithological, geochemical, and geochronological data from the East Kunlun Orogen and adjacent regions, we discusses the spreading and northward consumption of the Paleo-Tethys Ocean during Late Paleozoic-Early Mesozoic times. The main evolutionary stages are: (1) During Carboniferous to Middle Permian, the Paleo-Tethys Ocean (Buqingshan Ocean) was in an ocean spreading stage, as suggested by the occurrence of Carboniferous MORB-, and OIB-type oceanic units and Carboniferous to Middle Permian Passive continental margin deposits; (2) The Buqingshan Ocean subducted northward beneath the East Kunlun Terrane, leading to the development of a large continental magmatic arc (Burhan Budai arc) and forearc basin between ~270-240 Ma; (3) During the late Middle Triassic to early Late Triassic (ca. 240-230 Ma), the Qiangtang terrane collided with the East Kunlun-Qaidam terranes, leading to the final closure of the Buqingshan Ocean and occurrences of minor collision-type magmatism and potentially inception of the Bayan Har foreland basin; (4) Finally, the East Kunlun Orogen evolved into a postcollisional stage and produced major magmatic flare-ups and polymetallic mineral deposits between Late Triassic to Early Jurassic (ca. 230-200 Ma), which is possibly related to asthenospheric mantle upwelling induced by delamination of thickened continental lithosphere and partial melting of the lower crust. Accordingly, we propose that the Wilson cycle-like processes controlled the Late Paleozoic-Early Triassic tectonic evolution of East Kunlun, which provides significant implications for the evolution of Paleo-Tethys Ocean.

How to cite: Li, R., Pei, X., Li, Z., Pei, L., Chen, G., Liu, Z., Chen, Y., Liu, C., and Wang, M.: Paleo-Tethyan ocean evolution in the East Kunlun Orogen, northern Tibetan plateau, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17000, https://doi.org/10.5194/egusphere-egu23-17000, 2023.

EGU23-17021 | ECS | Orals | GD9.1

Rheological heterogeneities control the non-progressive uplift of the young Iranian plateau 

Yifan Gao, Ling Chen, Jianfeng Yang, and Kun Wang

The Iranian plateau is at the early stage of plateau development and intracontinental deformation in response to the Arabia-Eurasia collision. Its compressive deformation is concentrated in the northern plateau but skips the central counterpart, challenging the common views envisaging the progressive uplift from the collisional front to the hinterland. Based on three-dimensional, crustal-scale numerical models, we present how the rheological heterogeneities common in continents control the deformation of the young Iranian plateau. The weak northern plateau ensures itself a preferential zone in accommodating continental collision. The N-S strike-slip faults within the non-rigid central plateau, formed along the boundaries between the tectonic units with rheological contrast, suppress the shortening of the central plateau while further accentuating the compressive deformation of the northern plateau. Our results suggest a non-progressive intracontinental deformation pattern where rheological boundaries and mechanically weak zones, not necessarily those close to collisional fronts, preferentially accommodate continental convergence.

How to cite: Gao, Y., Chen, L., Yang, J., and Wang, K.: Rheological heterogeneities control the non-progressive uplift of the young Iranian plateau, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17021, https://doi.org/10.5194/egusphere-egu23-17021, 2023.

EGU23-17123 | Orals | GD9.1 | Highlight

The Nature of the Cimmerian Continent 

A.M. Celâl Şengör, Demir Altıner, Cengiz Zabcı, Gürsel Sunal, Nalan Lom, and Tayfun Öner

We have compiled local stratigraphic, structural, palaeobiogeographical and reliable isotopic age data from the remnants of the Cimmerian Continent from western Turkey to Malaysia with a view to understanding its nature and evolution. Our principal conclusions are the following:

1) The entire northwestern margin of Gondwana-Land was an extensional Pacific-type continental margin much like the present-day western Pacific during the Permo-Carboniferous characterised by typical Gondwana-Land biotas.

2) Beginning with the Permian, the Cimmerian Continent began to pull away from the northeastern margin of Gondwana-Land from Turkey in the west to Malaysia in the east, although in Thailand and Malaysia rifting may have started already during the earlierst Carboniferous.

3) Synchronously with this rifting, the Wašer/Rushan-Pshart/ Banggong Co-Nu Jiang ocean, herein called the Maera, began opening in the Permian isolating the Lhasa/Victoria Land block from the rest of the Cimmerian Continent. In fact, the Himalayan sector of the Neo-Tethys may have opened slightly later than the Maeran ocean.

4) Central Iran consisted of two parts: the northest Iranian extensional area and the multi-block Central Iranian Continent consisting of the Yazd, Posht-e Badam, Tabas and the Lut blocks. These blocks were stacked against one another horizontally as a consequence of the Cimmeride collisions in the Pamirs and Afghanistan while Albors was rifted away from the Sanandaj-Sirjan zone, as the latter was also rifting away from Gondwana-Land, stretching northwestern Iran into its present-day triangular shape.

5) Significant arc magmatism characterised the entire Cimmerian continent from one end to the other during the Permian to the Liassic interval.

We thus maintain that the Cimmerian Continent was the site of supra-subduction extension throughout its history until it collided with Laurasia during the medial to late Jurassic. In some areas the collision may have been earlier. The Maeran ocean remained opened until the Aptian. The best analogue for the evolution of the Cimmerian Continent and its attendant small oceans is the present-day southwest Pacific arc/marginal basin systems from the Tonga-Kermadec system in the east as far west as Australia.

How to cite: Şengör, A. M. C., Altıner, D., Zabcı, C., Sunal, G., Lom, N., and Öner, T.: The Nature of the Cimmerian Continent, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17123, https://doi.org/10.5194/egusphere-egu23-17123, 2023.

EGU23-1069 | ECS | Orals | SM2.1

Seismic Anisotropy from 6C Observations 

Le Tang, Heiner Igel, and Jean-Paul Montagner

A new approach is proposed for measuring the local dispersion curves of surface waves in weakly anisotropic media using a single, multi-component station, which consists of translation and rotation or strain. We directly extract the local azimuth-dependent phase velocity of the Rayleigh wave from the 6C amplitude ratio using seismic arrays deployed in Southern California. The extracted dispersion curves match well with the theoretical 2φ azimuthal anisotropy term. And the estimated fast wave direction is also consistent well with results calculated from SKS and beamforming methods which demonstrates the feasibility of studying local seismic anisotropy directly from 6C amplitude observations.

How to cite: Tang, L., Igel, H., and Montagner, J.-P.: Seismic Anisotropy from 6C Observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1069, https://doi.org/10.5194/egusphere-egu23-1069, 2023.

Distributed Acoustic Sensing (DAS) in geothermal wells is a particularly attractive technology to implement as part of routine seismic monitoring of geothermal plant operations. It brings a large network of sensors close to the monitoring target – the operated reservoir – increasing the sensitivity towards low magnitude events and allows the application of processing procedures inspired by large network or array processing. However, the technical management of the large flow of produced data and the suitability of the strain-rate acquisitions to monitor locally induced seismicity was yet to be fully assessed.

We present the results of a continuous 6-month monitoring period that aimed at testing an integrated system designed to manage the acquisition, the processing and the saving of DAS data collected from behind casing at the Schäftlarnstraße (SLS) geothermal project (Munich, Germany). The data management system links the existing on-site infrastructure to a cloud Internet-of-Things (IoT) platform integrated into the company’s IT infrastructure. The cloud platform has been designed to deliver both a secure storage environment for the DAS records and optimized computing resources for their continuous processing.

With a special focus on seismic risk mitigation, we investigate the potential of the monitoring concept to provide sensitive detection capabilities, despite operational conditions, while ensuring efficient data processing in order to strive for real-time monitoring. Further analysis of the records confirm additional logging capabilities of borehole DAS. We also evaluate the ability of DAS to provide reliable seismic source description, in particular in terms of location, moment magnitude, and stress drop.

Using two detected local seismic events, we demonstrate the relevance of the system for monitoring the SLS-site in an urban environment, while complementing advantageously the surface seismometer-based monitoring network.

How to cite: Azzola, J. and Gaucher, E.: Continuous seismic monitoring of a geothermal project using Distributed Acoustic Sensing (DAS): a case study in the German Molasse Basin., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1292, https://doi.org/10.5194/egusphere-egu23-1292, 2023.

EGU23-2091 | Orals | SM2.1 | Highlight

Using DAS-fibres at ocean floor and lunar surface 

Martin Landrø

We have used two seabed fibre optic cables connecting Ny Ålesund and Longyearbyen at Svalbard, North of Norway, to track several whales for several weeks. Exploiting that we have access to two fibres we demonstrate that it is possible to track several whales in a fairly large region. It is possible to create sound records of whales that can be used for identification and discrimination between various species. The localization method has also been tested by using a small air gun to confirm the localization method used for whales. Examples of earthquake recordings, ship traffic monitoring and distant storms will be shown.

Based on the rapid and promising developments within DAS technology, there is a growing interest for using fibre optic cables at the moon. Some challenges and possibilities related to Lunar DAS applications will be discussed.

How to cite: Landrø, M.: Using DAS-fibres at ocean floor and lunar surface, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2091, https://doi.org/10.5194/egusphere-egu23-2091, 2023.

EGU23-2814 | Orals | SM2.1

Divergence-based estimation of Rayleigh wave dispersion curves 

Pascal Edme, David Sollberger, Tjeerd Kiers, Cedric Schmelzbach, Felix Bernauer, and Johan Robertsson

We present a novel seismic acquisition and processing technique to efficiently evaluate the local dispersion curves of Rayleigh waves for subsequent inversion of shear velocities and near-surface characterization.

The proposed approach consists of computing the ratio between the (time derivated) horizontal spectra H(f)=(∂tVx(f)2+∂tVy(f)2)1/2  and the pseudo-divergence spectra D(f), with D being the sum of the horizontal gradients of the horizontal components (i.e. D=∂xVx+∂yVy).

The processing method itself is comparable to the commonly used H/V approach, except that the H/D spectral ratio provides a direct estimate of the frequency-dependent phase velocities cR(f)  instead of the site frequency amplification(s). This is demonstrated using synthetic data.

We describe how the D component can be obtained in practice, i.e. by finite-differencing closely spaced horizontal phones or potentially using Distributed-Acoustic-Sensing (DAS) and fibre-optic deployed at the surface. Some limitations about wavelength dependency and impact of Love waves are discussed, as well as potential mitigation measures.

A field test on several hours of ambient noise data collected in Germany with multi-component geophones results in realistic values of Rayleigh wave velocities ranging from ~770 m/s at 10 Hz to ~500 m/ at 30 Hz. Thanks to the local and omni-directional nature of the estimation, the minimal number of required channels and the applicability to ambient noise, we believe that the proposed H/D method can be an attractive alternative to expensive array-based techniques.

How to cite: Edme, P., Sollberger, D., Kiers, T., Schmelzbach, C., Bernauer, F., and Robertsson, J.: Divergence-based estimation of Rayleigh wave dispersion curves, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2814, https://doi.org/10.5194/egusphere-egu23-2814, 2023.

EGU23-3061 | Orals | SM2.1

Nano-strain resolution fiber-optic Fabry-Perot sensors based measuring systems 

Simon Pevec and Denis Donlagic

A work describes a deeply etched, long active length, high sensitivity short Fabry-Perot cavity nano-strain resolution sensor. The presented sensors exhibit high spectral sensitivity, low intrinsic temperature sensitivity which is for about 40 times lower than in case of FBG, small size and mounting comparable to conventional Fiber Bragg gratings. The sensor high potential is not only high sensitivity and low temperature intrinsic sensitivity, but also in short cavity length and its tunability, which can be simply accomplished in one production step. This brings versatility in interrogation with different general purpose and cost-efficient VIS-NIR widely available linear detector array-based spectrometers, while still providing strain sensing resolution within the range of few 10 nε. A strain resolution of 20 to 70 nε was demonstrated when using a cost-efficient VIS spectrometer. Furthermore, the sensor structure can be combined with multimode telecom lead-in fibers and low-cost broadband LEDs intended for automotive/lightning applications, which allow production of cost efficient solutions.

How to cite: Pevec, S. and Donlagic, D.: Nano-strain resolution fiber-optic Fabry-Perot sensors based measuring systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3061, https://doi.org/10.5194/egusphere-egu23-3061, 2023.

EGU23-3437 | ECS | Posters on site | SM2.1

Monitoring temperature at the ocean seafloor with fibre optic cables and DAS 

Julián Pelaez Quiñones, Anthony Sladen, Aurelien Ponte, Itzhak Lior, Jean-Paul Ampuero, Diane Rivet, Samuel Meulé, Frédéric Bouchette, Ivane Pairaud, and Paschal Coyle

Ocean water temperature measurements are fundamental to atmospheric and ocean sciences. Obtaining them, however, often comes along with major experimental and logistic challenges. Except for the uppermost ocean surface temperature, which can be measured from satellites, temperature data of the ocean is often poorly sampled or nonexistent, especially in deep-water regions.

Although Distributed Acoustic Sensing (DAS) technology has become popular because its high sensitivity to strains and mechanical vibrations, our work focuses on its usage on tens-of-kilometer-long underwater fibre-optic (FO) telecommunication cables to measure temperature anomalies at the seafloor at millikelvin (mK) sensitivity. This is possible because of the lack of dominant strain signals at frequencies less than about 1 mHz, as well as the poor coupling of the fibre with these signals while remaining highly sensitive to slow ambient temperature variations that locally affect its optical path length. DAS allows us to observe significant temperature anomalies at the continental shelf and slope of the Mediterranean sea, South of Toulon, France over periods of several days, with variability remaining relatively low at the deep ocean. By means of this approach, oceanic processes such as near-inertial internal waves and upwelling can be monitored at unprecedented detail.

Our observations are validated with oceanographic in-situ sensors and alternative Distributed Fibre Optic Sensing (DFOS) technologies established for temperature sensing. We outline key advantages of DAS thermometry over the aforementioned sensors in terms of spatial coverage, sensitivity, versatility and highest attainable frequency. At the current state of the art, DAS can only measure temperature anomalies as opposed to absolute temperature, a drawback that could be compensated via single temperature calibration measurements.

How to cite: Pelaez Quiñones, J., Sladen, A., Ponte, A., Lior, I., Ampuero, J.-P., Rivet, D., Meulé, S., Bouchette, F., Pairaud, I., and Coyle, P.: Monitoring temperature at the ocean seafloor with fibre optic cables and DAS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3437, https://doi.org/10.5194/egusphere-egu23-3437, 2023.

EGU23-3955 | ECS | Orals | SM2.1

Using Distributed Acoustic Sensing to Monitor and Investigate Eruptive Events at Stromboli Volcano, Italy 

Francesco Biagioli, Jean-Philippe Métaxian, Eléonore Stutzmann, Maurizio Ripepe, Alister Trabattoni, Pascal Bernard, Roberto Longo, Gianluca Diana, Lorenzo Innocenti, Yann Capdeville, Marie-Paul Bouin, and Giorgio Lacanna

Volcano seismology is essential for understanding, monitoring, and forecasting eruptive events. The use of distributed acoustic sensing (DAS) technology can be particularly useful for this purpose because of its high temporal and spatial resolution, which may help to overcome the challenges of deploying and maintaining seismic arrays on volcanoes.

Between 2020 and 2022, we installed 4 km of optical fibre on Stromboli volcano, Italy, whose persistent activity is well-suited for investigating the related dynamic strain rate. The cable was buried at a depth of 30 cm and the layout geometry was designed to provide wide coverage while being constrained by natural obstacles and topographical features. Seismometers were also installed along the fibre. DAS data were collected using a Febus A1-R interrogator, and the acquisition period increased from one week in 2020 to over four months in 2022. We recorded volcanic tremor, ordinary explosions (several per hour), two major explosions in 2021 and 2022, and the entire sequence of a pyroclastic flow in 2022. 

DAS and seismic data show good agreement in both time and frequency domains after converting strain rate to velocity and vice versa using different methodologies. Beamforming of DAS data shows a dominant signal in the 3-5 Hz frequency band coming from the active craters. We will also present preliminary results of major explosions and pyroclastic flow. This experiment demonstrates that DAS can be used for monitoring volcanic activity.

How to cite: Biagioli, F., Métaxian, J.-P., Stutzmann, E., Ripepe, M., Trabattoni, A., Bernard, P., Longo, R., Diana, G., Innocenti, L., Capdeville, Y., Bouin, M.-P., and Lacanna, G.: Using Distributed Acoustic Sensing to Monitor and Investigate Eruptive Events at Stromboli Volcano, Italy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3955, https://doi.org/10.5194/egusphere-egu23-3955, 2023.

EGU23-4256 | ECS | Posters on site | SM2.1

Groundwater monitoring using fibre-optics and DAS: Application to the Lyon water catchment area. 

Destin Nziengui Bâ, Olivier Coutant, and Camille Jestin

Water resource management is a crucial socio-economic issue that requires developing high-resolution monitoring techniques, including non-invasive geophysical methods. Among them, passive seismic interferometry takes advantage of natural ambient seismic noise to recover the slight variations of the seismic wave velocity induced by changes in the groundwater level. In this study, we present the time and space monitoring of groundwater changes artificially generated by infiltration ponds at the exploitation field of Crépieux-Charmy (Lyon, France).  We deployed 3km of optical fibre and a dense array of fifty 3C geophones around infiltration basins. We recorded several cycles of filling-emptying with a DAS using a 2m spatial sampling (i.e., 1500 fibre sensors). The recorded signals are mainly associated with local anthropogenic noise (highways, trains, pumping, etc.). We could track seismic velocity variations with high temporal and spatial resolutions using ambient noise interferometry techniques. These variations are associated with the interaction between the water diffused from the basins and water table variations. This dynamic information helps understand and model water exchanges on the ground. The study confirms the possibility of groundwater monitoring using DAS records of ambient noise for seismic interferometry in a highly urbanized zone.

How to cite: Nziengui Bâ, D., Coutant, O., and Jestin, C.: Groundwater monitoring using fibre-optics and DAS: Application to the Lyon water catchment area., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4256, https://doi.org/10.5194/egusphere-egu23-4256, 2023.

EGU23-4769 | ECS | Orals | SM2.1

Arrival Picking for Distributed Acoustic Sensing seismic based on fractional lower order statistics 

Xiang Wang, Honghui Wang, Yuhang Wang, Shangkun Zeng, and Yiru Wang

In recent years, fiber-optic distributed acoustic sensing (DAS) has been gradually applied to seismology because of its long-distance and dense observation capability. It is a great challenge to effectively process the massive seismic data recorded by DAS. At present, the seismic data processing methods based on deep learning have achieved great success, especially in the tasks of seismic detection and arrival-time picking. However, due to the differences between DAS and geophone, such as sensing principles, spatial and temporal sampling rates, and noise intensity. The seismic arrival time picking model based on deep learning, which is trained by geophone seismic data with low spatial and temporal sampling rates and low noise intensity, severely degrades in performance on DAS seismic data with high spatial and temporal sampling rates and high noise intensity. In addition, a new seismic arrival time picking model is trained by fully supervised learning, which usually requires a large number of seismic data with accurate labels. However, the huge cost of manual picking and the lack of effective automatic picking models make it very difficult to build large-scale DAS seismic data sets with accurate labels. Therefore, it is very difficult to build an arrival time picking model based on fully supervised learning for DAS seismic data.

In this study, we propose a DAS seismic arrival time picking method based on fractional lower order statistics. Based on the difference of probability density function between noise and seismic signal, the proposed method uses alpha-stable distribution modeling noise (generally follow a Gaussian distribution) and seismic signal (generally follow a non-Gaussian distribution), and uses fractional lower order statistics under the assumption of alpha-stable distribution as the characteristic function to pick the arrival time.

Synthetic and actual DAS data tests show that the proposed method has better performance and robustness to random noise than other methods based on characteristic functions, such as STA/LTA, AR-AIC and kurtosis. Since the actual DAS seismic data has no ground truth of arrival time, we have further the performance of the proposed method on the geophone seismic data set. The proposed method provides better results on geophone seismic data and the data after up-sampling them to the typical time sampling rate of DAS.

How to cite: Wang, X., Wang, H., Wang, Y., Zeng, S., and Wang, Y.: Arrival Picking for Distributed Acoustic Sensing seismic based on fractional lower order statistics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4769, https://doi.org/10.5194/egusphere-egu23-4769, 2023.

EGU23-5455 | ECS | Posters on site | SM2.1

Active-source seismic experiments with DAS for monitoring reservoir rock in underground laboratories 

Katinka Tuinstra, Antonio Pio Rinaldi, Federica Lanza, Alba Zappone, Andreas Fichtner, and Stefan Wiemer

Underground laboratories have become indispensable in the understanding of physical processes during e.g., hydraulic stimulation and seismic monitoring of deep geothermal reservoirs or CO2 storage target reservoirs. They provide a test bench and constitute the bridge between small-scale laboratory studies and full-scale pilot sites. Here, we present results from multiple active source seismic campaigns in one of the Swiss underground laboratories: the Mont Terri Rock Laboratory. Here, DAS fibres are cemented behind the casing of multiple monitoring boreholes and active shots are taken with a P-wave sparker. This dense array of active seismic measurements enables us to obtain a baseline characterisation of the P-wave velocity of the rock before any activity (e.g., injection) takes place. During stimulations, dynamic measurements with an active sparker source are recorded, followed by a time-lapse monitoring approach where seismic measurements are collected through active seismic campaigns in set time intervals in the months after stimulations. In this way we can create high-resolution, four-dimensional monitoring and characterisations of the rock body and potential earthquakes during the full monitoring period. We show different configurations and measurements settings with their effect on the DAS recordings of active signals.

How to cite: Tuinstra, K., Rinaldi, A. P., Lanza, F., Zappone, A., Fichtner, A., and Wiemer, S.: Active-source seismic experiments with DAS for monitoring reservoir rock in underground laboratories, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5455, https://doi.org/10.5194/egusphere-egu23-5455, 2023.

EGU23-5701 | ECS | Posters on site | SM2.1

Investigating Vibroseis Sweeps using 6 Rotational Sensors in Fürstenfeldbruck, Germany 

Gizem Izgi, Eva Eibl, Frank Krüger, and Felix Bernauer

Rotational motions can be recorded directly or derived from translational motion recordings. Fairly new rotational sensors allow seismologists to directly record and investigate rotational motions. In order to further investigate and compare recently developed rotational sensors an experiment was made in Fürstenfeldbruck. Within this scope, a vibroseis truck was operated starting from 20 November 2019, 11:00 UTC until 21 November 2019, 14:00 UTC. We recorded 480 Sweep signals at 160 different locations. The truck was operating at 30%, 50%, and 70% relative to a peak force output of 276 kN exciting the ground vertically and each sweep lasted 15 seconds starting with 7 Hz increased up to 120 Hz. We derived back azimuths of each sweep from 6 rotational sensors and calculated root mean squares of each component. We observed that within the first day, the North component of all sensors recorded the largest ground motion energy SV type of energy is dominant. The sweep sources were distributed over two North–South profiles and two East–West profiles.  While the truck moved to the east and its location moved from west to south of the rotational sensors, the signals dominate more and more on the East component.. From our preliminary results, we state that although having different signal to noise ratios all rotational sensor calculated the direction of each sweep. Thus, we can follow the movements of vibroseis truck using all rotational sensors.

How to cite: Izgi, G., Eibl, E., Krüger, F., and Bernauer, F.: Investigating Vibroseis Sweeps using 6 Rotational Sensors in Fürstenfeldbruck, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5701, https://doi.org/10.5194/egusphere-egu23-5701, 2023.

EGU23-5955 | ECS | Orals | SM2.1

Two-dimensional phase unwrapping algorithm aided high-precision source positioning with DAS 

Jianhui Sun, Yuyao Wang, Jialei Zhang, Anchi Wan, Shibo Zhang, Zhenyu Ye, Fulie Liu, Gulan Zhang, and Zinan Wang

Seismic monitoring requires high temporal-spatial resolution and low deployment cost. Distributed acoustic sensing (DAS), as an emerging sensing technology for recording seismic data in recent years, can leverage communication cables for seismic monitoring, providing strong support for more intensive and real-time observation of geological activity. However, the traditional DAS phase unwrapping algorithms (PUAs) derived from Itoh requires the phase difference of adjacent pixels to be less than π, and thus make mistakes in the case of severe noise or large disturbance. In this paper, to the best of our knowledge, two-dimensional (2D) PUA is used to obtain seismograms in DAS for the first time. Satisfactory phase unwrapping is achieved by the 2D PUA method based on the transport of intensity equation (TIE), due to its robustness and noise immunity. Dynamic strain measurements in 80 m straight fiber-optic cable using homemade high-performance DAS, combined with TIE-based 2D PUA produce high-quality seismograms. Time Difference of Arrival (TDOA) Algorithm is applied based on the sensing signal of reliable channels in the seismograms, realizing the high-precision localization of the source. 2D PUAs apply to all phase-demodulation-based sensing techniques and are suitable for recovering spatially correlated objects such as seismic waves, thus having great potential in the field of seismic monitoring.

How to cite: Sun, J., Wang, Y., Zhang, J., Wan, A., Zhang, S., Ye, Z., Liu, F., Zhang, G., and Wang, Z.: Two-dimensional phase unwrapping algorithm aided high-precision source positioning with DAS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5955, https://doi.org/10.5194/egusphere-egu23-5955, 2023.

EGU23-6189 | ECS | Orals | SM2.1

Contribution of spatial features for classifying seismic events from Distributed Acoustic Sensing (DAS) data streams 

Camille Huynh, Clément Hibert, Camille Jestin, Jean-Philippe Malet, and Vincent Lanticq

Distributed Acoustic Sensing (DAS) is an acoustic sensor instrument that turns a single optical fiber into a dense array of thousands of equally spaced seismometers. Geoscientists and companies have an interest in investing in DAS technologies for better understanding the Earth by observing natural and anthropogenic seismic events or assisting in large infrastructure monitoring with low installation and maintenance costs. However, this type of instrument generates a significantly larger amount of data than conventional seismometers, data that can be complex to store, exploit and interpret.

Several strategies for classifying seismic events from fiber-optics DAS data exist in the scientific literature. Conventional approaches rely on the use of features that describe the waveforms and frequency content of signals recorded individually at virtual stations along the fiber; they do not integrate the spatial density of information permitted by DAS. Several studies on dense seismological arrays have introduced similarity measures between the different time series data such as cross-correlations, dynamic time warping (DTW) or compression-based dissimilarity.

This study aims to quantify the contribution of spatial features for DAS data streams classification. We have chosen to explore spatial features related to both standard statistical measures (e.g., spatial mean, median, skewness, kurtosis), and advanced signal processing measures (e.g., auto-correlations, cross-correlations, DTW). This set of measures allows enriching a list of already used time series features which includes waveform, spectrum and spectrogram. A Random Forest (RF) classifier is then trained, and a Random Markov Field (RMF) algorithm is used after classification to account for redundant spatial and temporal information.

The evaluation of the spatial feature contribution is based on the output of the RF-RMF processing chain. Anthropogenically-triggered seismic data were acquired at the FEBUS Optics test bench. We consider five seismic sources: footsteps, impacts, excavators, compactor and fluid leaks. A class of noise is added as the RF-RMF algorithm is developed for processing DAS streams inherently affected by  noise.  Accurate  classification results can be obtained using only time features, and ongoing tests show a 2% increase in the correct classification rate with the use of both time and spatial features. The improvement allowed by the addition of spatial features is tangible but limited on our test dataset, but we think it should have a much greater impact on natural sources and we will discuss this perspective.

How to cite: Huynh, C., Hibert, C., Jestin, C., Malet, J.-P., and Lanticq, V.: Contribution of spatial features for classifying seismic events from Distributed Acoustic Sensing (DAS) data streams, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6189, https://doi.org/10.5194/egusphere-egu23-6189, 2023.

EGU23-6379 | Posters on site | SM2.1

Rotational ground motion recordings in the West Bohemia / Vogtland region for waveform inversion for seismic moment tensors 

Stefanie Donner, Johanna Lehr, Mathias Hoffmann, Frank Krüger, Sebastian Heimann, Rafel Abreu, and Stephanie Durand

In synthetic tests, rotational ground motion recordings proved to be beneficial for the wavefrom inversion for seismic moment tensors. In a next step, we want to verify these findings using real measurements. To do so, we installed two broadband rotational collocated to translational ground motion sensors in the West Bohemia / Vogtland area in summer 2022.

The area is characterised by regular seismic swarm activity, the last one occurring in December 2021. The seismic swarms are known to be connected with crustal flow of mantle fluids. However, the detailed mechanism of this connection is not well understood yet. Full seismic moment tensors, especially their non-double-couple part, will contribute to investigate the connection between swarm activity and fluid flow. So far, a lacking number of moment tensors and difficulties in the reliability of the non-double-couple part hampered the analysis in the study area. Including rotational ground motion recordings to waveform inversion will help to overcome these difficulties.

In seven months, we have recorded 120 events with magnitudes larger than M ≥ 0 in a distance of up to 35 km, thereof 35 around Nový Kostel, the center of the swarm activity. Considering that rotational sensors are about 2-4 times less sensitive than translational sensors (depending on the local phase velocity of the location) this is already a great success. Here, we show details of the sensor installations, first data analysis, and an estimate on the magnitude of completeness from rotational measurements.

How to cite: Donner, S., Lehr, J., Hoffmann, M., Krüger, F., Heimann, S., Abreu, R., and Durand, S.: Rotational ground motion recordings in the West Bohemia / Vogtland region for waveform inversion for seismic moment tensors, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6379, https://doi.org/10.5194/egusphere-egu23-6379, 2023.

EGU23-6422 | ECS | Posters on site | SM2.1

Effect of shallow heterogeneities on wavefield gradients measurements 

Mirko Bracale, Romain Brossier, Helle Pedersen, and Michel Campillo

In recent years, the use of rotational sensors and DAS has become a topic of increasing interest within the seismological community because of their increasing sensitivity and affordability. We analyze the sensitivity of wavefield gradients, in the form of normal strain and rotation, to localized shallow velocity changes in a homogeneous medium.
We performed several numerical simulations, using a suitably modified 3D-SEM code, to observe, in addition to wavefield itself, the normal strain and rotation as a direct output.
We analyzed two case studies in which a velocity anomaly is placed in a homogeneous medium. In the first case the velocity change between the anomaly and the surrounding medium is 10%, in the second case 70%. We analyzed the sensitivity of these new observables in terms of phase shift and amplitude change.
We observe a very local effect of the wavefield gradients, which show larger amplitude near the boundary between the medium and the anomaly, while away from it they behave like the displacement wavefield itself.

How to cite: Bracale, M., Brossier, R., Pedersen, H., and Campillo, M.: Effect of shallow heterogeneities on wavefield gradients measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6422, https://doi.org/10.5194/egusphere-egu23-6422, 2023.

EGU23-6915 | ECS | Posters on site | SM2.1

Modeling and analysis of Distributed Acoustic Sensing (DAS) data in Geothermal environments 

Davide Pecci, Juan Porras, Michele De Solda, Francesco Grigoli, Eusebio Stucchi, and Renato Iannelli

DAS technology is particularly suitable for microseismic monitoring application in geothermal environments. This instrumentation can resist to high temperatures (up to about 100°C or more) higher than the operational temperature of standard acquisition instruments (e.g., geophones), allowing the fiber to be located very close to the reservoir. For this reason, DAS is particularly useful for induced seismicity monitoring of Enhanced Geothermal System (EGS). Being of recent development, this acquisition technology still lacks appropriate modeling and analysis tools able to handle such a large amount of data without losing efficiency. Furthermore, open-access DAS datasets are still a rarity, if compared to other geophysical datasets (e.g., seismological data). Therefore, we aim to generate an open-access synthetic (but realistic) DAS dataset that may help the geophysical community to develop “ad hoc” data analysis methods suitable for this kind of data. In the presented work we make use of the spectral element modeling software 'Salvus', developed by Mondaic, which also allows the simulation of DAS data. In particular, it outputs a strain measurement between all points defined as receivers in the simulation. Using the repositories of DAS data collected at the geothermal test site Frontier Observatory for Research in Geothermal Energy (FORGE) located in Utah (USA), we tried to simulate realistic DAS acquisition conditions of seismic events related to low-magnitude natural seismic activity from the nearby Mineral Mountains and microseismic events related to hydraulic stimulation operations for the generation of an EGS.

In order to obtain realistic synthetic data, we first analyze the spectral properties of real noise waveforms by using the Power Spectral Density (PSD) Analysis. Starting from observed PSDs we model the synthetic noise waveforms using a stochastic approach. Then we add it to the synthetic event traces and compare them with the observed ones. We finally test a semblance-based event detector on a 1-hour continuous waveforms of synthetic data to evaluate the performance of the detector in different operational conditions (e.g., different noise levels and inter-event times).

How to cite: Pecci, D., Porras, J., De Solda, M., Grigoli, F., Stucchi, E., and Iannelli, R.: Modeling and analysis of Distributed Acoustic Sensing (DAS) data in Geothermal environments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6915, https://doi.org/10.5194/egusphere-egu23-6915, 2023.

EGU23-6998 | ECS | Orals | SM2.1

Exploiting Terrestrial Meshed Optical Data Networks as Environmental Sensing Smart Grids 

Emanuele Virgillito, Stefano Straullu, Rudi Bratovich, Fransisco M. Rodriguez, Hasan Awad, Andrea Castoldi, Roberto Proietti, Andrea D'Amico, Francesco Aquilino, Rosanna Pastorelli, and Vittorio Curri

Optical networks for data transmission have become a pervasive infrastructure in the last years in order to cope with the increasing bandwidth request, thus there is a huge potential to be employed as a wide fiber optic sensing network. In the terrestrial scenario such networks are usually arranged on meshed topologies densely covering large areas of hundreths or thousands of kilometers. On the network's nodes, dedicated hardware is used to routed the data traffic between the connections' endpoints. Such nodes are interconnected by optical fiber links of hundreds of kilometers long, repeated every tenths of kilometers using optical amplifiers.

To fulfill the modern traffic requirements, optical networks are evolving towards multi-service autonomous, flexible, software defined entities based on a centralized intelligence orchestrating the networking functions and communicating with the network elements using standardized interfaces. This trend opens the perspective of using the optical network for evironmental sensing, such as earthquake detection or anthropic activities monitoring. 

Indeed, distributed acoustic sensing (DAS) systems based on Rayleigh scattering have demonstrated that optical fibers are excellent sensors of mechanical stress. However, such systems are expensive and pose some limitations on the maximum reach, so they cannot be deployed extensively. In this context, re-using the already deployed optical data infrastructure to support and integrate dedicated system sensing may be highly beneficial. In this work, we propose an optical data network architecture exposing sensing functionalities with minimum or no additional hardware simply by exploiting the pervasiveness of the telecommunication infrastructure and getting data from the physical quantities already monitored for data transmission purposes. Such architecture on a typical terrestrial optical data network is outlined in figure.

Modern coherent transceivers based on digital signal processing already track the evolution of the transmitted optical signal phase and polarization to recover the transmitted data at the receiver side. As those quantities are strongly affected by external strain, they already contain environmental information. Furthermore, some polarization-based processing can be implemented on cheaper non-coherent transceivers available at each amplifier site as data-service channel, providing several sensing sources.

In addition, further optical devices such as add-drop multiplexer or optical amplifiers typically have several other sensors already embedded (power monitors, temperature sensors) or they can be equipped with some others which can provide environmental data from other physical quantities.

The set of all such environmental data streams produced by the network elements constitutes the streaming telemetry fed to a network controller. A post-process agent may be implemented by exploiting the computational power available in typical network elements to perform local data analysis and reduce the amount of data sent to the sensing controller. By cross-processing the data coming from the network elements, a sensing controller is able to detect and localize events making the network act as a smart grid by continuously monitoring large areas and providing early warning signals.

To support our proposal, in this work we show the results of an experimental activity aimed at detecting and localizing anthropic activities in the city of Turin using a deployed fiber ring.

 

How to cite: Virgillito, E., Straullu, S., Bratovich, R., M. Rodriguez, F., Awad, H., Castoldi, A., Proietti, R., D'Amico, A., Aquilino, F., Pastorelli, R., and Curri, V.: Exploiting Terrestrial Meshed Optical Data Networks as Environmental Sensing Smart Grids, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6998, https://doi.org/10.5194/egusphere-egu23-6998, 2023.

EGU23-7309 | ECS | Orals | SM2.1

Effects of cable geometry and specific noise sources on DAS monitoring potential 

Emanuele Bozzi, Nicola Piana Agostinetti, Alan F. Baird, Carlos Becerril, Biondo Biondi, Andreas Fichtner, Sara Klaasen, Nate Lindsey, Takeshi Nishimura, Patrick Paitz, Junzhu Shen, Arantza Ugalde, Fabian Walter, Siyuan Yuan, Tieyuan Zhu, and Gilberto Saccorotti

The Distributed Acoustic Sensing (DAS) method re-purposes fiber optic cables into a very-dense array of strain/strain-rate sensors, capable of detecting different types of seismic events. However, DAS data are characterized by lower SNRs compared with standard seismic sensors, mainly because of a) strong directivity effects, 2) ground coupling inhomogeneities, and 3) site effects. Hence, beyond the array geometry, specific noise sources may reduce the potential of DAS for seismic monitoring. Previous research has already shown successful case-studies for event detection/location. Nevertheless, a coherent test on the performances of various arrays of different sizes and geometries is still lacking.

In this study, an extensive DAS database is organized for such a goal, including 15 DAS arrays that recorded at least one seismic event (located at a range of distances from the arrays). P wave arrival times are exploited to estimate the epicentral parameters with a Markov Chain Monte Carlo method. Then, to analyze the effects of cable geometry and potential sources of noise/ambiguity on the location uncertainties, a series of synthetic tests are performed, where synthetic traveltimes are modified as follows: a) adding noise with equal variance to all the DAS channels (SYNTH-01), b) adding noise characterized by an increasing variance with the distance from the event (SYNTH-02), c) simulating the mis-pick between P and S phases (SYNTH-03) and d) adding noise with a variance influenced by cable coupling inhomogeneities (SYNTH-04). Results show that the epicentral locations with automatic P wave arrival times have different degrees of uncertainty, given the geometrical relation between the event and the DAS arrays. This behavior is confirmed by the SYNTH-01 test, indicating that specific geometries provide a lower constraint on event location. Moreover, SYNTH-04 shows that simulating cable coupling inhomogeneities primarily reproduces the observed location uncertainties. Finally, some cases are not explained by any of the synthetic tests, stressing the possible presence of more complex noise sources contaminating the signals.

How to cite: Bozzi, E., Piana Agostinetti, N., F. Baird, A., Becerril, C., Biondi, B., Fichtner, A., Klaasen, S., Lindsey, N., Nishimura, T., Paitz, P., Shen, J., Ugalde, A., Walter, F., Yuan, S., Zhu, T., and Saccorotti, G.: Effects of cable geometry and specific noise sources on DAS monitoring potential, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7309, https://doi.org/10.5194/egusphere-egu23-7309, 2023.

EGU23-7563 | ECS | Posters on site | SM2.1

TwistPy: An open-source Python toolbox for wavefield inertial sensing techniques 

David Sollberger, Sebastian Heimann, Felix Bernauer, Eva P. S. Eibl, Stefanie Donner, Céline Hadziioannou, Heiner Igel, Shihao Yuan, and Joachim Wassermann

In the past decade, significant progress has been made in the acquisition and processing of seismic wavefield gradient data (e.g., recordings of ground strain and rotation). When combined with conventional multicomponent seismic data, wavefield gradients enable the estimation of local wavefield properties (e.g., the local wave speed, the propagation direction, and the wave type) and the reconstruction of spatially under-sampled seismic wavefields. However, the seismological community has yet to embrace wavefield gradient data as a new observable.

We present TwistPy (Toolbox for Wavefield Inertial Sensing Techniques), an open-source software package for seismic data processing written in Python. It includes routines for single-station polarization analysis and filtering, as well as array processing tools. A special focus lies on innovative techniques to process spatial wavefield gradient data and, in particular, rotational seismic data obtained from dedicated rotational seismometers or small-aperture arrays of three-component sensors. Routines currently included in the package comprise polarization analysis and filtering in both the time domain and the time-frequency domain (for three-component and six-component data), dynamic tilt corrections, and beamforming (Bartlett, Capon, and MUSIC beamformers).  

With TwistPy, we attempt to lower the barrier of entry for the seismological community to use state-of-the art multicomponent and wavefield gradient analysis techniques by providing a user-friendly software interface.

Extensive documentation of the software and examples in the form of Jupyter notebooks can be found at https://twistpy.org.

How to cite: Sollberger, D., Heimann, S., Bernauer, F., Eibl, E. P. S., Donner, S., Hadziioannou, C., Igel, H., Yuan, S., and Wassermann, J.: TwistPy: An open-source Python toolbox for wavefield inertial sensing techniques, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7563, https://doi.org/10.5194/egusphere-egu23-7563, 2023.

EGU23-8327 | Posters on site | SM2.1

Fibre-optic dynamic strain borehole sensing at Etna volcano 

Philippe Jousset, Gilda Currenti, Rosalba Napoli, Mario Pulvirenti, Daniele Pelligrino, Christian Cunow, Graziano Larocca, Alessandro Bonaccorso, Giuseppe Leto, and Charlotte Krawczyk

Volcano monitoring has been experiencing significant improvements in recent years, yet eruption forecasting and scenarios have still lack of understanding, due to the poor observations in low amplitude events and hindered by surface external noise of similar amplitudes. Volcanic events have been shown to be accurately recorded with fiber optic techniques at the surface. In this study, we present preliminary results of fibre optic cable deployed in a new 200 m deep borehole on the southern flank of Etna at about 6 km away from the summit crater. This borehole has been designed primarily for the future deployment of a new strain sensor type. We benefited from the drilling of this new borehole to deploy a single-mode fibre optic cable. We connected an interrogator and recorded dynamic strain rate during several periods: first, in 2020 for several days during the completion of the borehole and the final stage of the drilling; second, in 2021 for several weeks during an active volcanic period; and in December 2022 during a quiet activity period of several months. We present a selection of records of noise while drilling, local volcano-tectonic earthquakes and volcanic events and tremor that occurred during those periods. These examples show the benefit of deploying a fibre in a borehole far from the active area and demonstrate the great variety of signals fibre optic can record is such configuration.

How to cite: Jousset, P., Currenti, G., Napoli, R., Pulvirenti, M., Pelligrino, D., Cunow, C., Larocca, G., Bonaccorso, A., Leto, G., and Krawczyk, C.: Fibre-optic dynamic strain borehole sensing at Etna volcano, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8327, https://doi.org/10.5194/egusphere-egu23-8327, 2023.

EGU23-8569 | Posters on site | SM2.1

Monitoring a commercially operating submarine telecom cable network in the Guadeloupe archipelago (Lesser Antilles) using Brillouin Optical Time Domain Reflectometry (BOTDR) 

Marc-Andre Gutscher, Lionel Quetel, Giuseppe Cappelli, Jean-Gabriel Quillin, Christophe Nativelle, Jean-Frederic Lebrun, and Melody Philippon

Submarine telecom cables criss-cross the oceans, connecting islands to continents and providing internet, financial and media services to consumers all around the world. Laser reflectometry as well as other optical techniques can potentially transform the optical fibers in these cables into sensors which can detect vibrations and ground motion from earthquakes, ocean waves, currents as well as permanent deformation of the seafloor. The goal of the ERC (European Research Council) funded project - FOCUS is to apply laser reflectometry on submarine fiber optic cables to detect deformation at the seafloor using BOTDR (Brillouin Optical Time Domain Reflectometry). This technique is commonly used monitoring large-scale engineering infrastructures (e.g. - bridges, dams, pipelines, etc.) and can measure very small strains (<< 1 mm/m) at very large distances (10 - 200 km), but until now has never been used to study movements at the seafloor.

 

Within the framework of the FOCUS project, and in collaboration with the “Conseil Regional” of Guadeloupe, in 2022 we began long-term monitoring of a network of submarine telecom cables that link the islands of the Guadeloupe archipelago. These cables connect the larger island of Basse Terre and Grande Terre to the smaller southern islands of Les Saintes, Marie Galante and La Desirade, with segment lengths ranging from 30 to 70 km. This network was deployed recently (in 2019) and is the property of the Conseil Regional of Guadeloupe, operated with the assistance of Orange. All cables contain twelve fiber pairs, of which three pairs are in use by mobile phone operators and thus unused fibers were available for this scientific monitoring project. In June 2022, we established BOTDR baselines on 8 optical fiber segments, in several cases in both directions. In December 2022, we repeated the measurements of the same fiber segments, allowing us to detect any strain along the cable over this period.

 

Here, we report that using the BOTDR technique, we detect significant strain signals  (50 micro-strain and more) in several locations along the cable network. These signals, which can be positive (elongation) or negative (shortening) occur typically in areas of steep seafloor slopes or in submarine valleys/canyons. Our tentative interpretation is that stretching and shortening of the cable (representing about 1 cm over a few hundred meters) is occurring, most likely due to sea-bottom currents. These currents may be related to the late summer/early autumn hurricane season, with the passage of tropical storm Fiona in Sept. 2022 dropping heavy rains, causing torrential floods and debris flows in some of the larger rivers with possible impacts further offshore. A longer time-series and more detailed analysis are necessary to test this preliminary hypothesis.

How to cite: Gutscher, M.-A., Quetel, L., Cappelli, G., Quillin, J.-G., Nativelle, C., Lebrun, J.-F., and Philippon, M.: Monitoring a commercially operating submarine telecom cable network in the Guadeloupe archipelago (Lesser Antilles) using Brillouin Optical Time Domain Reflectometry (BOTDR), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8569, https://doi.org/10.5194/egusphere-egu23-8569, 2023.

EGU23-8851 | ECS | Orals | SM2.1

Using Rotational Motions to understand material damage in Civil Engineering structure 

Anjali Dhabu, Felix Bernauer, Chun-Man Liao, Celine Hadziioannou, Heiner Igel, and Ernst Niederleithinger

The increasing evidence of rotational motions due to earthquakes is now motivating civil engineers to investigate the effects of rotational ground motions on structures. With the advancement in instrumentation techniques, rotational sensors have been developed in the past few years, which can measure three components of rotational waves in addition to the translational waves. Conventionally, buildings are designed to withstand horizontal and vertical translational ground motions to minimize the damage to human life and financial losses during an earthquake. Damage to the structure is identified at two levels; (i) structural and (ii) material. The structural damage in reinforced concrete buildings is visible in the form of cracks and spalling concrete, which reduces the overall load-carrying capacity of the building. The damage at the material level is not visible to the human eye. This damage can be identified using coda wave interferometry techniques. In this method, a high cross-correlation between the coda of two waves passing a point on different days of experiment indicates a negligible change in the shear wave velocity of the material. In comparison, a lower cross-correlation signifies considerable change in the material properties.    

In order to understand how rotational motions affect reinforced concrete structures and how these can be simulated, the present work makes a novel attempt to use the newly developed rotation measuring sensors, BlueSeis 3A and IMU50, to understand the damage in a model concrete bridge structure (BLEIB). We employ advanced sensors in addition to conventional broadband and ultrasonic sensors on the 24m long two-span continuous reinforced concrete bridge equipped with various non-destructive sensing techniques and subjected to a variable pre-tension force of up to 450kN and various static loads. As an initial analysis, we first identify the bridge's first three fundamental frequencies and mode shapes from both recorded translational and rotational data. The analysis shows that the same fundamental frequencies are obtained from the recorded translational and rotational data. However, we expect to see a difference in the mode shapes. Theoretically, rotations are maximum at the bridge support and minimum at the centre of the bridge span. This behaviour is the reverse of what we observe from translational motions, where maximum translations are observed at the centre of the span while minimum at the supports. As the study plans to simulate rotational motions for reinforced concrete structures, a finite element model of the prototype bridge is also developed, and the fundamental frequencies and mode shapes of the model are validated with those obtained from the recorded data. This work shall be extended to applying coda wave interferometry to the rotational data recorded on the bridge to understanding the change observed in material properties when the bridge is subjected to active and passive forces.

How to cite: Dhabu, A., Bernauer, F., Liao, C.-M., Hadziioannou, C., Igel, H., and Niederleithinger, E.: Using Rotational Motions to understand material damage in Civil Engineering structure, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8851, https://doi.org/10.5194/egusphere-egu23-8851, 2023.

EGU23-9089 | ECS | Orals | SM2.1

Detecting seismo-volcanic events based on inter-channel coherency of a DAS cable 

Julius Grimm, Piero Poli, and Philippe Jousset

Distributed Acoustic Sensing (DAS) has been successfully employed to monitor volcanic seismicity and to infer volcanic subsurface structures. Here, we analyse data recorded in September 2018 at Mount Etna by the 9N seismic network. The multi-instrument network includes a 1.3 km long fibre-optic cable that was buried 2-2.5 km away from the main craters. Additionally, 15 geophones were installed along the trajectory of the DAS cable, allowing for a comparison of strain-rate and ground velocity data.
During the acquisition period, tiny seismic events, likely caused by fluid movement and degassing, are visible with inter-event times in the range of 1 min. Volcanic explosions and volcano-tectonic earthquakes also occur frequently. We detect events over all frequency ranges by calculating the coherence matrix for very short time windows (stacking 15 windows of 5 seconds length). An eigendecomposition of the coherence matrices allows to extract the first eigenvectors, corresponding to the dominant source in the time window. The principal eigenvectors can be clustered to find groups of events with similar source properties. We also use the principal eigenvector of already known events as a matched filter to scan the whole dataset. The results of the DAS cable are compared to the observations of the geophone array. While largely obtaining similar findings, the DAS cable seems to better capture high-frequency features of certain events. We also explore the effects of stacking and downsampling of the DAS data prior to detection, which influences both resolution and computational efficiency of the algorithm.

How to cite: Grimm, J., Poli, P., and Jousset, P.: Detecting seismo-volcanic events based on inter-channel coherency of a DAS cable, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9089, https://doi.org/10.5194/egusphere-egu23-9089, 2023.

EGU23-9312 | Orals | SM2.1

Six-component wave type fingerprinting and filtering 

David Sollberger, Nicholas Bradley, Pascal Edme, and Johan O. A. Robertsson

We present a technique to automatically classify the wave type of seismic phases that are recorded on a single six-component recording station (measuring both three components of translational and rotational ground motion) at the earth's surface. We make use of the fact that each wave type leaves a unique 'fingerprint' in the six-component motion of the sensor. This fingerprint can be extracted by performing an eigenanalysis of the data covariance matrix, similar to conventional three-component polarization analysis. To assign a wave type to the fingerprint extracted from the data, we compare it to analytically derived six-component polarization models that are valid for pure-state plane wave arrivals. For efficient classification, we make use of the supervised machine learning method of support vector machines that is trained using data-independent, analytically-derived six-component polarization models. This enables the rapid classification of seismic phases in a fully automated fashion, even for large data volumes, such as encountered in land-seismic exploration or ambient noise seismology. Once the wave-type is known, additional wave parameters (velocity, directionality, and ellipticity) can be directly extracted from the six-component polarization states without the need to resort to expensive optimization algorithms.

We illustrate the benefits of our approach on various real and synthetic data examples for applications such as automated phase picking, aliased ground-roll suppression in land-seismic exploration, and the rapid close-to real time extraction of surface wave dispersion curves from single-station recordings of ambient noise. Additionally, we argue that an initial step of wave type classification is necessary in order to successfully apply the common technique of extracting phase velocities from combined measurements of rotational and translational motion.

How to cite: Sollberger, D., Bradley, N., Edme, P., and Robertsson, J. O. A.: Six-component wave type fingerprinting and filtering, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9312, https://doi.org/10.5194/egusphere-egu23-9312, 2023.

EGU23-9314 | ECS | Orals | SM2.1

Using Distributed Fiber-optic Sensing for Tracking Caprock Fault Activation Processes 

Verónica Rodríguez Tribaldos, Chet Hopp, Florian Soom, Yves Guglielmi, Paul Cook, Tanner Shadoan, Jonathan Ajo-Franklin, Michelle Robertson, Todd Wood, and Jens Birkholzer

Identifying and monitoring the reactivation of faults and opening of fractures affecting low permeability, sealing formations in natural underground storage complexes such as Carbon Capture and Storage projects and Nuclear Waste repositories is essential to ensure storage integrity and containment. Although passive seismic monitoring can be effective for detecting induced failure, stress accumulation and fault reactivation can occur aseismically in clay-rich formations, preventing early failure to be recognized. Here, we investigate the potential of applying strain monitoring with fiber-optics sensing technologies to assess in-situ changing stress conditions at high spatial and temporal resolution.

We present results of fiber-optic sensing monitoring during the FS-B experiment, a controlled activation of a fault zone affecting the Opalinus Clay Formation in the Mont Terri underground Laboratory (Switzerland). Six constant flowrate water injections induced the hydraulic opening of the fault. A hydraulic connection between the injector and a monitoring borehole occurred, developing a flow path sub-parallel to the fault strike. A 2 km long fiber-optic cable looped through 10 monitoring boreholes surrounding and crossing the fault zone was used for distributed acoustic and strain sensing (DAS and DSS) before, during and after injection. Continuous low-frequency (< 1 Hz) DAS data reveals mechanical strain associated with fault reactivation. Increasing extensional strain is recorded near the point of injection and near the newly formed hydraulic flow path, reaching a value of ~150 μɛ. Post-activation residual strain of ~60 μɛ suggests irreversible fault zone deformation. Smaller strain changes are recorded above and below the high pressure flow path, suggesting a mechanically disturbed zone larger than the leakage zone. Low-frequency DAS data are consistent with co-located DSS strain data, local, 3D displacement measurements of fault movements and P-wave velocity anomalies derived from Continuous Active Source Seismic Monitoring (CASSM). Our results are promising and demonstrate the potential of fiber-optic sensing as a powerful tool for monitoring spatio-temporal evolution of fault reactivation processes and leakage in clay formations induced by fluid pressurization.

How to cite: Rodríguez Tribaldos, V., Hopp, C., Soom, F., Guglielmi, Y., Cook, P., Shadoan, T., Ajo-Franklin, J., Robertson, M., Wood, T., and Birkholzer, J.: Using Distributed Fiber-optic Sensing for Tracking Caprock Fault Activation Processes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9314, https://doi.org/10.5194/egusphere-egu23-9314, 2023.

EGU23-9629 | ECS | Posters on site | SM2.1

Monitoring material properties of civil engineering structures with 6C point measurements 

Felix Bernauer, Shihao Yuan, Joachim Wassermann, Heiner Igel, Celine Hadziioannou, Frederic Guattari, Chun-Man Liao, Ernst Niederleitinger, and Eva P. S. Eibl

Observing motion within a building in six degrees of freedom (three components of translational motion plus three components of rotational motion) opens completely new approaches to structural health monitoring. Inspired by inertial navigation, we can monitor the absolute motion of a building or parts of it without the need for an external reference. Rotational motion sensors can directly measure harmful torsional modes of a building, which has always been challenging and prone to errors when using translation sensors only. Currently, we are developing methodologies including rotational motion observations for monitoring of material parameters in order to locate and characterize structural damage. Within the framework of the GIOTTO project (funded by the German Federal Ministry for Education and Research, BMBF) we explore these approaches.

Here, we introduce a newly developed 6C sensor network for structural health monitoring. It consists of 14 inertial measurement units (IMU50 from exail, former iXblue, France) that were adapted to the needs of seismology and structural health monitoring. We performed experiments at the BLEIB test structure of the Bundesanstalt für Materialforschung und -prüfung (BAM), a 24 m long concrete beam serving as a large scale bridge model. We present results on detecting changes in material properties (seismic wave speed) of the beam with varying pre-stress and load, as derived from a novel approach by comparing amplitudes of translational to rotational motions at a single measurement point. We compare our findings to results obtained with coda wave interferometry using rotational as well as translational motions.

How to cite: Bernauer, F., Yuan, S., Wassermann, J., Igel, H., Hadziioannou, C., Guattari, F., Liao, C.-M., Niederleitinger, E., and Eibl, E. P. S.: Monitoring material properties of civil engineering structures with 6C point measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9629, https://doi.org/10.5194/egusphere-egu23-9629, 2023.

EGU23-9641 | Posters on site | SM2.1

Loops of slack in dark fiber and their effect on interferometric analysis of ambient noise – symptoms, consequences and remedies 

Christopher Wollin, Leila Ehsaninezhad, Johannes Hart, Martin Lipus, and Charlotte Krawczyk

Seismic microzonation and ambient noise tomography via Distributed Acoustic Sensing (DAS) may contribute to the seismic hazard assessment and the exploration or monitoring of utilizable and utilised subsurface volumes at favorable costs. However, numerous technical aspects remain under investigation to further maturate this innovative seismological approach – particularly when applied to dark telecommunication fibers. For instance unknown coupling of the fiber to the ground or presence of loops of slack fiber may disturb the regular measuring of the stringed virtual sensors.

 

In this study, we investigate how loops of slack fiber affect the results of passive ambient tomography, a particularly appealing exploration approach due to its low footprint. We present results obtained with DAS recordings on purposefully installed as well as dark telecommunication optic fiber. Sledgehammer blows were recorded on an optic fiber laid out in an urban heating tunnel before and after introducing several loops of slack. The loops coiled up fractions and multiples of the utilized gauge length and were spaced in sufficient distance to independently analyze the surrounding wavefield. Discontinuous wavefronts can be observed once the coiled fiber exceeds the gauge length. Similar observations were made on the virtual shot gathers calculated along a 4.5 km long segment of dark fiber along a major road in the city of Berlin, Germany. We show how the loops of slack affect the further processing with respect to ambient noise tomography. On average, the removal of virtual sensors identified to be located in coiled fiber reduces the shear-wave velocities in the resulting model.

 

We conclude that the careful removal of virtual sensors within loops of slack is a mandatory processing step towards ambient noise tomography with linear DAS arrays. However, the calculation of virtual shot gathers can help to reveal the affected fiber segments.

How to cite: Wollin, C., Ehsaninezhad, L., Hart, J., Lipus, M., and Krawczyk, C.: Loops of slack in dark fiber and their effect on interferometric analysis of ambient noise – symptoms, consequences and remedies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9641, https://doi.org/10.5194/egusphere-egu23-9641, 2023.

EGU23-10767 | ECS | Posters on site | SM2.1

Exploring multiscale nonlinear NDTs for damage detection in concrete structures 

Marco Dominguez-Bureos, Celine Hadziioannou, Niklas Epple, Camila Sanchez Trujillo, and Ernst Niederleithinger

It has been shown that non-destructive tests (NDTs) based on nonlinear wave propagation are more sensitive to detecting very small damages in concrete structures than linear techniques. With the aim of exploring the nonlinear effects in civil structures as a damage indicator, we perform a 1-day multiscale vibration monitoring of a test bridge equipped with a pretension system.

We used the pretension system to subject the specimen to eight compression states in its longitudinal direction (400kN at the highest, and 280kN at the lowest). At every compression state, we struck the structure in the vertical direction three times at two locations on the bridge with an impulse source. Throughout the whole experiment, we recorded seismic ambient noise at different frequency bands with a 14-IMU50-sensor array to measure the acceleration and rotation rate, a 14-geophone array with a 4.5 Hz natural frequency, a DAS system, and 4 pairs of ultrasound transducers; the internal temperature of the concrete was also recorded.

At the structural scale (from 1 to 40 Hz) we were able to observe different responses of the structure to pre-tension changes, depending on where the measurement took place in relation to the vertical support pillars by estimating relative velocity changes using the Coda Wave Interferometry stretching processing technique.

At the material scale (ultrasound regime) we can observe temperature-dependent slow dynamics features related to changes in the seismic velocity of the concrete as a consequence of vertical strikes, and its recovery process that returns its physical properties to a steady state after the action of the impulse source.

With this work, we work towards the development of new NDTs that are increasingly sensitive to small cracks and imperfections using conventional and non-conventional seismic instruments to measure linear and nonlinear wave propagation.

How to cite: Dominguez-Bureos, M., Hadziioannou, C., Epple, N., Sanchez Trujillo, C., and Niederleithinger, E.: Exploring multiscale nonlinear NDTs for damage detection in concrete structures, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10767, https://doi.org/10.5194/egusphere-egu23-10767, 2023.

EGU23-11782 | ECS | Posters on site | SM2.1

A workflow to generate DAS based earthquake catalog, applied to an offshore telecommunication cable in central Chile 

Marie Baillet, Alister Trabattoni, Martijn Van Den Ende, Clara Vernet, and Diane Rivet

Fiber-optic Distributed Acoustic Sensing (DAS) is of critical value for the expansion of seismological networks, particularly in regions that are hard to instrument. The work presented here is part of the 5-year ERC ABYSS project, which aims at building a permanent seafloor observatory to increase our ability to capture low magnitude seismic signals from the subduction fault zone in the DAS data recorded by offshore telecommunication cables along the central coast of Chile.

In preparation for this project, a first experiment named POST was conducted from October to December 2021 on a submarine fiber-optic cable connecting the city of Concón to La Serena. DAS data were recorded continuously for 38 days over a distance of 150 km from Concón, constituting more than 36700 virtual sensors sampling at 125 Hz. This experiment provided an opportunity to anticipate what will be recorded over the next 5 years of the project, and to allow us to develop routines that will be applied later for real-time data processing.

As a first step, we developed an automated routine for generating a preliminary earthquake catalog, comprising various conventional signal processing steps, including data denoising, change-point detection, and separating seismic events from transient instrumental noise making use of the two-dimensional character of the DAS data. Over a span of 38 days (worth 72 TB of data), our pipeline detected more than 900 local, regional, and teleseismic events with local magnitudes down to ML < 2 (based on the Centro Sismológico Nacional (CSN) public catalog). The size of our catalog, enriched with numerous off-shore events, is a significant improvement over the current CSN catalog, which may aid future studies into the Chilean margin subduction zone seismicity.

How to cite: Baillet, M., Trabattoni, A., Van Den Ende, M., Vernet, C., and Rivet, D.: A workflow to generate DAS based earthquake catalog, applied to an offshore telecommunication cable in central Chile, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11782, https://doi.org/10.5194/egusphere-egu23-11782, 2023.

EGU23-11842 | Orals | SM2.1

Using path-integrated strain in Distributed Acoustic Sensing 

Alister Trabattoni, Francesco Biagioli, Claudio Strumia, Gaetano Festa, Martijn van den Ende, Diane Rivet, Anthony Sladen, Jean-Paul Ampuero, Jean-Philippe Metexian, and Éléonore Stutzmann

Distributed Acoustic Sensing (DAS) is becoming a well-established technology in seismology. For historical and practical reasons, DAS manufacturers usually provide instruments that natively record strain (rate) as the principal measurement. While at first glance strain recordings appear similar to particle motion (displacement, velocity, acceleration) waveforms, not all of the seismological tools developed over the past century (e.g., magnitude estimation, seismic beamforming, etc.) can be readily applied to strain data. Notably, the directional sensitivity of DAS differs from conventional particle motion sensors, and DAS experiences an increased sensitivity to slow waves, often composed of highly scattered waves that are challenging to analyze. To address these issues, several strategies have been already proposed to convert strain rate measurements to particle velocity.

Based on a previously proposed mathematical formalism, we stress some fundamental differences between path-integrated strain and conventional displacement measurements. DAS inherently records arc length variation of the cable which is a relative motion measurement along a curvilinear path. We show that if the geometry of the DAS deployment is adapted to the wavefield of interest, path-integrated strain can be used to closely approximate the displacement wavefield without the need of additional instruments. We validate this theoretical result using collocated seismometers, discuss the limitations of this approach, and show two benefits: enhancing direct P-wave arrivals and simplifying the magnitude estimation of seismic events. While using path integrated strain is in some aspects more challenging, it achieves flat (hence lower) noise levels both in frequency and wavenumber. It also provides better sensitivity to high velocity phases, and permits the direct application of conventional seismological tools that are less effective when applied to the original strain data.

How to cite: Trabattoni, A., Biagioli, F., Strumia, C., Festa, G., van den Ende, M., Rivet, D., Sladen, A., Ampuero, J.-P., Metexian, J.-P., and Stutzmann, É.: Using path-integrated strain in Distributed Acoustic Sensing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11842, https://doi.org/10.5194/egusphere-egu23-11842, 2023.

EGU23-12213 | ECS | Posters on site | SM2.1

Near-surface seismic characterisation of a railway embankment slope using fibre-optic distributed acoustic sensing 

Giuseppe Maggio, Andrew Trafford, and Shane Donohue

The behaviour of geological slopes during seasonal weather patterns represents one of the challenges for assessing the geotechnical state of health of the ageing infrastructures. In the presence of man-made soil infrastructure slopes, rainfall and prolonged dry periods can cause cycles of swelling and shrinking of the ground that could potentially compromise their structural integrity. Recent research has found that time-lapse velocity monitoring, has the potential to provide information on climate-related deterioration of geotechnical infrastructure. Variations of the ground conditions could manifest as changes in seismic velocity, detectable through the seasons and after extreme weather events.

In this work, we perform seismic imaging and velocity-monitoring of a critical railway embankment in the United Kingdom using fibre optic distributed sensing (DAS). The study area is a 6 m tall, and 350 m long embankment slope built more than 100 years ago in the outskirts of London (Surrey). The railway is currently utilised mostly by commuter trains. Since August 2022, a passive DAS dataset rich in train signals has been acquired. data acquisition will continue until July 2023. Furthermore, periodic active surveys have been conducted along the slope.

Firstly, to validate the seismic response of the fibre (i.e., maximum usable frequencies based on the gauge length), we calculate and compare surface wave dispersion curves derived from both DAS and geophones using passive ambient noise, train signals and active sledgehammer shots. As a result, we obtain consistent and comparable dispersion curves ranging from ~200 m/s at 10 Hz to ~140m/s at 40 Hz. 

Secondly, we invert, using global search algorithms, DAS-derived dispersion curves for 1D depth-velocity models to identify and clarify the trend of the near-surface (top 10 m) seismic structures. 

Thirdly, we apply seismic interferometry and moving window cross-spectral techniques to measure changes in seismic velocity at the embankment using the 6-month passive DAS data acquired so far. 

The ultimate goal of this project is to develop a geophysical tool diagnostic of geotechnical deterioration of critical infrastructures by linking together DAS-based seismic observations, temporal seismic velocity changes, weather data and laboratory-based soil sample tests.

How to cite: Maggio, G., Trafford, A., and Donohue, S.: Near-surface seismic characterisation of a railway embankment slope using fibre-optic distributed acoustic sensing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12213, https://doi.org/10.5194/egusphere-egu23-12213, 2023.

EGU23-12740 | ECS | Orals | SM2.1

Coherence-based Amplification of Rayleigh Waves from Urban Anthropogenic Noise recorded with Distributed Acoustic Sensing 

Leila Ehsaninezhad, Christopher Wollin, Benjamin Schwarz, and Charlotte Krawczyk

At a local scale, e.g. in urban settlements, seismic subsurface characterization requires implementing experiments at high spatial resolution. Distributed acoustic sensing (DAS) provides the opportunity of using pre-existing fiber optic cables as dense receiver arrays, thus potentially reducing the effort for active seismic surveying in urban areas. Due to their small footprint, passive experiments appear particularly appealing. However, extracting coherent signals in an urban environment, i.e. in the presence of anthropogenic activity in the receivers' vicinity, remains a challenge.

 

In this study, we present results from combining the well known technique of Multichannel Analysis of Surface Waves (MASW) with the coherency-based enhancement of wavefields. The investigation is based on a DAS dataset acquired along a major road in Berlin, Germany. We analyse a 4.5 km long straight subsegment of a dark fiber that was sampled at 8 m intervals with 1000 Hz over a period of 15 days. After temporal decimation and the interferometric analysis, clear causal and a-causal branches of Rayleigh-surface waves emerge in the virtual shot gathers.

 

In the further processing, we employ coherence-based enhancement of wavefields to amplify the Signal to Noise Ratio of the virtual shot gathers. Compared to the traditional workflow of ambient-noise tomography the modified one yields improved dispersion curves particularly in the low-frequency part of the signal. This leads to an increased investigation depth along with lower uncertainties in the inversion result. The final velocity model reaches depths down to 300 m. We show that the application of coherence-based enhancement of the virtual shot gathers in the MASW-workflow may significantly relax the necessity of collecting long baselines for passive tomography in urban environments.

How to cite: Ehsaninezhad, L., Wollin, C., Schwarz, B., and Krawczyk, C.: Coherence-based Amplification of Rayleigh Waves from Urban Anthropogenic Noise recorded with Distributed Acoustic Sensing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12740, https://doi.org/10.5194/egusphere-egu23-12740, 2023.

EGU23-13600 | Orals | SM2.1

Long-awaited and delayed Transportable Highest grade of Fiber Optic Gyroscope for Seismology 

Frédéric Guattari, Guillaume Lenogue, Kevin Gautier, Arnaud Frenois, and André Couderette

First announced at EGU2021, and said to be “released soon”, the 1C rotation seismometer which complements the blueSeis product line on the high performance segment, will be finally disclosed at EGU2023.

2019 and 2020 results have been shared about large mockup of giant Fiber-Optic Gyroscope from iXblue, having diameter as large as 1.2 meters, and the development road to reach an industrial product had been drawn. But several critical additional issues raised on the track.

Keeping in mind all the requirement of the instrument, the need for a transportable, and easily deployable instrument, the calibration capability, the possibility to push the performance pilling up the sensors, and the need for an optional orthogonal structure, we finally come to an instrumental solution with high versatility at expected performances.

The full development story will be shared, and the tests results of first production units of blueSeis-1C will be disclosed. Explanation about the various way to use it will be offered too.

Perspectives and applications using this long-awaited sensor will be presented, from ocean-bottom system tilt denoising to improved inversion of the seismic source.

How to cite: Guattari, F., Lenogue, G., Gautier, K., Frenois, A., and Couderette, A.: Long-awaited and delayed Transportable Highest grade of Fiber Optic Gyroscope for Seismology, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13600, https://doi.org/10.5194/egusphere-egu23-13600, 2023.

EGU23-13803 | ECS | Orals | SM2.1

Magnitude Estimation and Ground Motion Prediction to Harness Fiber Optic Distributed Acoustic Sensing for Earthquake Early Warning 

Itzhak Lior, Diane Rivet, Jean-Paul Ampuero, Anthony Sladen, Sergio Barrientos, Rodrigo Sánchez-Olavarría, German Alberto Villarroel Opazo, and Jose Antonio Bustamante Prado

Earthquake Early Warning (EEW) systems provide seconds to tens of seconds of warning time before potentially-damaging ground motions are felt. For optimal warning times, seismic sensors should be installed as close as possible to expected earthquake sources. However, while the most hazardous earthquakes on Earth occur underwater, most seismological stations are located on-land; precious seconds may go by before these earthquakes are detected. In this work, we harness available optical fiber infrastructure for EEW using the novel approach of Distributed Acoustic Sensing (DAS). DAS strain measurements of earthquakes from different regions are converted to ground motions using a real-time slant-stack approach, magnitudes are estimated using a theoretical earthquake source model, and ground shaking intensities are predicted via ground motion prediction equations. The results demonstrate the potential of DAS-based EEW and the significant time-gains that can be achieved compared to the use of standard sensors, in particular for offshore earthquakes.

How to cite: Lior, I., Rivet, D., Ampuero, J.-P., Sladen, A., Barrientos, S., Sánchez-Olavarría, R., Villarroel Opazo, G. A., and Bustamante Prado, J. A.: Magnitude Estimation and Ground Motion Prediction to Harness Fiber Optic Distributed Acoustic Sensing for Earthquake Early Warning, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13803, https://doi.org/10.5194/egusphere-egu23-13803, 2023.

EGU23-14093 | Posters on site | SM2.1

Six-component records of local seismicity in the Long Valley Caldera, Californica, US 

Johana Brokesova and Jiri Malek

Long Valley Caldera in the eastern part of California is a depression 32 km long and 18 km width, which was formed during a supervolcano eruption 760 000 years ago.  Weak volcanic activity manifested by hot springs, CO2 emmanations and earthhquake swarms in the caldera and neighboring Mammoth Mountain volcanic complex has been continuing until present. The seismicity in the area is the subject of intensive study. In 2016 - 2017 the monitoring system was supplemented by small-aperture array consisting of three short-period Rotaphone-D seismographs. The instruments were deployed in vaults few hundred meters apart at depts from 3.2 to 2.2 m. They are new short-period seismographs measuring three translational and three rotational components. The array enabled new methods of microearthquakes investigation. The noise from surface sources (mainly traffic along nearby highway) can be suppressed significantly by non-linear summing of redundant translational data from each Rotaphone. This enabled detection of very weak microearthquakes in the vicinity of the array with good signal-to-noise ratio. The true azimuth and phase velocity along surface are determined by two methods:  the zero-crossing point beamforming and rotation-to-translation relations. Based on these quantities, location of microearthquakes was performed and it was compared to the locations from the USGS catalogue of local earthquakes.

The six-component records in the Long Valley Caldera are extremely complex. Strong phases between P- and S-wave onsets and namely within the S-wave group are visible in most seismograms. They probably originated as reflection and refraction waves at distinctive interfaces beneath the sediment filling of the caldera. Six-component records enabled analysis of individual wavetypes in the seismograms. The seismic array was reinstalled in the summer 2021 with new data-acquisition system with bigger dynamic range (32 bits A/D converter). We expect even more sensitive measurements from this new observation. 

How to cite: Brokesova, J. and Malek, J.: Six-component records of local seismicity in the Long Valley Caldera, Californica, US, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14093, https://doi.org/10.5194/egusphere-egu23-14093, 2023.

EGU23-14444 | ECS | Orals | SM2.1

Modelling of DAS cable and ground coupling response using Discrete Particle Schemes 

Nicolas Luca Celli, Christopher J. Bean, Gareth O'Brien, and Nima Nooshiri

Since its first applications in the past decade, the use of fiber optic cables as ground motion sensors has become a central topic for seismologists, with successful applications of Distributed Acoustic Sensing (DAS) in various key fields such as seismic monitoring, structural imaging and source characterisation.

The instrument response of DAS cables however is largely unknown. Instrument response is a combination of instrument design, local site effects and ground coupling, and for DAS, the latter ones are believed to have a strong, spatially variable, but yet largely unquantified effect. This limits the application of a large number of staple seismological techniques (e.g. earthquake magnitude estimation, waveform tomography) that can require accurate knowledge of a signal’s amplitude and frequency content.

Here we present a method for accurately simulating a DAS cable and its response. The scheme is based on molecular dynamic-like particle-based numerical modelling, allowing the investigation of the effect of varying DAS-ground coupling scenarios. At first, we compute the full strain field directly, for each pair of neighbouring particles in the model. We then define a virtual DAS cable, embedded within the model and formed by a single string of interconnected particles. This allows us to control all aspects of the cable-ground coupling and their properties at an effective granular level through changing the bond strengths and bond types (e.g. nonlinearity) for both the cable and the surrounding medium. Arbitrary cable geometries and heterogeneous materials can be accommodated at the desired scale of investigation.

We observe that at the meter scale, realistic DAS materials, cable-ground coupling and the presence of unconsolidated trench materials around it dramatically affect wave propagation, each change affecting the synthetic DAS record, with differences exceeding at times the magnitude of the recorded signal. These differences show that cable coupling and local site effects have to be considered both when designing a DAS deployment and analysing its data when either true or along-cable relative amplitudes are considered.

How to cite: Celli, N. L., Bean, C. J., O'Brien, G., and Nooshiri, N.: Modelling of DAS cable and ground coupling response using Discrete Particle Schemes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14444, https://doi.org/10.5194/egusphere-egu23-14444, 2023.

EGU23-15048 | ECS | Posters on site | SM2.1

On Seismic Wave Equation Gradiometric Inversion for Density 

Marthe Faber and Andrew Curtis

It is of interest for environmental and resource applications to better characterise dynamic processes and properties of the near-surface critical zone of the solid Earth. Seismic wavefield gradiometry refers to a class of imaging techniques that estimate properties of the subsurface by calculating temporal and spatial gradients of incoming wavefields using dense array measurements, usually recorded at the Earth’s surface. One such method called wave equation inversion (WEI) has been shown to require only a few minutes of ambient seismic noise recordings to produce phase velocity maps, and shows promise for rapid field deployment.

Previous applications of WEI are based on the assumption that the 2D scalar Helmholtz wave equation adequately describes the dynamics of recorded wavefields. This approximation is severe for seismic waves because the Helmholtz equation fails to describe elastic wave dynamics. Since ambient noise recordings contain all kinds of interfering elastic wave types, the accuracy of subsurface material property estimates is compromised.

To investigate the potential to enhance the information available from WEI, we test the method synthetically using more sophisticated wave equations that represent wave propagation in the subsurface more accurately. Starting from a 3D seismic array geometry which provides wavefield gradient information both at the surface and at depth, WEI can be formulated in terms of the full elastic wave equation. From there we track approximations in both wave physics and field acquisition geometries that deplete information about the medium, eventually arriving at the conventional 2D scalar wave equation. These experiments highlight approximations that most deteriorate the solution, allowing us to target future effort to remove them.

One approximation made in all previous WEI studies is to assume that density is constant across the local array. In reality, subsurface density varies both laterally and with depth, yet remains poorly constrained in seismic imaging problems. Accurate density estimates would provide important insight into subsurface properties. This prompts us to test wavefield sensitivities to subsurface density contrasts via WEI. Synthetic results for 3D acoustic media suggest that it is possible to estimate relative density structure with WEI by using a full acoustic formulation for wave propagation along the surface. We show that using a constant density assumption for the medium can be detrimental to subsurface images, whereas the full acoustic formulation of gradiometry improves our knowledge of material properties. It allows us to estimate density as an additional material parameter as well as to improve phase velocity estimates by incorporating approximations to the density structure. By expanding this methodology to the elastic case, we will discuss the feasibility of estimating density with gradiometric WEI in the solid Earth.

How to cite: Faber, M. and Curtis, A.: On Seismic Wave Equation Gradiometric Inversion for Density, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15048, https://doi.org/10.5194/egusphere-egu23-15048, 2023.

EGU23-15050 | Orals | SM2.1

Low-frequency seismic wave sensing using coherent optical fiber networks for metrology 

Paul-Eric Pottie, Mads Tonnes, Maxime Mazouth-Laurol, Hendrix Montlavan-Leyva, Etienne Cantin, Benjamin Pointard, Hector Alvarez-Martinez, Rodolphe Le Targat, Olivier Lopez, Christian Chardonnet, and Anne Amy-Klein

Optical fiber networks are being implemented in several countries aiming at dissemination of ultra-stable time and frequency references. This enables the comparison of optical clocks, which is a key part of the roadmap towards the future redefinition of the International System of Units (SI) second. Furthermore, this enables uses in chronometric geodesy, where the sensitivity of the optical clocks to the gravitation field enables measurements of height differences as low as 1 cm [1].
The frequency signals in the optical fibers are sensitive to acoustic vibrations which are present in the ground, which is the main source of noise to the disseminated signals.
In recent years, this has enabled studies in the use of optical fiber links for the detection of earthquakes [2]. In such an approach, the measurement is the integrated noise over the fiber path. This typically allows for one to several orders of magnitudes longer range as compare to DAS techniques, but with the loss of localization along the fiber. Such integrated approaches include measurements of the total polarization change of the light along the fiber [3], or the total phase change of a coherent ultra-stable laser signal, potentially including distributed sensing techniques in submarine fibers [2,4].

Here, we will present the first quantitative studies on the use of coherent optical fiber links for seismic detection. Using a the fiber network REFIMEVE in France (see Fig. 1), we present studies on the sensitivity of coherent optical fiber links to seismic events. We describe the dependence of the sensitivity to a number of parameters like incident angle, magnitude and distance, and compare the sensitivity of a fiber link with that of conventional seismometers. We show, for a first time to our knowledge, the detection of seismic waves by a coherent optical fiber network, and we study the prospects of using such a network for the localization of earthquakes. Lastly, we discuss the principles and results of a machine learning algorithm, which enables automatic detection of earthquakes in a coherent optical fiber link.

Bibliography:
1. M. Takamoto et al., Test of general relativity by a pair of transportable optical lattice clocks, Nat. Phot., 14 (7), 411–415. doi:30210.1038/s41566-020-0619-8
2. G. Marra et al. , Ultrastable laser interferometry for earthquake detection with terrestrial and submarine cables. Science, eaat4458. doi: 10.1126/science.aat4458279
3. J.C. Castellanos et al. ,Optical polarization-based sensing and localization of submarine earthquakes. In Optical fiber communication conference (OFC) 2022, doi:26210.1364/OFC.2022.M1H.4
4. G. Marra et al., Optical interferometry–based array of seafloor environmental sensors using a transoceanic submarine cable. Science, doi: 10.1126/science.abo193

Figure 1 : Map of the French REFIMEVE fiber network, shown in red lines. Dotted lines indicates indicate the full scale of the planned network, and continuous red lines indicate links used in these studies. Blue lines indicates the linear approximations of the links. All seismometers of the RESIF network is shown by small green triangles, and seismometers used in theses studies are shown by larger, turquoise triangles.

How to cite: Pottie, P.-E., Tonnes, M., Mazouth-Laurol, M., Montlavan-Leyva, H., Cantin, E., Pointard, B., Alvarez-Martinez, H., Le Targat, R., Lopez, O., Chardonnet, C., and Amy-Klein, A.: Low-frequency seismic wave sensing using coherent optical fiber networks for metrology, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15050, https://doi.org/10.5194/egusphere-egu23-15050, 2023.

EGU23-15062 | ECS | Posters on site | SM2.1

Observing and analysing seismicity with a permanet 6C station 

Andreas Brotzer, Heiner Igel, Felix Bernauer, Joachim Wassermann, Robert Mellors, and Frank Vernon

In September 2022, a three-component rotational rate sensor (blueSeis-3A) provided by IRIS has been deployed at the underground vault of the Piñon Flat Observatory (PFO) near San Diego in California. A three-component broadband seismometer (Trillium 240s) is co-located on the granite pier, creating a 6C station for permanent observations of local and regional seismicity and wavefield studies. The permanent record is streamed online via IRIS and freely available with all required metadata (station: BlueSeis at Pinon Flat = BSPF). Additionally, the site offers observations of strain by optical fiber and vacuum laser strainmeters at PFO, allowing to study 7 components of the seismic wavefield in a quiet area with regard to seismic noise, but high seismicity (e.g. San Andreas fault zone, San Jacinto fault zone). Such a setup enables advanced studies of the seismic wavefield. Dense, large-N nodal experiments, temporarily deployed around PFO could provide dense sampling of the seismic wavefield for comparison studies. The seismic array of borehole sensors at PFO is well designed to compute array derived rotations with enables a direct comparison with the rotational record and applied methods. Moreover, the array is employed to compare array analysis with 6C methods (e.g. backazimuth estimation, wavefield separation, source tracking, local subsurface velocity changes). We present characteristics on the 6C station and preliminary analysis results.

How to cite: Brotzer, A., Igel, H., Bernauer, F., Wassermann, J., Mellors, R., and Vernon, F.: Observing and analysing seismicity with a permanet 6C station, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15062, https://doi.org/10.5194/egusphere-egu23-15062, 2023.

EGU23-15265 | ECS | Orals | SM2.1

Towards exploiting the advantages of a Standard telecom multi-fibre cable for volcano monitoring: an example from Mt. Etna 

Sergio Diaz-Meza, Philippe Jousset, Gilda Currenti, Air David, Andy Clarke, Anna Stork, Athena Chalari, and Charlotte Krawzcyk

Distributed Dynamic Strain Sensing (DDSS), also known as Distributed Acoustic Sensing (DAS), is becoming a popular tool for volcano monitoring. The sensing method relies on sending coherent light pulses into an optical fibre and measuring the phase-shift of Rayleigh back-scattered light due to strain on the fibre. This provides distributed strain rate measurements at high temporal and spatial sampling rates. Standard telecom fibres have been conventionally used for this purpose, however engineered fibres are being developed to enhance the back-scattered light, providing up to 100 times improved sensitivity in contrast to the conventional standard fibre. Despite the technical advantages of engineered fibres, standard fibres already have extensive coverage around the Earth surface, and so there is an interest in using the existing telecommunication infrastructure. In this study we compare stack DDSS data from a fibre loops made of several fibres within the same optical fibre cable, with DDSS data measured on an engineered fibre. We analyse how stacking can improve the signal quality of the recorded DDSS data. In an area located 2.5 km NE from the craters of Mt. Etna, we spliced 9 standard fibres together from a 1.5 km long cable to create a single optical path and interrogated using an iDAS unit. At the same time, we interrogated with a Carina unit a 0.5 km engineered fibre installed parallel to the standard multi-fibre cable. Both fibres were interrogated in a common period of 5 days. We use a spatial cross-correlation function to find the channel equivalences between each fibre and then stack them to evaluate the changes in the DDSS data and compare with the engineered fibre data. Our results show that, despite engineered fibres have lower noise, a stack of 5 fibres can achieve a maximum noise reduction of 20% outside of the optical noise band, in comparison to the engineered fibre. We achieved this noise reduction for our specific configuration, and so we show how the stack improvement is dependent on the type of configuration in terms of fibres stacked and length of the fibres. Our findings motivate the exploitation of multi-fibre cables in existing infrastructures, so-called dark fibres, for monitoring volcano and applications to other environments.

How to cite: Diaz-Meza, S., Jousset, P., Currenti, G., David, A., Clarke, A., Stork, A., Chalari, A., and Krawzcyk, C.: Towards exploiting the advantages of a Standard telecom multi-fibre cable for volcano monitoring: an example from Mt. Etna, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15265, https://doi.org/10.5194/egusphere-egu23-15265, 2023.

EGU23-15291 | ECS | Orals | SM2.1

Supporting the completion process of boreholes using combined fiber-optic monitoring technologies 

Johannes Hart, Martin Peter Lipus, Christopher Wollin, and Charlotte Krawzcyk

Efficient, safe and sustainable utilization of geothermal reservoirs depends on reliable well completion and monitoring technologies. Conventional borehole measurement methods can only be used after the completion process and usually show snapshots of the borehole conditions at discrete points in time. Therefore, the successful borehole completion is a risky process and mainly relies on the experience of the driller. By using distributed fiber-optic sensing technologies, it is possible to monitor all along the cable with dense spatial sampling and continuous in real-time.

In this presentation, we give insights into our newest case study in Berlin. A 450 m deep exploration well for an Aquifer Thermal Energy Storage was completed. We installed a fiber optic sensor cable along the whole production tubing, that contained several single-mode and multi-mode fibers in loose tube and tight buffered configuration. This cable allows to simultaneously measure distributed temperature (DTS), distributed acoustics (DAS) and distributed strain (DSS/DTSS) for the entire completion process.

Particularly with a combined analysis and interpretation of the different fiber-optic technologies, conventionally untraceable processes can be visualized. We are able to show changes of subsurface flow paths due to blockages. Processes to be prevented, like caving or bridging can be detected and the proper rise of gravel or cement can be surveyed. Provided to the driller in real time, subsurface uncertainties can be significantly reduced.

Monitoring geothermal wells with a fiber-optic sensing infrastructure is not only a powerful tool to reduce risks during well completion, which can lead to compromised well integrity. The installed equipment and technology can also be used to assess the well integrity over the whole cycle of the well, to ensure a longest possible lifespan.

How to cite: Hart, J., Lipus, M. P., Wollin, C., and Krawzcyk, C.: Supporting the completion process of boreholes using combined fiber-optic monitoring technologies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15291, https://doi.org/10.5194/egusphere-egu23-15291, 2023.

EGU23-15325 | Posters on site | SM2.1

Observation of the microseismic peak from Distributed Acoustic Sensing (DAS) measurements at the LSBB underground Laboratory 

Olivier Sèbe, Camille Jestin, Amaury Vallage, Stéphane Gaffet, Daniel Boyer, Alain Cavaillou, Jean-Baptiste Decitre, Charly Lallemand, Vincent Lanticq, and Olivier Rousseau

Thanks to its ability to provide dense strain rate measurements along Optical Fiber (OF) cable, the Distributed Acoustic Sensing (DAS) technique spreads over different seismic and geophysical domains. They range from exploration geophysics (Mestayer et al. 2011, Daley et al. 2013), to underground structure imaging (e.g. Ajo-Franklin et al. 2019, Cheng et al. 2021) or seismic activity and background noise monitoring (Jousset et al 2018, Nayak et al. 2021). Beyond the advantage of its dense spatial sampling and given a better understanding of its instrument response (e.g. Lindsey et al. 2020), the detection performance of these new DAS measurements also depends on its ability to precisely characterize the amplitude and phase of the seismic background noise in different environments. According to recent offshore seismic noise studies (Ugalde et al. 2021, Lior et al. 2021, Guerin et al 2022), we propose a study based on DAS recordings of the seismic background noise in an on-land quiet environment.

In 2020, a temporary seismic experiment PREMISE (PREliminary MIga Seismic Experiment) was carried out on the site of the underground low noise Laboratory (LSBB, Laboratoire Souterrain Bas Bruit) at Rustrel, France, in order to study the 3D seismic wave field properties in a pretty well-known underground geological structure. During this experiment, we deployed several kilometers of different OF in the LSBB galleries in order to create a multidirectional DAS array with a total fiber length of 10.5km and several ground-coupling conditions. We reprocessed two hours of “raw” DAS data, recorded with a FEBUS A1-R instrument, with different acquisition parameters to find the best configuration for enhancing the DAS measurement Signal to Noise Ratio. The power spectral density (PSD) of these reprocessed strain time-series reveals a peak in the background noise frequency range [0.08-0.25Hz] for gauge lengths of 90m and 150m. Independently, an estimation of the local strain field has been derived by a geodetic analysis (Spudich et al 1995) of the records from the LSBB broadband seismometers antenna. The comparison of the DAS and seismometers array-derived strain PSD shows a very good agreement with the secondary microseism peak in terms of frequency band, amplitude, and the wave field polarization, especially for DAS strain records processed with gauge-length of several tens of meters.

How to cite: Sèbe, O., Jestin, C., Vallage, A., Gaffet, S., Boyer, D., Cavaillou, A., Decitre, J.-B., Lallemand, C., Lanticq, V., and Rousseau, O.: Observation of the microseismic peak from Distributed Acoustic Sensing (DAS) measurements at the LSBB underground Laboratory, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15325, https://doi.org/10.5194/egusphere-egu23-15325, 2023.

EGU23-15589 | Posters on site | SM2.1

Variations of the system properties of a high-rise building over 1 year using a single station 6C approach. 

Yara Rossi, Konstantinos Tatsis, Yves Reuland, John Clinton, Eleni Chatzi, and Markus Rothacher

We demonstrate that the dynamic response of an engineered structure, including modeshape identification, can be obtained from just a single measurement at one position - if rotation is recorded in combination with translation. Such a single-station approach can save significant time, effort and cost when compared with traditional structural characterization using horizontal arrays. In our contribution we will focus on the monitoring of a high-rise building by tracking its dynamic properties and their variations due to environmental (e.g. temperature) and operational (e.g. wind) conditions (EOCs) over a 1-year period. We present a real-case structural identification procedure on the Prime Tower in Zurich. This is a 36-story tower of 126 m height, with a poured-in-place-concrete core and floors and precast-concrete columns; this concrete core structure, surrounded by a triple-glazed facade, is the third highest building in Switzerland. 
The building has been continuously monitored, over a 1-year period, by an accelerometer (EpiSensor), a co-located rotational sensor (BlueSeis) and a weather station located near the building center on the roof. Roof and vertical seismic arrays were deployed for short periods. The motion on the tower roof includes significant rotation as well as translation, which can be precisely captured by the monitoring station. More than 20 structural modes, including the first 6 fundamental modes, where translations are coupled with rotations, are tracked between 0.3 – 14 Hz. We will also show the variation of natural frequencies due to seasonal but also more short-term effects, in an effort to understand the effect of environmental and operational variability on structural deformation and response. Additionally, an amplification of the modes, not only during strong winds, but also during a couple of Mw 4.0 - 4.4 earthquakes at regional distance has been observed and analysed. The frequency band between 0.3 and 10 Hz is of key interest for earthquake excitation, making an investigation thereof essential. The work closes with a summary of the main benefits and potential in adopting collocated rotation and acceleration sensing for geo-infrastructure monitoring purposes.

How to cite: Rossi, Y., Tatsis, K., Reuland, Y., Clinton, J., Chatzi, E., and Rothacher, M.: Variations of the system properties of a high-rise building over 1 year using a single station 6C approach., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15589, https://doi.org/10.5194/egusphere-egu23-15589, 2023.

EGU23-15841 | Orals | SM2.1

Monitoring of elastic properties using DAS and DTS in a controlled experiment during road construction 

CharLotte M. Krawczyk, Martin P. Lipus, Johannes Hart, Christopher Wollin, Christian Cunow, and Philippe Jousset

Maintenance of infrastructure is costly and difficult to implement systematically when it spreads over wide areas, such as road or pipeline networks. In the monitoring of road ways, conventional methods to control the road integrity rely on discrete measurements in space and time. There is a large demand for innovative technologies that are able to assess the structural integrity as a whole and in regular intervals or even continuously. Distributed fiber-optic sensing opens the opportunity to measure numerous physical quantities such as temperature and strain with high spatial and temporal resolution over tens of kilometers. In addition, it is easily deployable at reasonable cost.

In order to address the issue of asphalt aging due to exposure to heavy traffic loads, we installed a fiber-optic cable into a reworked road interval and recorded fiber-optic data in a controlled experiment with numerous test vehicles of different sizes and weights. The recorded data suggests that elastic properties of the asphalt can be retrieved from the bypassing traffic. Vehicles can be characterized by the number of axes and load on the asphalt composite. In the next phase, we will monitor the aging of the test field to deduce how varying matrial properties can be better identified for geotechnical and geoscience applications.

How to cite: Krawczyk, C. M., Lipus, M. P., Hart, J., Wollin, C., Cunow, C., and Jousset, P.: Monitoring of elastic properties using DAS and DTS in a controlled experiment during road construction, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15841, https://doi.org/10.5194/egusphere-egu23-15841, 2023.

EGU23-16307 | Orals | SM2.1

Local earthquake recordings using Distributed Acoustic Sensing (DAS) at BFO 

Nasim Karamzadeh Toularoud, Ya-Jian Gao, Jérôme Azzola, Thomas Forbriger, Rudolf Widmer-Schnidrig, Emmanuel Gaucher, and Andreas Rietbrock

The application of distributed acoustic sensing (DAS) in seismology is rapidly expanding due to its ability to perform a large number of high-density measurements, i.e., distributed sensing, without using many point sensors, which is cost-effective. DAS application includes vertical seismic profiling, microseismic measurements, and hydraulic fracturing monitoring and mainly focuses on the event detection capability of  DAS data. 

Febus optics DAS interrogator (A1-R) is continuously running at German Black Forest Observatory (BFO) since May 2021, recording RAW data (selectively stored) or strain-rate data (continuously stored). Our study is in the experimental phase and focuses on testing basic concepts of DAS data, i.e., the effect of gauge-length on the amplitude of measurement and comparing the amplitude of DAS with other seismological sensors such as strain-meter array and a STS2 broadband sensor as well as synthetic simulations. Such comparison is performed using background noise characteristics (power spectral density) and examples of local and regional events that are detectable at the BFO site. 

In this study, we show examples of strain rate measurements related to local earthquakes recorded by horizontal fiber optic cables, employing two different DAS interrogators, cable types and coupling of the cables to the ground. We compared simultaneous recordings using Febus A1 DAS interrogator and OptoDAS by Febus optic and Alcatel Submarine Networks (ASN), respectively, and, concluded about the frequency and gauge-length dependent sensitivity of recordings in two cases. In addition, we compare the amplitude of DAS recordings, for example of local earthquakes, with the synthetic strain simulated  at lower frequency bands using the spectral-element method (Salvus) based on 3D media and analytic approach (Qseis) for 1D model. 

 

How to cite: Karamzadeh Toularoud, N., Gao, Y.-J., Azzola, J., Forbriger, T., Widmer-Schnidrig, R., Gaucher, E., and Rietbrock, A.: Local earthquake recordings using Distributed Acoustic Sensing (DAS) at BFO, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16307, https://doi.org/10.5194/egusphere-egu23-16307, 2023.

EGU23-16459 | ECS | Orals | SM2.1

Deep learning approach for detecting low frequency events on DAS data at Vulcano Island, Italy 

Martina Allegra, Gilda Currenti, Flavio Cannavò, Philippe Jousset, Michele Prestifilippo, Rosalba Napoli, Mariangela Sciotto, Giuseppe Di Grazia, Eugenio Privitera, Simone Palazzo, and Charlotte Krawczyk3

Since September 2021, signs of unrest at Vulcano Island have been noticed after four years of quiescence, along with CO2 degassing and the occurrence of long-period and very long-period events. With the intention of improving the monitoring activities, a submarine fiber optic telecommunications cable linking Vulcano Island to Sicily was interrogated from 15 January to 14 February 2022. Of particular interest has been the recording of 1488 events with wide range of waveforms made up of two main frequency bands (from 3 to 5 Hz and from 0.1 to 0.2 Hz).

With the aim of the automatic detection of seismic-volcanic events, different approaches were explored, particularly investigating whether the application of machine learning could provide the same performance as conventional techniques. Unlike many traditional algorithms, deep learning manages to guarantee a generalized approach by automatically and hierarchically extracting the relevant features from the raw data. Due to their spatio-temporal density, the data acquired by the DAS can be assimilated to a sequence of images; this property has been exploited by re-designing deep learning techniques for image processing, specifically employing Convolutional Neural Networks.

The results demonstrate that deep learning not only achives good performance but that it even outperforms classical algorithms. Despite providing a generalized approach, Convolutional Neural Networks have been shown to be more effective than traditional tecniques in expoiting the high spatial and temporal sampling of the acquired data. 

How to cite: Allegra, M., Currenti, G., Cannavò, F., Jousset, P., Prestifilippo, M., Napoli, R., Sciotto, M., Di Grazia, G., Privitera, E., Palazzo, S., and Krawczyk3, C.: Deep learning approach for detecting low frequency events on DAS data at Vulcano Island, Italy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16459, https://doi.org/10.5194/egusphere-egu23-16459, 2023.

In this study we use distributed acoustic sensing (DAS) on a 41-km-long submarine optical fibre (OF) cable located offshore Toulon, France. We record both the amplitude and frequency of seafloor strains induced by ocean surface gravity waves, as well as secondary microseisms. Combining the analysis of the two types of waves, we identify and localize local sources of secondary microseisms that manifest as Scholte waves generated by the reflection of oceanic gravity waves on the coastline. During the experiment, these local sources represent the most energetic contribution to the seismic noise recorded along the OF and by an onshore broad-band station located near the DAS interrogator. As a result, the characteristics of this noise are closely related to local wave conditions. One major challenge in performing seismic imaging using ambient seismic noise correlations using DAS data is that we cannot solve for the true seismic velocity because the noise wave field is dominated by local sources. To address this, we measure the incident angle of the dominant local noise sources, correct the apparent velocity using the incident angle retrieve from beamforming analysis and generate a 2D model. We then quantify the errors that arise from picking the dispersion curves of the most energetic velocities without correcting from the incident angle. Our results show that there are significant differences in velocities, with differences reaching up to several hundred meters per second. This highlights the importance of correcting these velocities before generating a tomography. Finally we evaluate an alternative strategy for a linear DAS fiber that cannot be use to localized the dominant noise source. We measure the dispersion curve of the slowest Scholte waves recorded and compare it to the corrected dispersion curves of the dominant source. Although this strategy suffers from limitation, it minimizes the error in the velocity model.

How to cite: Guerin, G. and Rivet, D.: Using localized microseismic noise sources to perform high-resolution seismic Imaging of seafloor using Distributed Acoustic Sensing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16640, https://doi.org/10.5194/egusphere-egu23-16640, 2023.

EGU23-17585 | Orals | SM2.1 | Highlight

Why high spatial resolution matters: narrow fault zone, but big effects observed by Taiwan Milun-fault Drilling and All-inclusive Sensing (Taiwan MiDAS) project 

Kuo-Fong Ma, Li-Wei Kuo, Hsin-Hua Huang, Sebastian von Specht, Chin-Jen Lin, Jing-Shan Ku, Chen-Ray Lin, En-Shi Wu, Chien-Yin Wang, and Wen-Yen Chang

Understanding fault zone dynamics in multi-scale is important to embrace the complexity of the earthquake behavior and its natural system. However, the opportunity to map and observe the fault zone behavior at depth with high spatial resolution are rare as also the challenge itself on targeting and identifying the fault zone at depth. We placed a 3D cross-fault fiber array with a downhole loop from surface to depth of 700m for Hole-A (Hanging wall site, crossing fault at depth), after drilling and coring to a frequent slip fault, Milun fault in a plate boundary zone, which ruptured during the 6 February 2018 Mw6.4 Hualien earthquake, and resulted in severe damage to several tall buildings with tens of casualties and injuries. Then, the surface segment crosses the surface fault rupture zone using commercial fiber, and to another downhole loop of 500m fiber for Hole-B (Footwall site). The high spatial resolution from distributed acoustic sensing (DAS) allows us to characterize the fault zone feature together with the retrieved core and geophysical logs after drilling through this frequent slip zone. This 3D route includes the experiment of using commercial fiber to the future application of surface rupture zone identification for seismic hazard mitigation. The project successfully retrieved the fault core associated with Milun fault zone, which could be also seen in geophysical logs with low velocity and resistivity, and mapped using Optical Fiber Sensing technique of the downhole fiber. Within the Milun fault zone, while a 20m thick fault core with grey and black gouge was discovered, a distinct seismic feature associated with this 20m fault gouge was found by its amplification of the strain records from DAS. This amplification ratio is about 2.5-3 when compared to the channels at deeper depth related to a consolidated rock material.  This amplification factor was frequency and azimuth independently, as genuinely observed from all events (e.g. local, and teleseismic earthquakes) with similar amplification factor. Our study shows that the amplification from this 20m fault gouge zone is mainly from the nature of the heterogeneous medium in elastic constant while crossing the fault zone, especially the fault core. Similar feature at surface but with wider surface rupture zone (~ 200m) was found in DAS data as well although less evidence using commercial fiber, while could be validated from the densely deployed geophones crossing the surface rupture of the 2018 Hualien earthquake. Through the depth, a high-resolution asymmetric feature of this active fault was evidenced from the downhole optical fiber and cores. This fault zone behavior would be hardly seen or confirmed without continuous viewing of the wavefields to this high spatial resolution to meter scale. Although the narrow fault gouge, the nature of its amplification in strain due to its strong material contrast from fault gouge was intriguing, and requires intensive attention to consider the contribution of the fault zone heterogeneity in the medium. This might give hints on the understanding of the observation of earthquake dynamics triggering reported worldwide after the occurrence of a mega-earthquake.

How to cite: Ma, K.-F., Kuo, L.-W., Huang, H.-H., von Specht, S., Lin, C.-J., Ku, J.-S., Lin, C.-R., Wu, E.-S., Wang, C.-Y., and Chang, W.-Y.: Why high spatial resolution matters: narrow fault zone, but big effects observed by Taiwan Milun-fault Drilling and All-inclusive Sensing (Taiwan MiDAS) project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17585, https://doi.org/10.5194/egusphere-egu23-17585, 2023.

ERE2 – Renewable energy

This study explores the potential of slow-varying components of the earth system to predict the monthly mean wind speeds over the seven homogenous climate zones of India at subseasonal to seasonal time-scales. The following set of predictors are selected for that purpose: sea-surface temperature, mean sea-level pressure, 10 m wind speed, wind speed at 850 hPa, and geopotential height at 850 hPa. With the exception of sea-surface temperature which is obtained from HadISST, the rest of the variables are obtained from the JRA55. Besides, the popular indices such as the Nino 3.4 index and the Dipole mode index are also used as predictors. The forecasts are made at 1, 2, 3, 4, and 5 months of leadtime for the monsoon months of June, July, August, and September when the wind speeds are the highest throughout the country. The regions of significant correlations of the predictor fields with the spatially-averaged wind speeds of each homogenous region are determined using the past 6 month lagged composites. Once identified, the variables over these regions are spatially averaged and are mapped to the 10 m wind speeds from JRA55, since it is the closest representation of observed wind speeds over India. This predictor-based forecasting is carried out using the following approaches: multi-linear regression, decision tree based regression, and K nearest neighbours regression. The models use data from 1958-2018 for training and 2019-2021 for testing. The deterministic predictions are evaluated using mean absolute error (MAE) and the skill compared to a climatological forecast is estimated using the root mean squared error skill score (RMSESS). Results show that different sets of predictor combinations are responsible for giving the best forecasts for individual months and leadtimes. These forecasts have MAE of  around 0.2 m/s and RMSESS values ranging from 0.5-0.7. Although we are looking at deterministic predictions here, a combination of multiple models and predictors used above can lead to the production of ensemble forecasts as well, which will be of further added value to the wind energy sector.

How to cite: Das, A. and Baidya Roy, S.: Exploiting the predictability of global teleconnections to forecast subseasonal to seasonal scale wind speeds over India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-507, https://doi.org/10.5194/egusphere-egu23-507, 2023.

EGU23-1119 * | Orals | ERE2.1 | Highlight

Meteorological challenges for renewable energy in the High Arctic 

Anna Sjöblom, Matthias Henkies, and Arthur Garreau

A transition to renewable energy is becoming increasingly more urgent in the High Arctic. In Svalbard (78°N), the previously coal based energy system is now, with a short transition period with diesel, moving to a completely renewable off-grid system. Both solar and wind energy are possible contributors to the energy mix. However, no renewable energy systems are specifically designed for the High Arctic and before implementing the systems they must be tested and adapted to Arctic conditions. Since 2020, the world’s northernmost higher education institution, The University Centre in Svalbard (UNIS), has developed a special focus on Arctic renewable energy meteorology, focussing especially on solar and wind energy. This is undertaken in close collaboration with local industry who are switching from coal mining to exporting renewable off-grid systems.

Many of the meteorological processes in the High Arctic are very different from further south with long periods of midnight sun, polar night, complex topography, low temperatures, stable stratification, snow and ice etc. What implications these processes will have on the solar and wind power are mostly unknown. To complicate matters further, numerical models are uncertain and unproved in these areas and there is a need for long-term measurements.

Long-term meteorological measurements to determine the energy potential as well as the impact of the Arctic climate have commenced around Longyearbyen, Svalbard, with a special focus on boundary layer processes. Initial results will be presented, including local wind processes important for wind energy and radiation properties for solar energy. The goal is to identify the most important meteorological processes and adapt the energy solutions accordingly.

How to cite: Sjöblom, A., Henkies, M., and Garreau, A.: Meteorological challenges for renewable energy in the High Arctic, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1119, https://doi.org/10.5194/egusphere-egu23-1119, 2023.

Inclined and flat-plate photovoltaic (PV) solar panels have been widely used in many countries and regions for generating electric power. For exploiting the available solar energy in a region, prior knowledge of this potential is necessary. This work investigates the performance of solar panels in 82 locations in Saudi Arabia by calculating the annual energy received on inclined-plate with tilt angles from 15° – 55° inclined to south and flat-plate that continuously follow the daily motion of the sun.  Calculations are performed using a fixed surface albedo of 0.2 and with a near-real value. The analysis indicates that tilt angles of 20°, 25°, and 30° towards the south are the optimum ones depending on the site. These optimum tilt angles define three distinct solar energy zones in Saudi Arabia. The variation of the total energy in each energy zone on a monthly, seasonal, and annual basis is given. Regression analysis for the total energy as a function of time is derived for each zone. Moreover, the spatial distribution of the annual global inclined solar energy in Saudi Arabia is illustrated in a solar map where the total energy is found to vary from 1612 - 2977 kWhm−2year−1 for the southward-inclined plates and 2159 – 4078 kWhm−2year−1 for the flat-plates across Saudi Arabia. The correction factor, introduced in a recent publication, is used; it is found that the linear relationship between the correction factor and the ground-albedo ratio is general enough to be graphically representable as a nomogram.

How to cite: Farahat, A. and Kambezidis, H.: Solar Potential in Saudi Arabia: Spatio-temporal and Plates-inclination Effects on the Performance of Photovoltaic Solar Panels, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1790, https://doi.org/10.5194/egusphere-egu23-1790, 2023.

In 2021, Saudi Arabia, a leading global oil producer, announced its Middle East Green Initiative with many objectives including reducing carbon emissions by divagating the country away from an oil-based economy and towards renewable. Saudi Arabia has a high potential to become one of the global largest solar energy producers, as it is geographically located on a sunbelt. By 2030, the Saudi government targets building eight solar plants across the country which are expected to produce more than 3,600 MW, enough to power more than 500, 000 homes. However, the vast desert environment in Saudi Arabia increases the dust and aerosol loadings in the atmosphere, which affects the performance of the solar irradiance performance of photovoltaic panels due to the scattering of the solar radiation and the dust deposition on the solar panels. In this work, ground-based data from weather stations located in five Saudi cities: Dammam, Riyadh, Jeddah, Najran, and Arar along with data from the Moderate Resolution Imaging Spectroradiometer (MODIS) are used to estimate solar irradiance and its correlation with atmospheric and meteorological conditions like air temperature, wind, and aerosol physical parameters. We investigate the effect of three major dust storms that blew over different regions in Saudi Arabia on 20 March 2017, 23 April 2018, and 15 April 2021 on solar irradiance. It is found that there is a strong correlation between aerosol optical parameters like Aerosol Optical Depth (AOD), Ångström exponent, and solar irradiance. Maximum AOD (about 2) is recorded over Jeddah on 19 March 2017, (about 2.3) over Riyadh on 20 March 2017, (about 1.5) over Riyadh on 24 April 2018, and (about 0.9) over Najran on 15 April 2021. Large dust events are found to reduce air temperature by a few degrees in the regions affected by dust loadings. The study found large dust loading decreases the DNI, and GHI components on the solar irradiance, while increasing the DHI component over the cities of Jeddah, Riyadh, and Najran. This could be an indication that scattering from dust particles could play a significant role in the solar irradiance intensity. 

How to cite: Labban, A. and Farahat, A.: Effect of Major Dust Events on Atmospheric Temperature and Solar Irradiance Components over Saudi Arabia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1854, https://doi.org/10.5194/egusphere-egu23-1854, 2023.

EGU23-2107 | Posters on site | ERE2.1

Power generation forecast for a solar plant with a deep-learning method 

Yu-Ting Wu and Chang-Yu Lin

In this study, we perform power generation forecast of a solar farm using deep learning. A long short-term memory (LSTM) network is applied to forecast time series data of the overall power production from a solar farm. An LSTM network can be considered as a recurrent neural network (RNN) looping with input data (e.g., measured power data) over time steps to update the network information. The network information also has records over all previous time steps. One can use an LSTM network to predict subsequent values of a time series (denoted as open loop forecasting) or sequence using previous time steps as input (denoted as closed loop forecasting). Both forecasting methods are built in the LSTM network. Preliminary results show that closed loop forecasting can allow to have predictions of solar power in more time steps, but less accurate than the other method.  

How to cite: Wu, Y.-T. and Lin, C.-Y.: Power generation forecast for a solar plant with a deep-learning method, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2107, https://doi.org/10.5194/egusphere-egu23-2107, 2023.

Wind energy is essential in many decarbonization strategies and potentially vulnerable to climate change. While existing wind climate change assessments rely on regional or global climate models, a systematic investigation of the global-to-regional climate modeling chain is missing. In this presentation, I therefore address the differences in climate change impacts on winds according to  regional and global climate model ensembles under three different future scenarios.

 

I highlight two key limitations, namely (a) the differing representation of land-use change in global and regional climate models which compromises comparability, and (b) the consistency of large-scale features along the global-to-regional climate modeling chain. To this end, I analyze the large EURO-CORDEX ensemble (rcp85: N=49; rcp45: N=18; rcp26: N=22) along with the driving global models (rcp85: N=7; rcp45: N=5; rcp26: N=7), finding evidence that climate change reduces mean wind speeds by up to -0.8 m/s (offshore) and -0.3 m/s (onshore).

 

Moreover, I provide physical explanations for these changes by identifying two key drivers. First, onshore wind speeds drop in the driving global models in regions and scenarios with strong land use change but show no drop in EURO-CORDEX where land use is held constant. Second, offshore wind reductions follow decreases in the equator-to-pole temperature gradient remarkably well with correlations reaching around 0.9 in resource-rich European countries like Ireland, the United Kingdom and Norway, implying that arctic amplification is a severe risk for European offshore wind energy.

 

My results suggest that earlier conclusions of negligible climate change impacts on wind energy might be premature if either land use changes strongly or polar amplification is at or above the range sampled in global climate models. In conjunction with earlier work that demonstrated the relevance of multidecadal wind fluctuations caused by climate variability, these results call for a better inclusion of climate risk in wind energy planning.

 

Reference

 

Wohland, J. Process-based climate change assessment for European winds using EURO-CORDEX and global models. Environ. Res. Lett. (2022) doi:10.1088/1748-9326/aca77f.

How to cite: Wohland, J.: Climate change impacts on winds in Europe: do global and regional climate models tell the same story?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2317, https://doi.org/10.5194/egusphere-egu23-2317, 2023.

January 2007 was a bad storm month for much of central and northern Europe with a series of extratropical cyclones bringing high winds and precipitation to highly populated areas between Ireland and Russia.  Although Storm Kyrill on 18-19 January 2007 was the most serious for its infrastructure damage and insurance costs, Storm Franz from the preceding week on 11-12 January 2007 was actually more serious for its maritime impacts in western Europe. This contribution takes a closer look at Storm Franz, presenting an overview of its impact to energy infrastructure as well as transportation networks and societal infrastructure damage.  Maritime casualties are reviewed with respect to met-ocean conditions.  An analysis is carried out on water level recorders around the North Sea to assess the storm surge and short period oscillations that may reveal harbour seiches or meteotsunamis.  The results are compared with wave recorders, which had a fairly good coverage across the North Sea in 2007.  The issue of wave damage to offshore infrastructure was highlighted in events associated with Storm Britta on 31 October - 1 November, 2006.  Offshore wind energy in northwest Europe was in a growth phase during this time, and there were questions about the extreme met-ocean conditions that could be expected in the 20 year lifetime of an offshore wind turbine.

How to cite: Kettle, A.: Storm Franz: Societal and energy impacts in northwest Europe on 11-12 January 2007, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3218, https://doi.org/10.5194/egusphere-egu23-3218, 2023.

EGU23-3486 | ECS | Posters on site | ERE2.1 | Highlight

Solar energy potential assessment on urban rooftops using digital surface models 

Xinyuan Hou and Stelios Kazadzis

Rooftop solar photovoltaic (PV) systems have the advantage of producing electricity without air pollution and greenhouse gas emissions, at the same time reducing carbon footprint as well as urban heat island effect. This study aims to assess physical, geographical and economic levels of solar energy potentials in actual atmospheric conditions on urban rooftops, using two municipalities in Athens, Greece as an example. 

We utilize very high-resolution digital surface models for the computation of clear-sky solar irradiance considering surrounding shadows. For all-sky conditions, cloud and aerosol data from 2012 to 2021 are obtained from the Copernicus Atmosphere Monitoring Service radiation service and the ECMWF Atmospheric Composition Reanalysis 4 product, respectively. The goals are to quantify the effect of solar elevation, the shadowing effect from adjacent buildings and constructions, and the effects of clouds and aerosols on the solar radiation availability on the rooftops and to investigate their interconnections. The spatio-temporal resolution of the analyses ranges from individual rooftop to neighborhood scale (approximately 3000 buildings) and from hourly intervals to ten years periods.

The results of the solar potential assessment are made available as a web GIS map for potential public access, intended to aid urban planning and encourage widespread adoption of solar energy in the public and private sectors.

How to cite: Hou, X. and Kazadzis, S.: Solar energy potential assessment on urban rooftops using digital surface models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3486, https://doi.org/10.5194/egusphere-egu23-3486, 2023.

EGU23-4625 | Posters on site | ERE2.1

Medium and Long-term Forecast of Wind Power Trend Based on Regional Similarity 

Xianxun Wang, Yaru Liu, Defu Dong, and Suoping Wang

Accurate and efficient medium and long-term forecast of wind power can provide technical support for efficient development and utilization of wind resources. Taking into account the regional characteristics of wind resources, the regional similarity factor is introduced into the study of wind power forecasting, and the long-term dependence of wind power, the Long Short-Term Memory method is selected for medium and long-term forecasting of wind power trend, a case study is carried out in five provinces of Northwest China. The results show that the error is reduced by an average of 20.80% compared with the forecast of individual stations, which verifies the effectiveness of the proposed method. Different area division methods result in different effects on improving the prediction accuracy. This study provides a new method and reference for medium and long-term wind resource prediction.

How to cite: Wang, X., Liu, Y., Dong, D., and Wang, S.: Medium and Long-term Forecast of Wind Power Trend Based on Regional Similarity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4625, https://doi.org/10.5194/egusphere-egu23-4625, 2023.

EGU23-5382 | Posters on site | ERE2.1

The GASPOC project and the global offshore atlases of siting parameters 

Xiaoli Larsén, Marc Imberger, Neil Davis, Jacob Sørensen, Carsten Kofoed, Jim Nielsen, Bjarke Olsen, Jana Fischereit, and Jake Badger

The Global Atlas of Siting Parameters for Offshore and Coasts (GASPOC) project aims at shortening the project development period for offshore wind farms, with faster energy integration, lower capital expenditure and lower operating expense. This value is brought by the partners DHI, DTU Wind, Vento Maritime and DECK1 through automatic data driven downscaling techniques, that are applied to meteorological, ocean and wave modeling and analytics, including the application to real test scenarios. GASPOC provides metocean data, including siting parameters for offshore wind turbines such as extreme winds and turbulence intensity, as well as extreme waves and joint wind-wave statistics. An ensemble of reanalysis data together with the spectral correction method (Larsén et al. 2012) is used to obtain the effective 10-min extreme winds at 50 m, 100 m, 150 m and 200 m, while the calculation of the turbulence intensity at heights above the surface layer also takes the mesoscale turbulence into consideration. We show the data of the siting parameters from GASPOC which support seamless application to strategic planning of offshore wind energy development.

Reference

Larsén X., Ott S., Badger J., Hahmann A. N. and Mann J. 2012: Recipes for correcting the impact of effective mesoscale resolution on the estimation of extreme winds. Journal of applied meteorology and climatology, Doi:10.1175/JAMC-D-11.090, vol 51, No. 3, p521-533.

How to cite: Larsén, X., Imberger, M., Davis, N., Sørensen, J., Kofoed, C., Nielsen, J., Olsen, B., Fischereit, J., and Badger, J.: The GASPOC project and the global offshore atlases of siting parameters, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5382, https://doi.org/10.5194/egusphere-egu23-5382, 2023.

EGU23-5388 | ECS | Posters on site | ERE2.1

Spatial complementary of offshore wind farm Iberian Peninsula sites based on COSMO-REA6 high-resolution reanalysis. 

Noelia López-Franca, Miguel Ángel Gaertner, Enrique Sánchez, Clemente Gallardo, María Ofelia Molina, María Ortega, and Claudia Gutiérrez

The energy transition is a fundamental endeavour in the way towards a zero-carbon future that will allow us to mitigate anthropogenic climate change. There are plans at a European Union level and, also at Iberian Peninsula (IP) one, to strongly increase the installed wind power capacity by 2030, with the aim by 2050 of making Europe the first climate-neutral continent. Onshore wind and solar photovoltaic are currently by far the main renewable technologies installed on the IP, receiving other potential dispatchable energy resources such as offshore wind less attention. This resource should also be considered due to its high energy potential and the increasing difficulty of finding suitable land for new onshore wind farms. Although some areas, such as the western IP, show high potential, there are important spatial constraints for the deployment of floating offshore wind towers, related to wind infrastructure technologies and legislative limits. Together, wind power generation is, by nature, complex, irregular and hard to be forecasted. Thus, increasing interconnections between regions can dampen the impact of wind variability on local wind power generation. An analysis of the spatial complementarity of the top potential floating offshore wind farm sites across IP is then proposed in this work. For this purpose, hourly wind fields from COSMO-REA6 very high resolution reanalysis (0.055º) in the 1995-2018 period were used to compute the wind capacity. The wind speed was vertically interpolated to the hub height of 105 meters of a reference turbine at each grid point between the levels 36-39 (approximately 35 to 178 meters) of the reanalysis by a cubic polynomial function using the least squares fit. Then, a total of 55 potential locations of Iberian commercial floating wind farm projects were manually collected, mainly from publicly available information. Of these, ten potential sites were chosen by applying a methodology that finds the combination of sites that minimizes the coefficient of variation of the aggregate wind power. The first results indicate that, in the period considered, it is more advantageous for the Iberian electricity system to build wind farms farther apart, giving priority to wind farm projects located in the northeast and northwest coastal corners of IP. Thus, as more distant sites are added, the coefficient of variation decreases more than the capacity factor. This behaviour varies slightly by season, with the variation decreasing the most in winter and the capacity factor decreasing the most in summer.

How to cite: López-Franca, N., Gaertner, M. Á., Sánchez, E., Gallardo, C., Molina, M. O., Ortega, M., and Gutiérrez, C.: Spatial complementary of offshore wind farm Iberian Peninsula sites based on COSMO-REA6 high-resolution reanalysis., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5388, https://doi.org/10.5194/egusphere-egu23-5388, 2023.

EGU23-5763 | Posters on site | ERE2.1

Realistic Wake Simulation using the WRF-SADLES System 

Hai Bui and Mostafa Bakhoday-Paskyabi

Simulating wind turbine wakes with high accuracy is crucial for understanding their effects on nearby flow patterns and optimizing the design and operation of wind farms. However, current Large Eddy simulation (LES) models for this purpose often rely on highly idealized boundary layer conditions, which may not capture all relevant realistic processes. In this study, we present the development and application of a Simple Actuator Disc model for Large Eddy Simulation (SADLES) for simulating wakes in realistic conditions. SADLES was developed to utilize traditional thrust and power curves provided by turbine manufacturers, while also achieving an intermediate resolution of a few dozen meters to strike a balance between fidelity and computational cost. SADLES has been integrated into the Weather Research and Forecast (WRF) model, resulting in the WRF-SADLES system. Using this system, atmospheric conditions from ERA5 data were downscaled to a wake-enable scale of 40 m using a system of 5 nested domains. Selected transition events were simulated and the results were validated using real observations from the FINO1 meteorological mast and LiDAR data. Our WRF-SADLES approach represents a promising advancement in the simulation of wind turbine wakes and their impacts on surrounding flow fields.

How to cite: Bui, H. and Bakhoday-Paskyabi, M.: Realistic Wake Simulation using the WRF-SADLES System, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5763, https://doi.org/10.5194/egusphere-egu23-5763, 2023.

European countries are increasing their share of power production from wind and solar energy to mitigate climate change. Also the relative contributions from PV and wind power production in Europe change over time. At present, the installed capacity of photovoltaic (PV) power for all of Europe is smaller than that of wind power with a ratio of 3:4. Future scenarios for the installations of PV and wind power capacities for 2050 suggest that this ratio will substantially change. Namely, the PV power capacity might exceed the wind power capacity with a ratio of 3:2 to 2:1. We test the hypothesis that the weather dependency of anomalies in the PV plus wind power production will change in the future compared to today. Specifically, we examine which synoptic weather patterns are associated with anomalies in the PV plus wind power production for the present and future installed capacities in Europe. To that end, we developed a renewable energy model for the installed capacity of 2019 and 2050. This model allows us to simulate hourly PV and wind power production at 6 km horizontal resolution for all of Europe. We analyze the weather dependency of power-production anomalies by pairing our model output with results of the classification of weather patterns from the German Weather Service. Our results highlight similar weather patterns associated with positive anomalies in the hourly PV plus wind power production for the 2019 and 2050 installation, namely weather patterns with prevailing westerly winds. However, weather patterns associated with negative anomalies strongly change between the two installations. We also assess the dependency of the results on the duration of the production anomalies. Particularly for long production anomalies, the associated weather patterns are different for the 2019 and 2050 installation. One exception is the weather pattern Anticyclonic Southeasterly that is associated with the lowest 10-day power production in Europe for both 2019 and 2050. Regionally, weather patterns have different impacts on different regions in Europe, when comparing the associated patterns between the 2019 and 2050 installation. For instance, anomalously low power production differ for the Iberian peninsula and Southeastern Europe when the two installed capacities are compared. Taken together, our study gives a systematic overview on changes in the weather dependency of anomalies in the mix of PV and wind power between 2019 and 2050.

How to cite: Ho, L. and Fiedler, S.: Weather dependency of European wind and photovoltaic power production for present and future installations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5812, https://doi.org/10.5194/egusphere-egu23-5812, 2023.

EGU23-5918 | ECS | Posters on site | ERE2.1

AEOLIAN, the new Italian Wind Atlas for local energy planning support 

Martina Aiello, Davide Airoldi, and Alessandro Amaranto

The decarbonization objectives set by the EU Green Deal to increase the renewable generation heavily rely on the contribution of wind energy, both onshore, through the installation of new plants and repowering of existing plants, and offshore. The issuance of the new "Fit for 55" package of measures will result in an increase in the objectives already identified for 2030 for Italy, which in all probability will be set at over 21 GW of installed capacity for onshore wind (i.e., doubling the currently operating power) and at least 3 GW for offshore wind. An informed energy planning of the territory is therefore paramount to efficiently maximize renewable penetration. In these regards, the development of informatic tools aimed at disentangling both resource availability and generation potential can effectively play a key role in supporting optimal technology displacement through space. RSE has worked on these themes since the end of the 1990s, when the first version of the Italian Wind Atlas (ATLAEOLICO) WebGIS was released, providing a support tool for adequate energy planning of the territory. Throughout the years, the Wind Atlas has represented a reference for various stakeholders (wind plants developers, authorities responsible for spatial planning and companies involved in the electricity grid development) who recognized its great utility in quickly identifying the most suitable Italian areas for wind energy exploitation in terms of long-term annual average wind speed and full load hours.  With the purpose that this platform keeps providing tangible support for energy planning, we have worked on both renewing the anemological database and the WebGIS structure, which is the focus of this work.  The new Italian Wind Atlas AEOLIAN provides for a new anemological database consisting in 30 years (1990-2019) of hourly wind data at 1.4 km horizontal resolution (WGS84 UTM32) covering the whole Italian territory and marine areas. Wind trajectories are estimated through the Weather Research and Forecasting (WRF) meteorological model combined with a statistical post-processing based on Analog Ensemble (AnEn). The renewed AEOLIAN WebGIS, developed through the open access framework TerriaJS, integrates standard functions for visualizing and querying data, data download functions and advanced tools to support local energy planning. It shows the spatial distribution of onshore and offshore wind speed [m/s] and full load hours [MWh/MW]. Each variable is computed as the 30 years annual average at the heights of 50, 75, 100, 125 e 150 m. a.s.l. Within AEOLIAN, users can download both variable maps and historical series of wind speed for more accurate evaluations. Besides maps, AEOLIAN also includes a tool for the technical and economical evaluation of a hypothetical wind farm at a local scale. This tool allows assessing the energy performances in terms of the net annual energy production and the average cost of the energy produced, considering local distribution of the wind resource, energy performances of the wind farm and investments and management costs.  

How to cite: Aiello, M., Airoldi, D., and Amaranto, A.: AEOLIAN, the new Italian Wind Atlas for local energy planning support, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5918, https://doi.org/10.5194/egusphere-egu23-5918, 2023.

EGU23-5952 | ECS | Orals | ERE2.1

The Aspire campaign: Assessing the effects of aerosols on solar radiation and energy in SE Europe. 

Dimitra Kouklaki, Ioannis-Panagiotis Raptis, Stelios Kazadzis, Ilias Fountoulakis, Kyriakoula Papachristopoulou, and Kostas Eleftheratos

In recent years, solar power applications are growing rapidly worldwide, to meet the increasing power demand and the sustainable development planning. Estimation of solar radiation availability at surface level, its characteristics and various factors that affect it, play a key role in designing and achieving the optimal performance of systems employing solar energy. Various solar -PV related - applications are using radiative transfer modeling to characterize the radiation field, since accurate surface solar irradiance measurements are not always available, especially in remote regions. Understanding the effect of aerosols to the solar energy potential is highly important for the energy sector as well as for a variety of fields.    In areas and periods where cloudiness is limited and they are in the proximity of particle sources, the significance of aerosol effect is very high.

The objective of this study is to assess the impact of the variability of aerosols on the solar Direct Normal Irradiance (DNI), Global Horizontal Irradiance (GHI) and solar energy, using spectral solar measurements and aerosol optical properties retrievals, in the framework of the one-year experimental campaign (December 2020-December 2021) of the ASPIRE (Atmospheric parameters affecting SPectral solar IRradiance and solar Energy, https://aspire.geol.uoa.gr) project, which was held in Athens, Greece.

Main findings include an assessment of differences among different PV technology and their calculated outputs using actual and standard spectra, linking the differences with aerosol optical properties (optical depth, spectral dependence, absorption). Aerosol optical depth is the major factor of such differences for all PV technologies. Spectral aerosol characteristics affect differently PV technologies as a consequence of different spectral responsivities.

Finally, aerosol effect on solar nowcasting models have been investigated by comparing spectral solar measurements and aerosol properties with model inputs and outputs.

How to cite: Kouklaki, D., Raptis, I.-P., Kazadzis, S., Fountoulakis, I., Papachristopoulou, K., and Eleftheratos, K.: The Aspire campaign: Assessing the effects of aerosols on solar radiation and energy in SE Europe., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5952, https://doi.org/10.5194/egusphere-egu23-5952, 2023.

Probabilistic forecasts based on ensemble simulations of numerical weather prediction models have become a standard tool in weather forecasting and various application areas. However, ensemble forecasting systems tend to exhibit systematic errors such as biases, and fail to correctly quantify forecast uncertainty. Therefore, a variety of post-processing methods has been developed to correct these errors and improve predictions [1]. In particular, machine learning methods based on neural networks have been demonstrated to lead to substantial improvements compared to classical statistical techniques [2].
While post-processing can successfully correct the biases and dispersion errors in the weather variables, its effect but has not been evaluated thoroughly in the context of subsequent forecasts, such as wind and solar power generation forecasts and it is not obvious how to best propagate forecast uncertainty through to subsequent power forecasting models. Therefore, the work presented here will evaluate multiple strategies for applying ensemble post-processing to probabilistic wind and solar power forecasts. We use Ensemble Model Output Statistics (EMOS) as the post-processing method and evaluate four possible strategies: only using the raw ensembles without post-processing, a one-step strategy where only the weather ensembles are post-processed, a one-step strategy where we only post-process the power ensembles and a two-step strategy where we post-process both the weather and power ensembles. The presentation is based on recent work in Phipps et al. (2022) [3] and ongoing other work.

References

[1] Vannitsem, S., et al. (2021). Statistical Postprocessing for Weather Forecasts - Review, Challenges and Avenues in a Big Data World. Bulletin of the American Meteorological Society, 102, E681–E699.
[2] Rasp, S. and Lerch, S. (2018). Neural networks for post-processing ensemble weather forecasts. Monthly Weather Review, 146, 3885–3900.
[3] Phipps, K., Lerch, S., Andersson, M., Mikut, R., Hagenmeyer, V. and Ludwig, N. (2022). Evaluating ensemble post-processing for wind power forecasts. Wind Energy, 25, 1379-1405. 

How to cite: Lerch, S.: Evaluating ensemble post-processing for probabilistic energy prediction, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6644, https://doi.org/10.5194/egusphere-egu23-6644, 2023.

EGU23-6943 | Orals | ERE2.1 | Highlight

Impact assessment of future wind farm characteristics on cluster-scale wake losses in the North Sea 

Nicole van Lipzig and Ruben Borgers

Offshore wind zones are reaching sizes at which they start to affect each other and potentially also alter mesoscale weather systems, impacting the energy production. Here, we assess the impact of future wind farm characteristics, like turbine type and capacity density, on cluster-scale wake losses. For this we use the mesoscale model COSMO-CLM at the km-scale resolution, which skillfully models frequency distributions of wind speed and wind direction at turbine level compared to measurement masts, wind lidars and satellite data. It was found that inter-farm wakes can reduce the long-term capacity factor at the inflow edge of wind farms from 59% to between 55% and 40% depending on the degree of clustering and the size of the upwind farms, for a layout equipped with 5MW turbines at a capacity density of 8.1 MW / km². Moving to next-generation wind turbines (15MW) partly mitigates this degradation, as the total generation over all windfarms (TWh) is increased by 19% under the same wind farm capacity density. On the other hand, increases in the capacity density in this future layout lead to a less than proportional (0.8 to 1) increase in the basin-integrated, total generation as a consequence of more intense intra- and inter-farm wake effects. Generally, wind farm characteristics play an essential role in inter-farm wake losses, which should be included in future wind farm planning.

How to cite: van Lipzig, N. and Borgers, R.: Impact assessment of future wind farm characteristics on cluster-scale wake losses in the North Sea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6943, https://doi.org/10.5194/egusphere-egu23-6943, 2023.

EGU23-8140 | ECS | Posters virtual | ERE2.1

From solar radiation estimation to solar energy potential in the High Arctic 

Arthur Garreau, Torodd Nord, Anna Sjöblom, and Aleksey Shestov

The High Arctic is a remote region with a harsh climate where communities mainly rely on fossil energy sources. In Longyearbyen, located in the archipelago of Svalbard at 78°N, solar energy is considered as one of the future energy sources. The available solar radiation must therefore be estimated to have solar energy as part of the energy mix. To achieve this goal, the University Centre in Svalbard has maintained a weather station that has recorded ten years of solar radiation data with a Kipp and Zonen CNR1 net radiometer. Additional pyranometers have been installed at other locations, at different altitudes, and with different configurations to establish a more complete atlas of the solar irradiance around Longyearbyen.

The solar irradiance in the High Arctic has different characteristics than that usually encountered at mid-latitudes. There are 24 hours of sunlight during summer and polar nights during winter. When the sun is present, its position and path in the sky differ from further south. In addition, the air mass, atmospheric aerosols, and albedo have an impact on radiation that is peculiar to the Arctic. All those specificities have yet to be completely understood for the Arctic, and hence some uncertainties remain about solar radiation.

A better understanding of the solar radiation received in Longyearbyen will help implement the future solar energy solution for the Arctic. The aim is to accurately estimate solar radiation at high latitudes, capture variability and predictability, and understand which solar cell configuration is optimal. In particular, differences between horizontal and plane-of-array irradiance have been investigated because of the very low elevation angle of the sun. The solar radiation distributions over different time scales have further been assessed using observations. Moreover, the impact of external factors on solar radiation, such as albedo, has been considered. In the future, the collected data will be used to assess Svalbard's solar PV potential.

How to cite: Garreau, A., Nord, T., Sjöblom, A., and Shestov, A.: From solar radiation estimation to solar energy potential in the High Arctic, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8140, https://doi.org/10.5194/egusphere-egu23-8140, 2023.

Near-surface wind fields are altered over mountainous topography, giving rise to complex wind flow patterns due to sheltering, acceleration, channelling, deflections, blocking or recirculation. However, the impact of the resulting spatio-temporal wind fields on wind energy potential remains largely unknown. While wind modelling approaches can describe highly resolved spatio-temporal wind fields in mountainous terrain rather well, wind fields cannot be generated in a reasonable amount of computational time. Models are therefore strongly limited in space and time for many applications. In mountainous regions, wind farm planning is thus much more challenging than in flat regions.

To investigate the variability of wind fields and its impact on wind energy production in mountainous terrain, we applied a computationally efficient statistical downscaling model approach to a small region in the Swiss Alps. This allowed us to analyze the impact of horizontal resolutions on spatial wind speeds and energy yield in a mountainous area. We applied the statistical approach of Helbig et al., 2017 to downscale coarse wind speed values to the fine scale based on local terrain parameters. This approach introduces two dominant local wind-topography interactions: sheltering and speed-up on coarse wind speed. Then, based on the resulting spatio-temporal near-surface wind fields and a common theoretical power curve, we calculated long-term wind energy yield. Through a sensitivity analysis, we assessed the impact of varying horizontal spatial resolutions in the mountainous environment on overall and local wind energy yield. Specifically, we addressed the impact when decreasing horizontal resolutions from grid cell sizes of 100 m down to 5 m. Resulting spatial variations will be discussed as functions of local terrain parameters, as well as wind speeds.

Helbig, N., Mott, R., van Herwijnen, A., Winstral, A. and Jonas, T. (2017): Parameterizing surface wind speed over complex topography. J. Geophys. Res., 122, 651–667.

How to cite: Helbig, N., Hammer, F., and Barber, S.: Characterizing the impact of spatial scales on near-surface wind speed and wind power generation in a mountainous environment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9025, https://doi.org/10.5194/egusphere-egu23-9025, 2023.

EGU23-9658 | Orals | ERE2.1

Renewable energy forecasting: results of the Smart4RES project and future research directions. 

Georges Kariniotakis and Simon Camal and the Smart4RES Team

The European Horizon 2020 project Smart4RES (http://www.smart4res.eu), which started in 2019 and runs until April 2023, aims at improving modelling and forecasting of weather variables necessary to optimize the integration of weather-dependent renewable energy (RES) production (i.e. wind, solar) into power systems and electricity markets. It gathers experts from several disciplines ranging from meteorology, data science, power systems a.o. It aims to contribute to the pathway towards energy systems with very high RES penetrations by 2030 and beyond.

This presentation has a double objective:

(1) To present a comprehensive overview in terms of KPI improvements of the final results obtained by the project. These results cover thematic objectives including:

  • Improvement of weather and RES forecasting;
  • Streamlined extraction of optimal value from the data through data sharing, data market places, and novel business models for the data;
  • New data-driven optimization and decision-aid tools for market and grid management applications;
  • Validation of new models in living labs and assessment of forecasting value vs costly remedies to hedge uncertainties (i.e. storage). 

The results obtained are numerous. Without being exhaustive, they include: improved forecasting of weather variables with focus on extreme situations and also through innovative measuring settings (i.e. a network of sky cameras); A seamless approach to couple outputs from different ensemble numerical weather prediction (NWP) models with different temporal resolutions; Advances from ultra-high resolution NWPs based on Large Eddy Simulation; Approaches for RES production forecasting aiming at efficiently combining highly dimensionally input (various types of satellite images, NWPs, spatially distributed measurements etc.); Seamless probabilistic RES forecasting covering multiple time frames and data inputs; Resilient energy forecasting. In the front of applications methods are proposed to optimally use forecasts for the management of storage systems coupled with renewables, for the optimal trading of renewables in multiple markets and for grid management optimization and dynamic security assessment. Prescriptive analytics and explainable AI methods are proposed to optimize decision making.  A cost benefit analysis is performed to assess the contribution of different types of data in forecasting problems.

(2) To present hierarchized proposals for future research directions. An international workshop is organized by the project (14/04/2023), where experts are invited to assess where RES predictability stands today and propose research directions for the future. In this presentation we will present the conclusions of this workshop. This will be a useful insight for academics, industrials as well as policy makers in the field.

How to cite: Kariniotakis, G. and Camal, S. and the Smart4RES Team: Renewable energy forecasting: results of the Smart4RES project and future research directions., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9658, https://doi.org/10.5194/egusphere-egu23-9658, 2023.

EGU23-10763 | Posters virtual | ERE2.1

Forecasting surface solar irradiance in Germany using Meteosat Rapid Scanning Service satellite images 

Mathieu Turpin, Sébastien Marchal, and Nicolas Schmutz

Photovoltaic (PV) production is strongly dependent on cloud cover behaviour. It can induce a very high variability of the production which is problematic for a safe and gainful injection into the power grid. Advanced forecasting solutions represent a major key to reliable PV systems. Satellite data are used to provide forecasts from 15 minutes until 6 hours ahead.

To achieve cloud cover forecast, the first step consists in converting two successive satellite images into a cloud index map. Then, the movement of the clouds between these two images is obtained by analysing the optical flow, transformed into a Cloud Motion Vector (CMV) which is then applied on the image taken at T0 to extrapolate it and forecast the various cloud index maps up to T0 + 6h. Finally, the cloud index is combined with a clear sky model in order to compute the effective Surface Solar Irradiance.

Over Europe, raw images are taken by EUMETSAT’s (European Organisation for the Exploitation of Meteorological Satellites) geostationary satellite. The satellite scans the Earth’s full disk in 15 minutes with the PRIME satellite positioned at 0°. However, the Rapid Scanning Service (RSS) scans the northern third of the Meteosat disk every five minutes, enabling more frequent data acquisition and lower delivery time. One satellite is dedicated to this operating mode and is positioned at 9.5°E.

TRUSTPV is a European Union’s Horizon 2020 Research project whose purpose is to investigate and demonstrate the development of O&M-friendly and grid-friendly solar solutions in large portfolios of distributed and utility scale photovoltaics. Within TRUSTPV, we demonstrate the performance improvement provided by using the geostationary meteorological satellite's RSS to obtain images more frequently and therefore improve intraday forecasts. In this work, we forecast cloud cover every 5 minutes with a 5-minute time step. Then, we simulate PRIME operation with forecasts generated every 15 minutes with a 15-minute time step by using the same optical flow and extrapolation algorithms. Moreover, we take into account the latency in the access to the data in real time. The model outputs are compared to 10-minute solar radiation measurements from Deutscher Wetterdienst (DWD) stations located in Germany over the period ranging from 2021-09-01 to 2022-08-31. We determine the quarterly performance in order to study the seasonal effects. The results are also expressed in terms of relative Root Mean Scare Error (RMSE), RMSE Skill Score, Mean Absolute Error (MAE), MAE Skill Score, and mean bias error.

Comparisons between forecasted surface solar irradiance at 30 minutes of time horizon and co-located pyranometric measurements show an improvement for all sites with a decrease of MAE around 4%. This gain brought by the RSS will improve the quality of power production forecasts of PV plants.

The research leading to these results has received funding from the Horizon 2020 Research and invention Programme, under Grant Agreement No 952957, Trust-PV project.

How to cite: Turpin, M., Marchal, S., and Schmutz, N.: Forecasting surface solar irradiance in Germany using Meteosat Rapid Scanning Service satellite images, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10763, https://doi.org/10.5194/egusphere-egu23-10763, 2023.

EGU23-11429 | ECS | Posters on site | ERE2.1

Improvements and validation of nextSENSE solar energy nowcasting and short-term forecasting system 

Kyriakoula Papachristopoulou, Ilias Fountoulakis, Alkiviadis F. Bais, Basil E. Psiloglou, Charalampos Kontoes, Maria Hatzaki, and Stelios Kazadzis

Solar energy is one of the main sources of renewable energy nowadays. Since there is a strong dependence of solar power generation on the presence of clouds and aerosols, operational nowcasting and short-term forecasting of solar resources are essential for its integration into the grid.

The aim of this study is the assessment of the downwelling surface solar irradiation (DSSI) estimates from the nextSENSE operational service. This service uses as input earth observational data for clouds (EUMETSAT), aerosols (Copernicus Atmosphere Monitoring Service - CAMS) and other important atmospheric parameters to the fast radiative transfer model (RTM) techniques (look-up table – LUT and multi-parametric equations) in order to derive DSSI in real time over Europe and North Africa in high spatial resolution (5 km at sub-satellite point), every 15 min. Recent modifications relative to the older versions are: (i) the use of multi-parametric equations to obtain the effect of clouds from cloud optical thickness (COT) instead of using Artificial Intelligence techniques, and (ii) the use of more detailed LUT. Forecasted DSSI values are also produced up to 3-hours ahead with a 15-min time step by applying a cloud motion vector (CMV) technique to the COT product based on Meteosat second generation (MSG) satellite data.

The new modeled (nowcasted and forecasted) DSSI values were validated against ground-based global horizontal irradiance measurements from pyranometers operating at the Baseline Surface Radiation Network (BSRN) stations and at two additional stations, these of Athens and Thessaloniki, Greece, for the year 2017. The nextSENSE forecasted DSSI values were also benchmarked against the smart-persistence forecast method. The performance of the modeled DSSI values were assessed for different cloud conditions in terms of real cloud modification factor (CMF) values derived by ground-based measurements in conjunction with a clear sky model. Additionally, the effects of aerosol related inputs for estimating DSSI were quantified by comparing the utilized CAMS aerosol optical depth (AOD) forecasts against surface retrievals of the AERONET network.

Acknowledgements

This study was funded by the European Commission project EuroGEO e-shape (grant agreement No 820852).

How to cite: Papachristopoulou, K., Fountoulakis, I., Bais, A. F., Psiloglou, B. E., Kontoes, C., Hatzaki, M., and Kazadzis, S.: Improvements and validation of nextSENSE solar energy nowcasting and short-term forecasting system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11429, https://doi.org/10.5194/egusphere-egu23-11429, 2023.

EGU23-12367 | ECS | Posters on site | ERE2.1

Projected Changes in Türkiye's Wind Energy Potential Using Next-Generation Climate Models and Scenarios 

Zekican Demiralay, M. Tufan Turp, Nazan An, and M. Levent Kurnaz

Renewable energy is a cornerstone in reducing greenhouse gas emissions and, accordingly, mitigating changes in the global climate system. Wind energy is becoming more common among all renewable energy sources used for electricity generation in terms of generation capacity, rapid growth and technological maturity. The share of wind energy in Türkiye's total electricity production, whose installed capacity has been increasing in recent years, has nearly tripled in the last decade. However, given that wind energy potential varies with wind speed, even small changes in future wind patterns and characteristics can strongly affect future wind power generation dependent on projections. For this purpose, in this study, Türkiye's mid-future (2031-2060) wind energy potential is examined under optimistic (SSP2-4.5) and pessimistic (SSP3-7.0) scenarios. In the study, 0.25° x 0.25° spatial resolution CMIP6 models from the NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP-CMIP6) dataset were used. The results point to regional differences in Turkey's mid-future (2031-2060) wind energy potential.

Acknowledgement: This research was supported by DaVinci Energy Investments and Consulting Industry and Trade Inc.

How to cite: Demiralay, Z., Turp, M. T., An, N., and Kurnaz, M. L.: Projected Changes in Türkiye's Wind Energy Potential Using Next-Generation Climate Models and Scenarios, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12367, https://doi.org/10.5194/egusphere-egu23-12367, 2023.

EGU23-12949 | Orals | ERE2.1

Post-processing and high-resolution downscaling of subseasonal ensemble forecasts with focus on renewables using statistics and machine learning 

Irene Schicker, Markus Dabernig, Petrina Papazek, Theresa Schellander-Gorgas, and Michael Tiefgraber

In the past decade, significant advances were made in improving the S2S and seasonal prediction using mainly numerical weather prediction models (NWP) and in some cases climate models for generating the predictions. Recently, the application of these models in real time forecasting through the S2S Real-Time Pilot Initiative (Robbins et al., 2020) was evaluated and is ongoing. There are, however, drawbacks. Computational costs for performing one forecast cycle are high (RAM, storage, ensemble for uncertainty) and limit the spatial, and to some extent temporal, resolution which are currently roughly 1.5° in spatial and at most 6-hourly in temporal resolution. Both resolutions are not sufficient for small scale renewable production sites.

 

In renewable energy applications, these time scales are getting more important as they can adapt their resource management strategies based on predictions of possible load/heating and cooling demand via anomalies to temperature, wind, precipitation amount, effects on the markets can be better estimated for trading, and scheduling of maintenance works. Thus, at least higher spatial resolutions could help improving the management and planning of these tasks.

 

Within the SSSEA project (SubSeasonal to Seasonal Ensemble prediction and Application), in project phase I, different methods for post-processing and downscaling the S2S challenge data to 1 km resolution and actual values instead of anomalies were implemented. The statistical methods EPISODES, GMOS, and SAMOS were adapted to be able to work with different time scales compared to their initial implementations (seasonal/hourly) and machine learning based methods were developed from scratch using a feed forward neural network, a Unet-based model, and a Random Forest. Temperature, precipitation, and in the currently ongoing project phase II, the wind components of the ECMWF S2S model were downscaled to daily analysis fields based on the INCA model.

 

For wind energy applications, specific indices were developed and applied to the downscaled results.  Verification and definition of suitable metrics is crucial to assess the skills of the different methodologies considered and a wide range of aspects and metrics were considered. Results on both grid and station verification for appx. 250 sites in Austria across nearly all altitude ranges show that all post-processing models are able to improve the ECMWF ensemble forecasts for the parameters considered, though, depending on lead time and season, differences in the models’ skill are visible. Furthermore, for most of the initial times and leadtimes in the forecast/testing period of 2020 we were able to outperform also the climatology. To assess the impact on renewable energy production, different indices were derived and evaluated with focus on wind energy and hydrology in project phases I and II. Results of SSSEA show clearly the added value of the post-processed and downscaled subseasonal predictions for both parameters and specified indices.

How to cite: Schicker, I., Dabernig, M., Papazek, P., Schellander-Gorgas, T., and Tiefgraber, M.: Post-processing and high-resolution downscaling of subseasonal ensemble forecasts with focus on renewables using statistics and machine learning, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12949, https://doi.org/10.5194/egusphere-egu23-12949, 2023.

EGU23-13992 | Orals | ERE2.1 | Highlight

Towards a paradigm of explainable AI applied in energy meteorology 

Konstantinos Parginos, George Kariniotakis, Ricardo Bessa, and Simon Camal

Standard practice of decision-making in energy systems relies largely on complex modeling chains to address technical constraints and integrate numerous sources of uncertainty. The increased penetration of Renewable Energy Sources (RES) such as solar and wind plants adds complexity due to the weather dependency of their electricity production. Artificial Intelligence (AI) based tools have proven their efficiency in different applications in the energy sector ranging from forecasting to optimization and decision making. They permit to simplify modeling chains and to improve performance due to higher learning capabilities compared to state-of-the-art methods. However, decision-makers of the energy sector need to understand how decision-aid tools construct their outputs from the data. AI-based tools are often seen as black-box models and this penalizes their acceptability by end-users (traders, power system operators a.o.). The lack of interpretability of AI tools is a major challenge for the wider adoption of AI in the energy sector and a fundamental requirement to better support humans in the decision-aid process. Agents of energy systems expect very high levels of reliability for the various services they provide. As energy systems are impacted by multiple uncertainty sources (e.g. available power of RES plants, weather and meteorological conditions, market conditions), developed AI tools should not only be performant on average situations but be able to guarantee robust solutions in the case of an extreme event. Therefore, our research focuses on understandable representations of data-driven decision-aid models for human operators in the energy sector. In order to enhance the interpretability of the AI models, a technique borrowed from the computer science domain is explored and further developed. Genetic programming and more precisely Symbolic Regression is used to derive a symbolic representation for the data-driven model that can take the form of a single equation. This equation results according to a specific reward function. The optimal solutions are selected naturally mimicking the biological theory of survival of the fittest. The main outcome is the production of symbolic representations of the AI models that require minimum changes when applied to different case studies. In this presentation a real-world use case is considered, to demonstrate the added value of the proposed tools for decision-making when trading the production of wind and solar power plants to the day-ahead market. An annual period of data is considered to train and test the proposed model. The typical modeling chain involves as many as 12 models for forecasting RES production, weather and meteorological conditions, together with stochastic optimization to derive trading decisions. A single AI-based model here replaces this complex chain. Such simplification is a significant enhancement to the modeling chain interpretability and facilitates trust to the human decision-maker. This work is carried out in part in the frame of the European project Smart4RES (Grant No  864337) supported by the H2020 Framework Program and in part in the frame the Marie-Curie COFUND project Ai4theSciences (Grant No  945304)

How to cite: Parginos, K., Kariniotakis, G., Bessa, R., and Camal, S.: Towards a paradigm of explainable AI applied in energy meteorology, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13992, https://doi.org/10.5194/egusphere-egu23-13992, 2023.

EGU23-14098 | ECS | Posters on site | ERE2.1

Offshore wind energy climate projections for the European region 

Stefano Susini and Melisa Menendez

The wind energy sector is experiencing a solid expansion towards the open sea, where higher-quality resources are available. This tendency is slowed down by the uncertainties in metocean characterization, with the wind playing a significant role as it represents both an action and a resource for the wind plant. The present study aims to investigate the climate change impact on the marine wind conditions, focusing on mean and extreme values.

Atmospheric circulation patterns over the European seas are classified based on combinations of the atmospheric sea level pressure and the directional wind speed data from the ERA5 reanalysis (1985-2015). These present climate patterns are then used to assess the performance of several General Circulation Model simulations from the sixth Climate Model Intercomparison Project (CMIP6) during the present climate. The best-performing models are then analyzed to provide projections of mean and extreme wind conditions in multiple shared socio-economic scenarios (SSP1-2.6, SSP2-4-5, and SSP5-8.5) and future horizons (2030-2060 and 2700-2100).

Results show a general decrease in the mean offshore wind speed over the European region, more intense in the Mediterranean Sea, while extreme wind speed will increase up to 3% along the Atlantic coast of Europe. The southeastern Atlantic coast appears to be favored in the analyzed climate change scenarios, as the extreme events are projected to reduce their intensity, while the wind resource is not expected to vary significantly.

How to cite: Susini, S. and Menendez, M.: Offshore wind energy climate projections for the European region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14098, https://doi.org/10.5194/egusphere-egu23-14098, 2023.

EGU23-14422 | ECS | Posters virtual | ERE2.1

Use of Several Sources of Spatio-temporal Information to Improve Short-term Photovoltaic Power Forecasting. 

Kevin Bellinguer, Robin Girard, Guillaume Bontron, and Georges Kariniotakis

In recent years, the share of photovoltaic (PV) power in Europe has grown: the installed capacity increased from around 10 GW in 2008 to nearly 185 GW in 2021. Due to the intermittent nature of PV generation, new challenges arise regarding economic profitability and the safe operation of the power network. To overcome these issues, a special effort is made to develop efficient PV generation forecasting tools.

Several sources of information are currently investigated in the literature. Each one possesses different characteristics, which make them horizon-specific. For short-term forecasting (i.e. from a few minutes to 6-hour ahead), endogenous inputs, namely past PV production measurements, are typically the main drivers. With the development of PV plants, and the advances in smart monitoring and measurements, we observe a paradigm shift from temporal- to spatio-temporal (ST)-based forecasting models. This family of models considers features that exploit ST correlations in the data, such as observations from spatially distributed portfolios of PV plants. This new paradigm offers power producers the possibility to economically value information from geographically distributed plant networks in the form of forecast accuracy improvements, and prepares the ground for a data-sharing market.

Depending on its distribution or density, a PV network may partially account for the complex ST processes at stake (e.g. mainly sites located upwind or crosswind). To fill this gap, satellite-based observations are an appealing option. With recent developments, geostationary satellites can capture images of Earth at a temporal resolution of less than an hour, which enables operational uses. Contrary to the spatial inflexibility inherent to PV networks, satellite-based observations offer the possibility of covering the whole vicinity of the site location, and much more. In that context, relevant features selection tools need to be considered.

In this work, we propose the following contributions to the state of the art. Traditionally in the literature, observations from spatially distributed units and satellite-derived information are used separately. We propose an incremental approach to assess the impact of one or several sources of data on the forecasting performances of the considered regression model. This approach shows that the combination of various sources of ST information leads to higher accuracy than when inputs are considered individually. This is assumed to result from the difference in spatial resolutions of both features. In this specific case study, we highlight the limits of the PV plants portfolio through an analysis of the local topography and wind distribution at several altitudes Then, we consider cloud opacity maps obtained from infrared channels. Despite being under-represented in the literature (only two studies have been found), infrared channel-based data present the advantage of offering nighttime observations of cloud cover, which contributes to improving early morning forecasts.

The proposed approaches are evaluated using 9 PV plants in France and for a testing period of 12 months.

How to cite: Bellinguer, K., Girard, R., Bontron, G., and Kariniotakis, G.: Use of Several Sources of Spatio-temporal Information to Improve Short-term Photovoltaic Power Forecasting., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14422, https://doi.org/10.5194/egusphere-egu23-14422, 2023.

Solar energy from photovoltaics (PV) is a major contributor to the power production, e.g., in Germany, with a growing share. It is a major contributor to renewable power production but highly volatile as it is heavily influenced by atmospheric conditions. Especially shading by clouds can change within seconds to minutes and cause ramps in irradiance and solar power production. Accurate short-term predictions (nowcasts) of irradiance for the next minutes can help to alleviate the impact of this volatility and improve the integration of solar power into energy grids. One approach for nowcasting is the use of all-sky imagers (ASI), ground based fisheye cameras which capture the current cloud situation. Therefore, cloud information is extracted from current images, future cloud states are extrapolated and converted into an irradiance nowcast. Despite substantial progress in the quality of the applied methods, current ASI nowcasting models still exhibit significant nowcast errors and struggle to reliably outperform persistence nowcasts for all situations. Therefore, we assessed the implications for nowcast performance of two common fundamental simplifications of ASI nowcasting models. Firstly, cloud evolution is often modelled by advection, i.e. simple displacement over time. Growth, shrinking or reshaping of clouds is usually neglected in the models. Additionally, the ASI viewing geometry may introduce a misrepresentation of the depicted cloud scene, which is also commonly neglected. The ASI views surrounding clouds from a single ground position and under varying angles. For direct irradiance however, the horizontal distribution of clouds and their intersection in the direction of the sun is essential. While ASI images are usually reprojected to comply with the required horizontal representation, the original difference in actual and required viewing geometry cannot be fully compensated. E.g., breaks between distant clouds may not be clearly visible by the ASI although modulating the irradiance. Kurtz et al. (2017) demonstrated a major impact by this geometric limitation. We applied a nowcasting model to synthetic ASI images of a simulated cloud scene to extend this previous study and analyze the errors introduced by both of the two commonly used simplifications of ASI nowcasting models. A large fraction of the nowcasting error is attributable to the simplifications, which implies a systematic baseline error of common ASI nowcasting models. While the implementation of more evolved cloud evolution and a better representation of relevant cloud geometry are challenging, this work indicates, that efforts to implement these improvements in ASI nowcasting models are a chance for a leap in performance of future nowcasting models.

 

Kurtz, B., Mejia, F., and Kleissl, J.: A virtual sky imager testbed for solar energy forecasting, Solar Energy, 158, 753–759, https://doi.org/10.1016/j.solener.2017.10.036, 2017.

How to cite: Gregor, P., Zinner, T., and Mayer, B.: How good can we get? – An analysis of systematic errors in common models for all-sky imager based irradiance nowcasting for solar energy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14645, https://doi.org/10.5194/egusphere-egu23-14645, 2023.

EGU23-14674 | Posters on site | ERE2.1

IEA Wind Task 51 Forecasting for the Weather Driven Energy System 

Gregor Giebel, Caroline Draxl, Helmut Frank, John Zack, Corinna Möhrlen, George Kariniotakis, Jethro Browell, Ricardo Bessa, and David Lenaghan
The energy system needs a range of forecast types for its operation in addition to the narrow wind power forecast. Therefore, the group behind the former IEA Wind Task 36 Forecasting for Wind Energy (running 6 years, from 2016-2021) has broadened its perspective on forecasting issues in part by reaching out to other IEA Technology Collaboration Programmes such as the ones for PV, hydropower, system integration, hydrogen etc. The three existing Work Packages (WPs) on NWP Improvements (WP1), Power and Uncertainty Forecasting (WP2) and optimal use of Forecasting Solutions (WP3), are complemented by thirteen work streams in a matrix structure.
 
The three work packages span three distinct areas of challenge in forecasting for the weather driven energy system. The first area is the continuing effort to improve the representation of physical processes in weather forecast models through both new high performance initializations and tailored parameterizations. The second area is the heterogeneity of the forecasters and end users, the full understanding of the uncertainties throughout the modelling chain and the incorporation of novel data into power forecasting algorithms. A third area is representation, communication, and use of these uncertainties to industry in forms that readily support decision-making in plant operations and electricity markets.
 
Task 51 will focus on facilitating communication and collaborations among international research groups engaged in the improvement of the accuracy and applicability of forecast models and their utility for the stakeholders in the wind industry, in the power sector and in the energy system.
 
The first two activities of Task 51 were (1) a workshop in Dublin on the State of the Art and Research Gaps for Forecasting. The results of the workshop will be compiled into a journal article, and (2) the publication of the IEA Recommended Practice for the Implementation of Renewable Energy Forecasting Solutions as an open access book by Elsevier. Other planned activities include further workshops on seasonal forecasting with emphasis on Dunkelflaute, storage and hydro in May 2023, a workshop on minute-scale forecasting (2024), and a workshop on extreme power system events (2025). The results of these interactive workshops will be compiled into a journal articles. Additionally, the Recommended Practice on Forecast Solution Selection will be updated to reflect the broader perspective.
 
Reference: Corinna Möhrlen, John Zack, Gregor Giebel (eds): IEA Wind Recommended Practice for the Implementation of Renewable Energy Forecasting Solutions. Elsevier, 348 pages, Nov. 2022. ISBN: 9780443186813. Download the individual chapters from https://www.sciencedirect.com/book/9780443186813/iea-wind-recommended-practice-for-the-implementation-of-renewable-energy-forecasting-solutions.

How to cite: Giebel, G., Draxl, C., Frank, H., Zack, J., Möhrlen, C., Kariniotakis, G., Browell, J., Bessa, R., and Lenaghan, D.: IEA Wind Task 51 Forecasting for the Weather Driven Energy System, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14674, https://doi.org/10.5194/egusphere-egu23-14674, 2023.

EGU23-14723 | Posters on site | ERE2.1

Analysis of Wind Energy production conditions in Catalonia (NE Spain) based on multiple data sources: station data, ERA-5 Reanalysis, WRF/CALMET, and EURO-CORDEX.  

Enric Aguilar, Oleg Skrynyk, Jon Xavier Olano Pozo, Anna Boqué Ciurana, and Antoni Domènech

Climate Change is largely affecting western societies and urgent decarbonization is a must to limit as much as possible global warming. Renewable energy is a critical component of this energy transition, as well as changes in human behavior. According to the Catalan Institute of Energy (ICAEN), Catalonia generated 2,706 GWh of wind energy in 2021, accounting for 6.4% of the total production.  

 

In this contribution, we explore the clear connection between wind energy capacity and weather and climate conditions. First, we use ERA-5 mean sea level pressure data (1959-2021) to identify the dominant circulation types and their evolution. Second, we combine these data with accurate local station data from the Catalan network of automatic weather stations (XEMA, from the acronym in Catalan) for the period 2009-2021 to identify the geographic patterns of wind energy production under the different circulation types. This analysis is refined using a coupled WRF/CALMET (on a 3km and 1km grid, respectively) hybrid dynamical/statistical downscaling of the GFS global data performed for the period 2016-2020. The investigation supports the assumption that, climatologically speaking, the southern areas in the mountains of Tarragona’s province and the northeastern area of Catalonia, bordering with France, are the most suitable for producing wind energy in most circumstances.  

 

Finally, using EURO-CORDEX climate model projections, we inspect future conditions.  

 

How to cite: Aguilar, E., Skrynyk, O., Olano Pozo, J. X., Boqué Ciurana, A., and Domènech, A.: Analysis of Wind Energy production conditions in Catalonia (NE Spain) based on multiple data sources: station data, ERA-5 Reanalysis, WRF/CALMET, and EURO-CORDEX. , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14723, https://doi.org/10.5194/egusphere-egu23-14723, 2023.

EGU23-14800 | Orals | ERE2.1

Integrated solar hydrogen production: Impact of the local climate 

Matthias M. May, Erica Schmitt, Johannes Grabenstein, Oliver Höhn, James Barry, Moritz Kölbach, and Kira Rehfeld

Hydrogen as a versatile, greenhouse gas-free energy carrier will play an important role in our future economy. Yet sustainable, competitive production and distribution of hydrogen remains a challenge. Highly integrated solar water splitting systems aim to combine solar energy harvesting and electrolysis in a single device, similar to a photovoltaic module.[1] Such a system can produce hydrogen locally without the requirement to be connected to the electricity grid. Unlike large electrolysis that draws power from the grid, the power density of such a device is reduced so far that it does not require active cooling, but its operating temperature will closely follow outdoor conditions.

Here, we present our work on high-efficiency integrated solar water splitting devices based on multi-junction solar absorbers. The light-absorbing component is sensitive to the shape of the solar spectrum and generally becomes more efficient at lower temperatures. Catalysis, on the other hand, benefits from higher temperatures. These conflicting trends wih respect to the temperature impact the design of the solar hydrogen production system. We analyse how the local climate affects production efficiency[2] and show in a lab study that adequate system design allows efficient operation at temperatures as low as -20°C.[3] These insights can help to design small-scale distributed solar hydrogen production for both temperate regions, but also more extreme climatic conditions.

[1] M.M. May et al., Nature Communications 6 (2015), 8286.
[2] M. Kölbach et al, Sustainable Energy & Fuels 6 (2022), 4062.
[3] M. Kölbach, K. Rehfeld, M.M. May, Energy & Environmental Sciences 14 (2021), 4410-4417.

How to cite: May, M. M., Schmitt, E., Grabenstein, J., Höhn, O., Barry, J., Kölbach, M., and Rehfeld, K.: Integrated solar hydrogen production: Impact of the local climate, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14800, https://doi.org/10.5194/egusphere-egu23-14800, 2023.

EGU23-14911 | ECS | Orals | ERE2.1

Wind farm wake recovery under different Planetary Boundary Layer schemes in WRF 

Oscar García-Santiago, Jake Badger, and Andrea N. Hahmann

Currently, to include the effects of wind farms in the Weather Research and Forecasting (WRF) model, a common choice is to use the Fitch wind farm parametrisation (WFP). This WFP has long been implemented into the WRF's standard repository and has been the subject of several wind resource assessment studies. However, one of the disadvantages of its current (WRF version 4.4) set-up is that it is constrained to one Planetary Boundary Layer (PBL) parametrisation. The Fitch scheme is coupled to the Mellor-Yamada Nakanishi Niino (MYNN) PBL parametrisation because it can inject Turbulent Kinetic Energy (TKE) from the turbines into the atmosphere. More importantly, it is the only PBL where the TKE advection can be activated. This feature is essential since it stores the TKE from one time step to the next and prevents the high TKE concentration at the turbine's location.

One way for the WFPs to become PBL-independent is to move away from focusing on the TKE source term and parametrise the turbulence in some other way. The Explicit Wake Parametrisation (EWP) is a WFP coupled to WRF that, as opposed to the Fitch scheme, does not include an explicit TKE source term and the turbulence is produced via enhanced vertical shear. The EWP is based on the assumption that the advection and diffusion terms in the RANS Navier-Stokes equations dominate the development of the wake. As a result, the drag equation is also related to the diffusion term from a 1.5 turbulence closure. The EWP then needs the turbine's information, wind speed and the turbulent diffusivity coefficient (Km) from the PBLs to calculate the wind deficit. Given the latter, the EWP can work if Km is present and comes from at least a 1.5-order turbulence closure PBL. However, studies have yet to attempt to prove this feature since it has only been used with the MYNN scheme.

In this study, we demonstrate the use of the EWP in WRF when other PBL schemes are used and the implications of this approach. We demonstrate this implementation under ideal neutral conditions with similar setups and forcings (surface roughness length, Coriolis parameter and hub-height wind speed) for two local (1.5-order closure) PBL schemes. Similarly, we test the possibility of coupling EWP into two non-local PBL schemes (first-order closure). The study focuses on the wake recovery behaviour, the drag strength and the power produced by an idealized wind farm under the four PBL schemes. Early results show faster wake recovery from non-local PBls than local ones, which could be related to the diffusivity coefficient values and the PBL's mixing rates.

How to cite: García-Santiago, O., Badger, J., and Hahmann, A. N.: Wind farm wake recovery under different Planetary Boundary Layer schemes in WRF, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14911, https://doi.org/10.5194/egusphere-egu23-14911, 2023.

EGU23-15319 | ECS | Posters on site | ERE2.1

A Temperature Profile Atlas based on Representative Profiles 

Sebastiaan Jamaer, Nicole van Lipzig, Dries Allaerts, and Johan Meyers

Vertical temperature profiles influence the wind power generation of large offshore wind farms through stability-dependent effects such as blockage and gravity waves. However, wind energy resource assessments often only consider idealized temperature profiles, which are not guaranteed to represent the atmospheric state and its variation. To assist the selection of atmospheric states, we created a temperature profile atlas and representative temperature profiles for Europe. To achieve this, we developed a new, generally applicable, analytical temperature model for the atmospheric boundary layer and lower troposphere with which the European temperature profiles over the period 2016-2020 are analyzed using a double clustering approach. This methodology results in eight representative profiles and spatial clusters with similarly behaving temperature profiles, which are quantified in cluster fingerprints. These representative profiles and cluster fingerprints can be used in the selection of background profiles for wind energy simulations such as LES models and can furthermore be used to make informed comparisons of results from different wind farm sites.

How to cite: Jamaer, S., van Lipzig, N., Allaerts, D., and Meyers, J.: A Temperature Profile Atlas based on Representative Profiles, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15319, https://doi.org/10.5194/egusphere-egu23-15319, 2023.

East Asia is a highly industrialized region with elevated GHGs emissions from extensive fossil fuel use. To achieve the Paris Agreement’s primary goal, an increase in the production of renewable energy is required in this region. Renewable energy generation, such as photovoltaic or wind power, is directly affected by weather and climate. Therefore, a detailed investigation of present and future changes in future renewable energy production potential using high-resolution and reliable climate data should be conducted to develop renewable energy policies. This study investigated recent changes in Wind Energy Potential (Wpot) over East Asia and projected them for the future period using the CORDEX-East Asia phase Ⅱ high-resolution multiple regional climate models. The averaged Wpot over the past 40 years (1979-2018) was highest in western and eastern Inner Mongolia across all seasons, and the recent Wpot in East Asia generally increased in spring, autumn, and winter, and decreased in summer, but had large inter-regional variability. In particular, the recent increase in Korea and Inner Mongolia was the largest in spring. Moreover, in inner Mongolia, wind speeds from 12 m s-1 or higher to less than 25 m s-1, which are the highest efficiency sections, were the most frequent and had the highest rate of increase. In the case of the RCP2.6 scenario, Wpot will increase considerably in central and southern China in the near future from 2021 to 2050 and decrease in summer in Korea, and will increase throughout East Asia in the mid-future (2051-2080) than in the near future, and in the far future (2081-2099) is projected to decrease. In the RCP8.5 scenario, the difference between regions is larger than that of the RCP2.6 scenario, and the increase is projected to be larger in central and southern China.

 

Acknowledgments: This work was funded by the Korea Meteorological Administration Research and Development Program under Grant KMI(KMI2021-00913).

How to cite: Park, C., Shin, S.-W., and Cha, D.-H.: Future Projections of Wind Energy Potential in East Asia Using the CORDEX-East Asia High-Resolution Multiple Regional Climate Models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15469, https://doi.org/10.5194/egusphere-egu23-15469, 2023.

EGU23-15554 | ECS | Orals | ERE2.1

Surface solar radiation trends over Europe assessed from ground-based measurements and satellite imagery and their comparison with climate models 

Leandro Cristian Segado-Moreno, José Antonio Ruiz-Arias, and Juan Pedro Montávez

Downward surface solar radiation (SSR) is the main component in the surface energy balance and the climate system, as well as being the fundamental source of energy in various forms of solar and photovoltaic technologies. It is therefore of great importance to know in detail the spatio-temporal variation of SSR, as well as its long-term trends. Scientific evidence has shown that the amount of solar radiation incident on the Earth’s surface is not stable over the years, but undergoes significant variations every decade. Until recently, ground-based observations have been the most reliable data source for SSR monitoring. Nevertheless, satellite-derived SSR measurements have a better spatial and temporal coverage, though the scientific literature on the use of satellite imagery for the study of SSR is still limited.

This study covers several purposes. First, a direct comparison between ground-based observations and satellite-derived estimates has been carried out, to determine the capability of the latter to reproduce measurements from surface observations. Monthly averaged time series of 108 land stations from GEBA (Global Energy Balance Archive) dataset (ground observations) have been compared to those estimated from satellite imagery by the Solargis model over the same locations. Solargis is a company based in Bratislava, dedicated to the assessment of the solar resource worldwide, using GIS (Geographic Information Systems). SSR anomalies measured at the surface and estimated from satellite images have been compared over Europe for the period 1994-2019. Second, multiannual SSR trends have also been calculated in detail (station-averaged and station-separated) for both ground-based and satellite-derived datasets, in the period of study. Finally, SSR time series have been compared to several CMIP6 (Coupled Model Intercomparison Project Phase 6 ) climate models runs.

The results show that the method of estimating SSR from satellite images is able to reproduce around 94% of the variability of the SSR measured by ground-based methods in Europe. In addition, trend analysis shows a general increase of SSR over the continent in the period of this study, with an average trend of 3.5 Wm-2decade-1for the observational data and 1.7 Wm-2decade-1for the satellite estimations. This increase in SSR may be associated with changes in the transmission of the atmosphere due to variations in cloud properties and aerosols. Finally, CMIP6 time series average over all models for RCP8.5 scenario shows exactly the same trend as the satellite-derived dataset, which suggests there are still some variables not considered by satellite imagery methods and climate models.

How to cite: Segado-Moreno, L. C., Ruiz-Arias, J. A., and Montávez, J. P.: Surface solar radiation trends over Europe assessed from ground-based measurements and satellite imagery and their comparison with climate models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15554, https://doi.org/10.5194/egusphere-egu23-15554, 2023.

EGU23-15617 | ECS | Posters on site | ERE2.1

A Computational Fluid Dynamics based framework to assess the wind energy potential of an urban landscape: A case study in Brussels 

Sampath Kumar Raghunathan Srikumar, Gabriele Mosca, Ioannis Tsionas, Maider Llaguno-Munitxa, André Stephan, and Alessandro Gambale

Wind is a clean and renewable energy source that has the potential to significantly contribute to the electricity supply in urban areas. Electricity generation through Micro Wind Turbines (MWTs) in an urban setting is not often implemented given their expected low performance due to low wind speed. Wind speed is indeed generally lower in urban areas than in open, rural, and coastal areas: buildings and structures represent obstacles to the wind flow and reduce its velocity. But those same obstacles also locally accelerate the flow at some locations, so that accurate positioning of wind turbines can often result in a satisfactory performance. 

In the present work, a framework is detailed to assess the wind energy potential of an urban neighborhood using Computational Fluid Dynamics (CFD) and applied to the Northern District of Brussels, Belgium, a neighborhood that has the ambition to become a Positive Energy District. Assessing the wind energy potential of an urban area requires knowledge of local wind properties (speed, direction, turbulence) to a high spatial resolution, as conditions even on a single roof are not uniform. CFD is a powerful tool that can be used to discern wind patterns and aid in an accurate assessment of the wind energy potential. By using CFD, it is possible to accurately predict the wind speed, direction and turbulence within an urban landscape, taking into account the effects of buildings, terrain and other structures. 

Statistical wind data from the last 30 years collected by the nearest meteorological station is used to define the conditions for a large enough number (typically 5-10) of CFD simulations for each wind direction. Based on the obtained results, the potential energy output of a specific MWT can be predicted and sites with suitable conditions can be identified. Simulations are performed using the opensource finite-volume solver OpenFOAM v7. A modified RANS turbulence model (k-ω SST)  with the improved Atmospheric Boundary Layer (ABL) approach from Bellegoni et al  is used to solve the flow equations in order to improve the accuracy of results. 

The numerical analysis allowed to identify the most suitable locations for MWTs in Brussels Northern District, demonstrating how the described approach can be effectively used in assessing the wind energy potential in an urban environment. 

How to cite: Raghunathan Srikumar, S. K., Mosca, G., Tsionas, I., Llaguno-Munitxa, M., Stephan, A., and Gambale, A.: A Computational Fluid Dynamics based framework to assess the wind energy potential of an urban landscape: A case study in Brussels, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15617, https://doi.org/10.5194/egusphere-egu23-15617, 2023.

EGU23-17208 | ECS | Orals | ERE2.1

Statistical characterization of simulated wind ramps 

Harish Baki, Sukanta Basu, and George Lavidas

Wind ramps, or rapid changes in wind speed, are a crucial aspect of atmospheric dynamics and
have significant implications for various wind energy applications. For example, wind ramps tend
to increase uncertainty in power output predictions. Furthermore, they also induce fatigue damage
to wind turbines.


In a recent study, DeMarco and Basu (2018; Wind Energy) used long-term observational
data from four geographical locations to characterize the tails of the wind ramp probability
distribution functions (pdfs). They showed that the pdfs from these various sites (ranging from
offshore to complex terrain) portray quasi-universal behavior. The tails of the pdfs are much
heavier than the Gaussian pdf and decay faster with increasing time increments. The tail-index
statistics, computed via the so-called Hill plots, exhibited minimal height dependency up to
approximately one hundred meters above the land or sea surface level. However, wind ramp
statistics at higher altitudes at Cabauw (the Netherlands) were quite distinct.


In the present study, we investigate if state-of-the-art reanalysis datasets capture the
intrinsic traits of wind ramp pdfs. Specifically, we make use of the newly released Copernicus
European Regional ReAnalysis (CERRA) dataset in conjunction with the popular fifth-generation
ECMWF reanalysis (ERA5) dataset. These datasets allow us to describe the characteristics of wind
ramp pdfs at high altitudes (up to 500 m). Given the disparity of the spatial resolution of CERRA
(~5.5 km) and ERA5 (~32 km) datasets, we are also able to demonstrate the impact of spatial
resolution on simulated tail index characteristics. Lastly, the influence of natural climate patterns
such as El-Nino and La-Nina on wind ramp pdfs are examined.

How to cite: Baki, H., Basu, S., and Lavidas, G.: Statistical characterization of simulated wind ramps, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17208, https://doi.org/10.5194/egusphere-egu23-17208, 2023.

EGU23-17290 | Orals | ERE2.1 | Highlight

Improving the satellite retrieval of surface solar irradiance during an eclipse 

Arindam Roy, Annette Hammer, Marion Schroedter-Homscheidt, Jorge Lezaca, Faiza Azam, Ontje Lünsdorf, Detlev Heinemann, and Yves-Marie Saint-Drenan

Solar eclipse causes high magnitude fluctuations in the Surface Solar Irradiance (SSI) for a short duration and consequently reduces the output of solar PV systems. Grid operators try to estimate the impending loss in PV power generation prior to the occurrence of an eclipse in order to schedule conventional generators for compensating the loss. The worldwide installed capacity of grid connected solar PV systems is expected to steeply rise in the coming decade as a result of the various policy initiatives aimed to tackle the climate change. In future electric supply networks with a high penetration of solar PV systems, such large ramps in generation could impact the stability of the network. Although a solar eclipse is a purely deterministic phenomenon, it’s impact on the satellite retrieval of Surface Solar Irradiance (SSI) is complicated due to the possibility of cloud presence in the regions affected by the eclipse. The extraterrestrial solar irradiance is reduced by the moon during an eclipse. On the one hand this causes clouds to appear darker and they get assigned lower reflectance values than they should have in reality. This leads to predicting higher values for the solar irradiance under these clouds than expected. On the other hand, the eclipse also reduces the clear sky irradiance reaching the earth surface. We developed a method to make corrections for both of these effects on the High Resolution Visible (HRV) channel images from Meteosat-11 The results are validated against ground measurements of irradiance provided by BSRN, IEA-PVPS, DTN and the National Weather Services networks. The validation is performed for sites with locations across Europe and for the last two eclipses.  

How to cite: Roy, A., Hammer, A., Schroedter-Homscheidt, M., Lezaca, J., Azam, F., Lünsdorf, O., Heinemann, D., and Saint-Drenan, Y.-M.: Improving the satellite retrieval of surface solar irradiance during an eclipse, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17290, https://doi.org/10.5194/egusphere-egu23-17290, 2023.

EGU23-500 | ECS | Orals | ERE2.2

Wind-solar-storage trade-offs in a decarbonising electricity system 

Anasuya Gangopadhyay, Ashwin K. Seshadri, and Balachandra Patil

In a steadily decarbonizing electricity system, it becomes increasingly important to explore cost-effective wind-solar-storage combinations to replace conventional fossil-fuelled power generation without compromising grid reliability. For a renewable-rich state in Southern India (Karnataka), we systematically assess the economics of various wind-solar-battery energy mixes given decreasing fossil-fuelled base generation and hydropower availability using Pareto frontiers. Our approach considers hourly load data, simulates generation based on hourly weather reanalysis products, and models the effects of battery charging and discharging on battery lifetime. We find that the allowed curtailment level limits the achievable grid reliability. Given declining baseload generation and available hydropower in the state electricity grid, the wind-solar-battery combined system can provide limited reliability, which declines as the grid is progressively decarbonized. A fully decarbonized grid with 2 GW of hydropower and a stringent 10% curtailment threshold can achieve maximum reliability of 66%. These values are sensitive to available hydropower capacity, baseload generation from fossil fuel, and the curtailment threshold. For a fully decarbonized grid, increasing the allowed curtailment threshold of renewable generation (during times of excess) to 80% would ensure 99% grid reliability. However, such a solution would be costly, requiring large wind-solar installations that exceed officially assessed potential, constrained by land allocation. Furthermore, these calculations show that adding storage capacity without concomitant expansion of renewable generation capacity is inefficient. The findings highlight the importance of a fresh examination of curtailment thresholds, renewable potential, and possibilities of demand-side management to evaluate pathways to the decarbonization of the electricity grid while maintaining reliability.

How to cite: Gangopadhyay, A., K. Seshadri, A., and Patil, B.: Wind-solar-storage trade-offs in a decarbonising electricity system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-500, https://doi.org/10.5194/egusphere-egu23-500, 2023.

EGU23-598 | ECS | Posters virtual | ERE2.2

Assessment of energy production potential from ocean currents along the Brazil coastline taking into account climate change 

Anderson Soares, Djalma Falcão, Raquel Toste, Luiz Landau, and Luiz Assad

The increasing electricity demand, coupled with the global need to reduce greenhouse gases, has made renewable energies an attractive solution to the problem. The oceans offer good alternatives for diversification and expansion of the energy matrix, among the possibilities for energy production is that one comes from ocean currents. Therefore, this work aims to evaluate the harnessing energy from ocean currents on the Brazilian coast based on the results of the global circulation model used in CMIP5, the Brazilian Earth System Model (BESM). Due to low temporal and spatial resolution, BESM results were downscaled using ROMS. In order to evaluate the effects of climate change on hydrokinetic production in the ocean, the simulation must represent the current climate conditions and the future condition,  based on the historical scenario and RCP4.5 respectively. For this purpose, these results were used as lateral boundary conditions and surface forcing into a two-way nested model composed of a donor and two receiver grids, with 1/5° and 1/15° of horizontal resolution, respectively. The highest resolution grids embrace the regions with the highest hydrokinetic potential on the southeastern and northern coasts, where the Brazilian current or North Brazilian current predominates. In addition to spatial and temporal variability, the synergy between ocean current as a source of electric power supply and others sources from the Brazilian electrical matrix will be discussed.

How to cite: Soares, A., Falcão, D., Toste, R., Landau, L., and Assad, L.: Assessment of energy production potential from ocean currents along the Brazil coastline taking into account climate change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-598, https://doi.org/10.5194/egusphere-egu23-598, 2023.

EGU23-664 | ECS | Posters on site | ERE2.2

Comparison of extreme value distributions for significant wave heights in the Mediterranean Sea 

Tahsin Görmüş, Burak Aydoğan, and Berna Ayat

The investigation of extreme sea conditions is of great importance regarding to the design and survivability of marine and offshore structures. Accurate quantification of the storm events in terms of the n-year return levels is needed. Extreme value distributions are used to analyze the extreme waves in the interested location, but the comparison of the distributions is usually ignored. This comparison is important, since a small deviation could mean much higher differences in the design parameters of the structures. This study evaluates the extreme wave conditions in the prescribed locations located in the Mediterranean Sea by quantitatively comparing different statistical distributions. The recent ERA5 dataset is used for the analysis. Statistical distributions of Generalized Extreme Value (GEV), Gumbel, Weibull and Lognormal are used based on the Annual Maximum Series (AMS); Weibull and Generalized Pareto Distribution (GPD) are used based on the Partial Duration Series (PDS). Peak-over-threshold method is used with 99.5th percentile threshold of the hourly 42-year long time-series after careful considerations of the alternatives found in the literature regarding to the threshold selection. The return levels of the significant wave height (Hm0,N) for each of the selected location is computed using the relation Hm0,N=F-1(1-1/λN) in where F denotes the cumulative distribution function of the used statistical distribution, N is the return period in years, and λ is the yearly frequency of the extreme events in the extracted time-series. The distribution parameters are acquired using the maximum likelihood approximation. The comparison of the distributions is made using the Anderson-Darling (AD) test. Mediterranean Sea exhibits diverse sea conditions. 12 spatially distributed locations are selected to represent the wave climate in the basin. The analysis clearly depicts the importance of the statistical distribution model selection. In the Gulf of Lion, 100-year return level Hm0,100 ranges between 9.5 m (Weibull/AMS) and 11.3 m (Gumbel/AMS). Inter-model uncertainty increases with the increasing return period. It is evaluated that the characteristics of the extreme wave series are determinative over the fitting accuracy of the distributions. Considering the best-fitting distributions among the 12 selected locations throughout the basin, the Hm0,100 values range between 4.9 m and 9.8 m. GEV distribution is selected as the best-fitting AMS distribution in five of those locations by the AD test, where for PDS models, Weibull distribution is outperformed the GPD in 11 points. This research is a part of a project supported by The Scientific and Technological Research Council of Turkey (TÜBİTAK) under grant number 122M279, and the first author is also supported by TÜBİTAK 2211 PhD scholarship programme.

How to cite: Görmüş, T., Aydoğan, B., and Ayat, B.: Comparison of extreme value distributions for significant wave heights in the Mediterranean Sea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-664, https://doi.org/10.5194/egusphere-egu23-664, 2023.

EGU23-790 | Posters on site | ERE2.2

Temporal variability of wind power in the Mediterranean and the Black Sea 

Burak Aydoğan, Tahsin Görmüş, and Berna Ayat

In this study, we investigated the spatiotemporal characteristics and variability of Mediterranean and Black Sea wind power. As the data source, ERA5 1-hourly dataset from the European Centre for Medium-Range Weather Forecasts is used in between the years of 1959 and 2020 and for 100-m altitude. The statistical analysis of the 62-year long time-series covered the investigation of several timescales of hourly, sub-daily, daily, monthly, seasonal, and yearly averaged values. The average values are spatially mapped for yearly and seasonal timescales. The study area has been divided into thirteen subsections to uncover the differences between the statistical parameters of the sub-basins. It is shown that in terms of wind power potential, two of the most energetic locations in the study area is Gulf of Lion and the Aegean Sea. The temporal average wind power density (WPD) map showed that the spatial maximum of the WPD reaches over 1100 W/m2 in the Gulf of Lion where the spatial average of the temporal average is over 370 W/m2. Several well-known indicators of variability have been used, such as yearly variability index, intra-annual variability index, and coefficient of variation to quantify the fluctuations. It is shown that in general, higher temporal variability has been obtained in the Eastern Black Sea, Eastern Tyrrhenian Sea, and the Sea of Azov for yearly and monthly timescales. A trend analysis based on over six-decade time-series showed that statistically significant downward trends are found in the Levantine Basin, Tunisian Plateau, and the Ionian Basin. Another important feature of the study is that WPD in the study area is also classified according the two spatial properties: water depth and the distance to the shoreline. A general conclusion of this investigation is that WPD increases with the distance to the shoreline where the most promising sub-sections with the highest potential within the first 25 km distance and up to 60 m water depth are the Aegean Sea and the Sea of Azov.

Acknowledgement: This research is supported by The Scientific and Technological Research Council of Turkey (TÜBİTAK) under grant number 122M279, and Tahsin Görmüş is also supported by TÜBİTAK 2211 PhD scholarship programme.

Keywords: wind power, temporal variability, Mediterranean, Black Sea

How to cite: Aydoğan, B., Görmüş, T., and Ayat, B.: Temporal variability of wind power in the Mediterranean and the Black Sea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-790, https://doi.org/10.5194/egusphere-egu23-790, 2023.

EGU23-1148 | ECS | Orals | ERE2.2

Cost-Potential Curves of Onshore Wind Energy: the Role of Disamenity Costs 

Oliver Ruhnau, Anselm Eicke, Raffaele Sgarlato, Tim Tröndle, and Lion Hirth

Numerical optimization models are used to develop scenarios of the future energy system. Usually, they optimize the energy mix subject to engineering costs such as equipment and fuel. For onshore wind energy, some of these models use cost-potential curves that indicate how much electricity can be generated at what cost. These curves are upward sloping mainly because windy sites are occupied first and further expanding wind energy means deploying less favorable resources. Meanwhile, real-world wind energy expansion is curbed by local resistance, regulatory constraints, and legal challenges. This presumably reflects the perceived adverse effect that onshore wind energy has on the local human population, as well as other negative external effects. These disamenity costs are at the core of this paper. We provide a comprehensive and consistent set of cost-potential curves of wind energy for all European countries that include disamenity costs, and which can be used in energy system modeling. We combine existing valuation of disamenity costs from the literature that describe the costs as a function of the distance between turbine and households with gridded population data, granular geospatial data of wind speeds, and additional land-use constraints to calculate such curves. We find that disamenity costs are not a game changer: for most countries and assumptions, the marginal levelized cost of onshore wind energy increase by 0.2–12.5 €/MWh.

How to cite: Ruhnau, O., Eicke, A., Sgarlato, R., Tröndle, T., and Hirth, L.: Cost-Potential Curves of Onshore Wind Energy: the Role of Disamenity Costs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1148, https://doi.org/10.5194/egusphere-egu23-1148, 2023.

Wind power onshore is one of the key technologies in the process of transitioning to a climate-neutral energy system. Yet, negative externalities of wind power for people and nature can occur. These externalities are usually regulated with spatial planning instruments that exclude certain areas from wind power development, like forest bans or increased setback distances to settlements, which were introduced across many regions in recent years. However, this regulatory practice can cause trade-offs between the regulated externalities. We use a multi-criteria GIS-based model of the potential areas for wind power onshore in Germany to identify and quantify these trade-offs for forest bans and setback distances to settlements.  Our results show that relevant trade-offs exist between a forest ban and the proximity of the remaining potential areas to settlements as well as between setback distances and the share of forest in the remaining potential area. Further, we find that individual and simultaneous implementations of the described regulations reduce the potential area of and production potential from wind power to an extent that future expansion targets for onshore wind power in Germany are no longer achievable.

How to cite: Tafarte, P., Geiger, C., and Lehmann, P.: The opportunity cost of land use restrictions and their impact on the energy transition - a case study for Germany´s onshore wind power, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2855, https://doi.org/10.5194/egusphere-egu23-2855, 2023.

EGU23-3367 | ECS | Orals | ERE2.2

Reducing the carbon footprint of mini-grids in Africa: the value of solar PV 

Théo Chamarande, Benoit Hingray, and Sandrine Mathy

Ensuring a universal access to a reliable, affordable, and sustainable energy by 2030 would require electrifying around 600 million people in Sub-Saharan Africa. The International Energy Agency estimates that one third of the future electricity connections would be met by mini-grids (MG). This electrification must be compatible with the objective of the Paris agreement and global pathways expected to limit warming to 1.5°C have to reach net-zero CO2 emission as soon as 2050. Autonomous MGs based on solar PV are there a promising solution to electrify rural areas. They have a low cost and allow to significantly reduce greenhouse gases (GHG) emissions compared to diesel generators.

Many different MG configurations hybridizing solar PV, diesel genset and batteries can supply the production required for a given community, and the sizing of MG is usually done by minimizing criteria such as the levelized cost of electricity (LCOE) and/or the carbon footprint (CFP) of the system. The goal of this study is to quantify the distance between the CFP optimum and the LCOE optimum configurations, and the potential to find compromising configurations between.

To do so, we consider fictitious hybrid MG for a large range of configurations (PV and diesel share, storage capacities) to supply typical load profiles for 93 different locations over Africa. The solar PV production is simulated using meteorological data at a 15min resolution (ERA5, Heliosat SARAH2) and we ensure that the electrical consumption is fully supplied with simple dispatch rules for the batteries and the genset.

We show that the least LCOE (LCOE*) and the least CFP (CFP*) configurations and values are mainly driven by the mean capacity factor of the solar resource and by its co-variability with the electric load profile. The larger the capacity factor, the lower the LCOE and the CFP, and the nighttime energy consumption strongly influences the CFP values for both configurations.

We show that, even in a configuration where all the production is obtained from solar, the CFP of a MG is non-negligible. If the CFP of a MG is obviously determined by the direct greenhouse gases (GHG) emissions related to fuel combustion, it indeed also results from the indirect GHG emissions obtained for solar PV and batteries production. For the studied locations, the CFP* values cannot go below a minimum threshold between 180 𝑔𝐶𝑂2/𝑘𝑊ℎ and 250 𝑔𝐶𝑂2/𝑘𝑊ℎ depending on the climatic zone and the load profile considered.

For almost all locations, the LCOE* configuration is obtained with a hybrid MG. We also show that this configuration usually allows a CFP reduction by more than 50% compared to a genset only configuration, and that, relatively high increases (often >20%) of the LCOE are needed to reduce further MG emissions at the level of the CFP* configuration. We however also show that significant CFP reduction can be obtained at low cost by choosing a configuration between the CFP* and the LCOE* configurations.

How to cite: Chamarande, T., Hingray, B., and Mathy, S.: Reducing the carbon footprint of mini-grids in Africa: the value of solar PV, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3367, https://doi.org/10.5194/egusphere-egu23-3367, 2023.

EGU23-4191 | ECS | Orals | ERE2.2 | Highlight

Inferring local social cost from renewable zoning decisions. Evidence from Lower Austria's wind power zoning. 

Sebastian Wehrle and Johannes Schmidt

Deploying renewable electricity generators comes with significant benefits but can also bring about social costs, for example, through interference with landscapes or the biosphere. 
We develop a novel methodology for quantifying the local social costs of renewable energy technologies. Through zoning decisions, authorities implicitly value spatial characteristics by trading-off different traits, such as wind resource quality or distance to settlements. 
We develop a simple theoretical model of renewable zoning and implement a corresponding discrete choice model that allows us to estimate the implied valuation from observed data in high spatial resolution. The wind power zoning in the federal state of Lower Austria, home to Austria's most significant wind resources, serves as our case study. 
According to our preliminary estimates, local social costs are non-negligible and significantly affect wind turbines' socially optimal spatial distribution. These results can inform optimal capacity choice in power system models and support wind turbine siting. Moreover, spatially highly resolved assessments of social cost are a significant improvement over conventional potential assessments based on binary exclusion criteria.

How to cite: Wehrle, S. and Schmidt, J.: Inferring local social cost from renewable zoning decisions. Evidence from Lower Austria's wind power zoning., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4191, https://doi.org/10.5194/egusphere-egu23-4191, 2023.

EGU23-5419 | Orals | ERE2.2

Historical analysis of global distribution of and trends in wind droughts 

Enrico Antonini, Edgar Virguez, Sara Ashfaq, Lei Duan, Tyler Ruggles, and Ken Caldeira

Wind droughts, or prolonged periods of low wind speeds, can be a severe issue for electricity systems that are largely reliant on wind generation. Therefore, it is important for energy system planning to understand the depth and distribution of wind droughts and their trends over time. In this study, we analyze the ERA5 weather reanalysis from 1979 through 2021, using an energy deficit metric that integrates the depth and duration of wind droughts over an annual temporal scale. Our analysis shows that the most severe wind droughts in many places occurred well before wind power generation started to penetrate power systems. This prevalence of wind droughts in the historical record, combined with little evidence for strong trends in their prevalence, suggests a statistical analysis of weather reanalysis products could provide valuable guidance in designing electricity systems reliant on wind power that are robust to wind droughts.

How to cite: Antonini, E., Virguez, E., Ashfaq, S., Duan, L., Ruggles, T., and Caldeira, K.: Historical analysis of global distribution of and trends in wind droughts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5419, https://doi.org/10.5194/egusphere-egu23-5419, 2023.

EGU23-7130 | ECS | Orals | ERE2.2

Studying renewable energy generation variability under future climate scenarios in Chile 

Guillermo Valenzuela-Venegas and Marianne Zeyringer

Chile has proven to be a country with great potential for renewable energies, favoring in the last decades the development of renewable energy projects, increasing its solar and wind capacities from 202 MW (1.1%) in 2012 to 6522 MW (21%) in 2021, and increasing further by 2022 to a total of 10476 MW (32%). According to the Chilean Energy Ministry, this trend will continue to increase to cover 70% of energy generation by 2030 with renewable energy sources and to meet the carbon neutrality scenario by 2050. However, since the electricity generation from renewable energy sources is affected by future extreme weather events caused by climate change, this possible uncertainty and variability should be considered when new energy projects are designed and developed. The present work aims to study the variability of renewable energy generation under future climate scenarios in Chile.

To capture the future variability of the weather conditions, we use the global climate models from Coupled Model Intercomparison Project Phase 6 (CMIP), which assess future climate change projections considering climate variability and uncertainties scenarios. We adapt these datasets for Chile, interpolate the wind speed based on model-level raw data proposed by Hahmann et al., and calculate capacity factors per renewable technology.

Through this study, we expect to explore the changes in renewable energy generation in Chile, estimating the impact of climate changes in this area. This work will help decision-makers decide on the future energy transition of Chile in the face of extreme changes in the climate condition of the country.

How to cite: Valenzuela-Venegas, G. and Zeyringer, M.: Studying renewable energy generation variability under future climate scenarios in Chile, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7130, https://doi.org/10.5194/egusphere-egu23-7130, 2023.

EGU23-7150 | ECS | Orals | ERE2.2

Future projections of wind energy capacity factors over Europe using CMIP6 

Idunn Aamnes Mostue, Marianne Zeyringer, Trude Storelvmo, and David Ruiz Baños

In a rapidly changing climate, changes in the frequency and intensity of future extreme weather events is expected to pose complex impact on future
weather-dependent energy systems. The contribution by Working Group I to the latest IPCC report (AR6) includes for the first time a dedicated chapter
on weather extremes. It demonstrates that even relatively small incremental increases in global mean temperature (+0.5C) cause statistically significant
changes in extremes on the global scale and for large regions. In 2021, Europe experienced the worst wind drought in 60 years, followed by extreme heatwave episodes and a national daily maximum temperature record of 40.3C in the UK in 2022.

The transition of the energy sector to renewable energy is key to reach the Paris Agreement goal of limiting global warming, but this also increases the energy sector’s exposure to future weather extremes in a changing climate. The impacts of climate variability and climate change on present and near future national energy systems are increasingly well documented within the literature. However, within this interdisciplinary field of research there has been little attention on impacts of extreme weather events on the energy system operations. Modellers usually use historic weather data and therefore do not consider ”new” extreme weather risks, posing problems on both the operational and infrastructural side. Omitting those risks can lead to designing systems that are operationally inadequate, i.e. prone to (long) power outages leading to major social, economic and health consequences.

The present work aims to study the variability of renewable energy generation for weather years under different future climates over Europe. We will use different future climate scenarios from the Coupled Model Intercomparison Project 6th Phase (CMIP6), to assess future projections of wind energy capacity factors. The global datasets of climate data will be adapted for Europe where we will interpolate the wind speed based on model-level raw data and further create energy capacity factors. We expect this study to be a first step in exploring the future changes in and occurrences of extreme weather events, and how these will impact the generation of renewable energy over Europe. This will in turn contribute to the knowledge on how we can plan for climate resilient renewable energy systems robust to future extreme weather events over Europe.

How to cite: Mostue, I. A., Zeyringer, M., Storelvmo, T., and Ruiz Baños, D.: Future projections of wind energy capacity factors over Europe using CMIP6, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7150, https://doi.org/10.5194/egusphere-egu23-7150, 2023.

EGU23-7394 | ECS | Posters on site | ERE2.2

A stakeholder-based approach for the sustainable deployment of renewable energies in conflictual social contexts 

Robin Tutunaru, Stephan Bosch, Lukas Greßhake, and Uwe Holzhammer

For a sustainable energy transition, concepts are needed that can map the techno-economic, socio-ecological, spatial and temporal complexity of regional site decisions for renewable energies (RE). Remarkable in this respect is that so far hardly any knowledge is available on how to design a computer-based methodological approach that precisely analyses and reflects the individual positions of the regional actors of the energy transition and visualises them with respect to the specificity of the actor-related land use interests. Our study therefore aims to analyse the complex interactions between the diverse competing land use claims. The central thesis is that a sustainable deployment of RE has to address in particular the communication processes between actors of the energy transition. Hence, we aim to capture the specific perspectives of certain stakeholders on the expansion of renewable energies. In doing so, we want to visualise the results by means of Geographic Information Systems (GIS) in such a way that they can be understood by each stakeholder or citizen and subsequently allow a constructive debate on the suitability of certain areas for the RE expansion. Favourable and unfavourable renewable energy sites cannot be generalised from the outset, rather they are linked to the interests, values and norms of the actors (e.g. cost minimisation, sustainability, land use efficiency, landscape aesthetics).

In order to analyse this complex interplay of technological, economic, ecological and social parameters and to be able to carry out a standardised evaluation of a socially balanced regional renewable energy deployment, this study will introduce an innovative GIS-based methodology. Our approach helps to deal with the competing social interpretations and constructs of all regional stakeholders that strive for a sustainable energy future.

How to cite: Tutunaru, R., Bosch, S., Greßhake, L., and Holzhammer, U.: A stakeholder-based approach for the sustainable deployment of renewable energies in conflictual social contexts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7394, https://doi.org/10.5194/egusphere-egu23-7394, 2023.

Renewable energy sources are being increasingly utilized in order to mitigate climate change and phase out the use of fossil-based fuels. However, the impact of developing such energy sources on the land and ecosystem needs to be assessed and mitigated properly to avoid any source of problem shifting.

Hydropower is considered nationally and globally the dominant source of renewable energy that can effectively contribute to reducing the usage of fossil fuels as well as being a backbone to help other renewable energy sources with their problem of variability due to its flexibility of production. However, the alteration of the land dynamics due to its deployment varies significantly depending on various spatial and technological factors.

In Norway, more than 70% of hydropower production was developed in the period between 1950 and 1980.  yet, the identification of the land system used for this development and the alteration of the landscape remains unknown.

This work contributes to the limited insights of quantifying the land used for hydropower development in Norway and how the land has transformed due to this development over time. We classified historical aerial images representing the areas for 40 hydropower systems in Norway counting for 8.1 GWh installed capacity which is 24% of Norway’s total hydropower installed capacity and 12% of the total reservoir area. We analyzed what kind of land was used for this development and compared these historical images with recent images to assess the land use change surrounding these hydropower systems with a 1 km buffer zone. 

We found that 63% of the total reservoir areas were already existing water bodies while 9% of the vegetation land was used for this development. We also found that 84% of the reservoirs were built on existing lakes or lakes that were expanded due to hydropower developments.

Additionally, we found that vegetation percentage either remained still or continued growth in most of the analyzed schemes while urban development was slightly small counting only for scattered cabins deployment and construction of roads.  The results of this work help unveil the uncertainties between land dynamics and hydropower development in Norway.

 

 

How to cite: Kenawi, M.: Quantification of the land-use pattern and areal effects of the hydropower development in Norway, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9594, https://doi.org/10.5194/egusphere-egu23-9594, 2023.

EGU23-10553 | ECS | Orals | ERE2.2

Comparing the effects of large scale solar farms on climate and regional surface energy budget in different climate models 

Arya Samanta, Moritz Adam, Mathias M. May, and Kira Rehfeld

Solar panels of utility scale are a rapidly growing contribution to the renewable energy supply with increasing efficiency and steeply reducing costs of photovoltaics (PV). Although there is consensus on long term reduction of greenhouse gas emissions and advantages of avoided emissions by using PV systems, there is need to understand the climatic effects of land surface modifications of such systems.

We first review studies focusing on effects of utility-scale solar farms and compare their results in accordance to their characterization of a photovoltaic and the type of model used to evaluate effects. Then, we perform simulations of larger than current utility-scale solar farms but also comparatively small localized farms which are both characterized by modified land surface properties. These regions are either identified on the basis of solar insolation and desert-like criteria (low precipitation) or are proposed in existing studies for potential deployment of solar farms. The solar farm deployments are characterized by static or gradual changes in respective boundary conditions of albedo, soil roughness and outgoing longwave thermal properties. Separate experiments are conducted with non-dynamic and dynamic vegetation components to investigate potential feedbacks originating from the interplay of vegetation and precipitation. To this end, we use a comprehensive model (MPI-ESM-LR; Mauritsen et al., 2019), and the Earth System Model of Intermediate Complexity PlaSim (Fraedrich et al., 2005) to understand, and cross-validate, the effects in two models of different complexity model.

We examine the results considering changes in radiative forces and surface energy budget and, therefore, the surface temperatures which can likely lead to atmospheric circulation patterns, precipitation and vegetation feedbacks. If lower complexity models provide results in an acceptable ballpark of comprehensive ESMs, then they could be further used for future quick compute simulations with various deployment scenarios and experimentation with variable technical aspects. Spatially explicit deployment of PV with focus on parameterized thermal properties dependent on the simulated climate would also allows us to look at the complementary effect of climate on panels and could help constrain the effect of different pathways on PV technology in the future.

How to cite: Samanta, A., Adam, M., May, M. M., and Rehfeld, K.: Comparing the effects of large scale solar farms on climate and regional surface energy budget in different climate models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10553, https://doi.org/10.5194/egusphere-egu23-10553, 2023.

EGU23-10896 | ECS | Orals | ERE2.2

Evaluating the physical limits to technical wind energy potential over onshore Germany in 2050 

Jonathan Minz, Axel Kleidon, Marc Imberger, Oliver Branch, Jake Badger, and Volker Wulfmeyer

Energy scenarios envision installation of up to 230 GW of wind capacity over available areas within the German onshore by 2050. The associated technical wind energy potential is typically derived assuming that the electricity generated by the wind turbines does not affect the wind resource. Consequently, future capacity factors, the ratio of generation to installed capacity, are implicitly assumed to be independent of the extent to which the wind resource is depleted. However, capacity factors reduce as wind capacity is increased. This is because kinetic energy (KE) removal lowers wind speeds that result in lower generation from the turbines. To assess the relevance of this resource depletion effect on capacity factors, we simulated electricity generation by wind turbines with a range of hypothetical and planned deployment scenarios using the Weather Research and Forecasting (WRF) model that incorporates the effects of atmosphere - turbine interactions and compared these to estimates derived from a simple, momentum-balance approach (VKE). Despite potential biases in modelled wind speeds, we find that for a typical planned scenario of ~200 GW deployed over 13.8% of land area, mean annual wind speeds reduce by an average of 0.4 m s-1 compared to the case where the impact of atmospheric - turbine interactions is excluded. Associated reductions in capacity factor are up to 20% in regions of high installed capacities. To isolate the key atmospheric influence, we compare the simulated range of wind speeds and capacity factors with those from the VKE model that only accounts for KE removal effects. We find that the KE removal effects play the dominant role in shaping the reductions in wind speeds and capacity factors, thus providing a simple tool to capture these effects.  We conclude that with increased deployment of wind energy in the context of the energy transition, these wind resource depletion effects need to be taken into account, but this can be done in a comparatively simple and physical way.

How to cite: Minz, J., Kleidon, A., Imberger, M., Branch, O., Badger, J., and Wulfmeyer, V.: Evaluating the physical limits to technical wind energy potential over onshore Germany in 2050, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10896, https://doi.org/10.5194/egusphere-egu23-10896, 2023.

EGU23-11226 | ECS | Posters on site | ERE2.2

Climate effects of wind farm in China 

Yinglu Liu

Building a new power system with new energy as the main body is a fundamental measure for energy and power sector to achieve carbon peak and carbon neutrality, and also a prerequisite for the whole economy and society to achieve the goal of "double carbon". However, how to construct a new type of power system is still a global problem, and its solution needs to rely on multidisciplinary knowledge. In this paper, a new power system analysis framework is constructed, and the structural characteristics and operation mechanism of the new power system are analyzed from the perspective of multidisciplinary comprehensive analysis. Based on this framework, we can initially diagnose various problems encountered in the construction of new power system and find possible solutions. Different actors participating in the construction of new power system can also find their own strength points in it and contribute to the security, stability and economic operation of the system.

How to cite: Liu, Y.: Climate effects of wind farm in China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11226, https://doi.org/10.5194/egusphere-egu23-11226, 2023.

EGU23-11780 | ECS | Orals | ERE2.2

Enabling agency: trade-offs between regional and European design flexibility in renewable energy systems 

Koen van Greevenbroek and Aleksander Grochowicz

To fulfil the Paris agreement, European countries have set out decarbonisation targets for 2050 and to reach them plan to massively expand the deployment of renewable energy technologies. Within the European Union, the member states are responsible for mapping out national strategies that meet the overarching EU objectives, including those of the recent REPowerEU plan. At the same time, the European electricity network is highly integrated with many interdependencies such that national policy decisions already have cross borders effects.


We study trade-offs between design flexibility on a regional level and in the entire network, and whether decisions by some actors (i.e. countries, regions or the EU) can enable or restrict the choices of others. This is done using the open sector-coupled energy system optimisation model PyPSA-Eur-Sec at a high spatial and temporal resolution, aiming at carbon-neutral scenarios for 2050. We define design flexibility in the context of near-optimal feasible spaces ---  using recent advances we are able to approximate the joint near-optimal feasible space for both a particular region and the rest of the system. By intersecting near-optimal spaces for different scenarios, we make this approach robust to uncertainties including weather variability and technology costs. For a number of selected regions in Europe, we thus look for both regional and European investment decisions which enable or restrict agency by enlarging or shrinking the space of solutions compatible with the decarbonisation targets for 2050.

How to cite: van Greevenbroek, K. and Grochowicz, A.: Enabling agency: trade-offs between regional and European design flexibility in renewable energy systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11780, https://doi.org/10.5194/egusphere-egu23-11780, 2023.

EGU23-12295 | ECS | Orals | ERE2.2

Identifying weather stress events from power system optimisation outputs 

Aleksander Grochowicz, Koen van Greevenbroek, and Hannah Bloomfield

The climate crisis and cost reductions in key technologies like solar, wind, and batteries are pushing an ambitious transition of power systems to renewables. This shift towards intermittent generation deepens the impact of weather and climate on the energy sector and can introduce new risks if not accounted for properly. Furthermore, as the ramifications of climate change are only to become even more noticeable, extreme events are expected to increase both in frequency and intensity. This in itself may lead to additional stress on renewable power systems, and recent research in energy meteorology relates these extreme weather events to so-called compound weather events, which are caused by more than one variable or component at the same time. However, compound events, their characteristics, and their risk for energy systems design are not yet well understood.

In this work, we use outputs of a power system model to identify what meteorological drivers lead to difficult periods and stress in the European electricity system. For this we couple energy modelling and meteorology in an iterative process that can connect weather insights from a synoptic scale to features of a highly resolved representation of the European electricity network. We use the open energy system model PyPSA-Eur with four decades of reanalysis weather data to find cost-minimal solutions for a fully decarbonised European power system. Dual variables of these optima are used to identify difficult weather periods, understood as periods that drive system design and total cost. This use of dual variables of the optima - as opposed to studying weather data in isolation - allows for a more accurate identification of difficult periods, tailored to the energy system at hand. We then characterise the underlying weather conditions during those periods and assess their effects on the power system and energy variables. Due to the level of integration, some of these spread across the entire continent, whereas other phenomena remain local; they can be of varied intensity and persist on different time scales.

Bringing an enhanced understanding of which weather events are difficult for energy systems, this approach can help to find obstacles for a transition to a fully renewable European power network, and inform how certain risks can be avoided or resilience strengthened.

How to cite: Grochowicz, A., van Greevenbroek, K., and Bloomfield, H.: Identifying weather stress events from power system optimisation outputs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12295, https://doi.org/10.5194/egusphere-egu23-12295, 2023.

EGU23-12347 | ECS | Orals | ERE2.2

Modelling the just allocation of energy infrastructure - Implications of assumptions and definitions of justice on model results 

Oskar Vågerö, Marianne Zeyringer, and Tor Håkon Jackson Inderberg

What constitutes socially just or unjust energy systems or transitions can be derived from the philosophy and principles of justice. Assessments of justice and modelling outputs leads to great differences based on which justice principles are applied. From the little research so far published in the intersection between energy systems modelling and justice, we find that comparisons between the two principles of utilitarianism and egalitarianism dominate in assessments of distributive justice, with the latter most often considered representing a 'just energy system'. Not recognising alternative and equally valid principles of justice, resting on e.g. capabilities, responsibilities and/or opportunities, may contribute to a narrow understanding of justice that fail to align with the views of different individuals, stakeholders and societies. More importantly, it can lead to the unjust design of future energy systems and energy systems analysis. 

In this work, we contribute to the growing amount of research on justice in energy systems modelling by assessing the implications of different philosophical views on justice on modelling results. Through a modelling exercise with a power system model for Europe (highRES Europe), we explore different designs of a future net-zero European energy system, and its distributional implications based on different justice principles. In addition to the utilitarian and egalitarian approach, we include, among others, principles of 'polluters pay' and 'ability-to-pay', which take historical contributions of greenhouse gas emissions and the socio-economic conditions of a region into account. 

We find that socially just energy systems look significantly different depending on the justice principles applied. Key output metrics include costs, technology mixes and spatial deployment of electricity generation infrastructure. The results should contribute to a greater discussion among researchers on the implications of different constructions of justice in modelling, expansion of approaches, and demonstrate the importance of transparency and assumptions when communicating such results. 

How to cite: Vågerö, O., Zeyringer, M., and Inderberg, T. H. J.: Modelling the just allocation of energy infrastructure - Implications of assumptions and definitions of justice on model results, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12347, https://doi.org/10.5194/egusphere-egu23-12347, 2023.

EGU23-13185 * | Orals | ERE2.2 | Highlight

Estimating the Offshore Wind Energy potential of the North Sea considering exclusion zones and the efficiency of large wind farms clusters 

Andrea Hahmann, Aikaterini Mitsakou, Nicolás G. Alonso De Linaje, Oscar García-Santiago, Jake Badger, Jelle van Uden, Anders Rennuit-Mortensen, and Michiel den Haan

The European Union has set ambitious greenhouse gas reduction targets, stimulating renewable energy production and accelerating the deployment of offshore wind energy in northern European waters, mainly the North Sea. We investigate if the set targets are achievable given the wind climate of the North Sea and efficiency loss resulting from large-scale extraction of kinetic energy.

We utilise the wind climate of the North Sea estimated from ERA5 and the New European Wind Atlas (NEWA) to evaluate the offshore energy potential of this region. We consider three scenarios of wind turbine technologies: wind farms in operation today, existing plus wind farms in the construction and planning stage, and all wind farms, which include all possible areas where offshore wind farms could be built in the future, which are determined from current exclusions zones in the North Sea. We estimate the annual energy production and capacity factors per country for the various scenarios under free-stream conditions, considering wind farm wakes from engineering models and the loss of efficiency of huge wind farms. We study the sensitivity of the energy potential to the source of wind climate (ERA5 versus NEWA), whether the data is bias-corrected or not, and the method used to apply the wake losses to the wind farm considered. We also evaluate the possible year-to-year variability of these estimates.

How to cite: Hahmann, A., Mitsakou, A., Alonso De Linaje, N. G., García-Santiago, O., Badger, J., van Uden, J., Rennuit-Mortensen, A., and den Haan, M.: Estimating the Offshore Wind Energy potential of the North Sea considering exclusion zones and the efficiency of large wind farms clusters, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13185, https://doi.org/10.5194/egusphere-egu23-13185, 2023.

EGU23-13628 | Orals | ERE2.2

Solar potential mapping to address energy poverty in a data poor region: A case study in Plovdiv, Bulgaria 

Wilfried van Sark, Gabriela Koster, and Britta Ricker

Bulgaria suffers significantly from energy poverty. With the EU goal to reduce 55% of its emissions by 2030, careful considerations are needed in the decarbonization policies within the energy system to avoid redistributive consequences that affect vulnerable groups.

 

Decarbonizing the building sector through photovoltaic (PV) solar technology is a viable option and supported by EU directives. PV technology offers financial benefits for the public and reduces energy dependency from the grid. Mapping the solar potential of a building is needed to determine whether an investment in PV is viable. Solar potential mapping that incorporates socio-economic factors can inform policymakers on alleviating energy poverty.

 

In this paper, a solar potential mapping approach using ArcGIS Pro is developed that allows physical, technical, as well as socio-economic aspects, including social considerations. As a case study for Bulgaria, the city of Plovdiv was chosen.  Open datasets have been used. Energy affordability is used which can be determined on the basis of energy consumption and energy prices.

 

The results show that there is a high solar energy potential in Plovdiv, while the actual potential depends on which irradiance dataset is used. The potential is estimated to supply the entire city's electricity needs by 20-58%, which translates to providing electricity needs of about 90,000 to 135,000 inhabitants. The solar potential exceeds the building energy consumption needs of 200-300 kWh/m² in all the buildings in Plovdiv. The estimated potential savings after PV installation from utility bills is between €21-32 million annually. The socio-economic factors help place the potential values in perspective, thus visualizing the benefits of distributed PV systems. It strengthens the argument of developing policies including energy poverty indicators.

How to cite: van Sark, W., Koster, G., and Ricker, B.: Solar potential mapping to address energy poverty in a data poor region: A case study in Plovdiv, Bulgaria, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13628, https://doi.org/10.5194/egusphere-egu23-13628, 2023.

EGU23-13862 | ECS | Orals | ERE2.2

The impact of climate change on future electricity generation and demand patterns in Europe 

Franziska Schöniger, Gustav Resch, Demet Suna, Florian Hasengst, Nicolas Pardo-Garcia, Gerhard Totschnig, Herbert Formayer, Philipp Maier, David Leidinger, and Imran Nadeem

Motivation

With increasing decarbonisation and electrification of the energy system, the electricity system's vulnerability to extreme weather events is becoming a focus of energy system planning and operation. This requires intensified collaboration between the domains of climatology and energy system modelling for an accurate portrayal of the effects of climate change on future energy systems. In this study, we construct a consistent data set for Europe's future electricity generation and demand components (covering NUTS3-NUTS0 level) using current climate models, including hydropower generation, which is frequently absent in comparable data sets.

Method

The methodological approach combines climate and energy system modelling. Parameters like temperature, wind speed, radiation, and precipitation are processed to derive weather-dependent electricity generation and demand profiles in hourly resolution for Europe until 2100. On the electricity generation side (wind, solar, hydro run-of-river, hydro storage), technology-specific processing steps are conducted to generate electricity generation profiles from climate data, e.g. the combination of wind speed levels with power curves of turbines. On the electricity demand side, the impacts of electrification and changing temperature (e.g., increased cooling demand during heat waves) are assessed. We model various scenarios to evaluate the effect of different shares of renewable electricity generation and different grades of climate change impacts. Therefore, projections for the future energy system in two decarbonisation scenarios (DN and REF) are combined with two RCP pathways (RCP4.5 and RCP8.5).

The following weather-dependent generation and demand profiles are generated:

  • E-heating, e-cooling, and e-mobility charging demand (dependent on temperature)
  • Photovoltaics generation (dependent on radiation, losses dependent on temperature)
  • Wind generation (dependent on wind speed)
  • Hydro generation (dependent on hydro inflow)

Results and conclusions

From the processed climate data, we receive hourly profiles for electricity demand and supply for all European countries, which are used as inputs for the energy system modelling. The dataset allows for the systematic identification of critical situations in the electricity system (e.g., high demand and low renewable generation), which can pose a risk to supply security.

Figure 1 shows as an example the distribution of the annual wind, hydro run-off-river (RoR), and photovoltaics (PV) generation, as well as electricity demand for e-cooling and e-heating in the 30 weather years surrounding the modelled year 2050. We observe a higher standard deviation in hydro generation than in the other two generation technologies, which is especially high in the RCP8.5 scenario. The demand shows relatively low variations between years, again stronger in the RCP8.5 scenario.

Figure 1: Annual wind, hydro run-of-river (RoR), and photovoltaics (PV) generation, as well as electricity demand for cooling and heating in the 30 weather years around 2050 in one RCP4.5 and one RCP8.5 scenario for Austria. The energy system projections are based on two scenarios for the year 2050: DN (RCP4.5) and REF (RCP8.5).

The climate and energy data sets for the whole of Europe in hourly resolution until 2100 will be made available for open access in the course of the project SECURES.

Funding

The project SECURES is funded by the Climate and Energy Fund (Klima- und Energiefonds) under project number KR19AC0K17532.

How to cite: Schöniger, F., Resch, G., Suna, D., Hasengst, F., Pardo-Garcia, N., Totschnig, G., Formayer, H., Maier, P., Leidinger, D., and Nadeem, I.: The impact of climate change on future electricity generation and demand patterns in Europe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13862, https://doi.org/10.5194/egusphere-egu23-13862, 2023.

EGU23-14160 | Posters virtual | ERE2.2

Downscaling Sub-Saharan Africa energy projections for power system planning: impacts, inconsistencies, and potential improvements 

Arianna Leoni, Angelo Carlino, Wyatt Arnold, and Andrea Castelletti

Development pathways for Sub-Saharan Africa project a substantial increase in population and living standards. To accommodate the future energy demand, the power and the energy system community have been developing least-cost optimization models to support long-term planning. Given the rise of climate change impacts and the necessity to mitigate them in the future, investments in new energy infrastructure should contemplate carbon neutral alternatives wherever economically viable.

However, integrated assessment and long-term energy planning models usually focus on annual or seasonal energy balances neglecting higher time resolution dynamics that can actually lead to short but high impact events. Indeed, the variability of renewable generation and power demand can lead to significant risks of high electricity prices, transmission lines overload, and power generation deficits.

To quantify these impacts, we inform a power system simulation model, PowNet, with energy development pathways from the long-term energy system planning model, OSeMOSYS-TEMBA. While the latter models the development of all the countries in continental Africa with a seasonal resolution from 2015 to 2070, the first has an annual horizon with hourly resolution and focuses on countries included in the Southern African Power Pool. In particular, PowNet is used to optimize the dispatch of power from each source as well as the usage of transmission lines, and it is constrained to the power capacity available according to the long-term energy planning provided by the OSeMOSYS-TEMBA model. We assess these impacts in 2025 and 2030 under three climate policy scenarios: no climate policy, and constrained to 2.0°C and 1.5°C warming constraining emissions to a consistent pathway. We study the difference in generation mix, the impact on transmission lines overloading, power generation deficits, and electricity prices.

Preliminary results show an increase of the generation during the years, in particular of the renewable resources, that varies depending on the selected scenario. Moreover, power generation deficits and transmission lines overloading are observed in many countries, especially during the night. These impacts are to be associated with insufficient total power system capacity to meet power demand due to the low time and spatial resolution of the energy system model. Indeed, the increased dependency on variable renewable resources, and a higher resolution demand profile prove the need to further expand total capacity, the importance of flexible generation adopting a diverse energy portfolio, and the potential benefits of increasing transmission lines’ capacity. Finally, the lack ofpower storage technologies in the energy system model might also significantly affect capacity expansion plans and consequent impacts. These results show the importance of the assumptions embedded in energy system model and motivate methodological improvements to design coupled energy and power system pathways that remain reliable at high spatial and time resolution.

How to cite: Leoni, A., Carlino, A., Arnold, W., and Castelletti, A.: Downscaling Sub-Saharan Africa energy projections for power system planning: impacts, inconsistencies, and potential improvements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14160, https://doi.org/10.5194/egusphere-egu23-14160, 2023.

EGU23-15736 | ECS | Posters on site | ERE2.2

Where will the Norwegian wind power go? Comparison of generation and transmission expansion scenarios. 

Maximilian Roithner, James Price, Johannes Schmidt, and Marianne Zeyringer

The Norwegian electricity demand has been almost entirely (~95 %) met by hydropower (~140 TWh of annual production, ~30GW of installed generation capacity), and low power prices were predominant for years. This has led to the development of industry and consumer dependence on ubiquitous cheap energy. The energy price shock in 2022 elevated price levels and opens multiple possible futures. With rising demand to be expected through electrification, increases in wind power generation capacity have been discussed and at least onshore been met with scepticism, and acceptance issues. As the export of energy in the form of oil and gas has been a major source of income for Norway that is now sought to be replaced, additional stakes join the discussion. Ideas of energy intensive industry such as battery production or data centres which would rely on low electricity prices, while also bringing demand increases, have been expressed. 

The future path splits between (further) integration into the European power system and (more) isolation of the Norwegian system. This would be expressed through electricity transmission and generation equipment expansion, which are important measures to ensure the adequacy and low carbon intensity of future nation- or continent-wide power systems. Policies may be measured by different competing targets, such as national price levels (which if low are favourable for industry), transnational carbon intensity (which if low helps to reach climate targets) or cross-border electricity trade (which if high helps to balance the system and generates income for the exporter). 

 We explore those trade-offs with Norway as a case study. The technical potential for North Sea offshore wind generation expansion is evident, and policy targets to expand offshore wind generation to the level of current hydropower generation (the highest in Europe) exist. Yet, the expansion of subsea transmission capacities (which would allow for more balancing through the Norwegian hydro reservoirs) seems to be on hold. Using the expansion and dispatch optimizing power system model highRES, we present scenarios for different degrees of expansion of offshore wind generation and (mostly subsea) transmission, to illustrate the crossroads in Norwegian energy policy, whose outcome could impact the European system.

How to cite: Roithner, M., Price, J., Schmidt, J., and Zeyringer, M.: Where will the Norwegian wind power go? Comparison of generation and transmission expansion scenarios., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15736, https://doi.org/10.5194/egusphere-egu23-15736, 2023.

EGU23-16237 | ECS | Posters virtual | ERE2.2

A methodology for integrating community acceptance of wind energy into energy system modelling (ESM) 

Paola Velasco Herrejón, Marianne Zeyringer, Tanja Winther, and Johannes Schmidt

Decarbonisation of the energy system is key to achieving the Paris Agreement goal of limiting global temperature rise to below 2°C which can be achieved by electrified and interconnected systems with a high share of variable renewables. This transition is shaped by uncertain factors, which include technology innovation, resource availability, and socio-economic variables. Energy system modelling (ESM) has been a key policy tool to study decarbonisation pathways. ESM provides stakeholders in the energy sector with knowledge-based and systematic methods to reach decisions about which technologies to support. However, present-day ESM mainly integrates techno-economical input parameters, whereas social factors, such as local responses to new installations, are largely understudied. ESM might therefore produce solutions that are not accepted by communities and as a result, could jeopardize energy transition goals. The main goal of this presentation is to present the framework for WINDACCEPT, a Horizon Europe project that aims to develop an innovative and interdisciplinary mixed-methods approach integrating concepts of sociology (stakeholder analysis), economic philosophy (capability approach), and technology systems (energy systems modelling) to better define the ‘real world’ feasibility of large-scale wind farms from a range of economic, political, regulatory, and societal perspectives. This new methodology will be developed and applied to the case of Norway, a country with excellent wind resources but high local opposition towards their development. The selected case study is NVE area No. 40 which includes the municipalities of Hasvik, Hammerfest, Måsøy, Kvalsund, Alta, Porsanger, and Nordkapp. This case study was selected to provide deep knowledge of the context of wind energy social barriers in Norway based on the following factors: 1) excellent wind power conditions, 2) (partly) considered by the NVE as a suitable area for wind power development based on social and environmental factors, 3) a zone where three major RE have been cancelled, and 4) a Sámi area. The methodology aims to contribute to elucidating the impacts of community barriers and value the costs and benefits of alternative options on the net zero energy system design in Norway and the effects on long-term, whole system decarbonisation in an interconnected Europe. The proposed framework will also aim to maximise techno-social synergies that provide beneficial relationships between technological and social systems to increase the social sustainability of RES.

How to cite: Velasco Herrejón, P., Zeyringer, M., Winther, T., and Schmidt, J.: A methodology for integrating community acceptance of wind energy into energy system modelling (ESM), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16237, https://doi.org/10.5194/egusphere-egu23-16237, 2023.

EGU23-17356 | ECS | Orals | ERE2.2

Using expired weather forecasts to supply up to 10 000 years of weather data 

Petr Dolezal, Srinivasan Keshav, and Emily Shuckburgh

When modelling possible future renewable electricity systems, a strong focus needs to be directed to the input weather variables driving any such system. Since we cannot know the exact weather in any slightly distant future, a probabilistic approach is usually chosen, modelling the system over many possible scenarios, typically all of the past recorded weather data available. However, this narrows the range of situations considered to about 40 years, placing fundamental limits on the analysis, e.g. of rare, extreme scenarios.

In our work, we explore the possibility of using past expired ensemble forecasts from the ECMWF [1] to drastically increase the number of scenarios considered to up to 10 000 years of data. These ensemble forecasts are physical models that are regularly initialized from the same slightly perturbed snapshot, but due to the chaotic nature of weather, their predictions diverge from each other. The later stages of their predictions are thus entirely independent predictions of what the weather could have been, including the correct spatial correlations. We analyze the data from the operational archive of ECMWF to assess their suitability for modelling renewable systems of the future and demonstrate how this wealth of additional weather scenarios can enable the utilization of otherwise heavily data-dependent machine learning techniques in energy modelling. 



 [1] European Centre for Medium-Range Weather Forecasts (ECMWF) Atmospheric Model Ensemble extended forecast https://www.ecmwf.int/en/forecasts/datasets/set-vi

How to cite: Dolezal, P., Keshav, S., and Shuckburgh, E.: Using expired weather forecasts to supply up to 10 000 years of weather data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17356, https://doi.org/10.5194/egusphere-egu23-17356, 2023.

EGU23-17364 | Orals | ERE2.2

Global pathways to achieve universal electricity access in 2030 

Victhalia Zapata, Anteneh Dagnachew, Oreane Edelenbosch, and Detlef van Vuuren

There are 770 million people without access to electricity globally, and 77% live in Sub-Sahara Africa (SSA). If the current electrification trends continue, IEA projections indicate that still 670 million people will lack electricity access by 2030, meaning that the SDG7.1 goal of achieving universal electricity access will not be achieved with current policies. Most of the research on optimal solutions for achieving SDG7.1 is focused on SSA. However, a nonnegligible number of people still lack access in other regions; therefore, a global perspective is important. This work aims to spatially analyze the least-cost strategies for achieving universal electricity access globally, the investment needed, and the synergies with climate change mitigation. Optimal least-cost solutions vary depending on the local situation. For instance, the cost of in-situ systems depends on the spatial spread of households, local energy demand and resource availability. Therefore, high-resolution (HR) spatial assessment is needed, also for integrated global analysis.

For this research, we build upon the work of Dagnachew et al. for SSA and expand the scope to global. The model is updated and re-coded for open-source access, and the spatial resolution has been increased from 30’ x 30’ to 5’x 5’. The levelized cost (LCOE) for eleven plausible electrification solutions is assessed per grid cell worldwide to select the least-cost option. They can be summarized in three categories: central grid extension and two off-grid options, stand-alone and mini-grid systems. A central grid connection is the solution that usually offers the largest security of supply. However, for remote areas, the high cost of grid extension justifies prioritizing off-grid solutions. Mini-grids consist of small powerplant (s) that feed electricity into a distribution grid. It is the most reliable off-grid option and can be built ready for future grid connection.

The main factors influencing LCOE are socio-geographic conditions and potential local energy resources for wind and solar. The socio-geographic factors are annual electricity use per household, obtained from the integrated assessment model IMAGE, population density translated into the number of households per grid cell, population dispersion within the grid cells and urban/rural rates. Another important factor is the distance to the central grid, assessed per grid cell (5’x5’ resolution) and determines the cost of grid extension. Preliminary results indicate that after optimizing for the lowest cost, central grid densification is the most suitable option for most people currently lacking access. Photovoltaic systems are used the most for the off-grid options, combined with diesel for mini-grids and in solar home systems. Total investment for the SSA region for achieving SDG7.1 is estimated at around 600 billion.

How to cite: Zapata, V., Dagnachew, A., Edelenbosch, O., and van Vuuren, D.: Global pathways to achieve universal electricity access in 2030, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17364, https://doi.org/10.5194/egusphere-egu23-17364, 2023.

EGU23-17544 | ECS | Posters on site | ERE2.2

Enhancing Tidal Energy Forecasting Using Hybrid Online Machine Learning 

Thomas Monahan, Tianning Tang, and Thomas. A. A. Adcock

A hybrid model is proposed for the short-term online prediction of tidal currents. The harmonic residual analysis (HRA) model is designed to augment the numerical schemes employed by tidal energy installations by forecasting the residual error of existing methods. Using a combination of techniques from Information and Fractal Theory, a novel component selection criterion for singular spectrum analysis (SSA) is used to remove true noise from the residual time series and to decompose the signal into components that are appropriate for linear-recurrent forecasting (LRF) and high order fuzzy time series (HOFTS) respectively. The performance of the HRA method is evaluated using a combination of simulated and real data from sites in the United Kingdom and the United States. Results demonstrate the model's viability for 6-minute and 1-hour forecast horizons across sites exhibiting variable degrees of non-linearity. Empirical analysis of the resultant tidal energy forecast verifies the superior accuracy and reliability of the HRA method when compared with existing numerical schemes. Simulated data from three sites at the Pentland Firth, UK is also provided to facilitate further study of the site's power generation characteristics and to allow for direct model performance comparisons.

How to cite: Monahan, T., Tang, T., and Adcock, T. A. A.: Enhancing Tidal Energy Forecasting Using Hybrid Online Machine Learning, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17544, https://doi.org/10.5194/egusphere-egu23-17544, 2023.

EGU23-1455 | ECS | Orals | ERE2.3

Assessing the potential of low transmissivity aquifers for ATES systems: a case study in Flanders (Belgium) 

Luka Tas, David Simpson, and Thomas Hermans

The Member States of the European Union pledged to reduce greenhouse gas emissions by 80-95% by 2050. Shallow geothermal systems might substantially contribute by providing heating and cooling in a sustainable way through seasonally storing heat and cold in the shallow ground (<200m). When the minimum yield to install a cost-effective aquifer thermal energy storage (ATES) system cannot be met, borehole thermal energy storage (BTES), relying mostly on the thermal conductivity of the ground, is proposed. However, for large-scale applications, this requires the installation of hundreds of boreholes which entails a large cost and high disturbance of the underground. In such cases, ATES systems can nevertheless become interesting. In this contribution, we present a case study performed on a Ghent University campus, where the feasibility of ATES in an area with a low transmissivity was determined. The maximum yield of the aquifer was estimated  at 5 m³/h through pumping tests. Although this low yield was attributed to the fine grain size of the aquifer, membrane filtering index tests and long-term injection tests revealed that the clogging risk was limited. A groundwater model was used to optimize the well placement while limiting the risk of interactions between the wells resulting in a thermal breakthrough or flooding at the surface. It was shown that a well arrangement in a checkerboard pattern was most effective to reach these objectives. Hence, for large-scale projects, a minimal CO2 output might be reached using a (more cost-effective) ATES system even in low permeable sediments.

How to cite: Tas, L., Simpson, D., and Hermans, T.: Assessing the potential of low transmissivity aquifers for ATES systems: a case study in Flanders (Belgium), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1455, https://doi.org/10.5194/egusphere-egu23-1455, 2023.

EGU23-1566 | Orals | ERE2.3

A multi-criteria decision-making tool to identify optimal locations for PV-geothermal systems for Heating and cooling in industrial areas. 

Adela Ramos Escudero, Isabel García Gil, Angel Molina Garcia, and Maria del Socorro García Cascales

The consequences of climate change and the urgent need in the EU to produce our self-clean energy from renewable resources are rapidly changing the rules. To meet the goal to produce our energy with 45% from the renewable resource for 2030, the diversification of the renewable resources to use to produce our energy is compulsory, and not only from solar and wind. Renewable energy hybrid systems are proven to be the most energy efficient and emissions savers as they take most of the natural resources intermittently, which is usually a drawback for a single renewable energy system.

Spain (along with Portugal) accounts for the highest yearly radiation rates, which energy is mainly used to produce electricity. Moreover, in Spain, 31% of the total energy is consumed by industry eminently consumed in Industrial parks, considered energy-consumers hotspots. Therefore, a hybrid PV-geothermal system is proposed as a more efficient system to produce heat and cold from renewables for the industry, both for industrial processes and heating and cooling. However, Spain shows very different orography and climate conditions along its territory, provoking different performance ratios of the proposed hybrid systems. Among the most influential factors affecting these systems' environmental and economic performance are the yearly solar irradiation, the energy demand, and the geothermal resource potential that differ in a spatial component.

In this work, a Multicriteria Decision Making (MCDM) tool is created and applied to spatially assess the performance of these systems and identify the optimal zones for PV-geothermal hybrid facilities based on the main spatial environmental factors. The tool is applied in high energy industrial demand areas from the new "Heat map of Spain" (Ecology Transition and demographic challenge Ministry of Spain) and is developed in a GIS environment. The main results expected are the performance indicators of PV-geothermal systems in Spain for the industrial sectors and the selection of the optimal zones of these systems in Spain based on the energy demand, solar irradiation, and geothermal potential.

How to cite: Ramos Escudero, A., García Gil, I., Molina Garcia, A., and García Cascales, M. S.: A multi-criteria decision-making tool to identify optimal locations for PV-geothermal systems for Heating and cooling in industrial areas., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1566, https://doi.org/10.5194/egusphere-egu23-1566, 2023.

EGU23-2371 | Orals | ERE2.3

Predicting interactions between three neighbor open-loop Aquifer Thermal Energy Storage (ATES) systems in two overlaying aquifers in Brussels (Belgium) 

Alain Dassargues, Caroline De Paoli, Philippe Orban, Mathieu Agniel, Estelle Petitclerc, and Thierry Duren

Shallow open-loop Aquifer Thermal Energy Storage (ATES) systems have been adopted by three large adjacent buildings in the centre of Brussels. The doublets of pumping and reinjection wells of two administrative buildings are located in a shallow aquifer made of Cenozoic mixed sandy and silty sublayers and operations started in 2014 and 2017. A third ATES system located in the underlying deep aquifer made of Palaeozoic fractured phyllites and quartzites, was started recently (2020) to provide the needed heating and cooling power to a large multi-service building. Groundwater levels variations in these two aquifer systems are different and pumping tests performed in the upper aquifer system have shown no impact on the groundwater levels in the Palaeozoic bedrock aquifer. After being calibrated on groundwater flow conditions in both aquifers, a 3D hydrogeological model using Feflow© was developed to simulate the cumulative effect of the three geothermal installations in the two exploited aquifers.

In terms of heat interactions, a previous model has shown how the thermal imbalance of the ATES system started in 2014 was jeopardising the thermal state of the upper aquifer (Bulté et al. 2021). Here, interactions with the third ATES system located in the deep aquifer are studied and modelled with different operational scenarios. Even though hydraulic interactions between the two aquifers are very limited, heat exchanges occur between the two aquifers, through an aquitard formed by low permeability Cretaceous base deposits and the weathered top of the bedrock.

The simulation results show that despite the unbalanced ATES system affecting mainly the shallow groundwater conditions, an adjacent but deeper ATES system can operate without significant interactions. Acquisition of additional measured data (i.e., piezometric heads, groundwater temperatures, detailed pumping, injection flow rate, etc.) will be crucial to improve the reliability of the simulated results for different operational scenarios. This will be particularly useful for the future management of the three ATES systems in order to avoid losses in both efficiency and durability.

This work was mainly conducted in the frame of the Master thesis of Caroline De Paoli. This was done with the partial support of the MUSE project—Managing Urban Shallow geothermal Energy. MUSE has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 731166 under the terms of GeoERA program—ERA-NET Cofund Action.

Bulté, M.; Duren, T.; Bouhon, O.; Petitclerc, E.; Agniel, M.; Dassargues, A. Numerical modeling of the interference of thermally unbalanced Aquifer Thermal Energy Storage systems in Brussels (Belgium). Energies 2021, 14, 6241. Special Issue on Geothermal Systems, https://doi.org/10.3390/en14196241

How to cite: Dassargues, A., De Paoli, C., Orban, P., Agniel, M., Petitclerc, E., and Duren, T.: Predicting interactions between three neighbor open-loop Aquifer Thermal Energy Storage (ATES) systems in two overlaying aquifers in Brussels (Belgium), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2371, https://doi.org/10.5194/egusphere-egu23-2371, 2023.

In installations with multiple borehole heat exchangers (BHEs), neighboring BHEs commonly influence each other. Imbalanced heat extraction and operation over many years thus causes growing interference and a pronounced thermal anomaly in the ground. This may not only have detrimental environmental effects but hamper the long-term efficiency of the entire system. As a remedy, concepts for adjusting the geometric layout and individual heat extraction loads of BHEs to a given site condition and heat demand have been presented. However, the more critical question is how to obtain an optimal and well-controlled system during the entire lifespan that often covers decades. In most of the optimization concepts that have been developed so far, the optimal load distribution is calculated on the basis of an estimated fixed heating demand. It is clear that this is not a realistic assumption due to various reasons such as changing weather conditions or a shift in consumption behavior. In our presentation, a more flexible combined simulation-optimization is introduced that takes into account a fluctuating heat demand at a monthly resolution. Here, in case of a deviation from the predefined heating demand, the BHE loads are revised and adjusted to the new conditions. Another aspect that can be considered in this sequential updating procedure is the inaccuracy of the model predicting the heat transport mechanisms in the subsurface. The new sequential optimization allows accepting a margin of uncertainty in subsurface thermal responses and taking into account thermal conditions in the ground that differ from what has been initially predicted. In our work, for demonstration, a heat demand profile with a series of monthly variations as well as a range of uncertainties in the measured temperatures of some individual boreholes in a BHE field is chosen. The optimization problem is solved efficiently by linear programming. To demonstrate the capability of the sequential procedure, fields with different densities and configurations of BHEs are studied.

How to cite: Soltan Mohammadi, H., Ringel, L. M., and Bayer, P.: Sequential simulation-optimization of a borehole heat exchanger field considering variability in heating demand and subsurface thermal responses, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3243, https://doi.org/10.5194/egusphere-egu23-3243, 2023.

The absence of an instantaneous local thermal equilibrium between rock and fluid has been observed multiple times in geoscientific, and especially geothermal, applications. The alternative, describing heat transfer between phases explicitly following Newton’s law of cooling, has been found essential to describe various processes, such as thermal stresses around wellbores or thermal breakthrough curves. While heat transfer founds growing interest in the geoscientific community, parameterization of the heat transfer coefficient and experimental data is still ambiguous. On the other hand, heat transfer has been studied extensively for decades in mechanical engineering for applications such as heat exchangers, chemical catalytic reactors, and thermal insulation.

In this work, the lessons learned about heat transfer from mechanical engineering are presented and tested for validity and transferability to geoscientific applications. This includes the differentiation of several heat transfer mechanisms, various scale-dependent types of thermal non-equilibrium, and useful equations for the heat transfer coefficient. As will be pointed out, there are several key findings from mechanical engineering applications, that can be applied to geosciences almost directly. There are a few results that would require further verification, and there are substantial conceptual differences in the heat transfer between mechanical engineering and geosciences. This work will provide present key takeaways from mechanical engineering on heat transfer with a direct influence on geothermal projects and will point out future directions of required research in geosciences.

How to cite: Heinze, T.: Heat transfer in pores and fractures – lessons learned from mechanical engineering, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4563, https://doi.org/10.5194/egusphere-egu23-4563, 2023.

EGU23-5153 | Posters on site | ERE2.3

Case study of a groundwater source heat pump at a coastal aquifer 

Byoung Ohan Shim

A groundwater source heat pump (GWHP) system for heating and cooling of building is a proven technology which has been adapted worldwide. This system is located at a coastal aquifer consisted of sand and gravel sedimentary layers. The groundwater flow direction towards to coastline and the aquifer thickness is around 24m which is the same depth of pumping and injection wells. The purpose of the GWHP is water heating for a commercial bath facility and the installed heat pump capacity is 396 kW. The groundwater pumping rate is around 1000 m3/day at three wells and the thermally wasted water through heat exchanger reinjects to three injection wells. The pumping tests were conducted to calculate hydraulic parameters. The system operates 6 hours per day with a break of once a month period, and we analyzed the monitoring data of more than one year. At the pumping well the entering water temperatures ranges from 6.0 to 14.7°C, and the groundwater temperature range of injection well is between 2.0 and 8.3°C. From the assumed hydraulic parameters, boundary conditions of operation time, and water levels measured during pumping tests, the groundwater flow and thermal diffusion were simulated by FEFLOW numerical modeling. The simulation model could represent the area of thermal diffusion according to the operation time.  

Acknowledgment: This study is conducted by KIGAM basic project ‘Development for Climate Change Adaptation Technologies for Securing and Utilization Large-Scale Groundwater Resources (23-3411)’

How to cite: Shim, B. O.: Case study of a groundwater source heat pump at a coastal aquifer, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5153, https://doi.org/10.5194/egusphere-egu23-5153, 2023.

EGU23-5771 | ECS | Posters on site | ERE2.3

Experiences with an Enhanced Thermal Response Test (ETRT) with high groundwater flow 

Anna Albers, Hagen Steger, Roman Zorn, and Philipp Blum

With an enhanced thermal response test (ETRT) depth-specific effective thermal conductivities can be determined. For this, a correct determination of the specific heat load is crucial. With an ETRT the heat is injected along the depth of the borehole heat exchanger (BHE) by applying a defined voltage to an electrically conductive cable. Hereby, an uniform specific heat load along the entire length of the cable is assumed. However, the electrical resistance of the heating cable and therefore the specific heat load depend on temperature. In this study, an ETRT is conducted at a study site with high groundwater flow. The results are critically evaluated with regard to the specific heat load and depth-specific effective thermal conductivities. We show an inaccuracy of 12 % in the determination of effective thermal conductivities when assuming constant electrical resistance of the heating cable with time. When using temperature measurements from distributed temperature sensing (DTS) to adjust the specific heat load along the length of the heating cable, variations of the specific heat load along the BHE in the order of 3 % are observed. Depth-specific effective thermal conductivities are evaluated ranging between 3.3 W m-1 K-1 and 12 W m-1 K-1. For 60 % of the evaluated depth-intervals the results of the infinite line source (ILS) forward model do not converge according to the criterion of Δλeffeff < 0.05/20h. These depth intervals are characterised by high groundwater velocities (> 0.6 m d-1) and a temperature increase for the evaluation with linear regression of ΔT < 0.6 K. From our results, we provide recommendations for the determination and adjustment of the specific heat load during an ETRT to account for temporal and spatial variations. Furthermore, we emphasise the need for higher specific heat loads in groundwater influenced depth intervals and elaborate difficulties associated with the increase of the specific heat load and the corresponding temperature increase along the heating cable.

How to cite: Albers, A., Steger, H., Zorn, R., and Blum, P.: Experiences with an Enhanced Thermal Response Test (ETRT) with high groundwater flow, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5771, https://doi.org/10.5194/egusphere-egu23-5771, 2023.

EGU23-7458 | Orals | ERE2.3

Geothermal heat extraction from abandoned mines 

Jeroen van Hunen, Julien Mouli-Castillo, Alexandra Sweeney, Sophie Chapman, Charlotte Adams, and David Townsend

Water from abandoned, flooded mines can form an excellent low-enthalpy, renewable long-term heat source, provided it is managed properly. Its sustainability, however, is only as good as its proper management. The poor understanding of the condition of the mine, post-closure makes the investment in these projects risky compared to other alternatives. Our modelling allows us to explore uncertainties and reduce a variety of project risks.

By combining numerical and analytical methods with digitised legacy mine data, we developed a tool to estimate the variations in the abstraction water temperature over the lifetime of a project. We couple the heat transfer approximation method originally proposed by Rodriguez and Diaz (2009) to that of flow in a pipe network as described by Todini and Pilati (1987). We refine the original heat transfer approximation by accounting for a flow regime specific heat transfer coefficient between the rock mass and the water, as prescribed by Loredo et al. (2017). We also develop a novel weighting function to account for the interference between adjacent mine galleries.

This method is applied to investigate the scenario in which multiple users will extract heat from the same mine water block. We investigate the interference resulting from heat extraction at multiple locations, using a mine system from the North East of England as a study case. The results of this study provide constraints on the maximum mine water extraction rates and proximity of the different users. The poorly constrained connectivity (through mine shafts, connecting roadways or porous flow) between mine workings from different coal seams is shown to be one of the most significant uncertainties in assessing the feasibility of a mine system as a sustainable heat source.

References:

  • Loredo C, Banks D, Roqueñí N. Evaluation of analytical models for heat transfer in mine tunnels. Geothermics 2017; 69; 153-164.
  • Rodriguez R and Díaz M. Analysis of the utilization of mine galleries as geothermal heat exchangers by means a semi-empirical prediction method. Renewable Energy 2009; 34(7), 1716-1725.
  • Todini E and Pilati S. A gradient method for the analysis of pipe networks. Computer app. In water supply 1987; 1-20, v1.

How to cite: van Hunen, J., Mouli-Castillo, J., Sweeney, A., Chapman, S., Adams, C., and Townsend, D.: Geothermal heat extraction from abandoned mines, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7458, https://doi.org/10.5194/egusphere-egu23-7458, 2023.

EGU23-8811 | ECS | Posters on site | ERE2.3

Fast regional-scale technical shallow geothermal energy potential calculation with a steady-state solution of the finite line source 

Johannes Miocic, Lukas Schleichert, Adinda Van de Ven, and Roland Koenigsdorff

The heating and cooling sector needs a large-scale transformation to achieve the climate neutrality goals by 2050 as outlined in the European Green Deal. Heat pumps coupled with a borehole heat exchanger (BHE) are a frequently discussed option for reducing greenhouse gas emissions from the heating and cooling of residential buildings. The thermal interference between BHEs makes the calculation of the technical potential on a regional scale computing intensive. Here, we use a steady-state solution of the finite line source to rapidly calculate the technical geothermal energy potential for a study area of ~35.000 km² and for up to 8.6 million BHEs. The results show that the proposed methodology can be used to calculate the potential of ground source heat pumps for heating on a regional scale with a high accuracy. Limitations of the study include the random placement of BHEs within parcels (with regulatory restrictions applying), and the non-consideration of ground water flow.

How to cite: Miocic, J., Schleichert, L., Van de Ven, A., and Koenigsdorff, R.: Fast regional-scale technical shallow geothermal energy potential calculation with a steady-state solution of the finite line source, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8811, https://doi.org/10.5194/egusphere-egu23-8811, 2023.

EGU23-9432 | ECS | Orals | ERE2.3

Is commercially viable heat extraction from legacy mine workings in the UK sustainable without dynamic heat recharge? 

Mylene Receveur, Christopher McDermott, Stuart Gilfillan, Gus Fraser-Harris, and Ian Watson

There is an increasing interest in the use of the thermal energy within abandoned, flooded coal mines within the UK, which offers a potential seen as a low-carbon source that could support the decarbonizing of heating and contribute to the nation’s 2050 net-zero emission goal. With about 78% of UK dwellings currently using natural gas to fuel central heating, residential and commercial heating is responsible for 23% of the countries carbon emissions. Whilst all the underground coal mines are now closed, about 25% of the population still live above legacy mine workings, a proportion of which remains in deprived rural mining areas and is prone to be affected by energy poverty. Using an open-loop heat pump mine-water heating system, heat could be harnessed from the 12-20°C mine-water filling the underground mining voids to provide an economic low carbon heat resource that could directly benefit the local population, provided that the heat extracted does not exceed the heat in place.

Whilst the potential of flooded mine workings to provide sustainable heat energy has been extensively investigated, only a limited number of mine-water heating system are currently operating worldwide, such as Heerlen in the Netherlands. In order to aid the development of the resource in the UK, a better understanding of the sustainability and thermal footprint of heat extraction is required. However, generating an optimal production scenario through numerical modelling requires a thorough understanding of the geometry of mine workings. This is generally highly complex and subject to numerous uncertainties, due to the long history of mining, poor documentation of the mine workings and the inability to characterize the current state of the workings. Hence, no standard modelling approach to quantify the potential thermal resource of abandoned mine workings has yet been developed. In order to develop such a tool, it is essential to quantify the effects and uncertainties linked to the choice of a modelling approach, to the mine geometry or to the values of rock properties.  

Here, we focus the analysis on the relative importance of geometrical features in controlling the dynamic heat recharge and extraction rate from pillar-and-stall and longwall mines, using different modelling approaches. We show that the volume of the mining zone and the permeability contrasts between the caved and fracture zone are key controls on the thermal output and that equivalent porous models can reasonably reproduce the power output of more detailed models. A combination of georeferenced mining data, monitoring temperature, hydraulic data, and a range of typical rock property values for the coal measures is then used to develop a conceptual model of the Bilston Glen mine in the UK and provide a first assessment of its static heat potential, accounting for the uncertainty in the mined volume. Calibrated numerical models are finally developed and compared to the analytical solutions to get insights into the dynamic heat recharge of the system in the long-term, and support the development of a generic conceptual tool for the assessment of sustainable rate of heat extraction from mine workings.

How to cite: Receveur, M., McDermott, C., Gilfillan, S., Fraser-Harris, G., and Watson, I.: Is commercially viable heat extraction from legacy mine workings in the UK sustainable without dynamic heat recharge?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9432, https://doi.org/10.5194/egusphere-egu23-9432, 2023.

EGU23-12666 | ECS | Orals | ERE2.3

Thermally-controlled direct shear tests at the soil-concrete interface 

Arianna Lupattelli, Diana Salciarini, Benedetta Brunelli, and Elisabetta Cattoni

The promotion of Energy Geostructures (EGs) is strongly related to the use of renewable and clean energy resources for the heating and cooling of buildings. They couple the structural role of geostructures with the exploitation of Low Enthalpy Geothermal Energy (LEGE). During their operation, EGs are continuously subjected to thermal variations, due to the heat exchange between the soil and heat transfer fluid circulating in the pipes inserted in the structure. This can lead to an impact on the mechanical response of the structure, and the role of the soil-structure interface takes on relevance in this operation. Nevertheless, experimental results deriving from the literature on the Thermo-Mechanical (TM) soil-structure interface behavior suggest that the effect of temperature on the shear resistance is quite limited, in the case of interaction with a building material such as concrete, especially for coarse-grained soils. The case of fine-grained soils is more complex: some studies suggest an enhancement of the interface shear strength, showing an increase of adhesion or a slight increase in friction angle at the interface during heating; while other studies show no significant variations of the interface behavior with thermal cycles. Such differences are likely due to the multitude of experimental configurations, development protocols, and composition of the samples used during tests. With the aim of better understanding this controversial framework on the interface behavior, a modified device for direct shear tests was developed at the Laboratory of Geotechnical Engineering of the University of Perugia: starting from the conventional direct shear apparatus, this has been equipped with a heating cement plate, where a thermal resistance and a temperature probe for continuous temperature control have been integrated. The first tests on silty sand reconstituted samples have shown that the thermal effects at the interface are limited to a decrease in shear strength of less than 3%.

How to cite: Lupattelli, A., Salciarini, D., Brunelli, B., and Cattoni, E.: Thermally-controlled direct shear tests at the soil-concrete interface, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12666, https://doi.org/10.5194/egusphere-egu23-12666, 2023.

EGU23-13398 | ECS | Posters on site | ERE2.3

Shallow Geothermal Energy systems for micro-scale 5G DHC in the Mediterranean island of Cyprus 

Lazaros Aresti, Christos Makarounas, Georgios Florides, Toula Onoufriou, and Paul Christodoulides

Shallow Geothermal Energy (SGE) systems find application through the use of Ground Source Heat Pumps (GSHPs) for space heating and cooling. GSHPs provide a higher performance over the alternative conventional Air Source Heat Pump (ASHP) systems, and have seen an increased interest with the continuous energy price increase and the need for lowering the CO2 emissions to meet the European Union “Fit for 55” targets. The high initial capital required for the GSHP systems in the residential sector is the main preventive factor for the GSHP systems. Recent studies revealed that with the nearly Zero Energy Buildings (nZEB) EU derivative in effect, the residential dwellings are built with a higher insulation on the building’s envelop and therefore with a lower heating and cooling demand; hence the potential payback period of such systems is increased.

Geothermal energy District Heating (DH) on the other hand could make these systems more viable with the advantage of lower carbon emissions, lower maintenance and a lower cost, but at the moment the infrastructure and availability are mainly present in central and northern Europe, where a higher heating demand is required compared to the southern EU. Having a central unit for distribution however, requires a large plant area, and of course the need for infrastructure and insulated pipes. An alternative to these solutions could be the use of SGE systems at a micro scale level.

To this extent, this research aims to computationally investigate the possibility and potential of SGE systems for a micro-scale urban environment. A theoretical case study is developed, with the inclusion of residential blocks categorized as “islands” for the production, use and distribution of SGE as a form of 5th generation (5G) DH and Cooling (DHC) with Mediterranean climate in the island of Cyprus. The case study includes either multiple multi-story residential buildings with nZEB characteristics or multiple detached residential buildings within a residential block, typical for the island of Cyprus. The heating and cooling demands, as well as the peak loads are estimated and the Ground Loop Design (GLD) software is used to size the required vertical Ground Heat Exchangers (GHEs) with different configurations. The effect of the unbalanced ground temperature and the temperature gain/ loss from the heat distribution is examined with the use of COMSOL Multiphysics software. Results indicate a potential advantage of the use of GSHP systems at a residential use micro-scale in terms of costs reduction and promotion of the geothermal energy use.

How to cite: Aresti, L., Makarounas, C., Florides, G., Onoufriou, T., and Christodoulides, P.: Shallow Geothermal Energy systems for micro-scale 5G DHC in the Mediterranean island of Cyprus, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13398, https://doi.org/10.5194/egusphere-egu23-13398, 2023.

The geothermal heat available in urban environments is becoming increasingly interesting for its possible use as geothermal resource available at shallow depth beneath cities.

This heat is mainly composed of the natural thermal background regime of the area of interest, the anthropogenic effect due to the urbanization process and the contribution due to the global warming. To be able to differentiate between these contributions provides a better understanding on how the urban heat resource could be used and managed.

In detail, global climate warming has a direct consequence in the increase of surface air temperature over time affecting, at local scale, the heat energy exchanges between the air-ground interface. The air temperature fluctuations can penetrate several meters deep into the subsurface raising the ground surface temperatures and, consequently, the mean annual temperature of shallow aquifers. A detailed analysis of temporal series of air, ground and shallow depth ground temperature data is expected to show this behaviour.

The city of Padova and its surroundings, located in the north-east of Italy, were selected as case study area. Here, starting from a comprehensive analysis of surface air temperature variation in the last 60 years, the local climate change was tracked. The correspondence between increase temperature on surface and underground was researched using at first underground temperature profile data collected in surface groundwater wells in urban and agricultural areas. The preliminary results confirm the influence of air temperature variation, affected by global warming, on shallow depth ground. Next step consists in the analysis of underground temperature profile variations over approximately 100 m depth in a geothermal borehole installed in the city centre, to assess the contribution of the climatic temperature to the background thermal regime and anthropogenic heat effect.

How to cite: Di Sipio, E., Cenni, N., and Galgaro, A.: Climate change and subsurface urban heat island: ground surface, well temperature and surface air temperatures correlation in the city of Padova, Italy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14638, https://doi.org/10.5194/egusphere-egu23-14638, 2023.

EGU23-15169 | ECS | Posters on site | ERE2.3

Unmanaged conflicts and potential synergies between shallow geothermal systems in a Swiss urban aquifer 

Rodolfo Perego, Giorgia Dalla Santa, Antonio Galgaro, and Sebastian Pera

The use of shallow geothermal systems (SGS) as an efficient technology to provide clean thermal energy has become increasingly widespread, especially in urban settings: this is leading to a significant systems density and to the more frequent risk of thermal interactions between neighboring systems. This work presents a holistic 3D numerical model of the urban aquifer of Locarno (Switzerland), simulating mutual interactions between open and closed-loop SGS. Results show that the high amount of installed SGS in limited space is progressively creating mutual hydraulic and thermal interferences: negative, with a reduction of SGS efficiency and sustainability or (rarely) positive, when an accidental and unmanaged synergic effect is established due to favorable exploitation patterns and SGS locations. Moreover, the presence of underground structures affects the thermal conditions of the subsurface and consequently the operation of SGS. Neglecting an underground holistic vision of the hydro/thermogeological processes in urban areas could result in long-term efficiency losses and thermal issues for SGS solutions, also given the increasing exploitation of shallow geothermal energy for building conditioning.

How to cite: Perego, R., Dalla Santa, G., Galgaro, A., and Pera, S.: Unmanaged conflicts and potential synergies between shallow geothermal systems in a Swiss urban aquifer, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15169, https://doi.org/10.5194/egusphere-egu23-15169, 2023.

Shallow geothermal energy has been popularly used for house heating and cooling by combining borehole heat exchangers (BHEs) with a heat pump. The efficiency and sustainability of BHE systems are receiving increasing attention in recent years.  Groundwater flow, among the hydrogeothermal properties of the subsurface, is considered to be a critical positive factor in maintaining BHE efficiency, especially when the groundwater flux is greater than 10-7 m/s. However, in practice, exact information on local groundwater flow is typically not available.  Rough estimates may introduce significant uncertainty in the design an performance of BHE systems. In this study, we implemented an uncertainty analysis of groundwater flow impacts on the seasonal coefficient of performance for a heat pump (SCOP). We first built a numerical model based on an existing geothermal site using FEFLOW. Groundwater flow parameters including groundwater level, flow direction, and groundwater flux within the layered subsurface were assumed to follow a Gaussian distribution in which the mean value is determined from regional hydrogeological conditions. Afterward, we selected the input data sets about groundwater flow by using Sobol sequence sampling, and then employed the selected data sets and the corresponding simulated SCOP in a random forest regression for training and predicting. Preliminary results show that groundwater flux and flow direction have a significant impact on SCOP. The impact of groundwater flow direction is strongly correlated with the arrangement of the BHEs.

How to cite: Liu, Q. and Ptak, T.: Uncertainty analysis of groundwater flow impacts on the performance of a borehole heat exchanger array, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15401, https://doi.org/10.5194/egusphere-egu23-15401, 2023.

EGU23-15458 | Orals | ERE2.3

Numerical simulation of a sedimentation tank applied to an open loop Ground Heat Exchanger system 

Dorian Hernandez, Philippe Pasquier, and François Guibault

Ground Heat Exchanger (GHE) used with heat pumps have the potential to lower energy consumption and greenhouse gas emissions. In particular, Standing Column Well (SCW), which is a category of GHE that uses groundwater has the heat transfer medium, is more compact and less expensive than conventional closed-loop GHEs. SCWs are usually coupled with an injection well to enhance the advection process and the overall efficiency during peak power period. Due to the sediment load present in groundwater, water reinjection tends to clog the aquifer, making it less permeable, and in the worst case, leading to undesirable overflows. To avoid this problem, the use of a sedimentation tank placed before the injection well is investigated. To assess the feasibility of this solution, a fully coupled numerical model has been developed based on standard SCW conditions and on laboratory analysis performed on sediments. The fluid dynamics and settling processes have been coupled and simulated with the Mixture model at a constant temperature. Results show that a conventional sedimentation tank can reduce the sediment concentration in the groundwater returned to the aquifer for different flow rate conditions. As the temperature has a major impact on the sedimentation process, a coupled Heat transfer Mixture model simulation was developed to analyse the response of the tank efficiency for a range of typical SCW operating conditions.

How to cite: Hernandez, D., Pasquier, P., and Guibault, F.: Numerical simulation of a sedimentation tank applied to an open loop Ground Heat Exchanger system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15458, https://doi.org/10.5194/egusphere-egu23-15458, 2023.

EGU23-16239 | Posters on site | ERE2.3

Comparison between DTRT and GEOsniff TRT methods for thermophysical characterization of the ground 

Antonio Galgaro, Alessandro Visentin, Alberto Stella, Eloisa Di Sipio, and Giorgia Dalla Santa

The research is oriented to provide elements of knowledge, useful for the choice of new generation methods of in situ thermal characterization of the subsoil, which may be more suitable to provide quantitative information on the design and sizing parameters for closed-circuit heat exchange systems. In particular, it is essential to determine the thermal resistance of the ground heat exchanger as well as the ground undisturbed temperature and the thermal conductivity of the ground affected by the heat exchange processes, being able to differentiate the contributions of the different geological levels crossed by the ground heat exchanger. These on-site tests are necessary to design the system and determine the thermal characteristics of cement mixtures to be apply to finally sealing the wells in which the ground heat exchangers are installed.

This paper analyzes and compares the results obtained from two different on-site thermal response test methods, carried out to design a borefield of a GSHP plant, foreseen in the renovation project of the Swiss Embassy in Italy in Rome (RM). The boreholes reach a depth of 200m and are installed in a geological context characterized by volcano-clastic deposits. In particular, two methods of distributed investigation of subsoil temperature and thermal properties are compared. The two methods are based on different technologies: optical fiber heating cable (DTS) and an innovative method that uses smart spheres ("GEOsniff"- enOware) floating inside the boreholes, integrated with miniaturized electronics, able to measure the temperature of the water inside the tube all along the whole vertical.

 

Both tests were carried out closed in time and in the same borehole heat exchanger. In particular, the fiber optic DTS (Distributed Temperature Sensing) technology, based on hybrid fiber optic cable and heating wire, performs a distributed thermal response test (DTRT) in one of the vertical geothermal exchangers. The "enOware GEOsniff" technology, based on special sensors and heating cable, was realized 2 months after, to perform a second advanced distributed thermal response (E-TRT) test in the more than one vertical geothermal exchanger.

In addition, thermal conductivity measurements and laboratory characterizations were carried out on 4 samples acquired from the corings derived during the drilling operations, thus providing specific values of thermal conductivity of the different levels.

The thermal conductivity values obtained in different ways are directly compared and discussed.

How to cite: Galgaro, A., Visentin, A., Stella, A., Di Sipio, E., and Dalla Santa, G.: Comparison between DTRT and GEOsniff TRT methods for thermophysical characterization of the ground, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16239, https://doi.org/10.5194/egusphere-egu23-16239, 2023.

EGU23-407 | ECS | Orals | ERE2.4

Characterization of natural and synthetic organic matter and naturally-occurring radionuclides in the hypersaline geothermal fluids of Balmatt site, Mol, Belgium: preliminary results 

Val Maverick Abecia, Sonia Salah, Mirela Vasile, Ben Laenen, Simona Regenspurg, and Valérie Cappuyns

Low enthalpy geothermal energy utilization is currently of great interest in Europe as a clean and sustainable alternative energy source, due to its potential to meet the demand for both electricity and space-heating. The increased interest presently accelerates research and development particularly for deep-seated, hot sedimentary aquifers all over Europe. Among the least understood aspects is the presence of naturally-occurring radionuclides (NORs)  such as 226Ra, 228Ra, 222Rn, 210Po, and 210Pb and the underlying geochemical processes and constraints affecting their mobility. This study aims to characterize natural organic matter (NOM) and synthetic scaling and corrosion inhibitors and their by-products as a first step to determine their role in the partitioning and mobility of these radionuclides. A two-step dead-end filtration at 0.45 and 0.22 μm pore sizes was conducted for the hypersaline brine from the production and injection wells (TDS= 100-270 g/L) of the Balmatt geothermal site in an anoxic environment, to initially determine the total organic carbon (TOC) and radiochemistry per filtrate fraction. The TOC content of filter residues was measured by combustion catalytic oxidation method, while the filtrates were excluded due to their known low organic carbon content yet hypersaline nature, requiring large dilution factors. UV-VIS spectrophotometry of all brine filtrates using various wavelengths (i.e. 204, 220, 254, 280, 365, 400, 436, 665 nm) shows very low absorbance ranges (e.g. A254 = 0.03-0.07,  A280 = 0.01-0.05), corroborating with  low organic carbon contents. On the other hand, the absorbance values of the scaling and corrosion inhibitors are higher (e.g. A254 = 6-10 , A280= 5-8)  correlating to higher TOCs of 64 mg C/L and 180 mg C/L, respectively. This suggests that the synthetic inhibitors may be an additional source of organic compounds possibly affecting the partitioning and mobility of NORs. Initial results of the radiochemical analyses by liquid scintillation and alpha spectrometry also show that total activity of 210Pb and 210Po are relatively higher at the production side (210Pb =0.20 Bq/L, 210Po=37 mBq/L) than the injection side (210Pb <0.09 Bq/L, 210Po=0.9 mBq/L), possibly suggesting their fractionation from the fluid to the known mineral scales such as galena. Other NORs measured using gamma spectroscopy indicate high activities of 222Rn (12.2 Bq/L), 226Ra (124-136 Bq/L) and 228Ra (9.3 Bq/L). In the future, leaching experiments will be conducted using reservoir rock cuttings from the geothermal wells to possibly distinguish between NOMs and synthetic inhibitor by-products. Size exclusion chromatography per filter fraction using a tangential flow setup will also be conducted to further characterize the organic matter. Reverse osmosis and solid phase separation are being considered in sample preparation to resolve the issue of low TOC but very high salt content of the fluids of the Balmatt geothermal system.

How to cite: Abecia, V. M., Salah, S., Vasile, M., Laenen, B., Regenspurg, S., and Cappuyns, V.: Characterization of natural and synthetic organic matter and naturally-occurring radionuclides in the hypersaline geothermal fluids of Balmatt site, Mol, Belgium: preliminary results, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-407, https://doi.org/10.5194/egusphere-egu23-407, 2023.

EGU23-872 | ECS | Posters virtual | ERE2.4

A Comparative Study of Geothermal Potential of the East and West-Coast Hot Springs, India 

Susmita Goswami and Abhishek Rai

Geothermal energy is an important source that has the potential to contribute to the energy needs of society. In this study, we try to understand the hydro-geological characteristics of the hot springs located in the two important coastal terrains of India. i.e., East Coast and West Coast. Our findings indicate that the west coast springs are dominated by Na-Cl, Ca-SO4, and Na-HCO3 water types, indicating that seawater intrusion through deep penetrating faults and fractures may have an impact. The majority of the east coast's hot springs which are located in Odisha have Na-Cl, and Ca-HCO3 water types and a short residence period. According to our findings, hot springs on the west coast have a higher potential compared to Odisha for producing geothermal energy. We find that hot springs on the West Coast are mostly composed of Na-Cl, Ca-SO4, and Na-HCO3 water and that they may be influenced by seawater intrusion. Hot springs on the east coast, particularly in Odisha, have Na-Cl and Ca-HCO3 water and have a short residence period. Some ionic concentrations have a strong correlation, indicating that seawater-rock interactions were dominant in the West Coast and some springs of Odisha thermal springs. The reservoir temperatures for the west and east coast springs, using the saturation-index method is found to be 120±5°C and 110±5°C. The reservoir depths and geothermal fluid circulation depths are estimated to be 1.71 ±0.17km and 1.37±0.32km, respectively. The control of water circulation in hot-spring systems is largely dependent on faults and subsurface high heat flow.  In comparison to Odisha, the West Coast thermal water is heated at a greater depth (1.71±0.17km at 120±5°C); circulation and mixing of thermal water via deeply connected faults and NNW-SSE lineaments. The West Coast springs' reservoir and geothermal fluid circulation depths are greater than those of Odisha, indicating greater circulation.

How to cite: Goswami, S. and Rai, A.: A Comparative Study of Geothermal Potential of the East and West-Coast Hot Springs, India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-872, https://doi.org/10.5194/egusphere-egu23-872, 2023.

EGU23-2534 | Posters on site | ERE2.4

Combining geophysical, geochemical and geological studies toward plausible geothermal models at the Hongchailin site for geothermal power generation in northeastern Taiwan 

Jian-Cheng Lee, Gong-Ruei Ho, Chien-Chih Chen, Hsin-Hua Huang, Cheng-Horng Lin, Sherng-Rong Song, Yi-Chia Lu, Hideaki Hase, Chih-Wen Chiang, Yue-Gau Chen, and Sun-Lin Chung

In this study, we conduct a multi-disciplinary study, including geophysics, geochemistry, and geology, in an attempt to reconstruct geothermal geological model(s) at the shallow 3 km, for a project of potential geothermal power generation at the Hongchailin site in the Ilan plain of northeastern Taiwan. Our geophysical techniques include seismic imaging from natural earthquakes as well as ambient noise. Three seismic arrays deployed at different time periods in the past decade were used. We also incorporate geophysical imaging results from previous studies, in particular a series of seismic reflection profiles. For the magnetotelluric (MT) technique, two major surveys have been conducted, including 2015-2018 AMT by National Central University and 2021-2022 MT by GERD and Academia Sinica.  Three test holes were drilled around the Hongchailin site in 2016-2019. Logging and on-site measurements were conducted at increment depths, including stratigraphy and rock types, P/T measurements, fractures analyses, geochemical analyses (e.g., hydrogen/oxygen/helium isotope, fluid inclusion, etc.), and so on.

        Based on regional geology and structures, and incorporating geophysical subsurface imaging, we reconstruct geothermal geological models in line with detailed geological cross sections at the shallow 3 km level. We interpret that there exits a shallow geothermal reservoir within the massive quartz sandstone layers (Szeleng sandstone) at 1-2 km depth with the downhole temperature of 80-100 C.  Geologically, the reservoir is located at the regional Songlo syncline and its south limb; and geophysically, it corresponds to a relatively low resistivity area. Isotope results show that the cool meteoric water came from nearby higher altitude mountain area, then flew through the Szeleng sandstone, which plunges 1-2 km depth below the Ilan plain. Hot fluid is interpreted to be derived from deeper heat source and to be upflowed along a N-S trending vertical faults system near the Hongchailin area.  In addition, two E-W trending major faults, identified by the seismic reflection profiles, seem to be acted as hydrothermal fluid barriers to confine the hot fluid within the reservoir area.

How to cite: Lee, J.-C., Ho, G.-R., Chen, C.-C., Huang, H.-H., Lin, C.-H., Song, S.-R., Lu, Y.-C., Hase, H., Chiang, C.-W., Chen, Y.-G., and Chung, S.-L.: Combining geophysical, geochemical and geological studies toward plausible geothermal models at the Hongchailin site for geothermal power generation in northeastern Taiwan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2534, https://doi.org/10.5194/egusphere-egu23-2534, 2023.

EGU23-4979 | Orals | ERE2.4

Inferences on the shear wave velocity structure below the Reykjanes peninsula (SW Iceland) from transdimensional ambient-noise surface wave tomography 

Cornelis Weemstra, Amin Rahimi Dalkhani, Þorbjörg Ágústsdóttir, Egil Árni Guðnason, Gylfi Páll Hersir, and Xin Zhang
We report on a Bayesian (i.e., probabilistic) inversion for the shear-wave velocity structure of the Reykjanes peninsula, SW Iceland. Travel times of Rayleigh waves traversing the peninsula served as input to the probabilistic algorithm. These Rayleigh waves were retrieved through the application of seismic interferometry to yearlong recordings of ambient seismic noise. The Reykjanes peninsula is well placed for this technique because it is surrounded by ocean, which implies a relatively uniform seismic noise illumination; the latter being a condition for accurate interferometric surface wave retrieval. The Bayesian algorithm uses a variable model parametrization by employing Voronoi cells in conjunction with a reversible jump Markov chain Monte Carlo sampler. The algorithm is entirely data-driven, meaning that, contrary to conventional deterministic tomographic inversions, the user does not need to define any regularization or parameterization parameters to solve the inverse problem.
 
The geology in the area of interest is characterized by four NE-SW trending volcanic systems, orientated oblique to the divergent plate boundary cutting across the Reykjanes Peninsula. These are from west to east; Reykjanes, Svartsengi, Fagradalsfjall and Krýsuvík, of which all except Fagradalsfjall host a known high-temperature geothermal field. We observe relatively high shear wave velocity patches close to the Earth’s surface (top two kilometers) at the location of these known high-temperature fields. These high velocity anomalies invert to relatively low shear wave velocities (in comparison to shear wave velocities in the same horizontal plane) at depths greater than 3 km. The latter low-velocity anomalies are relatively small below Reykjanes and Svartsengi. At depths of 5 to 8 km, a low-velocity anomaly extends horizontally below Reykjanes and Svartsengi, correlating relatively well with the inferred brittle-ductile transition below the high-temperature fields at 4-5 km depth. The low-velocity anomaly below Krýsuvík is much larger and coincides with a deep-seated low electrical resistivity anomaly. Horizontally, it coincides with the center of an inflation source at 4–5 km depth. For example, in 2010 this resulted in an uplift exceeding 50 mm/year, but several periods of alternating uplift and subsidence associated with increased seismicity have been observed in Krýsuvík since 2009. Our results both confirm and add details to previous models obtained in the area. Our study demonstrates the potential of Bayesian surface wave inversion as a complementary geophysical tool for geothermal exploration.
 

How to cite: Weemstra, C., Rahimi Dalkhani, A., Ágústsdóttir, Þ., Árni Guðnason, E., Páll Hersir, G., and Zhang, X.: Inferences on the shear wave velocity structure below the Reykjanes peninsula (SW Iceland) from transdimensional ambient-noise surface wave tomography, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4979, https://doi.org/10.5194/egusphere-egu23-4979, 2023.

EGU23-6370 | Posters on site | ERE2.4

3-D geometrical modelling of the Dinantian carbonate reservoir in Northern France: new constraints for the regional development of deep geothermy 

Olivier Averbuch, Aurore Laurent, Laurent Beccaletto, Fabien Graveleau, Frédéric Lacquement, Séverine Caritg, Stéphane Marc, and Laure Capar

In the general context of the development of renewable energy in the Hauts-de-France region (N France), some growing interest has been focused recently on the potential of deep geothermy. This area displays favourable conditions due to the burial of a regionally well-defined reservoir, i.e. the Dinantian karstic and brecciated limestones (Lower Carboniferous, 360-330 Ma), below the Nord-Pas-de-Calais coal-bearing Upper Carboniferous basin, developed by flexural subsidence in the foreland of the Northern Variscan frontal thrust system. The predominance of shales within the molassic basin as well as within the basal units at the floor of the thrust wedge (the Lower Devonian clastic units) are furthermore likely to form a large-scale permeability barrier potentially favouring the localization of hot waters within the underlying carbonate reservoir. The occurrence of a Dinantian regional geothermal resource has already been proven in Southern Belgium in the Hainaut coal basin area (the eastern prolongation of the Northern France coal basin) where the temperature in three geothermal wells reaches about 70°C.

To provide further constraints on such potential deep geothermal field in a structurally complex setting (a laterally segmented thrust front), the geometry of the Dinantian reservoir in northern France has been investigated through the integration and interpolation in a 3-D model of a large database including 1 128 boreholes and 532 km of reprocessed, interpreted and depth-converted seismic reflection profiles. The results of the 3-D modelling indicate that the Dinantian reservoir is present at depth over a large area covering approximately 7675 km² in northern France-southern Belgium. It extends at least 30 to 40 km south of the coal mining district area, underneath the Ardennes Allochthonous Unit of the Northern Variscan Front. The Dinantian reservoir is less than 200 m deep in the Lille metropolitan area and strongly deepens southward through a sharp flexure. It reaches 1000-3000 m depth underneath the coal basin and a maximum of 6944 m depth at the southern end of the study area. Overall, the Dinantian reservoir is structured along two main directions oriented N70-80° and N110-130°, related respectively to deep frontal Variscan thrusts and lateral-oblique ramps. The Dinantian reservoir ends west of Douai against a major complex lateral ramp system forming a first-order transfer zone within the Northern France Variscan thrust front. The latter localizes a set of strongly dipping N110-N130 faults (the Artois faults) representing second-order structures produced during subsequent deformation periods i.e. the Late Carboniferous-Permian rifting event and the Tertiary inversion related to the far-field accommodation of the Alpine-Pyrenean shortening.

How to cite: Averbuch, O., Laurent, A., Beccaletto, L., Graveleau, F., Lacquement, F., Caritg, S., Marc, S., and Capar, L.: 3-D geometrical modelling of the Dinantian carbonate reservoir in Northern France: new constraints for the regional development of deep geothermy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6370, https://doi.org/10.5194/egusphere-egu23-6370, 2023.

EGU23-6992 | ECS | Posters on site | ERE2.4

Determining the „geothermal reinjection potential” into sedimentary formations using datasets of hydrocarbon exploration 

Ábel Markó, Marianna Tóth, Maren Brehme, and Judit Mádl-Szőnyi

The so-called Green Transition EU strategy encourages oil businesses to move towards a circular economy and create green energy. The data already collected in the past during hydrocarbon exploration offer enormous possibilities for geothermal reutilization. Revealing this led to the joint project with MOL Plc. to evaluate the geothermal potential for Zala county, Hungary. Although the preliminary geothermal potential of the Zala region (SW Hungary) is assessed to be good, sustainable thermal water use is critical due to the need for reinjection, with only one operating doublet. The study focuses on the geothermal assessment of the siliciclastic Neogene formations.

Due to the need for reinjection wells for sustainable thermal water production, the evaluation has to handle the potential injectivity for the same siliciclastic reservoir. However, several injection-related problems are associated with the Neogene (so-called Pannonian) siliciclastic reservoirs in Hungary. Predicting the issues makes it possible to mitigate them, and it contributes to a “reinjection potential” assessment which can be part of the geothermal potential estimation.

Based on methodological contribution from previous studies (e.g., Markó et al., 2021), this research considers a variety of problem scales, including regional hydraulics, reservoir scale properties, and local clogging processes. As a next step, in the recent study, we investigate the extension of the reservoir sandstone bodies of the deltaic aquifer. This is done by interpreting 3D seismic volumes by amplitude extraction to detect sand-prone volumes combined with well-logs to delineate the reservoir. The analysis helps to predict where to drill the next reinjection well as well as to evaluate the potential of the existing hydrocarbon wells.

The first author was supported, and the research was financed through the KDP-2021 Cooperative Doctoral Programme of the Ministry of Innovation and Technology (Hungary) from the source of the National Research, Development and Innovation Fund, grant number: KDP_2021_ELTE_C1789026. The study was funded by the National Multidisciplinary Laboratory for Climate Change, RRF-2.3.1-21- 2022-00014 project.

How to cite: Markó, Á., Tóth, M., Brehme, M., and Mádl-Szőnyi, J.: Determining the „geothermal reinjection potential” into sedimentary formations using datasets of hydrocarbon exploration, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6992, https://doi.org/10.5194/egusphere-egu23-6992, 2023.

EGU23-7199 | Orals | ERE2.4

3D Structural modeling for geothermal potential evaluation in Southern Apennines 

Chrysanthi Pontikou, Giovanni Toscani, Angelo Ricciato, and Raffaele Di Cuia

Deep geothermal systems as a renewable and green source for energy production and for heating and cooling activities has a great potential for development in many European countries. Also, the need to expand the use of the geothermal resources is well supported by the Foundation for Sustainable Development and meets the goals of the UN 2030 Agenda. Under this perspective, the aim of this research is to study the geothermal energy as an under-exploited tool and how this natural resource could improve and support the ecological transition. The area of interest focuses on the subsurface Cretaceous-Eocene fractured shallow water carbonates (Apulia platform) in the Campania-Lucania sector of the Southern Apennines (Italy), where, based on previous studies, a geothermal positive anomaly has been detected at the level of the reservoir approximately at -3000m (below ground level). The presence of this heat anomaly and in particular the heat transfer mechanism (fluid migration, thermal conductivity, fractures) have not been satisfactorily yet explained from a structural point of view which seems to be one of the key factors for this anomaly. A wide public and confidential database including reflection seismic profiles, well data, gravimetric information and literature from the academia and the Oil and Gas Industry discussing the different structural styles, allowed the re-interpretation and the 3D reconstruction of the geological structures which is subsequently internally characterized by investigating the faults and fractures where hot fluids are present and circulate in the deep subsurface. The structural setting, the physical characteristics of the reservoir rock, the chemical-physical properties of the fluids in the deep subsurface and the dispersion of the heat potential of these fluids as they rise to the surface are all elements that must be considered in the screening phase of potential areas for the development of this geothermal project. We present a comprehensive synthesis of the available data which elaborates the temperature/heat observations derived by the subsurface data and explains sufficiently enough the heat anomaly observed in the area. The geological model is the foundation break of this research and the first fundamental input for the geomechanical characterization of the rock mass by defining the main fracturing trends and the large-scale fractures (discrete fracture network) as the main potential conduits and paths for hot fluid migration and circulation.

How to cite: Pontikou, C., Toscani, G., Ricciato, A., and Di Cuia, R.: 3D Structural modeling for geothermal potential evaluation in Southern Apennines, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7199, https://doi.org/10.5194/egusphere-egu23-7199, 2023.

EGU23-7884 | ECS | Posters on site | ERE2.4

Imaging medium changes during a hydraulic stimulation using the distortion matrix framework:  case of an Enhanced Geothermal System (EGS) in Espoo, Finland. 

Nicolas Compaire, Michel Campillo, Gregor Hillers, Rita Touma, and Alexandre Aubry

In 2018, the company St1 Oy performed an Enhanced Geothermal System (EGS) experiment using near-real-time seismic monitoring as feedback for the pumping procedure and thus allowing the control of the induced seismicity. Between 4 June and 22 July (49 days), ~18,000 cubic meters of water was injected at around 6 km depth beneath the University campus in Otaniemi, Espoo, Finland (Kwiatek el al. 2019). The hydraulic stimulation and post-stimulation stages were monitored by a temporary ~100 three-components geophone network installed by the Institute of Seismology, University of Finland (Hillers et al. 2020). If the requirements for induced seismicity have been successfully met, the medium changes produced by the hydraulic stimulation remain unclear. Especially with regard to the activation or opening of cracks. Recent application of the distortion matrix concept (Badon et al. 2020) in seismology (Touma et al. 2021) allows us to consider resolving some of these questions by imaging the distribution of the scatterers in the medium during the different injection stages. The distortion matrix operator makes it possible to correct a large part of the aberrations present in images obtained by focusing in depth a reflection matrix recorded at the surface. The phase distortions of the seismic wavefield due to complex velocity distributions can be recovered for any virtual source in the medium by comparing the recorded reflection matrix to the ideal geometric wave-front corresponding to this virtual source. By taking advantage of this powerful approach this study present 3D images of the volume surrounding the injection well of the EGS experiment.

How to cite: Compaire, N., Campillo, M., Hillers, G., Touma, R., and Aubry, A.: Imaging medium changes during a hydraulic stimulation using the distortion matrix framework:  case of an Enhanced Geothermal System (EGS) in Espoo, Finland., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7884, https://doi.org/10.5194/egusphere-egu23-7884, 2023.

Forecasting of downhole temperatures is of great interest for the development of deep geothermal energy, since the maximum production temperatures are important for the efficiency of the system. The production temperatures are mainly determined by the prevailing reservoir temperature, which is insufficiently known even in well-developed reservoirs. 

Most available temperature data from hydrothermal reservoirs are “bottom hole temperatures” (BHTs) that are usually measured during geophysical measurement programs, after each section of a deep geothermal well has been drilled. These measured temperatures are thermally disturbed by the preceding drilling fluid circulation and therefore show a high deviation from the undisturbed formation temperature, requiring correction of the BHT measurements. This is made possible by a variety of analytical and numerical BHT correction methods, all of which require different input parameters for each method. Those parameters are often documented with poor quality, incompletely, or not at all. It can be assumed that the inaccuracy of a corrected BHT value depends to a high degree on the errors of the input parameters and the choice of the correction method is secondary in this respect.

In order to perform a complete evaluation of corrected BHT values and to determine the range of errors, we corrected BHT values from over 300 current geothermal and old hydrocarbon wells in the Bavarian Molasse Basin in Southern Germany using a Monte Carlo approach. Thus, the corrected temperature was given as a density distribution rather than a discrete value after individual estimation of the error in the input parameters. This allows a prediction of the formation temperature based on risk scenarios, for example specifying a p10 or p90 case.

From the corrected temperatures and taking into account the individual variances studied (p10 and p90 values); we created a set of temperature gradients that take into consideration, if known, the discovered inflow zones and the slope changes in the stratigraphic layers. This approach provides a spatial representation of temperatures while accounting for error propagation by estimates in the correction process, as well as the extrapolation of point temperature data to gradients and the application of geo-statistical methods.

How to cite: Schölderle, F. and Zosseder, K.: Mapping regional variability of reservoir temperatures for hydrothermal use: a statistical model based on parameter uncertainty, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8110, https://doi.org/10.5194/egusphere-egu23-8110, 2023.

EGU23-8220 | ECS | Posters on site | ERE2.4

Multiparapmeter Seismic Tomography Across High-Temperature Geothermal Field in Hengill (Iceland) Using a Large-N Nodal Array 

Sin-Mei Wu, Pilar Sánchez-Pastor, Thorbjörg Ágústsdóttir, Anne Obermann, Gylfi Hersir, and Aurélien Mordret

The Hengill volcano system and its adjacent geothermal fields are Iceland's most productive harnessed high-temperature geothermal area. The geothermal resources are powered by cooling magmatic intrusions connected to three volcanic systems, with Hengill being the youngest that erupted ~2000 years ago. This area is located at a triple junction and has, therefore, a highly heterogeneous crustal structure in addition to a fissure swarm intersecting the Hengill volcanic center. Although explorations of Hengill began more than half a century ago, outstanding questions remain, such as the geophysical signature of super-critical fluid and a more detailed understanding of the underlying geothermal resources. Our particular focus in this work is to explore how high-resolution 3D isotropic and anisotropic seismic velocity models can help to address relevant questions in Hengill.

We perform ambient noise Rayleigh and Love wave imaging by combining a 498-node dense geophone array and a 44-station seismic backbone network. The backbone netowrk has ~2.5 years of data between late 2018 and 2021, with a >3 km station spacing and up to 40 km aperture. The dense array data, targeting provisioned geothermal subfields in the northern and southern parts of Hengill, was acquired through a 1–2 months campaign in the summer of 2021, with a <500 m station spacing and an aperture of 20 km. We demonstrate that, even with the shorter duration of data, the seismic imaging capacities are greatly enhanced in the top 5 km compared to the images retrieved from the backbone network alone. In addition to the shallow structure (<2 km), the dense sampling with good azimuthal coverage provides essential constraints on the deeper structure (>2 km). We observe a primary slow velocity anomaly at ~4 km depth which we associate with solidified magmatic intrusions. The trend of the anomaly is perpendicular to the NE striking Hengill fissure swarm, coinciding with a previously found deep lying low-resistivity anomaly. We find that most of the earthquake locations are near the margin of velocity contrasts, indicating a structure or permeability change in the subsurface.

From the anisotropy model, we observe a predominant fast direction along the vertical axis in the top 2 km of crust, implying an overall vertical crack formation resulting from extensional stress with ~10 mm/yr westward deformation. From 3 to 5 km depth, the fast direction transitions to the horizontal axis, broadly in agreement with intrusions or lava deposits. Around the same depth, the southwestern Hengill geothermal field remains in the vertically-fast direction. This area resides in the junction of distinct geologic, tectonic, and geodetic manifestations. We hypothesize that the extension of  vertically-oriented formation toward depth relates to crustal thinning and increasing permeability that promote one of the powerful boreholes in Hengill.

 

How to cite: Wu, S.-M., Sánchez-Pastor, P., Ágústsdóttir, T., Obermann, A., Hersir, G., and Mordret, A.: Multiparapmeter Seismic Tomography Across High-Temperature Geothermal Field in Hengill (Iceland) Using a Large-N Nodal Array, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8220, https://doi.org/10.5194/egusphere-egu23-8220, 2023.

EGU23-8583 | ECS | Orals | ERE2.4

Fines migration as a challenge for reservoir-wide chemical stimulation using retarded acid systems 

Jasmin Grifka, Mathias Nehler, Tobias Licha, and Thomas Heinze

Declining permeability of geothermal reservoirs due to fines migration is often considered with regard to existing fines like clay particles that are mobilized. However, fines are also generated due to dissolution and chemical stimulation techniques can induce the generation of fines. For near-wellbore regions, this is uncritical as fines can be extracted after stimulation using cleaning lifts. With the aim of replacing hydraulic stimulations for enhanced geothermal systems by a reservoir-wide chemical stimulation, the penetration depth of the acids needs to be substantially increased. However, cleaning lifts to remove fines are no longer possible in greater distance from the wellbore, so alternative strategies are required.

Flow-through experiments with citric acid on dolostone were used to investigate the dependence of fines generation on the reaction conditions. For all dissolution regimes over a range of different Damköhler numbers, fines were generated and could greatly reduce the permeability of the rock samples. Only when large pathways were created by the dissolution process, the generated fines were transported out of the major pathways as well as dissolved therein, thus not interfering with the increase of permeability due to dissolution. The results highlight the great challenges for reservoir-wide chemical stimulations techniques using retarded acid systems, but also indicate possible solutions.

How to cite: Grifka, J., Nehler, M., Licha, T., and Heinze, T.: Fines migration as a challenge for reservoir-wide chemical stimulation using retarded acid systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8583, https://doi.org/10.5194/egusphere-egu23-8583, 2023.

EGU23-8945 | Posters virtual | ERE2.4

GIS-based analysis for regional exploration in the geothermal province of intraplate volcanism in the Center of Mexico 

Ernesto Macedo Serrano and Rosa María Prol Ledesma

The regional evaluation of the intraplate volcanism province is attempted using the Play Fairway Analysis. This province is characterized by recent alkaline volcanism that is not related with the previous Farallon Plate subduction of the present Cocos Plate subduction. This volcanism is constrained to the main structures related with the Basin and Range processes of extensional tectonism.

A geographic information system is constructed by including geological and geophysical data. Thematic maps are developed with the information that is considered relevant for the location of areas with favorable conditions to host geothermal systems, with or without surface manifestations, i.e. including the blind geothermal systems. This work includes information of the occurrence of recent volcanism (age less than 2 Ma), geological structures, seismic activity, shallow Curie Point Depth, surface heat flow, crustal thickness, hydrothermal manifestations (hydrothermal alteration, thermal fluids discharge, etc.). Data integration is performed using a “Knowledge driven” model with three different geothermal play models producing play fairway evaluations. The presence of several areas with high favorability was identified to lead future detailed exploration in the field.

How to cite: Macedo Serrano, E. and Prol Ledesma, R. M.: GIS-based analysis for regional exploration in the geothermal province of intraplate volcanism in the Center of Mexico, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8945, https://doi.org/10.5194/egusphere-egu23-8945, 2023.

EGU23-9144 | ECS | Posters on site | ERE2.4

The shallow subsurface characterization in relation to geothermal resources in the Mallow area, Ireland, using passive seismic and gravity data inversion 

Meysam Rezaeifar, Christopher J. Bean, Duygu Kiyan, Brian O’Reilly, Colin Hogg, Patrick Meere, Javier Fullea, Sergei Lebedev, Tao Ye, Emma L. Chambers, Aisling Scully, and Gaurav Tomar and the DIG team

One key aim of the DIG (De-risking Ireland’s Geothermal Energy Potential) project is to determine and evaluate the potential low-enthalpy geothermal resources at reservoir scale in the Mallow warm springs area (MWSA), by performing a joint interpretation of new and existing geophysical, geochemical and petrophysical datasets together with structural geology and hydrochemistry results.

As a first step, based on the ambient detected noise sources in the study area, about 100 seismic stations (5Hz nodes) were deployed for two weeks along the railway, straddling fault structures that are thought to control hot spring fluid flow in the Mallow area. We performed seismic interferometry imaging on the recorded train-induced vibrations to map shallow subsurface (top ~2 km) structures and to extract the physical properties (e.g. seismic velocity and density) of these structures. Preliminary result shows a good correlation between S-wave velocity variation and the near-surface lateral changes of lithology, especially across the Killarney-Mallow Fault Zone (KMFZ).

In the next step, 2D interactive modeling of the gravity data was performed, using physical properties determined from the previous step to constrain shallow structures. Additionally, we used the result from the receiver function method that is applied to the data recorded by four broadband stations in the study area, in order to better constrain the deeper interfaces. The 2D inversion of gravity data reveals an anomalous zone in the vicinity of the KMFZ that could be related to the possible fault conduit, associated with the Mallow warm springs area.

The project is funded by the Sustainable Energy Authority of Ireland under the SEAI Research, Development & Demonstration Funding Programme 2019 (grant number 19/RDD/522) and by the Geological Survey Ireland.

How to cite: Rezaeifar, M., Bean, C. J., Kiyan, D., O’Reilly, B., Hogg, C., Meere, P., Fullea, J., Lebedev, S., Ye, T., Chambers, E. L., Scully, A., and Tomar, G. and the DIG team: The shallow subsurface characterization in relation to geothermal resources in the Mallow area, Ireland, using passive seismic and gravity data inversion, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9144, https://doi.org/10.5194/egusphere-egu23-9144, 2023.

EGU23-9422 | Orals | ERE2.4

Multiple target horizon exploration for the implementation of an integrated geothermal system for Göttingen, Germany 

Bernd Leiss, David C. P. Peacock, Ali Abdelkhalek, and Dmitry Romanov

To boost the contribution of geothermal energy to Europe’s energy transition, exploration and exploitation must extend to new regions and play types. The MEET (Multidisciplinary and multi-context demonstration of EGS exploration and Exploitation Techniques and potentials) project included analysis of the potential for an Enhanced Geothermal System (EGS) in the metasedimentary rocks of the Variscan Fold and Thrust Belt in the subsurface at the University of Göttingen, Germany. A feasibility study related to the integration of EGS into the existing district heating system of the Göttingen University campus, which currently uses a natural gas-based combined heat and power plant, presents several scenarios with minimum requirements for cost-effectiveness of the EGS, e.g. a brine flow rate of 30 l/s and brine temperature of 130°C. Mohr diagrams are used to predict the responses of the rocks to thermal and hydraulic stimulation, using information from geological analogue studies in the nearby Harz Mountains, and petrophysical data measured in the laboratory.

We focus on targeting multiple geological horizons to reduce the exploration risk and to optimize the geothermal energy system, including the development of deep, medium deep and shallow geothermal systems for heating, cooling, and heat storage. A concept based on these geothermal systems together with other renewable energies and energy-efficiency measures is proposed. The geology at Göttingen is suitable for such an integrated geothermal system. It includes Variscan basement rocks below ~1500 m, Zechstein layers with salt, gypsum and carbonate layers (up to 500 m thick), and Mesozoic sandstones and possibly karstified carbonates. Unconsolidated Pleistocene sediments are suitable for shallow geothermal systems. The multiple target horizons approach can be more appealing for funding because of the possibilities of higher output and greater efficiency. It will also decrease the exploration risk because fall-back options are available. Involvement and engagement of different stakeholders is a potential barrier to such an integrated approach.

MEET received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement № 792037

How to cite: Leiss, B., Peacock, D. C. P., Abdelkhalek, A., and Romanov, D.: Multiple target horizon exploration for the implementation of an integrated geothermal system for Göttingen, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9422, https://doi.org/10.5194/egusphere-egu23-9422, 2023.

EGU23-9522 | ECS | Orals | ERE2.4

Characterization of the geothermal anomaly associated with the pre-andean reverse fault of Calientes, South of Peru: a multi-disciplinary approach. 

Audrey Taillefer, Laurent Truche, Laurence Audin, Simona Denti, Frederic Donze, Delphine Tisserand, Nathaniel Findling, Laurent Guillou-Frottier, Pablo Jorge Masías Alvarez, Nelida Manrique Lllerena, and Swann Zerathe

In Peru, energy production is more than 75 % dominated by hydrocarbons (IEA, 2018) while at the same time, the Andes forearc is in a full demographic and economic development. However, the geothermal potential associated with reverse fault in the mountain range forearcs remains poorly studied compared to normal faults.  It is then essential to evaluate the geothermal potential associated with the Andes forearc thrust faults, in considering the environmental risks associated.

The hydrothermal system associated with the Sama-Calientes fault, near the city of Tacna South of Peru (18°S) is a suitable field site to experiment how integrated studies could provide an exploration diagnostic. The Calientes hot springs (42-44°C) emerge on the Sama-Calientes fault, an active thrust which delimits the border between the Andes and the north extension of the Atacama Desert. With an integrated study of the hydrothermal fluids and gas geochemistry, XRD composition of the hydrothermal deposits and veins, structural geology, and 3D numerical modeling with COMSOL Multiphysics, we propose to characterize the thermal anomaly associated with the Calientes springs and faults, putting them in perspective with the other hydrothermal springs in the region. Preliminary results indicated that hydraulic breccia, veins, and concretions around the Calientes springs and faults are mainly composed of calcite, contrarily to the other hot springs sites inside the Andes (excepted the Ticaco hot springs). Free and dissolved gas of the springs associated with the high Andean volcanoes (Casiri, Yucamani, Tacora) are mainly composed of CO2 (90-100%), while those associated with the pre-andean faults (Sama-Calientes, Incapuquio) are mainly composed of N2 (60-100%). Volcanic-associated springs show high sulfate concentrations (48-54 mmol/L) compared to fault-associated springs (3-25 mmol/L).  A simple 3D numerical model with a surface DEM and a homogenous permeability indicates that the topography-driven flow lines contributing to the Calientes springs would come from the Tacora volcano, 40 km north-east of Calientes. More investigation will precise the organization of the hydrothermal cells and the associated thermal anomalies. This work will also contribute to understand the role of hydrothermal fluids in subduction zones and especially on seismogenic reverse fault dynamics.

How to cite: Taillefer, A., Truche, L., Audin, L., Denti, S., Donze, F., Tisserand, D., Findling, N., Guillou-Frottier, L., Masías Alvarez, P. J., Manrique Lllerena, N., and Zerathe, S.: Characterization of the geothermal anomaly associated with the pre-andean reverse fault of Calientes, South of Peru: a multi-disciplinary approach., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9522, https://doi.org/10.5194/egusphere-egu23-9522, 2023.

EGU23-10151 | ECS | Orals | ERE2.4

Soil and soil-gas surveys for geothermal exploration at Cumbre Vieja volcano, La Palma, Canary Islands 

Alba Martín-Lorenzo, Nemesio M. Pérez, Gladys V. Melián, Fátima Rodríguez, Cecilia Amonte, María Asensio-Ramos, Pedro A. Hernández, and Eleazar Padrón

The most common types of survey in known geothermal areas are water and gas sampling of natural discharges. However, where wáter and gas discharge features are few and where the extent of the field is not known, soil and soil-gas surveys can prove useful. These surveys can identify areas in a field that are permeable and potential upflow or boiling zones. They can also outline the boundaries of a geothermal system, often in conjunction with geophysical surveys to provide more comprehensive understanding, especially when geophysical data is difficult to interpret. For all of the above, a soil and soil-gas survey for geothermal exploration had been carried out at Cumbre Vieja volcano that is characterized by neither having visible manifestations of volcanic gases nor zones of hydrothermal alteration on its surface. We have divided the soil and soil-gas survey for geotermal exploration into four categories based on the number of sampling sites per square kilometer: 1) Regional exploration survey (1 sampling site/km2), 2) Regular exploration survey (about 5 sample sites/km2), 3) Detailed I exploration survey (between 10 and 100 sampling sites/km2) and 4) Detailed II exploration survey (more than 500 sampling sites/km2). We have classified our soil and soil-gas survey for geothermal exploration at Cumbre Vieja volcano as a regular exploration survey due to the fact that 1200 observation or measurement points were selected for its 220 km2 area, resulting in approximately 5.5 sampling sites per km2. Similar soil gas surveys had been performed in other study áreas of the Canarian archipelago (Rodríguez et al. 2021). At every sampling site, we performed in-situ measurements of soil CO2 efflux and 222Rn activity in the soil gas atmosphere. In addition, soil gas samples were collected at a depth of 40 cm for further chemical and isotopic analysis in our geochem lab. Simultaneously with the soil gas survey, soil samples were collected from the base of the B Horizon-Subsoil (30–50 cm) which were subsequently dried and sieved (80 mesh) for subsequent leaching in order to analyze those volátiles (Hg0, As, B and NH3) of interest that were fixed in the organic-clay fraction of the soils. Some preliminary results of this soil and soil-gas survey for geothermal exploration at Cumbre Vieja are presented.

Rodríguez F., Pérez N. M., Melián G. V., Padrón E., Hernández P. A., Asensio-Ramos M., Padilla G. D., Barrancos J. and D’Auria L. (2021). Exploration of deep-seated geothermal reservoirs in the Canary Islands by means of soil CO2 degassing surveys. Renewable Energy, https://doi.org/10.1016/j.renene.2020.09.065

How to cite: Martín-Lorenzo, A., Pérez, N. M., Melián, G. V., Rodríguez, F., Amonte, C., Asensio-Ramos, M., Hernández, P. A., and Padrón, E.: Soil and soil-gas surveys for geothermal exploration at Cumbre Vieja volcano, La Palma, Canary Islands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10151, https://doi.org/10.5194/egusphere-egu23-10151, 2023.

EGU23-10434 | Posters virtual | ERE2.4

Socio-environmental exploration and evaluation of social impacts for direct geothermal uses in Los Baños, Veracruz, Mexico. 

Paola Anahi Olmedo Velazquez, Mariana Patricia Jácome Paz, Ana Laura Silva López, and Rosa María Prol Ledesma

During the geothermal prospecting and exploration stages, different interests may arise that motivate a socio-environmental conflict over the use of the resource. To prevent this, it is important to have a social management plan and consider cultural values within the exploration stages. The objective of this project is to evaluate the social impacts of the implementation of direct use in the Los Baños geothermal zone, in the intraplate volcanism province of eastern Mexico; as well as to identify the main actors of the territory and their perception of the geothermal resource. To do this, semi-structured field surveys were implemented, and the evaluation format required for larger energy projects (in Mexico) was adapted to identify local aspects of the social dimension.

The main results are identification of actors with greater cultural weight and influence in local decision-making, identification of the existence of a socio-environmental conflict linked to mining in the area, identification of the type of direct geothermal use that can be implemented with greater feasibility (social and technical) in the area, a constant dialogue with the managers of the territory and the joint approach of later stages for the social acceptance of the project.

Acknowledgement

Project PAPIIT-UNAM IA100921 Exploración geotérmica en el Oriente de la Faja Volcánica Transmexicana.

Project PAPIIT-UNAM   IA102123 Exploración avanzada en Los Baños, Veracruz para usos directos de la energía geotérmica.

How to cite: Olmedo Velazquez, P. A., Jácome Paz, M. P., Silva López, A. L., and Prol Ledesma, R. M.: Socio-environmental exploration and evaluation of social impacts for direct geothermal uses in Los Baños, Veracruz, Mexico., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10434, https://doi.org/10.5194/egusphere-egu23-10434, 2023.

The Qinghai-Tibet Plateau, located in the world-famous Mediterranean-Himalayan tropics, is the most intensely tectonically active region of the Cenozoic in mainland China. Accompanied with a large amount of hydrothermal activity and energy generation, this region had the greatest potential and concentration of high-temperature geothermal resources in mainland China. The Gudui geothermal field, located in the central Cone-oiga rift, is a shallow buried high-temperature geothermal field with the greatest power generation potential. In order to analyze the types and distribution characteristics of sinter and hydrothermal alteration, the favorable exploration direction and heat-controlling structure of Gudui geothermal field, the geothermal geological investigation, microscopic identification, and scanning electron microscope analysis were carried out. The hydrothermal alteration types, such as chloritization, silicification, kaolinization and carbonation, and sinters such as travertine, geyserite and sulphur, were identified. Three groups of faults were developed in the Gudui geothermal field with respect to the heat-controlling structure. The early EW faults are mostly reverse faults, and the later NE or NW secondary faults are mostly extensional faults as the main channels of geothermal fluid.The distribution of hydrothermal alteration is controlled by normal fault, of which alteration center is mainly located at the junctions of faults, and extends along the faults. An obvious hydrothermal alteration zonation was existed in the Gudui geothermal field, which extends from acidic alteration to weak acidic-neutral alteration, and the alteration center is mainly composed of extensively altered silicification or kaolinization zones. The distribution and intensity of hydrothermal alteration implies that the Bushonglanggu and Shagalanga geothermal display area have enormous resource potential. Therefore, geothermal exploration in Gudui geothermal field should focus on the Bushonglanggu and Shagalanga geothermal display area. with respect to hydrothermal deposition, the west area of Gudui geothermal field is dominated by travertine, and the east area is characterized by the coexistence of travertine and siliceous sinter. Furthermore, combined with the dynamic background of Qinghai-Tibet Plateau, an obvious coupling relationship exists between hydrothermal history and the uplift of Qinghai-Tibet Plateau during continent-continent collision and the activity of the Cone-oiga rift.

How to cite: Cao, R., Dor, J., and Meng, H.: Hydrothermal activity characteristics, types of hydrothermal alteration and exploration direction in Gudui high temperature geothermal field, Tibet, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10646, https://doi.org/10.5194/egusphere-egu23-10646, 2023.

EGU23-11067 | ECS | Orals | ERE2.4

Uncertainty quantification with a physics-based machine learning method for geothermal-well targeting: A case study of The Hague, Netherlands 

Ryan Kurniawan Santoso, Denise Degen, Dominique Knapp, Renate Pechnig, and Florian Wellmann

Drilling of production and injection wells for geothermal exploitation requires accurate knowledge of subsurface structures and processes related to fluid flow and heat transport, reactive transport, and mechanical processes. Since the number of exploration wells is limited, proper characterization of subsurface properties and structures is challenging. Therefore, quantifying uncertainties is essential for estimating the risk in selecting the location of suitable production and injection wells to increase the chance of profitable outcomes.

Uncertainty quantification is often conducted within a probabilistic framework which demands numerous forward model runs. It poses a computational challenge for geothermal applications since many geothermal subsurface models are high-dimensional due to covering a wide range of parameters and utilizing fine meshes to capture complex structures and address coupled processes. In this study, we introduce the use of the non-intrusive reduced-basis method (NI-RB), a physics-based machine learning method, to enable uncertainty quantification also for high-dimensional models. The NI-RB is a model-order reduction (MOR) technique that expresses a physical solution in a linear combination of basis functions and weights. The NI-RB preserves the structure of the physics in the basis functions and uses a machine-learning model to calculate the weight for each basis function. With this method, we can guarantee physical consistency with respect to a full Finite Element simulation in the prediction phase and gain significant speed-ups to enable probabilistic uncertainty quantification analyses.

As a test of feasibility, we use the model of The Hague case (in the Netherlands) to illustrate an uncertainty quantification with a physics-based machine learning method. With the use of this approach, we gain a significant computational speed-up for predicting a new temperature state, from 10 minutes in High-Performance Computing (HPC) infrastructures with 48 cores to 1 millisecond on a conventional laptop with a single core. It, therefore, enables performing a robust uncertainty quantification on such a high-dimensional model in only 30 minutes with 3 million realizations. The trade-off is on time required for preparing training samples for training the machine learning model. The selected training samples must be representative for the desired parameter ranges. We can, then, characterize the temperature distribution at any location with its uncertainty level. This information is valuable for a careful selection of the location of suitable production and injection wells and estimate the possible economic loss.    

How to cite: Santoso, R. K., Degen, D., Knapp, D., Pechnig, R., and Wellmann, F.: Uncertainty quantification with a physics-based machine learning method for geothermal-well targeting: A case study of The Hague, Netherlands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11067, https://doi.org/10.5194/egusphere-egu23-11067, 2023.

EGU23-11331 | ECS | Orals | ERE2.4

Insights on structural deformation within the Münsterland, Germany, from legacy and newly acquired 2D seismic data for the development of conventional geothermal systems 

Nicklas Ackermann, Alexander Jüstel, Michael Kettermann, Oliver Ritzmann, Gregor Bussmann, Carsten Lehmann, and Florian Wellmann

The Münsterland Cretaceous Basin with its underlying coal-bearing Paleozoic strata has become one of the prolific areas in North-Rhine Westphalia, Germany, to develop conventional geothermal systems. The presence and structural deformation of four potential calcareous and siliciclastic geothermal reservoirs within the basin (Upper Cretaceous carbonates) and the basement (Lower Carboniferous carbonates, Upper Devonian sandstones, Upper/Middle Devonian carbonates) are only known from sparsely distributed boreholes and crustal seismic data (DEKORP). We aim at reducing the geological uncertainties by interpreting and analyzing legacy data of the DEKORP project, and recently acquired 2D seismic data from the central Münsterland. In addition, information from former research and hydrocarbon wells, now intersecting the newly acquired surveys, were integrated to guide and verify the interpretation. Our investigations contribute to the already existing knowledge of the Variscan folding and spatial distribution of the potential geothermal reservoirs within and below the Münsterland Cretaceous Basin. Further, we show previously undescribed local inversion structures in the Cretaceous section caused likely by the reactivation of post-Variscan transtensional faults in the center of the basin. The seismic data exhibits anomalies which will be analyzed if they are indicating areas of increased porosities through structural deformation or the presence of migrated hydrocarbons in these regions. The latter would imply a structural connection between coal-bearing Carboniferous strata and porous reservoirs in the Upper Cretaceous via deep-reaching reactivated faults. The presence of fault zones that have evidently been vertically permeable on a geological time scale demonstrate possible fluid pathways for conventional geothermal systems. Such geothermal systems could be future targets for drilling to produce local renewable district heating for the city of Munster.  Therefore, further investigations such as in-situ tests through drillings are required to quantify the current permeability of these damage zones.

How to cite: Ackermann, N., Jüstel, A., Kettermann, M., Ritzmann, O., Bussmann, G., Lehmann, C., and Wellmann, F.: Insights on structural deformation within the Münsterland, Germany, from legacy and newly acquired 2D seismic data for the development of conventional geothermal systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11331, https://doi.org/10.5194/egusphere-egu23-11331, 2023.

EGU23-11457 | ECS | Orals | ERE2.4

Structural setting for a geothermal system at the eastern boundary of the Roer Valley Rift System – A case study from the Viersen Fault Zone in the vicinity of Straelen, Germany 

Alexander Jüstel, Philipp Rubach, Andrea Balza Morales, Michael Kettermann, Oliver Ritzmann, and Florian Wellmann

Geothermal systems have been developed in Paleozoic rocks within the Roer Valley Rift System (RVRS) on the Campine Block in Belgium in the West (e.g. Mol) and the Peel Block in the Netherlands in the East (Tegelen Fault, Californië project). However, no geothermal system has been developed further along the eastern boundary of the RVRS where the tectonically active Viersen Fault Zone (VFZ) is located. This fault zone separates the elevated Krefeld Block from the Venlo Block located near Straelen, Germany. Given the high demand for heat by local greenhouses, the city of Straelen and its surroundings would greatly benefit from geothermal developments. In this study, we aim at characterizing the subsurface structures of the VFZ to estimate the geothermal potential of the Dinantian carbonates, Upper Devonian Condroz sandstones and deeper targets like the Upper/Middle Devonian limestones. This is done by reinterpreting seismic data acquired within the framework of the Californië project, analyzing recently acquired data within the framework of the SCAN project and new gravity measurements performed in the Straelen area. The seismic interpretation indicates fault linkages and relay structures which can be correlated to surface expressions and the recorded gravity measurements. The potential geothermal reservoirs were mapped and horizons were interpolated between the seismic lines with insights provided from gravity results. Our investigations illustrate the previously undescribed segmentation of the Viersen Fault Zone in the Straelen area. This tectonic deformation may promote or enhance fluid flow within the reservoirs in the vicinity of the VFZ similar to the geothermal system developed along the Tegelen Fault in the Netherlands. However, the current permeability of these damage zones in VFZ within the reservoirs requires further local subsurface investigations and in-situ tests through drillings to characterize the hydraulic properties and to map the reservoirs and associated structures in 3D. 

How to cite: Jüstel, A., Rubach, P., Balza Morales, A., Kettermann, M., Ritzmann, O., and Wellmann, F.: Structural setting for a geothermal system at the eastern boundary of the Roer Valley Rift System – A case study from the Viersen Fault Zone in the vicinity of Straelen, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11457, https://doi.org/10.5194/egusphere-egu23-11457, 2023.

Sustainable and efficient use of the geothermal resource sitting below the city of Munich (Germany) is a topical issue for the local energy providers. Indeed, by 2035, Munich city expects to supply 100 % of its electricity and heat demand from renewable energies. Hence, the exploitation of the highly conductive aquifers will be intensified with the development of numerous new geothermal power plants. This is a challenging task, which requires better understanding of the coupled processes taking place underground and of their effects, especially in terms of possible induced seismicity and ground uplift or subsidence. These last two concerns are at the heart of the INSIDE research project. The present study focuses on the thermo-hydro-mechanical (THM) modelling of the deep geothermal site in Pullach im Isartal (close to Munich), which constitutes one step to reach the overall project goal.

At the Pullach site, since 2005, a deep geothermal reservoir in the Mesozoic Malm is successfully operated and supplies heat to the local grid. A finite-element (FE) reservoir model is developed consisting of eight different lithologies ranging from the crystalline basement to the Earth’s surface. Focusing on the Malm geothermal reservoir, the lithology of interest is subdivided into the three potential and permeable reservoir rocks of the lower, middle and upper Malm. The three geothermal wells are included with their real trajectories and open-hole sections as lower-dimensional elements. The FE model is used to simulate the fully-coupled THM processes taking place under continuous operation using the TIGER open-source application, which is based on the Multiphysics Object-Oriented Simulation Environment (MOOSE).

The 3D numerical model was calibrated using hydraulic tests conducted at the wells and the continuous operation of the plant, running for many years, gave the opportunity to assess the simulation results. Consequently, predictions of the long-term changes of the THM characteristics of the geothermal reservoir for the next 50 years are expected realistic. The results show that, under our assumptions and the current operational conditions, exploitation will remain sustainable in the future. Furthermore, near the injection well, a long-term increase in porosity and permeability should be expected due to thermo-poroelastic effects. At last, millimetre-scale uplift could be observed at surface above the injection well.

In addition to the present exploitation schemes, several scenarios to increase the exploitation using additional wells are investigated. A similar approach is taken, but particular attention is paid to possible interferences between existing and future neighbouring wells due to enhanced reservoir utilization.

How to cite: Gaucher, E. and Egert, R.: Change of the THM properties of a Malm geothermal reservoir under present and future exploitation schemes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11877, https://doi.org/10.5194/egusphere-egu23-11877, 2023.

EGU23-12208 | ECS | Orals | ERE2.4

Review of existing data for the evaluation and estimation of the geothermal potential in the basement of western Spain. 

María A. Berriolopez Llamosas, Antonio Olaiz, Alfonso Muñoz Martín, and Gonzalo Zamora

The last few years have been characterized by tremendous global instability due to assure energy supply. Global growth demands more and more resources at the same time as the population´s concern about climate change is increasing. In this context, geothermal energy, a green and renewable energy with the capacity to contribute to the transition of the energy market, is becoming increasingly important. This, together with the improvement in geothermal studies and the development of new exploitation methods, has triggered new geothermal targets to be considered during the last decades.


Geothermal studies in Spain were focused on sedimentary basins and volcanic settings during the 70´s and 80´s. In this framework, few investigations have been done on the western igneous massif of Spain. This study seeks to estimate and resume research on the geothermal potential of the Spanish basement. With that purpose this research analyzes high resolution airborne radiogenic data from Extremadura, Castilla La Mancha and Madrid (Geodata International Inc., 1980), acquired in the 70 and 80´s for uranium exploration, concentration measurements of Uranium, Thorium and Potassium from soil samples (Locutura et al. 2012) and temperature data from widespread hot springs along the studied area.


We have analyzed the concentration of the three heat producing elements in 9 plutons and estimated the heat production of each of them. In this regard, the high airborne-constrained concentrations of the plutons located in the north of Extremadura and west of Salamanca are noteworthy. In this area Uranium reaches 16.43 ppm, Thorium 14.52 ppm and Potassium 6.26 %. Same way a remarkable peak in heat production is located is this area with values up to 5.02 μW/m3. When comparing these data with the values obtained from the soil samples, the correlation between the two is remarkable. Furthermore, the positive radiometric anomalies of both maps coincide with the outcropping of granitic rocks and the location of most of the hot springs.


This work compiles vintage information of diverse origin in order to highlight areas with high geothermal potential in the basement of the westernmost Spain. The results of heat production and their relationship with the hot springs have shown that several of the Paleozoic plutons of the western igneous massif of Spain may have a great potential for geothermal projects.

How to cite: Berriolopez Llamosas, M. A., Olaiz, A., Muñoz Martín, A., and Zamora, G.: Review of existing data for the evaluation and estimation of the geothermal potential in the basement of western Spain., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12208, https://doi.org/10.5194/egusphere-egu23-12208, 2023.

EGU23-12224 | Orals | ERE2.4

Fault characterization using seismic and DAS recordings at the Hengill geothermal area, Iceland 

Bettina P. Goertz-Allmann, Nadège Langet, Alan Baird, Daniela Kühn, and Tina Kaschwich

The Hengill geothermal area is located in southwest Iceland on the plate boundary between the North American and Eurasian plates and is one of the most active seismic zones on the island with thousands of natural earthquakes per year. In addition, seismicity is induced due to active production and injection operations, including the two largest geothermal power plants in Iceland, Nesjavellir and Hellisheiði. In addition, this area is the next target region for the Iceland Deep Drilling Project (IDDP) in search for supercritical geothermal fluids. Detecting and imaging fault zones at high resolution is therefore an important contribution to evaluate the optimum drilling location. We analyze thousands of microseismic events in the area that occurred between December 2018 and August 2021. These events were recorded on different permanent and temporary seismometer networks in the area. In addition, we recorded distributed acoustic sensing (DAS) data along a 25 km long fiber optic telecommunication cable near the Nesjavellir geothermal power plant. We analyze event clustering with a waveform cross-correlation approach and find a clear spatial separation of event clusters delineating planar structures. Clusters experience different temporal evolutions where some develop steadily and others as sudden bursts. Spatial variations of Gutenberg’s b-value and event stress drops show patterns consistent with tomographic seismic velocity inversions. Furthermore, focal mechanisms indicate very consistent source mechanisms within selected event clusters. Along the fiber path, we study waveform characteristics, which correlate with mapped geological features.  Data segments that are recorded where the fiber crosses fault zones exhibit long-tailed codas that may indicate trapping of seismic energy in low-velocity zones around active faults.

How to cite: Goertz-Allmann, B. P., Langet, N., Baird, A., Kühn, D., and Kaschwich, T.: Fault characterization using seismic and DAS recordings at the Hengill geothermal area, Iceland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12224, https://doi.org/10.5194/egusphere-egu23-12224, 2023.

EGU23-12308 * | Orals | ERE2.4 | Highlight

Geothermal Energy in Switzerland: roadmap to 2050 

Matteo Lupi

For decades, geothermal energy was harnessed from magmatic systems only. This is no longer the case since projects began to exploit the energetic potential of a variety of geological domains across different tectonic settings. Vertical ground heat exchangers, groundwater aquifers and enhanced geothermal systems are only a few of a large spectrum of solutions proposed to harvest geothermal energy practically anywhere.
Despite lacking high-enthalpy geothermal resources, Switzerland is today one of the leading countries for research and development in the geothermal sector. New projects have been launched, underground laboratories have been developed and a wealth of research opportunities are rising. The new challenges to be faced are supported by solid research schemes fostering interaction between research and industrial partners. I will provide a brief overview of Switzerland’s geothermal roadmap to 2050 describing how the Helvetic confederation is planning to attend about 2 TWh of energy (and about 18 TWh if heat is also considered) by 2050. I will highlight the collaborative research opportunities and the future challenges that our community will have to undertake to foster geothermal energy as a solid and reliable resource to fuel our society across the energetic transition.

How to cite: Lupi, M.: Geothermal Energy in Switzerland: roadmap to 2050, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12308, https://doi.org/10.5194/egusphere-egu23-12308, 2023.

EGU23-12480 | ECS | Posters on site | ERE2.4

Modelling Impacts of Groundwater Flow on Borehole Heat Exchangers: Lessons Learned from Estonia 

Kaiu Piipponen, Alvar Soesoo, Heikki Bauert, and Teppo Arola

Production of geothermal energy relies heavily on subsurface properties. In low-enthalpy geothermal regimes, thermal energy extracted with a borehole heat exchanger (BHE) is the subsurface heat conducted from the rock and grout to the BHE fluid. No subsurface fluids are pumped in or out of the BHE system in the process. However, groundwater flow can bring warm or cold fluid from the surroundings which changes the temperature profile in the well and the vicinity and thus it can affect well heat production.

The geology in Estonia provides a good opportunity to study the groundwater influence on the BHE systems. In Estonia, several hundred meters thick Lower Palaeozoic sedimentary rock sequence is mostly covered by relatively thin Quaternary sediments, while the underlying Lower Proterozoic crystalline basement rocks occur at depths from 150 m in North Estonia to over 600 m in South Estonia. The main groundwater aquifers are confined to the Palaeozoic sedimentary rocks. In North Estonia, the main groundwater aquifers overlying the crystalline basement rocks are Gdov, Voronka, Cambrian-Vendian, Ordovician-Cambrian, and Silurian-Ordovician aquifers. Those aquifers have different thermogeological and hydrogeological parameters shown by several groundwater hydrogeological and hydrodynamic studies and modelling. Only a few geothermal energy studies have been conducted in the Estonian geological setting and the groundwater effects on the geothermal energy budget on the shallow to medium depth geothermal energy systems have not yet been studied in detail.

In this study, we parametrized different hydraulic conditions to compare how the groundwater flow velocity impacts the thermal energy yield of the geothermal system. We modelled single BHEs of lengths of 400 m, 500 m and 1000 m and a BHE field of ten 400 m wells at three sites across Estonia. 400 m wells have a U-tube type heat collector grouted with bentonite clay and the 500 m and 1000 m wells have a coaxial heat exchanger of plastic pipe or a vacuum-insulated tube (VIT), respectively. Our results demonstrate that 1) the thermogeological parameters of the area, such as subsurface temperature and thermal conductivity, are the most significant factor in the thermal energy yield of the wells and 2) at all sites, shallow BHEs are sensitive to the added groundwater flow, whereas 1-kilometer-deep coaxial wells with VIT are the least sensitive to the addition. An interesting highlight is that the increase in the thermal energy yield is not consistent at different locations with the groundwater flow variation. At sites where the aquifers are located deep with respect to the borehole length, an increase in groundwater flow velocity brought more advantages than at sites where permeable layers are distributed more evenly or near the top of the geothermal well.

How to cite: Piipponen, K., Soesoo, A., Bauert, H., and Arola, T.: Modelling Impacts of Groundwater Flow on Borehole Heat Exchangers: Lessons Learned from Estonia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12480, https://doi.org/10.5194/egusphere-egu23-12480, 2023.

EGU23-12749 | ECS | Orals | ERE2.4

Numerical simulation of fault zone permeability enhancement by chemical stimulation operation at the Eden geothermal projects, UK 

Mrityunjay Singh, Claire Bossennec, Kristian Bär, John Reinecker, Robbie Bilsland, Chris Briggs, Lucy Cotton, Jon Gutmanis, Tony Bennet, Jörg Baumgärtner, Augusta Grand, Nils Recalde Lummer, Omair Rauf, Clément Baujard, Albert Genter, and Ingo Sass

To increase fluid flow and thus obtain higher heat production from a geothermal well, chemical stimulation can be performed in their open-hole sections. Through chemical stimulation, fracture zone permeability in the vicinity of the borehole can be enhanced which results in higher fluid connectivity from the well to the reservoir fracture network. To understand the chemical stimulation effect on fault zone permeability enhancement and pressure development, the Eden geothermal project acted as a demonstration site in the framework of the MEET project. The open-hole section of the Eden geothermal project was characterized based on drill cutting analysis, several borehole geophysical logs including (Spectral Gamma Ray, Caliper, Borehole Image, etc.) as well as hydraulic testing. These hydraulic injection tests were carried out from January to March 2022 in the form of several low injection tests, where fluid was injected in a series of flow rates ranging from 5 – 15 l/s. Furthermore, a chemical stimulation test was performed in August-September 2022 followed by another series of hydraulic injection and production tests until late November 2022 at flow rates of 5 – 12.5 l/s. Rock cuttings from the target zone (3940 m TVD) indicated up to 3% of calcite which is easily dissolvable by acids. Therefore, the chemical stimulation was primarily aimed to treat possible near-wellbore damage resulting from an LCM cementation carried out during the drilling of the well in 2021, prior to installing the production casing.

Especially at high temperatures, commonly employed HCl tends to treat only near wellbore regions and show high corrosivity against metal tubular. To counteract such drawbacks, the strong organic acid system SSB-007 was used for chemical stimulation [1]. The two hydraulic injection test series of spring and autumn 2022 are compared against a coupled hydro-thermal numerical simulation solved using a finite element discretization approach in COMSOL Multiphysics. To numerically model the Eden geothermal system, a cubical reservoir including the well trajectory and casing design, and four individual fault zones are considered at a depth between 3830 m and 4280 m TVD. Due to similarity in the geological context on the regional level, permeability, porosity, and other petrophysical parameters of the faulted and matrix properties of the Cornubian granites are considered based on the United Downs geothermal reservoir [2,3]. Initially, the permeability and porosity of the fault zone and matrix are calibrated using the spring hydraulic testing data. Later, the downhole pressure evolution of the spring and autumn injection tests is compared to qualitatively understand any permeability enhancement. Initial results indicate that up to 20% of fault zone permeability enhancement was achieved by the chemical stimulation operation. Future reservoir characterization would be helpful for developing more accurate geochemical models predicting permeability enhancement.

1. Lummer, N.R., Rauf, O. and Gerdes, S., 2015, June. https://doi.org/10.2118/174242-MS.

2. Mahmoodpour, S., Singh, M., Obaje, C., Tangirala, S.K., Reinecker, J., Bär, K. and Sass, I., 2022. https://doi.org/10.3390/geosciences12080296.

3. Reinecker, J., Gutmanis, J., Foxford, A., Cotton, L., Dalby, C. and Law, R., 2021. https://doi.org/10.1016/j.geothermics.2021.102226.

How to cite: Singh, M., Bossennec, C., Bär, K., Reinecker, J., Bilsland, R., Briggs, C., Cotton, L., Gutmanis, J., Bennet, T., Baumgärtner, J., Grand, A., Recalde Lummer, N., Rauf, O., Baujard, C., Genter, A., and Sass, I.: Numerical simulation of fault zone permeability enhancement by chemical stimulation operation at the Eden geothermal projects, UK, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12749, https://doi.org/10.5194/egusphere-egu23-12749, 2023.

EGU23-12771 | Orals | ERE2.4

Imaging of the subsurface magnetization of the Krafla geothermal area using a high-resolution drone magnetic survey and constrains from a 3D electrical conductivity model 

Claire Bouligand, Yu Liu, Jonathan M.G. Glen, Tait E. Earney, Grant H. Rea-Downing, Laurie A. Zielinski, Branden J. Dean, Leon Kaub, Svetlana Byrdina, Benjamin Lee, Max Moorkamp, Knutur Árnason, Benoît Gibert, and Anette K. Mortensen

During the summers of 2021 and 2022, we conducted drone magnetic surveys over the Krafla geothermal system in the Northern Volcanic Zone of Iceland. The purpose of this survey was to image the subsurface magnetization to help characterize the geometry of the geothermal system and to determine the geological structures and lithologies controlling it. This new survey was collected with two types of magnetometer systems (a fluxgate vector system and a cesium scalar system) fixed to a hexacopter and flown over an area of about 20 km2 with a spatial resolution (i.e. flight line spacing and flight elevation above ground level) of 50 m. The data were corrected for the magnetic effect of the drone using the MagComPy software of Kaub et al. (Geochem. Geophys. Geosyst., 22, e2021GC009745, 2021), for the diurnal variations of the Earth’s magnetic field using a local base-station magnetometer, and for the main (large-scale) magnetic field using the IGRF (International Geomagnetic Reference Model) model. The resulting magnetic anomaly map exhibits a pronounced magnetic low coincident with the active geothermal system. The map also displays many remarkable short-wavelength anomalies associated with topography, cultural features, geological structures such as fault and fissures, areas of superficial hydrothermal alteration and recent lava flows. The comparison of observed and terrain anomalies, the latter computed assuming a constant magnetization of about 10 A/m below topography, suggests a strong influence of topography. However, many discrepancies between observed and terrain anomalies also indicate significant variations of magnetization in the subsurface. We then tested whether we can assume that the main source of rock magnetization variations is a demagnetization associated with hydrothermal processes in the geothermal reservoir. To this end, we used the 3D model of electrical conductivity from Lee et al. (Geophys. J. Int., 220, 541-567, 2020) to evaluate the depth to the top of the geothermal reservoir, characterized by a high conductivity layer interpreted as a clay cap. Magnetic anomalies were then predicted assuming a simple forward model with constant and null magnetization above and below the clay cap, respectively. The resulting predicted anomalies reproduce some large scale features from the observed anomaly map but also display significant differences especially for short-wavelength signals. We therefore inverted for the distribution of magnetization in rocks above the geothermal reservoir using the jif3D code of Moorkamp et al. (Geophys. J. Int., 184, 477-493, 2011) and imposing a null magnetization in the reservoir. The resulting  distribution of magnetization appears to be strongly influenced by the distribution of surface alteration and fresh recent lava flows that were not accounted for in our initial forward model due to both the simplicity of the modeling assumptions and the lower spatial resolution of the electrical conductivity model. This study suggests that the joint inversion of magnetic and electrical conductivity data is a promising approach for the imaging of geothermal systems as it takes advantage of both the sensitivity with depth of electromagnetic methods and the lateral sensitivity of high-resolution magnetic surveys.

How to cite: Bouligand, C., Liu, Y., Glen, J. M. G., Earney, T. E., Rea-Downing, G. H., Zielinski, L. A., Dean, B. J., Kaub, L., Byrdina, S., Lee, B., Moorkamp, M., Árnason, K., Gibert, B., and Mortensen, A. K.: Imaging of the subsurface magnetization of the Krafla geothermal area using a high-resolution drone magnetic survey and constrains from a 3D electrical conductivity model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12771, https://doi.org/10.5194/egusphere-egu23-12771, 2023.

EGU23-12919 | Posters on site | ERE2.4

Challenges for geothermal exploration- fluviatile systems and new interpretation techniques 

Hartwig von Hartmann and Nana Yaw Ofori-Amanfo

What are the main challenges of exploring geothermal reservoirs with low temperatures, so-called low-enthalpy systems? A typical situation in European countries, especially Germany, is regionally different in high information density due to former intensive exploration activities for hydrocarbons. Regionally there are concepts of more or less successful exploitation for geothermal projects based on special subsurface conditions, which allow high water production at high temperatures. The development of such regions where geothermal energy plays an essential role in the energy supply extends over decades. Uncertainties in reservoir characterization lead to high investment risk and a lack of economic viability. The increase in energy costs and the intensified search for climate-neutral energy has recently intensified the search for suitable reservoirs for geothermal use. In this context, the development times of geothermal projects must be shortened, and possible reservoirs must be systematically surveyed. Exploration plays one or even an essential role. Even if the state assumes costs and risks, concepts for exploration must be developed according to the current state of the art.

A closer look reveals that even in areas with a high information density, more than knowledge about the subsurface beyond the hydrocarbon reservoirs is needed for geothermal use. The exploration goal in geothermal energy so far has been mainly structural exploration. To better estimate the reservoir quality, understanding the depositional space and subdivision into different facies is necessary. These tasks are then the basis for estimating petrophysical parameters for reservoir characterization. Here, newer interpretation techniques help to perform such tasks quickly.

An example of an interpretation of a 3D seismic dataset from the Bavarian Molasse illustrates this. The Tertiary sediments of the Molasse basin are composed of marine sequences, redeposition of debris fans of the adjacent Alpine region and drainage systems of the basin. Due to regionally different uplift and subsidence of the basin, east-west directed trends exist in the respective depositional systems. In the region studied here, these changes are extreme. The goal was to find and map evidence of fluvial systems in the depositional settings. The seismic patterns are very heterogeneous, and there are only a few continuous reflectors to subdivide the study area. Indications of fluviatile deposits are not evident at first.

By calculating local inclinations and inversion techniques, a variety of so-called phantom horizons can be generated and then visualized with different seismic attributes. This way, fluviatile patterns could be recognized in a 300m thick part of the Aquitaine. The mapping of these patterns followed a further step by exploiting the corresponding signals' similarity and spatial connections. Machine learning can perform further facies discrimination but cannot recognize these fluviatile patterns.

The work showed that existing data, with appropriate processing and new interpretation methods, can be efficiently used to search new geothermal reservoirs systematically. The scientific challenge that industrial orders cannot solve is a more detailed analysis of the evolution of the sedimentation space. However, this is necessary for the transfer of results to neighbouring areas.      

How to cite: von Hartmann, H. and Ofori-Amanfo, N. Y.: Challenges for geothermal exploration- fluviatile systems and new interpretation techniques, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12919, https://doi.org/10.5194/egusphere-egu23-12919, 2023.

EGU23-12965 | ECS | Posters on site | ERE2.4

Seismic methods to investigate the interplay between magmatism and tectonics in the Northern Apennines hinterland, Tuscan Magmatic province, Italy 

Karen Nicollet, Francisco Muñoz, Geneviève Savard, Domenico Montanari, Michele d'Ambrosio, Gilberto Saccorotti, Davide Piccinini, Nicola Piana Agostinetti, Juan Luis Porras Loria, Konstantinos Michailos, Riccardo Minetto, Marco Bonini, Chiara Del Ventisette, and Matteo Lupi

The Northern Apennines hinterland is normally referred to as a back-arc area affected by magmatism since the late Neogene, with intrusive and extrusive magmatic rocks being scattered through the southern Tuscany and the Tuscan Archipelago. This setting makes this geothermal area one of the most important worldwide.  The very high geothermal gradient of the Tuscan Magmatic Province (up to 200–1000 mW/m2 in the central part of the Larderello-Travale geothermal field) fuels vigorous fluid flow that promotes a widespread geothermal activity. The plumbing magmatic systems progressively migrated eastwards. In Tuscany, the Elba Island is proposed to be the ancient (and now exhumed) analogue of the Larderello-Travale geothermal system where Pliocene to Pleistocene granites have been found at about 3 km depth. The occurrence of such magmatic bodies links to one of the most debated structures of the region, namely the K-horizon seismic reflector. Early authors suggest that this level may represent the transition between ductile and brittle geological units. Other authors propose that the k-horizon may represent a level where the magmatic brines released by the cooling plutons are stored at super-critical conditions.

To understand the spatial and temporal relationship between tectonics and eastwards migration of magmatism, we deployed a seismic network composed of 30 broadband sensors that complemented the permanent INGV network from September 2020 to August 2021. We used QuakeMigrate to build the seismic catalogue and identified 915 events. The seismic activity is well spread across the region and occurs in swarm sequences in areas marked by higher geothermal gradients, particulary in the Larderello-Travale geothermal field. We investigate the seismic clusters and compare them against the locations obtained with the permanent monitoring network. Our results significantly reduce the magnitude of completeness for the Northern Appennines hinterland and provide new insights into the tectonics of the region. This study will be continued with a newly funded project that will use ambient noise methods acquired by nodal networks to provide high-resolution tomographic inversions of the geothermal systems of the Tuscan Magmatic Province.

How to cite: Nicollet, K., Muñoz, F., Savard, G., Montanari, D., d'Ambrosio, M., Saccorotti, G., Piccinini, D., Piana Agostinetti, N., Porras Loria, J. L., Michailos, K., Minetto, R., Bonini, M., Del Ventisette, C., and Lupi, M.: Seismic methods to investigate the interplay between magmatism and tectonics in the Northern Apennines hinterland, Tuscan Magmatic province, Italy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12965, https://doi.org/10.5194/egusphere-egu23-12965, 2023.

EGU23-13303 | ECS | Orals | ERE2.4

Seismic anisotropy analysis based on synthetic and measured data for crystalline rock characterization 

Kathrin Behnen, Marian Hertrich, Hansruedi Maurer, and Alexis Shakas and the Bedretto-Team

The prior characterization of a reservoir volume as well as the monitoring of potential changes during heat extraction is highly important to ensure an economic and safe engineering and operation of a geothermal reservoir. While the use of active seismic measurements from the surface and in boreholes is commonly used to describe the seismic velocity field in the subsurface, its potential to analyze the seismic anisotropy is often neglected. We used active seismic crosshole measurements to analyze seismic anisotropy at the field scale to provide important information about the elastic properties and take advantage of this information for the analysis of the in-situ rock-physical conditions.

For the analysis of seismic anisotropy, a reliable data set is essential. We studied the sensitivity of the resulting anisotropy model to inaccuracies in the survey geometry by computing synthetic data and showed that inaccuracies of only a few degrees in dip and azimuth of the borehole orientation can significantly change the resulting anisotropy model of the volume. Especially the orientation of the symmetry axis used to describe a transverse isotropic model (TI) is highly sensible to source and receiver positions.

Beyond the analysis of the synthetic data, the focus of our study was on the exploitation of real measurement data. These data were recorded in a campaign in the Bedretto Underground Laboratory for Geosciences and Geoenergies (BULGG) in Ticino, Switzerland. The laboratory provides the opportunity to record crosshole data with high quality in a controlled environment. The geometry of the boreholes that we used allows a high coverage of ray path orientations which is crucial for the analysis of anisotropic wave propagation. The recorded data were used to create an anisotropy model of the subsurface based on a grid search and optimization algorithm, searching for both the optimized Thomsen parameters and the ideal orientation of the symmetry axis of the tilted TI model. The results give evidence of an ambient elastic anisotropy, while the host rock (Rotondo Granite) has proven negligible intrinsic anisotropy in previous laboratory measurements at sample scale. Further investigation will analyze the effect of the fracture inventory and ambient state of stress as potential controlling factors of the observed anisotropy. This relation can potentially help to monitor changes in the stress field during geothermal operations for a better hazard assessment.

How to cite: Behnen, K., Hertrich, M., Maurer, H., and Shakas, A. and the Bedretto-Team: Seismic anisotropy analysis based on synthetic and measured data for crystalline rock characterization, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13303, https://doi.org/10.5194/egusphere-egu23-13303, 2023.

EGU23-13667 | Posters on site | ERE2.4

Low temperature thermochronology as a tool for geothermal exploration: A promising test from the Larderello-Travale Geothermal Field (Italy). 

Domenico Montanari, Giovanni Ruggieri, Marco Bonini, and Maria Laura Balestrieri

High enthalpy geothermal fields are typically associated with magmatic intrusions providing the heat source that makes the system working. To identify and locate these features, geothermal exploration generally uses expensive, time-consuming approaches that could also require complex logistics. Here we present the result of a pilot study carried out in the well-known Larderello-Travale geothermal field (Tuscany, Italy), exploring the possibility of an advantageous use of low temperature thermochronology to obtain useful information implementing the geothermal exploration workflow. The majority of the collected samples (except one retaining the apatite fission-track age of undisturbed, or almost undisturbed country rocks) cluster in a close time span ranging between 3.1±0.8 and 1.9±1.1 Ma, which clearly matches the known ages of magmatic bodies in the region. We propose that this approach can contribute to the identification of sectors recently affected by thermal perturbations that could have led to the development of hydrothermal systems. This approach has allowed us to achieve clues for the presence of subsurface magmatic intrusions even in areas where currently there are no direct indications. Given the small number and distribution of analyzed samples, our contribution represents a first attempt that demonstrates the potentiality of the method in geothermal exploration, but that needs to be verified by further studies involving a larger sampling density. Overall, our results suggest how low temperature thermochronology can be a powerful, fast, and cost-effective tool for geothermal exploration, to be used jointly with the classical methods.

How to cite: Montanari, D., Ruggieri, G., Bonini, M., and Balestrieri, M. L.: Low temperature thermochronology as a tool for geothermal exploration: A promising test from the Larderello-Travale Geothermal Field (Italy)., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13667, https://doi.org/10.5194/egusphere-egu23-13667, 2023.

EGU23-14105 | Posters on site | ERE2.4

Potential for deep geothermal heat production in clastic rocks of the southern North German Basin – A case study from Hoya, Germany 

Michael Kettermann, Oliver Ritzmann, Jens Battermann, and Florian Wellmann

Deep geothermal aquifers can be a good source for industry applications with a high heat demand in the course of the energy transition. Industries such as paper production require heat sources that are independent of global market fluctuations, with predictable, reliable and green long-term supply. A number of clastic aquifers have been identified as potentially feasible for geothermal use within the North German Basin ranging from the lower Cretaceous to Middle Bunter Sandstone. Due to the extensive hydrocarbon exploration in the North German Basin, it is often possible to provide a local subsurface analysis of the geothermal potential at the location of the required use.

In this work, we present a case study from the town of Hoya in the southern North German Basin, where an abandoned hydrocarbon exploration well is available, as well as numerous wells in the vicinity (20 km) and some 2D seismic lines. From well log analysis, well reports, seismic data and an available 3D model of Lower Saxony, we evaluate the quality of different clastic reservoirs in the study area. We found? that many of the reservoirs that are known for good quality sandstones in the North German Basin are presented as shales at the paper mill in Hoya. Potentially usable sandstone reservoirs include the lower Cretaceous Aptian (top ca. 1600 m) and Valendis Sandstone (top ca. 1700 m), the middle Jurassic Dogger Delta 2 (top ca. 1950 m) and the Lower Triassic Hardegsen Sandstone (top ca. 3850 m). Surrounding well data, however, show a large spatial heterogeneity for these lithologies over relatively short distances. We include these geological uncertainties, temperature measurements from wells, permeability measurements from well tests and the specific requirements of a paper production company to evaluate the geological and economic feasibility, based on geothermal energy estimations and levelized costs of heat for the individual reservoirs.

How to cite: Kettermann, M., Ritzmann, O., Battermann, J., and Wellmann, F.: Potential for deep geothermal heat production in clastic rocks of the southern North German Basin – A case study from Hoya, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14105, https://doi.org/10.5194/egusphere-egu23-14105, 2023.

EGU23-14202 | Posters on site | ERE2.4

Hydrogeochemical research of thermal waters from Topusko, Croatia 

Mirja Pavić, Maja Briški, Marco Pola, and Staša Borović

A hydrochemical and geothermometric study of thermal waters in Topusko (Croatia) was conducted in order to improve the existing conceptual model of the Topusko hydrothermal system. The town of Topusko is located 80 km south of Zagreb at the SW edge of the Pannonian Basin System, which has favourable geothermal characteristics. The natural thermal springs of Topusko with temperatures up to 53°C and thermal waters from shallow wells with temperatures up to 65°C represent the second warmest natural thermal water source in Croatia. Water samples have been collected monthly since March 2021 from two natural thermal springs, i.e. Livadski izvor and Blatne kupelji springs, and the TEB-4 thermal well in the discharge area of the hydrothermal system. Furthermore, rainwater was sampled in the supposed recharge area. Chemical composition of groundwater is determined by the original composition of the infiltrated water as well as chemical reactions with various rocks along its circulation path. In-situ parameters, major anions and cations, stable water isotopes, radioactive isotope analysis of tritium (3H), and silica geothermometers were used to assess the origin of thermal waters in Topusko and their interaction with the thermal aquifer. Furthermore, a local meteoric water line was constructed and compared with the isotope ratio of the thermal waters. The results pointed to: i) the meteoric origin of thermal waters according to stable water isotopes; ii) Ca-HCO3 hydrochemical facies suggesting that carbonate dissolution occurs in the aquifer, being consistent with the presence of carbonates in the stratigraphic logs of wells; iii) an equilibrium temperature in the reservoir of 88°C according to silica geothermometers; and iv) low tritium activity being consistent with sub-modern waters and a recharge before 1955. The monitoring of these thermal springs will continue for another year to collect a larger dataset and reinforce our conclusions. Additional analyses including radiocarbon dating and stable isotope composition from SO42- will be conducted to provide a comprehensive hydrochemical characterisation of these thermal waters, which have been utilised since ancient Roman times, and intensively since 1980s, but have not been thoroughly investigated.

Acknowledgments: Presented research has been conducted in the scope of the project “Multidisciplinary approach to hydrothermal system modelling” (HyTheC) funded by the Croatian Science Foundation under grant number UIP-2019-04-1218.

How to cite: Pavić, M., Briški, M., Pola, M., and Borović, S.: Hydrogeochemical research of thermal waters from Topusko, Croatia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14202, https://doi.org/10.5194/egusphere-egu23-14202, 2023.

EGU23-14534 | Posters on site | ERE2.4

The potential of probabilistic moment-tensor inversions for the characterization of geothermal reservoirs in urban environments 

Deyan Draganov, David Naranjo, Katerina Polychronopoulou, and Cornelis Weemstra

Geothermal energy is a cleaner and more sustainable source of power, which plays a key role in the transition to a low-carbon economy. Sustainable and safe exploitation of geothermal resources, however, depends on our ability to understand and manage the associated seismic risks. In 2018, Nature's Heat geothermal project began operations in Kwintsheul, Netherlands, aiming to supply heat to 64 hectares of greenhouses. Between July and October 2019, a temporary seismic array was installed to monitor for possible seismic activity at the site. Microseismic moment-tensor inversion is a valuable tool for understanding the mechanics and structure of geothermal reservoirs, and for optimizing their exploitation. It can be challenging, though, to apply this technique when there are high levels of ambient seismic noise, as is often the case in geothermal operations in densely populated areas. In this study, we evaluate the feasibility of inverting the centroid moment tensor of microseismic events in Kwintsheul, using probabilistic moment-tensor inversions. We first test the probabilistic inversion using synthetic recordings of ambient seismic noise, after which we apply the technique to the low-magnitude (Md=0.16) event recorded on July 14, 2019. Our results give insight into the challenges and limitations of applying moment-tensor inversion to low-magnitude events in the context of geothermal operations in the Netherlands.

How to cite: Draganov, D., Naranjo, D., Polychronopoulou, K., and Weemstra, C.: The potential of probabilistic moment-tensor inversions for the characterization of geothermal reservoirs in urban environments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14534, https://doi.org/10.5194/egusphere-egu23-14534, 2023.

EGU23-14708 | ECS | Posters on site | ERE2.4

Monitoring steam content in the crust with seismic noise 

Pilar Sánchez-Pastor, Sin-Mei Wu, Ketil Hokstad, Bjarni Kristjánsson, Vincent Drouin, Gunnar Gunnarsson, Cecile Ducrocq, Antonio Rinaldi, Anne Obermann, and Stefan Wiemer

Seismic noise interferometry (SNI) is based on the computation of seismic response by extracting correlated wavefields from continuous seismic recordings. This seismic response is understood as the Green’s function of the propagation medium and it is typically used to image the subsurface. Furthermore, a regular retrieval of this magnitude in time enables the identification of changes in the structural and mechanical properties of the subsurface and therefore, it can be also used for monitoring purposes.

Here, we use SNI to monitor the steam content in geothermal reservoirs. The massive extraction of fluids commonly causes a pressure drop in the rock matrix and land subsidence in the surroundings of production areas. Furthermore, the boiling point decreases yielding decompression boiling. Estimating the steam fraction at depth is challenging especially in reservoirs with two-phase fluids. In this work, we focus on the Hengill geothermal area (Iceland), where the steam ratio has increased by around 30% in the last 10 years due to the harnessing of geothermal energy.

In this area, we measure the land deformation with synthetic aperture radar interferometry (InSAR) and estimate seismic velocity changes with SNI. We observe that both magnitudes linearly decrease in the long term accordingly to the energy production. Besides, we model the expected seismic velocity drop with in-situ borehole data (temperature, pressure, and steam ratio) and conclude that the seismic velocity drop might be related to the steam evolution within the reservoir. These results offer an innovative way of estimating the steam content in the crust with a surface and non-invasive technique.

How to cite: Sánchez-Pastor, P., Wu, S.-M., Hokstad, K., Kristjánsson, B., Drouin, V., Gunnarsson, G., Ducrocq, C., Rinaldi, A., Obermann, A., and Wiemer, S.: Monitoring steam content in the crust with seismic noise, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14708, https://doi.org/10.5194/egusphere-egu23-14708, 2023.

The Ilan Plain in northeastern Taiwan located at the southern termination of the Okinawa Trough, which is formed by the back-arc extension of the Ryukyu subduction zone. Owing to this extensional tectonic setting, the Ilan Plain shows distributed hot springs with high geothermal gradient in several places, such as the Chingshui, Jiaoxi, Longde-Lize and Hongchailin areas. These are potential locations for geothermal exploration which require a thorough investigation to understand their geothermal system and to evaluate their potential in geothermal power generation. Seismic velocity provides key information to determine properties of a geothermal system including the distribution of fluids, fractures, and porosity. This study obtained seismic velocity images of the Ilan Plain and the surrounding area by joint inversion of body wave travel times of local earthquakes and Rayleigh wave phase velocities from ambient noise correlations recorded by a temporary dense geophone array in the Ilan Plain and the Formosa Array in northeastern Taiwan. The joint inversion takes advantage of the complementary sensitivities of both data types to better constrain both shallow and deep structures. In addition, we also lift the flat earth surface assumption commonly assumed in the surface wave tomography to avoid possible biased velocity structure due to topography by adapting the surface wave sensitivity kernel to the surface topography in the inversion. The obtained image at the 1-km depth shows low Vp and Vs corresponding to unconsolidated Quaternary sediments. The deeper images at 2- to 5-km depths show a low-velocity corridor extending from the Guishan volcanic island northeastern offshore to the southwest corner of the Ilan Plain, implying that the heat source of the geothermal systems in the Ilan Plain may be related to magmatic intrusions of backarc rifting. Locally, in the shallow region of the Chingshui and Jiaoxi area and the deeper region of the Hongchailin and Longde-Lize area, the high Vp/Vs ratio with little increase in Vp and significant decrease in Vs could indicate a saturated rock with high porosity, based on the rock physics principles in geothermal environment summarized in previous study. The low Vp, Vs, and Vp/Vs ratio in the shallow region of the Hongchailin area could indicate vapor-rich high temperature environment. Our results demonstrate the potential of new seismic imaging integrating body- and surface-wave data for geothermal exploration.

How to cite: Su, P.-L., Huang, H.-H., Lin, C.-H., and Lee, J.-C.: High resolution Vp and Vs imaging for geothermal exploration in the Ilan Plain, northeastern Taiwan by joint inversion of body-wave and surface-wave data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14710, https://doi.org/10.5194/egusphere-egu23-14710, 2023.

EGU23-14928 | Posters on site | ERE2.4

Novel Directional Steel Shot Drilling Technology for Short-Radius Multilaterals – Field Application and Commercial Impact 

Andreas Reinicke, Paromita Deb, Martin O. Saar, Vedran Zikovic, V., Erich Lassnig, Marcel Knebel, and Jan Jette Blangé

Reliable delivery of economic well performance of geothermal projects is affected to a high degree by uncertain reservoir quality. Construction of multilateral wells is well known as an effective concept to overcome the challenges of reservoir heterogeneity or low permeability by increasing the reservoir contact. However, the drilling costs for these structures are currently very high and multilateral well construction with standard rotary steerable systems is complex. Canopus’ directional steel shot drilling system (DSSD) has the potential to enable the construction of short-radius multilaterals at rates attractive for geothermal applications.

As part of the European GEOTHERMICA project ‘DEPLOI the HEAT’, the operational performance and economic impact of Canopus’ DSSD system will be investigated. Full-scale tests at TNO’s Rijswijk Centre for Sustainable Geo-Energy (RCSG) and a field trial at the Hagerbach underground test facility (VSH) are planned for the first project year. The RCSG drilling rig enables full factory acceptance testing (FAT) of the drilling assembly before the trial at the VSH site is executed. The geology at the VSH site reflects conditions of typical mid-depth fractured limestone reservoirs in Switzerland and elsewhere. At VSH, a complete set of operational parameters and system longevity will be tested with a full-scale trial to prepare for live well deployment.

Further, a techno-economic assessment of multilateral structures drilled with Canopus’ DSSD system will highlight the potential for increasing or safe-guarding well productivity and economically de-risking geothermal projects. Several operators are involved in this project and the techno-economic assessment of the drilling technology will be based on several site-specific data sets provided by them. Stochastic modeling approaches will be implemented to generate an ensemble of equally probable realizations of permeable structures in the subsurface. Then, the performance and costs of different well geometries and multilateral configurations in different subsurface model realizations will be evaluated and compared.

The current status of this project will be presented with a focus on the factory acceptance testing at TNO, the VSH trial preparations and the workflow developed for the techno-economic assessment of this innovative multilateral drilling technology.

How to cite: Reinicke, A., Deb, P., Saar, M. O., Zikovic, V., V., Lassnig, E., Knebel, M., and Blangé, J. J.: Novel Directional Steel Shot Drilling Technology for Short-Radius Multilaterals – Field Application and Commercial Impact, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14928, https://doi.org/10.5194/egusphere-egu23-14928, 2023.

About half of all heating in Sweden comes from district heating, which makes it the most common form of heating in Sweden. The Otaniemi deep drilling project by St1 in Finland was a game changer, as it launched the idea to feed district heating systems with fossil-free, sustainable geothermal heat from great depths. Göteborg Energi AB has been conducting an exploration drilling program over the last three years targeting major Precambrian deformation zones in radiogenic heat-producing granites. The in-situ temperatures of these granites are boosted by radioactive gamma-ray decay from heat producing elements (K, U, Th). The objective is to develop an engineered geothermal system at 5-7 km depth where the groundwater temperatures reach 120°C to feed the local district heating system. Knowledge of the state of stress is central for this development because it provides insights for the understanding bedrock stability, induced seismicity and fluid flow patterns.

A first 1 km deep sub-vertical borehole in Högsbo was fully cored in 2021, and a second 1 km long inclined borehole in Sisjön was completed in 2022, less than 5 km south of the first borehole. Downhole logging was conducted in both boreholes to constrain downhole temperature, natural gamma radiation, fracture occurrence and orientation of in situ stress.

An acoustic borehole televiewer was used to map fracture occurrence and their geometry, as well as to investigate if stress-induced failure has occurred in the wellbore. For vertical boreholes, drilled parallel with a principal (vertical) stress, borehole breakouts and drilling-induced tensile fractures reveal the orientation of minimum- and maximum horizontal stress, respectively, if the tangential stress concentration generated by the borehole overcomes the compressional and tensile strength of the rock mass, respectively. Here, the objective is to investigate stress-induced failure in an inclined borehole, that is not aligned with a principal stress.

We analysed and processed acoustic borehole images from the Sisjön borehole and mapped fractures occurrence and stress induced features (borehole breakouts and drilling-induced tensile fractures). We have detected some stress-induced features at about 400-500 m depth, but most stress-induced features occur below 800 m. Preliminary results of drilling-induced tensile fractures suggest an orientation of maximum horizontal stress of 145±10°N along the inclined borehole. Corresponding mean orientation from borehole breakouts is slightly lower (132±21°N). More detailed studies are required to confirm the preliminary observations, and to account for the borehole inclination.

How to cite: Ask, M. and Pierdominici, S.: Constraining horizontal stress orientations for geothermal exploration in the inclined Sisjön borehole, Southwest Sweden, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15263, https://doi.org/10.5194/egusphere-egu23-15263, 2023.

The application of machine learning (ML) for reservoir characterization and prospect identification in seismic data is becoming standard practice in the exploration industry. This technique has proven useful in identifying patterns in the data that might be overlooked by the interpreter. In addition, it improve reservoir predictions and characterization at a lower computational cost.

In this study, we analyze the fluvio-deltaic seismic facies of the Upper Triassic Exter Formation in the North German Basin. For this purpose, we applied seismic attributes and an unsupervised machine learning algorithm based on waveform segmentation of seismic amplitude data. Furthermore, to evaluate the evolution of deltaic complexes, we implemented the stratal slicing technique through the resulting waveform segmentation and the generated attributes volumes.

The study resulted in the delineation of a number of fluvial architectural elements in the study area, i.e. lateral shifting of individual channels contributing to the formation of channel belt reservoirs within the Rhaetian Deltaic System.

These results contribute significantly to reducing the risk of geothermal exploration in the North German Basin by proposing for the first time a way to improve the prediction of Rhaetian reservoirs on a local scale based on seismic methods.

How to cite: Bello Rujana, L. A., von Hartmann, H., Moeck, I., and Franz, M.: Identification of fluvio-deltaic facies based on 3D-seismic attributes analysis and unsupervised machine learning techniques: strategy to reduce geothermal exploration risk in the North German Basin., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17482, https://doi.org/10.5194/egusphere-egu23-17482, 2023.

EGU23-495 | ECS | Orals | ERE2.6 | Highlight

Comparison of optimization approaches for the well placement of groundwater heat pumps 

Smajil Halilovic, Fabian Böttcher, Kai Zosseder, and Thomas Hamacher

Groundwater heat pumps (GWHP) use the thermal energy stored in groundwater. Therefore, GWHP systems extract groundwater via extraction wells and, after heat exchange, return it to the same aquifer via injection wells. The returned water has a lower temperature than the pumped water since the GWHP extracts heat for domestic heating. This causes the development of so-called thermal plumes in the aquifer. The thermal plume dissipates downstream according to the local groundwater flow direction and can reach the extraction wells of neighboring systems. Depending on their mode of operation, this altered water can significantly reduce their efficiency. To ensure optimal use of geothermal potential, such negative interactions between neighboring systems must be avoided and are legally constrained to a maximum temperature change of 1K in downstream extraction wells. One way to avoid the negative interactions and to maximize the spatial utilization is the optimal placement of GWHPs and their wells. In addition, the optimal placement of wells is important within a system to avoid significant thermal recycling. To determine the optimal placement of wells, estimations of thermal plumes are required. These calculations can be performed using analytical or numerical (PDE-based) models.

In this contribution, we compare two different optimization approaches for the placement of GWHP wells. The first approach is based on the linear advective heat transport model (LAHM), which is an analytical model, and integer linear programming. The second approach is based on numerical simulation of groundwater flow and heat transport and the adjoint optimization method. We first present these two recently developed optimization approaches and then analyze their potential applications (optimal management of the geothermal resource, optimal system design, urban energy planning, etc.), limitations, and future possibilities. We use real case studies to analyze and compare the approaches.

How to cite: Halilovic, S., Böttcher, F., Zosseder, K., and Hamacher, T.: Comparison of optimization approaches for the well placement of groundwater heat pumps, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-495, https://doi.org/10.5194/egusphere-egu23-495, 2023.

This study presents the performance evaluation of ATES-GSHP system based on long term monitoring since 2016. It consists of two office buildings with a combined net heated floor area of 18000 m2. ATES-GSHP system is in operation since 2016. The aim evaluate the performance as well as propose KPIs that take into account both the building HVAC system and ATES long term sustainable operation. 
The system is equipped with comprehensive instrumentation in HAVC system, heatpumps and aquifer including a unique and continuous installation of high resolution distributed temperature sensing using fiber optic cables throughout the aquifer.

The system is connected to district heating and has two heat pumps with a total nominal cooling and heating capacity of 1.5 MW and 1.8MW. Allowable groundwater extraction and injection is 50 l/sec. with undisturbed groundwater temperature of 9.5 ◦C.  The monitoring period analyzed for the HVAC system is March 2019 - March 2020 (for ATES from March 2016- March 2020). For the year 2019/2020, the total heating load (including domestic hot water) and cooling load was 456 and 381 MWh respectively. The total average heating and cooling used from the ATES are 673 MWh and 743 MWh respectively during the first 3 annual storage cycles of operation. Over the first three storage cycles, the average injection and extraction temperatures in the warm and cold ATES sides range between 7.6◦C and 13.3◦C. The average temperature differences across the main heat exchanger for ATES are 4.5-2.8 K which is 4-5 degrees lower than the optimum value. The average thermal recovery efficiency over the first 3 storage cycles were 47 % and 60 % for warm and cold storages respectively. The seasonal performance factors SPF for the system ranged between 5-54 depending on the boundary levels 0, 1 and 2 according to Annex 52 boundary definition. Furthermore, it discusses possible improvements to be implemented regarding the system boundary definition and GSHP-ATES coupled operation. The data analysis indicated annual energy and hydraulic imbalances which results into undesirable thermal breakthrough between the warm and cold side of the aquifer. Despite having favorable conditions from aquifer point of view, this was mainly due to suboptimal operation of the building energy system which led to insufficient heat recovery from the warm side, and subsequently insufficient cold injection in the cold wells, despite the building heating demand and the available suitable temperatures in the ATES. The cause of the suboptimal operation is attributed to oversizing of the heat pumps. As a result, the heat pumps could not be operated during small-medium loads. Additionally, the limitations of currently used energy and thermal KPIs for ATES are discussed and additional thermal KPI named heat exchanger efficiency balance (βHEX) that connects and evaluate the optimum operational point of temperature differences from both the building and ATES prospective is proposed to contribute in providing more complete picture on the ATES-building interaction performance and highlights the losses in energy recovery from ATES are due to the subsurface processes or building energy system operation.

How to cite: Abuasbeh, M.: Long term performance monitoring and KPIs’ evaluation of Large Scale ATES-GSPH system: Case study in Stockholm, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-875, https://doi.org/10.5194/egusphere-egu23-875, 2023.

Ground-coupled heat pump systems can help reducing energy consumption and electrical peak power demand while contributing to reduce greenhouse gas emissions. A key element of these systems is the ground heat exchanger that links the mechanical equipments to the underground geological materials. Although most ground heat exchangers are composed of closed-loop wells, standing column wells (SCW) represent a transformative opportunity in dense urban areas where aquifer productivity is limited. Based on a decade of research conducted in the area of Montreal in Canada, this conference will illustrate the potential of SCWs, present the preliminary results of two demonstration projects, discuss the impact of hydrogeological and hydrogeochemichal conditions on system design and discuss some recent advances related to field testing and modeling of SCWs. The challenges that remain to be overcome will also be discussed.

How to cite: Pasquier, P.: Standing Column Wells: A transformative opportunity to provide heating to buildings in dense urban areas., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1318, https://doi.org/10.5194/egusphere-egu23-1318, 2023.

EGU23-1781 | Orals | ERE2.6 | Highlight

Heat accumulation in shallow aquifers: managing a growing resource 

Peter Bayer, Guillaume Attard, Philipp Blum, Hannes Hemmerle, Barret L. Kurylyk, Kathrin Menberg, Maximilian Noethen, and Susanne Benz

Heat loss from buildings, infrastructure and enhanced heat flow from sealed surfaces increase the temperatures of shallow groundwater often more than global warming. A worldwide analysis of thousands of wells reveals that the temperature at every second location is higher than expected, and local anthropogenic heat sources that exist for decades contribute to subsurface waste heat accumulation down to a depth of around 100 m. At some places, such as in the city centre of Cologne, heating of groundwater by several degrees of Celsius appears to have even reached a maximum. Here, long-term temperature records reveal stabilizing thermal conditions in the shallow aquifer. This also means that the geothermal potential has increased significantly, possibly to a critical level for maximum stored heat in place. Still, the natural geothermal resources together with the artificially stored resources are often overlooked. In many regions, recycling only the energy lost to the subsurface could (1) fulfil a substantial part of the heat demand of buildings, and (2) increase the efficiency of heat pumps with a more favourable thermal regime during the heating period. This resource is growing.  On the global scale, by the end of this century nearly 75% of the heat demand could be covered by recycling the heat that accumulates in the subsurface from anthropogenic heat loss and in response to climate change. Especially in densely populated areas, continued heat accumulation mitigates the risk of overexploiting the geothermal potential of shallow aquifers. Sustainable thermal management of aquifers must integrate concepts of heat recycling to avoid long-term warming of groundwater. For this, integrated spatial planning is needed. Shallow geothermal systems such as groundwater heat-pump installations have to be spatially organized in urban districts to achieve optimal use of the geothermal resource. They can maintain controlled cooling of the groundwater while benefitting from enhanced waste heat flux. As an example, we discuss the thermal interference of urban infrastructure and geothermal wells for the city of Lyon, which are spatially arranged based on hydraulic and thermal criteria to benefit from urban groundwater heating.

How to cite: Bayer, P., Attard, G., Blum, P., Hemmerle, H., Kurylyk, B. L., Menberg, K., Noethen, M., and Benz, S.: Heat accumulation in shallow aquifers: managing a growing resource, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1781, https://doi.org/10.5194/egusphere-egu23-1781, 2023.

EGU23-2940 | Posters on site | ERE2.6

Borehole Heat Exchangers: a potential trigger for aquifer cross-contamination? 

Alessandro Casasso, Natalia Ferrantello, Simone Pescarmona, and Rajandrea Sethi

The number of Ground Source Heat Pumps (GSHPs) has been growing steadily in the last 20 years, and so has the number of Borehole Heat Exchangers (BHEs), which perform the heat exchange between the ground and the heat pump. BHEs are generally about 100 m deep and, hence, they can cross different aquifers. Concerns have been raised about the possible preferential flow of contaminants that can occur through boreholes, also known as cross-contamination. The strength of such phenomenon depends on the vertical hydraulic gradient between the aquifers and the hydraulic conductivity of the grout filling. Therefore, we developed a numerical flow and solute transport model in severe conditions to assess to which extent a BHE can induce cross-contamination between a shallow contaminated aquifer and a deep uncontaminated one, separated by an aquiclude. The results show that the leakage flow and the contaminant spatial distribution in the deep aquifer are well reproduced with analytical formulae, which can therefore be used to assess the potential impact of cross-contamination. Results also confirm that the geothermal grouts available in the market, with hydraulic conductivities well below 10-6 m/s, guarantee a sufficient protection from preferential flow through borehole heat exchangers.

How to cite: Casasso, A., Ferrantello, N., Pescarmona, S., and Sethi, R.: Borehole Heat Exchangers: a potential trigger for aquifer cross-contamination?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2940, https://doi.org/10.5194/egusphere-egu23-2940, 2023.

EGU23-5558 | ECS | Orals | ERE2.6

High-Resolution Spatiotemporal Monitoring Data During Groundwater Heat Pump System Operation 

Ji-Young Baek, Hae-Rim Oh, Seung-Wook Ha, and Kang-Kun Lee

Sustainability is one of the points in the design stage of the groundwater heat pump (GWHP) system. Thermal impacts on the surrounding environments should be accurately configured to ensure system sustainability. To achieve that goal, a sophisticated characterization of the target aquifer is required. So far, considering heterogeneity of subsurface environment in system design is challenging because there is lack of case studies provided high-resolution monitoring data enough to catch the heterogeneity. In this study, to detect the hydraulic and thermal responses to the GWHP operation, 12 monitoring wells were densely constructed between two geothermal wells at Eum-Seong, Republic of Korea. During the system operation, the high-resolution spatiotemporal changes in hydraulic pressure and temperature were detected by pressure sensors and fiber optic-distributed temperature sensing (FO-DTS). Monitored results were interpreted by time-series analysis to derive the thermal front velocity between monitoring wells. During the GWHP system operation, groundwater level monitoring results showed that a dynamic flow condition was generated especially near the geothermal wells up to 20 times of background flow. The estimated effective thermal velocities were comparable with the theoretically calculated velocities, but the higher velocity randomly appeared at the specific depths. From this case study, we confirmed FO-DTS was applicable to monitor the GWHP system. Those three-dimensional high-resolution monitoring data enabled to prove the existence of horizontal and vertical heterogeneity, indicating the need for accurate characterization of aquifer properties.

 

Acknowledgements

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2022R1A2C1006696). This work was also supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government(MSIT) (No. 2022R1A5A1085103).

 

How to cite: Baek, J.-Y., Oh, H.-R., Ha, S.-W., and Lee, K.-K.: High-Resolution Spatiotemporal Monitoring Data During Groundwater Heat Pump System Operation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5558, https://doi.org/10.5194/egusphere-egu23-5558, 2023.

EGU23-5989 | ECS | Orals | ERE2.6

Monitoring responses to mine water geothermal use in a highly characterised and instrumented groundwater system 

Andres Gonzalez Quiros, David Boon, Donald John MacAllister, Alan MacDonald, Barbara Palumbo-Roe, Brighid Ó Dochartaigh, Kyle Walker-Verkuil, and Alison Monaghan

Mine water geothermal has great potential to provide low carbon heating, cooling and energy storage. Some successful examples have shown that a flooded mine is a reliable, low carbon heat source and could contribute to a new green energy future for many European post-mining regions. To date, however, this potential has been hindered by scientific and technical challenges that have resulted in delay, cost overrun, or even abandonment of some mine water geothermal projects. Key sources of uncertainty that present challenges for developers, operators and regulators are groundwater flow behaviour and temperature distribution in abandoned mines under abstraction/reinjection cycles, the long-term sustainability of the geothermal system, and its interactions and impacts in the surrounding environment. 

The UK Geoenergy Observatory (UKGEOS) in Glasgow, Scotland, is an at-scale research facility with exceptional levels of hydrogeological and thermal characterisation and downhole instrumentation designed to monitor and quantify subsurface change and provide data to address challenges and risks associated with mine water geothermal systems design and operation. The Observatory includes four mine water boreholes connected in an open loop configuration with pumps for abstraction/reinjection, a heat pump-chiller and three different heat exchangers to enable testing of multiple modes of heat pump operation (heating and cooling) and component performance. A further two boreholes intercepting mine workings are equipped with downhole electrical resistivity tomography (ERT) and hybrid fibre-optic cables for distributed temperature sensing (Passive and Active DTS). Together with five environmental monitoring boreholes, a seismic monitoring borehole and ten hydrogeological downhole data loggers for continuous pressure, temperature, and electrical conductivity monitoring, the dedicated Observatory, which is not connected to any customers, is well equipped to examine the interaction and impacts of geothermal energy systems.

In this work we present a comprehensive set of initial hydrogeological and thermal observations collected during the construction and commissioning stages of the Observatory, including long term baseline monitoring, results of initial well pumping and heat abstraction/reinjection tests. These observations include evidence for the general groundwater flow circulation in the system, groundwater level response to recharge events, different transmissivities in different mined zones, and limited connectivity between mine workings at different depths, the surrounding aquifers and the River Clyde. We have integrated hydrogeological, thermal, and other information to develop an initial conceptual hydrogeological model of the system. Using the conceptual model and field data we have developed flow and heat numerical models to evaluate alternative scenarios of heating and cooling. Modelling results indicate variable flow paths and response times for thermal breakthrough for different geothermal operational configurations. Academic and commercial researchers are encouraged to get in touch to discuss using the Observatory’s unique capability for future mine water geothermal energy investigations, including investigating the behaviour, sustainability and impacts of groundwater flow and temperature under geothermal abstraction/reinjection cycles. 

How to cite: Gonzalez Quiros, A., Boon, D., MacAllister, D. J., MacDonald, A., Palumbo-Roe, B., Ó Dochartaigh, B., Walker-Verkuil, K., and Monaghan, A.: Monitoring responses to mine water geothermal use in a highly characterised and instrumented groundwater system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5989, https://doi.org/10.5194/egusphere-egu23-5989, 2023.

EGU23-10285 | ECS | Posters on site | ERE2.6

Groundwater mixing and pollution induced by the geothermal system operations in shallow groundwater 

Jaeyeon Kim, Jiyoung Baek, Hye-na Ko, Dugin Kaown, Haerim Oh, and Kang-Kun Lee

Groundwater, one of the environmental tools to achieve carbon neutrality, can be a sustainable thermal resource for a geothermal system. This study aims to investigate the groundwater system characteristics related to the thermal use of groundwater from the view of groundwater mixing and pollution for sustainable water resource management. Investigations have been conducted using hydrogeochemistry, multiple isotopes (O, H, Sr, and Rn), and microbial community structure data, around an open loop groundwater heat pump (GWHP) system. Continuous data of groundwater level and temperature showed the thermal plume propagation characteristics depending on the system operations. Multiple isotopes also revealed the specific characteristics accompanying the thermal use of groundwater. Especially, radon tracer quantitatively showed that the horizontal and vertical mixing occurred along main groundwater flow direction by mixing ratio calculations. In contrast, the clogging effects were observed in the wells located near the main flow direction by PHREEQC geochemical modeling and microbial diversity data, suggesting intensive management in these wells. A lot of time for recovery is needed in these wells. Overall results confirmed that combined analysis of hydrogeochemistry, multiple isotopes, and microbial community structure data can be effectively used to identify the impacts of geothermal system on shallow groundwater and to suggest effective management plan.

How to cite: Kim, J., Baek, J., Ko, H., Kaown, D., Oh, H., and Lee, K.-K.: Groundwater mixing and pollution induced by the geothermal system operations in shallow groundwater, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10285, https://doi.org/10.5194/egusphere-egu23-10285, 2023.

EGU23-12110 | ECS | Orals | ERE2.6

City-wide groundwater temperature profiles reveal underground urban heat islands in Vienna 

Cornelia Steiner, Christian Griebler, Eva Kaminsky, Constanze Englisch, Christine Stumpp, and Gregor Goetzl

Summer periods of warm weather become longer and hotter causing “Urban Heat Islands” in large cities. Rising temperatures do not stop at the surface, but migrate into the underground, where infrastructure – such as sewage and district heating systems, buildings and shallow geothermal energy systems for cooling – amplifies the increase of groundwater temperatures. In order to be able to quantify this ongoing process and predict future temperature developments, a sound data basis is necessary. As of now, only groundwater temperature measurements have been available for different depth (one-point or multiple depth measurements) and time intervals (varying from two weeks to months) at a limited number of wells within the shallow urban aquifers in Vienna. To increase the spatial information content, the goal of this study was to measure groundwater temperature and level within the urban shallow aquifers of Vienna in two extensive field campaigns for more than 800 wells and to analyze those data statistically

To document the warmest and coldest conditions, measurements took place in one week each in October (2021) and April (2022). In total, groundwater temperatures in 1 m depth intervals and groundwater level were measured at 812 locations. Out of these ones, at 150 wells, water temperature was measured in pumped water. The average value of the profile equals best the pumped groundwater and thus represents the average aquifer temperature. According to our data analysis, the groundwater temperatures in Vienna vary between 6.9 °C and 30.6 °C. The highest temperatures were detected in close proximity to possible heat sources and a rapid drop in temperature with increasing distance could be demonstrated.

Based on the collected data, temperature maps for both measurement dates and for different depth-intervals were derived, and display the underground urban heat islands in Vienna. The temperature maps enable the estimation of the potential for sustainable heating and cooling with groundwater in the capital of Austria.

Together with historic long-term temperature data, trend analyses will be performed to allow a prognosis of thermal changes in the groundwater. The results, together with an extensive analysis of the groundwater chemistry and ecology, will feed into the development of a catalogue of measures for authorities and policymakers. Intention of the included recommendations is to counteract further groundwater warming and to ensure an efficient and sustainable use of groundwater for heating and cooling. The guidelines will therefore not only contribute to cooling the groundwater, but also to decarbonize the heating and cooling supply of Vienna.

How to cite: Steiner, C., Griebler, C., Kaminsky, E., Englisch, C., Stumpp, C., and Goetzl, G.: City-wide groundwater temperature profiles reveal underground urban heat islands in Vienna, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12110, https://doi.org/10.5194/egusphere-egu23-12110, 2023.

EGU23-12148 | ECS | Posters on site | ERE2.6

Investigating the impact of different ground sealing types upon shallow subsurface temperatures 

Nele Hastreiter and Thomas Vienken

The monitoring of soil and groundwater temperatures is usually performed to estimate the environmental and economical sustainability of large scale shallow geothermal installations. The difference between the measured up- and downstream temperatures is mostly attributed to the impact of the shallow geothermal usage. However, especially in densely settled urban areas there are multiple other potential impacts on the subsurface temperature regime. The individual drivers are hard to distinguish and therefore mostly not considered when temperature monitoring data is evaluated.

In the presented study empirical temperature data in varying depths up to three meters has been collected below typical kinds of ground sealing in the urban environment, such as tarmac, different types of gravel and lawn. For that purpose, test sites have been installed artificially at a similar time and location. After a measurement period of 18 months, first results reveal clear effects on the very surface near underground temperatures. In a depth of 5 cm, measured temperatures show differences up to 8 K between different types of ground sealing. Depending on the degree and type of the ground sealing, temperature differences are measurable up to a depth of one meter.

The obtained data advance knowledge to quantify the impacts of different ground sealing types on underground and groundwater temperatures in urban areas. Furthermore, it contributes to a more reliable assessment of temperature monitoring data in the context of shallow geothermal applications as the effect of ground sealing on measured temperatures may be considered.

How to cite: Hastreiter, N. and Vienken, T.: Investigating the impact of different ground sealing types upon shallow subsurface temperatures, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12148, https://doi.org/10.5194/egusphere-egu23-12148, 2023.

In 2013 we started a spatial and temporal high-resolution groundwater temperature monitoring campaign at a residential neighborhood under intensive shallow geothermal energy use in the western outskirts of the city of Cologne, Germany. The monitoring was conducted with the aim to identify effects of the intensive thermal use upon groundwater temperatures. Although individual systems sizes in the neighborhood are small, the installed 47 borehole heat exchanger systems sum up to a total borehole heat exchanger length of 11,009 m within a confined area of 0,12 km2 to satisfy, together with three open systems, a total heat demand of 506 kW.

With almost ten years of groundwater temperature monitoring we created a valuable data set. Our results show a reduction of overall groundwater temperatures when comparing upstream and downstream groundwater temperatures during the first years of geothermal operation as an effect of the intensive use of shallow geothermal energy for heating and warm water provision. However, monitoring results depend on the measurement location in our study and it is known that urban subsurface and groundwater temperatures are influenced by several factors. In this contribution, the monitoring concept, results as well as pitfalls of the monitoring campaign are illustrated on our way to untangle urban groundwater temperature changes as a response to the intensive shallow geothermal energy use.

How to cite: Vienken, T.: Ten years of groundwater temperature monitoring at a residential neighborhood under intensive shallow geothermal energy use – insights and lessons learned, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13777, https://doi.org/10.5194/egusphere-egu23-13777, 2023.

EGU23-15158 | ECS | Posters on site | ERE2.6

The key to previous hydrogeological knowledge when determining the best solution in shallow geothermal systems. The case of a karstic aquifer in the city of Girona (Catalonia, NE Spain). 

Ignasi Herms, Georgina Arnó, Marta Picó, Jordi Ferrer, Victor Camps, and Montse Colomer

The European energy market must move quickly to achieve the decarbonization objectives of the economy in 2030-2050, including the domestic and tertiary sectors. In this context, the market for Surface Geothermal Energy (SGE) is growing rapidly due to its applicability in almost any geological and climatic conditions. The area of city of Girona (Catalonia, NE of Spain), is one of the urban areas in Catalonia where the SGE is progressing more rapidly, but is mainly focused on closed-loop (CL) geothermal heat pump systems despite the existing potential in the area for open-loop systems (OL). The urban area of Girona sits on Paleozoic rocks followed by Paleogene series with limestones, sandstones, and marls, configuring a Neogene basin full filled by continental alluvial deposits and Quaternary fluvial sediments, whose aquifers are being mainly used for water supply. Within the Paleogene series, there is the fractured and karstified Girona limestone aquifer (GLA). These materials outcrop in the upper part of the city and dip to the West, positioning themselves below the Neogene basin. The groundwater temperature in the karst aquifer ranges between 14ºC and 15ºC and the average annual temperature in the urban area of Girona is 14.7ºC. This contribution will present a case of a shallow geothermal installation for heating and cooling spaces for a private leisure building with a demand of 33 kWt whose initial solution was proposed with a classical CL system with about 7 BHE 100m depth. The initial project was carried out without conducting any prior hydrogeological assessment or conducting any preliminary drilling investigation to execute a TRT which could have been useful in verifying the issues that were later encountered. The implementation of the drilling campaign during works made it possible to verify the difficulty of drilling the fractured and karstic limestone aquifer and cementing its annulus for the installation of the geothermal single-U probes. The emergency solution taken directly on site - and indeed the most suitable, economical, and efficient solution considering the hydrogeological settings of the site- was to drastically change the chosen solution (CL) for an OL system and drill groundwater wells. Finally, a triplet of wells 20, 30, and 70m deep was executed (two injection and one production well) and a water well test was done and interpreted to acquire the corresponding permits. The case shows that having prior hydrogeological knowledge is essential when choosing the best solution for the client.

How to cite: Herms, I., Arnó, G., Picó, M., Ferrer, J., Camps, V., and Colomer, M.: The key to previous hydrogeological knowledge when determining the best solution in shallow geothermal systems. The case of a karstic aquifer in the city of Girona (Catalonia, NE Spain)., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15158, https://doi.org/10.5194/egusphere-egu23-15158, 2023.

EGU23-15422 | ECS | Posters on site | ERE2.6

A surrogate model to investigate the geothermal potential with variable groundwater flow velocity 

Alberto Previati, Valerio Silvestri, Alberto Presta Asciutto, Paolo Frattini, and Giovanni Crosta

Many cities worldwide extend upon alluvial aquifers which have a great potential for low temperature geothermal installations. Typically, the geothermal potential describes the ability to exchange heat with the subsurface and the relative sustainability.

To estimate the geothermal potential of shallow aquifers many techniques have been adopted such as analytical solutions and numerical methods considering aquifer thermal parameters (e.g. porosity, thermal diffusivity) and the system configuration (e.g. diameter of pipes, borehole thermal resistance). Analytical methods are typically fast and easy to implement in a GIS environment but commonly neglect the effects of groundwater advection on heat transfer mechanisms. On the other hand, physically based numerical methods can handle conductive and advective transport and complex 3D geometries but have the limitation of domain size/resolution that makes modeling unfeasible at scales greater than city districts or cities.

Hence, a new solution based on a surrogate model is presented to estimate the geothermal potential of aquifers at large scale covering a great variability of Darcy flow velocity. The model is based on the response of a synthetic transient-state 3D FEM model reproducing the infinite line source (ILS) configuration. The simulated thermal perturbation over a representative volume at different time stages was then used to calculate the thermal resistance of the aquifer and the corresponding (energy replenishment) potential combining the most relevant variables that affect the heat transport in porous media: thermal conductivity, specific heat capacity, saturation, porosity and flow velocity.

Then, a machine learning regression-based surrogate model was generated by fitting the calculated response (thermal potential) for all possible combinations of input variables. The proposed model well replicates the ASHRAE analytical solution which is based on the ILS method for no groundwater flow, and goes beyond including the effects of thermal transport by groundwater.

Finally, the model response was implemented in a GIS to obtain large scale geothermal potential maps in areas with highly variable groundwater flow velocity (between 10-5 to 10 m/d) highlighting an expected increase of the geothermal potential due to the advective transport. Field experiments are necessary to verify the numerical findings aiming to reconsider the commonly adopted temperature delta thresholds in areas where the energy replenishment potential is high due to groundwater advection.

How to cite: Previati, A., Silvestri, V., Presta Asciutto, A., Frattini, P., and Crosta, G.: A surrogate model to investigate the geothermal potential with variable groundwater flow velocity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15422, https://doi.org/10.5194/egusphere-egu23-15422, 2023.

EGU23-16094 | ECS | Posters on site | ERE2.6

Possible effects of shallow geothermal systems installed at coastal zones 

Rotman Criollo Manjarrez, Víctor Vilarrasa, Alejandro Orfila, and Angels Fernández-Mora

Coastal areas are more densely populated than inland areas and present faster rates of population increase and urbanization. This trend is expected to continue in the coming decades, and thus, the demand of natural resources in coastal areas, such as water and energy resources, increasing the pressure and impact on the environment, superposed to the effects of climate change. Currently, in Europe, the demand for heating in buildings and businesses outnumbers the demand for cooling. However, the latter is gradually catching up due to rising demand for air cooling or refrigeration for industry such as food, technological and medical supplies. The energy required to cool buildings in Europe is expected to increase by more than 70% by 2030, while energy used to heat buildings may decrease by 30% (UE, 2018). Low Temperature Geothermal Energy (LTGE) is most likely the green energy production method for heating and cooling with the highest potential to provide affordable and clean energy and meet the CO2-emissions reduction goals of the Green Deal. Despite advances on LTGE technologies, the efficiency of these systems remains inherently sensitive to changes in hydrodynamics and the media (e.g., changes in the groundwater thermal regime). Groundwater, on the other hand, is the world's largest freshwater resource, and it is especially important in coastal areas because interactions between aquifer systems and sea water may lead to salinization and resource loss. Because geothermal systems and coastal aquifers interact directly, specially at groundwater discharge areas, it is clear that a better understanding of the potential interactions of geothermal systems with current and prospective coastal aquifer processes is essential for their design and foreseeing potential environmental effects. To address these issues, we model variable-density groundwater coupled with heat transport to simulate the long-term evolution of groundwater salinity and aquifer thermal energy discharge. We find that the heating/cooling-induced water density variations affect the seawater intrusion. Understanding the behavior of the groundwater system is required to ensure sustainable water, energy, and coastal ecosystem management.

How to cite: Criollo Manjarrez, R., Vilarrasa, V., Orfila, A., and Fernández-Mora, A.: Possible effects of shallow geothermal systems installed at coastal zones, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16094, https://doi.org/10.5194/egusphere-egu23-16094, 2023.

EGU23-16562 | ECS | Orals | ERE2.6 | Highlight

Experimental Investigation of Groundwater Heat Pump Usage for District Heating and Cooling 

Taha Sezer, Abubakar Kawuwa Sani, Liang Cui, and Rao Martand Singh

Nearly half of Europe’s total energy consumption is dedicated to buildings. Heating and cooling consist of a significant part of this consumption. Groundwater heat pumps (GWHPs) are highly efficient, environmentally friendly and low-carbon technology that can supply heating and cooling to buildings on small to large scale. Northern Gateway Heat Network is an ongoing project based on GWHP, located in Colchester, UK. The planned project will probably be the largest GWHP system using the confined chalk aquifer to date. It will provide district heating and domestic hot water to healthcare buildings, around 300 dwellings, and offices. The system is designed as part-load to cover 75% of the annual heating demand of the planned development with an 800 kW output heat pump which will benefit from the open-loop groundwater extracted at around 12.5°C.

A laboratory-scale sandbox model having external dimensions of 1.178 m × 0.721 m × 0.715 m (L × W × H) with two acrylic tubes acting as injection and abstraction wells was built to investigate the impact of GWHP operation on the system performance and sustainability. The setup was designed to perform different groundwater flow rates by changing the water levels in the hydraulic head tanks on the left and right sides of the sandbox. Several experiments were conducted considering different scenarios: heating, cooling, heating and cooling, and thermal energy storage to examine their impact on thermal plume development and system performance. The study also aims at investigating the effects of groundwater flow velocity, injection and abstraction rates on thermal plume development.

The experimental results show that the thermal plume reaches the abstraction well in each scenario, causing a change in the abstraction temperature. This phenomenon, called thermal recycling, reduces the thermal energy abstraction from the groundwater. The results also illustrate that groundwater flow velocity, injection, and abstraction rates significantly impact thermal plume development. Higher injection and abstraction rates create a larger thermal plume. However, groundwater flow prevents heat development around the well by dispersing the heat in the groundwater flow direction. The results show that it is important to consider groundwater flow velocity, injection and abstraction rate when designing a GWHP system. The distance between injection and abstraction wells is another significant parameter that should be carefully considered. However, it could not be investigated in the current study as the sandbox model was not suitable for changing the distance between injection and abstraction well. Further studies need to be carried out using large-scale field test and/or numerical simulations.

How to cite: Sezer, T., Sani, A. K., Cui, L., and Singh, R. M.: Experimental Investigation of Groundwater Heat Pump Usage for District Heating and Cooling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16562, https://doi.org/10.5194/egusphere-egu23-16562, 2023.

EGU23-17433 | ECS | Orals | ERE2.6

Thermohydrochemical Model to Identify the Impact of Bleed Flow on Calcite Scaling in a Standing Column Well 

Léo Cerclet, Benoît Courcelles, and Philippe Pasquier

The interest towards standing column well (SCW) is increasing due to their higher thermal efficiency and a lower initial construction cost compared to conventional vertical ground heat exchangers. The SCW pumps and reinjects the groundwater inside the same well. They are usually coupled with an injected well to discharge a portion of the pumped groundwater, an operation called “bleed”, to increase punctually the thermal capacity of the system. Since groundwater is the heat carrier fluid, clogging issues can develop if detrimental conditions are locally present. The most common issue for hard water is calcite scaling. The impact of SCW on calcite precipitation had already been studied with a thermohydrochemical model and field experiments. However, it still lacks a reactive thermohydrochemical model calibrated with field acquired data. Once calibrated, this model could help defining the best strategy to avoid calcite precipitation.
A full-scale SCW was operated with a geothermal mobile laboratory for 70 consecutive days. A fractured zone intersects the SCW close to the surface. The operation corresponded to a heat injection with different flow rate sequences. In addition, a groundwater treatment unit installed in the laboratory was used to test different treatment sequences. During this experiment, 20 groundwater samples were collected and analyzed. Those analyses focused on the physico-chemical parameters and the major ions. A reactive thermohydrochermical model was developed in the Comsol Multiphysics environment. This model includes a complex geometry, groundwater flow, heat transfer, and reactive solute transport. The reactive solute transport is composed of two parts; the transport and kinetics model for three primary species and the chemical equilibrium of nine secondary species of calcite reaction. The calibration is achieved by imposing operational parameters as input variables for hydraulic and thermal model as well as the initial concentration.
The calibration identified the presence of CO2 degassing. The parameter with more influence on ion calcium concentration is bleed flow. In fact, bleed operation generates a groundwater flow of native groundwater toward the SCW. During this operation, the fracture contributed up to 33 % of the total calcium flux coming to the SCW. This flux is a convective flux. The concentration of total calcium transported by the fracture is closed to the initial concentration. As a consequence, the ion calcium concentration stabilized near the initial state. Thus, the groundwater treatment performance is minimized. The saturated index of the calcite is above zero. On the opposite side, when bleed is not activated, the groundwater is recycled is the SCW. As a results, the treatment unit is responsible of the observed decreases of the ion calcium concentration. The saturated index decreases below zero after five days. Also, when the total calcium concentration decreases in the SCW, a diffusive flux emerged into the fracture.
In conclusion, this study highlights the alteration of the solute transport as a function of the bleed operation. The type of flux depends on bleed and the treatment. In addition, the treatment of groundwater is unnecessary when bleed is activated.

How to cite: Cerclet, L., Courcelles, B., and Pasquier, P.: Thermohydrochemical Model to Identify the Impact of Bleed Flow on Calcite Scaling in a Standing Column Well, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17433, https://doi.org/10.5194/egusphere-egu23-17433, 2023.

Accurate ocean data (i.e., tide, current velocity and direction, wave) are essential for numerous environmental studies: 1) development of marine renewable energy (e.g., maximize the efficiency of energy conversion); 2) aquaculture (e.g., offshore development); 3) anthropic pollution (e.g., plastic/pollutant dispersal); and 4) ecology (e.g., spread of invasive species).

The exponential increase of computational power has made numerical models, such as Eularian hydrodynamic models and Lagrangian particle tracking models (PTM) useful tools to characterize physical oceanographic parameters. However, methods to validate PTMs appear less developed due the complexity of biophysical process interactions; for example, uncertainty remains on the impact of wind on surface currents and how the effects of wind are propagated through the water column

Here, we use a novel set of data representing the travel of drifters in the Irish Sea during two consecutive years (summer 2021 and 2022). The experiment aim is to reduce the near surface flow uncertainty influencing particle dispersal. Data were collecting using a range of drifters released in coastal and offshore locations of a tidally dominate shelf-sea (Irish Sea): 1) variation of drogue depth between 1m and 5m; 2) variation of period from tidal cycles to spring-neap cycles; and 3) some with reduced “windage” designs (no drogue and minimal exposure above surface).

Preliminary results show the importance of wind driven current between the surface and 5 m depth, which should be take into account when considering the development of PTM. Furthermore, we find some scales of oceanographic processes that affect transport, such as turbulent eddies and waves, were not resolved - and yet our predictions broadly matched observations.

How to cite: Demmer, J. and Neill, S.: Characterization of surface flow using Lagrangian drifter for particle tracking model applications., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2296, https://doi.org/10.5194/egusphere-egu23-2296, 2023.

EGU23-2849 | Posters on site | ERE2.7

Site characterization of META – the Marine Energy Test Area in Wales, UK 

Simon Neill, Iain Fairley, Saul Young, Tom Hill, Nicholas King, Michael Roberts, Matthew Lewis, Martin Austin, Chris Unsworth, Dominic Reeve, and Ian Masters

With lack of convergence on any single wave or tidal technology, test centres have a unique role in the marine renewable energy industry. Test centres facilitate real testing at sea for devices and components at various TRLs (Technology Readiness Level), reducing the time, cost, and risks faced by marine energy developers. META (Marine Energy Test Area) is a £2.7M project managed by Marine Energy Wales (MEW), consisting of eight test areas in the Milford Haven Waterway and surrounding waters (Pembrokeshire, Wales). Although various datasets have been collected from the META test areas over the last decade, and some aspects of these data have been published in various reports, the data has not been gathered together, systematically analyzed and critically assessed - the aim of this presentation. Here, the various META datasets are described and interpreted, including multibeam, ADCP (acoustic Doppler current profiler), and wave buoy data. We report the key parameters of relevance to testing at META, including bathymetry, the nature and magnitude of the tidal currents, turbulence, and wave climates. We make recommendations on future priorities for data collection at META, and discuss the future of the test areas, including expansion into floating wind and other evolving marine energy technologies.

How to cite: Neill, S., Fairley, I., Young, S., Hill, T., King, N., Roberts, M., Lewis, M., Austin, M., Unsworth, C., Reeve, D., and Masters, I.: Site characterization of META – the Marine Energy Test Area in Wales, UK, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2849, https://doi.org/10.5194/egusphere-egu23-2849, 2023.

EGU23-7277 | ECS | Orals | ERE2.7

Comparison Of a Floating and a Bottom Fixed Tidal Turbine in a Coastal Marine Environment 

Jack Lewis, Simon Neill, and Salim Poovadiyil

The predictability and opportunity to provide baseload power has made tidal energy one of the most attractive marine renewable energy resources to help fight anthropogenic climate change. This has led to extensive research regarding the overall resource and methods of extraction. However, with differing designs found in today’s tidal turbine market, it is clear that there remains an ongoing debate as to where a tidal turbine should sit within the water column. In this study, a floating turbine and bottom mounted turbine, both based on current designs found in the market, were analysed over a tidal cycle in a 3D hydrodynamic model of the Morlais tidal test zone. The model was validated from ADCP measurements from the same area and recorded over the same tidal cycle. The aim was to establish the most efficient design and its effect on the surrounding water column. The results showed significant differences in the near-field effects of each turbine, but negligible effects were found further afield. Over the established tidal cycle, the floating turbine was found to be more efficient.

How to cite: Lewis, J., Neill, S., and Poovadiyil, S.: Comparison Of a Floating and a Bottom Fixed Tidal Turbine in a Coastal Marine Environment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7277, https://doi.org/10.5194/egusphere-egu23-7277, 2023.

This study analyzes the nonhydrostatic wake turbulence induced by offshore wind turbine foundations and provides its parameterization needed by regional ocean models. Currently, offshore wind farms are rapidly expanding worldwide. They change critical marine properties such as density stratification and substance dispersion. Therefore, we urgently need to predict their environmental impacts to avoid catastrophic side-effects and to optimize their benefits. Such prediction can be made by regional ocean simulation if the parameterization of the wake turbulence is provided, typically in the form of eddy diffusivity and eddy viscosity. However, accurate values of these parameters are currently unknown. Therefore, we aim to determine state-of-the-art values of these parameters using large-eddy simulation of nonhydrostatic turbulence induced by turbine foundations. In particular, here, we parameterize the turbulence induced by monopiles in tidal currents.

How to cite: Suzuki, N. and Carpenter, J.: Eddy diffusivity and viscosity due to offshore wind turbine monopile foundations in tidal currents, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8817, https://doi.org/10.5194/egusphere-egu23-8817, 2023.

The whole world is urgently looking for alternative renewable energy resources to power its future economy with less carbon footprint. As one of the world’s largest energy consumers and CO2 emitters, China is making all efforts to decarbonize its power systems (‘carbon neutrality by 2060’), with special attention to offshore wind power. However, the potential of offshore wind power generation and emissions mitigation is largely unknown, and the contribution to regional carbon neutrality needs to be further clarified. Here, we estimate the offshore wind resource, its generation potential, and the reduction of CO2 emissions from offshore wind power to replace coal-fired power generation. We find that the abundant offshore wind energy resources in China can potentially generate enough electricity to fully power the country. However, current utilization of offshore wind energy is relatively limited, supplying less than 1% of local electricity needs. With the development of offshore wind farms, this share could be over 20 times higher in 2050 than that at present. The total emissions reduction would increase from 11.9 Tg CO2-eq yr–1 in 2019 to 294.3 Tg CO2-eq yr–1 in 2050 because of reduced coal use, significantly contributing to emissions mitigation along the coastal provinces. Our results highlight the important role of offshore wind power in upgrading the regional energy system and achieving carbon neutrality of China, and it will also give imputes to a cleaner electricity system worldwide. Future studies are encouraged to further explore the feasibility of offshore wind farm construction.

How to cite: Deng, X. and Qin, Z.: Offshore wind power in China contributing to regional power system upgrade and carbon neutrality, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10609, https://doi.org/10.5194/egusphere-egu23-10609, 2023.

EGU23-11321 | Posters on site | ERE2.7

Exploring the Biological, Chemical, and Physical Properties of Seawater of the Jordanian Gulf of Aqaba for Desalination Purposes 

Tariq Al-Najjar, Raid Al-Jawasreh, Ma'in Al-Khawaldeh, Ayman Hammoudeh, Nirajan Dhakal, Wissam Hayek, Maria Kennedy, and Mohammad Wahsha

This scientific work aims to monitor the quality of the Gulf of Aqaba seawater in terms of locations and depths to determine their suitability for desalination purposes. Accordingly, various parameters were measured within the selected coastal and offshore sites at several depths (5, 25, 75, and 125 meters). Parameters included temperatures, pH, salinity, dissolved oxygen, chlorophyll-a, nutrients (ammonium, nitrate, nitrite, and phosphate), Silt Density Index (SDI15), Modified Fouling Index (MFI0.45), and Adenosine Triphosphate (ATP). The sampling site (29°27'31.9"N 34°58'10.0"E) with an average depth of about 400 meters. Seawater samples were collected in Niskin bottles using the MSS research vessel equipped with oceanographic equipment. Temperature, salinity, dissolved oxygen, pH, and conductivity were recorded using the Conductivity, Temperature, and Depth meter (CTD). The maximum SDI15 value was registered in May with a value of 6.3 %/min at a depth of 125 m, while the lowest recorded value was 4.4 %/min at the surface water. Furthermore, the lowest MFI0.45 was reported at a depth of 75 m during February, and it was 0.5 s/L2, while the highest was 9.4 s/L2 at the surface seawater. The preliminary results of the seawater ATP analysis showed that the R2 of the regression is relatively high in the case of SDI15, temperature, depth, and MFI0.45 as 0.792, 0.854, 0.871, and 0.876, respectively. This work is a fruitful collaboration between the MSS (Jordan) and the IHE Delft Institute for Water Education (The Netherlands), in which SDI, MFI, and ATP seawater parameters have been utilized for the first time in the Gulf of Aqaba.

Keywords: Desalination; ATP, Gulf of Aqaba, MFI, SDI

How to cite: Al-Najjar, T., Al-Jawasreh, R., Al-Khawaldeh, M., Hammoudeh, A., Dhakal, N., Hayek, W., Kennedy, M., and Wahsha, M.: Exploring the Biological, Chemical, and Physical Properties of Seawater of the Jordanian Gulf of Aqaba for Desalination Purposes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11321, https://doi.org/10.5194/egusphere-egu23-11321, 2023.

EGU23-12169 | ECS | Orals | ERE2.7

Regional impacts of offshore wind farms on the North Sea hydrodynamics 

Nils Christiansen, Ute Daewel, Bughsin' Djath, Jeffrey Carpenter, Nobuhiro Suzuki, and Corinna Schrum

Offshore wind energy is essential for expanding renewable energy generation and reducing global greenhouse gas emissions. However, as offshore wind turbines form new elements in the marine environment, the offshore wind infrastructure has implications for the physics of the atmosphere and ocean. In this study, we demonstrate the effects of surface wind speed reduction and structure-induced mixing, and illustrate the consequences for ocean dynamics in the southern North Sea. Using unstructured grid modeling, we present simplified parameterizations to account for wind speed reduction due to offshore wind farms and the underwater structure drag by offshore wind turbine foundations in hydrodynamic models. The simulations cover the seasonal cycle of the summer stratification, while taking into account the recent state of European offshore wind development in the southern North Sea. The modeling shows that offshore wind farm effects cause large-scale structural changes in ocean physics, systematically affecting the North Sea hydrodynamics. The wake effects at offshore wind farms lead to spatial redistributions of horizontal currents and, in particular, affect the seasonal stratification development on regional scales. Although these perturbations are on the order of natural variability, changes in regional stratification suggest potential consequences for biogeochemical processes and marine ecosystem dynamics. With our results, we provide new insights into the adaptation of coastal seas to offshore wind farm effects and raise awareness for potential changes in the future coastal ocean and the southern North Sea.

How to cite: Christiansen, N., Daewel, U., Djath, B., Carpenter, J., Suzuki, N., and Schrum, C.: Regional impacts of offshore wind farms on the North Sea hydrodynamics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12169, https://doi.org/10.5194/egusphere-egu23-12169, 2023.

EGU23-13905 | Orals | ERE2.7

Wave Power in Lanzarote: Spatiotemporal Variability, Wind Co-location and Non-Physics based Modelling 

David Christie, Simon Neill, and Peter Arnold

The Canary Islands in the eastern North Atlantic has an abundant and diverse renewable energy resource but currently generates much of its electricity from imported diesel, at significant financial and environmental cost.  To address this, the government and electricity supplier are investing heavily in infrastructure to transform the islands’ energy mix to incorporate offshore wind and wave power. 

Economically and technically feasible offshore wave energy projects rely on understanding the regional distribution of wave properties (e.g. to optimize site selection), and how the wave power varies at inter- and intra-annual timescales.  We have constructed an 11-year wave hindcast model for a potential wave energy site at an energetic location in the north-west coast of Lanzarote, one of the largest of the Canary Islands, to investigate the spatial and temporal distribution of wave power. 

Due to a lack of a continental shelf, wave power is homogeneous until a few km from the coastline, and then begins to vary rapidly in space.  Temporal variation is relatively low due to the latitude.  The wave resource is heavily dominated by swell, with uninterrupted fetch across the Atlantic, and largely uncorrelated with local wind.  This makes co-location of wind and wave energy arrays particularly attractive from the perspective of reducing resource variability, as well as the other practical and financial benefits of sharing a grid location with more established offshore wind technology.

Finally, we demonstrate and validate a simple non-physics based process for extending the output timeseries beyond the hindcast duration, by correlating with parameters from global datasets.  This method also allows the possibility of power forecasting based on global operational models.

How to cite: Christie, D., Neill, S., and Arnold, P.: Wave Power in Lanzarote: Spatiotemporal Variability, Wind Co-location and Non-Physics based Modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13905, https://doi.org/10.5194/egusphere-egu23-13905, 2023.

EGU23-14622 | Orals | ERE2.7

Enhanced mixing by floating wind farms in stratified shelf seas 

Ben Lincoln and Tom Rippeth

The drive to achieve net zero carbon has motivated the development of offshore wind into deeper waters further from shore. The relatively weak tidal currents and deep water of future development sites means that infrastructure will, for the first time, be deployed at scale in seasonally stratified waters.   Current designs for floating turbines have sub-structures which penetrate this stratification.  Flow past such substructures generates turbulent wakes which can regionally enhance the very low levels of internal mixing observed in the seasonal thermocline. 

These low natural mixing rates drive nutrient fluxes which sustain phytoplankton growth at the subsurface chlorophyl maximum through the summer months and are responsible for 50% of the primary production in shelf seas.  Since this production supports the marine food web, changes to the physical drivers will fundamentally impact the marine food web.  Therefore, an anthropogenic source of turbulent mixing at the seasonal thermocline, has the potential to cause fundamental biogeochemical changes, impacting ecosystems, and fisheries in shelf seas. 

We present new measurements of strongly elevated turbulence within wakes at a shallow water wind farm.  Strongly enhanced mixing is observed in the wake, and across the wider wind farm area and is associated with reduced stratification.    These observations and our estimates for deeper water wakes suggest that mixing from these structures can be significant, and further research is essential to quantify the impact of this new source of anthropogenic mixing.

How to cite: Lincoln, B. and Rippeth, T.: Enhanced mixing by floating wind farms in stratified shelf seas, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14622, https://doi.org/10.5194/egusphere-egu23-14622, 2023.

EGU23-15848 | Orals | ERE2.7

Surrogate wave modelling to improve operational wave data for offshore wind farms 

Ian Ashton, Jiaxin Chen, Edward Steele, and Ajit Pillai

The continued expansion of offshore wind as a global energy technology represents a significant expansion of infrastructure into a range of coastal and oceanic regions. Effective design, operation and understanding physical impacts of turbines benefit from a detailed understanding of the wave conditions. In order to cover the spatial extent of offshore wind farms and to ensure high quality data, some combination of in-situ measurements and phase averaging wave modelling are commonly applied. These are used for monitoring current conditions and for short term forecasts that govern crucial operational decisions. Inaccuracies in this process lead to vessels missing suitable conditions to carry out an operation, or operations being aborted due to unsafe conditions. Both of these outcomes, cost money or affect safety.

This work reviews recent progress in using machine learning to develop surrogate wave modelling that can offer real-time spatial wave data leveraging a combination of in-situ measurements and model hindcasts, but without relying on continuous processing from traditional wave models. The outcomes show an improvement in accuracy of real-time wave predictions when compared to regional wave modelling, available at a fraction of the computational cost. This highlights the potential of this approach to change how wave data is provided for operational purposes, with immediate potential for reduced costs and improved safety for vessels working at offshore wind farms. The results also highlight the ongoing potential for research and development of surrogate models as part of the future of numerical wave modelling.

How to cite: Ashton, I., Chen, J., Steele, E., and Pillai, A.: Surrogate wave modelling to improve operational wave data for offshore wind farms, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15848, https://doi.org/10.5194/egusphere-egu23-15848, 2023.

EGU23-16285 | Orals | ERE2.7

Field Investigations of Scour Around Scaled Piles in a Region of Wave Breaking 

Thiruvenkatasamy Kannapiran and Simon Neill

Ocean renewable energy has strong potential for substituting power plants that rely on the combustion of fossil fuels. Due to maturity, offshore wind farms  are one of the most promising forms of ocean renewable energy. There are several windfarms around the world located in nearshore/beach regions (e.g. Bangui Wind Farm, Philippines). Scour around the foundation of nearshore windfarm structures is one of the important technical aspects to be addressed. In this study, field  investigations on the development of scour around scaled model piles  are carried out in two regions of wave breaking, viz.,  i) Uthandi beach, South Chennai, India, open coast having no structures and (ii) Muttukadu beach, South Chennai, India, which is 8 km south of Uthandi beach, having two breakwaters at Muttkadu lake mouth with eight groins in varying lengths with spacing of 50-200m.  Field investigations show rapid increases of the scour depth during swash due to wave uprush around piles and the scour depth reduces significantly during back wash. The field measurements on scour depth (S) around piles of various diameters (D) are well matching with previous published results of scour analysis (Sumer et al..2001).  The relative scour depth (S/D) increases with increase of upstream water run up heights, flow velocities, Froude number and pile positions relating to the location of wave breaking. The comparison of observed scour depths around piles in plunging and spilling wave breaker region indicates that the relative scour depth in plunging wave breaker is higher by around a factor of 1.3 times than that of the scour depth observed in the spilling breaker region.  The present study indicates that, to determine the foundation design depth of the piles for construction of pile supported structure in the region of wave breaking or in the surf zone, the scour depth must be estimated by considering additional depth variation on the beach profile for different monsoon season.  It is observed that the maximum relative scour depth (Smax / D) and width of scour hole are reduced significantly about 50% to 75% with presence of cotton cloths around piles.  However, for a full-scale wind turbine, a suitable geotextile material should be used. This presentation details the various aspects of hydrodynamic field measurements on scaled pile models, which serve as design parameters for designing the pile supported coastal structures including wind energy farms in nearshore regions.

 

Key Words:  Ocean Renewable Energy, near offshore wind farms, hydrodynamics, scour measurements, swash region, offshore piles

 

 

 

Reference:

  • Mohamed Rajab. P.(2019), Hydrodynamic Analysis of Scour Around Offshore Piles.

             Ph.D. Thesis., AMET University, India.

 

  • Sumer, B.M., Whitehouse, R.J.S. and Tørum, A.,(2001). Scour around coastal structures: a summary of recent research. Coastal Engineering, Vol.44:153-190.

 

 

How to cite: Kannapiran, T. and Neill, S.: Field Investigations of Scour Around Scaled Piles in a Region of Wave Breaking, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16285, https://doi.org/10.5194/egusphere-egu23-16285, 2023.

EGU23-17174 | ECS | Orals | ERE2.7

The influence of open boundary location on tidal lagoon modelling 

Bin Guo, Reza Ahmadian, and Roger Falconer

The Bristol Channel and Severn Estuary comprise the area most thoroughly investigated for tidal lagoons development, due to its second largest tidal range in the world and the high demand for clean electricity in the surrounding area. Accurate hydrodynamic modelling of tidal lagoons is a solid foundation for predicting potential electricity generation and environmental impact assessment. However, it is reported that in correct selection of an open boundary may amplify any disturbance associated with the tidal lagoons by affecting the resonant modes. Thus a model that simply held the identical open boundary condition for pre- and post-lagoons conditions may contain inaccuracies in the electricity generation and the impacts on the hydrodynamics of the region.

To investigate the influence of open boundary location on tidal lagoon modelling, the West Somerset Lagoon (WSL) was simulated using different hydrodynamic models with different open boundary locations. Two hydrodynamic models were established using the TELEMAC system, one of which covers the whole Bristol Channel and Severn Estuary (SEBC) as the most prior research used. Another one is a Continental Shelf (CS) model, which was centred on the Bristol Channel, and has its open boundary extended beyond the Continental Shelf. Both SEBC and CS models were run for pre- and post-WSL, to achieve the power output of WSL and the hydrodynamic impact in each model. The WSL was introduced into both hydrodynamic models using the domain decomposition method, and full momentum conservation was achieved by refining the momentum source terms at the turbine locations.

Although the hydrodynamic influences were generally similar between CS and SEBC models, results showed the influence of WSL on water level extended to the outer Bristol Chanel in the CS model, with over 10 cm decrease of tidal range on the location of the open boundary of SEBC model. However, there was a minor difference in far-field velocities prediction between the two models. The annual energy generation of WSL using the different models showed slight differences, i.e. less than 6%. However, this could also be exacerbated by the fact that similar operation was used in both scenarios.. This study concludes that  SEBC could be considered as a suitable model for early-stage studies and preliminary environmental impact modelling due to lower computational and set up time requirements. However, for later stages of the TRS design, such as power prediction for accurate revenue assessment and business case development, then a more precise open boundary condition is expected to be needed, either by extending the model domain to the Continental Shelf or theoretically modifying the open boundary characteristics.

How to cite: Guo, B., Ahmadian, R., and Falconer, R.: The influence of open boundary location on tidal lagoon modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17174, https://doi.org/10.5194/egusphere-egu23-17174, 2023.

Introduction

Modelling potential sites for tidal range energy across the world Neill et al, (2018) estimate a theoretical annual output of 25,880 TWh across 11 countries. The predictability, availability and sustainability of tidal range energy makes it an ideal alternative to fossil fuels for producing baseload power whilst boosting the marine energy industry. Despite the presence of this plentiful resource across many countries, the development of Tidal Range Structures (TRSs) has so far been limited to a handful of locations globally due to technical, financial and environmental concerns. The environmental impacts of TRSs must be addressed in order for this technology to be actualised.

Method

Whilst most research into TRSs deploys numerical modelling, this research adds to the body of knowledge using physical modelling to investigate the hydro-environmental impacts of varying TRS designs. A 1:5000 scale model was built in the Hydro-environmental Research Centre at Cardiff University to test the effects of varying turbine spacing in TRS seawalls as well as comparing the impact of different shaped TRSs with the same area. Acoustic Doppler Current Profilers were used to record velocity, whilst water level data was obtained using pressure cells and fluorescent dye was injected into the TRS and filmed in order to visualise flow.

Results

Results showed that velocity patterns are most influenced by turbine spacing and that tight spacing leads to the greatest impact on baseline conditions due to concentrated wake effects. Wider spacing promotes slower circulation which would enable other activities to take place within TRSs but may lead to issues with water quality if flows are too slow to facilitate effective flushing. Both square and rectangular TRS designs showed similar results within the TRS but a rectangular TRS leads to greater blockage effects outside. This emphasises the need for site specific design to take coastal conditions into account. Overall, turbine spacing has a greater impact on flow conditions than the number of turbines, and central placement with wider spacing was found to be best for maintaining natural conditions.

Acknowledgments

This research is funded as part of the Water Informatics Science and Engineering Centre for Doctoral Training under a grant from the Engineering and Physical Sciences Research Council, grant number EP/L016214/1.

References

Neill, et al. (2018) Tidal range energy resource and optimization – Past perspectives and future challenges. Renewable Energy, 127, 763-778.

How to cite: Leech, C. and Ahmadian, R.: Hydro-environmental Modelling of the Impacts of Turbine Layout and Design Considerations of Tidal Range Schemes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17316, https://doi.org/10.5194/egusphere-egu23-17316, 2023.

EGU23-228 | ECS | Orals | ITS3.2/ERE2.8

Releasing Climate-Sensitive Critical Infrastructure Power Reserves to Improve Grid Resilience 

James Fallon, David Brayshaw, John Methven, Kjeld Jensen, and Louise Krug

Reserve power systems are widely used to provide power to critical infrastructure systems in the event of power outages. The reserve power system may be subject to regulation, typically focussing on operational time, but the energy required for ensuring the supply of reserve power may be highly variable. The energy required may be strongly influenced by prevailing weather conditions and seasonality, for example, heating and cooling requirements have strong temperature sensitivities. Reserve infrastructure can therefore offer potential benefits and services back to the wider electricity system when not in use, supporting a transition to low-carbon technologies such as wind and solar power.

Drawing on the Great Britain (GB) telecommunications systems as an example, we present a methodology and case studies demonstrating that historic meteorological reanalyses can be used to evaluate the capacity of reserve required to maintain the regulated target of 5-days operations. Across three case-study regions with diverse weather-sensitivities, it is shown that infrastructure with cooling-driven electricity demand leads to a peak in the energy consumption during the summer, thus determining both the overall capacity of the reserve required and the availability of 'surplus' capacity (with the surplus appearing during other periods of the year when demand is lower).

Both the total capacity and surplus are further shown to depend strongly on risk preference, with lower risk tolerance leading to substantial cost increase (in terms of capacity required) but also enhanced opportunities for the use of surplus capacity. It is also shown that meteorological forecast information enables greater volumes of surplus capacity to be accessed for a given reserve capacity and risk tolerance.

The availability of surplus capacity is compared to a measure of supply-stress (so-called demand-net-wind) on the wider GB energy network. For infrastructure with cooling-driven demand (typical of most UK telecommunication assets), it is shown that surplus availability peaks during periods of supply-stress, offering greatest potential benefit to the national electricity grid.

How to cite: Fallon, J., Brayshaw, D., Methven, J., Jensen, K., and Krug, L.: Releasing Climate-Sensitive Critical Infrastructure Power Reserves to Improve Grid Resilience, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-228, https://doi.org/10.5194/egusphere-egu23-228, 2023.

The regional energy transition requires a growing share of alternative technologies powered by biomass sources,
for which not all their environmental impacts have been fully understood yet. The UN and the sustainable
development goal (SDG’s) seven encourage a cleaner, safer and modern energy production for all to uphold
environmental and climatic protection. This case study aims to apply the Life Cycle Assessment (LCA) modeling
tool such as the openLCA in assessing wholly (from up to downstream) the environmental, socio-economic and
engineering perspectives of energy transitions.
The Purpose is to analyze the environmental impacts of maize silage production for biogas production in support
of clean and affordable energy. This means, analyzing the supply chain activities from upstream to the downstream
to obtain the impacts on ecosystem and its services. The objectives of this research are to (a) explore different
bioenergy emission and climate change related problems while finding the tradeoffs across various impacts when
maize silage is used as feedstock. (b) To discover current natural gas production technology pathways in Alberta,
the oil exploration province of Canada and compare them with biogas production impacts

The Method applied is the Eco-indicator 99, E, E method, used in analyzing life cycle impact assessment worst-
case scenario of products or services, while comparing the effects with the TRACI & ReCipe methods across board. It provides robust quantitative estimates of GHG emissions, eutrophication, climate impacts, health and land-use impacts of maize silage production for biogas on a regional scale.
From the study’s scientific findings, relevant information on the interconnectedness of bioenergy environmental
impact is generated, which are also useful/applicable for Canada and globally. The result found that the use of high
nitrogen fertilizer (above 120 kg/h) contributes to high eutrophication potentials and drying of the maize silage
has high climate change potentials which proves that biogas production from maize silage is not completely clean
but can be improved
In conclusion. It concludes that biogas systems can decarbonize regional fossil energy grids, drying of the silage
be carried out in summer with biogas and natural gas mix, and supports the moderate use of farm chemicals to
create a balance between bioenergy development and environmental prosperity. the project is significant because
it comprehensively states the need for reduction of excessive emission of greenhouse
gases, land conversion, and nutrient delivery through biogas production and other energy transition activities that
have the potential to increase global warming, damage water and land resources in Alberta which is scarcely available.

KEYWORDS: Energy transition, Environmental impacts, Life cycle impact assessment, Openlca Eco indicator
99, biogas production, Sustainable Environmental.

How to cite: Kalu, A.: Investigating the environmental implications of biogas production pathways using life cycle impact assessment model to support regional energy transitions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1393, https://doi.org/10.5194/egusphere-egu23-1393, 2023.

EGU23-1471 | Posters on site | ITS3.2/ERE2.8

Constraints on the provision of bio-energy from forest biomass in Austria 

Robert Jandl and Andreas Schindlbacher

Limited access to gas has stimulated a new interest in domestically available sources of renewable energy. Currently, about 13% of the Austrian national energy demand (1453.9 PJ) is met from forest biomass and residues from wood product manufactoring. The share of renewable sources of energy is 29.8% (432.9 PJ). Efforts to increase the bioenergy production are in stark contrast to European policies to prevent an icrease of the direct energetic use of primary forest biomass. Austria has a highly efficient timber processing sector and is globally the second largest importer of timber. After a cascade of timber utilization for sawnwood, particle boards and pulp & paper about 50% of the resource is used for energy production. It partially supplies energy for timber processing, and is partially used in biomass power plants. Primary wood that goes directly from the forest into energy production comprises assortments and tree parts that presently cannot be turned into wood products. Yet, particularly in rural areas small-holder foresters extract timber for their regional energy needs. The growing demand for pellets cannot be fully met from the residues of timber processing and relies partially on imported pellets. A further increase of the provision of energy is possible, if (i) the market demands more wood products, and/or (ii) the harvesting rate is increased. Simulations have shown that Austrian forests can sustain several decades of increased harvesting rates, merely because the harvesting rate has been lower than the annual growth, as shown by rising biomass stocks since at least 60 years. Many forests are overdue for thinning because the operational  costs are not covered. Sustainability issues are raised. A slight increase in the production of bioenergy is feasible. Strong increases would deplete resources within only a few decades, and potentially lead to undesired side effects such as nutrient depletion.

How to cite: Jandl, R. and Schindlbacher, A.: Constraints on the provision of bio-energy from forest biomass in Austria, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1471, https://doi.org/10.5194/egusphere-egu23-1471, 2023.

EGU23-3450 | ECS | Orals | ITS3.2/ERE2.8

Potential of Waste to Generate Heat at a Domestic Scale 

Darpan Das, Avtar Matharu, Hannah Briers, and Nicola Carslaw

Rising energy costs and net zero carbon goals mean that the UK needs plentiful and clean energy sources. Current clean energy sources (biomass/ heat pumps) in the country are insufficient to meet residential space heating demands. Further with the advent of higher energy costs, residents are expected to start burning more solid fuel in their homes, as opposed to using gas-based central heating. The UK generates 222.2 million tonnes of waste annually, of which only ~45% is recyclable. The typical calorific value of municipal solid waste and agricultural/garden waste is ~10 MJ/kg and ~20 MJ/kg respectively. Traditionally, waste to energy (WtE) for the circular economy has been associated with waste incineration, but it could be used for household heating. Efficient utilization of waste through different thermochemical transition pathways has been primarily explored at an incineration plant scale (~50 MW heat) and not at a scale of residential heating stove (~5 kW). In the present study, we will use thermogravimetric analyzer- mass spectrometer (TGA-MS) to simulate conditions inside a heating stove. Reaction parameters would include packed bed temperature of 650 °C and heating rate of 10 °C/min for characterisation and assessment of the volatile species evolved during the thermal degradation of several waste materials. Pyrolysis behaviour of some typical household wastes would be analysed through characteristic reaction temperatures and evaluation of mass loss rates. The results from this study can contribute to better evaluation and testing of different waste materials with the aim to know their technical and economic feasibility for heat generation at a small scale.

How to cite: Das, D., Matharu, A., Briers, H., and Carslaw, N.: Potential of Waste to Generate Heat at a Domestic Scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3450, https://doi.org/10.5194/egusphere-egu23-3450, 2023.

The European Union consumes about 60 Exajoule (16.6 Peta Wh) of primary energy per year. In the past years, about 10% of this energy originated from natural gas (CH4). The dramatic developments in Ukraine and the accentuating climate crisis call for an eminent replacement of imported Russian natural gas with climate-neutral alternatives. Consumption reduction, enhanced energy efficiency, electrification, and industrial symbiosis should be prioritized. Being part of the European Economic Area, Iceland annually produces almost 20 TWh of green renewable electricity, using domestic hydropower and geothermal sources. About 80% of Icelandic electricity is exported in the form of energy-intensive products, namely aluminum and silicon. Due to the use of renewable energies, the exported Icelandic products disclose a very low carbon footprint. In regard to EU energy security and climate change targets, the Icelandic example may be used as a demonstration case for other energy products, namely hydrogen and power to X products. It may also be applied to other Arctic regions, namely Greenland, which is also part of the overseas countries and territories of the EU. In this presentation, we will demonstrate the following: i) how to assess the hydropower potential of remote Artic areas (Finger, 2018), ii) how excess hydropower can be used for green hydrogen production and subsequently converted to carbon-neutral CH4 (Cabalzar et al. 2021), iii) compare the life cycle analysis results of hydrogen produced in Iceland and mainland Europe (Vilbergsson et al. 2023) and iv) show the potential of Greenland to become a key player in decarbonizing the EU. While the first three topics have been well described and published (see references below), the potential of renewable energy production in Greenland is currently being investigated by the University of Greenland. One single fjord could yield an electricity production of over 2 GW and an annual yield of around 5 TWh. While exploiting such natural resources should consider local environmental, social, and economic aspects, the production of climate-neutral energy in the arctic can be an essential part of decarbonizing Europe – and be an alternative to other fossil-based foreign energy sources.

References:

Finger D. (2018) The value of satellite retrieved snow cover images to assess water resources and the theoretical hydropower potential in ungauged mountain catchments, Jökull, 68, 47-66. doi.org/10.33799/jokull.2018.68.047

Cabalzar U., Blumer L., Fluri R., Zhang X., Bauer C., Finger D., Bach C., Frank E., Bordenet B., and C. Stahel (2021) Projekt IMPEGA - Import von strombasiertem Gas, Aqua & Gas 6, 40-45, Schweizerischer Verein des Gas- und Wasserfaches

Vilbergsson K., Dillman K., Emami N., Ásbjörnsson E., Heinonen J., and D.C. Finger (in press) Can remote green hydrogen production play a key role in decarbonizing Europe in the future? A cradle-to-gate LCA of hydrogen production in Austria, Belgium, and Iceland, International Journal of Hydrogen Energy, in press

How to cite: Finger, D. C. and Hardenberg, S.: Climate-Neutral Europe: the Role of Renewable Energies in the Arctic to decarbonize Europe and enhance energy independence, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4148, https://doi.org/10.5194/egusphere-egu23-4148, 2023.

EGU23-4975 | Orals | ITS3.2/ERE2.8

Feasibility and Challenges of Adopting Solar Energy for Nearly Zero Energy Buildings: Lessons from Taiwan 

S. Ping Ho, Yaowen Hsu, Yu-Tien Lin, and Chung L. Chen

Promoting and developing Zero Energy Buildings (ZEB) is crucial to achieving the goal of net-zero emissions. Zero Energy Buildings emphasize not only on buildings’ energy efficiency, but also on the transition of buildings’ energy consumption from nonrenewable energy to renewable energy. However, practically, since it is often impossible to achieve the “Zero” energy consumption in a strict sense, the concept of ZEB is implemented as Nearly Zero Energy Buildings (NZEB). Although adopting solar energy to achieve the goal of NZEB is currently one of the most feasible strategies, under what conditions the use solar energy for NZEB is technically feasible and how the building owners are motivated to invest in NZEB are still vague and challenging. As the solar power technology continues to advance and the environmental morality continues to rise in countries and societies, this study takes Taiwan as a case to study how feasible technically and behaviorally the NZEB is and what could be the main challenges.

Through extensive literature review and expert interviews, we analyze and establish the standards for defining the NZEB in Taiwan. Then we categorize the building types and residential energy consumption scenarios in Taiwan and investigate different approaches to installing solar photovoltaic systems. In sum, the two main approaches to installing solar photovoltaic systems are the roof floor installation and the roof trellis installation. The types of buildings to be studied are the terrace houses, the five-story apartments, and the eight-story apartments. To simulate the net energy consumption, firstly, Ladybug Tools is used to simulate the annual power generation of each solar photovoltaic installation in different climatic regions in Taiwan. Secondly, the formula for calculating the photovoltaic power generation is proposed according to the simulation results. Lastly, we analyze whether each installation approach can meet the specifications of NZEB under different energy consumption scenarios and evaluate, accordingly, the technical feasibility of achieving the goal of NZEB.

Based on the simulation, the roof trellis type is shown to generate the most power under the same construction area and to be the most feasible solar photovoltaic installation approach for the residential buildings to achieve NZEB.

We also analyze the economic feasibility of different NZEB scenarios using NPV and IRR methods. It is shown that, except for the eight-story apartments in the northern Taiwan’s climatic region, the simulated NZEB scenarios are economically feasible. Among them, the NPVs of the roof trellis type are lower than other schemes, the investment costs are expected to be recovered in about 13 to 17 years, and the IRR is about 5 to 7% for terrace houses and five-story apartments. To conclude, based on the current/modern solar photovoltaic technologies, NZEB can be well achieved for the residential buildings if the housing owners choose to invest.

Finally, whether the NZEB can be achieved depends on the house owners’ willingness to invest in NZEB, the main challenges of NZEB in Taiwan. We shall develop a consumer behavior model and form policy insights concerning NZEB.

Acknowledgment: Grant number 111-2124-M-002-006 and Grant number 110-2221-E-002-060

How to cite: Ho, S. P., Hsu, Y., Lin, Y.-T., and Chen, C. L.: Feasibility and Challenges of Adopting Solar Energy for Nearly Zero Energy Buildings: Lessons from Taiwan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4975, https://doi.org/10.5194/egusphere-egu23-4975, 2023.

Millions of oil and gas wells are abandoned and orphaned in Canada and the United States. These well sites can be repurposed for wind and solar energy, while the wells access itself can be redeveloped for geothermal energy production. To identify opportunities for repurposing abandoned and orphaned wells and well sites for renewable energy development, we analyze public oil and gas well data from state, provincial, and territorial agencies to estimate the number and geospatial distribution of abandoned and orphaned wells in Canada and the United States. As of March 2022, we identify 4,724 orphaned wells and 420,113 abandoned wells in Canada and identify 123,318 orphaned wells (as of March 2022) and 3,151,700 abandoned wells (as of August 2022) in the United States. Using this dataset, we analyze geographic locations of abandoned and orphaned wells with national maps of renewable energy potential (geothermal, wind, and solar) and land cover/land use in Canada and the United States. We then evaluate how the potential to repurpose wells/well sites vary across Canada and the United States. Due to funding shortfalls, many abandoned and orphaned wells remain unplugged and are negatively impacting the environment and contributing to greenhouse gas emissions. Repurposing wells and well sites can provide an additional funding stream to manage the millions of abandoned and orphaned wells around the world.

How to cite: Boutot, J. and Kang, M.: Potential to convert abandoned and orphaned oil and gas well sites for renewable energy production in Canada and the United States, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7310, https://doi.org/10.5194/egusphere-egu23-7310, 2023.

EGU23-7547 | ECS | Orals | ITS3.2/ERE2.8

The Water, Land, and Carbon Intensity of Electricity Production: The Case of South Africa 

Thomas van Huyssteen, Djiby Thiam, and Sanderine Nonhebel

Electricity production has a significant impact on the Water-Energy-Food (WEF) nexus sectors as it requires substantial amounts of water and land, whilst also being a primary polluter of these resources. In addition, electricity production is a key contributor to global CO2 emissions.  With electricity production predicted to increase by over 50% by 2050, the impact of electricity production on water and land resources, as well as the environment, will need to be significantly reduced This is particularly important in countries facing water, energy, and food scarcity and insecurity such as South Africa. This paper therefore investigates the impact of electricity production on the WEF nexus sectors and environment in South Africa. To do this, this paper conducts a lifecycle assessment of the water footprint (WF), land footprint (LF), and carbon footprint (CF) of electricity production in South Africa, by electricity source, and under key scenarios. The results from the IRP 2030 scenario showed that despite a 63% increase in electricity production targeted from 2018-2030 in South Africa, the water, land, and carbon footprints of electricity production would decrease by 29%, 9%, and 5.5% respectively. Compared to the BAU 2030 scenario, it was shown that the water, land, and carbon footprints would be 55.5%, 42.6%, and 41.5% lower in the IRP 2030 scenario, respectively. Overall, the results show that to reduce the impact of electricity production on the WEF nexus sectors and the environment, integrated resource planning, switching away from fossil fuels, particularly coal, and promoting the use of non-hydro and non-biomass renewables is required.

How to cite: van Huyssteen, T., Thiam, D., and Nonhebel, S.: The Water, Land, and Carbon Intensity of Electricity Production: The Case of South Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7547, https://doi.org/10.5194/egusphere-egu23-7547, 2023.

EGU23-9018 | ECS | Orals | ITS3.2/ERE2.8

Accelerated energy transitions and the Earth system 

Harald Desing

Staying below 1.5°C and returning to 350ppm require much more ambitious and radical actions than currently envisioned. This necessitates different modelling approaches too, transcending current economically optimized equilibrium models. Planetary boundaries need to span the frame for transition modelling, e.g. by setting sustainable limits for renewable energy potentials or incorporating the need to return to 350ppm, which induces negative emissions at a massive scale. Furthermore, building renewable infrastructure needs energy and this feedback loop becomes decisive when accelerating transitions. It also needs materials: speed and pathways of mobilizing materials are pivotal for impacts on planetary boundaries and the energy needed for the transition. Initial modelling with a simple, global system dynamics model suggest that it is still possible energetically to stay below 1.5°C and return to 350ppm this century; however, this requires to keep energy demand and energy storage low.

How to cite: Desing, H.: Accelerated energy transitions and the Earth system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9018, https://doi.org/10.5194/egusphere-egu23-9018, 2023.

Buildings are responsible for a significant proportion of total energy consumption and therefore represent an important target for energy savings. Their consumption is strongly temperature-dependent, as it is dominated by the heating and cooling demand to ensure thermal comfort inside.

To quantify the energy savings of a building over time (for example after renovation or with lowered indoor temperatures), it is necessary to remove the influence of meteorology on energy consumption and determine the part that is independent of weather, i.e. related to the building properties and its use. Current methodologies use daily energy demand proxies (degree-days) with fixed temperature thresholds for heating and cooling. However, hourly energy consumption is increasingly monitored by smart meters, and high-quality meteorological reanalysis data are available globally, giving access to a finer temporal scale on which variations in both outside temperature and building use are expected.

Here we present a case study using 10 years of hourly meteorological data and energy consumption data from a university campus in Germany. We analyze the meteorology-dependent energy consumption including its sub-daily variations. We investigate the differences in energy savings quantification depending on the time step used. The detailed knowledge of energy consumption patterns and their temperature sensitivity that we obtain also provides the basis for identifying potential future energy savings through retrofits and changes in user behavior.

How to cite: Labuhn, I. and Deroubaix, A.: Improving the quantification of building energy savings through temperature-sensitivity analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9187, https://doi.org/10.5194/egusphere-egu23-9187, 2023.

EGU23-10368 | ECS | Posters on site | ITS3.2/ERE2.8

Humankind, Energy and the Climate - A EURO-CORDEX Analysis 

Markus Schlott, Omar El Sayed, Mariia Bilousova, Chen Li, Filippo Guidi, Alexander Kies, and Horst Stöcker

Climate change is going to alter the appearance of planet Earth throughout the century and beyond unprecedentedly. Therefore the United Nations (UN) decided to classify climate action as the 13th Sustainable Development Goal (SDG); right after the fight against poverty, hunger and other emphases. With the Paris Agreement from 2015, the world community finally got through to tackle this crisis in an ambitious step forward, aiming at a global warming rate of well below 2°C. However, it is by far not clear, how this task can be achieved in an economically sensible way; especially with regard to the first twelve SGDs, and, in addition to this, an ever increasing world population with around eleven billion human beings at the end of the century. This dilemma makes clear: future action against climate change must also develop solutions to the social questions from nowadays. But even more: it must be thought in a broader context, regarding energy security, population dynamics, economic transformation processes, as well as the general standard of living.

The presented work is the first part of a study that addresses these questions for Europe by cost-optimizing a sector-coupled network model of its energy system (PyPSA-Eur-Sec), done under two main aspects: first, the impact of climate change on the energy related infrastructure, and second, the role of socio-economic uncertainties in form of boundary conditions. The first is achieved by invoking all energy relevant meteorological weather data variables from the EURO-CORDEX climate projections. The second is based on social and economic projections such as the World Population Prospects from the UN Population Division.

The results from part one are given by an energy-meteorological analysis of the full EURO-CORDEX ensemble, covering three distinct greenhouse gas emission scenarios: RCP2.6, RCP4.5 and RCP8.5. The analysis investigates the power output from wind turbines (sfcWind, rlst), solar panels (hurs, rsds, rsus, tas), and hydro plants (mrro, orog); each time for the EUR-11 domain and at the end of the century in form of a last-year approach. The resulting fields are evaluated in two ways: in comparison to each other, quantifying the uncertainties among the different climate models, and in comparison to today’s climate status quo with respect to the ERA5 reanalysis, quantifying any impact of climate change on the variables and their related power potentials.

How to cite: Schlott, M., El Sayed, O., Bilousova, M., Li, C., Guidi, F., Kies, A., and Stöcker, H.: Humankind, Energy and the Climate - A EURO-CORDEX Analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10368, https://doi.org/10.5194/egusphere-egu23-10368, 2023.

EGU23-11361 | Orals | ITS3.2/ERE2.8 | ERE Division Outstanding Early Career Scientist Award Lecture

The role of the subsurface in the energy transition – (some of) the (scientific) challenges 

Johannes Miocic

The transition towards carbon-free, renewable based energy systems is a central element to limit global warming and is one of the key societal challenges we are currently facing. The subsurface offers many different pieces for the energy transition jigsaw, from renewable energy from geothermal sources to large volumes of pore-space to permanently sequester carbon dioxide. The subsurface also provides several options for storing renewable energy over seasonal timescales, by storing renewable energy surplus converted into hydrogen and compressed air. As the subsurface can be utilized for many different energy related purposes, it becomes clear that it has to be a crucial part of the energy-transition.  However, most subsurface utilization technologies are not yet used on the scale that is needed for a successful energy transition. One reason for this lies in the incomplete understanding of (geological) processes that occur in the subsurface during, and after, the operation of these technologies. Predicting the performance and the potential of subsurface utilisation in the energy transition can also be hampered by limited data availability and the uncertainties associated with sparse datasets. Here, some of the key geoscience challenges that need to be solved for a timely energy transition are presented and some potential solutions are reviewed. The subsurface can, and must, play an important role in tomorrow’s green energy systems!

How to cite: Miocic, J.: The role of the subsurface in the energy transition – (some of) the (scientific) challenges, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11361, https://doi.org/10.5194/egusphere-egu23-11361, 2023.

Increasing renewable energy penetration is essential for achieving carbon neutrality in the electricity system. In this regard, the most promising technologies are wind and PV. The degree of penetration of these technologies in the mix is affected by their capacity factor.

The objective of this study is to determine the sensitivity of the electricity system to changes in the capacity factor of wind and PV, not only uniform changes but also the changes in the low and high wind or PV production conditions. Simulations were performed using EOLES, an investment and dispatch optimization model. This model minimizes the total system cost by satisfying hourly demand, respecting technical and operational constraints, and giving us the optimal electricity system for a given input. This result provides an overview for the decision makers deciding how much capacity to install. In addition, to reflect the realistic situation of the energy system, in which we have already invested in installed capacities, EOLES is used only for dispatch optimization with the pre-fixed installed capacities.

Output variables chosen for sensitivity tests are total system cost and installed capacity of production technologies. Their sensitivity to changes in the average capacity factor was measured using elasticity quantity, which is calculated by dividing the relative change of the chosen output variable by the relative change of the capacity factor average. Uncertainty of capacity factor in the different production conditions of wind and PV was modeled by perturbing a specific quantile of the capacity factor dataset at each test and uniform errors by uniform perturbation of all time steps. Furthermore, perturbations of different magnitudes and signs are included to show the behavior of EOLES concerning the amount of perturbation.

The result shows the EOLES model is more sensitive to change in the capacity factor of the wind and least to PV for both Installed capacities and total system cost; also, it is more sensitive to the perturbation of low-production than high-production conditions. For instance, the elasticity of the installed capacity of PV and wind to perturbation of their capacity factor in low-production conditions is 15 and one, respectively, and it is approximately zero for both PV and wind in high-production conditions.

Optimization of installed capacities and dispatch in response to capacity factor perturbations results in a weak sensitivity of the total system cost (elasticities less than 0.5). On the other hand, optimizing only dispatch leads to having the elasticity of the total system cost as high as 14. Comparing elasticities indicates that installed capacity optimization compensates for the effect of capacity factor perturbation on total system cost. However, fixed installed capacity leads to either having an oversize system in positive or extra usage of expensive reserve technologies in negative perturbations; as a result, the higher elasticity of the total system is expected. Considering the high sensitivity of the low production events of the wind, it is worth improving our modeling of smaller capacity factors, including choosing a wind dataset, a bias correction method, and a power curve.

How to cite: Kadkhodaei, M., Tantet, A., Drobinski, P., and Quirion, P.: Evaluating the sensitivity of the total system cost and installed capacity of technologies of the electricity system to the perturbation of the wind and PV capacity factor, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11901, https://doi.org/10.5194/egusphere-egu23-11901, 2023.

EGU23-11915 | Orals | ITS3.2/ERE2.8

Fertilizers as batteries and regulators in the global Water-Energy-Food equilibrium 

George Kirkmalis, George-Fivos Sargentis, Romanos Ioannidis, David Markantonis, Theano Iliopoulou, Panayiotis Dimitriadis, Nikos Mamasis, and Demetris Koutsoyiannis

Fertilizers and especially Nutrient Nitrogen, are high consumers of energy. At present, the energy crisis has a serious effect in the production of fertilizers. As the world is seeking to smooth the curves of energy production, especially by renewable energy installations, the use of potential energy surplus in fertilizers’ production could be an alternative practice. Fertilizers can be utilized for the cultivation of energy crops or food (which also has an energy equivalent). In this work, we attempt to evaluate the potential of the integration of fertilizers in the energy production both for energy recovery and for the avoidance of possible failures by the deficit of fertilizers in the global Water-Energy-Food equilibrium. 

How to cite: Kirkmalis, G., Sargentis, G.-F., Ioannidis, R., Markantonis, D., Iliopoulou, T., Dimitriadis, P., Mamasis, N., and Koutsoyiannis, D.: Fertilizers as batteries and regulators in the global Water-Energy-Food equilibrium, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11915, https://doi.org/10.5194/egusphere-egu23-11915, 2023.

Often overlooked, citizen-led energy initiatives contribute to the low carbon energy transition in Europe. Under the name of energy communities, these groups have been specifically addressed in two separate EU directives (Directives EU-2018/2001 and EU-2019/944). Their projects have grown to produce, distribute, and consume energy from renewable sources while being governed democratically and benefits accruing locally. Despite this, data collection on the topic and statistical accounting of their impacts have not been undertaken systematically until now. This short documentary film quantifies the aggregate contributions of collective action in pursuit of the sustainable energy transition in Europe, estimating the number of initiatives (10,540), projects (22,830), people involved (2,010,600), installed renewable capacities (7.2-9.9 GW), and investments made (6.2-11.3 billion EUR) for 30 European countries.

The data presented in the video draws on our groundbreaking dataset which is the first systematic data collection to capture the nature and scope of collective citizen-led action in the energy transition for each country in Europe (https://doi.org/10.18710/2CPQHQ). The dataset consists of a broad range of variables to a high degree of granularity, covering both organizations and the individual projects that they manage, e.g., installation of renewable capacities, operation of charging infrastructure for electric vehicles, engagement in energy education and services provision, etc.

The documentary begins with background on energy services and cooperatives, highlighting 10 solutions by citizen action initiatives across Europe addressing various current issues of energy security, sustainability, and the affordable provision of energy services. While many of these initiatives are small in scope, they are of sufficient importance to policymakers as they actively involve people in the transformation. A "Facts & Figures" segment quantifies the aggregate contributions of citizen-led energy initiatives. These aggregate estimates do not suggest that collective action will replace government or commercial action in the short- or medium-term without fundamental alterations to policy and market structures, but the film presents strong evidence for the historical, emerging, and actual importance of citizen-led collective action to the European energy transition. Continued decentralization of energy systems and more stringent decarbonization policies will increase the importance of these actors in the future.

How to cite: Arghandeh Paudler, H. J.: "Power To & By the People": A documentary film on statistical evidence for the contribution of citizen-led initiatives to the energy transition in Europe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14326, https://doi.org/10.5194/egusphere-egu23-14326, 2023.

EGU23-14331 | ECS | Orals | ITS3.2/ERE2.8

A review of key material supply constraints to the future deployment of batteries in energy system modelling 

Tobias Verheugen Hvidsten, Marianne Zeyringer, and Fred Espen Benth

This paper presents a literature review identifying the issues relating to the supply of battery materials most likely to cause constraints. The efforts to decarbonize the electricity and transport sector cause an increasing demand for batteries. Batteries are deployed as energy storage to facilitate high shares of variable renewable energy and in battery electric vehicles. With this rising deployment, the demand for materials utilized in battery technology follow. Lithium, graphite and cobalt are examples of important battery materials expected to experience immense demand growth. The continued access to these materials is essential to decarbonize the electricity and transport sector, which is crucial to meeting the targets of the Paris Agreement.

The increased demand for these materials makes it of importance to consider possible constraints to their availability. This paper investigates issues across disciplines to assess these constraints. Causes to such constraints include: (i) Material scarcity, when a material is utilized to the point where reserves are depleted. (ii) Geopolitical issues, which could cause disruptions in supply of a material if reserves are mainly located in one country or region. (iii) Social issues, such as poor working conditions or the effect of extraction on the local environment and population. The literature review is performed to identify these key issues for the supply of critical materials for battery technology, and identify how each of these might constrain the deployment of batteries in the energy system. The key constraining factor of each battery material is identified, and the degree to which this might constrain the deployment of batteries is assessed.

Energy system models are often used to assess how to transition to future net-zero energy systems.  To better address sustainability as well as to account for the feasibility of the transition, material constraints should be implemented in the energy system model. This could also lead to optimized energy system developments showing greater resilience against the risks associated with these constraints. The work will provide a comprehensive overview of the main limiting factor to the supply of materials critical to batteries, and with that form a basis for the implementation of these constraints in energy system models.

How to cite: Hvidsten, T. V., Zeyringer, M., and Benth, F. E.: A review of key material supply constraints to the future deployment of batteries in energy system modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14331, https://doi.org/10.5194/egusphere-egu23-14331, 2023.

EGU23-14495 | Orals | ITS3.2/ERE2.8

Assessment of geothermal energy resources and in Armenia 

Khachatur Meliksetian, Gevorg Navasardyan, Lilit Sargsyan, Andrey Medvedev, Edmond Grigoryan, Peter LaFemina, Charles Connor, Vassily Lavrushin, Elya Sahakyan, Ivan Savov, and Natasha Toghramadjian

Armenia is a landlocked country in the South Caucasus region, situated between Iran, Georgia, Azerbaijan and Turkey, with population of about 3.0 million. Since Neogene to Quaternary times, the territory of Armenia has been located in a continent-continent collision zone (i.e., collision of the Arabian and Eurasian plates) and exposed to transpressional tectonics resulting in widespread and long-lasting polygenetic and monogenetic volcanic activity.

The studies of spatial density of vents in Armenia (Weller et al., 2018, Sugden et al.  2021) demonstrate that Armenia is one of the densest clusters of Quaternary monogenetic volcanoes on Earth: in total, 516 volcanoes are mapped within the area of  ~30,000  km2. Most of the monogenetic volcano clusters are oriented NW to SE, perpendicular to the major stress direction related to the movement of the Arabian plate from SW to NE.

Several active faults and potentially active and active volcanic systems exist in the country and many historical earthquakes have been recorded. The geology of Armenia with its volcanoes and active faults being potential source of hazards at the same time, has an important potential for geothermal energy, whilst much of Armenia’s current energy production is from imported fossil and nuclear fuel.

It is noteworthy, that hundreds of sources of thermal mineral waters exist in Armenia and most of them are found in close proximity to volcanic systems and active faults. Our preliminary geochemical studies of mineral waters aiming to apply geochemical thermometers to investigate the formation temperature of waters demonstrate several geothermal anomalies in Armenia. This contribution will present unified geological, geophysical, volcanological, geochemical database with selection of promising sites for further studies of geothermal energy potential of Armenia, and some preliminary results of application of ambient noise tomography (ANT) and satellite data.

How to cite: Meliksetian, K., Navasardyan, G., Sargsyan, L., Medvedev, A., Grigoryan, E., LaFemina, P., Connor, C., Lavrushin, V., Sahakyan, E., Savov, I., and Toghramadjian, N.: Assessment of geothermal energy resources and in Armenia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14495, https://doi.org/10.5194/egusphere-egu23-14495, 2023.

EGU23-15481 | ECS | Posters on site | ITS3.2/ERE2.8

The future Pan-European Atlas for Sustainable Geo-Energy Capacities. The #GSEU project. 

Ignasi Herms, Paula Canteli, Elsa Ramalho, Georgina Arnó, Jesús Garcia-Crespo, Joao Carvalho, Montse Colomer, Celestino Garcia de la Noceda, Rita Caldeira, Ignacio Marzán, Cristina de Santiago, Gregor Glotzl, Vit Hladik, Annamaria Nador, Cornelia Steiner, Petr Jirman, and Maayke Koevoets

Through a five-year Coordination and Support Action, the new #GSEU (Geological Service for Europe) project, EuroGeoSurveys, and 48 partner organizations from 36 European countries (including both national and regional Geological Survey Organisations - GSO, and associated partners) will deliver a plan for a sustainable Geological Service for Europe to be implemented beyond the 2027 project end. The project will directly support the vision of European Green Deal, focusing on our Earth and what lies within its subsurface, i.e. water, energy, raw materials, and all areas that require subsurface data and expertise. The GSEU’s key objective is to develop and make permanently available pan-European geological data on the already existing European Geological Data Infrastructure (EGDI) and related information services for the sustainable and safe use of our subsurface and its resources. The project is structured in 9 Working Packages (WP). Its ‘WP3 Geothermal energy & underground storage inventory’ will deliver the named online GIS ‘Pan-European Atlas for Sustainable Geo-Energy Capacities (SGEC)’, a future harmonized and generalized distribution of maps and databases of already known assessed capacity and resource potential, mainly from previous European projects, and supported with additional national and regional information from GSOs, including standardized qualitative and quantitative attributes. This will consider information on geothermal energy resources and subsurface storage capacities for sustainable energy carriers (hydrogen, heat and cold) and sequestration of CO2. This contribution will present the main objectives, methods and expected results with the publication of the future atlas.

How to cite: Herms, I., Canteli, P., Ramalho, E., Arnó, G., Garcia-Crespo, J., Carvalho, J., Colomer, M., Garcia de la Noceda, C., Caldeira, R., Marzán, I., de Santiago, C., Glotzl, G., Hladik, V., Nador, A., Steiner, C., Jirman, P., and Koevoets, M.: The future Pan-European Atlas for Sustainable Geo-Energy Capacities. The #GSEU project., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15481, https://doi.org/10.5194/egusphere-egu23-15481, 2023.

EGU23-17148 | Posters virtual | ITS3.2/ERE2.8

Sustainability impact assessment of urban energy transformation in smart cities 

Dr Ashish Sharma, Satya Narayan Singh, and Vladimir Strezov

The rapid urbanization and urban energy transformation worldwide have surpassed the urban global tipping point and poses serious challenges to the current energy systems and infrastructures in global mega cities. The cities consume about 75% of worldwide energy production and produce 80% of CO2 emissions. It is estimated that nearly 68% of the world’s population will be living in urban areas by 2050 as well as 2.5 billion people will be added to the world’s urban population (UN Department of Economic Social Affairs, 2018). The exponentially increasing urbanization poses environmental threats. This calls for research and development of technologies, sustainability assessment tools and public policy instruments with a strong focus on the energy transformation in mega cities. The knowledge base compiled from such an analysis will help in fast-tracking the transition towards equitable, sustainable, and livable cities. This requires a thorough analysis via life-cycle approach for the structure and the feedback of the cities to the implementation of the sustainable energy transformation pathways. To fill these gaps, the overarching goal of this proposed study is to assess the sustainability (i.e., environmental, economic and social) impacts and air quality benefits of urban energy transformation in future smart cities. This will be accomplished via a systematic review of existing literature for following key objectives, (i) To assess the impact of energy efficiency measures in smart cities planning as well as increasing uptake of renewable energy sources and diversification; (ii) To conduct the sustainability assessment and quantify the environmental benefits (i.e., air pollution reduction) of four specific interventions in smart city transport planning including, electrification, automation, vehicle sharing schemes and micro mobility options. The analysis will follow a life cycle thinking approach ; (iii) To examine the structure and the sensitivities of the cities in response to the sustainable energy transformation via modes such as alternative energy use, deployment of green infrastructure and distribution of decentralized energy systems (e.g., Solar photovoltaic technology and battery technology);  (iv) Further, the necessity and effectiveness of the legislative policies for energy transformation in smart cities planning and governance will be evaluated. This proposed study will provide benchmarks to broaden our knowledge and decision-making capabilities to quantify the energy and resource efficiencies of sustainable energy transformation pathways. It will indirectly contribute towards fulfilling and realizing the Sustainability Developments Goals (SDG’s) put forward by the UN. The findings of this study will be helpful for the city planners, local councils as well as the policy makers for a sustainable urban energy transformation for smart cities planning and implementation. This will help to broaden knowledge of different stakeholders for informed decision-making towards energy options with minimal sustainability impacts and greater energy/resource efficacies.

How to cite: Sharma, D. A., Singh, S. N., and Strezov, V.: Sustainability impact assessment of urban energy transformation in smart cities, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17148, https://doi.org/10.5194/egusphere-egu23-17148, 2023.

Electric vehicles (EVs) have been proposed as a key solution for decarbonizing urban transportation and addressing climate change. As the use of EVs increases in cities worldwide, it may lead to significant transformation in urban development, including changes in the electrical system and people's travel behavior, such as charging preferences and choices of where to live and work. Some questions arise, will the rise of EVs lead to more suburbanization or drive people towards a more compact urban form? Additionally, how can the relationship between EV users' residential locations and new energy infrastructure be best coordinated? A study in the rapidly growing metropolis of Beijing aims to address these questions by combining geo-spatial big data analysis, machine learning, and theories of urban development to understand the relationship between EV users' residential locations and new energy infrastructure. A novel data mining strategy was proposed to identify actual EV users based on location data from smartphones. By analyzing observation data of EV users, the study applies the Gradient Boost Decision Tree model to examine the nonlinear associations between the spatial distribution of EV residents and neighborhood attributes such as employment density, GDP, land use mix, public charging accessibility, building areas, access to public transit, and suburbanization. The results indicate that a higher percentage of EV users prefer to live in areas that are neither too far away from the city center nor too close to it, particularly the threshold effects show that they are concentrated in areas where it has a 10 km distance from the city center. Additionally, the study found that most public charging activities tend to occur within 1.5 km from home, suggesting an optimal threshold for public charging station deployment. The findings of this study can help inform energy management and infrastructure planning at the local, regional, and national levels to promote sustainable urbanization and smarter energy planning in policy-making.

How to cite: Kang, J., Kong, H., and Lin, Z.: Assessing the Effects of Electric Vehicle Adoption on Urban Energy Structure Transition: A Geospatial Machine Learning Study in Beijing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17241, https://doi.org/10.5194/egusphere-egu23-17241, 2023.

ERE3 – Geo-storage

EGU23-323 | ECS | Posters on site | ERE3.1

Monte Carlo modelling of a pulsed neutron capture tool for CO2 saturation estimation in sandstone reservoirs 

Jozsef Gabor Szucs, Attila Galsa, and Laszlo Balazs

One of the key factors for a successful carbon capture and storage (CCS) project, is the ongoing monitoring of the carbon-dioxide injected into the reservoir rocks. Borehole geophysics measurements are invaluable for this process. Due to the evident presence of borehole casing, the number of effective well logging methods is limited.  This means, that nuclear measurements play a highly important role owing to their relatively great depth of penetration. We present a method for PNC (Pulsed Neutron Capture) tools to estimate CO2 saturation in sandstone reservoirs independently of the water salinity. To achieve this, we utilize a carefully selected energy window in the inelastic part of the gamma spectra. The ratio created from the number of counts in this window for different detector spacings is sensitive to hydrogen content of the reservoir rock, thus indirectly to CO2 saturation as well. We estimate the energy deposited by gamma photons in the scintillation detectors of the PNC tool for different model parameters such as rock properties (e.g. porosity) and CO2 saturations. A systematic modelling of the measurement was carried out using Monte Carlo N-Particle (MCNP), a general-purpose particle transport code. These results demonstrate the potential of this method for CO2 monitoring in sandstone reservoirs.

How to cite: Szucs, J. G., Galsa, A., and Balazs, L.: Monte Carlo modelling of a pulsed neutron capture tool for CO2 saturation estimation in sandstone reservoirs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-323, https://doi.org/10.5194/egusphere-egu23-323, 2023.

EGU23-1044 | Posters on site | ERE3.1

Hydrogen migration through natural rocks – an experimental approach 

Bettina Strauch, Peter Pilz, Martin Zimmer, and Johannes Hierold

The investigation of hydrogen storage options in geological formations is an important part towards the development of technologies for the use of renewable energy. Promising storage capacities are expected in either rock salt deposits or porous sandstone formations with a gas-tight mudstone as cap rock. To obtain crucial data on hydrogen diffusion rates in these rocks, experimental studies are necessary as a first approach.

Here we present an experimental set up comprising two gas chambers, separated by the rock sample under investigation, where the driving force for gas migration through the rock sample is solely the chemical potential (concentration gradient). The hydrogen migration behaviour in samples of dry and wet sandstone, rock salt and mudstone was qualified by hydrogen break-through times and diffusion coefficients. Differences between the rock samples can be clearly seen. Also, the effect that wetted or water-saturated samples have higher retention due to closed pores and microcracks. The break through times varied from half an hour for dry sandstone to 918 hours for wetted rock salt. Based on concentration changes on the permeate side, hydrogen diffusion coefficients were derived in the range from 10-9 to 10-7 m²/s. The experimental set up proves to be suitable for determining diffusion parameters in natural rocks.

How to cite: Strauch, B., Pilz, P., Zimmer, M., and Hierold, J.: Hydrogen migration through natural rocks – an experimental approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1044, https://doi.org/10.5194/egusphere-egu23-1044, 2023.

EGU23-1909 | Posters on site | ERE3.1

Microbial Risk Assessment for Underground Hydrogen Storage in Porous Rocks 

Eike Marie Thaysen, Timothy Armitage, Lubica Slabon, Aliakbar Hassanpouryouzband, and Katriona Edlmann

Climate change, triggered by a continuously rising use of carbon based energy sources, is a global concern. Geological hydrogen storage, e.g. in depleted gas fields or saline aquifers, can overcome imbalances between supply and demand in the renewable energy sector and facilitate the transition to a low carbon emissions society, in this way mitigating climate change. However, a range of subsurface microorganisms utilise hydrogen which may have important implications for hydrogen recovery, clogging and corrosion. We created a novel, globally applicable risk categorization tool based on the published environmental growth constraints of all major hydrogen utilizing microbes (hydrogenotrophic methanogens, hydrogenotrophic sulphate reducing bacteria, homoacetogens and hydrogenotrophic dissimilative iron reducing bacteria) and on reports of paleosterile subsurface environments. Application of the tool to 75 depleted or close to depleted gas fields on the UK continental shelf showed that 9 fields fall either within the ´No Risk´ category with temperatures >122 °C, making them the ideal candidates for hydrogen storage from a microbial risk point of view. Hydrogen storage in the 35 ´Low Risk´ fields with temperatures >90 °C or the 22 ´Medium Risk´ fields with temperatures >55 °C and salinities >1.7 M NaCl will require the careful characterization of the microbial community composition to assure that hydrogenotrophic microorganisms are not present. We recommend against utilising depleted gas fields with temperatures <55 °C which are at high risk for adverse microbial effects. 

Results were mapped and aligned with centres for renewable energy production and out-of-use pipelines suitable for repurposing to transport hydrogen. This showed that No Risk or Low Risk depleted gas fields in the Southern North Sea are the most suitable candidates for hydrogen storage. Our results advise site selection choices in geological hydrogen storage in the UK. Our methodology is applicable to any underground porous rock system globally.

How to cite: Thaysen, E. M., Armitage, T., Slabon, L., Hassanpouryouzband, A., and Edlmann, K.: Microbial Risk Assessment for Underground Hydrogen Storage in Porous Rocks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1909, https://doi.org/10.5194/egusphere-egu23-1909, 2023.

EGU23-2282 | ECS | Orals | ERE3.1

Hydrogen underground storage in a saline aquifer at the Ketzin site (Germany) – a numerical pre-feasibility assessment 

Lea Döpp, Wolfgang Weinzierl, Cornelia Schmidt-Hattenberger, and Ingo Sass

For integrating green hydrogen to the future energy system, underground storage facilities are needed. So far, there is no underground hydrogen pore storage facility in Germany. However, there is a lot of experience in town gas, natural gas , and CO2 underground storage which now can be used for hydrogen storage pre-feasibility assessments, explorations and operations.

In this approach the Ketzin anticline (Germany) is used for a pre-feasibility assessment for hydrogen underground storage in a saline aquifer by using experimental and measurement data from its time as a CO2 test site during 2004 to 2017.

For this first feasibility assessment we focused on the influence of several reservoir parameters on hydrogen solubility and the production rate. Therefore, the influence of the brine´s salinity, capillary pressure, reservoir pressure and temperature of two potential storage formations at Ketzin site is analyzed.

The Stuttgart formation was already used as a CO2 storage formation during the projects CO2SINK, CO2MAN, COMPLETE. Due to loss reduction by a optimal structural trapping the potential hydrogen injection and production well is located at the top of the anticline –  about 1.5 km north to the former CO2 storage test site. Based on Fleury´s experimental data from 2013, including capillary pressure, six parameter setups are created to simulate six hydrogen production and injection cycles.

For the second storage formation, the Exter formation, less experimental and measurement data is available. Therefore, six scenarios were designed on the basis of literature values. The end members represent a low and a high hydrogen recovery scenario which combine the best and worsed possible parameter setup for this formation.

The results show that it is important to consider the regional conditions individually and to respond to the specifications of the site to minimize economic and safety risks in hydrogen underground storage.

How to cite: Döpp, L., Weinzierl, W., Schmidt-Hattenberger, C., and Sass, I.: Hydrogen underground storage in a saline aquifer at the Ketzin site (Germany) – a numerical pre-feasibility assessment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2282, https://doi.org/10.5194/egusphere-egu23-2282, 2023.

EGU23-2509 | Posters on site | ERE3.1

Ice-Inclusion Compounds for Energy Gas Storage 

Minjun Cha

Gas hydrates are types of crystalline-inclusion compounds composed by a ‘host’ framework and ‘guest’ molecules. In general, ‘host’ water molecules constitute the hydrogen-bonded host framework, and ‘guest’ molecules, such as methane, ethane, propane, hydrogen, or carbon dioxide, can be encapsulated in the framework structures. Huge amount of gases can be selectively captured in the hydrate structures, and thus; gas hydrates have been received much attention in the energy and environmental fields for gas storage and separation. Here, we introduced the hydrate-forming agents, including cyclic alcohol and amine molecules, for energy gas storage. The guest inclusion behaviors of binary clathrate hydrates were examined by spectroscopic tools, 13C solid-state nuclear magnetic resonance (NMR) spectroscopy and powder X-ray diffraction (PXRD) analysis. The storage capacity of methane gas in the binary clathrate hydrates was also examined. The findings, regarding the inclusion behavior of cyclic molecules in hydrate cages, the storage capacity of methane in hydrate structure, and the thermodynamic stability of the binary clathrate hydrates, may provide fundamental information on the complex nature of host–guest inclusion chemistry and lend useful insights with respect to potential gas hydrates applications for gas storage. 

How to cite: Cha, M.: Ice-Inclusion Compounds for Energy Gas Storage, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2509, https://doi.org/10.5194/egusphere-egu23-2509, 2023.

EGU23-3439 | Posters on site | ERE3.1

Testing the self-healing capacity of sealant materials for subsurface storage applications. 

Reinier van Noort and Viktoriya Yarushina

The secure subsurface storage of fluids, whether energy carriers such as hydrogen or wastes such as CO2 or nuclear waste, requires sealants that can ensure wellbore seal integrity over timescales of decades to millennia. Currently used sealants are typically based on Ordinary Portland Cement (OPC) technology, which results in brittle seals that may have limited ability to withstand aggressive chemical environments. These properties make it difficult to ascertain that such sealants will maintain seal integrity over the long lifetime of a subsurface storage reservoir, as temperature and/or pressure variations during operations; chemical attack; or geomechanical effects may induce leakage pathways through the seal, as well as along the interfaces between seal and wallrock, or between seal and steel, resulting in a loss of wellbore sealing integrity.

Self-healing sealant materials can be a key technology for ensuring long-term seal integrity in underground storage applications. Such sealants should interact with leaking fluids so that when leakage pathways do form, these pathways are sealed rather than widened. We present experiments in which we aim to test the self-healing capacity of different sealants, particularly for CCS applications, by exposing a reproducible simulated leakage pathway to a flow of CO2(-bearing fluid) under in-situ conditions. Our simulated leakage pathway consists of a sawcut through a hardened sealant sample, propped with crushed, hardened sealant (though other materials can also be used). Until now, we have focused on OPC-based sealants with various mineral additives (such as olivine and brucite) that result in an increase in solid during carbonation; but other sealants not based on OPC, such as geopolymers, may also be tested. During flow exposure, the pressure drop across the sample is monitored to assess permeability changes. After the experiments, SEM is used to study microstructures and identify reaction products. The results of this experimental work are then used as input for numerical modeling studies that seek to simulate the observed interactions and can extrapolate obtained results beyond laboratory time and length scales. In our model, chemical alteration of the cement is coupled to mechanical deformation and fluid flow to capture the cement system's volume changes that will help mitigate leakages.

How to cite: van Noort, R. and Yarushina, V.: Testing the self-healing capacity of sealant materials for subsurface storage applications., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3439, https://doi.org/10.5194/egusphere-egu23-3439, 2023.

EGU23-3867 | ECS | Posters virtual | ERE3.1

Underground Storage of Natural Gas and CO2 Monitoring Applications 

Gabriele Fibbi, Matteo Del Soldato, and Riccardo Fanti

Natural gas is one of the most widely used fossil fuels in the world and it represents an essential element for human activities. It can be stored in underground geological structures such as depleted oil/gas field, aquifers and salt caverns. Underground Gas Storage (UGS) application plays a key role for covering natural gas demand and supply fluctuations, e.g., methane, CH4, by injecting gas in the summer season when the demand is lower, ready to be withdrawn and deployed into the network to meet increased consumer demand in the winter season. Unfortunately, constant human exploitation of fossil fuels causes climate change phenomenon, creating a potential risk of breaching environmental tipping points with negative consequences. In this regard, the carbon capture and storage (CCS) practice, which is different in methods and purpose from UGS, has been gaining popularity in the last decades. The latter strategy involves storing Carbon Dioxide (CO2) before it enters in the atmosphere, by means of geological structures for centuries or thousands of years and it can support one of the most important challenges of the twenty-first century, helping the decrement of the global warming and to chase the goal of near-zero greenhouse gas emissions. Misuse of UGS and CCS activities or poor maintenance of injection and withdrawal wells can induce effects of considerable magnitude such as ground deformation, micro-seismic events, fault reactivation and gas leakage. The development of appropriate injection methods and long-term monitoring systems for leak detection is important to verify the integrity of the reservoir, the effectiveness of activities and the respect of safety conditions. In literature approximately a hundred scientific contribution of UGS and CCS monitoring applications were spanning in the world. All the scientific peer-reviewed books and articles, and congress proceedings about the reservoir monitoring in gas storage activities collected and critically analysed show an analytical and statistical overview of the most common use of UGS and CCS, detailing the different goals of these two applications. This research allows displaying the advantages and drawbacks of each monitoring technique involved in gas storage applications by analysing the main UGS and CCS projects. Further developments are required for the UGS monitoring, especially through multidisciplinary approaches useful for identifying possible effects on the surface and gas leaks at depth; meanwhile, CCS solutions are still at an experimental stage, due to the high costs for large-scale applications that require specific researches. The state of the art of these two very different practices can improve the further development of new monitoring approaches or additional methods. The next years will reveal if the CCS methods will be among the leading techniques in the race for energy transition.

How to cite: Fibbi, G., Del Soldato, M., and Fanti, R.: Underground Storage of Natural Gas and CO2 Monitoring Applications, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3867, https://doi.org/10.5194/egusphere-egu23-3867, 2023.

EGU23-4237 | ECS | Orals | ERE3.1

Numerical Assessment of Hydrogen and Gas Mixture Storage in Salt Caverns 

Richard Wallace and Zuansi Cai

With the UK recently doubling its hydrogen production goals to adjust to the market demand the necessity for storage is becoming realised [1]. There are several options for utility-scale storage including salt caverns, deep saline aquifers and depleted gas fields. Salt caverns hold the unique benefit over porous storage of being capable of numerous cycles due to the dynamics of gas withdrawal, making them indispensable in the hydrogen storage strategy of each country. This is exemplified in the UK where it is anticipated to range up to 56TWh. Unfortunately, these are not as readily available as porous storage and hence, competition between different energy storage types may cause problems.

Of the subsurface energy storage systems, natural gas has been in operation for decades and is an established technology with numerous papers investigating different aspects of its operation and development. However, with the ambition of phasing out fossil fuel energy sources compressed air energy storage (CAES) and hydrogen storage are considered in Salt Caverns. It is also understood that during the transitionary period a gas blend may be utilised for the heating, currently, the maximum this stands at is 80:20 %vol of CH4 to H2. In most instances (at least for the UK), these systems will compete for storage as offshore wind farms, gas reservoirs and the national transmission system (gas grid) align [2]. Due to the different thermodynamic properties of each gas, it is important to know the impact of cyclic loading of each system on both the gas temperature and how this translates to its surrounding rock.

To investigate this, an idealised model of the NK1 cavern at the Huntorf CAES facility is developed and a historical operational cycle is simulated. Methane, Hydrogen and a Gas blend (80:20 %vol of CH4:H2) will be simulated and compared to that of the compressed air energy storage in[3]. This is then furthered by creating a mass-balanced cycle based on the initial cycle and extended for one month to see how these variations develop. The significance of this is to provide insight for the decision-making in which energy storage facility is appropriate for the region as a result of the numerical modelling.

 

References

  • Hydrogen Strategy update to the market: July 2022, E.I.S. Department for Business, Editor. 2022: London, United Kingdom.
  • Wallace, R.L., Z.S. Cai, H.X. Zhang, K.N. Zhang, and C.B. Guo, Utility-scale subsurface hydrogen storage: UK perspectives and technology. International Journal of Hydrogen Energy, 2021. 46(49): p. 25137-25159.
  • Guo, C.B., L.H. Pan, K.N. Zhang, C.M. Oldenburg, C. Li, and Y. Li, Comparison of compressed air energy storage process in aquifers and caverns based on the Huntorf CAES plant. Applied Energy, 2016. 181: p. 342-356.

How to cite: Wallace, R. and Cai, Z.: Numerical Assessment of Hydrogen and Gas Mixture Storage in Salt Caverns, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4237, https://doi.org/10.5194/egusphere-egu23-4237, 2023.

EGU23-5973 | Orals | ERE3.1

Assessing permanent CO2 storage volume in a buried volcano offshore West Iberia 

Davide Gamboa and Ricardo Pereira

In-situ mineral carbonation is a process that occurs naturally, through the interaction of CO2 rich fluids and minerals of mafic and ultramafic rocks, towards the formation of new stable carbonate materials. Formed spontaneously in peridotites and serpentinites (e.g., the Samail Ophiolite of Oman), the concept has been successfully replicated through industrial applications with mineral trapping demonstrated to occur on Icelandic basaltic lava flows within a period of 2 years.

A Late Cretaceous volcanic edifice located on central West Iberian Margin, offshore Portugal, is investigated as a conceptual site for in-situ mineral carbonation, and a study case for the application of this model on similar volcanic edifices on continental margins worldwide.

Using seismic reflection surveys, the volcano is revealed as a 2800 m high edifice, with an estimated total rock volume of 327 km3. Dredges collected from an exposed crest of the volcano revealed vesicular olivine-rich sub-alkaline basalts, infilled with naturally formed carbonate minerals. Analysis of the internal architecture of the edifice reveals outward dipping reflectors, with its magmatic features assigned to alternating successions of lava flows and explosive debris, that have grown progressively to form a composite volcano. Lava flows directly associated with the final stages of volcanic build-up, comprise dendritic and lobate lava flows (pahoehoe or submarine flows) blanketing the flank of the edifice. Accounting for the auspicious architecture, nature, and rock properties of the edifice, a deterministic volumetric model is used to estimate different scenarios of the amount of CO2 that can be safely and permanently stored in the volcano. Combining comprehensive inputs from bulk rock volume, effective porosity, and sequestration ratios, our estimations indicates that on a base case, the volcanic edifice has the potential to capture nearly 1.2 Gt CO2 into new stable mineral phases. On a high case scenario, this single edifice could permanently capture up to 8.6 Gt of CO2. Considering that during the 2015-2018 period, the Portuguese energy sector emitted an average volume of about 48 Mt CO2 eq per year, our estimates suggest that the volcanic reservoir is capable of storing an equivalent of 24 years of the country’s industrial emissions. Compared with oceanic magmatic sequences worldwide, buried volcanic edifices on continental margins materialise as notable locations for in-situ mineral carbonation.

This assessment provides timely insights on the overall process of in-situ mineral carbonation, on ancient buried volcanoes, to reveal critical geological controls that can lead this technique to be applied on a pilot phase and envisage further concepts at economic scale. Moreover, geohazards associated with the proximity to populated areas are significantly minimised. Ultimately, results suggest that volcanoes on passive continental margins can be considered for safe and permanent carbon storage, by accommodating 100’s of Gt of CO2 from energy intensive industry sources and contribute to mitigate the impacts of anthropogenic carbon emissions.

This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) UIDB/04035/2020-GeoBioTec and UIDB/50019/2020-IDL. D. Gamboa thanks FCT funding for project MAGICLAND (PTDC/CTA-GEO/30381/2017).

How to cite: Gamboa, D. and Pereira, R.: Assessing permanent CO2 storage volume in a buried volcano offshore West Iberia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5973, https://doi.org/10.5194/egusphere-egu23-5973, 2023.

EGU23-6015 | ECS | Orals | ERE3.1

Rare methanogenic Archaea can become active in natural high-CO2 subsurface environments upon changing environmental conditions 

Zeyu Jia, Daniel Lipus, Oliver Burckhardt, Robert Bussert, Megan Sondermann, Alexander Bartholomaeus, Dirk Wagner, and Jens Kallmeyer

The Eger Rift (Czech Republic) is characterized by deep-seated volcanic activity, leading to high CO2 fluxes up to 125 kg m-2 d-1 and frequent tectonic activity. With its subsurface being naturally CO2-rich at least since the Mid-Pleistocene, the Eger Rift is a natural analogue of underground CO2 storage sites that allows for studying long-term effects of high CO2 concentrations on the mineralogy and microbiology of such systems. Frequent small earthquakes lead to abiotic production of H2, providing energy to indigenous microbial communities. Investigating the microbial communities residing in such natural analogue sites provides crucial knowledge about the possible log-term consequences of anthropogenic underground CO2 storage. To assess the metabolic potential of the CO2-adapted microbial community and its reaction to transient availability of Hydrogen, we evaluated diversity as well as metabolic attributes of bacterial and archaeal communities surviving under high CO2 conditions, and their changes after exposure to Hydrogen.

A 230 m long drill core was recovered as part of the International Continental Drilling Program’s (ICDP) Eger Rift Project. Drilling was carried out under contamination-controlled conditions to provide pristine samples for geomicrobiological analyses.

We used cell counts and qPCR to assess microbial abundance across sediment and rock samples and both Illumina and Nanopore DNA sequencing platforms to gain insights into community structure and metabolic potential. Enrichments were set up to evaluate the ability of the CO2-adapted microbial communities to utilize Hydrogen. We further isolated and purified active methanogens for detailed insights into their metabolic capability.

Our investigation revealed a CO2-adapted community with low biomass and a surprisingly diverse archaeal population. Methanogens are rare and account for less than 1% of the total microbial community in most drill core samples. However, enrichments revealed an active hydrogenotrophic methanogen population from a narrow depth interval (50-60 m), dominated by Methanobacterium and Methanosphaerula. The autotrophic sulfate reducer Desulfosporosinus, also thrives in the same depth interval. We isolated methanogen strains from the enrichments from the 50-60 m depth interval, whereas enrichments from other depths remained low in biomass and showed little or no methanogenesis.

The strong differences in methanogenic activity among the enrichment cultures emphasize sediment heterogeneity, strongly suggesting the need for a high-resolution sampling strategy to evaluate the long-term effects of CCS. Our study shows that distinct processes may happen only in very narrow depth intervals and only reveal themselves through incubation/cultivation experiments, thus highlighting the importance of cultivation-dependent investigation on exploring the metabolic potential of microbial communities in subsurface environments.

How to cite: Jia, Z., Lipus, D., Burckhardt, O., Bussert, R., Sondermann, M., Bartholomaeus, A., Wagner, D., and Kallmeyer, J.: Rare methanogenic Archaea can become active in natural high-CO2 subsurface environments upon changing environmental conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6015, https://doi.org/10.5194/egusphere-egu23-6015, 2023.

Decarbonisation of energy grids as part of the accelerating zero-carbon energy transition requires the massive deployment of renewable energy sources like wind and solar power. Because of their intermittent nature, grid-scale energy storage solutions are required on all scales ranging from battery storage, pumped-storage hydroelectric power and subsurface energy storage solutions.

Energy storage in geological formations, for example, depleted hydrocarbon reservoirs, saline aquifers and man-made rock and salt caverns, has been employed for decades and is ideal because of the potential to safely store large volumes of energy with negligible effects on the surface environment.

Man-made salt caverns have been in widespread use for natural gas storage. Salt formations are ideal due to the inert, impermeable and self-healing nature of salt. Gas can therefore safely be stored in large geometrical volumes at high storage pressures, making it optimal for not only natural gas storage but also electrical energy storage in the form of compressed air (CAES) or hydrogen (HES).

The study is in the Southern North Sea basin (SNS). The SNS is characterised by the accumulation of massive cyclical evaporitic sequences, which were extensively deformed by post-Permian salt movement of Zechstein salt sediments resulting in thicknesses ranging from less than 50m to greater than 2500m.

The North Sea oil and gas sector has been at the heart of the UK energy security. The SNS has undergone decades of extensive exploration yielding large volumes of geological and geophysical data available for renewable energy and energy storage research.

By means of 3D seismic reflection and well data interpretation, this work employs an established screening method used in the hydrocarbon industry, Play Fairway Analysis, to identify potential exploration targets on a regional scale. This approach involves determining the presence and efficiency of a source, migration pathway, a reservoir, a seal and assigning a risk factor to each based on those criteria.

The source and migration pathway equivalents are the location of current and future offshore infrastructure, the reservoir equivalent is defined by the characteristics and distribution of the salt structures and the seal equivalent is defined by the operational constraints within which energy storage can safely occur. The design and placement of salt caverns is governed by the characteristics of the salt deposit and the thickness of the salt layers above and below the cavern. The operational depth range required for sustainable and safe operation is between 400-1500m. The resultant common risk segment map highlights areas with highest energy storage potential.

Initial results indicate that numerous prospective salt structures in the UK sector of the SNS are readily located near existing and future planned offshore wind parks. Future work will build on this through geological characterisation of the target salt structures, shallow hazard assessment, geomechanical assessment to determine cavern placement and storage capacity. The key outcomes of this study include a regional overview of the number and distribution of salt structures, their respective storage potential and the overall feasibility of CAES and HES implementation as part of the UK energy transition strategy.

How to cite: Hansen, S. and Adam, J.: Compressed Air Energy and Hydrogen Storage Potential in Salt Structures in the UK Sector of the Southern North Sea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9900, https://doi.org/10.5194/egusphere-egu23-9900, 2023.

EGU23-10005 | Posters on site | ERE3.1 | Highlight

(Pre)feasibility study of underground hydrogen storage potential in depleted gas fields and salt caverns in the Netherlands 

Joaquim Juez-Larré, Cintia Gonçalves Machado, Hamid Yousefi, Ta-Kai Wang, Remco Groenenberg, and Serge Van Gessel

Hydrogen is expected to play an important role in our future energy system. It is a versatile energy carrier that can be produced from renewable electricity and then be used as a CO2-neutral fuel for (re)generating electricity and/or heat, or as feedstock for the chemical industry. Hydrogen can be stored underground in large quantities and therefore has the potential to take over the role of natural gas in securing the supply of energy. Although depleted gas fields can potentially store larger volumes of hydrogen than current clusters of salt caverns, UHS in porous reservoirs is not yet a proven technology. To enable future demonstration/pilot projects, screening studies are needed for the identification and characterization of potential underground candidates.

Since 2012, the Dutch Ministry has funded several national (pre)feasibility studies to estimate the potential for underground natural gas and hydrogen storage (UGS & UHS) and flow performance of depleted natural gas fields and salt caverns clusters in the Netherlands. Various methodologies and criteria are being utilized. Analog methods provide first-order estimates on UHS capacities based on the volume of natural gas originally contained in fields and clusters of salt caverns. This reveals a total theoretical maximum storage capacity onshore of up to a few hundred TWh for fields and tens of TWh for clusters of salt caverns. More accurate estimates were obtained from nodal analyses using the analytical inflow performance relationship (IPR) and the vertical flow performance (VFP) curves. Surface limitations were considered for onshore areas such as groundwater, protected and urban areas, which shows a significant reduction, on average around 60%, in the total theoretical storage capacity. Because of that, and in order to search for alternative UHS sites, more attention has been paid to depleted fields and salt pillars in offshore areas. For this, realistic technical limitations were assumed, such as the working pressure range of transmission systems between 150  and 250 bar. This reveals a significant reduction in the storage capacity and flow performances, as many fields would not be filled to their maximum working capacity. For a better understanding of the difference between the performance of UGS and UHS, three UGSs currently in operation in the Netherlands were investigated in more detail. Results show that the range of working pressures at which they may operate significantly determines the amount of energy that a UHS can store. Results from ongoing numerical modelling (Eclipse 300) for some of the best depleted gas fields allow quantifying the efficiency of different operating strategies and the number of wells required based on injection/withdrawal cycles at various timescales (daily-weekly-monthly), distinct ranges of working pressures and types of cushion gas (e.g. nitrogen/hydrogen). Other aspects such as geochemical reactions, microbial activity and type of residual gas in the different fields are also being considered as selection criteria. These ongoing studies are expected to facilitate the screening and design of future demonstration/pilot projects for UHS in gas fields and salt caverns in the Netherlands beyond 2030.

How to cite: Juez-Larré, J., Gonçalves Machado, C., Yousefi, H., Wang, T.-K., Groenenberg, R., and Van Gessel, S.: (Pre)feasibility study of underground hydrogen storage potential in depleted gas fields and salt caverns in the Netherlands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10005, https://doi.org/10.5194/egusphere-egu23-10005, 2023.

The non-linear interaction of supercritical CO2 with brine in confined saline aquifers is an important problem in geophysical fluid dynamics and understanding its mechanism is pivotal for the design of carbon-sequestration schemes. In principle, dissolution of CO2 into the ambient brine from a buoyant supercritical phase across the CO2-brine interphase causes the density of the mixed diffusive layer to increase, thereby triggering gravitational instability generating Rayleigh-Taylor like convection and increasing CO2 dissolution and uptake by the reservoir. These dynamics are nonlinear and must be studied numerically, with previous works commonly focusing on homogeneous domains and pure diffusion only and often assuming no background flow in the aquifer.

We discuss a large-scale numerical Monte Carlo study considering the three-way interaction of heterogeneous permeability and porosity field structure, background flow, and local-scale dispersion on CO2 uptake. For this purpose, we developed a novel combined Eulerian flow—Lagrangian transport code for simulating single-phase CO2-enriched brine movement in systems featuring a spatially varying density field controlled by dissolved CO2 concentration and a background pressure gradient. The usage of the Lagrangian approach uniquely allows us to quantify the effect of local-scale horizontal and longitudinal dispersion on the flow dynamics and capture relevant non-Fickian transport behaviors without the confounding effect of numerical dispersion and to maintain numerical stability under strongly advective conditions.

We present results characterizing the impact permeability-porosity structure, background flow, local dispersion on CO2 uptake and fingering dynamics. Quantifying these factors via appropriate dimensionless groups, we analyze their impact on onset time of convection, and on regime transition from gravitationally dominated convection to background flow dominated advection-macrodispersion regimes. The relationship between porosity-permeability structure and fingering dynamics is also outlined and quantified.

How to cite: Sen, S. and Hansen, S.: Modelling gravitational convection and miscible flows in heterogeneous porous media with a semi-Eulerian-Lagrangian scheme: implications for deep carbon sequestration., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11844, https://doi.org/10.5194/egusphere-egu23-11844, 2023.

EGU23-12119 | ECS | Orals | ERE3.1

Multiple caprock layers offer confidence in permanent geologic CO2 storage at the gigatonne scale 

Iman R. Kivi, Roman Y. Makhnenko, Curtis M. Oldenburg, Jonny Rutqvist, and Victor Vilarrasa

Widespread deployment of Geologic Carbon Storage (GCS) at the gigatonne scale is projected to play a vital role in reaching carbon neutrality and mitigating the climate crisis. One major concern with GCS scale-up is the ability of geologic formations to retain CO2 deep underground, at least over several thousand years. Of particular importance to this issue is the sealing capacity of the ideally low-permeability, high-gas-entry pressure caprock(s). Existing simulation studies to address the long-term fate of the injected CO2 could barely exceed multi-century time scales due to high computational costs. This work aims to provide an improved understanding of the extent to which the potentially leaked CO2 from basin-wide GCS may rise through a multi-layered system of laterally uniform aquifers and shale caprocks over geological time scales (million years). To this end, we develop a one-dimensional CO2 flow and transport model, which is arguably capable of capturing the dynamics of basin-scale upward CO2 migration. We consider two sets of caprock properties: (1) low intrinsic permeability (10-20 m2) and high capillary entry pressure (2.5 MPa), obtained from laboratory measurements on intact clay-rich shales, and (2) high permeability (10-16 m2) and low entry pressure (0.1 MPa), representative of pervasively fractured shales at regional scales. On the one hand, we find that the free-phase CO2 can hardly penetrate more than a few centimeters into the intact caprock directly overlying the storage reservoir. CO2 leakage in this scenario is exclusively governed by molecular diffusion with an estimated migration rate of 1 meter over thousands of years. On the other hand, the high permeability and low entry pressure of fractured caprocks enable CO2 to break through the whole primary caprock during the injection and through the secondary one(s) in the post-injection period. However, following the gradual CO2 pressure decline, brine imbibition back into caprocks suppresses CO2 leakage and the percolating path is cut by an overlying caprock. Once the pore fluid of upper aquifers becomes CO2-saturated, secondary CO2 accumulations form and may host a significant portion of the injected CO2. The extreme leakage scenario, which allows for further CO2 rise of nearly one hundred meters becomes eventually diffusion-dominated and hence relatively safe. Our model results suggest that the presence of multiple shaly caprock layers, even if pervasively fractured, provides secure CO2 containment in the subsurface over millions of years.

 

Reference

Kivi, I. R., Makhnenko, R. Y., Oldenburg, C. M., Rutqvist, J., & Vilarrasa, V. (2022). Multi-layered systems for permanent geologic storage of CO2 at the gigatonne scale. Geophysical Research Letters, 49, e2022GL100443. https://doi.org/10.1029/2022GL100443

How to cite: Kivi, I. R., Makhnenko, R. Y., Oldenburg, C. M., Rutqvist, J., and Vilarrasa, V.: Multiple caprock layers offer confidence in permanent geologic CO2 storage at the gigatonne scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12119, https://doi.org/10.5194/egusphere-egu23-12119, 2023.

EGU23-13433 | ECS | Posters on site | ERE3.1

Large Scale Experiments on the Tightness of Cemented Boreholes under Cyclic Loading 

Marcel Schulz, Birgit Müller, and Frank Schilling

The exit from nuclear and fossil-fuel energy and the increase in renewable energy conversion lead to a higher fluctuation in energy supply. To meet the demand in times of energy shortages from sun and wind, this effect can be compensated by extracting and using gas from underground gas storages. As long as enough renewable energy is available, storages can be filled again. However, this results in increasing injection and extraction frequencies, leading to faster occurring pressure and stress changes and therefore posing an additional challenge for reservoir rock, cap rock and technical components.

To evaluate the effects of this additional cyclic loading on the rock-cement-steel-compound, we used an autoclave system on a realistic scale. It simulates abandoned drillings and consists of a 2 m long cemented steel casing with an autoclave system. To simulate injection and extraction, gas pressure (N2) is applied and released on both ends. Additionally, temperature can be raised up to 100 °C. Between loading cycles, permeability can be measured to determine the effect of pressure and temperature variation on the tightness of the cemented well system.

We present results from the analysis of four cemented casings. Since the hardened cement isn’t connected to the steel casing after experiments, we assume an annular gap as main gas path in most cases. This gap is modelled and fitted to the experimental data. After pressure variations between 0 bar and 60 bar, tightness of the system decreased in every experiment, which leads to an increased modelled annular gap width. Temperature variations between 30 °C and 70 °C didn’t have an effect on the first two casings, but increased tightness and therefore decreased the modelled gap width in the third casing.

Additionally, we observed an anomaly in the second casing, which was extraordinarily tight before the first pressure drop. However, when small amounts of pressure (around 3 bar) were released from an autoclave chamber, around 30 % of the released pressure built up again within a few minutes, while the rest took several hours. We assume a releasing induced gas cooling in the autoclave, while the surrounding warmer steel heats the gas up to the original temperature. This can only be observed for experiments with a rather tight cement-steel plug. In other cases this is not observable because it is superimposed by the pressure build up through the annular gap. The results of finite difference model taken this temperature induced pressure build up into account and are compared to the results of independent permeability and porosity measurements.

How to cite: Schulz, M., Müller, B., and Schilling, F.: Large Scale Experiments on the Tightness of Cemented Boreholes under Cyclic Loading, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13433, https://doi.org/10.5194/egusphere-egu23-13433, 2023.

EGU23-13688 | ECS | Posters on site | ERE3.1

Hydrogen storage pilot: geological characterisation of an onshore aquifer structure in Fife, Scotland 

Kate Adie, Niklas Heinemann, Giorgos Papageorgiou, Mark Wilkinson, Stuart Haszeldine, Colin Thompson, and Courtney West

Energy storage technologies are required to support the rapid development and integration of intermittent renewable energy sources into energy systems. Large-scale hydrogen storage in porous formations presents the opportunity to balance seasonal variation in energy demand. This reservoir modelling study aims to establish dynamic capacity estimates for seasonal hydrogen storage. This study investigates a shallow (<1km) sandstone reservoir, of an onshore anticlinal structure in east Fife, Scotland. This storage evaluation supports the geographically proximal H100 pilot rollout of 100% hydrogen for domestic use in 300 volunteer homes (https://www.sgn.co.uk/H100Fife). The target reservoir comprises a partially explored Carboniferous aquifer, thus this study also addresses the challenge of establishing a workflow for the appraisal of storage sites with limited data availability. We aim to maintain low investment costs for this currently immature technology. A static 3D geological model was constructed in reservoir modelling software, PETREL (Schlumberger), informed by data obtained from legacy seismic surveys and from deep boreholes acquired in a hydrocarbon exploration campaign in the 1980s. A sedimentological study was undertaken on the well-known local and regional Carboniferous sedimentology from subsurface information and coastal exposures to characterise reservoir heterogeneity internally – a necessary step to address the large data gaps between sparsely available data points. The reservoir is conceptualised as a 60-70m channelised fluvial sand, with unreactive quartz-arkose mineralogy, interbedded with thin mudstone horizons. The top seal is characterised by silts and mudrock, comprising a widespread maximum flooding surface. Seismic and borehole data has enabled a 3D base case model of stratigraphy and structure. Combined reservoir and structure forms a finite element model exported to CMG’s GEM, used to assess dynamic capacity estimates. Our key research questions are: does the target reservoir exhibit sufficient capacity to support seasonal hydrogen storage based on scenarios informed by industrial experience; what are the cushion gas requirements and associated costs; and what are the key risks and uncertainties influencing capacity estimates. We plan a base case scenario using the most probable geological reservoir and will investigate sensitivity variations around the geology. Benefits from this study include: i) development of a workflow for the hydrogen characterisation of storage reservoirs and the management of risk, whilst minimising initial investment costs, ii) evaluation of cushion gas requirements in a layered reservoir with only a few degrees of dip. Our preliminary results of injection and production will be discussed.

How to cite: Adie, K., Heinemann, N., Papageorgiou, G., Wilkinson, M., Haszeldine, S., Thompson, C., and West, C.: Hydrogen storage pilot: geological characterisation of an onshore aquifer structure in Fife, Scotland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13688, https://doi.org/10.5194/egusphere-egu23-13688, 2023.

EGU23-13706 | Posters on site | ERE3.1

IESDB – A comprehensive database of evaporite structures in Iberia 

Juan Alcalde, Eloi González-Esvertit, and Enrique Gómez-Rivas

Evaporite rocks are one of the most mined mineral commodities and act as a seals or shaping traps in some of the major hydrocarbon provinces worldwide. In addition, they are also considered as suitable sites for the storage of energy and nuclear waste, being a key asset for the energy transition. Due their historic, present and future value, vast amounts of surface and subsurface information about evaporite structures have been generated by earth scientists, mining and exploration companies or geological surveys in the last century. However, this information is often scarcely useful due to access issues, segregation and scarce dissemination. Here we present the Iberian Evaporite Structure DataBase (IESDB), the first overall assessment focused on evaporite structures developed in any region of the world. The IESDB includes information and figures of 150 outcropping and buried evaporite structures and their surrounding rocks inventoried in Iberia. The Iberian Evaporite Structure Database (IESDB) includes information about the stratigraphy, structure, evolution, geophysical and petrophysical data availability, and mining activity, including a complete set of geological maps, sketches and geological cross-sections. The database targets different evaporite structures, such as undeformed successions, diapirs, evaporite-cored anticlines, evaporite-detached thrusts or allochtonous evaporite bodies. The IESDB is sourced from six different databases and more than 1,500 published and unpublished references, and includes information and figures for each of the 150 evaporite structures inventoried. The IESDB follows the FAIR principles of data management (Findable, Accessible, Interoperable, Reusable) and aims to be a resource for earth science teaching, academic research and resource exploration and appraisal. The IESDB is freely available at https://iesdb.eu

This research was performed within the framework of DGICYT Spanish Project PID2020-118999GB-I00 funded by the Ministerio de Ciencia, Innovación y Universidades/Agencia Estatal de Investigación/Fondo Europeo de Desarrollo Regional. Grants RYC2021-033872-I (Juan Alcalde) and RyC-2018-026335-I (Enrique Gomez-Rivas) funded by MCIN/AEI/10.13039/501100011033 and ESF “Investing in your future”.

How to cite: Alcalde, J., González-Esvertit, E., and Gómez-Rivas, E.: IESDB – A comprehensive database of evaporite structures in Iberia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13706, https://doi.org/10.5194/egusphere-egu23-13706, 2023.

EGU23-13953 | ECS | Posters on site | ERE3.1

Storage Potentials for artificial CO2 products in Germany 

Sarah Diekmeier, Karsten Reiter, and Colin Friebe

To achieve the EU's net zero emissions target in 2050, unconventional measures to remove CO2 from the atmosphere are urgently needed (IPCC, 2016). Due to the very tight remaining CO2 budget, all illustrative model pathways in the IPCC special report on the 1.5°C target assume that net negative emissions must be achieved in the second half of the century. Direct storage of pure carbon dioxide has been investigated and is still applied, but limited depending on the location by restrictive laws, geological availability, and the uncertain long-term safekeeping. The NETPEC project strives to use photo-electro-chemical methods as energy source to produce easily storable, safe and sustainable carbon-sink products. These solid or liquid carbon-rich products can be long-term stored in the underground or at the surface.

The aim of the project part, which will be presented, was to create a database containing the storage potentials of Germany with respect to different end products with a large as possible carbon content. Further criteria for the storage sites are a guaranteed safe deposit for at least 1000 years, no negative influence on the surrounding biosphere and its living organisms and no negative interactions between product and repository of any kind. Due to large volumes of production from opencast and mining operations, sites that appear to be suitable in Germany are former open-pit and underground mines. In the case of a fluid product, various underground storage facilities such as hydrocarbon fields and pore storage complexes appear suitable too. In addition, a disposal of solid end products via regular landfills is conceivable. The collected data were provided by the state offices of the federal states and included both legal office maps in raster format which were digitalized and supplemented by other provided or public data as well as shape files with attributes. Depending on the information provided by the states, the database contains the location, the name of the location, owner of the location, area of the location, type of authorization, type of natural resource and for some states also the extracted volumes of the resources.

Production quantities and volumes can be used to compare the capacities of potential storage sites with the volume of the CO2 product. As an interim result, both the qualitative opportunities and the quantitative potentials for final repository of solid or liquid carbon-rich product near the surface or underground are shown and illustrate the clearly widely distributed, large potential of the extensive volumes for storage in Germany.

How to cite: Diekmeier, S., Reiter, K., and Friebe, C.: Storage Potentials for artificial CO2 products in Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13953, https://doi.org/10.5194/egusphere-egu23-13953, 2023.

EGU23-14277 | Posters on site | ERE3.1

Effect of stress cycling on the deformation and AE characteristics of reservoir rock from the perspective of energy storage: An experimental study 

Milad Naderloo, Edgar Hernandez, Kishan Ramesh Kumar, Auke Barnhoorn, and Hadi Hajibeygi

A successful energy transition requires effective storage options. Using underground energy storage (UES), such as depleted porous reservoirs, can help balance the production and demand for renewable energy. Because of the production and injection operations sequence, all underground energy storage systems, including compressed air and hydrogen energy storage, are subject to cyclic loading. To design and operate underground storage facilities, it is essential to understand the geomechanical behavior of porous reservoir rock under cyclic loading. We present the results of the triaxial cyclic laboratory experiments conducted on Red Phaelzer sandstone at 10 MPa confining pressure. By considering three frequencies (F1=0.014 Hz, F2=0.0014 Hz, and F1=0.0002 Hz), two amplitudes (A1=20 MPa and A2=5.9 MPa) and two stress regimes (38 MPa and 85 MPa), 12 triaxial cyclic tests were performed. In total, eight triangular stress cycles were applied for each test, and at the same time, six piezoelectric sensors recorded the acoustic emission (AE) activities during these experiments. Results showed that the total axial inelastic deformation increases when the stress regime and amplitude of cycles are increased. However, this parameter reduces by increasing the frequency of cycles. In addition, Young’s modulus computed from the loading ramps of the cycles increased significantly from the first cycle to the second cycle for all the tests. For tests in the brittle regime, the relation is that the larger the amplitude of cycles, the lower the increase in Young’s modulus. In addition, the AE analysis showed that major events were recorded in the first cycle. By increasing the number of cycles, the number of events, the maximum AE, and the average AE amplitude decreased. Our experimental results highlight that major mechanical changes and AE activities occur during the first cycle, and the stress regime influences the intensity of AE and mechanical changes. These outcomes can benefit studies about subsidence, uplift, fault reactivation, and other physical phenomena impacting the reservoir’s storage capacity, which is affected by cyclic sandstone deformation.

How to cite: Naderloo, M., Hernandez, E., Ramesh Kumar, K., Barnhoorn, A., and Hajibeygi, H.: Effect of stress cycling on the deformation and AE characteristics of reservoir rock from the perspective of energy storage: An experimental study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14277, https://doi.org/10.5194/egusphere-egu23-14277, 2023.

EGU23-16180 | Orals | ERE3.1

Assessing the potential for permanent carbon storage in volcano-sedimentary sequences offshore mid-Norway: initial results from IODP Expedition 396 

John Millett, Sverre Planke, Christian Berndt, Carlos Alvarez Zarikian, Peter Betlem, Marija Rosenqvist, Ben Manton, David Jolley, Simona Pierdominici, Stefan Buenz, and Reidun Myklebust and the Expedition 396 Scientists

International Ocean Discovery Program (IODP) Expedition 396 drilled 21 holes at 10 sites spanning the mid-Norwegian volcanic rifted margin in 2021. Six sites recovered volcanic sequences with one objective of the cruise being to appraise the potential for permanent carbon storage within the offshore volcanic sequences.

This study presents a core-log-seismic and reservoir appraisal of the Kolga High Site U1566 which penetrated a c. 120 m Seaward Dipping Reflector (SDR) sequence beneath a thin Quaternary sediment cover below c. 2100 m water depth. Coring with high average recovery > 65 % through the volcanic sequence revealed a variably altered basaltic lava flow dominated sequence with inter-layered volcaniclastic and siliciclastic sediments, the latter containing granitic clasts eroded from the nearby high. The base of the volcanic sequence was recovered in the cores and marks a sharp transition from sub-aerial lava flows into deeply altered granite.

Shipboard petrophysical and wireline data for Site U1566 are analysed to characterize the SDR sequence and integrated with available seismic data. Whole-Round Multisensor Logger data were collected on cores for natural gamma radiation, bulk density, magnetic susceptibility, and P-wave velocity at 2.5 cm spacing. 588 P-wave caliper measurements along with 2219 point magnetic susceptibility measurements were made on the working-half sections. In addition, a total of 102 discrete samples were taken for moisture and density (MAD) analysis including 2 cm cubes and 34 additional minicore samples which were also tested for ambient permeabilities. Wireline data including gamma, density, P- and S-wave velocity, resistivity, magnetic susceptibility and image log data (micro-resistivity and acoustic) were collected over the main volcano-sedimentary sequence enabling a comprehensive appraisal of the penetrated volcanic sequence.

The volcanic sequence is characterized by vertically stacked compound to simple lava flows showing asymmetrical log profiles with individual flow lobes rarely exceeding c. 3 m in thickness. Primary vesicular porosity exceeds 40 % in fresh unaltered flow margins and decreases to < 10 % in flow interiors and where alteration and secondary mineralization are pervasive. Matrix permeability ranges from microdarcies within flow interiors up to several 10’s of millidarcies within flow margins and up to 100’s of millidarcies within sediment interbeds highlighting significant vertical heterogeneity linked to facies development through the studied sequence. The presence of alteration and fracturing within the studied sequence significantly alter reservoir properties and form key elements, along with facies scaling, that must be incorporated into reservoir appraisal. This pilot study reveals clear reservoir potential within both lava flows and inter-bedded sediments offshore mid-Norway. 

How to cite: Millett, J., Planke, S., Berndt, C., Alvarez Zarikian, C., Betlem, P., Rosenqvist, M., Manton, B., Jolley, D., Pierdominici, S., Buenz, S., and Myklebust, R. and the Expedition 396 Scientists: Assessing the potential for permanent carbon storage in volcano-sedimentary sequences offshore mid-Norway: initial results from IODP Expedition 396, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16180, https://doi.org/10.5194/egusphere-egu23-16180, 2023.

EGU23-16675 | Orals | ERE3.1 | Highlight

DemoStorage - an ATES demonstrator in an urban environment. 

Detlev Rettenmaier, Roman Zorn, Philipp Blum, Menberg Kathrin, Matthias Herrmann, Michael Viernickel, Fabian Eichelbaum, Paul Fleuchhaus, Thorsten Stoeck, Sven Katzenmeier, Hans-Werner Breiner, Hans Jürgen Hahn, and Andreas Fuchs

Aquifer thermal energy storage (ATES) is comparatively rarely used in Germany, in contrast to neighboring countries such as the Netherlands. This also applies to lower temperature ranges of less than 50 °C, which are mostly technically easier to handle than high-temperature storage. Since there is a lack of demonstration plants nationally, the goal of our BMBF-funded joint project “DemoSpeicher” (Development and Monitoring of Seasonal Heat and Cold Storage for the Demonstration of Aquifer Storage) is to implement and scientifically accompany a near-surface low-temperature aquifer storage system (NT-ATES). Within the scope of the project, the entire construction cycle of an NT-ATES is to be covered, which ranges from design and planning to grid integration and commissioning to thermal energy supply. An urban site in Germanys capital Berlin-Mitte was selected for the implementation of the demonstration plant, which is to be converted to climate-friendly heating and cooling concepts at an existing construction site. In addition to the necessary preliminary site investigations for the technical-economic feasibility, questions regarding legal approval requirements will also be presented.

For this reason, a extensive monitoring program is planned, which provides the metrological supervision of the thermal-hydraulic underground processes. Another focus of the project will be possible changes in groundwater chemistry and temperature-sensitive groundwater ecology as a result of thermal loading. Monitoring of energy flows is also planned in order to estimate the thermal energy exchange between the aquifer reservoir and the building's systems engineering. This will include a heating and cooling demand analysis, as well as an assessment of potential synergistic use effects with other technologies that could be used, for example, for thermal loading of aquifer storage. All results will be presented in a coupled thermal-hydraulic modeling of the planned thermal energy storage. The project and the first results of the implementation of an ATES in a densely populated urban area will be presented and discussed in this presentation.

How to cite: Rettenmaier, D., Zorn, R., Blum, P., Kathrin, M., Herrmann, M., Viernickel, M., Eichelbaum, F., Fleuchhaus, P., Stoeck, T., Katzenmeier, S., Breiner, H.-W., Hahn, H. J., and Fuchs, A.: DemoStorage - an ATES demonstrator in an urban environment., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16675, https://doi.org/10.5194/egusphere-egu23-16675, 2023.

EGU23-16856 | Posters on site | ERE3.1 | Highlight

Solid Carbon: Safe and Durable Carbon Storage in Ocean Basalt - From Feasibility to Demonstration to Global Potential 

Benjamin Tutolo, Martin Scherwath, Kate Moran, David Goldberg, Adedapo Awolayo, Laurence Coogan, Curran Crawford, Stan Dosso, Eneanwan Ekpo Johnson, Rachel Lauer, Emma Louis, Sara Nawaz, Terre Satterfield, Angela Slagle, Devin Todd, and Romany Webb

Oceanic crustal basalt rock has been identified to be the most abundant CO2 sequestration reservoir on earth with a total capacity of up to 250,000 Gt of CO2 and the added advantage of the CO2 mineralizing into carbonate rock in the safest and most durable way. Experiments and pilot projects have established geologic carbon storage in basalt on land (e.g. Carbfix in Iceland) but have not been carried out offshore and are therefore required to demonstrate and prove this form of carbon storage offshore. We are presenting the ongoing Solid Carbon project, which is currently in the feasibility stage of demonstrating this concept in the Cascadia Basin offshore Vancouver Island where Ocean Networks Canada operates a cabled ocean observatory, which will be utilized to monitor and verify this form of geologic carbon storage. The demonstration site is at about 2700 m water depth, where the ocean crust is overlain by 200-600 m of sediment acting as a cap for the porous and permeable crustal basalt aquifer (300-500 m thick), underlain by a thick conductive basement. From previous seafloor drilling campaigns, the subsurface and hydrogeology in this area are well known, feeding both into sequestration modelling and also planning the required monitoring. In addition to planning the offshore demonstration experiment, the Solid Carbon project further includes research on social, regulatory and social acceptance as well as adding offshore energy and direct carbon capture to transform the concept into a negative emission technology. We will present the past, present and potential future of this form of geologic carbon storage.

How to cite: Tutolo, B., Scherwath, M., Moran, K., Goldberg, D., Awolayo, A., Coogan, L., Crawford, C., Dosso, S., Ekpo Johnson, E., Lauer, R., Louis, E., Nawaz, S., Satterfield, T., Slagle, A., Todd, D., and Webb, R.: Solid Carbon: Safe and Durable Carbon Storage in Ocean Basalt - From Feasibility to Demonstration to Global Potential, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16856, https://doi.org/10.5194/egusphere-egu23-16856, 2023.

EGU23-17508 | Orals | ERE3.1

Predicting the frequency of seismic events for subsurface engineering projects usingbackground microseismicity data 

Eleni Dafnioti, Georgios Chatzopoulos, Stella Pytharouli, Filippos Vallianatos, and Rebecca Lunn

The general public is concerned about subsurface energy projects and their link to seismic activity.
However, in order to meet the Net Zero requirements, low carbon technologies involving fluid
injection into the subsurface, such as geothermal, Carbon Capture and Storage (CCS) and gas
storage, must be developed and implemented. In an effort to enhance their confidence, it is
important to comprehend the seismogenic effects and the triggering mechanism that such
technologies could have in a region.
The frequency of occurrence of microearthquakes (earthquakes with magnitude &lt; ML0 in the
Gutenberg – Richter scale) in natural faults can provide crucial details about the evolution of
seismicity of a region and the geological structures that support this. The permanent seismic
monitoring networks, due to their detection threshold on small magnitude earthquakes (&lt; ML1), do
not enable for the long – distance recording of all microearthquakes. These events have higher
frequencies that attenuate fast, making detection at stations 10s or more kilometres away difficult,
if not impossible.
In order to determine whether microearthquakes share the same characteristics as larger
earthquakes and whether they can be used as a precursor to the occurrence of larger earthquakes,
this research focuses on the study of the characteristics of natural microseismicity (frequency of
occurrence, magnitude distribution, depth of hypocentres etc.). In July 2022, we deployed a
temporary microseismic monitoring network in the southern Heraklion prefecture (Crete, Greece) in
collaboration with the Hellenic Seismological Network of Crete with the aim of recording very small
in magnitude earthquakes (within the range of -0.5 &lt; M &lt; 3, i.e. two orders of magnitude below the
current completeness magnitude of M c 2.0). The network consisted of seven short period
seismometers, one of which was placed in the centre of a nearly circular geometry with the
remaining six distributed around it at a radius of approximately 6.1km. This geometry provided a
good azimuthal coverage for determining the hypocentres.
In this work, we present analysis and results of the microseismic data collected from our local
monitoring network. We find a significantly larger number of microseismic events than that reported
for the same time period within 50 km distance from the central station of our local network in the
published seismic catalogue by the National Observatory of Athens. The number of detected events
we report here refers to only those events that can be visually observed in the recordings. The real
number of smaller in magnitude events is larger but obscured by noise. We use the detected
microseismic events to populate the Gutenberg Richter magnitude distribution for lower magnitude

events and discuss the implications on the existing Gutenberg Richter magnitude distribution for the
region as derived from events recorded by the permanent seismic network in Crete.

How to cite: Dafnioti, E., Chatzopoulos, G., Pytharouli, S., Vallianatos, F., and Lunn, R.: Predicting the frequency of seismic events for subsurface engineering projects usingbackground microseismicity data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17508, https://doi.org/10.5194/egusphere-egu23-17508, 2023.

EGU23-17538 | Posters on site | ERE3.1

Evaluation of the geochemical impact of biomethane and natural gasmix injection in sandstone aquifer storage 

Camille Banc, Irina Sin, Lau de Windt, and Anelia Petit

EU is seeking to rapidly replace part of the natural gas usually stored in deep saline aquifers
by its renewable analogue, i.e. biomethane. While natural gas is depleted in oxygen, up to
10 000 ppm of O2 can be measured in biomethane. But to date, the geochemical impact of
the injection of a gas mix containing natural gas (thus CH4 and CO2) and biomethane (thus
oxygen) in deep saline aquifer has never been studied. The objective of this study is to
evaluate the resilience of geological storage to oxygen injection and predict the evolution
of the quality of the formation water, the gas plume and the rock formation. To do so,
multiple injection scenarios with various gas quality were tested using multiphase reactive
transport modeling. The gas mixtures were injected in two different deep saline aquifers in
the Paris Basin (France) whose petrophysical and geochemical characteristics were
reproduced during the simulation. Site 1 was a felspathic sandstone with clay cement and
site 2 was a sandstone with clay-calcareous cement.


One dimensional radial flow model evidenced that in both sandstones, the injection of gas
mix induced an acidification of the solution from pH~8 to pH~6. The injected oxygen
originating from biomethane was quickly consumed during pyrite oxidation and
contributed to the acidification of the formation water close to the injection point. However,
the injection of 1% mol fraction of CO2(g) contained in the gas mix was the main acidification
factor. Model demonstrated that the sandstones pH buffering capacity relied upon three
geochemical processes (i) calcite dissolution, (ii) feldspar dissolution and (iii) clays
dissolution and sorption capacity. These three pH-buffers were efficient for oxygen contents
from 10 to 1000 ppm. Models predicted that the gas mix injection could induce minimal but
long-term change in the nature of mineral phases but without significantly impacting the
porosity. Overall, the gas quality was preserved in both sandstones. This result was
evidenced with the modeling of entire gas injection and withdrawal scenario. CO2(g)
exsolution, and to a lesser extent H2S(g) exsolution, could occur during these cycles. In
addition, this study through modeling results concluded that the injection of biomethane
did not significantly change gas-water-rocks interactions compared to those of natural gas
injection. This study also evidenced that the detailed results were largely site-dependent.

How to cite: Banc, C., Sin, I., de Windt, L., and Petit, A.: Evaluation of the geochemical impact of biomethane and natural gasmix injection in sandstone aquifer storage, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17538, https://doi.org/10.5194/egusphere-egu23-17538, 2023.

EGU23-1086 | Orals | ERE3.3

Advection in granitic rock matrix: Modeling a radionuclide tracer transport experiment at the Grimsel Test Site. 

Josep M. Soler, Deby Jurado, Maarten W. Saaltink, Lurdes Martínez, Juan J. Hidalgo, G. William Lanyon, and Andrew J. Martin

Within the GTS-LTD project (Grimsel Test Site – Long-Term Diffusion), a field radionuclide tracer transport experiment in unfractured granitic rock was performed. Grimsel groundwater containing several tracers (3H as HTO, 36Cl-, 22Na+, 134Cs+, 133Ba2+) was continuously circulated through a packed-off borehole and the decrease in tracer concentrations in the liquid phase was monitored for a period of 1266 days (05/03/2014 – 22/08/2017). Additionally, tracer breakthrough was monitored in an observation borehole a few cm away.

Initial modeling of the experiment (1D radial) showed that the evolution of tracer concentrations seemed to depart from the expected trend after some time, with concentrations in the injection borehole decreasing faster than expected from pure diffusive transport. Additional 2D calculations (section normal to the boreholes) were performed to check the possible effect of advection through the rock matrix. Advection could explain the evolution of concentrations in the injection borehole, but could not fully explain the measurements in the observation borehole.

Rock samples around the experimental section were collected right after the end of the experiment, allowing the measurement of tracer distributions in the rock. The observed patterns for the non-sorbing tracers (HTO, 36Cl-) showed clear preferential transport directions, consistent with advective flow towards the gallery from which the boreholes were drilled. Final 3D modeling of the experiment can explain the measured concentrations in the boreholes and in the rock. Tracer transport is affected by both diffusion and advection through the granitic rock matrix. Also, in situ accessible porosities (about 0.0014) are smaller than those measured in rock samples (about 0.009), pointing to the destressing of the rock samples after drilling.

How to cite: Soler, J. M., Jurado, D., Saaltink, M. W., Martínez, L., Hidalgo, J. J., Lanyon, G. W., and Martin, A. J.: Advection in granitic rock matrix: Modeling a radionuclide tracer transport experiment at the Grimsel Test Site., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1086, https://doi.org/10.5194/egusphere-egu23-1086, 2023.

EGU23-1181 | ECS | Orals | ERE3.3

Impact of seal configuration and pore fluid type on ion transport and cation exchange in bentonite in semi-technical scale Sandwich sealing experiments 

Eleanor Bakker, Franz Königer, Matthias Gruner, Martin Hofmann, Rainer Schuhmann, and Katja Emmerich

Disposal concepts for high-level radioactive waste involve underground repositories and involving an engineer barrier system (EBS) to ensure safe containment of radionuclides. Shaft and drift seals form part of the EBS and typical sealing concepts involve bulk bentonite. However, bulk bentonite is susceptible to the formation of preferential fluid flow pathways, which impact bentonite hydration and barrier performance. The Sandwich sealing system (CMM, Nüesch et al., 2002) is an alternative solution, and consists of alternating sealing segments (DS) of bentonite and equipotential segments (ES) which allow for homogeneous saturation of the bentonite.

Semi-technical scale experiments (d = 80 cm, h = 180 cm) were required to probe the impact of different segment configurations, pore fluids, and German Ca-Mg-bentonites on the performance of the Sandwich sealing system. Columns were saturated with various artificial fluids mimicking either pore fluid of Opalinus Clay or rock salt. Experiments were terminated when fluid was detected in the final DS, typically a few hundred days duration. Experimental columns were dismantled with up to 20 sampling points on up to 20 sampling levels through the column to provide a 3D snapshot of the system via chemical and physical characterisation of samples.

Water content decreased through bentonite sampling levels from 30-40% adjacent to the fluid inflow to <15% in the final level. Saturation was relatively consistent in DS segments, despite the presence of artificial hydraulic defects. Stark differences were observed between neighbouring ES and DS. Regardless of pore fluid and segment configuration, highest ion concentrations coincided with higher water content and were higher in DS sampling levels directly adjacent to ES. Position of a sampling level in the column was indicative of Ca-Mg- to Na-bentonite transformations as longer exposure time to the pore fluid increased the level of soluble Na+ for interlayer Ca2+ and Mg2+. Concentrations of soluble ions with DS and ES showed little variation. Presence of artificial hydraulic defects only impacted soluble ion concentration in the immediate vicinity of the defect, otherwise segments had relatively uniform ion concentrations. Despite the long duration of the experiments, Ca2+ and Mg2+ persist in the interlayer of DS smectite after > 400 days indicating ongoing cation exchange contribution of interlayer cations to pore fluid composition. Bentonite soluble phases also contribute to pore fluid composition and indicate the systems snapshotted here are far from equilibrium.

Bentonite swelling in DS near fluid inflow caused low final fluid flow rates, indicating the Sandwich sealing system behaved as expected and reduced hydraulic conductivity. Results show a robust system suitable for installation using a variety of different Ca-Mg-bentonites, and in different locations with exposure to pore fluids with low or high salt concentrations, without affecting long-term performance. The Sandwich sealing system is also highly effective at minimising the formation and impact of preferential flow pathways. The authors thank the German Federal Ministry for Economic Affairs and Energy for funding the Sandwich-HP (FKZ 02E11799 A+B+C).

How to cite: Bakker, E., Königer, F., Gruner, M., Hofmann, M., Schuhmann, R., and Emmerich, K.: Impact of seal configuration and pore fluid type on ion transport and cation exchange in bentonite in semi-technical scale Sandwich sealing experiments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1181, https://doi.org/10.5194/egusphere-egu23-1181, 2023.

EGU23-1462 | ECS | Orals | ERE3.3 | Highlight

Application of Ubiquituous-Joint Model for Modelling Fractures in Crystalline Rock Formations: Preliminary Studies 

Ajmal Gafoor, Christian Müller, and Philipp Herold

Rock salt, claystone and crystalline rock are considered as potential host rocks for the disposal of high-level radioactive waste in Germany. Rock types, properties, and composition determine how these potential geologic barriers contribute to the containment, isolation, and retardation of the radioactive waste. Crystalline rocks are anisotropic and heterogeneous due to the presence of discontinuities. Therefore, the consideration of discontinuities in numerical models is crucial with regard to the performance assessment of radioactive waste repository systems. The project aims at developing a modelling strategy that enables effective modelling of fractures in crystalline rock. The continuum modelling approach using a Ubiqitous-Joint model is adopted to model the rock fractures. Its applicabilty for large-scale anyalses of anisotropic rock masses is being investigated by developing the numerical models based on predefined structural-geologic information. The influence of fracture orientations on the modelling of the rock masses will be studied, and their impact on performance assessments for the safe disposal of high-level radioactive waste in crystalline rock will be assessed.

How to cite: Gafoor, A., Müller, C., and Herold, P.: Application of Ubiquituous-Joint Model for Modelling Fractures in Crystalline Rock Formations: Preliminary Studies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1462, https://doi.org/10.5194/egusphere-egu23-1462, 2023.

EGU23-1504 | Orals | ERE3.3

The Sandwich seal systems: A large-scale shaft sealing experiment at the Mont Terri rock laboratory – Installation and materials 

Katja Emmerich, Eleanor Bakker, Christopher Rölke, Franz Königer, Martin Hoffmann, David Jaeggi, Jürgen Hesser, Uwe Glaubach, Maria Victoria Villar, Ralf Diedel, Rainer Schuhmann, and Klaus Wieczorek

Shaft seals are part of the engineered barrier system (EBS) that belongs to the multi-barrier system for deep underground repositories of high-level radioactive waste. The German regulator demands that with respect to the reliability of containment, the interplay of barriers has to be optimized in diverse redundancy and shaft seals should also be constructed of diverse redundant components. The design of shaft seals for generic site models of Germany contains hydraulic sealing elements that should be realized as Sandwich sealing systems. In contrast to conventional hydraulic seals of monolithic bentonite the Sandwich sealing system consists of sealing segments (DS) of bentonite and hydraulically conductive equipotential segments (ES) (Nüesch et al., 2002). Formation water that is penetrating the hydraulic seal via preferential flow paths is contained in the ES and evenly distributed over the cross section of the seal. Thus, a more homogeneous hydration and swelling of the DS is obtained.

In July 2019 a large-scale experiment was launched at the Mont Terri rock laboratory (MTRL) to demonstrate the feasibility of installation, to investigate the saturation process and to assess the sealing effectiveness. The in-situ experiment consists of two experimental shafts of 1.18 m diameter and 10 ‑ 12.6 m depth in the sandy facies of the Opalinus Clay. The DS in both shafts are constructed of German Ca-bentonites from Bavaria (Calcigel) and Westerwald region (Secursol), respectively. Both Sandwich sealing systems are hydrated with Pearson water type A3 and are intensely monitored, together with the surrounding rock. The in-situ experiment is accompanied by extensive laboratory work and numerical modelling. The laboratory work comprises mineralogical analyses, Oedometer tests, MiniSandwich experiments and semi-technical scale experiments. The variety of experiments on different scales and with different model geometries allow us to recognize and understand different scale-dependent and nonlinear effects on the system behaviour.

The presentation will focus on the differences of the two German bentonites with respect to HMC properties and the installation of the Sandwich sealing systems in both shafts at MTRL. The bentonite from Westerwald is characterized by a high smectite content and had to be blended with non-swellable material to adapt expected maximum swelling pressure to the specific site conditions of the in-situ experiment. Both bentonites were then installed as binary mixtures of bentonite pillows and bentonite granular material with similar EMDD, water content and dry density.

Acknowledgment

The Sandwich pre-project and the Sandwich in-situ experiment were/are funded by the German Federal Ministry for Economic Affairs and Energy under contracts 02E11587 and 02E11799.

How to cite: Emmerich, K., Bakker, E., Rölke, C., Königer, F., Hoffmann, M., Jaeggi, D., Hesser, J., Glaubach, U., Villar, M. V., Diedel, R., Schuhmann, R., and Wieczorek, K.: The Sandwich seal systems: A large-scale shaft sealing experiment at the Mont Terri rock laboratory – Installation and materials, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1504, https://doi.org/10.5194/egusphere-egu23-1504, 2023.

In order to provide basic data for selecting candidate sites for high-level radioactive waste geological disposal, the drilling project is being carried out to investigate the deep environment for each type of bedrock existing on the Korean Peninsula. Securing 10 boreholes with a depth of 750 m is the final goal of the drilling project, which is planned for 5 years from 2020 to 2024. Two boreholes are being secured for sedimentary, plutonic, volcanic, metamorphic rock, respectively, and two additional boreholes will be secured for the rock types that require further investigation. As of December 2022, three boreholes were secured for sedimentary rocks, two for plutonic rocks, and one for metamorphic rocks. The boreholes were targeted for shale, granite and gneiss, respectively. To provide precise and reliable basic data, multidisciplinary (geological, geophysical, geochemical, hydrogeological, rock mechanics, etc.) studies have been conducted using drilling holes and cores. These research results are expected to be used as important basic data for selecting candidate sites for high-level radioactive waste geological disposal in Korea.

How to cite: Park, J.-Y. and Cheon, D.-S.: Drilling project for deep environmental geoscientific investigation for each type of bedrock for HLW geological disposal in Korea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1794, https://doi.org/10.5194/egusphere-egu23-1794, 2023.

EGU23-1992 | ECS | Orals | ERE3.3 | Highlight

Uncertainties in geomechanical models – A novel concept to data-driven stress modelling 

Moritz Ziegler and Oliver Heidbach

The undisturbed stress state of the subsurface is a key parameter for the assessment of geological barrier integrity in deep geological repositories. A robust knowledge of the stress state is required for forward simulations that predict the evolution of the deep geological repository during building, canister emplacement, and post-closure phase. However, stress magnitude data will always be sparse and point-wise and thus not sufficient to allow a continuous characterization of the stress field. 3D geomechanical-numerical models are incorporated to mitigate this shortcoming. The significance of such a model is tied to the stress magnitude data records whose availability is generally low and subject to measurement errors. In turn, the uncertainties of the modelled 3D stress state are large which lowers the predictive values of the ensuing forward models. Here, we present a novel approach to reduce the uncertainties of a modelled stress state (Ziegler and Heidbach, 2023).

In a first step we estimate all possible and realistic stress states with respect to the available stress magnitude data and their uncertainties. This provides an overall quantification of the range of stress states that are supported by data. In a second step we limit this usually very large range of stress states using additional indirect stress information to determine upper and lower limits. Formation integrity tests (FITs) are used as a lower limit for the stress state. Observed borehole wall failures (drilling induced tensile fractures and borehole breakouts) provide an estimate of the quality of a modelled stress state in relation with estimations of the rock strength. Observed seismicity and observed seismological quiescence in connection with a failure criterion is used as an upper constraint of the stress state. These additional data allow to identify the probability of a modelled stress state based on its agreement with observations. A weight is estimated for each modelled stress state in a formalized Bayesian approach. This allows an improvement in the significant interpretation of the initial stress state in terms of its robustness and transparency.

Results from an explanatory model and a case study in the Bavarian Molasse Basin show an improved significance in terms of clearly reduced model uncertainties. The amount of uncertainty reduction, however, depends significantly on the quality, suitability and assessment of the additional information.

 

Reference:

Ziegler, M. O., & Heidbach, O. (2023). Bayesian quantification and reduction of uncertainties in 3D geomechanical-numerical models. Journal of Geophysical Research: Solid Earth, 128, e2022JB024855. https://doi.org/10.1029/2022JB024855

How to cite: Ziegler, M. and Heidbach, O.: Uncertainties in geomechanical models – A novel concept to data-driven stress modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1992, https://doi.org/10.5194/egusphere-egu23-1992, 2023.

EGU23-2247 | Orals | ERE3.3 | Highlight

Disposal of HLW and ILW/LLW at the same site: challenges in an international context 

Ute Maurer-Rurack, Andreas Poller, Susie Hardie, Joachim Poppei, Marie Voss, and Paul Smith

Title:  Disposal of HLW and ILW/LLW at the same site: challenges in an international context

Authors:  Maurer-Rurack, U.*, Poller, A., Hardie, S., Poppei, J., Voss, M. **, Smith, P. ***

* Federal Office for the Safety of Nuclear Waste Management (BASE), Berlin, Germany

** CSD Ingenieure AG, Switzerland

*** Safety Assessment Management GmbH, Switzerland

 

Abstract:

Germany is looking for the site with best possible safety for an HLW (high level waste) repository. In the site selection procedure of Germany three host rocks: rock salt, clay and crystalline rock are considered. In accordance with §1 (6) of the StandAG (German Site Selection Act), an additional disposal of ILM/LLW (intermediate level/low level waste) might be allowed at the same site, provided that its characteristics satisfy the best possible safety criteria for the sole disposal of HLW waste. This point will be addressed within the framework of preliminary safety investigations pursuant to §27 (5) of the StandAG in the individual phases of site selection process for the HLW repository, according to the current state of science and technology.

The GemEnd research project (2022, in press) investigates the possible mutual influence of these different types of repositories at the same site and the resulting safety-relevant consequences for the HLW repository system in Germany.

This contribution provides an overview of the currently existing international disposal programs of non-heat-generating waste (ILW/LLW) and heat-generating waste (HAW) at the same site in the following countries: Belgium, France, Finland, Germany, Japan, Sweden, Switzerland and the United Kingdom.

The IAEA (International Atomic Energy Agency) also considers co-disposal of HLW and ILW/LLW as an option that has advantages over separate repositories. But particular critical interactions caused by gas formation and gas transport as well as interactions of cementitious materials with other engineered components and the host rocks should not be forgotten (IAEA 2009, 2018).

On this basis, existing international disposal programs for HLW and ILW/LLW at the same site are compared with each other. Important similarities and differences for the transferability of the findings to the site selection procedure in Germany are presented. Finally, the approach of other countries can contribute to a better assessment of the safety implications in Germany.

 

How to cite: Maurer-Rurack, U., Poller, A., Hardie, S., Poppei, J., Voss, M., and Smith, P.: Disposal of HLW and ILW/LLW at the same site: challenges in an international context, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2247, https://doi.org/10.5194/egusphere-egu23-2247, 2023.

In the context of safety assessments for nuclear waste repositories, it is essential to quantify potential radionuclide migration. This can only be done by the application of numerical simulations due to the required spatial (>100 m) and temporal scales (1 Ma), whereby resulting migration lengths highly depend on the underlying model concept and data [1-4].

Migration of uranium, the main component of spent fuel, is used here in regard to the potential host rock Opalinus Clay as an example for models close to a real case application. For this, one-dimensional diffusion simulations were conducted with PHREEQC applying mechanistic surface complexation models to account for sorption processes as a function of the geochemical conditions [1].

Extensive numerical studies for the hydrogeological system at the underground rock laboratory Mont Terri (Switzerland) have shown that migration lengths can vary from 5 m using an experimentally determined distribution coefficient Kd (m³/kg) up to 80 m applying more advanced approaches [1-4]. However, these results represent maximum scenarios. At Mont Terri, geochemical gradients established towards the embedding aquifers due to the Jura folding and associated erosion history [2, 3]. For a potential disposal site, more constant conditions without a gradient are favoured. Furthermore, the impact of the engineered barriers and with that a reduction of the source term was not taken into account in previously. Therefore, simulations are conducted for a site with less steep geochemical gradients compared to Mont Terri as well as for decreased source term concentrations.

First, measured pore water profiles from Schlattingen (Switzerland) were modelled, where geochemical gradients are less pronounced. Second, they serve as initial conditions for subsequent uranium migration driven by decreasing source term concentrations. The comparison of resulting migration lengths with the mentioned maximum scenarios shows that uranium migration is decreased by several metres. Consequently, the selection of initial and boundary conditions is essential for a reliable quantification of radionuclide migration.

References:

[1] Hennig, T. et al. (2020): Simulation of diffusive uranium transport and sorption processes in the Opalinus Clay. Applied Geochemistry 123, 104777. DOI: 10.1016/j.apgeochem.2020.104777

[2] Hennig, T. and Kühn, M. (2021): Potential uranium migration within the geochemical gradient of the Opalinus Clay system at the Mont Terri. Minerals 11 (10), 1087. DOI: 10.3390/min11101087

[3] Hennig, T. (2022): Uranium migration in the Opalinus Clay quantified on the host rock scale with reactive transport simulations, PhD Thesis, Potsdam: Universität Potsdam, 161 p. DOI: 10.25932/publishup-55270

[4] Hennig, T. and Kühn, M. (2022): Reactive transport simulations of uranium migration in the Opalinus Clay depend on ion speciation governed by underlying thermodynamic data. Advances in Geosciences 58, 11–18, DOI: 10.5194/adgeo-58-11-2022

How to cite: Hennig, T. and Kühn, M.: Uranium migration lengths in Opalinus Clay depend on geochemical gradients, radionuclide source term concentration and pore water composition, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2754, https://doi.org/10.5194/egusphere-egu23-2754, 2023.

EGU23-2875 | Posters on site | ERE3.3

Modelling the geochemical behaviour of aqueous solutions in the Opalinus Clay as part of the Mont Terri BN Experiment using PHREEQC 

Torben Weyand, Michael Jendras, Nele Bleyen, Katrien Hendrix, and Christoph Borkel

In several countries, claystone is a possible host rock for a radioactive waste repository. The reducing capacity of claystone has a strong impact on the speciation, solubility, retention and transport properties of redox-sensitive radionuclides. Since redox-sensitive radionuclides are more mobile in a more oxidised state, the reducing capacity of claystone is an important feature regarding the long-term safety of nuclear waste disposal.

To study the influence of oxidising components such as nitrate (which is for example a component of bituminised waste) on the reducing capacity of claystone and radionuclide mobility, ongoing in situ tests are carried out in the Opalinus Clay at the Mont Terri Rock Laboratory (Switzerland) as part of the Bitumen-Nitrate-Clay interaction (BN) experiment. These in situ tests are performed in a vertical borehole containing three packed-off intervals (water chambers), which allow to monitor and change the hydrochemical conditions in the different intervals. Moreover, in recent years, the fate of selenate (SeO42-) in the Opalinus Clay has been studied within the BN experiment. This includes the possible microbial reduction of Se(VI) to Se(IV) (in presence of nitrate), as this could contribute to the retention of selenium within the geosphere. Selenate was selected since 79Se is one of the main dose-contributing radionuclides in long-term safety analyses for radioactive waste disposal in claystone.

In each of the past in situ tests, artificial pore water with a pH of approximately 7.8 and containing nitrate and/or selenate and sometimes electron donors (acetate and H2), is injected in the borehole. Thereby all ongoing processes are studied at a near-neutral pH. In future experiments, the influence of an increased pH on the fate of nitrate (and later on selenate) and on the reducing capacity of the claystone will be investigated, since cement, for example used as an engineered barrier in a repository, may cause alkaline conditions. Therefore, it is envisaged to increase the pH of the water within the borehole slowly in a stepwise manner - first up to pH 9-10 - by injecting solutions containing NaOH, KOH or cementitious pore water.

In this study, geochemical calculations are performed using the program PHREEQC to evaluate the increased pH in the intervals on the surrounding claystone and the borehole water. The result of this modelling will show the aqueous speciation and mineral dissolutions and precipitations. An evaluation of mineral precipitations under the given conditions is necessary since clogging of the water lines in the experiment should be avoided. Therefore, an understanding of the geochemical interactions of the injected aqueous alkaline solutions with the surrounding claystone and pore water is necessary. Within the context of nuclear waste disposal in claystone, the database ThermoChimie provides suitable thermodynamic data and will be used for the simulations. To assess the precipitation of secondary phases for cementitious materials, the thermodynamic database CEMDATA might be applied for comparison. Finally, the range of pH that can be reached in the interval solutions will be assessed and the amount of precipitated minerals will be calculated.

How to cite: Weyand, T., Jendras, M., Bleyen, N., Hendrix, K., and Borkel, C.: Modelling the geochemical behaviour of aqueous solutions in the Opalinus Clay as part of the Mont Terri BN Experiment using PHREEQC, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2875, https://doi.org/10.5194/egusphere-egu23-2875, 2023.

EGU23-3224 | Orals | ERE3.3

The Sandwich seal systems: A large-scale shaft sealing experiment at the Mont Terri rock laboratory – hydration and monitoring 

Klaus Wieczorek, Katja Emmerich, Rainer Schuhmann, Jürgen Hesser, Markus Furche, Hua Shao, David Jaeggi, Senecio Schefer, José Luis García-Siñeriz, Franz Königer, Juan Carlos Mayor, Simon Norris, and Chang Seok Kim

Safety of deep underground repositories for high-level radioactive waste is ensured by a multi-barrier system consisting of the geological barrier (host rock) and the engineered barrier system (EBS). Shaft seals are a major part of the EBS. The German regulator demands that the interplay of barriers has to be optimized in diverse redundancy to increase reliability and robustness of the barrier system. Shaft seals should also be constructed of diverse redundant components. The design of shaft seals for generic site models of Germany includes hydraulic sealing elements that are to be realized as Sandwich sealing systems. In contrast to conventional hydraulic seals of monolithic bentonite the Sandwich sealing system consists of sealing segments (DS) of bentonites and hydraulically conductive equipotential segments (ES) (Nüesch et al., 2002). Formation water, that is penetrating the hydraulic seal via preferential flow paths is contained in the ES and evenly distributed over the cross section of the seal. Thus, a more homogeneous hydration and swelling of the DS is obtained.

In July 2019, after a two-years planning phase (Emmerich et al., 2019), a large-scale experiment was launched at the Mont Terri rock laboratory (MTRL) to demonstrate the feasibility of installation, to investigate the saturation process, to qualify monitoring techniques, and to assess the sealing effectiveness. The in-situ experiment is supported by laboratory experiments at different scales and by numerical simulation.

The in-situ experiment consists of two experimental shafts of 1.18 m diameter and 10 ‑ 12.6 m depth located in the sandy facies of the Opalinus Clay. The DS in both shafts are constructed of German Ca-bentonites, while the ES consist of fine-grained sand. Both Sandwich sealing systems are hydrated with Pearson water type A3. Both shafts were drilled in 2020 and Shaft 1 was installed subsequently. Hydration of Shaft 1 started in May 2021. Shaft2 was installed about two years later so that experience from Shaft 1 operation could be included. Additionally, an excavation damaged zone had the chance to develop close to the shaft wall.

The presentation will focus on the operation phase of the two shafts. Measurement systems and monitoring results, in terms of the evolution of water content, stress, pore pressure, and relative humidity in the sealing systems will be presented.

Acknowledgment

The Sandwich pre-project and the Sandwich in-situ experiment were/are funded by the German Federal Ministry for Economic Affairs and Energy under contracts 02E11587 and 02E11799.

How to cite: Wieczorek, K., Emmerich, K., Schuhmann, R., Hesser, J., Furche, M., Shao, H., Jaeggi, D., Schefer, S., García-Siñeriz, J. L., Königer, F., Mayor, J. C., Norris, S., and Kim, C. S.: The Sandwich seal systems: A large-scale shaft sealing experiment at the Mont Terri rock laboratory – hydration and monitoring, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3224, https://doi.org/10.5194/egusphere-egu23-3224, 2023.

EGU23-3988 | ECS | Posters on site | ERE3.3 | Highlight

Effects of Inhomogeneity and Anisotropy on THM Simulations 

Aqeel Afzal Chaudhry, Chao Zhang, Oliver Ernst, and Thomas Nagel

When modeling the material properties of host rocks for THM simulations for the purpose of barrier integrity investigations in deep geological disposal of radioactive waste, there are numerous modeling aspects to consider. We consider the simple case of stationary Darcy flow in a two-dimensional medium to convey the basic phenomena when constructing a suitable model for host rock permeability with a special focus on the treatment of anisotropy occurring at different spatial scales and the associated uncertainty. If complete information were available, permeability would be a known function of space, and hydrological features such as inhomogeneity (spatial variability) and anisotropy (direction-dependence) can be expressed by spatially varying and tensor-valued permeability coefficients. In reality, uncertainty is present and needs to be considered. One approach is to model the rock medium as piecewise homogeneous in such a way that the permeability values in each homogeneous subregion (e.g. geological layer) are modeled as random variables. The permeability values at any two locations of the same subregion are then completely correlated. Randomness with a more general structure can be modeled by random fields, the realizations of which are functions of space which are not necessarily constant. A common modeling choice is that of a Gaussian random field for log permeability, which is completely determined by its mean and two-point correlation function. Anisotropy can now occur both in the statistical covariance structure, resulting in different correlation lengths along principal axes, and in the hydraulic properties, leading to tensor-valued random fields the realizations of which are anisotropic tensors for which the underlying covariance structure may, in addition, display statistical anisotropy.

In this work we present a number of simulations designed to illustrate the effects of inhomogeneity, randomness as well as statistical and hydraulic anisotropy.

How to cite: Chaudhry, A. A., Zhang, C., Ernst, O., and Nagel, T.: Effects of Inhomogeneity and Anisotropy on THM Simulations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3988, https://doi.org/10.5194/egusphere-egu23-3988, 2023.

EGU23-4037 | Posters on site | ERE3.3

Hydrogeological Change in Borehole Damage Zone (BDZ) by Expanding Diameter of Borehole 

Kyung-Woo Park, Byeong-Hak Park, and Sung-Hoon Ji

This presentation describes the results of a study on the change in hydrogeological properties that can occur in natural barriers after excavating a disposal hole. We performed a series of hydraulic tests at a borehole in the KURT area to understand the change in the hydrogeological characteristics around the drilling-induced damage zone after excavating the disposal hole. As a result, it was confirmed that the transmissivity of fractured rock was increased from several times to tens of times. It was caused by the drilling-induced damage generated around the borehole surface by expanding the diameter of the borehole. In particular, the change in transmissivity was increased in the test section with low transmissivity. In the end, the permeability in the borehole damage zone had a high transmissivity overall, and the hydraulic connection within the borehole damage zone was expanded. Additionally, it was confirmed that the range of hydrogeological influence of the borehole damage zone decreases as the distance from the borehole hole. The results, which analyzed the hydrogeological effect of the borehole damage zone by the borehole expansion, differ in size from the actual disposal hole in the repository. However, compared to large-scale research on an excavation damage zone conducted in tunnels, researchers can easily access it. Therefore, it will be used in various studies to analyze qualitative phenomena.

How to cite: Park, K.-W., Park, B.-H., and Ji, S.-H.: Hydrogeological Change in Borehole Damage Zone (BDZ) by Expanding Diameter of Borehole, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4037, https://doi.org/10.5194/egusphere-egu23-4037, 2023.

EGU23-4206 | ECS | Orals | ERE3.3

Mechanical/Hydraulic Aperture of 3D-Printed Joints in Relation to JRC and Surface Geometry  

Tan-Minh Le, Xuan-Xinh Nguyen, and Jia-Jyun Dong

A thorough understanding of the hydro-mechanical behavior of rock joints is essential since joints typically serve as weak planes and fluid channels within rock masses. Joint roughness, among other factors, dominates the mechanical and hydraulic behavior of rock joints directly. Since 1970s, the joint roughness coefficient (JRC) has been used extensively to quantify joint roughness. As a result of using this variable in empirical equations, we can now anticipate the fluid flow characteristics under stresses. However, the validity of utilizing a single parameter to express the complicated geometry of joint surfaces should be testified. We used three-dimensional (3D) printers to produce a large number of joint samples with similar JRC (2 - 4) but varying surface geometry, including matched and mismatched joint surfaces. The mechanical and hydraulic apertures (E and e) of the printed joint samples were determined utilizing high confining pressure, permeability/porosity measurement equipment (YOKO2). The relationship between E and e can thus be quantified. The results indicate that the stress-dependent mechanical apertures of matched and mismatched joints with similar JRC is significantly different and result in the difference in e-E relationship. However, the measured e-E relationship is quite similar for matched or mismatched smooth joints regardless of joint surface geometry. To conclude, JRC is an appropriate index of smooth joint roughness for representing the stress-dependent e and E and accompanying e-E relationship. 

 

 

How to cite: Le, T.-M., Nguyen, X.-X., and Dong, J.-J.: Mechanical/Hydraulic Aperture of 3D-Printed Joints in Relation to JRC and Surface Geometry , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4206, https://doi.org/10.5194/egusphere-egu23-4206, 2023.

EGU23-5144 | Posters on site | ERE3.3 | Highlight

Development of an optimized, combined and high-resolution imaging method for the site investigation of radioactive repositories (DOSIS) 

Hui Ding, Maximilian Scholze, Eva Schörner, Sonia Sortan, Thomas Hertweck, Lars Houpt, Thomas Bohlen, Niklas Kühne, Tomi Jusri, Felix Hlousek, and Stefan Buske

3D seismic measurements are a tool for high-resolution structural exploration of the subsurface using artificially generated seismic waves. Depending on the acquisition geometry and the seismic source, structures can be examined at depths ranging from a few meters to more than 10 km. The accuracy of the geological layer boundaries in the depth image resulting from the field data depends heavily on the quality and the details of the physical earth model and the imaging algorithms used.

The "DOSIS" project was initiated in order to design an optimized, combined and high-resolution method to facilitate finding answers for important geophysical and geological questions in the exploration of repository sites in Germany in the future. In the framework of the "DOSIS" project, the simulation of elastic waves using finite differences and the associated full-waveform inversion as well as the Fresnel-volume migration are further developed, so that seismic anisotropy and inelastic attenuation can be taken into account for a detailed characterization of the subsurface. These methods are tested and validated using both, synthetic data and real data in the form of a massive high-quality 3D seismic data set acquired in 2020 in the area of the "Asse" salt structure in Lower Saxony and provided by BGE.

How to cite: Ding, H., Scholze, M., Schörner, E., Sortan, S., Hertweck, T., Houpt, L., Bohlen, T., Kühne, N., Jusri, T., Hlousek, F., and Buske, S.: Development of an optimized, combined and high-resolution imaging method for the site investigation of radioactive repositories (DOSIS), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5144, https://doi.org/10.5194/egusphere-egu23-5144, 2023.

EGU23-6380 | ECS | Orals | ERE3.3 | Highlight

Automated criticality calculations for radionuclide migration scenarios in the geological disposal of radioactive waste. 

Adam Paxton, Jiejie Wu, David Applegate, Andrew Price, Tim Hicks, and Callum Eldridge

Nuclear Waste Services (NWS) goal is to ensure radioactive waste produced in the UK is managed safely and securely. This includes being responsible for the siting and construction of the UK’s Geological Disposal Facility (GDF) infrastructure for higher-activity radioactive waste. This waste includes large quantities of fissile nuclides, therefore a safe GDF design must account for the risk of a subsurface criticality event (i.e. a chain fission reaction). Fissile nuclides will be dispersed in a GDF over post-closure timescales governed by uncertain processes such as corrosion, radioactive decay, diffusion and reactive transport. To account for the uncertainty in the future evolution of a GDF, safety assessments apply probabilistic modelling and compute thousands of radionuclide migration scenarios. Previous assessments using existing models have used expert human judgement to manually estimate the worst-case scenario of radionuclide migration and then used a criticality code to calculate the effective neutron multiplication factor (i.e. reactivity). However, this manual approach may fail to select the most reactive scenario. Therefore, a new codebase has been developed by Jacobs for NWS in order to automate the safety assessment process, considering all scenarios and identifying trends in reactivity. The new codebase, GoldSim Monte Carlo Interfacing Tool (GMIT), comprises a set of Python modules and scripts which utilise parallel processing to allow the user to couple thousands of scenarios from a reactive transport model of a GDF with a choice of criticality code (MONK or MCNP). The tool is developed with user customisability in mind, and includes optimisation features to minimise space requirements of the GDF design while remaining safely below a prescribed reactivity threshold. This talk will discuss the main features of GMIT and will present some preliminary results that have been obtained through its use in support of the UK GDF criticality safety programme.

How to cite: Paxton, A., Wu, J., Applegate, D., Price, A., Hicks, T., and Eldridge, C.: Automated criticality calculations for radionuclide migration scenarios in the geological disposal of radioactive waste., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6380, https://doi.org/10.5194/egusphere-egu23-6380, 2023.

Existing literature suggests the importance of the thermo-osmosis (TO) for an accurate simulation of pore pressure evolution in heater tests for nuclear waste disposal in clay rock. However, there is limited consensus regarding the appropriate choice of parameters controlling TO and the extent of its physical impact. Uncertainty of parameters describing the host rock and their spatial variability further add to  both the complexity of this consideration. This study will use the ATLAS in-situ full-scale heating experiment from the HADES underground research laboratory in Mol, Belgium, to investigate the impact of TO on the thermal pressurisation in Boom Clay and its significance for the evaluation of barrier integrity.

The ATLAS experiment was simulated with an inelastic thermo-hydro-mechanical model implemented in OpenGeoSys. After comparison to published data, assisted-history-matching was performed to obtain a good representation of the in-situ measurements with and without taking into account TO. The comparison of both groups allows a clearer discussion of the influence of TO on temperature and pressure evolution in the studied system. The final step -- uncertainty quantification of the TO parameterisation -- puts the results in the context of the large parameter uncertainty documented in the literature. Subsequently, the impact of TO and said uncertainties on barrier integrity was estimated in terms of area and duration of potential integrity violation using statistical and geometrical methods.  

How to cite: Kiszkurno, F., Buchwald, J., Kolditz, O., and Nagel, T.: Numerical investigation on the impact of thermo-osmosis on fluid pressurisation and barrier integrity in Boom clay – a case study of the ATLAS in-situ full-scale heating experiment., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7016, https://doi.org/10.5194/egusphere-egu23-7016, 2023.

EGU23-7159 | ECS | Posters virtual | ERE3.3

Simulation of neptunium migration as a function of clay mineralogy and redox conditions  

Majedeh Sayahi, Theresa Hennig, Vinzenz Brendler, and Michael Kühn

Migration of neptunium, a minor component of high-level nuclear waste but with a long half-life (237Np: 2.14·106 years) and high radiotoxicity, is assessed for safety of potential nuclear waste disposal sites. Argillaceous rocks, like the Opalinus Clay (OPA), are preferred host rocks because of their low hydraulic conductivity and high sorption capacity. Numerical simulations are required to quantify radionuclide migration in the context of safety assessments.

One-dimensional diffusion simulations are conducted with PHREEQC to quantify the general neptunium migration processes. Sorption of Np(V) on the clay minerals is taken into account using surface complexation models. Carbonate minerals, mainly calcite, govern the pH, while the redox potential (pe) is controlled by pyrite. Therefore, both are considered in the mineral assemblage for atmospheric pCO2 conditions. Numerical simulations as a function of mineralogy and the associated changes in redox state and pore water composition are compared for two diffusion laboratory experiments conducted by Fröhlich et al. (2013) and Wu et al. (2009). Although both experiments were performed with the same setup, the determined transport parameters differ by one order of magnitude. Np(V) was applied via a synthetic pore water with pH 7.6 and pe 6 under atmospheric conditions, but to different OPA core samples. The Fröhlich experiment has already been modelled, and therefore this numerical setup is now applied to the Wu experiment to assess quantitatively whether the differences are due to variations in clay mineralogy or geochemistry.

Impact of clay mineralogy is quantified for maximum and minimum weight percentages of kaolinite and illite. Our results revealed that mineralogical variations only have a minor impact on the migration, and therefore cannot explain the difference between the two experiments. Np speciation is highly sensitive to pe and is partitioned between Np(IV) and Np(V). In the experiments, a pe of 6 is applied resulting in a redox disequilibrium within the sample compared to in-situ conditions with a pe of -3.8. Simulated migration is underestimated at high pe due to increasing sorption and overestimated at low pe, where Np(V) does not sorb. Results are consistent with the Fröhlich experiment when the pe is in an intermediate range between in-situ and experiment. Applying different redox conditions compared to Fröhlich, results also coincide with the Wu experiment. Therefore, variations in neptunium sorption are mainly attributed to different redox conditions.

We conclude that neptunium migration is governed less by clay mineralogy and more by redox. Therefore, redox conditions need to be accurately controlled in laboratory experiments as they determine neptunium speciation, and hence sorption. Distribution coefficients (Kd) can vary significantly, for instance, by one order of magnitude between two experiments with the same set up. This might hinder the applicability of experimentally determined Kd to assess neptunium migration for in-situ conditions.

 

References

Fröhlich, D. R., et al. (2013). Radiochimca Acta, 101(9), 553-560. DOI:10.1524/ract.2013.2059

Wu, T., et al. (2009). Environmental Science & Technology, 43(17), 6567-6571. DOI: 10.1021/es9008568

 

How to cite: Sayahi, M., Hennig, T., Brendler, V., and Kühn, M.: Simulation of neptunium migration as a function of clay mineralogy and redox conditions , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7159, https://doi.org/10.5194/egusphere-egu23-7159, 2023.

EGU23-7365 | Posters on site | ERE3.3 | Highlight

Consequences of Fault Reactivation on Subsurface Flow in Crystalline Rock 

Dominik Kern, Christian B. Silbermann, Fabien Magri, Rebekka Steffen, Holger Steffen, and Thomas Nagel

Important aspects for subsurface installations, such as Deep Geological Repositories (DGRs), in crystalline rock are the presence and evolution of fractures and faults, since they control the subsurface flow regime. According to climate extrapolation, it is expected that cold and warm period will alternate, accompanied by ice sheet progression and regression. The large moving mass of an ice sheet causes a dynamic response of the earth's crust, referred to as glacial isostatic adjustment (GIA) [1]. GIA changes the displacement and stress field not only under and near the ice sheet but also in its far-field. In view of the long-term assessments, we apply boundary conditions derived from an established GIA model [2] in order to analyze induced far-field stress and pore pressure changes and their impacts on existing faults in a hydromechanical simulation. As indicator for permeability changes we apply the Coulomb failure stress criteria. To quantify the consequences on the subsurface flow we run a component transport simulation before and another after the fault reactivation, revealing how the faults canalize the radionuclid propagation. For both kinds of simulations, hydromechanical and component transport, we apply Finite-Element methods (FEM) [3].
The INFRA project is funded by the DFG under grants NA1528/2-1 and MA4450/5-1.
 
[1] Holger Steffen, Patrick Wu. "Glacial isostatic adjustment in Fennoscandia - a review of data and modeling". Journal of geodynamics 52.3-4, p. 169-204, 2011. https://doi.org/10.1016/j.jog.2011.03.002
[2] Georg Kaufmann. "Program package ICEAGE". Manuscript, Institut für Geophysik der Universität Göttingen, vol. 40. p. 840, 2004.
[3] OpenGeoSys 6.4.3. Lars Bilke, Thomas Fischer, Dmitri Naumov, Christoph Lehmann, Wenqing Wang, Renchao Lu, Boyan Meng, Karsten Rink, Norbert Grunwald, Jörg Buchwald, Christian Silbermann, Robert Habel, Linda Günther, Mostafa Mollaali, Tobias Meisel, Jakob Randow, Sophia Einspänner, Haibing Shao, Kata Kurgyis, Olaf Kolditz, Jaime Garibay. 2022. https://doi.org/10.5281/zenodo.7092676

How to cite: Kern, D., Silbermann, C. B., Magri, F., Steffen, R., Steffen, H., and Nagel, T.: Consequences of Fault Reactivation on Subsurface Flow in Crystalline Rock, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7365, https://doi.org/10.5194/egusphere-egu23-7365, 2023.

EGU23-7559 | Orals | ERE3.3 | Highlight

Concept for Numerical THM Integrity Analysis of a Generic Repository in Clayey Rock in Germany 

Jobst Maßmann, Jan Thiedau, Maximilian Bittens, Vinay Kumar, and Tuong Vi Tran

Within the ANSICHT project, BGE Technology, BGR, and the Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) developed a safety assessment methodology for a high-level radioactive waste repository in clay formations based on German legal requirements. This included the quantification of integrity criteria and their exemplary numerical evaluation by THM-modeling. In the project's second phase, the modeling concept was extended by a detailed near-field model and initial attempts were made to quantify uncertainty. For the safety assessment of a repository system, detailed knowledge of the processes in the nearfield, the processes in the host rock, and the evolution of the whole system up to the surface is equally important. Concerning the prediction period of 1 million years and the complex coupled processes triggered by the construction and operation of an underground repository, the computational effort for numerical modeling is enormous. To cope with this effort, the proposed concept consists of models with different resolutions, dimensions, considered processes, and local coverages: a detailed 3D model of the near-field, a 2D and a 3D model of the whole domain, with the 2D model allowing a much higher resolution. The associated mathematical models are solved using OpenGeoSys 6, a finite-element-simulator allowing fully implicit process couplings. A statement about the integrity criteria and the general THM behavior is made integrally by all three models. Furthermore, a simplified 2D model is used to quantify the effect of variations in material parameters on the uncertainty of the results with manageable effort. Various geological setups have been used to investigate the influence of large inhomogeneities, such as sand lenses or layers in meter- to kilometer-scale, on the integrity of the host rock.

In this contribution, the updated modeling concept is presented and applied illustratively to a generic but typical geological situation in northern Germany.

 

How to cite: Maßmann, J., Thiedau, J., Bittens, M., Kumar, V., and Tran, T. V.: Concept for Numerical THM Integrity Analysis of a Generic Repository in Clayey Rock in Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7559, https://doi.org/10.5194/egusphere-egu23-7559, 2023.

Low-permeability granites are considered as host rocks for nuclear waste repositories. Understanding fluid flow and solute transport in granite fractures are essential in assessing the feasibility and safety of a nuclear waste repository. The internal variability of fractures, such as aperture distribution and asperities, dictates the hydrodynamics of reactive fluid, thus affecting the dispersion and retention of radionuclides. Numerical studies using 2-D models have focused on the heterogeneity of aperture distribution, but the effects of fracture asperities and additional surface features on the evolution of flow paths have not been systematically examined. In this study, the nonreactive solute transport behavior in a single fracture was numerically investigated considering the effects of fracture aperture and surface asperity by comparing 2.5-D and 3-D modeling results on a realistic fracture. The additional motivation here was to identify the limitations of model simplification. The 3-D fracture geometry was extracted from a micro-computed tomography of a natural fracture several centimeters long. Then, 2.5-D models were generated by mapping the aperture distribution of the 2-D fracture geometry on the x-y plane. Flow simulations were performed in both numerical models to detect the respective effects of fracture shape and surface asperities. For validation, we performed a sensitivity analysis by decreasing the 3-D fracture geometry mesh according to the quadric edge-collapse strategy, simulating the solute transport behavior under different fracture surface properties. The size variability of the isometric grid blocks ranges from 6.5 µm to 2.2 mm. Thus, we provide a function that can be used to quantitatively estimate the concentration error due to the simplification of the geometry mesh. The results show which fracture asperities and surface properties can significantly affect the solute transport behavior. Above a certain geometry complexity, the 3-D model results show less retention in the rather stagnant zones and thus better agreement with breakthrough curves (BTCs) of experiments compared to the 2.5-D model approaches. The results of the 3-D models also agree well with previous studies that less pronounced tailing is observed in the case of lower surface roughness. Simplifying the model geometry leads to more distorted results, with the 3-D model being more sensitive than the 2.5-D model. Moreover, based on a function summarized from the BTCs, the error in the simulated concentration due to mesh simplification can be estimated within a certain range that varies with the fracture geometry. The results presented show the capabilities and limitations of using 2.5D models in comparison with more elaborate 3-D models in predicting fluid dispersion in fractured crystalline rocks. Our study can serve as a guideline for the construction of fracture geometry and model design in future reactive transport modeling.  

How to cite: Zhou, W. and Fischer, C.: 3D modeling of solute transport through natural fractures with microrough walls in crystalline host rocks: The effects of asperities and surface characteristics on hydrodynamics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7753, https://doi.org/10.5194/egusphere-egu23-7753, 2023.

EGU23-8051 | ECS | Orals | ERE3.3

An interface constitutive model for fractured clayey formations in the context of nuclear waste disposal 

Adriana Quacquarelli and Frédéric Collin

In the context of nuclear energy production, the storage of radioactive waste deep underground in geological disposal facilities (GDF) is a promising solution to ensure the protection of people and the environment in the short and long term.

Due to the tunneling and storage operations, the thermodynamic equilibrium of the site is disturbed, triggering some damage and generating an interconnected fracture network around the gallery where the hydraulic conductivity can increase by several orders of magnitude [1] and facilitating the potential release and migration of radionuclides into the soil. However, once the gallery is closed and after the emplacement of waste, fractures can be sealed through resaturation by water coming from the claystone as a function of its self-sealing potential, i.e., the capacity of the rock to restore its hydraulic permeability leading to the hydraulic closure of the fracture [2]. During this self-sealing process, no structural changes are observed, meaning that this is a purely hydraulic process inducing any mechanical strengthening or bond at the interface. Due to their low permeability and their swelling capacity that favors the recovery of their hydraulic properties, clay materials prove to be eligible for nuclear waste storage. In France, Andra (Agence Nationale pour la gestion des Déchets Radioactifs) has selected the Callovo Oxfordian claystone (Cox), while the Boom Clay is studied as the host rock in the Belgian context and the Opalinus Clay in MontTerri in Switzerland. Over the last two decades, many experimental studies have been carried out to better understand the self-sealing process of such clay formations. In all cases, the final permeability is very close to the original one, which is not actually really achieved. Moreover, plastic clays such as the Boom Clay and the Cox show that the resaturation induces some secondary micro-cracks around the main fractures where the material can swell quickly favoring the sealing process.  

Based on these experimental observations, the objective of the following work is to describe the hydro-mechanical behavior of the fracture taking into account the self-sealing capacity through an appropriate constitutive equation that is implemented in a 2D finite element model. This model will then be validated through comparison with experimental results on Boom clay and Cox claystone samples tested in the laboratory and will allow further insight into the physical phenomena.

REFERENCES

[1]      G. Armand et al., “Geometry and properties of the excavation-induced fractures at the meuse/haute-marne URL drifts,” Rock Mech. Rock Eng., vol. 47, no. 1, pp. 21–41, Jan. 2014, doi: 10.1007/s00603-012-0339-6.

[2]      W. Bastiaens, F. Bernier, and X. L. Li, “SELFRAC: Experiments and conclusions on fracturing, self-healing and self-sealing processes in clays,” Phys. Chem. Earth, vol. 32, no. 8–14, pp. 600–615, 2007, doi: 10.1016/j.pce.2006.04.026.

How to cite: Quacquarelli, A. and Collin, F.: An interface constitutive model for fractured clayey formations in the context of nuclear waste disposal, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8051, https://doi.org/10.5194/egusphere-egu23-8051, 2023.

EGU23-8722 | Posters on site | ERE3.3

Experimental study on the creep behavior of buffer materials in the deposition hole of a repository 

Wei-Hsing Huang and Guo-Liang Ren

With the extra long term consideration for safety in a geological disposal repository, the creep behavior of the buffer material in a deposition hole can have an effect on the long-term stability of the engineered barrier. In this study, the hydro-mechanical properties and creep modeling parameters were determined experimentally on MX-80 bentonite. These include swelling pressure, water conductivity, and shear stress-strain behavior obtained from constant-stress direct shear test. The experimental works involved testing the bentonite in 3 different modes, namely, unsaturated, saturation under constant volume, and saturation after pre-swell. The pre-swelling process was designed to simulate an expansion of the buffer material due to mass losses of bentonite upon resaturation in a deposition hole.

          The experimental results show that in the constant volume mode and pre-swell mode, the swelling curve each has its own characteristics and, as the density of buffer decreases, the swelling pressure continues to decrease but in different trends. The shear strength obtained in the 3 modes is different while the values for the latter 2 modes are close. In the constant stress shear test, the higher the shear stress level, the faster the increase in shear strain rate. The shear strain rate is found to be higher in the pre-swell mode. Thus, for the long term safety of the deposition hole, the mass loss of buffer material should be limited to prevent degraded performance against creep deformation.

          Finally, numerical simulation was implemented to predict the creep deformation in a deposition hole for extended periods of time, in order to provide a reference for the design of the deposition hole and disposal tunnel. It is estimated that, at the junction of the buffer material and the backfill material, the vertical displacement increases continuously and reaches its maximum at 100,000 years.

How to cite: Huang, W.-H. and Ren, G.-L.: Experimental study on the creep behavior of buffer materials in the deposition hole of a repository, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8722, https://doi.org/10.5194/egusphere-egu23-8722, 2023.

EGU23-8787 | Orals | ERE3.3

Radioactive waste storage in salt structures under cyclic glacial loading 

Anton A. Popov, Tobias S. Baumann, Boris J.P. Kaus, Maximilian O. Kottwitz, and Janos L. Urai

Various salt structures, such as diapirs and salt walls, are currently considered as potential locations for the long-term storage of radioactive waste. Yet many scientific questions need to be addressed before safety and integrity of such repositories can be ensured. In particular, the effect of cyclic glacial loading on the long-term stability of a potential nuclear waste repository needs to be investigated.

In the first part of this study, we perform a series of simplified 2D thermo-hydro-mechanical model scenarios selected to cover the basic geometrical features of salt diapirs and walls. Our models include internal heterogeneities in the salt and faults in the salt and overburden. We consider various repository design schemes and investigate the effect of the radiogenic heat production on the deformation of the surrounding salt in a thermo-mechanically coupled manner. We explore the sensitivity of the results to variations in the physical rock properties and evaluate the potentially significant effect of the different dominant microphysical deformation mechanisms such as dislocation creep, dynamic recrystallization and pressure solution creep in salt.

The second part of this study focuses on the parameterization of the relevant salt rheology that controls the viscoelastic response of the salt structure. We quantify the rock salt rheology in a probabilistic sense by implementing a statistical creep model. Here, we incorporate a priori constraints and observations from the microstructure and determine representative creep law parameters and associated uncertainties.

Following this integrated approach, we aim to identify key model parameters and find characteristics of generic salt structures to assist the selection process of suitable salt structures.

How to cite: Popov, A. A., Baumann, T. S., Kaus, B. J. P., Kottwitz, M. O., and Urai, J. L.: Radioactive waste storage in salt structures under cyclic glacial loading, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8787, https://doi.org/10.5194/egusphere-egu23-8787, 2023.

EGU23-8791 | Orals | ERE3.3

Workflows for generation of high quality meshes for simulating THMC processes in porous and fractured media 

Kyle Mosley, Lee Hartley, Robert Turnbull, and Neal Josephson

Many nations are electing to deal with high-level radioactive waste by developing and licensing deep geological repositories (DGRs). A key objective of DGR safety cases is to demonstrate that the engineered and natural barrier systems will remain resilient and functional far into the future, ensuring that no harmful contaminant levels ever reach the biosphere. DGR safety cases are typically supported by numerical modelling of the repository system and its environment, simulating the thermal, hydraulic, mechanical and chemical (THMC) coupled processes that influence the barrier system evolution over such timescales.

Numerical modelling of DGRs often calls for representation of complex geologies and closure engineering with varying scales of structures and physical processes, requiring unstructured meshes to balance accuracy and efficiency. Crystalline host rocks present particular challenges because simulation of THMC processes often involves both 3D volumetric meshes to model porous media such as engineered barriers, and discrete fracture network (DFN) meshes to represent the fractured host rock. Furthermore, the required mesh type may differ depending on the physics to be simulated. For example, thermal and mechanical processes, which are primarily transmitted via the bulk rock mass, are best simulated on volumetric meshes. Modelling of hydraulic processes and their associated chemical interactions, by contrast, may be undertaken on either a DFN or volumetric mesh, depending on the medium and the level of geometric detail required.

Here, we present examples of near-field THMC simulations enabled by new meshing workflows in the FracMan® modelling software. The workflows facilitate creation of a flexible set of medium representations, including so-called ‘hybrid’ meshes consisting of both volumetric and DFN representations in different regions of a single model.

In the case studies, illustrative DGR components are meshed using a coupling to the LaGriT gridding library, which supports the creation of unstructured meshes with deformable tetrahedral elements that accurately capture curved and complex geometries. Fractured rock sections of the model are represented either by a DFN mesh of 2D triangular elements or by a volumetric mesh, depending on the physics. In both cases, targeted mesh refinement is applied to regions of greater geometric complexity and/or steep numerical gradients, facilitating simulation of variable-scale processes. Iterative smoothing algorithms are employed to create a high-quality Delaunay mesh, with quality metrics included to assess the likely performance in simulations. In the final step, the mesh is converted to its Voronoi dual; a discretisation that is optimal for finite volume simulators that employ a two-point flux approximation. It also provides a flexible mesh connectivity topology, which allows for high-fidelity representation of material property contrasts and heterogeneity.

The generated meshes are applied in example THMC simulations, undertaken in the subsurface flow simulator PFLOTRAN together with FracMan geomechanics codes. FracMan post-processing calculations are used to simulate particle flow paths, providing input to performance assessments. The results demonstrate how the developed workflows are an innovative combination of methods that provide accurate and efficient solutions to some specific challenges of DGR systems – namely, strong contrasts in the dimensions and properties of individual barrier system components.

How to cite: Mosley, K., Hartley, L., Turnbull, R., and Josephson, N.: Workflows for generation of high quality meshes for simulating THMC processes in porous and fractured media, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8791, https://doi.org/10.5194/egusphere-egu23-8791, 2023.

EGU23-8846 | Posters on site | ERE3.3

Preliminary design of the repository for high-level radioactive waste in Germany 

Dominik Gottron, Thomas Lohser, Niklas Bertrams, Dennis Gawletta, Frederik Fahrendorf, Stephen Klimke, Florian Schlüter, Michael Werres, and Wolfram Rühaak

The Federal Company for Radioactive Waste Disposal (BGE mbH) is responsible for the execution of the German site selection procedure for high-level radioactive waste. The aim is to identify a repository site that ensures the best possible safety for the disposal of high-level radioactive waste for at least one million years. Three potential host rocks are considered for disposal in Germany: rock salt, claystone and crystalline rock. The German site selection procedure consists of three consecutive phases with a continuously increasing level of detail. The first step of phase I served to determine sub-areas based on different geoscientific criteria. In this process 90 suitable areas were identified. The second step of phase I comprises representative preliminary safety assessments to further narrow down the sub-areas (see Figure 1).

Figure 1: German Site Selection Procedure

For these assessments, a preliminary concept and dimensioning of the deep geological repository is required, among other aspects. The primary input data for the preliminary design of the repository are the respective host rock properties, the inventory data of the high-level radioactive waste as well as a preliminary safety concept for the disposal system. Since there are only limited area-specific data available as no exploration is part of this early stage of the selection procedure, a two-stage method has been developed for the determination of the required area of the potential repository, consisting of a host rock specific and a site specific part. The objective of the first, host rock specific stage is to perform an analysis irrespective of the prevailing geological conditions at the considered locations. The aim is to obtain the areal extend of a potential repository as a function of the depth, the initial temperature in the host rock and mechanical properties of the host rock. Another important topic is the assessment of favorable depth ranges of the repository. Within the second stage, the function is used with available site-specific data to obtain the possible size of the repository at this specific site.

This contribution will provide an overview of the first stage within the aforementioned methodology for the development of the preliminary design of the repository as part of the representative preliminary safety assessments. 

How to cite: Gottron, D., Lohser, T., Bertrams, N., Gawletta, D., Fahrendorf, F., Klimke, S., Schlüter, F., Werres, M., and Rühaak, W.: Preliminary design of the repository for high-level radioactive waste in Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8846, https://doi.org/10.5194/egusphere-egu23-8846, 2023.

EGU23-9029 | ECS | Posters virtual | ERE3.3

Coupled THM modelling of the FE Experiment at Mt. Terri in Decovalex Task C 

Sonja Kaiser, Michael Pitz, Wenqing Wang, Jörg Buchwald, Aqeel Afzal Chaudhry, Olaf Kolditz, and Thomas Nagel

The theory of non-isothermal Richards flow with mechanics (TRM) assumes that the mobility of gases in unsaturated porous media is always large enough to allow sufficiently fast drainage so that the gas pressure does not increase significantly but remains constant. The benefit of an implementation using this simplified approach is a faster numerical model compared to an implementation using the more general theory of non-isothermal two-phase two-component flow with mechanics (TH2M), which represents the gas phase explicitly. The Full-scale Emplacement (FE) experiment conducted at the Mont Terri Underground Rock Laboratory was designed to simulate an emplacement tunnel for high-level radioactive waste at full scale using the reference repository design of the National Cooperative for the Disposal of Radioactive Waste (Nagra) of Switzerland. In this experiment, which is numerically studied in Task C of the Decovalex-2023 project, water vaporisation in the bentonite backfill near the heaters might potentially increase the gas pressure. Thus, justification for the applicability of Richards' assumption for this environment should be demonstrated before attempting to use a TRM process to model the coupled thermo-hydro-mechanical problem of this experiment. We demonstrate the applicability for the given conditions by comparing model results from OpenGeoSys (OGS-6) obtained by a TRM process with those obtained by a TH2M process implementation. The comparison of the TRM with the TH2M process provides the basis for subsequent extensive analyses using the TRM process of OGS-6 for modelling the FE experiment with large 3D meshes with more than one million degrees of freedom in parameter variation studies. This model has 75 parameters and many initial / boundary conditions, of which single ones or several at a time are varied. By comparing model results of these variations at 200 observation points with each other and to five years of hourly measurement data using statistical methods, sensitivities to single parameters are studied. But also relevant features not included in the current setup are revealed by using parameter settings that act as proxies for these anticipated missing features. These proxies give results that fit well to the observations but are without physical justification themselves. Due to the great possibilities for validation of existing coupled THM models arising thereof, this also leads to significant further development of model capabilities for the use in integrity evaluations of geotechnical and geological barriers.

How to cite: Kaiser, S., Pitz, M., Wang, W., Buchwald, J., Chaudhry, A. A., Kolditz, O., and Nagel, T.: Coupled THM modelling of the FE Experiment at Mt. Terri in Decovalex Task C, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9029, https://doi.org/10.5194/egusphere-egu23-9029, 2023.

EGU23-9478 | Orals | ERE3.3

Tomographic analysis of advective flow and diffusive flux toward improved migration predictability in host rocks for radioactive waste 

Cornelius Fischer, Johannes Kulenkampff, Maria Cardenas-Rivera, Wenyu Zhou, and Jann Schöngart

The predictive power of numerical approaches for the analysis of flow fields, e.g. for  radionuclide migration, depends on the quality of the underlying pore network geometry. Validation of the obtained simulation results can only be performed with a limited number of methods. Positron emission tomography (PET) is a suitable technique that has been established in geomaterial sciences in recent years. The use of suitable radiotracers allows the analysis of advective transport and diffusive flux in a variety of complex porous materials. In addition to the visualization of time-resolved transport patterns, the statistical analysis of transport controlling parameters is currently in the focus of investigations using PET techniques.

Using potential host rock types with low permeability for underground radioactive waste repositories as examples, we have analyzed the heterogeneity of the flow field at laboratory scale.1 Diagenetic and sedimentary components and their pore size distributions and pore network geometries are responsible for the flow field properties. The resulting generalized pore network geometries are used in digital rock models to calculate effective diffusivities, using a combined upscaling workflow for transport simulations from the nanometer to the micrometer scale.2 For advective transport in fractured crystalline rocks, PET provides evidence for the influence of fracture wall geometries over a wide range of the length scale. Surface building blocks from nm to mm size are responsible for the observed changes in breakthrough curve behavior. Finally, another hot topic is the testing of reactive PET tracers for materials analysis. In addition to the use of conservative tracers described above, reactive tracers provide insight into the density of reactive surface sites in complex porous materials.

1Bollermann, T.; Yuan, T.;  Kulenkampff, J.;  Stumpf, T.; Fischer, C., Pore network and solute flux pattern analysis towards improved predictability of diffusive transport in argillaceous host rocks. Chemical Geology 2022, 606, 120997.

2Yuan, T.; Fischer, C., The influence of sedimentary and diagenetic heterogeneity on the radionuclide diffusion in the sandy facies of the Opalinus Clay at the core scale. Applied Geochemistry 2022, 146, 105478.

How to cite: Fischer, C., Kulenkampff, J., Cardenas-Rivera, M., Zhou, W., and Schöngart, J.: Tomographic analysis of advective flow and diffusive flux toward improved migration predictability in host rocks for radioactive waste, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9478, https://doi.org/10.5194/egusphere-egu23-9478, 2023.

EGU23-9636 | Orals | ERE3.3

Uncertainty reduction by DoE-based history matching of the FE-experiment at Mt. Terri 

Jörg Buchwald, Sonja Kaiser, Wenqing Wang, Olaf Kolditz, and Thomas Nagel

For the evaluation of the performance of nuclear waste repositories, a detailed investigation of the sensitivity and uncertainty of the underlying processes is essential. The verification and validation of the numerical tools under realistic conditions using experimental data from underground research laboratories is all the more crucial because a comprehensive experimental analysis or investigation of the final repository site is impractical for a variety of reasons. In our contribution, we apply design-of-experiment-based history matching to reduce and examine parameter uncertainties with pressure and temperature data from the FE experiment. The FE experiment is a full-scale multiple heater test in the Opalinus clay at the URL site in Mount Terri in Switzerland. We use the open-source program OpenGeoSys for the deterministic thermo-hydro-mechanical modeling. An initial parameter screening to identify heavy hitters was conducted prior to proxy building using a Gaussian Proxy model. The proxy model is then used for experiment-matching, employing Monte-Carlo sampling over the entire remaining parameter space. The obtained parameter boundaries were applied to a global sensitivity analysis based on the proxy model to quantify uncertainty and show how parameter sensitivities affect results.

How to cite: Buchwald, J., Kaiser, S., Wang, W., Kolditz, O., and Nagel, T.: Uncertainty reduction by DoE-based history matching of the FE-experiment at Mt. Terri, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9636, https://doi.org/10.5194/egusphere-egu23-9636, 2023.

EGU23-10687 | ECS | Posters on site | ERE3.3

Evaluation of the density distribution in bentonite-sand buffer blocks manufactured by floating die press method 

Deuk-Hwan Lee, Seok Yoon, and Gi-Jun Lee

For the safe disposal of high-level radioactive waste, several performances of the compacted buffer block are required, such as low hydraulic conductivity, high thermal conductivity, adequate swelling pressure, and good mechanical properties. Furthermore, it is well recognized as the performance of these buffers is highly correlated with the density of buffer blocks. Therefore, it is an essential task to fabricate the compacted buffer block with a homogenous density distribution. In this study, the manufacturing characteristics of bentonite-sand buffer were evaluated to identify the required density relationship in accordance with the pressure of floating die press and the homogeneity of the dry density distribution in the buffer blocks.

How to cite: Lee, D.-H., Yoon, S., and Lee, G.-J.: Evaluation of the density distribution in bentonite-sand buffer blocks manufactured by floating die press method, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10687, https://doi.org/10.5194/egusphere-egu23-10687, 2023.

Among many parameters needed to characterize subsurface rock mass related to underground storage and disposal projects, an important one is the heat production rate of the bedrock itself.

The rock produces heat from the decay of radioactive isotopes consisting of minerals and its gamma-ray emissions, of which the magnitude is dominated by contents of major radioactive isotopes, e.g., uranium, thorium, and potassium. The heat production rate is generally calculated from the rock density and the radiogenic isotope contents, which can be measured from the spectrometry of drilled cores or rock fragments. However, such approaches are rarely available in deep boreholes because recovering rock samples from several hundred meters to a few kilometers is quite difficult.

A recent geophysical logging technique for deep boreholes is available where the uranium, thorium, and potassium contents are measured from the gamma-ray spectrum. However, this technique requires the density to be measured separately, and the measurement depth of the equipment is still limited. As an alternative method, a natural gamma-ray logging tool was adopted to estimate briefly the heat production from the total gamma activity, which is relatively easy to measure. This study introduces the development of the proposed method for evaluating the heat production of a granitic rock mass with domestic commercial borehole logging tools, as well as its application and verifications in deep boreholes.

How to cite: Kim, M., jo, Y., and Park, I. H.: Estimation of the radiogenic heat production rate of fractured granitic rock mass based on in-situ natural gamma logging, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10713, https://doi.org/10.5194/egusphere-egu23-10713, 2023.

EGU23-11317 | Orals | ERE3.3

Manufacturing of physical models by 3D-scanning and -printing for fracture flow tests 

Michael Kröhn and Klaus-Peter Kröhn

Visual observation of flow and transport processes in fractures requires transparent replicas. Quite easily realized are parallel plate models, which pose only a quite rough approximation, though, and require certain geometric conditions. A better representation can be gained by impressions from real fractures, either by forming the free space, a common technique but rather effortful, or by epoxi imprints of the fracture surfaces. Accurate surface measurements and determination of contact pressures indicate, though, that several imprints of the same locations may show significant differences.

A rather new class of transparent physical models has been made possible with the introduction of reasonably accurate 3D-printers in combination with transparent resins.  Hydraulic tests with principle models of single fractures as well as DFNs have been established quite early. Realistic single fracture replicas still pose a problem, though.

Three steps are required to produce a fracture replica by this method:
1. 3D-scanning of the fracture surfaces
2. Preparation of a printable digital model of the fracture
3. 3D-printing of the digital model

This procedure has a lot of appeal as repeated printing of the same physical fracture model allows for parallel as well as repeated destructive tests.  Additionally, it rather elegantly avoids the problem of air enclosure and bubble evolution between resin and fracture surface which is a common problem with resin imprints. Moreover, it is possible to add features to the digital model that facilitate hydraulic tests such as connectors to inflow and outflow tubes. Since it was intended to cover the whole production process of this method, a 3D-scanner as well as a 3D-printer have been acquired accordingly.

However, new challenges appear also at all three stages of production. One obvious point is the accuracy. The coordinates of a fracture surface can of course only be sampled at a limited number of scanning points. On the same scale, also the dimensional accuracy of the 3D-Printer is restricted. Less evident is the problem of alignment of the two fracture surfaces. Snapping points of opposing fracture surfaces at a distance of less than one millimetre have been found in printed replicas of 7 x 10 cm size, suggesting a potentially serious impact on the aperture distribution by misalignment. Another point concerns the general ability of plastics to take up water, which affects the resin material to a considerable extent in that weight and size change with time. Details and solutions to these problems are addressed.

In closing, the repeatability of an actual tracer test in a printed fracture replica is investigated. The experimental setup consists of an upper and a lower part. Transport of a colored solution in the fully water-filled replica has been observed with an industrial camera and repeated three times. By post-processing the probability of the presence of the tracer at each pixel was evaluated. The resulting video reveals a reasonable degree of repeatability.

How to cite: Kröhn, M. and Kröhn, K.-P.: Manufacturing of physical models by 3D-scanning and -printing for fracture flow tests, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11317, https://doi.org/10.5194/egusphere-egu23-11317, 2023.

EGU23-11582 | ECS | Orals | ERE3.3

Material research and multi-sensory monitoring for concrete sealing structures in rock salt underground repositories 

Vera Lay, Prathik Prabhakara, Frank Mielentz, Sergej Johann, Tobias Fritsch, Michael Stamm, Hans-Carsten Kühne, and Ernst Niederleithinger

Within the project SealWasteSafe, we advance construction materials and non-destructive monitoring concepts of sealing structures applied for underground disposal of nuclear waste. As these engineered barriers have high demands regarding structural integrity, an innovative alkali-activated material (AAM) that is highly suitable for the application in salt as a host rock is improved and tested on two laboratory scales. This AAM has a low heat evolution due to the reaction mechanism in comparison to common salt concretes based on Portland cement or magnesium oxychloride binders. Hence, crack formation due to thermally induced stress during the hardening process is reduced.

After successful laboratory tests with small specimens (height ~5 cm), comparably manufactured large cubic (edge length 70 cm) and cylindrical specimens (height 120 cm, diameter 40 cm) are equipped with sensing technologies to demonstrate the sensors´ technical capabilities.  A comprehensive multi-sensory monitoring scheme is developed and investigated to characterize and compare the different material behaviour during the setting and hardening process of two materials: (1) the newly developed AAM-based mortars with salt aggregate, and (2) a blended Portland cement-based salt concrete as reference. The analysed parameters include temperature and humidity of the material, acoustic emissions, and strain variations recorded by fiber optic cables. Passive sensor systems based on radiofrequency identification technology (RFID) embedded in the concrete provide an interface for the wireless readout of various sensors. In parallel to the embedded RFID sensors, conventional cabled systems to read out the temperature and humidity measurements are installed for comparison. Additionally, a detailed inspection of the two large cubic specimens after a monitoring period of more than six months has been undertaken. Active thermography and ultrasonic echo measurements are used to reveal potentially occurring inner cracks from the surface. To verify the non-invasive results, a core sample (diameter 2 cm) was extracted from each of the investigated cubic specimens and analysed in detail with X-ray computed tomography.

Furthermore, ultrasonic methods are used for quality assurance to detect obstacles, cracks, and delamination at in-situ scale sealing structures. Experimental layout and applied imaging techniques are optimised to enhance the image quality for measurements from the front side of the engineered barrier. To characterize the inside of the test sealing structure and to improve the detection of potentially existing cracks, an ultrasonic borehole probe using the phased array technique is developed. First analyses at a half-spherical specimen coincide with modelling results and prove the reliability of the directional response caused by the phased array technique of the newly constructed ultrasonic borehole probe. Overall, the project SealWasteSafe helps to characterize construction materials and improves multi-sensory monitoring concepts and ultrasonic equipment for the sake of quality assurance. Particularly for salt as a host rock, this will help to design safe sealing structures for nuclear waste disposal.

How to cite: Lay, V., Prabhakara, P., Mielentz, F., Johann, S., Fritsch, T., Stamm, M., Kühne, H.-C., and Niederleithinger, E.: Material research and multi-sensory monitoring for concrete sealing structures in rock salt underground repositories, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11582, https://doi.org/10.5194/egusphere-egu23-11582, 2023.

The characterization of pores in materials such as Opalinus clay is crucial for understanding the physical properties, including permeability and strength, which are important for the safe disposal of radioactive waste. Scanning electron microscopy (SEM) is a technique that allows high-resolution imaging of these pores at the nanoscale. However, the analysis of SEM images can be challenging due to the resolution limits of nanoscale pores and their manual segmentation. In the development of automatic segmentation methods, approaches of supervised or unsupervised machine learning (ML) and deep learning (DL) methods are increasingly applied. The main advantage of these methods is to achieve fast and more consistent results that do not rely on user input.

An essential component in DL is the so-called backbones, which can learn object features that are necessary for object recognition. In image processing, objects are recognized through groups of specific features that allow an unambiguous identification. Pre-trained backbones, which have been trained on large datasets such as ImageNet containing millions of everyday images, possess a wide range of features that are useful during image processing tasks. However, specialized applications, such as the automatic analysis of microscope images using DL may require features that differ from those of pre-trained backbones. The limited availability of SEM images makes it difficult to effectively train DL models, as these models typically require a large amount of data to learn new features. In these cases, ML methods may perform better due to their ability to use carefully selected, expert-defined features [Maitre et al., 2019].

In this study, the training behavior of eight different DL backbones was examined using a dataset of 2000 SEM images showing both the background and pores of an Opalinus clay sample. The backbones studied included VGG16, VGG19, ResNet50, Desenet, Xception, and Mobilenet. To train these models with the relatively small amount of training data available, a transfer learning technique was applied. We analyzed gradient-weighted class activation mappings (grad-CAM) [Selvaraju et al.,2019] during the learning process to obtain a general sense of the behavior of the different backbones. Through analysis of the model's adaptation efforts, the present study demonstrates which pre-trained backbones show good training behavior on SEM images and provides an estimation of the amount of data needed for effective training.

 

References

[Maitre et al., 2019] Maitre, J., Bouchard, K., and Bédard, L. P. (2019). Mineral grains recognition using computer vision and machine learning. Computers & Geosciences, 130:84–93.

[Selvaraju et al., 2019] Selvaraju, R. R., Cogswell, M., Das, A., Vedantam, R., Parikh, D., and Batra, D. (2019). Grad-cam: Visual explanations from deep networks via gradient-based localization.

How to cite: Brysch, M. and Sester, M.: Evaluating the Capabilities of Backbones for Scanning Electron Microscopy Images of Opalinus Clay, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11590, https://doi.org/10.5194/egusphere-egu23-11590, 2023.

EGU23-11604 | Orals | ERE3.3

Multi-disciplinary investigation of water content and displacement evolution around the Mont Terri twin niches in Opalinus Clay 

Gesa Ziefle, Tuanny Cajuhi, Stephan Costabel, Markus Furche, Herbert Kunz, and Jobst Maßmann

Coupled hydro-mechanical effects in Opalinus Clay (OPA) are of significant interest regarding the  stability and integrity of a potential storage facility for high-level radioactive waste (HLW). In the Mont Terri Rock Laboratory, the CD-A twin niches differ only in their ventilation and enable the investigation of near field effects like desaturation and development of the excavation disturbed zone (EDZ). Amongst others, the evolution of water content and deformation are observed and provide a comprehensive data set as basis for a pragmatic approach to capture effects in the EDZ in safety assessment. The measuring campaign includes electric resistivity tomography (ERT), providing daily measurements of the electric resistivity distribution up to a few meters into the rock formation, as well as the nuclear magnetic resonance method (NMR) aiming on the evolution of water content near the surface of the niches. Due to the corresponding effort in handling the relatively new single-sided application, the NMR measurements are only conducted once per season. Nevertheless, the combined interpretation of NMR and ERT provides valuable data of water content and hydraulic conductivity evolution enabling a meaningful optimization of numerical modelling approaches. 
The interpretation of the water content evolution in combination with the geologic characterization demonstrates the high heterogeneity of the sandy facies of OPA, a significant impact of the ventilation, and a correlation of high resistivity regions with open fractures, indicating potential preferential flow paths that are relevant for transport processes. As a matter of fact, the results illustrate a need to discuss the set-up of numerical modelling, especially concerning the boundary conditions, the heterogeneities, and the parametrization and set-up of the EDZ. Further measuring focus on the displacements around the niches. While laser scans represent the convergence behavior near the surface, extensometers generate information about the displacements a few meters around the twin niches. Summarizing these data, the convergence behavior near the surface as well as a few meters around the twin niches depends significantly on the ventilation of the niches, indicating seasonal effects and differences in the long-term convergence behavior. Future work aims on an increased system understanding considering long-term effects due to climatic conditions, geotechnical boundary conditions, heterogeneities amongst others and their realistic representation in safety assessment.

How to cite: Ziefle, G., Cajuhi, T., Costabel, S., Furche, M., Kunz, H., and Maßmann, J.: Multi-disciplinary investigation of water content and displacement evolution around the Mont Terri twin niches in Opalinus Clay, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11604, https://doi.org/10.5194/egusphere-egu23-11604, 2023.

EGU23-12223 | Posters on site | ERE3.3

Development of Experimental System to Measure Waster Suction of Compacted Bentonites beyond 100 °C 

Seok Yoon, Gi-Jun Lee, and Deuk-Hwan Lee

The compacted bentonite buffer is one of the most important components in an engineered barrier system(EBS) to dispose of high-level radioactive waste (HLW) produced by nuclear power generation. The design temperature of the bentonite buffer is below 100 °C. However, if the design temperature can be increased above 100 °C, the disposal area can be reduced. For this reason, it is necessary to investigate its properties at 
temperatures above 100 °C to increase the target temperature of the buffer. Although some studies have investigated the thermal-hydraulic properties above 100 °C, few have evaluated the water suction of compacted bentonite. Therefore, this study developed experimental system to measure water suction above 100 °C, and measured relative humidity for compacted Korean bentonite between 25 and 150 °C with initial saturations of 0, 0.22, and 0.47 under constant saturation conditions. Water suction decreased as the temperature increased. In particular, there was an approximately 5–20% decrease in the water suction between 100 and 150 °C.

How to cite: Yoon, S., Lee, G.-J., and Lee, D.-H.: Development of Experimental System to Measure Waster Suction of Compacted Bentonites beyond 100 °C, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12223, https://doi.org/10.5194/egusphere-egu23-12223, 2023.

In deep underground storage facilities, coupled thermo-hydro-mechanical models are used to simulate the changes in temperature, pore pressure, and stress surrounding canisters containing high-level radioactive waste. Their numerical modeling is often computationally highly demanding, especially if an investigation is conducted that requires many model evaluations, like a sensitivity analysis or a parameter identification. In these analyses, the thermally driven pore pressure evolution and the subsequently altered flow processes are usually the primary targets of interest. 
In our contribution, we show the derivation of a hydro-thermal (HT) model with consistent incorporation of thermo-mechanical effects, allowing it to profit from its computational efficiency while maintaining most of its accuracy. We show its applicability to a 3D model of the FE experiment, a full-scale multiple heater experiment at the URL site in Mt. Terri.

How to cite: Buchwald, J., Kaiser, S., Wang, W., Kolditz, O., and Nagel, T.: Improved predictions of thermal fluid pressurization in hydro-thermal models based on consistent incorporation of thermo-mechanical effects - Application study of the FE-Experiment at Mt. Terri, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12486, https://doi.org/10.5194/egusphere-egu23-12486, 2023.

EGU23-13593 | Orals | ERE3.3

Automatized large-scale 3D THM simulations capturing glacial cycle effects on German nuclear waste repositories in clay rock 

Christian Silbermann, Florian Zill, Tobias Meisel, Friederike Tiedtke, Dominik Kern, Anton Carl, Andreas Jockel, Thomas Nagel, Olaf Kolditz, Heinz Konietzky, and René Kahnt

To properly assess the present and future conditions of potential nuclear waste repository sites, understanding their evolution in the past is mandatory. Here, glaciation cycles strongly affect the long-term thermo-hydro-mechanical (THM) evolution of the geosystem.
The AREHS project studies the effects of time-dependent boundary conditions on the evolution of large-scale hydrogeological systems. The focus is on numerical long-term modeling taking into account THM couplings. On the basis of generic geological models for different host rock formations, complex 3D THM simulations are performed. The long-term evolution during glacial cycles is simulated using the open-source multi-field finite element code OpenGeoSys, as well as multiple pre- and postprocessing tools integrated into an automatized workflow. This workflow facilitates testing/benchmarking and improves reproducibility as well as overall software quality in a sense of modularization. The impact of the glacial THM loading and atmospheric temperature evolution is taken into account using appropriate time-dependent THM boundary conditions. The simulation results are analyzed with respect to potential safety-critical parameters, such as maximum temperature, hydraulic pressure, subsidence, equivalent effective stress and strain. Some general conclusions will be drawn for the host rock clay in Germany.

Funding:

This research is funded by the Federal Office for the Safety of Nuclear Waste Management under Grant No. 4719F10402 (AREHS project).

How to cite: Silbermann, C., Zill, F., Meisel, T., Tiedtke, F., Kern, D., Carl, A., Jockel, A., Nagel, T., Kolditz, O., Konietzky, H., and Kahnt, R.: Automatized large-scale 3D THM simulations capturing glacial cycle effects on German nuclear waste repositories in clay rock, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13593, https://doi.org/10.5194/egusphere-egu23-13593, 2023.

EGU23-14400 | ECS | Posters on site | ERE3.3

Risk-based Assessment of Salt Domes as Disposal Sites for Nuclear Waste: Uncertainty of Groundwater Age in the Salt Dome Problem 

Jonas Suilmann, Andrea Perin, Matteo Broggi, Thomas Graf, and John W. Molson

Long-term safety has to be assured for the disposal of high-level nuclear waste to prevent contamination of the biosphere. A numerical framework for the probabilistic assessment of hazardous events regarding nuclear waste disposal in salt domes is developed here. The goal is to numerically simulate transport times and mass fluxes of radionuclides into the biosphere, and to couple this with a probabilistic framework for reliability assessment. This model can deal with uncertainties such as the impact of external events (major climate changes, human activities, earthquakes) on subsurface structure, material properties and boundary conditions. To quantify the impact of external events, a numerical model of the far field of a salt dome disposal site is generated. It includes the simulation of density-driven (thermohaline) flow, heat transport, transport of dissolved salt and a radionuclide in discretely-fractured porous media using the FE-code HEATFLOW-SMOKER Version V3/TC2.

As a first step in quantifying the effects of uncertain parameters in the context of nuclear waste disposal in salt domes, the salt dome problem (HYDROCOIN level 1 case 5) is further investigated in terms of groundwater age. Groundwater age is one of the exclusion criteria in the site selection process for nuclear waste deposits and therefore of great importance. Groundwater age is here calculated as a transport problem using steady-state flow velocities. This problem is density-driven due to transport of salt into the model domain and the steady-state solution is highly dependent on dispersion.  A sensitivity analysis is carried out to quantify the effect of uncertain dispersion on flow and salt distribution and resulting groundwater age. Preliminary simulation results demonstrate that both salt distribution and groundwater age in steady-state are significantly affected by longitudinal and transversal dispersivity. Resulting flow velocities are higher with increased dispersion and therefore lead to a decreased maximum groundwater age in the model domain.

How to cite: Suilmann, J., Perin, A., Broggi, M., Graf, T., and Molson, J. W.: Risk-based Assessment of Salt Domes as Disposal Sites for Nuclear Waste: Uncertainty of Groundwater Age in the Salt Dome Problem, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14400, https://doi.org/10.5194/egusphere-egu23-14400, 2023.

EGU23-14788 | Orals | ERE3.3

The potential for colloidal silica grout in multi-barrier systems for geological disposal 

Rebecca Lunn, Arianna Pagano, and Grainne El Mountassir

Over the past decades, researchers and industry have developed multi-barrier approaches to the sealing of deposition holes, tunnels, shafts and boreholes. Research has comprehensively described the hydromechanical behaviour of typical barrier materials, such as cement and compacted bentonite over a wide range of hydromechanical conditions. Where challenges remain for post-closure sealing is in controlling the hydromechanical behaviour at interfaces between materials within the repository. These interfaces include between the host rock and the barrier materials, as well as at the interfaces with materials required for safe construction and operation, such as shotcrete and steel.

 

This study explores the potential for colloidal silica grout as a secondary grouting material for repair of degraded cementitious construction materials and wasteforms and for sealing the interfaces between barriers materials and the host rock. Colloidal silica is an aqueous suspension of silica (SiO2) nanoparticles, with average particle size <100 nm.  The creation of siloxane bonds (Si – O – Si), typically triggered by the addition of an electrolyte accelerator, leads to the formation of a solid-like network of silica nanoparticles in the form of a hydrogel. Previous work at Strathclyde on colloidal silica gel has proved its potential to form low-permeability hydraulic barriers against fluid migration, and to inhibit the diffusion of radionuclides through the gel, making it a promising material for use in retrieval operations.

 

Here we present research to determine the potential for colloidal silica to be used in a range of geological disposal applications. We show that due to its excellent penetrability and controllable gel time, colloidal silica has the potential for repairing fine-aperture cracks within the cementitious materials, at the cement/steel interface, or at the interface between barrier materials and the host rock. We inject colloidal silica injected into fractured cement cores (0.2 and 0.5 mm fracture aperture) and expose them to varying pressure and temperature conditions. Fracture permeability upon water injection is assessed pre- and post-treatment. We find that permeability values after treatment are reduced by three orders of magnitude, thus confirming the potential of colloidal silica for repairing fine-aperture cracks. Further, our experiments show that mechanical strength of the cement is recovered, suggesting that additional C-S-H is produced during grouting. We then discuss the wider potential for colloidal silica as part of a multi-barrier approach to long-term sealing of geological disposal facilities.

How to cite: Lunn, R., Pagano, A., and El Mountassir, G.: The potential for colloidal silica grout in multi-barrier systems for geological disposal, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14788, https://doi.org/10.5194/egusphere-egu23-14788, 2023.

Clay minerals play an important role as barrier in radioactive waste storage. In addition to their function as hydraulic barrier, clay minerals can also immobilize radionuclides by adsorption and redox reactions with radionuclides. Reduction of redox-active radionuclides such as  technetium and selenium by smectites has already been shown. Many clay minerals contain iron (Fe) in their structure, however, not all of this structural Fe is accessible for redox reactions. This can depend on multiple factors such as the quantity and coordination of Fe in the clay mineral structure. While the redox-activity of Fe in smectites has received quite some attention, other common types of clay minerals present in clay host rocks have received less attention. In this study we investigated redox capacities of a variety of common clay minerals using mediated electrochemistry. Results show that most clay minerals have electrochemically‑active Fe to some extent, but there is a large variation in the fractions of electrochemically-active Fe between the different clay minerals. Smectites had the highest redox-active Fe fraction (~100%), followed by mixed illite-smectite (~40%), glauconite (~15%), illite (~10%) and chlorite (~1%). Within the same clay mineral type there was also variation in the redox-active fraction. Batch experiments showed that even for clay minerals in which only a small fraction of Fe was redox-active, reduction of selenite to elemental selenium took place.

How to cite: Hoving, A. and Griffioen, J.: Redox capacities of different types of clay minerals and their potential to immobilize redox-active radionuclides, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14909, https://doi.org/10.5194/egusphere-egu23-14909, 2023.

Crystalline rock is one of the potential rocks under consideration in Germany for hosting a heat-generating nuclear waste repository. The focus of this contribution is a repository system, which relies on the Containment Providing Rock Zone (CRZ) in a crystalline rock as the principal containment barrier. In compliance with the German safety requirements, the integrity of the CRZ is required, i.e. to keep its containment capabilities for a period of 1 million years. This implies that the formation of new pathways must be excluded, temperature development must not significantly impair the barrier effect and anticipated stresses and fluid pressures should not exceed the dilatancy strength and the fluid pressure capacity, respectively. To meet this requirement a safety-oriented assessment of mechanical, hydraulic, thermal and chemical processes, as well as their couplings, occurring in the host rock due to the storage of heat-generating nuclear waste, excavation and/or gas production among others, is needed and numerical modelling is an essential and powerful tool for it.

Fractures and other types of discontinuities, which usually characterize crystalline rock, are expected to influence the hydraulic behavior of the system. Thus, an adequate representation of the fracture network is required in order to capture its relevant properties, which will ultimately define the hydraulic boundary conditions surrounding the CRZs. Typically it is only possible to characterize fracture networks statistically. This requires a systematic investigation to quantify the influence of multiple realizations on the repository system.

The decay-heat produced by the heat-generating nuclear waste leads to an increase of the local temperature through which the host rock as well as the fluid will expand. Consequently, a change in the effective stresses is also expected. With the aim of obtaining a better representation of the temperature-induced fluid pressure increase a bi-directional coupling of the hydraulic-mechanical (HM) processes is being tested.

Previous work done by [1] based on a one-directional coupling between the HM processes for the estimation of the fluid pressure and one realization of a statistically generated generic geological model. This contribution aims to further develop the work from [1] by using a bi-directional coupling between the HM processes, implemented in the open-source finite element code OpenGeoSys version 6, to calculate the thermal induced fluid pressure increase and quantify the impact on the integrity criteria. Moreover, preliminary results for an approach used to evaluate the influence of multiple statistically equivalent fracture networks on the repository will be presented.

References

[1] Thiedau, J., et al.: CHRISTA-II - Analysen zur Integrität von geologischen Barrieren von Endlagersystemen im Kristallin. Ergebnisbericht, Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover, 2021

How to cite: Guevara Morel, C., Maßmann, J., and Thiedau, J.: Further development of a numerical modeling concept of the coupled THM behavior within a generic nuclear waste repository in crystalline rock, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15492, https://doi.org/10.5194/egusphere-egu23-15492, 2023.

EGU23-16189 | Orals | ERE3.3

Colloidal properties of clays related to the erosion and sedimentation behaviour of bentonite in fractures 

Ursula Alonso, Tiziana Missana, Miguel Garcia-Gutierrez, and Patrik Sellin

Smectites are selected as barriers in deep geological repositories for high-level radioactive waste repository due to their high swelling capacity and contaminant retention ability. Erosion of the clay barrier can affect repository safety and eroded particles may facilitate radionuclide migration within the host rock fractures. These processes depend on the physicochemical characteristics of the clay, on its structural properties and are affected by the chemical equilibrium established with the groundwater from the geological formation.

In order to assess the relationship between clay colloidal properties and the erosion and sedimentation behaviour in fractures, this study correlates the erosion behaviour of a compacted bentonite barrier, under repository conditions, simulating expansion and sedimentation in artificial fractures with physicochemical macroscopic properties (viscosity, turbidity,...) of different smectite suspensions. Studies are carried out under different geochemical conditions.

Results showed that sodium smectites had the highest viscosities, all showing similar behaviour: at low ionic strengths the viscosity remained constant and around 10 mM increased significantly. In spite of forming smaller particles, their expansion and sedimentation is hindered by their high viscosity. In contrast, clays with dominant bi-trivalent cations in their structure, has lower viscosity values, independent on the water ionic strength. Due to their higher particle size and lower viscosity, higher sedimentation in rock fractures is expected.

Turbidity measurements over time were done to assess sedimentation behaviour. It was observed that sodium smectites remained stable over time, even at high ionic strengths, as observed in viscosity studies. With calcium clays, turbidity decreased rapidly, indicating fast sedimentation occurred.

The study contributes to predict the erosion behaviour of the clay barrier in the fractures of the geological formation of a deep geological repository, starting from the colloidal properties of each clay.

This work was partially supported by the Swedish Nuclear Fuel and Waste Management Co, SKB (Sweden) and by the Spanish Ministry of Innovation and Science (PID2019-106398GB-I00, ARNO Project).

How to cite: Alonso, U., Missana, T., Garcia-Gutierrez, M., and Sellin, P.: Colloidal properties of clays related to the erosion and sedimentation behaviour of bentonite in fractures, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16189, https://doi.org/10.5194/egusphere-egu23-16189, 2023.

EGU23-16333 | Orals | ERE3.3 | Highlight

Profiles of δ18O and δ2H in porewater of a Mesozoic rock sequence: Regional variability and relation to large-scale transport regimes 

Thomas Gimmi, Lukas Aschwanden, H. Niklaus Waber, Eric C. Gaucher, Jin Ma, and Daniel Traber

Clay-rich rocks have very low hydraulic permeability and they also have good chemical retention properties for cationic contaminants. This makes them ideal as host rocks for the underground disposal of radioactive waste. In Switzerland, the Opalinus Clay Formation, Jurassic sediments deposited ~174 Ma ago, is envisaged as potential host rock. A large drilling campaign has recently been run in three potential siting regions in northern Switzerland. Drill core samples from a ~400 m thick Mesozoic low permeability zone were obtained at high spatial resolution in one slanted and eight vertical boreholes. Data including various natural tracers were obtained from these core samples. Here we report on the profiles of the stable isotopes δ18O and δ2H in porewater and groundwater in the eight vertical boreholes. The distribution of the tracers results from hydrogeological and transport processes acting in the past, and the profiles can be interpreted as results of ‘experiments performed by nature’. Hydrogeochemical investigations of groundwater and veins mineralisations help to constrain the temporal evolution of the system and to assess the system’s large-scale transport properties. The comparably large number of boreholes allows us comparing the observed depth distributions of the two tracers not only vertically, but also laterally in the three regions (~15-20 kilometers apart), and in the 2 to 4 boreholes in each region (a few kilometers apart). The isotope profiles from the different boreholes show many similarities, but also distinct features that are mainly related to the lateral variation in aquifer properties. The regional aquifers in the Malm (one locality Hauptrogenstein) and Muschelkalk typically build the upper and lower boundary, respectively, of the δ18O and δ2H profiles. In some, but not in all tracer profiles, there are indications of a local Keuper aquifer in the lower part. The variability reflects the lithological heterogeneity of this rock unit in the lateral dimension. The maximum isotope values plot to the right of the GMWL, are often similar and are found in the central part of the profiles in the Opalinus Clay Formation. Towards the Keuper aquifer (if present), the values decrease and approach the GMWL, and often some gentle decrease is also observed towards the upper aquifer, without reaching the GMWL. Towards the Muschelkalk aquifer, the values decrease sharply and reach the GMWL. The shapes of the profiles hint to the importance of diffusive transport processes over large spatial and geologic time scales. With transport simulations, we try to narrow down the timing of any changes in the aquifer signatures in the more recent past (10 ka to few Ma ago), as well as to assess the importance of various transport mechanisms in the development of the profiles. The interpretation of such tracer profiles is a key element with respect to the assessment of the large-scale transport properties of a host rock.

How to cite: Gimmi, T., Aschwanden, L., Waber, H. N., Gaucher, E. C., Ma, J., and Traber, D.: Profiles of δ18O and δ2H in porewater of a Mesozoic rock sequence: Regional variability and relation to large-scale transport regimes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16333, https://doi.org/10.5194/egusphere-egu23-16333, 2023.

EGU23-16485 | ECS | Posters on site | ERE3.3

Automatized large-scale 3D THM simulations capturing glacial cycle effects on German nuclear waste repositories in salt rock 

Florian Zill, Christian Silbermann, Tobias Meisel, Friederike Tiedtke, Dominik Kern, Anton Carl, Andreas Jockel, Thomas Nagel, Olaf Kolditz, Heinz Konietzky, and René Kahnt

To properly assess the present and future conditions of potential nuclear waste repository sites, understanding their evolution in the past is mandatory. Here, glaciation cycles strongly affect the long-term thermo-hydro-mechanical (THM) evolution of the geosystem.

The AREHS project studies the effects of time-dependent boundary conditions on the evolution of large-scale hydrogeological systems. The focus is on numerical long-term modeling taking into account thermal-hydraulic-mechanical couplings. On the basis of generic geological models for different host rock formations, complex 3D-THM-simulations are performed. The long-term evolution during glacial cycles is simulated using the open-source multi-field finite element code OpenGeoSys, as well as multiple pre-and postprocessing tools integrated into an automatized workflow. This workflow facilitates testing/benchmarking and improves reproducibility as well as overall software quality in a sense of modularization. The impact of the glacial THM loading and atmospheric temperature evolution is taken into account using appropriate time-dependent THM boundary conditions. The simulation results are analyzed with respect to potential safety-critical parameters, such as maximum temperature, hydraulic pressure, subsidence, equivalent effective stress and strain. Some general conclusions will be drawn for the host rock salt in Germany.

How to cite: Zill, F., Silbermann, C., Meisel, T., Tiedtke, F., Kern, D., Carl, A., Jockel, A., Nagel, T., Kolditz, O., Konietzky, H., and Kahnt, R.: Automatized large-scale 3D THM simulations capturing glacial cycle effects on German nuclear waste repositories in salt rock, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16485, https://doi.org/10.5194/egusphere-egu23-16485, 2023.

In January 2022, the Swedish government approved the development of a final repository for spent nuclear fuel at the Forsmark site. Leading up to this decision, and after completion of the main review phase in 2018, the Swedish Radiation Safety Authority (SSM) was asked by the Government to comment on new reported experiments related to degradation mechanisms for both the canister’s copper shell and cast iron insert. In particular, decision makers were concerned to ensure that such studies did not raise new questions regarding the suitability of the canister design.

In this paper, we provide an overview and assessment of the relevant degradation mechanisms:

  • Localised sulphide corrosion of copper: Although previously ruled out based on the condition that available sulphide would be consumed by general corrosion, for high sulphide loads passive films may form. Localised corrosion could then be induced by tensile stresses (SCC) or other factors (pitting corrosion).
  • Anoxic corrosion of copper: Although contradictory to conventional thermodynamic understanding, the detection of hydrogen evolution in certain laboratory experiments and an alleged higher than expected corrosion during a 20 year field experiment (LOT) have been proposed as evidence for this process.
  • Radiation induced effects: The initial radiation field is expected to have a limited effect on rates of corrosion and to some extent affect the properties of canister materials.
  • Strain hardening of cast iron: The implications for the canister’s mechanical integrity of deformation events that do not directly lead to canister failure (e.g. large earthquakes) have been proposed as being important in safety assessment.

It has been postulated that these processes represent a significant detriment for canisters, with suggestions that containment lifetimes could be reduced by orders of magnitude. Such claims have, however, typically been made in the absence of relevant data relating to repository conditions, and it has thus not been straightforward for decision makers to assess their accuracy.

SSM´s reviews generally found the first item to be most significant since experiments indeed reveal that passivating films could form under certain conditions. Even so, differences in overall repository performance were assessed to be limited, primarily because any appreciable effect would be restricted to a small number of deposition holes in which it was theoretically possible to sustain combined relatively large mass-transfer rates and high sulphide concentrations. The second item was judged to be of negligible significance, with no plausible connection to the LOT experiments, where detected corrosion is considered to be associated with oxidising conditions. For the third and fourth items, limited effects on canister integrity analysis can be expected and SSM looks for work to be conducted to ensure safety margins are maintained with respect to mechanical performance of canisters.

Although the fruitful Swedish canister debate did not result in a need to modify regulatory conclusions regarding compliance with regulatory criteria, experiences show that new scientific information can always emerge which must be considered in a site specific context regarding e.g. detailed canister design and production as well as safety assessment.

How to cite: Strömberg, B., Calota, E., Egan, M., and Liu, J.: Assessment of canister degradation for the encapsulation of spent nuclear fuel: Key research issues encountered in recent regulatory reviews and government decision making in Sweden, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16679, https://doi.org/10.5194/egusphere-egu23-16679, 2023.

EGU23-16757 * | Orals | ERE3.3 | Highlight

Potentials and challenges of applying artificial intelligence (AI) in geosciences for the search of a repository of high-level waste in Germany 

Florian Krob, Judith Krohn, Veronika Ustohalova, Stefan Wittek, and Dimitri Bratzel

In a science-based site selection process (StandAV), the Federal Republic of Germany searches for the site with the best possible safety for a repository of high-level waste (HLW) over a period of one million years. For this purpose, the geological subsurface of the German federal territory must be investigated and evaluated.

Challenges include the large area under investigation, that encompasses the entire federal territory of Germany with its large variability in geology, as well as the verification period which must be met to ensure the best possible long-term safety. Furthermore, an enormous amount of heterogenous geodata will have to be processed.

The application of AI-based methods in geosciences promises high potentials when dealing with large heterogenous data sets and cost- and time-consuming model calculations of complex and coupled processes. Accordingly, research on the application of AI has increased significantly in the geosciences over the last few years.

In our recent study “The use of artificial intelligence (AI) in the site selection process for a deep geological repository”, we succeeded developing an interdisciplinary assessment tool to evaluate the applicability of AI methods in geosciences in general and especially regarding their use for geoscientific issues in the StandAV. Here, we focus on potentials and challenges of applying AI in geosciences with respect to geological key activities in the StandAV. Thus, we emphasize on limitations that may arise from the use of AI regarding key activities in StandAV and propose necessary conditions for its applicability in the future.

Our results show that AI methods are superior to conventional methods, especially when it comes to data management and dealing with large geological data sets and model calculations of complex long-term and coupled geological processes. However, AI methods are generally only transferable to the geoscientific issues in the StandAV with methodological and subject-specific adaptations. Nevertheless, sufficient data, both in quality and quantity, is a prerequisite for the use of AI. Our study also shows that AI should only be used in a supportive way to tackle geological issues in the key activities and must not have any decision-making power when used in the StandAV.

High demands must be placed on the traceability of the applied AI methods. AI methods that do not meet the transparency requirements of the StandAV bear considerable risks of jeopardizing the trust of the population in the participation process. This could increase the general suspicion and scepticism towards AI in the public perception. Therefore, we strongly recommend to always evaluate and validate iteratively all methods and providing results to the public when applied to the key activities of the StandAV.

Title of study: “The use of artificial intelligence (AI) in the site selection process for a deep geological repository”,
a project on behalf of the Federal Office for the Safety of Nuclear Waste Management (BASE-FKZ 4721E03210)

How to cite: Krob, F., Krohn, J., Ustohalova, V., Wittek, S., and Bratzel, D.: Potentials and challenges of applying artificial intelligence (AI) in geosciences for the search of a repository of high-level waste in Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16757, https://doi.org/10.5194/egusphere-egu23-16757, 2023.

EGU23-16935 | Orals | ERE3.3 | Highlight

Joint geophysical and numerical insights of the coupled thermal-hydro-mechanical processes during heating in salt 

Yuxin Wu, Jiannan Wang, Sebastian Uhlemann, Shawn Otto, Brian Dozier, and Kristopher Kuhlman

Salt is an ideal medium for permanent isolation of heat-generating radioactive waste due to its tightness regarding fluid flow, high thermal conductivity, and ability to creep close fractures. Understanding the thermal-hydrological-mechanical (THM) processes, including the resulting brine migration, is a key part of the scientific basis for safe radioactive waste disposal in salt formations. Underground at the Waste Isolation Pilot Plant (WIPP), to study brine migration near an excavation during active heating, we conducted joint in-situ geophysical monitoring experiments using electrical resistivity tomography (ERT) and high-resolution fiber optic-based distributed temperature sensing (DTS), during a controlled heating experiment. ERT electrode arrays and fiber optic sensors were cemented into parallel horizontal boreholes. In addition, DEM (Discrete Element Model) based numerical simulations were conducted to simulate the THM processes during heating to understand better the mechanisms that led to changes in these geophysical measurements. During heating, resistivity changes near the heater can be explained well with a simple temperature effect. Yet, at more distant regions that were cooler, the resistivity decreased much more than is predicted from temperature effects alone. DEM simulations indicate that brine migration, driven by a pore pressure gradient, is likely the primary reason for the significant resistivity decrease beyond temperature effects. Comparison between the predicted ERT responses and observations is much improved when considering the DEM simulated brine migration effects. In support of our understanding of salt for radioactive waste disposal, this geophysical and simulation evidence provided mechanistic insights into field-relevant THM processes. 

How to cite: Wu, Y., Wang, J., Uhlemann, S., Otto, S., Dozier, B., and Kuhlman, K.: Joint geophysical and numerical insights of the coupled thermal-hydro-mechanical processes during heating in salt, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16935, https://doi.org/10.5194/egusphere-egu23-16935, 2023.

EGU23-17099 | Orals | ERE3.3 | Highlight

Highlights and lessons learned from groundwater investigations in the framework of Nagra’s exploratory boreholes for a deep geological repository 

Emiliano Stopelli, Niklaus Waber, Michael Heidinger, Gesine Lorenz, Herwig Müller, and Dani Traber

The Swiss National Cooperative for the Disposal of Radioactive Waste (Nagra) carried out an underground investigation program for a comparative evaluation of possible sites for a deep geological repository (DGR) for nuclear waste. Between 2019 and 2022, one inclined and eight vertical multi-purpose exploratory boreholes were drilled in three siting regions in northern Switzerland.

In the frame of these works, accurate groundwater sampling and analytical data interpretation has been fundamental to derive solid information on groundwater composition, evolution, and residence times in aquifers limiting the low permeability sequence of the host rock (Opalinus Clay) and the confining units.

Eighteen deep groundwater samples were successfully collected from the Malm, Keuper and Muschelkalk aquifers at depths between approx. 350 m and 1150 m below ground level. The following selected highlights and lessons learned regarding hydrochemical groundwater characterisation will be presented:

  • Procedures to correct analytical results for the contamination of groundwater with different types of drilling fluids, using artificial and environmental tracer data and geochemical modelling approaches;
  • Krypton-81 (T1/2 229 ka) in the groundwaters was successfully analysed and, combined with hydrochemical and isotopic data, helped to constrain groundwater mixtures and model residence times far beyond the classical carbon-14 method;
  • Tools to cope with technical challenges at a drill site resp. in deep exploratory boreholes (i.e. time constraints, low groundwater flow rates).

We demonstrate that a high level of quality for hydrochemical and isotope data of groundwaters can be reached even under challenging operational conditions.

The hydrochemical data of groundwater and the profiles of natural tracers in pore water are relevant datasets to constrain the site model used in the site selection process and in the long-term performance assessment for a DGR.

How to cite: Stopelli, E., Waber, N., Heidinger, M., Lorenz, G., Müller, H., and Traber, D.: Highlights and lessons learned from groundwater investigations in the framework of Nagra’s exploratory boreholes for a deep geological repository, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17099, https://doi.org/10.5194/egusphere-egu23-17099, 2023.

EGU23-17145 | Orals | ERE3.3

Bentonite and concrete: Efficient barrier materials for actinide retention under hyperalkaline conditions at increased ionic strengths and in presence of organics 

Katja Schmeide, Thimo Philipp, Nina Huittinen, Claudia Sieber, and Jérôme Kretzschmar

The safe disposal of radioactive waste from operation and decommissioning of nuclear power plants in geological repositories requires the application of multiple barriers to isolate the waste from the biosphere. Bentonite and cementitious materials are foreseen as buffer and borehole sealing material or for stabilization purposes. Pore waters of the North German clay deposits are characterized by high ionic strengths up to 4 M [1,2]. The contact of such saline formation waters with concrete will result in an enhanced corrosion of concrete and to the evolution of highly alkaline cement pore waters (10 < pH < 13), which in turn, can react with the bentonite buffer as well as with the clay host rock, changing their retention potential towards radionuclides. Moreover, the role of organics (as admixtures in cement-based materials or waste constituents [3]) on actinide retention has to be studied.

The U(VI) retention on Ca-bentonite in mixed electrolyte solutions (‘diluted Gipshut solution’, I = 2.6 M) was found to be very effective at pH>10, even in the presence of carbonate and despite the prevalence of anionic aqueous uranyl species [4]. By means of luminescence and X-ray absorption spectroscopy, the U(VI) speciation could be clarified. A substantial contribution of calcium (aluminum) silicate hydrates (C-(A-)S-H), formed as secondary phases in the presence of Ca due to partial dissolution of alumosilicates at hyperalkaline conditions, to the retention of anionic actinide species in clayey systems was shown [5]. Citrate and 2-phosphonobutane-1,2,4,-tricarboxylate (PBTC) were found to reduce U(VI) retention only when present at high concentrations.

The U(VI) and Eu(III)/Cm(III) retention by C-A-S-H, formed due to Al-rich additives in cement formulations, was studied applying samples with Ca/Si molar ratios of 0.8, 1.2 and 1.6, representing different alteration stages of concrete, and with increasing Al/Si molar ratios of 0, 0.06 and 0.18 in each series. Furthermore, the impact of temperature (25°C, 100°C, 200°C) on both the C-A-S-H structure and the actinide retention mechanism was studied. Solid-state 27Al and 29Si NMR spectroscopy along with XRD revealed that enhanced temperatures increase the crystallinity of the material with the appearance of neoformed crystalline phases. Surface-sorbed, interlayer-sorbed or incorporated actinide species were detected by luminescence spectroscopy. Actinide mobilization due to high ionic strengths or presence of organics (gluconate, PBTC or nitrilotriacetate (NTA)) was very low [6,7].

The results show that both bentonite and cementitious material constitute an important retention barrier for actinides under hyperalkaline conditions at increased ionic strengths and in presence of organics.

Acknowledgement. This work was supported by the German Federal Ministry for Economic Affairs and Energy (BMWi) within the GRaZ II project (no. 02E11860B) and by the European Union’s Horizon 2020 Research and Innovation Programme (CORI project, no. 847593).

References:

[1] Lommerzheim, A. et al. TEC-08-2014-Z. DBE Technology (2014).

[2] Brewitz, W. GSF-T 136 (1982).

[3] Altmaier, M. et al. EPJ Nuclear Sci. Technol. 8, 27 (2022).

[4] Philipp, T. et al. Sci. Tot. Environ. 676, 469-481 (2019).

[5] Philipp, T. et al. Sci. Total Environ. 842, 156837 (2022).

[6] Wolter, J.-M. et al. Sci. Rep. 9, 14255 (2019).

[7] Dettmann, S. et al. Front. Nucl. Eng. (under review).

How to cite: Schmeide, K., Philipp, T., Huittinen, N., Sieber, C., and Kretzschmar, J.: Bentonite and concrete: Efficient barrier materials for actinide retention under hyperalkaline conditions at increased ionic strengths and in presence of organics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17145, https://doi.org/10.5194/egusphere-egu23-17145, 2023.

EGU23-17181 | Posters on site | ERE3.3 | Highlight

Josef Underground Research Laboratory 

Jiří Šťástka

The Centre of Experimental Geotechnics (CEG) is an experimental department of the Faculty of Civil Engineering of the Czech Technical University (CTU) in Prague. The CEG operates the Josef Underground Laboratory (the Josef UL) situated in a former exploration mine (the Josef Gallery) that was excavated in connection with potential gold mining. This facility provides practical courses for students and also provides a unique location for the conducting of experimental and research projects. The Josef Gallery was substantially reconstructed to form the Josef Underground Laboratory in 2007. The most important role of this underground research facility is to provide practical in-situ training in the fields of geotechnical engineering, geology, geochemistry, radiochemistry, radioecology etc. The training of future experts in this authentic underground setting involves the participation of several other Czech universities and numerous experienced specialists from outside the academic sphere. The IAEA (International Atomic Energy Agency) has added the Josef UL to its prestigious list of international training centres and the Josef Underground Laboratory is a member of the Underground Research Facilities network.

The Josef underground complex provides excellent opportunities for both the conducting of in-situ research and teaching. The advantages of the facility include its varied geological conditions (tuffs, tuffites and granitic rocks) and excellent infrastructure which, together, form a modern and unique research and teaching facility. The total length of the reconstructed and ready-for-use galleries is currently over 5 km and the rock cover varies from 0m to 170m. Support for the experimental research conducted in the underground complex is provided by an experimental hall, laboratories and administration facilities that are housed in a specially-reconstructed surface building located near to the entrance to the Josef Gallery.

The Josef complex has been designed as a multi-disciplinary rather than a single topic-oriented facility. The size of the Josef underground gallery and its unique geological diversity make it ideal for the conducting of experimental research across a wide spectrum of scientific disciplines.

The research projects in which CEG staff participate and which are conducted or partially conducted at the Josef Underground Laboratory fall under the areas of underground and surface structures, modern tunnelling technologies, crash testing, ecology, waste storage and disposal, gas and heat storage, underground architecture and robotics.

How to cite: Šťástka, J.: Josef Underground Research Laboratory, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17181, https://doi.org/10.5194/egusphere-egu23-17181, 2023.

EGU23-17192 | Posters on site | ERE3.3

Progressive Excavation Disturbance Zone Evolution during and Post Mine-by Tunneling (PRECODE) – Insight into New Underground Research Laboratory 

Pooya Hamdi, Peter Achtziger, Seyyedmohammad Moulaeifard, Antonio Rinaldi, Virginie Durand, Linus Villiger, Florian Amann, and Stefan Wiemer

Development of brittle damage around nuclear waste repository tunnels is a common phenomenon in massive rocks in highly-stressed conditions. The time-dependent brittle fracturing may lead to an interconnected fracture network (i.e. excavation damage zone; EDZ) and induced seismicity. Within the excavation damage zone (EDZ), the permeability is often enhanced and – in the framework of nuclear waste disposal – may provide preferential pathways for radionuclide migration. Therefore, a comprehensive understanding of the brittle fracturing requires multi- multidisciplinary monitoring systems to allow for spatial and temporal characterization of the EDZ. Recently, the Swiss Federal Institute of Technology (ETH) Zurich established a new Underground Research Laboratory (URL) in Southern Switzerland in the old Bedretto Gallery. Within the PRECODE experiment, we will establish a new, experimental tunnel as a branch from the existing tunnel, which will be densely instrumented with strain, pore pressure and acoustic emission sensors prior to the excavation. The main objectives of the PRECODE experiment are to understand: (1) short-term rock mass behavior and EDZ formation during tunneling; (2) long-term fracture propagation within the EDZ associated with environmental conditions (fluctuations in humidity and temperature); (3) permeability changes with time around an open excavation and (4) the impact of tunneling on the nearby fault zones. This study outlines an overview of the project objectives, details of the planned monitoring systems, and some preliminary results obtained from a baseline study of characterization of the +40-year EDZ from the existing Bedretto Tunnel.

Bedretto Team: The team involves more than 30 people from ETHZ and 10 research institutes and companies involved in the Bedretto Laboratory (see http://www.bedrettolab.ethz.ch/en/home/ for more details)

How to cite: Hamdi, P., Achtziger, P., Moulaeifard, S., Rinaldi, A., Durand, V., Villiger, L., Amann, F., and Wiemer, S.: Progressive Excavation Disturbance Zone Evolution during and Post Mine-by Tunneling (PRECODE) – Insight into New Underground Research Laboratory, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17192, https://doi.org/10.5194/egusphere-egu23-17192, 2023.

EGU23-1030 | ECS | Posters on site | ERE3.4

Residential heating and cooling with Aquifer Thermal Energy Storage (ATES) on city scale 

Ruben Stemmle, Haegyeong Lee, Philipp Blume, and Kathrin Menberg

Aquifer thermal energy storage (ATES) is a promising technology for sustainable and climate-friendly space heating and cooling which can contribute to the energy transition, as it causes significantly less greenhouse gas (GHG) emissions than conventional space heating and cooling technologies. Using 3D thermo-hydraulic numerical models, this study quantifies the technical potential of shallow low-temperature ATES in the city of Freiburg, Germany. The numerical models consider various ATES configurations and different hydrogeological subsurface characteristics relevant for the study area. Based on the modeling results, spatially resolved ATES power densities for heating and cooling are determined and compared to the space heating and cooling energy demand. High ambient groundwater flow velocities of up to 13 m d-1 cause relatively high storage energy losses resulting in maximum ATES power densities of 3.2 W m-2. Yet, these still reveal substantial heating and cooling energy supply rates achievable by ATES systems. While heating energy supply rates of larger than 60 % are determined for about 50 % of all residential buildings in the study area, the cooling energy demand could be supplied entirely by ATES systems for 92 % of the buildings. Also, ATES heating alone could allow for greenhouse gas emission savings of up to about 70,000 tCO2eq a‑1, equivalent to 40 % of the current greenhouse gas (GHG) emissions from space and water heating in the study areas’ residential building stock. The proposed modeling approach in this study can also be applied in other regions with similar hydrogeological conditions to obtain estimations of local ATES supply rates and support city-scale energy planning.

How to cite: Stemmle, R., Lee, H., Blume, P., and Menberg, K.: Residential heating and cooling with Aquifer Thermal Energy Storage (ATES) on city scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1030, https://doi.org/10.5194/egusphere-egu23-1030, 2023.

EGU23-2795 | ECS | Posters on site | ERE3.4

Simulation of Re-Used Basin Structures for Long-Term, Large-Scale Sensible Thermal Energy Storage 

Christoph Bott, Mathias Ehrenwirth, Christoph Trinkl, Tobias Schrag, and Peter Bayer

Heat storages have become an increasingly important component of innovative energy systems on a  district-level, characterized by a high share of renewable energy and/or a high degree of autarky. Large-scale thermal energy storages are required to compensate for the seasonal mismatch between demand and supply; they form a central junction in the distribution network of a district, linking the various sources and sinks.

Established geothermal heat storage systems (Aquifer/borehole thermal energy storages) already show a high market availability. Based on a large number of customized implementations, substantial expertise and best practice is available in this sector. Additionally, closed systems based on artificial basins (Tank, pit, water-gravel thermal energy storages) were developed for site-independent implementation;  they can be distinguished by different components, materials and construction methods. However, they still lack market maturity, with two key aspects as critical barriers: firstly, building complexity of such facilities is high, resulting in high investment costs. Secondly, planning processes are still subject to a significant degree of uncertainty. Consequently, such sophisticated and expensive projects are often contrasted with a high financial and technological risk.

In order to tackle both of these key issues, we present two solutions within our study. We introduce an interesting alternative based on recycling. As high investment costs result mainly from excavations and expenses for structural components, we suggest the re-use of existing infrastructures and artificial basin installations. In our presentation, we estimate the potential of these technical conversions. From a conceptual perspective, we demonstrate the variety of possible types of infrastructures and analyze their suitability for being re-used as storage based on different requirements, e.g., accessibility, integrability, competing interests and legal constraints. From this, we derive an overall assessment with regard to the suitability of sites and highlight advantages and weaknesses of the various types of infrastructures.

Still, any implementation can only be successful if the structure used shows sufficient performance. This is in high contrast to the usually considerable deviations from common design conventions for closed seasonal thermal energy storages, e.g., geometrically with respect to the surface/volume ratio. Here, the possible maximum storage capacity, charging/discharging power and efficiency of a re-used infrastructure after its conversion needs to be analyzed from a technical perspective. To address this suitability aspect, we use a recently developed simulation tool “STORE”, which allows versatile modelling and evaluation of storage design scenarios on a component level using a 2.5‑D approach. In our presentation, we employ “STORE” to a case study and examine a potential re-use of a former water-treatment basin. After applying common boundary conditions of an energy system and setting different design scenarios, we focus on performance indicators and reveal the best technical solution for this specific case study and discuss transferability of the results.

Finally, we use our study to demonstrate, under which conditions the conversion and re-use of artificial infrastructures can be a promising approach: By reducing investment costs of large-scale, closed thermal energy storage systems, it can pave their way to full market availability.

How to cite: Bott, C., Ehrenwirth, M., Trinkl, C., Schrag, T., and Bayer, P.: Simulation of Re-Used Basin Structures for Long-Term, Large-Scale Sensible Thermal Energy Storage, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2795, https://doi.org/10.5194/egusphere-egu23-2795, 2023.

EGU23-6500 | ECS | Posters on site | ERE3.4

THM modelling of seismic velocities changes at DeepStor heat storage demonstrator 

Clara Fraile, Emmanuel Gaucher, and Thomas Kohl

In Central Europe, the thermal energy required for heating and cooling represents a major CO2 emitter in the energy sector. Seasonal underground heat storage offers the option to store a large amount of excess heat in summer for usage in winter and, with that, decrease the need for conventional sources of energy. Today, high-temperature aquifer thermal energy storage (HT-ATES) systems are attracting large interest for securing a heat demand in a sustainable manner.

In HT-ATES systems, hot water is injected into a reservoir over the summer months while exchanged cold water is injected over the winter season. These changing temperatures and pressures will affect the geomechanical and thermo-hydraulic properties of the reservoir and the surrounding layers. Monitoring the changes in the reservoir properties is key to run a heat storage system safely and efficiently. We try to determine if active seismic imaging could be a suitable method to characterize the time-space evolution of the reservoir.

With view on designing future geophysical assessment and monitoring systems, we perform thermo-hydro-mechanical (THM) modelling, using MOOSE and TIGER applications, with characteristics based on the DeepStor demonstrator under development in the north of Karlsruhe (Germany), at KIT, to determine the changes in the poroelastic properties of the underground. The first three layers model includes different mechanical properties with one borehole. The simulation of hot water injection over a period of time allows to quantify its effect on the underground material properties. Besides the DeepStor demonstrator expected operational frame, we test additional injection schemes with varying underground properties to simulate the different ranges of porosity changes and look at their effects on the elastic properties.

The changes in the parameters from the THM model are linked to seismic sensitive variables, such as velocities and impedances, using empirical equations. Hence, we can quantify the effects of injection on such variables and determine if it would be possible to detect them with active seismic surveys.

How to cite: Fraile, C., Gaucher, E., and Kohl, T.: THM modelling of seismic velocities changes at DeepStor heat storage demonstrator, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6500, https://doi.org/10.5194/egusphere-egu23-6500, 2023.

EGU23-6706 | ECS | Posters on site | ERE3.4

Modelling the combination of aquifer thermal energy storage with remediation of contaminated groundwater 

Maximilian Dörnbrack, Dr. Chaofan Chen, Dr. Haibing Shao, and Prof. Dr. Holger Weiß

In the scientific park of Leipzig an Aquifer Thermal Energy Storage (ATES) system is planned in combination with the remediation of groundwater contaminated with chlorinated volatile organic compounds.

During the operation of the ATES system a two-well system is used. The cold groundwater is extracted from one well, and reinjected after heating up through the other well into the aquifer as storage. Later this pumping mode will be reversed and the heated-up groundwater will be extracted as a heating source.

In the most of ATES system, hot water is injected into aquifers at temperature lower than 25°C, while the planned system will inject at temperature of up to 80°C. This leads to a more significant influence on the chemical composition of the groundwater than with lower temperature ATES systems. Additionally laboratory tests from a previous project also show a drastic change in the microbiological biome at 45 and 60°C.

To facilitate the understanding of such impacts, a simplified 2D numerical model has been constructed, simulating both hydraulic and heat transport process in the aquifer. The model is currently being used as a planning tool to predict the propagation of the thermal plume, as well as designing the pumping rate of the circulation system. The model results already show a larger thermal-affected zone due to the high-temperature injection compared to low temperature ATES system.

Future application of the model is to investigate the impact of thermal signal on the mobilization of the contaminants, and also its contribution to the natural attenuation through change in the microbiological biome and activity, which determines the degradation rate in most cases. The overall goal of the project is to develop a fully coupled THC model that will be used to simulate the thermal, hydraulic and chemical processes associated with the thermal usage of a contaminated aquifer in urban areas.

How to cite: Dörnbrack, M., Chen, Dr. C., Shao, Dr. H., and Weiß, P. Dr. H.: Modelling the combination of aquifer thermal energy storage with remediation of contaminated groundwater, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6706, https://doi.org/10.5194/egusphere-egu23-6706, 2023.

EGU23-6913 | ECS | Posters on site | ERE3.4

MD-BTES construction and integration into a district heating grid: Insights and targets of SKEWS and PUSH-IT projects 

Claire Bossennec, Ingo Sass, Lukas Seib, Matthias Landau, and Tien Hung Pham

Heat storage in crystalline basement rocks is a promising technology because it can provide a reliable source of heat and help to increase the efficiency of energy systems, and reduce greenhouse gas emissions. BTES systems work by circulating water in multiple borehole heat exchangers (BHE). However, BTES systems can be expensive to install, as they are sub-surface installations which require the drilling of medium-deep boreholes into often complex, sometimes fractured, heterogeneous lithologies.  Therefore, the geological uncertainties must be integrated from the early planning stage on.

This contribution focuses on the insights gained in the SKEWS (Seasonal Crystalline Borehole Thermal Energy Storage) project (research project SKEWS, project administrator Jülich, funding code 03EE4030A) and how these will be developed and rolled out in the Horizon Europe PUSH-IT project into follow-up sites at the European scale. The SKEWS project implements the world’s first demo site for Medium-Deep Borehole thermal energy storage in crystalline rocks, with three 750 m deep boreholes separated from an 8.6 m distance, drilled at campus Lichtwiese from the Technical University of Darmstadt, Germany.

From the drilling campaign carried out in the summer and autumn 2022, new insights have been gained into the implementation of BTES in such an urban environment. These insights go from the drilling technologies and verticality to the installation of the BHE. This knowledge and know-how will then be developed during the test phase and with the integration and surface connection of the BHE field with a section of the district heating grid.

Borehole heat exchanger installation, with insights on the experience gained on the optimal design, drilling, and completion, will be detailed. The planning and first results of the reservoir test phase and monitoring through optic fibre will be presented, as well as perspectives on targeted digital twin geological static and dynamic modelling of the reservoir and the district heating grid in a co-simulation workflow.

Such outputs will allow quantitative estimation of the technical and economic potential of the MD-BTES systems in existing or future district heating grids.

How to cite: Bossennec, C., Sass, I., Seib, L., Landau, M., and Pham, T. H.: MD-BTES construction and integration into a district heating grid: Insights and targets of SKEWS and PUSH-IT projects, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6913, https://doi.org/10.5194/egusphere-egu23-6913, 2023.

EGU23-7241 | ECS | Posters on site | ERE3.4

Drilling engineering experience gained from MD-BTES construction phase of SKEWS demo-site 

Matthias Landau, Lukas Seib, Claire Bossennec, Heiko Handke, Jürgen Muhl, Jürgen Stumpf, Uwe Schindler, and Ingo Sass

As a result of the current energy crisis triggered by war and increasing shortage of resources, renewable energy sources are becoming increasingly important. The storage of heat from fluctuating energy sources is an essential component for independent and base-load capable energy supply. A promising technology are medium-deep geothermal storage systems, which store excess heat in the crystalline subsurface and offer significant advantages over near-surface geothermal storage systems. At the Lichtwiese campus of the Technical University of Darmstadt, the world's first medium-deep research geothermal storage system was constructed in the crystalline bedrock with three 750 m deep boreholes with a distance of approx. 8.6 m (research project SKEWS, project administrator Jülich, funding code 03EE4030A). The outer casing of the coaxial system has a diameter of 7", on which an attached glass fiber cable records temperature and strain measurements. Research operations began in the spring of 2023, which consists of an initial enhanced Geothermal Response Test (eGRT) followed by five heating and cooling phases.

The experience and knowledge acquired are intended to demonstrate the basic construction and operational feasibility of such storage systems, as well as to be used as a basis for the planning, dimensioning, construction and costing of future projects.

With the current project status, it has already been possible to evaluate the processes of the drilling phase and their effects on the drilling operation. The encountering of deviating geological and hydrogeological conditions to the prognosis from the planning phase required, among other things, the change of the drilling technique from water hammer to rotary drilling with a clay-fresh-water fluid and accordingly also affected the verticality of the drillings. Based on the detailed drilling data recorded and the geological conditions explored, the drilling phase of the storage system could be evaluated in terms of its material usage, drilling accuracy, costs and energy consumption.

How to cite: Landau, M., Seib, L., Bossennec, C., Handke, H., Muhl, J., Stumpf, J., Schindler, U., and Sass, I.: Drilling engineering experience gained from MD-BTES construction phase of SKEWS demo-site, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7241, https://doi.org/10.5194/egusphere-egu23-7241, 2023.

EGU23-8618 | ECS | Orals | ERE3.4

Fully coupled heat transport modelling in porous media considering transfer between phases 

Haegyeong Lee, Andy Wilkins, Philipp Blum, Peter Bayer, and Gabriel Rau

Accurate prediction of heat transport in porous media is important for understanding geoscience processes and properties and to design applications, for example geothermal energy systems. While heat transport is generally modelled assuming of local thermal equilibrium (LTE), i.e., instantaneous heat transfer between the fluid and solid phases, previous studies have demonstrated presence of local thermal non-equilibrium (LTNE), i.e., delayed heat transfer, in natural porous materials. However, factors that influence the rate of heat transfer between the phases and their significance for inherently heterogeneous natural systems remain unknown and untested. We develop an open-source fully coupled, finite-element application to numerically simulate heat transfer between the fluid and solid phases. This is based on the Multiphysics Object-Oriented Simulation Environment (MOOSE) and allows massively parallel modelling of heat transport including customized transfer rates. We verify our model using an analytical solution considering LTNE and illustrate several applications. The model can be used to investigate processes that affect heat transport such as heat transfer mechanisms and their dependence on different hydrogeological conditions.

How to cite: Lee, H., Wilkins, A., Blum, P., Bayer, P., and Rau, G.: Fully coupled heat transport modelling in porous media considering transfer between phases, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8618, https://doi.org/10.5194/egusphere-egu23-8618, 2023.

EGU23-8903 | ECS | Orals | ERE3.4

Integration of at-scale field observations and application of surrogate modelling strategies for optimal design of ATES systems in the Sherwood Sandstone aquifer 

Vasileios Christelis, Andrés González Quirós, Corinna Abesser, David Boon, Edward Hough, and Michael Spence

Aquifer Thermal Energy Storage (ATES) systems use reversible abstraction and injection in combination with warm and cold wells to provide efficient heating and cooling solutions at scales up to ~0.5 MW per installation. It has been shown that these systems are able to improve the efficiency of thermal installations, but rely on an appropriate design, especially when several ATES systems share the same aquifer. In this work, we combine groundwater flow and heat transport numerical models with optimization frameworks to investigate the optimal distribution of wells for avoiding system interferences and improving recovery efficiency. To that end, we employ hypothetical modelling scenarios based on geological properties of the Sherwood Sandstone bedrock aquifer as one of the main potential targets for the development of ATES systems in the UK. Some of the available information is acquired from activities at the UK Geoenergy Observatory (UKGEOS) in Cheshire, which is under construction and will be equipped with a range of technologies and monitoring sensors for research, training, and on-site experiments. The Observatory will be open to industry and the research community to evaluate technological options for shallow geothermal use and energy storage and to gain a detailed hydraulic and thermal characterization of the Sherwood Sandstone. As practical application, we present an approach for the optimal design of the installation of multiple doublets that consider various spatial features as decision variables. The benchmark solution is provided by a simulation-optimization framework that uses a direct coupling of the groundwater flow and heat transport numerical model with an evolutionary algorithm. This approach is typically hampered by increased computational cost due to the time-intensive numerical simulations and the thousands of objective function evaluations required until convergence of the evolutionary algorithm is achieved. Therefore, we also investigate a lower computational resource strategy by applying surrogate-assisted optimization methods which are either embedded in the operations of the evolutionary algorithm or utilize an adaptive-recursive framework. The performance of the surrogate-based optimization method is assessed via several independent optimization trials and for different computational budgets. The ability of the surrogate-based optimization frameworks to approximate a near global solution is compared against the benchmark solution.

How to cite: Christelis, V., González Quirós, A., Abesser, C., Boon, D., Hough, E., and Spence, M.: Integration of at-scale field observations and application of surrogate modelling strategies for optimal design of ATES systems in the Sherwood Sandstone aquifer, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8903, https://doi.org/10.5194/egusphere-egu23-8903, 2023.

EGU23-9471 | Orals | ERE3.4 | Highlight

Chances and risks of aquifer thermal energy storage (ATES) systems 

Philipp Blum, Kathrin Menberg, Paul Fleuchaus, Simon Schüppler, Ruben Stemmle, Florian Barth, and Peter Bayer

Decarbonising the heating and cooling sector is crucial for reducing our global CO2 emissions. One promising option for environmental friendly energy supply in buildings is the use of shallow geothermal energy (SGE) (< 400 m depth) such as ground source heat pump (GSHP), groundwater heat pump (GWHP) and tunnel geothermal systems. In addition, renewable energy sources such as wind and solar are typically intermittent in nature, which is why they are characterized by an abundant but limited instantaneous availability. Peak time shaving and shifting by thermal energy storage are therefore considered as a key to the transition of the heating and cooling sector from fossil-based to zero-carbon. To balance these temporal variations in the availability and demand, Underground Thermal Energy Storage (UTES) systems could be used. In particular, Aquifer Thermal Energy Storage (ATES) systems are characterized by high storage capacities and low storage costs and is, therefore, drawing growing attention worldwide. However, only little is known about global application and distribution of ATES systems. Hence, this talk will provide an overview of the present and future potential of ATES systems including the chances and risks associated with such systems, which can play an important part in achieving our ambiguous climate targets.

How to cite: Blum, P., Menberg, K., Fleuchaus, P., Schüppler, S., Stemmle, R., Barth, F., and Bayer, P.: Chances and risks of aquifer thermal energy storage (ATES) systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9471, https://doi.org/10.5194/egusphere-egu23-9471, 2023.

EGU23-11413 | ECS | Orals | ERE3.4

Analyzing clogging and scaling processes in carbonate and siliciclastic ATES systems based on column and batch experiments 

Alireza Arab, Leonie Gabler, Martin Binder, Christian Engelmann, Christine Viehweger, and Traugott Scheytt

Aquifer thermal energy storage (ATES) is one of the main types of geo-storage concepts aimed at an efficient energy supply and for achieving a low-carbon energy balance. In ATES, thermal energy is stored underground for later use; for instance, by intentionally injecting warm water - heated up by excess heat energy of industry and commerce - into the aquifer, and recovering it later for heating purposes, e.g., during the winter period. However, a significant number of ATES projects suffer from operational and maintenance issues or failures. Mineral precipitation (scaling) and flocculation, or microbial growth are major risks for ATES. By reducing the permeability in reservoirs, these processes threaten medium- to long-term operational reliability.  

The BMBF-funded research project ‘UnClog-ATES’ comprehensively investigates clogging and scaling in two typical reservoirs for ATES systems (siliciclastic sediments and carbonate-bearing sediments) which are widely distributed and exhibit different reactivity with respect to temperature and hydrochemical changes. Laboratory-scale flow-through column experiments as well as batch reactor experiments will be performed to simulate transport under representative ATES conditions (pressure, temperature, hydraulics, and chemical composition). Additionally, countermeasures (e.g., scaling inhibitors, acids, or CO2) will be investigated to maximize the potential of ATES in the future. Finally, based on numerical reactive solute transport models, a catalog of criteria for users and decision-makers will be created to facilitate an initial site assessment in order to minimize the operational risk of ATES at this level.

How to cite: Arab, A., Gabler, L., Binder, M., Engelmann, C., Viehweger, C., and Scheytt, T.: Analyzing clogging and scaling processes in carbonate and siliciclastic ATES systems based on column and batch experiments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11413, https://doi.org/10.5194/egusphere-egu23-11413, 2023.

EGU23-11492 | ECS | Posters on site | ERE3.4

Aquifer Thermal Energy Storage in the UK: current status and challenges to uptake 

Geraldine Regnier, Hayley T. Firth, and Matthew D. Jackson

Aquifer Thermal Energy Storage (ATES) has the potential to provide large scale, seasonal, low carbon heating and cooling to the built environment. Currently, heating of buildings represents 23% of the UK’s greenhouse gas emissions. ATES could therefore be a key technology for the UK to meet its net zero targets, particularly as cooling demand is set to increase in a warming climate.

The potential for ATES developments in the UK is significant: it has a seasonal climate, and many major cities are underlain by suitable storage aquifers such as the Chalk beneath London, and the Permo-Triassic sandstone aquifers beneath Manchester and Liverpool. Despite this large potential, the uptake of ATES in the UK is limited, with only 11 installations over the past 16 years. 10 of these installations target the Chalk aquifer and 9 are located in London. In this study, we report the current status of ATES installations in the UK. A case study of an operational ATES system in the fractured Chalk aquifer in London is presented. Monitoring data over a 7 year period are used to quantify the performance of the system, with key metrics such as energy balance and thermal recovery being reported.

We also report challenges to uptake of ATES in the UK. Poor performance due to a lack of understanding of the technology is observed. Inadequate monitoring of the systems (temperature, flowrate) as well as large imbalances between heating and cooling loads are identified as key issues with some current ATES systems in the UK. The complexity of the UK aquifers is also identified as a potential challenge, as geological heterogeneity has been shown to lower system efficiency and increase the risk of well interference. Finally, a lack of awareness of ATES technology is also identified as a key barrier to uptake, so it is not considered as an option to provide heating and cooling to buildings by key stakeholders such as local and national planners and policy makers.  We report ongoing work to overcome these challenges.

How to cite: Regnier, G., Firth, H. T., and Jackson, M. D.: Aquifer Thermal Energy Storage in the UK: current status and challenges to uptake, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11492, https://doi.org/10.5194/egusphere-egu23-11492, 2023.

EGU23-11517 | ECS | Posters on site | ERE3.4

Co-Simulation of Seasonal Aquifer Thermal Energy Storage and District Heating Grid using the Functional Mock-Up Interface 

Max Ohagen, Hung Pham, Claire Bossennec, and Ingo Sass

District heating grids (DHG) face the problem of seasonal variability and peak demands, e.g., there is a high demand for heat in winter and a low demand in summer. Operators of district heating networks and energy suppliers are therefore seeking solutions to store heat and access it at peak times, thus reducing the use of carbon-emitting heat sources. Aquifers are well suited for heat storage because of high storage capacity relative to the surface occupancy and reasonably high recovery efficiency, if geological suitable. In this study, the potential of Aquifer Thermal Energy Storages (ATES) contribution in decreasing seasonal peak heat loads is investigated by numerical modelling. Each part of the overall system (surface and subsurface) is modelled in their corresponding simulation environment. They are numerically coupled with a novel approach, allowing for highest accuracy in both subsystems. The District Heating Grid is modelled in the object-oriented modelling language Modelica including the Open-Source library MoSDH. Using the Functional Mock-Up Interface (FMI) the Modelica models are exported to executable Functional Mock-Up Units (FMU). The groundwater flow and heat transport processes are modelled in the finite-element software FEFLOW. By developing a C++ Plug-In for FEFLOW the FMU is imported and dynamically co-simulated. This approach allows for easier adjustments in both subsystems and more coupling options to existing models and softwares.  Through numerical analysis different hydrological and geological scenarios of the ATES and different operational cycles are investigated to determine the long-term efficiency and capacity of the storage. This modelling approach can be used to develop strategies for the operation of the ATES as well as to evaluate in advance whether geological conditions are suitable for the particular network situation.

How to cite: Ohagen, M., Pham, H., Bossennec, C., and Sass, I.: Co-Simulation of Seasonal Aquifer Thermal Energy Storage and District Heating Grid using the Functional Mock-Up Interface, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11517, https://doi.org/10.5194/egusphere-egu23-11517, 2023.

EGU23-12390 | ECS | Orals | ERE3.4

Risk assessment of high-temperature heat storage (HT-ATES) at the DeepStor demonstrator site 

Kai Stricker, Robert Egert, Peter Fokker, Phil J. Vardon, Jan Diederik van Wees, Eva Schill, and Thomas Kohl

In central Europe, the majority of the CO2 emissions in the energy sector are related to the provision of building and process heat. Due to seasonal fluctuations in demand, especially to provide heat for residential and industrial buildings, local storage of excess heat in summer for utilization in winter is becoming increasingly important. With the current state of technology and foreseeable developments, sufficient amounts of heat can only be stored underground, taking advantage of the large available storage volumes. In contrast to typical near-surface aquifer thermal energy storage (ATES), the utilization of deep reservoirs enables the storage of much larger thermal energies due to potentially significantly higher injection temperatures (e.g. > 80 °C).

Previous studies demonstrated the high potential of deep reservoirs for high-temperature (HT) ATES, in particular for former hydrocarbon reservoirs in the Upper Rhine Graben. However, these studies focused on thermo-hydraulic processes, only rarely considering the impact of coupled mechanical processes. Using the case study of the DeepStor project, a demonstrator for HT-ATES under development in the north of Karlsruhe (Germany), the present study investigates the influence of coupled thermo-hydraulic-mechanical (THM) processes during the operation of HT-ATES systems.

In particular, we investigate the impact of seasonal HT-ATES with biannual injection/production cycles on the stress distribution in the subsurface and subsequently caused displacements in the reservoir and the surface as well as the shear capacity at faults. This study further aims at improving the understanding of poro- and thermoelastic processes related to HT-ATES. Whereas the thermoelastic component dominates the vertical displacements at the top of the reservoir, the uplift at the surface is primarily controlled by the poroelastic component. Furthermore, an assessment of potential risks such as surface uplift or shear capacity at faults is performed. Our results show that surface uplift is primarily controlled by the reservoir depth, Young’s modulus, and the injection/production flow rate.

How to cite: Stricker, K., Egert, R., Fokker, P., Vardon, P. J., van Wees, J. D., Schill, E., and Kohl, T.: Risk assessment of high-temperature heat storage (HT-ATES) at the DeepStor demonstrator site, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12390, https://doi.org/10.5194/egusphere-egu23-12390, 2023.

The seasonal storage of heat has the potential to reduce greenhouse gas emissions, since it accounts for the seasonal disbalance between heat production and demand in renewable-based energy-systems. High temperature aquifer thermal energy storage (HT-ATES) is a heat storage technology utilising the subsurface and therefore provides high storage capacity with limited above-ground usage, which is especially required in urban areas. Since the temperature difference between the ambient groundwater and the injected water (> 50 °C) results in density differences, convective buoyancy flow can be induced by HT-ATES. This process leads to an uneven heat distribution over the aquifer thickness, reduced storage efficiency and increased thermal impacts. The occurrence and intensity of buoyancy flow is site-specific, since it depends on operational parameters, such as injection temperature, as well as geological parameters, such as aquifer thickness and especially vertical and horizontal permeability.

The geological site considered for HT-ATES storage is located in Hamburg, Germany, using the Miocene Lower Braunkohlensande (brown coal sands) as storage aquifer. This sedimentological formation was deposited in a coastal transition regime between terrestrial and shallow-marine settings and consists mainly of sands. Peat swamps and lagoons formed brown coal, silt and clay layers, which have the potential to hinder convection due to their low permeability, depending on their lateral extent in relation to the size of the induced heat plume by HT-ATES. Lithological classifications of 25 wells provide the data basis for the geological analysis.

The aim of this study is to evaluate the influence of thin low permeability layers on induced buoyancy flow and thus HT-ATES performance, as measured by heat recovery. To this end, a site-specific numerical HT-ATES model is created, which simulates the coupled thermo-hydraulic processes. Different scenarios with varied vertical permeability as well as the number and lateral extent of low-permeability layers show the effect on density-driven buoyancy flow and HT-ATES efficiency. Increasing the vertical permeability by a factor of 10 results in an efficiency decrease from 78 % to 57 % in the 10th storage cycle. The findings serve as a process understanding basis for complex heterogeneous facies models of the HT-ATES site, which will be based on the geostatistical evaluation of site data.

How to cite: Heldt, S. and Bauer, S.: Evaluating the impact of anisotropy and low-permeability layers on high temperature aquifer thermal energy storage performance, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14087, https://doi.org/10.5194/egusphere-egu23-14087, 2023.

The current energy crisis since February 2022, have led governments to put in place short and long-term measures aimed at shielding consumers from the direct impact of the rising energy prices across Europe, and to counteract the continuous economic volatility. The pressure is high for finding solutions to reduce energy imports, and fight against climate change impacts. The numerous debates on climate change such as the COP27 are pushing for a greater acceleration in decarbonising the energy sector. Low carbon sources such as geothermal energy can substantially decrease energy consumptions and costs, especially if included into decarbonized heating and cooling grids (Chicco et al., 2022). The use of geothermal energy for thermal energy production and storage in district heating and cooling (DHC) grids may also be a key element in overcoming short-term energy peaks overcoming of the gap between energy supply and demand, which is still a challenge for the energy transition.  In this framework, underground thermal energy Storage (UTES) systems can be a key element for efficient operation of heating and cooling grids. Here, we present a study aimed at evaluating the performance of one of the most promising underground thermal energy storage systems, which uses boreholes to store heat or cold (BTES). Aimed at testifying the replicability of the used methodology, we replicated the same workflow already presented in Chicco and Mandrone (2022) but on a different area in northern Italy, with similar hydrogeological and thermo-physical characteristics. Based on real field data, the study focused on numerical simulations aimed at understanding how these technologies can be used as backup systems, or when the energy demand overcomes that supplied by conventional heating systems. Obtained results proved again how the integration of these technologies in DHC contexts can contribute to greater energy and economic savings, showing that BTES are very flexible to meet both the base and peak load requests for several users.

Chicco, J.M.; Antonijevic, D.; Bloemendal, M.; Cecinato, F.; Goetzl, G.; Hajto, M.; Hartog, N.; Mandrone, G.; Vacha, D.; Vardon, P.J. Improving the Efficiency of District Heating and Cooling Using a Geothermal Technology: Underground Thermal Energy Storage (UTES). In New Metropolitan Perspectives; Calabrò, F., Della Spina, L., Piñeira Mantiñán, M.J., Eds.; NMP 2022; Lecture Notes in Networks and Systems; Springer: Cham, Switzerland, 2022, 482, 1699–1710. https://doi.org/10.1007/978-3-031-06825-6_164

Chicco, J.M.; Mandrone, G. Modelling the Energy Production of a Borehole Thermal Energy Storage (BTES) System. Energies 202215, 9587. https://doi.org/10.3390/en15249587

How to cite: Chicco, J. and Mandrone, G.: Borehole thermal energy storage (BTES) as backup systems in district heating and cooling contexts: results from numerical simulations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14917, https://doi.org/10.5194/egusphere-egu23-14917, 2023.

EGU23-15738 | ECS | Orals | ERE3.4 | Highlight

The reduction of heating and cooling CO2 emissions with the ATES triplet 

Matthijs S. van Esch, Martin Bloemendal, Niels Hartog, and Philip J. Vardon

Low temperature Aquifer Thermal Energy Storage (ATES) is increasingly used for space heating and cooling. Though these systems emit 3-4 times less CO2 compared to gas heating, they still require a substantial amount of electricity, mostly because of the heat pump (~60%). Storing higher temperatures (HT) to be used for direct heating can be a solution to circumvent the use of a heat pump, however the return temperature after heating is not usually cold enough to use directly for cooling. The first HT ATES systems that are implemented have either no cooling, or alternative means for cooling. With better insulated buildings, that require both heating and cooling, as well as an increased pressure on the electricity grid, an autarkic system is needed that can supply both heating and cooling. The ATES Triplet system aims to do just that.

Similar to and HT ATES system, the ATES Triplet stores hot water at supply temperature needed for space heating in a hot well. Unlike the HT-ATES system, it also aims to store water at the supply temperature for cooling in a cold well. This heat and cold can be harvested by solar collectors and dry coolers (or other green heat/cold sources locally available). After the water extracted from the wells is used to heat/cool the building, the solar collectors and dry coolers can be used to store water at the right temperatures. However, the availability of these sources can be insufficient to reach the required temperatures. A third well is added that functions as a buffer. Water used for heating or cooling can be stored here until there is enough heating/cooling capacity available from the solar collectors and dry coolers to upgrade the water to the required temperature, and store in the hot or cold well. Furthermore, the solar collectors and dry coolers can also be used for direct space heating and cooling, making the entire system and autarkic heating and cooling system.

Initial simulations show a substantial reduction to operational CO2 emissions compared to conventional heating systems. Though a higher initial investment is required, systems also show an increased economic performance over conventional ATES systems and gas heating. Further research will investigate the effect of subsurface conditions, system layout and other operational conditions on the economic and environmental performance of the system.

How to cite: van Esch, M. S., Bloemendal, M., Hartog, N., and Vardon, P. J.: The reduction of heating and cooling CO2 emissions with the ATES triplet, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15738, https://doi.org/10.5194/egusphere-egu23-15738, 2023.

Over the past decade, there have been numerous attempts to use low-grade waste heat (30 oC and 100 oC) for a variety of different applications, especially district heating systems. However, the initial investment in waste heat recovery systems is usually high and the temperature is too low to meet the needs of the different end users. One possible solution is to integrate seasonal thermal energy storage with data centers or other industries that deals with waste heat. This is especially possible when considering borehole thermal energy storage (BTES), as it is highly adaptable, expandable and economical. However, almost all research and technical applications of BTES systems have focused on solar energy storage, with the exception of the projects in Emmaboda (Sweden) and Chifeng (China), where BTES systems have been used to store waste heat. In this paper, the results of a series of measurements on a BTES in Norway are presented and numerical simulations are performed to evaluate the long-term performance of the BTES once it is connected to a continuous supply of waste heat from a data center. The results obtained show how important a long-term prediction of the system performance is for planning and optimization. It was found that the storage temperature and heat recovery of the BTES are lower than expected when the quantity and quality of waste heat is overestimated. It seems that the borehole has the capacity to store  heat at a temperature of more than 75 C, but it may reduce its functionality over time and shorten its lifespan from 30 to 10 years.

How to cite: Gholami, R.: Thermal Energy Storage Integration with Waste Heat: What are the Challenges?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16904, https://doi.org/10.5194/egusphere-egu23-16904, 2023.

EGU23-3308 | ECS | PICO | EMRP2.8

Estimating Curie depth and Heat Flow in the Circum-Arctic Region 

Judith Freienstein, Wolfgang Szwillus, and Jörg Ebbing

We estimate the depth of the Curie isotherm and the associated heat flow for the Circum-Arctic Region using a Monte Carlo Markov Chain approach. In the first step, Curie depths are determined where heat flow measurements are available. For the depth estimates, different parameters and concepts are tested (e.g. pure conduction compared to half-space cooling) in order to assess the uncertainty underlying the depth estimates, but also of the observing point. Hereby, we rely on existing models of the Arctic lithosphere including ArcCRUST and LithoRef18. Half of the calculated Curie depth points show a low sensitivity to the choice of the parameters and models and hence can be regarded as stable, representing the thermal field of the lithosphere and not local effects. Hence, we can use these points as constraints for the second step, where we invert an aeromagnetic anomaly map for both the Curie depth and susceptibility for the Circum-Arctic Region. The new model shows that in areas where reliable constraints exist, the magnetic inversion is preferring to explain the magnetic anomalies with lateral susceptibility distribution, reflecting hereby the main geological features of the region.

How to cite: Freienstein, J., Szwillus, W., and Ebbing, J.: Estimating Curie depth and Heat Flow in the Circum-Arctic Region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3308, https://doi.org/10.5194/egusphere-egu23-3308, 2023.

EGU23-6843 | ECS | PICO | EMRP2.8

A multi-order joint inversion for potential field modelling. 

Luigi Bianco, Mojtaba Tavakoli, Andrea Vitale, and Maurizio Fedi

We propose a joint inversion method for potential fields aiming at recovering reliable models of complex source distributions, as those involving either shallow or deep-seated bodies. In this case, anomalies are characterized by different wavelength-contents, so that we may try to invert jointly the field and its higher-order vertical derivatives. To accomplish this task, we adopt a sequential strategy with a cross-gradient constraint. In this way, we can decouple the combined objective function into three terms: the field, its vertical-derivative and the cross-gradient constraint. For either separate or joint inversion we used a modified focusing algorithm, able to produce compact—source models and to incorporate different types of a-priori information (softer or harder constraints) to better address the ambiguity. The softer constraints include the model weighting function. Specifically, we used the inhomogeneous form of the model weighting function. On the other hand, we introduced harder constraints in the form of a reference model, which allows introducing other information from geology, previous geophysical interpretations or from well logs. The strength of the method is the applicability on both gravity and magnetic field to investigate different scenarios from small-scale (cavity detection) to basin-scale (resources exploration). In all the proposed cases, we obtained a significant model of the different sources at any depths. This is further demonstrated by a strong decrease in the cross-gradient values and a meaningful clusterization in the cross-plot of physical parameters.

How to cite: Bianco, L., Tavakoli, M., Vitale, A., and Fedi, M.: A multi-order joint inversion for potential field modelling., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6843, https://doi.org/10.5194/egusphere-egu23-6843, 2023.

Since the European Union is foreseeing a great increase in the demand of critical raw materials in the coming decades, new ore deposits will have to be explored (European Commision 2020). This has given an incentive to renew the mineral exploration also in Latvia, with a few of the magnetic anomalies known to be caused by various metal ore deposits, all of which lie in the Proterozoic crystalline basement. One of these anomalies lie in the northern part of Latvia – the Strenči magnetic anomaly. A geophysical exploration, involving magnetic, gravity and seismic exploration, as well as core drilling and geochemical analysis, was carried out in the late 20th century (Vetrennikov et al. 1986). Since then, no exploration has been done in the area. But the advent of powerful open-source modelling software which runs on consumer-grade computers has presented an opportunity to build new geophysical models based on old and new data.

To examine the possibility of developing a modern geophysical model of the Stenči magnetic anomaly, an open-source software SimPEG (Simulation and Parameter Estimation in Geophysics) was used (Cockett et al. 2015). The input data was Total Magnetic Intensity (TMI) measurements - a combination of the data from the exploration in the last century and newly acquired data. Quality control measurements of the previous data revealed uncertainty of ±135 nT, giving a rather large uncertainty of approximately 6% for the combined input TMI data. Based on the previous geophysical core logging data it was determined that the magnetic ore maintains a large remanent magnetization which may severely impact the geophysical model (REF). Thus, two models were developed: the first one based on the inversion of the magnetic susceptibility, but the second one using Magnetic Vector Inversion which takes into account remanent magnetization.

The developed models and data from previous research allowed to conclude that the magnetic anomaly is caused by metamorphosed granulite facies crystalline basement rocks of the Proterozoic to a depth of five kilometers. It was also discovered that the magnetization vectors coincide with the general direction of the dip of the rock strata. It was calculated that the predicted ore body contains a significant amount of critical minerals used in renewable energy technologies. A conclusion was made that the previous research has gathered a wealth of data, that can be used in regional crystalline basement research but not for detailed geophysical exploration of anomalies due to the uncertainty of the old data. The use of open-source software has enabled a very cost-effective development of sophisticated geophysical models which are impaired only by the quality of input data. Development of such models may be the first step into geophysical exploration which may attract interest for further investment.

This research was funded by “MikroTik” and University of Latvia Foundation, project no. 2258, and by the University of Latvia grant No. AAp2016/B041//Zd2016/AZ03 project “Climate change and sustainable use of natural resources”.

How to cite: Brants, M. and Karušs, J.: Geophysical modelling of Strenči magnetic anomaly in Latvia using SimPEG open-source software, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6865, https://doi.org/10.5194/egusphere-egu23-6865, 2023.

EGU23-7911 | ECS | PICO | EMRP2.8

ECS (“Extremely Compact Sources”): a new method for potential field data filtering. 

Marco Maiolino and Giovanni Florio

Filtering is a fundamental procedure that precedes further quantitative interpretations. In the potential fields case, filtering is used to separate and discriminate the different contributions of a given dataset. In this note we describe a potential field filtering technique based on a “Extremely Compact Sources” (ECS) approach. ECS filtering method allows us to solve the problem of the interfering anomalies, that could hide the real amplitude and shape of the single contributions. The interference phenomena may involve the superimposition of a regional field generated by deep sources in the study area on local anomalies, or the superimposition of anomalies having similar wavelengths. While many methods have been developed during the years to try to separate regional from local fields, fewer methods have been developed to address the separation of interfering  anomalies caused by similar sources. The ECS technique exploits the inherent ambiguity of potential fields to retrieve an extremely compact source model in which sources are well separated each one from other. In this way, the filtering process can be done through a simple "muting" process (setting the physical property of the cells relative to the unwanted contributions to 0) directly in the source domain. We show applications of the ECS technique to both synthetic and real anomalies to prove the validity of the methodology for both separation of interfering anomalies and filtering of regional fields.

How to cite: Maiolino, M. and Florio, G.: ECS (“Extremely Compact Sources”): a new method for potential field data filtering., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7911, https://doi.org/10.5194/egusphere-egu23-7911, 2023.

Gravity inversion is a process that obtains the spatial structure and physical properties of underground anomalies using surface collected gravity anomaly data. The principle of gravity inversion based on deep learning (DL) is to learn the mapping between gravity anomaly data and geological models by training a neural network with geological models as labels. However, using DL inversion requires generating a large amount of training data for each geological target, resulting in a significant consumption of time and storage space. We propose to use a neural network to approximate the expensive forward computation with a fast evaluation alternative. After training, the network can reproduce gravity anomalies at any observation point. To evaluate the accuracy of the forward model, we use the gravity anomalies predicted by the forward network for inversion network training. In addition, to mitigate the problem of poor generalization of existing DL inversions, we propose to use multi-task learning (MTL). Learning multiple related tasks simultaneously improves the generalization ability of the model, thus improving the performance of the main task. In this paper, a multi-task UNet3+ network is proposed to realize anomaly bodies localization and density reconstruction simultaneously. The test results on the synthetic dataset show that the gravity anomalies predicted by the forward network can be successfully inverted, and the multi-task approach can predict the subsurface geology more accurately than the single-task UNet3+. To further illustrate the effectiveness of the algorithm, we apply the method to the inversion of the San Nicolas deposit in central Mexico, and the inversion results are consistent with known geological information.

How to cite: Lv, M. and Zhang, Y.: Fast forward approximation and multi-task inversion of gravity anomaly based on UNet3+, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8211, https://doi.org/10.5194/egusphere-egu23-8211, 2023.

Scalable machine learning solution for commercial scale three dimensional geophysical inversions

Souvik Mukherjee1, Santi Adavani2*, Alan Morgan3, William N. Barkhouse4, Ronald S. Bell4, Peter G. Lelievre5, Colin G. Farquharson6

1EmPact-AI, USA, 2*RocketML, now at S2 Labs, USA, 3Bell Geospace, USA, 4Drone Geoscience, USA, 5Mt. Allison University, Canada, 6Memorial University, Canada

Abstract

Application of artificial intelligence (AI) and machine learning (ML) based workflows and methodologies for geophysical data processing, imaging, and interpretation are active focus areas in industry and academia. While much progress has been made to demonstrate applicability in many use cases, key bottle neck for widespread commercial use has been the prohibitively high computational cost involved in applying the method for large scale three dimensional inverse problems.

Key changes to the form of the simulated input data used for training and the corresponding design of the architecture of the hidden layers enable approximately O(n) (where n is the number of layers in the network) reduction in the computational complexity of the training architecture. Combined with multi-GPU Distributed Deep Learning (DDL) algorithms optimized specifically for training large scale ML data, this results in significant improvements in resolution of inversion results relative to conventional least squares imaging, while computational efficiency improves by order of magnitude compared to several commonly used open-source ML architectures and platforms.

When deployed for inversion of dense, closely spaced high resolution handheld magnetometer data collected over a buried pipe in a field in Texas, the resolved three-dimensional geometry and location using the new algorithm showed over 6-fold improvement compared to conventional three-dimensional least squares inversion. When applied to an 18-fold larger data set collected by a drone-based magnetometer over a field in California, the buried complex metallic pipe like structure was resolved using little over 2 days of compute time. Similar exercise undertaken in google collab GPU platform using state-of-the-art google tensorflow would have taken 3 – 6 months to complete, suggesting a 50 – 100-fold improvement in computational efficiency.

The method was also benchmarked against Los Alamos National Laboratory’s (LANL) open-source seismic full waveform inversion (FWI) dataset. LANL trained 24000 seismic data sets simulated from various 2D velocity models using 32 P100 Tesla GPU machines in 2 hours. When inferenced on 6000 previously unseen test models, the root mean square error (RMSE) in the inverted normalized velocity models was 0.018. The current workflow on the same data set achieved a comparable RMSE of 0.012 on 6000 unseen test models after training 24000 models in 50 minutes using just 4 GPU (V100) machines, achieving nearly 20-fold improvement in computational efficiency.

In addition to magnetic and seismic data, the method is being developed for applications to electromagnetic and full tensor gravity gradiometer (FTG) data. Given the significant improvements in resolution and computational efficiency, it is expected that successful ground truth based field trials of AI based geophysical data inversion has the potential to unlock several new application areas while dramatically improving the business impact of such applications in existing ones.

How to cite: Mukherjee, S. and Lelievre, P.: Scalable machine learning solution for commercial scale three dimensional geophysical inversions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8297, https://doi.org/10.5194/egusphere-egu23-8297, 2023.

EGU23-10036 | ECS | PICO | EMRP2.8

Supervised machine learning to estimate the basement depth by gravity data 

Andrea Vitale, Gabriellini Gianluca, and Maurizio Fedi

Applications of Machine Learning to the geosciences are increasing in numbers during the last two decades because of its computation power. In this work we propose a method to estimate the basement depth from gravity data using a supervised machine learning approach. We used the Bishop synthetic model to represent a variety of examples of input – target (i.e., gravity data – depth of the basement) training dataset. We so generated a large set of examples, using an overlapping moving window along the profiles in the N-S and E-W direction, associating the corresponding depth values of the basement to each of the windows. Due to its data-driven nature, the neural networks perform better as the number of examples provided in the training phase increases. However, increasing the number of examples leads to a higher computational cost in terms of speed and hardware needed. In the Big Data era this is not a huge issue, thanks to the increasingly present services of cloud computing. We found a good compromise on an average machine between speed and performance by using about 300k examples. A trial-and-error approach was used to find the hyperparameters that have the best compromise between performance and computation time.

We used, as a testing dataset, the gravity data due to a surface modelled from the Himalaya region DEM, with noisy and noise-free data. We found that this avoided overfitting and helped to verify the ability of the trained network to generalize to other cases, even with noisy data. The method was successfully applied also to a real dataset case: the isostatic anomaly of the Yucca Flat sedimentary basin (Nevada, USA) showing good agreement with previous inverse-modelling of the data, even if the author consider a set of layers with increasing density vs. depth, while in our case we used a mean density contrast of -0.7 g/cm3.

How to cite: Vitale, A., Gianluca, G., and Fedi, M.: Supervised machine learning to estimate the basement depth by gravity data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10036, https://doi.org/10.5194/egusphere-egu23-10036, 2023.

Identification of lineament structure plays a vital role in determining the metallogenic area and distribution of the geologic structure. Edge detection methods are mostly used to recognize the lineaments and define the geologic boundaries. Cooperatively using edge detection results of the gravity, magnetic and remote sensing data to recognize lineaments would obtain more geologic information. In this paper, new edge detectors of potential field derivatives are proposed to determine the sources’ boundary, named second tilt derivative, tilt of vertical derivative, and normalized second vertical derivative, respectively. Presented approaches are characterized by producing zero amplitude over sources’ edges and equalizing anomalies from different depths. Compared with original edge detection techniques including other second derivative methods, synthetic examples reveal significant superiorities of suggested approaches in providing more accurate and sharper edges and are especially effective in distinguishing superimposed anomalies. The experiments also demonstrate that the normalization to the edge detectors will make images cleaner and geologic edges more easily captured. Applied to airborne gravimetric and magnetic data in the Pobei area (NW China), the proposed methods display more geologic details and lineaments. Canny, Sobel, and Prewitt operators are applied to extract boundaries of remote sensing image. Lineaments picked by the three different types of data are combined collectively to get a comprehensive lineaments structure interpretation.

How to cite: Li, G. and Liu, S.: Identifying the Lineament Structure Cooperatively Using the Airborne Gravimetric, Magnetic and Remote Sensing Data: A Case Study from the Pobei Area, NW China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10565, https://doi.org/10.5194/egusphere-egu23-10565, 2023.

EGU23-10994 | ECS | PICO | EMRP2.8

Mitigating the effects of remanance in magnetic data processing and inversion 

Xiange Jian and Shuang Liu

Natural remanance will distort the direction of the total magnetization of the magnetic source away from the direction of induction magnetization, which brings difficulties in magnetic data processing and susceptibility inversion. To solve the problem affected by remanance, a magnetic data processing and three-dimensional inversion strategy under remanance conditions is proposed: A method of the total magnetization direction estimation based on multiple correlations is proposed and applied to the processing of magnetic data, which can eliminate the influence of remanance and oblique magnetization. Moreover, the influence of remanance can be considered in the subsequent inversion of magnetic data. Adding the information on the direction of total magnetization into the inversion can more accurately depict the location of the underground magnetic source and recover the physical property distribution. This strategy is applied to the ground magnetic survey data of a mining area in Jiangsu, China. The effects of remanance and oblique magnetization on the processing and inversion of magnetic data are eliminated, and the physical properties and spatial distribution of underground magnetic bodies are restored, which provides geophysical evidence for the study of geological interpretation.

How to cite: Jian, X. and Liu, S.: Mitigating the effects of remanance in magnetic data processing and inversion, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10994, https://doi.org/10.5194/egusphere-egu23-10994, 2023.

EGU23-11664 | PICO | EMRP2.8

Extraction of targeted source information from superimposed magnetic anomalies 

Dan Zhu, Xiangyun Hu, and Shuang Liu

    Magnetic anomalies commonly contain anomalies generated by crustal rocks that have variable mineral compositions and natural remanent magnetizations. Understanding the magnetic susceptibility, remanent magnetization, magnetization direction, and distribution is important for studying the spatial location, formation, and evolution of underground rocks. However, superposition of magnetic anomalies leads to nonnegligible errors of inversion and interpretation. To overcome the interpretation problems caused by source interference, it is necessary for the target magnetic anomaly to be extracted from the observed magnetic anomaly data. Different methods have been developed to separate the magnetic anomalies of different sources using the spectral differences of regional and residual anomalies. Such methods, which include matched filtering, Wiener filtering, and wavelet analysis, have been successfully applied to solve many geological problems. However, these methods cannot extract the anomalies caused by the interference of sources at similar depths because the spectra of the target and residual magnetic anomalies are similar. Effective techniques to obtain additional magnetic information regarding the distribution of rocks at different layers and with different magnetization directions remain lacking.

    Unlike existing regional-residual separation methods used for separating superimposed magnetic anomalies caused by sources with a large depth separation, this study focuses on magnetic anomalies generated by variability of the magnetic parameters and source interference with and without depth differences. We propose a new and useful method for extracting a target magnetic anomaly from an observed magnetic anomaly field. An optimization scheme is proposed for approximating the low-rank component of an observed magnetic anomaly field on the basis of low-rank theory. The magnetic dipole layout is added as a constraint based on the assumed source location. The optimal magnetizations of the magnetic dipoles are then obtained to minimize the objective function. The sum of the magnetic anomalies generated by the magnetic dipoles is calculated as the target magnetic anomaly. The synthetic and field data experiments indicate that the proposed method can accurately and robustly recover target magnetic anomalies. In the field data experiments, the magnetization information of the various isolated sources is derived via 3D fuzzy C-means inversion using the extracted magnetic anomalies. The results show that the proposed method can extract the geometric and physical information of each target magnetic source, even when the observed magnetic anomaly field is generated by various superimposed sources with target source interference at similar depths. The proposed method has the potential for dealing with the separation problems of potential field data with different scales, including the separation of the geomagnetic core field and the lithospheric magnetic field as well as the extraction of target magnetic anomalies from satellite magnetic measurements. Therefore, this approach could be of great importance for geological investigations and mineral exploration.

How to cite: Zhu, D., Hu, X., and Liu, S.: Extraction of targeted source information from superimposed magnetic anomalies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11664, https://doi.org/10.5194/egusphere-egu23-11664, 2023.

EGU23-14706 | ECS | PICO | EMRP2.8

Moho Inversion of East China Sea and Its Adjacent Areas Based on Potential Field Data 

Dingding Wang, Wanyin Wang, and Yimi Zhang

East China Sea and its adjacent areas are an important part of the circum-Pacific tectonic belt, and its fluctuation characteristics of Moho can provide an important basis for the study of the deep structure of the western Pacific. At present, the inversion of Moho depth based on potential field data is an important task. Meanwhile, its inversion accuracy is closely related to the gravity anomaly data quality, and to the density contrasts and inversion algorithm. We use the fast solution algorithm of forward problem for gravity field in a dual interface model to eliminate the gravity influence of terrain and sediments, and adopt the minimum curvature potential field separation method to remove the effect of residual geological bodies. Then we try to identify the Moho gravity anomaly as the regional field which has the strongest correlation with depths estimations from seismic data. Regression analysis and the "3σ" principle are used to delete the constraint points of Moho depth with large deviations, and the Bouguer plate formula is used to estimate the laterally variable density contrasts of Moho. Finally, the Moho depth in East China Sea and its adjacent areas is obtained by the dual-interface fast inversion algorithm, and the inversion deviations are mostly concentrated within 2 km. The inversion result shows that there is an obvious local uplift zone of Moho in East China Sea Basin, while the Okinawa Trough basin is located on a whole Moho uplift. The strike of the two uplift belts has the same change from NE to NNE.

How to cite: Wang, D., Wang, W., and Zhang, Y.: Moho Inversion of East China Sea and Its Adjacent Areas Based on Potential Field Data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14706, https://doi.org/10.5194/egusphere-egu23-14706, 2023.

EGU23-14724 | PICO | EMRP2.8

New Curie depth estimates from satellite conformed aeromagnetic anomaly compilations and their implications for assessing Antarctic subglacial geothermal heat flux heterogeneity  

Fausto Ferraccioli, Jonathan Ford, Ricarda Dziadek, Ben Mather, Egidio Armadillo, Joerg Ebbing, Graeme Eagles, Karsten Gohl, Rene Forsberg, Chris Green, Javier Fullea, and Massimo Verdoya

Geothermal heat flux (GHF) is a critical basal boundary condition that exerts important influences on the initiation of flow of the Antarctic ice sheet and is related to crustal and lithospheric structure and composition. Despite its importance, our knowledge of Antarctic GHF heterogeneity remains limited and this hinders interdisciplinary efforts to better constrain Solid Earth influences on subglacial hydrology and ice sheet behaviour.

Within the framework of the 4D Antarctica ESA project we produced a new continent-wide aeromagnetic anomaly compilation for Antarctica, conformed at longer wavelengths with SWARM satellite magnetic data. It includes recent data collected after the ADMAP 2.0 compilation, over the Ross Ice Shelf, the Amundsen Sea Embayment and the Recovery and South Pole regions, as well as enhanced maps for the Gamburtsev Subglacial Mountains and Wilkes and Dome C regions, based on relevelling.

We applied Curie Depth Point (CDP) estimation using the centroid, modified centroid and fractal and defractal approaches. We tested different window sizes at continental scale and for detailed analysis (200x200 km; 300x300 km; 400x400 km) and centroid distances, and both automated ranges and hand-picked intervals over selected features. The estimates reveal regions of enhanced GHF along the coast of the Amundsen Sea Embayment, in general agreement with independent seismological estimates, and are interpreted as reflecting dynamic interactions between the West Antarctic Rift System and anomalously warm Pacific upper mantle at depth. A higher degree of continuity of potential thermal anomalies related to the Byrd Subglacial Basin is evident between the Thwaites and Pine Island catchments compared to a recent magnetic estimate (Dziadek et al., 2021). A large area of enhanced GHF under the Siple Coast ice streams and active subglacial lake districts is confirmed, but has lower values and greater complexity than previously imaged (Martos et al., 2017). This can be correlated with regions of thinner and thicker crust and different magnetic patterns as revealed from inversion of satellite and airborne gravity and aeromagnetic data respectively.

In East Antarctica, the new CDP estimates suggest that any Mesozoic to Cenozoic extension is restricted to upper crustal levels and is focussed in narrow regions. Intriguing, relatively shallow CDP anomalies (given their location within the composite East Antarctic craton) are revealed in the Dome C lake district and also Gamburtsev Subglacial Mountains lake district regions. These may speculatively stem either from intraplate Mesozoic to Cenozoic fault reactivation and/or enhanced intracrustal heat production. 

We conclude that our new Curie depth estimates yield geologically reasonable thermal boundary conditions, which can be used together with independent estimates derived e.g. from seismology, machine leaning and multi-variate analysis to initialise new thermal models that incorporate crust and lithosphere thickness variations and intracrustal composition (as a proxy for ranges of radiogenic heat production and thermal conductivity).

How to cite: Ferraccioli, F., Ford, J., Dziadek, R., Mather, B., Armadillo, E., Ebbing, J., Eagles, G., Gohl, K., Forsberg, R., Green, C., Fullea, J., and Verdoya, M.: New Curie depth estimates from satellite conformed aeromagnetic anomaly compilations and their implications for assessing Antarctic subglacial geothermal heat flux heterogeneity , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14724, https://doi.org/10.5194/egusphere-egu23-14724, 2023.

EGU23-15151 | PICO | EMRP2.8

Depth estimation of gravity and magnetic sources from Wavelet transform spectral analysis 

Mahmoud Ahmed Abbas, Maurizio Milano, and Dora Francesca Barbolla

Spectral analysis, based on Fourier Transform, provides a high-resolution analysis in frequency domain but it has not resolution in the space domain. Due to this lack of space resolution, also celebrated methods such as the Spector and Grant’s one, cannot yield information about the position of the source identified in the frequency domain. We propose to fix these issues by resorting to a scalogram analysis, obtained through the continuous wavelet transform of the potential fields, using the Morlet analyzing wavelet. In the scalogram it is indeed possible distinguishing and locating the source contributes for both their space and scale contents. The depths to top and bottom of the potential fields causative sources are investigated locally along bounded subvolumes, subareas, and scale-profiles on the 3D scalogram. The application of such local spectral analysis to synthetic examples and real data leads to results in good agreement  with the known information about the causative sources, providing simultaneously good space and scale resolutions.

How to cite: Abbas, M. A., Milano, M., and Barbolla, D. F.: Depth estimation of gravity and magnetic sources from Wavelet transform spectral analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15151, https://doi.org/10.5194/egusphere-egu23-15151, 2023.

EGU23-15157 | PICO | EMRP2.8

An aero-towed vector magnetic system 

Roi Granot and Raz Edut

The three components of the crustal magnetic field provide essential constraints on the structure of the source layer as well as its age. In marine equatorial regions where the mid-ocean ridges are oriented north-south, the traditional total field anomalies are tiny, making them essentially undetectable. Still, the vector components of the equatorial magnetic field are detectable and can thus provide the only means of dating the oceanic crust there. However, collecting vector magnetic anomalies is difficult as it requires excellent knowledge of the three orientation angles. The existing vectorial systems are either installed on the carrying platform (airplanes or ships), thus suffer from significant magnetic contamination, or they are towed behind ships but suffer from poor constraints on the heading direction. Here we present the first aero-towed vector magnetic system (AeroVmag) that we have recently developed in order to reduce the magnetic contamination level to essentially null while maintaining excellent knowledge of the orientation angles. The system contains three independent sensors: a vector magnetometer, a scalar magnetometer, and a dual-GNSS/INS orientation sensor (accuracy of 0.02º). We tested the system by collecting data at a low altitude (100 m) above the northeast part of the Sea of Galilee, Israel. Data were collected at a high (200 Hz) sampling rate along a dense grid of profiles that allowed us to evaluate the error levels of our measurements. The scalar results compare favorably with an earlier sea surface total field survey. Together with the vector data, our observations also unravel the location of the main segment of the Dead Sea Transform fault that straddles the survey area. To conclude, this new system will allow the collection of cost-effective and accurate vector magnetic anomaly data. We expect this system to be most valuable over ice-covered, equatorial, and strongly magnetized regions.

How to cite: Granot, R. and Edut, R.: An aero-towed vector magnetic system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15157, https://doi.org/10.5194/egusphere-egu23-15157, 2023.

ERE4 – Raw materials

EGU23-71 | ECS | Orals | ERE4.3

Spectroscopic Studies and Confirmatory Geochemical Analyses of Rare Earth Element Bearing Rocks from the Neoproterozoic Siwana Ring Complex, Rajasthan, India 

Saraah Imran, Ajanta Goswami, Angana Saikia, Hrishikesh Kumar Rai, and Bijan Jyoti Barman

Abstract:

Rare earth elements (REEs) are of high economic value owing to their electronic, magnetic, optical, catalytic, and phosphorescent properties, thereby making them an important part of the development of green technology. They exhibit characteristic sharp absorption features in reflectance spectra in the visible-near infrared (VNIR) to short-wave infrared (SWIR) region due to their 4f-4f orbital intra-configurational electronic transitions.

In this study laboratory based close-range imaging spectroscopy techniques are used along with confirmatory geochemical analytical techniques (petrography, ICPMS, SEM and EPMA) to study 20 samples collected from REE-bearing rocks of the Neoproterozoic Siwana Ring Complex (SRC), a collapsed caldera structure situated in Barmer District, Rajasthan (India).

The SRC is an anorogenic, rift-related bimodal volcano-plutonic rock association belonging to the Malani Igneous Suite. It comprises of felsic and basic volcanic lava flows, rhyolite, peralkaline granite, pyroclastics, tuff and later microgranite, aplite and felsite dykes.

The spectral reflectance curves of the samples collected using an ASD FieldSpec4 (350-2500 nm) exhibit characteristic absorption dips at 439, 491, 580, 740 and 800 nm indicating the presence of Nd3+. Other major absorption dips are attributed to the presence of Sm3+, U4+, etc. Various combinations of absorption features in the VIS-SWIR region indicate the presence of minerals like biotite, epidote, chlorite, nontronite, goethite, and REE fluorocarbonates. The Fourier Transform Infrared (FTIR) spectra of the samples collected using a Thermo Fisher Scientific Nicolet 6700 (400-4000 cm-1) show symmetric and asymmetric bending and stretching vibration features of Si-O, P-O and O-H bonds, which are diagnostic of minerals like aegirine, riebeckite, and REE minerals like monazite apart from other major silicate minerals like quartz and feldspar. The presence of these minerals is confirmed by mineral chemistry, bulk and trace element data.

The observations from the spectroscopic studies seem to correlate well with data obtained from various geochemical analyses. This study provides spectroscopic information on the rocks from SRC for the first time. It shows the proficiency of spectroscopic studies as a cost-effective and non-destructive technique for the identification of REE minerals which can be used before detailed geochemical and mineralogical studies as well as future exploration.

Keywords: Siwana Ring Complex, Spectroscopy, REE

Abbreviations:

ASD – Analytical Spectral Devices, Inc.

EPMA – Electron Probe Micro Analyzer

FTIR – Fourier Transform Infrared

ICPMS – Inductively Coupled Plasma Mass Spectrometry

REE – Rare Earth Elements

SRC – Siwana Ring Complex

SWIR – Short Wave Infrared

VNIR – Visible Near Infrared

How to cite: Imran, S., Goswami, A., Saikia, A., Kumar Rai, H., and Jyoti Barman, B.: Spectroscopic Studies and Confirmatory Geochemical Analyses of Rare Earth Element Bearing Rocks from the Neoproterozoic Siwana Ring Complex, Rajasthan, India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-71, https://doi.org/10.5194/egusphere-egu23-71, 2023.

EGU23-1642 | ECS | Orals | ERE4.3

HyMap airborne imaging spectroscopy for mineral potential mapping of cupriferous mineralization in a semi-arid region based on pixel/sub-pixel hydrothermal alteration minerals mapping – A case study 

Soufiane Hajaj, Abderrazak El Harti, Amine Jellouli, Amin Beiranvand Pour, Saloua Mnissar Himyari, Abderrazak Hamzaoui, Mohamed Khalil Bensalah, Naima Benaouis, and Mazlan Hashim

Recently, hyperspectral datasets recognized a great interest in mineral exploration studies due to their high accuracy in detecting and mapping hydrothermal alteration minerals. Remote and mountainous regions are hardly accessible by geologists, while the spectral richness of imaging spectroscopy could provide detailed information about geology/mineralogy without having a direct contact with the ground surface. The Kerdous inlier in the Anti-Atlas belt of Morocco is recognized by several occurrences of Cu, Pb, Zn Au, Ag, and Mn mineral deposits. This study is carried out in Eastern Kerdous where the abandoned Idikel mine occurs in order to perform a high-resolution mineral potential map using Gamma-Fuzzy logic approach with twenty HyMap-derived layers. The HyMap-based thematic layers were generated using Directed Principal Component Analysis (DPCA), Relative Absorption Band Depth (RBD), and the Mixture Tuned Matched Filtering (MTMF) for pixel/sub-pixel mineral mapping. The hydrothermally altered regions within the study area reveal several Minerals/Mineral mixtures of hematite, illite, kaolinite, montmorillonite, muscovite, topaz, dolomite, and pyrophyllite. Then, the line density map extracted automatically from the HyMap data image was also integrated. The findings of the image processing were validated using field investigation, petrographic, and XRD analysis. This study demonstrates the great potential of the present research methodology and HyMap as a tool for mineral exploitation in similar areas in Morocco's western Anti-Atlas belt.

How to cite: Hajaj, S., El Harti, A., Jellouli, A., Beiranvand Pour, A., Mnissar Himyari, S., Hamzaoui, A., Khalil Bensalah, M., Benaouis, N., and Hashim, M.: HyMap airborne imaging spectroscopy for mineral potential mapping of cupriferous mineralization in a semi-arid region based on pixel/sub-pixel hydrothermal alteration minerals mapping – A case study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1642, https://doi.org/10.5194/egusphere-egu23-1642, 2023.

Underground mining is increasing in Korea, primarily due to the depletion of high quality mineral resources from surface open pit mining, and also due to the fact that environmental regulations are gradually tightened and strengthened. For sustainable mine design, safety and environmental issues are the most important factors forcing more specified and systematic guidelines to secure the stability of the mine openings and adits. However, with complex geological settings and various types of rock discontinuities, a geological mapping process to analyze the behavior of fractured rockmass is generally time-consuming. Information on the geologic structures are often collected by visual observation and analyzed based on two-dimensional drawings. Even worse, very limited and unrepresentative data are collected specially at operating mines leading to unreliable conclusions. Hence, construction of three-dimensional hydrogeological models adopting sophisticated surveying techniques has become a routine site investigation process. Laser scanners of high-end specifications are widely used in Korea. In this study, the Trimble X7 with automatic calibration and in-field registration capability has been used to collect accurate geospatial information at an underground limestone mine adopting the room-and-pillar method, with three drifts 9~12m wide and 6m high. For the two pillars of major stability concern, laser scanning was performed to obtain point-cloud data from which a total of 581 discontinuities were extracted. A discrete fracture network was simulated and the stability was evaluated based on the safety factor and displacement using a numerical model.

 

How to cite: Baek, H. and Kim, D.: Application of the 3-D laser scanning method for assessing the stability of fractured rockmass at an underground limestone mine in Korea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1750, https://doi.org/10.5194/egusphere-egu23-1750, 2023.

Rare earth elements (REE) have been a focus of global interest because of their irreplaceable role in developing “low carbon” technologies. The Bayan Obo is the world’s largest REE deposit, but its genesis is still highly debated. It is considered to have a close genetic association with carbonatite due to the presence of the carbonatite dykes around the orefield, as well as the geochemical similarities between these dykes and the orebody. However, the evolution of the carbonatite dykes and their REE mineralization are still poorly understood, hindering the interpretation of the genesis of the deposit. More than 100 carbonatite dykes have been found within the area of 0-3.5km nearby the orebodies of the deposit. These dykes show significant variations in mineralogy and geochemistry and were classified into dolomite (DC) and calcite carbonatite (CC). The rocks show an evolutionary sequence from DC to CC, and their corresponding REE contents increased remarkably, with the latter having very high REE content (REE2O3 up to 20 wt. %). The DC is composed of coarse-grained dolomite, magnetite, calcite, and apatite without apparent REE mineralization. The medium-grained calcites, and significant amounts of REE minerals, such as monazite, bastnäsite, and synchysite, make up CC. The REE minerals have a close relationship with barite, quartz, and aegirine. The REE patterns of dolomite and calcite in DC showed a steep negative slope with a strong LREE enrichment. In contrast, the calcite from CC has a near-flat REE pattern enriched in both LREE and HREE. Besides, apatite and magnetite in CC are characterized by strong REE enrichment compared to those from DC. Based on detailed petrology, mineralogy, and element geochemistry, we propose that strong fractional crystallization of initial carbonatitic melts led the REE enriched in the residual melt/fluid to form REE mineralization. In addition, sulfate, alkalis, and silica components play an important role in REE transportation and precipitation.

How to cite: Yang, J. and Song, W.: Mineralogy, major and trace element geochemistry of rock-forming and rare earth minerals in the Bayan Obo (China) carbonatite dykes: implications for REE mineralization, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2318, https://doi.org/10.5194/egusphere-egu23-2318, 2023.

EGU23-3180 | ECS | Posters on site | ERE4.3

Radiogenic and stable Sr isotope geochemistry of regolith hosted REE deposits: a preliminary report 

Hamed Pourkhorsandi, Vinciane Debaille, Sophie Decrée, Jeroen de Jong, Ali Yaraghi, Georges Ndzana, Martin Smith, Kathryn Goodenough, and Jindřich Kynický

The increasing global demand for the rare earth elements (REE), that are critical for green energy production, justifies the necessity of understanding REE ore formation processes [1]. The main type of REE mineralization is mostly found in association with carbonatites and alkaline rocks [1,2]. In addition, in some cases the REE can also reach economical levels in secondary products called supergene REE resources [3]. Primary ore mineralizations mostly are composed of mineral phases that are highly unstable and easily soluble in the near-surface conditions in time. The secondary concentration of the REE in weathering regolith into economic deposits is more favourable than those in primary igneous rocks. As the main source of global heavy-REE, weathering deposits in southern China are the most studied ores of this type [4]. Recently, because of the recent surge in REE deposit exploration and their geological importance, other potentially similar deposits are being studied worldwide. Most of these works focus on mineralogical and elemental aspects of these systems. However, those weathering (in cooperation with alteration) systems are complex and a lot of questions on their formation remain unanswered.

In this work, we focus on the isotopic characterization of regolith hosted REE deposits. To better understand their formation, we utilize stable 88Sr/86Sr and radiogenic 87Sr/86Sr ratios, which have been used widely in understanding chemical weathering [5]. Mainly controlled by the incongruent weathering of primary minerals, Sr isotopes can help to identify the sources involved and the main factors affecting regolith hosted REE deposit formation. Strontium is especially important because, as Ca and K, it occurs in different REE-bearing primary and secondary minerals such as carbonates, ancylite, apatite, clays etc.

We will present different regolith profiles’ Sr isotopic data from Asia and Africa. Combining with the elemental and mineralogical data, we will devise a formation model for regolith hosted REE deposits.

References: [1] Goodenough et al. (2016) Ore Geo. Rev., 72, 838. [2] Chakhmouradian & Zaitsev (2012) Elements 8, 347. [3] Estrade et al. (2019) Ore Geo. Rev., 112, 103027. [4] Li et al. (2019) Econ. Geol., 114, 541. [5] Pett-Ridge et al. (2009) GCA, 73, 25.

 

How to cite: Pourkhorsandi, H., Debaille, V., Decrée, S., de Jong, J., Yaraghi, A., Ndzana, G., Smith, M., Goodenough, K., and Kynický, J.: Radiogenic and stable Sr isotope geochemistry of regolith hosted REE deposits: a preliminary report, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3180, https://doi.org/10.5194/egusphere-egu23-3180, 2023.

EGU23-4661 | Posters on site | ERE4.3

Gamma radiation for rare earth elements (REEs) in deep-sea sediments 

Changyoon Lee, Yuri Kim, Yoon-Mi Kim, Sung Kyung Hong, and Seok-Hwi Hong

Gamma ray is routinely used for correlation, evaluation or classification of minerals and rocks on continent and ocean. Using natural gamma radiation (NGR) derived from Integrated Ocean Drilling Program (IODP) and Ocean Drilling Program (ODP), this study focuses on the correlation between lithology and REE (Rare Earth Element)-bearing sediments in two deep-sea areas, IODP Expedition 329 in the Southwest Pacific and ODP Leg 199 Sites in the Northeast Pacific basins, where values of the REEs are abundant. Deep-sea sediments are consisting mainly of clays, calcareous oozes and siliceous oozes. As a result of the correlation, the REEs prefer to the clays rather than oozes and high values of the REEs correspond with intervals of the clays where the upper sediments (0–70 mbsf) are. The clays show relatively high values of the gamma radiation and the differences between significant elements (Th, U and K) for gamma radiation, derived from geochemical analysis at every site, show two trends reflecting characteristics of regions. Therefore we suggest that the gamma radiation is fully useful for detecting REEs in the deep-sea sediments and plays a role as a predictable tool for finding quantitative REEs. 

How to cite: Lee, C., Kim, Y., Kim, Y.-M., Hong, S. K., and Hong, S.-H.: Gamma radiation for rare earth elements (REEs) in deep-sea sediments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4661, https://doi.org/10.5194/egusphere-egu23-4661, 2023.

Carbonatites are known to host over 95% of light rare earth element (REE) resource, and the REEs are commonly hosted in minerals with well-established extraction methods. Most REE mineralized carbonatites are associated with hydrothermal alteration/recrystallization. Identifying the source composition and role of recrystallization is crucial for understanding the formation of the giant carbonatite-associated REE deposit. Here we report the first in-situ carbon and magnesium isotopic compositions for the hosting dolomite in the Bayan Obo deposit.

In-situ carbon isotope analyses of dolomite from the coarse-grained (CM), fine-grained (FM) and heterogeneous-grained (HM) samples show a wide range of δ13C values (-5.19‰ to 2.08‰), which is distinct from the common mantle-derived carbonatite and slightly overlaps the range of sedimentary carbonate. CM dolomite displays almost homogeneous carbon isotope compositions (δ13C=-1.29‰ to 0.16‰) with the average δ13C of -0.82‰. Recrystallized dolomites from both FM and HM samples vary greatly, and FM dolomite generally displays a heavier δ13C range (-3.94‰ to 2.08‰) compared to that for HM dolomite (-5.19‰ to 0.64‰). CM dolomite also shows relative consistent Mg isotope compositions in the range of -0.27‰ to 0.05‰ with an average of -0.10‰, which is similar to the mantle value. δ26Mg values of FM and HM dolomites vary greatly from -1.18‰ to 0.06% with averages of -0.40‰ and -0.32‰, which are lighter compared to that of CM dolomite. The recrystallized dolomites (FM and HM) are characterized by depleted light REE (LREE) and increased Pb/CeN features compared to the pristine dolomite (CM). Moreover, the LREE depletion and Pb/CeN increase correlate with the lighter Mg isotope compositions. The highly variable C isotopes recorded by FM and HM dolomites (lighter or heavier compared to the pristine dolomite) involve both recrystallization and degassing. The combined in-situ Mg and C isotope compositions of the pristine dolomite suggest the Bayan Obo carbonatite sourced from the mantle previously fertilized by fluids derived from the carbonate-bearing subduction slab.

How to cite: Chen, W., Yang, F., and Lu, J.: In-situ C and Mg isotopes of dolomite from the giant Bayan Obo REE deposit: Implications for recrystallization and recycled carbonate in the source, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4823, https://doi.org/10.5194/egusphere-egu23-4823, 2023.

As the world's largest rare earth elements (REEs) deposit, the giant Bayan Obo deposit accounts for more than one third of the world's REEs resources. Fenitization is an alkali metasomatism that widely occurs around the carbonatite dykes at Bayan Obo and recent studies reveal huge quantities of REEs could be transferred from the alkaline magma to fenite (Sokół et al., 2022). However, the contribution of fenitization to REE mineralization at Bayan Obo remains unclear. Here, we present bulk rock chemical compositions, in-situ chemical and C-Sr isotopic investigations of calcite and apatite together with Th-Pb ages of monazite, aiming to provide new constraints on REE mineralization during fenitization.

Carbonatite at Wu dyke is mainly composed of calcite, aegirine and barite associated with REE minerals dominated by bastnasite and parisite, which intruded into the surrounding wall rocks of quartz conglomerate. The associated fenites include the close Na-fenite and faraway K-fenite. Na-fenite contains calcite, riebeckite, aegirine and apatite with minor monazite and bastnasite in association with barite. K-fenite consists of K-feldspar and quartz with accessory riebeckite and albite. Both REE and SO3 contents decrease from the center to the wall rocks. REE are most enriched in the centered carbonatites (up to 7.39 wt%), and Na-fenites also display strong REE enrichment (9876-22492 ppm). Of note, high-grade Na-fenite is characterized by the highest LREE concentrations among fenites, whereas HREE is most enriched in medium-grade Na-fenite. The latter is dominantly controlled by apatite, which hosts abundant HREE (118-677 ppm). Calcite from fenites displays flat REE patterns with more depleted LREE (La/YbN=0.28-3.02) compared to that within carbonatite (La/YbN=1.66-6.52). Th-Pb ages of monazite from fenites cover a wide range from 420 Ma to 1.27 Ga, which suggests these fenites have also undergone the early Paleozoic hydrothermal alteration. In-situ Sr and C isotope analyses of calcite from carbonatite define a limited range (87Sr/86Sr=0.70344 to 0.70358 and δ13C=-4.36 to -5.1 ‰), which are consistent with a mantle origin . 87Sr/86Sr and δ13C values for calcite within Na-fenite show larger variations of 0.70358 to 0.70620 and -4.92 to -9.87 ‰, respectively. Negative shift in δ13C values suggest degassing through the fenitizing reaction of 18CO32-+2Na++3(Mg2+,Fe2+)+2Fe2++8SiO2+24H++0.5O2= Na2(Mg,Fe2+)3Fe3+2Si8O22(OH)2+18CO2+11H2O. More radiogenic Sr isotopic compositions of fenites result from both assimilation of wall rocks during fenitization and the redistribution of Sr isotopes among minerals during the Paleozoic hydrothermal alteration.

Carbonatite-exsolved fenitizing fluids result in predominant REE enrichment within Na-fenite accompanying with light and heavy REE mineralization. LREE mineralization is dominated by monazite precipitation, and HREE enrichment is mostly controlled by apatite. Sulfate is an important ligand for REE transportation and mineralization during fenitization. Barite crystallization and simultaneous precipitation of LREE-bearing minerals lead to fenitizing fluids abundant in HREE, promoting the further formation of HREE-rich apatite.

Reference:

Sokół K., Finch A.A., Hutchison W., et al., 2022. Quantifying metasomatic high-feld-strength and rare-earth element transport from alkaline magmas. Geology, https://doi.org/10.1130/G49471.1.

 

 

How to cite: Yang, F. and Chen, W.: Fenitization associated with the Wu carbonatite dyke at Bayan Obo (Inner Mongolia, China): Implications for REE mineralization, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5183, https://doi.org/10.5194/egusphere-egu23-5183, 2023.

EGU23-8008 | Posters on site | ERE4.3

The metasomatism affecting karstic bauxites from the south-central Pyrenees, Catalonia (NE Spain) and its implications on the REE geochemistry in similar geological settings. 

Josep Roqué-Rosell, Pablo Granado, Juan Diego Martín-Martín, Jordi Ibáñez-Insa,, Ivanna Pérez Bustos, Roger Roca-Miró, and Abigail Jiménez Franco

Karstic bauxite deposits are the main resource of aluminum in Europe and are formed through a combination of weathering, leaching, and deposition processes known as bauxitization. Bauxites have recently been proposed as unconventional resources of rare-earth elements (REE) as well. The studied karstic bauxite deposits are located on the salt-detached Serres Marginals thrust sheet, at the external most unit of the south-central Pyrenees (Catalonia, NE Spain). The Pyrenean bauxites are found overlaying and filling karstic surfaces forming aligned pockets up to several meters thick. These deposits have been mined for more than 20 years and present high variability in SiO2, Al2O3 and Fe2O3 contents. Here, we characterize these deposits for the first time by a combination of field geology, XRD, FTIR and XRF to determine their formation, mineralogy, and geochemistry and to understand the causes affecting their compositional variations. Field data indicate that the bauxite deposits fill a paleokarst system affecting Dogger dolostones and/or Tithonian-Berriasian limestones. XRD data indicate that the studied karstic bauxites are mainly composed of Al-rich minerals kaolinite and boehmite, in addition to the Fe-oxide hematite, and lesser amounts of the Ti-oxides rutile and anatase. The detailed study of the FTIR spectra also confirmed the presence of diaspore and dickite. XRF data confirm the presence of varying amounts of Al, Fe and Si in addition to varying low contents of REE. These results suggest that boehmite was formed first during bauxitization and later transformed to diaspore, kaolinite and finally to dickite upon metasomatism. The presence of dickite in faults and fractures provides a direct proof for such fluid circulation. Our results suggest that the mechanisms responsible of the compositional variations in karstic bauxites are rather complex and fall beyond the standard bauxitization processes. The observed metasomatism should be further assessed, since the inferred fluid-rock interactions are susceptible to affect and mobilize REE not only in the south-central Pyrenees karstic bauxites but elsewhere in similar geological settings.

How to cite: Roqué-Rosell, J., Granado, P., Martín-Martín, J. D., Ibáñez-Insa,, J., Pérez Bustos, I., Roca-Miró, R., and Jiménez Franco, A.: The metasomatism affecting karstic bauxites from the south-central Pyrenees, Catalonia (NE Spain) and its implications on the REE geochemistry in similar geological settings., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8008, https://doi.org/10.5194/egusphere-egu23-8008, 2023.

EGU23-9090 | Orals | ERE4.3

Blast Hole Rock Cuttings analysis: Design and Implementation of an open Architecture LIBS System 

Ad Maas, Jorgina Akushika, and Federico Arboleda

This paper presents the development and implementation of a LIBS (Laser-Induced Breakdown Spectroscopy) system based on a robotic arm for fast chemical characterization of blast hole rock cuttings in open pit mining. The system is designed with an open architecture, allowing for the easy integration of additional sensors such as a spectrophotometer and a magnetic susceptibility meter. The use of the LIBS system significantly reduces the time required to characterize the raw material and obtain a broader characterization, including geological characterization. The preliminary results of this development demonstrate the potential of the LIBS system in improving the efficiency and accuracy of rock characterization in open pit mining operations.

How to cite: Maas, A., Akushika, J., and Arboleda, F.: Blast Hole Rock Cuttings analysis: Design and Implementation of an open Architecture LIBS System, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9090, https://doi.org/10.5194/egusphere-egu23-9090, 2023.

Recently, due to the active spread of electric vehicles, the demand for batteries is increasing fast, and for this reason, the exploration for lithium that is an essential mineral for battery production, is increasing. In Korea, lithium exploration is also being conducted around deposits where lithium was identified in the past. However, most lithium mines are located in very rough terrain, so it is not easy to conduct a surface geological and geophysical exploration. Without considering complex topography, errors may occur in the inversion of surface geophysical exploration data, and in particular, it is necessary to use precise topographic information for the three-dimensional inversion. In this study, we would like to introduce a case study using high-resolution topographic data obtained from a drone-mounted LIDAR in the three-dimensional inversion of surface resistivity and IP data conducted for lithium exploration. The target area is the Boam Mine, located in the Middle East of Korea. Surface geophysical exploration was conducted along a road and ridge of the mountain, which are relatively easy to set up the survey line. Because existing topographic maps that are publically available did not include mining traces related to mining development and topographical changes formed by nearby roads, it is not adequate for the 3D inversion of surface resistivity and IP data. To acquire precise topographical information, aerial photography and LIDAR measurements using drones were performed. A numerical topographic model was constructed using the obtained high-precision DEM (digital elevation map). By applying this to the three-dimensional inversion, the distribution of the underground mineralization zone was estimated. The interpreted results were compared with the existing drilling results performed near the mine. Comparing the two results, drilling surveys using only surface geological information proceeded in the direction in which the mineralization zone did not develop. Drone LIDAR measurement is a costly exploration method and is difficult to use actively at all exploration sites. However, if three-dimensional inversion is required where the surface topography is very complex, as in this survey area, it could give more reliable inversion results.

How to cite: Son, J., Kim, C., and Bang, E.: Three-dimensional interpretation of DC resistivity/IP survey for Lithium exploration using high-precision topographic information from drone-mounted LIDAR., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10680, https://doi.org/10.5194/egusphere-egu23-10680, 2023.

EGU23-10689 | Posters on site | ERE4.3

Investigations of Vanadiferous Titanomagnetite Deposit using Drone Magnetic and Electrical Resistivity Surveys in Korea 

Changryol Kim, Jeongsul Son, Eunseok Bang, Gyesoon Park, and Bona Kim

Recently, the demands for energy storage minerals such as vanadium and lithium are increasing as the use of the batteries for electrical vehicles has increased. Vanadium is one of the energy storage minerals occurred in Korea. In this study, vanadium mineralized zones of the ore deposit, named as Gwanin deposit, was investigated using geophysical exploration techniques. The mineralized zone is known as vanadiferous titanomagnetite (VTM) deposit, originated from pre-cambrian igneous intrusions (850-870 m.a.), located in the northwest region of Korea. Since the vanadium has occurred along with magnetite (low electrical resistivity and high magnetic susceptibility) in the study area, geophysical exploration techniques such as magnetic and electrical resistivity surveys were employed. For magnetic exploration, the drone magnetic survey technique was used since it provides more precise and higher resolution data than any other aerial magnetic exploration techniques for relatively small and mountainous areas. In addition, electrical resistivity data were obtained from the six survey lines in the study area. 3D inversion was performed with magnetic and resistivity data. The anomaly zones of low electrical resistivities and high magnetic susceptibilities were interpreted as VTM mineralized zones from the two different inversion results. The mineralized zones were identified from the drilling investigation for overlapping locations of the anomaly zones. The results of the study have shown that magnetic and electrical resistivity techniques are very effective tools for exploring ore deposits of vanadium resource accompanied with magnetite. In the future, drone magnetic exploration technique combined with other (surface) geophysical exploration techniques would provide more effective results of precise geophysical surveys for relatively small and mountainous areas with similar ore deposit environments.

How to cite: Kim, C., Son, J., Bang, E., Park, G., and Kim, B.: Investigations of Vanadiferous Titanomagnetite Deposit using Drone Magnetic and Electrical Resistivity Surveys in Korea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10689, https://doi.org/10.5194/egusphere-egu23-10689, 2023.

Apatite with high REE content is common in alkaline rocks, carbonatites and products of hydrothermal processes. The REE concentrations could enter mineral structure by different substitution mechanisms (Fleet et al., 2000) and the factors controlling the composition of high-REE apatite are not completely understood. New experimental data (Stepanov et al., 2023) show that at 800 °C and 10 kbar apatite crystalizing from felsic melt with addition of NaCl contains 14 wt.% ΣREEOx and coexists with britholite (37.2 wt.% ΣREEOx). The results suggest that equilibrium has been established during the run and both apatite and britholite contained REE in [Si4+REE3+] to [Ca2+P5+] solid solution, whereas the coupled substitution [Na1+REE3+] to [2Ca2+] was insignificant despite crystallisation from an alkaline, Na-rich melt. Coupling of the new experimental data allowed to constrain the width of the miscibility gap between apatite and britholite, and suggest complete miscibility between apatite and britholite above 950 °C. The substitution [Na1+REE3+] apparently develops mainly in apatite replacement reactions. Therefore, REE content and substitution mechanisms could be useful tools for interpretation of magmatic and metasomatic/hydrothermal associations in alkaline volcanic and plutonic rocks.
References 
Fleet, M., Liu, X., Pan, Y., 2000. Rare-earth elements in chlorapatite [Ca-10(PO4)(6)Cl-2]: Uptake, site preference, and degradation of monoclinic structure. American Mineralogist 85, 1437–1446.
Stepanov, A.S., Zhukova, I.A., Jiang, S.-Y., 2023. Experimental constraints on miscibility gap and partitioning between britholite and chlorapatite in alkaline melt. American Mineralogist.

How to cite: Zhukova, I. and Stepanov, A.: Experimental data on REE in apatite in high-REE environments: distinguishing magmatic and metasomatic compositions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11255, https://doi.org/10.5194/egusphere-egu23-11255, 2023.

EGU23-11997 | Orals | ERE4.3

Hyperspectral mineral mapping for underground mining 

Moritz Kirsch, Mary Mavroudi, Sam Thiele, Sandra Lorenz, Laura Tusa, René Booysen, Erik Herrmann, Ayoub Fatihi, Robert Möckel, Thomas Dittrich, and Richard Gloaguen

Future mining will increasingly require rapid and informed decisions to optimise ore extraction and valuation. In this context, the use of hyperspectral imaging has been proven to be effective for geological mapping in surface mining operations. The potential of hyperspectral methods in underground mining environments, however, remains underexplored due to challenges associated with illumination and surface water. Our contribution addresses this gap by evaluating different lighting setups and the effect of moisture on the spectral quality of hyperspectral data in a laboratory setup. We also compared three commercially available, visible-near infrared to shortwave infrared sensors to assess their suitability for underground hyperspectral scanning. As a demonstration, we acquired hyperspectral data from three adjacent outcrops in the visitor’s mine of Zinnwald, Germany, where rocks of a Late Variscan Sn-W-Li greisen-type deposit are exposed in representative underground mining conditions. A photogrammetric 3D digital outcrop model was used to correct for illumination effects in the data. We then estimated mineral abundance and lithium content across the mine face employing an adapted workflow that combines quantitative XRD measurements with hyperspectral unmixing techniques. Laser-induced breakdown spectroscopy was used to validate the results. While there are still challenges to overcome, this study proves that hyperspectral imaging techniques can be applied underground to yield rapid and accurate geological information. This application will pave the way for the safe, digital and automated underground mine of the future.

How to cite: Kirsch, M., Mavroudi, M., Thiele, S., Lorenz, S., Tusa, L., Booysen, R., Herrmann, E., Fatihi, A., Möckel, R., Dittrich, T., and Gloaguen, R.: Hyperspectral mineral mapping for underground mining, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11997, https://doi.org/10.5194/egusphere-egu23-11997, 2023.

EGU23-12056 | ECS | Posters on site | ERE4.3

ROBOMINERS resilient reflectance/fluorescence spectrometers 

Christian Burlet, Giorgia Stasi, Simon Godon, Roza Gkliva, Laura Piho, and Asko Ristolainen

ROBOMINERS (Bio-Inspired, Modular and Reconfigurable Robot Miners, Grant Agreement No. 820971, http://www.robominers.eu) is a European project funded by the European Commission's Horizon 2020 Framework Programme. The project aims to test and demonstrate new mining and sensing technologies on a small robot-miner prototype (~1-2T) designed to target unconventional and uneconomical mineral deposits (technology readiness level 4 to 5) (Lopez and al. 2020).

As part of the ROBOMINERS sensor array development, a set of mineralogical and geophysical sensors are designed to provide the necessary data to achieve a “selective mining” ability of the miner to reduce mining waste production and increase productivity of a small mining machine. To achieve this, the robot should have the ability to react and adapt in real time to geological changes as it progresses through a mineralized body. This study focuses on a set of compact sensors designed for ultrahigh-resilience and continuous operation in high pressure/vibrations/temperature environment. They are based on reflectance/fluorescence measurements in the visible/near infrared range, using a broadband light source (tungsten-halogen lamps) in reflectance mode and 365nm UV LED in fluorescence mode. 

The ROBOMINERS reflectance/fluorescence spectrometer “Mk1” was developed in collaboration with Taltech University. The spectrometer is built around a monolithic spectrometer (Hamamatsu C12800MA and a wifi capable microcontroller (Arduino RP2040 Connect).. As the ROBOMINERS prototype will be operated by ROS2 (Robotic Operating System v2 - https://www.ros.org/ ), we decided to implement a Micro-ROS publisher on the microcontroller.

The first field trials of the sensor have been carried out in the entrance of abandoned mine (baryte and lead mine, Ave-et-Auffe, Belgium), with the sensor integrated directly in the propulsion mechanism of the “RM3”’ ROBOMINERS prototype. This test allowed to demonstrate the immunity of the sensors to  to shocks, water and dust with no measurable de-calibration of the spectrometer.

References.

Lopes, B. Bodo, C. Rossi, S. Henley, G. Žibret, A. Kot-Niewiadomska, V. Correia, Advances in Geosciences, Volume 54, 2020, 99–108

 

 

How to cite: Burlet, C., Stasi, G., Godon, S., Gkliva, R., Piho, L., and Ristolainen, A.: ROBOMINERS resilient reflectance/fluorescence spectrometers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12056, https://doi.org/10.5194/egusphere-egu23-12056, 2023.

EGU23-13081 | Posters on site | ERE4.3

The surface chemistry of carbonatite soils: Implications for REE resources. 

Martin Smith, Charles Beard, Isaac Watkins, Sam Broom-Fendley, Frances Wall, Xu Cheng, Yan Liu, Wei Chen, and Jindrich Kynicky

The rare earth elements (REE), and in particular neodymium and dysprosium, are essential for the development of renewable energy. At present the REE are sourced from either low concentration weathered granitoid (ion adsorption clay) deposits in southern China, or from high concentration carbonatite-related deposits [1], especially the World’s dominant REE mine at Bayan Obo, China, but also including the Mt Weld weathered carbonatite, Australia. Weathered carbonatites (e.g. Tomtor, Russia; Mount Weld, Australia) are some of the world’s highest grade REE deposits. As part of the NERC Global Partnerships Seedcorn fund project WREED, we have carried out preliminary investigations in weathering products from carbonatite hosted REE deposits. Three end member deposit styles can be identified – in situ residual deposits, where carbonate dissolution has generated primary REE mineral enrichment on palaeosurfaces or in karst; supergene enrichment from dissolution and reprecipitation of REE phosphates and fluorcarbonates forming hydrated phosphates or authigenic carbonate minerals; clay and oxide caps (either from in situ weathering or from soil transport from surrounding rocks) that may hold the REE adsorbed to mineral surfaces (c.f. the ion adsorption deposits). High grade weathered carbonatite deposits typically consist of supergene horizons, that may be phosphate-rich due to dissolution and re-precipitation of apatite and monazite during the weathering process (Mount Weld [2][3]), overlain by later sediments that may be REE enriched by accumulation of residual minerals (e.g. Tomtor [4]). The mineralogy of the ore zone is linked to, but distinct from, the unweathered carbonatite rock, and includes phosphates, crandallite-group minerals, carbonates and fluorcarbonates and oxides. We have carried out leaching studies, SEM examination and XPS characterisation of soil and weathered rock samples from a range of deposits. Residual and supergene processes can result in enrichments up to 100x times bedrock concentrations, with residual enrichments in particular hosted in monazite and bastnäsite. Supergene enrichment results in more complex mineralogy which may present processing challenges. Clay-rich soils have much lower REE concentrations. However, sequential leaching studies demonstrate that a significant proportion of REE are present at trace levels in the oxide fraction in residual and supergene deposits. In clay caps the easily leachable fraction of REE matches that of ion adsorption deposits and may represent a potentially easily extractable resource.

 

References

[1] Wall and Chakhmouradian, 2012, Elements 8, 333-340;

[2] Duncan and Willett, 1990, Geology of Mineral Deposits of Australia pp. 591-597;

[3] Lottermoser, 1990, Lithos 24, 151-167;

[4] Kravchenko and Pokrovsky, 1995, Econ. Geol. 90, 676-689;

How to cite: Smith, M., Beard, C., Watkins, I., Broom-Fendley, S., Wall, F., Cheng, X., Liu, Y., Chen, W., and Kynicky, J.: The surface chemistry of carbonatite soils: Implications for REE resources., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13081, https://doi.org/10.5194/egusphere-egu23-13081, 2023.

EGU23-13899 | ECS | Posters on site | ERE4.3

Robot-aided autonomous hyperspectral mapping in mining environments 

Sandra Lorenz, Moritz Kirsch, Margret Fuchs, Sam Thiele, and Richard Gloaguen

Geological face mapping is a frequently recurring task in mining operations, the results of which have an immediate influence on the mines’ profitability, safety, and environmental impact. Hyperspectral imaging is an increasingly applied technology to improve the efficiency and accuracy of mapping tasks. The rapid and non-destructive acquisition of spectral material properties allows meaningful material information such as mineralogical surface composition to be obtained in a safe and efficient manner. The fusion product of backprojected hyperspectral data with 3D surface information (so-called “hyperclouds”) further enhances the data value by enabling easier data correction, integration, and implementation into digital archives and models. Mining environments, however, remain a challenge for operational hyperspectral mapping, particularly underground where inadequate lighting, access, and safety of operation make data collection difficult. Data processing and interpretation require expert knowledge and are typically performed semi-manually and offline. To be economically viable in such mining environments, the hypercloud technology has to mature toward autonomy and real-time delivery of results. In recent years, terrestrial autonomous platforms have entered the market that are suited to the challenging conditions of underground mining and can maneuver and navigate even in confined, uneven, and poorly lit environments. They provide optimal carriers for hyperspectral sensors, which have simultaneously evolved into lighter, faster, and more robust devices. However, implementing hyperspectral sensors as payload for terrestrial autonomous robots remains challenging, especially in terms of  technical compatibility, ensuring data quality under complex conditions,  and processing large amounts of data quickly and autonomously. In our contribution, we demonstrate the potential of autonomous terrestrial robots combined with hyperspectral technology and advanced data processing for the automation of geological mapping. We present results of hyperspectral data acquisition using an autonomous robotic platform in a confined underground mining environment and discuss strategies for adapted sensor design, autonomous validation, real-time hypercloud processing, and enhanced autonomous navigation supported by hyperspectral information. 

How to cite: Lorenz, S., Kirsch, M., Fuchs, M., Thiele, S., and Gloaguen, R.: Robot-aided autonomous hyperspectral mapping in mining environments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13899, https://doi.org/10.5194/egusphere-egu23-13899, 2023.

EGU23-15053 | Orals | ERE4.3

TIMREX – a European joint master programme to implement innovative mineral exploration achievements in geoscience education 

Ferenc Madai, Sibila Borojević Šoštarić, Gabriela Paszkowska, and Nils Jansson

Mineral resource exploration techniques and methodologies have undergone a very strong development in the last decade: e.g. portable and higher sensitive equipment, robotized exploration equipment, and tools for processing and interpreting of large, multidimensional datasets. In order to meeti the raw materials policy goals of the EU, these technologies should also be incorporated in higher education (Mádai, 2022).

 

TIMREX is a new EIT-Labelled joint master's program to train geoscience students focusing on innovative raw materials prospecting and exploration methods. The consortium consists of four academic partners – University of Miskolc, Hungary, University of Zagreb, Croatia, Wroclaw University of Science and Technology, Poland and Luleå University of Technology, Sweden. All four academic partners run their mineral exploration-focussed, geoscience engineering-type master programmes which comprise the ground for the joint master programme. Participating Universities are located within Fennoscandian, Fore-Sudetic and Tethyan/Carpathian-Balkan metallogenic belts hosting numerous primary, secondary and critical mineral resources essential for green transition of Europe. Scandinavian and West Balkan countries holds first and second place according to total mineral resources investments in Europe (data from 2019).

 

The TIMREX consortium incorporates eight non-academic partners who are at the frontier of mineral resource prospecting and exploration equipment and methodology development in the EU. They represent leading European mining companies such as Boliden Mineral and KGHM, but also SMEs and start-ups such as the Unexmin Georobotics (UGR) and the Geogold Kárpátia Ltd., as well as research institutes such as the Portuguese INESC TEC and the Slovenian Geological Survey (GeoZS).

Non-academic partners are actively involved in the TIMREX joint programme as trainers in field programs, internship mentors or thesis topic providers. Students of the programme can join research and development work at the partners. Examples are development of underwater robotized exploration methodologies (INESC TEC, UGR), drone-based multispectral surveys and complex dataset evaluation (Boliden, KGHM Cuprum, GeoZS, Geogold). The European Federation of Geologists provides a wider network of European prospectors and explorers to the joint programme and contributes to teaching of entrepreneurial skills. Therefore, TIMREX directly address major gaps of the Raw Materials sector: limited availability of qualified technical, scientific and managerial personnel involved in the whole mineral cycle (Borojević Šoštarić et al., 2022) as well as lack of generic skills crucial for increasing the innovation capacity of universities and their graduates (Grgasović and Borojević Šoštarić, 2021).

 

 

Borojević Šoštarić, S., Giannakopoulou, S., Adam, K. i Mileusnić, M. (2022). The future of mining in the Adria region: current status, SWOT and Gap analysis of the mineral sector. Geologia Croatica, 75 (Special issue), 317-334. https://doi.org/10.4154/gc.2022.26

Grgasović, P.; Šoštarić, S.B. (2021) Systematic Development of Generic Skills to Enhance Innovation Capacity of Eastern and Southeastern European Universities. Mater. Proc.

5, 99, 1-7. https://doi.org/10.3390/ materproc2021005099

Mádai F. (2022) Competence requirements of innovation and entrepreneurship oriented training programmes for the mineral exploration sector. In: Veresné Somosi M.; Lipták K.; Harangozó  Zs.(eds) "Mérleg és Kihívások - Fenntarthatóság" Miskolci Egyetem Gazdaságtudományi Kar (2022) pp. 537-547

How to cite: Madai, F., Borojević Šoštarić, S., Paszkowska, G., and Jansson, N.: TIMREX – a European joint master programme to implement innovative mineral exploration achievements in geoscience education, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15053, https://doi.org/10.5194/egusphere-egu23-15053, 2023.

EGU23-15445 | ECS | Posters virtual | ERE4.3

Re-evaluating Caledonian magmatism and associated base metal mineralisation: a case study of the Black Stockarton Moor porphyry copper system 

Chloe Gemmell, David Currie, Iain Neill, Josh Einsle, and Careen MacRae

Following the British Geological Survey’s (BGS) 1970s – 1990s Mineral Reconnaissance Programme (MRP), there has been limited characterisation and quantification of base and precious metal mineralisation in the UK, with the notable exception of Au. Data gaps still exist regarding mineral paragenesis, geochronology, deportment of critical raw materials (CRM), and ore forming processes. With increased focus on CRM, NetZero, and supply risk we must improve our knowledge of deportment in base metal systems. The BGS Critical Minerals Intelligence Centre (CMIC) was recently established to aid the UK in meeting projected future CRM demand and will act as a nexus for industry and academia. Here, we establish a workflow and document a case study where academia and the CMIC have partnered to re-evaluate a potential mineral resource, a starting point for renewed studies elsewhere in the UK. 

The Black Stockarton Moor (BSM) post-subduction porphyry Cu system is thought to have formed by interaction of Devonian plutonic to sub-volcanic complexes with Silurian turbidites in the Southern Uplands of Scotland. No study of the BSM has been undertaken since the 1979 MRP report, thus whether it is of any modern value remains unproven. Field sampling and utilising the National Geological Repository at BGS will allow for optical and scanning electron microscopy (SEM) to quantitatively establish paragenesis and primary mineralogy. Sites will then be identified for chemical mapping to quantify CRM deportment in base metals using SEM-energy dispersive X-ray analysis (EDX), with areas of particular interest further quantified by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Focused ion beam (FIB) nano-tomography will be used to identify the cm to nano-scale distribution of CRM. Finally, magmatism and mineralisation will be fully temporally constrained using U-Pb analysis of zircon, titanite, calcite and epidote and/or Re-Os analysis of sulphides as appropriate. On a large scale, this study will address one set of data gaps by re-invigorating our knowledge of the geology and geodynamic associations of mineralisation. However, by also identifying the quantities and associations of metals at the cm to micron scale, it addresses another, by constraining the extent and nature of processes responsible for the distribution of metals in such deposits. This workflow is to be refined for application to mineralisation elsewhere in the UK including work underway on the Strontian Caledonian granite and associated Pb-Zn mineralisation in the Northern Scottish Highlands.

How to cite: Gemmell, C., Currie, D., Neill, I., Einsle, J., and MacRae, C.: Re-evaluating Caledonian magmatism and associated base metal mineralisation: a case study of the Black Stockarton Moor porphyry copper system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15445, https://doi.org/10.5194/egusphere-egu23-15445, 2023.

EGU23-16567 | ECS | Posters on site | ERE4.3

Deep Electrical Resistivity Tomography as a mineral exploration tool: the Calamita distal Fe-skarn, Elba Island (Italy) 

Damian Braize, Julien Sfalcin, Matteo Lupi, Kalin Kouzmanov, Andrea Dini, and Gianfranco Morelli

To face the growing demand for raw materials, the discovery of new mineral deposits is essential for the future. Geophysical methods, and in particular electrical and electromagnetic tools, have an important role in mineral exploration. Recently, new technological developments made possible targetting deeper ore bodies and large areas with logistical challenges. We use the Deep Electrical Resistivity Tomography (DERT) method to investigate its application in mineral exploration. In particular, we use the Fullwaver technology developed by IRIS Instruments to study the full 3D resistive structure of the Calamita distal Fe-skarn deposit, Elba Island, Italy. This innovative hardware allows a full 3D deployment of autonomous and cable-less receivers and contrasts with traditional resistivity methods by its easy set-up and applicability in difficult contexts.

In November 2022, a 3D DERT survey has been carried out to investigate the Calamita deposit, consisting of massive magnetite-hematite ore bodies hosted in marbles overlaying micaschists of Tuscan Units. Skarn mineralogy/geochemistry and fluid inclusion characteristics suggest a magmatic source for the mineralizing fluids. 148 current injections have been performed on 48 receivers over an area of 2km² with the aim to reach exploration depths ranging from 600 m to 700 m. Geophysical data were combined with a high-resolution 3D Digital Elevation Model acquired by standard and thermal drone imagery.

The 3D inverted resistivity and induced polarization models match with the surface geology and shallow exploration drill hole data and highlight the architecture of Calamita deposit. Strong resistivity contrasts reveal the presence of sub-vertical conductive and chargeable pipes connecting the different skarn bodies at depth, interpreted to represent the paleo-hydrothermal upflow zones. The pipes point towards the inferred cupola of a magmatic intrusion that potentially triggered the formation of the ore deposit. High chargeability anomalies suggest the presence of hidden massive ore bodies and disseminated mineralisation on the flanks of the system.

DERT has the potential to investigate and explore mineral deposits in full 3D, with high sensitivity, and in logistically complex settings.

How to cite: Braize, D., Sfalcin, J., Lupi, M., Kouzmanov, K., Dini, A., and Morelli, G.: Deep Electrical Resistivity Tomography as a mineral exploration tool: the Calamita distal Fe-skarn, Elba Island (Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16567, https://doi.org/10.5194/egusphere-egu23-16567, 2023.

EGU23-17258 | Orals | ERE4.3

Dig_IT – A human-centred Internet of Things platform for the sustainable digital mine of the future 

Diego Grimani, Lorenzo Bortoloni, Damiano Vallocchia, Maria Garcia Camprubi, and David de Paz

Dig_IT project aims to develop a human-centred IIoT platform connecting the mining ecosystem of assets, environment, and humans to increase mining efficiency: saving costs using optimised scheduling, increasing uptime using predictive operation and maintenance, identifying new revenue opportunities using advanced geological interpretation on exploration mining phase. To address industry needs of minimising accidents, optimising production processes and reducing costs, intelligent systems will provide real-time insights for the enterprise at all operational levels.

Dig_IT follows a market need & technology offer approach aiming at covering all aspects of technical, industrial and business requirements towards a sustainable future in mining. The project’s value chain and concept has been built with the utmost objective to provide new solutions addressing the needs for safety, efficiency and sustainability, bringing innovative and competitive solutions to the mining business, face future challenges regarding standards and legislation, and spread the knowledge to as many sectors of the European extractive industry as possible.

The project aims to achieve several objectives: design and validate a smart Industrial Internet of Things platform to improving efficiency and sustainability of mining operations, achieving on-line measurements of asset-bound mining operations and online distributed measurements for broad area sustainability and occupational work environment, and Big Data optimisation through improving data quality. Furthermore, the project aims to develop Digital Twins of the physical mine entities, systems and processes, a Smart Garment and an Intelligent Toolbox for mining personnel sensing OHSE parameters, a Decision Support System and a Predictive Operation System.

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How to cite: Grimani, D., Bortoloni, L., Vallocchia, D., Garcia Camprubi, M., and de Paz, D.: Dig_IT – A human-centred Internet of Things platform for the sustainable digital mine of the future, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17258, https://doi.org/10.5194/egusphere-egu23-17258, 2023.

EGU23-17279 | Orals | ERE4.3

Underwater measurements with UX robots; a new and available tool developed by UNEXUP 

Norbert Zajzon, Boglárka Anna Topa, Richárd Zolzán Papp, Jussi Aaltonen, José Almeida, Balazs Bodo, Stephen Henley, Marcio Pinto, and Gorazd Zibret

The UX-2 robot of the UNEXMIN technology represents the newest generation of underwater explorers capable of operating in flooded mines and other closed underwater environments meanwhile providing geoscientific information. The technology was developed by an international team of scientists during the UNEXMIN (https://www.unexmin.eu/) Horizon 2020 project (2016–2019) and the UNEXUP (https://unexup.eu/) EIT RawMaterials project (2020–2022). The concept was proven in various environments and the first generation of robots was built in the UNEXMIN project. Besides technological upgrades, the UNEXUP project was focusing also on marketing and commercialization thru UNEXMIN Georobotics Ltd. (https://unexmin-georobotics.com/), the spin-off of the consortium.

The technology proved its capabilities at numerous flooded sites in various harsh environments during the last years including, abandoned mines, caves, historical sites and even drinking water facilities.

Although very bad visibility was observed in the South Crofty mine, Camborne (UK), the robot could manoeuvre down to -300 m and investigate a narrow shaft relying mainly on sonar-based navigation.

The Csór water well, the main drinking source of Székesfehérvár (Hungary) was another location where the UX technology proved its usefulness and 3D-mapped the well with centimetre accuracy for reconstruction purposes.

In August of 2022, the UX robot created a 3D topography map and continuous water parameter measurements further exploring the flooded karstic cave Hranice Abyss (Czech Republic) down to -450 m – setting up the current word depth record.

Even remote-control and full autonomy were demonstrated in Kőbánya-mine, Budapest, Hungary. During the remote-control test, the Budapest team launched the robot, but the underwater robot operation was done from INESCTEC, Portugal.

Ecton copper mine (UK) used to be the deepest mine of its age in the 18th century, closed and partially flooded for more than 160 years. Now it is a listed National Monument in the UK and is under strict protection within a site of special scientific interest. Here the UX robots proved their value in discovering new workings, connections, and technological solutions helping the archaeologists which could not be recovered by other methods as well as elucidating the geological structure.

The salt mine of Solotvyno, Ukraine was a demanding challenge as the UX robot had to be capable of operating and measuring in freshwater as well as in fully saturated (ca. 330g/l) brine with 1.25 g/cm3 density, which was located below a freshwater layer.

The abandoned fluorspar mine of Würmtal, Pforzheim, Germany was the last site visited within the frame of the UNEXUP project where the UX robot revealed its unique capabilities by exploring a large part of the flooded workings. More than 3 km was covered laterally in a single dive down to the fluorspar vein, and colour- and UV-images of the ore were delivered successfully. UX robot also brought back data, helping to assess the stability of the walls.

The UNEXMIN project was funded by the European Union thru the Horizon 2020 research and innovation programme under the no. 690008 grant agreement.

The UNEXUP project was funded partially by the European Union thru EIT RawMaterials no. 19160.

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How to cite: Zajzon, N., Topa, B. A., Papp, R. Z., Aaltonen, J., Almeida, J., Bodo, B., Henley, S., Pinto, M., and Zibret, G.: Underwater measurements with UX robots; a new and available tool developed by UNEXUP, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17279, https://doi.org/10.5194/egusphere-egu23-17279, 2023.

EGU23-384 | Posters on site | ERE4.4

Experimental investigation of multiple industrial wastes for geochemical carbon dioxide removal strategies 

Liam Bullock, José-Luis Fernandez-Turiel, and David Benavente

The Paris Agreement goal to limit the global average temperature increase to below 2°C cannot be achieved without atmospheric CO2 removal (CDR) on the order of tens of gigatonnes per year by 2100. Such a formidable challenge requires an urgent assessment of all possible routes to CDR, as further delayed mitigation will have an increasingly damaging effect on the environment. The challenge is pertinent to industrial sectors which produce several Gt of CO2 per year and are susceptible to financial impacts due to nascent carbon taxes worldwide, and other negative environmental impacts brought on by the generation of vast amounts of solid and liquid waste materials (e.g., rock cuttings and overburden, fine mine tailings, glassy slags, fly ashes and desalination reject brines). Geochemical CDR strategies in such industrial wastes, where the natural process of rock weathering and carbonate precipitation is utilised to uptake CO2, is a potentially significant CDR approach for bicarbonate (alkalinity) and carbonate generation, requiring material assessment and enhancement schemes to fully realise the high removal potential.

The DETAILS project (Developing enhanced weathering methods in mine tailings for CO2 sequestration; Marie Skłodowska-Curie grant agreement ID: 101018312) is exploring the CO2-water-solid waste material reactivity of a range of mine tailings, slags and fly ashes, sourced from industrial centres globally. The range of materials includes those considered to be chemically and mineralogically promising for CDR (e.g., mine tailings derived from olivine dunite, Ni sulphide and diamond kimberlite operations, carbonate marble fines), materials with limited or unknown CDR potential (e.g., Al-bauxite-related red muds, borate tailings, ilmenite tailings, products from SO2 processing, copper smelting produced slags and combustion fly ashes), and materials generally considered unfavourable (e.g., Cu and fluorite tailings). For all materials, the key to CDR strategy utilisation is the ability of favourable minerals to undergo significant dissolution for alkalinity generation and possible subsequent carbonation, on appropriate human timescales (e.g., seconds up to decadal), either naturally or through achieving enhanced rates of dissolution and precipitation.

Changes to water chemistry through reactions with CO2 and powdered material samples were monitored throughout the experiment. These include changes to pH, alkalinity, silica, Ca2+ and Mg2+ cations, (Mg-Ca cations required for reactions with CO2 to produce stabilised bicarbonate and carbonate ions). Preliminary results reveal that Mg- and Ca-bearing minerals within some wastes react with CO2 to form alkalinity, suggesting potential for CDR strategies. Methods to increase reaction rates will be explored, such as a microbially-induced pH switch to increase the kinetics of mineral dissolution and mineral carbonation (e.g., oxidation and reduction reactions associated with microbial metabolisms active in sulphur and nitrogen cycling). A better understanding of reaction kinetics for a wider range of industrial wastes will help future projects to confirm or re-consider the viability of materials for CDR strategies, and to better identify opportunities for upscaled pilot schemes with further implemented geochemical CDR methods to speed up reaction kinetics.

How to cite: Bullock, L., Fernandez-Turiel, J.-L., and Benavente, D.: Experimental investigation of multiple industrial wastes for geochemical carbon dioxide removal strategies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-384, https://doi.org/10.5194/egusphere-egu23-384, 2023.

A series of materials, including sand (S) silica blue (SB), iron-exchanged sand (IES), zeolite 13X (Z), ironexchanged zeolites (IEZ), and the waste material acid mine drainage sludge (AMDS), were used as adsorbents for the removal of hydrogen sulfide (H2S) from a feed stream in a pilot (bench)-scale study. Artificially polluted H2S gas streams were created using a gas cylinder with 10,000 ppmv of H2S in nitrogen (N2), which was used for further dilution. The adsorption performance of each sorbent material was assessed by dynamic breakthrough analysis. The sorbents were analyzed via Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-Ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) analysis. The efficiency of H2S removal was observed and compared between adsorbents under various operating conditions, such as different contact times and initial concentrations. The AMDS was discovered to have highest adsorption efficiency for H2S, of all adsorbents studied here. The Yoon-Nelson, Thomas and Adam-Bohart models were applied to study the effects of H2S concentration and flowrate on adsorption of H2S on AMDS, and the maximum adsorption capacity of 312.73 g g1 was attained
at 1000 ppmv and 0.5 L min1 of H2S concentration and flow rate, respectively. This study found that all tested adsorbent materials have appreciable H2S adsorption capacity and AMDS in particular is an appropriate adsorbent for treatment of H2S-contaminated steam. Moreover, AMDS is a waste material and is available in abundance; hence, AMDS could be a practical choice for the adsorption of H2S from biogas.

How to cite: Choi, J.: Removing hydrogen sulfide from a feed stream using suitable mine raw materials, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1057, https://doi.org/10.5194/egusphere-egu23-1057, 2023.

EGU23-1188 | ECS | Orals | ERE4.4

A coupled hydrodynamic-biogeochemical model for the prediction of mine pit lake water quality 

Maryam Zarrinderakht, Silvano Salvador, and Alan Martin

Pit lakes are a common feature of the post-closure landscape at mine sites where mining voids are allowed 
to fill with surface runoff, direct precipitation, and groundwater. Pit lakes also commonly serve as focal points 
for post-closure water management, often serving as a receptacle for various mining-related drainages and 
the final point of discharge for mine effluents. Therefore, an accurate and acceptable numerical model 
capable of predicting pit lake water balance, mixing characteristics, and water quality is needed to support 
post-closure management. In this paper, a coupled hydrodynamic-biogeochemical model (PitMod) for water 
quality prediction is described. The model, described in Crusius et al. (2002) and Dunbar (2013), simulates 
the physical and geochemical evolution of pit lakes over pit filling times ranging from monthly to century time 
scales. Within PitMod, the pit lake is approximated based on a one-dimensional, horizontally averaged 
vertical layer scheme. PitMod calculates the time-dependent vertical distribution of physical and geochemical 
pit lake properties, including temperature, salinity, conductivity, and dissolved oxygen. In this regard, the 
physical component of PitMod considers the effects of pit morphology, climate data, multiple surface and 
sub-surface (groundwater) inflows/outflows, precipitation/evaporation, surface ice formation/melting, vertical 
mixing due to surface wind stress, convective circulation, and turbulent mixing. The geochemical portion of 
PitMod utilizes a customized version of PHREEQC, capable of a wide variety of aqueous geochemical 
calculations, including speciation, saturation index calculations, mineral equilibria, surface complexation 
(adsorption) reactions, ion exchange, and redox processes. The model can also incorporate predictions of 
dissolved metal scavenging by biogenic particles in response to lake primary production.
PitMod, which has been applied at over 50 mine projects since 2002, incorporates physical processes like 
those found in other lake models such as DYRESM (Imerito, 2007), and has been validated against field 
observations. However, unlike DYRESM, PitMod offers the advantage of being able to incorporate various 
non-conservative geochemical and biological processes that are relevant to predictions of long-term water 
quality.

How to cite: Zarrinderakht, M., Salvador, S., and Martin, A.: A coupled hydrodynamic-biogeochemical model for the prediction of mine pit lake water quality, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1188, https://doi.org/10.5194/egusphere-egu23-1188, 2023.

Significant amounts of sediments are stored in natural lakes and dams. In the Erzgebirge, Germany, these sediments were eroded from surrounding areas and are often contaminated by metal(loid)s. This leads to a potential risk for water quality. The sediments themselves reduce the water storage capacity of these reservoirs. Decreasing capacities of landfills necessitate comprehensive treatment and recycling strategies to reduce the solid concentrations of the main contaminants (As, Pb, Cd, Cu, Zn). The aim of the study was to determine the spatial and fractional distribution of concentration and chemical bonding conditions of these metal(loid)s in the sediments of the investigation area to derive effective treatment technologies. For this, the total solid concentration, and the leaching behaviour of the metal(loid)s have to be determined. Therefore, representative samples were studied under reducing conditions using ‘aqua regia digestions’, sequential extractions with the fine grained fraction (≤ 0.063 mm), and elution tests with precipitation water and ultrapure water. The results show that pH, grain size and metal(loid) concentrations of the eluate and the solid depend on catchment areas, flow conditions, deposition conditions within the dam, and sediment depth. Maximal solid concentrations were detected between 30 cm and 60 cm sediment depth. There is no significant difference in solid concentration of the metal(loid)s between the fine grained fraction and the coarse grained fraction (> 0.063 mm, ≤ 2 mm). The main contaminants are bound in different proportions to non-residual compounds, thus less to silicates. The dissolved concentrations of the metal(loid)s, determined by the elution tests with the two solvents considered, do not differ significantly from each other. The study shows that mobilization may be an effective treatment option for these subaquatic sediments, but its evaluation requires further investigation.

How to cite: Hartmann, C. and Scheytt, T.: Concentration and chemical bonding conditions of metal(loid)s in mining contaminated subaquatic sediments of the Hüttenteich near Berthelsdorf, Saxony, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1371, https://doi.org/10.5194/egusphere-egu23-1371, 2023.

Since the first scientific observations on mine wastes hundreds of years ago, we have gained some phenomenal knowledge of mine wastes based on a great diversity of characterisation protocols and tests. Traditionally, such mine waste characterisation provides information on current and future environmental conditions, because current mining operations manage mine wastes based on a linear economy thinking (“take-make-dispose”). By contrast in a circular economy ("make-use-return"), mining should produce little waste, any raw material losses to waste streams should be minimized, and any waste generated should be characterized for possible reuse, recycling or remining. In fact, mining can make substantive contributions to circular economy systems, by designing wastes out of entire value chains and looping mine wastes back into the material flows. As part of this new approach, historic mine waste piles of diverse mineral commodities have moved into focus as potential sources of metals and industrial minerals (e.g. phosphogypsum) as well as critical raw materials (CRM). The objective of this contribution is to review the various tools available to characterise mine wastes on a macro to micro scale for circular economy systems. Such a new approach requires protocols and test methods that support novel recovery technologies, innovative environmental advances and new by-product value chains. Yet, today’s waste characterisation protocols and test methods still focus on environmental risks, have serious limitations, are riddled with uncertainties that are hard to quantify, or only allow predictions of waste properties that represent best estimates. The time has come to drastically improve our scientific efforts to precisely characterise mine wastes on all scales for circular economy purposes (micro to macro scales). This route to greater confidence in the characterisation of mine wastes will come from new macro approaches (e.g. remote sensing, monitoring of waste dumps), meso tests (e.g. infield analyses, sensors), and micro laboratory analyses (e.g. computed tomography). There is reason for optimism that the required progress is possible. In future, researchers have to provide new tools that support innovative circular practices and novel approaches to resource recovery from mine wastes.

How to cite: Lottermoser, B.: A review of protocols and tests to characterise mine wastes for circular economy strategies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1797, https://doi.org/10.5194/egusphere-egu23-1797, 2023.

EGU23-3582 | Posters on site | ERE4.4

Geochemical and mineralogical characterization of granite quarry scraps for their valorization as raw materials for ceramic products. 

Carmela Vaccaro, Antonello Aquilano, Giovanni Soro, and Elena Marrocchino

The extraction and processing chain of ornamental stones involves a long trail of waste throughout the process. In fact, about 20-22 % of the original block becomes waste in the cutting operations [1], and it goes up to 75 % of the excavated material when considering the entire chain from extraction to sawing, cutting, and polishing [2]. These percentages are higher in leuco-granite quarries as they are often crossed by dikes and small pegmatite intrusive bodies which are landfilled due to aesthetic defects that make them unusable in the context of ornamental stones.

The waste generated in the context of quarrying activities produces significant landscape and environmental problems due to the high volume and the possible presence of rare metals (Critical Raw Materials - CRMs) that can be mobilized and diffused in the hydrosphere and biosphere. In fact, massive accumulations of waste strongly impact the territories hosting the quarries due to land consumption and as possible sources of pollution [3].

The region of Sardinia (Italy) is the main producer of ornamental granite, with currently more than 350 active and inactive quarries, and huge amounts of waste from granite processing have accumulated in quarry areas throughout the region and these quarries are also near archaeological and landscape interest areas.

This paper focuses on a quarry located in the municipality of Buddusò, in the quarrying district of northern Sardinia. In this quarry, which has been active for over forty years, massive waste deposits have been created and can be seen a few km away from the site.

The aim of this work is to characterize from a geochemical and petrographic point of view the granite waste coming from the quarry and the products obtained through the processes of crushing and gravitational and magnetic separation of the minerals operated on such waste. This is to evaluate the possibilities of recycling granite waste for possible use in the context of the ceramic industry and to explore the possibility of extracting REE since this waste is rich in allanite (rare earth epidote).

The results of the analyses highlighted a rather homogeneous chemical-mineralogical composition of the samples taken from the various landfills present in the quarry under study.

As regards the results of the analyses carried out on the products obtained through the working processes on granite scraps, they have highlighted a high potential of these materials for possible use in the context of the ceramic industry. In fact, the composition of these products showed very low Fe2O3 content (< 0.35 %) and falls within the compositional ranges proposed by Fabbri & Fiori [7] of raw materials for mixtures to produce stoneware.

 

References

  • Rana, A. (2016). J. Clean. Prod., 135.
  • Silveira L.L.L. et al. (2014) In Tecnologia de Rochas Ornamentais: Pesquisa, Lavra e Beneficiamento; CETEM/MCTI: Rio de Janeiro, Brazil; Chapter 7.
  • Lokeshwari M. & Jagadish, K.S. (2016). Procedia Environ. Sci., 35.
  • Fabbri, B. & Fiori, C. (1985). Min. Petr. Acta, 29.

How to cite: Vaccaro, C., Aquilano, A., Soro, G., and Marrocchino, E.: Geochemical and mineralogical characterization of granite quarry scraps for their valorization as raw materials for ceramic products., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3582, https://doi.org/10.5194/egusphere-egu23-3582, 2023.

EGU23-3837 | Orals | ERE4.4 | Highlight

Recovery of critital raw materials from mining wastes: challenges, opportunities and barriers. 

Carlos Ruiz Cánovas, Jose Miguel Nieto, Manuel Olias, Francisco Macias, Maria Dolores Basallote, Rafael León, Jonatan Romero, and Rafael Pérez-López

Mining is a critical activity aimed at providing commodities for economic developing. However, the generation of wastes in the vicinity of the mines may lead to severe environmental problems and human health risks. Therefore, mining companies have to face huge investments in remediation options. This situation is especially challenging in historical mine sites, which accumulate large amounts of metal-rich wastes without any environmental regulation [1]. However, these wastes could be a source of critical raw materials due to the high concentrations observed for some elements. This is especially important in those countries with absence of primary deposits, which suffer from a strong external dependence for supply. The recovery of these critical raw materials could constitute a great opportunity to satisfy the internal demand and at the same time help to offset expensive waste treatment costs. However, the effective recovery of these valuable elements requires a vast amount of previous work such as site-by-site studies to determine the potential metal grade in wastes and deep investigation of mineralogical siting of valuable metals in these wastes or selective recovery methods. In this sense, there are some social, economic and technological barriers that must be overcome to achieve the final recovery. In this sense, the use of waste materials has commonly met resistance in the industrial sector and only being accepted after proved experience is achieved. On the other hand, the application of technologies may face technical and economic barriers such as the non-selectivity of extraction and recovery methods developed and the high initial costs which put in risk the return on investment and the cost efficiency of the recovery scheme [2]. Therefore, deep case-by-case investigation is required to achieve cost-effective secondary source of critical raw materials from wastes.

 

[1] Cánovas, C.R., Macías, F., Basallote, M.D., Olías, M., Nieto, J.M., Pérez-López, R., 2021. Metal(loid) release from sulfide-rich wastes to the environment: the case of the Iberian Pyrite Belt (SW Spain). Current Opinion in Environmental Science & Health 20, 100240. https://doi.org/10.1016/j.coesh.2021.100240.  

 

[2] Cánovas, C.R., Macías, F., Pérez-López, R., Basallote, M.D., Millán-Becerro, R., 2018. Valorization of wastes from the fertilizer industry: Current status and future trends. J. Clean. Prod. 174, 678e690. https://doi.org/10.1016/j.jclepro.2017.10.293.

How to cite: Ruiz Cánovas, C., Nieto, J. M., Olias, M., Macias, F., Basallote, M. D., León, R., Romero, J., and Pérez-López, R.: Recovery of critital raw materials from mining wastes: challenges, opportunities and barriers., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3837, https://doi.org/10.5194/egusphere-egu23-3837, 2023.

EGU23-4871 | Orals | ERE4.4 | Highlight

The critical importance of mine waste- an Australian Perspective 

Anita Parbhakar-Fox

Australia, whilst host to many greenfield exploration and new mining activities, also contains at least 50,000 abandoned or historic mine sites. These may not necessarily present immediate or long-term environmental risks (e.g., noxious dust or acid and metalliferous drainage (AMD) formation), but may still contain mine waste (e.g., tailings, waste rock, slag) ultimately requiring rehabilitation. Who is ultimately required to fund and complete rehabilitation may be controversial and/or contentious depending on the circumstances of mine closure. However, across Australia, there is a growing recognition that these sites may contain critical raw materials (CRMs), particularly those required for the energy transition leading to the birth of several research programs to investigate the secondary prospectivity of mine waste. In addition to individual mining companies, Geoscience Australia and the Queensland, New South Wales, Northern Territory and South Australian Governments have commissioned research to investigate the tenor and deportment of critical metals (as identified by the Australian Government) including cobalt, rare earth elements (REE), vanadium, indium, gallium, germanium, selenium, antimony, bismuth and manganese. Currently, over 40 sites have been sampled (targeting tailings, waste rock and metallurgical wastes including slag, phosphogypsum slimes, spent heap leach and coal combustion products) and assessed using an integrated geometallurgical testing program.

Early results have identified REEs (lanthanum and cerium) in tailings and waste rock at the Mary Kathleen mine, Queensland. New metallurgical extraction methods are being developed to enable ‘greener’ recovery. In addition, cobalt has been identified in the waste associated with iron-oxide copper gold (IOCG) and sedimentary hosted copper deposits in the North West Minerals Province, Queensland encouraging operational mines to consider mineral processing plant modifications to recovery this battery metal. Distinct manganese enrichment has been observed in wastes associated with Broken Hill type deposits, whilst indium is associated with volcanic hosted-massive sulphide (VHMS) and greisen deposits. Ongoing research is focused on developing business cases for CRM extraction at fertile sites. Post extraction, additional valorisation opportunities are being sought (e.g., aggregates, sulphuric acid production, ore sands) for the residual waste, and those barren (in CRM terms). By considering mine waste in these terms, Australia has an opportunity to significantly establish and grow their circular economy and take steps towards meeting their ambitious economic targets (AUD $26 Billion by 2025).

How to cite: Parbhakar-Fox, A.: The critical importance of mine waste- an Australian Perspective, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4871, https://doi.org/10.5194/egusphere-egu23-4871, 2023.

EGU23-5427 | Posters on site | ERE4.4

Ultramafic mine waste - potential material for CO2 storage and metallic elements immobilization 

Jakub Kierczak, Błażej Cieślik, Anna Pietranik, Alicja Łacińska, and Keith Bateman

Carbon dioxide, which is a direct product of the combustion of fossil fuels is the main component that enhances the greenhouse effect on Earth. For years, solutions have been developed to reduce the carbon dioxide present in the atmosphere. One of the methods of CO2 reduction is the mineral carbonation of rocks and anthropogenic materials. As a result of the reaction of silicates with CO2, new carbonate minerals that are stable under surface conditions are formed. Ultramafic rocks are considered one of the best substrates for mineral carbonation with the experiments showing relatively high carbonation efficiency. This is because they contain abundant Mg-rich minerals (olivine, serpentine) that readily react with CO2-rich fluids to form Mg-carbonates and silica. However these rocks contain also high abundances of metallic elements, in particular Ni, Cr, and Co, that may be mobilized during the carbonation experiments. This presentation aims at the characterization of selected ultramafic mine waste, in terms of the metallic element content. The goal of our research is to answer the question of whether it is possible to simultaneously bind both CO2 and metallic elements using mineral carbonation experiments.
We have chosen three types of ultramafic rocks for our study, two are from abandoned quarries and the third is a mine waste accompanying magnesite exploitation. Their chemical composition is characteristic of ultramafic rocks with high contents of silica and magnesia (both up to 40 wt %), with minor Fe2O3 and alumina (up to 10 and 3 wt % respectively). Metallic element content reaches values of up to 3,400 mg kg-1 for Cr, 2,500 mg kg-1 for Ni, and 125 mg kg-1 for Co. Two rocks represent partially serpentinized peridotites, whose main minerals are olivine and serpentine. The third rock is serpentinite, composed almost exclusively of serpentine group minerals. The minor phases in all the rocks are chlorite and spinel group minerals, with variable chemical compositions ranging from magnesiochromite through Cr-magnetite to magnetite. Peridotites contain amphiboles as minor components whereas carbonates (dolomite and magnesite) and sulfides (mainly Ni-Fe sulfides) were identified as accessory minerals in all the samples. The main Cr-bearing phases are the spinel group minerals, in the case of Ni these are serpentines and olivines, while Co is mainly concentrated in sulfides. Bulk chemical analyses of magnesite veins, naturally occurring in one of the quarries, revealed up to 250 mg kg-1 of Ni, and up to 3 and 5 mg kg-1 of Cr and Co, respectively. Although this indicates that magnesite has the potential to structurally incorporate Ni, further investigations are required to constrain the incorporation mechanism and the potential for the immobilization of Cr and Co in carbonate minerals.
Acknowledgment
The work is funded by the National Science Centre, research project No. 2021/43/B/ST10/01594.

How to cite: Kierczak, J., Cieślik, B., Pietranik, A., Łacińska, A., and Bateman, K.: Ultramafic mine waste - potential material for CO2 storage and metallic elements immobilization, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5427, https://doi.org/10.5194/egusphere-egu23-5427, 2023.

EGU23-6013 * | Posters on site | ERE4.4 | Highlight

Use and recovery of mining waste and tailings for sustainable management of works related to extractive activities 

Giovanna Dino, Susanna Mancini, Marco Casale, and Manuela Lasagna

Extractive waste (EW), including tailings, are produced in large quantities during mining activities.

In recent years, the linear economic model (based on “take-use-and-throw” approach) has been replaced by a circular approach, in which even waste and extractive residues acquire importance through sustainable use and recovery.

The use and recovery of EW shows also positive technological (in term of technological innovations), economic and social (in terms of new expertise and skills linked to sustainability), and environmental impacts (to be evaluated and faced to reduce the ecological footprint).

The use and recovery of EW takes place through the application and development of innovative protocols linked to waste exploitation (sustainable and environmentally friendly), i.e. BAT, which aim at the technological and process improvement of the activities and at the production of renewed, highly performing green materials. Mining waste and tailings, if suitably characterized, can be used to improve and make sustainable the works connected to the management of mining activities.

The qualitative-quantitative characterization of EW is essential not only for any subsequent reuse but also for assessing the extent of environmental impacts (AMD, dust, high concentrations of heavy metals, etc.) in the various matrices and risk to human health and the environment.

The application areas of use vary according to the type of waste and mining tailings, the morphological characteristics of the deposits, and the geological, geomorphological and logistic context of the area.

In this study, some examples of sustainable use of tailings and mining waste are presented (i.e. use of calcareous tailings to reduce acid drainage and the production of artificial substrates for environmental rehabilitation, waste for mining backfills, waste/landfill waste recovered for extraction RM/CRM, etc.). Further to this, positive impacts on the economic, environmental and technological/social level are also analysed. The latter actions, together with energy saving and the adoption of appropriate financial instruments, contribute to the transition of mining activities into "sustainable mining".

How to cite: Dino, G., Mancini, S., Casale, M., and Lasagna, M.: Use and recovery of mining waste and tailings for sustainable management of works related to extractive activities, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6013, https://doi.org/10.5194/egusphere-egu23-6013, 2023.

EGU23-7324 | ECS | Posters on site | ERE4.4

Hyperspectral sensing as a tool for smart environmental monitoring in mine waste management 

Hernan Flores, Tobias Rudoplh, and Stefan Möllerherm

The use of hyperspectral imaging (HSI) at different scales has become a big ally for a large range of applications in remote sensing, especially within the mining life cycle. In this contribution, we explore the use of HSI sensing, particularly to monitor mine waste at different constellations that might face environmental damaging phenomena: Acid Mine Drainage (AMD). Failure to accurately monitor and remediate such a complex process, leads to long-term impacts on ecosystems and human health, in addition to significant financial consequences and reputational damage to operators. We propose a workflow to integrate hyperspectral visible to near-infrared (VNIR) data, together with mineralogical and geochemical data to precisely map the extent of acid mine drainage using machine learning algorithms. Collected data from the field and further laboratory analyses on a few specimens provide the ground-truth and training data to support the proposed mapping algorithms. Results consist of semi-quantified concentration of dissolved metals, physicochemical properties in water bodies, and associated AMD minerals sub-products (e.g., goethite, jarosite, schwertmannite) within mine waste materials, as well as mineralogical characterization for predictive modeling at laboratory scale.  Regardless of the scale of acquisition, spectral imaging represents a cost-effective tool to enhance the quality of classical environmental analyses both in active and post-mining scenarios, which can increase the overall accuracy of the monitoring, allowing frequent and multi-temporal observations to reveal risk scenarios, take fast corrective actions and keep a continuous control.

How to cite: Flores, H., Rudoplh, T., and Möllerherm, S.: Hyperspectral sensing as a tool for smart environmental monitoring in mine waste management, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7324, https://doi.org/10.5194/egusphere-egu23-7324, 2023.

EGU23-8606 | ECS | Posters on site | ERE4.4

Reuse of by-products coming from blasting of unstable rock elements. 

Marco Casale, Giovanna Antonella Dino, and Claudio Oggeri

The improvement of safety conditions of unstable rock slopes can be achieved through the use of explosives, for the removal of unstable rock elements. This technique is often applied because, most of time, drill and blast operations, where they can be used, are cheaper and faster than other techniques and require less subsequent maintenance interventions.

When the activity is performed in an area that can be reached by vehicles (quarry area, slope above a road, etc…) it is possible to recover the blasted material.

Depending on the size of the unstable element to be removed, this kind of operations often lead to the production of large quantities of blasted rocks, which most often ends up at landfill or is marginally reused in unqualified manner (construction of temporary tracks, filling voids left by extractive activity, etc…).

Reusing blasted rocks can offer several benefits: more sustainable engineering practices, economic, environmental and social benefits; in particular, this way of operating can preserve natural resources and prevent the production of unwanted waste. As a rule, on-site and nearby-site reuse is preferred to meet sustainable goals. Specific cases where blasted material has been adopted for both slope protection and final rehabilitation works, in a quarry area, can be mentioned.

Unfortunately, due to unclear legislation, lack of technical data and extreme variability of the materials produced (for instance quantity, size and physical properties), the use of blasted material is not common: It can be estimated that only 20-30% of these materials are currently reused properly.

To improve this practice, the type of reuse must be a design goal since the beginning of the planning phase.

According to the quality of the rock mass and the type of blasting, different by-products can be obtained, i.e. armour stones to be applied in hydraulic engineering works, gabion stones, drainage stones and crusher run as a mix of different types of aggregates, that can be employed as paver layer on road construction.

When ornamental stone quarries are involved, hard rock fragments are obtained for high mechanical performances.

The main purpose of blasting demolition of unstable rock elements, as mentioned, is to improve the safety conditions of the site, depending on local features, as well as by the safety of the workers, that can force the blasting scheme geometry and firing and impose important limitations on the operating techniques.

Two case studies will be presented, both in the Verbano-Cusio-Ossola (VCO; Piemonte - NW Italy) extractive area; they show how the blast design can be arranged to obtain different fragmentation and greater quantities of a specific by-product, according to the local needs and specific reuse.

 

Key words: by products, blasting, muck reuse, solid waste, slope protection.

How to cite: Casale, M., Dino, G. A., and Oggeri, C.: Reuse of by-products coming from blasting of unstable rock elements., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8606, https://doi.org/10.5194/egusphere-egu23-8606, 2023.

EGU23-9294 | ECS | Posters on site | ERE4.4

In-situ remediation enlightens a down-to-earth pathway for managing the pyrite ash dumps in Italy: challenges in potentially toxic elements retention and CO2 mitigation 

Yikai Liu, Simone Molinari, Maria Chiara Dalconi, Luca Valentini, Maurizio Pietro Bellotto, Giorgio Ferrari, Graziano Rilievo, Gabriella Salviulo, and Gilberto Artioli

With the unprecedented urbanization in the last decades, massive solid wastes containing potentially toxic elements (PTEs) have been generated and dumped, which can be detrimental to soil health and affect flora and fauna. To minimize the exposure risks, delivering in-situ or ex-situ sustainable management of solid wastes continues to be one of the biggest public health challenges worldwide. Concurrently, in-situ high-performance solidification/stabilization© (S/S) has been proposed as a remediation strategy to prevent the release of pollutants in the stockpile sites, with ordinary Portland cement (OPC) being conventionally used as a cost-effective binder. However, growing concerns related to the substantial greenhouse gas emissions associated with the OPC production process and the limited PTEs retention capacity of OPC make the application of OPC under scrutiny. In this work, we examined the feasibility of minimizing the use of OPC in the S/S process of pyrite ash, a typical Pb and sulfate-rich solid waste generated in the sulfuric acid production industry. Four alternative binders (CEM/IIIB, calcium aluminate cement, white-steel-slag and ground-granulated blast-furnace slag mixture, and alkaline-activated ground-granulated blast-furnace slag) were tailored as solutions alternative to conventional OPC, with the aim of mitigating the anthropogenic CO2 emissions and promoting the PTEs retention. The experimental characterization and geochemical modeling of the stabilized products revealed the different interactions between the applied binder scenarios and pyrite ash, which clarifies the roles of hydration products and the binding systems’ microstructures on the Pb and sulfate leachability. Further, we evaluated the cradle-to-gate carbon footprint and cost analysis associated with each binder-pyrite ash system. Overall findings underscore that applying these alternative binders could be pivotal in the envisaged carbon-neutral scenario and offer technical benefits in future field trials if the growth of the cement-free roadmap continues.

How to cite: Liu, Y., Molinari, S., Dalconi, M. C., Valentini, L., Bellotto, M. P., Ferrari, G., Rilievo, G., Salviulo, G., and Artioli, G.: In-situ remediation enlightens a down-to-earth pathway for managing the pyrite ash dumps in Italy: challenges in potentially toxic elements retention and CO2 mitigation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9294, https://doi.org/10.5194/egusphere-egu23-9294, 2023.

EGU23-9592 | ECS | Orals | ERE4.4

Cover design considerations for mine waste rock dumps in subtropical environment  

Mandana Shaygan, Thomas Baumgartl, and Mansour Edraki

During mining activities in Australia, overburden is removed and deposited on the land in the form of waste rock dumps. When these waste rocks are exposed to atmospheric conditions and during rainfall events, they can create adverse environmental impacts through acidity and salt generation and release of metals, affecting surrounding environments, particularly final voids and water ways. The potential for impacts can be managed by rehabilitation, for example, by using soil and vegetation covers, and in some cases a barrier layer that excludes most of the rainfall from the underlying rocks. Apart from the generic objectives of rehabilitation i.e. safe, stable, non-polluting and being able to sustain a post-mining land use, cover design objectives include quantitative performance measures. Covers are intended to reduce oxygen ingress and/or net percolation into waste rock dumps. There are examples of failed covers in Queensland, Australia, due to a combination of factors such as inappropriate predictions of material performance and/or water balance. Even a very small water percolation may flush the reaction products out of waste dumps and release a significant load of acidity as seepage. Therefore, the efficiency of the cover depends not only on net percolation, but also on a range of other actors including the pre-cover conditions of the dump, the mineralogy and particle size distribution of rocks, structure of the dump and temperature and microbial activity. In Queensland, during development of Progressive Rehabilitation and Closure (PRC) plans, cover design planning needs to include identification and specification of the objectives of the cover system. If the objective is to reduce or eliminate residual environmental risks, then all relevant factors should be considered in design. In the case of coal mines of Queensland, a series of case studies have been conducted to classify, characterise and evaluate the ability of salt generation for different waste rocks. This provides an opportunity to recommend a guideline for the most effective cover design in a subtropical environment. These studies showed that firstly, the intensity and longevity of salt release are waste rock specific, and are linked to their original lithology, intrinsic salts, the presence of minerals and the magnitude of the dissolution and adsorption–desorption processes. The typical rehabilitation technique in Australia involves creating a landform using waste rocks, placement of soil on top of the waste rock pile and seeding, to create conditions for plant growth on the landform. Salt release from the waste rocks is one of the key factors that can limit plant growth, not only by creating saline seepage, but also by upward salt movement during dry periods. Therefore, attention should be given to the waste rocks sizes and their degradation degree to help determine their optimal placement in the cover design, as initial particle size and their dispersivity govern salt generation. Hydro-geochemical models, which can perform complex scenarios and mechanisms, and also include climatic scenarios, can be used to predict the salt and water movement within and from a cover design and thus predict the efficiency of the designed cover.

How to cite: Shaygan, M., Baumgartl, T., and Edraki, M.: Cover design considerations for mine waste rock dumps in subtropical environment , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9592, https://doi.org/10.5194/egusphere-egu23-9592, 2023.

EGU23-12445 | ECS | Posters on site | ERE4.4 | Highlight

POST-QUARRY LANDSCAPE. 3D representation and topology alteration as a tool for landscape recovery and secondary raw material procurement in the context of granite quarries. 

Lorenzo Tinti, Gianni Lobosco, Marco Medici, Antonello Aquilano, Luca Emanueli, and Carmela Vaccaro

At the end of their activity, quarries require environmental recovery in order to ensure a new balance between the quarry site and its physical and ecological context. Moreover, the activities of the ornamental rock extraction produce a large amount of extraction waste which profoundly modify the site's topography in an increasing way as the accumulations are formed progressively during the quarrying process. These wastes can be either recycled as secondary raw materials (e.g., in the context of the ceramic industry) or reused within the quarry site to mould a new topography and a new landscape as a result. Earth sciences and landscape architecture should constitute the disciplinary basis on which to develop the recovery project associated with the supply of secondary raw materials and the environmental improvement of the quarry site. This contribution discusses the case study of the Buddusò granite quarry (northern Sardinia, Italy), where a design methodology based on topology alteration of the site was applied. Through 3D survey and parametric design, it is possible to calculate the waste volumes within the excavation site and estimate how much and in what way the waste material can be recycled and reused. The first phase of the process consists of taking orthophotographic images by drone with subsequent georeferencing through G.P.S. points acquisition. After processing the acquired data, the topography of quarry volumes is recreated in an explorable 3D model. The last phase concerns the design management of the site topology through the application of parametric design tools. The objective is to create an adaptive project based on parameters such as: the balance between excavation and fill volumes; the recycling potential of waste material; the dynamics of water runoff; the ecological and ecosystem site potential; the site accessibility. The presented design methodology can be carried out either in the pre-quarry phase and/or during the quarry's operation, which allows an a priori assessment of what the future landscape will look like as a consequence of quarrying activities and subsequent site recovery. In practical terms, the presented methodology become a preliminary tool for the assessment of landscape evolution scenarios and ensures that the extraction cycle can be completely closed by reintegrating waste volumes into the recovery process. 

How to cite: Tinti, L., Lobosco, G., Medici, M., Aquilano, A., Emanueli, L., and Vaccaro, C.: POST-QUARRY LANDSCAPE. 3D representation and topology alteration as a tool for landscape recovery and secondary raw material procurement in the context of granite quarries., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12445, https://doi.org/10.5194/egusphere-egu23-12445, 2023.

EGU23-15511 | ECS | Orals | ERE4.4

Applications of Multi-temporal DTMs in Mining Management and Environmental Analysis 

Yi-Ru Wu, Yi-Chung Chen, Rou-Fei Chen, and Kuo-Jen Chang

The mining industry, which encompasses national resource management, environmental and ecological impacts, is becoming increasingly important to sustainable development policies. Digital Terrain Model (DTM) provides a spatial distribution of numerical terrain features and the ways in which the model can be constructed and mapped have evolved through a variety of technologies, including aerial photography, airborne LiDAR and drone mapping, DTM can be subdivided into Digital Surface Model (DSM) and Digital Elevation Model (DEM). This study therefore proposes to integrate multi-technology DTMs with terrain metrology analysis to accurately define the land use profile of a mine site over time to provide transparent land use information and monitor environmental changes. In addition to estimating assessment of the mine site is investigated, and vertical accuracy analysis based on spatial grid sampling and the 2018 airborne LiDAR DEM is conducted to assess the error between data to calculate surface volume variation and demonstrate elevation profile changes. According to the results of the accuracy analysis, the 2003 aerial photography DTM showed a larger average error of -0.19 m with a standard deviation of ±1.71 m compared to the airborne radar and UAV; the 2015 airborne radar DEM showed an average error of 0.00 m with a standard deviation of ±0.11 m; and the 2022 UAV DSM showed an average error of 0.00 m with a standard deviation of ±0.10 m. Aerial photographic DTMs can demonstrate the early geomorphology of the study area; airborne LIDAR DEMs can present a wide range of high-precision and high-resolution topographic information features that can penetrate vegetation; and UAV DSMs can reflect regional surface changes, such as mining volume variation in open pit mines. 

How to cite: Wu, Y.-R., Chen, Y.-C., Chen, R.-F., and Chang, K.-J.: Applications of Multi-temporal DTMs in Mining Management and Environmental Analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15511, https://doi.org/10.5194/egusphere-egu23-15511, 2023.

EGU23-15985 | Orals | ERE4.4

First insights into mineralogy and weathering of the slags produced by smelting lateritic Ni ore at Vozarci, North Macedonia 

Tamara Đorđević, Peter Nagl, Christian L. Lengauer, Uwe Kolitsch, Goran Tasev, Todor Serafimovski, Ivan Boev, and Blažo Boev

The laterite Ni ore smelting operations at Vozarci, North Macedonia, which produces ferronickel since 1982, have produced large amounts of smelting wastes dumped at the smelter. In May 2022 we have sampled three different types of slags occurring in these slag dumps. Slag 1 was produced using predominantly ore imported from Indonesia, slag 2 was formed using the ore from the nearby Ržanovo mine and slag 3 was produced using predominantly ore imported from the Ivory Coast. X-ray fluorescence (XRF) spectroscopy analyses showed that slags 1 and 3 contain between 43–47 wt.% SiO2 and slag 2 35 wt.% SiO2. Relative to slags 1 and 3, slag 2 is enriched in iron (40 wt.% Fe2O3). Furthermore, slag 2 is characterized by a large Cr content (ca. 17400 ppm of Cr2O3). A combination of powder X-ray diffraction, Raman spectroscopy and SEM-EDS analyses (of polished aliquots) showed that the slags consist of silicate glass, synthetic equivalents of orthopyroxenes (enstatite), clinopyroxenes (clinopyroxene, diopside, pigeonite, augite), olivines (forsterite, fayalite) and subordinate spinel-group phases (chromite, magnesiochromite, magnetite, trevorite), sulphides (pyrrhotite and FeS-NiS phases) and intermetallic compounds (metallic Fe with up to 10 at.% Ni and remnants of ferronickel). All three slags contain significant amounts of the following potentially toxic elements: Co (20-87 ppm), Cr (9600-17400 ppm), Ni (500-730 ppm) and Zn (150-380 ppm). The phase assemblages and textures in the Vozarci slags are similar to those in other pyrometallurgical slags produced during reworking of silicate and sulphide ores. Although the slags 1 and 2 have been exposed to atmospheric conditions for about 40 years, those occurring in the dumps are not much affected by weathering. At present, we have identified the following alteration products: (i) abundant iron oxy-hydroxides (including lepidocrocite) (slag 1), (ii) minor nesquehonite, MgCO3·3H2O (slag 2) and (iii) syngenite, K2Ca(SO4)2·H2O (slag 1). Since slag 3 is newly deposited slag, it is not weathered at all.

Financial support of the Federal Ministry of Education, Science and Research (BMBWF) and Austria´s Agency for Education and Internationalisation (OeAD), (WTZ Grant MK 06/2022) is gratefully acknowledged.

How to cite: Đorđević, T., Nagl, P., Lengauer, C. L., Kolitsch, U., Tasev, G., Serafimovski, T., Boev, I., and Boev, B.: First insights into mineralogy and weathering of the slags produced by smelting lateritic Ni ore at Vozarci, North Macedonia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15985, https://doi.org/10.5194/egusphere-egu23-15985, 2023.

EGU23-16221 | ECS | Posters on site | ERE4.4

Fourier Transform Infrared data analysis to analyse the environmental impact of coal mine waste 

Oscar Kamps, Fardad Maghsoudi, Feven Desta, and Mike Buxton

In the current energy transition, many governments have made plans to reduce energy production by coal. Therefore, Germany has set the ambition to close coal mines in 2030 (Wehrmann et al., 2021). The many years of mining produced a large amount of mine waste, used as a landfill. In the TRIM4mining project, a consortium of industry and academia investigate the environmental impact of coal mine waste. The samples used for this study are from the Schleenhein and Profen lignite mines in East Germany. Throughout the project, various samples were collected of specific lithologies in the mine, lithology mixtures and two drill cores of 50 meters drilled on the mine waste dump.

This study focuses on testing the applicability of Fourier Transform Infrared Spectroscopy (FTIR) for analysing lignite waste material samples. Here, the data is discussed regarding the liquefaction potential, acidification potential, secondary recovery, and heavy metal concentration. An additional abstract is submitted to present the result on how FTIR data can be used for regression modelling with the aim to integrate geochemistry and spectral infrared data for mine waste characterization.  

Preliminary results have shown clear spectral features that can be used to distinguish coal, silt, sand and clay material. Every meter of the waste material is measured to allow a core logging analysis. Besides the interpretation of the coal, clay, sand and silt fraction, various data analysis techniques are applied to interpret smaller variations in the FTIR data, that could be of interest to the environmental impact of coal mine waste.

How to cite: Kamps, O., Maghsoudi, F., Desta, F., and Buxton, M.: Fourier Transform Infrared data analysis to analyse the environmental impact of coal mine waste, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16221, https://doi.org/10.5194/egusphere-egu23-16221, 2023.

EGU23-16360 | Posters on site | ERE4.4

Multi-sensor approach for modeling rare earth elements within the lignite waste dumps 

Fardad Maghsoudi Moud, Oscar Kamps, Feven Desta, and Mike Buxton

Due to technological advances demand for rare earth elements (REEs) have been increased. However, exploration or secondary recovery of these elements has not been done properly except for a few countries in the world that supply REEs, such as China. Many studies using inductively coupled plasma mass spectrometry (ICP-MS) have been conducted on analyzing, and finding relationships of the REEs with other elements. Although these laboratory measurements are accurate, they are expensive and time-consuming. Also, a methodology or a model that helps geologists estimate the REE contents in situ is missing. Therefore, we combine the results of ICP with Fourier-Transformed Infrared (FTIR) spectroscopy to model and predict the REE contents within soil samples of mine waste dumps. The FTIR is a portable instrument that has shown many potentials in measuring mineral and organic material absorption features within the Mid-IR range.

Several studies have indicated the potential of lignite mines in the enrichment of REE minerals. Therefore, we have chosen two lignite mines: Profen and Schlenheein within Germany.  During the Miocene, different sub-tropical plants were developed within catchment basins. The decreased plants were covered by soil and glacial during the ice age. Then, the decreased plants sunk into swamps and decomposed into peats. Two parameters of ground heat and pressure led to the H, O, and nitrogen removal and formation of coal seams at the end of the Tertiary.

From the Profen area as our model training area, some of the thirteen samples (70% of the data used for training and 30% for testing), and from the Schlenheein area as our testing area, some of the hundred samples (all data were used for testing and validation) were collected from different waste dumps. The samples were used to collect the FTIR spectra and ICP-MS, and X-ray Diffractograms (XRD). The FTIR spectra were interpreted and validated with the XRD outputs. A matrix consisting of FTIR wavenumbers and their corresponding reflectance value, and ICP elemental content were created. The REEs were considered as the target parameters for modeling and FTIR wavenumbers were used as input parameters for modeling using stepwise multiple linear regression (SMLR). The SMLR models were investigated by checking the corresponding molecular bands assigned to the wavenumbers within the models and ensuring mineralogical sensibility. For the evaluation of the models, coefficient determination (R2) and root-mean-square error (RMSE) were computed. Finally, the models were applied on the testing data of the Profen area to assess their performances. Finally, the models were applied on the Schlenheein area and assessed.

The results showed that Ti has a high correlation with Y and other REEs (approximately 0.7). Also, the presence of titanite was confirmed by the XRD as titanite. Therefore, titanite is the main source of REEs within the waste dumps which was identifiable via the FTIR wavenumbers. The Profen Y model showed an R2 of 0.6 for training and testing and 0.55 for the Schlenheein area. The models showed that the FTIR is a powerful tool to quantitatively predict REE contents with an acceptable R2 and RMSE.

How to cite: Maghsoudi Moud, F., Kamps, O., Desta, F., and Buxton, M.: Multi-sensor approach for modeling rare earth elements within the lignite waste dumps, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16360, https://doi.org/10.5194/egusphere-egu23-16360, 2023.

EGU23-16590 | Orals | ERE4.4 | Highlight

GREEN MOVE project: Utilization of  waste rocks and mine tailings in building B-layer after soil relocation 

Elena Scibilia, Olga Odrzygóźdź, Trine Sogn, and Kurt Aasly

Well-developed soil is the starting point for good cultivated land, which is a prerequisite for food production. For many years there has been a decline in cultivated areas in Norway and in recent years we have seen an increasing conflict between the conservation of topsoil and the reduction of areas for use for development and infrastructure. Although there are political goals to increase cultivated areas, the reality is that more and more productive land is disappearing. There is little land available that enables the cultivation of food grains, and 35% of the remaining arable land is bog, which is not desirable to cultivate due to the effects on the environment.

The GREEN MOVE project aims at creating methods to maintain cultivated land by sustainably moving soils from the infrastructure affected sites and reconstructing agricultural soils to alternative locations avoiding important conflicting societal interests. The project aims at proposing an informed and strategic approach to a highly ambivalent issue that may enable both sustainable development of important infrastructure as well as preservation of valuable soil resources.

One of the objectives in the GREEN MOVE project is to evaluate the potential of utilizing crushed waste rocks and other mine tailings to improve subsoil properties at new locations securing agronomic plant production. To do it we need to build knowledge on how to determine the potential of utilizing crushed waste rock and other mine tailings to improve the susoil layers.

Selected waste rock materials from ongoing infrastructure projects (e.g. tunnel masses) and waste rock material from Norwegian mining industry will be characterized by use of XRD, XRF and SEM to analyze mineral content and surface characteristics. Grained rock fractions of < 2mm will then be used in simple column leaching experiments in the laboratory to determine lability of chemical components from the waste rock materials. The potential weathering rate of the different waste rock materials will also be explored in the laboratory when exposed to and being in equilibrium with still water and weak organic acids (mimicking plant root exudates). The grained fraction < 2 mm of selected waste rock materials will then be mixed by soil and/or peat and used as growth medium for plants in simple greenhouse experiments as well as in field soil lysimeters. The most promising waste rock materials will finally be used to build up soil B-horizons in field experiments with agronomic plant production. In the soil B horizon the waste mineral material will be mixed by soil and/or organic matter. Prior to the field experiments a careful selection of texture classes of the waste rocks needs to be done to secure the soil porosity, pore size distribution, permeability and water holding capacity. In the field experiments soil quality parameters and yield will be measured. 

How to cite: Scibilia, E., Odrzygóźdź, O., Sogn, T., and Aasly, K.: GREEN MOVE project: Utilization of  waste rocks and mine tailings in building B-layer after soil relocation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16590, https://doi.org/10.5194/egusphere-egu23-16590, 2023.

EGU23-1285 | ECS | Posters on site | ITS3.1/ERE4.7

Circular approach for industrial water management via water balance and LCA: A poultry slaughterhouse case study 

Chuan Jiet Teo, Thomas Wintgens, and Johann Poinapen

Ensuring the availability and sustainable water management not only is one of the UN SDGs, but sustainable water production is also one of the main accelerating global challenges within the upcoming decades. Unless the efficiency of water use rises, this imbalance of available freshwater resources and the increasing consumption will reduce freshwater ecosystem services. Industries are one of the largest freshwater consumers. Despite the huge potential to tackle water scarcity, industrial (waste)water management is often underlooked and has become a barrier to overcome to complete the transition towards a circular economy. This means designing for resource (water) minimisation and reduced hazards (such as phosphorus and heavy metals). A decentralised wastewater treatment, in association with local organisation and governance, is increasingly recognised as one of the options to contribute towards increasing the efficiency of wastewater treatment and closing the industrial water loop by the recovery and reuse of the treated wastewater. However, the design of an industrial water treatment system is a complex problem that involves different trade-offs (i.e. use of energy vs use of chemicals). In this context, life cycle assessment (LCA) offers an opportunity to evaluate the environmental sustainability of these technologies and processes, identifying the environmental impacts of the processes in the value chain by capturing trade-offs across various categories of environmental concern.

Circular water management for a slaughterhouse is especially relevant for the sustainable transition towards a circular economy. Throughout the value chain of livestock processing, the slaughterhouse is the second largest user of water, and also a potentially significant point source of pollution to local ecosystems and communities.

The objective of this study is to apply LCA and water footprint analysis to evaluate the environmental impact and missed opportunity of treating industrial wastewater streams generated from a poultry slaughterhouse located in Romania. LCA will be carried out at the planning and design levels of the wastewater system to allow analysis to be done regarding alternative wastewater management strategies, considering different treatment schemes including retrofitting physical-chemical treatment and biological treatment as separate scenarios. The foreground data is based on field data collection that considers effluent qualities. The background inventories are based on the Ecoinvent database v.3. The life cycle impact assessment is applied on both the characterised and normalised levels using the Environmental Footprint (EF) method.

How to cite: Teo, C. J., Wintgens, T., and Poinapen, J.: Circular approach for industrial water management via water balance and LCA: A poultry slaughterhouse case study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1285, https://doi.org/10.5194/egusphere-egu23-1285, 2023.

EGU23-1435 | ECS | Orals | ITS3.1/ERE4.7 | Highlight

Social and environmental impacts associated with fossil and mineral supply chains - a quantitative assessment of the EU’s international spillover effects 

Arunima Malik, Guillaume Lafortune, Camille Mora, Sarah Carter, and Manfred Lenzen

Fossil and mineral raw materials enable sustainable development and undermine it, causing unintended and detrimental environmental and social impacts via extraction and production processes. The reliance of humans on minerals has led to wide-scale mining and depletion of resources. In this study, we analyse how consumer demand in the European Union drives environmental and social impacts in mining sectors worldwide. We employ multi-regional input-output analysis to quantify positive (i.e., income, female and male employment) and negative (greenhouse gas emissions, accidents at work, and modern slavery) impacts of mining in raw material sectors, as indicators of the UN Sustainable Development Goals. We trace these environmen­tal and social impacts across the EU’s trading partners to identify sectors and regions as hotspots of international spillovers embodied in the EU’s consumer demand and find that these hotspots are wide-ranging in all continents. We estimate that across all sectors, EU’s consumption is associated with about 4200 cases of fatal accidents at work and 1.2 million cases of modern slavery annually. Raw material supply chains are respectively responsible for 5% and 3% of these totals, but also 14% of imported GHG emissions. These impacts take place primarily in Central Asia and the Asia Pacific as well as Africa. Our results underline the need for further reforms in mining industries and trade policies to eradicate modern slavery and other adverse social and environmental impacts and to implement safe workplaces for workers. Our results also highlight the need for transitioning to circularity in global supply chains for addressing the climate crisis.

How to cite: Malik, A., Lafortune, G., Mora, C., Carter, S., and Lenzen, M.: Social and environmental impacts associated with fossil and mineral supply chains - a quantitative assessment of the EU’s international spillover effects, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1435, https://doi.org/10.5194/egusphere-egu23-1435, 2023.

EGU23-2198 | ECS | Orals | ITS3.1/ERE4.7

Biogenic waste transformation into resources through anaerobic digestion 

You-Yi Lee and Chihhao Fan

A large amount of agricultural byproducts and animal husbandry waste have been produced due to the inevitable agricultural practice for human survival. The utilization of agricultural and animal husbandry residues in waste-to-energy technologies has become an eye-catching issue over years because of the concept of circular economy for sustainable development. These biogenic residues possess a high content of organic carbon such as sugars, proteins, and lipids and are being dumped into landfills or incinerated, causing severe environmental challenges and the waste of available resources. Anaerobic digestion (AD) provides a sustainable route for resource circular utilization in agriculture and husbandry waste. The dry anaerobic digestion process is adopted to treat biogenic waste including outer leaves of cabbage (C), litter (L), and pig manure (PM) in the present study. Different from the main target of past studies to enhance biomethane production, this study aimed to transform the waste into saccharides and organic acids which are the intermediates in AD processes (i.e. hydrolysis and acidogenesis phases) and can be further refined or utilized in various industries. For instance, succinic acid of high economic benefits can be obtained through transforming AD digestate. Hence, Saccharomyces cerevisiae was chosen as the microbial inoculum due to its non-gas-generating characteristic. The results of batch AD experiments for 35 days showed that the optimum feedstock mass mixture ratios are C:L = 2:1, C:L = 3:1, C:PM = 2:1, and C:PM = 3:1 since the observation of more saccharides formation. Moreover, the optimal feedstock-to-inoculum ratio (F/I ratio) is 1:1 and the best AD operation temperature is 50℃. The substance flow analysis was established based on the measurement of key AD products (i.e. saccharides, organic acids, CH4, CO2, and digestate). The batch experiments was scaled up to the 10L continuously-stirred reaction tank to determine the feasibility of in situ AD practice. In comparison to the traditional way to deal with agriculture and husbandry waste, AD is promising to be a valorized treatment to convert waste into reusable bioproducts which enables economic and environmental benefits to realize the concept of the circular economy.

How to cite: Lee, Y.-Y. and Fan, C.: Biogenic waste transformation into resources through anaerobic digestion, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2198, https://doi.org/10.5194/egusphere-egu23-2198, 2023.

Extended over 85.4 km2 with more than 2.5 million date palm trees, Al-Ahsa oasis in the eastern part of Saudi Arabia is the largest oasis in Arabian Peninsula and probably in the world. The oasis became a World Heritage site in 2018 and has also been part of the UNESCO Creative Cities Network since 2015. The urban expansion and the transition from farms being the main source of income to farms being lifestyle properties, has changed the farm management practices. However, farm ownership continues to be a very strong feature of Al Ahsa communities, with livestock raising integrated with the cultivation of date palms. In oasis farms, date palms products are used as animal feed while animal manure is used as date palm fertilizer. Unfortunately, the huge stockpiles of date palm fronds and burning within the oasis suggest that the waste management practices may not be environmentally sustainable. Therefore, this study was carried out to assess the impact of livestock raising on the oasis farms soil conditions. The methodology followed in the study involved site visits to farms, reviewing related reports and articles on farm management practices and water quality. Key findings of the study indicated that livestock raising on date palm farms has significantly increased over the last 4 decades. Since the 1970’s, the number of farms housing cows has increased from 34% to 100%, and the number with hybrid poultry farms has increased from 4% to 50%. Results indicated that the reuse of all cow and chicken sand / manure mixes, generated on oasis farms, as fertilizer would increase the nitrogen, phosphorus and potassium by 17, 32 and 8 times respectively, over the recommended levels. Moreover, further application of manure from intensive chicken and dairy enterprises located near the oasis as fertilizer is not sustainable and lead to several environmental impacts. To reduce these impacts, the study recommends the development of a composting facility for the date palm fronds which may provide a sustainable alternative waste management system for the green and livestock wastes. In addition, farmers could benefit from both a high volume, low cost mulch that could be produced from date palm pruning, and a low volume, higher cost composted soil conditioner that could be produced from low nutrient shredded green waste and high nutrient livestock waste. Reuse of these recycled products within the urban centers could improve water use efficiency and protect landscape plantings from sand storms, and could replace imported soil conditioners. These alternative waste management strategies will reduce the nutrient pressure on the oasis by redirecting organic products processed from farm wastes for beneficial reuse in urban centers.   

How to cite: Tawabini, B.: Sustainable Agriculture Waste Management Strategies: Case Study from Al-Ahsa Oasis, Saudi Arabia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2280, https://doi.org/10.5194/egusphere-egu23-2280, 2023.

This research focuses on the reutilization strategy and plan of the electric vehicle battery as the main body, if the battery is replaced. Under different development scenarios of electric vehicles, there will be uncertainty in the amount of electric vehicle batteries to be replaced later. At the same time, the service life of electric vehicle batteries may be slightly different in different years of production. Therefore, it is necessary to understand through data collection and actual interviews. Regardless of the number and the original service life, as long as it is judged that the battery must be replaced, if it can enter the reuse system and reuse it as an energy storage device in a different way, it will immediately show the extended battery energy service. Benefits, reduce environmental impact, improve resource utilization efficiency, etc.After the battery pack of the electric locomotive is replaced after regular maintenance, it may be necessary to distinguish and understand different battery states again. If it can be used again, there will be differences in the battery energy storage methods required for different battery usage habits derived from different solutions (for example, whether it is frequently charged and discharged, and whether it is more necessary to output electric energy stably). In addition to consumption habits, there are also uncertainties and situations in the use demand.The research methods that need to be used include: material flow analysis (MFA), life cycle analysis (Life cycle analysis LCA), etc. In the end, we can put forward the concept of circular economy, hoping to establish a plan or model that has economic feasibility, so that the plan may really be implemented. Therefore, in the evaluation of the program, the service of the battery is viewed from the overall life cycle, and the indicators that can be provided include resource service efficiency, energy service efficiency, and environmental impact. 

How to cite: Wang, Y.-S. and Kuo, N.: The strategy of recycling electric vehicle batteries from the perspective of circular economy in Taipei city, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2316, https://doi.org/10.5194/egusphere-egu23-2316, 2023.

EGU23-4293 | ECS | Orals | ITS3.1/ERE4.7

Towards Circular Economy by Using Green Concrete in the Egyptian Building Sector 

Heba Marey, Gábor Kozma, and György Szabó

Concrete is considered the most anthropogenic material used in the construction sector worldwide. It is associated with consuming massive amounts of energy and the depletion of natural resources, based on the increasing Egyptian urban expansion by establishing new cities to face the population growth challenges and achieve the national development strategy. The importance of applying the Circular Economy (CE) for concrete materials in the building sector became a robust key for reducing conventional concrete (CC) materials and addressing the building materials' future challenges. This study investigates the benefits of Green Concrete (GC) materials and their potential for supporting the principles of achieving circularity for concrete materials in the Egyptian building sector. Furthermore, develop a conceptual framework for using GC from the building scale perspective in two new Egyptian cities. The study attempts to answer how GC materials help achieve a circular economy and the potential benefits of integrating different CE strategies for using GC in the Egyptian building sector. The evidence-based solutions (EBS) methodology was used for collecting and analyzing data for assessing the environmental impacts based on reducing the natural resources consumption, recycling, and reusing waste products in the Egyptian building sector. Case studies are used to provide in-depth insights into the practicalities of GC. Applying the before-and-after (BAA) technique for two building models highlights the challenges and opportunities for substituting CC with GC to assess the interactive factors for achieving CE and applying sustainability. The results showed valuable insights into the potential for using GC to support the CE and have a strong ability to reduce natural resources consumption and construction waste stream, which leads to close the loop and achieving circularity in the Egyptian building sector, and recommended that Design for Recycling (DfR) strategy is the most need for improving the using of GC in the building sectors.

Keywords, Green Concrete, Circular Economy, Evidence-based Solutions, Egyptian building sector

How to cite: Marey, H., Kozma, G., and Szabó, G.: Towards Circular Economy by Using Green Concrete in the Egyptian Building Sector, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4293, https://doi.org/10.5194/egusphere-egu23-4293, 2023.

EGU23-4460 | ECS | Posters on site | ITS3.1/ERE4.7

Investigation of Municipal Solid Waste Fly Ash Reactivity into Magnesium Phosphate Cement 

Davide Bernasconi, Alberto Viani, Lucie Zárybnická, Gangadhar Das, Elisa Borfecchia, Caterina Caviglia, Enrico Destefanis, Roberto Gobetto, and Alessandro Pavese

Municipal solid waste incineration fly ash (MSWI-FA) is one of the solid by-products of MSWI treatment, accounting for about 1–3% of the total incinerated waste. FA forms in the plant purification system and bears important amount of heavy metals and salt (chloride and sulphate), therefore it is considered as hazardous waste (Bernasconi et al, 2022). For this reason, FA is required to undergo stabilization/inertization treatment (one of the most common is water washing), before being landfilled or used as secondary/supplementary raw materials. In this latter case, few studies have evaluated the incorporation of waste residues into magnesium potassium phosphate cements (MKPCs), mainly focussing on coal fly ash and grounded blast furnace slag (Gardner et al., 2015; Xu et al, 2017). They represent an example of chemically-bonded ceramics, in which the hardening occurs at room temperature through the acid-base aqueous reaction between an alkaline magnesia source (MgO) and a phosphate source (KDP, KH2PO4), according to the following chemical equation:

MgO + KH2PO4 + 5H2O → MgKPO4·6H2O (K-struvite)

This reaction is fast, exothermic and its mechanism has been described as a multi-step process (Viani et al., 2018). MKPCs are receiving increasing interest because of their excellent properties, namely high early age and long-term strengths, resistance to sulphate attack, rapid setting, near-neutral pH, low shrinkage (Xu et al, 2017). However, there are also some drawbacks, mainly related to the fast kinetics and expensive cost of the starting materials, since MgO needs to be calcinated at high temperature (at least 1500°C). The introduction of FA would be economically beneficial both by reducing the amount of MgO needed and providing a destination for a waste residue which otherwise would require important management costs.

In this work, the incorporation of washed MSWI-FA into MKPC is studied, paying major attention on how and in what extent MSWI-FA participates in the cement reaction. Indeed, an approach similar to the one adopted by Xu et al is employed, where the design strategy takes into account the reactivity of MSWI-FA. In particular, one formulation treats MSWI-FA as fully inert, replacing both magnesia and KDP, while in another one MSWI-FA is considered as fully reactive, thus replacing magnesia only. The obtained cement pastes are thoroughly characterized by employing spectroscopic (SSNMR, Zn K-edge XANES), X-ray diffraction, SEM-EDS and isocalorimetry techniques.

 

References

  • D. Bernasconi, C. Caviglia, E. Destefanis, A. Agostino, R. Boero, N. Marinoni, C. Bonadiman, A. Pavese. Influence of speciation distribution and particle size on heavy metal leaching from MSWI fly ash, Waste Management, 138 (2022), 318-327.
  • L.J. Gardner, S.A. Bernal, S.A. Walling, C.L. Corkhill, J.L. Provis, N.C. Hyatt. Characterisation of magnesium potassium phosphate cements blended with fly ash and ground granulated blast furnace slag, Cement and Concrete Research, 74 (2015), 78-87.
  • B. Xu, H. Ma, H. Shao, Z. Li, B. Lothenbach. Influence of fly ash on compressive strength and micro-characteristics of magnesium potassium phosphate cement mortars. Cement and Concrete Research, 99 (2017), 86-94.
  • A. Viani, P. Mácová. Polyamorphism and frustrated crystallization in the acid–base reaction of magnesium potassium phosphate cements, CrystEngComm, 20 (2018), 4600.

How to cite: Bernasconi, D., Viani, A., Zárybnická, L., Das, G., Borfecchia, E., Caviglia, C., Destefanis, E., Gobetto, R., and Pavese, A.: Investigation of Municipal Solid Waste Fly Ash Reactivity into Magnesium Phosphate Cement, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4460, https://doi.org/10.5194/egusphere-egu23-4460, 2023.

EGU23-5273 | Posters on site | ITS3.1/ERE4.7

MSWI fly ash steam washing, aimed to reach a condition of non-hazardous waste and to their possible reuse. 

Caterina Caviglia, Davide Bernasconi, Enrico Destefanis, Costanza Bonadiman, and Alessandro Pavese

Due to the high content of heavy metals and soluble salts, municipal solid waste incineration fly ash (MSWI FA) is classified as hazardous waste and its reuse is limited for their environmental risks. This work analyzes the steam washing application, to remove chlorides and heavy metals from MSWI FA, in order to reach a condition of non-hazardous waste, making them more suitable for stabilization as geopolymers or cement. The target of the steam application is both a sustainable and optimized utilization of water, to reduce the waste-water, and to take the advantage of the heat generation to dissolve most of the soluble salts; moreover, the steam is a resource that can be generated directly at the incineration plant. Steam washing experiments were performed under different conditions of flux and humidity, continuously monitored by sensors, keeping a low enthalpy steam (T< 100°C) for some cycles of washing; a vacuum pressure was applied to remove rapidly the superficial water in the washing chamber. Pre-treated (washed by water) samples of fly ash were also tested with steam washing for comparison. The steam washing was seen to be efficient in removing water-soluble chlorides including sodium chloride, potassium chloride, sulfates as well as heavy metals. The best efficiency of chlorides and sulfates removal was seen to be by 85%, using a steam flux of 2L/min and humidity of 40% v/v; while for heavy metals, like Cd, Zn, Pb the removal was up to 80% at the same conditions.

How to cite: Caviglia, C., Bernasconi, D., Destefanis, E., Bonadiman, C., and Pavese, A.: MSWI fly ash steam washing, aimed to reach a condition of non-hazardous waste and to their possible reuse., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5273, https://doi.org/10.5194/egusphere-egu23-5273, 2023.

EGU23-6595 | ECS | Posters on site | ITS3.1/ERE4.7

Strength performance of high-water content clays stabilized with cement and superabsorbent polymers 

Zhenhua Wang, Joachim Rohn, and Wei Xiang

An ideal solution for dealing with large volumes of waste clays is to stabilize and use them as fill materials for road construction. This paper presents an experimental study on the strength behavior of the clays with high water content stabilized by cement and superabsorbent polymers (SAP) at different curing periods. The SAP can effectively improve the strength of cement soils, and the increase in strength becomes more significant with time. The microstructures of the stabilized soils are also investigated via mercury intrusion porosimetry (MIP) and microcomputed tomography (Miro-CT). Comparison of the porosity and the pore size distribution of the stabilized soils shows clearly that the SAP facilitated the hydration/pozzolanic reaction through the absorption-release on free water. With this concept, free water, cement content, and curing period are considered as important parameters based on Abrams' law to characterize the strength of the cement-SAP-soil system.

How to cite: Wang, Z., Rohn, J., and Xiang, W.: Strength performance of high-water content clays stabilized with cement and superabsorbent polymers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6595, https://doi.org/10.5194/egusphere-egu23-6595, 2023.

The management and final disposal of waste containing radioactive elements is currently challenging in many countries due to the large volumes and their potential radiological risk. A promising alternative is the re-use to reduce the amount of waste to be disposed and to provide additional profit to the companies that generates this residue. This can be the case of fluorite sludge produced after the manufacturing of dicalcium phosphate. In this study, the initial stage of waste characterisation of fluorite sludge from two industrial sites, one active in Flix (NE Spain) and another one consisting of legacy ponds and stockpiles at El Hondón, in SE Spain, is reported. Fluorite sludge consists of 40-60% of CaF2, which precipitates during the reaction between fluorapatite (main component of phosphorite raw material) and HCl. This fluorite is very fine grained, with most particle sizes below 5 microns, and contains significant amounts of REEs, mainly Y, La, Ce and Nd, (0.2wt%, 800 ppm, 600 ppm and 300 respectively), especially in the sludge that precipitated in the reaction tanks. Concentration of the other REEs vary from 18 ppm to 167 ppm. Prices for the top grade REEs are high at the moment, and with time, as the reserves become scarcer, the prices will grow even more. Also, fluorite concentrate can be a valuable commodity. Taking into account the large amounts of disposed waste in both sites, and the concentrations of REEs, their recovery can be a great opportunity to reduce the amount of waste to be managed, and to provide new sources for these critical raw materials. So, current investigations are focused on cost-effective methodologies of fluorite separation and concentration and REEs extraction. 

How to cite: Grandia, F. and Plachciak, M.: Recovery of rare earth elements from fluorite sludges from dicalcium phosphate industry, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7985, https://doi.org/10.5194/egusphere-egu23-7985, 2023.

EGU23-8863 | Orals | ITS3.1/ERE4.7

Recycling of Nitrogen and Phosphorus with Bone Biochar and Biogas Digestates from Abattoir Residues 

Gerhard Soja, Anders Sörensen, Bernhard Drosg, Wolfgang Gabauer, Alexander Schumergruber, Gerald Dunst, Daniela Meitner, Elena Guillen, and Christoph Pfeifer

The by-products of abattoirs may become valuable resources for nutrient recycling and energy generation by including pyrolysis and biogas production in the value creation chain. This study investigated the potential of bone chars as sorbents for ammonium in order to produce a soil amendment useful for fertilizing purposes. Ammonium enriched from the digestate by membrane distillation or from pure ammonium sulphate solutions accommodated the nitrogen sorption to the bone chars. The plant availability of the sorbed nitrogen was studied by a standardized short-term plant test with rye (Secale cereale L.).

The results showed that ammonium, both from biogas digestate of the abattoir and from pure salt solutions, could be sorbed successfully to the bone chars post-pyrolysis and increased the nitrogen concentration of the chars (1.6±0.3 %) by 0.2-0.4 %. This additional nitrogen was desorbed easily and supported plant growth (+17 to +37 %) and plant nitrogen uptake (+19 to 74 %). The sorption of ammonium to the bone chars had a positive effect on the reversal of pure bone char phytotoxicity and on nitrogen availability. In summary, this study showed that abattoir wastes are useful pyrolysis input materials to produce bone chars and to use biogas digestates as ammonium source for nitrogen sorption to the chars. This innovation offers the possibility to produce nitrogen-enriched bone chars as a new type of fertilizer that upgrades the known value of bone char as phosphorus fertilizer by an additional nitrogen fertilizer effect. The study also shows that abattoirs, too, may become contributors to circular economy by facilitating the recovery of nitrogen and phosphorus.

How to cite: Soja, G., Sörensen, A., Drosg, B., Gabauer, W., Schumergruber, A., Dunst, G., Meitner, D., Guillen, E., and Pfeifer, C.: Recycling of Nitrogen and Phosphorus with Bone Biochar and Biogas Digestates from Abattoir Residues, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8863, https://doi.org/10.5194/egusphere-egu23-8863, 2023.

EGU23-10660 | ECS | Posters virtual | ITS3.1/ERE4.7

Analysis of variables for the modeling of aerobic processes on the treatment of the organic fraction of solid waste in megacities 

Ana Paola Becerra Quiroz, Johanna Karina Solano Meza, Maria Elena Rodrigo Clavero, and Javier Rodrigo Ilarri

The organic fraction of municipal solid waste (MSW) in megacities is usually managed by composting. In this technique the decomposition and stabilization of organic matter occurs under thermophilic conditions. Currently, composting systems range from simple garden piles and bins to highly engineered computer controlled mechanized processes. Composting is used worldwide, currently treating 5.5% of total urban solid waste. Therefore, modeling aerobic processes becomes important since it is the basis for determining the optimal conditions of the system and a fundamental tool to define its relevance and quantify environmental impacts.

However, biological processes such as composting require complex methods and specific software to predict the behavior of organic waste through mathematical models. In the case of the treatment of the organic fraction of urban solid waste, it is necessary to develop this type of models to enhance the recovery of the waste and determine the impacts associated with this technology. For this reason, modeling of organic waste processes is one of the priorities solid waste managing in megacities, where the development of technologies of greater complexity and magnitude is necessary due to the large population.

Success in determining feasibility in a predictive model is based on the parameter calibration process. Model results are dependent on the accuracy of the input variables and the way in which the collection and statistical treatment of the information is be carried out. Despite this need, the information associated with the management of solid waste in megacities is often scarce and incomplete. This is usually due to the poor information systems available in many countries for recording all the stages involved in MSW management.

Therefore, this research seeks the determination and standardization of the variables required for the mathematical modeling of aerobic processes of the organic fraction of solid waste in megacities. The proposal includes the definition of technical but also environmental, social, economic, administrative and financial variables for the case study of the megacity of Bogotá (Colombia).

How to cite: Becerra Quiroz, A. P., Solano Meza, J. K., Rodrigo Clavero, M. E., and Rodrigo Ilarri, J.: Analysis of variables for the modeling of aerobic processes on the treatment of the organic fraction of solid waste in megacities, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10660, https://doi.org/10.5194/egusphere-egu23-10660, 2023.

Within the rural electrification literature, only a few studies make remarks on the relation between the concept of circular economy and the effects of electricity in these marginalised communities. In contrast, most electrification studies describe the marginalised nature of the rural contexts in the Global South, leaving the dialogue about efficient technologies and economic models typical of CE literature outside their main discussion. The few articles to mention circularity seem to adopt a vision similar to the Global North, reproducing thoughts on the need to implement more efficient technologies, effective policies and financing schemes to promote the "sharing economy", yet under an overwhelming number of difficulties for its implementation [1, 2]. However, there is also a literature critical of CE primarily inside the Global North, which argues that circularity emerges as a theoretically, practically and ideologically questionable notion [3, 4]. These analyses argue that although some initiatives may lead to the decoupling of economic growth from resource extraction, it does not necessarily mean reducing the extraction rate or, for practical use, meeting environmental needs. It is also reasoned that CE can create an inevitable accumulation of individual wealth and exacerbate the informal economy and the precariousness of work [4, 5]. Nevertheless, few reflections on CE and community development emerge from the circumstances of marginalised communities in the global south [6]. Hence, there is not enough evidence to refute or support the idea that the circular economy can meet social and environmental goals compatible with the development needs in these contexts. The aim of this research is to discuss aspects of circularity in the perspective of marginalised communities without electrification in Southeast Asia. Building upon previous analyses of changes in daily activities experienced from introducing renewable solar systems in 2019-2022, we will address how compatible CE notions could be to promote sustainable development in rural communities in The Philippines and Malaysia and the relevance of the raised criticisms to CE. The investigation will be based on the analysis of interviews with members of the community.

References:

[1] Desmond, P., & Asamba, M. (2019). Accelerating the transition to a circular economy in Africa: Case studies from Kenya and South Africa. In The Circular Economy and the Global South (pp. 152-172). Routledge.

[2] Bhattacharyya, S. C., & Palit, D. (2016). Mini-grid based off-grid electrification to enhance electricity access in developing countries: What policies may be required?. Energy Policy94, 166-178.

[3] Corvellec, H., Stowell, A. F., & Johansson, N. (2022). Critiques of the circular economy. Journal of Industrial Ecology26(2), 421-432.

[4] Hart, J., & Pomponi, F. (2021). A circular economy: where will it take us?. Circular Economy and Sustainability1(1), 127-141.

[5] Fevrier, K. (2022). Informal Waste Recycling Economies in the Global South and the Chimera of Green Capitalism. Antipode.

[6] Kinally, C., Antonanzas-Torres, F., Podd, F., & Gallego-Schmid, A. (2022). Off-grid solar waste in sub-Saharan Africa: Market dynamics, barriers to sustainability, and circular economy solutions. Energy for Sustainable Development70, 415-429.

How to cite: Cravioto, J. and Ohgaki, H.: Can the circular economy be relevant for rural development? Insights from communities without electricity in South-East Asia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11487, https://doi.org/10.5194/egusphere-egu23-11487, 2023.

EGU23-12298 | Orals | ITS3.1/ERE4.7

How can agile sensing improve recycling stream characterisation and monitoring for e-waste? - news from the HELIOS lab 

Margret C. Fuchs, Sandra Lorenz, Yuleika C. Madriz Diaz, Titus Abend, Junaidh Shaik Fareedh, Andrea de Lima Ribeiro, Elias Arbash, Behnood Rasti, Jan Beyer, Christian Röder, Nadine Schüler, Kay Dornich, Johannes Heitmann, and Richard Gloaguen

Increasing volumes of electrical and electronic waste (e-waste) demand for innovative and efficient recycling solutions to keep materials in the process/recovery loop. The recovery percentage and quality of resulting recycling products depend fundamentally on the ability to accurately identify the constituents of the e-waste stream. Traditionally, recycling is based on sequential enrichment of target components and reduction of hazardous substances with random sampling from an assumed homogeneous mass. E-waste represents in this context a highly heterogeneous, complex waste composed of a variety of different compounds required to meet the high diversity of functional requirements. Tailored sensor-systems can achieve a successful extraction of several target materials such as precious metals or specific polymers, but reach their limits for many low concentrated, critical raw materials. Hazardous substances and additives (e.g. dark pigments in polymers, poisonous oxides) are difficult to remove from the stream and induce risks of down-cycling, quality loss and reduced acceptance of recycling products. 

HELIOS lab is an agile solution for non-invasive sensing applied to complex recycling streams such as e-waste suited for conveyor belt operations. We employ hyperspectral imaging technology for the fast and spatially resolved acquisition of information associated with physical material properties. Multiple cameras allow for combining reflectance information from the visible to midwave-infrared wavelengths range to differentiate material classes. Fast data processing routines then allow for generating first order material maps. Such maps suffice for well defined, relatively homogeneous material streams but not  for a precise and accurate sorting and process monitoring. For efficient e-waste recycling, further information is required to enhance the component identification, particularly for certain critical raw materials and complex compounds. We suggest additional validation cycles to refine the initial mapping. Several sensors traditionally used for bulk measurements deliver the solution for detailed point validation. Here, Raman spectroscopy, XRF and LIBS provide the needed complementary data for the identification of a wide range of critical raw materials and hazardous e-waste components. Additionally, our in-house developed laser-induced fluorescence (LiF) system contributes a scanning solution for rare-earth element mapping. However, those validation sensors are very sensitive to signal integration times, power and focus distances. We showcase two examples for a combination of Raman spectroscopy and LiF with hyperspectral imaging technology to extract meaningful information from typical e-waste streams such as printed circuit boards and electrolysers in a conveyor belt setting. We discuss the main challenges and give an outlook on additional development needs that we will address in our HELIOS lab in the frame of the EU funded projects RAMSES and inSPECtor (EIT RawMaterials), and the BMBF funded projects High-speed imaging, InfraDatRec, Digisort and H2Giga.




How to cite: Fuchs, M. C., Lorenz, S., Madriz Diaz, Y. C., Abend, T., Shaik Fareedh, J., de Lima Ribeiro, A., Arbash, E., Rasti, B., Beyer, J., Röder, C., Schüler, N., Dornich, K., Heitmann, J., and Gloaguen, R.: How can agile sensing improve recycling stream characterisation and monitoring for e-waste? - news from the HELIOS lab, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12298, https://doi.org/10.5194/egusphere-egu23-12298, 2023.

EGU23-12409 | Posters virtual | ITS3.1/ERE4.7

A naturally circular fibre: Sheep wool as a tool for assessing human and environmental exposure 

Sara Bortolu, Emanuela Azara, and Pierpaolo Duce

In the context of the Circular Economy, the enhancement of raw wool in new bioproducts represents an important challenge. Wool is the main by-product of sheep, although its production has decreased largely during the last decades. In addition, wools with coarse fiber diameter have little economic value since they are not adequate to be used in the textile sector and, when not transformed, wool needs to be treated as a special waste.

Wool is by its nature a circular fiber. Due to its complex chemical composition, physical structure and mechanical properties, it represents a biodegradable renewable resource and can find various value-added applications beyond the textile industry. The technological characteristics make wool particularly suitable for different applications such as thermo-acoustic insulation, agricultural amendment, biomedical polymers, etc.

Furthermore, it absorbs harmful pollutants, becoming a specific chemical indicator. In fact, it has been shown that wool fibers are good bio-indicators of the environmental status (soil, water and air pollution). The concentration of pollutants reflects either the feed and nutrition quality and the general health status of sheep as well as the climatic and environmental conditions. The sustainable and innovative alternative uses of this livestock waste could reduce and minimise keratinous waste disposal, reduce environmental impact and increase commercial process sustainability and circular economy.

The aim of this research was to investigate the degree of contamination of Sarda sheep wool to understand if wool fiber can be a contamination source for both the environment and human health.

Chemical analyses were carried out through Liquid chromatography Orbitrap mass spectrometry and Inductively coupled plasma mass spectrometry. Both analytical techniques were targeted for a wide range of micropollutants including pesticides, veterinary drugs and heavy metals. The results obtained in this study represent the first step for developing a new wool valorization chain.

Wool analysis can be an important strategy for the biomonitoring of human exposure to pesticides and for evaluating the quality of wool-based products.

How to cite: Bortolu, S., Azara, E., and Duce, P.: A naturally circular fibre: Sheep wool as a tool for assessing human and environmental exposure, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12409, https://doi.org/10.5194/egusphere-egu23-12409, 2023.

EGU23-12643 | ECS | Orals | ITS3.1/ERE4.7

Potential of optical sensors for polymer type identification in e-waste recycling streams 

Andréa de Lima Ribeiro, Margret Fuchs, Christian Röder, Nadine Schüler, Sandra Lorenz, Yang Xiao Sheng, Johannes Heitmann, Kay Dornich, and Richard Gloaguen

Plastics are major components of waste from electrical and electronic equipment (WEEE, or e-waste) accounting for up to 25% of annual e-waste production. The composition of such plastics varies greatly according to their original function in the electrical and electronic equipment, and may include additives such as dark pigments and brominated compounds. With WEEE becoming the fastest growing waste stream in recent years, the recycling of polymers became a keystone for waste management and closing material loops. Closing the loops in material life cycles requires that type-pure plastics are obtained at the end of the recycling chain. Accordingly, the identification of polymers prior to their sorting in recycling lines is a fundamental prerequisite.

Here, we explore how an innovative combination of optical sensors can aid the identification of plastics in the plastic recycling environment in order to increase recovery rates and quality of recyclates.

We have selected 23 different polymer samples, representative of the plastic types commonly found in e-waste. We investigated the sequential use of high-speed hyperspectral imaging (HSI) and Raman spectroscopic sensors for digitalization of the waste stream and identification of polymer composition. HSI-reflectance sensors in the short-wave infrared (HSI-SWIR, Specim AisaFenix, 970 - 2500 nm) domain acquired simultaneously spatial and spectral information, allowing for mapping and initial identification of certain transparent and light-coloured polymers (PE, PP, PET, and PC). Raman measurements, collected at specific points and with integration times < 2 seconds, allowed for specific identification of all polymer samples, including black plastics. The use of both sensor technologies on conveyor belts has the potential to fully characterise the WEEE plastics stream, generating identification signals serving as input for sorting machines or simulation models. The combination of latest high-speed sensors and data processing opens many further fields of material stream characterisation and monitoring, which come with high data acquisition rates and volumes. 

Consequently, a smart selection of sensors along with a tailored and learning data processing will be key to innovations towards more complex and agile recycling processes. In this context, our multi-sensor solution focuses on a combination of advantages from HSI and Raman spectroscopy aided by efficient data integration (‘RAMSES-4-CE’ project, supported by the EU EIT Raw Materials).

 
 

 

 

How to cite: de Lima Ribeiro, A., Fuchs, M., Röder, C., Schüler, N., Lorenz, S., Sheng, Y. X., Heitmann, J., Dornich, K., and Gloaguen, R.: Potential of optical sensors for polymer type identification in e-waste recycling streams, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12643, https://doi.org/10.5194/egusphere-egu23-12643, 2023.

EGU23-13238 | Posters on site | ITS3.1/ERE4.7

Leachability of elements in municipal, sewage sludge and industrial incineration ashes using a sequential extraction method 

Monika Kasina, Kinga Jarosz, Yingzun He, and Nhung Phan

A stable supply of raw materials required for industrial development and production of everyday goods is one of the major challenges for economies nowadays. EU countries are highly dependent on supplies which currently are extracted in only a few countries worldwide. It is also expected that the prices of industrially important raw materials will fluctuate, depending on the supplier policies. Growing concerns of mineral resources supplies on one hand, and the sustainable economy, where protection of natural resources is one of the key goals on the other hand, force us to search for alternative sources of economically important elements. For this reason, waste stream materials: municipal waste incineration ashes, sewage sludge incineration ashes and industrial incineration ashes were studied. The rational use of incineration wastes as a source of economically important materials requires detailed mineralogical and chemical characterization and evaluation of their recovery and leaching potential since they might contain both, important and potentially toxic for the environment elements. To maximize the extraction rates of valuable elements such as phosphorus and/or to minimize the leachability of potentially hazardous elements (e.g. As, Cr, Cd, Cu, Pb, Zn) a three-step sequential extraction procedure in accordance with the Community Bureau of Reference (BCR; Standards, Measurements and Testing Program) was implemented to characterize the content of trace elements and heavy metals, bonds and potential bioavailability of studied ashes. Leachates were analyzed using ICP methods. Mineralogical methods (XRD and SEM-EDS) were applied to study the composition of starting materials and post extraction solid samples. Efficiency of the proposed extraction method was strongly dependent on incineration technology, types of incinerated waste, bulk chemical composition and mineralogy of ashes that influenced their solubility and thus leaching efficacy.

Acknowledgment. This publication has been funded from the Anthropocene Priority Research Area budget under the program "Excellence Initiative – Research University" at the Jagiellonian University.

How to cite: Kasina, M., Jarosz, K., He, Y., and Phan, N.: Leachability of elements in municipal, sewage sludge and industrial incineration ashes using a sequential extraction method, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13238, https://doi.org/10.5194/egusphere-egu23-13238, 2023.

EGU23-14734 | ECS | Posters on site | ITS3.1/ERE4.7

How to power an off-grid telescope? Comparative life cycle analysis of renewable-based energy systems 

Isabelle Viole, Guillermo Valenzuela Venegas, Li Shen, Luis Ramirez Camargo, and Sabrina Sartori

A new radio telescope in the Atacama desert, Chile, is currently under design and envisaged to be powered by an off-grid energy system of photovoltaic arrays during the day-time and a hybrid energy storage system for non-sunny hours. Similar isolated solar energy systems employ Lithium-ion or Lead-acid batteries as storage, which either increase the pressure on critical materials like lithium and cobalt or contain lead which mining brings a set of harmful environmental impacts. Hydrides based on intermetallic compounds are emerging as a viable solution for energy storage in stationary applications and are particularly appealing due to their abundance and non-toxicity. Here, by developing a multi-objective techno-environmental optimization, we size a power system that can fuel the telescope’s demand economically while also maintaining a low life cycle carbon footprint. The optimization includes life cycle inventory data of potential components next to costs, including monocrystalline photovoltaic arrays, lithium-ion batteries, hydrogen storage in metal hydrides and as compressed gas, alkaline electrolyzers, PEM fuel cells and diesel generators.

Pure techno-economical optimization without life-cycle inventory optimizes towards power systems with up to 32% of curtailed photovoltaic power. Levelized costs of electricity resulted in $120/MWh with photovoltaics, hybrid storage systems and diesel generators as a backup, and $140/MWh for systems relying on solely batteries and photovoltaics. With our optimization, we propose a system resulting in a low life cycle carbon footprint and acceptable electricity prices, analyzing indirect carbon emissions of the stationary system as well as costs.

The life-cycle carbon footprint optimization performed allows both the remote telescope in question and other off-grid energy systems to make informed decisions on sustainable solutions to fuel their power needs.

How to cite: Viole, I., Valenzuela Venegas, G., Shen, L., Ramirez Camargo, L., and Sartori, S.: How to power an off-grid telescope? Comparative life cycle analysis of renewable-based energy systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14734, https://doi.org/10.5194/egusphere-egu23-14734, 2023.

EGU23-14785 | Orals | ITS3.1/ERE4.7

Bioleaching by endophytic microorganisms as a method of element recovery from sewage sludge incineration ash 

Kinga Jarosz, Monika Kasina, Piotr Rozpądek, and Rafał Ważny
 

Bioleaching by endophytic microorganisms as a method of element recovery from sewage sludge incineration ash 

Incinerated sewage sludge ash (ISSA) has been proven to have resource potential, and in case of some elements, such as phosphorus, in the same concentration range as currently exploited ores. Usage of waste resources, such as ISSA, to recover valuable elements together with the efficient methods are main assumption for sustainable development. Alongside feasibility, economic, energetic and environmental cost of methods applied have to be taken into consideration.  

The effective alternative methods to chemical treatment to recover elements form ISSA that simultaneously lower the negative impact of chemical reagents are biological methods. Microorganisms based solutions, even though described, have still underexplored potential in the field of element recovery. One of the reasons for this state is a limited range of species of microorganisms used for this purpose up to date.  

In present study bacteria and fungi, capable of phosphorus and metal containing phase solubilization, were employed in bioleaching of ISSA. microorganisms have been shown to be both effective in compound transformation as well as resilient in high pH environment – characteristic for ISSA water mixtures. The course and efficiency of bioleaching was determined by the means of ICP methods. The chemical composition of ISSA, leachates, and the post-reaction residues were examined. Moreover, direct observation of interactions between the fungi and the ash was made by SEM-EDS. 

Apart from element recovery, both in case of use of ISSA for fertilization or for any other use (e.g. as an additive to cement), the toxicity of the ash must be examined and reduced.  

The course and effect of ISSA bioleaching by microorganisms was described. The study confirmed that phosphorus extraction as well as chemical neutralization of ash can be achieved using microorganism based bioleaching methods. 

Acknowledgments:  

This publication has been funded from the Anthropocene Priority Research Area budget under the program "Excellence Initiative – Research University" at the Jagiellonian University”.  

This publication has been financed by Opus 17 Project 2019/33/B/NZ9/01372 

How to cite: Jarosz, K., Kasina, M., Rozpądek, P., and Ważny, R.: Bioleaching by endophytic microorganisms as a method of element recovery from sewage sludge incineration ash, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14785, https://doi.org/10.5194/egusphere-egu23-14785, 2023.

ERE5 – Process coupling and monitoring related to geoenergy applications

EGU23-1341 | Orals | ERE5.1

Uncovering the Processes that Control Induced Earthquake Sequences 

Elizabeth Cochran, Kayla Kroll, Morgan Page, Zachary Ross, and Justin Rubinstein

Earthquake sequences induced by fluid disposal into the subsurface show strong variability in their magnitude distributions and clustering behavior. We attempt to untangle the processes that control the occurrence and evolution of disposal-induced earthquake sequences by integrating detailed seismicity observations, pore pressure modeling, and 3D physics-based earthquake simulations. Observations of earthquake sequences in Oklahoma and Kansas include some sequences that have near-Poissonian distribution of interevent times and robust foreshock sequences, while other sequences display more typical mainshock-aftershock clustering behavior. Pore-pressure modeling shows that these behaviors correlate with the amplitude of the pore-pressure changes. Close to disposal wells where pore pressure changes are high, seismicity is controlled by both diffusion and earthquake stress interactions. Farther from the wells where pore pressure changes are lower, seismicity appears driven primarily by stress interactions. We further explore the stress and fault conditions that may allow for these diverse behaviors using an earthquake simulator, RSQSim. We find that the maximum magnitude of the triggered events depends strongly on the pre-existing stress on the fault. The roughness, distribution, and background stress state of pre-existing primary and secondary faults also likely influence the sequence behavior and is an area of ongoing work.  

How to cite: Cochran, E., Kroll, K., Page, M., Ross, Z., and Rubinstein, J.: Uncovering the Processes that Control Induced Earthquake Sequences, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1341, https://doi.org/10.5194/egusphere-egu23-1341, 2023.

Faults slip in response to changes in stress or fluid pressure, and these changes can be natural or anthropogenic. Estimating the likelihood of fault slip for a given change in loading is critical for safe geological storage and energy extraction in faulted rocks, as well as effective communication of risks to policy makers and the public. The energy transition and decarbonization are urgent and essential tasks: we will only be successful if we manage to balance public perceptions of risk with the technical challenges inherent to the exploitation of faulted rock. To accomplish both, we need to do a better job of quantifying the uncertainties in our mechanical and geometrical data. 

Measures of fault stability include slip (Ts) and dilation (Td) tendency, and fracture susceptibility (Sf, the change in fluid pressure to push effective stress to failure). The input values for any of these measures are always uncertain, and they are uncertain to varying degrees. For example, while the vertical stress can be well constrained from wireline density log data, the maximum horizontal stress is generally much harder to quantify from any source.

Probabilistic models of fault stability for the Mississippian (Lower Carboniferous) Limestone underlying much of northern England are presented. This is an undrilled target for geothermal energy. Fault maps are derived from published geological maps and recently reprocessed seismic reflection data. Stress and pressure constraints are derived from legacy onshore hydrocarbon wells and wireline logs. Coefficients of friction and cohesive strength remain poorly constrained, not only in terms of their magnitude, but critically in the shapes of their statistical distributions. In addition, the applicability of simplified indices of fault stability (Ts, Td, Sf) to complex natural fault zones is questionable, and our predictions could be improved through weighting by information derived from long-term seismological records.  

This contribution raises two key points: 1) Laboratory data rarely include repeat measurements from quasi-identical samples of the same rock, and therefore the statistical distributions of friction or cohesion are poorly known. This is important because skewed distributions – and the direction of that skewness (high or low) – can significantly affect predictions of fault stability; 2) What is the best way to weight the calculated probability of slip in complex natural fault zones to account for geometrical weakening? Specifically, is total fault length more or less important than fault smoothness (roughness)?

How to cite: Healy, D. and Hollis, C.: A probabilistic assessment of induced seismicity and fluid flow in the Carboniferous Limestone of northwest England: Implications for geothermal energy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2798, https://doi.org/10.5194/egusphere-egu23-2798, 2023.

EGU23-3100 | ECS | Orals | ERE5.1

Triggering Mechanisms of Post-Injection Induced Seismicity Using The Enhanced Geothermal System of Basel (Switzerland) 

Auregan Boyet, Silvia De Simone, Shemin Ge, and Victor Vilarrasa

Induced seismicity is a limiting factor in the widespread deployment of Enhanced Geothermal Systems (EGS). Induced seismicity occurs not only during injection, but also after the stop of injection, with the largest magnitude earthquakes usually occurring after the stop of injection at different scales of time (hours to months). The post-injection large magnitude seismicity is counterintuitive and is still not well understood. Multiple mechanisms have been identified as triggering induced seismicity in EGS systems. Pore pressure increase due to fluid injection is the most commonly accepted triggering mechanism to explain induced seismicity. Yet, coupled poromechanical effects and static stress transfer are also important mechanisms in the process of fault reactivation. We study the combination of these different mechanisms by simulating coupled hydromechanical processes of the Deep Heat Mining Project at Basel, Switzerland (2006), a well-known case of short-term post-injection large-magnitude seismicity. We apply the material characteristics and stress conditions of the site to a simplified 2-dimensional fault network that is based on the monitored seismic events. In our model, pore pressure has a dominant effect on the triggering of the seismicity in the vicinity of the injection well, but its effect decreases away from the well as static stress transfer and poroelastic stressing gain importance. Poroelastic stress can have a stabilizing effect when its direction is opposite to the fault slipping orientation; but an abrupt shut-in, and consequently a quick poroelastic relaxation, reactivates the fault soon after the shut-in. Later post-injection induced seismicity is partially due to the post-injection diffusion of the pore pressure, but is mainly induced by constant static stress redistribution from reactivations of the different faults of the domain. Understanding the processes inducing seismicity, and especially the post-injection large-magnitude seismicity, should enable developing better strategies of shut-in to mitigate the risks of post-injection large-magnitude seismic events.

How to cite: Boyet, A., De Simone, S., Ge, S., and Vilarrasa, V.: Triggering Mechanisms of Post-Injection Induced Seismicity Using The Enhanced Geothermal System of Basel (Switzerland), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3100, https://doi.org/10.5194/egusphere-egu23-3100, 2023.

EGU23-4577 | Posters on site | ERE5.1

CO2 fracturing simulation and reservoir simulation case study in the Liard Basin of Canada 

Taehun Lee and Taewoong Ahn

Hydraulic fracturing and horizontal drilling technology had contributed to the commercial shale gas production. However, hydraulic fracturing requires a water for the drilling fluids. Many countries have shale gas fields and are water stress country such as China. CO2 fracturing have many advantages than water fracturing. One is that CO2 gas is a greenhouse gas. The other is that SRV of the CO2 fracturing is much larger than that of the  water fracturing due to the low viscosity of CO2 gas. Devonian age Besa River shale gas play in the Liard Basin of northeastern BC with net estimated sales gas of 48 TCF over an area of 430,000 acres. We have conducted many case studies about CO2 fracturing simulation and reservoir simulation in the shale gas of Liard basin. In order to study, mechanical earth model was constructed. From this case study, we designed optimum fracturing pattern and development plan.

How to cite: Lee, T. and Ahn, T.: CO2 fracturing simulation and reservoir simulation case study in the Liard Basin of Canada, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4577, https://doi.org/10.5194/egusphere-egu23-4577, 2023.

Riedel shear structures (RSS) are often observed in the embryonic stage of strike-slip fault development. Typical RSS often involve a set of conjugated fault segments that interact with each other prior to the growth of a through-going fault, that is, the principal deformation zone (PDZ), sub-structures R, R’ and P. Ideally, sub-structures R and P should be symmetric to the PDZ while structures R and R′ are conjugated to each other. It is a critical concept linking the geomechanical behavior of individual earthquakes to structural geology at both local and regional scales. The depiction of RSS can help understand the geomechanical behavior of individual earthquakes. In the meantime, the influence of long-term fluid injections on the developing process of RSS, as manifested by the common occurrences of injection-induced earthquakes, has been rarely addressed.

 

Here we document a clear case in western Canada where the development of a local RSS system is expedited by 25 years of wastewater injection. RSS are manifested by an earthquake sequence consisting of 187 events (ML ranging 1.3–3.9) between 2018/01/01 and 2021/07/15 in an area without any previous seismic history.

 

Focal mechanisms of these events exhibit various faulting types with the majority (87%) being compatible with the background stress regime. The orientation of derived nodal planes and six fault segments depicted from the refined earthquake distribution collectively define the overall geometrical characteristics of RSS, which consists of four primary strike-slip structures striking 19º (R’), 79º (R), 94º (PDZ) and 109º (P), respectively. Mohr-Coulomb failure analysis further suggests a cumulative stress perturbation of up to 10.0 MPa, probably bringing the local structures very close to the critically stressed state.

 

Overall, our observations suggest that long-term fluid injection can expedite the development of local fault systems. Consequently, it is probably necessary to consider the full dimension of the local/regional RSS rather than the size of individual events in the assessment of the overall injection-induced seismic hazard.

 

How to cite: Yu, H., Kao, H., Wang, B., and Visser, R.: Long-term Fluid Injection Can Expedite Fault Development: Riedel Shear Structures Illuminated by Induced Earthquakes in Alberta, Canada, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4598, https://doi.org/10.5194/egusphere-egu23-4598, 2023.

On 14 July 2013, a deep geothermal drilling project close to the city of St Gallen, in Switzerland was initiated with the aim of producing electricity and heating. The target of the project was a fractured carbonate aquifer at a depth of 4 km b.s.l.. The project started with a stimulation phase on 14 July 2013 that produced only microseismicity. From 14 July 2013 through 19 July 2013 acid stimulations involving about 290 m3 of fluids broke the seal to a gas reservoir and caused a gas kick. Afterwards, well control operations were done by injecting ~700 m3 of water and heavier liquids, which probably induced the largest event in the sequence with ML 3.5. Well-control operations ended on 24 July 2013. In September 2013 fishing operations (that is removing lost or stuck objects from the wellbore) were done together with a cleaning of the well. A total of 346 earthquakes were recorded from July 2013 to October 2013 at the seismic network managed by the Swiss Seismological Service (SED). The events occurred at depths up to 4.2 km with ML between -1.2 and 3.5.

We infer seismic source parameters by using both a single-event approach and an empirical Green’s function (EGF) approach. This latter method helps to limit the spectral source parameters trade-off and to infer source parameters for the smaller earthquakes (ML  2.0). In fact, performing the ratio between the spectra of co-located events recorded at the same stations allows to remove propagation and site effects. For the larger events (ML>2.0), we use an iterative single-event approach where Q is fixed to avoid the trade-off with fc. Specifically, the QP and QS values are obtained from the slope of the displacement spectra - at frequencies lower than the expected corner frequency - of the smaller events. In order to apply the EGF approach, for each of the smaller earthquakes, we select among the larger events those for which the cross-correlation in the time domain is higher than a given threshold. Next, for the selected couples we compute the spectral ratio and infer the seismic moments' ratio and the corner frequency ratios by using a grid-searching technique. We find self-similar parameters scaling down to Mo=1010 Nm and an average static stress drop of 0.1 MPa. The mean value of seismic efficiency, estimated from the average apparent stress to static stress drop ratios is 0.05 suggesting an overshoot dynamic weakening mechanism.

This work has been supported by PRIN-2017 MATISSE project (No. 20177EPPN2), funded by Italian Ministry of Education and Research.

How to cite: Convertito, V. and De Matteis, R.: Unravelling kinematic source parameters of induced earthquakes at St Gallen geothermal field, Switzerland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5768, https://doi.org/10.5194/egusphere-egu23-5768, 2023.

EGU23-7498 | Posters on site | ERE5.1

Deriving the triggering potential in the Lower Rhine Embayment using background seismicity near Weisweiler, Germany 

Marco Pascal Roth, Rebecca M Harrington, Brigitte Knapmeyer-Endrun, Claudia Finger, and Marco Dietl

The Earth’s crust is permeated with faults and fractures due to its long tectonic history. Faults and fractures not only act as zones of weakness but can increase permeability and act as conduits to circulate fluids in the underground, making them ideally suited for geothermal energy production. However, human-induced changes to in-situ pressure fields have a documented history of leading to fault (re-)activation in the form of earthquakes (seismic slip) or aseismic slip that does not generate measurable ground motion.

This study aims to quantify the current background earthquake activity, the spatiotemporal relationship to the seismotectonic setting, and the remote earthquake-earthquake triggering propensity in the Lower Rhine Embayment (LRE) in western North-Rhine Westphalia. The study area is targeted for extensive exploration activities focused on geothermal energy production. While regional mean slip rates do not exceed 0.1 mm/yr, paleo-seismic studies suggest that the normal faulting system has hosted a series of ~14 earthquakes of Mw > 5.0 since the 14th century, including the 1992 Mw 5.3 Roermond earthquake. Therefore, estimating background seismicity rates independent of anthropogenic stress perturbation is one important element in developing strategies to minimize the probability of felt earthquakes caused by industrial activity. 

We evaluate waveform data from a temporary deployment of 48 seismic stations operating between July 2021 and May 2022 in a radius of roughly 10 km around a future exploration well drilling site in Weisweiler. We implement a machine learning-based earthquake detection algorithm, SeisBench, to detect earthquakes and denoise the continuous seismic waveforms (DeepDenoiser), estimate P- and S-phase arrivals (PhaseNet and Generalised Phase Detection; GPD), and associate earthquake phases using a Bayesian Gaussian mixture model (GaMMA). We locate 81 local earthquakes to complement the 14 recorded in the Earthquake Observatory Bensberg (BNS) catalog for a total of 95 seismic events recorded between July 2021 and December 2021 with magnitudes ranging from 0 < ML < 1.3. In addition, we use the continuous BNS catalog to evaluate the dynamic triggering potential in the LRE starting in 1990. We select 20 teleseismic mainshocks with M > 6 (1990 – 2015) and M > 7 (2016 – present), as well as the 1992 Roermond Mw 5.3 due to the high amplitude shaking it caused within the study area. Preliminary remote dynamic triggering results suggest that the passing surface waves of the July 2021 M 8.2 Chignik, Alaska earthquake may have triggered a seismic sequence of about 16 locatable earthquakes. The migrating aftershock sequence of the Roermond earthquake also suggests the mainshock caused limited dynamic triggering within the study area, which lies outside of the classical aftershock zone of ~2-3 fault lengths.

How to cite: Roth, M. P., Harrington, R. M., Knapmeyer-Endrun, B., Finger, C., and Dietl, M.: Deriving the triggering potential in the Lower Rhine Embayment using background seismicity near Weisweiler, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7498, https://doi.org/10.5194/egusphere-egu23-7498, 2023.

EGU23-8515 | ECS | Posters on site | ERE5.1

The effect of steady-state flow on induced stresses along displaced faults 

Pavan Cornelissen and Jan Dirk Jansen

Pore pressure changes due to fluid injection or withdrawal alter the rock stresses, which may potentially induce seismic events. Activities that have been associated with induced seismicity include geothermal energy production, subsurface gas storage, and natural gas production. Physics-based models are required to gain insight in the processes that lead to induced seismicity. When computing induced stresses with such models, a commonly made simplification is the assumption of uniform pressure changes across the entire reservoir. In reality, pressure gradients arise due to fluid production or injection. Here, we assess the effect of non-uniform pressure fields under steady-state flow conditions on induced stresses. We employ (semi-)analytical techniques to compute the corresponding pressure field and fault stresses. We are particularly interested in reservoirs with displaced faults (i.e., cases with nonzero fault offset), as shear stresses tend to concentrate at the reservoir corners along the faults. The stress profile along the fault becomes asymmetric under steady-state flow. The effect of fluid flow on fault stresses is larger in case of injection than in case of depletion. Injection with up-dip flow results in increased zones of fault slip near the bottom of the reservoir, while injection with down-dip flow results in increased slip near the top of the reservoir. The significance of steady-state flow on induced stresses can be estimated from the ratio of the average pressure change along the fault and the applied pressure gradient. The effect of steady-state flow is most relevant at the start of production or injection and diminishes with time. Thus, the effect of steady-state flow is only expected to be relevant when initially critically stressed faults are present. For non-critically stressed faults, the assumption of uniform depletion or injection is expected to be reasonable. An order-of-magnitude estimate of the effect of steady-state flow across displaced faults in the Groningen natural gas reservoir shows that the effect on fault stresses is probably negligible. A similar estimate of the effect in typical low-enthalpy geothermal doublets indicates that steady-state flow may possibly play a small role, in particular close to the injector. Nevertheless, site-specific assessments are necessary to quantify the effect in greater detail.

How to cite: Cornelissen, P. and Jansen, J. D.: The effect of steady-state flow on induced stresses along displaced faults, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8515, https://doi.org/10.5194/egusphere-egu23-8515, 2023.

EGU23-8557 | ECS | Posters on site | ERE5.1

Quantification of pre-operational seismic hazard of deep geothermal systems exemplified in the greater Ruhr region (Germany) 

Michal Kruszewski, Alessandro Verdecchia, Oliver Heidbach, Rebecca M. Harrington, and David Healy

In 2018, after more than 700 years, the last black coal mine ceased operation in the greater Ruhr region in western Germany. In addition to the repurposing of the unused subsurface infrastructure for heat storage projects, the utilization of deep geothermal resources, located below mining levels in the Devonian Massenkalk formations, is the most promising way of facilitating the green energy transition in this highly populated region. The operation of fluid injection or withdrawal during geothermal production alters subsurface stress and poses questions about the possible reactivation of faults in the greater Ruhr region, with strong implications for seismic hazard potential. Deep geothermal resources depend on permeable pathways (i.e., fault zones and fracture networks) in the subsurface, which are known to have certain intrinsic pre-operational seismic hazard. In this study, we evaluate the probability of reactivation (using the so-called slip tendency and fracture susceptibility indicators) and dilation tendency of major faults accounting for uncertainties of in situ stress conditions, fault geometries, and frictional properties. Furthermore, we investigate the spatio-temporal evolution of the slip tendency of a major fault in the region during geothermal operations utilizing coupled thermo-hydro-mechanical numerical models. This study benefits from a recently published in situ stress database of the greater Ruhr region derived from 429 hydrofracturing tests performed across several coal mines. The assessment of fault reactivation utilizing probabilistic and coupled numerical modelling approaches, as presented in this study, aims at de-risking the exploration of deep geothermal systems in the greater Ruhr region and can hopefully serve as an example for quantification of pre-operational seismic hazards in other regions. Based on preliminary results, we find that the NW-SE striking faults are much more prone to reactivation, in comparison to the NE-SW ones, which are oriented unfavorably under prevailing stress conditions. We also find that thermal stress contributes significantly to fault stability, especially during long-term geothermal production.

How to cite: Kruszewski, M., Verdecchia, A., Heidbach, O., Harrington, R. M., and Healy, D.: Quantification of pre-operational seismic hazard of deep geothermal systems exemplified in the greater Ruhr region (Germany), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8557, https://doi.org/10.5194/egusphere-egu23-8557, 2023.

EGU23-9584 | ECS | Orals | ERE5.1

Research on the Mechanism of Induced Seismicity Utilizing InSAR-Retrieved Land Subsidence, Source Model, and Geological Constraints 

Wojciech Witkowski, Magdalena Łucka, Henriette Sudhaus, Anna Barańska, Ryszard Hejmanowski, and Artur Guzy

Mining-induced sub-surface rock-failure processes cause seismicity and permanent surface deformation that may result in infrastructural damages and endanger residents in the affected areas. In recent years, this issue has received increasing attention due to the suddenness of the occurrence, the lack of effective predictive capabilities and the adverse consequences.  Importantly, seismic events have caused significant land subsidence and several fatalities in Polish underground mines. To better investigate such mining-induced sub-surface rock failure processes, we analyze rock deformation based on surface displacement data and also put local geology in context with seismological analysis results.

In Poland's Legnica-Glogow Copper District, between 2016 and 2020, 13 mining-induced earthquakes in the moment magnitude range from 3.2 to 3.8 have been recorded by the IS-EPOS platform. Based on co-seismic Sentinel-1 satellite radar images of ESA’s Copernicus program, and radar interferometry (InSAR) we measure the surface displacements caused by nine of these earthquakes. The maximum line-of-sight surface displacements are observed for the Mw3.6 mining-induced earthquake on October 17, 2016 with 144 mm and 124 mm away from the satellite in ascending and descending radar interferograms, respectively, and an estimated maximum land subsidence reaching -142 mm. We estimate the location and volume component associated with these surface effects by using an isotropic volume point-source model in a Bayesian inference. The Geodetic Bayesian Inversion Software GBIS has been applied for these calculations. Notably, only some of the earthquakes we analyse resulted in land subsidence. Although no significant relationship between earthquake magnitude and land subsidence is apparent, we find that the greater the thickness of loose Quaternary strata, the greater the land subsidence. The focal points of the deformation at depth of the investigated earthquakes, which we compare to seismic hypocenters, are located at depths of 437 m to 669 m, according to our results. Importantly, these focal points are located above the mining exploitation fields, within layers of rigid Triassic rock. Our results also show a mismatch between the spatial location of the earthquake epicentres and the maximum land subsidence. These differences are up to 440 m and are greater for the earthquake epicentres determined using seismic data than for the source point model. This discrepancy suggests that the epicentre of a mining-induced earthquake is not necessarily associated with the region of maximum rock layer compaction.

This study adds to our understanding of the impact of mining-induced seismicity on the occurrence of land subsidence and the seismic mechanism in areas of active mining paving the way towards more sustainable mineral extraction.

How to cite: Witkowski, W., Łucka, M., Sudhaus, H., Barańska, A., Hejmanowski, R., and Guzy, A.: Research on the Mechanism of Induced Seismicity Utilizing InSAR-Retrieved Land Subsidence, Source Model, and Geological Constraints, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9584, https://doi.org/10.5194/egusphere-egu23-9584, 2023.

EGU23-11422 | Posters on site | ERE5.1

An Attempt to Control Induced Seismicity and On-Fault Stress Pre-Conditioning in the Bedretto Underground Laboratory, Switzerland 

Mohammadreza Jalali, Paul Selvadurai, Luca Dal Zilio, Virginie Durand, Anne Obermann, Men-Andrin Meier, and Florian Amann and the Bedretto Team

Hydraulic stimulation has been used as a standard practice for rock mass treatment to fulfill the intended engineering goal of the stimulation procedure in various applications such as oil & gas, mining, and enhanced geothermal systems (EGS). High-pressure fluid injection during the hydraulic stimulation perturbs the local stress field around the injection borehole which has a direct influence on the hydro-mechanical behavior of the rock mass and the measured induced seismicity. Hydraulic stimulation is usually conducted using a predefined injection protocol, a sequence of pressure and/or flow rate injection cycles. Extensive attempts have been designed to develop a proper injection protocol in laboratory and field scales to reach the stimulation goals as well as reduce the risk of induced seismicity.

In the context of the ERC “Fault Activation and Earthquake Rupture (FEAR)” project, injection protocols are developed to further our understanding of earthquake rupture processes such as nucleation and premonitory slip. A series of stress-preconditioning injection strategies were tested in the Bedretto Underground Laboratory for Geoenergies and Geosciences, Switzerland (Ma et al., 2022, Solid Earth), using an existing stimulation and monitoring array (Plenkers et al., under rev. with Sensors). The main objective of these tests was to develop atypical injection strategies that could be implemented in different geological conditions that target aspects of induced seismicity associated with high-pressure fluid injection. We performed two injections and monitored the rock mass response using six monitoring boreholes each equipped with multi-component seismic monitoring systems, pressure, temperature, and distributed strain sensing arrays. Two different injection protocols have been applied in two packed-off injection intervals of a stimulation borehole, allowing us to characterize the hydro-mechanical response of the rock mass around these intervals. Each test was associated with pre- and post-characterization tests including hydraulic and hydro-mechanical tests such as HTPF tests.

The preliminary results of these tests show a direct dependency of the location and magnitude of seismicity with injection protocols. Moreover, the effect of the injection protocols on the characteristics of the rock mass such as transmissivity and normal stress could be quantified. Preconditioning of the fault appears to require low permeability, preferably undrained, fault structures and suffers if any fluids pathway are mitigated by the long range, slow pressurization of this region. Complex fluid pathways made re-stimulation and precondition of the target structures difficult. The outcomes of these tests play a key role in the design of upcoming FEAR stimulation experiments to better understand the earthquake physics on a field scale.

 

References

Ma, X., Hertrich, M., Amann, F., Bröker, K., Gholizadeh Doonechaly, N., et al., 2022. Multi-disciplinary characterizations of the BedrettoLab–a new underground geoscience research facility. Solid Earth, 13(2), pp.301-322.

Plenkers K., Reinicke A., Obermann A., Gholizadeh Doonechaly N., Krietsch H., et al., under rev. with Sensors, Multi-disciplinary monitoring networks for mesoscale underground experiments: Advances in the Bedretto Reservoir Project.

How to cite: Jalali, M., Selvadurai, P., Dal Zilio, L., Durand, V., Obermann, A., Meier, M.-A., and Amann, F. and the Bedretto Team: An Attempt to Control Induced Seismicity and On-Fault Stress Pre-Conditioning in the Bedretto Underground Laboratory, Switzerland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11422, https://doi.org/10.5194/egusphere-egu23-11422, 2023.

EGU23-11883 | ECS | Posters on site | ERE5.1

Modeling the waveforms of induced seismicity sequences with application to Utah FORGE 

Laura Ermert, Federica Lanza, Federico Ciardo, Peidong Shi, Michael Afanasiev, and Stefan Wiemer

We present a modeling workbench for generating hours-long synthetic sequences of induced seismic events. As input, this tool takes observed or synthetic catalogs of induced seismicity including the location, seismic moment and source mechanism of the induced events. It outputs synthetic seismic waveform recordings with added noise.

The purpose of this tool is two-fold: First, it serves to generate synthetic test data that can be used to train detection and location algorithms for induced seismicity monitoring, and to test their efficacy. Monitoring induced seismicity is a key task for the risk management of enhanced geothermal systems, but the relative scarcity of manually labeled data hampers rigorous testing of newly developed algorithms. We intend to partially close the gap in labeled data with synthetics, which can furthermore be used to enhance training data sets for deep learning approaches.

Second, the tool serves as an extension to physics-based models of induced seismicity in geothermal reservoirs, such as hydro-mechanical models, providing an efficient way of turning their induced event clouds into seismic “recordings”.

The workflow is based on the spectral-element solver Salvus and on Python, and relies on source-receiver reciprocity to decrease computational cost for large sets of induced events. As first application site, we chose the Utah Frontier Observatory for Research in Geothermal Energy – FORGE. This first application comprises a realistic digital representation of the reservoir and its surroundings, including topography, geologic structure and crustal scattering. We will show exemplary synthetic induced seismicity sequences based on an observed catalog from the 2022 stimulation at the Utah FORGE, as well as on a hydro-mechanically modeled synthetic catalog. The output waveform sequences are to be publicly shared for benchmarking monitoring workflows for induced events, in an effort to contribute to the de-risking of enhanced geothermal systems.

How to cite: Ermert, L., Lanza, F., Ciardo, F., Shi, P., Afanasiev, M., and Wiemer, S.: Modeling the waveforms of induced seismicity sequences with application to Utah FORGE, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11883, https://doi.org/10.5194/egusphere-egu23-11883, 2023.

EGU23-11960 | ECS | Orals | ERE5.1

Can earthquakes nucleate on nominally stable velocity-strengthening faults? 

Luca Dal Zilio, Paul A. Selvadurai, Jean-Paul Ampuero, Elisa Tinti, Massimo Cocco, Frédéric Cappa, Stefan Wiemer, Domenico Giardini, and the Bedretto Team

Tectonic faults are often assumed to slip either slow due to stable, velocity-strengthening frictional behavior, or fast as a result of velocity-weakening friction leading to dynamic (seismic) rupture. As a consequence, velocity-strengthening faults may be regarded as intrinsically stable as they do not spontaneously nucleate seismic events. However, recent laboratory and in-situ experiments of fluid injection challenged such assumptions. Here we present a fully coupled hydro-mechanical fault model in which stable, rate-strengthening frictional behavior is combined with dynamic weakening due to rapid poroelastic effects, allowing unstable (seismic) slip to occur on nominally stable faults. In our numerical experiments, fluid injection reduces the effective normal stress and frictional resistance, thus bringing the fault to failure. The onset of fault failure is controlled by competing mechanisms of shear-induced dilation and shear-enhanced compaction, which cause fault weakening and the propagation of a slow-slip transient from the fluid injection point. When a critical size of the slow slip patch is reached, dynamic rupture eventually nucleates at the slow-slip event front and propagates beyond the fluid pressure perturbed region. Further numerical experiments indicate that, when the fault is critically stressed, the growth of the aseismic patch – prior to dynamic rupture – occurs in a few seconds, whereas at lower stress levels, the aseismic slip phase propagates slowly over hundreds of seconds. These results predict that poroelastic compaction and fluid pressurization can cause the transition from aseismic slow-slip to fast seismic slip and the propagation of dynamic rupture on velocity-strengthening faults. In particular, they demonstrate that compaction-induced fluid pressurization can overcome the initial phase of shear-induced dilatancy, thus allowing the propagation of dynamic rupture in the form of pulse-like pore-pressure waves. The implication that earthquake rupture may nucleate on rate-strengthening faults, presently considered to be nominally stable, requires a re-evaluation of seismic hazard in many areas, particularly in the case of fluid injection in enhanced geothermal systems and CO2 storage.

How to cite: Dal Zilio, L., Selvadurai, P. A., Ampuero, J.-P., Tinti, E., Cocco, M., Cappa, F., Wiemer, S., Giardini, D., and Team, T. B.: Can earthquakes nucleate on nominally stable velocity-strengthening faults?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11960, https://doi.org/10.5194/egusphere-egu23-11960, 2023.

EGU23-12783 | ECS | Posters on site | ERE5.1

Performance comparison of newly developed hydro-mechanical (hybrid) models for real-time induced seismicity forecasting 

Victor Clasen Repolles, Antonio Pio Rinaldi, Federico Ciardo, Luigi Passarelli, and Stefan Wiemer and the Bedretto Team

The Adaptive Traffic Light System (ATLS) is a seismic risk mitigation tool that can be used during geoenergy exploitation projects such as in the creation of Enhanced Geothermal Systems (EGS). In real-time applications, ATLS needs to include a data assimilation scheme in order to produce adaptive and time-dependent probabilistic seismicity forecasts by using the maximum available information at the moment of the assessment during such industrial operation. Numerical models capable to robustly forecast in real-time the temporal evolution of induced seismicity while properly accounting for uncertainties are the core elements of a functioning ATLS. In this respect, hydro-mechanical (HM) hybrid models are suitable models since they combine both statistical and physics-based assumptions to forecast induced seismicity. They include an accurate modeling of the physical processes involved in the generation of seismicity caused by human activity by keeping the associated computational cost low. In this work, we have developed two classes of simplified hybrid models that are based on 1D radial pore-fluid diffusion and fluid injection. The first class (HM0) accounts for linear pore-fluid diffusion from the fluid source, while the second class (HM1) accounts for the non-linear response of the medium due to pressure-dependent permeability variations upon fluid injection. Each class is sequentially coupled to two stochastic seismicity models that trigger seismicity if the respective space-time pressure solution reaches a critical value according to the Mohr-Coulomb criterion. However, both seismicity models differ in the way they simulate seismicity. One model uses an analytical approach based on probability density functions of model parameters to simulate seismicity (CAPS), while the other model simulates seismicity via stochastic seed approach (SEED). In a hindcast experiment, we test the models’ real-time forecasting capabilities within a data assimilation scheme using datasets from in-situ injection experiments that encompass different spatial scales. An essential step towards building a reliable ATLS is to properly weight each candidate model according to its respective contribution to the seismic hazard calculation. Therefore, an important part in our calculations is to evaluate and compare the forecasting performance of each model for each of the presented cases. Our findings show that models that take into account reliable distribution of uncertainties on a-priori selected model parameters as well as models accounting for a physically more accurate pressure solution in space and time generate better forecasting performances.

How to cite: Clasen Repolles, V., Rinaldi, A. P., Ciardo, F., Passarelli, L., and Wiemer, S. and the Bedretto Team: Performance comparison of newly developed hydro-mechanical (hybrid) models for real-time induced seismicity forecasting, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12783, https://doi.org/10.5194/egusphere-egu23-12783, 2023.

EGU23-13227 | ECS | Orals | ERE5.1

Near-real-time microseismic monitoring with machine-learning and waveform back-projection at the Utah FORGE geothermal site 

Peidong Shi, Federica Lanza, Francesco Grigoli, and Stefan Wiemer

Deep geothermal energy exploitation necessitates establishing effective fluid circulation paths for heat transfer and managing induced earthquake risk. By detecting and characterizing induced microseismic events, we can provide insights into the fracture network growth and the induced earthquake risk during hydraulic stimulation and geothermal production in enhanced geothermal systems (EGS). During hydraulic stimulation, monitoring has to be performed in near-real-time to provide timely information for assessing potential earthquake risk and for adjusting the stimulation plan. In addition, high-precision microseismic event location is vital for evaluating the connectivity of the stimulated reservoir and designing the trajectory of the production wells. However, achieving real-time monitoring and high-resolution location in a single monitoring workflow is challenging due to the low signal-to-noise ratio and short inter-event time of microseismic events.

To address these challenges in microseismic monitoring, we build a near-real-time monitoring workflow that integrates machine-learning (ML) techniques for efficient event detection and waveform back-projection methods for high-precision event location. The proposed workflow is designed to utilize various pre-trained ML models to deal with the scarcity issue of training datasets in new EGS sites. We apply the proposed workflow to the microseismic dataset collected at the Utah FORGE geothermal site in a playback mode. Because most pre-trained ML models are trained on local earthquake datasets having larger event magnitudes and lower data sampling rates, we implement and evaluate various strategies, such as re-scaling, re-sampling, and filtering, to enhance the performance of pre-trained models on the microseismic dataset. We compare the obtained ML catalog with a reference catalog built from a conventional workflow consisting of automatic phase picking and manual refinement. Due to the application of ML and waveform back-projection techniques, our workflow can nicely separate microseismic events with very short inter-event times (in terms of a second) and cope with events with significant magnitude/amplitude differences, leading to more reliable event detections. Detailed comparisons show that the accuracy of ML phase identification is comparable to and sometimes even superior to manual picking (with a difference in milliseconds), which contributes to precise event locations.

How to cite: Shi, P., Lanza, F., Grigoli, F., and Wiemer, S.: Near-real-time microseismic monitoring with machine-learning and waveform back-projection at the Utah FORGE geothermal site, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13227, https://doi.org/10.5194/egusphere-egu23-13227, 2023.

EGU23-13239 | ECS | Posters on site | ERE5.1

Repeating earthquakes induced during a decameter-scale hydraulic stimulation experiment at the Grimsel Test Site, Switzerland 

Linus Villiger, Toni Kraft, Valentin Gischig, Hannes Krietsch, and Stefan Wiemer

We performed a similarity based hierarchical cluster analysis and carried out a master event relative relocation of seismicity induced during the hydraulic stimulation of a brittle and highly fractured shear zone. The shear zone was stimulated in an extend of about 10 m and is located in crystalline rock at the Grimsel Test Site, Switzerland. The objective of the experiment was to improve our understanding of stimulation processes associated with high-pressure fluid injections used for reservoir creation in enhanced geothermal systems. In addition to the seismic network exhibiting high spherical coverage at close distances (i.e., eight acoustic emission sensors ~10 – 15 m away from the injection interval), fluid pressures, rock mass deformations and fault dislocations were monitored around the injection location. 1/3 of the located seismic events could be assigned to 44 repeater families exhibiting high waveform similarity (i.e., >95%) when comparing waveform similarities sequentially in time. When comparing similarities to the chosen master event, similarities decay continuously within a repeater family which also reflects in a spatial migration of hypocenters. However, source areas of seismic events within repeater families mostly overlap assuming an appropriate stress drop. But the spatial extent of the observed migration of hypocenters compared to the measured mechanical deformation in the volume is larger and thus suggests that multiple asperities are responsible for seismic events within a repeater family. The repeater families themselves are distributed in clusters which are attributed to the stimulation of distinct fractures in the damage zone of the targeted shear zone. No repeating events were found in the seismicity accompanying a tensile fracture splaying off the stimulated pre-existing fractures. Statistically, events of repeater families are rather Gaussian than power-law distributed. The extended analysis of this multisensor array data presented here reveals a highly complex fracturing process on the 10 m scale during hydraulic stimulation (see also an earlier study of the same experiment focusing on source mechanism Villiger et al. (2021)).

 

References

Villiger, L., Gischig, V. S., Kwiatek, G., Krietsch, H., Doetsch, J., Jalali, M., Amann, F., Giardini, D., & Wiemer, S. (2021). Meter-scale stress heterogeneities and stress redistribution drive complex fracture slip and fracture growth during a hydraulic stimulation experiment. Geophysical Journal International. https://doi.org/10.1093/gji/ggab057 (Geophysical Journal International)

How to cite: Villiger, L., Kraft, T., Gischig, V., Krietsch, H., and Wiemer, S.: Repeating earthquakes induced during a decameter-scale hydraulic stimulation experiment at the Grimsel Test Site, Switzerland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13239, https://doi.org/10.5194/egusphere-egu23-13239, 2023.

EGU23-13390 | ECS | Orals | ERE5.1 | Highlight

First results on induced seismicity and its source parameters during hydraulic stimulations in the Bedretto Underground Laboratory, Switzerland 

Martina Rosskopf, Virginie Durand, Linus Villiger, Anne Obermann, and Domenico Giardini and the Bedretto Team

The Bedretto Underground Laboratory for Geoenergies and Geosciences (BedrettoLab) is a unique research environment in a tunnel in the Swiss Alps with an overburden of one kilometer. For a first experimental campaign in the context of enhanced geothermal reservoir creation (enhanced geothermal system, EGS), six 150-300 m long monitoring boreholes were drilled in the BedrettoLab and equipped with a multi-component geophysical monitoring system. The seismic sensors are composed of acoustic emission sensors, accelerometers and geophones to cover a magnitude range from nano to micro seismicity. An additional 400 m long stimulation borehole is equipped with a multi-packer system dividing it into 15 separate intervals of 8 to 55 m length.

In the first phase, we performed characterization stimulations in eight intervals using comparable small amounts of injected fluid (350-14000 l) dependent on the length of the interval and their initial transmissivity. In the second phase, we are restimulating the intervals with higher injection volumes. The objective of these experiments is to improve our understanding of the hydro-seismo-mechanical response of the surrounding rock mass to hydraulic injections. 

For each interval, the seismic activity varies in number and magnitude and in its spatial and temporal evolution although comparable injection volumes were used. We interpreted the spatio-temporal evolution of event clouds together with the preconditions of the intervals, such as fracture network and transmissivity. Those preconditions can have a big impact on how the rock mass behaves when pressurized during hydraulic stimulations. Depending on the interval, event clusters are distinguished, for which first moment tensors are estimated. The moment tensors show different mechanisms not only for different intervals but also for different clusters. Finally, we compare the seismicity to other observables in the volume like stress and temperature measurements performed in monitoring boreholes to recognize fluid pathways and the response of the rock mass.

How to cite: Rosskopf, M., Durand, V., Villiger, L., Obermann, A., and Giardini, D. and the Bedretto Team: First results on induced seismicity and its source parameters during hydraulic stimulations in the Bedretto Underground Laboratory, Switzerland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13390, https://doi.org/10.5194/egusphere-egu23-13390, 2023.

EGU23-14231 | Orals | ERE5.1

Coda Q analysis of active UT measurements to monitor the dm-scale fracture network in response to the STIMTEC hydraulic stimulations, Reiche Zeche URL (Germany) 

Aglaja Blanke, Carolin M. Boese, Georg Dresen, Marco Bohnhoff, and Grzegorz Kwiatek

The occurrence of induced microseismicity is commonly used to characterize a stimulated geo-reservoir, e.g. in terms of monitoring the damage and stress evolution in the rock mass. Studies in Underground Research Laboratories (URLs) have the advantage that a close by Acoustic Emission monitoring system (earthquake source – receiver distances < 50 meters) allows to investigate the detailed evolution of induced seismicity at the decimeter scale in response to injection operations. Controlled hydraulic stimulation experiments often benefit from additional active seismic measurements conducted near the source regions of the induced seismic events to better characterize the rock mass. The so-called active Ultrasonic Transmission (UT) measurements produce stronger signals covering a broad frequency range from the centimeter to decimeter scale which may be used to investigate space-time varying fracture network development and attenuation properties. The STIMTEC project in the Reiche Zeche URL in Freiberg (Germany) provides more than 300 active UT measurements that were performed before and after hydraulic stimulations in two boreholes in the targeted rock volume, an anisotropic metamorphic gneiss. To investigate spatio-temporal changes of frequency-dependent scattering attenuation and thus to monitor variations in the local fracture network, we analyzed S-coda waves of 88 spatially representative UT measurements covering a signal frequency content of 1 – 60 kHz. We grouped neighboring UT measurements to estimate frequency-dependent mean-Qc (coda quality factor) values for in total eight UT groups, covering different borehole depth intervals and time periods. Stable Qc estimates for center frequencies between 3 – 21 kHz of octave-width frequency bands were obtained. Our estimates show a characteristic frequency-dependence as observed at the field scale in geological reservoirs. Temporal variations of Qc values are strongly connected to hydraulic stimulation, and these variations are more significant than those resolved from estimated velocity changes. We find indication for healing processes of injection-induced small-scale fractures during a two-months post-stimulation phase indicated by attenuation changes at high frequencies not resolvable at the earth’s surface. The coda analysis further reveals spatial differences of attenuation characteristics supporting previous assumptions based on borehole televiewer logs and mapped structures of an existing fault with larger damage zone that crosses the stimulated rock volume. We conclude that the coda analysis of active UT measurements complements established imaging methods used during experiments in URLs. In particular, coda analysis is a powerful tool for the detection of damage zones and for monitoring changes in local fracture networks with immediate application for imaging geo-reservoirs considered for exploitation or underground storage of gases and liquids.

How to cite: Blanke, A., Boese, C. M., Dresen, G., Bohnhoff, M., and Kwiatek, G.: Coda Q analysis of active UT measurements to monitor the dm-scale fracture network in response to the STIMTEC hydraulic stimulations, Reiche Zeche URL (Germany), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14231, https://doi.org/10.5194/egusphere-egu23-14231, 2023.

EGU23-15041 | ECS | Posters on site | ERE5.1 | Highlight

Dynamic forecasting of the next largest earthquake during hydraulic fracturing stimulations 

Iason Grigoratos, Grzegorz Kwiatek, and Stefan Wiemer

Most traffic-light systems (TLS) related hydraulic fracturing stimulations still adopt the maximum observed magnitude as the decisive metric to aid decision making by stakeholders. However, waiting for the red-light magnitude to be observed is not a proactive stance, especially given that jumps of up to two magnitude units are evidently common enough between events. Clearly there is a need to actively forecast rather than to passively record the size of the next largest earthquake (NLE). In this study, we demonstrate that we can do just that using an ensemble of 6 existing models from the literature designed with similar purposes in mind (Shapiro et al. 2013; McGarr 2014; Mendecki 2016; van der Elst et al. 2016; Galis et al. 2017; Cao et al. 2020). Following a logic-tree approach, these 6 models are calibrated and dynamically weighted in near real-time using as sole inputs the initial parts of the earthquake catalogs and the reported injection rates. The proposed forecasting tool is tested against 18 past stimulations from 9 different Enhanced Geothermal Systems around the world (Helsinki, Basel, Soultz, Cooper Basin, Basel, Pohang, FORGE, Paralana, Newberry). Overall, the results indicate a consistent (across sites and time) and accurate estimation of the next largest magnitude with a tight uncertainty range (1σ) of less than 0.5 magnitude units. Our proposed framework underestimated the next largest magnitude only in one occasion (out of the 18 stimulations), while reliably maintaining a tight safety margin of less than 1 magnitude unit. We recommend that the forecasted NLE replaces the largest observed magnitude as the default metric adopted by future TLS governing any type of fluid-injection operation.

 

How to cite: Grigoratos, I., Kwiatek, G., and Wiemer, S.: Dynamic forecasting of the next largest earthquake during hydraulic fracturing stimulations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15041, https://doi.org/10.5194/egusphere-egu23-15041, 2023.

Subsurface fluid injections are commonly accompanied by seismicity which can sometimes result in earthquakes of relatively large magnitude that pose a serious hazard for the geo-energy industry. Current efforts to manage the seismic risk associated with fluid injections work generally under the tacit assumption that mitigation measures will become shortly effective in preventing the occurrence of earthquakes of larger magnitude than some pre-defined threshold. A common operational measure is shutting in the wells indefinitely. Unfortunately, seismicity after shut-in is common and, even more, it is not rare that the largest events of injection-induced seismic sequences occur during the post-injection stage. Understanding the physical mechanisms underpinning post-injection seismicity is thus of first importance for the successful development of geo-energy projects. Moreover, gaining knowledge in this matter may ultimately help to design physics-based strategies to mitigate the seismic risk associated with fluid injection operations. From a pure hydro-mechanical perspective, there are two well-known triggering mechanisms for post-injection-induced seismicity, namely, the diffusion of pore-fluid pressure (Parotidis et al., 2004) and poroelastic stressing (Segall and Lu, 2015). Recently, Sáez and Lecampion (2023) have investigated a third mechanism where injection-induced aseismic slip in pre-existing fractures and faults may keep propagating after shut-in and continue stressing even larger and more distant regions from the injector during time scales that could span even months for fluid injections of only few days, if the reactivated fracture/fault is critically stressed. This result has motivated us to develop a physics-based strategy to mitigate the seismic risk associated with post-injection aseismic slip. The idea is to extract fluids as an operational measure instead of just stopping the injection. It is shown that fluid withdrawal has not only the effect of reducing the further increase of pore pressure during the post-injection stage, but also the effect of decreasing both the spatial extent and exposure time of the surrounding rock mass to quasi-static changes of stresses due to aseismic slip. The main parameter controlling the reduction of the spatial extent and exposure time is the ratio between the extraction rate and injection rate.  We make use of realistic field configurations to provide examples that show the significant reduction of the exposure time that can be achieved by extracting fluids. We also discuss some field evidence that support the plausibility of this extraction strategy.

How to cite: Sáez, A. and Lecampion, B.: Extraction of fluids to mitigate the seismic risk associated with post-injection aseismic slip, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15861, https://doi.org/10.5194/egusphere-egu23-15861, 2023.

EGU23-15982 | ECS | Posters on site | ERE5.1

Detecting and mapping the induced seismicity of a planned EGS in Helsinki/Espoo, Finland 

Tommi Vuorinen, Gergor Hillers, Kati Oinonen, Jennifer Hällsten, George Taylor, and Martin Gal

The company ST1 Oy planned to construct an Enhanced Geothermal System (EGS) with two boreholes drilled down to ca. 6 km depth beneath the Aalto University campus in Otaniemi, Espoo, on the border of Helsinki. The company performed two stimulations, in June–July 2018 and in May 2020, with a goal of opening up a water reservoir and achieving water circulation between the boreholes. The stimulation periods, which induced thousands of earthquakes, and their immediate surroundings were monitored by both permanent and temporary seismic networks with over 100 stations located within a few tens of kilometers of the site. Between and after the stimulations, the site was and is still being monitored by a relatively dense, consisting in total of ca. 20 stations, regional surface station and company installed borehole station networks.

We have developed a cross-correlation based event detector which uses the existing ISUH manually analysed catalogues primarily of the 2018 and 2020 stimulation period seismicity, complemented by automatically picked catalogues from IMS, to detect events from the collected continuous waveform database. The 4-step detector – templating, detecting, event filtering & relocating – can run on varying station configuration and is able to detect events down to ML -0.5 – -1.0 with the station-event geometry around the EGS. We present here the results of the detector run from the beginning of the dense stimulation monitoring in May 2018 to the end of 2022 providing a comprehensive anatomy of the EGS induced seismicity.

How to cite: Vuorinen, T., Hillers, G., Oinonen, K., Hällsten, J., Taylor, G., and Gal, M.: Detecting and mapping the induced seismicity of a planned EGS in Helsinki/Espoo, Finland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15982, https://doi.org/10.5194/egusphere-egu23-15982, 2023.

EGU23-16577 | ECS | Posters on site | ERE5.1

GEOBEST2020+ baseline seismic monitoring workflow and network performance evaluation for deep geothermal projects in Switzerland 

Verónica Antunes, Toni Kraft, Philippe Roth, Tania Toledo, and Stefan Wiemer

Deep geothermal is a clean and renewable source of energy with a high potential for heat and electricity production which can help Switzerland meet its energy and climate objectives. Worldwide, several geothermal projects have been successfully operated for decades. Unfortunately, some projects have also been suspended due to unexpected levels of induced seismicity. Thus, adequate risk management is essential to establish safe and economically viable geothermal projects.

In Switzerland, the subsurface is under the sovereignty of the cantonal authorities. Within the GEOBEST2020+ project, the Swiss Seismological Service (SED) supports the cantons in adequately handling the risk of induced seismicity associated with deep geothermal projects. Funded by the Federal Office of Energy (SFOE) in the scope of its SwissEnergy program, the GEOBEST2020+ program aims to provide operator-independent seismological consulting and baseline seismic monitoring services to the cantonal authorities.

In this framework, we deploy dedicated seismic networks in the vicinity of the monitored projects. These networks must be sensitive enough to follow the evolution of microseismicity and allow the operators to run traffic-light systems and take action before larger events occur. Before the station installation, we perform a careful site survey analysis, considering the background noise conditions and evaluating the signal-to-noise ratio at each site. To evaluate beforehand the detection sensibility of a seismic network, we estimate the Bayesian Magnitude of Completeness (BMC), optimized for Switzerland. We additionally estimate the theoretical location uncertainties inside the network considering the background noise level at the stations and the network geometry.

Here we show the comparison results between our methodology to the ground truths of several years of continuous monitoring data at Lavey-les-Bains, canton of Vaud. We use a combination of three types of detection methods: Machine Learning combined with migration methods (MALMI), coherence (Pyrocko/Lassie) and template matching (QuakeMatch), to produce a high-quality, manually revised seismic catalog. We compare our theoretical methods of network performance to the real data measured at the geothermal site.

How to cite: Antunes, V., Kraft, T., Roth, P., Toledo, T., and Wiemer, S.: GEOBEST2020+ baseline seismic monitoring workflow and network performance evaluation for deep geothermal projects in Switzerland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16577, https://doi.org/10.5194/egusphere-egu23-16577, 2023.

EGU23-16584 | Orals | ERE5.1

Pressure diffusion controls maximum induced earthquake magnitudes 

Cornelius Langenbruch, Mohammad J. A. Moein, and Serge A. Shapiro

It is an open question if maximum induced earthquake magnitudes can be determined based on knowledge about operational parameters, subsurface conditions and physical process understanding. We analyzed a global compilation of earthquakes induced by hydraulic fracturing, geothermal reservoir stimulation, water disposal, gas storage and reservoir impoundment. Our analysis showed that maximum magnitudes scale with the characteristic length of pressure diffusion in the brittle Earth’s crust. An observed increase of the nucleation potential of larger magnitude earthquakes with time is likely governed by diffusion-controlled growth of pressure perturbed fault sizes. Numerical and analytical fault size modelling confirmed the findings. Finally, we derived scaling laws for the maximum possible and maximum expected magnitude for induced seismic hazard and risk forecasting and management.

How to cite: Langenbruch, C., Moein, M. J. A., and Shapiro, S. A.: Pressure diffusion controls maximum induced earthquake magnitudes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16584, https://doi.org/10.5194/egusphere-egu23-16584, 2023.

A workflow is presented to estimate the size of a representative elementary volume and 3-D hydraulic conductivity tensor based on the discrete fracture network (DFN) fluid flow analysis through the case study performed for a granitic rock mass near the low and intermediate level radioactive waste disposal site in southeastern Korea. Intensity and size of joints were calibrated using the first invariant of fracture tensor for the 2-D DFN of the study area. Effective hydraulic apertures were obtained by analyzing the results of field packer tests. The representative elementary volume of the 2-D DFN was determined to be 20m square by investigating the variations in the directional hydraulic conductivity for blocks of different sizes. The directional hydraulic conductivities calculated from the 2-D DFN exhibited strong anisotropy related to hydraulic behaviors of the study area. The 3-D hydraulic conductivity tensor for the fractured rock mass of the study area was estimated from the directional block conductivities of the 2-D DFN blocks generated for various directions in 3-D. The orientations of the principal components of the 3-D hydraulic conductivity tensor were found to be identical to those of the delineated joint sets in the study area.

How to cite: Um, J.-G. and Bae, J.: Estimation of 3-D hydraulic conductivity tensor for a granitic rock mass near the low and intermediate level radioactive waste disposal site in Korea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1696, https://doi.org/10.5194/egusphere-egu23-1696, 2023.

EGU23-4952 | ECS | Orals | ERE5.2

Poroelastic modeling of borehole-based periodic hydraulic tests in non-fractured and fractured porous rocks 

Nicolás Barbosa, Tobias Müller, Marco Favino, and Klaus Holliger

Characterizing fluid transport and pore pressure diffusion is key for understanding and monitoring many natural (e.g., seismically active zones and volcanic systems) and engineered environments (e.g., enhanced geothermal reservoirs and CO2 underground storage). Borehole hydraulic testing allows to infer relevant properties of the probed sub-surface volume, such as, for example, its transmissivity and diffusivity, for assessing the governing flow regime as well as for detecting the presence of hydraulic boundaries. Periodic hydraulic tests (PHT) achieve these objectives using a time-harmonic fluid injection procedure while measuring the fluid pressure response in monitoring boreholes. The relevant information on the pressure diffusion process occurring in the probed formation is retrieved from the phase shifts and amplitude ratios between the injected flow rate and the interval pressure. In general, the interpretation of PHT data relies on the assumption that the pressure diffusion process is uncoupled from the solid deformation of the probed rock volume. We present a poroelastic numerical approach to investigate the role played by hydromechanical coupling (HMC) effects during PHT and to assess whether and to what extent additional mechanical information can be extracted from these tests. We focus on (i) the influence of the borehole wall deformation on the wellbore storage coefficient Sw, which quantifies the difference between the injected flow rates and those actually entering the porous formation; and on (ii) the HMC effects associated with the presence of fractures in the formation. Following the commonly taken approach, we also interpret the synthetic data from the numerical poroelastic approach using the uncoupled diffusion solution. For different rock physical properties, we demonstrate that, in homogeneous formations, the uncoupled diffusion solution reproduces the poroelastic results. In this scenario, neglecting the effect of the deformation of the borehole wall on Sw upon injection can lead to an underestimation of both the transmissivity and diffusivity, which becomes worse for shorter oscillation periods. We also show that the effective values of Sw depend on the shear modulus of the formation and do not change with the oscillatory period. Based on this evidence, we present a methodology to obtain the effective Sw along with the hydraulic properties using observations at various oscillatory periods. Next, we consider formations containing hydraulically open and compliant fractures intersecting the borehole perpendicularly. Here, a single uncoupled diffusion model is not able to fully describe the poroelastic response of the medium at different periods. Furthermore, the presence of fractures significantly affects the effective value of Sw: it increases with respect to the one associated with the intact homogeneous rock, and the HMC effects associated with the compressibility contrast in the formation result in a period dependence of Sw. The characteristic period of the latter is primarily related to the diffusivity and size of the fractures. This result is particularly relevant for the planning and interpretation of monitoring experiments, in which the mechanical properties of the formation are expected to evolve, such as, for example, hydraulic stimulation procedures, seismic and/or volcanic regions, and injection of wastewater and CO2 for subsurface storage.

How to cite: Barbosa, N., Müller, T., Favino, M., and Holliger, K.: Poroelastic modeling of borehole-based periodic hydraulic tests in non-fractured and fractured porous rocks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4952, https://doi.org/10.5194/egusphere-egu23-4952, 2023.

EGU23-5623 | ECS | Orals | ERE5.2

The evolution of permeability with pressure and temperature in microfractured granite 

Lucille Carbillet, Michael Heap, and Patrick Baud

Measurements of permeability at high-pressure and high-temperature are critical to model and understand the behaviour and evolution of geothermal systems. To perform such measurements and provide constraints on the permeability of crustal rocks, we designed and tested a new apparatus.

Our high-pressure, high-temperature permeameter consists of three independent parts: the permeant gas circuit, the confining fluid circuit, and the heating element. For each measurement, a cylindrical sample is placed between the up- and downstream platens, into an annular Viton jacket which is secured within the pressure vessel. A confining pressure can be applied to the sample by filling the void space between the vessel and jacket through the inlet with kerosene. The confining pressure can be increased up to 50 MPa using a high-pressure hand pump. The temperature of the system can then be increased from room-temperature to up to 150 °C using a heating mantle wrapped around the pressure vessel and connected to a control box. After the confining pressure and temperature have been applied to the system, the permeability measurement is performed by flowing nitrogen (the permeant gas) through the sample while monitoring the pressure differential between the upstream pressure transducer and atmospheric pressure downstream of the sample at different volumetric flow rates (the steady-state method), measured using the downstream flowmeter.

Using this new experimental apparatus, the permeability of Lanhélin granite (from France) samples were measured. Cylindrical samples were prepared and thermally stressed (heated to 700 °C) to ensure that their permeabilities lie in the range that can be measured in our set-up (> 10-18 m2). Permeability measurements were then performed under confining pressures of 2, 5, 10, 15, 20, 30, 40, and 50 MPa at room temperature, 50, and 100 °C. Our results provide the evolution of the permeability of microfractured granite in various pressure and temperature conditions, which will serve to inform numerical modelling designed to explore the influence of in-situ conditions on fluid flow within a fractured geothermal reservoir.

How to cite: Carbillet, L., Heap, M., and Baud, P.: The evolution of permeability with pressure and temperature in microfractured granite, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5623, https://doi.org/10.5194/egusphere-egu23-5623, 2023.

EGU23-5675 | ECS | Orals | ERE5.2

Along-strike fault geometry controls damage zone parameters: the case of the Kornos-Aghios Ioannis Extensional Fault (Lemnos Island, NE Greece) 

Luigi Riccardo Berio, Fabrizio Balsamo, Mattia Pizzati, Fabrizio Storti, Manuel Curzi, and Giulio Viola

The study of fault damage zones is key to the understanding of fault-related fluid flow in the upper crust with many applications, including groundwater and hydrocarbon exploration, and underground storage of CO2 and H. Many studies reveal that a relationship exists between fault damage zone width and net fault displacement. Despite this positive relationship, several factors such as the tectonic setting, the depth of deformation, the deformation mechanisms, and the evolving mechanical properties of fault rocks affect damage zone characteristics (e.g., width, asymmetry, fracture attitude, deformation intensity). Furthermore, recent studies show that the overall along-strike fault geometry may play a pivotal role in controlling damage zone characteristics. In particular, areas such as tip regions, linkage sectors, relay ramps and step-overs can be characterised by fault damage zone parameters markedly different from sectors away from these structural complexities. In this contribution, we present new structural data of fault damage zone parameters acquired along the 8 km long extensional Kornos-Aghios Ioannis Fault (KAIF) on Lemnos Island, North Aegean Sea, Greece. The KAIF deforms lower Miocene effusive and hypabyssal magmatic rocks and middle Eocene to lower Miocene turbidites. Deformed rock volumes along the KAIF are locally strongly altered by hydrothermal fluids (e.g., hydrothermal silicification). We provide a detailed characterization of the KAIF in terms of 2D fault geometry (mapped at 1:1000 scale) and kinematics and we present a characterization of fault damage zone parameters, including frequency and attitude of subsidiary fault-related fractures, in different fault sectors. The acquired data allowed us to define the boundaries of fault damage zones in the different sectors and to discuss the differences in terms of fracture attributes in linking- and tip-damage zones compared to damage zones away from these structural complexities. Our results show that fault damage zones in linkage and tip sectors are wider and that fault-related fractures are more clustered around several subsidiary faults with centimetre- to metre-offsets. Also, secondary fractures in linkage and tip sectors are less systematically oriented, thus increasing fracture network connectivity and, consequently, facilitating fluid mobility in structurally complex fault sectors.

How to cite: Berio, L. R., Balsamo, F., Pizzati, M., Storti, F., Curzi, M., and Viola, G.: Along-strike fault geometry controls damage zone parameters: the case of the Kornos-Aghios Ioannis Extensional Fault (Lemnos Island, NE Greece), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5675, https://doi.org/10.5194/egusphere-egu23-5675, 2023.

Fluid flow within low permeable reservoirs such as carbonates is primarily controlled by faults, fractures and other structural networks which can be defined through properties such as intensity, connectivity and aperture. These properties can vary not only among individual fractures but also between scales which can influence uncertainties within permeability calculations and fluid flow simulations. Therefore, understanding the interactions and variations within these networks is fundamental to deriving properties such as permeability and characterising fluid flow through naturally fractured reservoirs.

Determining fracture network properties of reservoirs can be undertaken using several methods across different scales from both surface and subsurface sources. However, where subsurface data is limited (e.g., within the geothermal reservoirs of Northern Bavaria), outcrop analogues become vital for obtaining the important information required for characterising fracture networks. Outcrops such as quarry sections can be imaged and scanned using both 2D and 3D photogrammetry techniques, from which fault and fracture networks can be detected and analysed. Previous work has presented a method to upscale fracture networks to 2D permeability tensors from outcrop sections through independently assigning properties to individual fractures within the networks. However, upscaling the networks to larger scales can lead to uncertainties due to variations within the modelled fracture networks. It its therefore important to understand the how the permeability tensor varies between scales and dimensions to reduce upscaling uncertainties.

Using examples from multiple outcrops within the Franconian Basin, Germany, we present an improved workflow to derive the tensors between dimensions and an investigation of the relationships among fracture networks at different scales. This will show the effect on permeability within geothermal reservoirs in the region and how to reduce the uncertainty in upscaling outcrops to subsurface reservoir scale.

How to cite: Smith, R., Prabhakaran, R., and Koehn, D.: Investigating scale variations in outcrop derived permeability tensors and the effect on geothermal fluid in upscaling naturally fractured reservoirs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6756, https://doi.org/10.5194/egusphere-egu23-6756, 2023.

EGU23-6830 | ECS | Posters on site | ERE5.2

Comparative analysis of analytical and numerical solutions for hydraulic properties upscaling in fractured media 

Erica De Paolo, Andrea Bistacchi, Stefano Casiraghi, and Fabio La Valle

The investigation of hydro-mechanical properties in rock formations is of utmost importance for several geological and engineering applications, e.g. for carbon-dioxide or hydrogen underground storage, exploitation of groundwater, geothermal or oil and gas reservoirs, hydrothermal ore deposits, and the mechanics of earthquakes. In particular, modeling fluid flow into networks of discontinuities (i.e. faults and fractures) is a key task in all these studies. Due to the high complexity of such processes, involving a significant number of feedbacks and occurring at different spatial and time scales, the achievement of a satisfying representation of the physical problem remains a challenge.

In the last decades, a variety of modeling approaches have been proposed in literature, accounting for different orders of complexity and using several computational methods. Analytical solutions are commonly based on simplistic assumptions about the process, allowing for simple fracture geometries and/or implying incompressible Newtonian fluids; as well as about the medium, considered elastic and permeable (or impermeable). Nevertheless, these solutions are still widely employed, as they provide significantly quick, first-order solutions compared to more sophisticated approaches.

On the other hand numerical models, typically accounting for a higher number of parameters and concurrent effects, are expected to return more realistic solutions. Those based on Finite Element Methods (FEMs) or similarly discretized domains, for example, permit to model the fractured rock mass with information that can be inferred from geological surveys and geophysical techniques.

As anticipated, important limitations in the use of more advanced modeling approaches could be the computing time and model size or resolution, not always allowing for cost-efficient solutions. In this study, we aim at a comprehensive review and benchmarking of the main classes of existing methods, comparing their results obtained for an identical dataset. In this way, we are able to highlight the advantages and disadvantages of each technique, defining the differences in accuracy and the ranges of applicability of these methods. 

The outcomes of our work are intended as a cross-benchmarking among available models, as well as a starting point for the future development of novel improved techniques in the field of fluid flows dynamics in networks of discontinuities.

How to cite: De Paolo, E., Bistacchi, A., Casiraghi, S., and La Valle, F.: Comparative analysis of analytical and numerical solutions for hydraulic properties upscaling in fractured media, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6830, https://doi.org/10.5194/egusphere-egu23-6830, 2023.

EGU23-7330 | ECS | Orals | ERE5.2 | Highlight

Structural patterns and states of stress at the Hengill Triple Junction, SW Iceland: implications for fluid-injection induced seismic hazard 

Ashley Stanton-Yonge, Thomas Mitchell, Philip Meredith, Sveinborg Gunnarsdóttir, Sandra Ósk Snæbjörnsdóttir, and Vala Hjorleifsdottir

The Hengill region is one of the largest areas of high geothermal gradient and subsurface heat flow in Iceland, and hosts two of its largest geothermal power plants: Hellisheiði and Nesjavellir, which have a combined capacity of 423 MWe and 560 MWth. The Hengill region is located in a unique tectonic setting, characterized by the convergence of three plate boundary segments: the oblique-spreading Reykjanes Peninsula (RP), the orthogonal-spreading rift of the Western Volcanic Zone (WVZ) and the transform, South Iceland Seismic Zone (SISZ). Unlike most tectonic triple junctions, which occur on the ocean floor, the Hengill Triple Junction (HTJ) is exposed above sea level, thus providing a unique opportunity to study the interplay between three plate boundary segments and the local deformation processes occurring at their convergence site. Additionally, the injection of fluids due to on-going geothermal operations enhances the natural tendency of the region for seismic activity, and results in a significant level of induced seismic hazard. Because slip on pre-existing faults is triggered when the applied shear stress surpasses the frictional strength of the fault, regions that are naturally subjected to higher shear stresses are more prone to fault re-activation due to fluid re-injection. Therefore, a spatial variation in tectonic stresses may result in varying induced seismicity potential within a region.

The local interplay of the three converging tectonic regimes, and their effect on the stress fields within the triple junction region, has been examined through a combination of regional structural mapping and a numerical model of the plate boundary interactions using the Boundary Element Method (BEM). Large scale structural mapping and analytical models of oblique rifting were used to estimate the degree of rift obliquity for individual fissure swarms. Our results reveal that the transition from the highly oblique rift system of the RP towards the spreading-orthogonal rift of the WVZ is smooth, and manifests as a rotation of the trend of fissures and eruptive ridges, and the strike of normal faults formed in response to the local stress field developed in the HTJ. These results were then correlated with those from the BEM model, which allows us to predict the orientation, relative magnitude, and distribution of stresses within the study area. Finally, the shear stress distribution determined from the BEM model was plotted against the location of both natural and induced seismic events detected in the region over a time span of 26 months, by the COSEISMIQ project (Grigoli et al., 2022). Our results show that seismic events cluster in either at the triple junction or SW of it, within the highly stressed regions of the RP. Furthermore, the seismicity transitions from scattered to non-existent towards the north of the region, where shear stresses also diffuse. The good correlation between the high shear stress regions predicted by the model and distribution of seismicity suggests that this approach may provide a valuable and cost-effective tool for seismic hazard prediction within regions with complex tectonic settings.

 

How to cite: Stanton-Yonge, A., Mitchell, T., Meredith, P., Gunnarsdóttir, S., Ósk Snæbjörnsdóttir, S., and Hjorleifsdottir, V.: Structural patterns and states of stress at the Hengill Triple Junction, SW Iceland: implications for fluid-injection induced seismic hazard, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7330, https://doi.org/10.5194/egusphere-egu23-7330, 2023.

EGU23-7596 | ECS | Posters on site | ERE5.2

Seismic monitoring of laboratory fault reactivation by pore fluid injection 

Aukje Veltmeijer, Milad Naderloo, and Auke Barnhoorn

Rising demand for energy and green energy has led to increasing subsurface activities, such as geothermal energy sites. These increasing human activities in the subsurface have caused substantial induced earthquakes in more densely populated areas, increasing the risks of operating safely. Well-known examples of induced seismicity, due to geothermal sites, are the M5.4 earthquake in Pohang (South Korea) or the M3.4 earthquake in Basel (Switzerland).  

Monitoring and forecasting earthquakes have been a topic of interest for years. Predictions are often made by production scenarios, probabilistic models, or average earthquake size distribution (b-value). Only a few studies focus on predicting fluid-induced seismicity by using seismic monitoring methods. Pore fluid changes play an important role in the reactivation of the fault strength and stability. Variations in pore pressure can cause a drop in the stresses along the fault plane and cause fault instability and movement resulting in induced seismicity.  Monitoring and predicting the stress changes along the fault planes can therefore be essential in forecasting induced seismicity and mitigation, potentially reducing the risks of operating (in denser populated areas). However, monitoring the degree of these changes remains challenging. Most studies using seismic methods to monitor induced seismicity on a field scale or laboratory scale focus on either passive monitoring or active monitoring. This study combines the two methods and shows how they complement each other in monitoring and mitigation of fault reactivation in the laboratory. We have performed pore fluid injection experiments on faulted sandstones to reactivate the faults while monitoring both actively (active seismic) and passively (acoustic emission).

These results show that both acoustic monitoring techniques can be used to detect the different fault reactivation stages: linear strain build-up, early creep (pre-slip), stress drop (main slip), and continuous sliding phase. However, using active monitoring the early creep phase is detected slightly earlier than using passive monitoring. Combining the methods shows that the stress changes along the fault can be detected with more detail in more accuracy. As a result, the combination of passive and active techniques may be useful for monitoring faulted or critically stressed reservoirs that experience pore pressure changes.

How to cite: Veltmeijer, A., Naderloo, M., and Barnhoorn, A.: Seismic monitoring of laboratory fault reactivation by pore fluid injection, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7596, https://doi.org/10.5194/egusphere-egu23-7596, 2023.

EGU23-8016 | Posters on site | ERE5.2

Hydrochemical Stimulation in Fractured Carbonate Rocks - Monitoring and Simulation 

Jörn Bartels, Peter Schätzl, and Thomas Baumann

Hydrochemical stimulation by acidification of geothermal wells is a standard procedure to remove drilling mud and to improve hydraulic contact between borehole and reservoir. Several successive stimulations using hydrochloric acid were monitored by both online measurement and conventional analysis. The results show recovery curves with distinct two-step exponential temporal decrease of the chloride concentration. The initial decrease is fast, representing water and acid flow along pathways which are very well connected to the borehole. After the fluid from these flow paths has been recovered, the concentration decreases at a lower rate. This can be attributed to water flowing in less well connected flow paths. With additional stimulations the chloride concentration curve approaches a mono-exponential decrease. This indicates that the flow paths within the reach of the stimulation get more homogeneous.

A numerical model of flow and solute transport in the borehole and the surrounding geothermal reservoir was developed in order to simulate the observed chloride-recovery behaviour in the course of a number of successive hydrochemical stimulations. The finite-element model was adapted to match the observed hydraulic and hydrochemical data range.

Simulation hereby allows to separate time-dependent single contributions from the different flow paths to the total recovery concentration. Based on this information, indications of structural change due to the successive acidification steps can be derived from the chloride-recovery curves of each step. Furthermore, for typical settings the minimum time and volume of solution can be estimated which is required to achieve a significant structural signal

The derived structural information can be useful to predict the long-term behaviour of a geothermal injection well which during operation is exposed to a mild but constant chemical stimulation by the injected cold and, with respect to chloride in the rock matrix, undersaturated water. 

How to cite: Bartels, J., Schätzl, P., and Baumann, T.: Hydrochemical Stimulation in Fractured Carbonate Rocks - Monitoring and Simulation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8016, https://doi.org/10.5194/egusphere-egu23-8016, 2023.

EGU23-8221 | ECS | Posters on site | ERE5.2

Slip tendency and reactivation pressure prediction of natural fractures at the Bedretto Underground Laboratory, Switzerland 

Kai Bröker, Xiaodong Ma, Deborah Stadler, Nima Gholizadeh Doonechaly, Marian Hertrich, and Domenico Giardini and the Bedretto Team

Hydraulic shearing of natural fractures or fault zones is a key mechanism for enhancing permeability in engineered geothermal systems (EGS) in order to extract geothermal energy from crystalline basement rocks. Shear reactivation is achieved by hydraulic stimulation in an injection borehole, involving a complex hydro-seismo-mechanical response of fractured crystalline rock. A major challenge is to predict which fractures are reactivated at which reactivation pressures, in order to efficiently design the injection protocols and create a large fracture network for sufficient fluid circulation and heat exchange.

The Bedretto Underground Laboratory for Geosciences and Geoenergies (BedrettoLab) in Switzerland serves as an in situ test-bed where meso-scale hydraulic stimulation experiments are conducted to better bridge the knowledge gap between laboratory scale experiments and complex reservoir scale processes (Ma et al. 2022). The BedrettoLab is located in a 100 m long enlarged section of the Bedretto tunnel (Ticino, Switzerland), with an overburden of more than 1000 m of granite. Several characterization, monitoring, and two stimulation boreholes were drilled. One of the stimulation boreholes (referred to as ST1) is 400 m long, 45°-dipping, and was equipped with a multi-packer system that partitions the borehole into 15 intervals. Before conducting two multi-stage hydraulic stimulation phases in borehole ST1, the rock volume was characterized with various geophysical logging tools, hydraulic tests, and mini-frac tests for stress measurements (Bröker and Ma 2022, Ma et al. 2022).

Along the stimulation borehole, we mapped multiple clusters of sub-parallel pre-existing open fractures and fault zones that are preferentially oriented for reactivation in the estimated stress field. In this work, we compare our preceding probabilistic slip tendency and reactivation pressure estimates with the results from hydraulic stimulation experiments. The interval pressure and flowrate data from the stimulations reveal a reactivation of the natural fractures associated with an increase in injectivity. A comparison of the expected stress field around the stimulation interval with the observed reactivation pressure indicates that the fractures were likely reactivated by hydraulic shearing. The observed reactivation pressures are in the range of the preceding estimates, but a precise estimation is challenging due to the large number of input parameters, i.e. stress magnitudes and orientation, fracture orientation, pore pressure, coefficient of friction, and their uncertainties.

References:

Bröker, K., & Ma, X. (2022). Estimating the Least Principal Stress in a Granitic Rock Mass: Systematic Mini-Frac Tests and Elaborated Pressure Transient Analysis. Rock Mechanics and Rock Engineering. https://doi.org/10.1007/s00603-021-02743-1

Ma, X., Hertrich, M., Amann, F., Bröker, K., Gholizadeh Doonechaly, N., Gischig, V., Hochreutener, R., Kästli, P., Krietsch, H., Marti, M., Nägeli, B., Nejati, M., Obermann, A., Plenkers, K., Rinaldi, A. P., Shakas, A., Villiger, L., Wenning, Q., Zappone, A., … Giardini, D. (2022). Multi-disciplinary characterizations of the BedrettoLab -- a new underground geoscience research facility. Solid Earth, 13(2), 301–322. https://doi.org/10.5194/se-13-301-2022

How to cite: Bröker, K., Ma, X., Stadler, D., Doonechaly, N. G., Hertrich, M., and Giardini, D. and the Bedretto Team: Slip tendency and reactivation pressure prediction of natural fractures at the Bedretto Underground Laboratory, Switzerland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8221, https://doi.org/10.5194/egusphere-egu23-8221, 2023.

EGU23-9317 | ECS | Orals | ERE5.2

Effect of stress regime change on fractured carbonate’s permeability: A case of Latemar carbonate buildup (The Dolomites, Northern Italy)  

Onyedika Anthony Igbokwe, Jithender Timothy, Ashwani Kumar, Xiao Yan, Mathias Mueller, Alessandro Verdecchia, Günther Meschke, and Adrian Immenhauser

Changes in stress regimes impact the geometry of fracture networks and affect the porosity and permeability of carbonate reservoirs. This is, predominantly, because of the complexity of the deformation phases, the poor understanding of the mechanical and diagenetic mechanisms that affect apertures, and the difficulty in precisely characterizing aperture distributions in the subsurface. Utilizing outcrop data analysis and displacement-based linear elastic finite element modelling, we study the effect of stress regime change on fracture network permeability. The model is based on fracture networks, specifically fracture sub-structures.

The Latemar, which is primarily affected by subsidence deformation and Alpine compression, is used as an outcrop analogue for isolated (Mesozoic) carbonate formations with fracture-dominated permeability. We apply a novel strategy involving two compressive boundary loading conditions constrained by the study area's NW-SE and N-S stress directions. Stress-dependent heterogeneous apertures and effective permeability were computed by: (i) using the local stress state within the fracture sub-structure and (ii) running a single-phase flow analysis considering the fracture apertures in each fracture sub-structure.

Our results show that the impact of the modelled far-field stresses at: (i) subsidence deformation (first stage loading) from the NW-SE, and (ii) Alpine deformation (second stage loading) from the N-S, increased the overall fracture aperture and permeability. In each case, increasing permeability is associated with open fractures parallel to the orientation of the loading stages and with fracture densities. The anisotropy of permeability is affected by shear dilation and is increased by the density and connectedness of the fracture network. The two far-field stresses simultaneously acting within the selected fracture sub-structure at a different magnitude and orientation do not necessarily cancel out each other in the mechanical deformation modelling. These stresses effect the overall aperture and permeability distributions. These effects, which may be ignored in simpler stress-dependent permeability, can result in significant inaccuracies in permeability estimation, especially in the subsurface carbonate reservoirs.

How to cite: Igbokwe, O. A., Timothy, J., Kumar, A., Yan, X., Mueller, M., Verdecchia, A., Meschke, G., and Immenhauser, A.: Effect of stress regime change on fractured carbonate’s permeability: A case of Latemar carbonate buildup (The Dolomites, Northern Italy) , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9317, https://doi.org/10.5194/egusphere-egu23-9317, 2023.

EGU23-9661 | Orals | ERE5.2

Quantitative structural analysis of fracture networks in outcrop analogues of fractured reservoirs: a review of measurement methodologies and statistical techniques 

Andrea Bistacchi, Sylvain Mayolle, Stefano Casiraghi, Erica De Paolo, Mattia Martinelli, Federico Agliardi, and Fabio La Valle

The characterization and modelling of fractured reservoirs of geofluids are becoming increasingly important in the ongoing energy transition and climate crisis. Fractured reservoirs are fundamental for critical applications such as CO2 sequestration, H2 and natural gas storage, exploitation of geothermal fluids and hydrothermal ore deposits, and management and safeguard of groundwater resources (deep aquifers are considered more resilient in drought scenarios). In addition, the characterization of fracture networks is relevant in earthquake mechanics, slope stability and engineering geology.

Characterization of natural fracture systems and fracture networks is often based on characterization of outcrop analogues, with measurement of large structural datasets with a combination of field and remote sensing techniques (e.g. Digital Outcrop Models - DOMs), leading to statistical and topological analysis. Numerous studies provide significant amounts of data from a broad variety of methodologies and protocols used in the field. These methodologies aim at characterizing fracture systems by a large number of parameters. Individual “fracture” sets are characterized by genetic features (e.g. joint vs. stylolite), relative chronology, spatial distribution (regular, random, clustered...), density and intensity (e.g. P20 and P21), and by statistical distributions of spacing, orientation, length, height, and aperture (the latter being a dynamical property that varies with fluid pressure and confining stress). Fracture networks composed by several sets are also characterized by topology and connectivity (characterized for instance in terms of fracture terminations or with graphs).

Here we propose a thorough review, supported by rich case studies, of quantitative methods for fracture network characterization and analysis on DOMs. This review aims at determining the most relevant and efficient methods for field and remote-sensing measurement, and best-practice statistical analysis techniques, in order to accurately characterize outcrop analogues that can be used to model fractured reservoirs.

How to cite: Bistacchi, A., Mayolle, S., Casiraghi, S., De Paolo, E., Martinelli, M., Agliardi, F., and La Valle, F.: Quantitative structural analysis of fracture networks in outcrop analogues of fractured reservoirs: a review of measurement methodologies and statistical techniques, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9661, https://doi.org/10.5194/egusphere-egu23-9661, 2023.

EGU23-9673 | ECS | Posters on site | ERE5.2

Deformation bands characterization in porous carbonates: a case study from the Matera High (Southern Italy) 

Giovanni Freda, Silvia Mittempergher, Fabrizio Balsamo, Raffaele Di Cuia, and Angelo Ricciato

Faults and fractures have a crucial role in controlling the permeability in carbonate reservoirs, as they can act as a conduit or barrier for fluid flow. Reservoir-scale outcrop analogue studies provide a useful tool to investigate their spatial distribution and connectivity and to establish the relationships between small-scale structures with larger structures that can be identified in the subsurface.

In this contribution, we describe the preliminary results of a structural study carried out in the Matera's High, South Italy, as an analogue for porous carbonate structures that could be used as CO2 storage fields. Matera High is located on the western side of the Murge region, at the boundary between the Apulian foreland and the foredeep of the southern Apennines thrust belt. It consists of an asymmetrical horst structure involving the Cretaceous carbonates of the Apulian platform (Calcare di Altamura). The Calcare di Altamura is unconformably overlain by Plio-Pleistocene shallow-marine coarse-grained carbonates (Calcarenite di Gravina). The Calcare di Altamura is moderately tilted and is characterised by NW-SE striking normal faults with a throw variable from centimetres to tens of meters. The Cretaceous sequence is also characterised by widespread joints, whose intensity increases approaching faults. The Plio-Pleistocene carbonate succession has very few faults. It is dominated by deformation bands organized into 3 main sets dipping at high angles and striking N-S, NW-SE, and NE-SW. This geological setting allows us to conduct a detailed structural study on an area of about 80 km2, investigating how deformation structures affect the secondary porosity in tight limestone and porous calcarenites. The study was conducted at multiple scales in the field and laboratory and includes (1) geological mapping and structural measurements of faults, fractures and deformation bands; (2) use of linear scan-lines to characterise the deformation bands density across faults; (3) use of photogrammetric techniques to obtain Virtual Outcrop Models (VOMs); (4) development of 3D model based on statistical and topological analysis obtained from scan lines and scan areas in the field and VOMs, (5) petrophysical logging (uniaxial strength, in situ permeability, gamma ray) to highlight the factors that control the formation of the deformation bands, (6) image analysis of blue-resin impregnated thin section and optical cathodoluminescence images, and (7) He-density and Hg-intrusion porosimetry to quantify host rock and deformation bands porosity and pore size distribution.

The preliminary results suggest that the combination of fieldwork, VOMs and laboratory measurements allow the characterization of the deformation bands with more confidence to obtain conceptual and quantitative models about its effects on the fluid flow which can be used for reservoirs characterization for CO2 sequestration.

How to cite: Freda, G., Mittempergher, S., Balsamo, F., Di Cuia, R., and Ricciato, A.: Deformation bands characterization in porous carbonates: a case study from the Matera High (Southern Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9673, https://doi.org/10.5194/egusphere-egu23-9673, 2023.

EGU23-9694 | ECS | Posters on site | ERE5.2

Modelling fluid flow and water-rock interaction in fractured crust using a Discrete Fracture Network approach 

Ibrahim Harb, Fidel Grandia, Paolo Trinchero, and Jeffrey Hyman

Groundwater accounts for around 25% of the world’s fresh water supply. Due to the increasing anthropogenic pressure on shallow aquifers as well as climate change that is impacting global groundwater recharge, there is an increasing need to access deeper groundwater resources, which are frequently hosted in fractured-rock formations. The migration of groundwater (and other types of fluids, in general) in fractured rocks allows the contact between fluids in geochemical disequilibrium with the host rocks (i.e., large geochemical gradients) promoting water-rock reactions inside the fractures. These reactions may influence the permeability and porosity, as well as they may lead to fracture sealing. So, a thorough understanding of the coupled hydro-chemical processing that occur in fractured media is important for applications such as the sustainable exploitation of the afore-mentioned reserves, the protection and remediations of aquifers used for drinking water production or the safety analyses of deep geological repositories for spent nuclear fuel, energy storage, nuclear waste disposal sites, etc.. In fractured rocks, groundwater flows in specific pathways and interacts with the host rock which may lead to the change in the hydro-geochemical conditions. The prediction of these interactions become critical for a proper management of the different applications. Therefore, the understanding and modelling of fluid-fracture interaction is of high scientific and commercial interest.

Using the software dfnWorks, it is possible to model the fluid transport using a non-reactive Lagrangian method (particle tracking). In this contribution, we intend to implement geochemical reactions in dfnWorks to quantify the impact of these reactions in the fracture network. In fact, flow of water through Discrete Fracture Networks leads to interaction between water and the minerals occurring in the fracture plane and thus alters the underlying groundwater flow patterns. Thus, using these DFN-based reactive transport simulations, we aim at predicting the effect that chemical reactions have on flow and channeling. Besides presenting a proof-of-concept set of calculations, we will also present preliminary results of a real-case application, where fracture filling is produced as a result of a chemical imbalance.

How to cite: Harb, I., Grandia, F., Trinchero, P., and Hyman, J.: Modelling fluid flow and water-rock interaction in fractured crust using a Discrete Fracture Network approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9694, https://doi.org/10.5194/egusphere-egu23-9694, 2023.

EGU23-10311 | Orals | ERE5.2

Use of Mohr diagrams to predict fracturing in rock 

David Peacock, Bernd Leiss, and David Sanderson

Inferences have to be made about likely structures and their effects on fluid flow in a geothermal reservoir at the pre-drilling stage. This is the case for the potential geothermal reservoir in Variscan metasedimentary rocks that are expected to occur in the subsurface at Göttingen. Simple mechanical modelling, using reasonable ranges of values for rock properties, stresses and fluid pressures, is used here to predict the range of possible structures that are likely to exist in the sub-surface and that may be generated during thermal and hydraulic stimulation. Mohr diagrams are a useful way for predicting and illustrating how rocks can go from a stable stress state (i.e., no fracturing occurs) to an unstable stress state (i.e., fracturing occurs). This transition can occur if there are changes in: (1) the failure envelope; (2) the stresses; and/or (3) fluid pressure. Mohr diagrams are used to show under what fluid pressures and tectonic stresses different types and orientations of fractures are likely to be reactivated or generated. The approach enables the effects of parameters to be modelled individually, and for the types and orientations of fractures to be considered. This modelling is useful for helping geoscientists consider, model and predict the ranges of mechanical properties of rock, stresses, fluid pressures and the resultant fractures that are likely to occur in the sub-surface.

The Mesozoic rocks of the Somerset coast, UK, are used to illustrate how Mohr diagrams can help understand the history of fracturing. Such understanding is useful for predicting which fractures are likely to occur in the subsurface, which is important for predicting reservoir behaviour.

How to cite: Peacock, D., Leiss, B., and Sanderson, D.: Use of Mohr diagrams to predict fracturing in rock, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10311, https://doi.org/10.5194/egusphere-egu23-10311, 2023.

Pore fluid pressure in the geological formation at depth varies spatially and temporarily. An increase in pore fluid pressure leads to a reduction in effective normal stress and thus affects the rock strength and deformation mode. Extremely high pore fluid pressure induces very low normal stress conditions, where an extension or extension-shear hybrid fractures are formed. To better quantify the stress states and fluid pressure during fracture formation, it is crucial to document mechanical strength and the transition from tensile to shear fracture at low effective stress with elevated pore fluid pressure. However, all previous experimental studies were conducted under dry conditions. Here, we investigate the effects of pore fluid pressure on tensile and hybrid fractures in Berea sandstone by conducting triaxial extension deformation experiments under pore-fluid-pressure controlled conditions at effective maximum principal stress (σ1' = σ1 - Pp, where σ1 is total maximum principal stress and Pp is pore fluid pressure) ranging from 10 to 130 MPa. Fracture strength, inelastic strain, strain at failure, fracture angle to σ1', and the amount of comminution increase with σ1'. The transition of extension to shear fracture occurs at σ1' = ~ 30 MPa, based on the fracture angle and the degree of comminution. All the saturated or pore fluid pressure-controlled test specimens exhibit lower fracture strength than dry samples, and the difference is distinct when the minimum principal stress is tensile (i.e., σ3' < 0). This implies that pore fluid pressure more effectively assists the breakage of the bonds and opening of the microcracks in the extension fracture regime. A series of triaxial extension experiments at σ1' = 20 and 50 MPa with various combinations of σ1 and Pp indicate that the fracture angle to σ1' is independent of σ1 and Pp in the extension fracture regime at σ1' = 20 MPa, and that fracture angle increases with σ1 and Pp in the extension-shear hybrid fracture regime at σ1' = 50 MPa. This implies that the estimation of in-situ stress and pore fluid pressure from natural or human-induced deformation at low effective pressure (such as joints, veins, and drilling-induced tensile fractures) requires careful consideration of the mode of fractures formed.

How to cite: Kitajima, H., Ruplinger, C., and Tilley, C.: Experimental investigations on effects of pore fluid pressure on extension and extension-shear mixed-mode fracture in Berea sandstone, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10433, https://doi.org/10.5194/egusphere-egu23-10433, 2023.

EGU23-10795 | ECS | Posters on site | ERE5.2

Phase field method to model mixed-mode fracturing in fluid saturated porous reservoir 

Swapnil Kar and Abhijit Chaudhuri

                                        Hydraulic fracturing is a useful stimulation technique to create cracks in unconventional reservoirs and enhance the effective fluid transmissivity to recover gas from natural gas reservoirs or heat from geothermal reservoirs. However, due to fracturing the overall strength and load bearing capacity of the reservoir is compromised. This may be a serious concern if the reservoir is below a dam or any other massive structures. In such case significant settlement can take place as the result of mixed mode fracturing inside the reservoir which might already have natural fractures. Phase field method based on the formulation of mixed-mode fracturing has been adopted in the present work for modeling fracture propagation in a saturated porous medium when subjected to fluid pressure and increasing overburden load. A numerical method has been developed using Finite element method (FEM) for solving the displacement and damage field, and Finite volume method (FVM) for solving flow field due to its flux conservative nature which is automatically satisfied for each FVM cell. Our FEM code alone has been first validated for modelling mixed mode fracturing considering a single fracture as a notch against the published experimental and numerical results for elastic medium subjected to compressive load. In this method, the notch does not have any material and computational mesh is refined around the notch as commonly done by others. We have later developed an alternative method where the pre-existing crack is modelled as a fully damaged zone. In this method, a structured and uniform grid can be used to obtain same fracturing pattern and load-deflection curve. The alternative method has a few advantages such as it can be easily applied for reservoir with many cracks without any grid refinement around the pre-existing cracks, and it can be easily coupled with FVM code for modeling fluid flow. Our numerical modelling code is capable to simulate fracturing along with the branching and merging effects. We have simulated load-bearing capacity of a fractured reservoir subjected to increasing overburden load. The reservoir is considered to consists of many randomly oriented but poorly connected natural fractures. The load-bearing capacity and load-deflection curves are compared for reservoirs with and without hydraulic fracturing. The simulations have been performed for different set of natural fractures to understand the effect of fracture density and other fracture network properties on the load-deflection curves.

How to cite: Kar, S. and Chaudhuri, A.: Phase field method to model mixed-mode fracturing in fluid saturated porous reservoir, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10795, https://doi.org/10.5194/egusphere-egu23-10795, 2023.

 Deep geothermal reservoirs are often naturally or hydraulically fractured media which consist of a rock matrix and a network of randomly oriented discrete fractures of different sizes. In the present study, a three-dimensional model of coupled flow, heat transfer and deformation of fractured geothermal reservoir is developed. Because of high thermal expansibility and high mobility, supercritical C02 is under consideration as an alternative fluid to water/brine for extracting energy from geothermal reservoir. However, for simulation of CO2 based EGS, two phase flow model should be included and this makes the coupled model far more nonlinear and complex. FEHM which is one of the most robust code developed at LANL is capable to simulate the multi-physics problem of geosciences. We have found that the computational cost for CO2 based EGS a few times higher than that of water based EGS. Due to temperature drawdown and pressure difference between injection and production wells thermo-poro-elastic stresses are induced within the reservoir. This can influence larger shear dislocation, and normal opening /closing of fracture causing changes in the fracture aperture and permeability during the extraction of the geothermal energy from a reservoir. The correlation of the variation of fracture permeability with the variation of the local stress tensor has been taken into account in this study. To study the permeability alteration on geothermal energy extraction for water and CO2  based EGS different fracture networks, different values of injection temperature and injection pressure are considered. Three-dimensional fracture networks of randomly oriented rectangular fractures with different sizes, and dip angles are created using ADFNE Matlab code. A structured computational mesh is created for simulating the multiphase flow, heat transfer and geomechanics. The nodes belonging to the fractures are assigned appropriate permeability, thermal conductivity and mechanical properties depending on the fracture aperture. The values of these properties are subjected to alteration based on local stress values.

How to cite: Adhikary, S. S. and Chaudhuri, A.: Thermo-poro-elastic stress induced aperture alteration of fractured geothermal reservoir and its effect on geothermal energy production, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10797, https://doi.org/10.5194/egusphere-egu23-10797, 2023.

EGU23-12483 | ECS | Orals | ERE5.2

Mineralogical control on fault friction and stability: a systematic study on quartz, calcite and muscovite ternary mixtures. 

Roberta Ruggieri, Giacomo Pozzi, and Cristiano Collettini

During fault evolution different rock types are fractured and sheared within the fault core, producing fault gouges with heterogeneous mineralogical composition. Mineral composition exerts a primary control on fault frictional properties and hence on fault slip behaviour. Understanding the conditions that lead to seismic or aseismic fault slip is of great interest to earthquake hazard assessment both for natural and induced seismicity. Although the effect of single mineral phases is probably the most documented factor in laboratory tests, no clear link has been established to understand how systematic variation of different mineral phases in gouge mixtures influences the macroscopic frictional behaviour.

Here we present an experimental study designed to probe the control of mineral composition on fault friction and stability responses. We selected three representative mineral phases, commonly found in fault zones, that are known to have severely different frictional properties: muscovite (phyllosilicate), quartz (granular silicate) and calcite (granular carbonate). Thirty double direct shear experiments were performed using a biaxial rock deformation apparatus (BRAVA) on powders (with grain sizes < 125 µm) of pure minerals and their mixtures at normal stress of 50 and 100 MPa, at room temperature and water saturation conditions. After an initial sliding of 10 mm at 10 µm/s to develop a steady state shear fabric, slide‐hold‐slide sequences (30-1000 s) and velocity steps (0.3-300 µm/s) were employed to evaluate static healing and frictional stability, respectively.

Our experimental data indicate that the mineralogical composition of fault gouges significantly affects the frictional strength, healing, and stability with a non-trivial pattern. Increasing phyllosilicate (muscovite) content results in a decrease of the frictional strength, from 0.62 for pure calcite and 0.56 for pure quartz down to 0.33 for pure muscovite powders. This effect is more marked in calcite-rich mixtures rather than quartz-rich ones, possibly due to favourable conditions for fluid-assisted pressure-solution at grain contacts. Calcite-muscovite interaction also favours a reduction of frictional healing and a more marked velocity-strengthening behaviour (promoting stable sliding and fault creep) in comparison to quartz-muscovite mixtures.

How to cite: Ruggieri, R., Pozzi, G., and Collettini, C.: Mineralogical control on fault friction and stability: a systematic study on quartz, calcite and muscovite ternary mixtures., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12483, https://doi.org/10.5194/egusphere-egu23-12483, 2023.

EGU23-13820 | ECS | Orals | ERE5.2

Electric self-potential monitoring of hydraulic fracturing experiments in the Äspö Hard Rock Laboratory, Sweden. 

Nadine Haaf, Luis Guarracino, Damien Jougnot, and Eva Schill

A number of six in situ hydraulic fracturing experiments were carried out at the Äspö Hard Rock Laboratory (Sweden) in 2017 in a depth of 410 m. Here we present electric self-potential monitoring during the conventional and the step-wise cyclic injection experiments HF2 and HF3. Electric self-potential data were acquired through a two-sensor array, each including nine measuring probes and one base probe, that were installed at the 410 m and 280 m levels. The experimental borehole F1 is drilled in the direction of Shmin, perpendicular to the expected fracture plane. The self-potential sensors are installed sub-parallel to Shmin at level 410 at a distance of 50-75 m to the borehole F1 and sub-perpendicular to Shmin at level 280 m at a distance of 150-200 m to F1. The self-potential data were measured with a sampling rate of 1 Hz. Here, we propose a 1-D modelling of the streaming potential that approximates the measured self-potential data. These streaming potential gradients ∆V are estimated from the simulated pressure signals and the coupling coefficient.

How to cite: Haaf, N., Guarracino, L., Jougnot, D., and Schill, E.: Electric self-potential monitoring of hydraulic fracturing experiments in the Äspö Hard Rock Laboratory, Sweden., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13820, https://doi.org/10.5194/egusphere-egu23-13820, 2023.

EGU23-13949 | ECS | Posters on site | ERE5.2

Permeability and Compressibility Evolution of Fractured and Intact Reservoir Rocks from the Blue Mountain Geothermal Field, Nevada 

Valerian Schuster, Erik Rybacki, Anja M. Schleicher, Trenton T. Cladohous, Roshan Koirala, and Thomas H.W. Göbel

Many reservoir rocks of productive geothermal energy resources display low porosity and matrix permeability. Therefore, to enhance fluid flow, fault zones and natural fracture networks are increasingly targeted for geothermal energy exploitation that are hydraulically connected to geothermal wells by stimulating the reservoir units. To this end, fluid is injected into the reservoir, which is generally believed to reduce effective stress and induce minor slip along stressed faults. Fluid injection can also lead to induced microseismicity and remotely-triggered earthquakes at great distances from the target reservoirs. The Blue Mountain geothermal field produces the largest seismic activity during maintenance shutdowns of injection and production requiring additional mechanisms such as poroelastic stress effects. In order to improve seismic hazard assessment and the understanding of induced seismicity around injection wells, we explore the coupling between matrix permeability, fault zone hydrology and mechanical behavior.

One main goal of this work is to provide insight into the scale-dependence of permeability by comparing laboratory results with previous permeability measurements using tidal responses in three different idle wells in Blue Mountain. We present a series of laboratory experiments performed on rock samples collected from the DB2 well at the Blue Mountain geothermal site in Humboldt County, Nevada, USA. The geothermal field benefits from the intersection of two W- and NW-directed normal faults resulting in high permeability of the geothermal reservoir production zone controlled by a brittle damage zone. Samples were obtained from two different lithologies, both of Triassic age, that constitute the reservoir. The first set of samples are low-porosity, (0.4 vol%) quartz-dominated (~50 – 60 wt%) phyllites, which exhibit zones with pronounced fracturing and elevated porosity (3.8 vol%). The second set of samples are felsic intrusive rocks with moderate to high porosity (7 – 15 vol%) due to strong hydrothermal alteration and clay mineral formation. Samples from both lithologies were selected from different sections of the damage zone showing varying degrees of faulting, from intact to highly brecciated, containing mineralized veins. We determine flow and poroelastic properties of cylindrical samples with a length of 2 cm and a diameter of 5 cm, subjected to stepwise cyclic variation of pore (<40 MPa) and confining pressure (<45 MPa). At each pressure step, we measure volumetric strain changes to derive the bulk modulus and effective stress coefficient, and use steady-state or pore pressure oscillation to determine permeability.

In addition to the tidal response and laboratory results, we developed a high-resolution seismicity catalog based on more than three years of continuous waveforms records from 2016 to 2019. We performed template-matching and differential travel-time inversions and use the resulting seismic events with magnitudes between 0.7 – 2.7 to search for seismicity migration patterns associated with discrete injection events. Integration of field and laboratory results can improve the characterization of the permeability structure of the fault zone at Blue Mountain and help to understand the mechanisms that trigger seismic events during production shutdown as well as the role of poroelastic stress release.

How to cite: Schuster, V., Rybacki, E., Schleicher, A. M., Cladohous, T. T., Koirala, R., and Göbel, T. H. W.: Permeability and Compressibility Evolution of Fractured and Intact Reservoir Rocks from the Blue Mountain Geothermal Field, Nevada, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13949, https://doi.org/10.5194/egusphere-egu23-13949, 2023.

EGU23-14955 | Posters on site | ERE5.2

Equivalent Biot and Skempton coefficients for fractured rocks 

Silvia De Simone, Caroline Darcel, Hossein A. Kasani, Diego Mas Ivars, and Philippe Davy

Biot coefficient and Skempton coefficient are key descriptors of the coupled hydro-mechanical (HM) behavior of fluid-saturated porous materials. Biot coefficient defines a relationship between an applied load, fluid pressure and the stress that effectively acts on the solid skeleton. Skempton coefficient defines the temporary pore pressure variation caused by the application of a load in undrained conditions. The product of the two coefficients establishes the impact of an applied load on the solid skeleton, and thus the material deformation, under undrained conditions. The two coefficients are generally estimated through analytical expressions valid for isotropic homogeneous materials, or they are experimentally estimated at the laboratory sample-scale.

In this work, we define a framework for the evaluation of equivalent Biot coefficient and Skempton coefficient at the scale of a fractured rock mass. We derive theoretical expressions that estimate the two equivalent coefficients from the properties of both the porous intact rock and the discrete fracture network (DFN), including fractures with different orientation, size, and mechanical properties. These formal expressions are validated against results from fully coupled hydro-mechanical simulations on systems with explicit representation of deformable fractures and rock blocks. We show that the coefficients largely vary with the fracture orientation and density, which implies that disregarding the presence of fractures may incur an incorrect evaluation of the HM response. We also discuss the variability of the coefficients under different settings of DFN properties, including realistic scaling conditions of size-dependent and stress-dependent fracture properties.

How to cite: De Simone, S., Darcel, C., Kasani, H. A., Mas Ivars, D., and Davy, P.: Equivalent Biot and Skempton coefficients for fractured rocks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14955, https://doi.org/10.5194/egusphere-egu23-14955, 2023.

EGU23-14982 | Orals | ERE5.2

Constraining the impact of cyclic hydraulic stimulation on granites 

Jackie E. Kendrick, Julian Mouli-Castillo, Anthony Lamur, Andrew Fraser-Harris, Alexander Lightbody, Mike Chandler, Katriona Edlmann, Christopher McDermott, and Zoe Shipton

Subsurface engineering, such as geothermal energy extraction, requires knowledge of the rupture of geomaterials. Of particular importance is the time- and rate-dependence of material strength, which impacts fracture architecture and thus hydraulic conductivity and system permeability. Cyclic soft stimulation (CSS) techniques have been developed to maximise the efficiency of resource extraction whilst minimising large amplitude, fluid-injection induced seismicity. Here, we explore the benefits of cyclic stimulation experimentally, utilising novel “pulsed pumping” hydraulic fracture tests in which fluid pressure is cycled within the central borehole of a suite of 20x20cm cylinders of dense granite. The response is monitored at high-resolution by fibre-optic circumferential strain measurements, fluid pressure data and acoustic emission recording. Using cyclic high-low pressure square waves, we found that breakdown pressure was reduced by up to 15% compared to the monotonic case in which pressure was increased by applying a constant flow rate. Whilst peak pressure had the primary control on the number of cycles to failure, increasing the minimum pressure in the borehole (thus increasing mean pressure) further reduced breakdown pressure, suggesting that even small pressure fluctuations during hydraulic stimulation may reduce the largest stress drops, and hence the magnitude of induced seismic events. Strain measurements detected accelerating precursory deformation a few cycles prior to failure, hinting at the opportunity for responsive stimulation practices where activity can be monitored in real-time. These novel large-scale, high-resolution experiments were complemented by indirect tensile measurements at a range of strain rates, and by cyclic fatigue Brazilian disc testing at a range of peak loads and cycle amplitudes. These results further highlight the increasing contribution of time-dependent deformation during slower and cyclic loading, resulting in lower peak loads and reducing large magnitude fracturing events. The generated S-N curves demonstrate that weakening by cyclic hydraulic pressurisation mimics relationships defined by conventional fatigue testing of geomaterials. Such experimental constraints will be of great benefit to the development of cyclic stimulation practices for subsurface engineering.

How to cite: Kendrick, J. E., Mouli-Castillo, J., Lamur, A., Fraser-Harris, A., Lightbody, A., Chandler, M., Edlmann, K., McDermott, C., and Shipton, Z.: Constraining the impact of cyclic hydraulic stimulation on granites, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14982, https://doi.org/10.5194/egusphere-egu23-14982, 2023.

EGU23-15424 | ECS | Posters on site | ERE5.2 | Highlight

Structural evolution in the northern Ruhr basin: A case study of urban geothermal exploration in the Münsterland Region 

Vladimir Shipilin and Manfred Dölling

The geothermal potential in the deep subsurface of North Rhine-Westphalia (NRW) has been scarcely explored. Due to the increasing demand for zero-carbon heating applications, there has been a renewed phase of seismic exploration in the region to investigate potential geothermal aquifers. The prime exploration target is the Lower Carboniferous Ruhr Basin and the Devonian substratum of the Variscan foreland, as they host deep carbonate aquifers. Interpretation of the recently-acquired 70-km-long 2D seismic profiles, together with the 2D legacy seismic data in the northern part of the Ruhr basin, the Münsterland region, reveals two carbonate units; the Dinantian platform facies and the Givetian massive facies. These are located at depths that range from c. 4500 m to 6000 m. Considering their great burial depth, the permeability of the carbonate rocks is considered to be primarily facilitated by fault zones with dense fracture swarms. Therefore, understanding the complex deformation history of this fossil foreland basin is crucial to evaluate its geothermal potential. We here reveal the timing and geometric evolution of the fault zones. Using a multiattribute seismic analysis, we delineate three major types of faults; (1) SW–NE-⁠trending, syn-fold thrusts, (2) WNW–ESE-striking normal faults, and (3) E–W and N–S strike-slip faults. Interestingly, we do not observe in the available data flexure-induced faults that are typical for foreland basins and would be expected to strike parallel to the SW–NE-oriented Variscan Orogen. To constrain the relative timing of fault activity, we mapped seven well-constrained and age-calibrated stratigraphic horizons within the Carboniferous molasse sequence and the Cretaceous cover. The preliminary results confirm the observations of previous researchers that the thrust faults formed after the deposition of the Late Carboniferous strata, as evidenced by their concordant folding. Thrusts are crosscut by the normal faults, suggesting that the latter formed at a subsequent stage. Most of the strike-slip faults cut through the Carboniferous–Cretaceous unconformity, with some culminating in the Cretaceous cover as positive flower structures. Notably, one flower structure is co-linear with a thrust fault in the Carboniferous, suggesting that there is some degree of kinematic linkage between the two structural levels. Possibly, some of the optimally-oriented thrusts were reactivated and grew upward as strike-slip faults during Late Cretaceous transpression. Such multiphase evolution of fault zones may enhance permeability structure, since each reactivation event potentially contributes to the widening of the deformation zones, thereby increasing the density of interconnected fractures. In this study, we demonstrate how the integration of new seismic data provides valuable insights into the structural evolution of the Ruhr Basin and its geothermal potential. A 3D seismic acquisition campaign is planned in the investigated region. Using its results, we intend to conduct a high-resolution fault throw analysis to further constrain the kinematic development of the deformation structures.

How to cite: Shipilin, V. and Dölling, M.: Structural evolution in the northern Ruhr basin: A case study of urban geothermal exploration in the Münsterland Region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15424, https://doi.org/10.5194/egusphere-egu23-15424, 2023.

Previous hydrocarbon exploration in the Ordos, Tarim, and Sichuan basins of China has indicated that strike-slip faults play an important role in controlling reservoir distribution. High hydrocarbon production within strike-slip fault zones in these basins indicates that the fault zones not only act as conduits or seals for hydrocarbon migration, but also provide space for hydrocarbon accumulation. The productivity of different wells, however, can vary within one strike-slip fault zone, suggesting that variability in fault zone architecture controls hydrocarbon enrichment. To date, very few studies have explored fault zone architecture in the southern Ordos Basin, inhibiting oil exploration and development. We explored faults in the Jinghe Oilfield in the southern Ordos Basin by integrating outcrops, wellbore cores, well logs, and 3D seismic data. We carried out fault segmentation, qualitative characterization of fault zone architecture, and quantitative characterization of the boundary between the damage zone and wall rock. The results showed that fault zone architecture is complicated by fault segmentation, architectural configuration, and damage zone asymmetry. Strike-slip faults can be divided into transtensional, strike-slip, and transpressional segments along the fault strike, with transtensional and strike-slip segments dominant in the Jinghe Oilfield. Each segment is further complicated by different configurations of gouge, breccia, and fracture zones along the fault dip. Compared with the strike-slip segments, transtensional and transpressional segments showed more complexity, with the fracture density and damage zone width of the hanging wall being greater than that of the footwall. Transtensional segments with braided and horsetail structures showed more complexity owing to the presence of multiple fault cores and damage zones around the main fault and its subsidiary faults. Quantitative analysis showed that the fault zone width was the greatest for transtensional segments, intermediate for transpressional segments, and the lowest for strike-slip segments. We determined a positive linear relationship between the relative widths of the fault core and fault zone. The cavities in breccia zones and fractures in damage zones provide conduits and storage space for hydrocarbon migration and accumulation. We conclude that damage zones in transtensional segments, particularly in the hanging wall, are primary potential targets for petroleum exploration and development.

How to cite: Meng, Y., Chen, H., Luo, Y., Zhao, Y., Tang, D., and He, F.: Architecture of intraplate strike-slip fault zones in theYanchang Formation, Southern Ordos Basin, China: Characterizationand implications for their control on hydrocarbon enrichment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17164, https://doi.org/10.5194/egusphere-egu23-17164, 2023.

EGU23-17201 | Orals | ERE5.2

Micro-Continuum Modelling of Coupled Hydro-Bio-Chemical MICP Processes in Fractured Rock 

Guijie Sang, Rebecca Lunn, Grainne El Mountassir, and James Minto

Subsurface storage of CO2 and retrievable green energy (i.e. compressed air and hydrogen) in depleted gas reservoirs, deep saline aquifers and salt caverns, are considered as key transitions within the energy sector to enable many countries to meet their net zero carbon emissions targets. One of the main challenges in underground storage is the presence of potential leakage pathways (such as caprock fractures/faults) which pose a threat to economic feasibility and to the environment. Seeking an efficient technique to remediate leakage pathways is crucial to guarantee sealing efficacy. Microbially induced carbonate precipitation (MICP) is regarded as a promising bio-grouting technique for leakage remediation due to its advantages such as the low water-like viscosity and micron-size microbes, which enables permeation far from the injection point and excellent penetration into fine aperture fractures.

MICP utilizes ureolytic bacteria, commonly Sporosarcina pasteurii (S. pasteurii) to produce highly active urease enzyme, which can catalyze urea hydrolysis and result in the production of carbonate ions. Carbonate precipitation occurs if a calcium source is supplied, which can effectively remediate leakage by filling void space and improve strength by bonding solid grains.

We propose a micro-continuum model which accounts for the coupled hydro-bio-chemical MICP processes in fractured porous rock. In this micro-continuum model, the flow is controlled by the Darcy-Brinkman-Stokes equation over a number of control volumes (i.e. voxels based on X-ray CT scan). The kinetic parameters of urea hydrolysis and calcium carbonate precipitation are calibrated based on batch experiments. The bacteria deposition parameters, which feature the bacteria deposition in fractured rock, are calibrated based on experimentally measured bacteria breakthrough curves in a 1-dimensional column filled with fracture gouge materials. The proposed micro-continuum model can well represent the decreases in porosity and permeability of an artificially-cut anhydrite fracture filled with anhydrite gouges under MICP treatment cycles. Our modelling results also suggest that when the CaCl2 concentration is equal to or higher than the urea concentration in the injected cementing solution, the rate of microbially induced carbonate precipitation is predominantly limited by the kinetics of urea hydrolysis rather than the kinetics of calcium carbonate precipitation. The proposed micro-continuum model serves as a useful tool for evaluating MICP treatment strategies and may be upscaled to predict and optimise field-scale leakage remediation.

How to cite: Sang, G., Lunn, R., El Mountassir, G., and Minto, J.: Micro-Continuum Modelling of Coupled Hydro-Bio-Chemical MICP Processes in Fractured Rock, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17201, https://doi.org/10.5194/egusphere-egu23-17201, 2023.

EGU23-42 | Posters virtual | ERE5.5

Genesis and Origins of Natural Gas in Eastern Belt around Penyijingxi Sag in Junggar Basin, NW China 

Keshun Liu, Jiangxiu Qu, Ming Zha, and Xiujian Ding

Abstract: The Junggar basin is sandwiched between the Siberian plate, the Kazakhstan plate and the Tarim plate, and is an important part of the Central Asian orogenic belt. Based on the comprehensive analysis of the characteristics of the natural gas composition,carbon isotope, light hydrocarbons and source rocks in the eastern belt around Penyijingxi Sag, Junggar Basin, i.e., our studied area, the genesis and origins of natural gas in this area are discussed. The natural gases in the eastern belt around Penyijingxi Sag, are dominated by alkane gases, and have relatively low contents of heavy hydrocarbons and non-hydrocarbons. Methane is dominant in alkane gas, with volume fraction varies from 70.36% to 93.34%. In non-hydrocarbon gas, the volume fraction of nitrogen varies from 0.69% to 11.95%, and the volume fraction of carbon dioxide varies from 0 to 1.49%. The values of δ13methane(C1), δ13ethane(C2), δ13propane(C3) and δ13butane(C4) of natural gas are in the ranges from −45.57‰ to −31.19‰, −31.69‰ to −24.66‰, −28.76‰ to −23.56‰, −27.96‰ to −23.64‰, respectively. The overall carbon isotopic composition of the alkanes shows a trend as δ13C1 < δ13C2 < δ13C3 < δ13C4, and all δ13C1 values are ≤ -30‰, which are typical of gases of organic origin. The methane and ethane isotopic compositions and the characteristics of light hydrocarbons show that the natural gases in the studied area are dominated by coal-type gas and contain a small amount of oil-type gas. Specifically, the coal-type gas is from the mature to highly mature source rocks of the Lower Urho Formation, and the oil-type gas is from the mature to highly mature source rocks of the Fengcheng Formation. Analysis of gas migration parameters show that, while there was no significant lateral migration of natural gas in the studied area, natural gases once migrated vertically and resulted in the mixing of oil- and coal-type gases as well as the mixing of alkane gases of the same genetic type formed at different stages, which should be the cause of observed reversed carbon isotopic series. The diffusion and migration of carboniferous oil and gas after reservoir formation have led to differences in gas geochemical characteristics among gas wells in this area, which may provide important information for oil and gas exploration in the central Junggar Basin.

Keywords: Junggar Basin; geochemistry; natural gas genesis; carbon isotopes; light hydrocarbons

How to cite: Liu, K., Qu, J., Zha, M., and Ding, X.: Genesis and Origins of Natural Gas in Eastern Belt around Penyijingxi Sag in Junggar Basin, NW China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-42, https://doi.org/10.5194/egusphere-egu23-42, 2023.

EGU23-1111 | ECS | Orals | ERE5.5

Reaction-assisted fracture propagation: An application to carbon storage 

Santiago Pena Clavijo, Mouadh Addassi, Thomas Finkbeiner, and Hussein Hoteit

Understanding fracture propagation in chemically active rock formations is of interest to several engineering and science disciplines. Fracture nucleation and growth governed by in-situ chemo-poro-mechanical processes is crucial, for instance, during the transformation of CO2 into solid carbonate rock. The process consists of injecting a non-resident mixed fluid phase of CO2 in water which dissolves parts of the fracture-porous medium system and precipitates secondary minerals, altering the solid’s porosity and permeability. Hence, dissolution/precipitation processes and concomitant solid weakening alter physico-chemical properties in the system, which in the presence of pore pressure changes, may facilitate and enhance fracture nucleation and growth. More importantly, the evolution of fracture networks in the rock determines fluid flow, which is crucial for progressing chemical processes such as ionic advection and diffusion. This study focuses on the complex chemo-hydro-mechanical responses in naturally fractured rock formations subject to acidic carbon water injection. We use a recently developed framework to incorporate the mechanisms of reactive transport, fluid flow and transport in porous media, and fracture propagation in poroelastic media. Due to the complexity of such coupled phenomena, few numerical modeling and experimental studies have been published in this area. Existing models often oversimplify the chemical interactions by using simplistic fitting functions. Contrary to these conventional approaches, the considered framework uses PHREEQC to estimate the localized chemical interactions for a general system. A key novelty of this study is in applying the considered framework to study CO2 injection into complex naturally fractured basalt formations.

How to cite: Pena Clavijo, S., Addassi, M., Finkbeiner, T., and Hoteit, H.: Reaction-assisted fracture propagation: An application to carbon storage, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1111, https://doi.org/10.5194/egusphere-egu23-1111, 2023.

EGU23-1120 | ECS | Orals | ERE5.5

Hydro-mechanical modeling of swelling processes in clay–sulfate rocks: comparison of swelling laws 

Reza Taherdangkoo, Najib Mahfuzh Abdallah, and Christoph Butscher

Swelling of clay-sulfate rocks is a serious problem in geotechnical projects. In Staufen (a city in Baden-Württemberg, Germany), the heave of the land surface occurred as a result of clay-sulfate rock swelling, triggered by water inflow in Triassic Grabfeld Formation (formerly Gipskeuper = “Gypsum Keuper”). Clay-sulfate swelling is controlled by clay swelling due to osmotic processes, combined with chemical swelling due to the transformation of anhydrite into gypsum, associated with a volume increase. Previous studies showed that hydro-mechanical (HM) models can be employed to determine the mechanical behavior of swelling rocks with an accuracy sufficient for planning remedial measures. In such models, a constitutive relation between swelling pressure (stress) and swelling deformation (strain) must be defined (“swelling law”). In the present study, we developed coupled HM models to reproduce the heave observed at the Staufen site. We implemented different swelling laws, namely linear, semi-logarithmic, and sigmoidal constitutive relations between stress and strain. We compared the model calculations with the measured long-term heave records at the study site. We then analyzed the errors associated with each modeling approach to evaluate its effectiveness. This contribution provides insights about the performance of three existing swelling laws to estimate the long-term mechanical behavior of clay-sulfate rocks.

How to cite: Taherdangkoo, R., Mahfuzh Abdallah, N., and Butscher, C.: Hydro-mechanical modeling of swelling processes in clay–sulfate rocks: comparison of swelling laws, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1120, https://doi.org/10.5194/egusphere-egu23-1120, 2023.

EGU23-1338 | Orals | ERE5.5

A new functional form of the heat transfer coefficient for use in simulating EGS processes at the field scale. 

christine Detournay, Zorica Radakovic-Guzina, and Branko Damjanac

Heat extraction by circulating a cold fluid in a hot fractured rock mass at depth is the central topic of study in geothermal engineering. Typical reservoir rocks have a low thermal conductivity, and heat exchange between rock and fluid occurs in a thin region, adjacent to the fracture, where the temperature gradient is very high. Capturing this effect is important for accurate predictions of transient fluid temperatures — a critical aspect of geothermal power systems.

The model assumes a temperature jump at the rock/fracture-fluid contact (collapsed boundary layer), and Newton’s law of cooling

qcv = h (Trock -Tfluid )                                                                                                                            (1)

is used to express the heat exchanged by forced convection between media. The heat transfer coefficient, h has a significant impact on the results of EGS numerical modeling. A pragmatic expression is proposed whereby h is proportional to the rock thermal conductivity, kr and inversely proportional to the square root of the product of rock diffusivity, κ, and fluid injection time, t (Detournay C. et al., 2022):

     h = kr / (β√κt)                                                                                                                                (2)

The novelty is that h is primarily a function of rock thermal properties and only indirectly dependent of fracture fluid velocity. Also, Eq. (1) combined with Eq. (2) is the thermal equivalent of Carter’s equation for 1D leak-off flow. The logic, combined with heat advection-forced convection, is implemented in the commercial hydraulic fracturing code XSite and coupled with mechanical, fracture flow, and heat conduction.

Borehole injection of cold water in a penny-shaped pre-existing fracture with a 100 m diameter is simulated. Fluid extraction occurs at constant downhole pressure. Fluid-thermo-mechanical coupling is considered.


 Figure 1. Fluid temperature contour (°C) at 1 year.

Fluid temperature contours in Figure 1 show an oval cooled-off region surrounding the injection well and a “dead zone” near the producing well where the fluid temperature stays close to the warm original (rock) value. The warm fluid, initially present in the thin fracture, is produced and rapidly replaced by the injected fluid. The fluid temperature gradient between wells is caused by the migration of heat from rock to fluid.

REFERENCE

Detournay C., Damjanac B., Torres M., Cundall P., Ligocki L., Gil, I., 2022. Heat advection and forced convection in a lattice code – Implementation and geothermal applications. Rock mechanics Bulletin I (2022) 100004.

 

How to cite: Detournay, C., Radakovic-Guzina, Z., and Damjanac, B.: A new functional form of the heat transfer coefficient for use in simulating EGS processes at the field scale., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1338, https://doi.org/10.5194/egusphere-egu23-1338, 2023.

EGU23-1958 | ECS | Orals | ERE5.5

A Hydro-Mechanical Analytic Element Model for Seepage Forces 

Erik Toller and Otto Strack

Understanding the behavior of hydro-mechanical processes is a challenging task, and groundwater plays an important role in these. We separate the effect of groundwater into two main parts: the pore pressure and the seepage force. Our interest is in the latter part, where we develop a model that incorporates analytically seepage forces in a linear elastic model. This is work in progress; we present our latest developments, focusing on both the theoretical framework and application.

The approach is a further development of the Analytic Element Method, which, was recently extended to linear elasticity. We link a groundwater analytic element to a linearly elastic one, including the seepage forces directly in the equation of the linear elastic model. We initially limit the model to one-way coupling and exclude the effect of stresses and strains on the hydraulic conductivity.

We present an application where we isolate the impact of the seepage force on the mechanical model focusing on situations where we expect a large pressure gradient.

How to cite: Toller, E. and Strack, O.: A Hydro-Mechanical Analytic Element Model for Seepage Forces, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1958, https://doi.org/10.5194/egusphere-egu23-1958, 2023.

The Kızıldere geothermal field, located in the eastern part of the Büyük Menderes Graben, is one of the most productive geothermal systems in Western Anatolia (Türkiye). Electricity production in the field, which began in 1984, is still ongoing with three flash type geothermal power plants.

Four geothermal reservoirs with different rock compositions and geochemical characteristics have been identified in Kızıldere geothermal system. Steam production has changed over time from a shallow reservoir to the hottest deep reservoirs in the system. In the steam phase, CO2 is the dominant gas type in the Kızıldere geothermal system, with concentrations ranging from 98% to 99%. The 13C analyses revealed that the primary source of CO2 is Paleozoic aged metamorphics and that the origin of CO2 is primarily reservoir carbonate dissolution. The deep reservoir contains sulfate, sulfide minerals, dissolved sulfate, dissolved sulfide (HS-), H2S gas, and organic sulfur compounds. Sulfate in thermal waters could be caused by gypsum dissolution or the oxidation of sulfides such as pyrite and pyrrhotite.

In this study, the possibilities of reducing H2S and CO2 emissions by chemical and biological methods were investigated, taking into account the characteristics of the Kızıldere geothermal system. For this purpose, field tests were carried out with 6 different solutions  and the selected bacteria to examine the reduction of non-condensable gases in the Kızıldere geothermal field.

How to cite: Tut Haklıdır, F. and Şengün Çetin, R.: Geochemical Characteristics of the Kızıldere Geothermal System (Turkey) and a Case Study for Emission Reduction in the Kızıldere Geothermal Field, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2037, https://doi.org/10.5194/egusphere-egu23-2037, 2023.

The use of Enhanced Geothermal Systems (EGS) has been recognized as a viable source of renewable energy in regions with high geothermal temperatures. Nevertheless, geothermal reservoirs may experience reduced permeability during exploration or operation. Research on chelating agents in geothermal environments has been widely disseminated as a complementary method to conventional methods such as hydraulic and chemical stimulation. Previous studies reported fast and significant improvements in permeability in granitic and volcanic rocks using aqueous solutions of glutamic L-diacetate acid (GLDA) under acidic conditions. However, no studies have been conducted with chelating agents applied to volcanic rocks at different pH conditions, since pH determines the ionic species in the solution, and thus, the chemical interactions taking place in a system. Furthermore, the dissolution of minerals in these conditions was not quantified for modeling purposes. In the present study, an aqueous solution of the chelating agent GLDA at various pH conditions (2-10) was applied to improve the permeability of single-fractured intermediate to basic volcanic rocks. According to the results, permeability increases about up 4.3-fold under weak acid (pH 4) conditions, while it increases about 36-fold under alkaline (pH 10) conditions, due primarily to the formation of voids caused by mineral dissolution or groundmass dissolution, respectively. Moreover, channeled samples with mirror-conditions revealed that the formation of voids at acidic conditions was as deep as 135 µm by the selective dissolution of hematite, whereas an average of 4-µm dissolution of quartz was promoted at alkaline conditions. Although the depth of voids formed in alkaline conditions is less than the case of acidic, quartz composes the matrix that surrounds the phenocrysts of volcanic rocks, promoting a preferential fluid path that improved the permeability further at alkaline conditions. This study is the first step in spreading the use of this chemical stimulation technique to different volcanic-rock geothermal systems.

Keywords: EGS, chelating agents, permeability enhancement, andesitic rock, selective dissolution of minerals.

How to cite: Salalá, L., Argueta, J., Watanabe, N., and Tsuchiya, N.: pH dependence of mineral dissolution and permeability enhancement of intermediate to basic volcanic rocks by chelating agent flooding under geothermal conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3131, https://doi.org/10.5194/egusphere-egu23-3131, 2023.

EGU23-3513 | Posters on site | ERE5.5

Predicting swelling pressure of bentonite and bentonite mixtures using various machine learning approaches 

Muntasir Shehab, Reza Taherdangkoo, and Christoph Butscher

Bentonite and bentonite mixtures are used as buffer material for deep geological radioactive waste repositories. The swelling behavior of bentonite is an important property influencing the long-term safety of the barrier system by its self-sealing effect. The proper determination of bentonite swelling pressure is vital to ensure that geological repositories remain intact. In this study, a total of 305 data samples on bentonite swelling pressure was collected from the literature. Corresponding soil properties were montmorillonite content, liquid limit, plastic limit, plasticity index, initial water content, and dry density. We employed various machine learning algorithms, namely feed-forward and cascade forward neural networks, regression tree, regression tree ensembles, Gaussian process regression, and support vector machines to determine the maximum swelling pressure of unsaturated bentonite and its mixtures. The cascade-forward neural network (CFNN) produced the best overall performance, i.e. the lowest modeling deviations from the experimental swelling pressure values. Furthermore, we present two simplified CFNN models that depend on two (montmorillonite content and initial dry density) and three (montmorillonite content, initial dry density, and plasticity index) variables to estimate bentonite swelling pressures. These simplified models can to be used as alternatives in instances of limited data availability.

How to cite: Shehab, M., Taherdangkoo, R., and Butscher, C.: Predicting swelling pressure of bentonite and bentonite mixtures using various machine learning approaches, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3513, https://doi.org/10.5194/egusphere-egu23-3513, 2023.

Fractures such as joints and faults are widely present in crustal rocks. These discontinuity structures often form complex networks and dominate the bulk behaviour of geological media. Thus, understanding how fracture networks affect multiphysical processes and phenomena in subsurface rock formations is highly relevant to many geoenergy and geoengineering applications. However, the large-scale behaviour of fractured rocks consisting of many fractures cannot be derived by simple applications of the knowledge of single fractures, due to the hierarchy of scales, heterogeneities, and physical mechanisms as well as the possible emergence of qualitatively different macroscopic properties. In other words, macroscopic phenomena in fractured media arise from the many-body effects of numerous interacting fractures, such that the emergent properties at the fracture network scale are much richer and often surprising compared to the behaviour of each individual fracture. So, more is different!

To study this problem, I have developed a novel physics-based discrete fracture network modelling framework to simulate seismo-thermo-hydro-mechanical-chemical processes in fractured rocks. This modelling approach faithfully honours the discontinuous nature of geological media via explicit representations of fracture populations in rock and numerically computes multiphysics processes by solving the governing equations of fundamental mechanics. No a priori assumption about the representative elementary volume is needed, rendering this approach as an appropriate tool to study hierarchical crustal rocks that may have no characteristic length scale. Using this modelling paradigm, diverse macroscopic phenomena are spontaneously captured as emergent properties physically arising from the collective behaviour of a large population of existing/growing fractures in rock.

In this presentation, I will illustrate the richness of collective phenomena in fractured media and elucidate the underlying multiscale, multiphysical mechanisms that drive their emergence. I will also show some application examples of using this fractured media simulation framework to address subsurface engineering problems such as underground excavation, injection-induced seismicity, and nuclear waste disposal. The modelling framework established and research findings obtained have important implications for safe and sustainable development of geoenergy and geoengineering.

How to cite: Lei, Q.: More is different: On the emergence of collective phenomena in fractured geological media, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3770, https://doi.org/10.5194/egusphere-egu23-3770, 2023.

When CO2 is injected into the saline aquifer or depleted reservoir for geological carbon storage, physical processes are tightly coupled, affecting CO2 flooding and its trapping mechanisms.

For example, injection induces pore pressure build-up and dilation of pore space, which can uplift the ground surface or tensile/shear failure of the caprock which may result in the leakage of CO2. Thus, rigorous analyses of coupled flow and geomechanics are necessary to predict the long-term security of geological carbon storage. In this study, we focus on two irreversible (path-dependent) processes that are coupled through flow and geomechanics: hysteretic capillary pressure in flow and elastoplasticity in geomechanics. Hysteresis in capillary pressure during drainage and imbibition processes can be seen as mechanical energy dissipation. We employ our previously proposed numerical model based on the 1D elastoplasticity algorithm for constitutive relation of the hysteretic capillary pressure in two-phase flow, i.e., capillary pressure and irreducible water saturation. In particular, we model the irreducible (plastic) water saturation being attributed to the part from the hysteretic capillary pressure, which yields a mathematically well-posed problem. We implement the irreversible flow and geomechanics simulation, calculating the residual saturations and plastic strain from each iteration of flow and geomechanics, as we employ the fixed-stress sequential method solving coupled flow and geomechanics.

From the numerical experiments, we find robust computations of the coupled processes, highlighting the coupled effects of capillary hysteresis and elastoplasticity. As residual/capillary and structural trappings are major trapping mechanisms for CO2 geological storage, the proposed constitutive relation and algorithm for coupled path-dependent processes can predict flooding and trapping of CO2 underground more accurately.  

How to cite: Yoon, H. C. and Kim, J.: Numerical Modeling of Capillary Hysteresis and Coupled Elastoplasticity for Geological Carbon Storage, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4700, https://doi.org/10.5194/egusphere-egu23-4700, 2023.

EGU23-4965 | Posters on site | ERE5.5

Experimental study of CO2/CH4 distribution in shale rock samples during adsorption/desorption reaction by low-field NMR 

Taewoong Ahn, Young-ju Seo, Changhyup Park, hyunjoong Lim, and Dong Hyun Kim

Shale is attracting more attention than ever because it can act as a cap rock for CO2 storage as well as a source rock for hydrocarbon resources known as shale gas. In particular, it has been known that the enhanced gas recovery (EGR) technology that enhances the recovery of CH4 by injecting CO2 can be applied to shale gas production. Gas in shale is known to exist in phases of free gas and adsorbed gas, and the adsorption tendency of CO2 is higher than that of CH4. Because of these unique characteristics, CO2 injected into shale induces desorption of CH4 (natural gas production) and remains in adsorbed phase (CO2 storage) at the same time. In other words, shale can also serve as a CO2 storage site. Since shale has a complicated pore structure and a very small pore size, research on the fluid flow or CO2-CH4 adsorption-desorption mechanism within shale has not been well investigated yet.

In this experimental study, Low-field NMR was used to analyze the characteristics of NMR signals of gases present in shale and how they change according to various gas pressures. In addition, the CO2-CH4 adsorption-desorption mechanism was analyzed by observing how the signal characteristics due to adsorption and desorption change as CO2 was injected into a shale sample saturated with CH4 gas. Through this study, it was confirmed that the NMR signal obtained from shale sufficiently reflects the phase and amount of gas, and that the progress of the adsorption-desorption reaction can be quantitatively analyzed. The results of this experiment can be used as important analytical data to understand the behavior of gas in shale, which is essential for shale gas recovery enhancement and CO2 storage.

How to cite: Ahn, T., Seo, Y., Park, C., Lim, H., and Kim, D. H.: Experimental study of CO2/CH4 distribution in shale rock samples during adsorption/desorption reaction by low-field NMR, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4965, https://doi.org/10.5194/egusphere-egu23-4965, 2023.

EGU23-6711 | ECS | Posters on site | ERE5.5

Sensitivity analysis of model parameters for geothermal energy applications in deep mines of thermal-hydraulic-mechanical coupling of spatially heterogeneous settings 

Le Zhang, Thomas Hermans, Alexandros Daniilidis, and Anne-Catherine Dieudonné

With the increasing demand for mineral and alternative energy resources, as well as the gradual depletion of shallow resources, the exploitation and utilization of mineral resources and geothermal energy in deep strata is an effective way to solve the problem of resource shortage. In recent years, as a new type of resource mining mode, the co-mining of deep mineral and geothermal energy has developed rapidly. This method is effective in solving the of deep mines and can also provide convenience for geothermal exploitation with the help of the original equipment of the mine. However, in deep mines, the interaction of high temperature, high geomechanical stress and high-water pressure might lead to rock failure because of the co-mining of mineral and geothermal resources. The huge uncertainty of underground parameters also makes the engineering environment difficult to predict.

We have established a Thermal-hydraulic-mechanical coupling framework of co-mining of deep mineral and geothermal energy considering uncertainty in the model parameters including porosity, rock permeability, thermal parameters (heat capacity and heat conductivity), Young's modulus and their spatial heterogeneity, as well as boundary condition. 500 samples were generated within the prior uncertainty ranges, by means of Monte Carlo simulations, and simulated the spatial and temporal distribution of the temperature, pressure and principal stresses field for each sample with COMSOL. Using the distance-based global sensitivity analysis, the most sensitive parameters for deep mining are identified, and the heat storage capacity of the system is evaluated, including uncertainty.

How to cite: Zhang, L., Hermans, T., Daniilidis, A., and Dieudonné, A.-C.: Sensitivity analysis of model parameters for geothermal energy applications in deep mines of thermal-hydraulic-mechanical coupling of spatially heterogeneous settings, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6711, https://doi.org/10.5194/egusphere-egu23-6711, 2023.

EGU23-6889 | ECS | Posters virtual | ERE5.5

Exploiting induced carbonate precipitation to improve reservoir storage integrity and geothermal system efficiency 

Philip Salter, Katherine Dobson, James Minto, and Jay Warnett

Biomineralization, through microbially, thermally, or enzyme induced carbonate precipitation (MICP/TICP/EICP), is a naturally occurring and inexpensive cementation process that can seal microfractures and pore throats that are inaccessible to cement and chemical based grouts. The porosity, permeability and thermal conductivity of porous geomaterials can therefore be controlled.

This project aims to determine the optimal compositional and injection parameters for biomineralization fluids in a range of subsurface applications relating to the low carbon energy transition. These include, improving the subsurface storage integrity of CO2 and H2 by reducing permeability around poorly sealed legacy wells, enhancing mineral trapping of geo-sequestered CO2, and improving the thermal performance of well casings and ground around low-high geothermal and thermal energy storage systems. We also assess the real time response of bio-cemented samples to harsh environmental conditions representative of those in the subsurface.

Understanding the interactions between geochemical reactions and the transport properties of fluid at the reservoir scale first requires biomineralization experiments to be carried out at the pore (micron) scale. These studies are essential for understanding principles of crystal formation, growth and hydrodynamic feedback mechanisms. Using real-time in situ x-ray computed tomography, the complex and synergistic factors involved in the biomineralization process can be better understood. Correlation of microstructural and macroscopic properties during repeated precipitation and dissolution events will allow refinement of larger scale reactive transport models that assess the suitability of different injection strategies.

Carbon Capture and Storage: The ability to create large, and spatially targeted low permeability regions could be a key tool in preventing leakage of geo-sequestered CO2 (and H2), as well as improving/restoring CO2 injectability and sweep efficiency. During 2-phase EICP a poor choice of injection angle and flow rate can inhibit the mixing of precipitation fluids, and therefore the efficiency of permeability reduction within a porous medium. The challenge of getting 2 fluids to mix uniformly in a tight pore space is only likely to get worse in high pressure, low permeability real world systems. We explore single-phase thermally-delayed, and pulsed EICP injection strategies that encourage better mixing within heterogeneous real-world systems. Injection cycles are repeated multiple times to target the larger (order of magnitude) reductions in permeability required to alter the flow behaviour of CO2 and other gases.

Thermal: Cement and bentonite based grouts typically have low thermal conductivities (<1 W/m K), which is detrimental to subsurface heat exchange. They often form a poor seal at the host rock/soil interface which can increase interfacial resistance. Minerals formed by MICP at the contacts between soil grains can greatly increase the thermal conductivity of the ground, particularly in unsaturated conditions. We explore enhancing this effect further with inclusion of highly conductive additives. For thermal energy storage applications specific heat capacity can also be increased with integration of phase change materials. By developing these specialized geothermal grouts/backfill, shallower boreholes may be required, greatly reducing cost.

The findings of this project have profound implications on the commercialization of engineered biomineralization, and its role in the subsurface energy transition.

How to cite: Salter, P., Dobson, K., Minto, J., and Warnett, J.: Exploiting induced carbonate precipitation to improve reservoir storage integrity and geothermal system efficiency, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6889, https://doi.org/10.5194/egusphere-egu23-6889, 2023.

EGU23-7185 | ECS | Orals | ERE5.5

Fluid-rock interaction of Wolfcamp Shale: the effects of pore structure and mineralogy 

Chen Zhao, Qinhong Hu, Qiming Wang, Majie Fan, Jan Ilavsky, and Min Wang

Shale has been focused because of its potentials in fossil fuel as unconventional reservoirs and in carbon storage as cap rocks. Fluid rock interaction is important for shale study. Because hydraulic fracturing in unconventional oil and gas development and the sealing ability of cap rock are all related to the fluid-rock interaction. The fluid-rock interactions,  such as the spontaneous imbibition (SI), were studied on Wolfcamp Shale core samples in Midland Basin, west Texas in this work. Multiple experiments including X-ray diffraction (XRD), contact angle measurement, scanning electronic microscopy (SEM), and (ultra-) small angle X-ray scattering [(U)SAXS] were performed to characterize the mineralogy, wettability, and pore structure to assist the analysis of the SI data in Wolfcamp Shale. XRD results indicated the Wolfcamp Shale samples were dominated by carbonate and siliciclastics with different sample depths, which is concordant with the well-logging data. The SI experiments were conducted in hydrophilic de-ionized water (DIW) and hydrophobic D2T (a mixture of two parts of decane and one part of toluene). Most samples have layer structure, therefore, the SI experiments were performed in directions that parallel to the layer (P direction) and transverse to the layer (T direction) on each sample. The fitting slopes of SI results show that samples have better pore connectivity in hydrophobic D2T than DIW in both directions. In P direction, the imbibed volume of DIW and D2T are very close to each other, which indicate the Wolfcamp Shale could be more oil wet. (U)SAXS results provided the pore diameter distribution (PDD) of the samples, which separates the samples into two groups. Associated with mineralogy, group 1 is dominated by siliciclastic with pores at 10 nm and 50 nm, and group 2 is dominated by carbonate with pores at 100 nm and 600 nm. Coupled with PDD and mineralogy, the fitting slopes in group 2 in DIW P direction decrease and then increase with clay content with the turning-point at 30%. The micro-fractures and well-aligned clay minerals in SEM images in samples with more clay content could help to form fluid pathways during the DIW imbibition. Such a positive relationship in fitting slopes and clay content also appeared in D2T P direction imbibition. In summary, the experiments conducted on the Wolfcamp Shale in west Texas including SI, XRD, SEM, and (U)SAXS could investigate fluid transport mechanisms in shale to support the studies for unconventional reservoir development and carbon storage.

How to cite: Zhao, C., Hu, Q., Wang, Q., Fan, M., Ilavsky, J., and Wang, M.: Fluid-rock interaction of Wolfcamp Shale: the effects of pore structure and mineralogy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7185, https://doi.org/10.5194/egusphere-egu23-7185, 2023.

EGU23-7515 | Orals | ERE5.5

Coupled thermo-mechanical growth of multiple fractures in brittle heterogeneous rocks during thermal shock and resulting aperture distributions 

Adriana Paluszny, Lior Suchoy, Maria Cristina Saceanu, and Robert W. Zimmerman

Understanding the mechanisms that control the development of fractures in complex thermally deformed media, as well as how they interact with smaller-scale and larger-scale heterogeneiies in material properties, is relevant to a number of natural and engineered processes. In this study, we investigate the results of numerical simulations of thermal shock and the resultant fracturing of brittle rock slabs in the context of a fracture growth benchmark. The benchmark, based on multiple laboratory experiments, induces the non-planar formation of multiple fractures due to thermal shock on ceramic mm-scale slabs. The benchmark experiment tracks fracture geometries for a series of shock temperatures and is used to directly validate our numerical approach, which utilises a three-dimensional in-house finite element code to simulate thermo-mechanical deformation. The ensuing damage and spatially variable fracture apertures are quantified, as well as the resulting fracture network patterns. In our approach, fractures are represented as NURBS surfaces, which are discretised using quadrilaterals and triangles. The matrix is discretised using isoparametric tetrahedral and hexahedral elements. We show in our results how thermal shock affects the fracture aperture distributions, and how these aperture distributions depend on the initial heterogeneities in the modelled slab. We discuss how the simulated fracture interactions are self-organising, and compare well to the proposed multi-fracture benchmark. Additionally, we discuss the manner in which geometry, scale, and heterogeneity influence the resulting fracture pattern and aperture distribution. 

How to cite: Paluszny, A., Suchoy, L., Saceanu, M. C., and Zimmerman, R. W.: Coupled thermo-mechanical growth of multiple fractures in brittle heterogeneous rocks during thermal shock and resulting aperture distributions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7515, https://doi.org/10.5194/egusphere-egu23-7515, 2023.

EGU23-7705 | Posters on site | ERE5.5

Assessing carbon mineralization using an integrated approach at the Nesjavellir geothermal field, Iceland 

Deirdre Clark, Kjartan Marteinsson, Gunnar Þorgilsson, Iwona Galeczka, Helga Helgadóttir, Sandra Snæbjörnsdóttir, Bergur Sigfusson, and Sveinborg Gunnarsdóttir

The Nesjavellir high-temperature geothermal field in Iceland was chosen as part of the GECO H2020 project to further demonstrate the Carbfix method of carbon mineralization. In this method, geothermal power plant emissions of CO2 and H2S are captured using condensed steam, and subsequently co-injected with separated geothermal water into the subsurface where they mineralize in the form of carbonate and sulfide minerals. This technology has already been successfully shown to be a safe and cost-effective approach to reduce gas emissions from the nearby Hellisheiði geothermal power plant in SW Iceland.

An integration of geology, reservoir and geochemical models were used to evaluate the future injection of CO2 and H2S at the Nesjavellir site. These models include reservoir parameters such as the relative permeability and porosity of different stratigraphic layers as well as the locations of feedzones. Tracer tests and well temperature and pressure logs were used to calibrate single porosity and dual porosity TOUGH2 flow models. A 1-D flow reactive transport model was then created using TOUGHREACT and the parameters from the flow models and calibrated using chemical compositions of the reservoir background fluid and separated water, the proposed gas injection fluid chemistry and available bulk rock chemistry and lithological data from borehole reports. Results from this integrated approach offer possible controls on the flow, impacts of the CO2-H2S injection, and estimate the potential storage capacity of carbon mineralization within the Nesjavellir geothermal reservoir.

How to cite: Clark, D., Marteinsson, K., Þorgilsson, G., Galeczka, I., Helgadóttir, H., Snæbjörnsdóttir, S., Sigfusson, B., and Gunnarsdóttir, S.: Assessing carbon mineralization using an integrated approach at the Nesjavellir geothermal field, Iceland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7705, https://doi.org/10.5194/egusphere-egu23-7705, 2023.

Changes in temperature can modify the geochemistry of groundwater. This effect is very relevant not only for natural geothermal phenomena, but also for geothermal energy systems and Underground Thermal Energy Storage (UTES) systems. We propose a novel method that can be used to verify sophisticated numerical models and understand the thermo-hydro-chemical (THC) processes more clearly. The method decouples the chemistry from the thermo-hydraulic (TH) processes. The chemistry is obtained from geochemical batch calculation by PHREEQC and the TH processes from the finite element code CODE_BRIGHT. The method has been applied to a UTES pilot project near Bern, Switzerland, and compared with the THC coupled code RETRASO. The good agreement between the presented method and RETRASO verifies the correct implementation of our method. Moreover, the results provide information about the dominant reactive transport processes, mineral reaction rates and porosity changes.

Acknowledgements: This work was financed by the ERANET project HEATSTORE (170153-4401). This project has been subsidized through the ERANET cofund GEOTHERMICA (Project n. 731117), from the European Commission, RVO (the Netherlands), DETEC (Switzerland), FZJ-PTJ (Germany), ADEME (France), EUDP (Denmark), Rannis (Iceland), VEA (Belgium), FRCT (Portugal), and MINECO (Spain). Also, the first author is supported by a grant from the Department of Research and Universities of the Generalitat de Catalunya (2022 FI_B1 00208).

How to cite: Vidal, R. and Saaltink, M. W.: Decoupling thermo-hydraulic processes from chemical reactions to understand the effect of heat on chemical reactions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8356, https://doi.org/10.5194/egusphere-egu23-8356, 2023.

EGU23-10601 | ECS | Orals | ERE5.5

Diagenesis characteristics and diagenetic evolution of organic-rich marine shale 

Liangwei Xu, Lei Chen, Hao Wei, and Keji Yang

Shale is an unconventional oil and gas reservoir with both generation and storage characteristics. Diagenesis has an important impact on its organic petrological characteristics, reservoir physical properties, pore system structure characteristics, mineral component content and transformation. Diagenesis is of great significance for its porosity and permeability analysis, reservoir comprehensive evaluation and shale gas productivity. At present, the researches on diagenesis and diagenetic evolution mainly focus on conventional sandstone reservoir. Because the application of conventional oil and gas reservoir characterization technology to shale reservoir is limited, and the diagenetic characteristics of shale reservoir are difficult to identify, the researches on diagenetic evolution of shale reservoir are relatively weak, and the comprehensive researches on diagenesis and diagenetic evolution of shale reservoir are relatively scarce.

At present, there are mainly two kinds of research methods on the dual effects of thermal evolution and diagenesis of shale: the first is the direct observation method, which uses high-resolution equipment to analyze shale samples with different maturity and diagenesis to determine the characteristics and development differences of diagenesis. However, this method ignores the heterogeneity and regional differences of samples, and cannot show all the evolution characteristics of shale in the diagenesis process. The second is the physical simulation method, that is, the sample of low maturity is selected, the temperature series is set, and the generation of diagenesis process is induced by heating. This method reduces the heterogeneity of samples and the influence of regional differences on the experimental results to a certain extent. It has strong comparability and can provide the overall characteristics in the process of diagenesis. However, the disadvantage is that it lacks intuitive characterization and cannot clearly and intuitively display the diagenetic evolution characteristics of minerals in the same area.

In view of the above problems, the diagenesis and diagenetic evolution of low-mature organic-rich Marine type II shale in the Middle Proterozoic Xiamalin Formation in Zhangjiakou area of Hebei Province were studied by using the method of high temperature and high pressure physical simulation. The characteristics of diagenesis were observed and characterized in the simulated samples, and the types of diagenesis in the simulated products were identified. A conceptual model of shale diagenetic evolution sequence based on physical simulation is established. In addition, this study also uses direct observation method to characterize the diagenetic characteristics of natural marine shales of Xiamaling Formation in this area. Five diagenetic types including compaction, cementation, dissolution, hydrocarbon generation of organic matter and clay mineral transformation are identified, and diagenetic stages of Xiamaling Formation shales are divided. Furthermore, the marine diagenetic evolution sequence and diagenetic evolution model of the Mesoproterozoic Xiamalin Formation in Zhangjiakou area of Hebei Province are established (Fig.1). This study makes up for the deficiency in the study of shale diagenetic evolution, and has important reference and indicative significance for the development of other high-over-mature Marine shale gas reservoirs in China and the world.


Fig. 1. Diagenetic evolution sequence of the Mesoproterozoic Xiamaling marine shale in Zhangjiakou, Hebei.

How to cite: Xu, L., Chen, L., Wei, H., and Yang, K.: Diagenesis characteristics and diagenetic evolution of organic-rich marine shale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10601, https://doi.org/10.5194/egusphere-egu23-10601, 2023.

Subsurface fluid injection of environmental (e.g., carbon capture storage) and industrial (e.g., enhanced geothermal system) projects change pore pressure and underground stress which may induce fault slip. The temperature of injected fluid controls pore pressure and underground stress by thermo-poroelastic effect of fluid injection, that explains the interaction between pore fluid flow and elastic deformation in a porous medium. Since the perturbed subsurface stress distribution increases seismic uncertainty, a numerical modeling for varying injection conditions (e.g., injection scenario and fluid temperature) is helpful for understanding thermo-poroelastic behavior before the fluid injection. In this study, we build 2-dimensional finite element fluid injection models that simulate thermo-poromechanical processes using a COMSOL Multiphysics®. The thermal equation (Fourier’s Law) is coupled with the poroelastic theory to investigate the role of thermohydraulic-convection and -stress in a porous medium. We confirm that these injection conditions may change pore pressure, subsurface stress, and surface displacement, which supports the necessity of monitoring during/after fluid injection.

How to cite: Jang, C.-H., Kim, H., and So, B.-D.: A thermo-poroelastic finite element analysis of fluid injection depending on fluid temperature and injection scenarios, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10929, https://doi.org/10.5194/egusphere-egu23-10929, 2023.

EGU23-11202 | Posters on site | ERE5.5

Exploring and modeling the formation of desiccation cracks in Opalinus Clay at field scale 

Tuanny Cajuhi, Gesa Ziefle, Jobst Maßmann, and Keita Yoshioka

Opalinus Clay (OPA) has been one of the main focuses of international geoscientific research due to its potential use as a host rock for the storage of heat-generating radioactive waste. In-situ experiments taking place in the Mont Terri Rock Laboratory in Switzerland provide valuable insights into the material properties and behavior of OPA. The Cyclic Deformation (CD-A) experiment has been conducted since October 2019 in the rock laboratory to investigate hydro-mechanical effects through long-term direct and indirect measurements such as resistivity, water content, suction, and crack development. Desaturation effects due to variations in relative air humidity induced by ventilation and seasonal changes, drive the formation of desiccation cracks at the walls of the CD-A niches.

We use a mathematical model based on a macroscopic poromechanical and on the phase-field approaches to compute desiccation. The formulation consists of the balance equations of the solid and liquid phases and of the crack phase-field evolution equation. Within this combined framework, we are able to account for the drying of the niche and for desiccation cracks. Our solution scheme is implemented in the open-source finite element software OpenGeoSys (OGS 6).

In this contribution, we discuss the practical steps for applying the poromechanical phase-field approach at in-situ scale. The basic steps consist of determining the material properties and computing the fracture energy and characteristic length. Moreover, we use field data concerning the crack aperture to deduce the crack resolution for the simulations. The model setup consists of a quarter cross-section of a CD-A niche. We compare the modeled crack response with the monitored cracks at field scale and evaluate whether they initiate and propagate according to the monitored relative air humidity range. Furthermore, we assess the impact of randomly distributed material properties, e.g. fracture energy, and changes in permeability due to cracking.

How to cite: Cajuhi, T., Ziefle, G., Maßmann, J., and Yoshioka, K.: Exploring and modeling the formation of desiccation cracks in Opalinus Clay at field scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11202, https://doi.org/10.5194/egusphere-egu23-11202, 2023.

EGU23-11330 | ECS | Orals | ERE5.5

Shear-slip and Complex Fracturing by CO2 Injection in Naturally Fractured Granite at Geothermal Conditions 

Eko Pramudyo, Ryota Goto, Kiyotoshi Sakaguchi, and Noriaki Watanabe

Previous studies showed that cloud-fracture networks (CFNs), networks of permeable microfractures densely distributed over rock body, formed in granite at superhot geothermal conditions (> ~400 °C) through the stimulation of pre-existing microfractures by low-viscosity water near and above its critical temperature. The CFNs were also shown to form in granite at conventional (~150 – 300 °C) and superhot geothermal conditions by injection of low-viscosity CO2, through the same mechanism as that by low-viscosity water at superhot geothermal conditions. The stimulation of pre-existing microfractures by the low-viscosity CO2 implied that CFNs may be formed in the matrix (i.e., unfractured rock) of naturally-fractured conventional and superhot geothermal environments, where conventional bi-winged hydraulic fractures are known to be difficult to be achieved by injection of cold water. The present study illustrates the possibility of CFN formations in naturally-fractured geothermal environments, along with the shear-slip of the natural fractures, through CO2-injection experiments into cylindrical granite samples, each contained a sawcut (representing a natural fracture) inclined from the sample axis, under geothermal conditions. The experiments show that CO2 injection induced a larger cumulative shear displacement on the sawcut at conventional geothermal condition than at superhot geothermal condition. CFNs were formed at conventional and superhot geothermal conditions; nonetheless, the fracture-apertures were thinner for the CFN formed at conventional geothermal condition. The results imply that CFNs may be formed in naturally fractured geothermal environments, and may provide additional fluid-flow paths between the stimulated natural fractures.

How to cite: Pramudyo, E., Goto, R., Sakaguchi, K., and Watanabe, N.: Shear-slip and Complex Fracturing by CO2 Injection in Naturally Fractured Granite at Geothermal Conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11330, https://doi.org/10.5194/egusphere-egu23-11330, 2023.

EGU23-11566 | Orals | ERE5.5

Numerical modelling of ice forming and thawing in a subsurface energy storage application 

Tymofiy Gerasimov, Dmitrii Naumov, Thomas Nagel, Olaf Kolditz, and Haibing Shao

In the context of shallow subsurface ice storage, low temperature coolant fluid is circulated through multiple borehole heat exchangers (BHEs) to form ice in the surrounding soil. This can be used later on in building cooling applications. To evaluate the environmental impact of freezing and thawing cycles, we extended the classical Thermal-Hydro-Mechanical model in the OpenGeoSys software platform to simulate the aforementioned phase change scenarios.

The new feature development and verification is divided into several subsequent steps. In the model verification, the Stefan problem of slab melting is employed as the benchmark case: the numerical results from OpenGeoSys is verified against the available analytical solution. In the subsequent code verification, the concept of manufactured solution is adopted, in which the numerical outcome is compared with the reference data to show accurate agreement. Following that, the ultimate verification is conducted by comparing results from OpenGeoSys and the open source package like FreeFEM++.

For the application of the extended numerical model, we simulate the ice formation around the four BHEs in 3 dimensions for a quarter of the test field setup and over a period of 30 days. With -15 oC temperature imposed on the lower section of the BHE wall and the considered material data, the numerical simulation suggests an up to 50 cm thick layer of frozen soil surrounding the borehole. In the model results, major volumetric deformation of soil is observed in the close vicinity of the BHEs where the ice grows, also triggering small vertical surface elevation. Current on-going work is focusing on the coupling effect between thermal conductivity of soil, mechanical deformation and hydrology, where one of the envisioned impacts is the groundwater flow deviation due to the ice formed.

How to cite: Gerasimov, T., Naumov, D., Nagel, T., Kolditz, O., and Shao, H.: Numerical modelling of ice forming and thawing in a subsurface energy storage application, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11566, https://doi.org/10.5194/egusphere-egu23-11566, 2023.

EGU23-11711 | Posters virtual | ERE5.5

Understanding the triggering mechanisms of reservoir-triggered seismicity at Nova Ponte, Brazil, through hydro-mechanical modeling 

Victor Vilarrasa, Haris Raza, Iman Rahimzadeh Kivi, and George Sand França

Reservoir impoundment is usually accompanied by induced/triggered seismicity. The rise in the number of planned hydropower plants requires improving the understanding of the causes of this induced/triggered seismicity, which eventually could serve to propose mitigation measures to reduce the induced/triggered-seismicity risk. We investigate the case of reservoir-triggered seismicity at Nova Ponte, Brazil, where triggered seismicity started shortly after reservoir impoundment, with the maximum magnitude of M3.5 when reaching the highest water level on the dam, and followed by delayed seismicity, with the largest earthquake being a M4.0 about 4.5 years after impoundment. We have built a hydro-mechanical fully-coupled numerical model reproducing the T shape of the reservoir and including the three geological layers placed below the reservoir down to 10 km depth. Simulation results serve to identify the nodal plane, from the two nodal planes of the proposed focal mechanism, which nucleated the seismicity of the M3.5 earthquake: a vertical, E-W-oriented strike-slip fault with a reverse-displacement component. The initial seismicity was triggered by the undrained response of the subsurface to the loading of the reservoir. We also find that the delayed seismicity was triggered by pore pressure diffusion, bringing a critically oriented vertical fault to failure conditions. The vertical permeability to allow the pore pressure perturbation to reach the depth of the M4.0 earthquake, i.e., 3 km depth, in 4.5 years is 6.6·10-15 m2, two to three orders of magnitude higher than the expected permeability of the host rock, a low-permeability mica-schist. We contend that hydro-mechanical models are a useful tool to understand the triggering mechanisms of reservoir-triggered seismicity.

How to cite: Vilarrasa, V., Raza, H., Kivi, I. R., and França, G. S.: Understanding the triggering mechanisms of reservoir-triggered seismicity at Nova Ponte, Brazil, through hydro-mechanical modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11711, https://doi.org/10.5194/egusphere-egu23-11711, 2023.

Mudstones and shales are fine-grained sedimentary rocks that can serve as top seals of geological reservoirs in various geoenergy applications. Apart from traditional oil and gas exploration, the urgent need for underground storage of energy carriers (e.g., H2) and climate-relevant gases (e.g., CO2) facilitated extensive research on pore structural and mechanical parameters and their influence on the seal capacity of these rocks. The fracture behaviour of mudstone seal rocks controls the risk of seal failure due to microfracturing as a response to various geological processes (e.g., buoyancy pressure from the reservoir). In this contribution, the high-speed nanoindentation mapping approach was carried out for a proven mudstone top seal sample (~1629 m; quartz 31%, clay mineral 39%) from a Vienna Basin oil field. The nanoindentation results were then post-processed with machine learning-based tools to obtain representative mechanical parameters of the clay matrix. k-means clustering analysis was performed using three input features including hardness (H), reduced elastic modulus (Er), and the elastic-plastic deformation ratio based on the obtained load-displacement curves. In addition, broad ion beam-scanning electron microscopy (BIB-SEM) maps were taken before and after the nanoindentation to correlate the indentation results with direct imaging information and to verify the k-means clustering results. A total of 8 indentation map arrays (7 × 7 indents) were placed to test the sensitivity of different tips to indentation depth and load rate. The comparison of BIB-SEM image data and k-means clustering showed that decisions on phase assignment can be significantly improved and performed in a shorter time by k-means clustering analysis, still showing an overall good agreement with manual selections. For the studied mudstone sample, the resulting average Er and H values of the clay matrix range at 17.58 ± 6.89 GPa and 0.63 ± 0.76 GPa (n=30), respectively for the Berkovich tip and at 15.03 ± 4.79 GPa and 0.38 ± 0.23 GPa (n=62), respectively for the Cube Corner tip. The testing with both tips shows that despite the strongly heterogeneous microstructure of the indented clay matrix the obtained mechanical parameters are not sensitive to indentation depths and hence representative values can be determined from minimum volumes with statistical significance. Nevertheless, compared with the Berkovich tip, the Cube Corner tip sampled deeper depths (58-443 nm for the Berkovich tip and 412-1747 nm for the Cube Corner tip) and introduced more surface damage. By increasing the load rate from 1000 to 6000 μN s−1, the indentation testing tended to be unstable and the surface showed strong damage at the highest load rate. In conclusion, this contribution represents an important methodological step towards the implementation of combined high-speed nanoindentation mapping and machine learning data analysis as a feasible high throughput tool for the mechanical characterization of mudstones and similar fine-grained sedimentary rocks. The presented approach is planned to be applied to an extensive set of mudstone samples from the Vienna Basin with the purpose to link mechanical property changes to burial diagenesis.

How to cite: Shi, X., Misch, D., Zak, S., Cordill, M., and Kiener, D.: Determining representative mechanical parameters of clay matrix in mudstones using nanoindentation mapping and machine learning data analysis: a novel top seal characterization approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13696, https://doi.org/10.5194/egusphere-egu23-13696, 2023.

EGU23-13703 | ECS | Orals | ERE5.5

Long-term matrix acidification experiments under reservoir conditions using the Thermo-Triaxial device 

Angel Ramirez, Pham Tien Hung, Leandra Weydt, and Ingo Sass

Matrix acidification is one of the most popular stimulation techniques to increase the porosity and permeability of reservoir systems. Usually, the thermal-hydro-mechanical properties of reservoir rocks affected by the matrix acidification process are studied using flow-through tests or autoclave experiments. In this study, a novel acidification approach was tested using a thermal triaxial device at the TU Darmstadt laboratory. Thereby, hydrochloric acid 0.0375% (HCl pH=2) was flushed continuously through a total of five Remlinger sandstone samples under reservoir conditions (90oC temperature, s1=25 MPa, and s3=23MPa). Changes in matrix permeability and other petrophysical parameters due to the chemical reaction between the rock sample and HCl were recorded before, during, and after the reactive experiments. In addition, outflow fluid samples were collected and the pH was subsequently measured. After approximately 30 days of continuous flow for each sample, the permeability increased for all the samples, with a maximum increase of 300%. Likewise, porosity increased from 13.2% to 14.5%. In contrast, P- and -S-wave velocities decreased from 2608 to 2189 m‧s-1 and from 1540 to 1380 m‧s‑1, respectively. Test results provide important information for reservoir stimulation and can be used to benchmark THMC models.

How to cite: Ramirez, A., Hung, P. T., Weydt, L., and Sass, I.: Long-term matrix acidification experiments under reservoir conditions using the Thermo-Triaxial device, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13703, https://doi.org/10.5194/egusphere-egu23-13703, 2023.

EGU23-13900 | Orals | ERE5.5

Global thermal spring distribution and relationship to endogenous and exogenous factors 

Giancarlo Tamburello, Giovanni Chiodini, Giancarlo Ciotoli, Monia Procesi, Dmitri Rouwet, and Laura Sandri

In the last decades, the enormous potential for direct geothermal heat from aquifers attracted special attention, particularly toward those thermal springs indicating areas in which exploitation of geothermal energy might be economically feasible for indirect uses such as electrical power production. The availability of geochemical data besides the location of thermal spring areas assumes particular importance, especially in the first stages of a geothermal exploration program. In this work, we present a digitised format of the literature review of Gerald Ashley Waring on the geothermal springs of the world. This unprecedented dataset contains geographical coordinates (from georeferentiation) of ~6,000 geothermal spring areas, including complementary data such as temperatures, flow rates, total dissolved solids content (TDS, expressed in ppm), and quantitative chemical analysis of major elements (only for a few hundred sites). Using temperature and flow rate, we derive the heat discharged from 1483 thermal spring areas (between ~10-5 and ~103 MW, with a median value of ~0.5 MW and ~8300 MW in total). We complement this information with geological data sets currently available in the literature and analyse them using statistical and geospatial tools and a supervised machine-learning algorithm. We show that terrestrial heat flow, topography, volcanism, and extensional tectonic play a key role in the occurrence of thermal waters around the globe. These results can also be beneficial to address the geothermal interest towards specific and less studied areas and significantly drive the first steps of the geothermal surveys and detailed investigations. Finally, this data set in electronic format will be beneficial for future research on the spatial distribution of thermalism at a small scale and the variation of temperature and flow rate of several thermal springs in the last decades in certain regions.

How to cite: Tamburello, G., Chiodini, G., Ciotoli, G., Procesi, M., Rouwet, D., and Sandri, L.: Global thermal spring distribution and relationship to endogenous and exogenous factors, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13900, https://doi.org/10.5194/egusphere-egu23-13900, 2023.

EGU23-14038 | Orals | ERE5.5

Carbon dioxide, methane and heat emissions of the Monterotondo Marittimo and Sasso Pisano geothermal areas (Tuscany, Italy) 

Alessandra Ariano, Francesco Frondini, Carlo Cardellini, Giovanni Chiodini, Maurizio Petrelli, Marino Vetuschi Zuccolini, and Giorgio Virgili

In the central part of Tuscany region (Italy), is located the Larderello – Travale geothermal system which is a large-scale steam dominated system with reservoir temperatures that can exceed 350°C (Bellani et al. 2004). The characteristic high heat flow in this particular area is due to the presence of a thermal anomaly caused by the intrusion of a big Pliocene batholith into the upper crust (Musumeci et al. 2002). This work is aimed at investigating the relationships between carbon emissions and heat, particularly to analyse the distribution of CO2, CH4 and soil temperatures in the Monterotondo Marittimo and Sasso Pisano areas. Three hundred measurements of gas fluxes from the soil have been performed using the accumulation chamber method. CO2 fluxes range from 0.1 gm-2d-1 to about 20,000 gm-2d-1, while CH4 fluxes, available for a lower number of points, vary between 0 and 637 gm-2d-1. Soil temperatures were also measured at each location and ranges from 8.0 °C to 100 °C, with an average of 39.8 °C.

CO2 fluxes show a polymodal statistical distribution with (i) a background population characterised by an average CO2 flux in the order of 16.0 g m-2 d-1 and (ii) anomalous populations with an average CO2 flux of 400 g m-2 d-1 and 1600 g m-2 d-1   for Sasso Pisano and Monterotondo Marittimo respectively. Not null CH4 fluxes were measured only at points with a CO2 flux in the range of the anomalous CO2 flux population. The statistical distribution of the CH4 resulted more complex with two populations characterized by an average value of 0.8 g m-2d-1 and 174 g m-2d-1 respectively, probably reflecting differences in the gas transport mechanism in the soil and/or soil permeability, which is largely variable in the areas with anomalous flux.

The areas characterized by anomalous soil gas fluxes, show also an evident soil temperature anomaly (reaching values close to 100 °C), suggesting that soil degassing is accompanied by a significant process of steam condensation. In the anomalous areas, the CO₂/CH₄ ratios by weight vary between 1.6 x 10-4 to 1.0 x 10-1 and fall in the range of variation observed for the geothermal fluids of the Larderello-Travale region (Truesdell & Nehring, 1978; Chiodini et al., 1991; Chiodini & Marini, 1998).

Assuming that the soil is heated by steam condensation, a thermal energy release associated to the degassing process of about 200 MW is estimated for Monterotondo Marittimo, an energy release >15 MW is estimated for Sasso Pisano, where the measurements are still in progress.

How to cite: Ariano, A., Frondini, F., Cardellini, C., Chiodini, G., Petrelli, M., Vetuschi Zuccolini, M., and Virgili, G.: Carbon dioxide, methane and heat emissions of the Monterotondo Marittimo and Sasso Pisano geothermal areas (Tuscany, Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14038, https://doi.org/10.5194/egusphere-egu23-14038, 2023.

EGU23-14784 | ECS | Posters on site | ERE5.5

Numerical modelling of high-temperature aquifer thermal energy storage (HT-ATES) in the Upper Jurassic reservoir of the German Molasse Basin 

Kalliopi Tzoufka, Daniela Pfrang, Daniel Bohnsack, and Kai Zosseder

High-temperature aquifer thermal energy storage (HT-ATES) can contribute in balancing the spatiotemporal mismatch that arises between periods of excess energy supply in contrast to phases of high energy demand. Excess energy can be stored under the form of thermal energy in the subsurface by utilizing methods stemming from geothermal engineering applications. In order to increase the efficiency of operating geothermal systems at the German Molasse Basin, such concepts are currently considered for the storage of high-temperature fluids in the Upper Jurassic Reservoir (Malm) of the North Alpine Foreland Basin. The karstified and fractured Malm aquifer comprises a site of extensive and continuously increasing investigation and implementation of geothermal projects. Nevertheless, the suitability of this reservoir for the development of ATES systems has not been yet considerably investigated. In this work we present our initial approach to evaluate the potential for thermal energy storage application in the Upper Jurassic reservoir.

Due to the high structural and geological heterogeneity of the Malm aquifer, a subset of this reservoir, with favourable temperatures for heat storage, is investigated here that corresponds to segments governed by karst-dominated fluid flow. The numerical analysis builds upon three currently operating geothermal systems that exhibit such a characteristic karst-controlled fluid flow in depths of ca. 2000–3000 m TVD. In fact, a comprehensive analysis of borehole log data shows that several stratigraphic units contribute as inflow zones in those systems, however the main proportion of inflow results from the karstified zones. The model domain is, therefore, subdivided into three homogeneous units with the shallower layer representing a karstified unit, while the deeper units correspond to the less productive limestone and dolostone sequences of the Malm reservoir. Thermal and hydraulic properties are deciphered by field tests performed in the considered geothermal systems, their respective well logs as well as investigations of rock cores from two wells penetrating into the Malm reservoir (Bohnsack et al., 2020).

While those enhanced-permeability reservoirs may represent good candidates for subsurface heat storage due to high injectivity, they simultaneously enable high fluid fluxes that may in turn induce considerable thermal losses. A numerical analysis is performed here to capture and describe the governing physical processes, and to assess the potential of HT-ATES application in such reservoirs. Synthetic numerical models are hence developed that are based on the three considered geothermal systems of the Upper Jurassic reservoir. This approach enables to quantify thermal and hydraulic effects of heat storage, to identify potential hydraulic and thermal interference between injection and production, and to assess developing advective heat fluxes which may trigger heat losses and thus impede long-term sustainable operation of HT-ATES systems. Numerical results contribute into a better understanding of the reservoir behaviour and further into prediction of the system response under different background conditions.

 

References

Bohnsack, D., Potten, M., Pfrang, D., Wolpert, P., Zosseder, K. Porosity–permeability relationship derived from Upper Jurassic carbonate rock cores to assess the regional hydraulic matrix properties of the Malm reservoir in the South German Molasse Basin. Geothermal Energy 8, 12 (2020).

How to cite: Tzoufka, K., Pfrang, D., Bohnsack, D., and Zosseder, K.: Numerical modelling of high-temperature aquifer thermal energy storage (HT-ATES) in the Upper Jurassic reservoir of the German Molasse Basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14784, https://doi.org/10.5194/egusphere-egu23-14784, 2023.

EGU23-15956 | ECS | Orals | ERE5.5

Simulation of different georeservoir conditions on a highly-permeable sandstone 

Marco Fazio and Martin Sauter

Studying the mechanical and hydraulic behaviour of rocks at different depths is crucial to understand their potential as georeservoirs. In particular, permeability and porosity are affected by changing conditions and their values measured at surface do not represent the real value at a certain depth. Mostly rocks with low or intermediate permeability have been tested in this regard. Here, instead, we focus on a highly porous and permeable rock (approximately 25% and 1000 mD respectively): Bentheim sandstone.

Because of its petrophysical properties Bentheim sandstone is regarded as a reference rock material in laboratory experiments of rock mechanics: it is quasi monocrystalline (quartz up to 97%), with a well-sorted grain size distribution and well-connected pores, showing lateral continuity and homogeneous geometric, hydraulic and mechanical properties at the block scale.

Unsurprisingly, Bentheim sandstone, as a georeservoir, has been extensively tested in triaxial conditions for a variety of purposes, from oil and gas exploitation to geothermal energy and carbon storage and sequestration projects. In fact Bentheim sandstone is taken into consideration as a potential warm aquifer for low-cost geothermal energy and for studying anhydrite cementification in georeservoirs. Since Bentheim sandstone can be found at more than 2 km deep and has been previously buried down to 3.5 km, it is important to fully understand its behaviour at different pressure, temperature, hydraulic and stress-hystory conditions.

Previous laboratory studies have shown how the permeability of Bentheim sandstone is affected by effective confining pressure, bedding orientations and axial strain. In particular, it has been observed that an increase in effective pressure, corresponding to an increase in depth, does not influence the permeability of this sandstone. In reservoir geomechanics, this is a crucial finding. However, rocks at depths also experience different temperature and fluid pressure conditions, as well as different types of historic stress evolution. Although, general relationships between permeability and these parameters do exist, their specific effect on Bentheim sandstone has never been investigated in detail.

Based on triaxial experiments in a state-of-the-art apparatus, we demonstrate on large cylindrical samples the behaviour of Bentheim sandstone for quasi reservoir conditions. Our goal is to fill in the gap in understanding the hydromechanical behaviour of this highly-permeable rock and concomitant permeability changes at different georeservoir conditions, where a suite of geomechanical parameters is investigated.

How to cite: Fazio, M. and Sauter, M.: Simulation of different georeservoir conditions on a highly-permeable sandstone, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15956, https://doi.org/10.5194/egusphere-egu23-15956, 2023.

EGU23-211 | ECS | Orals | SM6.3

One to many seismogenic sources: from single earthquakes to seismic sequences 

Davide Zaccagnino, Luciano Telesca, and Carlo Doglioni

One of the major challenges in seismology is the lack of a unified view of earthquake dynamics embracing all the spatial and temporal scales at which it takes place: while several models describe successfully how single seismic events develop and statistical laws have been set up to characterize the distribution of seismicity in magnitude, space and time, at least as a consequence of mainshocks, such dichotomic information is rarely put into communication to better understand how seismogenesis occurs. Although a comprehensive, cross-scale theory is intrinsically impossible because of the different levels of physical complexity involved in the seismological processes, it is possible to derive several well-known links, as well as interesting new ones, between coseismic properties and long-term statistical patterns. We introduce a simple model based on optimization criteria to explain such mathematical relationships. Given an initial energy perturbation localised on a fault segment, the interface breaks down if the perturbation increases its energy beyond the breakdown level. The slip occurs and the fracture spreads rapidly. Not only that (which is not enough to explain how the fault system will behave at large scales), since the fault zone is in an unstable and frustrated state, i.e., a configuration forced by tectonic stress: meanwhile the fracture propagates, the adjoining interfaces and volumes move towards a more stable energy level, amplifying energy release by a certain amount. Then, the latter can be interpreted as a measure of the triggering power of fracture and applied to connect local and collective dynamics. We focus on the role of tectonic setting and the differences between in-fault and off-fault seismicity. Our model can reproduce several features of seismicity, such as the dependence of the b-value of the Gutenberg-Richter law on the tectonic setting, the correlation between b- and p-value of the Omori-Utsu law, the fractal dimension of hypocentral time series, duration of seismic sequences and the efficiency of the seismogenic process. We utilise the same framework to analyse the composition of moment tensor solutions of global and regional shallow seismicity in terms of double-couple vs non-double-couple contributions. We find that thrust events are characterized by higher double-couples with respect to normal and strike-slip fault earthquakes. Our results are also coherent with the broadly studied stress dependence of the scaling exponent b-value of the Gutenberg-Richter law, which turns out to be anticorrelated to the double-couple contribution. Our work suggests that the structural and tectonic complexity of the seismogenic source marked by the roughness of faults and the width of the dislocation zones has a significant impact on coseismic dynamics, which should be considered in the routinely applied observational procedures to avoid systematic biases in the estimation of the parameters of the seismic source, e.g., the seismic moment.

How to cite: Zaccagnino, D., Telesca, L., and Doglioni, C.: One to many seismogenic sources: from single earthquakes to seismic sequences, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-211, https://doi.org/10.5194/egusphere-egu23-211, 2023.

Earthquake swarms are bursts of relatively small to moderate earthquakes lasting from hours to months without a clear triggering mainshock. To shed new light on the physical processes driving the seismic swarm that occurred in 2013 along the Alto Tiberina low angle normal fault, we investigate the strain sensitivity to seismic velocity variations (dv/v). For that, we use continuous recordings of ambient noise recorded at 18 stations located in the vicinity of the Alto Tiberina fault for a period of four years. We then retrieve daily dv/v with a time lapse approach by applying the stretching technique. After decomposing our dv/v into tectonic and non-tectonic (thermoelastic and rain induced changes) components, we find a velocity drop (0.035%) coinciding with the seismic swarm. Our observations and the deduced strain sensitivity of roughly 1000 suggest that the triggering of the swarm is mainly caused by an aseismic slip enhanced by the presence of fluids at seismogenic depth (3 - 5 km) 

How to cite: Mikhael, N., Poli, P., and Garambois, S.: Non-linear seismic velocity variations observed during a seismic swarm in the Alto Tiberina low angle normal fault from ambient noise correlation measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-981, https://doi.org/10.5194/egusphere-egu23-981, 2023.

EGU23-1176 | Orals | SM6.3

Swarms of Microseismicity Beneath the Submarine Kolumbo Volcano Indicate Opening of Near‐Vertical Fractures Exploited by Ascending Melts 

Florian Schmid, Gesa Petersen, Emilie Hooft, Michele Paulatto, Kajetan Chrapkiewicz, Martin Hensch, and Torsten Dahm

The Kolumbo submarine volcano in the southern Aegean (Greece) is associated with repeated seismic unrest since at least two decades and the causes of this unrest are poorly understood. We present a ten-month long microseismicity data set for the period 2006–2007. The majority of earthquakes cluster in a cone-shaped portion of the crust below Kolumbo. The tip of this cone coincides with a low Vp-anomaly at 2–4 km depth, which is interpreted as a crustal melt reservoir. Our data set includes several earthquake swarms, of which we analyse the four with the highest events numbers in detail. Together the swarms form a zone of fracturing elongated in the SW-NE direction, parallel to major regional faults. All four swarms show a general upward migration of hypocentres and the cracking front propagates unusually fast, compared to swarms in other volcanic areas. We conclude that the swarm seismicity is most likely triggered by a combination of pore-pressure perturbations and the re-distribution of elastic stresses. Fluid pressure perturbations are induced likely by obstructions in the melt conduits in a rheologically strong layer between 6 and 9 km depth. We conclude that the zone of fractures below Kolumbo is exploited by melts ascending from the mantle and filling the crustal melt reservoir. Together with the recurring seismic unrest, our study suggests that a future eruption is probable and monitoring of the Kolumbo volcanic system is highly advisable.

How to cite: Schmid, F., Petersen, G., Hooft, E., Paulatto, M., Chrapkiewicz, K., Hensch, M., and Dahm, T.: Swarms of Microseismicity Beneath the Submarine Kolumbo Volcano Indicate Opening of Near‐Vertical Fractures Exploited by Ascending Melts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1176, https://doi.org/10.5194/egusphere-egu23-1176, 2023.

EGU23-1883 | ECS | Orals | SM6.3

40 years of seismic swarms in the the BR-CP transition zone in Central Utah 

Gesa Petersen, Katherine Whidden, and Kristine Pankow

Seismicity in Central Utah, USA, exhibits a remarkable diversity in swarm activity. Swarms in the study area may alter between high and low activity phases, show a comparably continuous moment release, or a rise and fall of magnitudes over time. While some swarms repeatedly occur in the same source area for several years, other large swarms occur in areas without any significant seismic activity. The diversity is attributed to the complex geo-tectonic transition zone between the Basin and Range province (BR) and the Colorado Plateau (CP) in Central Utah, which is manifested in tectonic forcing related to E-W extension, high heat flow, and hydrothermal processes. Based on the University of Utah Seismograph Stations' catalog, we analyzed forty years of seismic swarm activity within Central Utah, USA, regarding characteristic statistical features (e.g., duration, moment release over time, spatial variations). In-depth analyses of three seismic sequences, including event detections, relocations, MT inversions, waveform-based clustering, and repeater analysis, provide unique insights into the study area's complex and diverse faulting processes. This includes (1) swarm activity at a regional Basin and Range normal fault, (2) activation of a local fault deviating from the recent regional tectonic regime, and (3) the complex triggering of swarm activity by a mainshock. In a joint discussion of the single exemplary sequences and the characteristics of swarm activity, we aim to expand the discussion on swarm activity beyond the study area and shed light on its relation to geothermal and tectonic processes.

How to cite: Petersen, G., Whidden, K., and Pankow, K.: 40 years of seismic swarms in the the BR-CP transition zone in Central Utah, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1883, https://doi.org/10.5194/egusphere-egu23-1883, 2023.

Ample observations attest to the importance of pore pressure dynamics and fault-zone fluid flow in producing earthquake swarms, foreshocks, and aftershocks. However, poroelasticity effects incorporating the two-way coupling of solid and fluid phases where pore-pressure evolves due to e.g. slip, dilatancy, and compaction, are rarely considered in simulations of fault slip. Here we study how coupled dynamics of frictional slip, pore pressure, permeability and porosity evolution control the occurrence of precursory slow-slip and foreshocks leading to the mainshock. We model fully dynamic seismic cycles with a newly-developed Hydro-Mechanical Earthquake Cycles (H-MECs) code where uniform velocity-weakening rate-and-state friction and a constant and far-field loading rate are applied on a 2-D anti-plane fault model embedded in a poro-visco-elasto-plastic medium. We also include the effect of permeability barriers, represented by regions of low permeability and high pore-fluid pressure with wavelengths similar to the nucleation length. Despite the relatively simple model setup, a complex fault behavior arises from the numerical experiments, including small seismic events, complete ruptures, as well as aseismic slip transients. Our results indicate that permeability barriers – where pore-fluid pressure is high – lead to fault creep, whereas foreshocks and mainshocks unzip from locked asperities with relatively lower pore-fluid pressure. We find that the ratio between the size of locked asperity and the wavelength of permeability barriers controls both the nucleation and propagation of aseismic creep, slow-slip transients, cascade of foreshocks, and full seismic rupture. Further numerical experiments accounting for both permeability enhancement due to fault slip and permeability reduction due to healing and sealing show that, once the permeability seals break, fluid is injected and redistributed through the fault zone, which diffuses primarily on-fault, thus leading to the nucleation of a complete rupture. As a result, permeability evolution and pore-fluid pressure variations modulate the ratio of seismic to aseismic moment release of seismic swarms. Our results, compared to observations, demonstrate that pore-fluid pressure evolution and poroelastic effects on- and off-fault play a critical role in the dynamism of earthquake swarms, as they control the stability of faults and whether slip is seismic or aseismic.

How to cite: Ye, J. and Dal Zilio, L.: The role of poroelasticity and permeability barriers in governing the interplay between precursory slow slip and foreshocks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2003, https://doi.org/10.5194/egusphere-egu23-2003, 2023.

EGU23-2298 | Posters on site | SM6.3

An atypical swarm at the North Mid-Atlantic ridge indicating spreading events 

Simone Cesca, Malte Metz, Pınar Büyükakpınar, and Torsten Dahm

A large seismic swarm affected the North Mid-Atlantic ridge between September and November 2022, with an outstanding seismicity rate and a cumulative moment equivalent to a magnitude Mw 6.3. We performed a detailed seismological analysis using regional, teleseismic and array data to reconstruct the spatiotemporal evolution of the seismicity. Combining template matching, relative location and full moment tensor inversion, we identify that most seismicity was located in a narrow band along the ridge, with typical normal faulting mechanisms. However, some of the latest and strongest events occurred up tp 25 km off the ridge axis, with thrust mechanisms that are atypical at mid-ocean ridges and inconsistent with the extensional tectonics. Seismicity also present a clear migration pattern, propagating over ~60 km from North to South, with the thrust mechanisms only occurring in the late phase of the swarm and only in the central-southern section. We hypothesize a magmatic intrusion as driver of the seismicity, with a vertical dyke first propagating southward, accompanied by normal faulting earthquakes, and then thickening, to produce a stress perturbation able to trigger thrust earthquakes on pre-existing structures on the side of the dike. The 2022 unrest provides evidence for sporadic spreading accompanied by large swarm episodes driven by magma intrusions at the mid-ocean ridge.

How to cite: Cesca, S., Metz, M., Büyükakpınar, P., and Dahm, T.: An atypical swarm at the North Mid-Atlantic ridge indicating spreading events, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2298, https://doi.org/10.5194/egusphere-egu23-2298, 2023.

EGU23-2557 | ECS | Orals | SM6.3

Relative phase analysis for volcanic tremor detection and source location 

Andres Barajas and Nikolai Shapiro Shapiro

The analysis of highly coherent seismic signals produced during tremor episodes has been recently gained interest as a mean to study the structure of volcanic systems, and the underlying physical mechanism producing its activity. Volcanic tremor signals usually appear with a non-impulsive gradual onset and can last for long periods of time, ranging from hours to months, during which individual waves cannot be recognized. The lack of identifiable arrivals during tremor episodes and the long duration of the registered signals, renders ineffective classical methods based on the analysis of the travel times, making difficult the location of its sources. 

We present observations showing that during tremor episodes, the relative phase of inter-station cross-correlations is approximately constant, which is directly linked to the stability of the source position and mechanism. We propose a new method to identify the relative phase stability (and therefore, wavefield coherence) in recordings obtained from a seismic network, that can also be applied to recordings from a single pair of stations. Then, we use a new approach based on the relative phase measurements to find the position of the source of a tremor episode in 2015 at the Klyuchevskoy Volcanic Group.  In general, we show several of the advantages of extracting information from the relative phase as opposed from methods relying on the identification of arrival phases.

How to cite: Barajas, A. and Shapiro, N. S.: Relative phase analysis for volcanic tremor detection and source location, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2557, https://doi.org/10.5194/egusphere-egu23-2557, 2023.

EGU23-2618 | ECS | Orals | SM6.3

Propagation of a fluid-induced aseismic crack leads to earthquake swarm migration controlled by fluid volume 

Philippe Danré, Dmitry Garagash, Louis De Barros, Frédéric Cappa, and Jean-Paul Ampuero

Seismicity migration is one of the most remarkable features of earthquake swarms because of its ubiquity and the wide range of migration durations, velocities and shapes observed. The dynamic properties of swarms, like seismic moment or number of events, are often attributed to fluid circulation, directly or indirectly. However, classical models of fluid pressure diffusion aiming at explaining seismicity triggering and migration show some limitations.  An increasing body of evidence points at an important contribution of fluid-induced aseismic slip during swarms. Moreover, parameters like injection history and fault criticality are expected to intervene. In this work, we use a fracture mechanics framework to show that  earthquake migration can be explained as driven by the propagation of a fluid-induced aseismic slip transient on a rate-and-state fault. This theoretical model predicts a simple linear relation between the seismic migration distance and the square root of the injected fluid volume. This relation is validated by observations in two well-studied seismic sequences induced by injections for geothermal purposes (Basel and Soultz-sous-Forêts), in which the seismicity is mainly clustered around a single surface. In addition, the model helps constrain frictional, hydraulic and structural properties of the fault hosting aseismic slip, and can be reasonably generalized to all fluid-induced earthquake swarms, natural and anthropogenic.

How to cite: Danré, P., Garagash, D., De Barros, L., Cappa, F., and Ampuero, J.-P.: Propagation of a fluid-induced aseismic crack leads to earthquake swarm migration controlled by fluid volume, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2618, https://doi.org/10.5194/egusphere-egu23-2618, 2023.

EGU23-2833 | ECS | Posters on site | SM6.3

Microseismic triggering by small sinusoidal stress perturbations at the laboratory scale 

Martin Colledge, Jérôme Aubry, Kristel Chanard, François Pétrélis, Clara Duverger, Laurent Bollinger, and Alexandre Schubnel

Small transient stress perturbations are prone to trigger (micro)seismicity. In the Earth's crust, these stress perturbations can be caused by various sources such as the passage of seismic waves, tidal forcing, or hydrological seasonal loads. A better understanding of the dynamic of earthquake triggering by transient stress perturbations is essential to improve our understanding of earthquake physics and our consideration of seismic hazard.

Here, we study an experimental sandstone-gouge-filled fault system that undergoes creep with combined far field loading and periodic stress perturbations at crustal pressure conditions. This complex loading is analogous to the loading experienced by faults in the natural setting.

Microseismicity — in the form of acoustic emissions (AE) — strains, and stresses, are continuously recorded to study the response of the system as a function of loading rate, amplitude, and frequency of a periodic stress perturbation. 

The observed temporal distributions of the AEs disagree with the theoretical results of a Coulomb failure model considering both constant loading and oscillation-induced strain rates. This implies that the stress perturbations are of shorter period than the nucleation time of the AEs of the system. A susceptibility of the system’s AE response to confinement pressure amplitude is estimated, which highlights a linear relation between confinement pressure amplitude and the AE response amplitude, observations which are consistent with recent higher frequency experimental results on dynamic triggering.

The magnitude-frequency distribution of AEs is also computed. The Gutenberg-Richter b-value oscillates with the stress perturbations, the amplitude of the b-value oscillations increasing with the amplitude of the stress perturbations, as observed in natural catalogues with large stress oscillations. 

Our experiments may complement our understanding of the influence of low inertia stress phenomena on the distribution of seismicity, such as observations of dynamic triggering and seismicity modulation by solid earth tides or seasonal loading.

How to cite: Colledge, M., Aubry, J., Chanard, K., Pétrélis, F., Duverger, C., Bollinger, L., and Schubnel, A.: Microseismic triggering by small sinusoidal stress perturbations at the laboratory scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2833, https://doi.org/10.5194/egusphere-egu23-2833, 2023.

On 2nd October 2020, an unusual extreme rainfall event (600 mm) associated with the devastating “Alex storm” occurred in less than 24 hours in the Tinée valley, a low strain rate area (convergence rates of 0.3-0.9 mm/yr) of the Southern French Alps, located 20 kilometers from Nice city. This transitional zone between the Argentera Mercantour exhumed Alpine massif and the Nice/Castellane Arc, mainly filled with Cenozoic sediments covering inherited structures, has no clear active faults known and displays a low seismicity rate with only 60 events recorded between 2014 and October 2020 by the national RESIF-EPOS seismic network, with local magnitudes ranging from 0.6 to 2.6. However, in the days after the “Alex storm”, a sudden increase in the seismicity rate was observed, with 114 events detected by template matching (local magnitudes between -0.8 and 2.05). After a peak activity, reached on the 8th of October with more than 60 events detected, the seismic crisis ended around mid-December 2020. Here, we investigate how the intense rainfall can explain the seismic sequences and what are the triggering processes in such a low tectonically deformation area.
Basing our analysis on a precise relocation of the seismicity, using the double-difference relative method, three swarms successively activating from south to north, with focal depths around 5 kilometers have been revealed. The main swarm clearly presents a N160 alignment, which is quite consistent with the general orientation of the Southwestern Alps main faults. A geological field analysis has also shown the presence of major unmapped pluri-kilometers faults consistent with the seismicity location and orientation. Those faults may cross-cut the entire sedimentary layers, connecting more or less directly the ground surface to the deep basement with some highly-permeable channels for fluid flow. Moreover, this relocation analysis highlighted a bi-directional migration of the seismicity within the main swarm: northwestward with a velocity of 100 m/hr, compatible with aseismic slip-driven seismicity, and southeastward with a velocity of 4.5 m/hr, rather compatible with fluid diffusion-driven seismicity.
On top of that, preliminary numerical models, focusing on the analysis of Coulomb stress changes in response to the recorded rainfall rate, showed a correlation between the seismicity rate and the rainfall, which may indicate a rapid saturation of the shallow porous sedimentary layers with fluids after the storm. However, models of stress changes associated with increasing fluid pressure only or including the effect of poroelasticity are not sufficient to explain the temporal evolution of seismicity and its rates. The contribution of other driving processes is necessary and aseismic slip processes could be more relevant to explain the 3 main bursts of seismicity, the migration pattern and the few-days delay with the rainfall episode. Those rainfall-induced aseismic fault slip may have triggered local seismic ruptures along small seismogenic portions of unknown inherited structures. Thus, our study reveals that the Tinée valley area is a good example to study the complexity of aseismic triggering processes of seismicity in association with shallow rainfall-driven hydraulic perturbations in an intraplate region with a low-deformation background rate.

How to cite: Jacquemond, L., Cappa, F., Godano, M., and Larroque, C.: Locally triggered earthquake swarm in the low-deformation zone of Tinée Valley (Southwestern French Alps) following the extreme rainfall event associated with the 2020 Alex storm, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3067, https://doi.org/10.5194/egusphere-egu23-3067, 2023.

EGU23-4073 | ECS | Posters on site | SM6.3

Application of Ocean Bottom Seismometer: Study of the 4 Aug 2021 southernmost Okinawa Trough M6.1 event. 

Shiou-Ya Wang, Shu-Kun Hsu, Min-Rui Wu, Chin-Wei Liang, and Yen-Yu Cho

The Southern Okinawa Trough (SOT) is a back-arc-basin and characterized by an active normal faulting system and magmatic activity. Most seismic activities beneath the Southern Okinawa Trough at shallow depths (<30 km) are located about 50 km east of Ilan Plain (122.15°E - 122.55°E).  The seismic rate has increased significantly after May 2021. An earthquake struck offshore area of Ilan Plain on 4 August (0804 earthquake). Its magnitude of 6.1 at 7.0 km made it one of the rare, extremely powerful quakes ever before in the study area. However, the cause and mechanism are still unclear and worthy of further investigation. Furthermore, the previous study shows that submarine landslides have occurred in the northern continental margin of SOT. The frequent earthquakes will raise the risk of slope failure and may generate a local tsunami causing damage around the northeast coast of Taiwan. In order to explore the generation of 0804 earthquake, we have deployed an Ocean Bottom Seismometer (OBS) network to capture the seismicity around the study area.  In total, 852 events have been relocated and most of them are located in the high positive magnetic anomaly zone. The distributions of the earthquake show an NW-SE trending direction and may be related to the magmatic activity.  

How to cite: Wang, S.-Y., Hsu, S.-K., Wu, M.-R., Liang, C.-W., and Cho, Y.-Y.: Application of Ocean Bottom Seismometer: Study of the 4 Aug 2021 southernmost Okinawa Trough M6.1 event., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4073, https://doi.org/10.5194/egusphere-egu23-4073, 2023.

EGU23-5145 | ECS | Orals | SM6.3

Permeability and seismicity rate changes at an inflating submarine volcano caused by dynamic stresses 

Adnan Barkat, Yen Joe Tan, Guangyu Xu, Felix Waldhauser, Maya Tolstoy, and William S.D. Wilcock

Our understanding of dynamic earthquake triggering in submarine environments is limited due to the lack of offshore observations. Here, we analyze the triggering susceptibility of a magmatically robust, seismically active submarine volcano (Axial Seamount), located at the intersection of the Juan de Fuca ridge and the Cobb hotspot in the northeast Pacific Ocean. Axial Seamount hosts a cabled network of geodetic and seismic instruments since late 2014. Axial Seamount last erupted in April 2015 and has continued to inflate since. We utilize a high-resolution micro-seismicity catalog to evaluate the triggering response from July 2015 to July 2022 based on seismicity rate change estimates for potential triggering sources. We report statistically significant episodes of dynamic earthquake triggering for ~16% of cases, including instances of both instant (0 < 𝑡 < 2 ℎ𝑟) and delayed (2 < 𝑡 < 24 ℎ𝑟) increases in local earthquake rate following the arrival of teleseismic waves. Initial results do not show any obvious dependence of triggering strength on the amplitude of the peak ground velocity. To evaluate the possible influence of permeability change on dynamic earthquake triggering, we compute the phase lag between vent-fluid temperature and tidal loading for the 3-day periods before and after the arrival of teleseismic waves. We report permeability changes for both triggering and non-triggering cases. Our findings provide useful insights into the physical mechanisms controlling the dynamic earthquake triggering at submarine volcanic environments.

How to cite: Barkat, A., Tan, Y. J., Xu, G., Waldhauser, F., Tolstoy, M., and Wilcock, W. S. D.: Permeability and seismicity rate changes at an inflating submarine volcano caused by dynamic stresses, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5145, https://doi.org/10.5194/egusphere-egu23-5145, 2023.

EGU23-5772 | Posters on site | SM6.3

Different Tectonics, Same Approach:  Estimation of source parameters using the Coda Calibration Tool (CCT). 

Paola Morasca, Kevin Mayeda, Jorge I. Roman-Nieves, David R. Shelly, Katherine M. Whidden, Allison L. Bent, Charlie Peach, Stuart Nippress, David Green, William R. Walter, Justin Barno, and Dino Bindi

It is well known that the use of different methods (e.g., spectral fitting, empirical Green’s functions) for compiling catalogs of source parameters (e.g., seismic moment, stress drop) can results in significant inconsistencies (Baltay et al., 2022). In this study, we present the application of coda-wave source parameters estimation by the Coda Calibration Tool (CCT) to different tectonic settings for closer analysis of the regional variations.  CCT implements the empirical methodology outlined in Mayeda et al., (2003), which provides stable source spectra and source parameters even for events recorded by sparse local and regional seismic networks (e.g., Morasca et al., 2022). The main strength of the method is the use of narrowband coda waves measurements, which show low sensitivity to source and path heterogeneity. Additionally, we use independent ground-truth (GT) reference spectra for which apparent stresses are independently calculated through the coda spectral ratio (Mayeda et al., 2007), to break the path and site trade-off.  The use of GT spectra eliminates the need to assume source scaling for the region, reducing the impact of a-priori model assumptions on the interpretation of scaling laws of source parameters and their variability. The CCT is a freely available Java-based code (https://github.com/LLNL/coda-calibration-tool) that significantly reduces the coda calibration effort and provides calibration parameters for future use in the same region for routine processing.

Recently, several studies applied CCT in very different tectonic contexts, including (1) earthquakes in tectonically active regions (e.g., central Italy, Puerto Rico, southern California, Utah); (2) induced earthquakes in southern Kansas and northern Oklahoma; and (3) moderate-sized earthquakes in stable continental regions such as in Eastern Canada and the United Kingdom. There is excellent agreement between coda-derived Mw in all regions and available Mw from waveform modelling. In some cases, such as central Italy and Ridgecrest, the validation process also involved the comparison with estimates from different empirical techniques, such as spectral decomposition approaches applied to data sets sharing common events with CCT. Overall, there is a general consistency in the scaling laws obtained for different source parameters (e.g., seismic moment, corner frequency, radiated energy and apparent stress), with earthquakes in the UK and Canada having similar and higher apparent stresses than Utah, central Italy, Puerto Rico and southern California, while the induced regions are characterized by the lowest values. In conclusion, the application of a consistent methodological framework and the robustness demonstrated by the results of the seismic coda analysis allow comparison of source scaling relationships for different tectonic settings over a wide range of magnitudes.

How to cite: Morasca, P., Mayeda, K., Roman-Nieves, J. I., Shelly, D. R., Whidden, K. M., Bent, A. L., Peach, C., Nippress, S., Green, D., Walter, W. R., Barno, J., and Bindi, D.: Different Tectonics, Same Approach:  Estimation of source parameters using the Coda Calibration Tool (CCT)., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5772, https://doi.org/10.5194/egusphere-egu23-5772, 2023.

EGU23-6541 | Posters on site | SM6.3

Earthquake swarm September/October 2022 on Disko Island, West Greenland 

Trine Dahl-Jensen, Peter H. Voss, and Tine B. Larsen

During 25 days in September and August 2022, the island of Disko in central west Greenland experienced a swarm of around 200 small earthquakes, ranging from ML 1.0 to ML 3.1. The majority of the earthquakes were concentrated on a small peninsula measuring 15 x 25 km. We have not received any felt reports, with  the closest inhabited area is approximately 20 km away. The island of Disko is part of the Palaeogene North Atlantic province. Swarms has been observed on and around Disko Island earlier, but not in the same place as the September/October 2022 swarm. In 2010, 27 earthquakes were detected in an area  around 20 km to the east [1], and in 2016 a swarm of over 250 earthquakes occurred following three mb 4.5+ earthquakes. These earthquakes occurred offshore and south of Disko Island, 60 km to the SSE [2]. The coverage with seismic stations is Greenland is sparse, with distances between stations in hundreds of km, but since 2019 three additional stations have been in operation in central west Greenland due to monitoring for landslide events, enabling better locations. The closest station to the swarm is GDH, at 60 km distance. The largest earthquakes in the swarm could be observed at a distance of more than 1600 km.

  • Larsen, T.B., et al., Earthquake swarms in Greenland. Geological Survey of Denmark and Greenland (GEUS) Bulletin, 2014. 31: p. 75-78.
  • Dahl-Jensen, T., P.H. Voss, and T.B. Larsen, [S01-4-01] Recent earthquakes at Disko Island, Greenland, with focal mechanisms in IAG-IASPEI Joint Scientific Assembly. 2017: Kobe, Japan.

How to cite: Dahl-Jensen, T., Voss, P. H., and Larsen, T. B.: Earthquake swarm September/October 2022 on Disko Island, West Greenland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6541, https://doi.org/10.5194/egusphere-egu23-6541, 2023.

EGU23-6581 | ECS | Orals | SM6.3

Evidence of an aseismic slip event continuously driving the 2017 Valparaiso earthquake sequence 

Luc Moutote, Yuji Itoh, Olivier Lengliné, Zacharie Duputel, and Anne Socquet

Both laboratory experiments and friction theory predicts that earthquake ruptures do not begin abruptly but are preceded by an aseismic slip acceleration over a finite nucleation zone. Such a nucleation phase may also trigger precursory ruptures known as foreshocks. Therefore, the scalability of the nucleation phase and its detectability before actual earthquakes is an important question with direct implications for earthquake prediction and seismic hazard assessment. Both Slow Slip Events (SSEs) and seismicity rate increase have already been identified before a few large earthquakes and are often interpreted as evidence of their nucleation process. However, such observations still remain scarce and are associated with different characteristic lengths that raise doubt on the actual preparatory nature of these signals. Here, we further study the case of the 2017 Valparaiso Mw= 6.9 earthquake that was preceded both by an SSE and an intense seismicity suspected to reflect the nucleation phase. We further investigate seismic and aseismic interplay over the complete earthquake sequence, from foreshock up to post-mainshock times, to search for a possible connection with the mainshock occurrence. For that, we build a high-resolution catalog (Mc=2) of the region using cutting edge picking tools, reporting more than 100 000 events from 2015 to 2021 (compared with the ~8000 events reported by the Centro Sismológico Nacional over the same time-period). First, we search for anomalous seismicity rate increases in the vicinity of the mainshock compared to usual earthquake to earthquake triggering models. Using a modified Epidemic Type Aftershock Sequences model that accounts for short-term incompleteness (Hainzl 2021) and MISD declustering (Marsan and Lengliné 2008), we highlight a significant over-productive earthquake rate starting within the foreshock sequences and persisting continuously after the mainshock for several days. Then, thanks to repeating earthquakes, we show that the slow slip event is continuously decelerating from the foreshock sequences up to months after the mainshock. The estimated slip rate is lightly impacted by large magnitude occurrences and does not accelerate toward the mainshock or any large magnitude earthquake. The slip estimate from repeaters is also compared with original high-rate GPS observations during the complete 2017 sequence, further supporting the continuity of the slow slip from the foreshock up to post-mainshock times. The joint observation of an SSE and a transient background seismicity continuously from the foreshock up to post mainshock suggests a close connection between the SSE and the seismicity. Results suggest that the unusual seismic and aseismic activity observed do not reflect the nucleation phase accelerating to the mainshock dynamic rupture. The SSE would rather underlie the complete 2017 earthquake sequence, mediating a part of the seismicity, possibly by stress transfer. The resulting seismicity is then further enhanced with usual earthquake to earthquake triggering, building up the sequence. This suggests that high resolution analysis of seismic and aseismic processes over the complete earthquake sequence is needed to properly assess the significance of signals preceding mainshocks.

How to cite: Moutote, L., Itoh, Y., Lengliné, O., Duputel, Z., and Socquet, A.: Evidence of an aseismic slip event continuously driving the 2017 Valparaiso earthquake sequence, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6581, https://doi.org/10.5194/egusphere-egu23-6581, 2023.

EGU23-9103 | Posters on site | SM6.3

Tectonic and volcano-tectonic seismicity below Tungurahua volcano (Ecuador) between 2013 and 2018 

Jean Battaglia, Monica Segovia, Silvana Hidalgo, and Edwin Villareal

Tungurahua (5023 m a.s.l.) is an andesitic stratovolcano located in Central Ecuador. The more recent eruptive cycle started in September 1999 and lasted until March 2016 with repeated phases of enhanced activity. Its activity included the occurrence of distinct eruptive phases separated by periods of quiescence, both lasting from few weeks to months. From October 2013 until March 2018, we operated at Tungurahua a temporary seismic network including up to 13 broadband stations. It complemented the permanent monitoring network operated by the Instituto Geofísico de la Escuela Politécnica Nacional (IG-EPN) and included stations up to 4275 m a.s.l. as well as stations on the remote Eastern flank.

Using IG-EPN catalogs and cross-correlation techniques, we identified several clusters of shallow and deep (volcano-)tectonic earthquakes. For these clusters, we manually picked a selection of larger events and used them to pick automatically other similar events. A visual inspection of the pickings was performed to confirm the absence of major biases. The comparison of P-phase times shows differences less than 0.1 s. Regarding S-phases, the cross correlation technique detected by far more S-phases per event, providing a general improvement in the location of events. Additionally we used seismic amplitudes and their decay as a function of distance to locate tremor and explosion quake sources during eruptive phases.

The seismicity below sea level defines 4 main clusters spread around the volcano between 2 and 10 km b.s.l.. The temporal evolution of these clusters displays a rather steady behavior for 3 of them and a swarm-type behavior for the fourth. Their relation with the eruptive phases is, however, unclear. Above sea level a single cluster of small volcano-tectonic events is observed about 2-3 km below the summit. This cluster displays a rather clear relationship with the eruptive phases and often preceded phases with strong explosive onsets. Most of tremor and explosion quake sources are found just above this cluster.

This study emphasizes the importance of dense, geographically well distributed networks, to identify seismic precursors and decipher volcanic plumbing systems.

How to cite: Battaglia, J., Segovia, M., Hidalgo, S., and Villareal, E.: Tectonic and volcano-tectonic seismicity below Tungurahua volcano (Ecuador) between 2013 and 2018, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9103, https://doi.org/10.5194/egusphere-egu23-9103, 2023.

EGU23-9466 | Orals | SM6.3

Co-seismic Deformation and Source Parameters of the Mw6.0 Düzce Earthquake by InSAR 

Tülay Kaya-Eken, Çağkan Serhun Zoroğlu, Emre Havazlı, and Haluk Özener

23 November, 2022 Mw 6.0 Düzce Earthquake occurred in the west of the North Anatolian Fault Zone (NAFZ) representing a nascent transform fault between the Eurasian Plate and Anatolian Plate. Well-documented seismic sequence along this fault zone started in the east with the 1939 M7.9 Erzincan Earthquake and migrated westward with M>7 earthquakes. Following 1999 Mw7.4 Izmit and Mw7.2 Düzce failures, the next major earthquake was expected to be on the branch of the NAFZ in the Sea of ​​Marmara. However, the 2022 Düzce Earthquake activated already broken Karadere segment during the 1999 Izmit earthquake but release the accumulated strain energy at the north-eastern end of this segment. In this study, we aimed to measure co-seismic surface deformation caused by the 2022 Düzce rupture and determine the source parameters by combining geodetic and geophysical measurements. The co-seismic deformation is analyzed by using Interferometric Synthetic Aperture Radar (InSAR) technique performed on the Sentinel-1 data. The pre- and post-earthquake ascending and descending SAR images were processed using the TopsApp module of the InSAR Scientific Computing Environment (ISCE) software to obtain interferograms of the co-seismic deformation. Our preliminary results show ~30 mm surface deformation. Our preliminary inversion, based on Okada elastic dislocation modeling, resulted in a fault geometry with ~267, 68 and -172 for strike, dip, and rake angles, respectively. This identifies a dominant right-lateral strike slip motion and is fairly compatible with both surface morphological properties of this segment as well as with initial seismology data-based mechanism solutions of various national/international monitoring centers (e.g. KOERI, GEOFON).

How to cite: Kaya-Eken, T., Zoroğlu, Ç. S., Havazlı, E., and Özener, H.: Co-seismic Deformation and Source Parameters of the Mw6.0 Düzce Earthquake by InSAR, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9466, https://doi.org/10.5194/egusphere-egu23-9466, 2023.

EGU23-9610 | Posters on site | SM6.3

Comparison of earthquake swarm detection methods: Case study at Mór Graben, Hungary 

Barbara Czecze, Dániel Kalmár, Márta Kiszely, Bálint Süle, and László Fodor

The seismicity of the Pannonian Basin can be described as moderate. The study area is located in the northern part of the Pannonian Basin, which is one of the most active area in terms of earthquakes.

We found that earthquake swarms occur in the Mór graben quite regularly. The Kövesligethy Radó Seismological Observatory deployed three temporary stations in the graben to monitor the local seismicity, and these stations operated for ca. 20 months. We can study the very small magnitude events because the detection capability is more sensitive from 2020.

After relocating the events with a multiple-event location algorithm, we compare three different real swarm detection methods based on the filtered three-component waveforms, to find the best one to collect a complete swarm event list in the Mór Graben.

Using the temporary and permanent stations of the Kövesligethy Radó Seismological Observatory and the GeoRisk Ltd. networks we can identify more than a hundred swarms with small magnitudes.

Our results show that the Mór Graben is still active, where some of the largest earthquakes occurred in Hungary in the past.

 

How to cite: Czecze, B., Kalmár, D., Kiszely, M., Süle, B., and Fodor, L.: Comparison of earthquake swarm detection methods: Case study at Mór Graben, Hungary, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9610, https://doi.org/10.5194/egusphere-egu23-9610, 2023.

EGU23-10099 | Orals | SM6.3

Apparent stress of moderate sized earthquakes in southern California 

Ralph Archuleta, Chen Ji, and Aaron Peyton

Using S-wave records at epicentral distances less than 60 km we determine the apparent stress for 62 Mw≥4.5 earthquakes in southern California since 2000. All earthquakes have reliable network moment tensor solutions. We compute seismic radiated energy with two methods: a time domain method by Kanamori et al. (2020) and a frequency domain method by Boatwright et al. (2002). The Kanamori approach (GR) is a modified Gutenberg-Richter in which attenuation and near surface effects are not considered. The Boatwright method uses path attenuation, near surface kappa0, and a station specific radiation pattern. With Boatwright we compute seismic energy 1) with an average radiation pattern (F0) and 2) with station specific radiation pattern (F1). The geometric means of apparent stress are 0.48, 0.40 and 0.57 MPa for GR, F0 and F1, respectively. Apparent stress is independent of seismic moment for these earthquakes. Converting apparent stress to Brune’s stress drop (Andrews, 1986), we find stress drops of 2.1, 1.7 and 2.5 MPa for GR, F0 and F1, respectively. From the perspective of seismic radiated energy, a Brune stress drop is nearly the same as that when using Madariaga (1976) and Kaneko and Shearer (2014) models (Ji, Archuleta and Wang, 2022). The standard deviation of stress drop (log10) is 0.35—almost the same for GR, F0 and F1. Cotton et al. (2013) show the standard deviation from stochastic vibration theory used in ground motion prediction equations is 0.15 for Mw>5.5 earthquakes. Seismic moment/corner frequency methods produce a standard deviation of 0.61, though the magnitude range is larger in some studies. Apparent stress (and consequently stress drop) shows a statistically significant depth dependence (~0.05 MPa/km).

How to cite: Archuleta, R., Ji, C., and Peyton, A.: Apparent stress of moderate sized earthquakes in southern California, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10099, https://doi.org/10.5194/egusphere-egu23-10099, 2023.

EGU23-10172 | Orals | SM6.3

Cascading Hazards in a Migrating Forearc-Arc System: Earthquake and Eruption Triggering in Nicaragua 

Machel Higgins, Peter C. La Femina, Armando J. Saballos, Samantha Ouertani, Karen M. Fischer, Halldór Geirsson, Wilfred Strauch, Glen Mattioli, and Rocco Malservisi

Strain partitioning in the Central American convergent margin between the subducting Cocos Plate and Caribbean Plate is accommodated along the Middle America Trench and faults in the forearc-arc regions. In Nicaragua northwest-directed (margin parallel) forearc motion occurs on northeast (margin normal) and northwest (margin parallel) trending faults within the arc. The proximity of active faults and magmatic systems has historically led to magma-tectonic interactions. We investigate the active tectonics of Nicaragua, including a triggered sequence of earthquakes and a volcanic eruption. We use GPS-derived co-seismic displacements and relocated earthquake aftershocks to study the April 10, 2014 (Mw 6.1), September 15, 2016 (Mw 5.7), and September 28, 2016 (Mw 5.5) as a triggered sequence of earthquakes on faults that accommodate forearc motion. Our analyses and modeling indicate that the April 10, 2014 earthquake ruptured a previously unmapped margin parallel right-lateral strike-slip fault in Lago de Managua (Xolotlan) and that the September 2016 earthquakes ruptured mapped arc-normal, left-lateral and oblique-slip faults. The April 10, 2014 earthquake promoted failure of the September 2016 earthquake faults by imparting static Coulomb failure stress changes of 0.02 MPa to 0.07 MPa. Additionally, the September 15, 2016, earthquake promoted failure (static Coulomb failure stress change of 0.08 MPa to 0.1 MPa) on a sub-parallel fault that ruptured five hours after the mainshock. The April 10, 2014 earthquake displaced the flank of Momotombo volcano ~6 cm coseismically and dilated (10s of µStrain) the shallow magma system of Momotombo Volcano, which led to magma injection, ascent, and eruption on December 1, 2015, after ~100 years of quiescence. In total, this sequence represents the potential for cascading hazards in a forearc-arc system, with earthquake and magmatic triggering over short spatial (10’s km) and temporal (yrs) scales.

How to cite: Higgins, M., La Femina, P. C., Saballos, A. J., Ouertani, S., Fischer, K. M., Geirsson, H., Strauch, W., Mattioli, G., and Malservisi, R.: Cascading Hazards in a Migrating Forearc-Arc System: Earthquake and Eruption Triggering in Nicaragua, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10172, https://doi.org/10.5194/egusphere-egu23-10172, 2023.

EGU23-12165 | ECS | Orals | SM6.3

Detection and characterization of seismic sequences in the normal fault system of the Irpinia region, Southern Italy 

Francesco Scotto di Uccio, Gaetano Festa, Maddalena Michele, Gregory C. Beroza, Lauro Chiaraluce, Matteo Picozzi, Antonio Scala, and Mariano Supino

Understanding mechanical processes occurring on faults and catching the preparation phase of large magnitude events require a detailed characterization of the microseismicity, which can be enhanced today using advanced techniques for earthquake detection. These techniques decrease the detection threshold of seismic networks and provide augmented catalogs, which enable improved statistical analysis associated with event occurrence and size. However, seismic events recorded at the level of the noise typically emerge only at a few stations, making earthquake characterization challenging. This issue is further complicated in areas where seismicity occurs deep in the crust, as happens in the normal fault system of the Irpinia region, Southern Italy, where earthquakes occur at depths between 8 and 15 km.

In this work we focus on the detection and characterization of seismic sequences occurring in the Irpinia region featuring low magnitude mainshocks (Ml∼3), using data from the Irpinia Near Fault Observatory.

Event detection for the sequences is performed through the integration of a machine learning based detector (EQTransformer, Mousavi et al., 2020) and a template matching technique (Chamberlain et al., 2018), with the former providing a wider set of templates for the similarity search. This strategy outperforms auto-similarity techniques based on fingerprints (FAST, Yoon et al., 2015) and template matching grounded in manual catalogs. On average, the final catalog of the analyzed sequences increases the manually revised network bulletin by a factor 7. We compared P- and S- arrival time estimates, grounded in the machine learning phase picking and cross-correlation for template matching, using manual identifications to assess the reliability of automatic picks; the mean residual between manual and automatic values is ~0 for both P- and S-waves, with a larger residuals standard deviation for the latter.
We apply a double-difference location technique using both catalog and cross-correlation differential travel times for locating the events, with the goal of resolving and highlighting fault structures where seismicity takes place. We finally track the spatio-temporal evolution of the seismicity, and apply a mechanical model based on static stress, to discriminate whether sequences in the area are mainly triggered by static stress change, dynamic stressing, or aseismic mechanisms such as fluid diffusion.

How to cite: Scotto di Uccio, F., Festa, G., Michele, M., Beroza, G. C., Chiaraluce, L., Picozzi, M., Scala, A., and Supino, M.: Detection and characterization of seismic sequences in the normal fault system of the Irpinia region, Southern Italy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12165, https://doi.org/10.5194/egusphere-egu23-12165, 2023.

EGU23-12252 | Orals | SM6.3

Fast migrating sequences within earthquake swarms 

Josef Vlcek, Tomas Fischer, and Sebastian Hainzl

The hypocenters of earthquake swarms and injection-induced seismicity usually show systematic migration, which is considered to be a manifestation of their triggering mechanism. In many cases, the overall growth of clusters is accompanied by short sequences of rapid migration events, the origin of which is still not sufficiently clarified. We review the possible triggering mechanisms of these migrating episodes and propose a graphical method for distinguishing internal and external triggering forces. We also analyze the theoretical relationship between the evolution of the cumulative seismic moment and the rupture area and propose two models, the crack model and the rupture front model, which can explain the spreading of hypocenters. We developed an automatic algorithm for detecting fast migration episodes in seismicity data and applied it to relocated catalogs of natural earthquake swarms in California, West Bohemia, and Iceland, and to injection-induced seismicity. Fast migration episodes have been shown to be relatively frequent during earthquake swarms (8-20% of cluster events) compared to fluid-induced seismicity (less than 5% of cluster events). Although the migration episodes were detected independently of time, they grew monotonically with time and square-root dependence of radius on time was found suitable for majority of sequences. The migration velocity of the episodes of the order of 1 m/s was found and it anticorrelated with their duration, which results in a similar final size of the clusters in the range of first kilometers. Comparison of seismic moment growth and activated fault area with the predictions of the proposed models shows that both the rupture front model and the crack model are able to explain the observed migration and that the front model is more consistent with the data. Relatively low estimated stress drops in the range of 100 Pa to 1 MPa suggest that aseismic processes are also responsible for cluster growth. Our results show that the fast migrating episodes can be driven by stress transfer between adjacent events with the support of aseismic slip or fluid flow due to dynamic pore creation.

How to cite: Vlcek, J., Fischer, T., and Hainzl, S.: Fast migrating sequences within earthquake swarms, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12252, https://doi.org/10.5194/egusphere-egu23-12252, 2023.

EGU23-12362 | ECS | Posters on site | SM6.3

Persistent shallow microseismicity near a glacier in southwestern Switzerland (Arolla VS) revealed by enhanced earthquake catalogs 

Maria Mesimeri, Tobias Diehl, Marco Herwegh, John Clinton, and Stefan Wiemer

On October 05, 2021 an Mw4.0 earthquake struck 6 km south of the village of Arolla, near the tongue of the Arolla Glacier. Almost one year prior to this earthquake, an M3.5 event occurred on November 08, 2020 in the same location. Both earthquakes were followed by a few aftershocks that were detected and located by the Swiss Seismological Service (SED). The unusually shallow depth of 1-2 km of these earthquakes, indications for a mostly thrust-type mechanisms within a region characterized by a predominantly extensional stress regime, and unusual high CLVD (50-70%) components of SED’s routine moment tensor solutions raised questions regarding the triggering mechanism. To understand and explain the possible existence of shallow thrust earthquakes in the area, we perform a thorough seismotectonic analysis that is based on enhancing the existing earthquake catalog of the SED and complementary moment-tensor solutions computed by multiple algorithms. The original SED earthquake catalog contains 83 earthquakes that occur between January 01, 2020 and December 31, 2021 and locate ~5 km around the two mainshocks. Using a deep learning based algorithm (EQTransformer), we detect additionally 253 events, thus the new catalog contains 4 times more earthquakes than the original SED bulletin. Absolute locations for the additional earthquakes are obtained using the probabilistic NonLinLoc method in combination with a recently updated Vp and Vs crustal 3D velocity model. In addition, we compute local magnitudes (MLhc) using SED’s standard procedure, in order to compile a homogeneous catalog consistent with the SED bulletin. The enhanced catalog events are used as templates for a match filtering scheme, which increased the number of detections by at least one magnitude order. Last, we relocate the final catalog using the double difference method towards obtaining a high resolution enhanced earthquake catalog. Spatially, the main cluster shows an intense seismic activity, stretched in N-S direction that matches the strike of the fault planes derived from moment tensor inversion. An additional cluster, that is not present in the SED bulletin locations, is identified next to the area were the aftershock activity of the two main events locates. Furthermore, the enhanced catalog shows a smother temporal evolution with more background events than previously recorded. Overall, we explore the possibility of fluid driven microseismicity that might be related to the nearby glacier. With our study we emphasize the importance of enhanced earthquake catalogs using both machine learning pickers and template matching algorithms. These approaches lead to unravel prior unmapped structures and improve our understanding of the seismotectonic regime in the study area.

How to cite: Mesimeri, M., Diehl, T., Herwegh, M., Clinton, J., and Wiemer, S.: Persistent shallow microseismicity near a glacier in southwestern Switzerland (Arolla VS) revealed by enhanced earthquake catalogs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12362, https://doi.org/10.5194/egusphere-egu23-12362, 2023.

EGU23-12789 | Orals | SM6.3 | Highlight

Onset of a submarine eruption east of Mayotte, Comoros archipelago: the first ten months seismicity of the seismo-volcanic sequence (2018-2019) 

Jerome van der Woerd, Nicolas Mercury, Anne Lemoine, Cécile Doubre, Didier Bertil, Roser Hoste Colomer, and Jean Battaglia

Since 10 May 2018, an unprecedented seismic activity is observed east of Mayotte Island (France), related to the largest submarine eruption ever recorded with offshore geophysical studies. Using signals from regional and local seismic stations, we build a comprehensive catalog of the local seismicity for the first ten months of the sequence. This catalog includes a total of 2874 events of magnitude (Mlv) ranging from 2.4 to 6.0, with 77% of them relocated using a double difference location procedure. The hypocentral locations over the period May 2018 – February 2019 are highly dependent on the small seismic network available. We therefore compare the locations of later events from a local ocean bottom seismometer network with locations estimated using a similarly small network. Based on the time space evolution and characteristics of the seismicity, five distinct phases can be identified. They correspond to the successive activation of two deep seismic swarms, related to the lithospheric-scale magma ascent up to the seafloor. We also observe progressive deepening of the seismicity interpreted as decompression of a 40 km deep reservoir.

How to cite: van der Woerd, J., Mercury, N., Lemoine, A., Doubre, C., Bertil, D., Hoste Colomer, R., and Battaglia, J.: Onset of a submarine eruption east of Mayotte, Comoros archipelago: the first ten months seismicity of the seismo-volcanic sequence (2018-2019), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12789, https://doi.org/10.5194/egusphere-egu23-12789, 2023.

EGU23-13036 | ECS | Posters on site | SM6.3

Diffusion processes in minor normal faulting seismic sequences monitored by the Alto Tiberina Near Fault Observatory (Northern Apennines, Italy) 

Giulio Poggiali, Monica Sugan, Maddalena Michele, Samer Bagh, Raffaele Di Stefano, Alessandro Vuan, Emanuele Tondi, and Lauro Chiaraluce

The analysis of microseismicity has a fundamental role in understanding earthquakes, giving insights on the long- and short-term driving forces and processes preparing and generating the seismicity occurrence and its evolution in space and time.

Recent advances in detection and location algorithms, paired with dense seismic networks, and supported by higher computing capacity, allow dramatic increase in the quality and quantity of low magnitude earthquakes recorded resulting in high resolution earthquakes catalogs in terms of both location attributes and completeness.

Such catalogs enable us to analyze small magnitude (M<4) sequences having the advantage of a high frequency of occurrence, with unprecedented resolution in illuminating minor (few kilometers of extent) fault systems and seismicity patterns.

We present a detailed analysis of two seismic sequences occurred within an extensional sector of the Northern Apennines between 2010 and 2014: the Città di Castello and Pietralunga sequences (maximum magnitude ≤ 3.6). The area is within the Alto Tiberina Near Fault Observatory (TABOO-NFO), a multidisciplinary monitoring infrastructure dedicated to the investigation of the fault slip behavior of this very low angle normal fault.

The very high microseismic activity, the availability of a dense network and a complex tectonic setting involving shallow (H2O) and deep (CO2) fluids circulation, result in an ideal location to apply modern detection and analysis techniques to study microseismicity in detail.

We build the high-resolution catalog starting from the raw waveforms recorded by a seismic network composed of ~60 stations covering an area of 80x80km and applying a deep learning phase picker. The events are located with a probabilistic nonlinear algorithm and finally relocated with the double differences algorithm after undergoing a quality selection based on location parameters. The resulting catalog for these sequences counts 6 times the number of events documented in previously available standard catalogs.

The spatiotemporal distribution of events shows different characteristics, ranging from foreshock-mainshock-aftershock to more swarm-like patterns but almost all these patterns are compatible with pore-pressure diffusion (1 − 2m2s-1) processes and exhibiting along-strike migration. These are very similar behavior with respect to the ones observed during the larger extensional sequences occurred in the Apennines in recent years.

The case of fluid driven seismicity is coherent with the seismotectonic setting of the area showing large CO2 degassing phenomena and the presence of geologic formations prone to develop fluids overpressure. The comparison of the spatial distribution of events with a three-dimensional deterministic seismostratigraphic model based on different (non-seismic) geophysical data, highlights in fact a ubiquitous involvement of the Triassic Evaporites as hosting lithology, indicating a strong mechanical control and corroborating their seismogenic role.

How to cite: Poggiali, G., Sugan, M., Michele, M., Bagh, S., Di Stefano, R., Vuan, A., Tondi, E., and Chiaraluce, L.: Diffusion processes in minor normal faulting seismic sequences monitored by the Alto Tiberina Near Fault Observatory (Northern Apennines, Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13036, https://doi.org/10.5194/egusphere-egu23-13036, 2023.

EGU23-14089 | Orals | SM6.3

Estimating the rupture directivity and source parameters of moderate to small earthquakes using the second seismic moment  

Arianna Cuius, Haoran Meng, Angela Saraò, and Giovanni Costa

Rupture processes of large earthquakes have been studied by seismic waveform analysis and directivity effects have also been observed in moderate and small earthquakes.

 

This effect leads to azimuthal and spectral variations in ground motion that can be used to estimate the fault plane orientation or a predominant rupture propagation direction in a particular region or during a seismic sequence. For moderate-to-strong events, directivity at low frequencies can result in potentially destructive pulses with large ground motions, while at high frequencies and for small-to-moderate events, the most pronounced effect is the shift in corner frequencies that results in high-frequency energy arriving in short time intervals.

 

It is therefore of the utmost importance to estimate the directivity effects in engineering applications and seismological studies of earthquake sources. While some methods appear to work well for high magnitude earthquakes, determining directivity and source parameters for small to moderate magnitude earthquakes remains a challenge.

 

One of the most common methods to estimate the directivity from moderate to small earthquakes relies on measuring the duration of the source pulse (the apparent source time function) at each location and then modeling it using a line source. Some approaches rely on the deconvolution of waveforms by an empirical Green’s function (eGf), to overcome the problems associated with the presence of path and site effects.

A promising approach for estimating the rupture directivity effect and associated source properties is based on the calculation of the second seismic moments. In this study we apply the method based on the calculation of the second seismic moments to estimate the rupture process and source parameters to study a Mw 4.7 earthquake that occurred in central Italy during the 2016 - 2017 seismic sequence recorded by the RAN (Rete Accelerometrica Nazionale) and RSN (Rete Sismica Nazionale) italian networks.

We first used synthetic apparent source time functions calculated from a geometric source model obtained from a real event to test the robustness of the method. Then, we applied the second-seismic moment method and the approach based on high-frequency S wave amplitude variations versus source azimuths analysis with an empirical Green's function deconvolution approach and compare the results.

 

How to cite: Cuius, A., Meng, H., Saraò, A., and Costa, G.: Estimating the rupture directivity and source parameters of moderate to small earthquakes using the second seismic moment , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14089, https://doi.org/10.5194/egusphere-egu23-14089, 2023.

EGU23-14154 | Posters on site | SM6.3

The activities of the EMERSITO INGV emergency task force following the Mw 5.5 Costa Marchigiana-Pesarese earthquake 

Daniela Famiani, Fabrizio Cara, Giovanna Cultrera, Giuseppe Di Giulio, Sara Lovati, Simone Marzorati, Francesca Pacor, Gaetano Riccio, and Maurizio Vassallo and the EMERSITO working group

EMERSITO is the INGV emergency task force (website available at http://emersitoweb.rm.ingv.it/) with skills and experience in seismic response studies and in seismic microzonation activities, and contributes to emergency interventions following significant seismic events (M>5.0 or lower if a noticeable level of damage is observed).

After the Mw 5.5 (ML 5.7) event of November 9, 2022 06:07:24 UTC (Italian time 07:07:24) localized in the Costa Marchigiana Pesarese area, EMERSITO acted immediately to collect multidisciplinary available information regarding the epicentral area and adjacent areas.

EMERSITO decided to focus the scientific intervention in the municipal area of Ancona which is the main city of the Marche region. This choice was driven by: a) the values of peak ground accelerations observed during the main shock in the city compared with other cities at the same or lower epicentral distance; b) the observed damage, fortunately minor, and evacuations reported by the technicians of Regione Marche and the Fire Brigade; c) the scientific interest in the evaluation of the local seismic response in the urban area that is characterized by strong lithological heterogeneities; d) the presence of an INGV office in Ancona which supported the activities of all the INGV emergency groups, including the EMERSITO working group. The intervention of EMERSITO concerned the installation of a temporary seismic network (registered as 6N; the code was released by FDSN, the Federation of Digital Seismograph Networks) consisting of 11 seismic stations equipped with both velocimetric and accelerometric sensors. A part of these stations (6) has been set up in real-time mode, while the remaining stations (5), have a local acquisition system, requiring periodic maintenance interventions for checking and downloading the data.

At the end of the experiment, after a quality check all continuous data will be transferred to the European Integrated Data Archive (EIDA) repository, with a Digital Object Identifier (DOI) and made public after a pre-established restriction period to allow both preliminary data analysis and a general publication about the intervention of the EMERSITO group.

Site selection for network 6N was planned on the basis of the geological map, damage survey and other information. It was preceded by field inspections in collaboration with the technicians of the Municipality of Ancona and Regione Marche and was supported by colleagues from the INGV headquarter in Ancona. Given the observed variability in the seismic response of the permanent stations, particular attention was paid to the identification of one or more reliable reference sites. The deployment of the network took place between 13 and 17 November.

In this work we present the seismic dataset composed of ambient vibrations and aftershock recordings acquired from the 6N network during the experiment. Preliminary data analysis suggests a variability of the site responses depending on the outcropping lithologies. We believe that the instrumental data acquired by EMERSITO task force, together with the microzonation study available for the municipality of Ancona can increase the knowledge on possible site effects that occurred in different areas of the city after the Mw 5.5 event of November 9, 2022.

How to cite: Famiani, D., Cara, F., Cultrera, G., Di Giulio, G., Lovati, S., Marzorati, S., Pacor, F., Riccio, G., and Vassallo, M. and the EMERSITO working group: The activities of the EMERSITO INGV emergency task force following the Mw 5.5 Costa Marchigiana-Pesarese earthquake, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14154, https://doi.org/10.5194/egusphere-egu23-14154, 2023.

EGU23-15577 | Orals | SM6.3

Using measured and modelled shear-wave velocity profiles for the assessement of site response in Groningen, the Netherlands 

Pauline Kruiver, Manos Pefkos, Xander Campman, Erik Meijles, and Jan van Elk

The site response input in the Groningen seismic hazard assessment is based on modelled shear-wave velocity (VS) profiles. Two sets of data were used to compare in situ (field) and model data of VS. The first set consists of data from several blocks of ~ 400 nodes. Inversion of passive seismic data from a coarse grid of ~ 6 km x 10 km resulted in VS profiles to a depth of 800 m and from a denser grid of ~ 1 km x 1 km more detail to a depth of 100 m. The field VS profiles were a combination these two depth ranges. The site response analysis based on either the field or model VS profiles showed on average similar amplification factors over periods relevant for seismic risk. The model VS profiles are therefore a good representation. The second set consists of VS data from MASW surveys on dwelling mounds. The local detailed field VS profiles reach a depth of 18 m. Site response analyses using the full model VS profiles or profiles with the top 18 m replaced by field VS showed that the amplification on dwelling mounds is underestimated significantly, on average by 7 to 28 %. Because of this, a frequency-dependent Penalty Factor has been derived. In the risk calculations, this Factor is to be applied to buildings on dwelling mounds to transform the estimated motions at the ground surface (based on model VS) into motions at the top of the dwelling mound.

How to cite: Kruiver, P., Pefkos, M., Campman, X., Meijles, E., and van Elk, J.: Using measured and modelled shear-wave velocity profiles for the assessement of site response in Groningen, the Netherlands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15577, https://doi.org/10.5194/egusphere-egu23-15577, 2023.

EGU23-16208 | Orals | SM6.3

Stress transfer between volcanic dyke and seismic activity accompanying the 2021 and 2022 Fagradalsfjall eruptions, Iceland 

Tomáš Fischer, Josef Vlček, Pavla Hrubcová, Jana Doubravová, Þorbjörg Ágústsdóttir, and Egill Árni Guðnason

The 2021 Fagradalsfjall volcanic eruption in the Reykjanes Peninsula, Iceland, was preceded by an intensive earthquake swarm lasting one month. At the end of July 2022, a new intensive earthquake swarm occurred, which was followed on 3 August 2022 by a new effusive flow at the extension of the 2021 effusive fissure. We analyze seismic data of both swarms recorded by the Reykjanet local seismic network to trace the processes leading to the eruption to understand the relation between seismic activity and magma accumulation.

Precise relocations of the 2021 swarm show two hypocenter clusters in the depth range of 1-6 km. The WSW-ENE trending cluster of the 2021 and previous swarms show a stepover of ∼1 km offset, forming a pull-apart basin structure at the intersection with the dyke. This is the place where the 2021 eruption occurred, suggesting that magma erupted at the place of crustal weakening. The pre-eruption seismic activity in 2021 started with a M5.3 earthquake of 24 February 2021, which triggered the aftershocks on the oblique plate boundary and in the magmatic dyke area, in both cases in an area of elevated Coulomb stress. The co-existence of seismic and magmatic activity suggests that the past seismic activity weakened the crust in the eruption site area, where magma accumulated. The following M5.3 earthquake of 24 February 2021 also triggered the seismic swarm and likely perturbed the magma pocket which led to the six-months lasting eruption that started on 19 March.

The relocations of the July 2022 earthquake swarm show that only the northern part of the dyke-related swarm was activated compared to the 2021 swarm and both eruptions are located at the southern tip of the 2022 swarm. We compare the space-time and statistical characteristics of the 24 February 2021 aftershock sequence and of the 2021 and 2022 swarms to relate them to the different expected origin of these seismic activities.

How to cite: Fischer, T., Vlček, J., Hrubcová, P., Doubravová, J., Ágústsdóttir, Þ., and Guðnason, E. Á.: Stress transfer between volcanic dyke and seismic activity accompanying the 2021 and 2022 Fagradalsfjall eruptions, Iceland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16208, https://doi.org/10.5194/egusphere-egu23-16208, 2023.

EGU23-16210 | ECS | Posters on site | SM6.3

Modelling cascading ruptures on near-orthogonal strike-slip fault system: the 2019 Cotabato (the Philippines) earthquake sequence 

Yu Jiang, Shengji Wei, Judith Hubbard, Wan-Lin Hu, and Rino Salman

Earthquake sequences on near orthogonal strike-slip faults are not uncommon, as observed both in the subduction zone outer-rise region (e.g., the 2000 and 2012 Wharton basin earthquakes off-Sumatra, Robinson et al., 2001; Wei et al., 2013) and in the shallow continental crust (e.g., the 1987 Superstition Hills earthquakes, Hudnut et al., 1989; the 2019 Ridgecrest earthquakes, Shi and Wei, 2020). However, according to the Coulomb faulting theory (Anderson, 1951), strike-slip faults intersecting at an angle of around 90° (at 45° from the maximum principal stress) would require a near-zero friction coefficient, which is not consistent with the observed values 0.6~1 in nature, e.g., deep borehole stress measurements (Townend, 2006). Thus, the mechanisms controlling these cascading orthogonal ruptures remain poorly understood. The 2019 Cotabato earthquakes (the Philippines) provide a new opportunity to further explore the driving mechanism causing orthogonal strike-slip earthquakes, since abundant geodetic and seismic data sets are recorded in this sequence.

In this research, we focus on four Mw6.4+ events during the 2019 Cotabato earthquake sequence. Since the fault geometry is critical to analyze the potential stress triggering between earthquakes, careful processing and modelling of the data sets are required to provide a robust and reliable fault geometry. To better constrain the fault geometry, two types of observations were utilized, surface displacement data with a high spatial resolution and ground motion data with a high temporal resolution. (a) Geodetic modelling. We acquired eight ALOS-2 L-band SLC images, and generated ten interferograms monitoring the ground displacement, including seven ascending and three descending interferograms. To avoid the influence of phase unwrapping errors, we improved and applied an art-of-the-state Bayesian geodetic inversion approach (Jiang and González, 2020) by using the InSAR wrapped phase and allowing the estimation of multiple fault geometry simultaneously. (b) Seismic modelling. Seismic waveforms were collected from IRIS, including one regional station and over ten teleseismic stations. We performed Multiple Point Source inversions (Shi et al., 2018) to determine the subevents’ location and double-couple focal mechanism. Geodetic and seismic inversion results were cross-verified and updated to reconcile both datasets. Our results show that (1) in mid-October, the first Mw6.4 earthquake occurred on an NW-SE-striking fault at the depth range of 10-18 km; (2) the second Mw6.6 earthquake ruptured the shallow part of the same fault, followed by the third Mw6.5 earthquake two days later but rupturing a NE-SW-striking fault; (3) in mid-December, the most energetic Mw6.8 earthquake occurred on an NW-SE-striking fault, located at SE of the first two events. Coulomb stress analysis suggests that the friction coefficient on the NE-SW-striking fault has to be very low to allow the rupture on the near orthogonal faults. Our results indicate that the earthquake sequence is a cascading rupture that involved both weak and strong faults in which pore fluid pressure may have played a key role.

How to cite: Jiang, Y., Wei, S., Hubbard, J., Hu, W.-L., and Salman, R.: Modelling cascading ruptures on near-orthogonal strike-slip fault system: the 2019 Cotabato (the Philippines) earthquake sequence, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16210, https://doi.org/10.5194/egusphere-egu23-16210, 2023.

EGU23-1017 | ECS | Orals | SM6.1

Effects of rheological variations, erosion, and geotherm characteristics on tectonic setting and seismic activity in the Val d’Agri (Southern Italy) 

Alessio Lavecchia, Andrea Tallarico, Vincenzo Serlenga, Tony Alfredo Stabile, Giacomo Prosser, Marilena Filippucci, and Stuart Clark

Over the last decades, many studies highlighted the close relationship between thermal structure, surface processes, and tectonic forces in controlling the deformation of the lithosphere. The contribution of these key factors, however, is not constant in time and may result in a complex deformation history, as already observed in many regions around the globe. In this view, the rheology of the crust is pivotal to leading regional tectonic evolution.

Among the factors that may cause remarkable strength and rheological variations in the crust, the presence of fluid phases is undoubtedly one of the most prominent. The mechanisms of rock-fluid interaction are still a debated field of research. However, it has been suggested in many studies that a major effect of fluids is enhanced seismicity of regions where they are present.

In this framework, the Val d’Agri represents a perfect example of how crustal evolution can be influenced by several factors interacting with one another. In this region, we analyze the relationships between different mechanisms in the final structural setting of the region, with implications on the natural and induced seismicity. To this aim, we built up a numerical model that integrates the combined effects of rheological stratification of the crust, inherited zones of weakness, variations in the tectonic regime, surface erosion, and fluid presence. Our results show that variation in the strength of the evaporite layer between the carbonate platform and the basement has a profound impact on the tectonic style of the Val d’Agri. The uplifting and subsidence pattern in the region follows stages of slow vertical movements to stages of very fast uplifting and denudation, due to the activation of new tectonic structures where movement is enhanced. This reflects on pressure and temperature variations in time, that follow typical yo-yo patterns observed in several tectonically active regions. The present-day configuration of the VA is also influenced by the erosion rate. More in detail, a comparison between the observed structures in the area and our model’s results with varying erosion rates suggests that the VA has been subjected to medium to fast erosion during its evolutionary history. In addition, our model predicts the presence and orientation of faults where fluid percolation or injection at high pressure can generate clusters of microseismicity.

How to cite: Lavecchia, A., Tallarico, A., Serlenga, V., Stabile, T. A., Prosser, G., Filippucci, M., and Clark, S.: Effects of rheological variations, erosion, and geotherm characteristics on tectonic setting and seismic activity in the Val d’Agri (Southern Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1017, https://doi.org/10.5194/egusphere-egu23-1017, 2023.

EGU23-1018 | Posters on site | SM6.1

Role of crustal fluids and thermo-mechanical structure for lower crustal seismicity: the Gargano Promontory (southern Italy) 

Andrea Tallarico, Alessio Lavecchia, Marilena Filippucci, Giulio Selvaggi, Gianpaolo Cecere, and Sierd Cloetingh

Several regions around the globe are characterized by a seismically active lower crust, at depths where lithological, thermal and rheological conditions suggest stress release by ductile flow. The Gargano Promontory (GP, southern Italy) is an example where a recently installed seismic network has recorded an intense seismic activity at depths between 20 and 30 km, i.e. in the lower crust. We analyze a possible mechanism controlling the distribution of seismicity in the GP to identify the factors that make the lower crust seismically active. To this aim, we construct a thermo-rheological model of a layered continental crust, calibrated on the basis of geometrical, lithological and thermal constraints. The model takes into account a multiphase crustal lithology, the presence of fluids in the crystalline basement, lateral variations of geotherm and stress field.

The numerical simulations show that the presence of fluids is a key factor controlling the cluster of seismicity in the lower crust. Moreover, the presence of water in the upper crystalline basement and sedimentary cover provides a plausible explanation for upper crustal seismicity in a zone of very high heat flow SW of the GP. The distribution of the seismicity is probably affected by the composition of the crystalline basement, with mafic bodies injected into the crust during the Paleocene magmatic phase that affected the Mediterranean region. Our findings suggest that the presence of hydrous diapiric upwelling(s) in the upper mantle can feed a deep fluid circulation system, inducing lower crustal seismicity.

How to cite: Tallarico, A., Lavecchia, A., Filippucci, M., Selvaggi, G., Cecere, G., and Cloetingh, S.: Role of crustal fluids and thermo-mechanical structure for lower crustal seismicity: the Gargano Promontory (southern Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1018, https://doi.org/10.5194/egusphere-egu23-1018, 2023.

EGU23-1774 | ECS | Orals | SM6.1 | Highlight

Space-time monitoring of groundwaterfluctuations with passive seismicinterferometry 

Shujuan Mao, Albanne Lecointre, Robert D. van der Hilst, and Michel Campillo

Historic levels of drought, globally, call for sustainable freshwater management. Under pressing demand is a refined understanding of the structures and dynamics of groundwater systems. Here we present an unconventional, cost-effective approach to aquifer monitoring using seismograph arrays. Employing advanced seismic interferometry techniques, we calculate the space-time evolution of relative changes in seismic velocity, as a measure of hydrological properties. During 20002020 in basins near Los Angeles, seismic velocity variations match groundwater tables measured in wells and surface deformations inferred from satellite sensing, but the seismological approach adds temporal and depth resolutions for deep structures and processes. Maps of long-term seismic velocity changes reveal distinct patterns (decline or recovery) of groundwater storage in basins that are adjacent but adjudicated to water districts conducting different pumping practices. This pilot application bridges the gap between seismology and hydrology, and shows the promise of leveraging seismometers worldwide to provide 4D characterizations of groundwater and other near-surface systems.

How to cite: Mao, S., Lecointre, A., van der Hilst, R. D., and Campillo, M.: Space-time monitoring of groundwaterfluctuations with passive seismicinterferometry, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1774, https://doi.org/10.5194/egusphere-egu23-1774, 2023.

EGU23-2043 | ECS | Orals | SM6.1

Hydrogeochemical characterization of the waters circulating in the seismically active area of the Pesaro-Urbino province (northern Marche, central Italy) 

Lorenzo Chemeri, Marco Taussi, Jacopo Cabassi, Francesco Capecchiacci, Franco Tassi, Alberto Renzulli, and Orlando Vaselli

The Province of Pesaro-Urbino (northern Marche, central Italy) represents one of most seismically active areas in Italy, since it is interested by the presence of two major composite seismogenic sources: i) the first one is located in the Umbria-Marche Apennines; ii) the second one is along the Adriatic coast from Cattolica to Ancona cities. This area has recently experienced an intense seismic activity, e.g., the 1781 “Cagli Earthquake” with a magnitude of 6.4 Mw, and the 1930 “Senigallia Earthquake” of 5.8 Mw. The last earthquake (5.5 Mw) occurred on November 9, 2022, with its epicenter located in the Adriatic Sea, 35 km away from the city of Pesaro. Since the geochemical knowledge of this area is limited, a large-scale sampling survey was carried out during spring and autumn 2022. A total of 87 samples were collected from different types of emergencies (i.e., cold springs, wells, mineral springs, sulfur springs and ditches) and various geological and tectonic-structural contexts. The study area is dominated by a complex sedimentary structure (e.g., limestones, clays and alluvial deposits) and by climatic and topographic conditions that may influence the chemical and isotopic composition of the investigated fluids. A detailed geochemical characterization is thus of paramount importance in order to define a geochemical background. The aim of this study was to (1) understand the possible interaction of deep-originated fluids and shallow aquifers and (2) evaluate the use of selected geochemical parameters as possible seismic tracers. The results showed the presence of five different geochemical facies: (i) calcium-bicarbonate waters with low TDS (<500 mg/L); (ii) calcium-bicarbonate waters with a strong enrichment in sulfate (up to 200 mg/L); (iii) waters with extreme sodium-carbonate composition and an alkaline pH (>8.8); (iv) calcium-sulfate waters; and (v) sodium-chloride waters. The water isotopic composition showed a clear meteoric origin for all the investigated samples. The composition of major dissolved gases showed two different compositional clusters: (a) N2-dominated gases with N2/Ar ratios similar to those of air and ASW (Air Saturated Water); (b) CO2- and CH4-rich gases pertaining to mineral and sulfur springs. The origin of Ca-HCO3 waters is almost exclusively related to the dissolution of carbonate minerals. On the contrary, Ca-HCO3(SO4) waters are probably originated by deep circulation pathways and interactions with the Upper Triassic Burano Formation, composed by anhydrite layers. The Ca-SO4 waters should be considered as the product of ongoing flows within Miocene gypsum formations, whilst Na-HCO3 waters as the consequence of long-lasting interactions between meteoric waters and silicate rocks (containing albite) in saturation/oversaturation conditions for carbonate-bearing minerals. Finally, the Na-Cl waters probably derive from mixing processes between meteoric and highly saline connate waters trapped into the foredeep clayey deposits. Therefore, the Ca-HCO3(SO4) and Ca-SO4 waters can be regarded as the most interesting fluids to be monitored for a geochemical network aimed at recognizing chemical and isotopic variations related to seismic activity. They are indeed showing a deeper hydrogeological pathway and appear to be less influenced by surface processes.

 

How to cite: Chemeri, L., Taussi, M., Cabassi, J., Capecchiacci, F., Tassi, F., Renzulli, A., and Vaselli, O.: Hydrogeochemical characterization of the waters circulating in the seismically active area of the Pesaro-Urbino province (northern Marche, central Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2043, https://doi.org/10.5194/egusphere-egu23-2043, 2023.

EGU23-2254 | ECS | Orals | SM6.1

Hydrogeologic processes drive deformations in the Matese massif (Southern Italian Apennines) 

Francesco Pintori, Federica Sparacino, and Federica Riguzzi

The Matese massif is an extensive outcrop of Apenninic Platform carbonate rocks located at the boundary between Central and Southern Apennines (Italy), extending ~74 km from NW to SE over an area of ~1600 km² and reaching a maximum height of 2050 m. Its geological history documents different phases of compressional and extensional tectonics which modeled the shape and size of faults within the massif. The present seismotectonic background belongs to the extensional style of the Central-Southern Apennine chain, with a series of NW-SE active extensional faults and occurrence of seismic activity, which reached intensities up to IX MCS.
The karst features of the Matese significantly affect the hydrology of the massif, where rainfall trends lead to large variations in the water reservoirs.
Recent papers report the presence of deformations induced by the elastic response of the loaded surface and the poroelastic properties of the ground. These two mechanisms are different: in the first the water load causes subsidence, in the second uplift. However, under anisotropic conditions, water pressure changes in poroelastic rocks can induce large horizontal deformations especially where highly fractured rocks may provide permeability for fluid flow. When the porosity is determined by systematic fractures, the medium is anisotropic and the surface deformation is mainly perpendicular to the fracture system. To study such processes, we analyzed the time series of 7 GNSS permanent stations located in the Matese area, and the seismicity, covering the 2005-2022 time interval. The GNSS time series of each station were detrended from a best-fitted linear model plus eventual steps due to instrumental changes, without modeling periodicities, obtaining three time series of residual displacements (N, E, Up) for each site. 
We also analyzed spring discharge and pluviometric data. The latter are used to compute the rainfall excess as the difference between the cumulated daily rainfall and the best-fitting straight line of the cumulated rainfall. Then, we applied an Independent Component Analysis to the GNSS data. This allowed us to extract from the time series, in a blind way, a signal very well correlated with hydrological data. This geodetic signal has a large horizontal amplitude and occurs perpendicular to the fracture orientations. This is also shown by the horizontal strain tensor estimated from the displacements associated with this signal, whose maximum extension axis reaches up 1µstrain perpendicular to the fault direction.
During wet periods, characterized by high rainfall excess and increasing values of spring discharge, we observe extensional deformation with stations moving “away” from the massif center; during dry periods a compressional deformation occurs, with stations coming back “toward” the massif. This suggests that the water stored within the massif is the driver of such geodetic signal: the larger the water pressure is, the larger the extensional deformation becomes; when the water level decreases, the water pressure is reduced and then compressional deformation occurs. 
Further studies should be done to understand if water circulation also indirectly affects the background seismicity. 

How to cite: Pintori, F., Sparacino, F., and Riguzzi, F.: Hydrogeologic processes drive deformations in the Matese massif (Southern Italian Apennines), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2254, https://doi.org/10.5194/egusphere-egu23-2254, 2023.

EGU23-4376 | Orals | SM6.1 | Highlight

Earthquakes and helium: evidences of the impulsive nature of earth degassing 

Antonio Caracausi

In seismic regions, fluids play active roles during the preparatory phases of large earthquakes and, through their chemical and isotopic signature, transport to the surface information about deep processes within the fault zones.

In this scenario, noble gases are useful to investigate earth degassing, and their isotopic ratios help to decipher the dynamics of natural processes such as volcanic eruptions and earthquakes. The lightest of noble gases is helium (He), and in natural fluids, it is present with two isotopes, 3He and 4He. The former being mainly primordial and stored in the mantle, the latter continuously produced by U and Th decay in the earth interior. In stable continental region the He flux is dominated by the radiogenic 4He that is produced into the crust (mantle He <1%).  In contrast, primordial 3He escape to the atmosphere in regions of active tectonic (from extensive to compressive).

Experimental studies highlighted that during rocks deformation micro-fracturation increases as an effect of dilation, and consequently, He is liberated from rocks and it escapes towards the pore fluids and successively to the atmosphere. Hence, it indicates a direct link between seismicity and the crustal 4He degassing. However, it is mandatory to know the volume of the rocks involved in earthquakes-induced rock-fracturation to quantify the amount of He released in seismic processes.

Fault zones are complex systems whose mechanical properties evolve over time. Field observations and experimental works allow to schematically simplify these zones into two main structural regions: (1) the fault core and (2) the damage zone. However, the lack of direct observations limits the knowledge of their architecture at depth. Thus, in order to understand the multi-scale, physical/chemical processes responsible for the faulting that earthquakes occur on, it is fundamental to consider phenomena that intersect different scientific research fields. Near Fault Observatories (NFOs) are grounded on multidisciplinary infrastructures, collecting near fault high resolution scientific data that allows generation of innovative observations (Chiaraluce et al., 2022).

Here, we analysed a 12-year earthquake catalogue (M<4) in the IRPINIA NFO (Italy), a region affected by high-magnitude disastrous earthquakes (i.e. M= 7.0 in 1857 and M= 6.9 in 1980).

The analysis of this earthquakes catalogue allows reconstructing year by year the volumes of both the fault core and the damage zone. We computed the 4He output from the two faults zone observing that the low-magnitude earthquakes (M < 4) efficiently contribute to variations of the crustal helium output into the atmosphere. Our results support the impulsive nature of He degassing in tectonically active continental regions (Caracausi et al., 2022). We recognized a quantitative relationship between crustal helium outputs and the volume of fault zones, and  we suggest that variations in helium flux may represent a gauge of changes in the stress field that are related to the nucleation of earthquakes.

 

References

Caracausi et al. (2022). doi:10.1038/s43247-022-00549-9.

Chiaraluce et al. (2022). doi:10.4401/ag-8778.

How to cite: Caracausi, A.: Earthquakes and helium: evidences of the impulsive nature of earth degassing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4376, https://doi.org/10.5194/egusphere-egu23-4376, 2023.

EGU23-5861 | ECS | Orals | SM6.1

The impact of tectonic structures on the 3D scattering imaging of the Central Italy Seismic Sequence 

Simona Gabrielli, Aybige Akinci, Luca De Siena, Edoardo Del Pezzo, Mauro Buttinelli, Francesco Maesano, and Roberta Maffucci

The Amatrice (Mw 6.0) - Visso (Mw 5.9) - Norcia (Mw 6.5) seismic sequence (hereafter AVN) struck the Central Apennines (Italy) in 6-7 months during 2016-2017, and it has been widely associated with fluid migration in the normal faults network. The analysis of attenuation parameters (e.g., scattering and absorption) gives information about material properties and the presence of fluids and fracturing. In this study, we investigate in a 3D mapping the scattering contribution to the total attenuation of the AVN seismic sequence (August 2016-January 2017), together with a pre-sequence dataset (March 2013-August 2016). We applied peak delay as a proxy of seismic scattering, to obtain further information on the fracturing processes in time and space. Previous 2D mapping of peak-delay time and coda attenuation tomography in the same study area indicated a substantial control on the scattering of seismic waves by structural (e.g., Monti Sibillini thrust) and lithological (e.g., Umbria- Marche and Lazio-Abruzzi geological domains) features.
Our 3D results show clear differences between the pre-sequence and the sequence, where we can identify an increase of scattering with time after the mainshocks. The substantial alterations in scattering are observed between 4 - 6 km depth, in the hanging wall of the Monti Sibillini thrust, which acts as a rheological barrier between high and low scattering zones. Peak delay variations detected a significant anomaly in the Triassic deposits layer, at the roots of the Acquasanta thrust, east of Monti Sibillini. Here, low scattering during the pre-sequence epoch is replaced by high scattering during the mainshocks. The low scattering along the Acquasanta thrust suggests an increment of pore pressure, associated with the presence of fluids in this geological formation. The subsequent release of those fluids may have caused the mainshocks of the seismic sequence, and a subsequent increase in fracturing, as observed by the high scattering anomaly. These results bring a new light on the importance to consider the thrusts systems in the tectonic framework of the Central Italy.

How to cite: Gabrielli, S., Akinci, A., De Siena, L., Del Pezzo, E., Buttinelli, M., Maesano, F., and Maffucci, R.: The impact of tectonic structures on the 3D scattering imaging of the Central Italy Seismic Sequence, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5861, https://doi.org/10.5194/egusphere-egu23-5861, 2023.

EGU23-5872 | ECS | Posters on site | SM6.1

Study of interfacial seismoelectric signals in unsaturated pore media 

Ling Zeng, Hengxin Ren, Kaiyan Hu, Xuzhen Zheng, and Changcheng Li

The current theoretical study of the seismoelectric method is based on two sets of the governing equations, one is the electrokinetic coupling coefficient proposed by pride (1994) which is characterized by the zeta potential. The other is the electrokinetic coupling coefficient proposed by Revil & Linde (2006) which is based on the amount of excess charge in the pore volume. In this study, the Luco-Apsel-Chen generalized reflection and transmission method was used to solve the second set of seismoelectric governing equations and separate their interfacial response signals. The correctness of the algorithm is determined by comparing the consistency of the total interface signal with the superposition of the interface signals of each layer. The properties of the interface signals are investigated and it is found that different interface responses contribute differently to the overall signal and that the amplitude and phase of the interface signals are influenced by frequency and medium parameters.

How to cite: Zeng, L., Ren, H., Hu, K., Zheng, X., and Li, C.: Study of interfacial seismoelectric signals in unsaturated pore media, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5872, https://doi.org/10.5194/egusphere-egu23-5872, 2023.

EGU23-6023 | ECS | Posters on site | SM6.1

Seismoelectric conversions due to a ground source in stratified porous media 

Xuzhen Zheng, Hengxin Ren, Changcheng Li, and Ling Zeng

The penetration and diffusion of fluids in fluid-saturated porous media can cause electromagnetic (EM) disturbances due to the electrokinetic effect. These mechanically induced EM waves, often known as the seismoelectric wave fields are sensitive to hydraulic parameters such as porosity and permeability. For in-situ seismoelectric field observations, the source and receivers are usually located at or near the ground surface. However, the current reflectivity-method-based seismoelectric modeling algorithms will suffer computational difficulties due to the slow convergence problem occurring when the source and receiver are located at close or the same depths. To overcome this problem, we extend the peak-trough averaging method to update the seismoelectric modeling algorithm based on the Luco-Apsel-Chen generalized reflection and transmission method. The updated seismoelectric algorithm is then applied to study the seismoelectric coupling phenomena. The results demonstrate that the electric signals recorded by a surface receiver are several milliseconds earlier than their causative seismic waves due to the evanescent seismoelectric conversion. This is capable to interpret similar phenomena reported in seismoelectric field observations over a long history. This time difference may have the potential to identify the location of the groundwater table. Therefore, the updated seismoelectric algorithm is a precise and efficient tool for forward modeling, which also benefits the interpretations of field seismoelectric observations.

How to cite: Zheng, X., Ren, H., Li, C., and Zeng, L.: Seismoelectric conversions due to a ground source in stratified porous media, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6023, https://doi.org/10.5194/egusphere-egu23-6023, 2023.

EGU23-6668 | ECS | Orals | SM6.1

Strain sensitivity of seismic velocity variation induced by hydrological forcing of karst aquifers in the Apennines, Italy 

Stefania Tarantino, Piero Poli, Nicola D'Agostino, Gaetano Festa, Maurizio Vassallo, Gerardo Ventraffrida, and Aldo Zollo

Non-linear response of the elastic properties of the crust has been studied using the analysis of seismic velocity variations induced by various natural forcing agents (earthquakes, tides, volcanic processes, and others). Here we study 1) the variations of seismic velocities in response non-tectonic deformations associated to phases of groundwater recharge/discharge in large karstic aquifers in the Southern Apennines of Italy and discuss 2) the implications in terms of non-elastic behavior of the crust. Karst systems are complex aquifers common within the carbonate rocks of the Apennines. They store large amount of groundwater producing significant horizontal dilatational strains that modulate the secular, tectonic deformation (~3 mm/yr extension across the Apennines) and background seismicity (Silverii et al., 2019; D’Agostino et al., 2018) with seasonal and multi-seasonal signatures. The availability of accurate and temporally-long hydrological measurements (rainfall and karst spring discharge) in addition to dense seismic and geodetic networks provide the opportunity to assess the elastic response of the crust to strain forcing at various periods and the sensitivity of relative velocity variations to non-tectonic, hydrological strain variations. We performed velocity variation measurements on seismic noise autocorrelation signals recorded at seismic stations for different coda waves time lapse and compared them with strain measured by the GPS network. We observe that seismic velocities decrease during dilatation episodes (high hydraulic head) and increase during contraction (low hydraulic head). We find that the retrieved strain sensitivity of seismic velocity changes is of the order of ~103 and discuss such sensitivity with previous natural and laboratory results.

How to cite: Tarantino, S., Poli, P., D'Agostino, N., Festa, G., Vassallo, M., Ventraffrida, G., and Zollo, A.: Strain sensitivity of seismic velocity variation induced by hydrological forcing of karst aquifers in the Apennines, Italy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6668, https://doi.org/10.5194/egusphere-egu23-6668, 2023.

This study investigates the perturbations of the surrounding stress field caused by the cascade effect of Xiluodu and Xiangjiaba reservoirs after impoundment and a three-dimensional pore-elastic coupling model of the impoundment of cascade reservoirs are established. The finite element method calculates the pore pressure field, elastic stress field, and variation of Coulomb stress on local faults. The results show that: 1) the spatial distribution of the earthquake cluster is obviously consistent with the area where the pore pressure increases; 2) The ΔCFS at the epicenters of the April 2014 Yongshan M_L5.1 earthquake and the August 2014 Yongshan M_L5.2 earthquake imparted by the reservoirs are: 0.67kPa and 10.87kPa, respectively, indicating that impoundment promotes these two earthquakes at different levels, and the latter is more significant; 3) The elastic stress field change imparted by the impoundment of Xiluodu reservoir has an impact on the Xiangjiaba Reservoir in the early stage. However, the earthquakes between two reservoirs are possibly triggered by the latter. The Xiangjiaba reservoir increases the pore pressure in its upstream part by 1.0 kPa; 4) the impoundment of the reservoirs increases the seismic risk of the southern section of the Yanfeng fault and the middle section of the Lianfeng fault, while the Manao fault is less affected.

How to cite: Yin, G., Zhang, H., and Shi, Y.: Cascade effects of triggered earthquakes of cascade dams: Taking Xiluodu and Xiangjiaba reservoirs as examples, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7137, https://doi.org/10.5194/egusphere-egu23-7137, 2023.

EGU23-7351 | ECS | Orals | SM6.1

Time-Domain Source Parameter Estimation of natural and man-induced micro earthquakes at The Geysers geothermal field 

Valeria Longobardi, Sahar Nazeri, Simona Colombelli, Raffaele Rea, Grazia De Landro, and Aldo Zollo

Water injection in geothermal areas is the preferential strategy to sustain the natural production of geothermal resources. In this context, monitoring microearthquakes is a fundamental tool to track changes in the reservoirs in terms of soil composition, response to injections, and resource exploitation in space and time. Therefore, the refined source characterization is crucial to better estimate the size, source mechanism, and rupture process of microearthquakes, as possibly related to industrial activities and to identify any potential variation of the background seismicity. Standard approaches for source parameters estimation are ordinarily based on the modelling of Fourier displacement spectra and its characteristic parameters, the low-frequency spectral level and corner frequency. Here we apply a time-domain innovative technique that uses the curves of P-wave amplitude vs time along the seismogram. The methodology allows estimating seismic moment, source radius, and static stress drop from the plateau level and the corner-time and of the average logarithm of P-wave displacement versus time with the assumption of a triangular moment rate function, uniform rupture speed, and constant/frequency-independent Q-factor. In the current paper, this time-domain methodology is implemented to a selected catalog of micro-earthquakes consists of 83 events with moment magnitude ranging between 1.0 and 1.5, occurred during 7 years (2007-2014) of fluid extraction/injection around Prati-9 and Prati-29 wells at The Geysers Geothermal field.

How to cite: Longobardi, V., Nazeri, S., Colombelli, S., Rea, R., De Landro, G., and Zollo, A.: Time-Domain Source Parameter Estimation of natural and man-induced micro earthquakes at The Geysers geothermal field, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7351, https://doi.org/10.5194/egusphere-egu23-7351, 2023.

EGU23-7574 | Posters on site | SM6.1

Monitoring active fumaroles through electrical and magnetic survey: an application to the Pisciarelli fumarolic field (Campi Flegrei, Italy). 

Antonio Troiano, Claudio De Paola, Maria Giulia Di Giuseppe, Carmela Fabozzi, and Roberto Isaia

The hydrothermal area of Pisciarelli, together with the adjacent Solfatara volcano, currently represents the most active structure of the Campi Flegrei caldera in terms of degassing and seismic activity and recently manifesting significant morphological variations, including the opening of new fumarolic vents and mud emission episodes as well as changes in the geochemical characteristics of the gases/fluids. 
To define the structural setting of the Pisciarelli fumarolic field, Electrical Resistivity (ERT) and Time-Domain Induced Polarization (TDIP) tomographies, Self-Potential (SP), Temperature (T), PH and Magnetic (Mag) mapping have been recently realized. 
The geophysical tomographies furnished a 3D model of the area, which reconstructs the Pisciarelli subsurface in its area of maximum degassing, containing the main fumarole (“soffione”) and the mud pool. The comparison of the 3D model with SP, T, PH and Mag maps acquired in the area revealed the occurrence of zones characterized by intense and complex faulting and fracturing processes, affected by fluid circulation, as well as identifying sectors of the subsurface where gases accumulate as also evidenced at the surface by the presence of fumaroles and intense hydrothermal rocks alteration. In particular, the 3D model evidenced an upwelling channel in which fluids stored in a more profound reservoir rise toward the surface. Such a structure seems to be surmounted by a clay-cap formation that could govern the circulation of fluids and the abundance of gases/vapours emitted by the soffione.
The conceptual model proposed for the Pisciarelli fumarolic field suggests plausible mechanisms for explaining, at the same time, the soffione activity and the role played by the deeper origin fluid/gas in the shallow fluid circulation system. In addition, the advance in the understanding of the Pisciarelli fumarolic field setting could also improve the strategy for monitoring the unrest processes in the area and evaluating the associated hazards.

How to cite: Troiano, A., De Paola, C., Di Giuseppe, M. G., Fabozzi, C., and Isaia, R.: Monitoring active fumaroles through electrical and magnetic survey: an application to the Pisciarelli fumarolic field (Campi Flegrei, Italy)., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7574, https://doi.org/10.5194/egusphere-egu23-7574, 2023.

EGU23-7667 | Orals | SM6.1 | Highlight

Seismic Imaging of the Nesjavellir geothermal field, SW-Iceland 

Ortensia Amoroso, Ferdinando Napolitano, Gylfi Páll Hersir, Þorbjörg Ágústsdóttir, Vincenzo Convertito, Raffaella De Matteis, Sveinborg Hlíf Gunnarsdóttir, Vala Hjörleifsdóttir, and Paolo Capuano

The harnessed Nesjavellir geothermal area is one of several geothermal fields on the flanks of the Hengill volcano, SW-Iceland. In this study, we present a detailed seismic imaging of the area through the mapping of the VP, VS and VP/VS ratio using seismic data recorded from 2016 to 2020 and compare them to a resistivity model from the same area and rock temperature measured in boreholes. To obtain reliable initial hypocenter locations and a reference seismic velocity, we solve the coupled hypocenter-velocity problem and obtain a reliable minimum 1D P-wave velocity model for the study area. First, we performed the relocation of all the events in the catalogue using the new 1D velocity model and the estimated  VP/VS value of 1.77. We chose the highest quality events based on the quality of the relocations and used them to perform the 3D tomographic inversion. We used an iterative linearized delay-time inversion to estimate both the 3D P- and S-wave velocity models and earthquake locations.

The results highlight that at depths less than 1 km the crust has a high VP/VS ratio (around 1.9) and low VP and VS values. Low resistivity at comparable depths in the same region has been explained as being due to the smectite clay cap. The observed low VP/VS ratio of 1.64 to 1.70 for depths between 1 and 3 km coincides with high resistivity values. The seismicity in this region, where temperatures often exceed 240°C, seems to be sparse and concentrated near the production wells. This seismicity has been explained as being caused by both production and tectonic activity.  At depths larger than 3 km significant high VP/VS ratio anomaly (>1.9) is observed and coincides spatially with a deep-seated conductive body that domes up at about 4.500 m b.sl. Elevated temperatures are observed above this structure in borehole temperature data. We propose that these signals reflect hot 600-900°C cooling intrusives, close to the brittle ductile transition - possibly the heat source(s) of the geothermal field above. These anomalies are at the same location as the last fissure eruption in Hengill almost 2,000 years ago. A deeper NNE-SSW trending seismic cluster at 3-6 km depth, likely outlining an active fault, is observed at the edge of this high VP/VS anomaly. The heat source of the Nesjavellir geothermal field is most likely connected to this most recent volcanism as reflected by the deep-seated low resistivity body and high VP/VS ratio, located beneath the deep fault that connects the flow path of the high temperature geothermal fluid, resulting in an actively producing reservoir.

The availability of a 3D model represents a starting point for 4D tomography study which will allow us to track changes in crustal properties over time and the estimation of fault mechanisms and kinematic source parameters.

This work has been partially supported by PRIN-2017 MATISSE project, No 20177EPPN2, funded by the Italian Ministry of Education and Research.

How to cite: Amoroso, O., Napolitano, F., Hersir, G. P., Ágústsdóttir, Þ., Convertito, V., De Matteis, R., Gunnarsdóttir, S. H., Hjörleifsdóttir, V., and Capuano, P.: Seismic Imaging of the Nesjavellir geothermal field, SW-Iceland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7667, https://doi.org/10.5194/egusphere-egu23-7667, 2023.

EGU23-7724 | ECS | Orals | SM6.1

Earthquake source parameters in the Zagros region (Iran) from the time of evolutionary P-wave Displacement 

Sahar Nazeri, Fatemeh Abdi, Amir Ismail, Habib Rahimi, and Aldo Zollo

The rupture process of the recent moderate-to-large earthquakes in the longest seismic sector in Iran's plateau, the Zagros area, has been modeled using the strong motion data provided by the Iranian Building and Housing Research Center (BHRC). The selected dataset includes the largest and deadliest seismic event, the 2017 Mw 7.3, Sarpol-e Zahab earthquake. The earthquake source parameters (moment magnitude, source duration, rupture dimension, and average stress drop) are determined by implementing a parametric modeling technique in the time domain based on the time evolution of the P-wave displacement signals. The seismic source parameters are calculated from simulated trapezoidal and triangular moment-rate functions assuming the unilateral rectangle and circular crack models, respectively, where the rupture propagates at a constant velocity as a fraction (90%) of the average shear-wave velocity in the medium. The anelastic attenuation effect assuming the independent frequency-Q parameter ranging from 50 to 200 is accounted for by a post-processing procedure that retrieved the observed moment-rate triangular shape. Hence, the average stress drop with different varies between <Δ𝜎>=1.50 (1.14−1.95) and <Δ𝜎>=0.90 (0.71−1.14) MPa. Assuming a circular rupture model for Sarpol-e-Zahab, we estimate a moment magnitude of 7, rupture duration of 7 seconds, source radius of 16 km, and statistical stress drop of about 3.5 MPa. Alternatively, a unilateral rupture model calculates the fault length and width at 45 and 16 km, with a lower stress drop of 2 MPa.

How to cite: Nazeri, S., Abdi, F., Ismail, A., Rahimi, H., and Zollo, A.: Earthquake source parameters in the Zagros region (Iran) from the time of evolutionary P-wave Displacement, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7724, https://doi.org/10.5194/egusphere-egu23-7724, 2023.

EGU23-8292 | Orals | SM6.1

The role of CO2 degassing in the seismogenic process of the Apennines, Italy 

Francesca Di Luccio and the The FURTHER Team

An accurate survey of old and new datasets allowed us to probe the nature and role of fluids in the seismogenic processes of the Apennines mountain range in Italy. Geodynamics, geophysical and geochemical observations highlight differences between the western and eastern domains of the Apennines, and the main characteristics of the transition zone, which spatially corresponds with the overlapping Tyrrhenian and Adriatic Mohos. Tomographic images exhibit a large hot asthenospheric mantle wedge that intrudes beneath the western side of the Apennines and disappears at the southern tip of the southern Apennines. This wedge modulates the thermal structure and rheology of the overlying crust as well as the melting of carbonate-rich sediments of the subducting Adriatic lithosphere. As a result, CO2-rich fluids of mantle-origin have been recognized in association with the occurrence of destructive seismic sequences in the Apennines. The stretched western domain of the Apennines is characterized by a broad pattern of emissions from CO2-rich fluids that vanishes beneath the axial belt of the chain, where fluids are instead trapped within crustal overpressurized reservoirs, favoring their involvement in the evolution of destructive seismic sequences in that region. In the Apennines, areas with high mantle He are associated with different degrees of metasomatism of the mantle wedge from north to south. Beneath the chain, the thickness and permeability of the crust control the formation of overpressurized fluid zones at depth and the seismicity is favored by extensional faults that act as high permeability pathways. This study strongly relies on the multidisciplinary analysis of different datasets (both existing and newly acquired) with the most advanced methodologies to stimulate the knowledge of the fluid-related mechanisms of earthquake preparation, nucleation and space-time evolution. Ongoing and future investigations will include the continuous and simultaneous geochemical and geophysical monitoring at the scale of the outcropping seismogenic faults to properly decipher the link between earthquake occurrence, surface rupture and fluid release.

How to cite: Di Luccio, F. and the The FURTHER Team: The role of CO2 degassing in the seismogenic process of the Apennines, Italy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8292, https://doi.org/10.5194/egusphere-egu23-8292, 2023.

The Apennines mountain range develops all along Italy, presenting important variations in terms of both structural and tectonic environments, and seismogenic patterns as well. This is observed not only along the main NW-SE chain axis, but also by comparing multidisciplinary observations between the western Tyrrhenian and the eastern Adriatic domains (Di Luccio et al., 2022).

We focus on the southern Apennines, where the Adriatic plate subducts westward under the thinner Tyrrhenian plate and the highest seismic release is documented.

Recent studies showed that fluids play an important role in the seismic behavior of the area. The western domain is associated with heterogeneous and distributed patterns of CO2 gas emission at the surface; the latter ceasing in the east, where high-pressure fluids are trapped in crustal pockets and affect the seismogenic cycle (Chiodini et al., 2004; Improta et al., 2014; Di Luccio et al., 2022 and references therein).

We perform regional-scale P- and S-body waveform analysis and forward numerical modeling, for a selected catalog of crustal events recorded by the broadband seismic stations of the italian network, as well as of temporary passive seismic experiments. We focus on a SW-NE transect, which cross-cuts the southern portion of the Apennines chain, and along which the recorded waveforms exhibit important differences in terms of frequency content and pulse shape. Along the same transect, the waveforms from two events (2013 Mw5 Sannio-Matese and 2014 Mw4.5 Gargano earthquakes) show significant differences in the propagation towards the east and west, respectively.

Starting from two velocity models such as EPcrust (Molinari et al. 2011) and the adjoint tomographic model of Magnoni et al. (2022), we use the finite difference numerical modeling code nbpsv2d (Li et al. 2014) to produce synthetic waveforms to fit and explain the observations. By including information on the earthquake source mechanism and by improving the waveform fit in terms of both arrival time and body-wave coda, we provide new, preliminary information on the crustal structure of the southern Apennines, aimed at improving our understanding of the fluid-seismicity interaction in the area.

 

Research performed in the framework of FURTHER project (https://progetti.ingv.it/en/further).

 

References:

 

  • Chiodini G., Cardellini, C., Amato, A., Boschi, E., Caliro, S., Frondini, F., and Ventura, G. (2004). Carbon dioxide Earth degassing and seismogenesis in central and southern Italy. Geophys. Res. Lett., 31, L07615, doi:10.1029/2004GL019480.
  • Di Luccio et al., (2022). Geodynamics, geophysical and geochemical observations, and the role of CO2 degassing in the Apennines. Earth-Sci. Rev., https://doi.org/10.1016/j.earscirev.2022.104236
  • Improta L., P. De Gori, and C. Chiarabba (2014). New insights into crustal structure, Cenozoic magmatism, CO2 degassing, and seismogenesis in the southern Apennines and Irpinia region from local earthquake tomography, J. Geophys. Res. Solid Earth, 119, 8283–8311, doi:10.1002/ 2013JB010890.
  • Li, D., Helmberger, D., Clayton, R. W., & Sun, D. (2014). Global synthetic seismograms using a 2-D finite-difference method. Geophysical Journal International, 197(2),1166-1183.
  • Magnoni, F., Casarotti, E., Komatitsch, D., Di Stefano, R., Ciaccio, M. G., Tape, C., ... & Tromp, J. (2022). Adjoint tomography of the Italian lithosphere. Communications Earth & Environment3(1),1-12.
  • Molinari, I., & Morelli, A. (2011). EPcrust: a reference crustal model for the European Plate. Geophysical Journal International185(1), 352-364.

How to cite: Scarponi, M., Di Luccio, F., and Piromallo, C.: Waveform modeling of moderate earthquakes for the comprehension of the seismic structure and the fluid-seismicity interaction beneath the southern Apennines (Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8375, https://doi.org/10.5194/egusphere-egu23-8375, 2023.

EGU23-8421 | ECS | Posters on site | SM6.1

Crustal fluid migration and gas-water-rock interaction processes in a seismic area: the case study of the Contursi hydrothermal system (Southern Appenines) 

Dario Buttitta, Giorgio Capasso, Michele Paternoster, Marino Domenico Barberio, Francesca Gori, Marco Petitta, Matteo Picozzi, and Antonio Caracausi

The geochemical characteristics of fluids that emerge at the Earth's surface are influenced by gas-rock-water interactions in the deep and shallow crustal layers, including mixing, outgassing of volatiles, and precipitation of minerals. The goal of the study was to understand the various interactions that influence the migration and behaviour of fluids within the Earth's crust and how they may change during the process of crustal fluid migration towards a hydrothermal system in the shallow crustal layers and within (Contursi basin, Italy). These processes can make it difficult to identify the source of deep gas by using the classical approach based on mixing processes of fluids and carbonate dissolution. Therefore, alternately the relationship between Total Dissolved Inorganic Carbon (TDIC) and the δ13CTDIC in groundwater from the Contursi hydrothermal system investigating the water-gas-rock interaction at the local scale through the detailed reconstructions of the geological framework at depth have been taken into consideration. We found that both the dissolved and free gas in the hydrothermal system probably originated from a deep CO2 endmember with a δ13CCO2 value ranging from +2.12‰ to +3.20‰ (PDB) depending on the presence of brine or freshwater in the local aquifers. However, we observed that this CO2 lost its pristine carbon isotopic signature during its storage in the deep dolomite-composed reservoirs (6-8 km), making it challenging to figure out its deep origin (decarbonation vs mantle/magmatic CO2). Our calculations also showed that the output of CO2, taking into account secondary processes (i.e. degassing CO2 and calcite precipitation) and interactions with water at different salt concentrations, could be at least 40% higher than estimates from the mixing-only approach, such that it is comparable with several active and quiescent worldwide volcanic systems. In order to interpret potential geochemical changes that may occur during future seismic events in sites like Contursi, which are earthquake-prone areas, it is necessary to implement models that can help us understand fluids origin and the processes that influence their chemical and isotopic signature.

How to cite: Buttitta, D., Capasso, G., Paternoster, M., Barberio, M. D., Gori, F., Petitta, M., Picozzi, M., and Caracausi, A.: Crustal fluid migration and gas-water-rock interaction processes in a seismic area: the case study of the Contursi hydrothermal system (Southern Appenines), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8421, https://doi.org/10.5194/egusphere-egu23-8421, 2023.

EGU23-8732 | Posters on site | SM6.1

Grande Comore and Mayotte gas-geochemistry and evidence of deep fluid migration during the 2018-2020 submarine eruption off Mayotte 

Marco Liuzzo, Andrea Di Muro, Andrea Luca Rizzo, Antonio Caracausi, Fausto Grassa, Guillaume Boudoire, Massimo Coltorti, and Bhavani Bénard

Located within the Mozambique Channel, the Comoros archipelago is situated within a complex geodynamic system of great interest owing to recent volcanic and seismic activity (2018-20), but where little gas geochemistry research has been conducted.

Focusing on Grande Comore and Petite Terre, a small islet off the northeast coast of Mayotte, our investigations set out to identify the gas-geochemistry characteristics of the islands, and explore any potential influence from the then ongoing unrest and/or volcanic activity.

Geochemical surveys included measurements of soil CO2 flux on both islands, and gas sampling from fumarolic areas at Karthala volcano (Grande Comore) and two bubbling areas at Petite Terre, with the aim of determining the chemical and isotopic characteristics of the main gases (CO2, CH4, He, Ne, Ar) and equilibrium temperatures of the hydrothermal system at Petite Terre.

δ13C values of soil CO2 emissions highlight evidence of a low magmatic contribution at Grande Comore, while a significantly higher contribution is evident at Petite Terre. 3He/4He data are consistent with average values of fluid inclusions for both Grande Comore and Petite Terre rocks, and are fixed at low value ranges (4.7≤Rc/Ra≤5.9 and 5.3≤Rc/Ra≤7.5 respectively). The gases detected at the two sites of Petite Terre primarily reflect the signature of deep gases in terms of geochemical tracers such as R/Ra and δ13C in CO2.  At one of the two emission sites at Petite Terre, namely the meromictic lake Dziani Dzaha, the gases are relatively more variable in relative proportion of CO2, CH4  and C isotopes; at this specific site, a significant influence from microbial activity is evidenced.

Our results allow us to infer that the general degassing characteristics between the two islands are similar. They also shed light on their reciprocal differences, which may either be attributable to local specifics within Petite Terre, or to different states of volcanic activity between Grande Comore and Petite Terre at the time of the surveys, the latter being a consequence of fluid migration to the mainland of Mayotte during the offshore submarine activity (2018-20).

The outcomes of this work provide a necessary step towards filling gaps in the knowledge of gas-geochemistry in Comoros, and contribute potential support for volcanic and environmental monitoring programmes.

How to cite: Liuzzo, M., Di Muro, A., Rizzo, A. L., Caracausi, A., Grassa, F., Boudoire, G., Coltorti, M., and Bénard, B.: Grande Comore and Mayotte gas-geochemistry and evidence of deep fluid migration during the 2018-2020 submarine eruption off Mayotte, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8732, https://doi.org/10.5194/egusphere-egu23-8732, 2023.

Reservoir-induced seismicity (RIS) related to water-level changes in artificial lakes is a well-documented phenomenon. The best known RIS example is the 6.3 Mw 1967 Koyna-Warna earthquake. However, it must be considered that small-to-moderate magnitude RIS occurs very often, both in relation to water load changes and poroelastic stress perturbation in pre-existing faults. Monitoring the temporal and spatial evolution of RIS is very important for assessing the mechanical state of faults, especially when artificial lakes are located in areas characterized by a high seismic hazard. Indeed, where the crust is affected by the presence of faults with a stress level close to failure, even static stress changes of a few tens of kPa associated with RIS might promote the worst-case scenario of large earthquakes.

Understanding of the physical processes that generate and characterize natural and induced earthquakes, including RIS, is often improved by studying the spatiotemporal evolution of the source parameters obtained through inversion of the seismic data, or by studying the mechanical properties of rocks through seismic velocities. Nevertheless, the source parameters for small magnitude earthquakes such as stress-drop and seismic energy are difficult to estimate, are model-dependent, and, above all, are affected by large uncertainties. Alternatively, the variability of RIS source processes can be investigated by studying the temporal and spatial variability of the ground motion intensity (δBe).

In this work, we investigate the spatiotemporal evolution of ground motion caused by RIS at the Pertusillo artificial lake in southern Italy. The area has a strong seismogenic potential, having been affected in the past by the 1857, Mw 7.0 Basilicata earthquake. We consider ∼1,000 microearthquakes that occurred from 2001 to 2018 and were recorded by a local network of nine seismic stations. The ground motion intensity associated with microseismicity allows us to identify two periods, each lasting approximately 2 years. They are characterized by a high rate of events but exhibit different source properties and spatial distributions. In the first period, the seismicity is spatially clustered close to the lake, on faults with different orientations and kinematics. In the second period, the seismicity is distributed along the Monti della Maddalena faults. Comparing the ground motion intensities of the two periods, we observe that events that occurred in the first period are associated with higher stress levels than others, in agreement with the b-values of the respective frequency-magnitude distributions. We compare the temporal evolution of the ground motion intensity with the rainfall and water levels measured at the artificial lake, as well as with the discharge of a ∼80 km distant spring, which is strictly controlled by climate trends. The results provide information about the regional processes acting on the southern Apennines. Our results show that the microseismicity is clearly associated with the Pertusillo artificial lake in the first period, whereas in the second period is a result of a combination of local effects due to water table oscillations of the lake itself, regional tectonics, and the poroelastic and elastic phenomena associated with carbonate rocks hosting aquifers.

How to cite: Stabile, T. A., Picozzi, M., and Serlenga, V.: Spatio-temporal evolution of ground motion intensity caused by reservoir-induced seismicity at the Pertusillo artificial lake (southern Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9324, https://doi.org/10.5194/egusphere-egu23-9324, 2023.

EGU23-9565 | Orals | SM6.1

Passive seismic and infrasonic monitoring at the Mefite d’Ansanto deep-CO2 degassing site (Southern Apennines, Italy). 

Luisa Valoroso, Spina Cianetti, Pasquale De Gori, Giovanni Diaferia, Carlo Giunchi, Luigi Improta, Davide Piccinini, Luciano Zuccarello, Rocco Cogliano, Antonio Fodarella, Felice Minichiello, Stefania Pucillo, and Francesca Di Luccio

The role of fluids in the preparatory phase of major earthquakes and in the evolution of aftershocks and swarms in space and time is well-documented. In particular, numerous studies evidence the primary role that mantle-derived fluids play in the generation of large upper crustal earthquakes in extensional domains, where crustal-scale faults act as preferential hydraulic pathways.  

We focus on the Mefite D'Ansanto degassing site, the largest low-temperature non-volcanic CO2 emission in the world, located at the northern tip of the Mw6.9 1980 Irpinia faults. The study area experienced strong historical earthquakes (1702, 1732 and 1930 M6+ earthquakes) but it is characterized by a relatively low background seismicity rate with respect to the nearby Sannio and Irpinia regions.    

To collect high-quality microseismicity data in this key sector of the southern Apennine extensional belt and investigate the relationship among seismicity, crustal fluids, and physical-hydraulic properties of the crust, we installed in July 2021 (up to May 2023) a temporary network composed of 10 stations equipped with short-period velocimeters (5 sec). The temporary network covers an area of approximately 30x30 km2 surrounding the Mefite d’Ansanto site and integrates with the numerous permanent stations of the INGV and ISNet networks located at the boundary of the survey area. 

Within the Mefite area, we also deployed a temporary seismo-acoustic dense array to study two CO2 vents. The seismo-acoustic array is composed of 5 infrasonic stations equipped with IST-2018 broadband microphones developed by The ISTerre (Université Savoie Mont Blanc, France), in addition to one seismo-acoustic station equipped with a co-located digital broadband seismometers (120s). The array is positioned approximately at the vertices of a star, with an aperture of about 50 meters. The deployment lasted for 1 week at the end of May 2022, allowing us to sample the emission site during “dry” weather conditions. 

We show first results of the analysis of seismicity recorded by the temporary network applying both standard (STA/LTA) detection algorithms or innovative enhanced techniques such as cross-correlation based template-matching algorithms and/or Deep-Learning-Phase-Recognition methods.

The activities are developed in the framework of the multidisciplinary project FURTHER (https://progetti.ingv.it/en/further).

How to cite: Valoroso, L., Cianetti, S., De Gori, P., Diaferia, G., Giunchi, C., Improta, L., Piccinini, D., Zuccarello, L., Cogliano, R., Fodarella, A., Minichiello, F., Pucillo, S., and Di Luccio, F.: Passive seismic and infrasonic monitoring at the Mefite d’Ansanto deep-CO2 degassing site (Southern Apennines, Italy)., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9565, https://doi.org/10.5194/egusphere-egu23-9565, 2023.

EGU23-9822 | ECS | Posters on site | SM6.1

Monitoring pore-pressure from Vp/Vs ratio around the Costa Molina 2 wastewater disposal well in southern Italy 

Grazia De Landro, Tony Alfredo Stabile, Titouan Muzellec, Vincenzo Serlenga, and Aldo Zollo

Monitoring conditions of the medium embedding the reservoir is strictly required for the hazard assessment in exploited areas.

Fluid injection/extraction operations cause a pressure perturbation into the volume hosting the reservoir which, in turn, may trigger new failures and induce changes in the elastic properties of rocks. Therefore, technologies are needed to reconstruct pore-pressure evolution around injection wells.

To test how the conditions of the reservoir can be monitored noninvasively by using induced micro-seismicity, here we show a rock physics approach aimed to reconstruct the pore-pressure temporal evolution from the changes in Vp/Vs ratio.  

We applied this strategy to the volume affected by the wastewater disposal activity of the Costa Molina 2 injection well, located in the High Agri Valley (Southern Italy) and belongs to the Val d’Agri oilfield, the largest productive onshore oil field in West Europe that produces hydrocarbons (oil and gas) from a fractured carbonate reservoir. We analyzed an enhanced seismic catalogue of the induced micro-seismicity, occurred between 2016 and 2018, that consists of 196 located earthquakes in the magnitude range − 1.2 ≤ Ml ≤ 1.2. For the same period, both seismicity recordings and fluid-injection data are available.

For the evaluation of Vp/Vs ratio with the Wadati formula, the accurate measure of arrival time is critical, especially in case of micro-events. So, we first refined with high precision the first P- and S-wave arrival times by using waveform cross-correlation and hierarchical clustering and selected the events with a high DD location quality; then, we calculated the Vp/Vs ratio for each source-station couple and averaged the ratio values for all the events at the stations nearest to the well (INS1, INS2, INS3) to reconstruct the elastic properties temporal evolution in the source region around the well. 

We found that the Vp/Vs ratio temporal evolution well correlates with injection operational parameters (i.e. injected volumes and injection pressures). With a rock physics model, by using the Pride approach of the Biot theory, we reconstruct the pore-pressure temporal variation starting with the Vp/Vs as known parameters, thus demonstrating the value of seismic velocity monitoring as a tool to complement a monitoring system.

How to cite: De Landro, G., Stabile, T. A., Muzellec, T., Serlenga, V., and Zollo, A.: Monitoring pore-pressure from Vp/Vs ratio around the Costa Molina 2 wastewater disposal well in southern Italy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9822, https://doi.org/10.5194/egusphere-egu23-9822, 2023.

EGU23-11035 | ECS | Posters on site | SM6.1

Interdependent effects of injection volume and rate on fault slip behavior: A large-scale numerical study 

Riddhi Mandal and Semechah Lui

Various injection parameters have been shown to pose significant effects on human-induced seismicity due to a variety of activities such as wastewater injection, carbon storage and geothermal energy production. In this study, we used numerical modeling to investigate how different injection parameters, namely injected volume and injection rate, affect the behavior of faults in the context of fluid-induced seismicity. We tested a large model space (4500 simulations) and modeled injection cases with both spatially homogenous and heterogenous pore-pressure perturbations. Simulation results showed that the two parameters can have various impacts on fault behavior, and that in some cases their effects are interconnected. We discovered that aseismic slip plays a significant role in altering the timing of triggered earthquakes and has lasting impacts on future seismic activity. Moreover, we found that increasing the injection rate tends to increase the size of the triggered cluster of earthquakes, while increasing the injection volume increase the overall rate of earthquakes. We find that spatial heterogeneity has qualitatively similar effects as compared to spatially homogenous cases, with a few quantitative differences. Lastly, we also performed a case study of an injection scenario based on realistic values of pore-pressure diffusion and injection operations in Oklahoma, and we found that for an injection duration of one year, the pore pressure on the faults in the region does not go back to zero even after 70 years and can cause earthquakes years after the end of injection, perturbing the seismic cycles for ~200 years. Our work has potential important implications for safe operation of injection processes which can reduce the risk of seismic hazards.

How to cite: Mandal, R. and Lui, S.: Interdependent effects of injection volume and rate on fault slip behavior: A large-scale numerical study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11035, https://doi.org/10.5194/egusphere-egu23-11035, 2023.

EGU23-11047 | Posters on site | SM6.1

Characteristics of microseismicity in the Kiskatinaw area, northeastern British Columbia, Canada 

Suhee Park, Dabeen Heo, Tae-Seob Kang, Junkee Rhie, Seongryong Kim, and Jan Dettmer

Since the early 2000s, lots of induced earthquakes have occurred due to fluid-injection during the development of unconventional resources at the Kiskatinaw Seismic Monitoring and Mitigation Area (KSMMA) located in northeastern British Columbia, Canada. The spatial-temporal distribution of microearthquakes induced by fluid-injection are important to understand the characteristics of crack and movement of fluid. Also, to mitigate earthquake disasters, it is essential to continuously monitor microearthquakes in fluid-injection areas. We used the seismic data recorded at the EON-ROSE seismic network, which is a dense seismic network consisting of 16 broadband seismic stations, and GSC-BCOGC seismic network to analyze the characteristics of microseismicity of the KSMMA in 2020. We detected the seismic signal (P- and S-wave) using the automatic seismic phase detection method, which is based on the short-term-average to long-term-average ratio (STA/LTA) and kurtosis. And then, we associated the seismic phase arrival data to combine to earthquakes from the automatic seismic phase association method using the temporal distribution of the detected signals and the spatial distribution of the seismic stations used. The hypocenter parameters of associated earthquakes were determined with the HYPOINVERSE location algorithm and the existing 1-D velocity model of KSMMA. The epicenter distributions of the detected earthquakes are concentrated in the area known as active fluid-injection, and the focal depths are also distributed at about 2 km. We analyzed the seismicity by dividing it with three periods based on COVID-19 lockdown and confirmed the low-seismicity of the lockdown period, which is consistent with the result of the independent study performed at the region.

How to cite: Park, S., Heo, D., Kang, T.-S., Rhie, J., Kim, S., and Dettmer, J.: Characteristics of microseismicity in the Kiskatinaw area, northeastern British Columbia, Canada, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11047, https://doi.org/10.5194/egusphere-egu23-11047, 2023.

EGU23-11775 | ECS | Orals | SM6.1 | Highlight

Hydrogeologic and microseismic monitoring as a tool to evaluate fault criticality in karstic regions 

Léa Perrochet, Giona Preisig, and Benoît Valley

Natural groundwater level fluctuation in karstic networks resulting from significant recharge (precipitation and/or seasonal snowmelt) can potentially induce seismicity. Triggering is often considered to be the result of pore pressure diffusion front migrating from the surface to focal depth, assuming a homogeneous crust. Although this assumption can be acceptable in some cases (e.g. homogeneously fractured basement) it is hardly justified in known karstic area. Considering the specific features of karst and data of three case studies, we elaborate a conceptual model of rain-triggered seismicity in karstic regions by identifying potential triggering mechanisms and, using simplified analytical solutions, quantifying their impact on fault stability. Results of this analysis indicate that a direct hydrogeological connection between karstic conduits and the hypocenter can lead to pore pressure variation of the order of MPa, potentially initiating a rupture. To test the conceptual model, field investigations are carried out in the Jura Mountains, a well-known karstic area with low to moderate seismicity. Data acquisition consists in monitoring the natural microseismicity and the flowrate at karstic springs, used as a direct proxy for groundwater level fluctuations.Combining both data sets allows to identify events that are potentially rain-triggered and to acquire a quantitative knowledge on what pressure change, inferred from the hydraulic head increase, is affecting the fault’s stability, a valuable information when planning underground projects.

How to cite: Perrochet, L., Preisig, G., and Valley, B.: Hydrogeologic and microseismic monitoring as a tool to evaluate fault criticality in karstic regions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11775, https://doi.org/10.5194/egusphere-egu23-11775, 2023.

EGU23-12491 | Orals | SM6.1 | Highlight

Adjoint Tomography of the Italian Lithosphere 

Federica Magnoni, Emanuele Casarotti, Dimitri Komatitsch, Raffaele Di Stefano, Maria Grazia Ciaccio, Carl Tape, Daniele Melini, Alberto Michelini, Antonio Piersanti, and Jeroen Tromp

The evolution and state of geological structure at Earth’s surface is best understood with an accurate characterization of the subsurface, where fluid distribution plays a key role. We present high-resolution seismic tomographic images of tectonic and geological features of the Italian lithosphere based on ground motion recordings and obtained through an iterative procedure. Enhanced accuracy is enabled by state-of-the-art three-dimensional wavefield simulations in combination with an adjoint-state method. The resulting tomographic model characterizes the subsurface structure in terms of compressional and shear wavespeed values at remarkable resolution, corresponding to a minimum period of ~10 s. As primary findings of our work, images of the lithospheric structure in Central Italy are consistent with recent studies on the distribution of fluids and gas (CO2) within the Italian subsurface, allowing us to infer the presence of deep melted material that induces shallow gas fluxes, or traps and deep storage of gas that can be correlated with seismicity. We illuminate Mt. Etna volcano and support the hypothesis of a deep reservoir (~30 km) feeding an intermediate-depth magma-filled intrusive body, which in turn is connected to a shallow chamber. We also investigate the intriguing features of the Adriatic plate offshore of the eastern Italian coast. Tomographic evidence reveals a structure of the plate made of two distinct microplates with different fabric and behavior, and separated by the Gargano deformation zone, indicating a complex lithosphere and tectonic evolution.

How to cite: Magnoni, F., Casarotti, E., Komatitsch, D., Di Stefano, R., Ciaccio, M. G., Tape, C., Melini, D., Michelini, A., Piersanti, A., and Tromp, J.: Adjoint Tomography of the Italian Lithosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12491, https://doi.org/10.5194/egusphere-egu23-12491, 2023.

EGU23-12756 | ECS | Posters on site | SM6.1 | Highlight

Centroid full moment tensor analysis reveals fluid channels opened by induced seismicity at EGS, Helsinki region, southern Finland 

Annukka Rintamäki, Gregor Hillers, Sebastian Heimann, Torsten Dahm, and Annakaisa Korja

Understanding fluid injection induced seismicity is key to safe and successful operations of deep geothermal systems. Efficient geothermal energy extraction by an enhanced geothermal system (EGS) requires increased fluid flow between geothermal wells. The experimental 6-km-deep EGS in the Helsinki capital region, southern Finland is an intriguing natural laboratory in a cool Precambrian shield setting that yields excellent seismic data quality. We investigate the source processes of the earthquakes induced by weeks-long EGS stimulations in 2018 and 2020 via a probabilistic waveform fitting method. Detailed resolution of full moment tensor solutions and their opening components can reveal crucial information on earthquake nucleation and fluid flow patterns.

We present results of a centroid full moment tensor analysis for ~250 events from 2018 and 16 events from 2020 in the moment magnitude range 0.5–1.9. We use three-component data of ~30 stations within a 9-km radius of the well-head site. We fit P- and S-phases by modeling synthetic waveforms using Green’s functions with a 20 m grid spacing based on a homogeneous velocity model. We employ automatic high signal-to-noise ratio waveform selection and automatically determined channel-wise correction coefficients for time shifts and amplitude scaling to represent small scale crustal variations not reflected in the velocity model. With the application of both waveform selection and channel corrections, the uncertainty of the moment tensor decreases on average by ~60 % and the location uncertainty by ~85 %. This results in a catalog of well-resolved moment tensors and centroid locations.

The obtained high-quality solutions are dominated by reverse faulting mechanisms with variable compensated linear vector dipole (CLVD) contribution and non-significant isotropic component. The 3D event distribution reveals largest positive CLVD contribution in seismic sources close to the injection well, which indicates localized fracture opening under constant volume with a simultanous adjacent shear event. Farther from the well, seismic sources have pure double-couple mechanisms or even negative CLVD contribution which may be indicative of fracture lengthening or closing under constant volume at later stages of the stimulation.

Identifying clusters with respect to source type and location within the 3D event distribution supports the interpretation of physical source processes and reveals fluid flow channels, and zones of weakness. Events with positive CLVD component occurring close to fluid-filled fractures are potentially nucleated by direct contact with the injected fluid and the associated pore pressure change. Events with zero or negative CLVD component on the outer parts of the seismicity distribution may have been nucleated by poroelastic stress transfers without a direct hydraulic contact to the injected fluid. Our findings suggest that the full extent of injection induced seismicity may not be indicative of fluid flow and thus it should not be used to estimate the extent of an artificially created connected fracture network of a geothermal reservoir.

How to cite: Rintamäki, A., Hillers, G., Heimann, S., Dahm, T., and Korja, A.: Centroid full moment tensor analysis reveals fluid channels opened by induced seismicity at EGS, Helsinki region, southern Finland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12756, https://doi.org/10.5194/egusphere-egu23-12756, 2023.

EGU23-12806 | Posters on site | SM6.1

Seismological temporal patterns at Mefite d’Ansanto CO2 emission field. 

Simona Morabito, Lucia Nardone, Simona Petrosino, and Paola Cusano

Mefite d’Ansanto (Italy) is the largest non-volcanic CO2 emission field on the Earth. The isotopic signature of the CO2 testifies a deep origin of the gases emitted at this site, whose source is probably the mantle wedge beneath the Apennines along the Tyrrhenian side (Chiodini et al., 2010). Mefite is located between the Sannio and the Irpinia seismogenic regions, that are considered among the most active areas of the southern Apennines. The emission site falls at the northern tip of the Irpinia fault system that is associated with the destructive MS = 6.9, 1980 Irpinia earthquake. The gas leakage from this zone is linked to active faulting that characterized the area and determined large historical earthquakes

A temporary acquisition survey close to the Mefite emission field was carried out between 8 June and 28 September 2020 by using a seismic array, named Array MEfite (AME), composed of seven short-period stations. We have analyzed the characteristics of the recorded background seismic noise, e.g., spectral properties, energy temporal pattern (RMS) and polarization (Montalbetti et al., 1970), and estimated site effects (Nakamura, 1989; http://www.geopsy.org/). The seismological temporal patterns have been compared with the meteorological parameters, such as temperature and rainfall, to find possible relationships with exogenous factors. We found a well-defined spatial pattern for the spectral components above 5 Hz, which appear clearly linked to the emission field dynamics. On the other hand, the spectral components below 5 Hz result from the overlapping of multiple sources, of both exogenous, such as anthropogenic and meteorological factors, and endogenous nature. Application of the Independent Component Analysis (ICA) technique (Hyvärinen et al., 2001) contributed to discriminate between natural and anthropogenic sources.

 

References

Chiodini, G., D. Granieri, R. Avino, S. Caliro, A. Costa, C. Minopoli, and G. Vilardo (2010). Non‐volcanic CO2 Earth degassing: Case of Mefite d’Ansanto (southern Apennines), Italy, Geophys. Res. Lett. 37, L11303, doi: 10.1029/2010GL042858.

Hyvärinen, A., Karhunen, J. & Oja, E. (2001). Independent Component Analysis. Wiley, New York,

Montalbetti, J. R., Kanasevich, E. R. (1970): Enhancement of teleseismic body phase with a polarization filter. Geophys. J. Int. 21 (2), 119–129.

Nakamura, Y. (1989). A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface, Railway Technical Research Institute, Quarterly Reports, 30 (1), 25-33.

How to cite: Morabito, S., Nardone, L., Petrosino, S., and Cusano, P.: Seismological temporal patterns at Mefite d’Ansanto CO2 emission field., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12806, https://doi.org/10.5194/egusphere-egu23-12806, 2023.

EGU23-13270 | ECS | Orals | SM6.1 | Highlight

Fluid migration in volcanic environment: thermo-poroelastic modelling of Solfatara crater. 

Andrea Barone, Gianluca Gola, Antonio Pepe, Pietro Tizzani, and Raffaele Castaldo

In volcanic environment, the fluids migration in the crust can affect the evolution of magmatic processes. Meteoric water can for instance infiltrate volcanic rocks developing shallow hydrothermal systems and descending meteoric water may encounter fluids rising up from deep magma feeding system. The accurate tracking of fluid storages and movements turn out to be crucial for the evaluation of the seismic and volcanic activity. Specifically, Campi Flegrei caldera is an example of fluids interaction of different nature, especially at Solfatara crater, where the complexity of this volcanic system is highlighted by diffuse degassing, high temperatures and bradyseism phenomenon.

The Solfatara crater was formed at about 4.2 ka and it consists of a sub-rectangular depression, whose geometry is controlled by N40-50W and N50E trending fault systems. Nowadays, degassing and fumarolic emissions occur at the Solfatara crater, together with a series of small uplift episodes and seismic swarms, particularly from 1984 to 2006 when the whole caldera subsided. Specifically, these earthquakes are likely to be associated with a buried cavity filled with a water-vapour mixture at poor gas-volume fractions.

In this scenario, we propose a 2D multi-physics study of Solfatara volcanic system via the integration of thermodynamic and poroelastic model results.

We start with the first model, for which we collect the available geological and geophysical information, such as the main faults, crustal parameters and the temperature distribution in the conductive regime. This information is merged into a multiphysics Finite Element Model by using COMSOL Multiphysics software: we simulate the crustal thermal regime beneath the Solfatara crater by performing a time-dependent convective thermal model in porous media. We also simulate the fluids circulation in accordance with the Darcy’s Law by considering the bi-phasic water properties (i.e., liquid and vapor states) as approximation to characterize the modelled fluid. Furthermore, the seepage of meteoric water through the high permeable volcanic rocks is also considered. At the end of the simulation, we observe the activation of a convective cell below the Solfatara crater, where the 250°C isotherm reaches ~500 m b.s.l.. The retrieved results is compared with the available data, as the resistivity model proposed by Siniscalchi et al. (2019) and the measured temperature at the CF23 well.

Within the same discretized numerical domain, we perform the second model by considering the previous fluid pore pressure modelled field; we detect the pressure source parameters better explaining the observed ground deformations of Campi Flegrei caldera. The analysed dataset consists of processed SAR images acquired by Sentinel-1A/B satellites constellation during the 2020 – 2022 time interval. We here compare the retrieved stress field within the caldera with the hypocenters distribution.

In conclusion, this study contributes to improve the knowledge about the role of fluids migration in the framework of the magmatic processes.

How to cite: Barone, A., Gola, G., Pepe, A., Tizzani, P., and Castaldo, R.: Fluid migration in volcanic environment: thermo-poroelastic modelling of Solfatara crater., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13270, https://doi.org/10.5194/egusphere-egu23-13270, 2023.

EGU23-14488 | ECS | Orals | SM6.1

Mapping of structures formed by hydraulic fracturing based on microseismic events location. 

Elzbieta Weglinska, Andrzej Lesniak, Andrzej Pasternacki, and Pawel Wandycz

Structures created by hydraulic fracturing can be identified using the location of induced microseismic events. Estimating the effectiveness of stimulation depends on fracture mapping. Event location errors make precise imaging of fractures in a scattered seismic cloud challenging. In order to increase the reliability of the determined structures on the basis of events with location error, we proposed a several-stage procedure. This procedure was demonstrated on microseismic events located during the fracturing of the Wysin-2H/2Hbis horizontal well, an exploration well for shale gas in northern Poland from June 9, 2016 to June 18, 2016. All located events were subjected to a collapsing that allows obtaining new locations of events that are equivalent to original locations in a statistical sense. The creation of such an equivalent point cloud allows us to see certain structures that may reflect, for example, fractures. To validate the results before and after collapsing method, all events were set against the probability of a given brittleness index map.  It is demonstrated that the collapsed events occurred in regions that were more rigid, while the locations of events prior to this procedure showed no relationship with the occurrence of areas with higher susceptibility to fracking. The unsupervised machine learning algorithm HDBSCAN was used on a collapsed cloud to automatically detect clusters of events. The directions of identified clusters agree with the direction of regional maximum horizontal stress.

How to cite: Weglinska, E., Lesniak, A., Pasternacki, A., and Wandycz, P.: Mapping of structures formed by hydraulic fracturing based on microseismic events location., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14488, https://doi.org/10.5194/egusphere-egu23-14488, 2023.

Earthquakes are typically followed by a series of aftershocks. Deeply trapped and internally generated high-pressure fluid diffuses along permeable paths and subsequently reactivates faults that drive thousands of seismic events. The thermal decomposition of CO2 in the carbonate regime in the central Apennines contributes significantly to seismogenesis and provides substantial quantities of internally derived high-pressure fluids. We develop a 3-dimensional model of non-linear diffusion with a source term that diffuses along faults and to the surroundings, triggering seismicity along the flow paths, and compare model results with the spatial and temporal observations from the 2009 L'Aquila (Mw 6.3) and the 2016 Amatrice-Visso-Norcia (Mw 6.5) earthquake sequences. The model mimics the generation of additional fluid by thermal decomposition and shows solid correlations in space by comparing the calculated fluid pressure field and the locations of over 50,000 well-constrained hypocenters.

In contrast, other earthquakes result in only a small number or even no aftershocks. These include the Peru earthquake (Sep. 25, 2013 -Mw 7.1), the Mexiko earthquake (Sep. 19, 2017 - Mw 7.1), and the Crete earthquake (Oct. 12, 2021). Additionally, great earthquakes in Pakistan (Jan. 18, 2011 - Mw 7.2) and Iran ( Apr. 16, 2013 -Mw 7.7) also spawned no aftershocks despite the high magnitudes. These phenomena can be linked to the dynamics of volcanic arcs.

How to cite: Gunatilake, T. and Miller, S. A.: Linking Aftershock-free significant earthquakes to the dynamics of volcanic arcs; and linking aftershock-rich significant earthquakes to devolitization., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15583, https://doi.org/10.5194/egusphere-egu23-15583, 2023.

EGU23-16074 | ECS | Orals | SM6.1

Exploring the characteristics of seismo-electromagnetic signals (SES) in both passive and active experiments 

Ivana Ventola, Gerardo Romano, Marianna Balasco, Michele de Girolamo, Salvatore de Lorenzo, Marilena Filippucci, Roselena Morga, Domenico Patella, Vincenzo Serlenga, Tony Alfredo Stabile, Andrea Tallarico, Simona Tripaldi, and Agata Siniscalchi

Seismo-electromagnetic signals are electromagnetic signals generated by the propagation of a seismic wave in a porous media containing fluids (Gao & Hu, 2010).These signals can potentially provide useful information on the poro-elastic media and the hosted fluids (Garambois & Dietrich, 2002).Thus, there has been a growing interest in the study of SES in recent years, due to their potential.

Researchers are focusing both on modelling and analysis of both passive and active experiments to investigate the characteristics of these signals (e.g. Honkura et al., 2000; Matsushima et al., 2002; Warden et al., 2013; Gao et al., 2016; Balasco et al., 2014; Dzieran et al., 2019).Passive experiments involve the observation and analysis of naturally occurring SES triggered by earthquakes, while active experiments involve the controlled generation of these signals using seismic source.

The aim of our work is to present the results deriving from the analysis of SES recorded with both approaches. As for the passive one, the data set consists of the time series recorded by two magnetotelluric stations in continuous monitoring, co-located with two seismic stations, in seismically active areas of Southern Italy (the Gargano promontory and the Agri valley).

As for the active one, the data set derives by an active seismic experiment carried out in the caldera of the Phlegrean Fields, the Italian super-volcano.

How to cite: Ventola, I., Romano, G., Balasco, M., de Girolamo, M., de Lorenzo, S., Filippucci, M., Morga, R., Patella, D., Serlenga, V., Stabile, T. A., Tallarico, A., Tripaldi, S., and Siniscalchi, A.: Exploring the characteristics of seismo-electromagnetic signals (SES) in both passive and active experiments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16074, https://doi.org/10.5194/egusphere-egu23-16074, 2023.

EGU23-16539 | ECS | Posters on site | SM6.1

Insights into shallow and deep fluid circulation of the Southern Apennines seismic belt (Italy) using borehole pore pressures 

Eleonora Vitagliano, Luigi Improta, Luca Pizzino, and Nicola D'Agostino

Pore pressures at depth are usually described in relation with hydrostatic pressures, implying an interconnection between pores and fractures from the earth's surface up to a certain depth. In some cases, pore pressures exceed hydrostatic values, and these overpressures can be interpreted as an equilibrium between geological pressurization mechanisms (e.g., under compaction, tectonics, hydrocarbon generation, dehydration reactions, various sources of fluids, etc.) and pressure dissipation processes, which mainly depend on rock properties (e.g., hydraulic diffusivity).

In actively deforming regions, other subsurface mechanisms may favor the generation of overpressure (e.g., parallel shortening of strata) and in addition, surface topography may drive meteoric groundwater to flow from positive reliefs to nearby lowlands, interacting with deeper fluids.

Within the framework of the PRIN FLUIDS project, the research presented here aims to study the pore pressures collected in 30 exploration wells of the Sannio and Irpinia regions (Southern Apennines thrust-and-fold belt, Italy), with the objective of clarifying if and how deep fluids (e.g., free gas phases such as CO2 and HCs, as well as saline paleo/formation waters with Na-Cl chemistry and high pCO2) interact with shallow waters and to investigate the relation between shallow and deep crustal fluid dynamics and seismogenesis. In the proposed study, pressures, normalized to a hydrostatic profile, have been first retrieved from borehole pressure data, and then projected on five geological transects, to recognize the spatial distribution of the pressure trends (i.e., hydrostatic, over-pressured and hydrostatic over-pressured zones) underneath the Apennines range (from the internal to the external thrust belt) and the Plio-Pleistocene Bradano foredeep. In addition to the structural features, we also used other information available from well profiles (i.e., litho-stratigraphy, geochemical data, thermal data and petrophysical parameters) and open sources (i.e., geothermal gradient and sedimentary facies distribution maps). This material was integrated with the distribution, at the surface, of deep-derived fluids (gas manifestations, thermal springs, CO2-rich groundwater) to calibrate the system. Moreover, the overall data enabled deepening the comprehension of the role of the pressurized layers in acting as possible vertical and lateral barriers to/for fluid migration, and estimating the possible origin and depths reached by the thermal circuits. Finally, with respect to the distribution of pore pressure zones, two other aspects related to the active deformation and fluid leakage were addressed: vertical stress magnitudes at depth and distribution pattern of low-magnitude background seismicity of the area. The analysis on these topics and the preliminary results will be shown at the end of the proposed workflow.

How to cite: Vitagliano, E., Improta, L., Pizzino, L., and D'Agostino, N.: Insights into shallow and deep fluid circulation of the Southern Apennines seismic belt (Italy) using borehole pore pressures, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16539, https://doi.org/10.5194/egusphere-egu23-16539, 2023.

EGU23-17093 | Posters on site | SM6.1

Application of a time-domain method to estimate the attenuation quality factor from the Geysers geothermal field microearthquake records 

Aldo Zollo, Sahar Nazeri, Jin Zhen, and Grazia De Landro

To determine the crustal rock rheological properties and model wave propagation in an anelastic attenuating medium, it is necessary to determine the quality factor Q, which expresses the fraction of friction-dissipated energy to total seismic energy. Measuring time-broadening of the first P- and S-wave pulses, we propose a time-domain method to estimate the frequency-independent Q parameter of body waved from microearthquake records. We assume a uniform velocity, circular rupture model as represented by a triangular moment rate/displacement function, whose attenuated velocity pulse widths are analyzed in the near-source distance range. The attenuated velocity pulse width data allow the calculation of the source parameters, including rupture duration/radius and stress drop values, as well as the attenuation factor t* (travel distance/quality factor), used to determine the attenuation structure in the study area. It is noted that the constant coefficient of the pulse-width vs t* relationship, required for calculating the t* catalog, have been calibrated for a triangular displacement waveform through simulation analysis. An evaluation of the methodology was carried out on 126 micro-events with Mw ranging from 1 to 3 located around the PRATI-9 and PRATI-29 injection wells at the Geyser geothermal field, California. The analysis of the P- and S-waves indicates a Qp range of 55 to 100 and a Qs range of 89 to 189. To validate the the t* data, we have inverted them to obtain a 1D QP model that matches consistently with the profiles derived from existing tomographic QP models in the area.

How to cite: Zollo, A., Nazeri, S., Zhen, J., and De Landro, G.: Application of a time-domain method to estimate the attenuation quality factor from the Geysers geothermal field microearthquake records, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17093, https://doi.org/10.5194/egusphere-egu23-17093, 2023.

Natural faults host various types of migrating slow earthquake phenomena, with migration speeds much lower than seismic wave speeds and different moment-duration scaling from regular earthquakes. To advance the obtained quantitative understanding of the migration process and long duration of slow earthquakes,  I study a chain reaction model in a population of brittle asperities based on a rate- and state-dependent friction on a 3-D subduction plate boundary. Simulation results show that the migration speed is quantitatively related to frictional properties by an analytical relation derived here. By assuming that local pore water in front of the migration drives rapid tremor reversal and is so local as to hold a constant stress drop, the application of the analytical solution to observational results suggests that (i) the temporal changes of observed migration speeds for the rapid tremor reversal could be explained by about 70% reduction of the effective normal stress; (ii) effective normal stress for the deeper extension of seismogenic segment in the western part of Shikoku is about 1.5 times greater than that in the central part. Applying rupture time delay between slow earthquake asperities for a duration longer than the regular earthquake, I also conclude that (iii) the characteristic slip distance of rate-and-state friction for low-frequency earthquakes is roughly between 30 μm and 30 mm; (iv) the stress and strength drops of very low-frequency earthquakes is much smaller than 1 MPa.

References:

Ariyoshi, K. (2022). Extension of aseismic slip propagation theory to slow earthquake migrationJournal of Geophysical Research: Solid Earth127, e2021JB023800. https://doi.org/10.1029/2021JB023800

How to cite: Ariyoshi, K.: Physical interpretation of slow earthquake migration process based on a friction law, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-204, https://doi.org/10.5194/egusphere-egu23-204, 2023.

With the growing need for CO2 storage, risk management is essential to secure the storage sites; these risks include fault reactivation, ground surface deformation/sea-bottom (uplift), well and caprock integrity, and CO2 leakage; managing these risks could be achieved by understanding the hydromechanical behaviors of rock induced by the reservoir pressure build-up caused by CO2 injection. However, this remains a crucial challenge because the rock's mechanical and hydraulic properties are poorly constrained. Moreover, the conventional monitoring methods usually consider CO2 plume migration only, which is not enough to understand the induced pressure front that occurs far beyond the real pressure plume. Although several techniques could image the geomechanical deformation and investigate the surface deformation well, these monitoring methods do not provide a complete image regarding the deformation migration from the subsurface to the surface due to the limited measurement points in addition to the cost issue.

 In this paper, we will introduce Rayleigh scattering-based Distributed Optical Fiber Strain Sensing (DFOSS) as an effective tool for subsurface and surface geomechanical monitoring to track the dynamic responses at each spatial location along the cable due to the deformation caused by injection; this technology could overcome other conventional methods' limitations including continual spatiotemporal measurements, cost-effective installation: vertically along the wellbore and horizontally into the ground surface, covered area and sea bottom. We will review several laboratory and field experiments from our previous studies. First, we will show the laboratory results from the first laboratory test to track the movement of the CO2 plume as it enters the clay-rich critical regions in the reservoir–caprock system using DFOSS and monitoring of the injected water in a sandstone sample using DFOSS in the second test. Both results demonstrated that DFOSS could provide high-resolution information on deformation and fluid activity. Next, we will show our subsurface monitoring field results, where we conducted several water injection tests in a shallow well. We monitored the injection process by installing DFOSS in a monitoring well. Our outcome confirmed that DFOSS could provide critical information for rocks' properties and fluid migrations by geomechanical monitoring, and it could be a real-time and permanent monitoring tool for wellbore, caprock integrity, and CO2 leakage. Finally, we will show the surface deformation monitoring results, where we installed the fiber cable into the surface horizontally in a shallow trench; the airbag inflation and deflation tests were conducted under the fiber cable to simulate uplift and subsidence caused by the fluid injection and production in the subsurface. The results suggested that DFOSS could locate any anomaly along the cable.

 Our results demonstrate that installation of DFOSS in fiber cables horizontally into the surface around the injection site and vertically in a well to incorporate well-based strain sensing with surface monitoring, allowing geomechanical monitoring (horizontally into the surface and vertically in the subsurface) in three dimensions via a cost-effective, real-time and permanent monitoring system.

How to cite: Amer, R., Xue, Z., and Hashimoto, T.: Geomechanical Monitoring at CO2 storage sites with Distributed Fiber Optic Strain Sensing: Insights from laboratory and Field experiments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1507, https://doi.org/10.5194/egusphere-egu23-1507, 2023.

EGU23-1637 | ECS | Posters on site | TS1.3

Numerical simulation provides conditions for interpreting the groundwater response to Earth tides 

Jose Bastias, Gabriel Rau, and Philipp Blum

Earth tides exert small gravitational variations in the subsurface which lead to pore pressure changes and water level fluctuations in groundwater monitoring wells. This groundwater response to Earth tides has been used to estimate subsurface hydraulic and geomechanical properties. However, existing approaches are based on simplifying assumptions and their reliability has not been tested for realistic conditions. To simulate how Earth tides affect the subsurface, we developed and verified a numerical model that couples hydraulic and geomechanical theories. We modelled the response of a semi-confined aquifer which exchange water with an observation well for the dominant M2 Earth tide component. We reveal that undrained (i.e., groundwater does not flow in response to stress) and confined (i.e., groundwater is under pressure) conditions are necessary for the analytical solution to be valid. For the M2 frequency we assess that this occurs at depths ≤ 50 m and requires specific storage at constant strain sε ≥ 10-6 m-1, hydraulic conductivity of the aquitard kl ≤ 5 • 10-5 ms-1 and aquifer kl ≥ 1 • 10-4 ms-1, respectively. Further, we illustrate that established analytical solutions are valid in unconsolidated systems, whereas consolidated systems require additional consideration of the compressibility ratio between the porous medium and the porous skeleton (i.e., inclusion of the Biot coefficient). Overall, we find that a priori knowledge of the subsurface system increases the reliability of the groundwater response interpretation. Our results improve understanding of the effect of Earth tides on groundwater systems and provide a framework for evaluating subsurface properties.

How to cite: Bastias, J., Rau, G., and Blum, P.: Numerical simulation provides conditions for interpreting the groundwater response to Earth tides, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1637, https://doi.org/10.5194/egusphere-egu23-1637, 2023.

EGU23-2823 | ECS | Posters on site | TS1.3

Experimental evidence for viscous deformation and strain localization in fractured granitoid rocks 

Natalia Nevskaya, Weijia Zhan, Holger Stünitz, Alfons Berger, and Marco Herwegh

According to well-established hypotheses based on field observations of natural faults, viscous deformation may localize following pre-existing brittle fractures. The weak behaviour can be explained by brittle grain size reduction and phase mixing, which may activate grain size sensitive processes in the viscous field. To prove this hypothesis, it is necessary to perform experiments to observe the strain and stress evolution in faulted and non-faulted rocks. Pec et al. (2012) performed experiments on granitic rocks by shearing manually crushed granitic powder between coarse solid granitic forcing blocks. However, in their study, there are unavoidable boundary conditions between the forcing blocks and the gouge, and a comparison to an intact rock without fracture is difficult.

In our study, we reduce the boundary conditions to a minimum and can directly compare the stresses and microstructural evolution during deformation of intact and fractured granitic ultramylonites at 650°C, confining pressure of 1.2GPa, and a constant displacement rate of 10-8m/s. We perform these experiments on initially solid cylindrical samples in two experimental sets: In set A, we slowly apply the load and confining pressure, to ensure an intact rock sample is deformed. In set B, we create fractures before the experiment starts but already in the closed system of the experimental setup. Once experimental P/T conditions are reached, both experimental sets are deformed to different finite strains to investigate the associated microstructural evolution. The deformation is disseminated in the set A experiments, but localizes strongly along the fracture in experimental set B. The strain is accommodated by viscous granular flow incorporating an impressive grain size reduction of up to 1000x and dissolution/precipitation processes. In addition, the stress records show that in experiments A, initially a 30% higher yield stress has to be overcome before steady state flow, while in set B steady state flow is reached directly without a strain softening increment. In both sets, steady state stresses range around 300MPa, i.e. far below the confining pressure.

Applying microstructural observations and mechanical data of our experiments to deformation of granitoid crust in nature reveals that fractures serve to reach mechanical steady state earlier compared to non-fractured crust. As a matter of strain, however, both settings may yield at the same mechanical strengths of resulting shear zones. It is important to note that polymineralic fine-grained ultramylonites are up to four times weaker than monomineralic quartz, presenting an important behaviour of efficient strain localization and rheological properties substantially below those of the end member minerals.

 

Pec, M., Stünitz, H. and Heilbronner, R., 2012. Semi-brittle deformation of granitoid gouges in shear experiments at elevated pressures and temperatures. Journal of Structural Geology, vol. 38, pp. 200-221. https://doi.org/10.1016/j.jsg.2011.09.001

How to cite: Nevskaya, N., Zhan, W., Stünitz, H., Berger, A., and Herwegh, M.: Experimental evidence for viscous deformation and strain localization in fractured granitoid rocks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2823, https://doi.org/10.5194/egusphere-egu23-2823, 2023.

The present mean convergence rate of Himalaya is ~ 15 mm/year. In comparison to the convergence and stress accumulation, only few stress release events represented by greater than M5+magnitude earthquakes in the Himalayan region have been observed. Understanding the constraints leading to the disparity in stress accumulation and stress release, is crucial to understand the stress accommodation mechanism and seismicity in the Himalayas. The current active subduction boundary is marked by Main Frontal Thrust separating the sub-Himalayas and the Gangetic alluvial plains. The rock types within the Main Frontal Thrust sheet show two primary types of sandstone protoliths, and gouges exhibiting cataclastic to foliated microstructural features. In this study, we have performed rotary-shear velocity step experiments on the powdered samples of the sandstone within the Main Frontal Thrust to determine their frictional properties at slow (creep) to fast (seismic) velocity under 10 MPa effective normal stress condition.  We discuss these results and their implications on seismic nucleation in Himalayan Main Frontal Thrust.

How to cite: Sarkar, D. P. and Hirose, T.: Frictional properties of sandstone gouges within Himalayan Main Frontal thrust: constraints on seismicity of shallow crustal deformation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3062, https://doi.org/10.5194/egusphere-egu23-3062, 2023.

EGU23-3401 | ECS | Posters on site | TS1.3

Ambient Stress in Subduction Forearcs Constrained by Numerical Models and Earthquake Static Stress Drop Values 

Gian Maria Bocchini, Armin Dielforder, Kilian B. Kemna, Rebecca M. Harrington, Andrea Hampel, and Onno Oncken

Stress in active subduction forearcs is controlled primarily by friction along the megathrust and the gravitational force. The competing deviatoric compressive and tensional stresses generated by megathrust friction and gravity, respectively, are of the same order of magnitude and result in very low deviatoric stress in the forearc. The near neutral stress state in subduction forearcs is supported by observations of stress reversal, that is a change from deviatoric compression to deviatoric tension, caused by very small megathrust shear stress drops (<10MPa) after recent large megathrust earthquakes. However, studies that quantify and compare the stress state in subduction forearcs at various stages of the seismic cycle are still limited. Here, we use two-dimensional finite-element force-balance models to quantify and constrain forearc stresses at different locations along the Chilean and Japanese subduction margins that are at different stages of the seismic cycle. The models consider forearc topography, slab geometry, crustal thickness, and water load to quantify the elastic stress in the forearc due to gravity and friction along the megathrust. The models indicate low deviatoric stress values (10s of MPa) in the subduction forearcs, which imply a weak forearc crust in areas of active seismic deformation. We validate the model results by estimating seismic stress drop values of forearc earthquakes from high-quality seismic waveform recordings. We estimate spectral corner frequency using both single-spectrum and spectral-ratio estimates and depth-dependent shear-wave velocity models. Spectral-ratio estimates provide more robust corner-frequency estimates that we employ to validate and interpret the increasing stress drop trend down to depths of ~50-60 km. The slight depth dependency of seismic stress drop values is consistent with depth dependency of deviatoric stress obtained from the finite-element models. Moreover, we find that average seismic stress drop values are systematically lower or similar to maximum deviatoric stress obtained from our models, which is consistent with a partial stress release during earthquakes in the forearc. Our results suggest a relation between seismic stress drop values and ambient stress in subduction forearcs.

How to cite: Bocchini, G. M., Dielforder, A., Kemna, K. B., Harrington, R. M., Hampel, A., and Oncken, O.: Ambient Stress in Subduction Forearcs Constrained by Numerical Models and Earthquake Static Stress Drop Values, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3401, https://doi.org/10.5194/egusphere-egu23-3401, 2023.

EGU23-4865 | ECS | Posters on site | TS1.3

Rotation of borehole breakouts by the effect of fractures/faults: observation and numerical model study 

Minzy Kang and Chandong Chang

Borehole breakouts, rock compressive failure at the wellbore wall, are one of the most widely utilized stress indicators, providing useful site-scale in situ stress states for a variety of geo-engineering projects. A 1 km deep vertical borehole drilled to study earthquakes in southeast Korea showed borehole breakouts rotated in azimuth at several depths by as much as 35° from the average azimuth, enlarging uncertainty in representative stress orientation. These breakouts developed in a highly fractured tuffaceous rock at a depth range from 840 m to 1000 m and breakout rotation always occurred adjacent to fractures and faults. While breakout rotation adjacent to fractures/faults has often been observed previously, there are several issues that have to be addressed regarding such a rotation, that is, would it be a local perturbation associated with drilling that can be ignored when assessing representative in situ stress states?; what aspect of fracture perturbs the stress indicator? To address these questions, we carried out a series of 3D finite element modeling, in which the rock mass consists of a single competent rock type (metamorphosed tuff) with a thin and soft planar fracture crossing the model. A borehole penetrates the center of the model vertically. The fracture orientation was varied from model to model for a given far-field boundary stress condition. The model results show that the rotation of breakouts increases generally (but with wide scattering) with an increase in slip tendency of the fracture. A more detailed analysis shows that the azimuthal rotation of breakouts tends to increase in a clearer manner with an increase in the horizontal shear displacement (or shear strain) component along fracture having relatively high slip tendency. For the reasonable values of mechanical properties assumed in the model, the breakout rotation can be as high as ~34° from the boundary stress orientation imposed in the model. Such stress rotation occurs throughout the extent of the fracture and is reflected in breakout rotation. The model results are quite comparable to the breakout rotations observed in the borehole. Our study suggests that breakout rotation is not just a local feature around the borehole but reflects a site-scale stress rotation associated with the presence of fractures having specific orientations and slip direction.

How to cite: Kang, M. and Chang, C.: Rotation of borehole breakouts by the effect of fractures/faults: observation and numerical model study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4865, https://doi.org/10.5194/egusphere-egu23-4865, 2023.

We explore the strength of the lithosphere beneath the Graham Land region (Antarctic Peninsula) using numerical modeling which simulate lithospheric deformation as a function of geological and geophysical parameters. First, we process 21 GNSS time series data spanning 1997–2022 provided by the Nevada Geodetic Laboratory, to produce a robust tectonic velocity solution and calculate a new geodetic strain rate model using an optimal mesh grid definition of 0.5 x 0.5 degrees that best fits our study area. Second, we combine our new geodetic strain rate model with the Moho depth and rheological parameters such as geothermal heat flow (GHF), heat productions and thermal conductivity previously published in the literatures to determine yield strength envelope (YSE) along three profiles (A, B and C respectively) beneath Graham Land. The lithospheric strength values are in a range from 0 to 500 MPa and depend more on strain-rates at the surface and thermal regime (GHF) than on crustal thickness. The highest values for the crust (500 MPa) are mostly concentrated in the profile A, near Cape Alexander, where the second invariant of the strain rate present the smaller value (5-15 μstrain/yr) and the principal strain rates are compressive approximately in the N-S directions. In contrast, the highest values for the mantle mainly depend on the thermal structure of the lithosphere and Moho depth and the highest values are concentrated in the profiles B (297 MPa) and C (279 MPa), in the Trinity Peninsula. Here, the second invariant of the strain rates, present the larger value (50-80 μstrain/yr) and the principal strain rates are extensive in the W-E directions, with a maximum value of 30 μstrain/yr. The results of our study demonstrate that both “jelly sandwich” and “crème brûlée” models are valid for the Graham Land lithosphere, depending on specific thermal and rheological conditions considered.

How to cite: Linsalata, F. and Spada, G.: Strength of the lithosphere derived by geological and geophysics data: the Graham Land (Antarctic Peninsula) case study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5060, https://doi.org/10.5194/egusphere-egu23-5060, 2023.

EGU23-5935 | ECS | Posters on site | TS1.3

A stress field model for the Unterhaching geothermal plant: Challenges and solutions in local model calibration 

Sophia Morawietz, Moritz Ziegler, Karsten Reiter, Oliver Heidbach, Inga Moeck, Ingmar Budach, Hartwig von Hartmann, and Jennifer Ziesch

The stress field of Earth's upper crust is crucial for geodynamic processes and of key importance in planning and managing the utilization of the subsurface, such as geothermal energy extraction, stimulation of enhanced geothermal systems, or safety assessment of deep geological repositories. The contemporary 3-D stress state also provides the basis to assess the impact of induced stress changes which can lead to the reactivation of pre-existing faults, the generation of new fractures, or subsidence due to long-term depletion.

However, information on the stress state of Earth's crust is sparse and often not available for the areas of interest. So far, the stress tensor orientations and stress regimes have been systematically compiled and provided by the World Stress Map (WSM) project in a public-domain database. Yet, the acquisition of stress tensor orientations is not necessarily accompanied by the determination of the stress magnitudes, which, however, are required when investigating questions related to stability and hazard mitigation strategies of georeservoirs. To estimate the 3-D stress state, geomechanical-numerical modelling is applied. For the calibration of such models, stress magnitude data are essential. A major challenge is to bridge the scale gap between the widely scattered data that is required for model calibration and the high-resolution small-scale geological model in the target area. Ziegler et al. (2016) presented a multistage approach to resolve this challenge. For this, two successively calibrated models are created – one large-scale model with coarse resolution but available stress magnitude data for calibration, and one local model with fine resolution, e.g., based on a 3-D seismic survey of the target area, but without any stress data. Synthetic data obtained through the large-scale model is used to calibrate the small-scale local model.

First, we validated the multistage approach by means of generic models to rigorously quantify the associated introduced uncertainties. For this purpose, we implemented a highly simplified model lithology with only vertical stratification and no lateral changes. In a second step, we applied the multistage approach in a real-world setting and demonstrated the applicability on a local model of Unterhaching, south of Munich/Germany, where a geothermal district heating plant is located. Here, a local high-resolution model based on a 3-D seismic survey (Budach et al., 2018) has been successfully calibrated on a regional-scale stress model of the Bavarian Molasse Basin. The results of the local-scale model agree with the large-scale model. At the same time, stress change due to rock property variability, only resolved in the local-scale model, is shown.

How to cite: Morawietz, S., Ziegler, M., Reiter, K., Heidbach, O., Moeck, I., Budach, I., von Hartmann, H., and Ziesch, J.: A stress field model for the Unterhaching geothermal plant: Challenges and solutions in local model calibration, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5935, https://doi.org/10.5194/egusphere-egu23-5935, 2023.

EGU23-6297 | ECS | Posters on site | TS1.3

New steps toward estimating the driving and resistive forces on the Eurasian plate 

Renato Gutierrez Escobar, Candela Garcia Sancho, and Rob Govers

We aim to quantify the likely ranges of magnitudes and directions of forces that may explain present-day natural stresses within the Eurasian plate. We first focus on one of the driving forces, horizontal gravitational stresses (HGSs) resulting from lateral variations in gravitational potential energy, which are particularly relevant in the context of the Eurasian plate because there are no major slabs attached to it (i.e., no slab pull force). We show that different published models of lithospheric density including lateral variations in the lithosphere-asthenosphere boundary result in significantly different HGSs. Other driving forces are mantle convective tractions including dynamic topography, and plate interaction tractions with bounding plates. Second, we include observed major faults into a 2D spherical cap elastic model of the Eurasian plate. We show results of forward FEM calculations based on the best model parameters of Warners et al. (2013) and compare them with observed stress directions. We propose different objective functions that quantify the (relative contributions to the) misfit of the modelled and observed stresses, fault slip directions, and magnitudes, the deviation of the net torque on the plate from zero, and the model representation error. Our study represents a stepping stone towards a Bayesian inference workflow to constrain the dynamics of the Eurasian plate of which we show preliminary results.

Warners-Ruckstuhl, K. N., R. Govers, and R. Wortel, 2013, Tethyan collision forces and the stress field of the Eurasian Plate: Geophys. J. Int., v. 195, no. 1, p. 1–15, doi:10.1093/gji/ggt219.

How to cite: Gutierrez Escobar, R., Garcia Sancho, C., and Govers, R.: New steps toward estimating the driving and resistive forces on the Eurasian plate, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6297, https://doi.org/10.5194/egusphere-egu23-6297, 2023.

EGU23-6615 | ECS | Posters on site | TS1.3

Weakening of granitoid gouge in hydrothermal ring shear experiments 

Weijia Zhan, Natalia Nevskaya, André Niemeijer, Alfons Berger, Chris Spiers, and Marco Herwegh

Fault gouges of granitoid composition represent the principal non-cohesive tectonites within fault zones in the continental crust. The spatial distribution and strength of granitoid fault gouges is therefore crucial for understanding how weak the upper continental crust could be due to the formation of fault zones. Although several laboratory investigations reported the mechanical weakening of granitoid gouges in shear experiments, the deformation mechanism responsible for such behavior remains not well understood.

To address this issue, we conducted two series of shear experiments on granitoid gouges by using a ring shear apparatus. The starting gouge powders were derived from crushed granitoid mylonite with a median grain size of 45 μm. In a first set of experiments, gouges were sheared at a sliding velocity of 100 μm/s for a displacement of 15 mm. Temperatures explored ranged from 20°C to 650°C in order to determine the temperature dependence of gouge strength. The second set of experiments is identical to the first ones, except that the applied sliding velocity was set at 1 μm/s to study how fault slip rate influences the strength of gouges.

We observe that differences in gouges strengths as a function of sliding velocity and temperature: At a sliding velocity of 100 μm/s, the steady-state shear stress (τ) remains relatively constant at τ=76-82 MPa over the entire temperature range. Contrastingly, at a sliding velocity of 1 μm/s the steady-state shear stress remains temperature-insensitive with τ≈75 MPa up to tempertures of 450°C, but decreases then to τ≈50 MPa at 650°C (Fig.1 a). Furthermore, the amount of decrease of shear stress is strain dependent (Fig.1 b). At even slower sliding velocity of 0.1 µm/s, the shear stresses decrease further to τ≈38 MPa.

Microstructurally, all gouges deformed at T≦450°C show typical cataclastic features, where angular clasts with grain size of ~10 μm are surrounded by a fine-grained matrix. Intergranular fracture arrays in Riedel- and Y-shears are well developed over the entire cross section, indicating homogeneous bulk deformation. In contrast, gouges sheared at 650°C with τ≈50 MPa show strain localization in a principal slip zone. It is shear plane parallel with widths up to ~50 µm. Inside the principal slip zone, all grains are dramaticly reduced to nm-size and tightly packed. No intergranular fracture arrays are observed. Outside the principal slip zone, rounded grains with size of ~5 μm are loosely packed, with meniscus cement growing in between. The aforementioned strain localization is enhanced at temperature above 450°C and slip rate below 1μm/s, suggesting that viscous creep mechanisms (e.g. pressure solution) control the deformation process at slow sliding velocities, which is not the case in fast rate experiments. Our results show that the activation of viscous creep mechanisms leads to significant fault zone weakening, while contrasts in grain size keep deformation localized.

Figure 1 Shear stress plotted as a function of temperature. Shear stress data collected at (a) 15mm displacement in steady-state, and at (b) 5mm displacement.

How to cite: Zhan, W., Nevskaya, N., Niemeijer, A., Berger, A., Spiers, C., and Herwegh, M.: Weakening of granitoid gouge in hydrothermal ring shear experiments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6615, https://doi.org/10.5194/egusphere-egu23-6615, 2023.

The North Alpine Thrust Front (NATF) is an example of the classical onshore fold-and-thrust belt and foreland system [1]. There are ongoing heat production projects in this area. However, complex compaction and stress fields require detailed investigation for safe and economical drilling activities. Previous field investigation of the wedge and foredeep shed light on the possible driving mechanisms for overpressure generation in the wedge, foredeep and footwall in the SE of Germany. To do this, 20 deep wellbores are selected in this area and their geophysical and drilling data are investigated [2]. This study is a complementary work to find possible explanations for observations through numerical modeling. Examining the mechanics behind these complex deformations is beyond the capabilities of the critical taper theory. However, a large strain geomechanical numerical simulator coupled with critical state soil mechanics constitutive model can provide useful insights in this regard. Geomechanical forward modeling requires boundary conditions at far distances. Also, except some basic geometrical features, other deformations are not predefined and they are developing during the simulation. Therefore, it is not only insightful regarding the final shape of the system, but also progressive development of the deformations is trackable [3].  A plane-strain framework is implemented to simulate the interested processes through the Elfen software [4]. A quasistatic criterion is assumed throughout the simulation to decrease the possible boundary effects of the loading. Adaptive-remeshing helps to capture the large-strain behavior of the system in a reasonable computational time. Data from different sources of the drilling, geophysical tools and field observation is used to tune the model and test the capability of the model to estimate the required properties. Numerical simulations result in a similar geometry which is observed in the field works. Obtained stress values and pore pressure are comparable to the field data.  The differences between the simulation results and field observations can be attributed to the assumptions which were made during the simulation. For example, thermal impacts and possible diagenetic processes are neglected during the simulation. Also, a homogeneous material is assumed for the different layers, while in the real case, there are heterogeneities inside the layers.

1. Pfiffner, O, A. (1986) “Evolution of the North alpine Foreland Basinn in the central Alps”, Foreland Basins, 219-228.

2. Drews, M., Duschl, F. (2022) “Overpessure, vertical stress, compaction and horizontal loading along the North Alpine Thrust Front, SE Germany”, Marine and Petroleum Geology, 143, 105806.

3. Albertz, M., Sanz, P, F. (2012) “Critical state finite element models of contractional fault-related folding: Part 2. Mechanical analysis”, Tectonophysics, 150-170

4. Rockfield (2017) “Elfen explicit manual (Version 4.10)”, Swansea, UK, Rockfield Software.

How to cite: Mahmoodpour, S., Drews, M., and Duschl, F.: Geomechanical forward modeling of the stress field, pore pressure and compaction in the North Alpine Thrust Front, SE Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7038, https://doi.org/10.5194/egusphere-egu23-7038, 2023.

EGU23-7497 | Orals | TS1.3

Shear resistance and near-field stresses on rough faults 

Yuval Tal and Lior Wise

Natural faults are rough at all scales and can be described with fractal geometry. This deviation from planarity results in geometric asperities and a heterogeneous stress field. Analytical and numerical studies have shown that roughness introduces additional shear resistance on the fault and promotes failure in the medium surrounding the fault because of the elevated stresses. These studies generally assume a small slip on the fault, i.e., much smaller than the minimum roughness wavelength, λmin. It is important to examine the effects of roughness on shear resistance and near-fault stresses at large sliding, as well as the assumptions incorporated in the derivation of the analytical solutions.

In this study, we examine the effects of fault geometry on the shear resistance and near-fault stresses at large sliding numerically, using a method that is based on the mortar finite element formulation, in which non-matching meshes are allowed across the fault, and the contacts are continuously updated. This enables modeling slip larger than λmin and the overriding of asperity contacts. We begin with simulations of an elastic medium and show that, indeed, the roughness results in large and heterogeneous stresses on and off the faults, which increase with the roughness level. However, except for small slip values, the increase of shear resistance with slip is much smaller than the linear increase predicted by the analytical models, which assume small and uniform slip. For self-similar geometry, with Hurst exponent of H = 1, the average shear resistance increases with slip at a decreasing rate. For self-affine geometry, with H < 1, it initially increases with slip, then decreases at a slip larger than λmin /2. Although overriding of asperities is allowed in the simulations, as slip increases, significant stress concentrations are developed on the fault, which may not be realistic for natural rock surfaces. To account for that, we implement wear laws into the method and model the evolution of stresses during a quasistatic slip and cycles of dynamic earthquakes. The wear process redistributes and bounds the stresses on the fault and allows a more realistic characterization of stress distribution near the fault.

How to cite: Tal, Y. and Wise, L.: Shear resistance and near-field stresses on rough faults, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7497, https://doi.org/10.5194/egusphere-egu23-7497, 2023.

EGU23-8377 | ECS | Orals | TS1.3

Structural and frictional control on the transient deepening of the seismogenic zone following major earthquakes in Central Italy 

Giuseppe Volpe, Maria Eugenia Locchi, Giacomo Pozzi, Elisa Tinti, Marco Scuderi, Chris Marone, and Cristiano Collettini

After many large earthquakes aftershocks activity can reach depths greater than the base of the seismogenic zone that is defined by background seismic activity. This observation is generally explained by strain rate induced embrittlement associated with the increase of post-mainshock strain rate, which favors a transition from ductile to brittle behavior. However, the underlying physical processes are not well understood. Here we integrate geological and geophysical data for the 2016–2017 Central Italy seismic sequence with laboratory experiments to provide a geological and physical interpretation for the post-mainshock transient deepening of the base of the seismogenic zone.

The base of the seismogenic zone in the central-northern Apennines is set typically at 9-10 kilometers and corresponds to the top of the phyllitic basement. Structural studies on exhumed basement rocks highlight a heterogeneous basement fabric consisting of competent, 10 to 200 m wide, quartz-rich lenses surrounded by an interconnected and frictionally weak phyllosilicate-rich matrix. The matrix controls the overall rheology of the basement due to its interconnectivity, and promotes aseismic deformation because its rate-strengthening behavior.

Following each major (Mw > 5.5) event of the 2016–2017 sequence, a dramatic and abrupt increase in seismic rate is observed below 10 km, hence within the basement. Here we document the presence of seismicity clusters made of more than 4 earthquakes and characterized by small magnitude (Mw < 2.5), small dimensions (< 500 meters), small temporal duration (< 14 days) and a swarm-like behavior. Furthermore, these clusters are often represented by multiple or repeating earthquakes with a cross correlation coefficient higher than 0.7 for all the three components. These observations suggest that the increase of shear stressing rate within the basement is responsible for deepening of seismicity. To further explore this idea, we performed laboratory experiments on rocks from exhumed outcrops of basement rocks. We found that shear stressing rate promotes accelerated creep on the phyllosilicate-rich matrix and dynamic instabilities on the quartz-rich gouge belonging to the lenses.     

Our integrated analysis suggests that the mainshocks of the 2016-2017 seismic sequence promoted an increase of shear stressing rate within the basement allowing the phyllosilicate-rich matrix to creep faster hence favoring the loading and the repeated failures of locked seismogenic patches represented by the quartz-rich lenses.

How to cite: Volpe, G., Locchi, M. E., Pozzi, G., Tinti, E., Scuderi, M., Marone, C., and Collettini, C.: Structural and frictional control on the transient deepening of the seismogenic zone following major earthquakes in Central Italy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8377, https://doi.org/10.5194/egusphere-egu23-8377, 2023.

EGU23-8980 | ECS | Orals | TS1.3

Continental lithosphere deformation is a response to its thermodynamically controlled critical crustal thickness 

Ajay Kumar, Mauro Cacace, and Magdalena Scheck-Wenderoth

We study the present-day thermo-mechanical state of the Alpine Himalayan Collision Zone to understand the physics controlling the observed crustal differentiation and the underlying continental-wide geodynamics. We found that the stability of the lithosphere is regulated by a thermodynamically controlled critical crustal thickness (Cr), which is close to the average thickness of the continental crust. Regions with thickness higher than Cr, representing orogenic lithosphere, and higher than average potential energy undergo weakening and dissipate the acquired internal energy, compared to their foreland lithospheres that have crustal thickness close to Cr. A weaker orogenic lithosphere deforming in a dissipative mode to release the acquired potential energy manifests as zones of diffused rather than focused deformation. We additionally find that the energy dissipation path that the orogenic lithosphere takes to either attain Cr (cratonization) or to undergo runaway instability (rifting) is modulated by the feedback between the thermal and mechanical relaxation of the lithosphere. The internal energy stored in the crust from heat-producing elements, fastens the dissipation of the acquired potential energy.

How to cite: Kumar, A., Cacace, M., and Scheck-Wenderoth, M.: Continental lithosphere deformation is a response to its thermodynamically controlled critical crustal thickness, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8980, https://doi.org/10.5194/egusphere-egu23-8980, 2023.

EGU23-10150 | ECS | Orals | TS1.3

SpannEnD – Prediction of the recent crustal stress state of Germany using a 3D geomechnical-numerical model 

Steffen Ahlers, Karsten Reiter, Tobias Hergert, Andreas Henk, Luisa Röckel, Sophia Morawietz, Oliver Heidbach, Moritz Ziegler, and Birgit Müller

For the safe usage of the subsurface the stress state is of great importance, e.g., for borehole stability, mitigation of induced seismicity or the search and long-term safety of a high-level nuclear waste deposit. However, the state of knowledge concerning the stress state in Germany is limited as only unevenly distributed stress measurements are available which frequently provide only one component of the stress tensor. The SpannEnD (Spannungsmodell Endlagerung Deutschland) project aims to improve this knowledge with the help of a 3D geomechanical-numerical model. The model is calibrated on available stress magnitudes and enables a continuum-mechanics based prediction of the stress state and its local variability for Germany.

The 3D geomechanical-numerical model comprises the upper lithosphere and contains 22 lithological units parametrized with individual mechanical properties (Young’s modulus and Poisson’s ratio) and densities. Linear elasticity is assumed and the finite element method (FEM) is used to solve the equilibrium of forces. Overall, the model contains about 11 million hexahedral elements resulting in a lateral resolution of 2.5 x 2.5 km2 and a vertical resolution of up to 250 m. The model is calibrated by adaptation of displacement boundary conditions with magnitudes of the minimum (Shmin) and maximum horizontal stresses (SHmax). The model results show an overall good fit with these stress magnitudes used for calibration indicated by a mean of the absolute stress differences of 4.6 MPa for Shmin and 6.4 MPa for SHmax. Furthermore, the results agree well with additional data sets excluded from calibration but used for validation, e.g., with a mean of the absolute stress differences of 1.1 MPa for vertical stress magnitudes and an absolute mean deviation of the orientation of SHmax with regard to World Stress Map data of 11.9°.

How to cite: Ahlers, S., Reiter, K., Hergert, T., Henk, A., Röckel, L., Morawietz, S., Heidbach, O., Ziegler, M., and Müller, B.: SpannEnD – Prediction of the recent crustal stress state of Germany using a 3D geomechnical-numerical model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10150, https://doi.org/10.5194/egusphere-egu23-10150, 2023.

An essential feature of plate tectonics is that lithospheric deformation is localized at plate boundaries with substantially larger magnitude than that in plate interiors, suggesting that lithospheric rheology is weaker at plate boundaries than in plate interiors. Numerous mantle convection modeling studies that approximate this empirically derived lithospheric rheology using different formulations or proxies (e.g., pre-existing weak zones, faults, reduced coefficient of friction or yield stress, …) have largely reproduced the observed features of lithospheric deformation. While the rheological formulations in theoretical modeling studies have become increasingly more sophisticated often with an expressed goal to understand the cause of plate tectonics and initiation of subduction, it is important to place constraints on lithospheric rheology using in-situ observations including flexural (i.e., vertical motion) and seismic response to different forcings. Laboratory studies indicate that lithospheric deformation is controlled by frictional sliding, low-temperature plasticity (LTP) and high-temperature creep with increasing temperature. Observations of lithospheric flexure and seismicity at Hawaiian Islands (i.e., plate interior setting) in response to volcanic construction suggest that internal frictional coefficient µf is 0.25, while LTP is significantly weaker than that derived from laboratory studies [e.g., Mei et al., 2010], based on modeling studies of loading response of Hawaiian lithosphere with realistic elasto-frictional-plastic-viscous rheology [Zhong and Watts, 2013]. Further studies [Bellas and Zhong, 2021; Bellas et al., 2020; 2022] showed that µf is 0.3 and activation energy of LTP needs to be reduced from laboratory derived value of 320 KJ/mol to 190 KJ/mol to fit the flexural and seismic deformation at Hawaii, and that the same rheological parameters reproduce the observed elastic thickness at other oceanic islands and seamounts on lithosphere of different ages. The Japan subduction zone shows characteristic features of subducting lithosphere with its outer rise and trench topography and transition from shallow normal/extensional faulting to deep reverse/compressional faulting seismic deformation (i.e., neutral plane) [e.g., Craig et al., 2014]. Dynamic deformation models of subduction have been formulated, using realistic slab buoyancy force and elasto-frictional-plastic-viscous rheology, to interpret the observations of trench-outer rise topography and neutral planes [Han et al., 2022]. The modeling indicated that the observed neutral plane in the Japan subduction zone is consistent with the rheology for subducting lithosphere with LTP activation energy of ~220 KJ/mol and µf~0.3, which are similar to that inferred for the plate interior at Hawaii. The modeling also found that µf<0.1 that is required to generate mobile-lid or plate tectonic convection in mantle convection models [e.g., Moresi and Solomatov, 1998] would not generate the extensional to compressional stress transition (i.e., neutral plane) in the Japan subducting lithosphere, further suggesting the importance of in-situ observational constraint on lithospheric rheology and dynamics of plate tectonics. 

How to cite: Zhong, S., Han, S., and Bellas, A.: Constraints of Flexural and Seismic Observations on Lithospheric Rheology at Plate Interior and Plate Boundary Settings, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11786, https://doi.org/10.5194/egusphere-egu23-11786, 2023.

EGU23-12847 | ECS | Posters on site | TS1.3

Slip tendency analysis of 3D faults in Germany 

Luisa Röckel, Steffen Ahlers, Sophia Morawietz, Birgit Müller, Karsten Reiter, Oliver Heidbach, Tobias Hergert, Moritz Ziegler, Andreas Henk, and Frank Schilling

For many underground operations such as geothermal energy exploitation, mining, oil and gas production or the storage of high-level radioactive waste, active tectonic or induced seismicity is of concern. Seismicity usually occurs on pre-existing faults that are reactivated under adequate stress conditions. Thus, an assessment of the reactivation potential of faults can aid in the identification of areas particularly prone to the occurrence of seismic events or such areas where adequate geotechnical measures have to be taken to avoid anthropogenic fault reactivation. A tool for the assessment of the fault reactivation potential is the so called slip tendency, which is the ratio between the maximum resolved shear stress on the fault plane and the normal stress. Such an analysis requires information about the stress field acting on the fault plane and information about the fault geometry, fault orientation and frictional properties. Information about these parameters can be very limited, since 3D fault geometries are often only extrapolated from geological surface data. Furthermore, stress data is usually sparse, only available pointwise and unevenly spatially distributed. Geomechanical-numerical modelling can be used to derive a spatially comprehensive description of all six independent components of the stress tensor from the available stress data.   

For Germany, an estimate of the stress tensor is provided by the geomechanical-numerical model by Ahlers et al. (2022). Furthermore, fault geometries as part of geological models of the German federal states are available for large parts of Germany. We use both the stress data derived from the geomechanical-numerical model and the fault geometry data from the federal state models to calculate slip tendencies for more than 10.000 faults and fault segments. The resulting slip tendency is generally the highest in the northern Upper Rhine Graben area where it routinely reaches values of 0.7 and more. In the Alpine and Alpine Foreland region the slip tendency is generally the lowest with values only very rarely exceeding 0.3. In North Germany slip tendency values range mainly between 0.3 and 0.6 but with both higher and lower values being fairly common. In general, faults striking in NNE-SSW direction and NW-SE direction display the overall highest slip tendencies whereas faults striking in ENE-WSW direction show very low slip tendencies. With increasing depth slip tendencies generally decrease strongly. However, there are still major areas in Germany where either no fault geometries or only insufficient fault geometries are available. Furthermore, pore pressure has a major influence on the slip tendency. For our calculations, we assume hydrostatic pore pressure. While overpressured pore fluid is documented for example for the Molasse Basin in South Germany, no spatially comprehensive pore pressure data set is currently available for the whole of Germany.

How to cite: Röckel, L., Ahlers, S., Morawietz, S., Müller, B., Reiter, K., Heidbach, O., Hergert, T., Ziegler, M., Henk, A., and Schilling, F.: Slip tendency analysis of 3D faults in Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12847, https://doi.org/10.5194/egusphere-egu23-12847, 2023.

EGU23-13718 | Posters on site | TS1.3

If you get the stress data, you've always asked for 

Karsten Reiter, Oliver Heidbach, Moritz Ziegler, Silvio Giger, Rodney Garrard, and Jean Desroches

The upper Earth crust is increasingly used by mankind, to extract, transport, store or dispose materials, energy, or waste. Regardless of the objective, long term safety and stability is essential and thus, the contemporary stress state of the upper crust is one of the key variables. To estimate a continuous description of the 3‑D stress tensor, geomechanical numerical models are used. The most important parameters to set up such models are the knowledge of the underground structures, the distribution of rock properties as well as the stress data, on which the models are calibrated. In the model, the vertical stress results from the gravitational volume forces due to the density distribution and the horizontal stresses from the Poisson effect as well as appropriate lateral displacement boundary conditions. The latter are determined by finding a best-fit with respect to given stress magnitude data of the maximum and minimum horizontal stress SHmax and Shmin, respectively.

A unique dataset of stress magnitude data has been recently acquired within the exploration phase for deep geological repository of radioactive waste in Switzerland. Nine cored boreholes in three potential siting areas have been drilled and besides a wide range of logging runs, and laboratory tests of rock properties, more than 120 Mini-Hydraulic Fracturing (MHF) and Sleeve Re-Opening (SR) tests were successfully performed in different stratigraphic units to estimate the magnitudes of Shmin and SHmax

Here, we present a 3‑D geomechanical-numerical model that shows both, the best-fit to the measured stress magnitudes as well as the range of stress magnitude variability in the volume of the different stratigraphic units. This variability results from MHF/SR measurements uncertainties and from the variation of rock properties within the lithologies. Furthermore, one has to assess how representative each MHF/SR measurement is for a larger rock volume. To represent the stress variability within the lithologies, many model simulations that cover the distribution of possible rock parameters were performed. The distribution is given by the cumulative density function (CDF) for the Youngs modulus and the Poisson number for each stratigraphic unit. Based on the range of model simulations we visualize the variation of the stress components along virtual well paths in analogy to the statistical variation. Such plots allow to quantify and visualize the potential variation of the present-day stress state within the stratigraphic column because of the petro-physical variability within the stratigraphic units. Furthermore, using the CDF, we can assign to each model simulation a probability that allows us also to estimate a probability distribution of the stress variability in the different units.

How to cite: Reiter, K., Heidbach, O., Ziegler, M., Giger, S., Garrard, R., and Desroches, J.: If you get the stress data, you've always asked for, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13718, https://doi.org/10.5194/egusphere-egu23-13718, 2023.

EGU23-13795 | Orals | TS1.3

Integrated stress determination at the KTB deep crustal laboratory 

Carolin Boese, Marco Bohnhoff, Oliver Heidbach, and Georg Dresen

One main goal of the Continental Deep Drilling Program (KTB) of the Federal Republic of Germany was to establish a continuous stress profile from the surface to the final drilling depth of 9.1 km. To characterize stresses with depth, several independent methods were applied: analyses of borehole failure such as borehole breakouts/drilling-induced tensile fractures; hydraulic fracturing mini-tests at several intervals ≤3 km depth as well as two modified hydraulic tests at 6 and 9 km depth; and core disking and strain retardation of core samples. Focal mechanisms of induced seismic events from fluid injection experiments were inverted for stress estimates at different depths. Since then, the KTB is known as a world-class site with regard to crustal stress data. In particular, stress magnitude estimates are still among the deepest and fewest high-quality estimates derived at crustal depth.

The GEOREAL fluid injection experiment aims to characterize the geothermal potential at the KTB site at 4 km depth and to refine the adaptive reservoir stimulation concept employing near-real-time microseismic monitoring with direct feedback on hydraulic parameters. Additionally, a goal of GEOREAL is to investigate spatial and temporal stress variations at this depth. We noticed new borehole breakouts in the open hole section of the pilot well KTB-VB, likely due to the massive fluid production and injection experiments between 2002 and 2005. Together with new logging and seismic data from GEOREAL, these stress estimates will be used to further characterize the stress field from the borehole to the reservoir scale.

The GEOREAL hydraulic stimulation will include a series of hydraulic tests at ≥3.9 km to investigate the effect of pressure build-up and release, the role of continuous and periodically varying flow rates, the effect of relaxation phases and maximum injection pressure on the spatio-temporal propagation of induced seismicity. Induced events will be monitored with high precision using a 12-level geophone chain in the KTB main hole at only ~300 m distance to the stimulation interval. This will be used to determine stress estimates from focal mechanism inversion of induced events on a 100-m source scale.

To better understand the role of the local stress field we use a 3-D geomechanical-numerical model (10 x 10 x 10 km3) of the KTB. This offers a unique opportunity to utilize the detailed knowledge of the subsurface at the KTB site, in particular due to the existing 3-D structural model, high-quality rock property estimates from laboratory work, high-quality stress magnitude data, and new information from GEOREAL. The model provides a continuous description of the 3-D stress field including its changes due to the variability of rock properties to assess the in-situ stability of the intact rock mass and faults. This allows for further detailed studies that require the undisturbed in-situ stress state as one key observable and input parameter to characterize deep geothermal reservoirs and associated processes such as induced seismicity.

How to cite: Boese, C., Bohnhoff, M., Heidbach, O., and Dresen, G.: Integrated stress determination at the KTB deep crustal laboratory, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13795, https://doi.org/10.5194/egusphere-egu23-13795, 2023.

EGU23-13955 | Posters on site | TS1.3

The 3D stress field of Nordland, northern Norway - insights from numerical modelling 

Sofie Gradmann, Marie Keiding, Odleiv Olesen, and Yuriy Maystrenko

The Nordland area in NW Norway is one of the tectonically most active areas in Fennoscandia. It exhibits patterns of extension, which are in contradiction to the first-order regional stress pattern that reflects compression from ridge-push. The regional stress field stems from the interaction of ridge push and GIA (glacial isostatic adjustment); the local stress field mainly results from gravitational stresses, as well as the flexural effects of sediment erosion and re-deposition.

We develop 3D finite element numerical models of crustal scale, using existing geometric constraints from previous geophysical studies. Internal body forces, induced by variations in density, topography or Moho depth, already yield significant deviatoric stresses, which are often omitted in stress models. We show that these can strongly influence the near-surface stress regime, in particular for the continental-margin setting we are considering. Similarly, existing weakness zones (such as faults) control the local stress field.

We apply the far-field stress fields (GIA, ridge-push, sediment redistribution) as effective force boundary conditions to the sides or base of the model. This way, we can account for all stress sources at once, but can also vary them separately in order to examine their relative contributions to the observed stress and strain rate fields.

We compare our models to the stress and strain observations derived from different recent seismological and geodetic data sets. These point to a correlation of seismicity with major changes in the crustal geometry.

How to cite: Gradmann, S., Keiding, M., Olesen, O., and Maystrenko, Y.: The 3D stress field of Nordland, northern Norway - insights from numerical modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13955, https://doi.org/10.5194/egusphere-egu23-13955, 2023.

EGU23-14316 | Posters virtual | TS1.3

Lithospheric rheology and strength in La Palma Island (Canary archipelago) 

Silvia Martín-Velázquez, David Gomez-Ortiz, Tomás Martín-Crespo, Cristina De Ignacio, José Arnoso, and Fuensanta G. Montesinos

The Canary Islands are an archipelago of eight islands and several islets in the Atlantic Ocean that have been built up by intraplate magmatism. The more recent subaerial eruption took place in La Palma Island during the last four months of 2021 (September 19th to December 13th). This volcanic activity formed the Tajogaite volcanic vent and several minor vents following an eruptive fissure roughly trending N310ºE. The eruption was preceded by intense shallow (<12 km depth) volcanotectonic activity that continued during the whole eruptive process, reaching more than 11,000 earthquakes located. After the first shallow pre-eruptive seismic swarm, the seismicity was mainly located at two different depth levels with hypocenters located at 10-15 and 30-40 km depth.

Seismicity record in the island for previous historical eruptions is very scarce and we have used this seismic episode to explore the lithospheric strength in this intraplate geodynamic setting corresponding to an old (~156 Ma) oceanic lithosphere. Geotherms and brittle and ductile rheological laws with different thermo-mechanical properties have been used to calculate strength envelopes. We have combined the study of the lithospheric strength and the vertical distribution of the seismicity from that period to estimate the extension of the brittle mechanical layer that conditioned the hypocentral locations.

How to cite: Martín-Velázquez, S., Gomez-Ortiz, D., Martín-Crespo, T., De Ignacio, C., Arnoso, J., and Montesinos, F. G.: Lithospheric rheology and strength in La Palma Island (Canary archipelago), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14316, https://doi.org/10.5194/egusphere-egu23-14316, 2023.

EGU23-14361 | ECS | Posters on site | TS1.3

Evidence of Synorogenic Extension in the Upper-Middle Crust in Central Taiwan  

Olivia Lozano Blanco, Björn Lund, Puy Ayarza, Joaquina Álvarez-Marrón, Dennis Brown, and Yih-Min Wu

The active Taiwan mountain belt is located in a complex geodynamic setting that involves two subduction processes. To the northeast, the Philippine Sea Plate subducts northward beneath the Eurasian Plate at the Ryukyu Trench, while in the southwestern part, the Eurasian Plate subducts eastward under the Philippine Sea Plate, where it obliquely collides with the Luzon Volcanic Arc. The Taiwan thrust-and-fold belt is created as a result of this ongoing arc-continent collision. Regardless of the predominance of compression in the overall structure of the island, several studies have also reported normal faulting. This study aims to estimate the local and regional stress field using earthquake focal mechanism data to contribute to a better understanding of crustal deformation in the complex tectonic setting of Taiwan.

Manually clustered earthquake focal mechanisms are inverted to obtain an estimate of the principal stress (σ1, σ2, σ3) orientations and the stress ratio (σ12)/(σ13), from which the direction of the maximum horizontal stress (SH) is calculated. The initial data set contains 11,587 earthquake focal mechanisms compiled from several sources dating between 1990 and 2020. All deep earthquakes in the Ryukyu subduction zone were removed from the data set. The Chi-Chi 1999 and other major earthquakes and aftershocks were also removed as they may reflect a distorted stress field. After preprocessing, a database consisting of 8,510 events with focal depths between 1-144 km and magnitudes ML=0.7-5.9 was used in the inversion. Depth division was performed in a regular 7 km grid up to 28 km depth, all events deeper than 28 km being considered in the same layer.

Preliminary results show that, to the southwest, the notable clockwise rotation of SH from SW-NE to a W-E direction and a change in the fault type from strike-slip to reverse to the east coincides with the interaction between the ENE-striking reactivated inherited structures of the Eurasian continental margin and the NNE-striking thrust faults of the foreland thrust-and-fold belt. To the centre-east, results show normal faulting in the upper crust, which changes to reverse faulting with depth, suggesting that there is a stress transition at approximately 14 km. Beneath that depth, there is a general state of compression. Ongoing research aims at integrating these results with those of numerical modelling and with field data in an effort to understand the locus of deformation and the occurrence of extensional tectonics in compressional settings, here and in other mountains belts worldwide.

This research is part of project PGC2018-094227-B-I00 funded by the Spanish Research Agency of the Ministry of Science and Innovation of Spain. Olivia Lozano acknowledges funding from the same agency through contract PRE2019-091431. Funding from SERA European Union H2020 INFRAIA-2016-2017 Agreement, 170522 is also acknowledged.

 

How to cite: Lozano Blanco, O., Lund, B., Ayarza, P., Álvarez-Marrón, J., Brown, D., and Wu, Y.-M.: Evidence of Synorogenic Extension in the Upper-Middle Crust in Central Taiwan , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14361, https://doi.org/10.5194/egusphere-egu23-14361, 2023.

EGU23-15990 | ECS | Orals | TS1.3

Flooding Induced Seismicity in the Ruhr Area – a geomechanics numerical modelling approach 

Thomas Niederhuber, Martina Rische, Thomas Röckel, Birgit Müller, and Frank Schilling

The Ruhr region is characterized by centuries of coal mining at depths reaching more than 1000 meters. After the closure of the last mines, their controlled flooding started. The Floodrisk project investigates ground uplift, stress changes due to pore pressure changes and the reactivation potential of faults to explain induced seismicity. We focused on monitoring the eastern Ruhr area and are investigating in detail the relationship between mine water rise, tectonic stress and induced seismicity in the Haus Aden drainage area.

In the region of the former "Bergwerk Ost", which had the highest seismicity in the Ruhr area during active mining, the RUB has installed a network of up to 30 short-period seismic stations. Continuous monitoring of seismicity and mine water levels is available for this region from the active mining phase through the post-mining phase to flooding. The temporal evolution of the mine water level after the pumps were shut down in mid-2019 shows a strong correlation with the temporal evolution of the observed microseismicity. Over 2200 induced events have been located since the beginning of flooding, showing spatial clustering. A comparison of the mine galleries, which today serve as the main underground waterways, with the localizations of the events shows that most of the events occur about 300 m below the main pillars located between the longwall panels.

This study provides a compilation of the regional stress state in the eastern Ruhr area based on the mine measurements, which were re-evaluated to derive the regional stress component and compared with stress orientations from independent sources (information on stresses in deep boreholes and earthquake focal mechanisms). The spatial distribution of stress orientations in the Ruhr region shows a rather homogeneous stress pattern with only very few locations where stress orientations differ significantly from the average.

Based on the geometry of the pillars, shafts and longwall panels, a generic numerical FE-model was developed using the compiled stress data for model calibration. The results indicate increased vertical stresses within and below the pillars as a result of stress arching. The horizontal stress changes are minor, thus differential stress increases in the vicinity of the event localizations.

How to cite: Niederhuber, T., Rische, M., Röckel, T., Müller, B., and Schilling, F.: Flooding Induced Seismicity in the Ruhr Area – a geomechanics numerical modelling approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15990, https://doi.org/10.5194/egusphere-egu23-15990, 2023.

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