ERE – Energy, Resources and the Environment

ERE1 – Integrated studies

EGU22-689 | Presentations | ERE1.2

Reducing aviation emissions: investigating time minimal and fixed time trajectories for transatlantic flights. 

Cathie Wells, Paul Williams, Nancy Nichols, Dante Kalise, and Ian Poll

With full satellite coverage of transatlantic flight routes now a reality, situational awareness is no longer a limiting factor in planning trajectories. This extra freedom allows us to consider moving from the current Organised Track System to Trajectory Based Operations, in order to limit fuel use and thus reduce emissions.

In all parts of this research, flights between New York and London, from 1st December, 2019 to 29thFebruary, 2020 are considered. Average daily winds and temperatures are taken from a global atmospheric re-analysis dataset.

 

We first use optimal control theory to find the minimum time trajectories through daily wind fields. The aircraft is assumed to fly at Flight Level 340 with airspeeds ranging from 200 to 270 m s-1. Since fuel burn and greenhouse gas emissions are directly proportional to the product of time of flight and airspeed, this quantity, air distance, is used as a measure of route fuel efficiency. Minimum time air distances are compared with actual Air Traffic Management tracks, giving potential savings ranging from 0.7 to 16.4%. 

 

However, minimum time routes are not always practical. Airlines and airports require trajectories that will minimize fuel burn and thus carbon dioxide emissions, whilst adhering to a rigid timetable. To address this we again apply optimal control theory, but this time to find minimum fuel routes through the same wind fields. 

The control variable is expressed as a set of position-dependent aircraft headings, with the optimal control problem solved through a reduced gradient approach.  A second formulation is considered, wherein both heading angle and airspeed are controlled.  By comparing fuel burn for each of these scenarios, the importance of airspeed in the control formulation is established. 

 

Thus large reductions in fuel consumption and emissions are possible immediately, by planning time or fuel minimal trajectories, without waiting decades for incremental improvements in fuel-efficiency through technological advances.

How to cite: Wells, C., Williams, P., Nichols, N., Kalise, D., and Poll, I.: Reducing aviation emissions: investigating time minimal and fixed time trajectories for transatlantic flights., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-689, https://doi.org/10.5194/egusphere-egu22-689, 2022.

EGU22-755 | Presentations | ERE1.2

Potential for future reductions of global GHG and air pollutants from circular waste management systems 

Adriana Gomez Sanabria, Gregor Kiesewetter, Zbigniew Klimont, Wolfgang Schoepp, and Helmut Haberl

The rapidly rising generation of municipal solid waste jeopardizes the environment and contributes to climate heating. Based on the Shared Socioeconomic Pathways, we here develop a global systematic approach for evaluating the potentials to reduce emissions of
greenhouse gases and air pollutants from the implementation of circular municipal waste management systems. We contrast two sets of global scenarios until 2050, namely baseline and mitigation scenarios, and show that mitigation strategies in the sustainability-oriented
scenario yields earlier, and major, co-benefits compared to scenarios in which inequalities are reduced but that are focused solely on technical solutions. The sustainability-oriented scenario leaves 386 Tg CO2eq/yr of GHG (CH4 and CO2) to be released while air pollutants from
open burning can be eliminated, indicating that this source of ambient air pollution can be entirely eradicated before 2050.

How to cite: Gomez Sanabria, A., Kiesewetter, G., Klimont, Z., Schoepp, W., and Haberl, H.: Potential for future reductions of global GHG and air pollutants from circular waste management systems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-755, https://doi.org/10.5194/egusphere-egu22-755, 2022.

EGU22-2917 | Presentations | ERE1.2

The opportunities and challenges of Green Hydrogen from Africa and Iceland to decarbonize the industries 

Daniel Ayuk Mbi Egbe, David Finger, and Reinhold Lang

Green hydrogen has been identified as a key energy carrier to decarbonize the main emission sectors. In the industry sectors hydrogen can be used as a reducing agent in the metallurgy, in the transportation sector hydrogen can be used as a fuel and in the energy sector hydrogen can be used as an energy storage option. However, the production of hydrogen is energy intensive and can only lead to a reduction of greenhouse gas emissions if the primary energy source is renewable, carbon-free, and has a low ecological footprint. Wind, geothermal, solar and hydropower have been identified as key sources for sustainable and green hydrogen production, especially if excess energy is used for the hydrogen production. Unfortunately, large scale renewable energy production is frequently located at distant location from main consumers. We assess the challenges and opportunities of two remote production hot spots for sustainable and green hydrogen, namely Iceland and northern Africa. We will present different methods, ranging from energy modelling, life cycle assessment, to stakeholder analysis to present a holistic picture of sustainable green hydrogen production. Based on our preliminary results, we conclude that Iceland as well as northern Africa have the potential to produce sustainable and green hydrogen.

How to cite: Egbe, D. A. M., Finger, D., and Lang, R.: The opportunities and challenges of Green Hydrogen from Africa and Iceland to decarbonize the industries, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2917, https://doi.org/10.5194/egusphere-egu22-2917, 2022.

EGU22-3119 | Presentations | ERE1.2

Distinguishing Capital Investment and Consumption of Material Footprint: A Comparative Analysis between Subnational China and Other Nations 

Meng Jiang, Paul Behrens, Yongheng Yang, Zhipeng Tang, Dingjiang Chen, Yadong Yu, Lin Liu, Pu Gong, Shengjun Zhu, Wenji Zhou, Edgar Hertwich, Bing Zhu, and Arnold Tukker

Economic prosperity is vital to human development, but heavy reliance on material extraction leads to environmental degradation. To successfully decouple growth from degradation, the main drivers of material footprint (MF) must be identified. Here, we focus on MFs in Chinese provinces as well as emerging economies in a global context. We employ a local-global input-output model that considers trade and classified investment/consumption to evaluate the relationship between MF and the Human Development Index (HDI). The results show that China's growing MFs exhibit different development trajectories. While GDP and Human Development Index (HDI) are generally correlated with MFs, some low-income provinces in China have higher MFs per capita than some affluent provinces and advanced economies. We find that capital investments related to buildings, infrastructure, and equipment in China explain the complexity. To explain this further, we distinguish between consumption-driven and investment-driven MFs. We demonstrate the different roles of consumption and investment in the physical economy. An interesting finding is that consumption-driven MFs are generally associated with HDI across Chinese provinces and countries, but investment-driven MFs are not. Such trends are also observed in some developing economies. Capital investment shapes the different trajectories of MFs in rapidly industrializing economies. Given the large infrastructure gaps in emerging economies and post-pandemic investment plans, these underline the need to consider the broader sustainability implications of future investment plans. The concept that investigating different roles of investment- and consumption-associated footprint in input-output framework suggests that modeling future MFs, especially in rapidly industrializing countries, requires a more sophisticated framework. Taking capital investment and stocks formation into the general modeling is important. We conclude by asking two open questions: (1) Does the development of consumption-driven and investment-driven MFs across countries follow a paradigm where the early process of development is high-infrastructure MFs, and then shifts to higher consumption MFs as capital stocks build up? (2) How much investment does an economy need to maintain healthy and green growth?

How to cite: Jiang, M., Behrens, P., Yang, Y., Tang, Z., Chen, D., Yu, Y., Liu, L., Gong, P., Zhu, S., Zhou, W., Hertwich, E., Zhu, B., and Tukker, A.: Distinguishing Capital Investment and Consumption of Material Footprint: A Comparative Analysis between Subnational China and Other Nations, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3119, https://doi.org/10.5194/egusphere-egu22-3119, 2022.

We recently launched a citizen science project on household water-energy efficiency as part of the cross-border, interdisciplinary Dŵr Uisce research project on improving the energy performance and long-term sustainability of the water sectors in Ireland and Wales. Citizen science is emerging as a critically important means of democratising science by engaging the public to contribute to the creation of solutions to some of the most important topical global challenges like climate change.

The main aim of the citizen science project is to engage with and collaborate with the public to improve understanding of water-related energy use in Irish homes to help assess the most effective means of improving the efficiency and sustainability of household water-related energy use through water use efficiency.

The project consists of two key parts: a cross-sectional survey that assessed the current public perception of household water and water-related energy use, followed by a longitudinal study where participants record water use at home to assess the actual current household micro-component water use and associated water-related energy use. The findings of the project will be used to quantify the potential of climate action through household water-energy use efficiency in reducing emissions and costs, and to develop up-to-date best practice guidelines for climate action from household water use efficiency.

We will be presenting the results of the cross-sectional survey on current perception of household water and water-related energy use. The survey, open to all households in the Republic of Ireland, ran for 7 weeks in September and October 2021 and a prize draw was used to incentivise participation. We received a total of 265 responses of which 23 responses were partially completed responses (8.7%); however, data available for non-completed responses does not indicate any difference compared to completed responses, and it may well be possible some non-completed responders went on to restart the survey after it timed out. The survey consisted of 60 questions grouped by general questions on household water use (e.g., water provision, and water and energy metering) and household water use types (bathroom, kitchen, cleaning and laundry, and outdoor water use). Itwas designed to be disaggregated by the Irish Central Statistics Office (CSO) household demographic and socio-economic census as a segmentation framework: location, household type, household age, housing status, employment status, household income and household size (disaggregated by age). The responses are found to be generally representative compared with the most recent 2016 census data in terms of location, employment status, housing status, household income, household type, and household age.

How to cite: Bello-Dambatta, A., Bellini, R., and Williams, P.: Energy efficiency through household water use efficiency: a survey on public perception of household water and water-related energy use in Ireland, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3310, https://doi.org/10.5194/egusphere-egu22-3310, 2022.

EGU22-3545 | Presentations | ERE1.2

Impact of climate change on Spanish electricity demand 

Ricardo García-Herrera, Jose M Garrido-Pérez, David Barriopedro, and Carlos Ordóñez

 

The need to balance supply and demand has become an important policy concern in a context of a projected growth in global energy consumption. Based on the demand–temperature relationship and the ongoing global warming, climate change is expected to alter the regional patterns of electricity demand. This work evaluates the influence that climate change could exert on electricity demand patterns in Spain conditioned on the level of warming, with special attention to the seasonal occurrence of extreme demand days. For this purpose, assuming the currently observed electricity demand–temperature relationship holds in the future, we have generated daily time series of pseudo-electricity demand from the recent past until the late twenty-first century by using simulated temperatures from statistical downscaling of global climate model experiments.

We have found that, despite the minor warming effects on the median values of daily electricity demand, the mean values as well as the frequency and severity of extreme electricity demand days are expected to increase significantly in Spain, even for low levels of regional warming. Moreover, the occurrence of these extremes will experience a seasonal shift from winter to summer due to the projected temperature increases in both seasons. Under a high radiative forcing scenario of greenhouse gas emissions (RCP8.5), the extended summer season (June–September) will concentrate more than 50% of extreme electricity demand days by mid-century, increasing to 90% before the end of the century. Since these events will often be related to extreme heat, there could also be side effects that jeopardize the electricity infrastructure. Thus, this result should be considered by energy planners to ensure power supply and improve the effectiveness of the energy system.

Finally, we have shown that future changes in electricity demand could have considerable spatial heterogeneity over the country, which has strong implications for the management of the electricity system. While Spain is warming up faster than the global mean, there are some regions that will be exposed to lower warming than others. In particular, northwestern Spain will experience the seasonal shift later than the rest of the country due to the relatively mild summer temperatures and lower projected warming there. 

How to cite: García-Herrera, R., Garrido-Pérez, J. M., Barriopedro, D., and Ordóñez, C.: Impact of climate change on Spanish electricity demand, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3545, https://doi.org/10.5194/egusphere-egu22-3545, 2022.

EGU22-6603 | Presentations | ERE1.2 | Highlight

Mitigation and Adaptation Emissions Embedded in the Broader Climate Transition 

Corey Lesk, Denes Csala, Robin Krekeler, Sgouris Sgouridis, Antoine Levesque, Katharine Mach, Daniel Horen Greenford, H. Damon Matthews, and Radley Horton

Climate change necessitates an immediate and sustained global effort to reduce greenhouse gas emissions while adapting to the increased climate risks caused by historical emissions. This broader climate transition will involve mass global interventions including renewable energy deployment, coastal protection and retreat, and enhanced space cooling, which will result in CO2 emissions from energy and materials use. Yet, the magnitude of these emissions remains largely unconstrained, leaving open the potential for under-accounting of emissions and conflicts or synergies between mitigation and adaptation goals. Here, we use a suite of models to estimate the CO2 emissions embedded in the broader climate transition. For a pathway limiting warming to 2°C, we estimate that selected adaptations will emit ~1.5GtCO2 through 2100. Emissions from energy used to deploy renewable capacity are much larger at ~95GtCO2, equivalent to over two years of current global emissions and ~8% of the remaining carbon budget for 2°C. These embedded transition emissions are reduced by 80% to 20GtCO2 under a rapid decarbonization scenario limiting warming to 1.5°C. However, they roughly double to 185GtCO2 under a low-ambition transition consistent with current policies (2.7°C warming by 2100), mainly because a slower transition relies more on fossil fuels. Under this status-quo, the emissions embedded in the transition total nearly half the remaining carbon budget for 1.5°C. Our results provide the first holistic assessment of the carbon emissions embedded in the transition itself, and suggest that these emissions can be largely minimized through rapid energy decarbonization, an underappreciated benefit of enhanced climate ambition.  

How to cite: Lesk, C., Csala, D., Krekeler, R., Sgouridis, S., Levesque, A., Mach, K., Horen Greenford, D., Matthews, H. D., and Horton, R.: Mitigation and Adaptation Emissions Embedded in the Broader Climate Transition, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6603, https://doi.org/10.5194/egusphere-egu22-6603, 2022.

EGU22-6658 | Presentations | ERE1.2

Methane and Environmental Impacts of Abandoned Oil And Gas Wells in the North American Arctic-Boreal Region 

Louise Anne Klotz, Oliver Sonnentag, and Mary Kang

Arctic and Boreal regions are experiencing major natural and anthropogenic disturbances, leading to significant changes in ecosystem composition, structure and functioning in recent decades. Therefore, it is crucial to understand the main drivers of change, as well as the ecosystem impacts on natural and cultural resources, human health and the climate system. Large numbers of oil and natural gas wells are being drilled in Arctic and Boreal regions; however, the number and distribution of wells drilled in these regions over time is not well documented and understood. Moreover methane emissions and relationship with land cover and land cover change have not been analyzed. Using oil and gas well databases from provincial, territorial and state agencies in Canada and the U.S., we analyze drilled oil and gas wells throughout the study period (1984-2014) and in relation to land cover distribution and change across the Arctic-Boreal region of western North America. We find 254,998 wells, mostly located in Alberta (211,747) and British Columbia (35,012), in Arctic and Boreal regions of Canada and the U.S. We characterize the wells, based on data provided in the database, according to well production type (gas or oil and gas) and well abandonment status (active, abandoned, abandoned and plugged) and find that annual well drilling has increased from 269 to 8599 from 1984 to 2014. We estimate emissions from abandoned oil and gas wells in the study domain to be 40 – 148% of Environment and Climate Change Canada’s national estimate for methane emissions from abandoned oil and gas wells in 2018. Finally, using the annual land cover maps for 1984-2014, we find the number of drilled wells in each land cover class throughout the years. We identify significant increases in number of wells drilled between 1984-1999 and 2000-2014 in evergreen forest, sparsely vegetated and barren land cover classes. 

How to cite: Klotz, L. A., Sonnentag, O., and Kang, M.: Methane and Environmental Impacts of Abandoned Oil And Gas Wells in the North American Arctic-Boreal Region, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6658, https://doi.org/10.5194/egusphere-egu22-6658, 2022.

EGU22-6801 | Presentations | ERE1.2

Representative models and energy and material efficiency strategies for residential buildings in urban India 

Aishwarya Iyer, Mohamed Aly Etman, Edgar Hertwich, and Narasimha Rao

40% of global energy demand can be attributed to buildings, and 75% of this share is contributed by residential buildings. Developing countries are expected to be the hotspot for future growth in residential energy demand, as many of them expect significant growth in population and urbanization. For instance, 75% of the residential floorspace expected to exist in India in 2030 remained to be constructed in 2015. Thus, a lot of the new energy demand from residential buildings can still be controlled and mitigated. As the country expected to have the largest population in the world by 2025, India has a responsibility to grow sustainably, in a way that aids global climate change mitigation goals. Studying the residential building sector in India thus is a necessary step towards achieving these goals.

Indian residential buildings are diverse, and include informal slums,  low-quality formal buildings, mid-rise formal buildings, and high-rise skyscrapers. Global models for energy efficiency in the residential sector usually consider only one type of building from developing countries, the formal (cement-concrete) type. They create a generalized model, based on the assumption that appliances and thermal comfort standards are the same in most countries. These generalizations do not consider the diverse types of buildings, appliances and thermal comfort standards in India, or any developing country.

This project presents a life-cycle assessment representing all residential building types in India - formal, semi-formal and informal. The semi-formal typology is hitherto missing from building energy modeling literature.  We include and model embodied phase and use-phases separately. The embodied phase study helps understand the energy demand and material demand from the building materials and construction. In the use-phase study, we create detailed models of all residential building typologies, and simulate cooling energy demand results for the city of Mumbai. We study building clusters, to account for the heat transfer and shading effects from the crowded urban environment in India. We also model realistic cooling appliances commonly used in Indian households, like fans and water-based coolers, in addition to air conditioners, and more representative cooling behaviour.

For the first time in this Indian residential life-cycle assessment study, we define three representative typologies for Indian residential buildings. We study clusters and model real appliances used in these homes. We explore some simple material efficiency and energy efficiency strategies through different envelopes, appliances and usage. The goal of this study is to create a preliminary model of what buildings in India are like, and understand how their life-cycle energy demands differ, and some simple options to reduce this demand.

How to cite: Iyer, A., Aly Etman, M., Hertwich, E., and Rao, N.: Representative models and energy and material efficiency strategies for residential buildings in urban India, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6801, https://doi.org/10.5194/egusphere-egu22-6801, 2022.

Paris climate agreement has been a major step forward to limit the global mean temperature rise to below 1.5°C above pre-industrial levels. For many countries, it has led to adopt Net-Zero GHG Emissions (NZE) targets by mid-century. Such objectives imply renewing much existing infrastructures and equipment through low-carbon investments in key sectors (buildings, transport, and power supply). However, there is a risk to overshoot the objectives due to base carbon-intensive materials (steel, cement, etc.). Indeed, material demand is already expected to double by mid-century following economic trends. Deploying intensively low-carbon infrastructure and technologies is expected to increase material demand even more. The size of this surplus is unclear as most energy prospects neglect the feedback between the low-carbon transition and material needs. In addition, most countries restrict their NZE targets to territorial emissions, whereas a carbon footprint approach is essential to account for carbon linkage and industrial relocation toward more carbon-intensive countries. Also, the potential for a fast transition to zero-carbon industrial processes and materials as required is still uncertain, all the more in developing countries producing most materials. The design of stringent climate policy needs a clearer vision of the role of materials in the low-carbon transition to prioritizing mitigation actions.

Our study aims to quantify the link between GHG emissions, low-carbon investments, and the demand for materials. We develop an Input-Output model called MatMat designed (i) to integrate various sets of expertise about low-carbon scenarios and (ii) to track the role of investment demand and material supply in the evolution of the carbon footprint. We apply our method to the french governmental NZE scenario and global mitigation scenarios until 2050. By disentangling key drivers impacting GHG emissions embodied in materials, we show that the carbon footprint of materials could offset national NZE targets due to (i) the indirect material demand embodied in imports and (ii) the potential delay in decarbonizing the material production compared to other sectors, especially abroad. To relieve the material bottleneck for the transition to NZE strategy, we recommend (i) developing material efficiency and circular economy policies, (ii) relocating low-carbon industrial productions, and (iii) supporting imports of clean industrial products at the national level.

How to cite: Teixeira, A. and Lefèvre, J.: The future carbon footprint of materials as a bottleneck for the transition to Net-Zero Emissions – case study on France, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11525, https://doi.org/10.5194/egusphere-egu22-11525, 2022.

EGU22-12238 | Presentations | ERE1.2 | Highlight

Reducing the energy demand to achieve universal access to modern energy while ensuring women’s well-being: How much energy and carbon can be saved by fertility decline? 

Camille Belmin, Peter-Paul Pichler, Guillaume Marois, Shonali Pachauri, and Helga Weisz

In a climate-constrained world, understanding the energy needs to reach universal access to modern energy is critical. This requires making assumptions on future population trajectories, and developments in energy access can affect them. Yet, this feedback has never been accounted for in energy models. Access to modern energy enhances women’s ability to make reproductive choices and leads to fertility decline as it reduces child mortality, improves health, increases women’s access to information, education and employment. In this paper, we assess the household energy requirements to expand energy access while considering the relationship between energy access and fertility, using Zambia as a case study. To do so, we built a micro-simulation model of population projection in which fertility depends on access to modern energy and education level, and projected the electricity and cooking energy needs of the Zambian population to 2050, under different scenarios. Our preliminary results show that while electricity consumption is higher in the universal access scenario compared to the baseline scenario, total energy demand is 67% lower, partly due to strong decline in the use inefficient traditional cooking fuels. Reduced population growth due to expanded energy access and education accounts for 15% of this reduction in rural areas, and 8% overall. Although the challenge of achieving universal access to modern energy seems daunting, our results suggest that this goal could be co-beneficial to achieving climate goals. Our study also reveals that accounting for the energy-population nexus in energy models would scale down the currently assumed energy needs to ensure decent well-being for all.

How to cite: Belmin, C., Pichler, P.-P., Marois, G., Pachauri, S., and Weisz, H.: Reducing the energy demand to achieve universal access to modern energy while ensuring women’s well-being: How much energy and carbon can be saved by fertility decline?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12238, https://doi.org/10.5194/egusphere-egu22-12238, 2022.

EGU22-12341 | Presentations | ERE1.2

Polish demand and supply of mineral raw materials  in the light of the European Green Deal 

Alicja Kot-Niewiadomska and Krzysztof Galos

The European Green Deal (EGD) is a development strategy aimed at transforming the European Union into a the world's first climate-neutral area. The way to achieve this goal is a low-emission energy transformation, which should end in 2050, but the first milestones should be achieved already in 2030. Following the dynamically accelerating EU climate and energy trends will be a significant transformation challenge for Poland. The strategies proposed in the EGD will have a significant impact on key areas of the national economy (energy system, construction, industry, transport, households), including the level of supply and demand for many mineral raw materials. The most visible changes will be registered in the group of fossil fuels, but also regarding metallic raw materials, which will be associated with the development of advanced technologies for renewable energy sources.

A crucial breakthrough in the Polish energy transformation was the country's accession to the declaration of resignation from the coal exploitation, which Poland signed during the World Climate Summit in 2021. According to the social contract, the last hard coal mine in Poland will be closed by 2049. Thus, for the first time Poland was on the list of countries that officially confirm the withdrawal from coal. The resignation from this raw material is also included in the Polish Energy Policy 2040, according to which hard coal will be replaced by natural gas, nuclear energy and renewable energy. As a consequence, an increase in demand for both natural gas and nuclear fuels, should be expected. It should be noted that Poland does not have its own fossil nuclear fuel sources, and the domestic extraction of natural gas covers only 13% of the demand. In both cases an increasing demand for fuels should be assumed in the coming decades. Crude oil is also in the group of fuels sensitive to changes resulting from EGD. The main sector of the Polish economy in which petroleum products are consumed is transport. The development of electromobility, the use of biocomponents and alternative fuels will be the most important factors influencing changes in the level of demand for crude oil in the next 10-20 years.

The EGD strategy will play an important role in changing the structure of demand for metallic raw materials, both in terms of their quality and quantity. It should be emphasized that Poland has the largest copper ores deposits in Europe. In recent decades, the Polish production has accounted for nearly 50% of the total copper ore concentrates production and for more than 20% of the total refined copper production in the EU. Development of demand for this raw material is related to the scale of use of refined copper, among others in renewable energy (wind power and photovoltaics) and electromobility, which are the pillars of EGD. Unfortunately, practically all other metals important in development of renewable energy sources in Poland (e.g. cobalt, nickel, manganese, lithium, REEs, silicon) are completely deficit for the Polish economy due to lack economically feasible domestic sources. 

How to cite: Kot-Niewiadomska, A. and Galos, K.: Polish demand and supply of mineral raw materials  in the light of the European Green Deal, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12341, https://doi.org/10.5194/egusphere-egu22-12341, 2022.

EGU22-107 | Presentations | ERE1.4

Climate change: a threat to underwater cultural heritage 

Elena Pérez Álvaro

Predictions forecast changes in climate that may affect cultural heritage in the future. Not only the underwater cultural heritage will become exposed, but also our land tangible cultural heritage will be submerged: entire nations and their cultural heritage may disappear, losing their identity as nations, countries, and communities. In fact, climate change has the potential to increase the sea level enough by 2100 to inundate 136 sites considered by UNESCO as cultural and historical treasures.

This presentation will examine the specific climate changes that oceans will most likely suffer and how they will probably affect tangible underwater cultural heritage, analysing how the changes will affect every possible material that can be found in a submerged archaeological site. It will also explore cases of heritage that are already suffering the consequences examining two future scenarios: how climate change may disturb underwater cultural heritage, and how land cultural heritage may change its label and subsequently become underwater cultural heritage. Lastly, the presentation will propose a new partnership natural/cultural resources and the qualification of cultural heritage as a natural resource for its preservation, establishing the same common measures for both heritage against climate change.

How to cite: Pérez Álvaro, E.: Climate change: a threat to underwater cultural heritage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-107, https://doi.org/10.5194/egusphere-egu22-107, 2022.

EGU22-1776 | Presentations | ERE1.4

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

Oscar Julián Esteban Cantillo, Beatriz Menendez, and Benjamin Quesada

The analysis and interpretation of past climate data and simulations of climate models for future periods will allow us to know future climate conditions and their differences with past ones. One of the many applications of these analyzes is the study of the impacts of climate change on two types of cultural heritage that differ due to their geographical location and therefore their climatic conditions, as are vernacular cultural heritage in Europe and archaeological sites in Latin America, but they share a fundamental similarity in terms of the use of materials and construction techniques.

The first objective of our study is to review and quantify the impacts of combined climate (mean and extreme) and pollution on building materials of cultural heritage under future IPCC socioeconomic scenarios with high and low mitigation measures at years 2030, 2050 and 2070, using peer-reviewed dose-response equations.

We also focus on the degradation effects due to compound extreme events (heatwave, dry spells and extreme rainfall/flood) of each of the selected regions of our case study (European project SCORE: Sustainable COnservation and REstoration of built cultural heritage 2021-2024), in order to determine how future climatic conditions may affect the cultural heritage of some sites in Europe and Latin America. The foregoing by applying these climatic conditions in different models, based on scientific literature, that allow determining the consequences of these conditions on the materials in which these structures were built.

Finally, based on the literature review, we deliver preliminary results on a “cocktail of extreme events” experiment in laboratory specifically designed to quantify the damages and degradation of building materials due to a realistic series of adverse climate and pollution events.

How to cite: Esteban Cantillo, O. J., Menendez, B., and Quesada, B.: Climate change impact on vernacular and archaeological cultural heritage building materials in Europe and Latin America, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1776, https://doi.org/10.5194/egusphere-egu22-1776, 2022.

EGU22-2571 | Presentations | ERE1.4

Black crusts as past air pollution archives 

Mathilde Ropiquet, Aurélie Verney-Carron, and Anne Chabas

Since the Industrial revolution, emissions of pollutant (gas, aerosols) due to human activities increased and modified the composition of the atmosphere, causing air pollution and climate change. However, pollution measurements are relatively recent. In order to know past air pollution and assess its impact on monuments, proxies need to be found and studied.

One of these potential local proxies is black crusts that are a chemical alteration pattern mainly found on limestone or marble monuments. They are forming a dark mineralogical layer composed of gypsum (CaSO4.2H2O) that results from the sulfation reaction between the calcite (CaCO3) of the stone and the sulphur dioxide (SO2) from the atmosphere. As gypsum is easily soluble, this pattern particularly affects sheltered area from the rain where particulate matter is trapped and accumulates. Therefore, black crusts act as passive sampler and could be used as an archive of air pollution.

To validate black crusts nomination as a new proxy and to find the best pollution marker, samples were collected at Père Lachaise cemetery on ancient tombs (dated from the 1820’s). A specific protocol was applied to separate strata from each other. Then, multiple analyses were realised using SEM-EDS, ICP-AES, and ICP-MS. The results show a different particulate content as a function of the depth, with different contributions of fly-ash typical of coal and oil combustion. This is confirmed by the chemical analyses as the trace metal concentrations are in agreement with the pollution sources. This study demonstrates that laminar black crusts have an internal stratigraphy that can be crucial to reconstruct past air pollution and provides precious data on pollution sources.

How to cite: Ropiquet, M., Verney-Carron, A., and Chabas, A.: Black crusts as past air pollution archives, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2571, https://doi.org/10.5194/egusphere-egu22-2571, 2022.

EGU22-2850 | Presentations | ERE1.4

Making use of climate information for protecting cultural heritage from extreme weather events in a warming world 

Lola Kotova, Johanna Leissner, Matthias Winkler, Florian Antretter, Ralf Kilian, Jürgen Mossgraber, Jürgen Reuter, Tobias Hellmund, Anton Dolgov, Katharina Matheja Matheja, Michael Rohde Rhode, Uta Pollmer, and Uwe Mikolajewicz

The intensity and frequency of extreme weather events in Europe are one of the most dangerous consequences of a warming climate. Some regions suffer more under heat waves and droughts, while others are experiencing extreme rainfalls. Thus, for example, a severe flood in July 2021 in several European countries caused widespread damages particularly in Belgium and Germany.

Which extreme weather events are to be expected in the future? How can the damage of irretrievable historical sites be avoided or, at least, limited or dealt with? All these questions are addressed in the three-year research project KERES, which is funded by the German Federal Ministry of Education and Research (BMBF) and is coordinated by the Fraunhofer ISC together with the Fraunhofer EU Office in Brussels.

As first step the regional relevance of future extreme weather events in Germany will be investigated.  This information will be further used to estimate the potential damages to buildings and outdoor facilities. The precautionary and responsive measures to manage potential or acute damage situations will be investigated as well. The designed methodologies will be tested for five case studies including World Heritage Sites (historical buildings and historical gardens)  in Germany.

The major tools of KERES include building component and indoor climate simulations and high-resolution urban climate models. The necessary input will be taken from the most recent ensemble of regional climate change projections of the EURO-CORDEX Initiative (www.euro-cordex.net).  As a result, an ontology-based information system will be designed for managing the expected damage situations.

We will present first results from the KERES project. The discussion will be focused on how to access and visualize the robustness of projected changes of extreme weather events in a way oriented to individual cultural heritage sites.

How to cite: Kotova, L., Leissner, J., Winkler, M., Antretter, F., Kilian, R., Mossgraber, J., Reuter, J., Hellmund, T., Dolgov, A., Matheja, K. M., Rhode, M. R., Pollmer, U., and Mikolajewicz, U.: Making use of climate information for protecting cultural heritage from extreme weather events in a warming world, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2850, https://doi.org/10.5194/egusphere-egu22-2850, 2022.

EGU22-2857 | Presentations | ERE1.4

The French monumental heritage in the face of global climate change: state of the art and research perspectives 

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

France's monumental heritage has been the subject of little theoretical research in the face of global climate change, although many applied studies have concerned its adaptation and resilience, especially at the local level. Furthermore, this heritage includes more than 44,000 monuments and classified sites, 48 of which being inscribed on the UNESCO List and therefore deserves to be taken into account in the context of the current climate unbalance.

The complexity lies in the diversity of materials making up the monuments (stones, glass, metals, wood...) and of phenomena that affect them (as well as other constructions). In order to assess the impact of these increasing slow or extreme events already at work, the tools and methodologies range from the description and inventory of the effects, their measurement, mapping and projection into the future using models such as dose-response functions (DRF) with input data from climate models and scenarios. Ancient data can also be used to complement the correlation between climate and heritage, such as dendroclimatology studies of the wood in monuments.

Results from research carried out in France will be presented concerning stone facades, ancient stained glass windows, metals, degradation of walls by salts and dendroclimatology. Further research should focus on the consequences on the monumental heritage of rising marine waters, river and urban flood and low waters, freeze-thaw, the stability of monuments on clay soils and the indoor climate of monuments and their carbon footprint.

In conclusion, much remains to be done in France: (1) complete the inventory and description of the phenomena, their impacts and their location at the national, regional, urban and monumental scales, (2) quantify these impacts in the future via empirical or geochemical models based on climate models outputs.

How to cite: Lefèvre, R.-A., Brimblecombe, P., and Verney-Carron, A.: The French monumental heritage in the face of global climate change: state of the art and research perspectives, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2857, https://doi.org/10.5194/egusphere-egu22-2857, 2022.

EGU22-3476 | Presentations | ERE1.4

A Communities Engagement Mobile Application for Assessing the Resilience and Deterioration of Cultural Heritage Monuments 

Maria Krommyda, Nikos Mitro, Katerina Georgiou, Vassillis Nousis, and Angelos Amditis

Climate change has been proved to have negative impacts on historic areas hosting cultural heritage sites and monuments, which in turn yields significant adverse impacts on local economies, societies, and even politics. The first and necessary step of the process of confrontation of this challenge is the early detection and recording of the on-site inflicted damage by a monitoring tool. In order to achieve that, we developed a dedicated mobile application that aims to assist the assessment of the resilience and the deterioration of the historic areas and the potential impacts due to various hazards. Citizens and local authorities worldwide can directly use the developed application on their mobile phones to acquire photos of on-site damages and submit short reports based on them. This software component has been designed and developed in the context of the European project entitled “HYPERION”, which aims to deliver an integrated resilience assessment platform, addressing multi-hazard risk understanding, faster and efficient response, and sustainable reconstruction of historic areas.

With this application, we aim to create a user-friendly application with the latest user interface and usability issues/trends which is focused on museum enthusiasts and active citizens’ or travelers’ needs. It’s important to put the users of this targeted group at the center of our efforts and by understanding their needs to create an intuitive application for them and at the same time a useful tool for the local authorities.

Users download the application from the Google or Apple App store and they log in or create an account in the application through the PLUGGY platform, which was developed in the context of the “PLUGGY” European project. The main function of the application is to create and post an asset using PLUGGY’s REST API. An Asset is an elementary unit of content in PLUGGY, a media file with an identified owner, a title, a description, a set of tags, and a license, which specifies how this file can be reused. Initially, the user’s location is detected via GPS and corrected in case of miscalculation. The user is then prompted to select a photo (or directly to take a snapshot) that depicts the damage of a monument. To complete the creation of the asset, the user will also need to select a title that will accompany the photo, and some tags, not only for a better description of the event but also for correlation with other assets or exhibition points that already exist in PLUGGY.

The developed mobile application gives voice to citizens and encourages them to provide direct feedback to the relevant cultural authorities, in order to assist them in assessing the deterioration of the cultural heritage sites and determining the needed reconstruction actions. As a result, the communities can have a major role in the safeguard of their cultural heritage.

How to cite: Krommyda, M., Mitro, N., Georgiou, K., Nousis, V., and Amditis, A.: A Communities Engagement Mobile Application for Assessing the Resilience and Deterioration of Cultural Heritage Monuments, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3476, https://doi.org/10.5194/egusphere-egu22-3476, 2022.

EGU22-5264 | Presentations | ERE1.4

A data-driven approach to understanding the equilibria behaviour of salt mixtures in built cultural heritage 

Scott Allan Orr, Sebastiaan Godts, and Tim De Kock

Salt weathering is a complex and active area of research, with implications for tangible cultural heritage worldwide. A preventive conservation approach is often taken to limit salt crystallisation cycles, which requires an understanding of the relative risks of scenarios and their respective heritage characteristics, salts present, and the climate, including climate change. Equilibrium relative humidity is an important property that indicates this risk: typically, it is represented by specific RH% and temperature derived from a single salt. The behaviour of single salts does not accurately represent the behaviour of salt mixtures, which are far more common in cultural heritage contexts. To address this, 11412 salt mixtures present in the built environment have been analysed using the ECOS/Runsalt model to predict their mixture-based mutual relative humidity of crystallisation and deliquescence points, the salt mixture composition, as well as the relative humidity of crystallisation and deliquescence for individual salts in the mixtures. This dataset, although sampled primarily from Belgian cultural heritage sites, is representative of the general classes of salt mixtures found in the built environment globally. This analysis represents an important step in developing a generalised statistical method for parameterising environmental time series data for salt weathering risk within climate change scenarios, as well as progressing fundamental knowledge on the behaviour of salt mixtures in built cultural heritage.

How to cite: Orr, S. A., Godts, S., and De Kock, T.: A data-driven approach to understanding the equilibria behaviour of salt mixtures in built cultural heritage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5264, https://doi.org/10.5194/egusphere-egu22-5264, 2022.

EGU22-5301 | Presentations | ERE1.4

The influence of biofouling on water transport inside porous stones 

Laurenz Schröer, Tim De Kock, Sebastiaan Godts, Nico Boon, and Veerle Cnudde

During the 21st Century, climate change and improving air quality will alter biological communities and their influence on building stones. While air pollution used to be a principal factor of stone deterioration, it is diminishing in many parts of the world. These environmental changes affect the aesthetics of building stones, and fewer black gypsum crusts will form, while more biological-induced discolorations could occur. Within the British Isles, it resulted in the “greening” of monuments after increased algal growth. Besides aesthetical damage, the formation of biofilms could affect water transport and retention. Changes in the water-stone relationship should be studied in detail because moisture is the most significant facilitator of stone alteration, leading to physical, chemical and further biological weathering.

This topic was intensely studied on soils. However, knowledge of the effect of biofilms on water transport and retention of stones is limited. For this reason, three porous natural building stones: Ernzen, Euville and Savonnières, were biofouled at the outer surface with the cyanobacteria Phormidium autumnale. The colonization was estimated by spectrophotometry, and their relationship with the stones was studied by Scanning Electron Microscopy (SEM), Environmental SEM (ESEM) and optical microscopy on thin sections. Based on the European standards, the water transport properties were determined of biofouled and untreated samples.

Microscopy showed that the biofilms covered the surface while they spanned over and closed numerous pores. They had a measurable effect on water transport and retention and reduced the rate of capillary water absorption and drying in combination with higher moisture content after (vapor) sorption. Moreover, the biofilms changed the surface wettability and induced near hydrophobic conditions in a dry state while no effect was measured on the water vapor diffusion and air permeability. These changes can alter the material properties and other processes like salt weathering and freeze-thaw damage. As swelling and shrinkage were observed by ESEM, the properties and physical effects of biofilms are expected to change with fluctuating relative humidity.

How to cite: Schröer, L., De Kock, T., Godts, S., Boon, N., and Cnudde, V.: The influence of biofouling on water transport inside porous stones, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5301, https://doi.org/10.5194/egusphere-egu22-5301, 2022.

Historical buildings, which play a major role in shaping the urban fabric, are facing challenges due to climate change. Today the cultural values are considered among the main goals of sustainable development much like the social, economic and environmental values. Therefore it is important to discover the sustainable ways of conservation and maintenance practices on mitigating the impacts of climate change, so that the historical buildings can play an active role in achieving sustainable development goals without compromising their cultural and heritage values.

Nature-based solutions (NbS) are considered as sustainable and effective solutions on mitigating impacts of climate stressors. Exploring their compatibility to conservation practices can bring mutual opportunities to the urban fabric and to the historical buildings. However, nature has been considered as a threat amongst the conservation practices due to potential biodegradation of materials, obscuring the heritage structure and requiring an additional cost of maintenance. Nevertheless, many uses of nature-based solutions come across in history, e.g. in the form of turf or sod roofs that provide thermal insulation on extreme climate conditions. Today, there are some attempts to integrate NbS to heritage environments within the scope of retrofitting projects. Nevertheless, a comprehensive methodology of performance assessment on mitigating climate challenges without compromising the cultural and heritage values has not been developed yet.

This project aims to develop a decision making framework for heritage actors on evaluating the compatibility of NbS to conservation and maintenance practices of historical buildings that are exposed to adverse impacts of climate stressors in the urban context. For developing a general outline of the framework, various NbS will be evaluated and categorized based on quantitative data in the literature according to their aesthetic fit to historic buildings, their structural feasibility and their performance on mitigating the effects of climate stressors. Throughout the project, process and value based research will be conducted on carefully selected case studies. The selected case studies will be evaluated within the scope of determining the severity of the prevailing climate stressors in their context, their structural sensitivity and their adaptability capacity to the new interventions. Based on the results, the compatible NbS and design measures can be identified. In the later stages of the project, the feasibility of the proposed nature-based design for the case studies will be tested by monitoring and comparing the results before and after the implementation.

How to cite: Kale, E., De Groeve, M., and De Kock, T.: Developing a Decision Making Tool for Evaluating the Compatibility of Nature-Based Solutions to the Built Heritage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5311, https://doi.org/10.5194/egusphere-egu22-5311, 2022.

EGU22-5806 | Presentations | ERE1.4

Influence of rock pore structure on the protective coating against weathering 

Chiaki Oguchi and Yukina Ikeda

Tuff is rich in color and is used as a stone material, and it is also a rock that forms a unique landscape in Japan, a volcanic country. However, since it is generally a fragile rock, it is susceptible to weathering and deterioration. The present study conducted an experiment to confirm the effectiveness of the surface protectant using tuff with different physical characteristics. Sodium sulfate aqueous solution was used to determine the effectiveness of protective agent application for 5 types of tuff (Oya stone, Nikka stone, Ashino stone, Tatsuyama stone, Towada stone) An experiment was conducted in which the lower 3 cm of a 5 cm × 5 cm × 15 cm specimen that had been oven-dried at 110 ° C was immersed in a salt solution, and 20 ° C-40 ° C was repeated for up to 20 cycles in a 48-hour cycle. When the weight and P-wave velocity of each specimen were measured every cycle, the solution reached the surface of the uncoated stone material for comparison, salt crystals were deposited. The surface of the specimen was peeled off, and the P-wave velocity gradually decreased.  On the other hand, in the stone material coated with the protective agent, salt crystallization was not observed even when the solution reached the top surface shortly after the start of the experiment.  The P wave velocity did not decrease, despite cracks occurred as the experiment progressed. As a result, the P-wave velocity began to decrease and the surface layer fell off. In Ashino and Tatsuyama stones, the coated specimens were more severely destroyed than the uncoated specimens. In Oya stone and Towada stone, which contain clay minerals (miso) in the form of patches, crushing proceeded from the miso part. This experiment suggests that the effect of the protective agent may depend on the rock structure and the pore diameter. In other words, for rocks containing miso, the use of a protective agent is likely to increase deterioration regardless of the pore structure. For rocks with a large proportion of micropores and low durability against salt weathering, the use of a protective agent is used. Therefore, the start time of surface exfoliation can be delayed. In addition, in rocks with a large proportion of large gaps (> 10-0.5 μm), even if crystallization occurs on the surface of the specimen. The  peeling does not occur for a while, but the protective agent penetrates deep into the thick protective agent penetration area. It is considered that the crystallization of the salt occurs more internally and the deterioration is more severe than it should be. 

How to cite: Oguchi, C. and Ikeda, Y.: Influence of rock pore structure on the protective coating against weathering, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5806, https://doi.org/10.5194/egusphere-egu22-5806, 2022.

EGU22-5898 | Presentations | ERE1.4

Developing a new method for long-term monitoring of the weathering of historical building materials 

Luigi Germinario, Chiara Coletti, Petros Choidis, Dimitrios Kraniotis, Lara Maritan, Raffaele Sassi, Laura Tositti, and Claudio Mazzoli

This contribution presents the work of research and technical development for designing a novel method for monitoring and predicting the weathering of cultural heritage, in particular of stones and timber used historically as building materials.
An apparatus for long-term field tests was designed in its hardware and software components with a twofold application:

  • Exposure of a set of selected stone and wood specimens to natural weathering, at different orientations (North, South, and horizontal plane) and environmental settings (Italy and Norway).
  • Non-stop acquisition of microclimate data series at different resolutions, down to the scale of the specimen surface, completed by datasets of regional stations of environmental monitoring.

Complementary laboratory analyses aim at setting a reference point for the state of conservation of each material before the exposure tests, and monitoring the changes of surface recession/topography (by 3D optical profilometry), thus reconstructing the relevant deterioration trends.
Within the framework of the EU-funded project HYPERION, this novel experimental approach is expected to help assessing the interaction of building materials with the environment and their weathering constrained by microclimate and climate variability; combining climate model simulations, the stresses brought about by climate change can also be assessed. The findings might represent a source of precious information for the activities and decision-making protocols of the stakeholders involved in the protection of cultural heritage.

How to cite: Germinario, L., Coletti, C., Choidis, P., Kraniotis, D., Maritan, L., Sassi, R., Tositti, L., and Mazzoli, C.: Developing a new method for long-term monitoring of the weathering of historical building materials, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5898, https://doi.org/10.5194/egusphere-egu22-5898, 2022.

EGU22-7085 | Presentations | ERE1.4

The effect of vertical urban greening on historical building materials 

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

Due to hard coverage and building infrastructures, cities experience higher temperatures and higher pollution levels in their city centre relative to their less dense surroundings. This urban heat island effect is receiving an increasing amount of attention and concern. In response, cities are implementing green initiatives to mitigate elevated temperature and pollution levels, improving the health and well-being of their residents. However, the urban heat island is typically the largest in the historical core of the city, where the abundance of built heritage can make the implementation of green initiatives difficult. The dense urban fabric and the rules of conservation make such an implementation inconvenient. A major concern is how green initiatives might affect the condition of the historical building materials.

Therefore we scope the compatibility of vertical greening with built heritage, in terms of microclimatic changes, and considering impacts of salt crystallization, frost events, biodeterioration and pollutant deposition. The vertical greening represents vegetation growing along exterior walls. Either plants, rooted on the ground, climb up the facade by attaching themselves on the vertical surfaces or plants hang down from the top of the facade. Monitoring case studies in Antwerp and laboratory studies will help us investigate key changes, beneficial or adverse, in the material condition of heritage buildings. This project will develop our understanding of the relationship between the green initiatives and the historical materials in an urban area.

How to cite: De Groeve, M., Kale, E., Orr, S. A., and De Kock, T.: The effect of vertical urban greening on historical building materials, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7085, https://doi.org/10.5194/egusphere-egu22-7085, 2022.

EGU22-7880 | Presentations | ERE1.4

Analysis of Climate Change Impacts on the still existing 28 Norwegian Stave Churches 

Chiara Bertolin and Elena Sesana

Norway, nowadays, still preserves outstanding examples of traditional Scandinavian wooden architecture called stavkirker (i.e., stave churches), these are typical Norwegian medieval churches built since 11th-12th Centuries with posts and staves as load bearing elements. This homogeneous group of immovable cultural heritage share similar architectural features, construction materials, as well as tangible and intangible values. They represent the highly developed tradition of wooden buildings that extended at these latitudes during Middle Ages and incorporate a large reuse of decorative and construction elements originating from other stave churches built in earlier centuries. Besides having similar use and maintenance requirements still today, the stave churches have similar vulnerability, as well as risk assessment and preservation needs.

 

For their protection it becomes fundamental to analyse and predict the impact of climate change in term of expected extreme temperature and rainfall events. In fact, modification of temperature (and consequently relative humidity) and/or of precipitation amount may cause rot to the Pine wood material constituting the churches or may enhance the mechanisms of biological and mechanical decay with an ultimate loss of valuable building assets.

 

This contribution focuses on the whole group of the still existing 28 stave churches spread over 6 regions in centre-south Norway with different climate, from temperate continental climate/humid continental climate (Dfb in the Köppen classification) to cool continental subarctic climate (Dfc) passing through the Tundra climate (ET). The work introduces an overview of the churches` architectural categorization, location, and flood vulnerability; then it focuses on climate change impacts. For the analysis of temperature and precipitation extreme events the modelled grid data from the Norwegian Climate Service Center (https://nedlasting.nve.no/klimadata/kss)  over 1x1 km spatial resolution have been used. These forecasts have been produced using the regional climate model simulation COSMO-CLM1 (Consortium for small scale modelling in Climate Mode) considering the Representative Concentration Pathways RCP4.5 (i.e., slow increase of concentrations of greenhouse gases in the atmosphere until 2050 followed by emission reduction over time with, in addition, a human-induced radiative forcing at 4.5 W/m2). More than 100 Gb of data were elaborated to create a novel database with daily temporal resolution over two reference time periods i.e., the recent past (RP, 1991-2020) and the far future (FF, 2071-2100) for the location closest to each stave church. Further the analysis concentrates on extreme precipitation and temperature occurrences (e.g., > 99.99 percentile) investigated as cumulative distribution function (CDF) and complementary cumulative distribution function (CCDF). Results highlight expected anomalies in extreme events for all the 28 locations and report the total extreme precipitation and temperature related hazards as indexes which easily allow to categorize the change in risk for each stave church.

References:1Rockel, B., Will, A., & Hense, A. (2008). The regional climate model CLM. Meteorologische Zeitschrift, 17, 347–348

How to cite: Bertolin, C. and Sesana, E.: Analysis of Climate Change Impacts on the still existing 28 Norwegian Stave Churches, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7880, https://doi.org/10.5194/egusphere-egu22-7880, 2022.

EGU22-8670 | Presentations | ERE1.4

Mn-rich Black Patina Formation on Built Heritage in Humid Areas 

David Martin Freire-Lista, Rebeca Blanco-Rotea, Maria do Rosário Costa, and Jorge Sanjurjo-Sánchez

This study aims to characterise the decay due to black patinas of Santalla de Bóveda Monument (Lugo, Northwest of Galicia, Spain).

Manganese is one of the most abundant elements on Earth, and the granite on which Santalla de Bóveda Monument was built (used as building material of the monument) has considerable amounts of Manganese. This monument shows black patinas on the surface of its building materials (mortars and granites).

Mortars and granite with Mn-rich black patinas were analysed in their chemical, mineralogical and petrographical properties (polarizing and scanning electron microscopes, X-ray diffraction and X-ray fluorescence). In addition, the water from springs near the monument was analysed.

According to the experimental study results, it was observed that rich Mn-oxide crusts are presumably induced by bacteria. That is, the oxidation of Mn fuels the growth of chemolithoautotrophic microorganisms, which need water to live. These patinas of biogenic Mn-oxide minerals presented different shapes, nano-dimensions, with low degree of crystallinity, and appear to be composed of manganese oxides such as birnessite, ramsdellite and groutellite. They were associated with large amounts of extracellular polymeric substances exuded by filamentous bacterial communities, which serve as nuclei for preferential precipitation of manganese oxides on the extracellular sheaths, as seen in scanning electron microscope analyses.

Mn required for patina formation likely derives from the reductive dissolution in water of Mn-rich minerals, as suggested by the mineralogy and chemistry of Mn-rich phases present in the building granite and mortars. Mn migrates to the exposed surface of building materials, where they are re-oxidized via biological processes. Patinas developing over time result from the alternation of wetting-reducing and drying-oxidizing cycles.

Water absorption, dampness and black patinas are among the most common and critical problems when it comes to decay of both cultural heritage and modern buildings. The climate and specifically the humidity are determinant for the development of Mn-rich black patinas. Results revealed that chemical composition and porosity played a major role in the development of biological activity that generates the black patinas of manganese oxides on mortars and granite.

How to cite: Freire-Lista, D. M., Blanco-Rotea, R., Costa, M. D. R., and Sanjurjo-Sánchez, J.: Mn-rich Black Patina Formation on Built Heritage in Humid Areas, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8670, https://doi.org/10.5194/egusphere-egu22-8670, 2022.

Weathering is a key component of the geomorphological process system and poses a major threat to cultural heritage, such as building structures and rock art sites. Since almost all rock decay is enhanced by the presence of water, research on moisture content and flow is crucial to understanding weathering processes. Nevertheless, measuring rock moisture and its fluctuations is difficult as there is no universally used sensor that meets the requirements of non-destructiveness, reliability, repeatability, and applicability at field sites. Therefore, this work aims to evaluate several moisture measurement techniques under different natural conditions and to provide recommendations for their use. We tested seven types of methods (1D resistivity, 2D resistivity, TDR, borehole humidity, microwave reflectance, IR thermography, and uranine probes) under controlled conditions in a sandstone block that was subject to a slow wetting and drying cycle and to a series of freeze-thaw cycles.

Overall, the methods measuring dielectric properties of the rock (TDR, microwave) can be generally recommended for their reliability, repeatability, and applicability at field sites. Precise observation of moisture dynamics in deeper subsurface however remains a challenge, especially when moisture contents are close to drier states. Therefore, to get reliable water content data, it is vital to drill inside the rock rather than to use surface sensors, which are particularly sensitive to surface moisture and surface roughness. Nonetheless, out of the non-destructive surface methods, dielectric sensors using the microwave spectrum with a greater penetration depth (>10 cm) should be considered as they have the advantage of interacting the transmitted signal into a larger volume of material, therefore making the influence of surface less pronounced. Furthermore, the use of electrical resistance methods is less recommended because of mainly two factors: they need to be calibrated for each sensor pair, and they are prone to erroneous measurements in the presence of salts. Concerning the other methods, probes using a reactive dye, and borehole humidity sensors can be used to determine the location of the subsurface evaporation front where salt crystallisation takes place, and the IR imaging for studying evaporation dynamics needs either highly controlled environment or continuous measurement. In conclusion, this work provides new insights into rock moisture measurements and further research should focus on subsurface moisture measurements and the improvement and calibration of available techniques.

How to cite: Weiss, T. and Sass, O.: The challenge of measuring rock moisture: A laboratory experiment using eight types of sensors, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8814, https://doi.org/10.5194/egusphere-egu22-8814, 2022.

Water plays a vital role in the deterioration and conservation of built heritage and management problems might be aggravated by climate change. However, there is as yet no overarching framework for understanding the processes and impacts of water interacting with building materials. The term 'Heritage Hydrology' is a holistic way of conceptualising the flows and stores of water involved in deterioration of built and rock-hewn heritage. We distinguish the following basic types: (a) stone-built buildings, (b) ruins and free-standing walls, and (c) rock-hewn sites which include carved rock art and large rock sculptures. We focus on a key knowledge gap: The spatial and temporal characteristics of water flows/stores and the challenges of using currently available techniques to provide information on these characteristics.

In our selective review we provide examples of spatio-temporal patterns of moisture in stonework at different scales. We raise six key points about the state of research on heritage hydrology, from which we develop a future research agenda. (1) Three characteristics of moisture regimes are important to deterioration, i.e. presence, fluctuations and saturation thresholds. (2) There is a wide range of different heritage hydrological settings ranging from masonry building walls to natural rock slopes, and as yet no clear understanding of the commonalities vs specificities of these different settings. (3) While there is now a wide array of techniques available to measure and monitor moisture regimes in lab and field settings, the understanding of how comparable different measurement approaches are is still lacking. (4) There are now many measurements of the spatial patterning of moisture, but lack of clarity about the causes of these patterns. (5) There has been less research focusing on the temporal dynamics of moisture on heritage walls than on spatial patterns. (6) Studies combining measurement and modelling have proved particularly useful.

A research agenda for the future for heritage hydrology should focus on addressing the following broad questions: What are the best combinations of methods available to measure and model spatio-temporal patterns in moisture on built and rock-hewn heritage? What are the major factors controlling spatio-temporal patterns in moisture, also considering climatic changes? Which spatio-temporal patterns in moisture are most important for driving deterioration, and how do their respective scales interact? Tackling these research questions requires a coordinated approach, linking different research teams and methodologies. It should be based on a combination of data collected through laboratory experiments, detailed studies of test walls, and instrumented sections of walls at heritage sites. It should explore the causes and consequences of moisture regimes which provide fundamental links between climate and the deterioration of built and rock-hewn heritage.

How to cite: Sass, O. and Viles, H.: Heritage hydrology: A conceptual framework for understanding water fluxes and storage in built and rock-hewn heritage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10024, https://doi.org/10.5194/egusphere-egu22-10024, 2022.

EGU22-11582 | Presentations | ERE1.4

A risk assessment tool for the protection of cultural heritage exposed to extreme climate events. 

Alessandro Sardella, Stefano Natali, Riccardo Cacciotti, Milos Drdácký, and Alessandra Bonazza

The risk to cultural heritage as a consequence of the impact of climate change is globally recognized, even though not exhaustively tackled with sustainable solutions and tools addressed to support policy and decision makers in the preparedness phase of risk reduction and management cycle.

This contribution aims at presenting the methodological approach applied and main results of the “Risk mapping tool for cultural heritage protection” specifically dedicated to the safeguarding of cultural heritage exposed to extreme climate changes, produced in the framework of the Interreg Central Europe STRENCH (2020 - 2022). STRENCH project is strongly based on a user-driven approach and the multidisciplinary collaboration among the scientific community, public authorities, rescue bodies and the private sector (https://www.protecht2save-wgt.eu/).

The presented tool provides hazard maps for Europe and in the Mediterranean Basin where cultural and natural heritage is exposed to heavy rain, flooding and prolonged drought. The tool enables assessing risk of cultural heritage assets based on:

  • the computation of extreme changes of precipitation and temperature performed using climate extreme indices defined by the Expert Team on Climate Change Detection Indices (ETCCDI);
  • the exploitation of the Copernicus Climate Change Service (C3S), together with Earth Observation-based data and products;
  • the integration with outputs from Regional Climate Models from the Euro-CORDEX experiment under two different scenarios (RCP4.5 and RCP8.5);
  • a developed methodology for identifying the main critical elements determining the vulnerability of cultural heritage;
  • the ranking of the vulnerability taking into account 3 main aspects, namely the susceptibility, exposure and resilience of cultural heritage.

Preliminary results from the testing of the “risk mapping tool” at European case studies (Krems-Stein in Austria and Troja-Prague in Czech Republic) allow concluding on the feasibility and applicability of the tool presented in the perspective of optimizing preparedness strategies and mitigating the risk of cultural heritage subject to climate change related actions.

In conclusion, the STRENCH project, through the implementation of its outputs, is expected to proactively target the needs and requirements of stakeholders and policymakers responsible for disaster mitigation and safeguarding of cultural heritage assets and to foster the active involvement of citizens and local communities in the decision-making process.

How to cite: Sardella, A., Natali, S., Cacciotti, R., Drdácký, M., and Bonazza, A.: A risk assessment tool for the protection of cultural heritage exposed to extreme climate events., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11582, https://doi.org/10.5194/egusphere-egu22-11582, 2022.

The climate of the city of Tønsberg in Norway is cold and humid. As a result, the brick-made historic buildings in this city are threatened by frost damage. Climate change is expected to affect the action of this degradation mechanism. In the current research, climate data resulting from the REMO2015 driven by the global model MPI-ESM-LR were used for periods 1960-69, 2010-2019, and 2060-69 representing the past, present, and future climate conditions. In addition, data from the ERA5 reanalysis for the present conditions, 2010-19, were used to assess the accuracy of the climate model data. Given the climate excitations, the freeze-thaw events were calculated according to two climate indices, i) the events of temperature decrease below 0oC and ii) by considering that freezing occurs below -3oC and thawing occurs above 1oC. Moreover, a material response-based index that takes into account the temperature and the moisture content of a 5mm layer in the exterior side of the wall assembly was calculated. Prior to its calculation proper hygrothermal simulations were performed. According to this index, the critical temperature and degree of saturation that characterize a freeze-thaw event are 0oC and 25%, respectively. From the climate model data and the first climate index, the 0oC crossings that were calculated are 400, 340, and 223 under the past, present, and future conditions, respectively. The respective number of the freeze-thaw events that were calculated by using the second climate index are 49, 31, and 27 which are significantly lower. From the data obtained from the ERA5 reanalysis, the number of freeze-thaw events that were calculated is 425 and 123 for the first and the second climate index, respectively. This difference is attributed to the underestimation of the air temperature in the climate model data, which results in a lower number of temperatures hovering around the examined thresholds during winter. The results of the material response-based index show a minor frost risk for the brick-made wall assemblies which is reduced through the years. The southeast-oriented walls were the ones with the highest exposure to driving rain and the greatest frost damage risk. For this orientation, the number of freeze-thaw events was 6, 3, and 2 under past, present, and future conditions, respectively. Moreover, according to the ERA5 reanalysis, only 1 freeze-thaw event was calculated. This is attributed to the fact that the climate model overestimates significantly the precipitation and the relative humidity compared to the ERA5 reanalysis. In conclusion, it is worth mentioning that both the climate-based and the material response-based indices define a decreasing trend of the frost damage risk of historic brick-made walls due to climate change. The use of the material response-based index is suggested for a more accurate assessment of the frost damage which can further support proper adaptation measures. Finally, the quality of the results can be improved by using climate data from more climate models and applying bias correction or morphing methodologies on the climate files to avoid systematic errors.

How to cite: Choidis, P. and Kraniotis, D.: Climate-based and material response-based approaches for the impact assessment of climate change on the frost damage of historic brick walls in Tønsberg, Norway., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12070, https://doi.org/10.5194/egusphere-egu22-12070, 2022.

Dust is one of the main pollutants that settle on historic structures and cause the blackening of stone surfaces. The stone facades of historic buildings became dark, and besides its aesthetic alteration, dust deposition and subsequent chemical reactions led to the deterioration of the construction material. The composition of dust changes in time due to climate change, clean air acts and changes in transportation, industrial activities and heat. The present study tries to detect the temporal changes in the composition of dust by using a stone buildings as dust traps in Budapest. The studied historic building is more than one hundred years old, and no façade cleaning was done in the past century. Visual inspection of the city centre building suggested that dust accumulation show a distinct pattern representing differences in the vertical profile in terms of thickness and colour. Dust samples were collected from layer to layer representing newly settled and historical dust. Scaffolds were made to reach the various elevations of the building facades. Besides the dust, host rock samples were also picked to detect textural and compositional changes of the porous oolitic limestone material. The textural-mineralogical analyses (XRD, SEM) and chemical compositional tests (XRF, LA-ICP-MS) provide evidence of changes in composition of dust with time. In all host rock samples, gypsum was detected but in various proportions. Good correlations were also found between water-soluble calcium and gypsum content and between sulphate and gypsum content both for black crusts and host rocks, forming two distinct fields in calcium vs gypsum and sulphate vs gypsum graphs. Gypsum was also found in the dust either as a primary or as a secondary mineral phase. Metals, transition metals and water-soluble ions also occur in various concentrations in different layers of dust. The detected elements primarily include  Fe, Mn, Zn, Cu, Cr, Pb, Ni. From soluble salts, chloride, nitrate and sulphate were also detected. The changes in elemental and ionic concentrations reflect temporal changes in dust composition and provide indirect evidence for air quality changes and air pollution levels.

How to cite: Török, Á.: Compositional changes of settling dust in time on buildings in Budapest: centennial evidence of air pollution trends, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12113, https://doi.org/10.5194/egusphere-egu22-12113, 2022.

EGU22-790 | Presentations | ERE1.6

Lithification of slag-dominated artificial ground through atmospheric CO2 drawdown 

John MacDonald and Connor Brolly

Legacy deposits of by-product slag from iron and steel making create significant volumes of artificial ground around the world. Composed mainly of calcium-silicate mineral phases, experimental studies have shown the potential of slag for capturing atmospheric CO2 by mineralisation (e.g. Huijgen et al. 2005). Renforth (2019) calculated that steel slag could capture ~370-400 kg CO2 per tonne of slag, depending on the type of slag. ~0.5 Gt of steelmaking slag is produced every year (USGS 2018) and this could potentially reach ~2 Gt yr-1 by the end of the century (Renforth 2019). In addition to new slag, there is an estimated 160 million m3 of legacy slag in the UK alone (Riley et al. 2020), stockpiled or dumped from historical steelmaking.

Artificial ground poses challenges around ground stability but slag-dominated artificial ground also offers opportunities for atmospheric CO2 drawdown. In this contribution, we document the lithification of legacy slag deposits – conversion of loose gravelly slag material into a rock-like mass through cementation of calcite via drawdown of atmospheric CO2.

Parts of slag heaps at our case study sites (Glengarnock and Warton, UK) have a lithified nature: gravel-to-cobble sized lumps of slag are visible but have been cemented together with a mineral cement, with an appearance not unlike a natural breccia rock. We present field, X-Ray Diffraction and δ13C data from these case study sites to document the lithification of slag-dominated artificial ground through mineralisation of atmospheric CO2 as a cementing phase; we present scanning electron microscope data to show the microstructural evolution of this lithification. This understanding has implications for artificial ground stabilisation and how atmospheric CO2 drawdown can be harnessed in this process.

 

References

Huijgen et al., 2005, ES&T, 39, 9676-9682

Renforth, 2019, Nat. Comms., 10, 1401

Riley et al., 2020, J. Geochem. Exp., 219, 106630

USGS, 2018, USGS Minerals Yearbook

How to cite: MacDonald, J. and Brolly, C.: Lithification of slag-dominated artificial ground through atmospheric CO2 drawdown, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-790, https://doi.org/10.5194/egusphere-egu22-790, 2022.

EGU22-1352 | Presentations | ERE1.6

Anthropogenic biodiversity and geodiversity – can legacy industrial waste help offset falling global biodiversity? 

Savanna van Mesdag, John MacDonald, Iain Neill, and Alistair Jump

Anthropogenic substrates are produced as waste materials and/or by-products of various industries. Such substrates include: blast furnace/steel slag; colliery spoil; oil shale spoil; and paper mill sludge (Ash et al. 1994; Riley et al. 2020). Historically, in the UK, these substrates were dumped in or close to the sites where they were being produced (Riley et al. 2020). Many examples of anthropogenic substrate sites still exist in the UK, despite the fact that there has been much cultural motivation to restore these sites (Ash et al. 1994; Bradshaw, 1995; Riley et al. 2020). This often results in either the total removal of anthropogenic substrate, or the covering of anthropogenic substrate with a clay cap/similar natural substrate. However, if left undisturbed, such sites could potentially provide undisturbed spaces for wildlife.

Various studies have been carried out which demonstrate that wildlife, including unusual and/or important species communities, can colonise and live on anthropogenic substrate sites (Ash et al. 1994; Riley et al. 2020). It is important to note that because anthropogenic substrate often differs greatly from the natural substrate in the surrounding area, such sites can support species and communities which might not otherwise survive in that area. For example, plants that rely on calcareous substrates might settle on slag sites or on Solvay process waste sites, but might not otherwise settle in the area if natural calcareous substrate is absent (Ash et al. 1994). Anthropogenic substrate sites can, therefore, act as refugia for many species and communities.

This study investigates three important aspects of anthropogenic substrate sites: substrate chemistry and mineralogy; plant species and communities; and certain invertebrate species. The investigation of these aspects allows for a detailed study of both anthropogenic geodiversity and biodiversity. For the substrates, various analyses will be carried out to determine the minerals, elements and pH levels present, including X-ray Diffraction, ICP and pH analysis for the six study sites. Different plant communities, as well as the species within them, were recorded in 2021 using quadrats in the six study sites. Different invertebrate species were recorded in 2021, throughout three of the study sites. Due to the current biodiversity crisis, it is more important than ever before to record and assess the biodiversity of places, especially if such places are often overlooked in terms of biodiversity potential. Additionally, very few studies have investigated the relationships between plant species and the mineralogical and elemental composition of the substrates on which they are growing – this work helps us to investigate plant establishment, survival and growth on anthropogenic substrates in a novel manner.

Ash et al., 1994, J. Appl. Ecology, 71, 74-78

Riley et al., 2020, J. Geochem. Explor., 219, 106630

Bradshaw, 1995, Can. J. Fish. Aquat. Sci. 53, 3-9

How to cite: van Mesdag, S., MacDonald, J., Neill, I., and Jump, A.: Anthropogenic biodiversity and geodiversity – can legacy industrial waste help offset falling global biodiversity?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1352, https://doi.org/10.5194/egusphere-egu22-1352, 2022.

Bauxite residue, the by-product produced in the alumina industry, is generated at an estimated global rate of approximately 150 million tonnes per annum. Currently, the reuse of bauxite residue is low (∼2%), and consequently the bulk is stored in land-based impoundments.

If not adequately managed, exposed residue may be prone to dusting, wind and water erosion and can contaminate surrounding areas. Establishing vegetation covers (rehabilitation) is viewed as an effective strategy for mitigating against pollution risk and approaches used can be broadly divided into capping with inert soil material or establishing vegetation in the tailings surface (revegetation). Revegetation provides a strategy where topsoil material is scarce and avoids the sourcing of large volumes from other sites.

While bauxite residue is typically alkaline (pH 10-12), saline and lacking in nutrients the implementation of effective rehabilitation strategies can promote favourable soil conditions for plant growth. Results also show establishment of soil microbial communities and soil faunal activity. These positive rehabilitation effects are maintained for several years and demonstrate that residue can be transformed to a soil-like medium capable of supporting ecosystem function.

How to cite: Courtney, R.: Technosols derived from bauxite residue tailings for effective revegetation and rehabilitation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2318, https://doi.org/10.5194/egusphere-egu22-2318, 2022.

EGU22-4044 | Presentations | ERE1.6

Analysis of metal entrapment within anthropogenic tufa using synchrotron micro-XRF 

Susan Cumberland, Kieran Tierney, Joanna Renshaw, Kalotina Geraki, and John MacDonald

The leaching of heavy metals from post-industrial slag and other anthropogenic waste sites is detrimental for human health and the wider environment. Remediation of these sites can be costly and sustainable low carbon solutions are preferably sought. Examining natural analogues which stabilize metals could provide valuable insights into low-cost solutions to the legacy problems of aquatic environments that are impacted by leaching. Calcareous tufa, sometimes known as travertine limestone, forms naturally when calcium-rich groundwater is exchanged with atmospheric CO2 at mid to hyperalkaline pH resulting in a calcite (CaCO3) precipitation. Tufa has also been observed to form at a small number of old industrial sites (e.g. mining, steel works, paper mills) across northern England and Scotland. One site of interest is at Consett, N.E England, UK. Here tufa precipitates in the Howden Burn stream, a tributary of the River Derwent, as it emerges from the slag heaps from old steel work’s. Bulk analysis shows lead, arsenic, vanadium and zinc are present in the Howden Burn up to several 100 ppm.  Analysis of the water downstream of the tufa shows metal concentrations are considerably reduced compared to concentrations upstream. High spatial resolution LA-ICP-MS analysis of the solid tufa sampled reveal metals present within the tufa structure. This leads to the hypothesis that the metals are precipitated together with the tufa during its formation. However, little is known about metal capture processes during tufa formation and the form that these metals are in.  Here we present synchrotron micro X-ray fluorescence (μ-XRF) element maps of the tufa in cross-section that show the distributions of the metal within the laminations of the tufa structure. Understanding and exploitation of artificial tufa for metal capture could have potential as a CO2 positive solution for sustainable in-stream remediation. 

How to cite: Cumberland, S., Tierney, K., Renshaw, J., Geraki, K., and MacDonald, J.: Analysis of metal entrapment within anthropogenic tufa using synchrotron micro-XRF, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4044, https://doi.org/10.5194/egusphere-egu22-4044, 2022.

EGU22-4137 | Presentations | ERE1.6

Iron and steel-making slags as an environmentally-beneficial resource; a UK perspective. 

Alex Riley, Patrizia Onnis, Catherine Gandy, John MacDonald, Ian Burke, Phil Renforth, Adam Jarvis, Karen Hudson-Edwards, and William Mayes

The production of iron and steel has generated substantial volumes of slag as waste, with estimates of up to 384 million tonnes (Mt) of iron slag and 280 Mt of steel slag produced globally, to date. Whilst the majority of these by-products (approximately 70 %) have seen bulk re-use in a number of applications (e.g. as ballast in construction applications), a significant volume of slag has been disposed of in environmental settings, where the release of metal-rich alkaline leachates can cause enduring pollution. However, the mineralogical and physical properties of slags also offer opportunity for environmental benefits, namely; through sequestration of atmospheric carbon dioxide, by acting as stockpiles of critical raw materials, and in certain situations performing as incidental coastal defences.

Findings are presented from national-scale field investigations, laboratory experiments, and spatial data analyses, which aim to explore the resource potential of iron and steel slags in the United Kingdom (UK). Within the 236 Mt of slags disposed of in the UK environment, projected carbonation rates revealed a potential for uptake of 138 Mt CO2 under enhanced weathering conditions. Notable masses of technologically-critical elements were also estimated within UK slags, with reserves in the region of 1.55 Mt of V2O5, 1.58 Mt of TiO2, and 1.26 Mt of Cr2O3 estimated. Further to acting as a resource, in areas of coastal deposition, slag banks were observed to offer tidal protection. At a number of sites this allowed the development of nationally-significant ecological communities, whilst laboratory leaching experiments reveal a very low risk of chemical leaching in saline conditions. The integration of spatial analyses with chemical composition and leaching data can help to inform decisions on maximising resource potential whilst minimising the potential environmental risks associated with slag reworking.

How to cite: Riley, A., Onnis, P., Gandy, C., MacDonald, J., Burke, I., Renforth, P., Jarvis, A., Hudson-Edwards, K., and Mayes, W.: Iron and steel-making slags as an environmentally-beneficial resource; a UK perspective., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4137, https://doi.org/10.5194/egusphere-egu22-4137, 2022.

EGU22-4645 | Presentations | ERE1.6

The utilisation of X-ray Micro-Computed Tomography (XCT) for the quantification of carbon dioxide in passively carbonated steel slag. 

Jose Porfirio Del Angel Lozano, Alice Macente, and John MacDonald

Mineral sequestration using solid alkaline by-products, such as steel slag, is a feasible technology to capture carbon dioxide. This silicate weathering reaction forms solid carbonates, mineralizing the atmospheric CO2 into calcite, which can occur passively under ambient environmental conditions over monthly to decadal timescales. The passive mineralization of carbon dioxide in steel slag is a not well-known reaction, particularly when climate factors influence the mineral carbonation. Non-destructive quantification of CO2 mineralization is necessary to set underpinning knowledge on capturing rates.

The utilisation of X-ray micro-Computed Tomography (XCT) allows the 3D spatial visualisation and quantification of carbon dioxide precipitated as calcite in steel slag pores. We used XCT to analyse samples of legacy steel slag collected in Mexico and Scotland, to determine the effects of environmental factors on mineral carbonation. The XCT data were analysed with image processing to classify the slag volume into three phases (slag, pores, and calcite). The classification of the data into different phases allows the determination of the volume of each phase in the sample as well as its 3D spatial extent, thus enabling the quantification of mineralized CO2 characterized as the calcite phase.

We will present a comparison between the volumes of carbon dioxide passively mineralized in the samples from the Mexican and Scottish collection sites, in the context of contrasting environmental factors. Preliminary results from one of the Scottish samples shows that calcite (mineralized CO2) accounts for  ~ 5 vol. % of the sample, and it is localised across the whole sample.  A comparison of these results between the Mexican and Scottish samples will provide a better understanding of how climatic factors influence the volumes of atmospheric CO2 mineralized by the samples. 

How to cite: Del Angel Lozano, J. P., Macente, A., and MacDonald, J.: The utilisation of X-ray Micro-Computed Tomography (XCT) for the quantification of carbon dioxide in passively carbonated steel slag., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4645, https://doi.org/10.5194/egusphere-egu22-4645, 2022.

EGU22-4824 | Presentations | ERE1.6

An investigation of crushed returned concrete (CRC) as a soil amendment for atmospheric CO2 removal 

Frank McDermott, Maurice Bryson, and David van Acken

Soils have high pCO2 because of the decay of organic matter and plant root respiration. Some of this CO2 dissolves to form carbonic acid in soil waters. Natural weathering partially neutralizes this carbonic acid, but in recent years there has been much interest in using soil mineral and rock amendments (e.g. added olivine and basalt) to accelerate weathering-driven atmospheric CO2 drawdown to counter rising atmospheric CO2.  To be effective, accelerated weathering should result in increased dissolved bicarbonate (the main dissolved inorganic carbon carrier at circum-neutral pH) in drainage waters, as well as enhanced land-to-ocean fluxes of divalent metal cations such as Ca and Mg, ultimately to lock up the soil-derived inorganic carbon in marine limestones. Here we present new results for field experiments that investigate a novel soil amendment to sequester CO2 from soil-gas via weathering; crushed returned concrete (CRC). Unlike previously investigated mafic and ultramafic materials for accelerated weathering approaches that generally require energy- and carbon-intensive mining, grinding and long-distance transport operations, CRC is a waste product that requires minimal crushing after post-return solidification at concrete plants to achieve high measured specific surface areas (c. 10 m2/g).  CRC is widely available globally because a few % of the >10Gt/year of concrete produced is typically returned unused to concrete ready-mix plants.  Engineering codes preclude the reincorporation of this waste as aggregate in new concrete in many jurisdictions. This results in the widescale availability of this highly weatherable alkaline waste product that is often landfilled or sold as a low-value construction fill.  Local availability of the material facilitates short haulage distances and relatively small energy and carbon footprints to transport the material to nearby field sites.  In this pilot study, CRC was added to the upper 15 cms of a one-hectare trial tillage field in SE Ireland at a rate of 10 tonnes/hectare. Soil-water solutions were extracted for analysis using suction-cup lysimeters at monthly intervals from the amended and adjacent non-amended control sites to determine the geochemical impact of CRC on soil waters and to calculate weathering and therefore CO2 uptake rates via carbonic acid neutralisation. Relative to adjacent control sites, concrete-amended sites exhibited significant increases in soil-water pH (by 0.2 to 0.5 pH units), a two- to three-fold increase in electrical conductivity (total ion load) and similar increases in soil-water Ca2+, reflecting the weathering of portlandite and calcium silicates in the concrete. Field experiments are ongoing to assess the long-term effects of the concrete amendment on soil-water chemistry, soil pH and nutrient status. No increases in detrimental heavy metals (e.g. Ni, Cr) often associated with the use of mafic and ultramafic materials as soil amendments have been detected. Weathering is attributable entirely to carbonic acid neutralization, with no evidence for weathering by strong acids. Methods for the calculation of likely rates of CO2 capture (tonnes CO2 per tonne of amendment) and their associated uncertainties based on alkalinity increases, divalent metal exports and enhanced soil-leachable Ca will be discussed. 

How to cite: McDermott, F., Bryson, M., and van Acken, D.: An investigation of crushed returned concrete (CRC) as a soil amendment for atmospheric CO2 removal, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4824, https://doi.org/10.5194/egusphere-egu22-4824, 2022.

EGU22-6308 | Presentations | ERE1.6

Carbonation and cementation of ultramafic mine wastes 

Justin Lockhart, Ian Power, Carlos Paulo, Amanda Stubbs, and Duncan McDonald

Ultramafic (Mg-rich) mine wastes are produced in vast quantities, are of no economic value, and their storage impoundments can be susceptible to catastrophic failure.1 Carbon dioxide (CO2) mineralization of these wastes to form carbonate cement can reduce greenhouse gas emissions2 and assist in de-risking storage impoundments through physical stabilization.3 CO2 mineralization and cementation have been documented at asbestos,4 nickel,2 and diamond mines, occurring unintentionally over long periods (e.g., decades).2,4 This research aimed to 1) better understand carbonation and cementation processes by examining historic kimberlite mine wastes from diamond mines and 2) accelerate these processes in experiments using brucite-bearing serpentinite mine wastes. 

We collected physical, mineralogical, and geochemical data of cemented historic kimberlite wastes 70 to >110 years old. Analysis of cemented fine- and coarse-grained residues from the Voorspoed and Cullinan diamond mines (South Africa) revealed the presence of a fine-grained (<63 µm) cement matrix with greater total inorganic carbon (TIC; +0.08–0.34% relative to clasts), secondary clays (e.g., Mg-Al silicates), and some minor carbonates (e.g., calcite). Unconfined compressive strength varied considerably between fine- and coarse-grained wastes (UCS; 0.13–4.45 MPa). Furthermore, kimberlite clasts and cements were isotopically distinct, suggesting that mineral weathering by meteoric water drove cementation over decades after the deposition of these wastes. 

In experiments, coupling organic and inorganic carbon cycling accelerated carbonation of synthetic tailings that contained brucite [Mg(OH)2], a minor yet reactive mineral. In cylindrical test experiments (2.5 × 5 cm; 40 weeks), waste organics were either mixed (0–10 wt.%) or kept separate from brucite-bearing serpentinite mine wastes to provide an additional source of CO2. In the mixed cylinders, brucite consumption ranged from 3–30% and was limited by CO2 generation, as evidenced by minor increases in TIC (+0.02–0.22%). Compressive strengths amongst the cylinders reached 0.51 MPa with few cylinders becoming sufficiently stabilized; however, in experiments that exposed cylinders to CO2 generated from organics separate from cylinders, brucite carbonation (64–84% consumption) and compressive strengths were substantial (0.4–6.9 MPa).3 Our research demonstrates the role of long-term weathering for sequestering CO2 within ultramafic mine wastes, and how coupling organic and inorganic carbon cycling can accelerate CO2 sequestration and physically stabilize these wastes. 

References: 

1. Rourke and Luppnow (2015), Tailings Mine Waste Manag., 225–230. 
2. Wilson et al. (2014), Int. J. Greenh. Gas Control 25, 121–140. 
3. Power et al. (2021), Environ. Sci. Technol. 55, 10056–10066. 
4. Wilson et al. (2009), Econ. Geol. 104, 95–112.

How to cite: Lockhart, J., Power, I., Paulo, C., Stubbs, A., and McDonald, D.: Carbonation and cementation of ultramafic mine wastes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6308, https://doi.org/10.5194/egusphere-egu22-6308, 2022.

EGU22-6525 | Presentations | ERE1.6

Passive CO2 mineralisation in slag: evidence from a slag heap in Lanarkshire, Scotland. 

Faisal W. K. Khudhur, Alice Macente, John MacDonald, and Luke Daly

CO2 mineralization is a natural process that occurs during weathering of silicate materials that are calcium/magnesium-rich and aluminum-poor (Kelemen et al., 2020). During this process, silicates convert to carbonates, making silicate-rich materials such as ultramafic rocks and alkaline wastes suitable for CO2 removal from air.  Using slag to sequester CO2 is particularly attractive as it is a by-product of a key industry, and it can utilize CO2 from the emission source, therefore reducing the need for CO2 and slag transportation, or draw down of CO2 already in the atmosphere. It is estimated that steel slag has the potential to capture ~150-250 Mt CO2 yr-1 now, and ~320-870 Mt CO2 yr-1 by 2100 (Renforth, 2019).

Although the chemical composition of alkaline wastes shows that CO2 capture can significantly offset emissions from corresponding industries, recent observations reveal that the CO2 uptake in alkaline wastes in underutilized (Pullin et al., 2019). Here, we use image-based analysis to understand the microstructures of CO2 mineralization in slag. We use X-ray Computed Tomography (XCT) to visualize slag internal structures and to calculate reactive surface area and pore connectivity. We then use scanning electron microscopy (SEM), coupled with energy dispersive spectroscopy (EDS) to study the distribution of elements within the studied sample.

In our study, we use a slag sample collected from the former Ravenscraig Steelworks in Lanarkshire, Scotland, where steelmaking took place from 1950s until 1992 (Stewart, 2008), leaving behind a slag heap that has been weathering since then. Our analysis demonstrates that calcium carbonate precipitates as pore-lining. Surface passivation and low surface-connected porosity were identified as processes that can cause reduction in CO2 uptake.

 

References

 

Kelemen, P.B., McQueen, N., Wilcox, J., Renforth, P., Dipple, G., Vankeuren, A.P., 2020. Engineered carbon mineralization in ultramafic rocks for CO2 removal from air: Review and new insights. Chem. Geol. 550, 119628. https://doi.org/10.1016/j.chemgeo.2020.119628

Pullin, H., Bray, A.W., Burke, I.T., Muir, D.D., Sapsford, D.J., Mayes, W.M., Renforth, P., 2019. Atmospheric Carbon Capture Performance of Legacy Iron and Steel Waste. Environ. Sci. Technol. 53, 9502–9511. https://doi.org/10.1021/acs.est.9b01265

Renforth, P., 2019. The negative emission potential of alkaline materials. Nat. Commun. 10, 1401. https://doi.org/10.1038/s41467-019-09475-5

Stewart, D., 2008. Fighting for Survival: The 1980s Campaign to Save Ravenscraig Steelworks. J. Scottish Hist. Stud. 25, 40–57. https://doi.org/10.3366/JSHS.2005.25.1.40

How to cite: Khudhur, F. W. K., Macente, A., MacDonald, J., and Daly, L.: Passive CO2 mineralisation in slag: evidence from a slag heap in Lanarkshire, Scotland., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6525, https://doi.org/10.5194/egusphere-egu22-6525, 2022.

EGU22-8116 | Presentations | ERE1.6

Anthropogenic tufa at legacy industrial sites: Potential for metal capture 

Marta Kalabová, Susan Cumberland, Joanna Renshaw, and John MacDonald

Uncontrolled leaching from legacy industrial waste may release toxic elements, which poses long-term risks of water and soil contamination. In some situations, secondary mineralisation from the leachates may occur downstream from waste sites, thus potentially limiting contaminant migration. An example is tufa, a surface freshwater CaCO3 (calcite) deposit which forms as a result of atmospheric CO2 absorption into Ca-rich hyperalkaline leachates. The tufa develops a range of morphologies and varies in hardness across the deposit. Moreover, it may also incorporate other elements into its mineral structure during precipitation. Understanding the processes of secondary mineralisation which are able to capture toxic metals would provide beneficial insights into controlling hazardous leaching.

This work characterises tufa occurring within anthropogenic contexts. Several tufas were found forming on or adjacent to anthropogenic sites (colliery spoil and steel slag heaps) in central Scotland, UK and studied for their geochemistry. A combination of direct field measurements of water physico-chemistry is complemented by alkalinity and elemental analyses of leachate source, water and tufa by ion chromatography (IC) and ICP-OES. The results from these analyses will help understand the processes involved in tufa formation and can be applied to the re-creation of tufa with the purpose of metal capture under controlled laboratory conditions. Early experiments have focused on CaCO3 precipitation onto different media by bubbling CO2 into CaCl2 solutions. The aim of these experiments is to create an engineered metal-capturing tufa system which can be applied across different post-industrial settings as a low-cost technique which beneficially captures CO2.

How to cite: Kalabová, M., Cumberland, S., Renshaw, J., and MacDonald, J.: Anthropogenic tufa at legacy industrial sites: Potential for metal capture, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8116, https://doi.org/10.5194/egusphere-egu22-8116, 2022.

The development of civilization is accompanied by a continuous increase in the production of various types of waste, especially municipal solid waste (MSW). The problem of rational MSW management has become one of the most pressing global challenges [1].

The countries which joined the EU in the middle of the last century can serve as examples of establishing effective MSW management systems. Presently, the amount of recycled MSW in these countries is rather high: recycling constitutes – 30–40%; incineration – 30–50%; composting – 18–20%; the amount of MSW disposed of at a landfill has been reduced to 1–3%. All these factors made it possible to increase the MSW revenues in Germany 4.8 times over the last 25 years; in Sweden – 3.29 times; in Denmark – 2.76 times, and in the Netherlands – 3.06 times.

Based on the above data, a conclusion can be made about the expediency of implementing MSW management in Russia.  

Thus, if we consider the creation of such a system for Saint Petersburg generating 1.82 million tons of MSW annually and recycling 40% of MSW, incinerating 35%, composting 23% and landfilling 2%, then an estimated revenue from the implementation of secondary raw materials can be determined:

C=M1xC1+M2xC2+M3xC3-M4xC4

where: M1 – the mass of MSW realized by the allocation of secondary raw materials, M2 – incineration, M3 – composting, M4 – landfill,

C1 – specific revenue from the implementation of secondary raw materials, C1=1254  ruble/tonne [2],

C2 – МSW incineration, C2=850  ruble/tonne [3],

C3 – MSW composting, C3=400  ruble/tonne [2],

C4 – MSW disposal, C4=350  ruble/tonne [2].

The amount of MSW in Saint Petersburg (million tons): secondary raw materials – 0,72,  energy – 0,65, compost – 0,418, landfill – 0,032.

Then the revenue from the implementation of secondary raw materials per annual volume of MSW in Saint Petersburg will be:

C = 902,288 + 535,5 + 165,6 – 12,6 = 1,590,788 million rubles.

The specific revenue indicator for Saint Petersburg MSW per person is as follows:

Cp=1590,788/5,392992=294,9 ruble/person.

In order to implement the considered option of a city-wide program, it is necessary to establish the following enterprises:

– processing of secondary raw materials – four plants with a capacity of 180 thousand tons each;

– МSW incineration – four plants with a capacity of 160 thousand tons each;

– MSW composting – two plants with a capacity of 207 thousand tons each;

– MSW disposal – two landfills with a capacity of 18 thousand tons each.

Conclusion

  • The established systems of MSW management in European countries are highly economically efficient, processing 97–98% of the produced MSW.
  • The creation of a similar MSW management system in Saint Petersburg will significantly improve the environmental conditions of the city and generate 1,590,788 million rubles in revenue annually.

References

  • L.S. Ventsiulis, A.N. Chusov. Municipal Solid Waste is One of the Main Environmental Problems in Russia. Saint Petersburg: Polytechnic University Press, 2017. – page 208.
  • Program to improve the system of collection, transportation and disposal of waste in the Primorsky district of Saint Petersburg. Estimation of revenue from the processing of separately collected waste, 2011.
  • D.I. Kofman, M.M. Vostrikov. Thermal Destruction and Neutralization of Waste. Saint Petersburg, NPO Professional, 2013. – page 340.

How to cite: Voronov, N. and Ventsyulis, L.: Economic efficiency of sales of municipal solid waste based on the development of the regional market of certified secondary raw materials, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8727, https://doi.org/10.5194/egusphere-egu22-8727, 2022.

Clinker substitutes are frequently used in the cement and concrete industries to reduce CO2 emissions associated with production, improve physico-chemical properties and performance, and reduce costs. Pulversized Fly Ash (PFA), a fine waste residue produced in coal-fired power stations, is the commonly used partial clinker substitute in Ordinary Portland cement (OPC) for cements for the immobilisation of low-level nuclear waste (LLW). Because of the global trend to shut-down coal-fired power stations, the production of PFA is decreasing and will eventually cease. Alternative sustainable clinker substitutes can be used must meet strict performance standards for the safe enclosure of LLW for the final disposal. These include physical, chemical, and mechanical properties; performance and suitability for use.

This study investigates the suitability of different materials (natural and anthropologic) as a substitute of PFA in OPC in LLW immobilisation, and compares the behaviour of these substituted cements to those of the current standard. The focus of the study is on the cementing and physico-chemical properties of the cement, and the interaction between groundwater, the cement, and the stored waste.

Here we present the characterisation the standard PFA+OPC (samples provided by Low-Level Waste Repository Ltd.) using X-ray computed tomography (XCT), and the latest data from the ongoing analysis elemental composition of the alternative materials and the leaching tests. Over the leaching period the samples undergo repeated XCT analysis to link structural changes to the chemical evolution. Future work will include studying the long-term leaching effects and the interaction of the LLW (usage mock waste formulation) with concrete.

These studies will allow us to identify changes to the cement microstructure and physico-chemical properties arising from the PFA substitutes, and the chemical and physical interaction of the cements, especially with groundwater Such understanding is critical for the adoption of clinker alternatives in LLW encapsulation.

How to cite: Kozlowski, A., Renshaw, J., and Dobson, K.: Replacing Pulversized Fly Ash in cement with natural and anthropogenic geomaterials identifying the corresponding physico-chemical properties used for the encapsulation of Low-Level Waste, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11448, https://doi.org/10.5194/egusphere-egu22-11448, 2022.

EGU22-12781 | Presentations | ERE1.6

The compressive strength of earth-hemp blocks tested with different densities, earth types, and cementitious binders 

Guilhem Amin Douillet, Nicolajs Toropovs, Wolfgang Jan Zucha, Ellina Bernard, Anja Kühnis, and Fritz Schlunegger

The building sector needs to shift toward the use of materials that have low-embodied energy, minimize operational-energy, and minimize the amount of waste upon disposal. Here, we report on a series of experiments on low-density earth-hemp blocks, which can be implemented as an insulation for buildings. Earth-hemp finds a similar usage to hempcrete/hemp-lime, yet the use of raw earth as a binder allows to dramatically decrease the embodied energy. The set presented here evidences that pure earth-hemp with high content in clay minerals reaches higher compressive strength (0,33 MPa) than equivalents with hydraulic binder, for similar thermal conductivity (0,07 W/m.K).

Earth-hemp samples were characterized in terms of compressive strength in order to test the influence of density, earth type, incorporation of mineral additives, and amount of water used for creating the blocks. Two types of natural earths were investigated, which differ in their clay content: a surficial loess with 25 wt.% clay minerals and a quarried paleosoil with high clay content (65 wt.%). For each earth type, 4 types of mineral additives were investigated in order to test whether they can have a stabilizing effect: Portland cement, aerial-lime, gypsum-plaster and a MgO-based cement. The binders (i.e. earth + additive) were created with replacement of earth by mineral additives at 0, 4, 8, and 20 wt. %. For each type of binder, 3 densities of the resulting earth-hemp samples were produced (250, 280, 340 kg/m3). Additionally, two series of this set of samples were produced using a low amount of added water (150 wt.% water/hemp) and high amount of added water (370 wt.% water/hemp).

Samples using the earth with high clay content have compressive strengths up to twice as high as those with low clay content. This result is expected since clay minerals are the main agent of binding in earth materials. Also expected was the increase in compressive strength with sample density, which is directly correlated to the amount of binder. More interestingly, the dataset also exhibits the negative effect of mineral additives: a trend of decreasing compressive strength with amount of incorporated mineral additive is visible, independently of the type of additive and earth type. In between additive types, the compressive strengths of samples mixed with MgO-based cement and gypsum-plaster are better than those mixed with Portland cement and aerial lime. Additionally, samples produced using a low amount of added water are much less resistant than those with a high amount of added water for every sample tested. Finally, samples using pure earth with high clay content and high amount of incorporated water are the most resistant, and reach compressive strengths of 0.33 MPa for a density of 340 kg/m3, which is slightly stronger than existing commercial lime-hemp blocks. 

How to cite: Douillet, G. A., Toropovs, N., Zucha, W. J., Bernard, E., Kühnis, A., and Schlunegger, F.: The compressive strength of earth-hemp blocks tested with different densities, earth types, and cementitious binders, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12781, https://doi.org/10.5194/egusphere-egu22-12781, 2022.

EGU22-170 | Presentations | ERE1.7

Comparing miscanthus hybrids – growth and environmental impacts 

Anita Shepherd, Danny Awty-Carroll, Jason Kam, Chris Ashman, Elena Magenau, Enrico Martani, Mislav Kontek, Andrea Ferrarini, Stefano Amaducci, Chris Davey, Mohamad Al Hassan, Vanja Jurišić, Isabelle Lamy, Iris Lewandowski, Emmanuel de Maupeou, Jon McCalmont, Luisa Trindade, Andreas Kiesel, John Clifton-Brown, and Astley Hastings and the Anita Shepherd1

Our research is aligned to the expansion of energy crops with a view to future developments in greenhouse gas removal and we need to ensure that does not have a detrimental effect on the surrounding environment.

Miscanthus is a sustainable bioenergy crop which is wildlife-friendly and will grow on otherwise unproductive land. Mature crops do not require fertilizer thereby ensuring low nitrous oxide emissions. Miscanthus x giganteus (M x g) as a sterile clone, has been propagated vegetatively, with relatively high establishment costs and low multiplication rates. New seed-propagated hybrids, with the potential of upscaling the crop for greater provision, are being readied for market and in crop trials over Europe.

Projections are presented from research involving the international GRACE project and the Supergen SUMMER project. We determine the potential for miscanthus growth and environmental impact, using the hybrids under 21st century climate conditions. We show yield projections which have been modelled using crop trial data across different European countries together with simulations from the MiscanFor model for agricultural soil carbon sequestration and water deficit.

How to cite: Shepherd, A., Awty-Carroll, D., Kam, J., Ashman, C., Magenau, E., Martani, E., Kontek, M., Ferrarini, A., Amaducci, S., Davey, C., Al Hassan, M., Jurišić, V., Lamy, I., Lewandowski, I., de Maupeou, E., McCalmont, J., Trindade, L., Kiesel, A., Clifton-Brown, J., and Hastings, A. and the Anita Shepherd1: Comparing miscanthus hybrids – growth and environmental impacts, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-170, https://doi.org/10.5194/egusphere-egu22-170, 2022.

EGU22-1881 | Presentations | ERE1.7

Impact on native bees from utility-scale solar development in the Mojave and western Sonoran Deserts 

Leslie Saul-Gershenz, Thomas Zavortink, Jenny Van Wyk, John S. Ascher, and Lynn Kimsey

We determined the bee species presence, abundance, and diversity at utility-scale ground-mounted solar development (USS) to assess the impact on desert pollinators and the services they provide to the plants in the communities in which they live, specifically, in the Mojave and Colorado Desert regions.  We used a matched transect control design to test whether pollinator populations have changed due to solar utility scale installations. Sixty to 90% of flowering plants require animal pollinators. The Mojave Desert represents a hotspot of bee biodiversity corresponding to its rich botanical diversity of 1512 species. Our study found 113 species in a severe drought year after five drought years (2011-2015). 42% were oligoleges, 10% were polylectic and 29% of the  lacked data on their floral diets. Included were 5 undescribed species in the families Apidae (Tetraloniella, Anthophora -Anthophoroides, Anthophorula,) and Halictidae (Lasioglossum [Dialictus]). In our transect study we found lower abundance, diversity and richness inside the solar installations. However, we did not find a significant effect of distance from solar installation at 2K for our one year study. The BVT traps represented 16% of the collected specimens and 58 species and cup traps represented 83% of traps, and captured 46.7% of the total specimens and 66 species.Of the total bees species captured and identified, 76% are ground-nesting species.

How to cite: Saul-Gershenz, L., Zavortink, T., Van Wyk, J., Ascher, J. S., and Kimsey, L.: Impact on native bees from utility-scale solar development in the Mojave and western Sonoran Deserts, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1881, https://doi.org/10.5194/egusphere-egu22-1881, 2022.

EGU22-1993 | Presentations | ERE1.7

Resolving land use conflicts between renewable energy, nature protection and food production 

Gemma Delafield, Brett Day, Greg Smith, and Robert Holland

As countries transition to net zero emissions, the number of land use conflicts between energy generation, nature conservation and food production are expected to rise. Models typically restrict energy deployment from land deemed as providing high societal value (e.g. National Parks, peatland) when exploring future energy pathways to resolve these conflicts. This study applies the spatially explicit ADVENT-NEV model to Great Britain to determine the lower-bound of the implied value being placed on the land excluded. It compares the ‘optimal’ locations for new renewable energy when strict restrictions are applied against those identified when a natural capital approach is used.

When energy development is restricted from Areas of Outstanding Natural Beauty, National Parks and high-grade agricultural land the cost of the energy system is shown to increase by approximately 10%. Even limited bioenergy crop expansion is unfeasible if strict restrictions are applied. In particular, results indicate that such restrictions would not be compatible with net zero emissions targets. These restrictions also result in an increase in the spatial footprint of solar farms, wind farms and bioenergy power stations by up to 13.4%, 79.6% and 15.8% respectively.

Incorporating the valuation of ecosystem services into renewable energy modelling provides a more nuanced approach than a binary exclusion, highlighting how strict restrictions may not always be best for society. The natural capital approach makes trade-offs between energy, nature conservation and food production more explicit for decision-makers allowing them to take a more holistic approach.

How to cite: Delafield, G., Day, B., Smith, G., and Holland, R.: Resolving land use conflicts between renewable energy, nature protection and food production, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1993, https://doi.org/10.5194/egusphere-egu22-1993, 2022.

EGU22-2180 | Presentations | ERE1.7

On-site floral resources and surrounding landscape characteristics impact pollinator biodiversity on solar parks 

Hollie Blaydes, Simon Potts, Duncan Whyatt, and Alona Armstrong

As solar photovoltaic make a greater contribution to the energy mix, there will be increasing land use change for solar parks. Land use change can affect biodiversity across spatial scales and opportunities to incorporate biodiversity benefits into the energy transition are increasingly being recognised. For example, solar parks could support insect pollinators through providing critical resources such as flowering plants. However, understanding of pollinator response to solar park developments is currently limited and empirical data are lacking. To address this knowledge gap, we surveyed bumble bees, butterflies and flowering plants between July and September across 15 solar parks in the UK. We also investigated the composition and connectivity of the landscapes surrounding each solar park using landcover data and a GIS, allowing us to explore the impacts of on-site floral resources and surrounding landscape characteristics on bumble bee and butterfly abundance and diversity. We found that bumble bee and butterfly biodiversity varied across solar parks, but overall butterflies were more than five times more abundant than bumble bees. Pollinator biodiversity was impacted by both on-site resources and landscape characteristics. However, characteristics of the floral resources on site appeared to be the most important factors, with increases in floral diversity, floral cover and vegetation height associated with increases in pollinator abundance and diversity. Our findings suggest that local and landscape scale factors affect pollinator biodiversity on solar parks, but solar parks that provide diverse and abundant flowering plants may be best placed to support pollinators. Incorporating this knowledge into existing and future solar park developments could promote benefits to insect pollinators alongside the energy transition.

How to cite: Blaydes, H., Potts, S., Whyatt, D., and Armstrong, A.: On-site floral resources and surrounding landscape characteristics impact pollinator biodiversity on solar parks, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2180, https://doi.org/10.5194/egusphere-egu22-2180, 2022.

EGU22-4958 | Presentations | ERE1.7 | Highlight

Long Term Ecological Monitoring of Large Scale Solar Parks in the UK 

Hannah Montag and Tom Clarkson

There is currently a total of 750 large scale solar parks (>5MW) in the UK, with an installed capacity of approximately 7.3GW; this is likely to cover an area of land of around 14,500 ha. While the planning process for such developments is currently geared towards increasing biodiversity gain, there remains a large discrepancy between the way that solar farms are managed and the actual ecological enhancement achieved. With large scale solar parks being a critical part of meeting the targets within the Paris Agreement, it becomes increasingly important to understand how the construction of solar parks impacts local wildlife, where biodiversity net gain can be achieved and the obstacles in the way of maximising this biodiversity net gain.

This talk offers a perspective from a practitioner’s point of view; Clarkson & Woods have carried out ecological monitoring of over 100 operational solar farms since 2016, and have collated an extensive database of botanical data from operational solar arrays. We will present this botanical data based on over 2,000 recorded botanical quadrats and look at how various factors affect botanical diversity including land management approach, age of array and location of quadrat. A discussion of some of the obstacles and potential solutions to maximising biodiversity net gain will be presented based on our knowledge of solar farms in the UK.

How to cite: Montag, H. and Clarkson, T.: Long Term Ecological Monitoring of Large Scale Solar Parks in the UK, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4958, https://doi.org/10.5194/egusphere-egu22-4958, 2022.

EGU22-6272 | Presentations | ERE1.7

Floating solar interactions with water bodies under climate warming 

Giles Exley, Trevor Page, Andrew M. Folkard, Stephen J. Thackeray, Rebecca R. Hernandez, and Alona Armstrong

Floating solar photovoltaics (FPV) are deployed on aquatic systems worldwide as an alternative to ground- and roof-mounted installations. FPV installations represent a considerable water surface transformation, and the consequent threats and opportunities for hosting aquatic systems are poorly understood. Moreover, we must consider any impacts within the context of a changing climate, given FPV operational lifetimes.

Impacts on aquatic systems may be significant given that FPV can perturb two key drivers of water body function - wind shear stress and solar radiation intensity. The potential impacts of changes on water body function are wide-ranging. For example, FPV may beneficially reduce the occurrence of nuisance algal blooms or could detrimentally lead to anoxic conditions, leading to the release of heavy metals from bed sediments. However, impacts are likely to be highly water body-specific, dependent on deployment configuration and be contingent on future climate conditions.

To better understand FPV effects on aquatic ecosystem processes, which underpin ecosystem services, we extended an existing lake model to simulate FPV installations under future climate scenarios on a UK reservoir. We examined plausible changes to a range of meteorological variables, water temperatures, reservoir inflow and depth. We found that FPV alters key water quality properties, including water temperature and phytoplankton community composition. Depending on the conditions, the implications are positive or negative. Our analysis shows that FPV can partially mitigate the impacts of climate change by reducing water temperature. The extended lake model will help inform policymakers and practitioners on best practices for deploying FPV, minimising detrimental impacts and maximising co-benefits.

How to cite: Exley, G., Page, T., Folkard, A. M., Thackeray, S. J., Hernandez, R. R., and Armstrong, A.: Floating solar interactions with water bodies under climate warming, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6272, https://doi.org/10.5194/egusphere-egu22-6272, 2022.

EGU22-7770 | Presentations | ERE1.7

Applying Biodiversity Net Gain to solar parks in the UK 

Adèle Remazeilles, Hannah Montag, Fabio Carvalho, Guy Parker, and Belinda Howell

Biodiversity Net Gain (BNG) is defined in the UK as ‘development that leaves biodiversity in a better state than before’ and involves an approach where land developers work with local governments, wildlife groups, landowners and other stakeholders in order to support local priorities for nature conservation. The Environment Act 2021 will set out a minimum 10% biodiversity net gain to be mandatory for most land developments and the gain will need to be calculated using the Natural England Biodiversity Metric. The terrestrial habitats listed within the Biodiversity Metric are based on the UK Habitat Classification system (UK Hab).

Solar park developments usually achieve high gains in biodiversity as they commonly lead to intensive arable land or improved grassland being restored to permanent grassland; further enhancements may include sowing of wildflower seed and application of conservation grazing/cutting. However, debate remains regarding classification of proposed habitat within solar parks, in particular, the shaded habitat beneath the panels. We argue that rather than this area being regarded as “lost” habitat, our data show that a variety of plant species can thrive. However, this varies from site to site and is dependent on the vegetation management regime implemented within the site. Site management varies from conservation grazed to intensively grazed, to completely unmanaged, to cut throughout every month to once every three years or with occasional shade / access strips. This extends to treatment of injurious weeds with some non-chemical treatments to other sites which are blanket sprayed with a glyphosate herbicide.

A data set of 30 operational solar parks which were monitored in 2020 were selected and a total of 523 botanical quadrats analysed in order to characterise the vegetation within solar parks (including beneath the panels) in terms of species composition and other UK Habitat Classification criteria such as habitat condition.

These results will be used to provide formal guidance for calculating BNG on solar farms for the solar industry and planning authorities. The proposed approach is being developed with input from Natural England, UK Hab and Solar Energy UK.

 

How to cite: Remazeilles, A., Montag, H., Carvalho, F., Parker, G., and Howell, B.: Applying Biodiversity Net Gain to solar parks in the UK, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7770, https://doi.org/10.5194/egusphere-egu22-7770, 2022.

EGU22-8685 | Presentations | ERE1.7

Footprint of large scale expansion of wind power in productive boreal forests – forests under a zero-emission strategy 

Wiebke Neumann, Therese Bjärstig, Camilla Thellbro, and Johan Svensson

The increasing demand of emission-free energy enhances the footprint of wind power on landscapes worldwide. Wind power establishments claim considerable areas given their establishment sites and connected infrastructure. Being a major (but late arriving) land-use actor, onshore wind power expands in a landscape context already shaped by other land uses, thereby becoming directly a competitor for area. Being at forefront within the European Union, Sweden in northern Europe has ratified ambitious environmental goals to meet net zero emissions of greenhouse gases by 2045. This asks for substantial expansion in renewable energy sources nationwide, particularly of wind power. In practice, suggested future wind power establishments claim about 3.5% of the total national land surface in Sweden but higher shares in forest-dominated regions. Within the Swedish environmental strategy, forests, however, are key players to provide also other products and services to mitigate impacts of climate change as well as to preserve biodiversity. Notably, a land demand of about 3.5% by wind power is comparable to the share of all formally protected Swedish forestlands below the mountain forest border, which currently is heavily debated due to the experienced loss of forestland for wood biomass production. This makes wind power establishment in forest landscape a serious competitor for space and for meeting different forest goals.

Using Sweden as a case, we quantify the amount of forests in relation to their productivity, landownership (state, company or private) and nature conservation value that we expect to convert into wind power land following the recent national strategy for wind power expansion based on current wind power distribution in Sweden. Our preliminary results suggest a considerable conversion of productive forestland into wind power land, particularly in the southern boreal landscape. Preliminary findings also indicate landowner differ to which degree their productive forestland without conservational value likely become wind power land.  

Our results emphasized the need for regional context-specific landscape planning in order to allow for both forests development and utilization meeting different environmental goals, including wind power and other interests.

How to cite: Neumann, W., Bjärstig, T., Thellbro, C., and Svensson, J.: Footprint of large scale expansion of wind power in productive boreal forests – forests under a zero-emission strategy, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8685, https://doi.org/10.5194/egusphere-egu22-8685, 2022.

EGU22-8855 | Presentations | ERE1.7 | Highlight

Global implications of lignocellulosic crop-based BECCS for terrestrial vertebrate biodiversity 

Steef Hanssen, Zoran Steinmann, Vassilis Daioglou, Mirza Cengic, Detlef van Vuuren, and Mark Huijbregts

Bioenergy with carbon capture and storage (BECCS) based on purpose-grown lignocellulosic crops can provide negative CO2 emissions to mitigate climate change, but its land requirements present a threat to biodiversity. Here, we analyse the implications of crop-based BECCS for global terrestrial vertebrate species richness, considering both the land-use change (LUC) required for BECCS and the climate change prevented by BECCS. LUC impacts are determined using global-equivalent, species-area relationship-based loss factors. We find that sequestering 0.5–5 Gtonne of CO2 per year with lignocellulosic crop-based BECCS would require hundreds of Mha of land, and commit tens of terrestrial vertebrate species to extinction. Species loss per unit of negative emissions decreases with: i) longer lifetimes of BECCS systems, ii) less overall deployment of crop-based BECCS, and iii) optimal land allocation, i.e., prioritising locations with lowest species loss per negative emission potential, rather than minimising overall land use or prioritising locations with lowest biodiversity. The consequences of prevented climate change for biodiversity are based on existing climate response relationships. Our tentative comparison shows that for crop-based BECCS considered over 30 years, LUC impacts on vertebrate species richness may outweigh the positive effects of prevented climate change. Conversely, for BECCS considered over 80 years, the positive effects of climate change mitigation on biodiversity may outweigh the negative effects of LUC. However, both effects and their interaction are highly uncertain and require further understanding, along with analysis of additional species groups and biodiversity metrics. We conclude that factoring in biodiversity means lignocellulosic crop-based BECCS should be used early to achieve the required mitigation over longer time periods, on optimal biomass cultivation locations, and most importantly, as little as possible where conversion of natural land is involved, looking instead to sustainably grown or residual biomass-based feedstocks and alternative strategies for carbon dioxide removal.

How to cite: Hanssen, S., Steinmann, Z., Daioglou, V., Cengic, M., van Vuuren, D., and Huijbregts, M.: Global implications of lignocellulosic crop-based BECCS for terrestrial vertebrate biodiversity, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8855, https://doi.org/10.5194/egusphere-egu22-8855, 2022.

EGU22-10036 | Presentations | ERE1.7

Significant land-sparing potentials from implementing carbon capture and utilization for the Brazilian sugarcane ethanol industry 

Luis Ramirez Camargo, Gabriel Castro, Katharina Gruber, Michael Klingler, Olga Turkovska, Elisabeth Wetterlund, and Johannes Schmidt

Brazil is the global frontrunner in the production of sugarcane ethanol. Strong national biofuels policies, a consolidated internal demand for ethanol for transportation purposes, and a global growing demand for sugar and ethanol have supported this development. The sugarcane ethanol industry has contributed to economic growth, technological progress, job creation and is among the key strategies for mitigating CO2 emissions in Brazil. However, the industry is also responsible for a wide range of undesirable impacts on land. Biodiversity loss, structural soil degradation, pollution, and depletion of water sources can result from the associated direct and indirect land-use change. We therefore assess the potential of a carbon capture and utilization pathway to increase the fuel production of this industry in a land-neutral way. 

The pathway combines the almost clear surplus CO2-stream from the ethanol fermentation process with H2 produced using wind and solar power to synthesize methanol. The change of use of land from sugarcane production to renewable electricity generation is an intensification step which allows to spare significant amounts of land.

To understand the implications of this pathway in terms of land-use and cost, we develop a spatio-temporal model to determine the cost-optimal system configuration, the resulting land effciency, and consequently the land sparing potential. The core of the model consists of a techno-economic optimization model that minimizes cost for a system that includes variable renewable electricity generation (wind and solar power), storage (electricity, CO2 and H2), electrolyzers and methanol synthesis installations for each one of the sugarcane ethanol production plants in the country. The optimization model relies crucially on two time-series which we derived specifically for each Brazilian ethanol plant based on a consolidated spatially explicit data set of sugarcane ethanol installations: first, individual time series of the CO2-streams from ethanol fermentation, and second multi-year time series of wind and solar power in hourly temporal resolution using ERA5 and ERA5-land reanalysis data. Furthermore, we extensively review costs of individual system components and derive footprints of Brazilian solar and wind power plants from satellite imagery.

The proposed pathway leads to a combined amount of ethanol and methanol that represents an increase of  43%-49% compared to the current output of the ethanol industry in energetic terms. This amounts to around 100 TWh of methanol that would be sufficient to cover the projected growth in Brazil biofuel demand until 2030. In contrast, if the same amount of energy would be provided by sugarcane ethanol, produced at the current average Brazilian sugarcane-to-ethanol land-use efficiency, an additional 23,000 km2 - 27,000 km2 of land would be required. This underlines the significant land sparing potential of the proposed pathway. 

How to cite: Ramirez Camargo, L., Castro, G., Gruber, K., Klingler, M., Turkovska, O., Wetterlund, E., and Schmidt, J.: Significant land-sparing potentials from implementing carbon capture and utilization for the Brazilian sugarcane ethanol industry, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10036, https://doi.org/10.5194/egusphere-egu22-10036, 2022.

EGU22-343 | Presentations | ERE1.8

Geotourism assessment of the northwestern part of the Gerecse Mountains, Hungary 

Edina Hajdú, Gáspár Albert, and Márton Pál

Geotourism is a relatively new sector in tourism, in which visitors are offered earth scientific knowledge when visiting spectacular locations (geosites or geotopes) and participating in various organized activities there. Areas and sites with high geological-geomorphological relevance are usually managed by national parks, geoparks or other types of nature reserves. For this reason, research into the assessment of these sites serves not only the purposes of geoscience but also those of these organisations and, through them, tourism.

The aim of our research was to carry out a quantitative geotourism assessment in the NW part of the Gerecse Mts, Hungary, on an area of 180 km2. As this type of assessment determining geotourism potential has not been made here before, the Gerecse Mountains are still undiscovered in terms of quantitative geotourism values. However, this area has great geodiversity due to its earth scientific richness (its various and spectacular geosites are mainly from the Mesozoic, but Eocene, Miocene and Quaternary sediments are also present). It has strong connections to culture and human activities: it is an important source of building stones since Roman times.

We used analogue geological and topographic maps, publications, and databases to identify potential geosites. The selected sites were ranked based on their types (e.g., cliff, quarry, break of slope) and distance from trails. They were visited on site – omitting the least important ones based on the preliminary categorization. Following the fieldwork, the potential geosites were evaluated based on quantitative assessment models that have been used in Hungary several times. We applied the Geosite Assessment Model (GAM, Vujičić et al., 2011) and the Modified Geosite Assessment Model (M-GAM, Tomič & Božić, 2014). Among objective aspects, the latter involves tourists (from other studies) into the evaluation process, thus giving a more realistic image of the geotourism potential of the given geosite. The final score of an object is built up by scientific, infrastructural and this visitor-based values. In the end of the work, each geosite got an analysis on its improvable characteristics, and a group of them were selected as suitable for later geotourism activities and development.

The results (more than 100 evaluated geotopes) contribute to the geosite cadastral of the Gerecse Mts – providing useful data for the management body – the Duna-Ipoly National Park Diretorate. Suitable protection and tourism activity measures of local earth science values can be planned using our results – these two factors are the base of a good balance between nature and society.

EH is supported by the ÚNKP-21-2 New National Excellence Program of the Ministry for Innovation and Technology from the source of the National Research, Development and Innovation Fund.

 

Tomić, N., & Božić, S. (2014). A modified Geosite Assessment Model (M-GAM) and its Application on the Lazar Canyon area (Serbia). International Journal of Environmental Research, 8(4), 1041-1052.

Vujičić, M., Vasiljević, D., Marković, S., Hose, T., Lukić, T., Hadžić, O., & Janićević, S. (2011). Preliminary geosite assessment model (GAM) and its application on Fruška Gora Mountain, potential geotourism destination of Serbia. Acta Geographica Slovenica, 51(2), 361-377.

How to cite: Hajdú, E., Albert, G., and Pál, M.: Geotourism assessment of the northwestern part of the Gerecse Mountains, Hungary, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-343, https://doi.org/10.5194/egusphere-egu22-343, 2022.

Accurate mapping of forest aboveground biomass (AGB) is critical for carbon budget accounting, sustainable forest management as well as for understanding the role of forest ecosystem in the climate change mitigation.

In this study, spaceborne Global Ecosystem Dynamics Investigation (GEDI) LiDAR data were used in combination with Sentinel-1 synthetic-aperture radar (SAR) and Sentinel-2 multispectral imagery as well as elevation data to produce a wall-to-wall AGB map of Australia that is more accurate and with higher spatial and temporal resolution than what is possible with any one data source alone. Specifically, the AGB density map was produced that covers the whole extent of Australia at 200m spatial resolution for the Austral winter (June-August) of 2020. To produce this map Copernicus Sentinel-1 and Sentinel-2 composites and ALOS World 3D Digital Surface Model (DSM) were trained with samples from the GEDI Level 4A product.

From GEDI Level 4A data available within Australia between June – August 2020, all measurements not meeting the requirements of L4A product quality, and those with degraded state of pointing or positioning information and an estimated relative standard error in GEDI-derived AGB exceeding 50% were rejected. Mean Sentinel-1 composite was generated using thermal noise corrected, radiometrically calibrated and terrain corrected VV- and VH-polarization backscatter imagery. Similarly, median Sentinel-2 composite was generated using cloud and cloud-shadow free Level-2A imagery, and was further used to calculate Normalized Difference Spectral Indices (NDSIs) from all spectral bands. Finally, aspect and slope were calculated from the DSM.

The boosting tree machine learning model was applied to predict wall-to-wall AGB density map. For each 200m × 200m cell the number of available GEDI measurements was calculated and models were built based on average AGB density of cells containing > 5 GEDI measurements.

Up to ≈62000 cells, each 200m × 200m, were used to train predictive machine learning models of AGB density. The predictive performance of models based on Sentinel-2 imagery only (single-data source) and a fusion of Sentinel-2 with Sentinel-1 imagery and elevation data (multi-data source) was compared. Bayesian hyperparameter optimization was used to identify the most accurate Light Gradient Boosting Machine (LightGBM) model using 5-fold cross-validation. 

The single-data source analysis based on Sentinel-2 imagery resulted in AGB density predicted with the coefficient of determination (R2) of 0.74-0.81, root-mean-square error (RMSE) of 40-44 Mg/ha and root-mean-square percentage error (RMSPE) of 45-55%.Model performance improved only marginally with the addition of Sentinel-1 and DSM information: AGB density prediction with R2 of 0.75-0.82, RMSE of 36-41 Mg/ha and RMSPE of 44-48%. Using a SHapley Additive exPlanations (SHAP) approach to explain the output of LightGBM models it was found that Sentinel-2 derived NDSIs using Red Edge and Short-wave Infrared bands were the most important in predicting seasonal AGB density. 

Similar model performance is expected for annual prediction of AGB density at a finer resolution (e.g. 100m) due to higher density of GEDI measurements. This research highlights methodological opportunities for combining GEDI measurements with satellite imagery and other environmental data toward seasonal AGB mapping at the regional scale through data fusion.

How to cite: Shendryk, Y.: Fusing GEDI, Sentinel-1, Sentinel-2, and elevation data for seasonal forest biomass mapping across Australia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2077, https://doi.org/10.5194/egusphere-egu22-2077, 2022.

EGU22-2484 | Presentations | ERE1.8

Update on soil carbon balance in Hungarian crop rotation systems 

Giulia De Luca, Krisztina Pintér, Szilvia Fóti, Zoltán Nagy, and János Balogh

Long term flux measurements are needed to improve our understanding of the carbon balance of arable lands. The objective of our study was to determine the seasonal dynamics of carbon cycling in a Hungarian cropland and to examine the effect of crop rotation on net ecosystem exchange of CO2 (NEE), furthermore to assess the influences of C outputs and inputs derived from lateral fluxes on soil organic carbon (SOC) stock. In this study we update the results presented in our poster of last year’s conference (EGU21-10977).

The experiment began in 2017 and crop rotation of the measured field consisted of winter wheat (2017-2018 and 2019-2020), rapeseed (2018), sorghum (2019) and sunflower (2021). CO2 fluxes and annual net ecosystem exchange (NEE) of CO2 were measured by a field-scale eddy covariance (EC) station at a Central Hungarian cropland site. Both vertical and lateral C fluxes were taken into account when calculating the net ecosystem carbon budget (NECB).

As presented in our previous study the largest sink activity was observed in the sorghum season (-277 g C m-2 from sowing to harvest). The cropland acted as a source of CO2 during the rapeseed season (140 g C m-2) due to incomplete germination caused by extreme autumnal drought.

We found that during the study period both meteorological variables and lateral carbon fluxes such as C inputs derived from seed and crop residues and outputs (harvest) had significant influence on the C dynamics. The higher temperatures and precipitation amount that characterised the fall of 2019 caused large differences in NEE dynamics for winter wheat when compared to 2017. The impact of climatic factors could be seen in the sunflower period since lack of precipitation in 2021 led to remarkably low carbon uptake.

Fallow periods in total covered a relatively long period of time (approximately 1 year out of the 4 year long study period). These fallow periods had a significant effect on NECB values due to immense C loss. During the four years of our experiment cumulative NEE was -222 g C m-2 and NECB was 726 g C m-2 as carbon loss during fallow periods (437 g C m-2 in total) and carbon export through harvest (964 g C m-2 in total) counterbalanced the crop’s CO2 uptake.

We can conclude that while this Hungarian cropland was a sink of carbon it could not maintain the soil organic carbon content as it was not able to sequester enough carbon to do so. Cover plants and crop residue retention could be a solution to reduce the risk of soil carbon stock depletion but further studies are needed in the field of soil management practices.

How to cite: De Luca, G., Pintér, K., Fóti, S., Nagy, Z., and Balogh, J.: Update on soil carbon balance in Hungarian crop rotation systems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2484, https://doi.org/10.5194/egusphere-egu22-2484, 2022.

EGU22-3398 | Presentations | ERE1.8

A Study on the Selection of Biodiversity Offset Area in Korea - Focusing on Jeju Island 

Dayong Jeong, Seungyeon Lee, Yujin Shin, and Seongwoo Jeon

Jeju island’s unique and diverse species of flora and fauna and well-preserved natural environment earned Jeju the designation as a UNESCO Biosphere Reserve in December 2002(World Heritage Office & Jeju Special Self-Governing Province, 2016). To achieve no net loss and preferably a net gain of this outstanding biodiversity, ‘biodiversity offsets’ can be implemented(BBOP, 2009). Until now, there have been attempts in Korea to introduce the concept of offset, such as the establishment of the ‘Total Natural Resource Conservation’(Lee et al., 2020), but studies on the specific criteria or method of biodiversity offset area are insufficient. It is desirable not to prepare offset area whenever damage occurs, but to select them in consideration of ecological connectivity, environmental functional aspects, and socio-cultural continuity in the planning process(Lee et al., 2020). Therefore, we intend to select the offset area of Jeju Island using the methodology of Pilgrim et al (2012), which derives the relative offsetability in consideration of the biodiversity conservation concern, residual impact magnitude, theoretical offset opportunity, practical offset feasibility. Potential offset area derived from previous studies has already reflected the concept of biodiversity conservation concern, including vulnerability and irreplaceability. Through the Environmental Impact Assessment(EIA) of Jeju Island, the type of development that had a significant impact on biodiversity is selected as an example, and the impact magnitude of the development type is identified. In addition, offset opportunity is derived by considering functional area and natural distribution, and offset feasibility is derived by factors such as developer capacity and financing. Finally, the relative offsetability is evaluated and the offsetability map is established. The characteristics of offset areas are analyzed using the established offsetability map. For instance, the size and patterns of sites with high offsetability can be studied. As a result, the offsetability map is established by evaluating the relative offsetability of potential offset areas. Therefore, it is possible to specifically find where the biodiversity offset is available in Jeju Island, and to identify the offset priority through comparison of the relative offsetability between the selected offset sites. By analyzing the characteristics of the offset area, it is possible to identify what characteristics increase the offsetability, how large it should be to have high offsetability, and what patterns exist between the selected offset areas. This study shows the specific offset area selection process, and through this, it will help to create a roadmap for selecting a site for a biodiversity offset where the biodiversity offset concept was not introduced into the policy. This work was supported by the Korea Environment Industry and Technology Institute (KEITI) through the Decision Support System Development Project for Environmental Impact Assessment, funded by the Korea Ministry of Environment (MOE) (No. 2020002990009). This work was Supported by a Korea University Grant.

How to cite: Jeong, D., Lee, S., Shin, Y., and Jeon, S.: A Study on the Selection of Biodiversity Offset Area in Korea - Focusing on Jeju Island, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3398, https://doi.org/10.5194/egusphere-egu22-3398, 2022.

EGU22-3421 | Presentations | ERE1.8

Mapping the Biodiversity Conservation Value for Potential Offset Area 

Yu Jin Shin, Seungyeon Lee, Dayong Jeong, and Seongwoo Jeon

Jeju Island, the research area, has been registered as a UNESCO World Natural Heritage Site and has high biodiversity and ecological value, such as designation as a global geopark and biosphere reserve. It also has a beautiful landscape, so it is not only necessary for conservation but also highly demanded as a landscape resource (Kim et al., 2015; Ko, 2011). Accordingly, it is necessary to prioritize the conservation area that can reconcile the conflict between indiscriminate development and nature protection, as well as to establish potential offset sites for ‘No Net Loss’ in order to respond to development impacts. Selecting conservation areas based on biodiversity value can be an effective offset decision-making tool on where and how to prioritize conservation policies (Li et al., 2021; SANBI & UNEP-WCMC, 2016). There have been many studies on biodiversity conservation between excellent ecological value and development pressure in Jeju Island, but there are almost no studies on the implementation conditions of the offset or offset sites. We here aim to map a conservation area map in consideration of the environmental characteristics of Jeju Island and to select a potential offset area that can practically work offset. We will use ‘Zonation’ program, which is a systematic conservation planning-based model. Zonation is a useful land planning tool that can minimize development impact and realize biodiversity offset (Wintle, 2008; Lethomaki & Moilanen, 2013). The biodiversity attributes inputs required for running Zonation are potential habitat data using MaxEnt and environmental variable data. As a result, we will identify the spatial range and location of the potential biodiversity offset area through Zonation Priority Rank Map output. In addition, we can also analyze their spatial and environmental characteristics, and group out the shape of potential offset site composition (size or pattern). This study can be utilized as a basis for feasible offset policy by proposing potential offset areas through selecting conservation areas in Jeju Island. This work was conducted with the support of the Korea Environment Industry & Technology Institute (KEITI) through its Urban Ecological Health Promotion Technology Development Project, and funded by the Korea Ministry of Environment (MOE) (2020002770003).

How to cite: Shin, Y. J., Lee, S., Jeong, D., and Jeon, S.: Mapping the Biodiversity Conservation Value for Potential Offset Area, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3421, https://doi.org/10.5194/egusphere-egu22-3421, 2022.

EGU22-3656 | Presentations | ERE1.8

Comparing the spatio-temporal differences of global NPP simulation data with different resolutions 

Tao Zhou, Xiaolu Tang, Yuting Hou, Xinrui Luo, Zhihan Yang, Yunsen Lai, Peng Yu, Ke Luo, and Runying Zhao

*Corresponding author: Xiaolu Tang (lxtt2010@163.com)

Net primary productivity (NPP) is a key parameter to characterize terrestrial ecological processes. NPP reflects the carbon sequestration capacity of vegetation to absorb atmospheric carbon dioxide, and plays an important role in mitigating atmospheric carbon dioxide content. Currently, the majority of studies focused on the model efficiency total NPP at the global scale. However, whether the model resolution of NPP affects the NPP amount at the global is still uncertainty. To fill this knowledge gap, we first collected 3307 NPP field observations from published literatures, and then model NPP using climate, soil, and vegetation variables using Random Forest (RF) to predicted global NPP at the spatial resolutions of 0.05°, 0.25° and 0.5°. Results showed that RF could well capture the spatial and temporal variability of NPP with the model efficiencies (R2) of 0.55, 0.52 and 0.53 for at the resolution of 0.05°, 0.25° and 0.5°, respectively. Similar spatial patterns were also found for NPP at different spatial resolutions and NPP decreased with increased latitude where the highest NPP was found in the tropical regions and the lowest NPP were distributed in high latitude areas, e.g. alpine tundra. However, a great difference was found for the magnitude of NPP resulting a great difference in total global NPP of 71.5, 78.6, 87.7 Pg C year-1 from 1981 to 2016 for the resolutions of 0.05°, 0.25° and 0.5°, respectively. These findings suggested the challenges to improve modelling accuracies of the global carbon fluxes used appropriate resolutions.

Keywords: Net primary productivity; Different resolutions; Random Forest; Spatial pattern; Appropriate resolution;

Acknowledgment: the study was supported by the National Science Foundation of China (31800365).

How to cite: Zhou, T., Tang, X., Hou, Y., Luo, X., Yang, Z., Lai, Y., Yu, P., Luo, K., and Zhao, R.: Comparing the spatio-temporal differences of global NPP simulation data with different resolutions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3656, https://doi.org/10.5194/egusphere-egu22-3656, 2022.

EGU22-4378 * | Presentations | ERE1.8 | Highlight

From SDGs to IDGs: Translating global Sustainable Development Goals for water, food and energy to river basin specific Indus Development Goals 

Arthur Lutz, Wouter Smolenaars, Sanita Dhaubanjar, Khalid Jamil, Hester Biemans, Fulco Ludwig, and Walter Immerzeel

The UN Sustainable Development Goals (SDGs) are a powerful concept to drive action towards a more sustainable future. However, the SDGs are formulated in a qualitative and generic way whereas specific and quantitative definitions of targets are required to steer policy and practice.

The Indus river basin is a global hotspot for future climate change and socioeconomic development. The basin has the largest continuous irrigation scheme in the world, and hydropower is developing rapidly with a large hydropower potential still untapped. Therefore, water, food and energy are strongly interlinked in the basin’s water-food-energy nexus. The basin already faces insecurity of water, food and energy in the present situation, and with strong projected climate and socioeconomic change, achieving the SDGs for these three resources in the basin will be challenging.

Here we present a novel approach to translate the global SDGs for water, food and energy (SDGs 2, 6 and 7) to quantitative targets specified for the Indus river basin. Our approach is based on a resource accounting framework operating at sub-basin scale and monthly time step, combining models and geospatial data. The approach uses ensembles of downscaled projections for three climate change scenarios driving water availability and three sets of downscaled projections of socioeconomic drivers, including population and GDP, as main drivers for the demand for water, food and energy. The accounting framework considers dependencies between the three resources and represents scenario-specific exchange of resources between sub-basins in this transboundary river basin. The approach results in scenario-specific quantitative targets for water, food and energy to be realized to achieve the three related SDGs at the river basin scale.

How to cite: Lutz, A., Smolenaars, W., Dhaubanjar, S., Jamil, K., Biemans, H., Ludwig, F., and Immerzeel, W.: From SDGs to IDGs: Translating global Sustainable Development Goals for water, food and energy to river basin specific Indus Development Goals, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4378, https://doi.org/10.5194/egusphere-egu22-4378, 2022.

EGU22-5400 | Presentations | ERE1.8

openghgmap.net -  Estimating CO2 Emissions for 108,000 European Cities 

Daniel Moran, Peter-Paul Pichler, Heran Zheng, Helene Muri, Jan Klenner, Diogo Kramel, Johannes Többen, Helga Weisz, Thomas Wiedmann, Annemie Wykmans, Anders Hammer Strømman, and Kevin R. Gurney

City-level CO2 emissions inventories are foundational for supporting the EU’s decarbonization goals. Inventories are essential for priority setting and for estimating impacts from the decarbonization transition. Here we present a new CO2 emissions inventory for all 116,572 municipal and local government units in Europe, containing 108,000 cities at the smallest scale used. The inventory spatially disaggregates the national reported emissions, using 9 spatialization methods to distribute the 167 line items detailed in the National Inventory Reports (NIRs) using the UNFCCC Common Reporting Framework (CRF). The novel contribution of this model is that results are provided per administrative jurisdiction at multiple administrative levels, following the region boundaries defined OpenStreetMap, using a new spatialization approach. Project website: openghgmap.net

How to cite: Moran, D., Pichler, P.-P., Zheng, H., Muri, H., Klenner, J., Kramel, D., Többen, J., Weisz, H., Wiedmann, T., Wykmans, A., Strømman, A. H., and Gurney, K. R.: openghgmap.net -  Estimating CO2 Emissions for 108,000 European Cities, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5400, https://doi.org/10.5194/egusphere-egu22-5400, 2022.

EGU22-6287 | Presentations | ERE1.8

A global assessment of spatiotemporal uncertainties in Land Cover – a key indicator for monitoring sustainable development 

caterina barrasso, ruben remelgado, and carsten meyer

Land cover (LC) is an important indicator to reach several of the targets under the Global Goals. Accurate global LC time-series are thus vital to monitor sustainable development. Although the number and quality of open-access, remotely sensed LC products is increasing, all products have uncertainties due to widespread classification errors. However, the relative magnitude of uncertainties among exiting LC products is largely unknown, which hampers their confident selection and robust use for sustainable development evaluation and planning. To close this gap, we quantified region-, time-period-, and coarse-LC class-specific data uncertainties for the 10 most widely used global LC time-series. To this end, we developed a novel multi-scale validation framework that accounts for differences in mapping resolutions and scale mismatches between the spatial extent of map grid cells and validation samples. We aimed for a fair validation assessment by carefully evaluating the quality of our validation samples with respect to landscape heterogeneity that LC products often fail to classify accurately. To address the issue, we supported the validation assessment with Landsat-based measures of cross-scale spectra similarity. The metric was computed by taking advantage of the full Landsat archive in Google Earth Engine. We base our assessment on more than 1.8 million globally integrated LC validation sites, where we mobilized around 2.8 million samples during the period 1980-2020 composed by hundreds of sampling effort of varied nature, from field surveys to crowdsourcing campaigns. Here, we will present the results of the assessment, providing insights on global and regional patterns of LC uncertainties. We found that no single product is more accurate over the others in mapping all LC classes, regions and time-periods. We will provide recommendations on the selection of fit-for-purpose LC time-series, and discuss future strategies for addressing their uncertainties in sustainable development evaluation and planning.

How to cite: barrasso, C., remelgado, R., and meyer, C.: A global assessment of spatiotemporal uncertainties in Land Cover – a key indicator for monitoring sustainable development, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6287, https://doi.org/10.5194/egusphere-egu22-6287, 2022.

Abstract

Sweden aims to achieve net zero GHG emissions by 2045. To do this, one strategy could be increasing the biomass contribution in energy sector as approximately 75% of total greenhouse gas (GHG) emissions are related to energy consumption. Therefore, it is beneficial to explore efficient ways to upgrade biomass materials into high value-added bioenergy. This study considers the potential of Miscanthus cultivation and its application as biofuel materials in Sweden in terms of carbon sequestration and contribution in climate impact mitigation. Miscanthus, as an energy crop with relatively low maintenance requirements and a high dry matter yield and energy content, can play a major role in the sustainable development of biofuels. Using Miscanthus for energy, results in avoiding fossil fuel combustion and the corresponding GHG emissions. The results of this assessment demonstrated that the Miscanthus cultivation contributes in soil organic carbon sequestration by over one tonne carbon ha−1 yr−1 which results in mitigating a significant amount of soil CO2 fluxes. Therefore, the adaption of Miscanthus biomass, would directly contribute in UN Goal 7, affordable and clean energy, and Goal 13, climate action due to a significant reduction in GHG emissions. The integration of Miscanthus plant into the landscape may stimulate the economy of rural areas in the country and offer more profit than afforestation and reforestation on abandoned and marginal croplands.

Keywords: Energy crops, Climate change, Bioenergy, Soil organic carbon, Ecosystem services

How to cite: Mohammadi, A.: Carbon sequestration potential of Miscanthus application as biofuel source in Sweden, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6413, https://doi.org/10.5194/egusphere-egu22-6413, 2022.

The topography of Sichuan Province is extremely complex, with a rich variety of vegetation, and its vegetation shows a clear horizontal and vertical distribution structure. The subtropical evergreen broad-leaved forest is the zonal vegetation of Sichuan. In 1980, according to the field survey data, forestry scientists roughly divided the evergreen broad-leaved forest in Sichuan Province into Erlang Mountain, Daxiangling Mountain, Xiaoliang Mountain or Huangmaogeng. It was divided into a dry evergreen broad-leaved forest in the west and a moist evergreen broad-leaved forest in the east. However, there is no quantitative classification of wet and dry evergreen broad-leaved forests in Sichuan. The traditional forest vegetation survey mainly relies on manual field survey, which has a long period, high cost, and consumes a lot of manpower and material resources. Remote sensing technology, with its wide coverage, large amount of information and short update cycle, brings the possibility of rapid and accurate quantitative classification of wet and dry evergreen broad-leaved forests. In this paper, based on the field survey data of evergreen broad-leaved forests in Sichuan Province, we combined NASADEM_HGT elevation data and Landsat8 images to perform SCS+C topographic correction on remote sensing images of the whole region of Sichuan on the Google earth engine cloud computing platform, and also based on the differences in spectral, textural and temporal characteristics between dry and wet evergreen broad-leaved forests. The experimental results were compared with the field survey data and obtained excellent accuracy, and it provides a strong technical support for vegetation mapping and forestry resources investigation and monitoring, and also lays a certain foundation for the classification of complex mountain forest vegetation.

 

How to cite: zhang, S.: The division of dry and wet areas of evergreen broad-leaved forest in Sichuan Province, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7143, https://doi.org/10.5194/egusphere-egu22-7143, 2022.

EGU22-7343 | Presentations | ERE1.8

Conceptualising the management of climate extreme events through the GIS-based digital twin system 

Khurram Riaz, Marion McAfee, Iulia Anton, and Salem Gharbia

Climate change has been recognised for decades, and environmental risks related to it are expected to become more common over time as the world's population continues to grow. This tendency is compounded by people congregating in areas such as coastal regions, which are becoming increasingly vulnerable due to climate change. It is demonstrated that overpopulated regions need robust early warning systems representing the region's complex systems to allow all stakeholders to receive the correct information and respond appropriately and quickly under extreme climate events to avoid losing lives and property. The concept of a 'digital twin' is proposed as an accurate virtual representation of the effect of climate events on a specific region, which can be used as a tool to achieve better resilience of cities against extreme events. A digital twin can be created by combining data from various IoT sensors and artificial intelligence with a city model to represent a digital replica of the actual world. This paper presents an up-to-date picture of the GIS-based digital twin technology developed in the last decade for the early warning of extreme climate events worldwide and their integration with the smart city management systems. The findings suggest that GIS-based digital twin technology for severe climate hazard early warning is an emerging method. Yet, it has gained prominence in recent years due to developments in technology, software development, and communication technologies. However, much more research on digital twins is necessary to create a more effective early warning system approach. This paper highlights a potential framework for the development, implementation, and application of GIS-Based digital twins in climate resilience management in coastal regions.

How to cite: Riaz, K., McAfee, M., Anton, I., and Gharbia, S.: Conceptualising the management of climate extreme events through the GIS-based digital twin system, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7343, https://doi.org/10.5194/egusphere-egu22-7343, 2022.

EGU22-9721 | Presentations | ERE1.8

Modeling Aboveground Biomass and carbon sequestration at local and national scale with in-situ and remote sensing data 

Luca Foresta, Sake Alkema, Niels Anders, Rens Masselink, Vincent Schut, Sacha Takacs, and Arjen Vrielink

Monitoring carbon release and sequestration is now more important than ever. Not only to confirm that carbon sinks remain intact or vulnerable ecosystems do not further degrade, but also to keep track of our journey towards carbon neutrality, where increasing efforts to offset CO2 emissions have been initiated. Amongst a number of solutions, carbon trading schemes have been introduced, such as the EU Emission Trading System that is used in programs where local smallholder farmers benefit from transitioning towards agroforestry. Critical to the success of such programs is the use of accurate, scalable and transparent remote sensing technologies that objectively monitor the carbon that trees in a given plot of land have removed from the atmosphere.

At Satelligence, we exploit radar and optical satellite data worldwide and at scale to empower clients to combat deforestation and decrease carbon losses, as well as to protect biodiversity and prevent land degradation. In this contribution, we will present our approach to model Aboveground Biomass (AGB) over tropical moist forests at (sub) national scale based on data from several Earth Observation missions (GEDI, Sentinel-1, Sentinel-2, Landsat) and machine learning models. In-situ data, where available, are integrated to improve models at local and regional scales. We will show preliminary results of modeled AGB and carbon sequestration over large areas as well as individual agricultural plots for selected countries in Africa and South America.

How to cite: Foresta, L., Alkema, S., Anders, N., Masselink, R., Schut, V., Takacs, S., and Vrielink, A.: Modeling Aboveground Biomass and carbon sequestration at local and national scale with in-situ and remote sensing data, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9721, https://doi.org/10.5194/egusphere-egu22-9721, 2022.

EGU22-11084 | Presentations | ERE1.8

Terrestrial net primary productivity dynamics under climatic variability and urban expansion in western Himalaya 

Sonali Sharma, Pawan Kumar Joshi, and Christine Fürst

The western Himalaya is one of the most climate-sensitive and ecologically vulnerable ecosystems of the world. In the recent past, the region has undergone rapid alterations owing to climate change and paced urbanization. These alterations have significantly impacted Terrestrial Net Primary Productivity (TNPP) of the region. The present study takes the emerging urbanizing centers: Pithoragarh (Uttarakhand) and Dharamsala (Himachal Pradesh), situated in Indian western Himalaya to estimate TNPP dynamics of various land use classes. The study demonstrates usage of Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model (ESTARFM) for predicting a high spatio-temporal Normalised Difference Vegetation Index (NDVI) imagery obtained by fusing spatial details of Landsat NDVI and temporal details of Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI images. The predicted NDVI showed a good agreement with actual Landsat NDVI (R2=0.64 and 0.89; RMSE: 0.09 and 0.04; p < 0.01 for Dharamsala and Pithoragarh, respectively), therefore was reliable for TNPP estimations. This was assimilated in Carnegie Ames Stanford Approach (CASA) model for TNPP estimation for the years 2001 to 2019. The preliminary results show a net loss in TNPP in both of the urbanizing centers. During the study period 2001-2019, TNPP fluctuated annually and showed a decreasing trend of 1475.77 g C m-2 year-1 and 790.84 g C m-2 year-1 in Dharamsala and Pithoragarh, respectively. Among the forest vegetation classes, Oak the most dominant forest class experienced the highest decline in TNPP accounting for 67.55% and 34.04% of net TNPP loss in Dharamsala and Pithoragarh, respectively. The urban expansion contributed to 14.77% (Dharamsala) and 9.77% (Pithoragarh) decline of net TNPP loss. The results provide a better understanding of spatio-temporal dynamics of TNPP consequent to climatic variability and urbanization and provide a theoretical reference for future urban planning.

How to cite: Sharma, S., Joshi, P. K., and Fürst, C.: Terrestrial net primary productivity dynamics under climatic variability and urban expansion in western Himalaya, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11084, https://doi.org/10.5194/egusphere-egu22-11084, 2022.

EGU22-11923 | Presentations | ERE1.8

A multiscale approach for discovery of illegal micro-dumps based on satellite detections 

Donato Amitrano, Cesario Vincenzo Angelino, Luca Cicala, Francesco Gargiulo, Gabriella Gigante, Francesco Nebula, Roberto Palumbo, Sara Parrilli, Domenico Pascarella, Gianpaolo Pigliasco, and Francesco Tufano

Satellite remote sensing allows for large scale monitoring with low cost and high revisit time. However, in some applications, it does not provide all the information needed by the analyst for the full characterization of the problem due to, as an example, insufficient resolution or lack of specific measurements. This can lead to inaccuracies in classification and/or detection tasks. Nevertheless, satellite data can be used to guide subsequent discovery, recognition and characterization actions, defining potential areas of interest of limited extension that can be furtherly investigated with on-site strategies. This work presents an innovative framework showing how to use incomplete and inaccurate information extracted by satellite images in order to address on-ground discovery actions aimed to the mapping and the characterization of illegal micro-dumps in Campania Region (Italy). In particular, high-resolution images up to 50 cm resolution are exploited to detect potential micro-dumps by means of a statistical learning method based on spatial features. The detection map is then used to create a priority map based on environmental risk considerations, such as the extension of the area interested by the dump and its proximity to urban settlements, and previous risk mitigation actions. This information is ingested by a planning system in order to allocate and calculate patrolling routes based on the available manpower and vehicles for on-site surveying. The survey is implemented by means of drones equipped with payloads and software allowing for real-time three-dimensional reconstruction of the scene and volumetric estimations. This provides further data to assess the real dangerousness of the site giving to decision makers essential information to plan remediation actions. The system is demonstrated through a case study showing all the stages of the decision process.

How to cite: Amitrano, D., Angelino, C. V., Cicala, L., Gargiulo, F., Gigante, G., Nebula, F., Palumbo, R., Parrilli, S., Pascarella, D., Pigliasco, G., and Tufano, F.: A multiscale approach for discovery of illegal micro-dumps based on satellite detections, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11923, https://doi.org/10.5194/egusphere-egu22-11923, 2022.

Energy has been identified as an enabler for several of the Sustainable Development Goals (SDGs). Globally, 759 million people (2019) still lack access to electricity. Energy planning is important to describe the pathway to achieve the nations goals, where energy systems models are important tools to explore scenarios and provide insight. Until recently, modelling energy access with low electrification rate was conducted either at low spatial (e.g. national) or temporal resolution (e.g. annual time slices).  The central grid is often modelled as a black box with approximate optimization methods. This is recognised as unsuitable for understanding integration of technological alternatives to a centralised grid, including distributed generation and mini-grids/renewables. However, methods to model national energy systems at very high spatial and temporal resolutions are data and computation intensive. At the same time increased transparency on the data and code behind these models and insight is important as energy infrastructure is both capital intensive and strategic for the nation.

In this paper we investigate the use of OSeMOSYS, an open-source energy systems model, and increase the spatial resolution while keeping a medium time resolution. OSeMOSYS is a linear programming model and conveniently finds the global optimum in contrast to approximate methods. The approach provides insights into the trade-offs across supply and demand. The model generation is available in an open-source repository where results can be reproduced.

For this paper we use Kenya as our case study where still 16 million people lack access to electricity (2019). We select the spatial resolution to 378 supply cells (40x40km square cells) which leads to 591 demand cells split between electrified and un-electrified. The modelled number of seasons are 12 and the day is split into 3 slices: day, evening, and night, leading to 36 time slices. Specific demand profiles for electrified and un-electrified are assessed in combination with location specific supply options (expansion from the grid, PV, wind, diesel gensets).

Our preliminary results show that the varying un-electrified demand profile, with a high evening peak and low night-time demand, hybrid solutions are preferred with more than one supply option to meet the demand. The expansion of the grid to cells located far away is not motivated due to the low expected consumption, therefore decentralized supply options are required to serve at a high service level.

The results highlight the need for further work to investigate the sensitivity of the spatial and temporal resolutions in combine in energy systems optimization models.

How to cite: Moksnes, N., Howells, M., and Usher, W.: Increasing spatial and temporal resolution in energy system optimization model for energy access – the case of Kenya, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12071, https://doi.org/10.5194/egusphere-egu22-12071, 2022.

EGU22-12177 | Presentations | ERE1.8

SOMERS: Monitoring greenhouse gas emission from the Dutch peatland meadows on parcel level 

Gilles Erkens, Roel Melman, Siem Jansen, Jim Boonman, Ype van der Velde, Mariet Hefting, Joost Keuskamp, Merit van den Berg, Jan van den Akker, Christian Fritz, Huite Bootsma, Ralf Aben, Rudi Hessel, Ronald Hutjes, Sanneke van Asselen, Sarah Faye Harpenslager, Bart Kruijt, and Nobv consortium

Following the Paris Agreement (2015) that aims to limit climate warming, the Dutch government presented a National Climate Agreement in 2019. This agreement stated the overall ambition of reducing the national greenhouse gas emission by 49% in 2030 (compared to 1990) and allocates this reduction target to different sectors, such as industry, mobility, agriculture or land use. Within the latter sector, the peatland meadows are currently estimated to contribute ~4.6 to 7 Mton per year of CO2 to the national Dutch greenhouse gas emission. In the National Climate Agreement, the aim is to reduce the net CO2 emission from the peatland meadows with 1 Mton per year by 2030. 

To comply with the greenhouse gas emission reduction targets for peatlands, a set of measures that raise groundwater levels are currently being proposed and tested in pilots. The Dutch National Research Programme on Greenhouse Gas Emissions from Peat Meadows (NOBV) investigates the effects of the proposed measures on the greenhouse gas emission balance under different environmental conditions. In the National Climate Agreement, it was decided that annual progress made in reducing greenhouse gas emissions needs to be monitored. The NOBV consortium is developing a registration system for this monitoring and presents it current status and ideas for future development in this contribution.

The registration system SOMERS (Subsurface Organic Matter Emission Registration System) is based on a multi-model ensemble approach. Using numerical models that simulate groundwater and carbon dynamics, the CO2 emission as a result of peat decomposition is calculated. Within SOMERS, existing models are supplemented by two newly developed models for assessing groundwater dynamics and peat decomposition, that require limited data input and have a short runtime. The new models simulate at parcel resolution and together are used to make a multi-model ensemble estimate of annual, national peatland greenhouse gas emissions since 2016 (the reference year). The new models are tested with annual carbon flux estimates. In the long run, we envisage to fully couple the modelling approach with the automated field measurements that are being collected in a new national measurement network.

In this contribution, SOMERS will be introduced, and the calibration and validation approach will be discussed. We present predictions, under idealized average weather conditions, to establish effects of proposed mitigation measures. This directly serves policy development in regional spatial plans for the Dutch peatland meadows. Lastly, a first national peatland CO2 emission budget based on SOMERS is presented, which after some further development may support LULUCF-sector reporting in the Netherlands.

How to cite: Erkens, G., Melman, R., Jansen, S., Boonman, J., van der Velde, Y., Hefting, M., Keuskamp, J., van den Berg, M., van den Akker, J., Fritz, C., Bootsma, H., Aben, R., Hessel, R., Hutjes, R., van Asselen, S., Harpenslager, S. F., Kruijt, B., and consortium, N.: SOMERS: Monitoring greenhouse gas emission from the Dutch peatland meadows on parcel level, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12177, https://doi.org/10.5194/egusphere-egu22-12177, 2022.

EGU22-12962 | Presentations | ERE1.8

Green pearls: digital support for reforestation 

Djamilja Oud, Angelina Savchuk, Simon Quesseveur, Abdoul Aziz Mounkaila Issaka, and Marc van den Homberg

Haiti faces extreme land degradation, making the country prone to natural hazards and poverty, both undeniably linked. The Haitian Red Cross partnered with the Netherlands Red Cross, 510, and Commonland to roll out a long-term landscape restoration program. Over two decades, this program aims to realize 30 ‘Green Pearls. These are areas where best practices on restoration are combined to retrieve healthy landscapes, making communities more resilient and empowering people economically. Landscape restoration happens in small areas through planting trees and bushes. To carefully identify reforestation zones with the highest possible potential success rate, GIS-based site suitability analysis is applied using several indicators: Elevation (Slope), Soil (Soil PH, Soil Texture, Soil Bulk Density), and Climate (Solar Radiation, Temperature, Rainfall). Data on these indicators was obtained from different, often satellite-based data sources. All resulting layers (maps) per indicator are by default processed as equally important. However, the analysis can be tailored to produce different outcomes depending on the reclassification and weights given by experts to specific indicators. For the La Vallée de Jacmel region in the Haiti case, weighting was applied with the help of local experts. The output is a raster map indicating the locations for planting trees divided into five classes (from most suitable to least suitable). Currently, social indicators such as land ownership are not yet included. Our site suitability method is set up as a model using only open data from global datasets and is, therefore, replicable to other areas. The default model has also been applied to a similar case in the Kayes region in Mali. However, local knowledge on the significance of specific indicators remains indispensable input for the reforestation model. Overall, the site suitability method has proven to be a very useful digital support for holistic land restoration.

How to cite: Oud, D., Savchuk, A., Quesseveur, S., Mounkaila Issaka, A. A., and van den Homberg, M.: Green pearls: digital support for reforestation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12962, https://doi.org/10.5194/egusphere-egu22-12962, 2022.

Excessive growth in the global human population and eventually urbanisation has become a serious threat to the environment. These situations arise especially in the rapidly developing nations, India being one of them. A higher population naturally poses a high pressure on the environment directly or indirectly, which is a threat for the sustainable development of the country. Most Indian cities face environmental sustainability challenges. Most cities in India are presently going through rapid urbanization and industrialization which leads to environmental degradation of the city. The objective of this study is to analyse the environmental quality of the selected developing cities and also compare the intensity to which they are affected by urbanisation. The study is performed using satellite-based remote sensing data. Initially, Landsat data is used for the years 2001 to 2021 and is utilized for studying the LULC (land use land cover) transformations. MODIS data products are used at 1 km resolution to extract the biophysical indicators (BI) such as normalized difference vegetation index (NDVI) and land surface temperature (LST). MODIS data for PM2.5 is also utilised and finally, an index is calculated to represent the comprehensive environmental quality of the selected cities (CEQI). The yearly and decadal changes in the values of this index is mapped. The LULC transformations depicted a phenomenal decay in the greenness and an increase in the urban built-up area of the city. The CEQI variations and temporal trends reveal the significant deterioration of the overall environmental conditions in most of the cities. This is due to the change in gentrification patterns and also the change in urbanization and the greenness of the city. The study suggests that emission control strategies and urban greening can significantly contribute to enhancing urban environmental quality, especially in rapidly developing cities. The measures suggested to improve the environmental quality can help the policy-makers in the sustainable planning of the city.

How to cite: Singh, S. and Jain, K.: A comparative analysis of urban environmental quality of developing cities of India: A geospatial approach, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13558, https://doi.org/10.5194/egusphere-egu22-13558, 2022.

To achieve the ambitious but necessary climate targets set by the Paris Agreement, the IPCC model pathways for limiting global warming to 1.5°C compared to pre-industrial levels make apparent the need for safeguarding and enhancing the natural global carbon sink – including via carbon dioxide removal (CDR). A range of ocean-based CDR approaches, also termed “negative emissions technologies” (NETs), has been proposed to make use of the ocean’s potential to take up carbon dioxide from the atmosphere and store it in water, biomass, and sediments. The governance framework in place to regulate CDR in the ocean, at this time, is limited to the direct and articulate regulation of ocean fertilization. Meanwhile, other NETs such as ocean alkalinity enhancement and artificial upwelling emerge, but a comprehensive and foresight-oriented regulation for the testing or even deploying at larger scale is missing. Specifically, there is large uncertainty on unintended (positive and negative) effects of these technologies on the condition of the ocean, in addition to enhanced carbon uptake and storage, and how these may impede on or support other global sustainability goals. The deployment of NETs in the ocean poses additional governance complexities relating to unknowns, uncertainties, and transboundary issues. In a study that is part of the EU H2020-project OceanNETs, we explore to what extent the current global governance framework directly or indirectly regulates emerging ocean-based NETs and reflect on the particularities and requirements for their comprehensive governance. The analysis considers the gaps, challenges, needs, and opportunities for comprehensive governance of ocean-based NETs. 

How to cite: Neumann, B. and Röschel, L.: Global governance of ocean-based negative emission technologies. Exploring gaps, challenges, and opportunities, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-893, https://doi.org/10.5194/egusphere-egu22-893, 2022.

EGU22-1956 | Presentations | ITS4.4/ERE1.10

The implementation of ecological engineering in Tibet has strengthened the local human-policy-resource connection 

Yijia Wang, Yanxu Liu, Xutong Wu, Xinsheng Wang, Ying Yao, and Bojie Fu

Facing the dual threats of climate and socio-economic changes, how the social-ecological systems (SES) in the Tibet Autonomous Region can seize the opportunity of ecological restoration to enhance the quality of the environment while improving the relationship between human and nature is of great significance to promote the regional sustainable development. Thus, regarding human as the key component, we used Ostrom’s SES framework as an analytical fundation to analyze the impact of the implementation of ecological engineering on local human-policy-resource connection. We distributed questionnaires for local residents, distinguished experimental groups (EG, n=325) and control groups (CG,n =165), and used a network approach to construct indicators for assessing effectiveness of ecological engineering, including overall connectivity and evenness. Meanwhile, random forest regression was used to explore the background variables of the dominant connection and accordingly proposed subsequent directions for optimal governance. We found that interviewees in areas where ecological engineering was implemented had more positive perceptions of the importance of ecosystem services, the relationship between ecological conservation and well-being, attitudes toward ecological engineering, and the impact of measures. The overall connectivity and evenness of EG were significantly higher than that of CG. The implementation of ecological engineering enhanced the connection between local people and the environment, but caused some inconvenience to local residents’ livelihoods. Besides, elevation and annual precipitation were the background variables that dominated the overall connectivity. The overall connectivity was lower in alpine steppes with elevation of around 4000 m and semi-arid areas with annual precipitation around 400-500 mm. The implementation of ecological engineering played a positive role in alleviating human-nature relationship in tensions and promoting collective governance of common pool resources, but the governance process still involved risks. Safeguarding and improving the residents’ livelihoods and enhancing the regional weak SES coupling due to geographical constraints are the future directions for optimal governance.

How to cite: Wang, Y., Liu, Y., Wu, X., Wang, X., Yao, Y., and Fu, B.: The implementation of ecological engineering in Tibet has strengthened the local human-policy-resource connection, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1956, https://doi.org/10.5194/egusphere-egu22-1956, 2022.

EGU22-1978 | Presentations | ITS4.4/ERE1.10

Mapping NBS stakeholders’ perspective over Sludge Treatment Reed Bed (STRB) in Iceland 

Amir Gholipour, Elizabeth Duarte, Rita Fragoso, Ana Galvao, and David Christian Finger

Nature-Based Solutions (NBSs) like Sludge Treatment Reed Beds (STRBs) can address resource recovery from sewage sludge in urban and rural areas to boost circular economy and to mitigate climate change. To ensure successful implementation of STRBs, an evaluation of stakeholders’ perceptions can be helpful to identify relevant barriers and opportunities. In this study, semi-structured interviews were conducted with relevant stakeholders, which were categorized in 5 interest groups including academics, state and governments, NGOs, water companies and local communities across Iceland. The interviews were then transcribed and effective elements influencing STRB technology in Iceland were identified through an open-coded method on the transcriptions. The elements were categorized as independent elements (NBS actors, on-going projects, feasibility, legal, economic, sociological, and natural criteria), which were grouped into 7 classifications impacting dependent elements (relevant aspects of STRB, STRB services and system cost). Through Causal Diagrams (CDs), the impact of the independent elements was visualized on the dependent elements. The result of the study is exposed in 8 causal networks and 4 aggregated CDs for sustainability, climate change, biodiversity and circular economy together with mediators interpreting the impacts. The complexity of multi-sequenced causalities of a heterogeneous nature is depicted in CDs implying by stakeholders’ reports and expectations. The study exposes information on the compatible aspects, where further research is required to facilitate the use of STRB for the resource recovery of sewage sludge in Iceland. Therefore, our findings can enable decision makers with intracommunity information to identify elements impacting STRB application, in which the influence of the multiple groups of interests is regarded. 

 

Keywords: Nature-Based Solutions; Sludge Treatment Reed Beds, Resource Recovery, Causal Diagram, climate change, circular economy, sustainability

How to cite: Gholipour, A., Duarte, E., Fragoso, R., Galvao, A., and Christian Finger, D.: Mapping NBS stakeholders’ perspective over Sludge Treatment Reed Bed (STRB) in Iceland, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1978, https://doi.org/10.5194/egusphere-egu22-1978, 2022.

EGU22-4699 | Presentations | ITS4.4/ERE1.10

Assessing global macroalgal carbon dioxide removal potential using a high-resolution ocean biogeochemistry model 

Manon Berger, Laurent Bopp, David T. Ho, and Lester Kwiatkowski

Carbon dioxide removal (CDR) has become part of the portfolio of solutions to mitigate climate change. In combination with emission reductions, CDR may be critical to achieving the goal of limiting global warming to below 2°C, as outlined in the Paris Agreement. Due to its potential high productivity and environmental co-benefits, macroalgae cultivation has recently become a prominent ocean-based CDR strategy. However, estimates of the CDR potential of large-scale deployment are highly limited. Here we simulate idealized global deployment of macroalgae-based CDR using the NEMO-PISCESv2 ocean biogeochemical model at high spatial resolution (0.25° nominal horizontal resolution). Macroalgae growth is confined to the upper 100m of the water column in Exclusive Economic Zones (EEZ) free of sea ice and with an appropriate nitrate/phosphate regime. Although the loss of dissolved inorganic carbon (DIC) through macroalgal growth enhances the flux of atmospheric carbon into the ocean, this increase in carbon uptake is less than the rate of macroalgal production. In the absence of any nutrient limitation on growth, the enhancement in ocean carbon uptake is only 73-77% of the carbon lost from the water column due to macroalgal production. However, when macroalgae nutrient limitation/uptake is additionally accounted for, the increase in ocean carbon uptake accounts for only 41-42% of the potential carbon lost through macroalgae production. These inefficiencies are due to ocean transport replacing part of the DIC lost in the upper water column with DIC from depth, the influence of local nutrient concentrations on the vertical profile of macroalgal production, and feedbacks on the nutrient resources available for phytoplankton net primary production. CDR efficiency is shown to scale near-linearly between scenarios assuming 1% to 10% of the global EEZ area is cultivated for macroalgae. The efficiency of macroalgal CDR shows significant regional variability, with much of the enhancement in ocean carbon uptake (43%-46%) occurring outside EEZs, posing potential difficulties to national scale accounting.

How to cite: Berger, M., Bopp, L., Ho, D. T., and Kwiatkowski, L.: Assessing global macroalgal carbon dioxide removal potential using a high-resolution ocean biogeochemistry model, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4699, https://doi.org/10.5194/egusphere-egu22-4699, 2022.

EGU22-5175 | Presentations | ITS4.4/ERE1.10 | Highlight

Completing Urban GHG Emissions Data to Assess the Effectiveness of Climate Action Plans in Europe 

Jessica Page, Haozhi Pan, and Zahra Kalantari

Urban areas are major contributors to global greenhouse gas (GHG) emissions. To address climate change, many cities have developed climate action plans (CAPs) as strategic roadmaps to reduce their emissions and strive for emission neutrality and climate resilience by 2050 or before. It has been more than a decade since the first of these plans were put in place, and it is now important to evaluate these plans and to access whether city-level climate ambitions will be realised or perhaps need adjustment to pursue for improvements in climate resilience over time

 This work aims to further our understanding of urban GHG emissions, by completing existing urban carbon emissions data with blue-green contributions to the urban carbon cycle. In a previous study, it was found that the inclusion of blue-green emissions in urban carbon accounting in Stockholm, Sweden had a significant impact on that region’s ability to reach net zero emissions in the coming decades (Page et al., 2021). In this study, we complete the urban emissions data for cities across the European Union (EU) in order to assess if, and for which types of cities, the inclusion of blue-green emissions in the GHG accounting is similarly relevant.

Furthermore, we will use data about the CAPs produced and implemented by these cities together with the completed GHG emissions in order to assess whether the actions and plans made by many European cities have actually had any impact on the emissions from these cities. The inclusion of blue-green emissions and sequestrations in this assessment is particularly important, as many of the strategies included in CAPs impact blue-green areas, such as the implementation of nature-based solutions (NBS).

Conclusions will be drawn about the role of green-blue areas in urban GHG emissions, the role which CAPs have played in reducing emissions in European cities, and how and where these could potentially be adapted to further reduce future GHG emissions in urban areas.

Keywords: Sustainable cities; Greenhouse Gas Emissions; Nature-based Solutions; Climate Action Plans

References:

Page J, Kåresdotter E, Destouni G, et al. (2021) A more complete accounting of greenhouse gas emissions and sequestration in urban landscapes. Anthropocene 34: 100296. DOI: 10.1016/j.ancene.2021.100296.

How to cite: Page, J., Pan, H., and Kalantari, Z.: Completing Urban GHG Emissions Data to Assess the Effectiveness of Climate Action Plans in Europe, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5175, https://doi.org/10.5194/egusphere-egu22-5175, 2022.

EGU22-6126 | Presentations | ITS4.4/ERE1.10

Investigating potential climatic side-effects of a large-scale deployment of photoelectrochemical devices for carbon dioxide removal 

Moritz Adam, Thomas Kleinen, Matthias M. May, Daniel Lörch, Arya Samanta, and Kira Rehfeld

Without substantial decarbonization of the global economy, rising atmospheric carbon dioxide (CO2) levels are projected to lead to severe impacts on ecosystems and human livelihoods. Integrated assessments of economy and climate therefore favour large-scale CO2 removal to reach ambitious temperature-stabilization targets. However, most of the proposed approaches to artificially remove CO2 from the atmosphere are in conflict with planetary boundaries due to land-use needs and they may come with unintended climatic side-effects. Long-term draw-down of CO2 by photoelectrochemical (PEC) reduction is a recent and promising approach that potentially entails a very low water footprint and could offer a variety of carbon sink products for safe geological storage. For renewable hydrogen fuel production, PEC devices have already been demonstrated to deliver high solar-to-fuel efficiencies. If such devices are adjusted to deliver high solar-to-carbon efficiencies for carbon dioxide removal, they would require comparably little land for achieving annual sequestration rates that are compatible with limiting global warming to 2°C or below. Yet, no production-scale prototype exists and the climatic side-effects of such an "artificial photosynthesis'' approach for negative emissions are unknown. Here, we discuss our work towards investigating potential impacts of PEC CO2 removal on the climate and the carbon cycle in simulations with the comprehensive Earth System Model MPI-ESM. We designed a scheme to represent hypothetical PEC devices as a land surface type which is influencing land-atmosphere energy and moisture fluxes. We parameterize the irradiation-driven carbon sequestration of the devices and interactively couple their deployment area and location to a negative emission target. We plan to compare the potential side-effects between scenarios of dense, localized deployment and spread-out, decentralized application. These scenarios represent different guiding objectives for deploying hypothetical PEC systems such as maximizing the insolation per module area, or mitigating the overall impacts on climate and on carbon stocks. For the different scenarios, we intend to investigate changes in the surface balances, which could impact atmospheric circulations patterns. We further plan to quantify the amount of land-stored carbon that is relocated due to land-use change, as this affects the amount of CO2 that can effectively be withdrawn from the atmosphere. Finally, we relate theoretical expectations for area requirements and CO2 withdrawal with results from the coupled simulations which could inform the technological development. While ambitious emission reductions remain the only appropriate measure for stabilizing anthropogenic warming, our work could advance the understanding of possible benefits and side-effects of hypothetical PEC CO2 removal.

M. M. May & K. Rehfeld, ESD Ideas: Photoelectrochemical carbon removal as negative emission technology. Earth Syst. Dynam. 10, 1–7 (2019).

How to cite: Adam, M., Kleinen, T., May, M. M., Lörch, D., Samanta, A., and Rehfeld, K.: Investigating potential climatic side-effects of a large-scale deployment of photoelectrochemical devices for carbon dioxide removal, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6126, https://doi.org/10.5194/egusphere-egu22-6126, 2022.

EGU22-7019 | Presentations | ITS4.4/ERE1.10

Forecasting impacts of climate change on plantation carbon sink capability 

Hung-En Li and Su-Ting Cheng

In the face of climate change, the government of Taiwan requires new mitigation policies and implementation strategies. As forest plantations are commonly accepted as great carbon sinks, developing reliable carbon systems linking forestry carbon sequestration into green carbon credits in the economic sector requires synergic integration to examine potential carbon sink capability of forest plantations under the ever-changing climate. In this regard, this study developed a process-based stand growth model based on the structure of the Physiological Principles for Predicting Growth (3-PG) for carbon sequestration estimations of Sugi plantations in the National Taiwan University (NTU) Experimental Forest. The model considered monthly solar radiation, temperature, precipitation, vapor pressure deficit (VPD), and the atmospheric carbon dioxide concentration to simulate dynamic biomass production, and then allocated the simulated biomass to root, stem, and foliage by allometric equations fitted to biomass data from the SugiHinoki Database. After that, the mortality of stand was determined by using a zero-inflated Poisson modelling on long-term growth data collected by the NTU Experimental Forest during 1921-2019. In addition, we performed a scenario analysis to forecast future stand growth under 4 climate scenarios of RCP2.6, RCP4.5, RCP6, and RCP8.5. Results revealed higher annual biomass increment (around 4 t ha-1y-1) in the end of the century in RCP6.0 and RCP8.5, and lower increment (around 2.5 t ha-1y-1) in RCP2.6 and RCP4.5. A step-wise multiple linear regression analysis on the simulated growth data and climatic inputs revealed stronger positive impact of CO2 concentration than precipitation on unit biomass primary production (NPP/Biomass). Temperature had comparable counter impact against precipitation, and solar radiation showed the least negative influence on unit biomass primary production. Based on this process-based stand growth model, we are able to dig into the relation between climatic variables and carbon sequestration rate, and help sketch prospect of plantations in the carbon market for plantation managers, investors, and policy makers.

How to cite: Li, H.-E. and Cheng, S.-T.: Forecasting impacts of climate change on plantation carbon sink capability, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7019, https://doi.org/10.5194/egusphere-egu22-7019, 2022.

EGU22-7324 | Presentations | ITS4.4/ERE1.10

Assessing co-benefits of urban greening coupled with rainwater harvesting management under current and future climates across USA cities 

Ziyan Zhang, Athanasios Paschalis, Ana Mijic, Barnaby Dobson, and Adrian Butler

Globally, urban areas will face multiple water-related challenges in the near future. The main challenges are intensified droughts leading to water scarcity, increased flood risk due to extreme rainfall intensification, increased total water demand due to an increasing urban population, amplified urban heat island intensities due to urban sprawl, and reduction in urban carbon sink due to plant water stress. Urban greening is an excellent option for mitigating flood risk and excess urban heat. Meanwhile, rainwater harvesting (RWH) systems can cope with water supply needs and urban water management. In this study, we investigated how urban greening and RWH can work together to mitigate the aforementioned risks. We evaluate the joined-up management approach under climate projections for 30 cities in the USA spanning a variety of climates, population densities and urban landscapes. By incorporating a new RWH module in the urban ecohydrological model UT&C and flexible operational rules of reusing harvested water for domestic use and urban green space irrigation, we tested 4 intervention approaches: control, RWH installation, urban greening supported by RWH, and urban greening supported by traditional irrigation (i.e., supplying via mains water). Each intervention approach was evaluated using our adapted version of UT&C and forced by the last generation convection-permitting model simulations of current (2001-2011) and end-of-century (RCP8.5) climate from Weather Research and Forecasting (WRF). The volume of RWH is assumed to be 2000L per household for all cities. Results showed that neither urban greening nor RWH could contribute significantly to reducing the expected increase in canyon temperature, because of the strong change in background climate (i.e., increases in average atmospheric temperature). However, RWH alone can sufficiently reduce the intensifying surface flood risk and effectively enhance water conservation, and urban greening can significantly increase the carbon sink of cities especially in dry regions, and if supported by traditional irrigation. Those results vary with the background climate: the benefits of urban greening, either supported by RWH or traditional irrigation, on canyon temperature reduction and carbon sink improvement increased with average air temperature and decreased with wetness index respectively; the benefits of RWH on runoff reduction and water conservation are both positively dependent on local annual precipitation.

How to cite: Zhang, Z., Paschalis, A., Mijic, A., Dobson, B., and Butler, A.: Assessing co-benefits of urban greening coupled with rainwater harvesting management under current and future climates across USA cities, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7324, https://doi.org/10.5194/egusphere-egu22-7324, 2022.

Multiple disaster risks are interconnected and are commonly caused by ecosystem degradation. Ecosystem degradation also drives many of the world's major problems, including biodiversity loss, climate change, and poverty. Ecosystem-based solutions such as ecosystem-based adaptation, biodiversity conservation, and community forestry are increasingly implemented in various contexts. However, little is known about possible interlinkages, synergies, and trade-offs among those ecosystem-based responses and potential barriers to their integration. This study explores spatial and conceptual synergies and trade-offs among ecosystem-based adaptation, biodiversity conservation, and community forestry and the barriers to implementing integrated actions.

The study was located in Ayeyarwady Delta, Myanmar. The research first used a comprehensive socio-ecological risk assessment framework and multi-risk impact chains to understand high-risk areas and identify potential areas for ecosystem-based adaptation. Potential areas for biodiversity conservation and community forestry respectively were then identified using criteria developed based on a literature review. At this point, spatial autocorrelations were tested, and a modified t-test was used to identify spatial relationships among them. Finally, qualitative expert interviews were conducted, and content analysis was used to understand conceptual synergies, trade-offs, and potential barriers for integrated action.

Results show potential for both social and ecological synergies. Ecosystem-based adaptation and biodiversity conservation show synergies with community forestry in the areas of local governance, and the relevance of social factors such as multi-stakeholder awareness, indigenous knowledge, land tenure security, community rule-making and ownership, and biodiversity-friendly livelihoods. Synergies between ecosystem-based adaptation and biodiversity conservation are mostly related to ecological factors such as benefits for biodiversity, ecosystem health, and corridor and buffer functions. Moreover, significant spatial synergies were observed between community forestry and biodiversity conservation areas.

Despite synergies, trade-offs exist and are mainly linked to social inequalities and the use of biodiversity-damaging practices. Spatial trade-offs occur between ecosystem-based adaptation and community forestry due to a lack of land tenure security in high-risk townships. Conceptual trade-offs between ecosystem-based adaptation and community forestry are mainly linked to inequality, lack of access, local power relations, and land tenure insecurity. Trade-offs between biodiversity and the other two are observed due to the use of monocultures, exotic species, and clear-cutting practices. Legal, social, and financial barriers have been identified for the implementation of synergetic actions, while proper facilitation, community rule-making, and biodiversity-friendly livelihoods are key enabling factors in achieving sustainable ecosystem restoration.

This research argues that ecosystem-based adaptation, biodiversity conservation, and community forestry benefit each other, highlighting that fostering those synergies is key for ecosystem restoration and conservation in the face of climate change, biodiversity loss, and poverty. Furthermore, the research stresses the need to consider community governance and biodiversity aspects in ecosystem-based adaptation to address societal challenges.

How to cite: Wuit Yee Kyaw, H. and Sebesvari, Z.: Assessment of synergies and trade-offs among ecosystem-based adaptation, biodiversity conservation and community forestry in Ayeyarwady Delta, Myanmar, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7415, https://doi.org/10.5194/egusphere-egu22-7415, 2022.

EGU22-7797 | Presentations | ITS4.4/ERE1.10

Governance and science implications of low environmental impact outdoors solar radiation management experiments 

Gideon Futerman, Martin Janssens, Iris de Vries, John Dykema, Andy Parker, and Hugh Hunt

There are many uncertainties surrounding solar radiation management (SRM), which cannot all be quantified and reduced using models, laboratory experiments or observations of natural analogs such as volcanic eruptions, ship tracks, or dust storms. While there is broad consensus both in- and outside the scientific community that better understanding of the climate system is beneficial to policy makers and society, the value of improved knowledge of SRM has been highly controversial. Yet, it is evident that SRM research can contribute to quantifying and reducing important uncertainties pertaining to fundamental knowledge on the workings of the Earth system, while also providing essential specific knowledge on positive and negative impacts of SRM to inform future decisions.

In 2016, a group of SRM experts gathered at the Institute for advanced sustainability studies in Potsdam for a workshop to formulate a set of low environmental impact SRM experiment proposals. We present these as a non-exhaustive set of possible experiments with no measurable environmental side effects that could provide valuable information that cannot be obtained from models or lab experiments. Both perturbative and non-perturbative experiments are proposed for different SRM methods including marine cloud brightening, stratospheric aerosol injection and cirrus cloud thinning.

It was found that in the time period between 2016 and now several of the research questions addressed in the experiment proposals have been answered by unrelated experimental environmental science studies, whereas no experimental studies have been carried out in the context of SRM. This finding shows that there is significant overlap in high priority research questions and outcomes of non-SRM and SRM environmental research. In addition, it shows that non-controversial environmental science experiments can provide similar SRM-relevant knowledge as dedicated SRM-experiments. Given that one of the main arguments against SRM research is the potential danger of the acquired knowledge, the finding that obtained knowledge of non-SRM and SRM experiments can be similar raises the question which effect the declared relationship to SRM on outdoors research proposal review and regulation should be.

How to cite: Futerman, G., Janssens, M., de Vries, I., Dykema, J., Parker, A., and Hunt, H.: Governance and science implications of low environmental impact outdoors solar radiation management experiments, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7797, https://doi.org/10.5194/egusphere-egu22-7797, 2022.

EGU22-7868 | Presentations | ITS4.4/ERE1.10 | Highlight

The potential of urban soils for carbon neutral cities 

Esko Karvinen, Leena Järvi, Toni Viskari, Minttu Havu, Olivia Kuuri-Riutta, Pinja Rauhamäki, Jesse Soininen, and Liisa Kulmala

Urban areas are notable sources of atmospheric CO2 and cities are currently setting up climate programs with the aim of carbon neutrality in the near future. For example, two major cities in Southern Finland, Helsinki and Turku, have set their targets for 2035 and 2029, respectively. Carbon neutrality can be achieved by reducing carbon emissions, compensating them, and / or strengthening carbon sinks in urban vegetation and soils, the last of which is often deemed the most cost-efficient option. However, the current understanding of biogenic carbon cycling in urban environments is based on dynamics observed in more well-known ecosystems such as forests and agricultural lands. Urban ecosystems differ from non-urban areas in terms of temperature, precipitation and water cycling, pollution, and the level of human-induced disturbance. Thus, there is a need for observations on urban carbon to accurately model and estimate the carbon sinks and stocks in urban green space.

We aimed to monitor urban biogenic carbon cycle with an extensive field campaign carried out around the SMEAR III ICOS station in 2020–2022, accompanied by a few satellite sites around the capital region of Finland. In this presentation, we will show soil carbon pools and the dynamics of soil respiration at five different types of urban green space: a managed park lawn with and without trees, small urban forest, apple orchard, and street tree site. Soil respiration was measured with both regularly repeated manual chamber measurements and automatic chambers throughout two growing seasons. Soil carbon stock was estimated by soil samplings conducted in 2020 and 2021. We investigate the role of different drivers in soil CO2 emission at the various urban green space types and compare those to corresponding metrics measured in non-urban areas. In addition, we test the applicability of Yasso model to simulate the soil carbon dynamics in urban areas.

How to cite: Karvinen, E., Järvi, L., Viskari, T., Havu, M., Kuuri-Riutta, O., Rauhamäki, P., Soininen, J., and Kulmala, L.: The potential of urban soils for carbon neutral cities, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7868, https://doi.org/10.5194/egusphere-egu22-7868, 2022.

There are many uncertainties surrounding solar radiation management (SRM), not in the least concerning the technological feasibility of hypothetical deployment scenarios. In sulfate stratospheric aerosol injection (SAI) scenarios, the radiative effectiveness of the aerosol is governed by its size distribution. In turn, aerosol size distribution is governed by the aerosol-precursor injection rate and injection plume conditions. Hence, uncertainties in cost and environmental impact of aircraft-based sulfate stratospheric aerosol injection (SAI) are primarily determined by uncertainties in injection plume conditions. In addition, the climate impacts and side effects of SAI as simulated by climate models depend on the prescribed initial conditions concerning aerosol characteristics, which also hinge on injection plume dynamics and microphysics.

Up to now, studies into aircraft-based SAI have used simplified plume models, which estimate plume dynamics with considerable uncertainty, and which do not account for effects of the local plume dynamics on the microphysical processes. Here, we work towards reducing this uncertainty by using full computational fluid dynamics representations of plume dynamics within simulations incorporating state-of-the-art microphysics models for the computation of aerosol size distributions in aircraft engine plumes.

In order to anchor our approach in the current literature, we first consider simplified problems with the objective of validating our methodology using existing results. These experiments confirm the attainability of favourable initial aerosol size distributions under roughly the same conditions as shown with other lower-fidelity models. However, our results retain disagreement with respect to previous studies concerning the exact aerosol growth behaviour, highlighting a sensitivity to model choice which may also explain apparent contradictions in those previous studies. 

We then consider a RANS computational fluid dynamic representation of an engine plume. This differs from the simplified plume representation in several ways, including realistic local variations in temperature, vorticity, and eddy viscosity resulting from the inflow determined using a state-of-the-art engine model. This representation is currently being employed in combination with the previously validated microphysical models to simulate realistic aerosol size evolutions for aircraft-based delivery scenarios.

We anticipate our results to (1) provide a higher-confidence foundation on which to base the discussion concerning technological feasibility of SAI-based SRM and (2) constrain the uncertainty range of inputs for model and impact studies, improving reliability of simulations of (desired and undesired) effects of potential SRM scenarios and thereby informing the scientific and public debate.  

How to cite: Tluk, A., de Vries, I., Janssens, M., and Hulshoff, S.: Towards higher fidelity simulations of aerosol growth in aircraft plumes for feasibility and impact assessment of sulfate stratospheric aerosol injection, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7923, https://doi.org/10.5194/egusphere-egu22-7923, 2022.

 

Abstract

The challenges posed by the growth of urbanization in Egypt and the development of new cities play an essential role in applying the circular economy (CE) in the construction materials sector and the priorities for promoting sustainable construction activities in the future. Therefore, the construction sector has many adverse environmental impacts on energy and natural resources consumption. Starting from materials production, operation until disposal to landfills. Consequently, the industry is considered one of the most consumers of non-renewable resources and producer of CO2 emissions. On the other hand, applying Nature-based solutions (NbS) to enhance sustainability by protecting the ecosystems and maintaining economic benefits plays a vital role, especially for new Egyptian cities. The research aims to investigate the role of applying NbS for achieving CE in construction materials and eliminate its negative impact in the scope of three factors:  green building materials, waste management systems, renewable energy use. The current research attempts to answer how NbS can improve the CE and reduce environmental impacts of the construction materials sector. Therefore, the SOWT analysis investigated the strengths, opportunities, weaknesses, and threats of using the NbS strategies for three different construction sites in Egypt. Furthermore, the survey questionnaire was applied to identify the interactions between the parameters derived from 40 participants such as consultants, architecture engineers, civil engineers, site engineers, project managers and review the previous research efforts. As a result, a conceptual framework was created for the construction materials considering reduce, reuse, recycle, recovery, and disposal, to identify the impact of the implementation of NbS on achieving sustainable development strategies in the Egyptian construction sector. The result showed that the NbS could effectively promote the construction sector and achieve environmental and economic benefits, which consequently help the transition to CE. Therefore, there is the necessity for developing new sustainable policies and cooperation between public and private sectors to support the investments of sustainable strategies in the construction materials market and increase Egyptian society's awareness of the benefits of NbS in economic, environmental, and social aspects.

 Keywords, Nature-based solution, Construction materials, Circular Economy, Egypt 

How to cite: Marey, H., Szabó, G., and Kozma, G.: Using the Nature-Based Solutions for Applying Circular Economy for the Construction Materials Sector in Egypt, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7997, https://doi.org/10.5194/egusphere-egu22-7997, 2022.

EGU22-8269 | Presentations | ITS4.4/ERE1.10

Carbon cycle feedbacks in an idealized and a scenario simulation of carbon dioxide removal in CMIP6 Earth system models 

Ali Asaadi, Jörg Schwinger, Hanna Lee, Jerry Tjiputra, Vivek Arora, Roland Séférian, Spencer Liddicoat, Tomohiro Hajima, Yeray Santana-Falcòn, and Chris Jones

Limiting global warming to 1.5°C by the end of the century currently seems to be an ambitious target which will potentially be accompanied by a period of temperature overshoot. Achieving this climate goal might require massive carbon dioxide removal on large scales. Regardless of the feasibility of such removals, their effects on biogeochemical cycles and climate are not well understood. Changes in atmospheric CO2 concentration ([CO2]) and climate alter the CO2 exchange between the atmosphere and the underlying carbon reservoirs of land and ocean. Carbon-concentration and carbon-climate feedback metrics are useful tools for quantifying such changes in the carbon uptake by land and ocean, currently acting as a sink of carbon. We investigate the changes in carbon feedbacks under overshoot scenarios that could influence mitigation pathways to achieve the temperature goal. An ensemble of Coupled Model Intercomparison Project 6 (CMIP6) Earth system models that conducted an idealized ramp-up and ramp-down experiment (1pctCO2, with increasing and later decreasing [CO2] at a rate of 1% per year) has been used and compared against a scenario simulation involving negative emissions (SSP5-3.4-OS). The analyses are based on results from biogeochemically coupled (where land and ocean respond to rising CO2 levels but the climate is kept constant) and fully coupled simulations. For the positive emission phases, the model-mean global average carbon-climate feedback looks roughly similar between the SSP5-3.4-OS and the 1pctCO2 simulations, with a gradual monotonic decreasing behavior in absolute values which translates to a reduction in land and ocean uptakes. The carbon-concentration feedback in SSP5-3.4-OS is larger than in the 1pctCO2 simulations over the ocean. Both the ocean and land simulate an increase in carbon uptake during the ramp-up, while during the ramp-down, their uptakes show a hysteresis behavior. This feature is more prominent in the idealistic 1pctCO2 experiment with a higher [CO2] growth rate and without land use change effects than in the more realistic SSP5-3.4-OS scenario. Also, the time evolution of the global annual carbon-concentration and carbon-climate feedbacks seem to be very similar over natural land areas. In addition, changes in carbon fluxes are compared over the high latitude permafrost and non-permafrost regions in the Northern Hemisphere. Over land, the carbon-concentration feedback metric is decomposed into different terms to investigate the contributions from changes in live vegetation carbon pools and soil carbon pools. This indicates that the feedback is dominated by the residence time of carbon in vegetation and soil. Furthermore, building on previous studies, feedback metrics are also calculated using an alternative approach of instantaneous flux-based feedback metrics to further compare differences between models. The difference between the two approaches can be seen more obviously in the geographical distribution of the two feedbacks, especially for the negative emission phases of the 1pctCO2 experiment.

How to cite: Asaadi, A., Schwinger, J., Lee, H., Tjiputra, J., Arora, V., Séférian, R., Liddicoat, S., Hajima, T., Santana-Falcòn, Y., and Jones, C.: Carbon cycle feedbacks in an idealized and a scenario simulation of carbon dioxide removal in CMIP6 Earth system models, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8269, https://doi.org/10.5194/egusphere-egu22-8269, 2022.

EGU22-8598 | Presentations | ITS4.4/ERE1.10 | Highlight

A systematic analysis of Horizon 2020 Nature-Based adaptation Solutions projects 

Mario Al Sayah, Pierre-Antoine Versini, and Daniel Schertzer

With the advances of the Nature-Based Solutions (NBS) concept, much attention is being given to its potential for climate change adaptation. Accordingly, Nature-Based adaptation Solutions (NBaS) have become central elements for action on climate. In the EU, the Horizon 2020 (H2020) program translates the ambition of positioning Europe as the world’s leader in NBS. In an effort to draw a comprehensive roadmap of these efforts, this study investigates 21 H2020 projects that utilize NBaS throughout different ecosystems. The main objectives of this study are to provide an inventory of current knowledge, to extract identified risks and knowledge limitations, and to propose future research orientations.

For this purpose, the CORDIS database was used to identify the relevant projects. Using the keyword nature-based solutions and through a rigorous search of research topics and programs, the following projects were retained (based on the existence of deliverables at the time of this study): CLEARING HOUSE, CLEVER Cities, Connecting Nature, DRYvER, EdiCitNet, EuPOLIS, FutureMARES, GrowGreen, NAIAD, Nature4Cities, NATURVATION, OPERADNUM, PHUSICOS, proGIreg, RECONECT, REGREEN, RENATURE, ThinkNature, UNaLab, Urban GreenUP and URBiNAT. Consequently, 137 deliverables were individually examined. Numerous findings were then obtained. These were divided into general and specific results.

In terms of general results, the definition of the NBS concept is still debated: some projects adopt the EC’s definition, others compare between the EC’s and the IUCN’s definition, while many reformulate their own. Second, the continental geographical gradient of pilot sites follows a dense South-West orientation in contrast to a less developed North-Eastern line. In terms of target ecosystems, 61% of the projects target the urban realm, while freshwater ecosystems come second. The coastal, natural and mountainous environments are the least addressed. The focus on urban systems makes most of the generated knowledge, designed solutions and monitoring methods more or less restricted to this realm, hence not necessarily applicable in other settings. Regarding climatic challenges, urban heat islands and floods came first. These are followed by sea level rise, intense precipitation, heat stress, storms, erosion and landslides.

In terms of specific findings, current knowledge and limitations were grouped in-depth per ecosystem (urban, freshwater, marine-coastal, mountainous, forest-natural, and agricultural) and per main research topics (climate change adaptation, risks of oversimplification, system complexity, uncertainty, the scale quandary, progress measuring-monitoring, and disservices). On this basis, several research perspectives were then proposed. Accordingly, interest in NBS-NBaS should extend beyond the urban ecosystem, while deeper knowledge on nature (the physical fundamentals of the N) in NBS-NBaS is needed. It is also important to understand if NBaS are intended to withstand weather change and/or climate change. For the implementation of wide-scale solutions, an extension beyond conservationism is needed, and a better accommodation of uncertainties is required. Therefore, understanding ecosystem tipping points, thresholds, and the resource efficiency of NBaS is primordial. Finally, it is crucial to acknowledge that both ecosystem development and climate change will keep progressing throughout the existence of NBaS. Therefore, the interacting co-evolution of ecosystems, NBaS and climate change should be further studied where their interaction could be forgotten.

How to cite: Al Sayah, M., Versini, P.-A., and Schertzer, D.: A systematic analysis of Horizon 2020 Nature-Based adaptation Solutions projects, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8598, https://doi.org/10.5194/egusphere-egu22-8598, 2022.

EGU22-8613 | Presentations | ITS4.4/ERE1.10 | Highlight

Spatial deployment of Nature-based Solutions to support carbon neutrality for 50 EU cities. 

Haozhi Pan, Jessica Page, Cong Cong, and Zahra Kalantari

Clear implementing plan for Nature-based solutions (NBS) beyond conceptualization is critical for successful in mitigating urban carbon emissions. In this paper, we demonstrate an approach to deploy nature-based solutions on high-resolution (25x25-meter) land use grid and its carbon emission reduction benefits for 50 major European Union (EU) cities. The deployment process takes 3 parts: 1) downgrading carbon emission data with larger spatial scales (10x10km GID data) to high-resolution cells using land use and socioeconomic data; 2) identifying opportunities and suitability of deploying NBS on these land use cells from a database with meta-analysis on the emission reduction potentials of different types of NBS; 3) Estimating total carbon emission potentials from spatial deployment and coupling of of multiple NBS with parametric simulation. Our results indicate that vast areas of urbanized and un-urbanized lands in EU cities can apply NBS to further mitigate carbon emissions. The reduction potential is huge and can contribute to a critical wedge of carbon neutrality.     

How to cite: Pan, H., Page, J., Cong, C., and Kalantari, Z.: Spatial deployment of Nature-based Solutions to support carbon neutrality for 50 EU cities., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8613, https://doi.org/10.5194/egusphere-egu22-8613, 2022.

EGU22-9109 | Presentations | ITS4.4/ERE1.10 | Highlight

Ecosystems for disaster risk reduction: what is the scientific evidence? 

Dr. Karen Sudmeier-Rieux and the Co-authors

Calls are rising for ecosystems, or green infrastructure, to complement engineered infrastructure for more effective disaster risk reduction and climate governance. Key international framework agreements, including the Sendai Framework for Disaster Risk Reduction 2015-2030 and the 2021 Glasgow Pact, noted the importance of ensuring the integrity of all ecosystems in addressing climate change and disaster risk. For example, vegetation can stabilize slopes to reduce mountain hazards and sand dunes, mangroves, and/or seagrasses can reduce the impacts of coastal storms.  However, there are gaps in the scientific evidence on this topic with few comprehensive, peer-reviewed studies to support decision-making on green infrastructure for disaster risk reduction.

This study systematically reviews 529 English-language articles published between 2000 and 2019. The objective was to catalogue the extent of knowledge and confidence in the role of ecosystems in reducing disaster risk. The main question this review addresses is: What is the evidence of the role that ecosystem services and/or functions contribute to disaster risk reduction? We modified the review methodology established by the Intergovernmental Panel on Climate Change to identify the robustness of evidence and level of agreement on the role of ecosystems in attenuating most common types of hazards.

The data demonstrate very robust links on the role of ecosystems in forest fire management, urban flooding and slope stabilization to reduce mountain hazards in a cost-effective manner. The study also highlights how ecosystems provide multiple services and functions in addition to regulating hazards, e.g., provisioning services for reducing vulnerability. The review highlights several research gaps, notably a geographic concentration of studies on urban areas of Europe and North America, and insufficient policy-relevant research on coastal, dryland, and watershed areas, especially in Asia, Africa and Latin America. To conclude, more attention should be paid to filling these research gaps and developing performance standards, which would provide policy-makers with increased confidence in investing in green infrastructure for disaster risk reduction and climate governance.

How to cite: Sudmeier-Rieux, Dr. K. and the Co-authors: Ecosystems for disaster risk reduction: what is the scientific evidence?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9109, https://doi.org/10.5194/egusphere-egu22-9109, 2022.

EGU22-10433 | Presentations | ITS4.4/ERE1.10 | Highlight

Suitability of soil carbon certificates for climate change mitigation 

Carsten Paul, Axel Don, Bartosz Bartkowski, Martin Wiesmeier, Sebastian Weigl, Steffi Mayer, Markus Steffens, André Wolf, Cenk Dönmez, and Katharina Helming

There is growing awareness of the role that agricultural soils can play for climate change mitigation. Agricultural management that increases soil organic carbon (SOC) stocks constitutes a nature-based solution for carbon dioxide removal. As soils store about twice the amount of carbon found in the atmosphere, even small relative increases could significantly reduce global warming.

However, increasing SOC requires management changes that come with costs to the farmers. In this regard, soil carbon certificates could provide a much-needed financial incentive: Farmers register their fields with commercial providers who certify any SOC increase achieved during a set period of time. The certificates are then sold on the voluntary carbon-offset market. We analysed the suitability of soil carbon certificates for climate change mitigation from the perspectives of soil sciences, agricultural management, and governance. In particular, we addressed questions of quantification, additionality, permanence, changes in emissions, leakage effects, transparency, legitimacy and accountability, as well as synergies and trade-offs with other societal targets.

Soil properties and the mechanisms by which carbon is stored in soils have strong implications for the assessment. Soils have a limited storage capacity, and SOC is not sequestered but its SOC stocks are the dynamic result of plant derived inputs and losses mainly in the form of microbial respiration. The higher the SOC stock, the higher the annual carbon inputs that is needed to maintain it. If carbon friendly management is discontinued, elevated SOC levels will therefore revert to their original level.

We found that while changes in agricultural management that increase SOC are highly desirable and offer multiple-co benefits with climate change adaptation, soil carbon certificates are unsuitable as a tool. They are unlikely to deliver the climate change mitigation they promise as certificate providers cannot guarantee permanence and additionality of SOC storage over climate relevant time-frames. Where the certified carbon storage is non-permanent or fails to meet criteria of additionality, the use of such certificates to advertise products as “carbon-neutral” may be construed as false advertising.

How to cite: Paul, C., Don, A., Bartkowski, B., Wiesmeier, M., Weigl, S., Mayer, S., Steffens, M., Wolf, A., Dönmez, C., and Helming, K.: Suitability of soil carbon certificates for climate change mitigation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10433, https://doi.org/10.5194/egusphere-egu22-10433, 2022.

Globally, there is clear evidence that unsustainable urbanisation and climate change are pressing challenges for our systems. Nature-based Solutions are starting to be considered as a mechanism to help underpin and tackle societal and global challenges such as biodiversity loss, ecosystem depletion, resource use or human and ecological well-being. Nevertheless, still disciplines are working separately and enabling the co-design of Nature-based Solutions to reach sustainable urban planning in cities is far to be considered for climate adaptation and climate neutrality in cities. Therefore, the study intends to overcome those research gaps mentioned. On the way to tackle those issues, the paper frames the necessity to align science, policy and society goals to reach a sustainable future and bring sectors together to ensure and help build an inclusive, healthy and a resilient world. The methodology is based on a systematic review process where we explore the state of the art on the matter. This paper intends to open the discussion of a holistic, systemic and comprehensive approach to mainstreaming Nature-based Solutions  and  presents a novel pathway for transdisciplinary climate and environmental planning action. A novel conceptualization; socio-ecological and environmental-economic framework for Nature-based Solutions action plan with defined key principles to enable the mainstreaming of nature-based solutions into policies and governance. The study recommends and proposes specific nature-based solutions strategies to underpin the lack of coherence that sometimes shows in some approaches when designing and planning cities, implementing policies for sustainable urban planning and design, facilitating ecosystem restoration and human well-being. To reach an environmentally, socially, economically, locally, ecologically and politically sustainable, circular and resilient Europe by 2030 to help deliver the global policy agendas and the European Green Deal and its strategies.

How to cite: Garcia Mateo, M. C. and Tillie, N.: Enabling the mainstreaming of nature-based solutions into policy-making and governance: Holistic and systemic approach and coherence across policies to build a sustainable, circular and resilient planet and tackle societal challenges, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10493, https://doi.org/10.5194/egusphere-egu22-10493, 2022.

EGU22-10608 | Presentations | ITS4.4/ERE1.10

Earth Climate Optimisation Productivity Island Array (ECOPIATM) 

John Allen, Calum Fitzgerald, and Lonnie Franks

A new nature based solution for capturing the entire man-made emission of carbon dioxide per year and locking it away in the deep ocean, called ECOPIATM, has been devised by a marine think tank, MyOcean Resources Ltd. This is a global solution to the anthropogenic climate change problem, without environmental downsides - it provides the fix. By using the characteristics of the Ocean, ECOPIATM removes the excess atmospheric CO2, de-acidifies the ocean’s waters, creates new sustainable fisheries, and most importantly allows the economies of the world to continue to grow and prosper.

ECOPIATM is able to address the anthropogenic climate change problem whilst having a positive global impact on economic growth. It enables continued economic growth for all nations by balancing the problem of excess atmospheric CO2 rather than following strategies that require a reduction in economic activities. Trying to reduce the amount of excess CO2 emitted by economies can be considered the biggest waste management issue the world has to solve; however current strategies have had trouble getting traction due to their negative impact on economic growth. 

By transillumination of the giant deserts of the Ocean, we can reduce the amount of atmospheric CO2 at the same time as de-acidifying the oceans, by empowering natural oceanic primary productivity simply through the provision of light. This allows ECOPIATM to be an effective CO2 waste management solution for the atmosphere. Rather than having to harm economic growth through difficult to achieve emissions reductions, companies can work with ECOPIATM to genuinely offset their atmospheric CO2 emissions, through photosynthetic CO2 uptake.

These enormous deserts of the sub-tropical open oceans, one seventh (~ 50 million km2) of the whole of the Earth’s ocean area, are reportedly getting bigger; with productive surface waters being replaced by an increase in the minimally productive surface waters of the oligotrophic gyres, at a rate of 0.8 million km2 per year . ECOPIATM in total only requires 0.2 million km2 of those gyres, just one quarter of the current increase in area per year.

Many of the nature based solutions have significant uncertainties that largely come about from the farming-like practise of changing the composition of the ‘soil’ or in this case the ocean waters. ECOPIATM takes a different approach, that of channelling light down to the depths where there are plenty of naturally determined nutrients and seed population, thus we are no longer ‘farming’ we are simply providing light. Furthermore, as there is no strict geo-engineering involved, ECOPIATM provides no mechanism for a preferential pressure on the naturally determined diversity of the light cultured ecosystem.

It has been noted by the UK's, HRH the Prince of Wales, amongst others, that the global anthropogenic climate change issue can only be solved by Industry. ECOPIATM stands out in that it is self-fundable, both in infrastructure and operational costs, via the use of Carbon Credits at today’s prices, allowing Industry to solve the issue in an affordable way.

How to cite: Allen, J., Fitzgerald, C., and Franks, L.: Earth Climate Optimisation Productivity Island Array (ECOPIATM), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10608, https://doi.org/10.5194/egusphere-egu22-10608, 2022.

EGU22-11878 | Presentations | ITS4.4/ERE1.10

N2O-emission risk assessment tool for nitrogenous fertilizer applications 

Henrik Vestergaard Poulsen, Sander Bruun, Cecilie Skov Nielsen, and Søren Kolind Hvid

Nitrous oxide (N2O) emitted from agricultural soils makes up a significant part of the collective agricultural greenhouse gas (GHG) emissions. These emission are to a large extent caused directly or indirectly by the application of nitrogenous fertilizer and there is a strong demand for mitigation strategies.

 

Nitrous oxide is produced in the soil in a range of different processes but mainly in microbial nitrification and denitrification. A number of factors exert influence on these microbial processes in the soil, most notably the oxygen concentration, availability of ammonium and nitrate, available organic matter and diffusivity, and fairly advanced process-based simulation models are often used in attempts to simulate the amount of N2O emitted. Here we propose using more a simplistic modelling approach to provide a novel risk assessment tool for nitrogenous fertilizer applications to be implemented in Danish farmers field management programmes.

 

At SEGES Innovation we have unique database access to field activity data from Danish farmers - e.g. crop sequence, fertilizer applications, residue handling, soil texture - covering more than 85 % of the Danish cultivated area. Based on these data and field specific climate data, a soil water balance model (Plauborg et al. 1995) and soil organic carbon model (Taghizadeh-Toosi et al. 2014) are running in daily timesteps for all fields in the database. These models provide, respectively, the daily level of WFPS in the soil and the organic matter turnover rate in the soil simulated during the weather forecast period of 10 days. Those two outputs are combined with a simulated soil temperature in a simplified version of the NGAS-model (Parton et al. 1996) to give a rough simulated N2O-emission for any planned fertilizer application throughout the weather forecast period.

 

The risk assessment tool exhibits this daily simulated N2O-emission as a risk evaluation of fertilizer application to the farmer in field management programmes, where future field activities are entered and logged. The objective is to lower the GHG emission by reducing the number of fertilizer applications right at peak N2O-emission conditions, once the farmers are presented with this information.    

How to cite: Vestergaard Poulsen, H., Bruun, S., Skov Nielsen, C., and Kolind Hvid, S.: N2O-emission risk assessment tool for nitrogenous fertilizer applications, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11878, https://doi.org/10.5194/egusphere-egu22-11878, 2022.

The deployment of carbon dioxide removal (CDR) processes is required, as well as strong and immediate emission reductions, to limit the global temperature increase “well below to 2°C above pre-industrial levels” as required by the Article 2 of the Paris Agreement.

Among the CDR processes, ocean alkalinity enhancement (OAE) allows to remove CO2 from the atmosphere and simultaneously to counteract the ongoing ocean acidification caused by the increased CO2 atmospheric concentration. In the framework of the DESARC (DEcreasing Seawater Acidification Removing Carbon) MARESANUS research project, different strategies to produce decarbonized slaked lime (SL), i.e. Ca(OH)2, and to discharge it in the seawater have been evaluated.

The feasibility and the potential of OAE were evaluated at the global scale and at the Mediterranean Sea basin scale. Two different logistic scenarios for the discharge of SL were analyzed: new dedicated ships, and partial load on modified existing dry bulk and container ships. The data on the existing global fleet of vessels and marine routes has been elaborated to assess the potential discharge of SL.

Through the life-cycle assessment methodology, the efficiency of removing CO2 from the atmosphere was evaluated, as well as other potential environmental impacts connected to SL production and transport. The “cradle-to-grave” approach has been applied to different configurations of the process, that consider both biomass gasification and the use of renewables as a source of energy for limestone calcination, as well as eventual CO2/H2 separation and CO2 storage.

The data collected for the life cycle inventory were mainly obtained from the preliminary design of the process and the scientific literature, as well as from the ecoinvent database. According to the environmental footprint method implemented in SimaPro software, sixteen impact categories for assessing the burdens on the environment and human are evaluated, with a particular focus on Climate change, Land use,  and Mineral and metals use.

The results show that for all the analyzed configurations, the process has a potential negative impact on the Climate change category, i.e. there is a benefit for the environment in terms of CO2 removal from the atmosphere. Since the avoided impacts are related to the source for hydrogen, the type of avoided source has a relevant role and is subjected to a sensitivity analysis.

Finally, the availability of limestone for the large-scale development of ocean alkalinisation have been evaluated, considering in particular the deposits of pure limestone near the coastlines, that  could minimize logistic and transportation activities.

Results show that pure carbonate potential resources are of several trillion tons and are not a constraint for the development of global-scale ocean liming. A large part of pure limestone resources is nearby the coastline, in areas with no or low vegetation cover, mainly in North Africa and Iran. Global limestone yearly production is similar to coal, and the required upscaling compared to the current extraction rate is far lower for limestone than for other materials considered for OAE, such as olivine, magnesite and brucite.

How to cite: Campo, F. P., Caserini, S., and Grosso, M.: Feasibility, potential and environmental impacts of ocean alkalinity enhancement for removing CO2 from the atmosphere and counteracting seawater acidification, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12467, https://doi.org/10.5194/egusphere-egu22-12467, 2022.

EGU22-12839 | Presentations | ITS4.4/ERE1.10 | Highlight

"The Arctic - the first step towards the terraformation of Mars. Experiences from northern Europe." 

Adrianna Rusek and Miłosz Huber

The Arctic is an area with unique climatic qualities on Earth. Located behind the Arctic Circle, the region is characterized by numerous phenomena such as polar day (in summer) and polar night (in winter), which affect the state of well-being of people living there. The numerous aurorae are examples of magnetic storms whose health effects are most pronounced in this region. Extreme temperatures can be recorded in these zones, especially in winter. At the same time, it is there that the environment shows great sensitivity to changing climatic conditions and human activities. A small increase in temperature can melt permafrost and methane clathrates. At this time, climate change affects the ecosystem of the plant and animal world. At the same time, it is in the Arctic that there are important deposits of energy resources, non-ferrous metals and others. In the Arctic regions there are trade routes connecting the continents (the so-called "Northern Road"). Growing interest in the Arctic contributes to its urbanization. This process is also important in a broader context. Many of the technologies that prove themselves in these harsh conditions will also be applicable in other climate zones. The Arctic is becoming a testing ground for human missions in harsh conditions, a way to survive in an unfavorable climate, and to test pro-environmental technologies. An important advantage of the Arctic is also its great similarity to the climatic conditions of the warmest zones on Mars. However, compared to Mars, planning engineering projects in the Arctic has many advantages. The presence of air at normal pressure, while not preventing the construction of airtight capsules, allows for easier evacuation of personnel in the event of a failure of life support systems.  Working people at various stations in the Arctic can be just as tested for the vulnerability of long periods of being in a small confined space. Nevertheless, there are also numerous localities in the Arctic where people lead relatively normal lives, the best example being northern Scandinavia, which is currently the most urbanized area beyond the Arctic Circle.  Their experience of living in the extreme conditions of the north, the problems of urban development and transportation, environmental protection and many other areas of life in this zone, can be an important source of information for other inhabitants of Earth and Mars.  Issues related to the problems of environmental protection and the fight against pollution in this climate zone will be just as relevant in other zones, where there are many more opportunities to use, for example, renewable energy sources. In the long run, building stable urbanized human settlements in the Arctic will become an example of human activity in the region of Mars and (perhaps) other regions of the Solar System. The authors present numerical data and possible scenarios of sustainable urbanization development in the Arctic based on selected examples of Scandinavian experience. They analyze which of them have universal character and are possible to apply also in other climatic conditions. 

How to cite: Rusek, A. and Huber, M.: "The Arctic - the first step towards the terraformation of Mars. Experiences from northern Europe.", EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12839, https://doi.org/10.5194/egusphere-egu22-12839, 2022.

EGU22-13010 | Presentations | ITS4.4/ERE1.10

Scientific evidence of the economic benefits of ecosystem-based disaster risk reduction and ecosystem-based climate change adaptation 

Marta Vicarelli, Michael Kang, Madeline Leue, Aryen Shrestha, David Wasielewski, Karen Sudmeier-Rieux, Jaroslav Mysiak, Simon Schütze, Michael Marr, Shannon McAndrew, and Miranda Vance

Ecosystems and ecosystem services are key to helping achieve reduction in disaster risk, sustainable development, and climate change adaptation, and this is now recognized by major international framework agreements (Convention on Biological Diversity, 2014; United Nations Office for Disaster Risk Reduction, Sendai Framework for Disaster Risk Reduction, 2015-2030). However, there is limited knowledge about the cost efficiency and socio-economic equity outcomes of Nature-based Solutions (NbS) compared to traditional engineered strategies.

In this study we developed a global database of more than 130 peer-reviewed studies, published between 2000 and 2020, that perform economic evaluations of NbS for Ecosystem-based Climate Adaptation (EbA) and Ecosystem-based Disaster Risk Reduction (Eco-DRR). Using meta-analysis techniques, we assess the existing scientific knowledge on the economic viability and performance of NbS for Eco-DRR and EbA, cataloguing outcomes both in terms of degree of economic efficiency and social equity. Our analysis includes multiple dimensions: geographic distribution of the published studies, types of ecosystems and ecosystem services evaluated, hazards and climate impacts analyzed, and economic methodologies used to perform economic efficiency evaluations (e.g., cost benefit analysis, stated/revealed preferences evaluation methods).

This study builds on a recent global assessment (Sudmeier-Rieux et al, 2021) that performs the first systematic review of Eco-DRR peer-reviewed studies across all disciplines. Their results show robustness of evidence and level of agreement on the role of ecosystems in attenuating 30 types of hazards, based on the assessment methodology established by the Intergovernmental Panel on Climate Change (IPCC). Our meta-analysis expands the 2021 review by evaluating the economic benefits associated with Eco-DRR and NbA approaches; by examining cost efficiency of Eco-DRR and NbA interventions compared to traditional engineering solutions; by performing equity assessments of the outcomes; and by studying how the NbS interventions reviewed contributed to the sustainable development goals (SDGs).

REFERENCE:

Sudmeier-Rieux, K., Arce-Mojica,T., Boehmer, H.J., Doswald, N., Emerton, L., Friess, D.A., Galvin, S., Hagenlocher, M., James, H., Laban, P., Lacambra, C., Lange, W., McAdoo, B.G., Moos, C., Mysiak, J., Narvaez, L., Nehren, U., Peduzzi, P1., Renaud, F.G., Sandholz, S., Schreyers, L., Sebesvari, Z., Tom, T., Triyanti, A., van Eijk, P., van Staveren, M., Vicarelli, M., Walz, Y. "Scientific evidence for ecosystem-based disaster risk reduction." Nature Sustainability (2021): 1-8. 

How to cite: Vicarelli, M., Kang, M., Leue, M., Shrestha, A., Wasielewski, D., Sudmeier-Rieux, K., Mysiak, J., Schütze, S., Marr, M., McAndrew, S., and Vance, M.: Scientific evidence of the economic benefits of ecosystem-based disaster risk reduction and ecosystem-based climate change adaptation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13010, https://doi.org/10.5194/egusphere-egu22-13010, 2022.

EGU22-1425 | Presentations | ITS4.2/ERE1.11

Optimal design of nature-based solutions in highway runoff management based on resilience to climate and pollution load changes 

Mehrdad Ghorbani Mooselu, Helge Liltved, Mohammad Reza Alizadeh, and Sondre Meland

Sedimentation ponds (SPs) are nature-based solutions (NBSs) for sustainable stormwater management. SPs control the quantity and quality of runoff and promote biodiversity. Hence, the optimal design of SPs is crucial for ecosystems resilience in urban and natural environments. This study aims to optimize the design of roadside SPs in terms of location and surface area, considering the resilience to stressors such as climate changes and pollution load variations. Accordingly, the highway runoff in a new 22 km highway (E18 Arendal-Tvedestrand) in southern Norway was simulated by the storm water management model (SWMM). The quantity and quality (BOD and TSS values) of highway runoff in all probable scenarios of existing uncertainties were estimated for potential outfall points using the repeated execution model of SWMM coded in MATLAB®. The scenarios were defined based on applying best management practices (BMPs), including grass swale and infiltration trench in different sections of the road that work before SPs, climatic (rainfall quantity estimated by the LARS-WG model), and modeling uncertainties (buildup and washoff coefficients). The generated dataset was then applied to assess the resilience of sedimentation ponds in potential outfalls to climate change and pollution load shocks. The resiliency was quantified for three metrics, including the quantity and quality of receiving runoff to sedimentation ponds and biodiversity in ponds over 25 years (2020-2045). The biodiversity index was defined based on Shannon's Entropy computed from field observation in 12 highway sedimentation ponds across Norway. Using this procedure, it was determined that the proper arrangement of BMPs along the road and the optimal design of ponds enhance the resilience of SPs by 40% over time. This study makes important contributions to stormwater management, the resilient design of NBS, and achieving UN SDG6 (Clean water and sanitation).

How to cite: Ghorbani Mooselu, M., Liltved, H., Alizadeh, M. R., and Meland, S.: Optimal design of nature-based solutions in highway runoff management based on resilience to climate and pollution load changes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1425, https://doi.org/10.5194/egusphere-egu22-1425, 2022.

EGU22-1677 | Presentations | ITS4.2/ERE1.11

Effects of land use change for solar park development in the UK on ecosystem services 

Fabio Carvalho, Hannah Montag, Stuart Sharp, Piran White, Tom Clarkson, and Alona Armstrong

In the rush to decarbonise energy supplies to meet internationally agreed greenhouse gas emissions targets, solar parks (SPs) have proliferated around the world, with uncertain implications for the provision of ecosystem services (ES). SPs necessitate significant land use change due to low energy densities that could significantly affect the local environment. In the UK, SPs are commonly built on intensive arable land and managed as grasslands. This offers both risks and opportunities for ecosystem health, yet evidence of ecosystem consequences is scarce. Therefore, there is an urgent need to understand how ES assessments can be incorporated into land use decision making to promote SP development that simultaneously addresses the climate and biodiversity crises. We aim to provide some of the first scientific evidence to help answer this question by determining the effects of land use change for SPs in the UK on the provision of ecosystem services (e.g., biomass production, soil carbon storage) of hosting ecosystems. Through a Knowledge Transfer Partnership project between Lancaster University and Clarkson & Woods Ecological Consultants, 35 SPs in England and Wales were surveyed in summer 2021. Soil and vegetation data were collected from 420 sample plots (900 cm2) under different types of land use: underneath solar panels, between rows of solar arrays, and control sites (e.g., pastureland, areas set-aside for conservation). Total plant cover was significantly lower underneath solar panels and between solar arrays than on land set-aside for conservation, while land around the margins of SPs showed higher aboveground biomass of monocotyledons and forbs than on land underneath solar panels. Some measures of soil fertility (e.g., nitrogen) and soil organic matter, fractioned into particulate and mineral-associated organic matter, also varied significantly between these different land uses. These results have implications for land management within SPs and will enable optimisation of SP design and management to ensure the long-term delivery of ecosystem services within this fast-growing land use.

How to cite: Carvalho, F., Montag, H., Sharp, S., White, P., Clarkson, T., and Armstrong, A.: Effects of land use change for solar park development in the UK on ecosystem services, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1677, https://doi.org/10.5194/egusphere-egu22-1677, 2022.

EGU22-2049 | Presentations | ITS4.2/ERE1.11

What locals want: (mapping) citizen preferences and priorities for an alpine river landscape 

Chiara Scaini, Ana Stritih, Constance Brouillet, and Anna Scaini

Sustainable river management frameworks are based on the connection between citizens and nature. So far, though, the relationship between rivers and local populations has played a marginal role in river management. We present a blueprint questionnaire to characterize the perception of cultural ecosystem services and flood risk by locals, and how preferences change across the river landscape. We investigate how locals value the river and whether their preferences are affected by characteristics such as place of residence, age, frequency of visits and relation to the river. The approach is tested on the Tagliamento river, the last major free-flowing river in the Alps, which is characterized by debates on flood protection, flood management and ecological conservation. The questionnaire was filled in by more than 4000 respondents, demonstrating huge interest and willingness to contribute with their opinion on this topic. A participatory map of favorite places shows that most of the river is valued/appreciated by locals, with a high preference for the landscape of the braided middle course. River conservation is the main priority for most respondents across different stakeholder groups, highlighting the need for nature-based solutions in flood-risk management and demonstrating the mismatch between management choices and citizens´ values and priorities. Land-use planning is identified as a factor that can increase flood risk. The results highlight the necessity to tackle conservation, risk management and land-use planning together in order to develop risk-oriented river management strategies. More generally, this work points out that any river intervention should be pondered carefully accounting for its environmental impact also in terms of loss of cultural ecosystem services.

How to cite: Scaini, C., Stritih, A., Brouillet, C., and Scaini, A.: What locals want: (mapping) citizen preferences and priorities for an alpine river landscape, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2049, https://doi.org/10.5194/egusphere-egu22-2049, 2022.

Check dam plays a crucial role in controlling soil erosion on the Loess Plateau and reducing sediment loads in the Yellow River. Moreover, sediment deposition in check dams also provides valuable information for understanding of soil erosion on the Loess Plateau. Study on the influence of rainfall patterns on sediment yield in small catchments scale is significant for the reasonable arrangement of soil and water conservation measures, particularly for complex environments such as the wind-water erosion crisscross region. This study estimated sediment yield trapped by the check dam in Laoyeman catchment based on deposited flood couplets formed in erosion rainfall events during the period 1978-2010. All erosive rainfall were divided into three rainfall patterns according to the precipitation, rainfall duration and rainfall erosivity, and the correspondence analysis between sediment yield and rainfall pattern was analyzed. Results showed that there were 1.1´105 t sediment deposited in the dam filed during the trapping history of the check dam as a whole. It has three obvious change stages, which had sediment yield of 4.53´104 t during 1978-1988, 4.48´104 t during 1988-1997, and 1.68´104 t during 1997-2010, respectively. The stage 1989-1997 had the fastest annual deposition rate of 4.98×103 t·year-1, 20.9% and 286% faster than stage 1978-1988 and stage 1998-2010. For similar rainfall pattern in these three stages, sediment yield and the characteristic of flood couplet change were closely related to both rainfall erosivity and land use types. This was also approved by the significant decrease of sediment yield on condition of similar rainfall pattern in a decade before and after the implementation of Grain for Green project indicated that this project made a great contribution to the control of soil erosion on the Loess Plateau. The impact of rainfall pattern on sediment yield indicated that the largest sediment yield is initiated under short duration and high intensity rainfall events, while the sediment in the reservoir area is mainly deposited under the rainfall pattern of moderate precipitation, erosivity and duration. That is the reason for the wettest year (1995) had relatively low sediment deposition, while the year (1982) had strong rainfall erosivity had the maximum annual sediment yield (1.68´104 t).

How to cite: Yin, M. and Zhang, J.: Influence of rainfall patterns on sediment yield in flood couplets of a check dam on the Chinese Loess Plateau, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3322, https://doi.org/10.5194/egusphere-egu22-3322, 2022.

EGU22-3770 | Presentations | ITS4.2/ERE1.11

The approach ‘think global, act local’ neglects the particular ecological value of ecosystems 

Guido J.M. Verstraeten and Willem W. Verstraeten

A sustainable society is considered as an organic system, called an ecosystem, wherein all possible connected parameters are contributing to the conservation and evolution of the ecosystem containing life and landscape against stress from outside. Any ecosystem contains species of mutually interacting organisms all contributing to a dynamic equilibrium. An ecosystem is characterized by a population carrying capacity.

Humans are the only species on earth without a specific ecosystem. They live everywhere. The evolution did not adapt the homo sapiens to some ecosystem, on the contrary humans transformed all ecosystems to their own environment. Nature transforms into environment when humans are managing an ecosystem and transform it to their environment by attributing to nature the concept of natural capital as first instrumental step to economic growth, considering pollution as collateral damage.

Inspired by Enlightenment Anthropology (Shallow Ecology and Naess´ Deep Ecology) the UN encourages humanity to transform the consumption of raw matter, energy and food into a more sustainable cleaner way and even to start transition of energy resources and human diet in order to dampen the effects of global warming. Economic policy supports technological procedures avoiding waste of raw material and stimulating sustainable production processes and sustainable recuperation of raw material inside the produced items. The energy transition and preferable industrial production method, however, is globally imposed top-down without examining the consequences for local life of humans, non-humans (e.g. wind turbines near human settlement, bird mortality, destruction of the ecosystems of the seafloor) and the landscape (e.g. solar energy systems on hillside, water dams). Moreover, the global view favors large scale in policy as well as in means of production. However, this global transition organization of the global environment establish the new order characterized by its global and universal action and is not in balance with local ecosystems characterized by diversity of life and human management (so called perverted adaptation). Nature is reduced to things and just rewarded in terms of natural capital to sustain a Global Urban Middleclass consumptive society.

Therefore, we adopt Aldo Leopold ‘Land ethics’ (1949) and apply it to the shear coast of Southwestern Finland. We summarize his ideas in three hot headlines: (i) The land ethic changes the role of Homo sapiens from conqueror of the land-community to plain member and citizen; (ii) We abuse land because we regard it as a commodity belonging to us. When we see land as a community to which we belong to, we may begin to use it with love and respect; (iii) Anything is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise. Participation to the ecosystem based on autonomous technology, i.e. not controlled, is focused on global energy transition to save the Universal Urban Middleclass Life. On the contrary, the concept of Land Ethics makes room for eco-development based on care for humans, culture, environment and nature in interaction with all ecosystems. In a nutshell: act local, interact global.

How to cite: Verstraeten, G. J. M. and Verstraeten, W. W.: The approach ‘think global, act local’ neglects the particular ecological value of ecosystems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3770, https://doi.org/10.5194/egusphere-egu22-3770, 2022.

EGU22-3784 | Presentations | ITS4.2/ERE1.11

Assessing the interconnections between the characteristics, perception, and valuation of Nature-Based Solutions: A case study from Aarhus, Denmark 

Martina Viti, Roland Löwe, Hjalte J.D. Sørup, Ursula S. Mcknight, and Karsten Arnbjerg-Nielsen

When assessing strategies for implementation of Nature-Based Solutions (NBS) it is fundamental to quantify all benefits for securing better, informed decision making. Particularly relevant is the quantification of their multiple co-benefits for communities and the environment. One of the most widespread techniques to quantify these values is to use contingent valuation (CV) methods, such as the Willingness-To-Pay (WTP) approach. Within the CV method, questionnaires are the main tool used to elicit the value attributed to a specific good by the respondents. However, many studies focus on site-specific economic valuation, whereby transferability to other locations is jeopardized. We therefore created a survey to explore how the valuation of an NBS is shaped by its relationship with the users (e.g. frequency and length of visits), and how these responses are linked to both the respondents and the sites’ characteristics (e.g. socio-economic status, size of the NBS, etc.).

We applied this method to a case study comprised of two distinct areas located in Aarhus, Denmark, asking users to explore their perception of the two NBS sites with different features. Both NBS sites have as overarching goals to (i) prevent flooding from cloudburst or water bodies, (ii) improve the biodiversity in the area, and (iii) benefit the local population, e.g. by providing more recreational areas. Despite these common goals, the two sites differ by a number of characteristics, i.e. size, location, and time passed since construction. One NBS involves a large artificial lake in a peri-urban setting, while the other is a small urban park. Respondents were allowed the option of either expressing a value for only one, or for both of the sites. 

We analyzed both responses that stated a WTP and protest votes, that is, responses that rejected the valuation scenario altogether. We found that older citizens are more likely to protest, as well as those not visiting the sites. For the respondents who accepted to state a WTP, their bids significantly increased when the improvement of nature and biodiversity was mentioned in the valuation scenario. Comparing the value given to the two different sites, the characteristics of the NBS seem to play a role in the respondents’ perception and use of the sites, which in turn enhances valuation. In our case study, people’s perception of the site and their relationship with it appear to have a stronger link with the WTP than their socio-economic characteristics. Specifically, frequency and length of visits, and interest in a good quality of nature were mostly related to a positive WTP.

The inclusion of people-NBS relational variables in benefit quantifications appears to be an essential tool to realize a more realistic economic valuation, as well as correctly design NBS in order to achieve the desired impacts. Understanding the underlying synergies between the multiple co-benefits of NBS, their features and the users’ perception is decisive for maximizing these strategies’ potential and avoiding missing opportunities.

How to cite: Viti, M., Löwe, R., Sørup, H. J. D., Mcknight, U. S., and Arnbjerg-Nielsen, K.: Assessing the interconnections between the characteristics, perception, and valuation of Nature-Based Solutions: A case study from Aarhus, Denmark, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3784, https://doi.org/10.5194/egusphere-egu22-3784, 2022.

EGU22-4971 | Presentations | ITS4.2/ERE1.11

Integrating remote sensing and social media data advances assessment of cultural ecosystem services 

Oleksandr Karasov, Stien Heremans, Mart Külvik, Artem Domnich, Iuliia Burdun, Ain Kull, Aveliina Helm, and Evelyn Uuemaa

Over the past decade, we witnessed a rapid growth in the use of social media data when assessing  cultural ecosystem services (CESs), like modelling the supply-demand relationships. Researchers increasingly use user-generated content (predominantly geotagged pictures and texts from Flickr, Twitter, VK.com) as a spatially explicit proxy of CES demand. However, for modelling CES supply most of such studies relied on simplistic geospatial data, such as land cover and digital elevation models. As a result, our understanding of the favourable environmental conditions underlying good landscape experience remains weak and overly generic.

Our study aims to detect the spatial disparities between population density and CES supply in Estonia in order to prioritise them for further in-depth CES assessment and green and blue infrastructure improvements. We relied on Flickr and VK.com photographs to detect the usage of three CESs: passive landscape watching, active outdoor recreation, and wildlife watching (biota observations at organism and community levels) with automated image content recognition via Clarifai API and subsequent topic modelling. Then, we used Landsat-8 cloudless mosaic, digital elevation and digital surface models, as well as land cover model to derive 526 environmental variables (textural, spectral indices and other indicators of landscape physiognomy) via the Google Earth Engine platform. We conducted an ensemble environmental niche modelling to analyse the relative strength and directions of relationships between these predictors and the observed occurrence of CES demand. Based on multicollinearity and relative importance analysis, we selected 21 relevant and non-collinear indicators of CES supply. With these indicators as inputs, we then trained five models, popular in environmental niche modelling: Boosted Regression Trees, Generalized Linear Model, Multivariate Adaptive Regression Spline, Maxent, and Random Forest. Random Forest performed better than the other models for all three CES types, with the average 10-fold cross-validation area under curve > 0.9 for landscape watching, >0.87 for outdoor recreation, and >0.85 for wildlife watching. Our modelling allowed us to estimate the share of the Estonian population residing in the spatial clusters of systematically high and low environmental suitability for three considered CESs. The share of the population residing in the clusters of low environmental suitability for landscape watching, outdoor recreation, and wildlife watching is 5.5%, 3.1%, and 7.3%, respectively. These results indicate that dozens of thousands of people in Estonia (population is >1.3 million) likely have fewer opportunities for everyday usage of considered CESs. However, these results are biased as there was not enough evidence in social media for CES use in some of these areas.

Although our results should be treated with caution, because social media data are likely to contain a considerable sampling bias, we have demonstrated the added value of remote sensing data for CES supply estimation. Given nearly global and continuously updated satellite imagery archives, remote sensing opens new perspectives for monitoring the loss and gains in landscape suitability for CES across temporal and spatial scales. As such, we can better account for the intangible underlying geospatial features that can influence  economic and environmental decision-making.

How to cite: Karasov, O., Heremans, S., Külvik, M., Domnich, A., Burdun, I., Kull, A., Helm, A., and Uuemaa, E.: Integrating remote sensing and social media data advances assessment of cultural ecosystem services, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4971, https://doi.org/10.5194/egusphere-egu22-4971, 2022.

EGU22-6317 | Presentations | ITS4.2/ERE1.11

Effect of soil management practices on soil carbon dynamics under maize cultivation 

Michael Asante, Jesse Naab, Kwame Agyei Frimpong, Kalifa Traore, Juergen Augustin, and Mathias Hoffmann

An increasing world population and change in consumer preferences necessitate the need to increase food production to meet the demand of a changing world. Intensified agriculture and an accelerated climate crisis with increasing weather extremes threaten the resource base needed to improve crop production. Maize yield obtained by farmers in the guinea savannah zone of Ghana is generally low due to low soil fertility status resulting from continuous cropping coupled with low use of external inputs. Integrated Soil Fertility Management (ISFM) practices have proven to sustainably increase maize yield. However, majority of the farmers practicing ISFM till their land conventionally, potentially resulting in substantial greenhouse gases (GHG) emissions that contribute to global climate change. However, there is dearth of information on GHG emissions regarding crop production systems in sub-Saharan Africa in general and Ghana in particular. Hence, within a field trial we seek to investigate the impact of different tillage practices and ISFM applied to sustain maize yield, on net CO2 or ecosystem exchange (NEE) and net carbon (C) balance (NECB). The field trial was established at the Council for Scientific and Industrial Research-Savanna Agricultural Research Institute in Northern region of Ghana. A split plot design was used with the main plot treatments being conventional tillage and reduced tillage and the subplot treatments being factorial combination of organic and inorganic fertilizers at three levels each. To determine NEE and thereon based estimates of NECB, an innovative, customized, low-cost manual, dynamic closed chamber system was used. The system consists of transparent (V: 0.37 m3, A: 0.196 m2; for NEE measurements) and opaque chambers (for ecosystem respiration (Reco) measurements) of the same size. Diurnal regimes of Reco and NEE fluxes were measured twice a month by repeatedly deploying chambers for 5 to 10min on the 3 repetitive measurement plots (PVC frames inserted 5 cm deep into the soil as collars) per treatment. CO2 concentration increase and decrease over chamber deployment time was detected by portable, inexpensive Arduino based CO2 logging systems, consisting of a battery powered microcontroller (Arduino Uno) and data logging unit (3 sec frequency) connected to an NDIR-CO2 sensor (SCD30; ± 30 ppm accuracy), air temperature and humidity (DHT-22) as well as air pressure sensor (BMP280). Measured CO2 fluxes were subsequently gap-filled to obtain seasonal NEE. C import and export were further on added to NEE to determine the NECB for each treatment. In parallel to CO2 exchange measurement campaigns, agronomic and crop growth indices such as the normalized difference vegetation index (NDVI) were performed biweekly at all plots. Here we present NEE and NECB balances for the first crop growth period.

Keywords: Tillage, Integrated soil fertility management, CO2 emission, Zea mays, net ecosystem carbon balance (NECB)

How to cite: Asante, M., Naab, J., Agyei Frimpong, K., Traore, K., Augustin, J., and Hoffmann, M.: Effect of soil management practices on soil carbon dynamics under maize cultivation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6317, https://doi.org/10.5194/egusphere-egu22-6317, 2022.

EGU22-7121 | Presentations | ITS4.2/ERE1.11

Application of the International Guidelines on Natural and Nature Based Features for Flood Risk Management and the way forward 

Ralph Schielen, Chris Spray, Chris Haring, Jo Guy, and Lydia Burgess-Gamble

In 2021, the International Guidelines on Natural and Nature Based Features for Flood Risk Management  were published, as a result of a joint project between the Rijkswaterstaat (Netherlands), the Environment Agency (England) and the Army Corps of Engineers (USA). These Guidelines give direction in the application of Nature Based Solutions (NBS) for coastal and fluvial systems. In this contribution we will focus on the fluvial part of the guidelines. We will briefly discuss the process that lead to the origin of the Guidelines and discuss the intended use. It is important to realize that the location within a catchment, and the scale of a catchment determine the specifications of the most optimal NBS. Considering the classical ‘source-pathway-receptor’ approach, in the source of a catchment, NBS aim to hold back the water in the headwaters of larger catchments, enhancing management of water and sediment. In the pathways-receptor (floodplains),  NBS are more focussed on increasing the discharge capacity of the main stem. In smaller catchments, also temporarily storage of water in the floodplains occurs, if flooding of such a temporary nature can be accommodated. Rather than a detailed instruction guide, the Guidelines are intended to give best practices and list important points of attention when applying NBS. Furthermore, they act as inspiration through the many case studies that are listed.

We will also connect the Guidelines to other initiatives on the application of NBS, for example the impact that NBS might have on reaching the United Nations Sustainable Development Goals. This requires a proper assessment framework which has been developed in adjacent projects and which values the added co-benefits that NBS have, compared to grey or grey-green alternatives. These benefits are also addressed in the Guidelines. Finally, we will share some thoughts on upscaling and mainstreaming NBS and the actions that are needed to accomplish that.

How to cite: Schielen, R., Spray, C., Haring, C., Guy, J., and Burgess-Gamble, L.: Application of the International Guidelines on Natural and Nature Based Features for Flood Risk Management and the way forward, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7121, https://doi.org/10.5194/egusphere-egu22-7121, 2022.

PHUSICOS platform aims at gathering nature-based solutions (NBS) relevant to reduce hydro-geological risks in mountain landscapes. The platform can be accessed directly through a web portal. It is based on an Open Source CMS website, including a filter to store documents and a map server to bring ergonomic and powerful access.

To design the platform, an in-depth review of 11 existing platforms has been performed.  Furthermore, a list of metadata has been proposed to structure the information. These metadata have provided the baseline for database. The PHUSICOS platform currently references 176 NBS cases and 83 documents of interest (review articles, assessment papers…). It is continuously enriched through the contribution of NBS community.

For that, a questionnaire based on relevant data, necessary for the definition and identification of the NBS (metadata, to be used for searching the NBSs within the platform) has been defined to enter new entries. A preliminary analysis of the cases has been realized. To characterize and analyse the current 152 solutions, we have worked on the following four categories: The nature of impacted ecosystems, The hazard(s) concerned, The other challenges treated by the NBS, The type of exposed assets.

The platform also proposes a qualitative assessment of the NBSs collected according to 15 criteria related with five ambits: disaster risk reduction, technical and economical feasibility, environment, society, and local economy. The criteria level is sufficiently general to be analysed for the entire PHUSICOS platform NBSs whatever the type of work, the realized approaches, the problematic or the spatial or temporal scale.

The structure of the platform and a first analysis of the qualitative NBS assessment are presented in this work.

How to cite: Bernardie, S., Baills, A., and Garçin, M.: PHUSICOS platform, dedicated to Nature-Based Solutions for Risk Reduction and Environmental Issues in Hilly and Mountainous Lands : presentation and qualitative NBS assessment, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7664, https://doi.org/10.5194/egusphere-egu22-7664, 2022.

An adequate strategy for water quality improvement in developing countries must consider the economic scarcity of water, the external factors that affect its quality, and the participation of multisectoral stakeholders in water management decisions. In addition, stronger links to nature can be established through methods inspired from nature to clean the water, such as artificial floating islands (AFI). Restoration of aquatic ecosystems with AFIs occurs as water passes beneath the floating mat and the roots of macrophytes take up metals and nutrients. In this context, we utilized Fuzzy Cognitive Maps (FCMs) to identify the principal concepts that affect water quality from different perspectives: political, economic, social, technological, environmental, and legal (PESTEL). We also theoretically explore the use of AFIs combined with different policies, to find the strategy that best adapts the local water situation.

By applying the principles of FCMs, different sources of knowledge can predict the effects of policy, and problems can be identified using the centrality index of the underlying graph theory. Thus, a two-step approach was implemented for our analysis: First, from 40 literature-based PESTEL concepts related to water quality deterioration, local experts in water management were invited to identify the most influential concepts and to include additional ones regarding the local water situation and policies to support the improvement of water quality. Second, workshops were organized, inviting members of communities to discuss the degree of cause-effect influence of the identified concepts, and also to include a water management policy, considering AFIs as one solution.

Three Ecuadorian communities distributed to cover representative ecosystems from the Pacific coast, Andean mountains, and Amazon floodplain were selected for this research, i.e. the community of Mogollón dominated by mangroves land cover, Chilla chico by páramos, and Awayaku by rainforest. According to the FCMs, 21 PESTEL concepts affect water quality in the páramos community and most of them are related to politics (23%) and the environment (23%). Community workshop at the same community identify that the major problem is related to natural water pollutants. For the mangrove community, 23 concepts were identified mainly driven (47%) by environmental concepts, whereas the communities see the major water quality issue in view of human exposure to environmental pollutants. In the case of the rainforest community, 19 concepts were recognized with 40% related to economics, whereas the communities identify the principal concern being the violation of environmental legislation. Regarding the potential implementation of AFIs, the páramos community concludes that AFIs should be implemented and coupled with environmental education programs. Additionally, water-related governmental institutions should be involved during realization. The mangrove community shows interest in AFIs, when combined with payment for ecosystem services. Finally, the rainforest community do not consider AFIs as a primary solution. Instead they propose the creation of a committee to denounce violations of water quality laws and to improve the educational level of community members. In conclusion, the FCM is a powerful tool to bring together the knowledge of multisectoral stakeholders and to analyse suitable strategies for the local improvement of water quality.

How to cite: Fonseca, K., Correa, A., and Breuer, L.: Using the fuzzy cognitive map approach to promote nature-based solutions as a strategy to improve water quality in Ecuadorian communities, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8395, https://doi.org/10.5194/egusphere-egu22-8395, 2022.

EGU22-8884 | Presentations | ITS4.2/ERE1.11

Effects of the Nature-Based Solutions on the ecosystem services; an evaluation of the Piave River catchment (Italy) in a 2050 scenario 

Francesco Di Grazia, Luisa Galgani, Bruna Gumiero, Elena Troiani, and Steven A. Loiselle

Sustainable river management should consider potential impacts on ecosystem services in decision-making with respect to mitigating future climate impacts. In this respect, there is a clear need to better understand how nature-based solutions (NBS) can benefit specific ecosystem services, in particular within the complex spatial and temporal dynamics that characterize most river catchments. To capture these changes, ecosystem models require spatially explicit data that are often difficult to obtain for model development and validation. Citizen science allows for the participation of trained citizen volunteers in research or regulatory activities, resulting in increased data collection and increased participation of the general public in resource management.

In the present study, we examined the temporal and spatial drivers in nutrient and sediment delivery, carbon storage and sequestration and water yield in a major Italian river catchment and under different NBS scenarios. Information on climate, land use, soil and river conditions, as well as future climate scenarios, were used to explore future (2050) benefits of NBS on local and catchment scales, followed the national and European directives related to water quality (Directive 2000/60/EC) and habitat (Directive 92/43/EEC). We estimate the benefits of individual and combined NBS approaches related to river restoration and catchment reforestation.

How to cite: Di Grazia, F., Galgani, L., Gumiero, B., Troiani, E., and Loiselle, S. A.: Effects of the Nature-Based Solutions on the ecosystem services; an evaluation of the Piave River catchment (Italy) in a 2050 scenario, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8884, https://doi.org/10.5194/egusphere-egu22-8884, 2022.

EGU22-9397 | Presentations | ITS4.2/ERE1.11

Analysis of survival probability on multiple species using metapopulation model 

Eun sub Kim, Yong won Mo, Ji yeon Kim, and Dong kun Lee

The ecological concept of the meta population helps evaluate the effectiveness of conservation areas (Soule et al., 1988), and is used as a useful tool for evaluating responses between individuals to artificial stressors such as urbanization, habitat destruction, and fragmentation (Kawecki. 2004). In particular meta population model can help increase the accuracy of population estimation across various spatial scales and explain several interactions populations (Walther et al., 2002; Faborg, 2014). Previous studies have demonstrated that habitat destruction and fragmentation caused by urbanization can affect the viability of species in habitats due to reduced fertility and mobility, but papers on the selection of conservation areas can increase the viability of multi species according to the changing surroundings are insufficient. Therefore, this study analyzed the possibility of multi species surviving in the habitat using a meta population model for conservation area scenarios and analyzed the effect of habitat pattern changes on each population from various perspectives.

In order to analyze the survival probability of multi species in habitats by conservation area scenario, (1) setting the 15 virtual habitat spaces within 160ha, (2) Big & Small conservation scenarios considering habitat area, connection, and connection, (3) collecting and estimation of migration rate, home range, dispersal distance for biological species for analyzing the possibility of extinction by population. Finally, the change in the population of each population during period t was analyzed using the meta population model.

Overall, when the Big Conservation area was applied, the probability of extinction of all species was low, followed by the Big+Connectivity scenario. In addition, the probability of survival was similarly derived in the Small scenario and the Connectivity scenario. However, the preferred conservation scenarios for each classification population group were different depending on the conservation scenario. In particular, birds had a high probability of extinction in the small scenario, while small mammals had a low probability of extinction. Through this study, the effect on the change in the number of multi species according to the conservation area scenario was analyzed, which is expected to be used to evaluate the validity and effectiveness of setting up a conservation area in the future.

How to cite: Kim, E. S., Mo, Y. W., Kim, J. Y., and Lee, D. K.: Analysis of survival probability on multiple species using metapopulation model, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9397, https://doi.org/10.5194/egusphere-egu22-9397, 2022.

EGU22-9474 | Presentations | ITS4.2/ERE1.11

Co-evaluating and -designing a Sustainable Agriculture Matrix for Austria in an international context 

Christian Folberth, Franz Sinabell, Thomas Schinko, and Susanne Hanger-Kopp

Agricultural ecosystems provide essential services mainly through food, feed, fiber and consequently income but they also contribute cultural, supporting and regulating services. In turn, farming can adversely affect ecosystem services, especially those from natural ecosystems, if farming practices are unsustainable.

Recently, a Sustainable Agriculture Matrix (SAM; https://doi.org/10.1016/j.oneear.2021.08.015) of indicators across environmental, economic, and social dimensions has been developed by an international research team to coherently quantify the sustainability of countries’ farming systems globally. The focus was on indicators that can be tracked over time and relate to performance to facilitate analyzes of synergies and trade-offs. At present, this indicator system is being co-evaluated with stakeholders in ten countries within an international consortium including Austria, to elicit stakeholders’ appraisal of the framework’s applicability in their specific geographical and socioeconomic context and eventually co-design a revised matrix based on stakeholders’ requirements.

A first workshop has shown that most indicators from the environmental dimension are useful for stakeholders in the Austrian context, but some need further refinements. Biodiversity, for example, is only considered via land cover change whereas threats to (agro-)biodiversity in Austria and the EU foremost occur in-situ. The economic dimension is ranking second in its usefulness for Austrian stakeholders with few indicators such as food loss being of little relevance. The indicators presently included in the social dimension are least relevant as they cover aspects such as land rights, undernourishment, and rural poverty, which do not pose major issues in Austria and more broadly the EU.

General concerns of stakeholders are the directionality of indicator ratings and their scope which is in part considered too narrow. E.g., high government expenditure for agriculture is considered positive in the matrix regardless of its purpose and may cause dependencies. Human nutrition is only included via undernourishment and soil nutrient status solely as surplus, whereas in both cases also the other extreme may be adverse. Accordingly, a bell-shaped indicator and rating would be favored in such cases. A general requirement was expressed for an additional context dimension. Governance arrangements and the overall socioeconomic situation are so far deliberately not included due to the focus on performance in the existing SAM. Yet, indicators describing such framework conditions can be essential to interpret synergies and trade-offs and the effectiveness of policy measures aiming at achieving SDGs. Beyond the evaluation of existing indicators, the stakeholder process yielded comprehensive suggestions for additional indicators, covering biodiversity, research and education, self-sufficiency, as well as various aspects of resilience and stability. Overall, the co-evaluation with stakeholders highlights that only few globally defined indicators are readily applicable in a regional context where consideration of local conditions and specifics is vital.

The proposed revisions are now being matched with available data across geographic scales to revise the matrix and perform further analyses on trade-offs and synergies. This will also include further context information to facilitate the evaluation of policies, ultimately allowing for improved policy-making to attain agricultural sustainability. Results will be further co-evaluated iteratively with stakeholders to eventually produce a globally applicable indicator system.

How to cite: Folberth, C., Sinabell, F., Schinko, T., and Hanger-Kopp, S.: Co-evaluating and -designing a Sustainable Agriculture Matrix for Austria in an international context, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9474, https://doi.org/10.5194/egusphere-egu22-9474, 2022.

EGU22-9476 | Presentations | ITS4.2/ERE1.11

Detection of Habitat Heterogeneity Changes Using Laser Scanning Data Targeting Birds 

Ji Yeon Kim, Dong Kun Lee, and Eun Sub Kim

Research dealing with three-dimensional structural data of forests or vegetation is increasing. LiDAR-based research to detect biodiversity (LaRue et al. 2019) is growing, through using structural data such as analyzing heterogeneity, distribution, and height in forest structures (Matsuo et al. 2021) or identifying rugosity (Gough et al. 2020). For example, the technology to detect canopy structures is linked with the GEDI technology, leading to structural diversity mapping on a wide scale and further to β-diversity. (Schneider et al. 2020) Meanwhile, most connectivity studies so far have been conducted on two-dimensional surfaces, and resistance value-based studies on species data, topography and vegetation structure, and habitat quality have been performed. In this study, we try to detect changes in the space distribution pattern of species due to anthropogenic intervention through lidar-based 3D structural data. Through structural heterogeneity, the connectivity at the landscape level is analyzed, and for this purpose, it can be compared with the traditional diversity evaluation method through a verification process based on species data. By detecting the impact on species in advance in the impact assessment stage, this study intends to present a methodology that can function as a forestry and conservation decision-making support tool in combination with ICT-based monitoring technology.

How to cite: Kim, J. Y., Lee, D. K., and Kim, E. S.: Detection of Habitat Heterogeneity Changes Using Laser Scanning Data Targeting Birds, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9476, https://doi.org/10.5194/egusphere-egu22-9476, 2022.

EGU22-9542 | Presentations | ITS4.2/ERE1.11

Eliciting public preferences for wildfire management policies in Crete, Greece 

Haleema Misal, Ioannis Kountouris, Apostolos Voulgarakis, and Anastasios Rovithakis

Fire regimes form an integral part of terrestrial biomes in the Mediterranean region as they provide essential disturbances which change the structure and function of plants that favour Mediterranean type climates. Fire is inextricably linked to such ecosystems and cannot be excluded from them. However, the intensification of human activities in Greece, coupled with increasingly unpredictable wildfires has created huge imbalances and jeopardised the ecological integrity of ecosystems. Expansions into the wildland urban interface, rural abandonment, and the focus on fire suppression are increasing the vulnerability and flammability of the Greek environment. The duality of fire is delicate, both at local and national level, catastrophic wildfires singe deeply on landscapes and economies, social burns can take just as long to heal. In Greece, this is further exacerbated by the burgeoning socio-economic and political complexities that have catalysed the current ineffective and unsustainable fire management strategies. Damages from wildfires affect ecosystem services which can lead to a reduction in human wellbeing. Understanding the interactions between ecosystems and humans through environmental valuation is key to implementing effective policy. This study uses economic valuation methods in the form of a choice experiment to elicit public preference for a wildfire management policy in Crete. A survey was deployed around the island, with respondents asked about their preferences between different management strategies. The policies outlined in the survey are made up of the following attributes: risk of fire, agricultural production, landscape quality and post-wildfire damage mitigation. Results from this study indicate a positive preference by the public for a new proposed policy. The findings from this study can be used for decision making in Crete and other similar southern European environments by providing metrics for appropriate wildfire management.

How to cite: Misal, H., Kountouris, I., Voulgarakis, A., and Rovithakis, A.: Eliciting public preferences for wildfire management policies in Crete, Greece, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9542, https://doi.org/10.5194/egusphere-egu22-9542, 2022.

The concept of ecosystem services (ES), as a set of components of the natural capital that provide products and services directed to humans, was born around the middle of the last century, reaching a more systematic definition in the early 2000s with the Millennium Ecosystem Assessment (MA, 2005). This issue is implicitly linked to popular research topics, such as climate change,  population well-being, fight against hunger in the world and has undergone a significant increasing interest from scientific research since the SDGs subscription, defined in the 2030 Agenda.

With the thrust of the investigation into this new branch, various tools have been created aimed at dealing with ecosystem services, not only from a qualitative point of view but in quantitative terms. The present work aims to analyze the applicability of a specific SE quantification software for vegetation, based both on the use of meteorological data and on the acquisition of field data and capable of returning outputs relating to the main components: environment (air quality), soil (use and cover) and water (quality and quantity of water runoff, with a focus on vegetation hydrology). The combination of this eco-hydrological model with a monetary ES evaluation is also interesting: although the economic model considered is particularly simple and therefore characterized by a non-negligible standard error, it is important to underline the direct and spontaneous association between SE and monetary quantification considered by the software, unlike how at the end of the last century the economic value of nature was still neglected.

Finally, the main results of a ES quantification project in an Italian urban context will be discussed, underlining  the environmental improvement to the surroundings and the social benefits for the population.

How to cite: Busca, F. and Revelli, R.: Ecosystem services, monetary value and social sphere: a specific-vegetation software suite on a urban-scale project, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11996, https://doi.org/10.5194/egusphere-egu22-11996, 2022.

EGU22-12354 | Presentations | ITS4.2/ERE1.11

Social capital in stressed social-ecological systems: understanding social learning in agricultural communities in China to aid environmental policy and practice 

Ying Zheng, Larissa A. Naylor, Weikai Wang, Alasdair Stanton, David Oliver, Neil Munro, Nai Rui Chng, Susan Waldron, and Tao Peng

Social learning is increasingly used to address environmental challenges including sustainable farming. How sustainable agricultural knowledge is co-produced, shared and used between farmers, scientists and government is important for building capacity and trust for sustainability in stressed socio-ecological communities worldwide. However, such understanding is largely lacking in developing economies. This research presents the findings from analysis of smallholder farmers’ social learning in three agricultural regions in China. Combining an existing social capital framework with questionnaires (Q) and interviews (I) with farmers (Q n=632; I n=30) and officials (Q n=77, I n=64), we demonstrate how farmers access and share farming knowledge through bonding, bridging and linking networks. In two regions, family bonding was the dominant learning pathway while linking networks to access ‘formal knowledge’ from government (or scientists) were limited. However, in the third region, government played a more important role in farmers’ knowledge sharing and acquisition processes. In all regions, learning from researchers was largely absent. Key suggestions about ways to enhance use of multiple forms of knowledge are provided. First, this study highlights the need for a more locally and socially embedded approach to facilitate enhanced farmers’ knowledge exchange and learning, to then build trust and capacity to help better address pressing local environmental challenges. Second, we show how social dynamics research can usefully inform knowledge exchange plans for collaborative, international development science, so that it can be best suited to local contexts, to optimise research impacts, capacity building and avoiding of mismatches. 

How to cite: Zheng, Y., Naylor, L. A., Wang, W., Stanton, A., Oliver, D., Munro, N., Chng, N. R., Waldron, S., and Peng, T.: Social capital in stressed social-ecological systems: understanding social learning in agricultural communities in China to aid environmental policy and practice, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12354, https://doi.org/10.5194/egusphere-egu22-12354, 2022.

EGU22-2024 | Presentations | ITS3.1/SSS1.2 | Highlight

Understanding natural hazards in a changing landscape: A citizen science approach in Kigezi highlands, southwestern Uganda 

Violet Kanyiginya, Ronald Twongyirwe, Grace Kagoro, David Mubiru, Matthieu Kervyn, and Olivier Dewitte

The Kigezi highlands, southwestern Uganda, is a mountainous tropical region with a high population density, intense rainfall, alternating wet and dry seasons and high weathering rates. As a result, the region is regularly affected by multiple natural hazards such as landslides, floods, heavy storms, and earthquakes. In addition, deforestation and land use changes are assumed to have an influence on the patterns of natural hazards and their impacts in the region. Landscape characteristics and dynamics controlling the occurrence and the spatio-temporal distribution of natural hazards in the region remain poorly understood. In this study, citizen science has been employed to document and understand the spatial and temporal occurrence of natural hazards that affect the Kigezi highlands in relation to the multi-decadal landscape change of the region. We present the methodological research framework involving three categories of participatory citizen scientists. First, a network of 15 geo-observers (i.e., citizens of local communities distributed across representative landscapes of the study area) was established in December 2019. The geo-observers were trained at using smartphones to collect information (processes and impacts) on eight different natural hazards occurring across their parishes. In a second phase, eight river watchers were selected at watershed level to monitor the stream flow characteristics. These watchers record stream water levels once daily and make flood observations. In both categories, validation and quality checks are done on the collected data for further analysis. Combining with high resolution rainfall monitoring using rain gauges installed in the watersheds, the data are expected to characterize catchment response to flash floods. Lastly, to reconstruct the historical landscape change and natural hazards occurrences in the region, 96 elderly citizens (>70 years of age) were engaged through interviews and focus group discussions to give an account of the evolution of their landscape over the past 60 years. We constructed a historical timeline for the region to complement the participatory mapping and in-depth interviews with the elderly citizens. During the first 24 months of the project, 240 natural hazard events with accurate timing information have been reported by the geo-observers. Conversion from natural tree species to exotic species, increased cultivation of hillslopes, road construction and abandonment of terraces and fallowing practices have accelerated natural hazards especially flash floods and landslides in the region. Complementing with the region’s historical photos of 1954 and satellite images, major landscape dynamics have been detected. The ongoing data collection involving detailed ground-based observations with citizens shows a promising trend in the generation of new knowledge about natural hazards in the region.

How to cite: Kanyiginya, V., Twongyirwe, R., Kagoro, G., Mubiru, D., Kervyn, M., and Dewitte, O.: Understanding natural hazards in a changing landscape: A citizen science approach in Kigezi highlands, southwestern Uganda, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2024, https://doi.org/10.5194/egusphere-egu22-2024, 2022.

EGU22-2929 | Presentations | ITS3.1/SSS1.2

Possible Contributions of Citizen Science in the Development of the Next Generation of City Climate Services 

Peter Dietrich, Uta Ködel, Sophia Schütze, Felix Schmidt, Fabian Schütze, Aletta Bonn, Thora Herrmann, and Claudia Schütze

Human life in cities is already affected by climate change. The effects will become even more pronounced in the coming years and decades. Next-generation of city climate services is necessary for adapting infrastructures and the management of services of cities to climate change. These services are based on advanced weather forecast models and the access to diverse data. It is essential to keep in mind that each citizen is a unique individual with their own peculiarities, preferences, and behaviors. The base for our approach is the individual specific exposure, which considers that people perceive the same conditions differently in terms of their well-being. Individual specific exposure can be defined as the sum of all environmental conditions that affect humans during a given period of time, in a specific location, and in a specific context. Thereby, measurable abiotic parameters such as temperature, humidity, wind speed, pollution and noise are used to characterize the environmental conditions. Additional information regarding green spaces, trees, parks, kinds of streets and buildings, as well as available infrastructures are included in the context. The recording and forecasting of environmental parameters while taking into account the context, as well as the presentation of this information in easy-to-understand and easy-to-use maps, are critical for influencing human behavior and implementing appropriate climate change adaptation measures.

We will adopt this approach within the frame of the recently started, EU-funded CityCLIM project. We aim to develop and implement approaches which will explore the potential of citizen science in terms of current and historical data collecting, data quality assessment and evaluation of data products.  In addition, our approach will also provide strategies for individual climate data use, and the derivation and evaluation of climate change adaptation actions in cities.

In a first step we need to define and to characterize the different potential stakeholder groups involved in citizen science data collection. Citizen science offers approaches that consider citizens as both  organized target groups (e.g., engaged companies, schools) and individual persons (e.g. hobby scientists). An important point to be investigated is the motivation of citizen science stakehoder groups to sustainably collect data and make it available to science and reward them accordingly. For that purpose, strategic tools, such as value proposition canvas analysis, will be applied to taylor the science-to-business and the science-to-customer communications and offers in terms of the individual needs.

How to cite: Dietrich, P., Ködel, U., Schütze, S., Schmidt, F., Schütze, F., Bonn, A., Herrmann, T., and Schütze, C.: Possible Contributions of Citizen Science in the Development of the Next Generation of City Climate Services, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2929, https://doi.org/10.5194/egusphere-egu22-2929, 2022.

EGU22-4168 | Presentations | ITS3.1/SSS1.2

Extending Rapid Image Classification with the Picture Pile Platform for Citizen Science 

Tobias Sturn, Linda See, Steffen Fritz, Santosh Karanam, and Ian McCallum

Picture Pile is a flexible web-based and mobile application for ingesting imagery from satellites, orthophotos, unmanned aerial vehicles and/or geotagged photographs for rapid classification by volunteers. Since 2014, there have been 16 different crowdsourcing campaigns run with Picture Pile, which has involved more than 4000 volunteers who have classified around 11.5 million images. Picture Pile is based on a simple mechanic in which users view an image and then answer a question, e.g., do you see oil palm, with a simple yes, no or maybe answer by swiping the image to the right, left or downwards, respectively. More recently, Picture Pile has been modified to classify data into categories (e.g., crop types) as well as continuous variables (e.g., degree of wealth) so that additional types of data can be collected.

The Picture Pile campaigns have covered a range of domains from classification of deforestation to building damage to different types of land cover, with crop type identification as the latest ongoing campaign through the Earth Challenge network. Hence, Picture Pile can be used for many different types of applications that need image classifications, e.g., as reference data for training remote sensing algorithms, validation of remotely sensed products or training data of computer vision algorithms. Picture Pile also has potential for monitoring some of the indicators of the United Nations Sustainable Development Goals (SDGs). The Picture Pile Platform is the next generation of the Picture Pile application, which will allow any user to create their own ‘piles’ of imagery and run their own campaigns using the system. In addition to providing an overview of Picture Pile, including some examples of relevance to SDG monitoring, this presentation will provide an overview of the current status of the Picture Pile Platform along with the data sharing model, the machine learning component and the vision for how the platform will function operationally to aid environmental monitoring.

How to cite: Sturn, T., See, L., Fritz, S., Karanam, S., and McCallum, I.: Extending Rapid Image Classification with the Picture Pile Platform for Citizen Science, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4168, https://doi.org/10.5194/egusphere-egu22-4168, 2022.

EGU22-5094 | Presentations | ITS3.1/SSS1.2

Life in undies – Preliminary results of a citizen science data collection targeting soil health assessement in Hungary 

Mátyás Árvai, Péter László, Tünde Takáts, Zsófia Adrienn Kovács, Kata Takács, János Mészaros, and László Pásztor

Last year, the Institute for Soil Sciences, Centre for Agricultural Research launched Hungary's first citizen science project with the aim to obtain information on the biological activity of soils using a simple estimation procedure. With the help of social media, the reactions on the call for applications were received from nearly 2000 locations. 

In the Hungarian version of the international Soil your Undies programme, standardized cotton underwear was posted to the participants with a step-by-step tutorial, who buried their underwear for about 60 days, from mid of May until July in 2021, at a depth of about 20-25 cm. After the excavation, the participants took one digital image of the underwear and recorded the geographical coordinates, which were  uploaded to a GoogleForms interface together with several basic information related to the location and the user (type of cultivation, demographic data etc.).

By analysing digital photos of the excavated undies made by volunteers, we obtained information on the level to which cotton material had decomposed in certain areas and under different types of cultivation. Around 40% of the participants buried the underwear in garden, 21% in grassland, 15% in orchard, 12% in arable land, 5% in vineyard and 4% in forest (for 3% no landuse data was provided).

The images were first processed using Fococlipping and Photoroom softwares for background removing and then percentage of cotton material remaining was estimated based on the pixels by using R Studio ‘raster package’.

The countrywide collected biological activity data from nearly 1200 sites were statistically evaluated by spatially aggregating the data both for physiographical and administrative units. The results have been published on various platforms (Facebook, Instagram, specific web site etc.), and a feedback is also given directly to the volunteers.

According to the experiments the first citizen science programme proved to be successful. 

 

Acknowledgment: Our research was supported by the Hungarian National Research, Development and Innovation Office (NKFIH; K-131820)

Keywords: citizen science; soil life; soil health; biological activity; soil properties

How to cite: Árvai, M., László, P., Takáts, T., Kovács, Z. A., Takács, K., Mészaros, J., and Pásztor, L.: Life in undies – Preliminary results of a citizen science data collection targeting soil health assessement in Hungary, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5094, https://doi.org/10.5194/egusphere-egu22-5094, 2022.

EGU22-5147 | Presentations | ITS3.1/SSS1.2

Distributed databases for citizen science 

Julien Malard-Adam, Joel Harms, and Wietske Medema

Citizen science is often heavily dependent on software tools that allow members of the general population to collect, view and submit environmental data to a common database. While several such software platforms exist, these often require expert knowledge to set up and maintain, and server and data hosting costs can become quite costly in the long term, especially if a project is successful in attracting many users and data submissions. In the context of time-limited project funding, these limitations can pose serious obstacles to the long-term sustainability of citizen science projects as well as their ownership by the community.

One the other hand, distributed database systems (such as Qri and Constellation) dispense with the need for a centralised server and instead rely on the devices (smartphone or computer) of the users themselves to store and transmit community-generated data. This new approach leads to the counterintuitive result that distributed systems, contrarily to centralised ones, become more robust and offer better availability and response times as the size of the user pool grows. In addition, since data is stored by users’ own devices, distributed systems offer interesting potential for strengthening communities’ ownership over their own environmental data (data sovereignty). This presentation will discuss the potential of distributed database systems to address the current technological limitations of centralised systems for open data and citizen science-led data collection efforts and will give examples of use cases with currently available distributed database software platforms.

How to cite: Malard-Adam, J., Harms, J., and Medema, W.: Distributed databases for citizen science, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5147, https://doi.org/10.5194/egusphere-egu22-5147, 2022.

EGU22-5571 | Presentations | ITS3.1/SSS1.2

RESECAN: citizen-driven seismology on an active volcano (Cumbre Vieja, La Palma Island, Canaries) 

Rubén García-Hernández, José Barrancos, Luca D'Auria, Vidal Domínguez, Arturo Montalvo, and Nemesio Pérez

During the last decades, countless seismic sensors have been deployed throughout the planet by different countries and institutions. In recent years, it has been possible to manufacture low-cost MEMS accelerometers thanks to nanotechnology and large-scale development. These devices can be easily configured and accurately synchronized by GPS. Customizable microcontrollers like Arduino or RaspBerryPI can be used to develop low-cost seismic stations capable of local data storage and real-time data transfer. Such stations have a sufficient signal quality to be used for complementing conventional seismic networks.

In recent years Instituto Volcanológico de Canarias (INVOLCAN) has developed a proprietary low-cost seismic station to implement the Canary Islands School Seismic Network (Red Sísmica Escolar Canaria - RESECAN) with multiple objectives:

  • supporting the teaching of geosciences.
  • promoting the scientific vocation.
  • strengthening the resilience of the local communities by improving awareness toward volcanism and the associated hazards.
  • Densifying the existing seismic networks.

On Sept. 19th 2021, a volcanic eruption started on the Cumbre Vieja volcano in La Palma. The eruption was proceeded and accompanied by thousands of earthquakes, many of them felt with intensities up to V MCS. Exploiting the attention drawn by the eruption, INVOLCAN started the deployment of low-cost seismic stations in La Palma in educational centres. In this preliminary phase, we selected five educational centres on the island.

The project's objective is to create and distribute low-cost stations in various educational institutions in La Palma and later on the whole Canary Islands Archipelago, supplementing them with educational material on the topics of seismology and volcanology. Each school will be able to access the data of its station, as well as those collected by other centres, being able to locate some of the recorded earthquakes. The data recorded by RESECAN will also be integrated into the broadband seismic network operated by INVOLCAN (Red Sísmica Canaria, C7). RESECAN will be an instrument of scientific utility capable of contributing effectively to the volcano monitoring of the Canary Islands, reinforcing its resilience with respect to future volcanic emergencies.

How to cite: García-Hernández, R., Barrancos, J., D'Auria, L., Domínguez, V., Montalvo, A., and Pérez, N.: RESECAN: citizen-driven seismology on an active volcano (Cumbre Vieja, La Palma Island, Canaries), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5571, https://doi.org/10.5194/egusphere-egu22-5571, 2022.

EGU22-6970 | Presentations | ITS3.1/SSS1.2

Analysis of individual learning outcomes of students and teachers in the citizen science project TeaTime4Schools 

Anna Wawra, Martin Scheuch, Bernhard Stürmer, and Taru Sanden

Only a few of the increasing number of citizen science projects set out to determine the projects impact on diverse learning outcomes of citizen scientists. However, besides pure completion of project activities and data collection, measurable benefits as individual learning outcomes (ILOs) (Phillips et al. 2014) should reward voluntary work.

Within the citizen science project „TeaTime4Schools“, Austrian students in the range of 13 to 18 years collected data as a group activity in a teacher guided school context; tea bags were buried into soil to investigate litter decomposition. In an online questionnaire a set of selected scales of ILOs (Phillips et al. 2014, Keleman-Finan et al. 2018, Wilde et al. 2009) were applied to test those ILOs of students who participated in TeaTime4Schools. Several indicators (scales for project-related response, interest in science, interest in soil, environmental activism, and self-efficacy) were specifically tailored from these evaluation frameworks to measure four main learning outcomes: interest, motivation, behavior, self-efficacy. In total, 106 valid replies of students were analyzed. In addition, 21 teachers who participated in TeaTime4Schools, answered a separate online questionnaire that directly asked about quality and liking of methods used in the project based on suggested scales about learning tasks of University College for Agricultural and Environmental Education (2015), which were modified for the purpose of this study. Findings of our research will be presented.

How to cite: Wawra, A., Scheuch, M., Stürmer, B., and Sanden, T.: Analysis of individual learning outcomes of students and teachers in the citizen science project TeaTime4Schools, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6970, https://doi.org/10.5194/egusphere-egu22-6970, 2022.

EGU22-7164 | Presentations | ITS3.1/SSS1.2

Seismic and air monitoring observatory for greater Beirut : a citizen observatory of the "urban health" of Beirut 

Cecile Cornou, Laurent Drapeau, Youssef El Bakouny, Samer Lahoud, Alain Polikovitch, Chadi Abdallah, Charbel Abou Chakra, Charbel Afif, Ahmad Al Bitar, Stephane Cartier, Pascal Fanice, Johnny Fenianos, Bertrand Guillier, Carla Khater, and Gabriel Khoury and the SMOAG Team

Already sensitive because of its geology (seismic-tsunamic risk) and its interface between arid and temperate ecosystems, the Mediterranean Basin is being transformed by climate change and major urban pressure on resources and spaces. Lebanon concentrates on a small territory the environmental, climatic, health, social and political crises of the Middle East: shortages and degradation of surface and groundwater quality, air pollution, landscape fragmentation, destruction of ecosystems, erosion of biodiversity, telluric risks and very few mechanisms of information, prevention and protection against these vulnerabilities. Further, Lebanon is sorely lacking in environmental data at sufficient temporal and spatial scales to cover the range of key phenomena and to allow the integration of environmental issues for the country's development. This absence was sadly illustrated during the August 4th, 2020, explosion at the port of Beirut, which hindered the effective management of induced threats to protect the inhabitants. In this degraded context combined with a systemic crisis situation in Lebanon, frugal  innovation is more than an option, it is a necessity. Initiated in 2021 within the framework of the O-LIFE lebanese-french research consortium (www.o-life.org), the « Seismic and air monitoring observatory  for greater Beirut » (SMOAG) project aims at setting up a citizen observatory of the urban health of Beirut by deploying innovative, connected, low-cost, energy-efficient and robust environmental and seismological instruments. Through co-constructed web services and mobile applications with various stakeholders (citizens, NGOs, decision makers and scientists), the SMOAG citizen observatory will contribute to the information and mobilization of Lebanese citizens and managers by sharing the monitoring of key indicators associated with air quality, heat islands and building stability, essential issues for a sustainable Beirut.

The first phase of the project was dedicated to the development of a low-cost environmental sensor enabling pollution and urban weather measurements (particle matters, SO2, CO, O3, N02, solar radiation, wind speed, temperature, humidity, rainfall) and to the development of all the software infrastructure, from data acquisition to the synoptic indicators accessible via web and mobile application, while following the standards of the Sensor Web Enablement and Sensor Observation System of the OGC and to the FAIR principles (Easy to find, Accessible, Interoperable, Reusable). A website and Android/IOS applications for the restitution of data and indicators and a dashboard allowing real time access to data have been developed. Environmental and low-cost seismological stations (Raspberry Shake) have been already deployed in Beirut, most of them hosted by Lebanese citizens. These instrumental and open data access efforts were completed by participatory workshops with various stakeholders  to improve the ergonomy of the web and application interfaces and to define roadmap for the implantation of future stations, consistently with  most vulnerable populations identified by NGOs and the current knowledge on the air pollution and heat islands in Beirut.

How to cite: Cornou, C., Drapeau, L., El Bakouny, Y., Lahoud, S., Polikovitch, A., Abdallah, C., Abou Chakra, C., Afif, C., Al Bitar, A., Cartier, S., Fanice, P., Fenianos, J., Guillier, B., Khater, C., and Khoury, G. and the SMOAG Team: Seismic and air monitoring observatory for greater Beirut : a citizen observatory of the "urban health" of Beirut, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7164, https://doi.org/10.5194/egusphere-egu22-7164, 2022.

EGU22-7323 | Presentations | ITS3.1/SSS1.2

Citizen science for better water quality management in the Brantas catchment, Indonesia? Preliminary results 

Reza Pramana, Schuyler Houser, Daru Rini, and Maurits Ertsen

Water quality in the rivers and tributaries of the Brantas catchment (about 12.000 km2) is deteriorating due to various reasons, including rapid economic development, insufficient domestic water treatment and waste management, and industrial pollution. Various water quality parameters are at least measured on monthly basis by agencies involved in water resource development and management. However, measurements consistently demonstrate exceedance of the local water quality standards. Recent claims presented by the local Environmental Protection Agency indicate that the water quality is much more affected by the domestic sources compared to the others. In an attempt to examine this, we proposed a citizen science campaign by involving people from seven communities living close to the river, a network organisation that works on water quality monitoring, three government agencies, and students from a local university. Beginning in 2022, we kicked off our campaign by measuring with test strips for nitrate, nitrite, and phosphate on weekly basis at twelve different locations from upstream to downstream of the catchment. In the effort to provide education on water stewardship and empower citizens to participate in water quality management, preliminary results – the test strips, strategies, and challenges - will be shown.

How to cite: Pramana, R., Houser, S., Rini, D., and Ertsen, M.: Citizen science for better water quality management in the Brantas catchment, Indonesia? Preliminary results, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7323, https://doi.org/10.5194/egusphere-egu22-7323, 2022.

EGU22-7916 | Presentations | ITS3.1/SSS1.2

Citizen science - an invaluable tool for obtaining high-resolution spatial and temporal meteorological data 

Jadranka Sepic, Jure Vranic, Ivica Aviani, Drago Milanovic, and Miro Burazer

Available quality-checked institutional meteorological data is often not measured at locations of particular interest for observing specific small-scale and meso-scale atmospheric processes. Similarly, institutional data can be hard to obtain due to data policy restrictions. On the other hand, a lot of people are highly interested in meteorology, and they frequently deploy meteorological instruments at locations where they live. Such citizen data are often shared through public data repositories and websites with sophisticated visualization routines.  As a result, the networks of citizen meteorological stations are, in numerous areas, denser and more easily accessible than are the institutional meteorological networks.  

Several examples of publicly available citizen meteorological networks, including school networks, are explored – and their application to published high-quality scientific papers is discussed. It is shown that for the data-based analysis of specific atmospheric processes of interest, such as mesoscale convective disturbances and mesoscale atmospheric gravity waves, the best qualitative and quantitative results are often obtained using densely populated citizen networks.  

Finally, a “cheap and easy to do” project of constructing a meteorological station with a variable number of atmospheric sensors is presented. Suggestions on how to use such stations in educational and citizen science activities, and even in real-time warning systems, are given.  

How to cite: Sepic, J., Vranic, J., Aviani, I., Milanovic, D., and Burazer, M.: Citizen science - an invaluable tool for obtaining high-resolution spatial and temporal meteorological data, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7916, https://doi.org/10.5194/egusphere-egu22-7916, 2022.

Among the greatest constraints to accurately monitoring and understanding climate and climate change in many locations is limited in situ observing capacity and resolution in these places. Climate behaviours along with dependent environmental and societal processes are frequently highly localized, while observing systems in the region may be separated by hundreds of kilometers and may not adequately represent conditions between them. Similarly, generating climate equity in urban regions can be hindered by an inability to resolve urban heat islands at neighborhood scales. In both cases, higher density observations are necessary for accurate condition monitoring, research, and for the calibration and validation of remote sensing products and predictive models. Coincidentally, urban neighborhoods are heavily populated and thousands of individuals visit remote locations each day for recreational purposes. Many of these individuals are concerned about climate change and are keen to contribute to climate solutions. However, there are several challenges to creating a voluntary citizen science climate observing program that addresses these opportunities. The first is that such a program has the potential for limited uptake if participants are required to volunteer their time or incur a significant cost to participate. The second is that researchers and decision-makers may be reluctant to use the collected data owing to concern over observer bias. This paper describes the on-going development and implementation by 2DegreesC.org of a technology-driven citizen science approach in which participants are equipped with low-cost automated sensors that systematically sample and communicate scientifically valid climate observations while they focus on other activities (e.g., recreation, gardening, fitness). Observations are acquired by a cloud-based system that quality controls, anonymizes, and makes them openly available. Simultaneously, individuals of all backgrounds who share a love of the outdoors become engaged in the scientific process via data-driven communication, research, and educational interactions. Because costs and training are minimized as barriers to participation, data collection is opportunistic, and the technology can be used almost anywhere, this approach is dynamically scalable with the potential for millions of participants to collect billions of new, accurate observations that integrate with and enhance existing observational network capacity.

How to cite: Shein, K.: Linking citizen scientists with technology to reduce climate data gaps, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10634, https://doi.org/10.5194/egusphere-egu22-10634, 2022.

The 2019-2020 bushfire season (the Black Summer) in Australia was unprecedented in its breadth and severity as well as the disrupted resources and time dedicated to studying it.  Right after one of the most extreme fire seasons on record had hit Australia, a once-in-a-century global pandemic, COVID-19, occurred. This pandemic caused world-wide lockdowns throughout 2020 and 2021 that prevented travel and field work, thus hindering researchers from assessing damage done by the Black Summer bushfires. Early assessments show that the bushfires on Kangaroo Island, South Australia caused declines in soil nutrients and ground coverage up to 10 months post-fire, indicating higher risk of soil erosion and fire-induced land degradation at this location. In parallel to the direct impacts the Black Summer bushfires had on native vegetation and soil, the New South Wales Nature Conservation Council observed a noticeable increase in demand for fire management workshops in 2020. What was observed of fires and post-fire outcomes on soil and vegetation from the 2019-2020 bushfire season that drove so many citizens into action? In collaboration with the New South Wales Nature Conservation Council and Rural Fire Service through the Hotspots Fire Project, we will be surveying and interviewing landowners across New South Wales to collect their observations and insights regarding the Black Summer. By engaging landowners, this project aims to answer the following: within New South Wales, Australia, what impact did the 2019-2020 fire season have on a) soil health and native vegetation and b) human behaviours and perceptions of fire in the Australian landscape. The quantity of insights gained from NSW citizens will provide a broad assessment of fire impacts across multiple soil and ecosystem types, providing knowledge of the impacts of severe fires, such as those that occurred during the Black Summer, to the scientific community. Furthermore, with knowledge gained from reflections from citizens, the Hotspots Fire Project will be better able to train and support workshop participants, while expanding the coverage of workshops to improve support of landowners across the state. Data regarding fire impacts on soil, ecosystems, and communities has been collected by unknowing citizen scientists all across New South Wales, and to gain access to that data, we need only ask.

How to cite: Ondik, M., Ooi, M., and Muñoz-Rojas, M.: Insights from landowners on Australia's Black Summer bushfires: impacts on soil and vegetation, perceptions, and behaviours, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10776, https://doi.org/10.5194/egusphere-egu22-10776, 2022.

High air pollution concentration levels and increased urban heat island intensity, are amongst the most critical contemporary urban health concerns. This is the reason why various municipalities are starting to invest in extensive direct air quality and microclimate sensing networks. Through the study of these datasets it has become evident that the understanding of inter-urban environmental gradients is imperative to effectively introduce urban land-use strategies to improve the environmental conditions in the neighborhoods that suffer the most, and develop city-scale urban planning solutions for a better urban health.  However, given economic limitations or divergent political views, extensive direct sensing environmental networks have yet not been implemented in most cities. While the validity of citizen science environmental datasets is often questioned given that they rely on low-cost sensing technologies and fail to incorporate sensor calibration protocols, they can offer an alternative to municipal sensing networks if the necessary Quality Assurance / Quality Control (QA/QC) protocols are put in place.

This research has focused on the development of a QA/QC protocol for the study of urban environmental data collected by the citizen science PurpleAir initiative implemented in the Bay Area and the city of Los Angeles where over 700 purple air stations have been implemented in the last years. Following the QA/QC process the PurpleAir data was studied in combination with remote sensing datasets on land surface temperature and normalized difference vegetation index, and geospatial datasets on socio-demographic and urban fabric parameters. Through a footprint-based study, and for all PurpleAir station locations, the featured variables and the buffer sizes with higher correlations have been identified to compute the inter-urban environmental gradient predictions making use of 3 supervised machine learning models: - Regression Tree Ensemble, Support Vector Machine, and a Gaussian Process Regression.

How to cite: Llaguno-Munitxa, M., Bou-Zeid, E., Rueda, P., and Shu, X.: Citizen-science urban environmental monitoring for the development of an inter-urban environmental prediction model for the city of Los Angeles, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11765, https://doi.org/10.5194/egusphere-egu22-11765, 2022.

EGU22-11797 | Presentations | ITS3.1/SSS1.2

Attitudes towards a cafetiere-style filter system and paper-based analysis pad for soil nutrition surveillance in-situ: evidence from Kenya and Vietnam 

Samantha Richardson, Philip Kamau, Katie J Parsons, Florence Halstead, Ibrahim Ndirangu, Vo Quang Minh, Van Pham Dang Tri, Hue Le, Nicole Pamme, and Jesse Gitaka

Routine monitoring of soil chemistry is needed for effective crop management since a poor understanding of nutrient levels affects crop yields and ultimately farmers’ livelihoods.1 In low- and middle-income countries soil sampling is usually limited, due to required access to analytical services and high costs of portable sampling equipment.2 We are developing portable and low-cost sampling and analysis tools which would enable farmers to test their own land and make informed decisions around the need for fertilizers. In this study we aimed to understand attitudes of key stakeholders towards this technology and towards collecting the data gathered on public databases which could inform decisions at government level to better manage agriculture across a country.

 

In Kenya, we surveyed 549 stakeholders from Murang’a and Kiambu counties, 77% men and 23% women. 17.2% of these respondent smallholder farmers were youthful farmers aged 18-35 years with 81.9% male and 18.1% female-headed farming enterprises. The survey covered current knowledge of soil nutrition, existing soil management practices, desire to sample soil in the future, attitudes towards our developed prototypes, motivation towards democratization of soil data, and willingness to pay for the technology. In Vietnam a smaller mixed methods online survey was distributed via national farming unions to 27 stakeholders, in particular engaging younger farmers with an interest in technology and innovation.

Within the Kenya cohort, only 1.5% of farmers currently test for nutrients and pH. Reasons given for not testing included a lack of knowledge about soil testing (35%), distance to testing centers (34%) and high costs (16%). However, 97% of respondents were interested in soil sampling at least once a year, particularly monitoring nitrates and phosphates. Nearly all participants, 94-99% among the males/females/youths found cost of repeated analysis of soil samples costing around USD 11-12 as affordable for their business. Regarding sharing the collecting data, 88% believed this would be beneficial, for example citing that data shared with intervention agencies and agricultural officers could help them receive relevant advice.

In Vietnam, 87% of famers did not have their soil nutrient levels tested with 62% saying they did not know how and 28% indicating prohibitive costs. Most currently relied on local knowledge and observations to improve their soil quality. 87% thought that the system we were proposing was affordable with only 6% saying they would not be interested in trialing this new technology. Regarding the soil data, respondents felt that it should be open access and available to everyone.

Our surveys confirmed the need and perceived benefit for our proposed simple-to-operate and cost-effective workflow, which would enable farmers to test soil chemistry themselves on their own land. Farmers were also found to be motivated towards sharing their soil data to get advice from government agencies. The survey results will inform our further development of low-cost, portable analytical tools for simple on-site measurements of nutrient levels within soil.

 

1. Dimkpa, C., et al., Sustainable Agriculture Reviews, 2017, 25, 1-43.

2. Zingore, S., et al., Better Crops, 2015, 99 (1), 24-26.

How to cite: Richardson, S., Kamau, P., Parsons, K. J., Halstead, F., Ndirangu, I., Minh, V. Q., Tri, V. P. D., Le, H., Pamme, N., and Gitaka, J.: Attitudes towards a cafetiere-style filter system and paper-based analysis pad for soil nutrition surveillance in-situ: evidence from Kenya and Vietnam, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11797, https://doi.org/10.5194/egusphere-egu22-11797, 2022.

Keywords: preconcentration, heavy metal, cafetiere, citizen science, paper-based microfluidics

Heavy-metal analysis of water samples using microfluidics paper-based analytical devices (µPAD) with colourimetric readout is of great interest due to its simplicity, affordability and potential for Citizen Science-based data collection [1]. However, this approach is limited by the relatively poor sensitivity of the colourimetric substrates, typically achieving detection within the mg L-1 range, whereas heavy-metals exist in the environment at <μg L-1 quantities   [2]. Preconcentration is commonly used when analyte concentration is below the analytical range, but this typically requires laboratory equipment and expert users [3]. Here, we are developing a simple method for pre-concentration of heavy metals, to be integrated with a µPAD workflow that would allow Citizen Scientists to carry out pre-concentration as well as readout on-site.

The filter mesh from an off-the-shelf cafetière (350 mL) was replaced with a custom-made bead carrier basket, laser cut in PMMA sheet featuring >500 evenly spread 100 µm diameter holes. This allowed the water sample to pass through the basket and mix efficiently with the 2.6 g ion-exchange resin beads housed within (Lewatit® TP207, Ambersep® M4195, Lewatit® MonoPlus SP 112). An aqueous Ni2+ sample (0.3 mg L-1, 300 mL) was placed in the cafetiere and the basket containing ion exchange material was moved up and down for 5 min to allow Ni2+ adsorption onto the resin. Initial investigations into elution with a safe, non-toxic eluent focused on using NaCl (5 M). These were carried out by placing the elution solution into a shallow dish and into which the the resin containing carrier basket was submerging. UV/vis spectroscopy via a colourimetric reaction with nioxime was used to monitor Ni2+ absorption and elution.

After 5 min of mixing it was found that Lewatit® TP207 and Ambersep® M4195 resins adsorbed up to 90% of the Ni2+ ions present in solution and the Lewatit® MonoPlus SP 112 adsorbed up to 60%. However, the Lewatit® MonoPlus SP 112 resin performed better for elution with NaCl. Initial studies showed up to 30% of the Ni2+ was eluted within only 1 min of mixing with 10 mL 5 M NaCl.

Using a cafetière as pre-concentration vessel coupled with non-hazardous reagents in the pre-concentration process allows involvement of citizen scientists in more advanced environmental monitoring activities that cannot be achieved with a simple paper-based sensor alone. Future work will investigate the user-friendliness of the design by trialling the system with volunteers and will aim to further improve the trapping and elution efficiencies.

 

References:

  • Almeida, M., et al., Talanta, 2018, 177, 176-190.
  • Lace, A., J. Cleary, Chemosens., 2021. 9, 60.
  • Alahmad, W., et al.. Biosens. Bioelectron., 2021. 194, 113574.

 

How to cite: Sari, M., Richardson, S., Mayes, W., Lorch, M., and Pamme, N.: Method development for on-site freshwater analysis with pre-concentration of nickel via ion-exchange resins embedded in a cafetière system and paper-based analytical devices for readout, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11892, https://doi.org/10.5194/egusphere-egu22-11892, 2022.

EGU22-12972 | Presentations | ITS3.1/SSS1.2 | Highlight

Collection of valuable polar data and increase in nature awareness among travellers by using Expedition Cruise Ships as platforms of opportunity 

Verena Meraldi, Tudor Morgan, Amanda Lynnes, and Ylva Grams

Hurtigruten Expeditions, a member of the International Association of Antarctica Tour Operators (IAATO) and the Association of Arctic Expedition Cruise Operators (AECO) has been visiting the fragile polar environments for two decades, witnessing the effects of climate change. Tourism and the number of ships in the polar regions has grown significantly. As a stakeholder aware of the need for long-term protection of these regions, we promote safe and environmentally responsible operations, invest in the understanding and conservation of the areas we visit, and focus on the enrichment of our guests.

For the last couple of years, we have supported the scientific community by transporting researchers and their equipment to and from their study areas in polar regions and we have established collaborations with numerous scientific institutions. In parallel we developed our science program with the goal of educating our guests about the natural environments they are in, as well as to further support the scientific community by providing our ships as platforms of opportunity for spatial and temporal data collection. Participation in Citizen Science programs that complement our lecture program provides an additional education opportunity for guests to better understand the challenges the visited environment faces while contributing to filling scientific knowledge gaps in remote areas and providing data for evidence-based decision making.

We aim to continue working alongside the scientific community and developing partnerships. We believe that scientific research and monitoring in the Arctic and Antarctic can hugely benefit from the reoccurring presence of our vessels in these areas, as shown by the many projects we have supported so far. In addition, our partnership with the Polar Citizen Science Collective, a charity that facilitates interaction between scientists running Citizen Science projects and expedition tour operators, will allow the development of programs on an industry level, rather than just an operator level, increasing the availability and choice of platforms of opportunity for the scientific community.

How to cite: Meraldi, V., Morgan, T., Lynnes, A., and Grams, Y.: Collection of valuable polar data and increase in nature awareness among travellers by using Expedition Cruise Ships as platforms of opportunity, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12972, https://doi.org/10.5194/egusphere-egu22-12972, 2022.

EGU22-13115 | Presentations | ITS3.1/SSS1.2

Participatory rainfall monitoring: strengthening hydrometeorological risk management and community resilience in Peru 

Miguel Arestegui, Miluska Ordoñez, Abel Cisneros, Giorgio Madueño, Cinthia Almeida, Vannia Aliaga, Nelson Quispe, Carlos Millán, Waldo Lavado, Samuel Huaman, and Jeremy Phillips

Heavy rainfall, floods and debris flow on the Rimac river watershed are recurring events that impact Peruvian people in vulnerable situations.There are few historical records, in terms of hydrometeorological variables, with sufficient temporal and spatial accuracy. As a result, Early Warning Systems (EWS) efficiency, dealing with these hazards, is critically limited.

In order to tackle this challenge, among other objectives, the Participatory Monitoring Network (Red de Monitoreo Participativo or Red MoP, in spanish) was formed: an alternative monitoring system supported by voluntary community collaboration of local population under a citizen science approach. This network collects and communicates data captured with standardized manual rain gauges (< 3USD). So far, it covers districts in the east metropolitan area of the capital city of Lima, on dense peri-urban areas, districts on the upper Rimac watershed on rural towns, and expanding to other upper watersheds as well.

Initially led by Practical Action as part of the Zurich Flood Resilience Alliance, it is now also supported by SENAMHI (National Meteorological and Hydrological Service) and INICTEL-UNI (National Telecommunications Research and Training Institute), as an activity of the National EWS Network (RNAT).

For the 2019-2022 rainfall seasons, the network has been gathering data and information from around 80 volunteers located throughout the Rimac and Chillon river watersheds (community members, local governments officers, among others): precipitation, other meteorological variables, and information regarding the occurrence of events such as floods and debris flow (locally known as huaycos). SENAMHI has provided a focalized 24h forecast for the area covered by the volunteers, experimentally combines official stations data with the network’s for spatial analysis of rainfall, and, with researchers from the University of Bristol, analyses potential uses of events gathered through this network. In order to facilitate and automatize certain processes, INICTEL-UNI developed a web-platform and a mobile application that is being piloted.

We present an analysis of events and trends gathered through this initiative (such as a debris flow occurred in 2019). Specifically, hotspots and potential uses of this sort of refined spatialized rainfall information in the dry & tropical Andes. As well, we present a qualitative analysis of volunteers’ expectations and perceptions. Finally, we also present a meteorological explanation of selected events, supporting the importance of measuring localized precipitation during the occurrence of extreme events in similar complex, physical and social contexts.

How to cite: Arestegui, M., Ordoñez, M., Cisneros, A., Madueño, G., Almeida, C., Aliaga, V., Quispe, N., Millán, C., Lavado, W., Huaman, S., and Phillips, J.: Participatory rainfall monitoring: strengthening hydrometeorological risk management and community resilience in Peru, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13115, https://doi.org/10.5194/egusphere-egu22-13115, 2022.

EGU22-2135 | Presentations | ITS3.2/HS1.1.8

Assessing the groundwater sustainability of Bengaluru megacity, India, through the lens of socio-hydrogeology 

Tejas Kulkarni, Matthias Gassmann, Chandrakanth Kulkarni, Vijayalaxmi Khed, and Andreas Buerkert

Water extraction in Bengaluru, India's fastest expanding metropolis, entirely depends on its ~500000 wells in a crystalline rock aquifer, of which an unknown number has been abandoned and the level of others has sunk to depths of 450 meters below surface. Recent research has highlighted the spatial heterogeneity and questioned the reliability of water level data in these settings. To fill existing knowledge gaps on the likely over-extraction of groundwater as a vital resource we used a socio-hydrogeological approach of front-lining local hydrogeologists to collect primary data on the spatio-temporal evolution of well depths across the city. Our data show that over the past 60 years borewell depth has increased significantly while water yields have remained unchanged, indicating that digging deeper wells is unsustainable. Using camera inspections of 56 wells in a 2.1km2 catchment of industrial land use in Electronic City of Bengaluru, we noted that water levels in the wells are largely determined by rock fractures, not by well depth. Our data show that increased borewell depths is a good signal of declining water levels in Bengaluru’s aquifers. Analysis of δ18O and δ2H signatures of groundwater samples across all depths followed the local meteoric water line indicating recent recharge, implying that drilling deeper only increased the borehole volume and did not tap into newer water sources.

How to cite: Kulkarni, T., Gassmann, M., Kulkarni, C., Khed, V., and Buerkert, A.: Assessing the groundwater sustainability of Bengaluru megacity, India, through the lens of socio-hydrogeology, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2135, https://doi.org/10.5194/egusphere-egu22-2135, 2022.

EGU22-3412 | Presentations | ITS3.2/HS1.1.8

Socio-hydrogeological approach to identify contaminant fluxes towards groundwater-dependent hydrosystems, case of the Biguglia lagoon (Corsica, France) 

Eléa Crayol, Frédéric Huneau, Emilie Garel, Viviana Re, Alexandra Mattei, Sébastien Santoni, and Vanina Pasqualini

Coastal Mediterranean lagoons are very often groundwater-dependent hydrosystems, however their hydrogeological functioning is poorly known, damaging their management. Socio-hydrogeology allows, in an inter-and transdisciplinary way to clarify the relationships linking human activities and groundwater status. Those interactions within the watershed, combined with consumption patterns of the population, and sanitation defects can generate processes leading to pollutant fluxes with impacts on surface water, groundwater and lagoon water quality. This approach integrates both social and economic components into hydrogeological investigations.

The Biguglia lagoon watershed (Northern Corsica, France) has been chosen as a pilot site. Indeed, significant nitrate content, emerging compounds, and pesticides have already been observed in the lagoon waters, but their origin still needs to be specified, both in terms of source and dispersion modalities.

The aim of this study is to (1) assess the link between groundwater quality and the anthropogenic pressures on the watershed, (2) understand water users’ and the stakeholders ‘perception and knowledge of the watershed and the local territory, (3) identify the origin of pollutions detected in the lagoon’s water.

In this purpose, a field sampling was led in spring 2021, combining several tools useful for the knowledge improvement of the hydrogeological functioning and the tracing of anthropic pollutant fluxes. Investigations with structured interviews was administered to 32 water users and 16 local stakeholders involved in the monitoring assessment, to determine the land use evolution since 1950’s to present and aiming at identifying past and present uses of the water resource over the watershed. At the same time, a multi-tracer water sampling, combining physico-chemical parameters, major ions and trace elements as well as, stable isotopes of the water molecule was carried out on 53 points (lagoon, rivers, canals waters, groundwater), of which 21 samples were also analysed for a set of pesticides (screening of 240 molecules).

Pesticide’s analysis show that the study site is affected by agricultural pollution. Indeed, neonicotinoid insecticides, extensively used worldwide, have been found on the sampling points with significant concentrations. Those pesticides are mainly used in fruit, vegetable and cereal crops. The field survey, the questionnaire and the sampling campaign have allowed to identify and confirm the presence of these cultures on the study site. In the same way, benzotriazoles, perfluorinated acids (PFAs) and DEET (insect repellent) have also been detected. They are related to the consumption habits of the population on the watershed.

Geochemical analysis correlated with the social analysis and the land use analysis permitted to better constraint pollution sources, evidencing two main sources: sanitation defect and agriculture activity.

The socio-hydrogeological approach is essential to improve the knowledge of the Biguglia lagoon hydrosystem. The purpose of this work is to offer a new functional diagram of the area, including the space-time continuum of anthropogenic impacts within the watershed. This new knowledge will help local stakeholders towards the recovery of a good geochemical and ecological status for the lagoon brackish water body of Biguglia.

How to cite: Crayol, E., Huneau, F., Garel, E., Re, V., Mattei, A., Santoni, S., and Pasqualini, V.: Socio-hydrogeological approach to identify contaminant fluxes towards groundwater-dependent hydrosystems, case of the Biguglia lagoon (Corsica, France), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3412, https://doi.org/10.5194/egusphere-egu22-3412, 2022.

Developing green infrastructures (GIs) for rainwater harvesting has prevailed in many arid regions, which requires a new water management framework. This paper focuses on a water policy - water trading scheme – design and analysis for integrated green infrastructures and water resource management in a watershed that consists of multiple urban areas. A multiagent model bringing together urban water management and GIs planning models for multiple water managers with hydrological models is proposed to show 1) what the optimized water trading scheme is, 2) how the scheme would affect watershed socio-hydrologic environments, and 3) what the role of GIs in the scheme is. In the model, the water trading scheme design depends not only on the hydrologic dynamics of watershed caused by GIs and but on the social interactions between watershed and multiple urban managers. The proposed model is applied to the Colorado River Lower Basin, which is one of the USA's aridest regions and is planning water trading. Results indicated that a water-trading scheme effectively allocates limited water resources with a minimized system cost in the study area. Results also show that developing GIs to use rainwater resources might further reduce the cost induced by the water trading scheme. However, it might also exacerbate water resource allocation inequity among water users. These findings can help decision-makers design the associated water policy to support sustainable watershed development in arid regions.

How to cite: Zhang, M. and Chui, T. F. M.: Modeling water trading to support integrated green infrastructure and water resources management in an arid watershed, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3487, https://doi.org/10.5194/egusphere-egu22-3487, 2022.

EGU22-4065 | Presentations | ITS3.2/HS1.1.8

Combining groundwater numerical modelling and social sciences to assess water access in developing countries rural environments 

Daniela Cid Escobar, Albert Folch, Nuria Ferrer, and Xavier Sanchez-Vila

Shallow groundwater is usually more accessible than surface water in remote and rural areas due to the infrastructure cost to collect and allocate surface water on dispersed communities. However, the absence of a proper hydrogeological characterization of the aquifer system added to the lack of groundwater infrastructure and maintenance, technical capacity, and governance has not allowed the development of sustainable use of local groundwater resources in different territories worldwide.

We propose an interdisciplinary approach to determine the risk of a household experiencing water shortage due to depletion of the aquifer, degradation of the water quality, not access to the water point, or sustainable functionality. Three main parameters were defined: Closeness (determined by geographical parameters and easily computed using GIS), Availability (determined by hydrogeological parameters that can be assessed from a groundwater model), and Sustainability (differentiating between software functionality and hardware functionality (Bonsor, MacDonald, Casey, Carter, & Wilson, 2018), the former analyzed through Multiple Factor Analysis. Each of these three factors range between 0 and 1, and their product provides an index that can be used to map the risk of individual households.

An application case in Kwale County, southeast coast of Kenya, is presented, where community handpumps are the main water supply system. The novelty of the index relies on the combination of groundwater model outputs with household data, which allows the generation of time-dependent risk indexes that can be calculated for several scenarios depending on the data available. In this case, we present three scenarios, one involving the potential malfunctioning of a percentage of the existing handpumps, and two other ones dealing with extreme climate scenarios, all of them designed to test the resilience and applicability of the proposed index and their applicability for decision making.

Acknowledgements: This work was funded by the Centre of Cooperation for Development of the Universitat Politècnica de Catalunya. We want to thank UPGRO and Gro For Good projects for their support and collaboration in acquiring available data.

References: Bonsor, H., MacDonald, A., Casey, V., Carter, R., & Wilson, P. (2018). The need for a standard approach to assessing the functionality of rural community water supplies. Hydrogeology Journal, 26(2), 367–370. https://doi.org/10.1007/s10040-017-1711-0

How to cite: Cid Escobar, D., Folch, A., Ferrer, N., and Sanchez-Vila, X.: Combining groundwater numerical modelling and social sciences to assess water access in developing countries rural environments, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4065, https://doi.org/10.5194/egusphere-egu22-4065, 2022.

EGU22-4383 | Presentations | ITS3.2/HS1.1.8

Insights from a transdisciplinary approach for water quality monitoring and multi-stakeholder management in the island of Santa Cruz, Galápagos (Ecuador) 

Chiara Tringali, Jonathan Rizzi, Viviana Re, Caterina Tuci, Marta Mancin, Edison Mendieta, and Antonio Marcomini

The Galápagos Archipelago (Ecuador) is traditionally considered a living museum and showcase of evolution. The rich biodiversity and distinctive environment attract thousands of visitors every year. However, this tourist flow exerts continuous pressures on the natural environment, and on water resources in particular, to the detriment of the local population who is faced with the challenges of accessing safe and sustainable drinking resources.

For this reason, over the years numerous projects, especially in the context of international cooperation activities, have tried to assess the impact of anthropogenic activities on the water quality and quantity in the islands. Unfortunately, the lack of coordination among all these projects did not allow to carry out continuous monitoring and, above all, to obtain homogenous and consistent time series of the measured hydrogeochemical parameters.

For this reason, in the framework of a joint technical cooperation project (“Health protection and prevention of anthropic pollution risks” in the Island of Santa Cruz” financed by Veneto Region, Italy; CS2012A19) a comprehensive assessment on water quality data (physico-chemical parameters, major elements, trace elements and coliforms) collected since 1985 in the Santa Cruz Island was performed. Results revealed the need of optimizing monitoring efforts to fill knowledge gaps and to better target decision making processes. All data were therefore standardized, homogenized and collected in an open database, accessible to all water stakeholders involved in water control, management and protection in the island. 

The information gathering activity also revealed the lack of coordination between the stakeholders themselves and the presence overlapping interests towards water resources, which represent an obstacle for coordinated actions targeted to sustainable water resources management in such a fragile environment. 

Therefore, under the guidance of the Santa Cruz Municipality, a Water Committee was established to foster the coordinated action among the water stakeholders in the island. The latter range from national to local authorities (e.g. National Water Secretariat, Ministry of Agriculture, Ecuador Naval Oceanographic Institute, National Park Galapagos, Municipality), research institutes (Charles Darwin Foundation), bottled water companies and Santa Cruz Households. Within the committee, shared procedures for data collection, sample analysis, evaluation and data assessment by an open access geodatabase were agreed collectively and tested in the field. Joint monitoring in the island can optimize the efforts for water quality assessment and protection, and improve accountability and outreach towards civil society and water users. Such a coordinated action can also ensure that international cooperation activities carried out in the island will respond to the real needs of the local population, and results will contribute to the long-term protection of the scarce water resources in the island.

Overall, results of the project revealed the high potential of adopting transdisciplinary approaches in complex, multi-stakeholder, framework typical of small island states.

How to cite: Tringali, C., Rizzi, J., Re, V., Tuci, C., Mancin, M., Mendieta, E., and Marcomini, A.: Insights from a transdisciplinary approach for water quality monitoring and multi-stakeholder management in the island of Santa Cruz, Galápagos (Ecuador), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4383, https://doi.org/10.5194/egusphere-egu22-4383, 2022.

EGU22-7114 | Presentations | ITS3.2/HS1.1.8

Integration of hydrogeology and social sciences in practice, two IWRM case studies with challenges and opportunities from semi-arid Africa 

Anne Van der Heijden, Maarten J. Waterloo, Anouk I. Gevaert, and Daniela Benedicto van Dalen

Groundwater resources in African drylands are important sources of freshwater but are under pressure due to population growth and climate change. It is therefore increasingly important that groundwater resources are managed in a sustainable way. Development of IWRM plans are ongoing in (semi-)arid African countries with support from national governments, NGOs and consultancies. This presentation aims to highlight two case studies in which bio-geophysical and socio-economic data were combined to assist in the Integrated Water Resources Management (IWRM) process: 1) catchment-scale Water Infrastructure Assessment (WIA) in Sudan and 2) assessment of pathways towards sustainable groundwater use in African drylands. Per case study lessons learned and recommended approaches are provided.

In IWRM intervention planning for semi-arid regions a local increase in available water resources is sought after, which can be found in the better use of excess runoff. A balance between water demand and water resources on community level is key and a prerequisite for implementing durable and inclusive interventions that last. The IWRM process starts with a strong knowledge base. In practice, however, the development of a good knowledge base is not simple. Challenges arise in collecting, processing, and mapping results. With hydrogeology, a 3D situation is translated to 2D maps. Socio-economic data are often stored based on administrative boundaries and need corrections for hydrological source-area delineation and seasonal and interannual variations. Population density and water demand change over seasons, following crop cycles and livestock migration patterns. Looking at local water availability, rainfall and surface water flows are becoming more variable and less reliable. Therefore, assessment of the rainfall regime and corresponding behaviour and movements of people and livestock is key. For WIAs, yields and usage are often averaged, thus disregarding seasonal changes, even though shallow wells and reservoirs regularly become depleted outside the rainy season. The Sudan case study presents an improved approach for a WIA, that is adaptable and can be applied in semi-arid environments in Africa and elsewhere, in which seasonality and socio-economic dynamics were taken into account.

Both hydrogeologic and socio-economic conditions tend to be quite location-specific. This makes developing a simple blueprint for integrated groundwater management impossible. However, by translating local conditions into regional advice, strategic pathways were developed for the drylands of Africa[1] to support IWRM. The zonal hydrogeological and socio-economic setting determined the main groundwater issues and the potential sustainability strategies. The sustainability pathways describe potential sets of strategies that can be effective in moving towards sustainable groundwater resources development and use. While these pathways provide insight into regional differences within the African drylands, these cannot be used at local scales. Tailor-made approaches are necessary. In these assessments, remote sensing provides opportunities. Gridded datasets of population density are of great value in water demand assessments on a larger scale. Participatory stakeholder processes also provide opportunities, including group interviews for development of community calendars providing useful information on the occurrence and frequency of natural hazards and water demand.

[1] Gevaert et al. 2020, Towards sustainable groundwater use in the African drylands

 

 

How to cite: Van der Heijden, A., Waterloo, M. J., Gevaert, A. I., and Benedicto van Dalen, D.: Integration of hydrogeology and social sciences in practice, two IWRM case studies with challenges and opportunities from semi-arid Africa, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7114, https://doi.org/10.5194/egusphere-egu22-7114, 2022.

EGU22-10542 | Presentations | ITS3.2/HS1.1.8

From Coarse Resolution to Realistic Resolution: GRACE as a Science Communication and Policymaking Tool for Sustainable Groundwater Management 

Li Xu, James S. Famiglietti, David Ferris, Xander Huggins, Chinchu Mohan, Sara Sadri, Palash Sanyal, and Jefferson S. Wong

Managing groundwater resources is challenging because they are difficult to monitor. The application of remote sensing methods has improved our capacity to monitor variability in groundwater storage, as is the case for the Gravity Recovery and Climate Experiment (GRACE) and the GRACE Follow-On (GRACE-FO) missions. While GRACE-based groundwater studies to date have covered many places across the globe, perspectives that link scientific studies to policymaking and practices are still limited. Challenges to applying GRACE data into practice result from their coarse resolution, which limits their utility at the smaller scales at which water management decisions are made. Another reason is that the data and related studies can be difficult to use and understand by policymakers and end-users. However, these challenges offer the GRACE scientific community opportunities to communicate with stakeholders, policymakers, and the public in raising awareness around groundwater sustainability issues. This paper addresses three questions: which GRACE data and GRACE-derived products can be useful for groundwater practices and management; how GRACE-derived groundwater messages can be better communicated with practitioners; and how to better operationalize GRACE-derived products for groundwater practice and management. This paper also aims to provide an agenda for the continued use of GRACE and GRACE-FO for the purpose of sustainable groundwater management. To gain insight into these questions, a policy Delphi survey was conducted to collect opinions of both the scientific and non-scientific communities. We made use of target search and snowballing techniques to identify suitable participants who are experienced groundwater researchers or practitioners, and who are familiar with GRACE. A total of 25 participants from around the world were surveyed (14 scientific and 11 non-scientific), and they provided thoughtful responses. We found that both communities acknowledged the potential of GRACE data and GRACE-derived products for groundwater management, and would be willing to collaborate to develop projects for practical applications. Better communication between researchers and practitioners was recommended as a key for the application of GRACE-derived products into practice. Practitioners noted their high demand for reliable data for their management responsibilities, but are more favorable towards locally observed data. The reliability of GRACE at small scales was an issue, even though some robust downscaling methods have been demonstrated down to local scales. The survey showed a desire for more comparison of GRACE-derived products to local measurements to determine whether GRACE products, e.g. downscaled data, can be useful for informing local decisions. Based on the survey, we proposed an agenda that helps to improve the usefulness of GRACE-derived products for practices. This agenda includes scientific recommendations that help to resolve the resolution and technical barriers for local applications, and professional perspectives that bridge the connection between science and policy, and facilitate communication for groundwater management.

How to cite: Xu, L., Famiglietti, J. S., Ferris, D., Huggins, X., Mohan, C., Sadri, S., Sanyal, P., and Wong, J. S.: From Coarse Resolution to Realistic Resolution: GRACE as a Science Communication and Policymaking Tool for Sustainable Groundwater Management, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10542, https://doi.org/10.5194/egusphere-egu22-10542, 2022.

EGU22-11819 | Presentations | ITS3.2/HS1.1.8

Adaptation to floods and droughts in (semi) arid transboundary basins: insights, barriers and opportunities drawn from socio-hydrogeological research in the Limpopo river basin, Southern Africa 

Jean-Christophe Comte, Luis Artur, Zareen Bharucha, Farisse Chirindja, Rosie Day, Joyce Dube, Fulvio Franchi, Josie Geris, Stephen Hussey, Eugene Makaya, Alessia Matano, Syed Mustafa, Edward Nesamvuni, Oluwaseun Olabode, Melanie Rohse, Simon Taylor, Sithabile Tirivarombo, and Anne Van Loon

The Limpopo river basin (LRB) is water-stressed and highly susceptible to floods and droughts. The impacts of floods and droughts on water availability and quality is increasing as a result of their increase in magnitude and frequency. The LRB encompasses a large diversity of physical and socio-economical characteristics spread across four Southern Africa countries (Botswana, Mozambique, South Africa and Zimbabwe). This dictates highly heterogeneous physical and human responses, coping mechanisms, and policy frameworks from local to transboundary scales.

Understanding the multidimensional connections that exist between and within flood and drought events and cycles, between various regions across the basin, between physical and social impacts, and between users and decision-makers, is critical to sustainable water resources management and long-term resilience to hydrological extremes.

The Connect4 Water Resilience project has brought together an international multidisciplinary team of hydrologists and social scientists from academia, policy, and practice to investigate the drivers and impacts of floods and droughts, and to promote solutions towards adaptation. In our research we deployed hydrological and geological investigations alongside community and governance interviews and workshops across the LRB to jointly feed in the application of a large-scale transboundary hydrological model of the LRB. Model assessment and future management scenario definition and analysis were implemented collaboratively with stakeholders across the basin, through iterative workshops at local, national, and transboundary scales.

Results so far revealed: (1) the high complementarity of physical (hydrological and sedimentological) and social (community narrative) data to reconstruct spatiotemporal dynamics and impacts of events, which has been crucial to model application in the basin affected by highly fragmented monitoring; (2) the observed increase in floods and droughts magnitude and frequency is not responsible for significant changes in groundwater recharge, suggesting that the general observed groundwater level decline is to be related to increasing abstraction, which in turn amplifies droughts; (3) flood severity and impacts are higher after droughts regardless of rainfall magnitude; (4) mitigation, through anticipatory action and preparation for floods and droughts at policy, user and community level is uneven and inadequately resourced, with generally some forms of preparation to droughts but little for floods; (5) the uptake of forecast and management recommendations from governments is patchy, while extension officers are playing a key role for communication and NGOs for training; (6) local stakeholder expertise and experience brought in during stakeholder workshops were critical to groundwater model conceptualisation, and management scenario definition and analysis; (7) preferred scenarios of management strategies, as collaboratively defined with stakeholders, were highly variable across the LRB countries and sub-regions, including preference for local water management (e.g. temporary flood water storage for subsequent droughts) in upstream upland regions vs large scale strategies (e.g. storage in dams) in downstream floodplain regions; however, hydrological model outputs showed that local/regional strategies have basin-scale (transboundary) impacts emphasizing the importance of transboundary cooperation and management of water resources and extreme events.

Research outcomes are being translated into tailored guidance for policy and practice including feeding in ongoing early warning system development and sustainable water resource management.

How to cite: Comte, J.-C., Artur, L., Bharucha, Z., Chirindja, F., Day, R., Dube, J., Franchi, F., Geris, J., Hussey, S., Makaya, E., Matano, A., Mustafa, S., Nesamvuni, E., Olabode, O., Rohse, M., Taylor, S., Tirivarombo, S., and Van Loon, A.: Adaptation to floods and droughts in (semi) arid transboundary basins: insights, barriers and opportunities drawn from socio-hydrogeological research in the Limpopo river basin, Southern Africa, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11819, https://doi.org/10.5194/egusphere-egu22-11819, 2022.

EGU22-12846 | Presentations | ITS3.2/HS1.1.8

Reflections on collaboration and capacity-building for sustainable groundwater quality monitoring in rural Malawi 

Fortune Gomo, Sarah Halliday, Wiktor Chichlowski, Susan Chichloska, Harlod Zaunda, and Alistair Geddes

Drinking water quality is a key component of water security to ensure clean and safe water supplies to achieve the Global SDG6. Yet frequently there are capacity constraints on the adequacy and sustained water quality monitoring programs in LDC contexts, especially in rural areas where resources are more limited and the resident population is more reliant on scattered independent groundwater supplies. In Malawi, knowledge of the importance of water quality has been developing over recent years, necessitating local capacity development for sufficient and sustained water quality monitoring.

International, transdisciplinary, and interdisciplinary research collaboration and capacity-building efforts in rural water quality monitoring can be a vehicle to improve technology development that supports operational monitoring and data reporting in resource-poor settings. However, in cognate fields, similar international partnership models have drawn some criticism of late, because of their alleged tendency to not translate collaboration agreements into demonstrable local capacity gains. We, therefore, link our consideration of these issues specific to our direct input to efforts to create a new water quality testing program in rural southern Malawi in southern Africa in a collaborative research project between the University of Dundee and Fisherman’s Rest, a local NGO in Malawi. Fisherman’s Rest works with rural communities in Malawi, specifically borehole monitoring under the Madzi Alipo program. However, their work lacked the water quality monitoring component, a key element to water security. Using our reflections, we find that the line of critique on international collaborations has some value in terms of thinking about how to advance ‘genuine’ collaboration and capacity-building in water quality monitoring programs as we look to expand our collaboration efforts with Fisherman’s Rest and other stakeholders in rural water quality monitoring in Malawi.

How to cite: Gomo, F., Halliday, S., Chichlowski, W., Chichloska, S., Zaunda, H., and Geddes, A.: Reflections on collaboration and capacity-building for sustainable groundwater quality monitoring in rural Malawi, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12846, https://doi.org/10.5194/egusphere-egu22-12846, 2022.

Atmospheric water management or cloud seeding technologies might be effectively applied to assess the impacts from changing climate on water security and renewable energy use. During said assessments it might be possible to exploit their observations to mitigate the negative impacts from climate change by enhancing the water supply as part of a water security plan, and/or by effectively removing low-level supercooled cloud decks/fogs to facilitate renewable energy use providing added sunshine during typically overcast day-time periods. Cloud seeding technologies are used to positively affect the natural hydrologic cycle, while respecting and avoiding damage to public health, safety and the environment.  This talk summarizes atmospheric water management technologies and their use, how these technologies might be applied as part of a strategy to ensure water security and how their application might provide a potential opportunity for recouping lost energy potential.

How to cite: DeFelice, T.: The role atmospheric water management technologies might play in Nature-based solutions (NbS), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1941, https://doi.org/10.5194/egusphere-egu22-1941, 2022.

EGU22-2263 | Presentations | GI6.3

EasyGeoModels: a New Tool to Investigate Seismic and Volcanic Deformations Retrieved through Geodetic Data. Software Implementation and Examples on the Campi Flegrei Caldera and the 2016 Amatrice Earthquake 

Giuseppe Solaro, Sabatino Buonanno, Raffaele Castaldo, Claudio De Luca, Adele Fusco, Mariarosaria Manzo, Susi Pepe, Pietro Tizzani, Emanuela Valerio, Giovanni Zeni, Simone Atzori, and Riccardo Lanari

The increasingly widespread use of space geodesy has resulted in numerous, high-quality surface deformation data sets. DInSAR, for instance, is a well-established satellite technique for investigating tectonically active and volcanic areas characterized by a wide spatial extent of the inherent deformation. These geodetic data can provide important constraints on the involved fault geometry and on its slip distribution as well as on the type and position of an active magmatic source. For this reason, over last years, many researchers have developed robust and semiautomatic methods for inverting suitable models to infer the source type and geometry characteristics from the retrieved surface deformations.

In this work we will present a new software we have implemented, named easyGeoModels, that can be used by geophysicists but also by less skilled users who are interested in sources modeling to determine ground deformation in both seismo-tectonic and volcanic contexts. This software is characterized by some innovative aspects compared to existing similar tools, such as (i) the presence of an easy-to-use graphic interface that allows the user, even if not particularly expert, to manage the data to be inverted, the input parameters of one or more sources, the choice of the deformation source (s), effective and simple way; (ii) the possibility of selecting the GPS data to be inverted, simply by selecting the area of interest: in this case the software will automatically consider for the inversion only the GPS stations present in the selected area and will download the relative data from the Nevada Geodetic Laboratory site; (iii) the generation of output files in Geotiff, KMZ and Shapefile format, which allow a faster and more immediate visualization through GIS tools or Google Earth.

Finally, as applications, we will show some preliminary results obtained through the easyGeoModels software on areas characterized by huge deformation both in a volcanic context, such as that of the Campi Flegrei caldera, and a seismo-tectonic one, as for the case of the Amatrice earthquake (central Italy) which occurred on 24 August 2016.

How to cite: Solaro, G., Buonanno, S., Castaldo, R., De Luca, C., Fusco, A., Manzo, M., Pepe, S., Tizzani, P., Valerio, E., Zeni, G., Atzori, S., and Lanari, R.: EasyGeoModels: a New Tool to Investigate Seismic and Volcanic Deformations Retrieved through Geodetic Data. Software Implementation and Examples on the Campi Flegrei Caldera and the 2016 Amatrice Earthquake, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2263, https://doi.org/10.5194/egusphere-egu22-2263, 2022.

EGU22-4876 | Presentations | GI6.3 | Highlight

Geodetic imaging of the magma ascent process during the 2021 Cumbre Vieja (La Palma, Canary Islands) eruption 

Monika Przeor, José Barrancos, Raffaele Castaldo, Luca D’Auria, Antonio Pepe, Susi Pepe, Takeshi Sagiya, Giuseppe Solaro, and Pietro Tizzani

On the 11th of September of 2021, a seismic sequence began on La Palma (Canary Islands), followed by a rapid and significant ground deformation reaching more than 10 cm in the vertical component of the permanent GNSS station ARID (Aridane) operated by the Instituto Volcanológico de Canarias (INVOLCAN). The pre-eruptive episode lasted only nine days and was characterized by an intense deformation in the western part of the island and intense seismicity with the upward migration of hypocenters. After the onset of the eruption, which occurred on the 19th of September of 2021, the deformation increased a few cm more, reaching a maximum on the 22nd of September and subsequently showing a nearly steady deflation trend in the following months.

We obtained a Sentinel-1 DInSAR dataset along both ascending and descending orbits, starting from the 27th of February of 2021 and the 13th of January of 2021, respectively. We selected the study area at the radial distance of 13 km from the eruption point (Latitude: 28.612; Longitude: -17.866) to realize an inverse model of the geometry of the causative sources of the observed ground deformation. While the ascending orbit that passed on the 18th of September indicated mainly a dike intrusion in the shallow depth, the descending orbit from the 20th of September seemed to indicate a deformation caused by at least two sources: the pre-eruptive intrusion and the nearly-vertical eruptive dike. The deeper source spatially coincides with the location of most of the pre-eruptive volcano-tectonic hypocenters.

Finally, based on the preliminary inverse model of the DInSAR dataset, we applied the geodetic imaging of D’Auria et al., (2015) to retrieve the time-varying spatial distribution of volumetric ground deformation sources. The final results show the kinematics of the upward dike propagation and magma ascent.

 

References

D’Auria, L., Pepe, S., Castaldo, R., Giudicepietro, F., Macedonio, G., Ricciolino, P., ... & Zinno, I. (2015). Magma injection beneath the urban area of Naples: a new mechanism for the 2012–2013 volcanic unrest at Campi Flegrei caldera. Scientific reports, 5(1), 1-11.

How to cite: Przeor, M., Barrancos, J., Castaldo, R., D’Auria, L., Pepe, A., Pepe, S., Sagiya, T., Solaro, G., and Tizzani, P.: Geodetic imaging of the magma ascent process during the 2021 Cumbre Vieja (La Palma, Canary Islands) eruption, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4876, https://doi.org/10.5194/egusphere-egu22-4876, 2022.

EGU22-5431 | Presentations | GI6.3

Modeling Potential Impacts of Gas Exploitation on the Israeli Marine Ecosystem Using Ecopath with Ecosim 

Ella Lahav, Peleg Astrahan, Eyal Ofir, Gideon Gal, and Revital Bookman

Exploration, production, extraction and transport of fossil fuels in the marine environment are accompanied by an inherent risk to the surrounding ecosystems as a result of the on-going operations or due to technical faults, accidents or geo-hazards. Limited work has been conducted on potential impacts on the Mediterranean marine ecosystem due to the lack of information on organism responses to hydrocarbon pollution. In this study, we used the Ecopath with Ecosim (EwE) modeling software which is designed for policy evaluation and provides assessments of impacts of various stressors on an ecosystem. An existing EwE based Ecospace food-web model of the Israeli Exclusive Economic Zone (EEZ) was enhanced to include local organism response curves to various levels of contaminants, such as crude oil, in the water and on the sea floor sediments. The goal of this study is to evaluate and quantify the possible ecological impacts of pollution events that might occur due to fossil fuel exploitation related activities. Multiple spatial static and dynamic scenarios, describing various pollution quantities and a range of habitats and locations were constructed. Using the enhanced Ecospace models for assessing the potential impacts of gas exploitation on organism biomass, the spatial and temporal distribution and food-web functioning was tested and evaluated. The results of this study will show a quantitative assessment of the expected ecological impacts that could assist decision makers in developing management and conservation strategies.

How to cite: Lahav, E., Astrahan, P., Ofir, E., Gal, G., and Bookman, R.: Modeling Potential Impacts of Gas Exploitation on the Israeli Marine Ecosystem Using Ecopath with Ecosim, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5431, https://doi.org/10.5194/egusphere-egu22-5431, 2022.

EGU22-5618 | Presentations | GI6.3

Slope stability monitoring system via three-dimensional simulations of rockfalls in Ischia island, Southern Italy 

Ada De Matteo, Massimiliano Alvioli, Antonello Bonfante, Maurizio Buonanno, Raffaele Castaldo, and Pietro Tizzani

Volcanoes are dynamically active systems in continuous evolution. This behaviour is emphasized by many different processes, e.g., fumarolic activity, earthquakes, volcanic slope instabilities and volcanic climax eruptions. Volcanic edifices experience slope instability as consequence of different solicitations such as i) eruption mechanism and depositional process, ii) tectonic stresses, iii) extreme weather conditions; all these events induce the mobilization of unstable fractured volcanic flanks.

Several methods exist to gather information about slope stability and to map trajectories followed by individual falling rocks in individual slopes. These methods involve direct field observation, laser scanning, terrestrial or aerial photogrammetry. Such information is useful to infer the likely location of future rockfalls, and represent a valuable input for the application of three-dimensional models for rockfall trajectories.

The Ischia island is volcano-tectonic horst that is a part of the Phlegrean Volcanic District, Southern Italy. It covers an area of about 46 km2 and it has experienced a remarkable ground uplift events due to a resurgence phenomenon. Slope instability is correlated both with earthquakes events and with volcanism phenomena. Specifically, evidences suggest that rockfalls occurred as an effect of the gravitational instability on the major scarps generated by the rapid resurgence, eased by the widespread rock fracturing.

We present results of an analysis relevant to the most probable individual masses trajectories of rockfall affecting the slopes of Ischia island. We first identified the prospective rockfall sources through an expert-mapping of source area in sample locations and statistical analysis on the whole island. Probabilistic sources are the main input of the three-dimensional rockfalls simulation software STONE.

The software assumes point-like masses falling under the sole action of gravity and the constraints of topography, and it calculates trajectories dominated by ballistic dynamics during falling, bouncing and rolling on the ground. Analysis of high-definition critical sector pictures, achieved by using UAV (Unmanned Aerial Vehicle) platform, will allow a detailed localization of source areas and an additional more robust simulations.

The procedure can be viewed as a multiscale analysis and allows besting allocating computational efforts and economic resources, focusing on a more detailed analysis on the slopes identified as the most risky ones during the first, large-scale analysis of the whole area.

How to cite: De Matteo, A., Alvioli, M., Bonfante, A., Buonanno, M., Castaldo, R., and Tizzani, P.: Slope stability monitoring system via three-dimensional simulations of rockfalls in Ischia island, Southern Italy, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5618, https://doi.org/10.5194/egusphere-egu22-5618, 2022.

EGU22-6226 | Presentations | GI6.3

The framework for improving air quality monitoring over Indian cities 

Arindam Roy, Athanasios Nenes, and Satoshi Takahama

Indian air quality monitoring guideline is directly adopted from World Health Organization (1977) guidelines without place-based modification. According to Indian air quality guidelines (2003), the location of monitoring sites should be determined from air quality modeling and previous air quality information. If such information is not available, the use of emission densities, wind data, land-use patterns and population information is recommended for prioritizing areas for air quality monitoring. The mixed land-use distribution over Indian cities and randomly distributed sources pose serious challenges, as Indian cities (unlike in other parts of the world) are characterized by a lack of distinct residential, commercial, and industrial regions, so the concept of “homogeneous emissions” (which have guided site monitoring decisions) simply does not apply. In addition, the decision-making data emission and population information, are either not available or outdated for Indian cities. Unlike the cities in Global North, the Indian urban-scape has distinguished features in terms of land use, source and population distribution which has not been addressed in air quality guidelines.

We have developed an implementable place-based framework to address the above problem of establishing effective new air quality stations in India and other regions with complex land-use patterns. Four Indian million-plus cities were selected for the present study; Lucknow, Pune, Nashik and Kanpur. We broadly classified air quality monitoring objectives into three; monitoring population exposure, measurements for compliance with the national standards and characterization of sources. Each monitoring station over four cities was evaluated and metadata has been created for each station to identify its monitoring objective for each of the stations. We find that present air quality monitoring networks are highly inadequate in characterizing average population exposure throughout each city, as current stations are predominantly located at the site of pedestrian exposure, and are not representative of the city-wide exposure.

Possible new sites for monitoring were identified using night-time light data, satellite-derived PM2.5, existing emission inventories, land-use patterns and other ancillary open-sourced data. Over Lucknow, Pune and Nashik, setting up stations at highly populated areas is recommended to fulfill the knowledge gaps on the average population exposure. Over Kanpur, it was recommended to incorporate stations to measure short-term pollution exposure in traffic and industrial sites. Rapidly developing peri-urban regions were identified using night-time light data and recommendations were provided for setting up monitoring stations in these regions.

How to cite: Roy, A., Nenes, A., and Takahama, S.: The framework for improving air quality monitoring over Indian cities, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6226, https://doi.org/10.5194/egusphere-egu22-6226, 2022.

EGU22-6374 | Presentations | GI6.3

Geochemical monitoring of the Tenerife North-East and North West Rift Zones by means of diffuse degassing surveys 

Lía Pitti Pimienta, Fátima Rodríguez, María Asensio-Ramos, Gladys Melián, Daniel Di Nardo, Alba Martín-Lorenzo, Mar Alonso, Rubén García-Hernández, Víctor Ortega, David Martínez Van Dorth, María Cordero, Tai Albertos, Pedro A. Hernández, and Nemesio M. Pérez

Tenerife (2,034 km2), the largest island of the Canarian archipelago, is characterized by three volcanic rifts NW-SE, NE-SW and N-S oriented, with a central volcanic structure in the middle, Las Cañadas Caldera, hosting Teide-Pico Viejo volcanic complex. The North-West Rift-Zone (NWRZ) is one of the youngest and most active volcanic systems of the island, where three historical eruptions (Boca Cangrejo in 16th Century, Arenas Negras in 1706 and Chinyero in 1909) have occurred, whereas the North-East Rift-Zone (NERZ) is more complex than the others due to the existence of Pedro Gil stratovolcano that broke the main NE-SW structure 0.8 Ma ago. The most recent eruptive activity along the NERZ took place during 1704 and 1705 across 13 km of fissural eruption in Siete Fuentes (Arafo-Fasnia). To monitor potential volcanic activity through a multidisciplinary approach, diffuse degassing studies have been carried out since 2000 at the NWRZ (72 km2) and since 2001 at the NERZ (210 km2) in a yearly basis. Long-term variations in the diffuse CO2 output in the NWRZ have shown a temporal correlation with the onsets of seismic activity at Tenerife, supporting unrest of the volcanic system, as is also suggested by anomalous seismic activity recorded in the studied area during April, 2004 and October, 2016 (Hernández et al., 2017). In-situ measurements of CO2 efflux from the surface environment were performed according to the accumulation chamber method using a portable non-dispersive infrared (NDIR) sensor. Soil CO2 efflux values for the 2021 survey ranged between non-detectable values and 104 g·m-2·d-1, with an average value of 8 g·m-2·d-1 for NWRZ. For NERZ, soil CO2 efflux values ranged between non-detectable values and 79 g·m2·d-1, with an average value of 7 g·m-2·d-1. The probability plot technique applied to the data allowed to distinguish different geochemical populations. Background population represented 49.2% and 74.0% of the total data for NWRZ and NERZ, respectively, with a mean value (1.7 - 2.0 g·m-2·d-1) similar to the background values calculated for other volcanic systems in the Canary Islands with similar soils, vegetation and climate (Hernández et al. 2017). Peak population represented 0.9 and 0.7% for NWRZ and NERZ, respectively and with a mean value of 45 and 57 g·m-2·d-1. Soil CO2 efflux contour maps were constructed to identify spatial-temporal anomalies and to quantify the total CO2 emission using the sequential Gaussian simulation (sGs) interpolation method. Diffuse emission rate of 506 ± 22 t·d-1 for NWRZ and 1,509 ± 58 t·d-1 NERZ were obtained. The normalized CO2 emission value by area was estimated in 7.03 t·d-1·km-1 for NWRZ and in 7.2 t·d-1·km-1 for NERZ. The monitorization of the diffuse CO2 emission contributes to detect early warning signals of volcanic unrest, especially in areas where visible degassing is non-existent as in the Tenerife NWRZ and NERZ.

Hernández et al. (2017). Bull Volcanol, 79:30, DOI 10.1007/s00445-017-1109-9.

How to cite: Pitti Pimienta, L., Rodríguez, F., Asensio-Ramos, M., Melián, G., Di Nardo, D., Martín-Lorenzo, A., Alonso, M., García-Hernández, R., Ortega, V., Martínez Van Dorth, D., Cordero, M., Albertos, T., Hernández, P. A., and Pérez, N. M.: Geochemical monitoring of the Tenerife North-East and North West Rift Zones by means of diffuse degassing surveys, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6374, https://doi.org/10.5194/egusphere-egu22-6374, 2022.

Two moderate earthquakes with magnitude ML5.0 happened on 11th of November 2020 near the Mavrovo lake in northwestern Macedonia. The lake is an artificial lake with a dam built between 1947 and filled by 1953. Its maximum length is 10km, width is 5km and the depth is 50m. Given its water volume, it is possible that geological factors causing earthquakes could also affect the hydrobiological characteristics of the flow system surrounding the lake.

A list of 180 earthquakes registered by the local stations with magnitudes equal or greater than ML1.7 was analysed in terms of temporal and spatial distribution around the lake. No specific clustering of events was noticed in the foreshock period from July 2020. In the aftershock period, the most numerous events lasted about a month after the main events. However, there was another period of increased seismicity during March 2021, followed by gradual decrease onwards. The distribution of epicentres was mainly along the terrain of Radika river and a few smaller tributaries to the lake system.

A comparative analysis was done with the dataset collected by the program run at the department of Biology at the Faculty of Natural Sciences, University UKIM in Skopje. Environmental investigations in Europe have shown stress reactions of hydrobionts in respect to water temperature and heavy metal pollution, for example the influence of radioactive radiation. Earthquake-induced seismic changes most often affect the chemical-physical properties of water quality and temperature stratification, i.e., mixing of water masses. In our research, we analyse for the first time the relationship between the seismological activities in the Jul 2020-Nov 2021 period in details and a possible impact to environment thru the population of macrozoobenthos from Mavrovo Lake.

How to cite: Sinadinovski, C. and Smiljkov, S.: Numerical analysis of Seismic and Hydrobiological data around lake Mavrovo in the period Jul.2020-Nov.2021, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6452, https://doi.org/10.5194/egusphere-egu22-6452, 2022.

EGU22-6468 | Presentations | GI6.3

Measuring greenhouse gas fluxes – what methods do we have versus what methods do we need? 

David Bastviken, Julie Wilk, Nguyen Thanh Duc, Magnus Gålfalk, Martin Karlson, Tina Neset, Tomasz Opach, Alex Enrich Prast, and Ingrid Sundgren

Appropriate methods to measure greenhouse gas (GHG) fluxes are critical for our ability to detect fluxes, understand regulation, make adequate priorities for climate change mitigation efforts, and verify that these efforts are effective. Ideally, we need reliable, accessible, and affordable measurements at relevant scales. We surveyed present GHG flux measurement methods, identified from an analysis of >11000 scientific publications and a questionnaire to sector professionals and analysed method pros and cons versus needs for novel methodology. While existing methods are well-suited for addressing certain questions, this presentation presents fundamental limitations relative to GHG flux measurement needs for verifiable and transparent action to mitigate many types of emissions. Cost and non-academic accessibility are key aspects, along with fundamental measurement performance. These method limitations contribute to the difficulties in verifying GHG mitigation efforts for transparency and accountability under the Paris agreement. Resolving this mismatch between method capacity and societal needs is urgently needed for effective climate mitigation. This type of methodological mismatch is common but seems to get high priority in other knowledge domains. The obvious need to prioritize development of accurate diagnosis methods for effective treatments in healthcare is one example. This presentation provides guidance regarding the need to prioritize the development of novel GHG flux measurement methods.

How to cite: Bastviken, D., Wilk, J., Duc, N. T., Gålfalk, M., Karlson, M., Neset, T., Opach, T., Enrich Prast, A., and Sundgren, I.: Measuring greenhouse gas fluxes – what methods do we have versus what methods do we need?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6468, https://doi.org/10.5194/egusphere-egu22-6468, 2022.

EGU22-8458 | Presentations | GI6.3

Temporal evolution of dissolved gases in groundwater of Tenerife Island 

Cecilia Amonte, Nemesio M. Pérez, Gladys V. Melián, María Asensio-Ramos, Eleazar Padrón, Pedro A. Hernández, and Ana Meire Feijoo

The oceanic active volcanic island of Tenerife (2,034 km2) is the largest of the Canarian archipelago. There are more than 1,000 galleries (horizontal drillings) in the island, which are used for groundwater exploitation and allow reaching the aquifer at different depths and elevations. This work presents the first extensive study on the temporal variation of dissolved gases in groundwaters from Fuente del Valle and San Fernando galleries (Tenerife, Spain) since April 2016 to June 2020. This investigation is focused on the chemical and isotopic content of several dissolved gas species (CO2, He, O2, N2 and CH4) present in the groundwaters and its relationship with the seismic activity registered in the island. The results show CO2 as the major dissolved gas specie in the groundwater from both galleries presenting a mean value of 260 cm3STP·L-1 and 69 cm3STP·L-1 for Fuente del Valle and San Fernando, respectively. The average δ13C-CO2 data (-3.9‰ for Fuente del Valle and -6.4‰ for San Fernando) suggest a clear endogenous origin as result of interaction of them with deep-origin fluid. A bubbling gas sample from Fuente del Valle gallery was analysed, obtaining a CO2 rich gas (87 Vol.%) with a considerable He enrichment (7.3 ppm). The isotopic data of both components in the bubbling gas support the results obtained in the dissolved gases, showing an endogenous component that could be affected by the different activity of the hydrothermal system. During the study period, an important seismic swarm occurred on October 2, 2016, followed by an increase of the seismic activity in and around Tenerife. After this event, important geochemical variations were registered in the dissolved gas species, such as dissolved CO2 and He content and the CO2/O2, He/CO2, He/N2 and CH4/CO2 ratios. These findings suggest an injection of fluids into the hydrothermal system during October 2016, a fact that evidences the connection between the groundwaters and the hydrothermal system. The present work demonstrates the importance of dissolved gases studies in groundwater for volcanic surveillance.

How to cite: Amonte, C., Pérez, N. M., Melián, G. V., Asensio-Ramos, M., Padrón, E., Hernández, P. A., and Meire Feijoo, A.: Temporal evolution of dissolved gases in groundwater of Tenerife Island, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8458, https://doi.org/10.5194/egusphere-egu22-8458, 2022.

Land surface temperature (LST) is a manifestation of the surface thermal environment (LSTE) and an important driver of physical processes of surface land energy balance at local to global scales. Tenerife is one of the most heterogeneous islands among the Canaries from a climatological and bio-geographical point of view. We study the surface thermal conditions of the volcanic island with remote sensing techniques. In particular, we consider a time series of Landsat 8 (L8) level 2A images for the period 2013 to 2019 to estimate LST from surface reflectance (SR) and brightness Temperature (BT) images. A total of 26 L8 dates were selected based on cloud cover information from metadata (land cloud cover < 10%) to estimate pixel-level LST with an algorithm based on Radiative Transfer Equations (RTE). The algorithm relies on the Normalized Difference Vegetation Index (NDVI) for estimating emissivity pixel by pixel. We apply the Independent Component Analysis (ICA) that revealed to be a powerful tool for data mining and, in particular, to separate multivariate LST dataset into a finite number of components, which have the maximum relative statistical independence. The ICA allowed separating the land surface temperature time series of Tenerife into 11 components that can be associated with geographic and bioclimatic zones of the island. The first ten components are related to physical factors, the 11th component, on the contrary, presented a more complex pattern resulting possibly from its small amplitude and the combination of various factors into a single component. The signal components recognized with the ICA technique, especially in areas of active volcanism, could be the basis for the space-time monitoring of the endogenous component of the LST due to surface hydrothermal and/or geothermal activity. Results are encouraging, although the 16-day revisit frequency of Landsat reduces the frequency of observation that could be increased by applying techniques of data fusion of medium and coarse spatial resolution images. The use of such systems for automatic processing and analysis of thermal images may in the future be a fundamental tool for the surveillance of the background activity of active and dormant volcanoes worldwide.

How to cite: Stroppiana, D., Przeor, M., D’Auria, L., and Tizzani, P.: Analysis of thermal regimes at Tenerife(Canary Islands) with Independent Component Analysis applied to time series of Remotely Sensed Land Surface Temperatures, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8580, https://doi.org/10.5194/egusphere-egu22-8580, 2022.

EGU22-9376 | Presentations | GI6.3

An IoT based approach to ultra high resolution air quality mapping thorigh field calibrated monitoring devices 

Saverio De Vito, Grazia Fattoruso, and Domenico Toscano

Recent advances in IoT and chemical sensors calibration technologies have led to the proposal of Hierarchical air quality monitoring networks. They are indeed complex systems relying on sensing nodes which differs from size, cost, accuracy, technology, maintenance needs while having the potential to empower smart cities and communiities with increased knowledge  on the highly spatiotemporal variance Air Quality phenomenon (see [1]). The AirHeritage project, funded by Urban Innovative Action program have developed and implemented a hierarchical monitoring system which allows for offering real time assessments and model based forecasting services including 7 fixed low cost sensors station, one (mobile and temporary located) regulatory grade analyzer and a citizen science based ultra high resolution AQ mapping tool based on field calibrated mobile analyzers. This work will analyze the preliminary results of the project by focusing on the machine learning driven sensors calibration methodology and citizen science based air quality mapping campaigns. Thirty chemical and particulate matter multisensory devices have been deployed in Portici, a 4Km2 city located 7 km south of Naples which is  affected by significant car traffic. The devices have been  entrusted to local citizens association for implementing 1 preliminary validation campaign (see [2]) and 3 opportunistic 2-months duration monitoring campaigns. Each 6 months, the devices undergoes a minimum 3 weeks colocation period with a regulatory grade analyzer allowing for training and validation dataset building. Multilinear regression sw components are trained to reach ppb level accuracy (MAE <10ug/m^3 for NO2 and O3, <15ug/M^3 for PM2.5 and PM10, <300ug/M^3 for CO) and encoded in a companion smartphone APP which allows the users for real time assessment of personal exposure. In particular, a novel AQI strongly based on European Air Quality Index ([3]) have been developed for AQ real time data communication. Data have been collected using a custom IoT device management platform entrusted with inception, storage and data-viz roles. Finally data have been used to build UHR (UHR) AQ maps, using spatial binning approach (25mx25m) and median computation for each bin receiving more than 30 measurements during the campaign. The resulting maps have hown the possibility to allow for pinpointing city AQ hotpots which will allows fact-based remediation policies in cities lacking objective technologies to locally assess concentration exposure.  

 

[1] Nuria Castell et Al., Can commercial low-cost sensor platforms contribute to air quality monitoring and exposure estimates?, Environment International, Volume 99, 2017, Pages 293-302 ISSN 0160-4120, https://doi.org/10.1016/j.envint.2016.12.007.

[2] De Vito, S, et al., Crowdsensing IoT Architecture for Pervasive Air Quality and Exposome Monitoring: Design, Development, Calibration, and Long-Term Validation. Sensors 202121, 5219. https://doi.org/10.3390/s21155219

[3] https://airindex.eea.europa.eu/Map/AQI/Viewer/

How to cite: De Vito, S., Fattoruso, G., and Toscano, D.: An IoT based approach to ultra high resolution air quality mapping thorigh field calibrated monitoring devices, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9376, https://doi.org/10.5194/egusphere-egu22-9376, 2022.

EGU22-10290 | Presentations | GI6.3

Soil gas Rn monitoring at Cumbre Vieja prior and during the 2021 eruption, La Palma, Canary Islands 

Daniel Di Nardo, Eleazar Padrón, Claudia Rodríguez-Pérez, Germán D. Padilla, José Barrancos, Pedro A. Hernández, María Asensio-Ramos, and Nemesio M. Pérez

Cumbre Vieja volcano (La Palma, Canary Islands, Spain) suffered a volcanic eruption that started on September 19 and finished on December 13, 2021. The eruption is considered the longest volcanic event since data are available on the island: it finished after 85 days and 8 hours of duration and 1,219 hectares of lava flows. La Palma Island is the fifth in extension (706 km2) and the second in elevation (2,423 m a.s.l.) of the Canarian archipelago. Cumbre Vieja volcano, where the volcanic activity has taken place exclusively in the last 123 ka, forms the sand outhern part of the island. In 2017, two remarkable seismic swarms interrupted a seismic silence of 46 years in Cumbre Vieja volcano with earthquakes located beneath Cumbre Vieja volcano at depths ranging between 14 and 28 km with a maximum magnitude of 2.7. Five additional seismic swarms were registered in 2020 and four in 2021. The eruption started ~1 week after the start of the last seismic swarm.

As part of the INVOLCAN volcano monitoring program of Cumbre Vieja, soil gas radon (222Rn) and thoron (220Rn) is being monitored at five sites in Cumbre Vieja using SARAD RTM2010-2 RTM 1688-2 portable radon monitors. 222Rn and 220Rn are two radioactive isotopes of radon with a half-life of 3.8 days and 54.4 seconds, respectively. Both isotopes can diffuse easily trough the soil and can be detected at very low concentrations, but their migration in large scales, ten to hundreds of meters, is supported by advection (pressure changes) and is related to the existence of a carrier gas source (geothermal fluids or fluids linked to magmatic and metamorphic phenomena), and to the existence of preferential routes for degassing (deep faults). Previous results on the monitoring of soil Rn in the Canary Islands with volcano monitoring purposes are promising (Padilla et al, 2013).     

The most remarkable result of the Rn monitoring network of Cumbre Vieja was observed in LPA01 station, located at the north-east of Cumbre Vieja. Since mid-March 2021, soil 222Rn activity experienced a sustained until reaching maximum values of ~1.0E+4 222Rn Bq/m3 days before the eruption onset. During the eruptive period, soil 222Rn activity showed a gradual decreasing trend. The increase of magmatic-gas pressure due to magma movement towards the surface and the transport of anomalous 222Rn originated from hydrofracturing of rock, from direct magma degassing or from both, is the most plausible explanation for the increases in radon activity before the eruption onset observed at LPA01. As soil gas radon activity increased prior to the eruption onset, this monitoring technique can be efficiently used as an initial warning sign of the pressurization of magma beneath La Palma Island.

Padilla, G. D., et al. (2013), Geochem. Geophys. Geosyst., 14, 432–447, doi:10.1029/2012GC004375.

 

How to cite: Di Nardo, D., Padrón, E., Rodríguez-Pérez, C., Padilla, G. D., Barrancos, J., Hernández, P. A., Asensio-Ramos, M., and Pérez, N. M.: Soil gas Rn monitoring at Cumbre Vieja prior and during the 2021 eruption, La Palma, Canary Islands, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10290, https://doi.org/10.5194/egusphere-egu22-10290, 2022.

EGU22-10603 | Presentations | GI6.3 | Highlight

The "Campania Trasparente" multiscale and multimedia monitoring project: an unprecedented experience in Italy. 

Stefano Albanese, Annamaria Lima, Annalise Guarino, Chengkai Qu, Domenico Cicchella, Mauro Esposito, Pellegrino Cerino, Antonio Pizzolante, and Benedetto De Vivo

In 2015, the "Campania Trasparente" project (http://www.campaniatrasparente.it), a monitoring plan focused on assessing the environmental conditions of the territory of the Campania region, started thanks to the financial support of the regional government. The project's general management was in charge of the Experimental Zooprophylactic Institute of Southern Italy (IZSM).
In the project framework, the collection and analysis of many environmental and biological samples (including soil and air and human blood specimen) were completed. The primary aim of the whole project was to explore the existence of a link between the presence of some illnesses in the local population and the status of the environment and generate a reliable database to assess local foodstuff healthiness.
Six research units were active in the framework of the project. As for soil and air, the Environmental Geochemistry Working Group (EGWG) at the Department of Earth, Environment and Resources Sciences, University of Naples Federico II, was in charge of most of the research activities. Specifically, the EGWG completed the elaboration of the data on potentially toxic metals/metalloids (PTMs) and organic contaminants (PAHs, OCPs, Dioxins) in the regional soils and air.
The monitoring of air contaminants lasted more than one year, and it was completed employing passive air samplers (PAS) and deposimeters spread across the whole region.
Three volumes were published, including statistical elaborations and geochemical maps of all the contaminants analysed to provide both the regional government and local scientific and professional community with a reliable tool to approach local environmental problems starting from a sound base of knowledge.
Geochemical distribution patterns of potentially toxic elements (PTEs), for example, were used to establish local geochemical background/baseline intervals for those metals (naturally enriched in regional soils) found to systematically overcome the national environmental guidelines (set by the Legislative Decree 152/2006).
Data from the air, analysed in terms of concentration and time variation, were, instead, fundamental to discriminate the areas of the regional territory characterised by heavy contamination associated with the emission of organic compounds from anthropic sources.

The integration of all the data generated within the "Campania Trasparente" framework, including the data proceeding from the Susceptible Population Exposure Study (SPES), focusing on human biomonitoring (based on blood), allowed the development of a regional-wide conceptual model to be used as a base to generate highly specialised risk assessments for regional population and local communities affected by specific environmental problems.

How to cite: Albanese, S., Lima, A., Guarino, A., Qu, C., Cicchella, D., Esposito, M., Cerino, P., Pizzolante, A., and De Vivo, B.: The "Campania Trasparente" multiscale and multimedia monitoring project: an unprecedented experience in Italy., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10603, https://doi.org/10.5194/egusphere-egu22-10603, 2022.

EGU22-10659 | Presentations | GI6.3

Long-term variations of diffuse CO2, He and H2 at the summit crater of Teide volcano, Tenerife, Canary Islands during 1999-2021 

Germán D. Padilla, Fátima Rodríguez, María Asensio-Ramos, Gladys V. Melián, Mar Alonso, Alba Martín-Lorenzo, Beverley C. Coldwell, Claudia Rodríguez, Jose M. Santana de León, Eleazar Padrón, José Barrancos, Luca D'Auria, Pedro A. Hernández, and Nemesio M. Pérez

Tenerife Island (2,034 km2) is the largest island of the Canarian archipelago. Its structure is controlled by a volcano-tectonic rift-system with NW, NE and NS directions, with the Teide-Pico Viejo volcanic system located in the intersection. Teide is 3,718 m.a.s.l. high and its last eruption occurred in 1798 through an adventive cone of Teide-Pico Viejo volcanic complex. Although Teide volcano shows a weak fumarolic system, volcanic gas emissions observed in the summit cone consist mostly of diffuse CO2 degassing.

 

In this study we investigate the Teide-Pico Viejo volcanic system evolution using a comprehensive diffuse degassing geochemical dataset 216 geochemical surveys have been performed during the period 1999-2021 at the summit crater of Teide Volcano covering an area of 6,972 m2. Diffuse CO2 emission was estimated in 38 sampling sites, homogeneously distributed inside the crater, by means of a portable non dispersive infrared (NDIR) CO2 fluxmeter using the accumulation chamber method. Additionally, soil gases were sampled at 40 cm depth using a metallic probe with a 60 cc hypodermic syringe and stored in 10 cc glass vials and send to the laboratory to analyse the He and H2 content by means of quadrupole mass spectrometry and micro-gas chromatography, respectively. To estimate the He and H2 emission rates at each sampling point, the diffusive component was estimated following the Fick’s law and the convective emission component model was estimated following the Darcy’s law. In all cases, spatial distribution maps were constructed averaging the results of 100 simulations following the sequential Gaussian simulation (sGs) algorithm, in order to estimate CO2, He and H2 emission rates.

 

During 22 years of the studied period, CO2 emissions ranged from 2.0 to 345.9 t/d, He emissions between 0.013 and 4.5 kg/d and H2 between 1.3 and 64.4 kg/d. On October 2, 2016, a seismic swarm of long-period events was recorded on Tenerife followed by an increase of the seismic activity in and around the island (D’Auria et al., 2019; Padrón et al., 2021). Several geochemical parameters showed significant changes during ∼June–August of 2016 and 1–2 months before the occurrence of the October 2, 2016, long-period seismic swarm (Padrón et al., 2021). Diffuse degassing studies as useful to conclude that the origin of the 2 October 2016 seismic swarm an input of magmatic fluids triggered by an injection of fresh magma and convective mixing. Thenceforth, relatively high values have been obtained in the three soil gases species studied at the crater of Teide, with the maximum emission rates values registered during 2021. This increase reflects a process of pressurization of the volcanic-hydrothermal system. This increment in CO2, He and H2 emissions indicate changes in the activity of the system and can be useful to understand the behaviour of the volcanic system and to forecast future volcanic activity. Monitoring the diffuse degassing rates has demonstrated to be an essential tool for the prediction of future seismic–volcanic unrest, and has become important to reduce volcanic risk in Tenerife.

D'Auria, L., et al. (2019). J. Geophys. Res.124,8739-8752

Padrón, E., et al., (2021). J. Geophys. Res.126,e2020JB020318

How to cite: Padilla, G. D., Rodríguez, F., Asensio-Ramos, M., Melián, G. V., Alonso, M., Martín-Lorenzo, A., Coldwell, B. C., Rodríguez, C., Santana de León, J. M., Padrón, E., Barrancos, J., D'Auria, L., Hernández, P. A., and Pérez, N. M.: Long-term variations of diffuse CO2, He and H2 at the summit crater of Teide volcano, Tenerife, Canary Islands during 1999-2021, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10659, https://doi.org/10.5194/egusphere-egu22-10659, 2022.

EGU22-11493 | Presentations | GI6.3

Analysis and Modelling of 2009-2013 Unrest Episodes at Campi Flegrei Caldera 

Raffaele Castaldo, Giuseppe Solaro, and Pietro Tizzani

Geodetic modelling is a valuable tool to infer volume and geometry of volcanic source system; it represents a key procedure for detecting and characterizing unrest and eruption episodes. In this study, we analyse the 2009–2013 uplift phenomenon at Campi Flegrei (CF) caldera in terms of spatial and temporal variations of the stress/strain field due to the effect of the retrieved inflating source. We start by performing a 3D stationary finite element (FE) modelling of geodetic datasets to retrieve the geometry and location of the deformation source. 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. We optimize our model parameters by exploiting two different geodetic datasets: the GPS data and DInSAR measurements. The modelling results suggest that the best-fit source is a three-axis oblate spheroid ~3 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 with the DInSAR measurements. Subsequently, starting from the same FE modelling domain, we explore a 3D time-dependent FE model, comparing the spatial and temporal distribution of the shear stress and volumetric strain with the seismic swarms beneath the caldera. Finally, We found that low values of shear stress are observed corresponding with the shallow hydrothermal system where low-magnitude earthquakes occur, whereas high values of shear stress are found at depths of about 3 km, where high-magnitude earthquakes nucleate.

How to cite: Castaldo, R., Solaro, G., and Tizzani, P.: Analysis and Modelling of 2009-2013 Unrest Episodes at Campi Flegrei Caldera, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11493, https://doi.org/10.5194/egusphere-egu22-11493, 2022.

EGU22-11874 | Presentations | GI6.3

Time evolution of Land Surface Temperature (LST) in active volcanic areas detected via integration of satellite and ground-based measurements: the Campi Flegrei caldera (Southern Italy) case study. 

Andrea Barone, Daniela Stroppiana, Raffaele Castaldo, Stefano Caliro, Giovanni Chiodini, Luca D'Auria, Gianluca Gola, Ferdinando Parisi, Susi Pepe, Giuseppe Solaro, and Pietro Tizzani

Thermal features of environmental systems are increasingly investigated after the development of remote sensing technologies; the increasing availability of Earth Observation (EO) missions allows the retrieval of the Land Surface Temperature (LST) parameter, which is widely used for a large variety of applications (Galve et al., 2018). In volcanic environment, the LST is an indicator of the spatial distribution of thermal anomalies at the ground surface, supporting designed tools for monitoring purposes (Caputo et al., 2019); therefore, LST can be used to understand endogenous processes and to model thermal sources.

In this framework, we present the results of activities carried out in the FLUIDs PRIN project, which aims at the characterization and modeling of fluids migration at different scales (https://www.prinfluids.it/). We propose a multi-scale analysis of thermal data at Campi Flegrei caldera (CFc); this area is well known for hosting thermal processes related to both magmatic and hydrothermal systems (Chiodini et al., 2015; Castaldo et al., 2021). Accordingly, data collected at different scales are suitable to search out local thermal trends with respect to regional ones. In particular, in this work we compare LST estimated from Landsat satellite images covering the entire volcanic area and ground measurements nearby the Solfatara crater.

Firstly, we exploit Landsat data to derive time series of LST by applying an algorithm based on Radiative Transfer Equations (RTE) (Qin et al., 2001; Jimenez-Munoz et al., 2014). The algorithm exploits both thermal infrared (TIR) and visible/near infrared (VIS/NIR) bands of different Landsat missions in the period 2000-2021; we used time series imagery from Landsat 5 (L5), Landsat 7 (L7) and Landsat 8 (L8) satellite missions to retrieve the thermal patterns of the CFc area with spatial resolutions of 30 m for VIS/NIR bands and 60 m to 120 m for TIR bands. Theoretical frequency of acquisition of the Landsat missions is 16 days that is reduced over the study area by cloud cover: Landsat images with high cloud cover were in fact discarded from the time series.

In particular, we process both the daily acquisitions as well nighttime data to provide thermal features at the ground surface in the absence of solar radiation. To emphasize the thermal anomalies of endogenous phenomena, the retrieved LST time-series are corrected following these steps: (i) removal of spatial and temporal outliers; (ii) correction for adiabatic gradient of the air with the altitude; (iii) detection and removal of the seasonal component.

Regarding to the ground-based acquisitions, we consider the data collected by the Osservatorio Vesuviano, National Institute of Geophysics and Volcanology (OV- INGV, Italy, Naples); the dataset consists of 151 thermal measurements distributed within the 2004-2021 time-interval and acquired inside the Solfatara and Pisciarelli areas at a depth of 0.01 m below the ground surface. Similarly, we process this dataset following corrections (i) and (iii).

Finally, we compare the temporal evolution of thermal patterns retrieved by the satellite and ground-based measurements, highlighting the supporting information provided by LST and its integration with data at ground.

How to cite: Barone, A., Stroppiana, D., Castaldo, R., Caliro, S., Chiodini, G., D'Auria, L., Gola, G., Parisi, F., Pepe, S., Solaro, G., and Tizzani, P.: Time evolution of Land Surface Temperature (LST) in active volcanic areas detected via integration of satellite and ground-based measurements: the Campi Flegrei caldera (Southern Italy) case study., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11874, https://doi.org/10.5194/egusphere-egu22-11874, 2022.

EGU22-11990 | Presentations | GI6.3

Integrating geophysical, geochemical, petrological and geological data for the thermal and rheological characterization of unconventional geothermal fields: the case study of Long Valley Caldera 

Gianluca Gola, Andrea Barone, Raffaele Castaldo, Giovanni Chiodini, Luca D'Auria, Rubén García-Hernández, Susi Pepe, Giuseppe Solaro, and Pietro Tizzani

We propose a novel multidisciplinary approach to image the thermo-rheological stratification beneath active volcanic areas, such as Long Valley Caldera (LVC), which hosts a magmatic-hydrothermal system. Geothermal facilities near the Casa Diablo locality supply 40 MWe from three binary power plants, exploiting about 850 kg s−1 of 160–180 °C water that circulates within the volcanic sediments 200 to 350 meters deep. We performed a thermal fluid dynamic model via optimization procedure of the thermal conditions of the crust. We characterize the topology of the hot magmatic bodies and the hot fluid circulation (the permeable fault-zones), using both a novel imaging of the a and b parameters of the Gutenberg-Richter law and an innovative procedure analysis of P-wave tomographic models. The optimization procedure provides the permeability of a reservoir (5.0 × 10−14 m2) and of the fault-zone (5.0 · 10−14 – 1.0 × 10−13 m2), as well as the temperature of the magma body (750–800°C). The imaging of the rheological properties of the crust indicates that the brittle/ductile transition occurs about 5 km b.s.l. depth, beneath the resurgent dome. There are again deeper brittle conditions about 15 km b.s.l., agreeing with the previous observations. The comparison between the conductive and the conductive-convective heat transfer models highlights that the deeper fluid circulation efficiently cools the volumes above the magmatic body, transferring the heat to the shallow geothermal system. This process has a significant impact on the rheological properties of the upper crust as the migration of the B/D transition. Our findings show an active magmatic system (6–10 km deep) and confirm that LVC is a long-life silicic caldera system. Furthermore, the occurrence of deep-seated, super-hot geothermal resources 4.5 – 5.0 km deep, possibly in supercritical conditions, cannot be ruled out.

How to cite: Gola, G., Barone, A., Castaldo, R., Chiodini, G., D'Auria, L., García-Hernández, R., Pepe, S., Solaro, G., and Tizzani, P.: Integrating geophysical, geochemical, petrological and geological data for the thermal and rheological characterization of unconventional geothermal fields: the case study of Long Valley Caldera, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11990, https://doi.org/10.5194/egusphere-egu22-11990, 2022.

EGU22-12331 | Presentations | GI6.3 | Highlight

The evaluation of soil organic carbon through VIS-NIR spectroscopy to support the soil health monitoring 

Haitham Ezzy, Anna Brook, Claudio Ciavatta, Francesca Ventura, Marco Vignudelli, and Antonello Bonfante

Increasing the organic matter content of the soil has been presented in the:”4per1000″ proposal as a significant climate mitigation measure able to support the achievement of Sustainable Development Goal 13 - Climate Action of United Nations.

At the same time, the report of the Mission Board for Soil health and Food, "Caring for soil is caring for life," indicates that one of the targets that must be reached by 2030 is the conservation and increase of soil organic carbon stock.  De facto, the panel clearly indicates the soil organic carbon as one of the indicators that can be used to monitor soil health, and at the same time, if the current soil use is sustainable or not.

Thus it is to be expected that the monitoring of SOC will become requested to check and monitor the sustainability of agricultural practices realized in the agricultural areas. For all the above reasons, the development of a reliable and fast indirect methods to evaluate the SOC is necessary to support different stakeholders (government, municipality, farmer) to monitor SOC at different spatial scales (national, regional, local).

Over the past two decades, data mining approaches in spatial modeling of soil organic carbon using machine learning techniques and artificial neural network (ANN) to investigate the amount of carbon in the soil using remote sensing data has been widely considered. Accordingly, this study aims to design an accurate and robust neural network model to estimate the soil organic carbon using the data-based field-portable spectrometer and laboratory-based visible and near-infrared (VIS/NIR, 350−2500 nm) spectroscopy of soils. The measurements will be on two sets of the same soil samples, the first by the standard protocol of requested laboratories for soil scanning, The second set of the soil samples without any cultivation to simulate the soil condition in the sampling field emphasizes the predictive capabilities to achieve fast, cheap and accurate soil status. Carbon soil parameter will determine using, multivariate regression method used for prediction with Least absolute shrinkage and selection operator regression (Lasso) in interval way (high, medium, and low). The results will increase accuracy, precision, and cost-effectiveness over traditional ex-situ methods.

The contribution has been realized within the international EIT Food project MOSOM (Mapping of Soil Organic Matter; https://www.eitfood.eu/projects/mosom)

How to cite: Ezzy, H., Brook, A., Ciavatta, C., Ventura, F., Vignudelli, M., and Bonfante, A.: The evaluation of soil organic carbon through VIS-NIR spectroscopy to support the soil health monitoring, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12331, https://doi.org/10.5194/egusphere-egu22-12331, 2022.

EGU22-12364 | Presentations | GI6.3

Stromboli Volcano observations through the Airborne X-band Interferometric SAR (AXIS) system 

Paolo Berardino, Antonio Natale, Carmen Esposito, Gianfranco Palmese, Riccardo Lanari, and Stefano Perna

Synthetic Aperture Radar (SAR) represents nowadays a well-established tool for day and night and all-weather microwave Earth Oobservation (EO) [1]. In last decades, a number of procedures EO techniques based on SAR data have been indeed devised developed for investigating several natural and anthropic phenomena the monitoring of affecting our planet. Among these, SAR Interferometry (InSAR) and Differential SAR Interferometry (DInSAR) undoubtedly represent a powerful techniques to characterize the deformation processes associated to several natural phenomena, such as eEarthquakes, landslides, subsidences andor volcanic unrest events [2] - [4].

In particular, such techniques can benefit of the operational flexibility offered by airborne SAR systems, which allow us to frequently monitor fast-evolving phenomena, timely reach the region of interest in case of emergency, and observe the same scene under arbitrary flight tracks.

In this work, we present the results relevant to multiple radar surveys carried out over the Stromboli Island, in Italy, through the Italian Airborne X-band Interferometric SAR (AXIS) system. The latter is based on the Frequency Modulated Continuous Wave (FMCW) technology, and is equipped with a three-antenna single-pass interferometric layout [5].

The considered dataset has been collected during three different acquisition campaigns, carried out from July 2019 to June 2021, and consists of radar data acquired along four flight directions (SW-NE, NW-SE, NE-SW, SE-NW), as to describe flight circuits around the island and to illuminate the Stromboli volcano under different points of view.

References

[1] Moreira, P. Prats-Iraola, M. Younis, G. Krieger, I. Hajnsek, K. P. Papathanassiou, “A tutorial on Synthetic Aperture Radar”, IEEE Geoscience and Remote Sensing Magazine, pp. 6-43, March 2013.

[2] Bamler, R., Hartl, P., 1998. Synthetic Aperture Radar Interferometry. Inverse problems, 14(4), R1.

[3] P. Berardino, G. Fornaro, R. Lanari and E. Sansosti, “A new algorithm for surface deformation monitoring based on small baseline differential SAR interferograms”, IEEE Trans. Geosci. Remote Sens., vol. 40, no. 11, pp. 2375-2383, Nov. 2002.

[4] R. Lanari, M. Bonano, F. Casu, C. De Luca, M. Manunta, M. Manzo, G. Onorato, I. Zinno, “Automatic Generation of Sentinel-1 Continental Scale DInSAR Deformation Time Series through an Extended P-SBAS Processing Pipeline in a Cloud Computing Environment”, Remote Sensing, 2020, 12, 2961.

[5] C. Esposito, A. Natale, G. Palmese, P. Berardino, R. Lanari, S. Perna, “On the Capabilities of the Italian Airborne FMCW AXIS InSAR System”, Remote Sens. 2020, 12, 539.

 

How to cite: Berardino, P., Natale, A., Esposito, C., Palmese, G., Lanari, R., and Perna, S.: Stromboli Volcano observations through the Airborne X-band Interferometric SAR (AXIS) system, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12364, https://doi.org/10.5194/egusphere-egu22-12364, 2022.

EGU22-12927 | Presentations | GI6.3 | Highlight

FRA.SI.project - AN INTEGRATED MULTI-SCALE METHODOLOGIES FOR THE ZONATION OF LANDSLIDE-INDUCED HAZARD IN ITALY 

Pietro Tizzani, Paola Reichenbach, Federica Fiorucci, Massimiliano Alvioli, Massimiliano Moscatelli, and Antonello Bonfante and the Fra.Si. Team

Fra. Si. a national research project supported by the Ministry of the Environment and Land and Sea Protection, develops a coherent set of multiscale methodologies for the assessment and zoning of earthquake-induced landslide hazards. To achieve the goal, the project operates at different geographical, temporal, and organizational scales, and in different geological, geomorphological, and seismic-tectonic contexts. Given the complexity, variability, and extent of earthquake-induced landslides in Italy, operating at multiple scales allows you to (a) maximize the use of available data and information; (b) propose methodologies and experiment with models that operate at different scales and in different contexts, exploiting their peculiarities at the most congenial scales and coherently exporting the results at different scales; and (c) obtain results at scales of interest for different users.

The project defines a univocal and coherent methodological framework for the assessment and zoning of earthquake-induced landslide hazard, integrating existing information and data on earthquake-induced landslide in Italy, available to proponents, available in technical literature and from "open" sources - in favor of the cost-effectiveness of the proposal. The integration exploits a coherent set of modeling tools, expert (heuristic) and numerical (statistical and probabilistic, physically-based, FEM, optimization models). The methodology considers the problem at multiple scales, including: (a) three geographic scales - the national synoptic scale, the regional mesoscale and the local scale; (b) two time scales - the pre-event scale typical of territorial planning and the deferred time of civil protection, and the post-event scale, characteristic of real civil protection time; and (c) different organizational and management scales - from spatial planning and soil defense, including post-seismic reconstruction, to civil protection rapid response. Furthermore, the methodology considers the characteristics of the seismic-induced landslide and the associated hazard in the main geological, geomorphological and seismic-tectonic contexts in Italy.

The project develops methodologies and products for different users and/or users. The former concern methodologies for (i) the synoptic zoning of the hazard caused by earthquake-induced landslides in Italy; (ii) the zoning and quantification of the danger from earthquake-induced landslides on a regional scale; (iii) the quantification of the danger of single deep landslides in the seismic phase; and for (iv) the identification and geological-technical modeling of deep co-seismic landslides starting from advanced DInSAR analyzes from post-seismic satellites.

How to cite: Tizzani, P., Reichenbach, P., Fiorucci, F., Alvioli, M., Moscatelli, M., and Bonfante, A. and the Fra.Si. Team: FRA.SI.project - AN INTEGRATED MULTI-SCALE METHODOLOGIES FOR THE ZONATION OF LANDSLIDE-INDUCED HAZARD IN ITALY, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12927, https://doi.org/10.5194/egusphere-egu22-12927, 2022.

Wet deposition has been identified as a critical impactor for the modelling of 137Cs in the Fukushima Daiichi Nuclear power plant (FDNPP) accident. However, it is difficult to simulate due to the involvement of close interaction between various complicated meteorological and physical processes during the wet deposition process. The limitation of measurement of the in-cloud and below-cloud scavenging also contribute to the uncertainty in wet deposition modeling, leading to the great variation of 137Cs wet deposition parameterization. These variations can be amplified further by inaccurate meteorological input, making simulation of radionuclide transport sensitive to the choice of wet scavenging parameterization. Moreover, simulations can also be influenced by differences between radionuclide transport models, even if they adopt similar parameterization for wet scavenging. Although intensively investigated, wet deposition simulation is still subject to uncertainties of meteorological inputs and wet scavenging modeling, leading to biased 137Cs transport prediction.

To improve modeling of 137Cs transport, both in- and below-cloud wet scavenging schemes were integrated into the Weather Research and Forecasting-Chemistry (WRF-Chem) model, yielding online coupled modeling of meteorology and the two wet scavenging processes. Overall, 25 combinations of different in- and below-cloud scavenging schemes of 137Cs, covering most wet scavenging schemes reported in the literature, were integrated into WRF-Chem. Additionally, two microphysics schemes were compared to improve the simulation of precipitation. These 25 models and the ensemble mean of 9 representative models were systematically compared with a previous below-cloud-only WRF-Chem model, using the cumulative deposition and atmospheric concentrations of 137Cs measurements. The findings could elucidate the range of variation among these schemes both within and across the five in-cloud groups, reveal the behaviors and sensitivities of different schemes in different scenarios.

The results revealed that the Morrison's double moment cloud microphysics scheme improves the simulation of rainfall and deposition pattern. Furthermore, the integration of the in-cloud schemes in WRF-Chem substantially reduces the bias in the cumulative deposition simulation, especially in the Nakadori and Tochigi regions where light rain dominated. For atmospheric concentration of 137Cs, those models with in-cloud schemes that consider cloud parameters showed better and more stable performance, among which Hertel-Bakla performed best for atmospheric concentration and Roselle-Apsimon performed best for both deposition and atmospheric concentration. In contrast, the in-cloud schemes that rely solely on rain intensity were found sensitive to the meteorological conditions and showed varied performance in relation to the plume events examined. The analysis based on the spatial pattern shows that the Roselle scheme, which considers cloud liquid water content and depth, can achieve a more balanced allocation of 137Cs between the air and the ground in these two cases than that achieved by the empirical power function scheme Environ. The ensemble mean achieves satisfactory performance except for one plume event, but still outperforms most models. The range of variation of the 25 models covered most of the measurements, reflecting the reasonable capability of WRF-Chem for modeling 137Cs transport.

How to cite: Zhuang, S., Dong, X., and Fang, S.: Sensitivity analysis on the wet deposition parameterization for 137Cs transport modeling following the Fukushima Daiichi Nuclear Power Plant accident, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-177, https://doi.org/10.5194/egusphere-egu22-177, 2022.

The nuclear emergency response for accidental release around the nuclear power plant site (NPPs) requires a fast and accurate estimate of the influence caused by gaseous hazardous pollutants spreading, which is critical for and preventing protecting lives, creatures, and the environment. However, as usual, the NPPs is consist of dense buildings and multi-type terrain, e.g. river and mountain, which poses challenges to atmospheric dispersion calculation for response tasks. Micro-SWIFT SPRAY (MSS) comprises both the diagnostic wind model and the dispersion model, which enables the airflows and atmospheric dispersion simulation with the meteorological and other inputs. For a small-scale scenario, especially, the separate module for obstacles influence modeling provides the potential capability of precise atmospheric dispersion. But the error behavior of such a scenario around a nuclear power plant site with complex topography remains to be further demonstrated. In this study, MSS is comprehensively evaluated against a wind tunnel experiment with a 1:600 scale for the small-scale (3 km × 3km) atmospheric dispersion modeling. Tens of buildings located in this scenario of a NPPs surrounded by a mountain and river. The evaluations for diagnostic wind modeling include the speed, direction, and distribution of horizontal airflows and vertical profile of speed at a representative site. And for the concentration calculation, horizontal distribution, axis profile, and vertical profile at a representative site. The results demonstrate the MSS can reproduce fine airflows near the buildings but overestimate the wind speed. The maximum deviation of vertical speed is around 2.09 m/s at the representative site. The simulated plume of concentration reproduces the highest concentration place and matches the observations well. The axis profile of concentration is underestimated and the vertical profile displays an increasing deviation with the height increase. Compared with the observations, the FAC5 and FAC2 of concentration simulation reach 0.945 and 0.891 in the entire calculation domain, which convinces the performance of MSS in small-scale modeling.

How to cite: Dong, X., Zhuang, S., and Fang, S.: Micro-SWIFT SPRAY modeling of atmospheric dispersion around a nuclear power plant site with complex topography, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-190, https://doi.org/10.5194/egusphere-egu22-190, 2022.

EGU22-666 | Presentations | GI2.3

Dry deposition velocity of chlorine 36 on grassland 

Sourabie Deo, Didier Hebert, Lucilla Benedetti, Elsa Vitorge, Beatriz Lourino Cabana, Valery Guillou, and Denis Maro

Chlorine 36 (36Cl, T1/2 = 301,000 years) is a radionuclide with natural and anthropogenic origin that can be rejected accidentally during decommissioning of nuclear power plants or chronically during recycling of nuclear waste. Once emitted into the atmosphere, 36Cl (gas and particles) can be transferred to the soil and vegetal cover by dry and wet deposition. However, knowledge of these deposits is very scarce. Because of its relatively high mobility in the geosphere and its high bioavailability, 36Cl fate in the environment should be studied for environmental and human impact assessments. So, the objective of this work is to determine the dry deposition rates of chlorine 36 on grassland. Grass is studied, as it is a link in the human food chain via cow's milk.

In order to achieve this objective, a method for extracting the chlorine contained in plant leaves has been developed. This method consists in heating the dried and grounded plant sample in presence of sodium hydroxide. A temperature gradient up to 450°C allows the extraction to be carried out in two stages: (i) The chlorides with a strong affinity for alkaline environments are first extracted from the plant and preserved in sodium hydroxide; (ii) The organic matter is then destroyed by combustion and the sodium hydroxide crystallised. Brought out from the oven, the dry residue is dissolved in ultrapure water and chemically prepared for the measurement of chlorine 36. This extraction method was validated by its application to NIST standards of peach and apple leaves. The average extraction efficiency of chlorides was 83 ± 3%.

For the determination of dry deposition rates, 1m2 of grass was exposed every 2 weeks at the IRSN La Hague technical platform (PTILH) located 2 km downwind from Orano la Hague, a chronic source of low-level chlorine 36 emissions. A mobile shelter with automatic humidity detection covered the grass during rainy episodes. In proximity to the grass, atmospheric chlorine was also sampled at the same frequency as the grass. Gaseous chlorine was sampled by bubbling in sodium hydroxide and by an AS3000 sampler containing activated carbon cartridge. Particulate chlorine was collected on a composite (teflon and glass fibre) filter. Chlorine 36 was measured by accelerated mass spectrometry ASTER (Accelerator for Earth Sciences, Environment and Risks) at CEREGE, Aix-en-Provence, France. All samples were subjected to a succession of chemical preparations in order to remove the sulphur 36 (an isobaric interferent) and to collect the chlorides in the form of AgCl pastilles. The results show a chlorine 36 deposition flux on the grass of 2.94.102 at/m2.s with a deposition velocity in dry weather vd(gas+particles) = 8.10-4 m/s for a contribution of 65.5% of particulate chlorine 36 and 34.5% of gaseous chlorine 36. Based on these experimental results, a modelling of the dry and wet deposits will be carried out considering the parameters related to the canopy and the atmospheric turbulence.

How to cite: Deo, S., Hebert, D., Benedetti, L., Vitorge, E., Lourino Cabana, B., Guillou, V., and Maro, D.: Dry deposition velocity of chlorine 36 on grassland, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-666, https://doi.org/10.5194/egusphere-egu22-666, 2022.

EGU22-1235 | Presentations | GI2.3

Modeling the depth dependence of Cs-137 concentration in Lake Onuma 

Yuko Hatano, Kentaro Akasaki, Eiichi Suetomi, Yukiko Okada, Kyuma Suzuki, and Shun Watanabe

Lake Onuma on Mt. Akagi (Gunma Prefecture, Japan) is a closed lake with an average water residence time of 2.3 years. The activity concentration of radioactive cesium in the lake was high shortly after the Fukushima accident. According to Suzuki et al. [1] and Watanabe [2], after a filtration process, Cs-137 are separated into two groups: particulate form and dissolved form. These two forms appears to have very different concentration profiles with each other,  when the Cs-137 concentration plotted against the sampled water depths. In the present study, we are going to model those behavior of particulate/dissolved forms with an emphasis on the depth dependency.

We consider a creation-annihilation process of plankton for the model of the particulate form, since diatom shells are found to be a major constituent of the particulate Cs-137 [2]. We set  ∂P/∂t = f(x,t)  and  f(x,t) = χ(x) cos(ωt) (0 ≤ x ≤ L(water column height), t > 0),  where P=P(x,t) is the activity concentration of the particulate form. The term f(x,t) is the rate of the net production of the plankton at a specific location x at a specific time t. Seasonal cycle is also taken into account by the cosine function (we neglect the phase shift here). The function χ(x), depends solely on water depth x, is responsible for dynamics or inhomogeneity of lake water, such as circulation, stratification or a thermocline. We assume that such a water structure relates to the production rate of plankton through the function χ(x). Thus, we may obtain the concentration of particulate Cs-137. For the dissolved concentration S(x,t), we use the classical diffusion equation with the diffusivity K being dependent on both space and time (i.e. K(x,t)), namely ∂S/∂t =  ∇•(K(x,t) ∇S). Here S=S(x,t) is the activity concentration of the dissolved form. The total activity concentration C(x,t) is the sum of P(x,t) and S(x,t). Using the pair of the equations, we can reproduce the followings. (1) depth profiles of each of the soluble- and particulate activity concentration and (2) depth profiles of the total Cs-137 concentration.

 [1] Suzuki, K. et al., Sci. Tot. Env. (2018)

 [2] Watanabe, S. et al.,  Proc. 20th Workshop on Environmental Radioactivity (2019)

How to cite: Hatano, Y., Akasaki, K., Suetomi, E., Okada, Y., Suzuki, K., and Watanabe, S.: Modeling the depth dependence of Cs-137 concentration in Lake Onuma, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1235, https://doi.org/10.5194/egusphere-egu22-1235, 2022.

EGU22-3340 | Presentations | GI2.3

Factors controlling the dissolved 137Cs seasonal fluctuations in the Abukuma River under the influence of the Fukushima Nuclear Power Plant accident 

Yasunori Igarashi, Nanb Kenji, Toshihiro Wada, Yoshifumi Wakiyama, Yuichi Onda, and Shota Moritaka

The 2011 Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released large amounts of radioactive materials into the environment. River systems play an important role in the terrestrial redistribution of FDNPP-derived 137Cs in association with water and sediment movement. We examined the seasonal fluctuations in dissolved and particulate 137Cs activity concentrations and clarified the biological and physicochemical factors controlling 137Cs in the Abukuma River’s middle course in the region affected by the FDNPP accident. The results showed the water temperature and K+ concentration dominated the seasonality of the dissolved 137Cs activity concentration. We concluded that the 137Cs in organic matter is not a source of dissolved 137Cs in river water. The study also revealed the temperature dependence of Kd in riverine environments from a Van ’t Hoff equation. The standard reaction enthalpy of 137Cs in the Abukuma River was calculated to be approximately −19.3 kJ/mol. This was the first study to clearly reveal the mechanisms by which the dissolved 137Cs activity concentration and Kd are influenced by chemical and thermodynamic processes in the middle course of a large river, and it is expected to lead to an improved model of 137Cs dynamics in rivers.

How to cite: Igarashi, Y., Kenji, N., Wada, T., Wakiyama, Y., Onda, Y., and Moritaka, S.: Factors controlling the dissolved 137Cs seasonal fluctuations in the Abukuma River under the influence of the Fukushima Nuclear Power Plant accident, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3340, https://doi.org/10.5194/egusphere-egu22-3340, 2022.

EGU22-3442 | Presentations | GI2.3

A comparative study of riverine 137Cs dynamics during high-flow events at three contaminated river catchments in Fukushima 

Yoshifumi Wakiyama, Takuya Niida, Hyoe Takata, Keisuke Taniguchi, Honoka Kurosawa, Kazuki Fujita, and Alexei Konoplev

This study presents the temporal variations in riverine 137Cs concentrations and fluxes to the ocean during high-flow events in three coastal river catchments contaminated by the Fukushima Daiichi Nuclear Power Plant accident. River water samples were collected at points downstream in the Niida, Ukedo, and Takase Rivers during three high-flow events that occurred in 2019–2020. Variations in both the dissolved 137Cs concentration and 137Cs concentration in suspended solids appeared to reflect the spatial pattern of the 137Cs inventory in the catchments, rather than variations in physico-chemical properties. Negative relationships between the 137Cs concentration and δ15N in suspended sediment were found in all rivers during the intense rainfall events, suggesting an increased contribution of sediment from forested areas to the elevated 137Cs concentration. The 137Cs flux ranged from 0.33 to 18 GBq, depending on the rainfall erosivity. The particulate 137Cs fluxes from the Ukedo River were relatively low compared with the other two rivers and were attributed to the effect of the Ogaki Dam reservoir upstream. The ratio of 137Cs desorbed in seawater to 137Cs in suspended solids ranged from 2.8% to 6.6% and tended to be higher with a higher fraction of exchangeable 137Cs. The estimated potential release of 137Cs from suspended solids to the ocean was 0.048–0.57 GBq, or 0.8–6.2 times higher than the direct flux of dissolved 137Cs from the river. Episodic sampling during high-flow events demonstrated that the particulate 137Cs flux depends on catchment characteristics and controls 137Cs transfer to the ocean. 

How to cite: Wakiyama, Y., Niida, T., Takata, H., Taniguchi, K., Kurosawa, H., Fujita, K., and Konoplev, A.: A comparative study of riverine 137Cs dynamics during high-flow events at three contaminated river catchments in Fukushima, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3442, https://doi.org/10.5194/egusphere-egu22-3442, 2022.

EGU22-5397 | Presentations | GI2.3

Integrating measurement representativeness and release temporal variability to improve the Fukushima-Daiichi 137Cs source reconstruction 

Joffrey Dumont Le Brazidec, Marc Bocquet, Olivier Saunier, and Yelva Roustan

    The Fukushima-Daiichi accident involved massive and complex releases of radionuclides in the atmosphere. The releases assessment is a key issue and can be achieved by advanced inverse modelling techniques combined with a relevant dataset of measurements. A Bayesian inversion is particularly suitable to deal with this case. Indeed, it allows for rigorous statistical modelling and enables easy incorporation of informations of different natures into the reconstruction of the source and the associated uncertainties.
    We propose several methods to better quantify the Fukushima-Daiichi 137Cs source and the associated uncertainties. Firstly, we implement the Reversible-Jump MCMC algorithm, a sampling technique able to reconstruct the distributions of the 137Cs source magnitude together with its temporal discretisation. Secondly, we develop methods to (i) mix both air concentration and deposition measurements, and to (ii) take into account the spatial and temporal information from the air concentration measurements in the error covariance matrix determination.
    Using these methods, we obtain distributions of hourly 137Cs release rates from 11 to 24 March and assess the performance of our techniques by carrying out a model-to-data comparison. Furthermore, we demonstrate that this comparison is very sensitive to the statistical modelling of the inverse problem.

How to cite: Dumont Le Brazidec, J., Bocquet, M., Saunier, O., and Roustan, Y.: Integrating measurement representativeness and release temporal variability to improve the Fukushima-Daiichi 137Cs source reconstruction, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5397, https://doi.org/10.5194/egusphere-egu22-5397, 2022.

EGU22-6698 | Presentations | GI2.3

Vertical distribution of 137Cs in bottom sediments as representing the time changes of water contamination: Chernobyl and Fukushima 

Aleksei Konoplev, Yoshifumi Wakiyama, Toshihiro Wada, Yasunori Igarashi, Gennady Laptev, Valentin Golosov, Maxim Ivanov, Mikhail Komissarov, and Kenji Nanba

Bottom sediments of lakes and dam reservoirs can provide an insight into understanding the dynamics of 137Cs strongly bound to sediment particles. On this premise, a number of cores of bottom sediments were collected in deep parts of lakes Glubokoe, Azbuchin, and Cooling Pond in close vicinity of the Chernobyl NPP in Ukraine, in Schekino reservoir (Upa River) in the Tula region of Russia (2018) and in Ogaki reservoir (Ukedo River) in Fukushima contaminated area (2019). Each layer of bottom sediments can be attributed to a certain time of suspended particles sedimentation. With 137Cs activity concentration in a given layer of bottom sediments corresponding to 137Cs concentration on suspended matter at that point in time, we were able to reconstruct the post-accidental dynamics of particulate 137Cs activity concentrations. Using experimental values of the distribution coefficient Kd, changes in the dissolved 137Cs activity concentrations were estimated. The annual mean particulate and dissolved 137Cs wash-off ratios were also calculated for the period after the accidents. Interestingly, the particulate 137Cs wash-off ratios for the Ukedo River at Ogaki dam were found to be similar to those for the Pripyat River at Chernobyl in the same time period after the accident, while the dissolved 137Cs wash-off ratios in the Ukedo River were an order of magnitude lower than the corresponding values in the Pripyat River. The estimates of particulate and dissolved 137Cs concentrations in Chernobyl cases were in reasonable agreement with monitoring data and predictions using the semi-empirical diffusional model. However, both the particulate and dissolved 137Cs activity concentrations and wash-off ratios in the Ukedo River declined faster during the first eight years after the FDNPP accident than predicted by the diffusional model, most likely, due to greater natural attenuation and, to some extent, remediation measures implemented on the catchments in Fukushima.

This research was supported by Science and Technology Research Partnership for Sustainable Development (SATREPS), Japan Science and Technology Agency (JST)/Japan International Cooperation Agency (JICA) (JPMJSA1603), by bilateral project No. 18-55-50002 of Russian Foundation for Basic Research (RFBR) and Japan Society for the Promotion of Science (JSPS), and JSPS Project KAKENHI (B) 18H03389.

How to cite: Konoplev, A., Wakiyama, Y., Wada, T., Igarashi, Y., Laptev, G., Golosov, V., Ivanov, M., Komissarov, M., and Nanba, K.: Vertical distribution of 137Cs in bottom sediments as representing the time changes of water contamination: Chernobyl and Fukushima, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6698, https://doi.org/10.5194/egusphere-egu22-6698, 2022.

EGU22-7068 | Presentations | GI2.3

Seasonal variation of dissolved Cs-137 concentrations in headwater catchments in Yamakiya district, Fukushima Prefecture 

Taichi Kawano, Yuichi Onda, Junko Takahishi, Fumiaki Makino, and Sho Iwagami

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident occurred on March 11, 2011, and a large amount of Cs-137 was released into the environment. It is important to clarify the behavior of radioactive cesium-137 in headwater catchments because most of the Cs-137 falls and is deposited in forest areas and is transported in the environment through river systems.

The purpose of this study was to clarify the influence of water quality composition and organic matter on the seasonal variation of dissolved Cs-137 concentrations in stream water based on long-term monitoring since 2011 at four headwaters catchments in Yamakiya district, Fukushima Prefecture (Iboishiyama, Ishidairayama, Koutaishiyama, Setohachiyama), located about 35 km northwest of FDNPP.

Water temperature, pH, and EC were measured in the field, and SS and coarse organic matter were collected using a time-integrated SS (suspended sediments) sampler and organic matter net. The Cs-137 concentrations was measured in the laboratory using a germanium detector. Concentrations of cations (Na⁺,K⁺,Ca²⁺,Mg²⁺,NH₄⁺) and anions (Cl⁻,SO₄²⁻,NO₃⁻,NO₂⁻,PO₄²⁻) were measured by ion chromatography after 0.45μm filtration. In addition, dissolved organic carbon (DOC) concentrations was measured using a total organic carbon analyzer.

The results showed that K⁺, which is highly competitive with Cs-137, was detected at Iboisiyama, Ishidairayama, and Koutaishiyama, while NH₄⁺ was only detected in some samples at Iboishiyama. There was no obvious relationship between dissolved ion concentration and water temperature, and between dissolved ion concentration and dissolved ¹³⁷Cs concentration at all sites. However, a positive correlation between dissolved cesium concentration and water temperature and DOC and water temperature was observed at all sites regardless of the presence of K⁺ and NH₄⁺. On the other hand, there was no clear relationship between the cesium concentrations in SS and organic matter and water temperature. These results suggest that the seasonal variation in dissolved Cs-137 concentrations in stream water with water temperature could be caused by the seasonality of microbial decomposition of organic matter.

How to cite: Kawano, T., Onda, Y., Takahishi, J., Makino, F., and Iwagami, S.: Seasonal variation of dissolved Cs-137 concentrations in headwater catchments in Yamakiya district, Fukushima Prefecture, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7068, https://doi.org/10.5194/egusphere-egu22-7068, 2022.

A study of 137Cs distribution in a landscape cross-section characterizing the ELGS system (top-slope-closing depression) in the “Vyshkov-2” test site located in the Chernobyl abandoned zone, the Bryansk region, Russia, has been performed in 2015 and 2021. The test site (70×100 m) is located on the Iput’ river terrace in a pine forest characterized by the undisturbed soil-plant cover. Sod-podzolic sandy illuvial-ferruginous soils present the soil cover. The initial level of 137Cs contamination of the area varied from 1480 kBq/m2 to 1850 kBq/m2. Up to now, 89-99 % of the total 137Cs is fixed in the upper 20 cm soil layer with 70-96 % in the upper 8 cm. It allows field spectrometry data to study the structure of the 137Cs contamination field. The 137Cs activity was measured in the soil and moss cover along cross-sections with 1 m step by adapted gamma-spectrometer Violinist-III (USA). Cs-137 content in the soil cores’ and plant samples was determined in the laboratory by Canberra gamma-spectrometer with HPGe detector. It was shown that there is no unidirectional movement of 137Cs both in the soil and in the vegetation cover of the ELGS from the top to the closing depression. On the contrary, the data obtained allow us to state a pronounced cyclical variation of the 137Cs activity in ELGS, which can be traced in the soil and the vegetation. The variation appeared to be rather stable in space 29 and 35 years after the primary pollution. Cyclic fluctuation (variation) of 137Cs activity was described mathematically using Fourier-analysis, which was used to model the observed changes by the revealed three main harmonics. High and significant correlation coefficients obtained between the variation of 137Cs activity and the model for the soil-vegetation cover (r0,01= 0,868; n=17 - 2015; r0,01= 0,675; n=17 - 2021), soils (r0,01= 0,503-0,859; n=17) and moss samples (r0,01= 0,883; n=17 - 2015; r0,01= 0,678; n=17 - 2021) proved satisfactory fitting of models. The character of 137Cs variability in moss cover was generally similar to surface soil contamination, but the level of contamination and amplitude was specific.

The performed study confirmed specific features of 137Cs secondary migration in ELGS, which periodic functions describe. We infer that the observed cyclicity reflects elements’ migration in the ELGS system with water.

The reported study was funded by the Vernadsky Institute federal budget (research task #0137-2019-0006). The field works were supported partly by RFBR No 19-05-00816.

How to cite: Dolgushin, D. and Korobova, E.: Regularities of the 137Cs secondary distribution in the soil-moss cover of elementary landscape-geochemical systems and its dynamics within 6 years on the test site in the Chernobyl abandoned zone, Russia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8178, https://doi.org/10.5194/egusphere-egu22-8178, 2022.

EGU22-9022 | Presentations | GI2.3

Ten-year long-range transport of radiocaesium in the surface layer in the Pacific Ocean and its marginal seas 

Michio Aoyama, Yuichiro Kumamoto, and Yayoi Inomata

Radiocaesium derived from the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) accident was observed across a wide area of the North Pacific, not only in surface seawater, but also in the ocean interior. In this presentation, we summarized the time scale of Lagrangian transport of the FNPP1 derived radiocaesium in surface water during the period from the time of the accident to March 2021 in the North Pacific and the Arctic Oceans and its marginal seas as shown below.

Initial observation results until December 2012 in the surface layer in the North Pacific Ocean by the global observations revealed that a typical feature within one year after the accident was a westward movement across the North Pacific Ocean, speed of which was reported at 7 km day-1 until August 2011. After that, the main body of FNPP1-derived radiocaesium moved east as 3 km day-1 and is separated from Japan in 2013. The arrival of the FNPP1 signal at the west coast of the American continent was reported in 2014. The elevation in the FNPP1 derived radiocaesium concentration in the Bering Sea in 2017 and in the Arctic Ocean in 2019 was reported. The northward bifurcation of the Kuroshio Extension made these obvious transport of the FNPP1 derived radiocaesium to the subarctic and arctic region while the transport by southward bifurcation was not observed. At Hawaii Islands in the subtropical gyre, there was no signal of the FNPP1 derived radiocaesium during the period from March 2011 and February 2017. At Yonaguni Island where the Kuroshio enters the East China Sea, the FNPP1 signal arrived at Yonaguni Islands eight years after the time of the accident, and these might be transported mainly from the subtropical gyre.

At the marginal seas of the North Pacific Ocean, the elevation in the FNPP1 derived radiocaesium concentration in the northern East China Sea in 2014, in the Sea of Japan in 2014/2015 were observed.

We also briefly summarize study results on nuclides other than radiocaesium (e.g., 90Sr, 239240Pu, and 129I).

How to cite: Aoyama, M., Kumamoto, Y., and Inomata, Y.: Ten-year long-range transport of radiocaesium in the surface layer in the Pacific Ocean and its marginal seas, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9022, https://doi.org/10.5194/egusphere-egu22-9022, 2022.

Radiocesium (137Cs) was one of the radioactive materials released from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011. Highly 137Cs contaminated water from groundwater to the sea was reduced after installation of the sea-side impermeable wall as a countermeasure against contaminated water in October 2015. As a result, 137Cs contamination in water from other sources became more prominent and the levels of 137Cs concentration in seawater was correlated with rainfall fluctuation. To determine the source of contamination, we estimated the fluctuation patterns of 137Cs concentration in seawater, groundwater level, and discharge from the channels using the Antecedent Precipitation Index (Rw) method.
The results indicated that the fluctuation in seawater collected near the 1-4 Units had strong agreement with the 3 day half-life of Rw. The half-life is shorter than that estimated by groundwater level (7 to 30 day). Therefore, the 137Cs concentration in seawater was influenced by relatively faster runoff than the deep groundwater flow. We also made the spatial distribution map of 137Cs concentration in seawater to determine the sources of contamination. It showed that the 137Cs contaminated area was the highest at “south- inside the intake of 1-4 Units” where the outlets of the K and BC discharge channels are located. In particular, the concentration of 137Cs in the channel K was found to correlate with the concentration of 137Cs in seawater near the 1-4 Units (average of R2 = 0.5). These results indicate that the concentration of 137Cs in seawater inside the FDNPP port can be estimated by the Rw method and that the source of the contamination could be determined using the half-life.

How to cite: Sato, H. and Onda, Y.: Determining sources of the 137Cs concentration in seawater at Fukushima Daiichi Nuclear Power Plant using Antecedent Precipitation Index, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9055, https://doi.org/10.5194/egusphere-egu22-9055, 2022.

European seas such as, Baltic, North, and Norwegian Seas are mostly affected areas by the accident at the Chernobyl nuclear power plant (CNPP) in 1986. Since Fukushima Daiichi nuclear power plant (FDNPP) is located on the coast of the North Pacific Ocean in east Japan, its accident resulted in the release of large amounts of radiocesium to the surrounding coastal marine environment (i.e. the waters off Fukushima and neighboring prefectures). The temporal change of radiocaesium concentration in seawater after both accidents was largely dependent on their submarine topography: The Baltic Sea is a semi-closed basin, while Norwegian and North Seas, and the waters off Fukushima and neighboring prefectures is directly connected to open-water. Although concentration of radioacesium (137Cs) in the surface water of the Baltic Sea (central part) continuously decreased, the values in 1996, ten years after the accident, were even higher than pre-accident level in 1985. On the other hand, in the waters off Fukushima and neighboring prefectures 137Cs concentrations in 2020, nine years after the accident, are approaching the pre-accident levels of 2010. The quick decrease is attributable to the intrusion or mixing of water masses with low 137Cs.

How to cite: Takata, H.: Temporal trends of radio-cesium concentration in the marine environment after the Chernobyl and Fukushima Dai-ichi Nuclear Power Plant accidents, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10644, https://doi.org/10.5194/egusphere-egu22-10644, 2022.

EGU22-10713 | Presentations | GI2.3 | Highlight

Decontamination and subsequent natural restoration processes impact on terrestrial systems in Niida River Catchment in Fukushima 

Yuichi Onda, Feng Bin, Yoshifumi Wakiyama, Keisuke Taniguchi, Asahi Hashimoto, and Yupan Zhang

For the Fukushima region in Japan, the large-scale decontamination in the catchments needed to require more attention because of their possible consequence in altering particulate Cs-137 flux from the terrestrial environment to the ocean. Here, combining the high-resolution satellite dataset and concurrent river monitoring results, we quantitively assess the impacts of land cover changes in large-area decontaminated regions on river suspended sediment (SS) and particulate Cs-137 dynamics during 2013-2018. We find that the decontaminated regions’ erodibility dramatically enhanced during the decontamination stage but rapidly declined in the subsequent natural-restoration stage. River SS dynamics show linear response to these land cover changes, where annual SS load (normalized by water discharge) at the end of decontamination increased by over 300% than pre-decontamination and decreased about 48% at the beginning of natural restoration. Fluctuations in particulate Cs-137 concentrations well reflect the process of sediment source alternation due to land cover changes in decontaminated regions. The “Fukushima decontamination experiment” can reveal the dramatic impact of decontamination-natural restoration processes, which highlights the need for quantitatively assessing human impacts on land use and resultant alternation in sediment transfer patterns in large scale catchments. 

How to cite: Onda, Y., Bin, F., Wakiyama, Y., Taniguchi, K., Hashimoto, A., and Zhang, Y.: Decontamination and subsequent natural restoration processes impact on terrestrial systems in Niida River Catchment in Fukushima, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10713, https://doi.org/10.5194/egusphere-egu22-10713, 2022.

EGU22-10817 | Presentations | GI2.3

Effects of stemflow on radiocesium infiltration into the forest soil 

Hiroaki Kato, Hikaru Iida, Tomoki Shinozuka, Yuma Niwano, and Yuichi Onda

Radiocesium deposited in the forest canopy is transferred to the forest floor by rainwater and litterfall. Among them, stemflow likely increases the radiocesium inventory by concentrating rainwater around the trunk. However, the effects of stemflow on the influx of radiocesium into forest soil have not been evaluated quantitatively. In this study, the fluxes of rainwater via stemflow, throughfall, and soil infiltration water were observed. The concentration of dissolved 137Cs was measured in a cedar forest in Fukushima Prefecture, Japan. Soil infiltration water was collected at 5 cm and 20 cm depths at the distant point from the tree trunk (Bt), and the base of the tree trunk (Rd), where the influence of stemflow was strong. The observations were conducted during the period from September 2019 to November 2021. During the observation period, an experiment was conducted to intercept the inflow of rainwater via the throughfall or stemflow, and the change in soil infiltration water was observed. The observation results showed that the infiltration flux of radiocesium into the forest soil was significantly higher at the Rd site and about three times larger than at the Bt site. Particularly at the 20 cm depth at the Rd site, the soil infiltration water flux increased with the stemflow. The stemflow exclusion resulted in the dcrease of radiocesium flux by about 70% at all depths at the Rd site. These results suggest that the stemflow increases the input of radiocesium to the base of the tree trunk and facilitates its transfer to the deeper soil layers.

How to cite: Kato, H., Iida, H., Shinozuka, T., Niwano, Y., and Onda, Y.: Effects of stemflow on radiocesium infiltration into the forest soil, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10817, https://doi.org/10.5194/egusphere-egu22-10817, 2022.

EGU22-11022 | Presentations | GI2.3

Estimation of 137Cs inventories in each ocean basin by a global ocean general circulation model for the global database interpolation 

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 by atmospheric nuclear weapons tests, releases from reprocessing plants in Europe, and supplied to the ocean by the Fukushima Daiichi Nuclear Power Plant (1F NPP) 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, observed data have been summarized in a historical database (MARIS) by IAEA. The spatio-temporal density of the observations varies widely, therefore simulation by an ocean general circulation model (OGCM) can be helpful in the interpretation of these observations.

In order to clarify the behavior of 137Cs in the global ocean, OGSM simulations were conducted. Parallel Ocean Program version 2 (POP2) of the Community Earth System Model version 2 (CESM2) is employed. The horizontal resolution is 1.125 degree of longitude, and from 0.28 degree to 0.54 degree of latitude. There are 60 vertical levels with a minimum spacing of 10 m near the ocean surface, and increased spacing with depth to a maximum of 250 m. The simulated period was from 1945 to 2030 with the circulation forced by repeating (“Normal Year”) atmospheric conditions. As input sources of 137Cs to the model, global fallout from atmospheric nuclear tests, releases from reprocessing plants in Europe, and input from the 1F NPP accident were considered. It was assumed that the input conditions in 2020 would continue after 2020.

The simulated 137Cs activity agrees well with the observed data in the database, especially in the Atlantic and Pacific Oceans where the observation density is large. Since 137Cs undergoes radioactive decay with a half-life of 30 years, the inventory for each basin is the difference between the decay corrected cumulative input and flux. In the North Pacific, the inventory reached its maximum in 1966 due to the global fallout by atmospheric nuclear weapons tests. Fluxes from the North Pacific to the Indian Ocean, Arctic Ocean, and Central Pacific were positive, and the North Pacific was a source of supply for other ocean basins. The 1F NPP accident caused a 20% increase in the inventory in 2011. In the North Atlantic, the inventory reaches its maximum in the late 1970s, due to the releases from the reprocessing plant. The outflow flux from the North Atlantic to the Greenland Sea is larger than the other fluxes and is a source of supply to other ocean basins. After 2000, the inflow flux to the North Pacific from the Labrador Sea and the South Atlantic is larger than the outflow flux.

The time series of 137Cs inventory in each ocean basin and the fluxes among ocean basins were quantitatively analyzed by OGCM simulations, and the predictions for the next 10 years were made.  The 137Cs activity concentrations by global fallout can be detected in the global ocean after 2030. The OGCM simulations will be useful in 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.: Estimation of 137Cs inventories in each ocean basin by a global ocean general circulation model for the global database interpolation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11022, https://doi.org/10.5194/egusphere-egu22-11022, 2022.

EGU22-11502 | Presentations | GI2.3

Retrospective assessment of 14C aquatic and atmospheric releases from Ignalina Nuclear Power Plant due to exploitation of two RBMK-1500 type reactors 

Evaldas Maceika, Rūta Barisevičiūtė, Laurynas Juodis, Algirdas Pabedinskas, Žilvinas Ežerinskis, Justina Šapolaitė, Laurynas Butkus, and Vidmantas Remeikis

Considerable amounts of 14C in the nuclear reactor are generated by neutrons. It accumulates in reactor components, coolant, and cleaning systems, and partly is released into the environment as gaseous releases and as liquid effluents. Two RBMK-1500 type reactors were exploited at Ignalina NPP (Lithuania) 1983-2009. Releases from NPP radiocarbon accumulated in local biosphere by photosynthesis, including terrestrial and aquatic media, as INPP used Lake Drūkšiai as a cooling pond

Temporal variation of 14C in lake ecosystem was examined by analyzing measured radiocarbon concentration of the organic compounds (Alkali soluble-AS) and alkali insoluble-AIS) derived from the layers of the Drūkšiai lake bottom sediments. The lake sediment cores were sampled in 2013 and 2019, sliced to 1 cm layers and 14C concentration was measured of every layer. AS and AIS organic fractions of sediment samples were extracted by using the acid-base-acid method.

Tree ring cores were collected from Pinus Sylvestris pines around the Ignalina NPP site at different directions and distances. Cellulose extraction was performed with BABAB (base-acid-base-acid-bleach) procedure, and all samples were graphitized and measured by a single state accelerator mass spectrometry at Vilnius Radiocarbon facility. Tree rings 14C concentration analysis provides atmospheric radiocarbon concentration in locations around the nuclear object. This analysis provides an opportunity to evaluate the impact of a nuclear object on water and terrestrial ecosystems.

The results showed a pronounced increase of 14C above background up to 17.8 pMC in the tree rings during INPP exploitation as well during decommission (since 2010) periods. According to the recorded data in 2004-2017 of the local Ignalina NPP meteorological station, the prevailing wind direction was towards the North and East during warm and light time periods. The radiocarbon released from the INPP stack dilutes when it travels in a downwind direction from the INPP. However, even 6.6 km away from the INPP, the impact of the power plant is still clearly visible. By using our created Gaussian dispersion model, the estimated annual emissions of 14C activity from the Ignalina NPP to the air vary from year to year. When only the 1st INPP reactor Unit was operating in 1985-1987, average emissions were 1.2 TBq/year. Emissions almost doubled to 2.1 TBq/year in 1988, when the 2nd Unit became operational. Later, emission levels increased. It could be explained by the large amount of 14C accumulating in the graphite of the RBMK reactor and its gradual release.

14C concentration profile analysis of the lake bottom sediments core revealed a significant impact of the Ignalina NPP on the Drūkšiai lake ecosystem. An increase of 14C concentration in the layers of bottom sediments by 80 pMC in the AS fraction and only by 9 pMC in the AIS fraction was observed, corresponding to the period about years of 1998-2003. The maximum peak in AS of 189 pMC was reached approximately in 2001, followed by gradual lake recovery. This radiocarbon peak in the lake represents a large single one-time pollution release. The critical period was in 2000s when maintenance works of the reactors were performed.

How to cite: Maceika, E., Barisevičiūtė, R., Juodis, L., Pabedinskas, A., Ežerinskis, Ž., Šapolaitė, J., Butkus, L., and Remeikis, V.: Retrospective assessment of 14C aquatic and atmospheric releases from Ignalina Nuclear Power Plant due to exploitation of two RBMK-1500 type reactors, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11502, https://doi.org/10.5194/egusphere-egu22-11502, 2022.

EGU22-11571 | Presentations | GI2.3

Mapping of Post-Disaster Environments using 3D Backprojection and Iterative Inversion Methods Optimised for Limited-Pixel Gamma Spectrometers on Unoccupied Aerial Systems (UAS). 

Dean Connor, David Megson-Smith, Kieran Wood, Robbie Mackenzie, Euan Connolly, Sam White, Freddie Russell-Pavier, Matthew Ryan-Tucker, Peter Martin, Yannick Verbelen, Thomas Richardson, Nick Smith, and Thomas Scott

All radiological measurements acquired from airborne detectors suffer from the issues of geometrical signal dilution, signal attenuation and a complex interaction of the effective sampling area of the detector system with the 3D structure of the surrounding environment. Understanding and accounting for these variables is essential in recovering accurate dose rate maps that can help protect responding workforces in radiologically contaminated environments.

Two types of terrain-cognisant methods of improving source localisation and the contrast of airborne radiation maps are presented in this work, comprising of ‘Point Cloud Constrained 3D Backprojection’ and ‘Point Cloud Constrained Randomised Kaczmarz Inversion’. Each algorithm uses a combination of airborne gamma-spectrometry and 3D scene information collected by UAS platforms and have been applied to data collected with lightweight, simple (non-imaging) detector payloads at numerous locations across the Chornobyl Exclusion Zone (CEZ).

Common to both the algorithms is the projection of the photopeak intensity onto a point cloud representation of the environment, taking into account the position and orientation of the UAS in addition to the 3D response of the spectrometer. The 3D Backprojection method can be considered a relatively fast method of mapping of through proximity, in which the measured photopeak intensity is split over the point cloud according to the above factors. It is an additive technique, with each measurement increasing the overall magnitude of the radiation field assigned to the survey area, meaning that more measurements continues to increase the total radiation of the site. The total measured intensity of the solution is then normalised according to the time spent in proximity to each point in the scene, determined by splitting and projecting the nominal measurement time at each survey point over the point cloud according to the distance from the survey position. Thus accounting for sampling biases during the survey.

The inversion approach adapts algorithms routinely used in medical imaging for the unconstrained world in which the detector is no longer completely surrounding the subject/target. A forward projection model, based on the contribution of distant point sources to the detector intensity, is used to determine the relationship between the full set of measurements and the 3D scene. This results in a hypercube of linear equations where it is assumed every point in the scene contributes to the measured intensity. The algorithm randomly adds measurements from within the aerial set and back-projects this onto the point cloud, with the initial state of the solution set to emit no radiation. After a given number of iterations, the fit of the current solution to the original measurements is assessed though a least squares method and updated when this produces a fit better than the current best estimate. This continues to happen until a minimum value is reached before the divergence of the system, representing the most confident solution. Based on examples from both simulations and real world data, the improvement in contrast of airborne maps using this inversion method can make them equivalent to ground-based surveys, even when operating at 20 m AGL and above.

How to cite: Connor, D., Megson-Smith, D., Wood, K., Mackenzie, R., Connolly, E., White, S., Russell-Pavier, F., Ryan-Tucker, M., Martin, P., Verbelen, Y., Richardson, T., Smith, N., and Scott, T.: Mapping of Post-Disaster Environments using 3D Backprojection and Iterative Inversion Methods Optimised for Limited-Pixel Gamma Spectrometers on Unoccupied Aerial Systems (UAS)., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11571, https://doi.org/10.5194/egusphere-egu22-11571, 2022.

EGU22-11620 | Presentations | GI2.3

Methodology for estimating the emission of radionuclides into the atmosphere from wildfires in the Chernobyl Exclusion Zone 

Valentyn Protsak, Gennady Laptev, Oleg Voitsekhovych, Taras Hinchuk, and Kyrylo Korychenskyi

Most of the territory of the Chernobyl Exclusion Zone (CEZ) is covered by forest. Forest of CEZ have accumulated a significant part of the radioactive release and for many years have served as a barrier to the non spreading of the radionuclide contamination outside the CEZ.

According to the classification of wildfire danger, the forests of CEZ belong to high, above average and medium classes, making cases of wildfires as quite common.

Poor, sod-podzolic soils of Ukrainian Polesye contribute to the entry the activity of 90Sr and 137Cs in plant biomass. During wildfires some of the radionuclides contained in combustion products of biomass are emitted into the atmosphere. Biologically important radionuclides such as 90Sr, 137Cs, plutonium isotopes and 241Am bound to fine aerosols - combustion products - can be transported with atmospheric flows over the long range, causing secondary radioactive fallout and forming additional inhalation dose loads on the population.

Lack of the actual information on the source term (rate of emission of radionuclides) does not allow reliable modeling of the radiological impact of wildfires. To address this issue, we have proposed a methodology that allows for operational assessments of the dynamics of radionuclide emissions into the atmosphere from wildfires in the CEZ.

The basic parameters for the calculations are

  • cartographic data on the density of radionuclide contamination of the territory of the CEZ;
  • classification of the territory of the CEZ according to the distributive features of forests and meadows;
  • classification of CEZ forests according to taxa characteristics to estimate amount of stored fuel biomass (kg/m2);
  • experimental data on the transfer of radionuclides from soil to the main components of biomass for the calculation of radionuclide inventory in fuel biomass (Bq/m2). Thus, for meadows the main fuel component is grass turf, while for forest these are litter, wood, bark and pine needles.
  • experimental data on emission factors of radionuclides from fuel biomass.

Implementation of the proposed algorithm in the form of GIS application makes it possible to assess the dynamics of radionuclide emission into the atmosphere by delineation the fire areas on the CEZ map. The NASA WorldView interactive mapping web application can be used to estimate the temporal and spatial characteristics of the wildfire while it is being developed. The contouring of the area affected by fire is carried out according to the analysis of the cluster of thermal points. Also, operational contouring of wildfire can be carried out using data delivered from unmanned aerial vehicles.

The application of the proposed algorithm for the analysis of the dynamics of 137Cs emissions into the atmosphere from the April 2020 wildfire showed a good agreement with the data reported by various authors who used the method of inverse simulation. Improving the accuracy of calculations according to the proposed algorithm can be done by rectifying radionuclide emission factors and taking into account fire intensity data, which in turn can affect both the radionuclide emission factor and the degree of burnout of plant biomass.

How to cite: Protsak, V., Laptev, G., Voitsekhovych, O., Hinchuk, T., and Korychenskyi, K.: Methodology for estimating the emission of radionuclides into the atmosphere from wildfires in the Chernobyl Exclusion Zone, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11620, https://doi.org/10.5194/egusphere-egu22-11620, 2022.

Human activities such as mining and processing of naturally occurring radioactive materials have a potential to result in enhanced radioactivity levels in the environment. In South Africa, there has been extensive mining of gold and uranium which produced large mine tailings dams that are highly concentrated with radioactive elements. The purpose of this study was to carry out a preliminary survey on a large scale to assess the activity concentrations of 238U, 232Th and 40K in mine tailings, soils and outcropping rocks in the West Rand District in South Africa. This was done to better understand the impact of the abandoned mine tailings on the surrounding soil. This study employed in-situ gamma spectrometry technique to measure the activity concentrations of 238U, 232Th and 40K. The portable BGO SUPER-SPEC (RS-230) spectrometer, with a 6.3 cubic inches Bismuth Germanate Oxide (BGO) detector was used for in-situ measurements. In mine tailings the activity concentrations for 238U, 232Th and 40K were found to range from 209.95 to 2578.68 Bq/kg, 19.49 to 108.00 Bq/kg and 31.30 to 626.00 Bq/kg, respectively. In surface soil, the activity concentration of 238U for all measurements ranged between 12.35 and 941.07 Bq/kg, with an average value of 59.15 Bq/kg. 232Th levels ranged between 12.59 and 78.36 Bq/kg, with an average of 34.91 Bq/kg. For 40K the average activity concentration was found to be 245.64 Bq/kg, in a range of 31.30 - 1345.90 Bq/kg. For the rock samples analyzed, average activity concentrations were 32.97 Bq/kg, 32.26 Bq/kg and 351.52 Bg/kg for 238U, 232Th and 40K, respectively. The results indicate that higher radioactivity levels are found in mine tailings than in rocks and soils. 238U was found to contribute significantly to the overall activity concentration in tailings dams as compared to 232Th and 40K. It has been observed that the mine tailings have a potential to impact on the activity concentration of 238U in soil in the immediate vicinity. However, on a regional scale it was found that the radioactivity levels in surface soil mainly depend on the radioelement concentration of the underlying rocks. The contamination is only confined to areas where mine tailings materials are washed off and deposited on surface soils in close proximity to tailings sources. This serves as an indication that the migration of uranium from tailings dams is localized and occurs within short distances. It is recommended that further radiological monitoring be conducted in areas found to have elevated concentration of uranium-238.

Keywords-In-situ gamma-ray spectrometry, Mine tailings, Radioactivity, Soil.

How to cite: Moshupya, P., Abiye, T., and Korir, I.: In-situ measurements of natural radioactivity levels in the gold mine tailings dams of the West Rand District, South Africa., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11669, https://doi.org/10.5194/egusphere-egu22-11669, 2022.

Due to the combined effect of human-driven depletion and anthropogenic climate change, groundwater storage is decreasing across the globe. This trend will potentially have an adverse impact on future human socio-economic development, by increasing the frequency and duration of both hydrological and socio-economic droughts as well as generating inter-sectoral competition for limited water resources.

Large-scale modelling studies on changes in groundwater availability can be separated into two big families. First, hydrological impact models actively consider water usage across sectors but ignore land-atmosphere interactions by design. Second, Earth System Models consider two-way interactions between climate and groundwater resources, but almost never consider the anthropogenic water resource depletion, except in some cases for irrigation.

The goal of this study is to connect the expertise of these two families by implementing domestic and industrial water usage in the Community Earth System Model version 2. Using land-atmosphere coupled simulations, we will revisit previously computed trends in future groundwater availability by simultaneously accounting for climate change and anthropogenic water resource usage.

How to cite: Taranu, I. S. and Thiery, W.: Implementing sectoral water usage in the Community Earth System Model for projecting future water resource availability, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-596, https://doi.org/10.5194/egusphere-egu22-596, 2022.

EGU22-898 | Presentations | HS7.3

Salinity-inclusive water scarcity: examples from food bowl regions of the US and Australia 

Josefin Thorslund, Marc F.P. Bierkens, Anna Scaini, Edwin H. Sutanudjaja, and Michelle T.H. van Vliet

Irrigated agriculture sustains more than 40% of global food production and uses up to 90 % of the world’s water resources. Water scarcity for the irrigation water use sector is a common problem, which may be driven by both water shortages and increased salinity levels. Limited studies however considered salinity issues in water scarcity assessment. We here developed a salinity-inclusive water scarcity framework for the irrigation sector, accounting for crop-specific irrigation water demands and salinity tolerance and its relation to water availability and salinity levels of both surface and groundwater resources. We assess temporal and spatial variation of water scarcity in agricultural river basins of the Central Valley (California) and the Murray Darling Basin (Australia), which are important food bowl regions. Our results show that including salinity and crop-specific salinity tolerances leads to very different water scarcity levels, compared to water scarcity approaches based on water quantity only, particularly at local scales. Further, our results from the Central Valley region highlights that severe water scarcity can be strongly alleviated by conjunctive groundwater use, to dilute and lower salinity levels below crop specific tolerance values in many sub-basins. However, groundwater resources needed for dilution frequently exceed renewable groundwater rates in this region, posing additional risks for groundwater depletion. Taken together, through capturing these dynamics, our water scarcity framework can support local-regional water management and provide a useful tool for sustainable water use and assessing the impact of agricultural practices, such as crop choices, on water scarcity levels.

How to cite: Thorslund, J., Bierkens, M. F. P., Scaini, A., Sutanudjaja, E. H., and van Vliet, M. T. H.: Salinity-inclusive water scarcity: examples from food bowl regions of the US and Australia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-898, https://doi.org/10.5194/egusphere-egu22-898, 2022.

Quantification of the Water Losses (WL) components in Water Distribution Networks (WDNs) is a vital task towards their reduction. However, current WL estimation methods rely on semi-empirical approaches with high uncertainty levels, which usually lead to inaccurate estimates of the lost volume. Here, we compare the probabilistic Minimum Night Flow (MNF) estimation method introduced by Serafeim et al. (2021) to the Water Balance components analysis, introduced by the International Water Association (IWA). The strong point of the Serafeim et al. (2021) approach is that it uses statistical metrics to filter out noise effects in the flow timeseries used for MNF estimation, leading to more accurate estimation of the low flows during night hours. The effectiveness of the applied methods is tested via a large-scale, real world application to the 4 largest Pressure Management Areas (PMAs) of the WDN of the city of Patras, the third largest city in Greece (see Serafeim at al., 2022). Although methodologically different, the two approaches lead to very similar results, substantiating the robustness of the Serafeim at al. (2021) approach which allows for reliable confidence interval estimation of the observed Minimum Night Flows, making it particularly suited for engineering applications.

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.; Kokosalakis, G.; Deidda, R.; Karathanasi, I.; Langousis, A. (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

How to cite: Langousis, A., Serafeim, A., Kokosalakis, G., Deidda, R., and Karathanasi, I.: Probabilistic water losses estimation in water distribution networks and comparison with the top down - water balance approach: A large-scale application to the city center of Patras in western Greece, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1974, https://doi.org/10.5194/egusphere-egu22-1974, 2022.

EGU22-2855 | Presentations | HS7.3

Parametric model for probabilistic estimation of water losses in water distribution networks: A large scale real world application to the city of Patras in western Greece 

Athanasios V. Serafeim, George Kokosalakis, Roberto Deidda, Irene Karathanasi, and Andreas Langousis

Abstract

Quantification of the leakage volume in pressure management areas (PMAs) is a vital task for water agencies’ financial viability. However, currently, there is no rigorous approach for their parametric modeling on the basis of networks’ specific characteristics and inlet/operating pressures. To bridge this gap, the current work focuses on the development of a probabilistic framework for minimum night flow (MNF) estimation in water distribution networks that: 1) parametrizes the MNF as a function of the network’s specific characteristics, and 2) parametrically describes water losses in individual PMAs as a function of the inlet/operating pressures. MNF estimates are obtained using the robust, non-parametric, probabilistic minimum night flow (MNF) estimation methodology developed and validated by Serafeim et al. (2021 and 2022), which allows for confidence interval estimation of the observed MNFs. The effectiveness of the developed model is tested in a large-scale real world application to the water distribution network of the city of Patras in western Greece, which serves approximately 200,000 consumers with more than 700 km of pipeline. The developed framework is validated through flow-pressure tests conducted by the Municipal Enterprise of Water Supply and Sewerage of the City of Patras to 78 PMAs of the network, indicating that the developed framework can be effectively used to improve water loss estimation and flow-pressure management in a morphologically and operationally diverse set of PMAs.

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.; Kokosalakis, G.; Deidda, R.; Karathanasi, I.; Langousis, A. (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

How to cite: Serafeim, A. V., Kokosalakis, G., Deidda, R., Karathanasi, I., and Langousis, A.: Parametric model for probabilistic estimation of water losses in water distribution networks: A large scale real world application to the city of Patras in western Greece, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2855, https://doi.org/10.5194/egusphere-egu22-2855, 2022.

EGU22-3301 | Presentations | HS7.3

Monitoring of agricultural drought from remote sensing products and in-situ meteorological data 

Mathis Neuhauser, Thomas Tilak, Christophe Point-Dumont, and Alexandre Peltier

The extreme events increasingly present in the Pacific (El Nino / La Nina phenomena) have significant consequences on island territories. The effect of climate change and drought episodes is therefore a central concern in many Pacific islands like Vanuatu, Wallis-and-Futuna, French Polynesia, etc. The intense drought events have undeniable impacts on biodiversity, agricultural crops and water resource, as was the case in 2019 for New Caledonia. In particular, projections in New Caledonia count on a possible increase in temperatures of 3°C and a water deficit of 20% in 2100 with longer and more intense drought episodes and an even greater west coast/east coast disparity (Dutheil, 2018). To date, the monitoring and anticipation of these drought episodes is done via meteorological measurements providing information on the rainfall deficit and not on the water stress of plants. In addition, the data are only available on a few measurement points and are not continuous over the territories.

In order to meet this need, a tool for monitoring environmental and agricultural drought using satellite images and meteorological data is being developed and validated in New Caledonia: Earth Observations for Drought Monitoring (EO4DM) project. This project is carried out in collaboration with Météo-France NC as a technical partner and the local Rural Agency as end user, and aims to provide a tool to help decision-making to institutions and management assistance for farmers. This solution will provide data constituting a singularly important source of information whose valuations and contributions can be multiple: agriculture, resource management (water), security (monitoring of risks linked to floods, fires), environment, etc.

To do so, various surface indices reflecting the state of the vegetation and certain soil properties such as humidity and temperature were estimated from different satellite sensors (MODIS, Sentinel-2, Landsat-8, ASCAT) in order to address different space scales from the field to regional scale. These indices were normalized over a relatively long period, allowing access to drought indicators: VHI (Vegetation Health Index; Kogan et al., 1997), VAI (Vegetation Anomaly Index; Amri et al., 2011), MAI (Moisture Anomaly Index; Amri et al., 2012) or TAI (Temperature Anomaly Index; Le Page and Zribi, 2019). Combined with in-situ meteorological products like SPI (Standardized Precipitation Index; McKee et al., 1993) and SPEI (Standardized Precipitation Evapotranspiration Index; Vicente-Serrano et al., 2010), these indicators assess the intensity of drought episodes and estimate their severity over the entire territory.

How to cite: Neuhauser, M., Tilak, T., Point-Dumont, C., and Peltier, A.: Monitoring of agricultural drought from remote sensing products and in-situ meteorological data, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3301, https://doi.org/10.5194/egusphere-egu22-3301, 2022.

EGU22-5834 | Presentations | HS7.3

Performance of regional climate models in simulating rainy seasons in West Africa 

Torsten Weber, Vincent O. Ajayi, Imoleayo E. Gbode, Daniel Abel, Katrin Ziegler, Heiko Paeth, and Seydou B. Traore

Agriculture in West Africa is highly dependent on rainfall during the rainy seasons. Therefore, modifications in rainy season characteristics due to recent and future climate change have a direct impact on crop yields and production in the region. Consequently, stakeholders and decision-makers need reliable regional climate change information on rainy seasons in order to develop appropriate adaptation measures.

Regional Climate Models (RCMs) can provide information on climate change at high temporal and spatial resolution through dynamic downscaling of climate projections generated by Earth System Models (ESMs). In order to assess the performance of RCMs in simulating rainy seasons and their characteristics such as onset and cessation, length and total sum of rainfall, a thorough evaluation of RCMs is required.

The current study evaluates the performance of three different RCMs (REMO2015, RegCM4-7 and CCLM5-0-15) in simulating rainy seasons in West Africa using gridded observational data sets. For the assessment, we will use the ERA-INTERIM driven simulations of the RCMs from the Coordinated Output for Regional Evaluations (CORE) embedded in the WCRP Coordinated Regional Climate Downscaling Experiment (CORDEX) for Africa with a spatial resolution of about 25 km.

How to cite: Weber, T., Ajayi, V. O., Gbode, I. E., Abel, D., Ziegler, K., Paeth, H., and Traore, S. B.: Performance of regional climate models in simulating rainy seasons in West Africa, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5834, https://doi.org/10.5194/egusphere-egu22-5834, 2022.

EGU22-7460 | Presentations | HS7.3

Environmental, economic and social sustainability of Alternate Wetting and Drying rice irrigation in Northern Italy 

Olfa Gharsallah, Alice Mayer, Marco Romani, Andrea Ricciardelli, Sara Caleca, Michele Rienzner, Stefano Corsi, Giovanni Ottaiano, Giulio Gilardi, and Arianna Facchi

Italy is the Europe’s leading rice producer, with over half of total European production. The main rice area is in the north-western part of the country (Lombardy and Piedmont regions). In this area, irrigation of rice has been traditionally carried out by flooding; the introduction of alternative water-saving irrigation strategies could reduce water consumption, but their overall environmental and economic sustainability, as well as their social acceptability, should be investigated.

An experimental platform was set up in the core of the Italian rice district (Lomellina, PV) to compare different rice irrigation management options: wet seeding and traditional flooding (WFL), dry seeding and delayed flooding (DFL), wet seeding and alternated wetting and drying (AWD). Six plots of about 20 m x 80 m each were set-up, with two replicates for each irrigation option. One out of two replicates for each option was instrumented with: water inflow and outflow meters, set of piezometers, set of tensiometers and water tubes for the irrigation management in the AWD plots. Proper agronomic practices were adopted for the three management options. Periodic measurements of crop biometric parameters (LAI, crop height, crop rooting depth) were performed and rice grain yields and quality (As and Cd in the grain) were determined. Data measured in the field, together with those provided by the farmer, concerning the agronomic inputs and the economic costs incurred for the three irrigation options, were used to assess their economic and environmental sustainability through a set of quantitative indicators. Finally, through interviews with rice growers of the area, barriers to the adoption of the AWD technique were assessed and ways of overcoming them identified. In order to support water management decisions and policies, data collected at the farm level are extrapolated to the irrigation district level through a semi-distributed agro-hydrological model, used to compare the overall irrigation efficiency achieved implementing AWD when compared to WFL.

How to cite: Gharsallah, O., Mayer, A., Romani, M., Ricciardelli, A., Caleca, S., Rienzner, M., Corsi, S., Ottaiano, G., Gilardi, G., and Facchi, A.: Environmental, economic and social sustainability of Alternate Wetting and Drying rice irrigation in Northern Italy, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7460, https://doi.org/10.5194/egusphere-egu22-7460, 2022.

EGU22-8093 | Presentations | HS7.3

Can an agro-hydrological model improve the irrigation management of maize under a center pivot? 

Arianna Facchi, Alice Mayer, Bianca Ortuani, and Alberto Crema

Plain areas of Northern Italy are characterized by a strong agricultural and zootechnical vocation. In the Lombardy region, the total utilized agricultural area (UAA) is about 700,000 ha, 72% of which is irrigated. Globally, about one half of the UAA is cropped with maize, but in some provinces this crop reaches almost the totality of the UAA. Maize is typically irrigated by border irrigation; however, in the context of the climate change and of the increased competition for the use of water in the plain, it is crucial to optimize the use of this resource.

This study is aimed at demonstrating the applicability of Precision Irrigation approaches in a large farm located in the core of the maize basin of the Lombardy plain (La Canova farm, BS, Italy; http://lacanovasrl.it/). In the farm, irrigation is provided by center pivots and linear irrigation systems. Although sprinkler irrigation can reduce the applied irrigation volumes compared to border irrigation, at present, a uniform irrigation rate is provided at fixed time intervals without accounting for spatial heterogeneity of soil or crop development.

During the agricultural season 2021, in a 15 hectares surface cropped with maize under a center pivot the irrigation was applied following a variable-rate approach. The soil variability was investigated using an Electromagnetic induction (EMI) sensor; through the application of cluster analysis techniques to the EMI survey, four types of soils were detected and characterized through a traditional soil sampling. According to soil variability and pivot geometry, four management zones (MZ) were identified: two MZs were characterized prevalently by coarse soils while the other two by medium-fine soils. In one ‘coarse’ MZ and one ‘fine’ MZ the irrigation was managed with the support of soil probes installed at two depth, and by a physically based agro-hydrological model (SWAP, https://www.swap.alterra.nl/) fed with weather forecasts at 7 days (https://www.abacofarmer.com/). A MATLAB code was developed to run the whole modelling system. Irrigation in the other two MZs was applied by the farmer according to the farm’s typical management (about 25-30 mm every four days). In the MZs managed with Variable Rate irrigation, the model was used to identify the optimal water depth to be applied at each irrigation event, depending on the soil water balance computed for the following 5 days; in doing this, a 4-day turn and a minimum irrigation depth of 18-25 mm (as a function of the time of the season) were respected, since they were constraints imposed by the farmer. Despite the constraints, compared to the reference MZs, the approach adopted led to a water saving of about 20 and 25% for the ‘coarse’ and ‘fine’ MZs, respectively, without a loss of yield. In the next step, the approach adopted will be used to estimate the water and energy saving achievable at the farm scale.

How to cite: Facchi, A., Mayer, A., Ortuani, B., and Crema, A.: Can an agro-hydrological model improve the irrigation management of maize under a center pivot?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8093, https://doi.org/10.5194/egusphere-egu22-8093, 2022.

EGU22-8392 | Presentations | HS7.3

Limnological responses to active management of the invasive aquatic fern Salvinia molesta in Las Curias Reservoir, San Juan, Puerto Rico. 

Xavier García López, Jorge Ortiz Zayas, Rodrigo Díaz, Aurelio Castro Jiménez, and Moisés Abdelrahman López

In the Anthropocene, human action and globalization are closely linked to the deterioration of natural habitats and water resources. Invasive aquatic weeds have been recognized as a major problem in watersheds worldwide due to their environmental impacts. This study focuses on the management of the Las Curias Reservoir in Cupey Puerto Rico in the Río Piedras watershed since the arrival of Salvinia molesta after Hurricane María in 2017.
Aquatic weed control consists of three methods: biological, mechanical, and chemical. Since December 2019, with the help of federal and local agencies, the University of Puerto Rico in Rio Piedras and a community-driven initiative led to the introduction of the Cyrtobagous salviniae in Las Curias Reservoir.  This insect is considered an effective biological control agent for S.  molesta.  Simultaneously, community members initiated a mechanical removal campaign using an aquatic harvester. Monthly sampling was conducted to measure physicochemical, biochemical, and biophysical variables in the reservoir in response to the reduction of S. molesta cover. In addition, monthly drone flights were conducted to create orthomosaic maps of the plant coverage over the water surface, as part of the monitoring of the ecosystem health and characterization. Probably the propagation of S. molesta occurred due to eutrophication after an increase in nutrient-rich sewage discharges from septic tanks and faulty sewage pump stations affected by power outages after Hurricane Maria. By 2019, the reservoir was completely covered with S. molesta. It is not until August 2020 that we noticed considerable changes in the reduction of plant density. Upon the reduction of S. molesta coverage, we found increases in the mean of water temperature (+3 Cِ°), dissolved oxygen (+1.4 mg/L), pH (+0.5) specific conductance (+118.3 µS/cm) and in light penetration (+255.6 
μmo/m^2/s).  The water stored in Las Curias could become an invaluable source of raw water for public supply during future droughts, especially in the densely populated San Juan Metropolitan Area, where Las Curias is located. Therefore, its restoration is socially relevant and justifiable. 

How to cite: García López, X., Ortiz Zayas, J., Díaz, R., Castro Jiménez, A., and Abdelrahman López, M.: Limnological responses to active management of the invasive aquatic fern Salvinia molesta in Las Curias Reservoir, San Juan, Puerto Rico., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8392, https://doi.org/10.5194/egusphere-egu22-8392, 2022.

EGU22-8409 | Presentations | HS7.3

Statistical methodology for PRV malfunction detection and alerting in Water Distribution Networks 

Anastasios Perdios, George Kokosalakis, Irene Karathanasi, and Andreas Langousis

As the outflow velocity from a pipe crack increases with increasing hydraulic pressure, pressure management concepts have been widely applied to reduce water losses in the delivering and distribution parts of water networks. In this context, pressure reducing valves (PRVs) have been commonly used to regulate pressures and therefore reduce water losses, in both water supply and water distribution networks, by reducing the upstream pressure to a set outlet pressure (i.e. downstream of the PRV), usually referred to as set point.

As all types of mechanical equipment, PRVs exhibit malfunctions affecting pressure regulation, which can be defined as events when the outlet pressure does not match the set point. These events can be classified in two categories: a) high frequency fluctuations around the set point, and b) prolonged systematic deviations from the set point. Since PRV malfunctions result in systematic or random deviations of the outlet pressure from the set point, their detection can be approached in a statistical context.

In this study, we develop a novel framework for detection of PRV malfunctions in water supply and water distribution networks, which uses: a) the root mean squared error (RMSE) as a proper statistical metric for monitoring the performance of a PRV by detecting individual malfunctions (i.e. malfunction occurrences) in the high-resolution pressure time series, and b) the hazard function concept to identify a proper duration of sequential events from (a) to issue alerts.

The suggested methodology is implemented using pressure data at 1-min temporal resolution from pressure management area “Diagora” of the water distribution network of the city of Patras (the third largest city in Greece), for a 3 year period from 01 January 2017 to 31 December 2019. The obtained results show that the developed statistical approach effectively detects major PRV malfunctions (as reported by the Municipal Water Supply Company and Sewerage of Patras, DEYAP), allowing it to be used for operational purposes.

Acknowledgments:

This research is 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-4177).

How to cite: Perdios, A., Kokosalakis, G., Karathanasi, I., and Langousis, A.: Statistical methodology for PRV malfunction detection and alerting in Water Distribution Networks, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8409, https://doi.org/10.5194/egusphere-egu22-8409, 2022.

EGU22-8898 | Presentations | HS7.3

Small Islands – Precipitation in the Future 

Maria Meirelles, Fernanda Carvalho, Diamantino Henriques, and Patrícia Navarro

For most islands, there is very little published literature documenting the probability, frequency, severity,or consequences of climate change impacts, such as an decrease in precipitation. Some times, projections of future climate change impacts are limited by the lack of model skill in projecting the climatic variables that matter to small islands. The Azores are an archipelago formed by nine high volcanic islands, presenting a relatively small land area where precipitation is of orographic origin. Relatively projections up to the end of the 21st century, they were used for the same geographic region - the Azores region between 37 °N - 40°N and 32°W - 25°W - the results of the CMIP5 project for the RCPs (Representative Concentration Pathways) scenarios; trajectories describe four possible future climate scenarios, which depend on the amount of greenhouse gases emissions that may be emitted in the coming years. The four RCP scenarios (RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5), correspond to four radiative forcing intervals for the year 2100, to pre-industrial values ​​(+2.6, +4.5, +6.0 and +8.5 W/m2, respectively). Most of the CMIP5 climate data and projections used in this work they are freely available on the Climate Ex plorer portal (https://climexp.knmi.nl/) of the KNMI (Koninklijk Nederlands Meteorologisch Instituut). Anomaly of the average annual precipitation for the Azores was calculated in the 1979-2019 period and its projections are estimated up to 2100, according to the RCP scenarios (Figure 1). In this case, the average variation calculated for the three scenarios for annual precipitation is -7.8 mm; in the case of the scenario more pessimistic (RCP 8.5), the models show for the Azores a decrease in average annual precipitation of about 9.8 mm/day until the end of the century, compared to the average of the last 30 years. According to the RCP4.5 scenario, a decrease is observed which is accentuated from the northwest to the southeast in the region under consideration, especially affecting the islands of the central and eastern groups. Of the calculations results for the average of the models an increase of the maximum number consecutive days with low rainfall (<1mm) from + 0.2 to 4.8 days / year until the year 2100. The demand for water affects basically four activities: the agriculture, energy production, industrial uses and consumption human. The projections found for the Azores of a decrease in precipitation are in line with other small island regions, such as the Caribbean and Mediterranean region. Thus, these regions become more vulnerable to social, economic and environmental impacts.

How to cite: Meirelles, M., Carvalho, F., Henriques, D., and Navarro, P.: Small Islands – Precipitation in the Future, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8898, https://doi.org/10.5194/egusphere-egu22-8898, 2022.

EGU22-10221 | Presentations | HS7.3 | Highlight

Pandemic Medical Supply Needs with a Coincident Natural Disaster and an Analysis of COVID-19 Data Availability 

Paul Churchyard, Ajay Gupta, and Joshua Lieberman

The Open Geospatial Consortium’s Disaster Pilot 2021 focused on turning earth observation and reporting data into decision ready indicators (DRI) for disaster response and management.  HSR.health as a Pilot participant  developed the recipe for, and produced a Medical Supply Needs Index that indicates what medical supplies, such as Personal Protective Equipment, are needed to respond to COVID-19 cases throughout a population. Medical Supply Needs Indices were calculated for areas within the Pilot focus regions and shared via a dashboard-style application. HSR.health and collaborators then set up an integrated demonstration showing the Medical Supply Needs Index updating in real-time as a result of data on the occurrence and impacts of multiple coincident natural disasters such as flooding, landslides, and pandemic spread. HSR.health also carried out work within the Pilot to apply and evaluate the draft Health Spatial Data Infrastructure (HSDI) model developed in the pre-Pilot OGC Health Spatial Data Infrastructure Concept Development Study. This included research into the availability of pandemic-related health related data in the US and in Peru, as well as investigation of the spatiotemporal granularity or resolution of observation data best suited to support indicators for community-level public health interventions.

How to cite: Churchyard, P., Gupta, A., and Lieberman, J.: Pandemic Medical Supply Needs with a Coincident Natural Disaster and an Analysis of COVID-19 Data Availability, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10221, https://doi.org/10.5194/egusphere-egu22-10221, 2022.

Coastal cities in India houses nearly 100 million people and are evenly distributed across India’s 7516-kilometer coastline. These cities are important centers of socio-economic activities in the country and are some of the densely populated regions in the world. A number of studies recently have predicted that there is a risk of substantial portions of these cities’ areas being lost to the sea due to sea-level rise in the next few decades, since a major portion of these cities are at a near zero elevation from the mean sea level (M.S.L). Further, in the past few decades, major coastal cities in India have been repeatedly affected by recurrent extreme rainfall events and subsequent floodings. Several studies document that rapid change in the Indian monsoon, increased frequency in the formation of cyclones and the swift changes in the hydro-climatic regime in the Indian Ocean are the major contributors to the occurrence of these extreme precipitations events. While we can safely conclude that these events are likely to occur more frequently in the future, it is important to understand the factors that control and influence these events, comprehend how the cities are and will be affected, and develop feasible policy changes and mitigation action for effective governance. In this paper, we have taken the case of Chennai – an important coastal city located in the southern part of India that has been severely affected by extreme precipitation and subsequent flooding (notably the infamous 2015 Chennai floods) in the past few years, to study the influencing factors contributing to these events and the ground challenges faced by the government machinery in planning and managing these disasters effectively. Our findings indicate that there is a notable variation in the monsoon rainfall pattern in Chennai and the net annual rainfall in the city has increased significantly in the past decade (by ~15%). Further, we found that significant urban centers in the city, especially the regions that are at near zero elevation (± 5 meters above M.S.L) are more vulnerable to flooding, and the important contributing factors to the increased severity of the recent floodings include the lack of adequate stormwater drainage infrastructure and poor policy choice of converting natural surface water bodies (lakes and ponds) into towns during the past three to four decades. We also discuss the planning and execution of Chennai city’s mitigation action during the 2021 floods, analyze its success and shortcomings, and suggest sustainable and feasible policy changes and measures that can be adopted for better management of similar events in the future in other coastal cities as well.

How to cite: Mohanavelu, A. and Soundharajan, B.-S.: Increased frequency of urban floodings in coastal Indian cities caused by variation in monsoon rainfall: Influencing factors, challenges, and solutions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10483, https://doi.org/10.5194/egusphere-egu22-10483, 2022.

EGU22-11068 | Presentations | HS7.3

Optimal sowing dates for major crops in India under climate change 

Aditya Narayan Sharma, Sai Jagadeesh Gaddam, and Prasanna Venkatesh Sampath

Agriculture plays a pivotal role in supporting the socioeconomic situation of millions of farmers in India, which is increasingly coming under threat due to climate change. In particular, the future changes in rainfall patterns has the potential to directly affect the irrigation water demands, thereby impacting water consumption, agricultural productivity, and influencing food security. For instance, the optimal sowing dates for crops may change according to the altered rainfall patterns. With this motivation, we studied the impacts of shifts in sowing periods in order to identify the optimal sowing dates for a particular crop. First, we collected daily temperature and rainfall data for India at a resolution of 0.25o from different GCM models (EC-Earth 3 and EC-Earth 3 veg) under different SSP scenarios (SSP 126, SSP 245, SSP370, SSP585). Also, region-wise agricultural data such as crop acreage and sowing dates were collected for seven major crops - paddy, wheat, maize, groundnut, sugarcane, red gram, black gram, and soybean. Subsequently, we estimated the reference evapotranspiration using the modified Penman-Monteith method. The estimated reference evapotranspiration and rainfall data were incorporated into FAO’s CROPWAT model to calculate the irrigation water requirements (IWR) of the selected crops. The optimal IWR for each crop was selected by varying the sowing dates at fifteen-day intervals across the year (twenty-four dates for the year). Preliminary results indicate that there is considerable scope for water savings by shifting the sowing dates of staple crops to account for climate change impacts. These strategies may become vital for policymakers in the coming decades to reduce the stresses on water without endangering food security. Indeed, such strategies require the cooperation of various stakeholders for better implementation at multiple scales.

How to cite: Sharma, A. N., Gaddam, S. J., and Sampath, P. V.: Optimal sowing dates for major crops in India under climate change, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11068, https://doi.org/10.5194/egusphere-egu22-11068, 2022.

EGU22-11145 | Presentations | HS7.3

Optimizing cropping patterns under the influence of climate change 

Sindhuja Reddy Pasula, Swethu Sree Gudem, Sai Jagadeesh Gaddam, and Prasanna Venkatesh Sampath

The world needs 70% more food by 2050, increasing the pressure on the available water resources. With the climate change threat approaching, the water stress will further be exacerbated that would adversely affect food security. In countries like India, with extensive cultivation of staple crops like paddy, there has been a rapid increase in the total water consumption. At the same time, cultivation of crops such as pulses and millets has not been sufficient to satisfy the nutritional requirements of India’s population. With the increased likelihood of droughts and floods due to the advent of climate change, it becomes imperative to achieve water, food, and nutritional security into the future. This study attempts to optimise cropping patterns to minimise future water requirement, while satisfying the nutritional and caloric requirements of future generations. We perform the analysis for the southern Indian state of Andhra Pradesh, where agriculture depends predominantly on irrigation. To achieve this objective of optimization, we collected bias-corrected climate datasets from three General Circulation Models (BCC-CSM2-MR, INM-CM5-0, MPI-ESM1-2 HR) that include future rainfall and temperature information from 2021 to 2050. Further, we collected crop-wise farm-level data of five major crops in the state - paddy, sugarcane, groundnut, sorghum, and red gram. The irrigation water requirement (IWR) of the selected crops was estimated using FAO’s CROPWAT model under two different scenarios - SSP 245, SSP 585. Further, we developed an optimization model to obtain the optimal cropping pattern that minimises water consumption. Future food requirements in terms of protein and calorie demands and arable land available for cultivation were used as constraints to perform this optimization. Preliminary results indicate that shifting from water-intensive crops like sugarcane to relatively more nutritious crops like red gram and sorghum has the potential to significantly reduce water consumption, while also enhancing the nutritional security of the region. Interestingly, the optimization results indicated that the southern part of the study region required more interventions in terms of crop diversification as compared to the northern part. Such insights could help decision makers to devise holistic policies, enhancing the water-food security under different climate change scenarios. Further, this research could be extended to domains such as economics, ecology, and energy to achieve overall sustainability in the agricultural sector.

How to cite: Pasula, S. R., Gudem, S. S., Gaddam, S. J., and Sampath, P. V.: Optimizing cropping patterns under the influence of climate change, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11145, https://doi.org/10.5194/egusphere-egu22-11145, 2022.

EGU22-11578 | Presentations | HS7.3

The role of urban streams in the microplastics contamination scenario: the case study of the Mugnone Creek (Florence, Italy) 

Alessio Monnanni, Gabriele Bicocchi, Eleonora De Beni, Valentina Rimondi, Tania Martellini, David Chelazzi, Alessandra Cincinelli, Stefania Venturi, Guia Morelli, Pierfranco Lattanzi, and Pilario Costagliola

Due to their spread, abundance and potential impact on food security and human health, microplastics (MPs) are emerging global pollutants. Metropolitan areas are among the main sources of MPs (1 μm - 5 mm); indeed, about 80% of the MPs found in the oceans come from freshwaters. In particular, impervious surfaces runoff in urban areas results in the transport of large quantities of solid wastes, comprising MPs, to the superficial water bodies. Thus, the ecological state of urban streams represents a reliable indicator to evaluate the environmental impact of a city. In this study, we report data about MPs in stream sediments and waters of a minor urban stream, the Mugnone Creek (MC), which flows across the highly urbanized city of Florence (Italy) and discharges to the Arno River.

Several sites along the 17 km-long MC were chosen, including “greenfield” sites upstream of the Florence urban area, urban-impacted sites located along congested roads, and the MC outlet. The stream sediments were collected in June 2019, while stream waters were recovered via glass bottles twice a year (June and December) in 2019 and 2020, to account for seasonal variability. Stream discharge was simultaneously determined during water sampling to allow mass flow calculations of contaminants.

Water samples were filtered onto glass microfiber filters (ø 47 mm) and observed by HD digital stereomicroscope; a similar method was followed for sediments after a density separation step (NaCl saturated solution) and H2O2 digestion. Fourier Transform Infrared Spectroscopy (FT-IR) was used for identification and characterization of MPs. Microparticles classification was based on polymer type, shape and colour.

MPs concentration in sediments showed an increasing trend from the pre-urban site to the outlet. A maximum value (1.540 MPs/kg) was reached immediately after the Terzolle Creek confluence, which drains the large University Hospital District of Careggi. Fibers were the dominant shape class of polymers observed and blue/black items stand out among the colour classes. The highest concentrations of MPs in water samples were recorded during winter seasons (up to 16.000 items/m3), with a predominance of fibers and blue/black colours. Polymer classification by FTIR indicated the presence of (in order of abundance): PA (polyamide), PET (Polyethylene Terephthalate), SBR (butadiene-styrene rubber), PP (Polypropylene), blend PP+PE (PP+Polyethylene), PTFE (Polytetrafluoroethylene) and PU (Polyurethane). The black-SBR polymers likely related to tyre abrasion occurring during vehicles driving, since they were especially found on a site close to traffic-congested roads. In addition to synthetic particles, high concentrations of natural fibers (mainly cellulose) were found in waters at all sites. Up to 109 synthetic particles are estimated to be discharged daily by MC to the Arno River during the winter season, a load much higher than creeks with similar urbanization context worldwide. Mass loads of natural fibers were of the same order of magnitude of MPs in every season.

Studies are in progress to elucidate the impact on local biota and to characterize the anthropic pressure on the Arno River, aiming to improve the knowledge about the environmental status of one of the main Italian river basins.

How to cite: Monnanni, A., Bicocchi, G., De Beni, E., Rimondi, V., Martellini, T., Chelazzi, D., Cincinelli, A., Venturi, S., Morelli, G., Lattanzi, P., and Costagliola, P.: The role of urban streams in the microplastics contamination scenario: the case study of the Mugnone Creek (Florence, Italy), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11578, https://doi.org/10.5194/egusphere-egu22-11578, 2022.

Due to climate change, extreme weather conditions such as droughts may have an increasing impact on the water demand and the productivity of irrigated agriculture. For the adaptation to changing climate conditions, knowledge about adequate irrigation control strategies and information, e.g., about future climate development and soil properties, is of great importance for the optimal operation of irrigation systems. We consider climate and soil variability within one probabilistic simulation-optimization framework for irrigation scheduling based on Monte Carlo simulations to support informed decisions. The framework implements optimizers for full, deficit, and supplemental irrigation strategies. We provide the  Matlab code as the open source Deficit Irrigation Toolbox (DIT). For this analysis, we apply DIT for preliminary test simulations for a global numerical deficit irrigation experiment (GDIE) which allows for the analysis of both the impact of the selected irrigation strategy on water productivity and the value of information about (i) different scheduling methods, (ii) climate development, and (iii) soil hydraulic properties. The first results show a strong dependency on the value of information about climate and soil for sites required for increasing water productivity in different climate regions. Moreover, DIT can enable and support the site-specific transformation of low efficient rainfed and irrigated systems achieving higher water productivity and food insecurity on a local scale.

How to cite: Schütze, N. and Dietz, A.: Comparison of the value of information for the management of deficit irrigation systems in different climate regions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11631, https://doi.org/10.5194/egusphere-egu22-11631, 2022.

EGU22-12798 | Presentations | HS7.3

FORESHELL Project: development of sanitary/weather-environmental predictive technological tools to enhance the efficiency and sustainability of shellfish farming. 

Barbara Tomassetti, Annalina Lombardi, Valentina Colaiuda, Federica Conti, Giuseppina Mascilongo, Fabrizio Capoccioni, Domitilla Pulcini, Gabriella Di Francesco, Ludovica Di Renzo, Chiara Profico, Carla Ippoliti, Carla Giansante, Nicola Ferri, and Federica Di Giacinto

Many of the estuaries and coastal areas in Europe are used for the cultivation and harvesting of bivalve mollusks. Mussel farming is strongly influenced by weather and environmental conditions. Several studies have shown that the sanitary conditions of shellfish are related to hydrological factors of rivers adjacent to the farming area, as rivers are the main routes of bacteriological contamination from the surface or sub-surface.

The "FORESHELL" project, funded by Costa Blu FLAG as part of the EMFF 2014-20 program of the Abruzzo Region, is carrying out a pilot initiative for the development of sanitary/weather-environmental predictive technological tools in order to improve efficiency and sustainability of the mussel farm located at the Giuliano Maritime District.

A specific sampling schedule is established before and after severe weather events to determine the E. coli
concentration in freshwater at the river mouths and in mussels/seawater in the farming site. At the same time, the hydrographic basins of the rivers close to the farm, Vibrata and Salinello, are constantly monitored trough the hydrological model (CHyM), to predict the occurrence of flow discharge peaks at mouth of the river. In addition, the satellites and the in-situ probe acquire environmental parameters such as sea water temperature, salinity, chlorophyll-a, sea currents and wave motion.

The web application for data visualization is under construction, as well as the early warning reports to the farmer. Furthermore, the growth of mussels is constantly monitored with biometric controls. The implementation of all phases of the FORESHELL project are proceeding according to the timeline in order to develop innovative tools useful for the management of mussel farming area.

How to cite: Tomassetti, B., Lombardi, A., Colaiuda, V., Conti, F., Mascilongo, G., Capoccioni, F., Pulcini, D., Di Francesco, G., Di Renzo, L., Profico, C., Ippoliti, C., Giansante, C., Ferri, N., and Di Giacinto, F.: FORESHELL Project: development of sanitary/weather-environmental predictive technological tools to enhance the efficiency and sustainability of shellfish farming., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12798, https://doi.org/10.5194/egusphere-egu22-12798, 2022.

EGU22-1826 | Presentations | HS5.5

Quantifying economic-social-environmental trade-offs and synergies of water-supply constraints: An application to the capital region of China 

Dandan Zhao, Junguo Liu, Laixiang Sun, Bin Ye, Klaus Hubacek, Kuishuang Feng, and Olli Varis

Quantifying economic-social-environmental trade-offs and synergies of water-supply constraints: An application to the capital region of China

 

Dandan Zhao a,b, Junguo Liub,, Laixiang Sunc,d,e,, Bin Ye b, Klaus Hubacekf, Kuishuang Fengc, Olli Varisa

 

a Water & Development Research Group, Aalto University, PO Box 15200, 00076 Espoo, Finland

b School of Environmental Science and Engineering, Southern University of Science and Technology, China

c Department of Geographical Sciences, University of Maryland, College Park, USA

d School of Finance and Management, SOAS, University of London, London, UK

e Institute of Blue and Green Development, Weihai Institute of Interdisciplinary Research, Shandong University, Weihai,

f Integrated Research of Energy, Environment and Society (IREES) , University of Groningen, the Netherlands

 

Sustainable water management is one of the sustainable development goals (SDGs) and is characterized by a high level of interdependencies with other SDGs from regional to global scales. Many water as[1]sessment studies are restricted to silo thinking, mostly focusing on water-related consequences, while lacking a quantification of trade-offs and synergies of economic, social, and environmental dimensions. To fill this knowledge gap, we propose a “nexus” approach that integrates a water supply constrained multi-regional input-output (mixed MRIO) model, scenario analysis, and multi-criteria decision analysis (MCDA) to quantify the trade-offs and synergies at the sectoral level for the capital region of China, i.e. the Beijing-Tianjin-Hebei urban agglomeration. A total of 120 industrial transition scenarios includ[1]ing nine major industries with high water-intensities and water consumption under current development pathways were developed to facilitate the trade-off and synergy analysis between economic loss, social goals (here, the number of jobs) and environmental protection (with grey water footprint representing water pollution) triggered by water conservation measures. Our simulation results show that an imposi[1]tion of a tolerable water constraint (a necessary water consumption reduction for regional water stress level to move from severe to moderate) in the region would result in an average economic loss of 68.4 (± 16.0) billion Yuan (1 yuan ≈ 0.158 USD$ in 2012), or 1.3 % of regional GDP, a loss of 1.94 (± 0.18) million jobs (i.e. 3.5 % of the work force) and a reduction of 1.27 (± 0.40) billion m3 or about 2.2% of the regional grey water footprint. A tolerable water rationing in water-intensive sectors such as Agriculture, Food and tobacco processing, Electricity and heating power production and Chemicals would result in the lowest economic and job losses and the largest environmental benefits. Based on MCDA, we selected the 10 best scenarios with regard to their economic, social and environmental performances as references for guiding future water management and suggested industrial transition policies. This integrated approach could be a powerful policy support tool for 1) assessing trade-offs and synergies among multiple criteria and across multiple region-sectors under resource constraints; 2) quantifying the short-term supply-chain effects of different containment measures, and 3) facilitating more insightful evaluation of SDGs at the regional level so as to determine priorities for local governments and practitioners to achieve SDGs.

How to cite: Zhao, D., Liu, J., Sun, L., Ye, B., Hubacek, K., Feng, K., and Varis, O.: Quantifying economic-social-environmental trade-offs and synergies of water-supply constraints: An application to the capital region of China, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1826, https://doi.org/10.5194/egusphere-egu22-1826, 2022.

EGU22-3637 | Presentations | HS5.5

Integrated assessment of renewable urban heating systems considering water use, committed emissions and energy justice 

Chelsea Kaandorp, Nick van de Giesen, and Edo Abraham

Transitioning towards renewable heating is important to minimise the use of fossil fuels and abate carbon emissions, because heating accounts for 50% of the final energy consumption and 40% of carbon dioxide emissions globally. In the city of Amsterdam, the Netherlands, the aim is to transition towards renewable heating by 2040 and achieve carbon-neutral heating by 2050 through a neighbourhood-based approach. Such an approach entails that per neighbourhood a renewable heat solution is chosen  based on criteria such as carbon emissions, reliability, affordability and feasibility. The impacts of urban heating systems however goes beyond a neighbourhood, and take place on multiple spatial and temporal scales. In this presentation we discuss how a transition towards renewable heating systems can influence the water-energy-land nexus on multiple scales in three ways.

First, heating systems use water locally, but also indirectly through the water footprint embedded in energy carriers. We therefore present an analysis of the direct and indirect water use of heating pathways towards 2050. Second, heating systems which currently have the lowest carbon emissions, may not be the heat option with the lowest carbon emissions in the future. Current decisions for heat options can therefore create non-optimal solutions for minimising carbon emissions in the future. An optimization model to find a mix of heating systems to reduce committed emissions on a neighbourhood scale within a given time period for different scenarios for the insulation of buildings and the decarbonisation of electricity generation is therefore presented. At last, new norms and forms of organising neighbourhood-based heating systems may emerge, potentially creating or exacerbating social inequalities within and beyond the spatial boundaries of a neighbourhood. We therefore present the preliminary results of an analysis on energy justice based on in-depth interviews with urban professionals, dwellers and decision makers in Amsterdam. 

By presenting these three studies we aim to address the challenge of multi-scale impacts of transitioning towards renewable urban energy systems and show how energy-water-land nexus research can contribute to decision making for urban infrastructures.

How to cite: Kaandorp, C., van de Giesen, N., and Abraham, E.: Integrated assessment of renewable urban heating systems considering water use, committed emissions and energy justice, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3637, https://doi.org/10.5194/egusphere-egu22-3637, 2022.

Nature-based solutions (NbS) in brook catchments are considered as climate measures to adapt to hydro-meteorological extremes (storms, floods, droughts) and human-induced water demand. These NbS, often wetlands at multiple scales, cause land-use change (LUC), e.g., from cropland into wetland. Furthermore, LUC is also caused by other anthropogenic reasons (e.g., urbanization, channeling).

To improve this modelling by incorporating multi-scale spatial and temporal aspects, earlier studies modelled LUC and carbon pools, but did this without a regional focus on the impact of NbS. A system analysis of a brook catchment (Dutch Aa/Weerijs; 147 km2; S of Breda)  determines the spatio-temporal dynamics of LUC and its connection to carbon pools including the climate mitigation impact of NbS. The question arises if ready-to-use tools can help to connect the associated spatio-temporal datasets, to support professionals in regional development on rapid appraisal of carbon pool dynamics and impacts of NbS.

Firstly, in a pilot study, a system analysis of LUC and temporal carbon pool data has been developed on open access datasets (e.g., open topo and land registry). To get an outlook for 2050, 1960 was taken as a starting point because the brook catchment, including the brook itself, transformed just after 1960. To determine historic spatio-temporal dynamics of LUC and carbon pools, 2010 was chosen. Then, the landscape is predicted for 2050 in two scenarios: A Technical/physical scenario (in which a business-as-usual situation is considered) and a NbS/Wetlands scenario which focusses on NbS and in particular on wetlands. Four terrestrial carbon pools within seven land-use categories have been used. Land-use classification for 1960 and 2010 has been done with topographic maps and ArcGIS. Land-use prediction for 2050 has been done with a Land Change Modeler (TerrSet2020, ClarkLabs) with land-use from 1960 and 2010 as input data.

Secondly, the results of the pilot study have been validated by a field visit and regional professionals with expertise on LUC and carbon pools. As a third step, the updated, validated method has been applied to the whole Dutch catchment.

Findings indicate that 40 km2 (≈ 27%) transformed between 1960 and 2010 with an impact on terrestrial carbon of + 0.5 Mton (≈ +50% change: 1 Mton in 1960 and 1.5 Mton in 2010). Findings for 2050 are:

  • For the Technical-physical scenario a minor increase of terrestrial carbon. This will probably be explained by settlement expansion and by the increase areal of tree nursery. Tree nursery is especially a land-use category that emerges in the study area.
  • For the NbS/Wetlands scenario, which emphasizes wetlands as nature-based solutions, a major increase of terrestrial carbon. This is explained by the increase of the areal of wetlands.

In this study we presented an approach where a combination of tools - a land change modeler and ArcGIS - can be used for a rapid assessment of mitigating effects on climate adaptation measures. This offers water professionals the opportunity to meet the many challenges on NbS in brook/river basins.

How to cite: Timmer, L., Van Wijnen, J., and Lansu, A.: Nature-based solutions in brook catchments: Modelling land-use change and its impact on terrestrial carbon pools (1960 – 2010 – 2050)., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4006, https://doi.org/10.5194/egusphere-egu22-4006, 2022.

EGU22-6964 | Presentations | HS5.5 | Highlight

Global emission trade market design and local outcomes on the water-energy-land nexus 

Mel George, Sha Yu, Leon Clarke, and Jae Edmonds

The COP26 in Glasgow produced a Paris Agreement rulebook for international cooperation through carbon markets under Article 6. The intent of Article 6 is to enhance mitigation ambition by utilizing efficiency gains from trading and to cooperatively implement nationally determined contributions (NDCs) while avoiding double-counting. Such international emissions trading forms the bedrock to mobilize public and private sector investment flows to meet ambitious climate goals. At the same time, a growing body of research concludes that there are important links between mitigation and other societal objectives, such as those embodied in the UN Sustainable Development Goals (SDGs). Such local and national decisions which consider co-benefits and tradeoffs on some of the SDGs, in turn, are critical in deciding the aggregate success and consequences of global policies. This raises the question of how emissions trading may enable or hinder SDG attainment and how different countries might value their participation in such markets.

 

Countries view their own climate mitigation efforts through a more comprehensive lens than mere emissions reduction, and the links with societal outcomes would influence their consideration of comparability and participation in emissions trading markets. The success of these markets in enhancing ambition would depend on perceptions of the relationships of mitigation with local and regional societal goals around water, energy & land use. The degree of congruence between these relationships could influence future climate negotiations and market design.

 

In this paper, using a global integrated assessment model (GCAM: Global Change Analysis Model, ver. 5.4), we demonstrate that spatial and temporal distributions of the influence of Article 6 emissions markets on a subset of the broader SDGs may differ. We use a subset of sustainability metrics related to the energy-water-land nexus issues. Our analysis of these metrics tracks the interconnected nature of human and earth systems under different emission market designs for 10 key geographical regions (USA, EU, China, India, Japan, Brazil, Russia, Australia, Sub-Saharan Africa & Latin America) from 2030 to 2050, under a consistent integrated framework. This allows us to assess the local implications of emissions market design on energy access, prices & security, water consumption for different applications, food prices and forest area changes. We include the effects of redistribution and international financial transfers. We demonstrate these effects on the energy-water-land nexus for different national and global mitigation scenarios: the recently updated NDCs, a net zero emissions target in 2050 and a scenario which allows countries to reach net zero goals based on equity principles.    

 

Our results imply that global cooperation in markets can be altered if interactions between mitigation and local effects on the energy-water-land triad were accounted for. Furthermore, we demonstrate that the extent to which these distributions differ depends on market design and pricing of nature-based mitigation options.

 

Our analysis provides a foundation for assessing how global emission market schemes under Article 6 could be better understood in the local developmental contexts of energy, water & land use changes.

How to cite: George, M., Yu, S., Clarke, L., and Edmonds, J.: Global emission trade market design and local outcomes on the water-energy-land nexus, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6964, https://doi.org/10.5194/egusphere-egu22-6964, 2022.

EGU22-9311 | Presentations | HS5.5 | Highlight

Trade-offs between water needs for food, utilities, and the environment—a nexus quantification at different scales 

Lotte de Vos, Hester Biemans, Jonathan C Doelman, Elke Stehfest, and Detlef P van Vuuren

With a growing population and a changing climate, competition for water resources in the water-energy-food (WEF) nexus is expected to increase. In this study, competing water demands between food production, freshwater ecosystems and utilities (energy, industries and households) are quantified. The potential trade-offs and related impacts are elaborated for different SSP scenarios with the integrated assessment model IMAGE, which includes the global vegetation and hydrology model Lund-Potsdam-Jena managed Land (LPJmL). Results for the 2045–2054 period are evaluated at the global scale and for a selection of 14 hotspot basins and coastal zones. On the global scale, we estimate that an additional 1.7 billion people could potentially face severe water shortage for electricity, industries and households if food production and environmental flows would be prioritized. Zooming in on the hotspots, this translates to up to 70% of the local population. Results furthermore show that up to 33% of river length in the hotspots risks not meeting environmental targets when prioritizing other water demands in the nexus. For local food production, up to 41% might be lost due to competing water demands. The potential trade-offs quantified in this study highlight the competition for resources in the WEF nexus, for which impacts are most notably felt at local scales. This emphasizes the need to simultaneously consider different dimensions of the nexus when developing scenarios that aim to achieve multiple sustainability targets.

How to cite: de Vos, L., Biemans, H., Doelman, J. C., Stehfest, E., and van Vuuren, D. P.: Trade-offs between water needs for food, utilities, and the environment—a nexus quantification at different scales, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9311, https://doi.org/10.5194/egusphere-egu22-9311, 2022.

EGU22-10568 | Presentations | HS5.5

High-resolution water temperature impact assessment on thermal power plants operations in Europe and riverine ecosystems 

Marko Adamovic, Ad de Roo, Berny Bisselink, and Bruna Grizzetti

Thermal power plants consume large amounts of water for electricity generation, mainly for cooling purposes that is later discharged back to riverine eco-systems. Increase in water temperature of the river systems and oceans is becoming the real environmental challenge to tackle, posed by the accelerated changes in climate change.  

In this study, new high-resolution data set of the water temperature projections of the main rivers in Europe due to climate change has been created using the new LISTEMP water resources model. We developed the new model called LISTEMP as a result of online coupling between the LISFLOOD open source hydrological model and newly developed water temperature module that runs on a 5 km grid and solved using a semi-Lagrangian numerical scheme. The results are based on 11 climate models which project current and future climate under two Representative Concentration Pathways (RCPs): RCP4.5 and RCP 8.5 emission scenario. We assess thermal plant's vulnerability to water temperature changes as climate change continues.  

We conclude that operations and maintenance of many thermal power plants could be at risk due to the water temperature change since their efficiency and performance depend mostly on a possibility to intake huge quantities of cooling water. Furthermore, we identified the hot spots in Europe where current power plants urge for technological change in order to be more resilient to climate. We also detect spots where plants are returning water at a temperature above the ecologically desirable ranges due to climate change. Knowledge acquired in this study and dataset contribute to multi-scale water-energy-food nexus and Common Fisheries Policy for conserving fish stocks with future climate.

 

How to cite: Adamovic, M., de Roo, A., Bisselink, B., and Grizzetti, B.: High-resolution water temperature impact assessment on thermal power plants operations in Europe and riverine ecosystems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10568, https://doi.org/10.5194/egusphere-egu22-10568, 2022.

EGU22-10882 | Presentations | HS5.5

Integrating climate impacts across energy, water, land systems within a global framework 

Muhammad Awais, Adriano Vinca, Edward Byers, Oliver Fricko, Stefan Frank, Yusuke Satoh, Volker Krey, and Keywan Riahi

IIASA’s Integrated Assessment Model (IAM), MESSAGEix-GLOBIOM is used in various assessments to understand scenarios of socio-economic development within the energy and land systems across scales (global, country, basin). However, the representation of climate impacts and water systems within IAMs until now has been limited. The study goes a step forward on improving the representation of climate impacts and the capability to analyze interactions between population, economic growth, energy, land, and water resources in a dynamic system simultaneously. It uses spatially resolved representation of water systems to retain hydrological information without compromising computational complexity, and simplified water availability and key infrastructure assumptions mapped with the energy and land systemsThe results from this study inform the required regional and sectoral investments pathways across mitigation and non-mitigation pathways. The results also highlight the importance of water as a constraint in energy and land-use decisions and implications of global responses to the limited water availability from water resources – renewable water, non-renewable groundwater, desalinated water 

How to cite: Awais, M., Vinca, A., Byers, E., Fricko, O., Frank, S., Satoh, Y., Krey, V., and Riahi, K.: Integrating climate impacts across energy, water, land systems within a global framework, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10882, https://doi.org/10.5194/egusphere-egu22-10882, 2022.

EGU22-10955 | Presentations | HS5.5

Causality Analysis in the Water-Energy-Food Nexus in the Canadian Prairies 

Behdad Saed, Amin Elshorbagy, and Saman Razavi

As global water, energy, and food (WEF) demands are continuously increasing because of population growth, climate change, and the modernization of the human lifestyle, sustainable resource management is of prime importance. Societies have been struggling with the planning and management of WEF resources under changing population, climate, and ecosystem. Integrated resource management is essential to achieve optimal and sustainable WEF management as sector-centric (e.g. water-centric) management can lead to poor outcome. To that end, WEF nexus as a multi-centric approach has been introduced to emphasize interlinkages among WEF sectors. Such interlinkages need to be identified, quantified, and analyzed to facilitate sustainable WEF resources management.

This study aims to conduct a quantitative data analysis within the WEF nexus context to identify the interrelationships among WEF sectors and to understand how each sector interacts with other sectors in the Canadian Prairie provinces (Alberta, Saskatchewan, and Manitoba) individually, and as a whole over the period 1990-2020. Historical data used in this study are at annual temporal and provincial spatial resolution. A correlation-and-causality analysis has been conducted for different pairs of WEF sectors to measure the degree of relationships and to explore the cause-and-effects between each pair of sectors. The Multispatial Convergent Cross Mapping method, as a causal inference tool, has been used for identifying and assessing the causal relations. Determining the causal relationships among WEF sectors helps researchers identify critical components, of a large and complex system, for further investigation and modelling. It can also guide policy-makers for better allocation of resources.

Results showed that water has a stronger influence on food and energy than the other way around in the upstream province of Alberta. It was also found that food had more influence on energy than the other way around in the three prairie provinces. This study is a step forward toward a better understanding of the WEF nexus by using causal inference methods for tracking the strength of interactions to identify dominant sectors at both the provincial and regional scales. This can help build more parsimonious and efficient WEF nexus models for further simulation and scenario analysis.

How to cite: Saed, B., Elshorbagy, A., and Razavi, S.: Causality Analysis in the Water-Energy-Food Nexus in the Canadian Prairies, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10955, https://doi.org/10.5194/egusphere-egu22-10955, 2022.

EGU22-11545 | Presentations | HS5.5

Integrated surface and groundwater resources management in a coastal aquifer (Cap BonPeninsula-NE of Tunisia) 

Ichrak Khammessi, Serge Brouyère, Jalel Aouissi, adel zghibi, Ali Mirchi, Anis Chkirbene, Amira Merzougui, Mohamed Haythem Msaddek, and Hamadi Habaieb

Coastal aquifers are usually the main source of water supply for irrigation, drinking
and industrial purposes in coastal regions. They are often subject to overexploitation and
consequent quantitative and qualitative degradation. The groundwater flow system of the Chiba
watershed in the CapBon peninsula (NE of Tunisia) is a typical case of an overexploited aquifer,
where a piezometric depression exceeding -10 m (a.m.s.l) appeared has developed over the two
last decades. Among the numerous remediation tentatives, the SMART-WATER project aimed
to propose a remediation plan based on a smart monitoring and water-energy nexus solution
through the installation of smart energy and water meters (SEWM). This technology aims to
optimize groundwater pumping at a set of selected representative farming systems in the
watershed. In this context, a first coupled surface water-groundwater flow model has been
developed and applied, coupled with energy nexus for the irrigated Chiba plain. The model is
implemented using a dynamic coupling between MODFLOW WEAP and LEAP in order to
assess the SEWM system efficiency in reducing aquifer exploitation and electrical energy
consumption at farm level. Multi-objective calibration of the model using river discharge and
GW level data has yielded accurate simulation of historical conditions, and resulted in better-
constrained parameters compared to using either data source alone. Model simulations show that
crop water demand cannot be met during droughts due to limited GW pumping capacity, and that
increased GW pumping has a relatively strong impact on GW levels due to the small specific
yield of the aquifer. Groundwater and energy models have also revealed that, under different
management and climatic scenarios, electric energy consumption and groundwater table decline
are intricately connected. Despite the short monitoring period and the intermittence of the
received data, SEWMs have shown a promising role in monitoring groundwater pumping and
engaging farmers in energy saving and aquifer sustainability.

How to cite: Khammessi, I., Brouyère, S., Aouissi, J., zghibi, A., Mirchi, A., Chkirbene, A., Merzougui, A., Msaddek, M. H., and Habaieb, H.: Integrated surface and groundwater resources management in a coastal aquifer (Cap BonPeninsula-NE of Tunisia), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11545, https://doi.org/10.5194/egusphere-egu22-11545, 2022.

EGU22-12998 | Presentations | HS5.5 | Highlight

Exploring Uncertainty Surrounding Deep Decarbonization Pathways: Application to Colombia 

Mengqi Zhao, Thomas Wild, Brinda Yarlagadda, Leon Clarke, and Gokul Iyer

Limiting end-of-century temperature rise to 1.5-2 degrees C will require achieving net-zero CO2 emissions globally by 2050. Toward this goal, the Government of Colombia (GoC) is crafting a portfolio of actions (i.e., a mid-century strategy) that will not only substantially reduce emissions but also perform well across a range of societal objectives, despite the many uncertainties to which those actions will be exposed. In collaboration with a diverse array of stakeholders, here we seek to discover which actions hold promise for Colombia to achieve its climate and other societal objectives under a range of future uncertainties. The most effective mix of actions from Colombia’s perspective maybe those that create a solid near-term foundation for future ambitious action, and also those that avoid poor performance (across multiple societal objectives) under future uncertainty. This presentation will identify key elements of a robust decarbonization strategy for Colombia, and understand which sources of uncertainty may be critical to acknowledge and better understand.

It is not possible to assign meaningful probabilities to scenarios that consist of complex combinations of policy actions (i.e., levers) and uncertainties. However, it is possible to discover which scenarios, or combinations of levers and uncertainties, drive consequential outcomes across societal objectives. We use the “XLRM” conceptual organizing framework for defining this immense challenge and its possible solutions in Colombia, including: policy levers ("L"), such as renewable portfolio standards and electric vehicles deployment; future uncertainties ("X") such as socioeconomic change, technological change, and climatic change; and metrics ("M") for evaluating the relevant societal outcomes that result from the implementation of levers in uncertain future worlds, such as air quality, food security, water security, energy access, land use change, and economic development. To map policy levers to key outcomes (metrics) under uncertainty, we use the Global Change Analysis Model (GCAM) v5.3 to explore the order of 10,000 GCAM scenarios reflecting diverse futures. The study focuses on a set of questions, and a methodological approach, that have immediate relevance to Colombia but also broader applications both within Latin America and beyond to the rest of the world.

How to cite: Zhao, M., Wild, T., Yarlagadda, B., Clarke, L., and Iyer, G.: Exploring Uncertainty Surrounding Deep Decarbonization Pathways: Application to Colombia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12998, https://doi.org/10.5194/egusphere-egu22-12998, 2022.

ERE2 – Renewable energy

EGU22-380 | Presentations | ERE2.1

Comparative analysis of wind and solar energy potential from differnet  climate regions, case studies  of Morocco , India and  Kenya 

Abderrahmane Mendyl, Arun Gandhi, Peter K Musyimi, Balázs Székely, and Tamás Weidinger

Wind and solar energy have emerged as the one of the most popular and successful sources of renewable energy in combating environmental degradation and climate change. Countries around the world are developing policy mechanisms for increasing the share of renewable energy technologies for fulfilling their energy demands. Both wind and solar have proved their potential as clean and efficient sources of energy generation. Therefore, transitioning into a sustainable future requires a shift from fossil fuels to renewable energy technologies. The main goal of this study is to compare wind and solar energy potential for different climate regions of Morocco, India and Kenya using standard methodologies.

In this study we have used the wind profile power law relationship for estimating the wind speed and power at 100 m level. We are analysing long term synoptic datasets from 2 to 4 synop stations in arid and humid regions of North India, Morocco and Kenya based on the Meteomanz standard meteorological database. Stability dependent power law profile approximations were used and comparisons made with ERA5 reanalysis data. Estimation of wind energy production for different continental wind generators were also provided. Using the connection between the wind speed and profile law we demonstrated how wind energy can vary using different values of power law exponents for different climatic regions.

Standard meteorological measurements (temperature, humidity and cloudiness) gave the opportunity for estimation of global irradiance which was also compared with the ERA5 dataset. Applicability of widely used direct and diffuse irradiance parameterizations for different climate regions were also investigated.

For instance, in Marrakech the six Pasquill-Gifford stability classes were determined by estimating the global solar irradiance for cloudy and clear sky conditions as well as the wind speed. Analysis of the data showed that windspeed at 10 m varied between 1.8 m/s in the early morning (UTC 06:00) to 3.5 m/s in the evening (UTC 18:00) while the windspeed at 100 m varied between 2.6 m/s and 5 m/s at the same time periods.  The estimated wind energy at 100 m level for rural areas was more than that of urban areas The wind energy at 100 m varied between 47.2 KW in the early morning (UTC 06:00) to 573 KW in the evening (UTC 18:00) for the rural areas while in urban areas the variation was between 83.8 KW to 670.5 KW during the same time periods. The annual average global solar radiation was found to be maximum during the afternoon with a value more than 970 W/m2.

How to cite: Mendyl, A., Gandhi, A., Musyimi, P. K., Székely, B., and Weidinger, T.: Comparative analysis of wind and solar energy potential from differnet  climate regions, case studies  of Morocco , India and  Kenya, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-380, https://doi.org/10.5194/egusphere-egu22-380, 2022.

We present an intercomparison of a one year of atmospheric simulations performed with a numerical atmospheric model system based on the WRF model with tall mast observations. We employ the nestinga capabilities of the WRF model to run up to high resolution large-eddy simulations (WRF-LES). The simulations  aim at describing the wind climatology and the turbulence characteristics at Østeild, Denmark. There, DTU established the National Test Site for Wind Turbines, where some of the largest wind turbines prototypes are under testing. We evaluate the goodness of the simulations using the WRF-LES system by comparison with high-quality mean wind and turbulence observations from a 250-m meteorological mast. The main objective of the work is to demostraste that the WRF model does not only provide long-term time series of wind speed and direction but also turbulence characteristics and parameters, which are needed for the evaluation of the site conditions, and turbine design and peformance.

The WRF-LES based simulations are performed using four nested telescopic domains centered at the Østerild mast position. The outermost and largest domain has a horizontal resolution of 6250 m, whereas the innermost and smallest domain a horizontal resolution of 50 m. By modeling at these scales, we intend to resolve most of the turbulent scales.  We run the two outermost domains in a traditional mesoscale fashion, which means we use a commmonly used planetary boundary layer (PBL) scheme, whereas the two innermost domains are run in large-eddy simulation mode, i.e., without a PBL scheme. A complete year is simulated through parallel ten day long simulations. The output for the innermost domain is produced at the model grid point closest to Østerild every 12 s, whereas that of the other domains is produced every 10-min.

After computing the 10-min statistics for the full year on the model output of the innermost domain output and the 1-Hz data of the cup anemometers at Østerild that cover the range of the mast, we find very good agreement between the observed and simulated wind climatology. Turbulence estimates from both observations and simulations are also in good agreement, even though from the observations the site shows a wide variety of atmospheric stability and turbulence conditions. The turbulence intensity changes with wind speed in a similar way both in the simulations and the measurements. Our work shows that numerical models can be used as a tool to describe turbulent site conditions required, among others, for the efficient siting of wind turbines.

How to cite: Peña, A. and Mirocha, J.: Intercomparing WRF-LES based turbulence simulations with measurements from a 250-m tall meteorological mast, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-800, https://doi.org/10.5194/egusphere-egu22-800, 2022.

EGU22-1837 | Presentations | ERE2.1

Quantifing the influence of meteorological and large-scale atmopsheric drivers on energy compound events 

Noelia Otero, Olivia Martius, Sam Allen, Hannah Bloomfield, and Bettina Schaefli

 The transition towards decarbonized power systems requires to account for the impacts of the climate variability and climate change on renewable energy sources. With the growing share of wind and solar power in the European power system and their strong weather dependence, balancing the energy demand and supply becomes a great challenge. In this study, we assess energy compound events, defined as periods of simultanous low renewable production of wind and solar power, and high electricity demand. Using a country-based logistic regression approach, we model the binary occurrence of energy compound events and we examine the effects of meterological and weather regimes. Then, we quantify the meteorological conditions resulting in the highest probability of occurrence of energy compound events. We found that the combination of extremely low temperatures (below the 5th percentile) and low wind speed (below the 10th percentile), along with moderate-high solar radiation (above the 50th percentile), lead to the highest probability of occurrence of energy compound events over most European countires. Furthermore, we show that blocked weather regimes lead to the weather conditions that can have a major risk in the European power system. In particular, the Greenland blocking and the European blocking were associated with widespread energy compound events that affected multiple countries at the same time. Our results highlight the importance of the weather regimes that result in spatially compounding energy events, which might a major impact within a potential fully interconnected European grid.

How to cite: Otero, N., Martius, O., Allen, S., Bloomfield, H., and Schaefli, B.: Quantifing the influence of meteorological and large-scale atmopsheric drivers on energy compound events, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1837, https://doi.org/10.5194/egusphere-egu22-1837, 2022.

EGU22-2164 | Presentations | ERE2.1

Climatology and Spatial Patterns of Cloud Shadows and Irradiance Peaks 

Wouter Mol, Bert Heusinkveld, Wouter Knap, and Chiel van Heerwaarden

Surface irradiance variability is present on many spatio-temporal scales, but most strongly on the scale of minutes to seconds due to low broken clouds. Fast and large fluctuations, or spatial heterogeneity, of irradiance affects solar energy production. In idealised settings, let alone in operational forecasts, the modelling of realistic fields of surface irradiance in the presence of clouds is challenging. It relies on realistic cloud fields, is computationally demanding due to the nature of 3-d radiative transfer models, and ultimately requires observations for validation. Dense spatial observation of irradiance on the scale of cloud shadows or solar energy parks are rare, however. Even 1-d time series are often not available at high enough resolution. 

In ongoing work, we provide those missing observations. I will present our gathering and analyses of new and detailed observations of surface irradiance to address knowledge gaps in our physical understanding and provide validation datasets for models. In 2021, we deployed a dense network of custom, low-cost radiometers at two field campaigns, FESSTVaL (Germany) and LIAISE (Spain), to observe spatial patterns of irradiance driven by clouds. The instruments are able to closely match expensive conventional instruments, and combined with skyview imagery, the spatial observations are directly linked to observed clouds. To complement these short term spatial data, long-term statistics of irradiance variability are derived from a 10-year 1 Hz resolution data from the Baseline Surface Radiation Network station in Cabauw, the Netherlands. Distributions and typical spatio-temporal scales of cloud shadows and irradiance peaks can be related to cloud type and meteorological conditions. The gathering and study of these datasets will lead to a better understanding of the physics, help validate models, and ultimately improve our ability to accurately forecast irradiance variability at the small scales.

How to cite: Mol, W., Heusinkveld, B., Knap, W., and van Heerwaarden, C.: Climatology and Spatial Patterns of Cloud Shadows and Irradiance Peaks, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2164, https://doi.org/10.5194/egusphere-egu22-2164, 2022.

EGU22-2287 * | Presentations | ERE2.1 | Highlight

Kyrill, Franz, and the Societal Impacts of the Storms of January 2007 

Anthony Kettle

January 2007 was a remarkably stormy period in Europe with impacts on societal infrastructure and implications for energy meteorology.  A series of cyclones tracked across the North Atlantic and into Europe during the two week period 8-22 January 2007.  For many parts of Europe, Storm Kyrill on 18 January 2007 was the most important of these for the infrastructure damage that it caused.  It had the highest European storm-related insurance losses in recent history.  The storm spawned a high intensity derecho that started in western Germany and travelled into eastern Europe. It was associated with severe convection, lightning, several tornadoes, and strong wind gusts.  The storm caused over 50 fatalities, widespread disruption of transport and power networks, and a lot of forest damage.   Storm Hanno on the 14 January 2007 was the second most severe storm of the period with serious impacts in Norway and southern Sweden.  Wind gusts reached the level of the 20-50 year event.  There were 6 fatalities in southern Sweden, some building damage, power cuts, and forest damage.  Storm Franz on 12 January 2007 caused the highest surge in the southern North Sea for January.  However, its flooding impact was reduced because the monthly cycle of spring and neap tides was near a minimum.  By contrast, astronomical tides were highest near the end of the period on 20-22 January 2007.  The highest absolute water levels for the month for many tide gauge stations were registered during Storm Kyrill on 18 January 2007 and also during Storm Lancelot on 20 January 2007.  This contribution takes a closer look at the North Sea surge of two important storms of the period: Storm Franz and Storm Kyrill.  An analysis is presented of tide gauge data to elucidate the storm surge and wave field around the North Sea and to assess possible links with shipping accidents and offshore incidents.  An unusually large wave sequence had been registered at the FINO1 offshore wind energy research platform only a couple of months previously on 1 November 2006.  The water level data is analyzed to ascertain if there may have been a repeat of the wave event during the storm sequence on 8-22 January 2007.

How to cite: Kettle, A.: Kyrill, Franz, and the Societal Impacts of the Storms of January 2007, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2287, https://doi.org/10.5194/egusphere-egu22-2287, 2022.

EGU22-2373 | Presentations | ERE2.1

Wind farm effects on weather forecast using the operational model HARMONIE-AROME 

Jana Fischereit, Bjarke Tobias Olsen, Marc Imberger, Henrik Vedel, Xiaoli Guo Larsén, Andrea Hahmann, Gregor Giebel, and Eigil Kaas

Wind farms extract kinetic energy from the flow to generate electricity. Thereby, they modify the wind and turbulence fields upwind, at the side and especially downwind of the farm. Due to the induced enhanced mixing, other meteorological variables such as temperature and humidity are also affected by the presence of wind farms. With the massive growth of installed capacity both on- and offshore, these wind farm effects play an increasing role in numerical weather forecasts. This study will investigate the impact of currently installed wind farms in Europe on the weather forecast accuracy.

We performed forecasts for central and northern Europe with and without wind farm parameterizations. We used the operational mesoscale model HARMONIE-AROME equipped with the wind farm parameterization (WFP) by Fitch et al. (2012) as implemented by van Stratum et al. (2021). We added another WFP, the explicit wake parameterization (EWP, Volker et al. 2015). We created a European wind turbine data set by combining different data sets and using a machine learning gap-filling approach. This data set includes turbine locations and their characteristics. Different scenarios were tested using this data set: (A) including only offshore turbines in the German Bight and surrounding Denmark, (B) including all on- and offshore turbines present in the European wind turbine data set.

The simulation results from HARMONIE-AROME indicate that wind farms affect near-surface wind speed, temperature and humidity. The magnitude of these differences decreases with increasing distance from the farm, but still amounts to ±0.5 m/s in 10-m-wind or ±0.25 K in 2-m-temperature at a non-negliable number of locations in Denmark for an investigated exemplary summer day compared to the scenario without wind farms. The impact of onshore turbines is generally smaller than that of offshore turbines. However, the response to scenarios (A) and (B) differ, indicating that it is necessary to include both on- and offshore turbines to capture the full effect of wind farms in Europe. The wind farm effect also depends on the chosen wind farm parameterization, and both schemes provide plausible results. Future studies are necessary to better evaluate the two parameterizations and derive possible fine-tuning or combinations of the schemes. Overall, an ensemble consisting of both wind farm parameterizations could give a more reliable forecast in the future.

 

A. C. Fitch, J. B. Olson, J. K. Lundquist, J. Dudhia, A. K. Gupta, J. Michalakes, and I. Barstad. Local and Mesoscale Impacts of Wind Farms as Parameterized in a Mesoscale NWP Model. Mon Weather Rev, 140(9):3017–3038, sep 2012. ISSN 00270644. doi:10.1175/MWR-D-11-00352.1

B. van Stratum, N. E. Theeuwes, J. Barkmeijer, B. van Ulft, and I. Wijnant. A year-long evaluation of a wind-farm parameterisation in HARMONIE-AROME. Earth and Space Science Open Archive, page 29, 2021. doi: 10.1002/essoar.10509415.1. URL doi:10.1002/essoar.10509415.1

P. J. H. Volker, J. Badger, A. N. Hahmann, and S. Ott. The Explicit Wake Parametrisation V1.0: a wind farm parametrisation in the mesoscale model WRF. Geoscientific Model Development, 8(11):3715–3731, 2015. ISSN 1991-959X. doi:10.5194/gmd-8-3715-2015.

How to cite: Fischereit, J., Olsen, B. T., Imberger, M., Vedel, H., Guo Larsén, X., Hahmann, A., Giebel, G., and Kaas, E.: Wind farm effects on weather forecast using the operational model HARMONIE-AROME, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2373, https://doi.org/10.5194/egusphere-egu22-2373, 2022.

EGU22-2602 | Presentations | ERE2.1

Influence of offshore wind farms on the latent heat flux in the marine boundary layer 

Andreas Platis, Yann Büchau, and Jens Bange

Unique airborne in-situ measurements were evaluated to investigate the influence of offshore wind farms on the latent heat flux in the marine boundary layer. 21 of the total 42 measurement flights carried out in the frame work of the WIPAFF project over the German Bight in the years 2016 and 2017  enabled such an evaluation under different atmospheric conditions. The measurements of 15 flights showed a significant increase of the vertical upward latent heat flux over the offshore wind farm clusters Amrumbank West, Nordsee Ost, Meerwind Süd/Ost or the wind farm Godewind. Under thermally stable conditions, all except one of the measurement flights showed an increase of latent heat flux over or in the wake of the wind farms, with an heat flux up to 17 times higher compared to the undisturbed flow. During flights under unstable thermal stratification, the phenomenon was observed in 8 out of 13 cases. The results also suggest that not only thermal stratification but also moisture stratification plays a decisive role in whether the influence of the wind farm becomes noticeable in the latent heat flux.  Considering the absolute amount of the increase of the upward latent heat flux, a maximum increase of +400 W/m² was measured in unstable conditions. 

How to cite: Platis, A., Büchau, Y., and Bange, J.: Influence of offshore wind farms on the latent heat flux in the marine boundary layer, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2602, https://doi.org/10.5194/egusphere-egu22-2602, 2022.

EGU22-2875 | Presentations | ERE2.1

Forecasting day-ahead 1-minute irradiance variability from NWP output 

Frank Kreuwel and Chiel van Heerwaarden

Forecasting day-ahead 1-minute irradiance variability from NWP output

 

Accurate forecasts of solar irradiance are required for the large scale integration of solar photovoltaic (PV) systems. Fluctuations of energy generation in the order of minutes can lead to issues on the electricity grid, therefore accurate forecasts of minute-to-minute irradiance variability are required. However, state of the art numerical weather predictions (NWP) deliver forecasts at a much coarser temporal resolution, e.g. hourly averages.

In this work we present a methodology to forecast a quantification of minute-to-minute irradiance variability as well as the probability distribution function (pdf), by applying statistical postprocessing and machine learning on hourly NWP ourput. In total, 10 target parameters related to the irradiance variability are forecasted. The algorithm is tested using the NWP HARMONIE-AROME (HA) mesoscale model as input, with 1-minute irradiance observations for 18 locations throughout the Netherlands used as ground truth.

Results show that the proposed algorithm is capable of forecasting the 1-minute irradiance PDF with reasonable resemblence to the observed PDF. Moreover, we show that inaccuracies of the postprocessed result are to a large extent due toerrors in the radiation forecast of the NWP used as input, reducing the average R2 score from 0.75 to .57 for the most relevant targets. The generalizability of the proposed algorithm is demonstrated by training the model on data of a single site and testing the performance on all 18 sites. Surprisingly, we find for 14 sites the model achieves higher accuracy than at the site it was trained on. Including data of all sites in the train set improves the accuracy on 3 of the 6 relevant target parameters while decreasing the accuracy on 1. Finally, we compare this work on post-processing to the next generation weather models based on high resolution Large Eddy Simulation (LES). A case study spanning four days is performed on four days well-captured by the NWP model and results are compared to results from the post-processing algorithm. While LES underestimates values of high irradiance due to lack of 3D radiative effects, it enables detailed analysis of the dynamics at high spatial and temporal resolution unreachable by statistical postprocessing.

The algorithm presented in this work is able to predict intra-hour irradiance variability based on day-ahead NWP output. Thereby moving forward significantly towards improving grid operation, planning, and resilience in relation to large-scale solar PV generation.

How to cite: Kreuwel, F. and van Heerwaarden, C.: Forecasting day-ahead 1-minute irradiance variability from NWP output, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2875, https://doi.org/10.5194/egusphere-egu22-2875, 2022.

EGU22-3177 | Presentations | ERE2.1

Assessment of nocturnal low-level jets and their implication for wind power from FESST@home measurements 

Eduardo Weide Luiz and Stephanie Fiedler

Nocturnal Low-Level Jets (NLLJ) are maxima in vertical profiles of the horizontal wind speed in the lowest hundreds of meters of the troposphere. NLLJs therefore influence the winds at typical rotor heights. However, due to rare measurements with a sufficient precision and resolution, the occurrence frequency and spatio-temporal characteristics of NLLJs on the mesoscale are still poorly understood. The present work uses new measurements of wind profiles for June to August 2020 from Doppler wind lidars that were installed as a part of the Field Experiment on Submesoscale Spatio-Temporal Variability (FESTVaL) campaign, in Lindenberg and Falkenberg (Germany), at about 6 km of distance from each other. The aim of our NLLJ assessment is to characterize their mesoscale properties and evaluate their potential impacts on wind power production. The vertical profiles of the 10-minute mean winds from the lidar measurements were statistically analysed using automated detection tools for NLLJs. These allowed the determination of the frequency of occurrence, height and wind speed in the core of NLLJs as well as the vertical wind shear with a high temporal resolution. First, we intercompared the results from the two sites in order to analyse the temporal and spatial variability of NLLJs on the mesoscale. Our automatic detection identified NLLJs in about 64% to 74% of the summer nights in 2020, showing that they were a common phenomenon during that summer. About half of the NLLJ events were longer than 3 hours, with Lindenberg having more often shorter events of less than 1 hour. If very long NLLJ events (> 6 hours) occurred, they typically affected both places simultaneously, an indicative of their mesoscale character. Our results further suggest that very long NLLJ events are generated by the classical inertial oscillations, influenced by a large-scale horizontal pressure gradient and intermittent turbulent mixing, while shorter NLLJ events are more strongly dependent on local conditions or are driven by shorter-living density currents. Regarding their potential impact on wind turbines, we simulated wind power production for two different turbine types of different height and capacity. Both simulations indicate that NLLJs clearly increase the power production compared to nights without NLLJs. The quantitative NLLJ impacts on power production strongly depend on the height of the wind turbines: during NLLJ events the average wind production was 80% higher for a hub height of 135 m and only 53% higher for 94 m. At the same time, NLLJs increased the wind shear across the rotor layer. Extreme shear in the rotor layer was often associated with NLLJs, with 37% of all NLLJs leading to extreme shear and 48% of all extreme shear cases being caused by NLLJs. We infer from our assessment that particularly long NLLJ events strong influence wind power production, while shorter NLLJs can increase the temporal and spatial variability in power production, causing power ramps.

How to cite: Weide Luiz, E. and Fiedler, S.: Assessment of nocturnal low-level jets and their implication for wind power from FESST@home measurements, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3177, https://doi.org/10.5194/egusphere-egu22-3177, 2022.

EGU22-3641 | Presentations | ERE2.1

Deep learning for improved bias correction of satellite-derived SIS maps 

Alberto Carpentieri, Martin Wild, Doris Folini, and Angela Meyer

Accurate maps of surface incoming solar (SIS) radiation are a crucial prerequisite for producing precise solar radiation and photovoltaic power (PV) nowcasts useful to utility companies, grid operators and energy traders. 

We present a new bias correction approach for satellite-retrieved SIS measurements using deep neural networks with time encoding features, achieving significantly reduced biases on high time resolution data. Moreover, we demonstrate the necessity and the benefits of automated bias correction prior to performing surface radiation and PV nowcasts.

We make use of SIS retrieved from the SEVIRI spectrometer onboard the geostationary Meteosat MSG satellite with the HelioMont (Stöckli, 2013) and HelioSat (Müller et al., 2015) algorithms by the CM SAF team. HelioMont comes at a spatial resolution of 0.02x0.02 degrees, while HelioSat provides a resolution of 0.05x0.05 degrees. For the bias correction, we employ high-quality long-term pyranometer measurements from 113 ground stations of one of the densest meteorological networks around the world, the SwissMetNet.  The SIS radiations are retrieved at 30-minutes, 15-minutes and 10-minutes resolutions (HelioSat, HelioMont, and SwissMetNet, respectively) for the entire year 2018. We use 46 weeks as training set and 6 weeks as test set, wherein the latter consists of the 3 sunniest and 3 cloudiest weeks of 2018.

Our approach involves a multilayer perceptron (MLP) trained to correct the satellite SIS bias by exploiting the predictor variables (time encoding, location features and satellite SIS) and fitting them to predict the ground station SIS. By doing so, we demonstrate that our novel bias correction method can reduce the SIS mean absolute bias (MAB) of both HelioMont and HelioSat by more than 10%. Comparing our results with a standard linear regression (LR) model, we find that the MLP outperforms the LR approach on 112 and 111 SwissMetNet stations for HelioMont and HelioSat, respectively. 

Moreover, we found that the bias magnitude is significantly correlated with the altitude of the considered location and with the time of year. The biases are largest in mountainous regions that tend to have a higher albedo due snow and ice. In fact, the Pearson correlation between the altitude and the average MAB is 0.76 and 0.80 for HelioMont and HelioSat, respectively.

 

References

  • R. Stöckli (2013). The HelioMont Surface Solar Radiation Processing. Scientific Report 93, MeteoSwiss, 122 pp.
  • Müller, R., U. Pfeifroth, C. Träger-Chatterjee, J. Trentmann, and R. Cremer (2015), Digging the METEOSAT Treasure-3 Decades of Solar Surface Radiation, Remote Sensing, 7(6), 8067-8101, doi:10.3390/rs70608067.

How to cite: Carpentieri, A., Wild, M., Folini, D., and Meyer, A.: Deep learning for improved bias correction of satellite-derived SIS maps, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3641, https://doi.org/10.5194/egusphere-egu22-3641, 2022.

EGU22-4572 | Presentations | ERE2.1

Full-scale turbulence structure of wind and applications 

Xiaoli Larsén, Søren Larsen, Erik Petersen, and Torben Mikkelsen

As today’s wind farm clusters can be as large as thousands of kilometers squared and individual turbines hundreds of meters tall, we are challenged when applying classical wind and turbulence models for corresponding wind energy-related calculations.  Typical boundary-layer turbulence models are applicable to time scales smaller than ~1 h, or as denoted by Högström et al. (2002) the Kolmogoroff inertial subrange, the shear production range, and for ranges within the spectral gap region. 

This study revisits some key characteristics of the atmospheric boundary-layer turbulence, covering frequencies from 1/year, over the energy-containing range, to synoptic- and mesoscales, to the gap region and to the 3D turbulence range. This study aims at investigating the following fundamental questions: How to characterize the full-scale spectral behaviors and what are the mechanisms behind them? To which extent is the condition of stationarity fulfilled? What are the 2D-isotropy characteristics? How are numerical modeling abilities in capturing these characteristics? We also show how these findings have been used in wind energy applications, e.g. for generating time series of wind speed including meso-scale variability, for investigating meandering, for extreme wind calculation and for improving turbulence intensity calculation in the presence of organized atmospheric phenomena.

The study includes literatures as well as a series of our studies in recent years (e.g. Larsén et al. 2013, 2016, 2019, 2021).  We combined measurements and modeling in the analysis. The primary datasets are from several met stations over Denmark and the North Sea region, including both 10-min and sonic measurements from about 10 m up to 240 m. The investigations include both statistical and numerical modeling.

 

References:

Högström U, Hunt J, Smedman AS (2002) Theory and measurements for turbulence spectra and variances in the atmospheric neutral surface layer. Boundary-Layer Meteorol 103:101–124

Larsén, X. G., Larsen, S. E., Petersen, E. L., & Mikkelsen, T. K. (2021). A Model for the Spectrum of the Lateral Velocity Component from Mesoscale to Microscale and Its Application to Wind-Direction Variation. Boundary-Layer Meteorology, 178, 415-434. https://doi.org/10.1007/s10546-020-00575-0

Larsén X., Larsen S., Petersen E. and Mikkelsen T. 2019: Turbulence Characteristics of Wind-Speed Fluctuations in the Presence of Open Cells: A Case Study. Boundary-Layer Meteorology, https://doi.org/10.1007/s10546-019-00425-8, (171), 191 – 212.

Larsén X. Larsen S. and Petersen E. (2016): Full-scale spectrum of the boundary layer wind. Boundary-Layer Meteorology, Vol 159, p 349-371

Larsén X., Vincent C. and Larsen S.E. (2013): Spectral structure of mesoscale winds over the water, Q. J. R. Meteorol. Soc., DOI:10.1002/qj.2003, 139, 685-700.  

 

How to cite: Larsén, X., Larsen, S., Petersen, E., and Mikkelsen, T.: Full-scale turbulence structure of wind and applications, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4572, https://doi.org/10.5194/egusphere-egu22-4572, 2022.

EGU22-5232 | Presentations | ERE2.1

Evaluation of the assumptions used in the assessment of future wind resources - A case for CMIP6 in Northern Europe 

Andrea N. Hahmann, Alfredo Peña, Oscar García-Santiago, and Sara C. Pryor

In 2020, the North Sea already had 19.8 GW or 79% of the European offshore wind installations. The size and number of wind farms in this region are expected to increase substantially to reach climate mitigation targets, with forecasts of offshore wind commitments across Europe adding up to 111 GW of offshore wind by 2030. However, governments base their climate mitigation plans on past historical wind resources data. Still, there is a probable threat that these will change in the future due to climate change during the lifetime of a wind farm. 

The study of future changes in wind resources is not a new subject. A systematic literature search with the keywords "Wind Resources" and "Climate Change" returned over 80 peer-reviewed articles that assessed future wind resources at the global, regional and local scale. Most of these studies used the 10-m wind speed output from the climate or regional model to directly estimate a wind turbine's power production, using the power law and sometimes an idealised power curve. As far as we know, only two studies explored the possible implications of changes in wind direction. 

In this presentation, we explore the implications of the various assumptions. We use the example of the North Sea and Northern Europe and the CMIP6 climate model archive to demonstrate that some assumptions can exaggerate future wind resource changes. We also consider the consequences of the changes in boundary layer stability, wind direction and vegetation changes to the future wind resources in Northern Europe. 

How to cite: Hahmann, A. N., Peña, A., García-Santiago, O., and Pryor, S. C.: Evaluation of the assumptions used in the assessment of future wind resources - A case for CMIP6 in Northern Europe, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5232, https://doi.org/10.5194/egusphere-egu22-5232, 2022.

EGU22-5888 | Presentations | ERE2.1

Inter-comparison of PV power simulations from seven gridded irradiance data sets 

Darragh Kenny and Stephanie Fiedler

Accurate irradiance data is necessary for model estimates of expected photovoltaic (PV) power production. Such data is freely available from reanalysis and satellite products with a high temporal and spatial resolution, including locations without ground-based measurements. Gridded irradiance data is therefore used for the characterization of solar resources at specific locations and larger areas, e.g. by power system modellers. Past assessments of irradiance data for PV modelling often relied on the evaluation of global horizontal irradiance (QGHI). However, the direct and diffuse irradiance components as well as differences in seasonal characteristics can strongly affect the PV capacity factors (C) potentially leading to larger biases in C than for QGHI. We therefore systematically assess differences in QGHI, direct and diffuse horizontal irradiance (Qdir  and Qdif) and quantify the subsequent bias propagation from individual radiation components to C in a contemporary PV power model. Our PV model simulations use seven different gridded irradiance data sets, namely ERA5, COSMO-REA6, COSMO-REA6pp, COSMO-REA2, CAMS radiation service, SARAH-2 and CERES Syn1Deg. All data sets provide Qdir and Qdif as separate time series spanning seven to 43 years and with a temporal resolution of 15 minutes to one hour. The results are compared against seven years of simulations based on reference measurements from 30 weather stations of the German Weather Service. We compute metrics characterizing biases in seasonal and annual spatial means, day-to-day variability and extremes in C, considering single stations and a simulated PV fleet. Our results highlight biases of -1.4 % (COSMO-REA6) to +8.2 % (ERA5) in annual and spatial means of C at single stations across Germany, while the bias in QGHI is -3 % for COSMO-REA6 to +3.6 % for ERA5. We also show the bias on days of very low PV production, relevant for extreme event analysis: The days within the lowest ten percent of daily PV production in a PV fleet show a bias of +70.2 % in ERA5, while it is only +4 % in the post-processed COSMO-REA6 data (COSMO-REA6pp). SARAH-2 and COSMO-REA6pp outperform the other products for many metrics, but also cause some biases in C. For instance, SARAH-2 yields good results in summer, but overestimates C in winter by 16 % averaged across all stations. COSMO-REA6pp represents day-to-day variability in C of a simulated PV fleet very well and has a relatively small bias of +0.5 % in the annual spatial means, but this is partly due to compensating biases from individual stations. Our results suggest that gridded irradiance data should be used with caution for site assessments and should ideally be complemented by local measurements. For power system modellers, our results may provide guidance for the quantification of uncertainties caused by gridded irradiance data.

 

Reference:

Kenny, D., and Fiedler, S., in press, Which gridded irradiance data is best for modelling photovoltaic power production in Germany?, Solar Energy.

How to cite: Kenny, D. and Fiedler, S.: Inter-comparison of PV power simulations from seven gridded irradiance data sets, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5888, https://doi.org/10.5194/egusphere-egu22-5888, 2022.

EGU22-6339 | Presentations | ERE2.1

Convection-permitting ICON-LAM simulations as input to evaluate renewable energy potentials over southern Africa 

Shuying Chen, Stefan Poll, Heidi Heinrichs, Harrie-Jan Hendricks-Franssen, and Klaus Görgen

The largest part of the global population without reliable access to electricity lives in Africa. Here, renewable energy is a sustainable, cost efficient, and climate-friendly solution, especially given the large untapped renewable energy potential existing over the African continent. However, most renewable energy-related studies over Africa typically use input datasets at relatively coarse spatial resolutions (e.g., ERA5 at about 30km). Our objective is to produce a prototypical high-resolution dataset over southern Africa from dedicated atmospheric simulations. The data will be used with renewable energy assessment models, to eventually evaluate the renewables potentials. The hypothesis is that the high-resolution datasets provide more realistic and accurate renewable energy potential estimates. The ICOsahedral Nonhydrostatic (ICON) Numerical Weather Prediction (ICON-NWP) model is run as the operational forecast model at the German Weather Service (DWD); and we employ the same model in its Limited Area Mode (ICON-LAM) in this project. The study domain over southern Africa is chosen due to its high solar and wind energy potential. ICON-LAM dynamically downscales the global deterministic ICON-NWP forecasts dataset from a spatial grid spacing of 13km to a convection-permitting resolution of 3.3km, without convection parameterization. This southern Africa ICON-LAM implementation is novel and has not been run before. Simulations cover the time span from 2017 to 2019 with contrasting meteorological conditions. The high-resolution triangulated grid cells of the 3.3km domain are exactly inscribed in the 13km global grid cells, following the sub-triangle generation rule of the ICON model mesh. To keep the ICON-LAM close to the observed atmospheric state the model atmosphere is reinitialized every 5 days, with one day spinup. The land surface and subsurface are run transient. In a very initial evaluation step, simulated 10m wind speed, global solar radiation, 2m air temperature, and precipitation from the coarser driving model, the ERA5 reanalysis as well as our ICON-LAM setup are validated using satellite data and in situ observations from the two local meteorological networks (SASSCAL and TAHMO). Initial results point to an added value of the convection-permitting simulations.

How to cite: Chen, S., Poll, S., Heinrichs, H., Hendricks-Franssen, H.-J., and Görgen, K.: Convection-permitting ICON-LAM simulations as input to evaluate renewable energy potentials over southern Africa, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6339, https://doi.org/10.5194/egusphere-egu22-6339, 2022.

EGU22-6831 | Presentations | ERE2.1

Variability of the Surface Solar Radiation over Reunion island and its interaction with the synoptic, intraseasonal and interannual convective variability 

Chao Tang, Pauline Mialhe, Benjamin Pohl, Béatrice Morel, Shunya Koseki, Babatunde Abiodun, and Miloud Bessafi

The impacts of large scale climate variabilities on the solar energy resource are widely investigated around the world, however their effects are not yet clear for Mascarene Islands (southwest Indian Ocean, SWIO) and needs to be addressed. In this study, surface solar radiation (SSR) classification and anomalies at the diurnal scale from SARAH-E satellite product over Reunion Island are linked to the large scale climate variabilities in SWIO region. These climate variabilities include Tropical Cyclones (TCs) and the Tropical Temperate Troughs (TTTs) at the synoptic scale, the Madden–Julian Oscillation (MJO) at the intraseasonal scale, and the Indian Ocean Dipole (IOD), the Subtropical Indian Ocean Dipole (SIOD) and the El Niño–Southern Oscillation (ENSO) at the interannual scale.
We identified the variability of SSR at various time scales where both local processes and the large scale convective variabilities play important roles. At the synoptic and intraseasonal timescales, the local variability of SSR over Reunion shows a significant association with TCs, TTTs and the MJO. The sign and amplitude of SSR diurnal anomaly are found to be correlated with the enhanced- / depressed- convective phase and amplitude of these events. The SSR anomaly is strongly altered with the presence of nearby TCs, with a value of up to about 30% of climatology, although at low occurrence; TTTs and MJO have relatively weaker impact, with a value of about 13% and 5% respectively. At the interannual timescale, IOD, SIOD and ENSO have relatively much less importance on local SSR variability. The daily total solar energy density has been calculated for all these variabilities to provide useful information for energy applications. 

How to cite: Tang, C., Mialhe, P., Pohl, B., Morel, B., Koseki, S., Abiodun, B., and Bessafi, M.: Variability of the Surface Solar Radiation over Reunion island and its interaction with the synoptic, intraseasonal and interannual convective variability, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6831, https://doi.org/10.5194/egusphere-egu22-6831, 2022.

EGU22-6872 | Presentations | ERE2.1

Regional-scale day-ahead wind power forecasting using deep learning 

Mathilde Lepetit, Frederik Kurzrock, Pierre Aillaud, Nicolas Sebastien, and Nicolas Schmutz

Historically, electricity was provided by dispatchable sources that are able to adjust to demand variations. Adding an irregular source to the network is a challenge for the grid stability. Especially, wind turbine production varies depending on meteorological conditions. At a regional or country scale, Transmission System Operators (TSOs) are responsible to maintain supply demand equilibrium in their network. In this context, wind power production forecast is one of the tools needed to manage the network. Traditionally, physical models are used to predict power production based on turbine characteristics and numerical weather prediction models. Indeed, wind power production is strongly correlated to wind speed at turbine hub height and other meteorological parameters. One limit of those physical approaches is that they require precise knowledge on turbines characteristics and locations, in particular at a regional scale.

To overpass this limit, a statistical approach such as deep learning can be used but needs to be qualified in terms of performances. In this study, a supervised deep learning model is explored. This model does not require information on turbine location or characteristics but does require historical samples of weather parameters and associated production.

Our work focuses on day-ahead forecasts (horizons 24 to 48 hours) for a German TSO (region-scale). One physical model was selected as a reference and the goal was to combine deep learning and physical predictions to obtain the best possible forecast. Both the physical and the deep learning models use spatiotemporal meteorological inputs from the IFS (ECMWF) and GFS (NCEP) models. A convolutional neural network (CNN) was used to exploit the spatial information of maps of features. A LSTM was added to capture information from the time series evolution. Finally, several deep learning predictions were combined with the physical model prediction using a multi-layer perceptron. With this method, the MAE-based skill score of our final model, combining the physical one and deep learning ones, reaches more than 6% over a validation period of one year.

How to cite: Lepetit, M., Kurzrock, F., Aillaud, P., Sebastien, N., and Schmutz, N.: Regional-scale day-ahead wind power forecasting using deep learning, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6872, https://doi.org/10.5194/egusphere-egu22-6872, 2022.

EGU22-7926 | Presentations | ERE2.1 | Highlight

Forecasting for the Weather Driven Energy System – The New IEA Wind Task 51 

Gregor Giebel, Caroline Draxl, Helmut Frank, John Zack, Jethro Browell, Corinna Möhrlen, George Kariniotakis, and Ricardo Bessa

The last 6 years, the International Energy Agency (IEA) Wind Task 36 “Forecasting for Wind Energy” has provided forecasting stakeholders (weather institutes, forecast service providers, end users and academics) a platform to discuss challenges and benefits of forecasting for wind power. These discussions have led to a number of activities and initiatives to overcome challenges and to broadcast the benefits of forecasting. Among the major outputs are an information portal with links to free data, a collection of use cases for probabilistic forecasts, and the IEA Recommended Practice on Forecast Solution Selection, including 4 chapters dealing with the (1) solution selection process, (2) benchmarks and trials, (3) verification process and  use of online measurements from wind farms for real-time forecasting applications.

 In the future, we will no longer “integrate” wind and solar into existing power systems, but instead are wind and solar going to be the backbone of our power systems.

To address those challenges in an integrated fashion, the IEA Task for Forecasting under the IEA Wind Technology Collaboration Programme (TCP) relaunched with a new Task number (51) and a new work program. The work packages (WPs) are still structured according to stakeholder topics: WP1 deals with weather forecasting, and mainly addresses meteorologists, WP2 deals with the conversion of the weather feeds to the application specific variables such as wind power and addresses forecast vendors, and WP3 deals with the applications and how to get most value out of the forecasts, and therefore addresses the forecast users, including recent advances in data science and digitalisation. However, many of the topics the new Task takes up are cross-cutting, and are therefore now  Work Streams (WS):

  • Atmospheric physics and modelling (lead by WP1)
  • Airborne Wind Energy Systems (WP1)
  • Seasonal forecasting (WP1)
  • State of the Art for energy system forecasting (WP2)
  • Forecasting for underserved areas (WP2)
  • Minute scale forecasting (WP2)
  • Uncertainty / probabilistic forecasting (WP3)
  • Decision making under uncertainty (WP3)
  • Extreme power system events (WP3)
  • Data science and artificial intelligence (WP3)
  • Privacy, data markets and sharing (WP3)
  • Value of forecasting (WP3)
  • Forecasting in the design phase (WP3)

Most of these work streams require collaboration, and therefore have dedicated partners in other IEA Wind Tasks, or in IEA Tasks outside of the Wind TCP. Task 51 will therefore collaborate with IEA Wind Tasks 32, 44, 48 and 50,  IEA PVPS Task 16, IEA Hydro, the IEA Hydrogen TCP, IEA Bioenergy Task 44  and WMO. 

A major activity of Task 51 will be four public workshops in the next four summers, starting with a workshop on the State of the Art and Research Gaps in 2022, on seasonal forecasting with a special emphasis on hydro power and storage in 2023,  on minute scale forecasting in 2024, and on extreme power system events in 2025.  We keep the community updated on events, new publications and other relevant information on our website ieawindforecasting.dk and via LinkedIn and Research gate.

How to cite: Giebel, G., Draxl, C., Frank, H., Zack, J., Browell, J., Möhrlen, C., Kariniotakis, G., and Bessa, R.: Forecasting for the Weather Driven Energy System – The New IEA Wind Task 51, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7926, https://doi.org/10.5194/egusphere-egu22-7926, 2022.

EGU22-8241 | Presentations | ERE2.1

Offshore atmospheric stability estimation from floating lidar wind profiles 

Marcos Paulo Araujo da Silva, Francesc Rocadenbosch, Joan Farré-Guarné, Andreu Salcedo-Bosch, Daniel González-Marco, and Alfredo Peña

In this work, we revisit the 2D parametric-solver algorithm [1] to estimate the Obukhov length, and hence, determine atmospheric stability from floating Doppler wind lidar (FDWL) wind profiles. The algorithm fits the wind-profile model derived from Monin-Obukhov similarity theory to the FDWL-measured wind profile by means of a constrained non-linear least squares optimisation. Observational data were gathered at the IJmuiden test site in the North Sea (52.848 N, 3.436 E) between March and June of 2015. The reference Obukhov length was obtained via bulk Richardson number, which was estimated from IJmuiden-mast observations. Comparisons with the reference stability are performed by using a simplified atmospheric stability classification consisting of only three types, namely stable, neutral and unstable. Fairly similar results were obtained from the 2D-estimated and the mast-derived reference stability classifications for the stability behaviour during the time of day as well as for horizontal-wind-speed dependence on the stability type.

This research is part of the projects PGC2018-094132-B-I00 and MDM-2016-0600 (“CommSensLab” Excellence Unit) funded by Ministerio de Ciencia e Investigación (MCIN)/ Agencia Estatal de Investigación (AEI)/ 10.13039/501100011033/ FEDER “Una manera de hacer Europa”. The work of M.P Araujo da Silva was supported under Grant PRE2018-086054 funded by MCIN/AEI/ 10.13039/501100011033 and FSE “El FSE invierte en tu futuro. The work of A. Salcedo-Bosch was supported under grant 2020 FISDU 00455 funded by Generalitat de Catalunya—AGAUR. The European Commission collaborated under projects H2020 ACTRIS-IMP (GA-871115) and H2020 ATMO-ACCESS (GA-101008004).

[1] M. P. Araujo da Silva, F. Rocadenbosch, J. Farré-Guarné, A. Salcedo-Bosch, D. González-Marco, and A. Peña, “Assessing obukhov length and friction velocity from floating lidar observations: A data screening and sensitivity computation approach,” Remote Sensing, 2022, submitted.

How to cite: Araujo da Silva, M. P., Rocadenbosch, F., Farré-Guarné, J., Salcedo-Bosch, A., González-Marco, D., and Peña, A.: Offshore atmospheric stability estimation from floating lidar wind profiles, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8241, https://doi.org/10.5194/egusphere-egu22-8241, 2022.

EGU22-9393 | Presentations | ERE2.1

Development of a solar energy forecasting system for two real solar plants based on WRF Solar with aerosol input and a solar plant model 

Miguel A. Prósper, Ian Sosa-Tinoco, and Gonzalo Miguez-Macho

Regional meteorological models are becoming a generalized tool for solar energy production forecasting,  due to their capacity to simulate different types of cloud formations and their interaction with solar radiation. The greater demand for reliable forecasting tools in the energy industry is the motivation for the development of an integrated system that combines the Weather Research and Forecasting atmospheric model package designed to fulfill the needs of solar energy applications (WRF-Solar), with the solaR power plant model. This study focuses on the use and validation of this coupled tool in forecasting the energy production for two real solar plants, one in Spain and another in India. A period of one year for the Spanish emplacement and nine months for the Indian site are simulated with a daily operational forecasting set-up. Aerosol data from the Copernicus Atmosphere Monitoring Service (CAMS) are considered in the calculations, a new capability in WRF-Solar. Power predictions are obtained and compared with real data from the inverters of both plants provided by the operating company.

The results show that WRF-Solar obtains accurate forecasts of global, direct, and diffuse radiation and of the ambient temperature that solaR uses as input to predict the energy production of the solar plants. The normalized Mean Annual Errors (NMAE) is 5.18% in the Spanish and 5.59% in the Indian plant for the first day of predictions, demonstrating a reliable performance of the forecasting system in different climate locations. The skill scores for the second day of prediction are also promising, with practically the same errors as the previous day (5.19% and 6.17 for Spain and India respectively). By comparing the model predictions, with and without AOD input during the dustiest days in the Spanish site, the importance of the aerosol effect inclusion is demonstrated with an improvement up to 10% in the energy forecast. These results demonstrate the system’s potential both for solar plant operation and energy market applications.

How to cite: Prósper, M. A., Sosa-Tinoco, I., and Miguez-Macho, G.: Development of a solar energy forecasting system for two real solar plants based on WRF Solar with aerosol input and a solar plant model, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9393, https://doi.org/10.5194/egusphere-egu22-9393, 2022.

With the rapidly increasing use of solar power accurate predictions of the site-specific power production are needed to ensure grid stability, energy trading, (re)scheduling of maintenance, and energy transfer. Particularly in systems relying on many factors such as solar energy, extreme events can be a threat to the power grid stability and accurate nowcasts. Thus, warnings within a reasonable amount of time ahead for preparation are essential. In the MEDEA project, funded by the Austrian Climate Research Program, we aim at improving the definition and detection of extreme events relevant for renewable energies and using these findings to improve both weather and climate predictions of such extreme events.

In the presented case study, we investigate selected (extremes) cases of Sahara dust events in 2021 where various weather prediction models were unable to properly reproduce the amount of aerosols in Central Europe resulting in a discrepancy between actual solar power production compared to predictions being off by more than 5 GW.  Here, several solar production forecasts gave impaired results based on raw NWP model output. To tackle such events and improve the predictability, a deep learning framework including an LSTM (long short-term memory; type of an artificial neural network) and random forest will be adopted for nowcasting with multiple heterogeneous data sources available. Relevant features include 3D-fields from different NWP models (AROME, WRF), satellite data and products (CAMS), point-interpolated radiation time series from remote sensing, and observation time-series (site observations, close meteorological sites). We investigate up to 6 hours ahead nowcasts at several Austrian solar power farms with an update frequency of 15 minutes.

Results obtained by the developed method yield, in general, high forecast-skills, where we elaborate on interesting cases studies from a meteorological point of view. Different combinations of inputs and processing-steps are part of the analysis. We compare obtained forecast results to available forecast methods, e.g., an analogs-based method, pvlib forecasts driven with AROME and AROME RUC. 

How to cite: Papazek, P., Schicker, I., and de Wit, R.: Nowcasting of Solar Power Production by a Deep Learning  Methodology: Improving Forecasts for Solar Energy Sites during Sahara Dust Events using Highly Resoved Historic Time Series, Remote Sensing and Numeric Weather Prediction Models, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9709, https://doi.org/10.5194/egusphere-egu22-9709, 2022.

EGU22-9818 | Presentations | ERE2.1

Influence of the number of lidar sounding heights on Adaptive Unscented Kalman Filtering for Floating Doppler wind-lidar motion correction 

Andreu Salcedo-Bosch, Francesc Rocadenbosch, and Joaquim Sospedra

A study on the floating Doppler wind lidar (FDWL) motion-correction performance by means of the Unscented Kalman Filter (UKF) method as a function of the lidar measurement heights is presented. The study is carried out by simulating one, three, and five lidar measurement heights by means of time-series down-sampling techniques. The performance is tested over experimental data measured by a fixed and a FDWL sited 50 m appart in the context of Pont del Petroli measurement campaign.

The motion-correction UKF [1] relies on FDWL dynamics as formulated by Kelberlau et al. [2] as well as on the lidar internal wind-vector estimation algorithm to recursively estimate the clean (i.e., motion-free) wind vector. To carry out the correction, the filter uses the FDWL-measured wind vector and 6 Degrees of Freedom buoy motion measurements by the Inertial Measurement Units installed on the FDWL buoy.

Continuous-wave focusing DWLs measure the wind at multiple heights sequentially and, therefore, they sound a particular height every n scans (≈1 scan/s), with n the number of measurement heights. When a lidar is configured to measure at multiple heights, this is equivalent to down-sampling the wind-vector time-series by a factor n.

To study the UKF motion-correction performance, the turbulence intensity (TI) measured by the FDWL, with and without correction, were compared (at 10-minute resolution) against the TI measured by the reference fixed DWL considering three measurement-height configurations (emulated as downsampled time-series): single-height sounding, and 3, and 5 sounding heights.

The experimental results showed that the filter successfully takes the sea motion out of the wind speed measurements, hence it virtually removes the apparent turbulence induced by wave motion for all three measurement-height configurations. However, the poorer one-to-one-point correspondence found when increasing measurement height numbers (equivalently, lower sampling rates in the simulation) stated that less wind information was retained in the 10-min time-series. Thus, the coefficient of determination reduced from R2=0.94 (1 height) to 0.81 (5 heights), and the RMSE increased from 0.74 % (1 height) to 1.34 % (5 heights).

Future work plans to validate the quantitative statistical indicators retrieved by the UKF simulator with reference to experimental wind-speed data measured under real conditions.

Acknowledgements

This research was funded by the Spanish Government and EU Regional Development Funds, ARS project PGC2018-094132-B-I00, H2020 ACTRIS-IMP project GA-871115 and H2020 ATMO-ACCESS project GA-101008004. The European Institute of Innovation and Technology (EIT), KIC InnoEnergy project NEPTUNE (call FP7) supported the

measurement campaigns. The Generalitat de Catalunya—AGAUR funded doctoral grant 2020 FISDU 00455 by A. Salcedo-Bosch. CommSensLab-UPC is an Excellence Unit (MDM-2016-0600) funded by the Agencia Estatal de Investigación, Spain.

 

 

References

[1] Andreu Salcedo-Bosch, Francesc Rocadenbosch, and Joaquim Sospedra, “A robust adaptive unscented kalman filter for floating doppler wind-lidar motion correction,” Remote Sens., vol. 13, no. 20, 2021.

[2] Felix Kelberlau, Vegar Neshaug, Lasse Lønseth, Tania Bracchi, and Jakob Mann, “Taking the motion out of floating lidar: Turbulence intensity estimates with a continuous-wave wind lidar,” Remote Sens., vol. 12, no. 5, 2020.

How to cite: Salcedo-Bosch, A., Rocadenbosch, F., and Sospedra, J.: Influence of the number of lidar sounding heights on Adaptive Unscented Kalman Filtering for Floating Doppler wind-lidar motion correction, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9818, https://doi.org/10.5194/egusphere-egu22-9818, 2022.

EGU22-10440 | Presentations | ERE2.1

Long term wind speed and wind power change analysis over South Greenland using the regional climate model MAR. 

Clara Lambin, Xavier Fettweis, Damien Ernst, and Christoph Kittel

Fighting global warming implies replacing fossil fuels by renewable energy sources. Wind has the benefit to be an easily accessible and infinitely renewable resource but is not evenly distributed in space and time. A solution to prevent energy scarcity in a decarbonised world would be the building of a global interconnected grid that provide populated regions with electricity generated in remote but resourceful areas. In this context, it has appeared in previous studies that Greenland and Europe have complementary wind regimes. In particular, the southern tip of Greenland, Cape Farewell, has gained increasing interest for wind farm development as it is one of the windiest places on Earth. In order to gain new insights about future wind speed variations over South Greenland, the Modèle Atmosphérique Régional (MAR), validated against in situ observations over the ice-free area where wind turbines are most likely to be installed, is used to built climate projections under the emission scenario SSP 5-8.5 by downscaling an ensemble of CMIP6 earth system models (ESMs). These projections enable to assess the long term wind speed and maximum wind power change between 1981 and 2100 over Cape Farewell, quantified with the help of a linear regression. It appears from this analysis that, during this period over the ice-free area, the annual wind speed is expected to decrease of ~-0.8 m/s at 100m a.g.l. This decrease is particularly marked in winter while in summer, wind speed acceleration occurs along the ice sheet margins. An analysis of two-dimensional wind speed change at different vertical levels indicates that this decrease is likely due to synoptic circulation change, while in summer, the katabatic winds gowing down the ice sheet are expected to increase due to an enhaced temperature contrast between the ice sheet and the surroundings. As for the mean annual maximum wind power a turbine can yield, a decrease of ~-300.5 W is to be expected over the ice-free area of Cape Farewell between 1981 and 2100 at 100m a.g.l. Again, the decrease is especially marked in winter. Considering the very high winter wind speeds occuring in South Greenland which can cut off wind turbines if too intense, the projected wind speed decrease might be beneficial for the establishment of wind farms near Cape Farewell.

How to cite: Lambin, C., Fettweis, X., Ernst, D., and Kittel, C.: Long term wind speed and wind power change analysis over South Greenland using the regional climate model MAR., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10440, https://doi.org/10.5194/egusphere-egu22-10440, 2022.

EGU22-10583 | Presentations | ERE2.1

Transfer of small scales space-time fluctuations of wind fields to wind turbines torque computation 

Ángel García Gago, Auguste Gires, Paul Veers, Daniel Schertzer, and Ioulia Tchiguirinskaia

Wind fields are known to be extremely variable in space and time over a wide range of scales. Universal Multifractals (UM) are a common tool used to model and simulate such features. This parsimonious framework is based only on 3 parameters (α , C1 and H) with physical interpretation, while the 4th, the power a of a conservative flux, is absorbed by the empirical estimation of the mean singularity over a non-conservative field. Obviously, in the context of wind power production, these properties are transferred to wind turbine torque and ultimately power.

Here, we investigate this transfer through modelling of wind turbine torque. For this purpose, 2 different modelling chains have been developed. The first one takes into account the spatial distribution of the wind velocities and the rotation of the blade considering an integral torque along the blades, this is in contrast with traditional approach which uses the average wind speed at hub height and blade radius to compute the torque. The second one is based on TurbSim for wind input computation, and OpenFAST for torque computation, which are tools developed by National Renewable Energy Laboratory (NREL). The main challenge is to input a space-time varying wind because, although it is possible to know the wind data at isolated points, where high resolution anemometers can be located, obtaining the wind speed in all points over a given area is rather complex. Using uniform wind fields in space creates too strong artificial correlations.

In this work, we suggest the reconstruction of wind fields from a point measurement by relying on well established scaling laws. More precisely, the wind field at any location is obtained by adding to the data at the available anemometer point, the product of a prefactor, a random UM field and distance increment raised to power av and Hv respectively. The exponents are obtained in the literature using purely dimensional arguments. Data from 2 high resolution 3D sonic anemometers located on a meteorological mast in a wind farm situated approximately 110 km south-east of Paris, with approx. 33 m vertical distance, are used to tune parameters of UM field and the prefactor according to the event. Data is collected in the framework of the RW-Turb measurement campaign (https://hmco.enpc.fr/portfolio-archive/rw-turb/); which is supported by the French National Research Agency (ANR-19-CE05-0022)

UM analysis over numerous events (more than 1-year data is available) was carried out to confirm good agreement between UM parameters retrieved on anemometer data and simulation data. A comparison between torque obtained with the traditional approach and both modelling chains using simulated fields and UM analysis of the outputs was also performed to observe the differences focusing on the small scales.

How to cite: García Gago, Á., Gires, A., Veers, P., Schertzer, D., and Tchiguirinskaia, I.: Transfer of small scales space-time fluctuations of wind fields to wind turbines torque computation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10583, https://doi.org/10.5194/egusphere-egu22-10583, 2022.

In the coming decades, the European energy system will undergo major transformations, like widespread electrification and fast development of variable renewable energy, in order to reach carbon neutrality and comply with the Paris Agreement. As a consequence, energy production will increasingly depend on weather variability, and the future European energy system needs to be designed to cushion this variability, at all time scales. In particular, rare events leading to extreme fluctuations in energy production or demand can be expected to play a major part in this design. For instance, one of the main challenging events is a combination of low renewable energy production with high demand for a long time period. To know how much flexibility will be needed (seasonal storage such as green gas reserves, number of auxiliary thermal power plants, needs in terms of demand-side management, etc.) and assess its cost, one needs to estimate the probability of occurrence of such events. However, observations of renewable energy production or climate variables are too short to quantitatively study these critical events. Therefore we need to rely on climate and energy models, and to develop dedicated tools to study extreme events of energy production and demand.

Here, we study the extreme imbalance between renewable generation and demand in Europe, at the sub-seasonal to seasonal scale. Based on a state-of-the-art climate model (CESM1.2.2) with extremely long simulations, we couple models of wind, solar PV, and demand with climate variables to obtain very long time series of energy production and demand. We consider 9 scenarios of renewable installed capacities to assess the probability of occurrence of extreme residual loads (demand minus renewable production). We study the statistics of extremely rare events that last for several weeks to several months.

The results show that extremely high residual loads are dominated by extremely low wind energy production events in winter, that are not visible in historical data. Leveraging our very long time series, we compute return time curves for extreme wind energy fluctuations. These curves tell us how frequent energy shortfalls of a given amplitude are. We find a renormalization such that return time curves depend weakly on the scenario. The estimation of such return times relies crucially on the available amount of data. We show that good approximations can be obtained from simple stochastic processes. 

How to cite: Cozian, B., Bouchet, F., and Herbert, C.: Assessing the probability of extremely rare renewable production and residual load in Europe at sub-seasonal to seasonal time scales, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11781, https://doi.org/10.5194/egusphere-egu22-11781, 2022.

EGU22-11858 | Presentations | ERE2.1

An unmanned aircraft system for (offshore) wind energy research 

Ines Weber, Andreas Platis, Kjell zum Berge, Martin Schön, Jakob Boventer, Bughsin Djath, Johannes Schulz-Stellenfleth, and Jens Bange

The Multipurpose Airborne Sensor Carrier (MASC) is a fixed-wing unmanned aircraft system (UAS) that has been continuously developed and used for in-situ, high-resolution flight measurements of atmospheric variables such as wind, temperature, humidity as well as trace gas and particle concentrations by the Environmental Physics group at University of Tübingen. The most recent innovation in the MASC-series is the MASC-V type vertical takeoff and landing UAS. It has been designed in cooperation with ElevonX d.o.o.. Compared to its predecessor, MASC-3, it can automatically takeoff and land on small patches of land while carrying an identical atmospheric measurement payload. This capability, complemented by an enhanced safety and operational concept, allows for deployment in offshore applications. Particularily, MASC-V has demonstrated safe operation beyond visual line of sight (BVLOS) from the remote safety pilot in offshore applications within the EUs new legal framework introduced in 2020.

Before its first offshore mission, MASC-V underwent a full system validation against a meteorological tower at the German Weather Service (DWD) Observatory site at Falkenberg, Germany. Offshore measurements were conducted from the German offshore island Heligoland at the Testfield for Maritime Technologies in cooperation with the Fraunhofer Institute for Applied Material Science in September 2021. The goal of the Heligoland campaign was to validate the remote sensing of sea surface wind measurements by Synthetic Aperture Radar (SAR) satellites of the Sentinel-1 formation at low flight altitudes (20 m - 30 m). SAR satellites can deliver detailed wind data over large areas such as the German Bight including for example wind farm wake effects. Direct validation of these results is difficult with other in-situ techniques. Buoys and measurement towers or platforms can provide stationary data. Aerial measurements with manned aircraft are only possible at higher altitudes. The new UAS data provide the first aerial in-situ SAR validation measurement at low altitude. Additionally, we have demonstrated the capabilities of VTOL fixed-wing UAS for vertical profiling as well as to operate tens of kilometers away from ground personell over open water.

How to cite: Weber, I., Platis, A., zum Berge, K., Schön, M., Boventer, J., Djath, B., Schulz-Stellenfleth, J., and Bange, J.: An unmanned aircraft system for (offshore) wind energy research, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11858, https://doi.org/10.5194/egusphere-egu22-11858, 2022.

EGU22-12664 | Presentations | ERE2.1

Experimental Validation of Numerical Simulation of Tidal Power Plants (Deep Green) using ADCP Measurements 

Nimal Sudhan Saravana Prabahar, Sam Fredriksson, Göran Broström, and Björn Bergqvist

Tidal turbines harnessing power from tidal currents, have the prospective to become an important source for renewable energy production. The tidal power plant studied here, the Deep Green, rather than being fixed like conventional horizontally mounted axial tidal turbines, uses a ‘flying’ kite with a turbine attached to it. The kite, which is tethered to the bottom, converses in a lemniscate trajectory (Ꝏ) perpendicular to the direction of the tidal current. In the trajectory, the apparent flow velocity experienced by the turbine is several times the tidal flow, thereby allowing utilization of sites with lower tidal current velocities than most traditional tidal power plants. To study the operation of single power plants and for designing efficient arrays of tidal power plants Computational Fluid Dynamics (CFD) are used.

Through previous studies, the Deep Green is modelled using Large Eddy Simulations (LES) and the Actuator Line Model (ALM). While using ALM, the Deep Green wing and its turbine are represented as a momentum source that moves in a prescribed trajectory (lemniscate). Using the numerical simulations, the impact of the Deep Green on the tidal flow is studied by analysing the changed velocity field and turbulence characteristics downstream of the power plant. Before conducting large-scale numerical studies on the design of arrays, the numerical model needs to be validated against observations.

The measurements used for this study were performed by Minesto AB in the site Holyhead deep using a vessel mounted ADCP (Acoustic Doppler Current Profiler) downstream of the kite. A domain and boundary conditions similar to the measurements are set up in the numerical simulation. The velocity downstream of the power plant is compared with the measured velocity data, and the preliminary study shows good agreement between ADCP observations and output from the CFD model. The results of the validation will be helpful to strengthen the methods used in numerical modelling in order to conduct sound tidal power array analysis.

How to cite: Saravana Prabahar, N. S., Fredriksson, S., Broström, G., and Bergqvist, B.: Experimental Validation of Numerical Simulation of Tidal Power Plants (Deep Green) using ADCP Measurements, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12664, https://doi.org/10.5194/egusphere-egu22-12664, 2022.

EGU22-12923 | Presentations | ERE2.1

Highlight results of the Smart4RES project on weather modelling and forecasting dedicated to renewable energy applications 

Georges Kariniotakis and Simon Camal and the Smart4RES team

In this presentation we detail highlight results obtained from the research work within the European Horizon 2020 project Smart4RES (http://www.smart4res.eu). The project, which started in 2019 and runs until 2023, aims at a better modelling and forecasting of weather variables necessary to optimise the integration of weather-dependent renewable energy (RES) production (i.e. wind, solar, run-of-the-river hydro) into power systems and electricity markets. Smart4RES gathers experts from several disciplines, from meteorology and renewable generation to market- and grid-integration. It aims to contribute to the pathway towards energy systems with very high RES penetrations by 2030 and beyond, through thematic objectives including:

  • Improvement of weather and RES forecasting,
  • Streamlined extraction of optimal value through new forecasting products, data market places, and novel business models;
  • 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). 

In this presentation we will focus on our results on models that permit to improve forecasting of weather variables with focus on extreme situations and also through innovative measuring settings (i.e. a network of sky cameras). Also results will be presented on the development of seamless approach able to couple outputs from different ensemble numerical weather prediction (NWP) models with different temporal resolutions. Advances on the contribution of ultra-high resolution NWPs based on Large Eddy Simulation will be presented with evaluation results on real case studies like the Rhodes island in Greece.

When it comes to forecasting the power output of RES plants, mainly wind and solar, the focus is on improving predictability using multiple sources of data. The proposed modelling approaches aim to efficiently combine highly dimensionally input (various types of satellite images, numerical weather predictions, spatially distributed measurements etc.). A priority has been to propose models that permit to generate probabilistic forecasts for multiple time frames in a seamless way. Thus, the objective is not only to improve accuracy and uncertainty estimations, but also to simplify complex forecasting modelling chains for applications that use forecasts at different time frames (i.e. a virtual power plant - VPP- with or without storage that participates in multiple markets). Our results show that the proposed seamless models permit to reach these performance objectives. Results will be presented also on how these approaches can be extended to aggregations of RES plants which is relevant for forecasting VPP production.

How to cite: Kariniotakis, G. and Camal, S. and the Smart4RES team: Highlight results of the Smart4RES project on weather modelling and forecasting dedicated to renewable energy applications, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12923, https://doi.org/10.5194/egusphere-egu22-12923, 2022.

EGU22-12936 * | Presentations | ERE2.1 | Highlight

The GWIII contribution to the IPCC AR6 and its relevance to Energy Meteorology and Climate 

Andrea Hahmann

The Working Group III contribution to the Sixth Intergovernmental Panel on Climate Change (IPCC) Assessment Report-- mitigation of climate change-- will be publically released on 4 April 2022. The sections on "Mitigation Options: Energy Sources and Energy Conversion", "Climate Change Impacts on the Energy System", and a BOX on "Energy Resilience" are highly relevant to the Energy Meteorology community. As a Chapter Lead Author, I will summarise the findings of Chapter 6, Energy System, and emphasise their relevance to Energy Meteorology and Climate. I will also discuss my experience as a lead author and the challenges of communication between such different research communities. 

How to cite: Hahmann, A.: The GWIII contribution to the IPCC AR6 and its relevance to Energy Meteorology and Climate, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12936, https://doi.org/10.5194/egusphere-egu22-12936, 2022.

EGU22-12965 | Presentations | ERE2.1

Short-term forecasting of renewable production trajectories at high-temporal resolution 

Simon Camal, Dennis Van Der Meer, and George Kariniotakis

High temporal resolution intra-day and day-ahead renewable energy source (RES) power forecasts are important to maximize the value of RES systems because they give stakeholders the opportunity to participate in both the energy and ancillary services markets. In the realm of electricity markets, day-ahead electricity markets often require bids at hourly temporal resolution. However, the requirements for temporal resolution on intra-day markets are more demanding and may require a temporal resolution of 5 minutes in the near future.

Moreover, high resolution forecasts offer the possibility to employ advanced control strategies to mitigate severe frequency fluctuations in, for instance, island grids. More specifically, battery integration can improve power system management in isolated grids with high RES power penetration. However, battery control requires high temporal resolution forecasts.

Since the temporal dependence structure between time steps is highly relevant in control problems, there is a need to efficiently generate trajectory forecasts that can be used in stochastic optimisation problems. This study proposes an efficient method to generate trajectory forecasts of RES power production that is based on pattern matching. Consequently, we do not need to forecast all forecast horizons separately and estimate a covariance matrix that represents the dependence structure between the forecast horizons. To compare our method against the state-of-the-art, we use quantile regression forests in combination with a Gaussian copula and show that our method performs similar in terms of relevant scores but is approximately 98% faster and simplifies the modelling chain considerably.

The proposed method is evaluated on real data from operating renewable sites in an isolated power system. Considering its fast computation and its applicability to diverse situations (different energy sources, individual sites or aggregated production), the method has the potential to be integrated into the decision-making process of forecasting end-users such as operators of power systems under high renewable penetration.

How to cite: Camal, S., Van Der Meer, D., and Kariniotakis, G.: Short-term forecasting of renewable production trajectories at high-temporal resolution, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12965, https://doi.org/10.5194/egusphere-egu22-12965, 2022.

EGU22-13264 | Presentations | ERE2.1

The value of solar forecasting for energy-related applications: a treasure box of literature yet to be opened 

Rodrigo Amaro e Silva and Hadrien Verbois

The solar forecasting literature is rich and diverse; to navigate it, practitioners can rely on review papers, or on recent papers’ introduction sections. In a considerable share of the literature, however, the focus is put almost exclusively on model design and statistical assessment aspects. The economic value of solar forecasting research, on the other hand, is seldom discussed. Looking, for example, at two prominent review works [1,2], only 5-10% of their references address this issue. However, it is important not to assume from this that there is a lack of research done on this topic.
The present work aims to share the preliminary results of the analysis of an abundant and diverse amount of literature addressing the economic value of solar forecasts for energy-related applications. The goal is to better understand how that value depends on the accuracy of a given forecasting model, and how much it varies from one application to another. It is also of relevance to discuss how researchers infer such value.


References
1. Notton, G.; Nivet, M.L.; Voyant, C.; Paoli, C.; Darras, C.; Motte, F.; Fouilloy, A. Intermittent and stochastic character of renewable energy sources: Consequences, cost of intermittence and benefit of forecasting. Renew. Sustain. Energy Rev. 2018, 87, 96–105, doi:10.1016/j.rser.2018.02.007.
2. Antonanzas, J.; Osorio, N.; Escobar, R.; Urraca, R.; Martinez-de-pison, F.J.; Antonanzas-torres, F. Review of photovoltaic power forecasting. Sol. Energy 2016, 136, 78–111, doi:10.1016/j.solener.2016.06.069.

How to cite: Amaro e Silva, R. and Verbois, H.: The value of solar forecasting for energy-related applications: a treasure box of literature yet to be opened, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13264, https://doi.org/10.5194/egusphere-egu22-13264, 2022.

EGU22-13480 | Presentations | ERE2.1

Estimation of cloud motion vectors: exploring different approaches using a dense network of solar radiation sensors 

Yves-Marie Saint-Drenan, Rodrigo Amaro e Silva, Hartwig Deneke, and Philippe Blanc

At small time scales, the spatio-temporal variability of downwelling surface solar radiation can be considered in a first approximation as resulting from the advection of clouds. It is common in the solar energy and atmospheric science communities to use a quantity called Cloud Motion Vector (CMV) to quantify this displacement.
Intuitively, cloud advection is expected to be a direct result of wind patterns at cloud-height levels. This idea is reflected, for example, in various works where wind information at cloud height is used as a driver of solar variability in solar forecasting applications [1]–[6]. However, relating spatio-temporal characteristics of the solar radiation to the wind speed is not obvious. In some meteorological situations, such as orographic clouds, the wind speed and the apparent cloud movement can be decoupled. More generally, the coexistence of different layers of clouds advecting in different directions question the validity of the use of wind information at a single level.
Other inference techniques can be used to estimate the cloud motion vectors such as the calculation of block matching or optical flow algorithms applied to sequences of satellite images [7], [8] or the cross-correlation analysis of high-resolution measurements of dense networks of sensors [9], [10], like the ones from the HOPE [11] or Oahu [12] campaigns. Yet, these alternative methods have their own weaknesses: the conclusion of cross-correlation analysis can be hampered when the characteristics of the clouds are not appropriate to track their motion (e.g., absence of texture, edges), while satellite-based CMV may miss local advection due to limited spatial and temporal resolutions.
To better understand cloud advection dynamics and understand the strength and weaknesses of the different estimation methods, a benchmark has been done using the HOPE measurement campaign [11] as a reference, with 99 pyranometers with time step of 0.1 s and inter-sensor distances ranging from 100 m to 10 km. CMV timeseries have been inferred from three different approaches:
• Applying an optical-flow method to sequences of images of surface solar irradiance from the HelioClim-3 database [13], [14], derived from Meteosat Second Generation satellite.
• Evaluating the lagged cross-correlation between different pairs of ground sensors.
• Extracting vertically-resolved wind estimates from the ERA5 reanalysis [15].
The evaluation has been conducted in two steps. Firstly, a global evaluation was conducted to assess and rank the performance of CMV-based solar forecasting from the different sources/methods using as reference quality-checked measurements from the HOPE campaign. In a second step, a comprehensive compilation of relevant and typical situations, selected from a systematic visual inspection of time series, is proposed to explain the difference between the CMV sources/methods using illustrative examples.

 

How to cite: Saint-Drenan, Y.-M., Amaro e Silva, R., Deneke, H., and Blanc, P.: Estimation of cloud motion vectors: exploring different approaches using a dense network of solar radiation sensors, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13480, https://doi.org/10.5194/egusphere-egu22-13480, 2022.

EGU22-13481 | Presentations | ERE2.1

Improving 0-24 h offshore wind power forecasts over the Baltic Sea: comparing post-processing methods of varying complexity 

Christoffer Hallgren, Stefan Ivanell, Heiner Körnich, Ville Vakkari, and Erik Sahlée

Accurately forecasting short-term wind power production is a challenging task. As the share of wind power in the electrical system is rapidly growing, this task is becoming increasingly important not only for power production companies but also for transmission system operators. By applying post-processing methods to forecasts of wind speed from numerical weather prediction (NWP) models, power production forecasts can be improved. In this study, we used two years of lidar measurements of the wind speed from a coastal site in the Baltic Sea to calculate a theoretical power production and evaluated forecasts from the NWP model HARMONIE-AROME. Six post-processing methods of varying degree of complexity were implemented and tested in order to mimic how they could be used operationally. The performance of the methods in different weather situations was analysed in terms of the mean absolute error (MAE) skill score. For the test period it was found that, in general, the simple method of temporally smoothing the wind speed forecast by applying a low-pass filter (moving average) with a window of ±1 h outperformed the other methods tested. The main reason for this being a reduced risk of double penalty due to small time shifts in wind speed variations in the forecast compared to the observations. However, under weak synoptic forcing the best skill score was achieved using a mix of the forecast from the previous and the current day. Additionally, when low-level jets were forecasted, the best result was achieved using the machine learning random forest algorithm.

How to cite: Hallgren, C., Ivanell, S., Körnich, H., Vakkari, V., and Sahlée, E.: Improving 0-24 h offshore wind power forecasts over the Baltic Sea: comparing post-processing methods of varying complexity, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13481, https://doi.org/10.5194/egusphere-egu22-13481, 2022.

Extreme exploitation of fossil fuels has imposed catastrophic scarcity of energy sources, worldwide. Bioenergy is extremely pertinent to renewable energy alternatives. Municipal solid waste (MSW) and industrial organic waste has sufficient energy potential due to ample organic content. Moreover, landfilling being most economic disposal method offers incubated treatment of solid waste along with production of gases for energy generation. Bioreactor landfills are the new advancements to conventional landfills which accelerates the bioenergy production through incorporation of leachate recirculation. In this research, four simulated anaerobic landfill bioreactors co-disposed with paper mill sludge (PMS) as an industrial organic waste and MSW in three different proportions were installed. One reactor was kept as control (BRL1) with sole disposal of MSW along with other co-landfilled reactors with ratios of PMS and MSW as 1:3 (BRL2), 1:1 (BRL3) and 3:1 (BRL4). Leachate produced from each landfill reactors was utilized for moisture maintenance and degradation enhancement through its recirculation. Periodic analysis of leachate physico-chemical parameters and chromatographic analysis of landfill gas were performed until 300 days of landfilling. Artificial neural network (ANN) modeling was performed to predict biogas production and leachate organic pollutants removal from operating anaerobic landfill simulators. Experimented physico-chemical parameters including pH, electrical conductivity, volatile solids, volatile fatty acids, total alkalinity, ammoniacal and total nitrogen were used as input layer for neural network modeling. Different sets of output layers for leachate pollutants (chemical oxygen demand and total heavy metal concentrations) and biogas yield were decided for individual ANN training. Levenberg-Marquardt algorithm was used to train data sets with 10 number of hidden layers, 15% validation and 15% testing. Moreover, the performance of each landfill reactor was optimized statistically using back propagation network model. Over the completion of landfilling process, BRL3 with equal co-disposal ration of PMS and MSW fetched maximum biogas yield of 146.14 mL/VS/d, which was 1.53, 1.33 and 2.35 times more than that of BRL2, BRL4 and BRL1, respectively. The prediction model could forecast and statistically optimize the biogas content with excellent fitting with experimented data (R2 > 0.95). This study expands the dimensions of experimental and mathematical investigations for co-landfilling practices for not only acquiring energy out of simultaneously co-landfilled solid wastes from distinct origins but also supports the attempts for diminishing its leachate pollutant concentrations.

Keywords: Artificial neural network, Bioenergy production, Landfills, Co-disposal, Municipal solid waste, Paper mill sludge

 

How to cite: Srivastava, A. N. and Chakma, S.: Artificial Neural Network Modeling for Prediction of Bioenergy Production and Organic Pollutant Removal from Simulated Co-Disposed Landfills , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-118, https://doi.org/10.5194/egusphere-egu22-118, 2022.

EGU22-1074 | Presentations | ERE2.2

Multi-Criteria Decision Making for Site Suitability of a Solar Farms 

Lalit Mudholkar and Bharath Haridas Aithal

 The global electricity consumption is increasing at a faster rate than total global power production. Non-renewable sources contributed more than 63.3% of global electricity production in 2020, and such a high reliance on non-renewable sources could lead to electricity shortages and environmental issues. This alarming situation is on the doorstep as various countries in the world are facing electricity crises. Solar energy can be an alternative to tackle this problem and to achieve the Sustainable Development Goal (SDG) of affordable and clean energy. There are several environmental factors that affect the efficiency of solar panel. Thus, based on the nature and working principle of photovoltaic cell, there is a need to prioritise these factors to locate suitable locations to increase the efficiency of both transmission and generation. Solar panel being expensive capital component, meticulous planning of such projects is necessary as it has long payback period, substantial investment, and relatively lower returns on investment. This study emphasises on two components, first the method of finding a suitable location with several required parameters through geospatial data analysis and the second being financial feasibility by identifying suitable locations of execution and maintenance costs that will be as minimal as possible without compromising the efficient solar locations. Higher efficiency and lower cost locations will together increase sustainability and affordability that contribute to achieving the SDG of affordable and clean energy. 

How to cite: Mudholkar, L. and Haridas Aithal, B.: Multi-Criteria Decision Making for Site Suitability of a Solar Farms, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1074, https://doi.org/10.5194/egusphere-egu22-1074, 2022.

EGU22-4463 | Presentations | ERE2.2

Let’s talk: incorporating stakeholder needs in climate-science based wind resource assessments 

Laura Schaffer, Johanna Borowski, Martin Dörenkämper, Daniela Jacob, Elke Keup-Thiel, Kevin Sieck, and Jan Wohland

The variable nature of wind power generation poses many challenges. The scientific community has addressed many of these challenges and made much progress in the recent years. These include, for example, quantifying resource variability, constraining future climate change impacts on wind energy, and suggesting robust system designs. Much of this research, however, has been academic in nature and lacks bi-directional interactions with stakeholders who make real world decisions. As an attempt to facilitate more exchange with industry partners, we present first results of a stakeholder workshop. The workshop theme is the role of climate in wind energy site assessments, including aspects related to climate variability and climate change. In addition to direct yield related parameters, such as capacity factors and their variability, we also plan to address relevant indirect effects that are less extensive researched, such as climate-induced changes in bat activity that trigger generation interruptions and blade icing. We report on the workshop design, highlight lessons learned and illustrate how the stakeholder feedback is used in shaping the precise research questions to be addressed in the course of the KliWiSt project [1]. KliWiSt is a German acronym that stands for the impact of climate change on wind energy site assessments. The general transdisciplinary approach can be adapted and used in other stakeholder-oriented research projects.


[1] https://www.climate-service-center.de/science/projects/detail/103308/index.php.en; https://www.iwes.fraunhofer.de/de/forschungsprojekte/aktuelle-projekte/kliwist.html

How to cite: Schaffer, L., Borowski, J., Dörenkämper, M., Jacob, D., Keup-Thiel, E., Sieck, K., and Wohland, J.: Let’s talk: incorporating stakeholder needs in climate-science based wind resource assessments, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4463, https://doi.org/10.5194/egusphere-egu22-4463, 2022.

We construct a geodatabase of spatially resolved PV supply profiles for building, land and water-bound installations under typical meteorological circumstances. This is done for three 2050 energy transition scenarios, which are all in line with the Dutch Climate Agreement, but differ from each other regarding the degree of decentralization of electricity demand and supply.

Hourly global horizontal irradiation (GHI) measurements by 33 Dutch ground observation stations are gathered and linearly interpolated to obtain a raster dataset with a resolution of 25 km. GHI is converted to global tilted irradiation (GTI) for a multitude of slope and azimuth combinations by subsequently applying the Erbs diffuse fraction and Perez transposition models, thus generating a GTI lookup table.

By combining building polygons and a high-density LiDAR height point cloud, roof surface polygons characterized by a slope and azimuth are identified for all buildings in the Netherlands. Using the GTI lookup table, the solar resource on each of the roof surfaces is determined. Scenario-specific national PV capacities for residential and utility buildings are then distributed over neighborhoods proportional to the total yearly solar resource on their corresponding roof surfaces. The resulting neighborhood capacities are sub-distributed over slope-azimuth-positions by applying distribution ratios found in a large dataset on registered Dutch PV systems.

Scenario-dependent national capacities for field-bound PV (agriculture, roadside and dike) and inland water-bound PV are distributed over municipalities proportional to their corresponding suitable land use areas. Offshore PV capacity is kept on national level. All neighborhood and municipality capacities are converted to GTI. The building-bound profiles are then translated to PV supply by applying solar elevation angle dependent performance ratios and an assumed panel efficiency of 20%. The same is done for the land and water-bound profiles, only now assuming a constant performance ratio of 90%. Residential building-bound PV is fully allocated to the low voltage distribution grid. For the utility variant, the portion allocated to low voltage level is equal to the neighborhood floorspace share of utility buildings estimated to have a grid connection capacity of less than 300kW. The remainder is assigned to mid voltage level. Water and land-bound PV supply is apportioned to mid and high voltage level with a 3:1 ratio, except for the offshore category, which is fully allocated to high voltage level.

Research results will be presented in the form of a country map and a cumulative distribution function (CDF) graph for; low voltage PV supply; mid voltage PV supply,  low voltage self-sufficiency,  and mid voltage self-sufficiency. All maps and CDF graphs provide information for all three 2050 scenarios, a 2030 scenario and the present situation. 

The PV supply calculation module described above is part of our Advanced Scenario Management model. This model consists of a number of supply and demand modules (traditional building demand, heat pump demand, electric vehicle demand, PV supply and wind turbine supply), each producing low voltage (neighborhood), mid voltage (municipality) and high voltage (country) level electricity profiles. Together, they allow for supply-demand system analysis for multiple voltage levels and energy transition scenarios.

How to cite: van Sark, W., Nortier, N., and Mewe, A.: Spatio-temporal potential profiles for building, land and water-bound photovoltaic installations for future Dutch energy transition scenarios, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4468, https://doi.org/10.5194/egusphere-egu22-4468, 2022.

EGU22-4481 | Presentations | ERE2.2

How weather and climate affect renewable electricity sources in Norway 

Ingjerd Haddeland and Maria Sidelnikova

European electricity production is increasingly based on renewable energy sources, inspired by ambitious climate politics. Hence, the power system must adapt to larger shares of less flexible electricity sources like wind and solar, which depend on fluctuating weather. Here, hydro power inflow, wind power, solar power and electricity demand in Norway are estimated based on meteorological data for the period 1961-2020. The installed capacity of the production technologies is kept constant at 2020 levels throughout the analyses. Mean annual power production is higher than mean annual electricity demand. However, the variability in production potentials is large for all renewable energy sources at time scales ranging from hourly to annual, and power deficits occur occasionally even at the annual scale. Hydro power inflow shows an increasing trend during the period studied, and the relative increase is largest during the winter season. Wind and solar power production are only marginally affected by climate differences in the study period. Electricity consumption decreases somewhat during the 60-year period, due to increasing average temperatures. The combined effect of production and consumption changes is an increase in mean annual surplus of electricity during the period studied. However, although a surplus of electricity exists at the mean annual level, additional available electricity in the form of reservoir storage or import is needed to maintain security of supply within the country.

How to cite: Haddeland, I. and Sidelnikova, M.: How weather and climate affect renewable electricity sources in Norway, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4481, https://doi.org/10.5194/egusphere-egu22-4481, 2022.

EGU22-5615 | Presentations | ERE2.2

Climate ambiguity and optimal allocation of renewable energy capacities in the 2050 EU 

Natalia Sirotko-Sibirskaya, Fred Espen Benth, and Marianne Zeyringer

The Paris Agreement aims at creating the climate-neutral world by the middle of the 21st century. One possible and currently popular solution to achieve this goal is to integrate renewable energies into the existing power grid. However, this is a highly complex task, since renewable energies are intermittent due to their weather dependency and predicting weather long-term both at a sufficient time and spatial resolution is non-trivial. It is often the case that both weather predictions based on historical data and future climate predictions are of very limited precision. To accommodate both for aleatoric and epistemic uncertainties we address the problem of optimal allocation of renewable energy capacities in the context of distributionally robust optimization, where the best possible capacity allocation is found given the worst possible weather conditions. We determine the optimal mix for the future 2050 climate-neutral Europe in the financial portfolio framework, where we view mean production of renewable power plants as expected returns on the assets. In the suggested framework portfolio risk is diversifed based on probabilistic characteristics of the underlying assets. Taking into account probabilistic nature of weather variables provides additional safety guarantees which are of primary importance when modelling renewable-based power systems. We limit our analysis to solar and wind energy capacities and implement suggested approach using both historical data-based forecasts and climate predictions models for the EU. 

How to cite: Sirotko-Sibirskaya, N., Benth, F. E., and Zeyringer, M.: Climate ambiguity and optimal allocation of renewable energy capacities in the 2050 EU, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5615, https://doi.org/10.5194/egusphere-egu22-5615, 2022.

Policy and economic analyses use simple estimates of regional and global wind energy potential, or technical wind energy potential, to evaluate low carbon energy transition pathways. They  neglect the reduction in mean wind speeds due to the extraction of kinetic energy (KE) from the lower atmosphere as a means to reduce the computational complexity. However, climatological analyses of proposed regional wind turbine deployments with capacity densities ranging from 2-10 MW km-2 show that this assumption leads to significant overestimation of wind energy potentials because the removal of KE does reduce wind speeds and turbine yields. This gap between policy focussed and climatology based estimates implies the need for the former to use a more climatologically descriptive, yet simple, approach to estimating technical potential. Framing regional wind energy potential within the context of a fixed lower atmosphere KE budget which uses variation in mean boundary layer height to define the KE budgets can improve estimates without increasing computational complexity. We evaluate this hypothesis by analysing a set of previously published Weather Research and Forecasting simulations of a hypothetical large scale wind turbine deployment in Kansas, US, which showed that nighttime yields were lower than daytime, despite wind speeds being 40% higher at night. We assess this seemingly counter-intuitive result by estimating day and nighttime yields while constraining them with separate day and night KE budgets. Daytime budgets are defined by higher mean boundary layer heights (2000m) while nighttime budgets by lower heights (900m). The combination of wind speeds boundary layer variations during day and night result in similar budgets. This means that turbines extract more KE from the atmosphere at night than daytime, leading to the nighttime budgets being depleted faster and thus lower deployment yields. Using the standard approach, which discounts the effect of KE removal by wind turbines, leads to a 180% and 600% overestimation in day and nighttime yields, respectively, relative to the weather model simulations. The KE budget approach , in contrast, leads to a significant improvement with day and nighttime bias being reduced to 20% and 60%, respectively. Using this approach, we revaluate existing technical wind energy potentials using the net area available for wind energy deployment in Kansas to show that yield expectations of 2000-3000 TWh yr-1 could be reduced by almost 50%. Despite this reduction, the technical potential remains almost 3-5 times higher than the state’s 2018 primary energy consumption. We show that framing the yield from regional wind turbine deployments within a fixed lower atmosphere KE budget framework that uses mean boundary layer variations to define the KE budget leads to more climatologically representative estimates of technical potential without increasing computational complexity. These estimates are likely to improve further with the inclusion of nighttime stability effects. Climatologically representative estimates of technical wind energy potential will enable the development of more robust renewable energy transition policy. 

How to cite: Minz, J., Mbungu, N., Kleidon, A., and Miller, L.: Estimates of technical wind energy potentials can be improved by incorporating information about the variation in mean boundary layer heights, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5764, https://doi.org/10.5194/egusphere-egu22-5764, 2022.

Electricity system optimisation models should have a high spatial resolution, because mixing locations with high renewable yield and locations with high electricity demand while ignoring power lines underestimates transmission constraints that can cause congestion. This can result in an infeasible model and is particularly true for configurations with high renewable penetration because the infrastructure of today’s transmission grid is not designed for an uncertain and geographically scattered generation. But spatially high resolved models are computationally intractable, therefore researchers have developed methods to simplify their models on a spatial scale. Common approaches include modeling every country by a single node, or clustering spatially high resolved models using selected clustering methods. Nevertheless, it was not investigated if results obtained from such low resolution or clustered models are feasible when dis-aggregating the results back into a higher resolution. Moreover, no evaluated dis-aggregation method exists to the author’s knowledge. This is a challenging task as the clustering process typically is not bijective and finding a suitable inverse is not intuitive.

Here, we propose a first method to dis-aggregate spatially low resolution model results into higher resolution. The proposed dis-aggregation is a local optimisation problem that minimises the excess of renewable energy for every node within the cluster while respecting land-use restrictions. We define excess as the available renewable energy per node minus local electricity demand minus all transmission capacity that is connected to the node. Electricity storage is distributed proportional to the resulting renewable capacity. Then, the spatially high resolved model is solved as an operational problem where no further capacity expansion is allowed. We investigate if the cost-optimal low resolution investment results of a fully renewable system that consists of wind and solar energy and storage (hydrogen and battery) is feasible when dis-aggregated into a spatially high resolved model of 1250 nodes. Results of our novel approach are benchmarked against the intuitive Ansatz to uniformly dis-aggregate the low resolution modeling results, i.e. distributing the capacity of a clustered node evenly among the nodes in the high-resolution model.

Our results for dis-aggregating a low resolution model of Europe where every country is modeled as a single node are that 12.8% of total demand can not be met with renewable energy (benchmark: 15.3%). If this gap is compensated with gas, carbon emissions would rise by 5% of 1990 emissions (benchmark: 6%) and total annual system costs would increase by 24 billion euros (benchmark: 29 billion). When modelling Europe with 100 nodes, our dis-aggregtion method yields 5.6% of unmet demand (benchmark: 7.3%). This means that carbon emissions would rise by 2.2% (benchmark: 2.7%) compared to 1990s level in case the unmet demand is satisfied with gas and would increase the total system costs by additional 10.6 billion euros (benchmark: 13.2 billion). This result supports other research which shows the importance of modelling at higher resolution than country boundaries in order to avoid unwanted infeasibilities. Approximately one half of unmet demand can be avoided by raising the model resolution in Europe to 100 nodes.

How to cite: Frysztacki, M. and Brown, T.: Inverting spatially low resolved electricity system modeling results: How feasible are they when disaggregated into high resolution?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5827, https://doi.org/10.5194/egusphere-egu22-5827, 2022.

EGU22-6907 | Presentations | ERE2.2 | Highlight

Extreme impacts in the European renewable electricity system as a result of climate variability 

Lieke van der Most, Karin van der Wiel, Richard Bintanja, René Benders, and Winnie Leenes

With the need for clean energy that reduces greenhouse gas emissions, the coming decades will see a transition of our energy system towards a higher share of renewable energy sources. With this work we aim at gaining insight in meteorological conditions that lead to extremely low energy generation and extremely high residual load (difference between production and demand) in European countries. We constructed a simplified climate-energy modeling framework in which extreme impact events on the European energy system can be examined. We compute daily electricity demand and the supply from hydropower, wind and photovoltaic solar, based on 2000 years of simulated present and future weather conditions for countries in Europe. From this data the meteorological drivers with high impact on the current energy system were investigated for individual countries and larger regions. Atmospheric blocking in summer can result in heatwaves and droughts that in turn result in long-lasting periods of high energy demands in countries with large cooling capacities (southern Europe) and low energy production in countries that rely on hydropower. In winter, dry and cold periods with lower than normal windspeeds lead to high residual load in northern European countries, especially around the North Sea. These countries have a high share of offshore wind and high installed heating capacities. Dry seasons lead to a higher sensitivity to wind and solar variability due to a decrease in balancing potential of hydropower. Additionally, the co-variability of electricity shortage events between countries is investigated. The goal is to identify balancing potential of transmission between countries. Due to different demand profiles across Europe and the spatial variability of weather the potential of extreme event reduction through cross-border transmission is high.

How to cite: van der Most, L., van der Wiel, K., Bintanja, R., Benders, R., and Leenes, W.: Extreme impacts in the European renewable electricity system as a result of climate variability, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6907, https://doi.org/10.5194/egusphere-egu22-6907, 2022.

EGU22-8608 | Presentations | ERE2.2

Climate change impact on wind and PV power generation characteristics in Europe 

Yvonne Scholz and Ronald Stegen

Climate change may alter long term averages as well as short term extremes of solar irradiation and wind speed distributions. Resulting changes in the performance of wind and solar power generation capacities can impact returns on investments and security of power supply. To assess this impact and enable robust energy system planning, we use climate scenarios from global and regional climate models on an hourly basis to calculate renewable power generation potentials with our Energy Data Analysis Tool EnDAT. We investigate the development of key parameters of wind and solar power generation: annual capacity factors, minimum and maximum generation, duration of periods with extremely low generation and ramp rates. Results show that while changes are small at European average, significant changes can occur at country level. We present model results and discuss uncertainties associated with the climate scenarios and wind and solar power technology parameters as well as capacity distribution. Future research will include demand scenarios and the impact of climate change on “Dunkelflaute”-events in Europe.

How to cite: Scholz, Y. and Stegen, R.: Climate change impact on wind and PV power generation characteristics in Europe, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8608, https://doi.org/10.5194/egusphere-egu22-8608, 2022.

EGU22-9573 | Presentations | ERE2.2

Impact of Legislation and Social Acceptance on Wind Potentials in Germany 

Stanley Risch, Noah Pflugradt, Leander Kotzur, and Detlef Stolten

In the climate protection act of 2021 Germany has set the goal to become climate neutral by 2045 [1]. To meet this target, the renewable energy sites in Germany must be significantly expanded. At the same time, the acceptance of wind turbines is heavily discussed. For example, the construction of wind turbines inside forests or distances to residential buildings are topics in societal discussions. Furthermore, the different legislation in the individual federal states lead to unequal wind expansion possibilities.

This paper assesses the impact of legislation on the onshore wind energy potential in Germany considering residential buildings for the first time. To this end, different scenarios for high resolution land eligibility analyses are developed with the open-source tool GLAES [2] using a 10 m*10 m resolution and high accuracy GIS-data. Firstly, the impact of different exclusion zones in the analysis is evaluated. The distance to residential land use and the use of forests and protected landscapes are especially influential for the results. Secondly, we investigate the impact of different legislation in the individual German federal states. A comparison to national energy system studies shows that a nationwide application of for example Bavaria’s legislation leads to insufficient wind capacity potentials to reach climate neutrality by 2045. Thirdly, we evaluate the distribution of the wind potential when the current federal states’ legislation is applied which uncovers large inequalities.

 

[1]    Bundes-Klimaschutzgesetz (KSG). 2021. Accessed: Jan. 05, 2021. [Online]. Available: https://www.gesetze-im-internet.de/ksg/KSG.pdf
[2]    D. Ryberg, M. Robinius, and D. Stolten, ‘Evaluating Land Eligibility Constraints of Renewable Energy Sources in Europe’, Energies, vol. 11, no. 5, p. 1246, May 2018, doi: 10.3390/en11051246.

 

How to cite: Risch, S., Pflugradt, N., Kotzur, L., and Stolten, D.: Impact of Legislation and Social Acceptance on Wind Potentials in Germany, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9573, https://doi.org/10.5194/egusphere-egu22-9573, 2022.

EGU22-9597 | Presentations | ERE2.2

Analyzing Input Data Influence in Local Techno-Economic Analyses for Power-to-Methane Plants 

Javier Valdes, Robert Bauer, and Grégoire Klaus

Power-to-methane has been identified as a solution for quickly and effectively exploiting surplus electricity potential. Nevertheless, due to the current efficiencies, costs and sizes, it may not be suitable for local energy transitions. This article presents the results of two optimization models developed in Calliope for two case studies regions, with low wind levels in southern Germany with different electricity mixes. The optimization models simulate all available generation sources in the regions and their extensions with an additional Power-to-methane plant. The model minimizes the cost of the overall systems that meet the given demand including the gas, district heating, and electricity systems. Annual gas and district heating demand are generated based on collected data from industries, commerce, and households and standard load profiles, while annual electricity demand is obtained from public statistics. Besides, hourly electricity demand data from industries, commerce, and households are collected. Results are compared with scenarios using standard load profiles for electricity. The results show that the use of Power-to-methane is significantly affected by the load profiles used as well as the existing technological mix.

How to cite: Valdes, J., Bauer, R., and Klaus, G.: Analyzing Input Data Influence in Local Techno-Economic Analyses for Power-to-Methane Plants, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9597, https://doi.org/10.5194/egusphere-egu22-9597, 2022.

For the analysis of the expected performance of renewable energy systems of all sizes, nowadays various data bases offer the required time series of irradiances and wind speed. The validation of these sets is mainly based on various comparison schemes of averages or distribution functions on a yearly or monthly scale, forming a comprehensive toolbox for the respective quality assessment.  This allows for a high confidence in predictions of system performance data, as-long-as system operation can be considered as “memory-less”.  This is most prominently not the case for systems containing storage devices whose performance depend on the temporal characteristics of the time series - which had been less in focus for the validation of irradiance sets. 

This contribution aims to discuss which sequential characteristics of the data series govern the storage sizing. This should result in the identification of parameters that are applicable for the validation of irradiance series for this task. As example, photovoltaic + battery systems are analyzed, that are driven by data extracted from different sources made available by the PVGIS (https://ec.europa.eu/jrc/en/pvgis ) service.

How to cite: Beyer, H. G.: Identifying sequential characteristics of irradiance data sets applicable for the validation of sets for the assessment of the performance of renewable energy systems containing storage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9615, https://doi.org/10.5194/egusphere-egu22-9615, 2022.

EGU22-9702 | Presentations | ERE2.2

PV and wind power simulation with ERA5 and ERA5-land – a multi-country analysis 

Katharina Gruber, Luis Ramirez Camargo, and Johannes Schmidt

Climate data sets are widely used for renewable power simulation. While previous generations of global reanalysis data including MERRA-2 and ERA-Interim have been widely assessed for their suitability to simulate variable renewable power systems, more recent datasets such as ERA5 and ERA5-Land lack validation, particularly in regions outside of Europe.

Here, we assess the accuracy and bias of wind power simulation using ERA5 wind speeds in Brazil and New Zealand as well as solar photovoltaic power simulation accuracy using ERA5-Land solar radiation and temperature data in Chile. We compare the performance of ERA5 and ERA5-Land to MERRA-2 based renewable power generation. The reference data sets are capacity factors derived from data measured at individual installations in each country and the performance indicators include the pearson’s correlation coefficient, mean bias error (MBE) and root mean square error (RMSE). For wind power simulation, we also assess a bias correction method using the Global Wind Atlas.

Since models applying the resulting datasets are based on different spatial and temporal scales, we also aim at finding a relation between the spatial and temporal resolution and simulation quality. We assess the simulation results applying spatial aggregation ranging from individual installations to the country level and temporal aggregation varying from hours to months. This aids to evaluate the reliability of the simulated renewable power generation time series on various spatiotemporal scales for future simulation efforts.

Overall, we find that both datasets, ERA5 and ERA5-Land, perform well in wind and solar photovoltaic power simulations. For wind power simulation, ERA5 shows improved performance compared to MERRA-2 based wind power simulation, while for solar photovoltaic the improvements of ERA5-Land compared to MERRA-2 are minor. Correlation of wind power generation is around 0.8 without correction and MBEs around -0.1. Mean bias correction with the Global Wind Atlas does not consistently improve simulation results. For the solar photovoltaic power simulation, we find correlations above 0.75, while the MBE is between -0.05 and 0.1.

How to cite: Gruber, K., Ramirez Camargo, L., and Schmidt, J.: PV and wind power simulation with ERA5 and ERA5-land – a multi-country analysis, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9702, https://doi.org/10.5194/egusphere-egu22-9702, 2022.

EGU22-9909 | Presentations | ERE2.2 | Highlight

Severity of variable renewably energy droughts in Germany and Europe 

Martin Kittel

Increasing the generation of variable renewable energy sources (VRE), such as wind or solar photovoltaics, is one pivotal element in the decarbonization of our energy systems. VRE availability depends on prevailing weather conditions. During a period with high VRE availability, surplus energy needs to be integrated into the system. Times of VRE shortage require flexibility options that can serve demand. These options need to cover VRE droughts, i.e., long-lasting periods of low VRE availability. They may challenge the security of supply, notably in the case of simultaneity with high demand phases, and vary largely across time and space. This paper evaluates VRE droughts in terms of severity, duration, timing, and simultaneity in Germany and Europe using the Pan-European Climate Data Base by ENTSO-e, which provides VRE availability factors for 35 years.

 

Two definitions apply to VRE droughts (Ohlendorf & Schill, 2020). First, droughts as periods of consecutive hours with availability factors constantly below a certain threshold (CBT). Second, droughts as periods of consecutive hours with a moving average of VRE availability factors below a certain threshold (mean below threshold – MBT). While the CBT notion identifies drought periods in the narrow sense, the MBT definition also accounts for longer stretches of low VRE availability on average, with short instances of VRE availability above a threshold possible. Contrasting results from these two approaches reveals insights on the short- and long-term need for flexibility, for instance, by different types of storage.

 

Additionally, there are two options to count VRE droughts: First, a drought window denotes a period of consecutive availability factors with a fixed duration, qualified either according to the CBT or MBT notion. Windows are counted for increasing window size, starting with a few hours up to multiple months. This method identifies flexibility slices that the system needs to provide for all relevant time scales. Second, a drought event is a period of consecutive availability factors with variable duration. The algorithm counts in descending order from the longest event lasting multiple months to events lasting only a few hours. Consequently, each qualified CBT or MBT period is counted only once. Results reveal the number of drought events with a minimum duration that the system needs to balance.

 

This paper analyzes VRE droughts of individual VRE generation technologies, all VRE generation technologies combined, and, to account for simultaneity with demand peaks, residual load time series to identify periods with an energy deficit in the system (Ruhnau & Qvist, 2022). Insights allow for a distinct assessment of the relevance of energy droughts concerning VRE technologies individually and in terms of simultaneity for the transition of our energy systems, both in the German and European context (Raynaud et al., 2018; Kaspar et al., 2019).

 

 

References

Ohlendorf, N., Schill, W.-P., 2020. DOI: 10.1088/1748-9326/ab91e9

Kaspar, F., Borsche, M., Pfeifroth, U., Trentmann, J., Drücke, J., Becker, P., 2019. DOI 10.5194/asr-16-119-2019.

Raynaud, D., Hingray, B., François, B., Creutin, 2018. DOI: 10.1016/j.renene.2018.02.130.

Ruhnau, O., Qvist, S., 2022. (in press).

How to cite: Kittel, M.: Severity of variable renewably energy droughts in Germany and Europe, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9909, https://doi.org/10.5194/egusphere-egu22-9909, 2022.

EGU22-9953 | Presentations | ERE2.2

Energy production simulation of Agrivolatic Systems 

Christian Mikovits, Theresa Krexner, Iris Kral, Alexander Bauer, Thomas Schauppenlehner, Martin Schönhart, Erwin Schmid, and Johannes Schmidt

The European Union set the goal to meet 32% of its final energy consumption from renewable sources by 2030. Other than fossil or nuclear electricity generation, VRE produce electricity not at a few individual locations, but distributed throughout a country. Even though solar PV can be generated on urban infrastructure, e.g. on rooftops or above parking spaces, this potential is limited and costs are usually higher than those for ground mounted PV. It is therefore likely that substantial amounts of solar PV have to be deployed as ground mounted PV and land use conflicts may arise from this infrastructure expansion. Mainly land which is currently under agricultural use would be available for that purpose. As this would imply a competition between food, feed, and electricity production, expansion on that kind of land is discussed controversially. One option for minimizing this conflict is an integrated use of agricultural land, producing both agricultural products and electricity from PV. To better understand the synergies and trade-offs, A thorough analysis of integrated PV and agricultural production on a large scale is necessary.

This work presents a simulation framework to determine electricity as well as crop production of APV systems at high temporal and spatial resolution. Radiation data, digital height data and land cover data function as input data to find suitable areas and simulate the APV system power output.

How to cite: Mikovits, C., Krexner, T., Kral, I., Bauer, A., Schauppenlehner, T., Schönhart, M., Schmid, E., and Schmidt, J.: Energy production simulation of Agrivolatic Systems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9953, https://doi.org/10.5194/egusphere-egu22-9953, 2022.

EGU22-10283 | Presentations | ERE2.2

Offshore wind and solar photovoltaic energy combination to stabilize energy supply in the western Iberian Peninsula in the near future. 

Xurxo Costoya, Maite deCastro, David Carvalho, Beatriz Arguilé-Pérez, and Moncho Gómez-Gesteira

The expansion of marine renewable power is a major alternative for the reduction of greenhouse gases emissions. In Europe, however, the high penetration of offshore wind brings intermittency and power variability into the existing power grid. Offshore solar photovoltaic power is another technological alternative under consideration in the plans for decarbonization. However, future variations in wind, air temperature or solar radiation due to climate change will have a great impact on both renewable energy resources. In this context, this study focusses on the offshore energy assessment off the coast of Western Iberia, a European region encompassing Portugal and the Northwestern part of Spain. Making use of a vast source of data from 35 simulations of a research project called CORDEX, this study investigates the complementarity of offshore wind and solar energy sources with the aim of improving the energy supply stability of this region up to 2040. The most pessimistic greenhouse gases emission scenario (RCP8.5) is considered. The 35 simulations are validated by comparing wind speed at 10m, air temperature at 2m and solar radiation values with data from the ERA5 reanalysis database. Although the offshore wind energy resource has proven to be higher than solar photovoltaic resource at annual scale, both renewable resources showed significant spatiotemporal energy variability throughout the western Iberian Peninsula. When both renewable resources are combined, the stability of the energy resource increased considerably throughout the year. The proposed wind and solar combination scheme is assessed by a performance classification method called Delphi, considering stability, resource, risk, and economic factors. The total index classification increases when resource stability is improved by considering hybrid offshore wind-photovoltaic solar energy production, especially along the nearshore waters.

How to cite: Costoya, X., deCastro, M., Carvalho, D., Arguilé-Pérez, B., and Gómez-Gesteira, M.: Offshore wind and solar photovoltaic energy combination to stabilize energy supply in the western Iberian Peninsula in the near future., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10283, https://doi.org/10.5194/egusphere-egu22-10283, 2022.

Wind power is attracting more attention as an alternative energy in accordance with efforts to reduce carbon emissions, but its stable operation is difficult due to the intermittency of wind. Since the 1990s, many previous studies have suggested forecasting models focusing on accuracy and speed using numerical weather prediction models, statistical approaches, and hybrid techniques. However, although their verification methods and periods are different, most showed high errors of about 15% or more. In this study, we developed and validated a hybrid forecasting model using the mesoscale model Weather Research and Forecasting (WRF) and artificial neural network (ANN) for a wind farm located in Yeongyang-gun, Gyeongsangbuk-do, South Korea, a complex mountainous terrain (36°36ʹ49ʺN, 129°13ʹ21ʺE). In order to simulate more accurate wind at hub-height of wind turbine (i.e., 80 m), roughness sublayer parameterization (Yonsei surface layer scheme; YSL) is used and daily spatio-temporal high resolution wind forecasts are performed for one year in 2020. The simulated wind speed and actual wind power generation at that time are used as training data set for ANN to construct a hybrid forecast model, and it is validated for January and February 2021. Our analysis shows that improved parameterization in the roughness sublayer can significantly contribute to wind power forecasting through more accurate wind speed forecasting.

How to cite: Kim, J., Gim, K., and Hong, J.: Hybrid wind power forecasting model (WRFv4.1.3 and Artificial Neural Network) considering roughness sublayer characteristics, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10976, https://doi.org/10.5194/egusphere-egu22-10976, 2022.

EGU22-11025 | Presentations | ERE2.2

Evaluation of varying spatial resolution in power system modelling 

Maximilian Roithner, Marianne Zeyringer, and James Price

Power system models are frequently used in academia and by policymakers to study different designs of country or continent-wide electricity systems. To have them remain computationally feasible, simplifications are made in many areas. When assessing the variability of renewable generation sources, weather data is an important input to such models. Yet, the spatial resolution of weather data (e.g., from reanalysis or satellites) is often more detailed than the resolution of the models using them. Hence, it is common to use averages or other aggregation techniques to use the weather data in the power system model.  

Using our power system model highRES, we compare the performance of an aggregated version (NUTS1 and 3- level) to an unaggregated grid cell level one based on ERA5 reanalysis data (30 km), to assess the benefits and drawbacks of this simplification: In the former, the aggregation is performed on the inputs already before handing them to the model (an hourly zonal average capacity factor for each technology is computed from all cells in that region before running the model), while the latter is allowed to pick and choose the grid cells that are to be used to deploy variable renewable generators in each region. The resulting grid cell model makes use of the high spatially resolved weather data. Using this framework, we seek to understand how varying spatial resolution impacts the cost and design of the power systems it produces, with different shares of renewable generation technology penetration.

How to cite: Roithner, M., Zeyringer, M., and Price, J.: Evaluation of varying spatial resolution in power system modelling, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11025, https://doi.org/10.5194/egusphere-egu22-11025, 2022.

EGU22-11608 | Presentations | ERE2.2

Climatic response of thermally coupled solar water splitting in Antarctica 

Moritz Kölbach, Oliver Höhn, James Barry, Manuel Finkbeiner, Kira Rehfeld, and Matthias M. May

Hydrogen is a versatile energy carrier. When produced with renewable energy by water splitting, it is a carbon neutral alternative to fossil fuels. The industrialization process of this technology is currently dominated by electrolyzers powered by solar or wind energy. For small scale applications, however, more integrated device designs for water splitting using solar energy might optimize hydrogen production due to lower balance of system costs and a smarter thermal management. Such devices offer the opportunity to thermally couple the solar cell and the electrochemical compartment. In this way, heat losses in the absorber can be turned into an efficiency boost for the device via simultaneously enhancing the catalytic performance of the water splitting reactions, cooling the absorber, and decreasing the ohmic losses.[1,2] However,integrated devices (sometimes also referred to as “artificial leaves”), currently suffer from a lower technology readiness level (TRL) than the completely decoupled approach.

Here, we describe our progress in designing integrated solar water splitting devices to power research stations in Antarctica as a first potentially economic competitive implementation of this technology.[3] In such remote world regions, local and small-scale hydrogen production can become both economically and environmentally favorable, since the logistics for fossil fuels are expensive and environmentally hazardous. One reason for the low TRL of integrated devices is the complex and poorly understood influence of different weather/climate conditions and changes in the solar spectra on their efficiency.[4] Therefore, we introduce an open-source Python-based model that combines solar cell physics, optical simulations, electrochemistry, as well as atmospheric and climate data as part of the “YaSoFo” environment.[5] We model and analyze the climatic response of a device based on state-of-the-art AlGaAs/Si dual-junction photoabsorbers in Antarctica. Furthermore, we present a first prototype demonstrating solar water splitting at temperatures as low as -20°C. [3]  

Our work gives important insights into the chances and challenges for thermally coupled solar water splitting and lays the foundation for our goal of using these devices in remote world regions with cold climates.

 

[1] R. van de Krol, B. Parkinson, MRS Energy Sustain., 2017, 4(e13), 1-11

[2] S. Tembhurne, F. Nandjou, S. Haussener, Nat. Energy, 2019, 4, 399–407

[3] M. Kölbach, K. Rehfeld, M.M. May, Energy Environ. Sci., 2021,14, 4410-4417

[4] M. Reuß, J. Reul, T. Grube, M. Langemann, S. Calnan, M. Robinius, R. Schlatmann, U. Rau,  D. Stolten, Sustain. Energy Fuels, 2019, 3, 801-813

[5] M. M. May, D. Lackner, J. Ohlmann, F. Dimroth, R. van de Krol, T. Hannappel, K. Schwarzburg, Sustain. Energy Fuels, 2017, 1, 492-503

How to cite: Kölbach, M., Höhn, O., Barry, J., Finkbeiner, M., Rehfeld, K., and May, M. M.: Climatic response of thermally coupled solar water splitting in Antarctica, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11608, https://doi.org/10.5194/egusphere-egu22-11608, 2022.

EGU22-11962 | Presentations | ERE2.2

An overview of land-use requirements for solar PV and wind power 

Olga Turkovska, Katharina Gruber, Michael Klingler, Claude Klöckl, Luis Ramirez Camargo, Peter Regner, Sebastian Wehrle, and Johannes Schmidt

From a superficial reading of the literature on land-use requirements for renewable energy systems, one may conclude that the community has a very clear understanding of how much land is necessary to deploy renewable energy generation technologies. In particular for solar PV and wind power (VRES), the technologies with the highest growth potentials in the coming decades, abundant literature is available. However, a systematic overview is lacking, in particular, concerning approaches used for estimating the requirements, underlying factors that affect the results, and the regional differences.

There is no standard metric that is applied for estimating the land area necessary to accommodate a certain amount of renewable energy capacity. Several different metrics are used for this purpose, including land-use efficiency, land-use intensity, power density, and land occupation, to name a few. E.g., land-use efficiency in one paper can refer to the land area needed to install a certain capacity for energy generation, whereas another paper considers land-use efficiency as the area needed to generate a certain amount of electricity. Therefore, estimates of land-use requirements quantified with the same metrics vary greatly.  

The variability of the land-use requirements is also rooted in the underlying assumptions regarding the area, power-related component, and time of the chosen metrics. However, a systematized review of all aforementioned assumptions on land-use by renewable energies is absent.

Land-use requirements are often derived from the existing VRES facilities. Hence, their values are influenced by such location-specific factors as climatic conditions, orography, land ownership, among others. As land-use requirements are often integrated into the research that estimates potentials for the future deployment of renewable energy, the influence of those factors is implicitly integrated as well. Hence, the potentials for one region may be estimated by applying the data from another region. Although the application of region-specific land-use requirements could reduce the introduced inconsistencies, known land-use requirements are in its vast majority estimated for the US. Therefore, a compilation that in particular gathers literature on land-use of renewable energies in underrepresented world regions is of high importance.

How to cite: Turkovska, O., Gruber, K., Klingler, M., Klöckl, C., Ramirez Camargo, L., Regner, P., Wehrle, S., and Schmidt, J.: An overview of land-use requirements for solar PV and wind power, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11962, https://doi.org/10.5194/egusphere-egu22-11962, 2022.

EGU22-12420 | Presentations | ERE2.2

An action-oriented approach to make the most of the wind and solar power complementarity 

Sonia Jerez, David Barriopedro, Alejandro García-López, Raquel Lorente-Plazas, Andrés Somoza, Marco Turco, and Ricardo M. Trigo

Solar and wind power curves typically exhibit inverted daily and annual cycles. However, their monthly anomalies show both positive and negative low correlation values across Europe, which compromises the effectiveness of their integration in the energy grid. This is because the well-known asymmetric response of the resources to the main large-scale teleconnection patterns vanishes and/or shows low synchronicity when the compound effect of these patterns is considered, as we show here. So we propose a step-wise method to help narrowing the monthly deviations of the total wind-plus-solar electricity production at the regional level from a given curve (here, the mean annual cycle of the total production), applied here across five continuous European regions but with straight application elsewhere and at other temporal scales. It detects the optimal shares of each power over previously identified sub-regions with homogeneous temporal variability of the monthly anomalies of the wind and solar capacity factors. Results show that, keeping the current total regional shares, just through a smart distribution of the power units, the standard deviation of the monthly anomalies of the total wind-plus-solar production is reduced up to 20% without loss in the mean capacity factor as compared to a base scenario with uniform distribution of the installations. This reduction grows above 50% if the total regional shares also came into the optimization game.

 

Acknowledgments:

This study was supported by the Spanish Ministry of Science, Innovation and Universities – Agencia Estatal de Investigación and the European Regional Development Fund through the project EASE (RTI2018-100870-A-I00), and by the Fundación Séneca – Agencia de Ciencia y Tecnología de la Región de Murcia through the project CLIMAX (20642/JLI/18).

How to cite: Jerez, S., Barriopedro, D., García-López, A., Lorente-Plazas, R., Somoza, A., Turco, M., and Trigo, R. M.: An action-oriented approach to make the most of the wind and solar power complementarity, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12420, https://doi.org/10.5194/egusphere-egu22-12420, 2022.

EGU22-12710 | Presentations | ERE2.2

Is renewable energy resources availability decisive for Energy Cooperatives' existence? A spatiotemporal analysis 

Maria Luisa Lode, Luis Ramirez Camargo, and Thierry Coosemans

Increased adoption of local renewable energy sources and larger active participation of energy end-consumers in the energy transition are attributed to Energy Cooperatives (ECoops). These are the most common organizational form of energy communities, which are currently one of the key strategies of the European Union to advance the energy transition. Getting to understand better which factors facilitate and benefit the existence and development of ECoops might help to foster a larger adoption of energy communities. Most studies addressing this are of qualitative character, while large-scale quantitative studies trying to understand general trends are scarce. None of them has paid attention to the impact of the type and quality of renewable energy resources (RES)  available at the location of ECoops.

We conduct an exploratory spatial data analysis on the NUTS2 and NUTS3 regions levels to explore which characteristics of RES availability co-occur with the presence of ECoops across Europe. The characteristics of RES availability include total solar irradiation, average wind speeds, complementarity between solar and wind resources as well as resource droughts. We use multiple decades of ERA5 and ER5-land data to determine the average RES characteristics for each NUTS region. The location of ECoops is derived from the database on ECoops by ReScoop.

Results contribute to the understanding if there is any spatial relationship between the existence of ECoops and RES availability. Clusters of NUTS regions with rather low RES availability and flourishing ECoops, as well as regions with good resources and a low number or no ECoops, are identified. Further, the study identifies hot-spots that require special attention to become auspicious for energy communities due to the rather challenging conditions of RES availability.

How to cite: Lode, M. L., Ramirez Camargo, L., and Coosemans, T.: Is renewable energy resources availability decisive for Energy Cooperatives' existence? A spatiotemporal analysis, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12710, https://doi.org/10.5194/egusphere-egu22-12710, 2022.

EGU22-12759 | Presentations | ERE2.2

Mesoscale modelling of the spatio-temporal variability in wind and solar time series for power and energy system applications 

Graziela Luzia, Andrea N. Hahmann, and Matti J. Koivisto

Renewable energy generation variability impacts several areas in power and energy systems, such as optimal energy system planning, power system vulnerability to storm shutdowns, and available voltage stability support. For this reason, meteorological data able to represent fluctuation in solar irradiance and wind speed is crucial. For such studies, it is a requirement that time series provided by weather models are capable of simulating temporal dependencies, such as autocorrelations, but also temporal correlations among locations. However, most weather model developments for wind energy studies seem to focus their validations on the mean values of solar and wind variables or the skill of numerical weather prediction forecasts.

In this context, this work aims to contribute to modelling the spatio-temporal variability in solar and wind time series over Northern Europe by addressing the following questions: How does the interaction between the mesoscale model and its forcing impact the quality of generated time series for power and energy system purposes? How do model initialisations affect the temporal dependencies? The Weather Research and Forecasting (WRF) model generates the simulated time series for various sites with available measurements. Different model configurations are tested, such as domain size, placing and nesting, and the impact of abrupt versus smooth initialisation.

How to cite: Luzia, G., Hahmann, A. N., and Koivisto, M. J.: Mesoscale modelling of the spatio-temporal variability in wind and solar time series for power and energy system applications, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12759, https://doi.org/10.5194/egusphere-egu22-12759, 2022.

Deep geothermal energy is regarded as an important renewable source of power and heat that has the potential to occupy a central place in a just energy transition as part of the UK’s strategy to meet its Net Zero Commitment.  Access to deep geothermal energy bears some similar risks to shale gas development, a practice met in the UK with much public concern and controversy. Existing research on shale gas has established that risk perceptions, notably around induced seismicity, were of particular importance to the public and in local communities where exploration was proposed. Furthermore, the UK government’s approach to regulating induced seismicity across these two industries has not been uniform. It thus remains unclear how the exploitation of geothermal energy will be received more broadly, and how the government might regulate geothermal activity . 

The exploration and exploitation of geothermal energy is intrinsically technical, yet geothermal developments also include social, spatial and political aspects that have so far been neglected in geothermal energy research. As such, in this paper we draw on multiple data sets, including interviews with government, industry and public stakeholders to compare and contrast governance approaches and public risk perceptions tied to shale gas and geothermal energy production in the UK. We suggest some key differences between the shale and geothermal energy industries in terms of technologies, social acceptance and implications for climate change. Yet we also point to divergent issues, in terms of a lack of a cohesive regulatory framework or guidance for community engagement tied to geothermal energy, and how this might negatively impact public perceptions of the practice, thwarting social acceptance. In closing, we make recommendations for establishing more systematic geothermal regulations and policies aimed at creating consistent, environmentally sustainable and socially just practices in the industry moving forward. 

How to cite: Ryder, S., Rohse, M., and Abesser, C.: Risk perception, regulation, community engagement and acceptance: Navigating the legal and social UK geothermal landscape, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2328, https://doi.org/10.5194/egusphere-egu22-2328, 2022.

Geothermal ressources for heat and power generation are an integral part of the transition from fossil fuels to clean and sustainable energy and have been successfully developed in the North Alpine Foreland Basin since the 2000s. The timeframe since the first exploration activities is rather short and data on induced changes in the aquifer is scarce. It might be a good idea to take a look at the development classical groundwater ressources for comparison, even more so, if the geothermal facility also includes a net withdrawal for eg. medical or wellness applications.
Most deep groundwater aquifers are of vital importance but strongly limited as ressources for drinking water. Depletion of these aquifers is easy to assess and usually handled well in the legislative procedure. The development of the hydrochemical state and the possible occurrence of mobile persistent trace pollutants, on the other hand, is hard to predict. Here, the current assessment framework which is based on the protection of the aquifer by impermeable layers falls short: together with groundwater renewal the age structure of the aquifer has to change. Old groundwater is replaced by more recent groundwater. Substances with a similar transport behaviour as wateritself will sooner or later show up in these deep groundwater ressources. Examples from bottled water producers show that the development from a state without any traces of anthropogenic substances to a the first occurrence is sharp and irreversible.
Future development concepts for deep groundwater aquifers have to take the age structure of the aquifer into account when defining acceptable withdrawal rates, groundwater protection zones and technical operations which influence the integrity of the protecting layers.
We present a conceptual assessment and monitoring concept for deep groundwater aquifers which includes the risks posed by unconventional uses of the impermeable layers (foundations, corroded wells, geothermal, ...).

How to cite: Baumann, T.: Assessment of the hydrochemical integrity of deep geothermal aquifers - Lessons from bottled water producers, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4279, https://doi.org/10.5194/egusphere-egu22-4279, 2022.

EGU22-4288 | Presentations | ERE2.3

A feasibility assessment of the implementation of a minewater heating system on the Durham University estate. 

Michael MacKenzie, Jeroen van Hunen, and Jon Gluyas

Minewater heating is a form of shallow geothermal energy provision that exploits abandoned subsurface mines that have since flooded after mining activity ceased. Groundwater that occupies the void space left from material extraction is warmed to ambient temperatures by heat transfer exchanges with the surrounding rock.

By using ground source heat pumps, the temperatures of these waters can be lifted to those suitable for domestic heat use, with efficient electrical input.  

An assessment to determine the feasibility of the implementation of a minewater heating system on the Durham University campus is currently in progress, with results due in March 2022. The system would use abandoned coal mines of the Durham Coalfield to heat several student accommodation buildings built above.

Assuming abstraction and reinjection of the minewater, we investigated the available heat resource using a numerical modelling tool developed at Durham University. This tool modelled the minewater flow through the void space of the mines and thermal interaction with the surrounding rock.

A new methodology was developed for the digitisation of historic mine plans provided by the UK’s Coal Authority, which have then been modelled to provide 3D visualisation of technical factors critical to the success of such a project. Various configurations have been tested, and results indicate over 11 million kWh of heat in place resource available, at temperatures of 14°C. This heat in place figure is likely an underestimation of the resource as records indicate deeper seams were also mined at the locality.

 

We subsequently carried out an assessment of the economic feasibility. If a decentralised configuration were chosen for the design, it would be advisable to focus on three buildings with the most student rooms. Initial costs would be high, driven mainly by the associated costs of drilling injection and extraction wells. As the target seams are relatively shallow (145m for extraction and 70m for injection), smaller wells could be used, costing roughly £40,000 per well. If a centralised design were used, costs would be reduced by drilling fewer wells. However, retrofit work to replace the original centralised gas infrastructure connections could induce significant cost and disruption. However, running costs would be low, and emissions savings from not using gas boilers would be significant; peak daily CO₂ emissions from gas were 17,992 kg in 2019.

Finally, to assess the internal policy structure of the university and the feasibility of permission to be granted for the project, a social acceptance study was undertaken with key members of the university’s Board of Directors. Considering the project through the concept of risk, obstacles to implementation were identified, and potential policy solutions were developed.

This study provided insights into current institutional views on engaging with innovative energy technologies. Future work may benefit from understanding these to produce relevant solutions to mitigate them in their feasibility studies.

How to cite: MacKenzie, M., van Hunen, J., and Gluyas, J.: A feasibility assessment of the implementation of a minewater heating system on the Durham University estate., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4288, https://doi.org/10.5194/egusphere-egu22-4288, 2022.

Green hydrogen produced through electrolysis using renewable energy has the potential to decarbonize many sectors by replacing fossil fuels. Although production is currently marginal, green hydrogen projects are initiated and assessed all around the globe, ranging from small energy systems to large-scale production units. Previous studies have identified a wide range of key stakeholders that influence the diffusion of green hydrogen technologies. However, an understanding of the overall complexity of the emerging hydrogen sector regarding techno-economic, social, and environmental aspects is needed. The main objective of this study is to provide a depiction of an emerging sustainable technology sector by integrating various stakeholders’ perspectives. Based on this mapping key mechanisms that foster or hinder the production of green hydrogen will be identified. To perform our study, we chose a green hydrogen production project at the Hellisheiði geothermal power plant (Iceland) to construct a causal loop diagram (CLD) of the Icelandic green hydrogen production sector. Seven semi-structured interviews and one e-mail interview were conducted with relevant stakeholders. The National Innovation System was taken as a conceptual model in order to encourage the participants to answer in a systemic manner. Variables and causal links were then extracted from the interview transcripts using a coding process adapted from the literature. An overall CLD was constructed, showing the dynamic complexity of the system. The results show that mobility and export are the main sources for enhanced demand. Since most power companies in Iceland are state owned, green hydrogen supply comes mainly from energy companies, and strongly depends on political support. The importance of civil society, especially concerning the topics of nature protection and climate awareness, is also depicted. Additionally, a range of social, technical, and economical factors are identified, as well as their impact on the system’s behavior. The diagram allows for comprehension of stakeholders’ expectations and concerns with their potential consequences on the diffusion on green hydrogen technologies. The use of system dynamics and causal loop modelling provides a comprehensive view on the problem and helps to address issues that could be overlooked without it. Some of these causal chains could potentially lead to policy failure if not addressed early enough. The findings can be used to enhance cooperation between stakeholders and guide decision-making processes.

How to cite: Perruchoud, R., Vögeli, G., and Finger, D. C.: Opportunities and drivers for green hydrogen production from renewable energy: Constructing of a causal loop diagram from stakeholders perspective in Iceland., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5957, https://doi.org/10.5194/egusphere-egu22-5957, 2022.

EGU22-6292 | Presentations | ERE2.3

The potential of geothermal district heating in the city of Banja Luka, Bosnia and Herzegovina 

Petar Gvero, Einar Jón Ásbjörnsson, David Finger, Milovan Kotur, Xavier Musonye, Danijela Kardas, and Milan Pupcevic

The geothermal energy potential in the Balkan area includes locations in Slovenia, Hungary, Romania, Bulgaria, Serbia and Bosnia and Herzegovina. Although the potential for clean, cost-efficient, and renewable geothermal heating energy is well known, exploitation of geothermal sources is still hampering. According to the existing surveys, mappings, and calculations, Banja Luka area is built on a geothermal underground reservoir, which is currently only used for balneology purposes. Due to the specific geographic position and the emissions from the existing district heating system based on biomass and heavy petrol, the air quality in Banja Luka is severely mitigated during the winter season. In order to assess the potential and the challenges of geothermal district heating for Banja Luka numerical energy modeling, life cycle analysis of the energy systems, and stakeholder assessment are currently being performed. These activities are currently carried out in the frame of international cooperation between the University of Banja Luka, Reykjavik University in Iceland, and the Energy Institute at the Johannes Kepler University in Linz, Austria. Our preliminary results indicate that geothermal district heating in Banja Luka can provide a reliable, cost-efficient, clean, renewable, and domestic heat supply to the residents of Banja Luka. Furthermore, our initial findings indicate that that the main challenges in developing geothermal district heating in Banja Luka are complex bureaucratic processes, high skepticism among the decision-makers, and a high degree of conflicting interests among relevant stakeholders. This presentation will conclude by highlighting how geothermal district heating in Banja Luka falls in line with the concepts of the new EU Green Deal and the obligations of Bosnia and Herzegovina according to Energy Community Treaty.

How to cite: Gvero, P., Jón Ásbjörnsson, E., Finger, D., Kotur, M., Musonye, X., Kardas, D., and Pupcevic, M.: The potential of geothermal district heating in the city of Banja Luka, Bosnia and Herzegovina, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6292, https://doi.org/10.5194/egusphere-egu22-6292, 2022.

EGU22-8639 | Presentations | ERE2.3

Diffuse emission of 3He and 4He and thermal energy released in volcanic systems 

Mar Alonso, Nemesio M. Pérez, Pedro A. Hernández, Eleazar Padrón, Gladys Melián, Fátima Rodríguez, Germán Padilla, José Barrancos, María Asensio-Ramos, Thrainn Fridriksson, and Hirochika Sumino

Active or recent volcanism indicates the presence of high-enthalpy resources at depth. This is obvious when visible surface emanations as volcanic plumes, fumaroles, solfataras or bubblings appear. However, visible manifestations of deep anomalies do not always appear at the surface, making more difficult the detection of possible geothermal reservoirs. In this work, we propose that in areas where there are no visible emanations, it is possible to make an estimation of the associated thermal energy of the reservoir. For this purpose, 15 volcanic systems located in different geotectonic environments have been studied, where diffuse 3He and 4He emission and thermal energy released have been calculated. This work has focused on the study of diffuse He emissions due to its chemically conservative properties as a noble gas, helium is an excellent indicator of magmatic activity allowing to delimit permeable areas of preferential ascent of deep origin fluids. Two different methodologies for the calculation of diffuse 3He and 4He emissions have been proposed. In addition, the thermal energy released has been calculated following the methodology proposed by Chiodini et al., 2001. A consistent observation across the entire study is that those areas with relatively high diffuse 3He and 4He emissions also show relatively high thermal energy released values, suggesting a clear and positive relationship between the parameters. This implies that, in volcanic areas where no visible geothermal emanations are observed, and therefore, the inability to sample, but anomalies in the diffuse 4He emission are present, there should be a deep thermal anomaly associated, and therefore, a possible geothermal reservoir.

 

  • Chiodini, F. Frondini, C. Cardellini, D. Granieri, L. Marini, G. Ventura. CO2 degassing and energy release at Solfatara volcano, Campi Flegrei, Italy. J. Geophys. Res. 106 (B8) (2001) 16213e16221, https://doi.org/10.1029/2001JB000246.

How to cite: Alonso, M., Pérez, N. M., Hernández, P. A., Padrón, E., Melián, G., Rodríguez, F., Padilla, G., Barrancos, J., Asensio-Ramos, M., Fridriksson, T., and Sumino, H.: Diffuse emission of 3He and 4He and thermal energy released in volcanic systems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8639, https://doi.org/10.5194/egusphere-egu22-8639, 2022.

EGU22-10599 | Presentations | ERE2.3

Characterization of Atotonilco geothermal area, Veracruz, Mexico 

Emma Daira Baizabal Gómez, Mariana Patricia Jácome Paz, Daniel Pérez Zarate, Juan Ramón de la Fuente Rivera, and Rosa María Prol Ledesma

Geothermal high enthalpy resources can be an important potential source to satisfy Mexico’s energy requirements ; nevertheless, low and moderate enthalpy resources may contribute through the direct uses to replace fossil fuels. In both cases, the exploitation of geothermal resources are an important factor inthe energy transition that the whole world strives to achieve. Furthermore, it has an important social impact in the communities, where the use of geothermal energy can bring considerable benefit. In this work, a geothermal characterization with a geographic approach is presented for the “Atotonilco” (hot water in native language) town in Calcahualco municipality of Veracruz state (eastern México). The surface manifestations in the area are calcium-carbonate warm springs with flows from 1 to 12 liters per second. The temperature at depth was estimated between 70°C and 74°C with the calcedony geothermometer, which corresponds to a low enthalpy resource. A preliminary conceptual model of the Atotonilco geothermal area, using all data and a list of the feasible direct uses applications are proposed. These proposals consider the social and economic characteristics of the study area that were observed during the field work. The recommended actions include dissemination of the results of this research, as an important contribution to the development of geothermal resources in Atotonilco town.

Keywords: Geothermal energy, environmental geography, renewable energy, direct use, geochemical exploration, geoscience dissemination.

Acknowledgment

Thanks to Dr. Ramón Espinasa Pereña for his technical support during the field work. Thanks to the Laboratory of Analytical Chemistry of the Institute of Geophysics, UNAM, especially to the QFB Olivia Cruz, M in Ing. Alejandra Aguayo and QFB Omar Neri, for carrying out the chemical analyzes of water presented here.

How to cite: Baizabal Gómez, E. D., Jácome Paz, M. P., Pérez Zarate, D., de la Fuente Rivera, J. R., and Prol Ledesma, R. M.: Characterization of Atotonilco geothermal area, Veracruz, Mexico, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10599, https://doi.org/10.5194/egusphere-egu22-10599, 2022.

Increasing the share of renewables in the heating sector is crucial to reduce CO2-emissions. Using the shallow geological subsurface for heating and cooling is part of the solution. Especially the use of shallow geothermal energy for heating is widely applicable. An intensive but at the same time sustainable shallow geothermal use is essential to avoid interactions between geothermal users with a resulting decrease in system efficiency or competing use with other subsurface usages, e.g. groundwater provision. The intensive thermal use of the shallow subsurface is generally controlled by monitoring of subsurface or groundwater temperatures. Induced changes of subsurface or groundwater temperatures are required to not exceed specific thresholds over time. However, the urban subsurface is exposed to different sources of temperature impacts which need to be considered during the long term subsurface or groundwater temperature monitoring to determine absolute changes. This is especially true for new urban quarters. Elevated groundwater temperatures in densely populated areas in comparison to the rural surroundings, often referred to as groundwater urban heat islands, have been observed and investigated over decades. However, only little information is available about the formation of heat islands over time and yet, its effects are hardly considered in groundwater temperature monitoring practice. To overcome this lack of knowledge, this study follows an innovative approach by coupling simulated elevated groundwater temperatures for a densely settled quarter with empiric groundwater temperature data. Therefore, heat losses from buildings and their contribution to the formation of groundwater urban heat islands over time are analysed for a refurbished quarter with a building stock of 150 houses and intensive use of shallow geothermal energy in Cologne, Germany.  To simulate heat losses from buildings, different scenario analyses with houses of varying insulation standards are performed using a building physics software. Obtained results were then implemented into a groundwater flow model to evaluate the impact on underground temperatures over time and compared with measured data of the same area. Simulation results reveal that the geothermal heating activities impact the groundwater temperatures more than the monitoring data suggests.

How to cite: Hastreiter, N. and Vienken, T.: An innovative temperature monitoring approach to ensure the sustainable use of shallow geothermal energy on quarter scale, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11801, https://doi.org/10.5194/egusphere-egu22-11801, 2022.

EGU22-13573 | Presentations | ERE2.3

CROWDTHERMAL - developing financial and social engagement strategies for geothermal projects 

Balazs Bodo, Isabel Fernández Fuentes, Márcio Tameirão Pinto, Ronald Kleverlaan, Georgie Friederichs, and Christina Baisch

CROWDTHERMAL is a project funded under the European Union’s Research and Innovation programme Horizon 2020 – Grant Agreement n°857830. It is a is a 36-month project led by the European Federation of Geologists (EFG), with a consortium of 10 partners from 7 different European countries.

The main purpose of CROWDTHERMAL is to support the uptake of geothermal energy projects in Europe. To reach this goal it is necessary to involve and empower the public in the development of such projects, and CROWDTHERMAL has developed social engagement strategies that were validated in three different case studies over the project’s implementation: Hungary, Spain, and Iceland.

In addition to the social aspects, the project produced numerous reports on alternative financing schemes, such as crowdfunding, and risk mitigation tools to be implemented in the development of a geothermal project. These tools aim to increase financial security and attract investments in geothermal energy in Europe – contributing to the EU Green Deal goals for 2050.

In 2022, the final year of CROWDTHERMAL, the consortium is focused on the development, improvement, and deployment of a set of Core Services. The Core Services are a result of reports, analysis and studies developed and validated along the project that are addressed to different target audiences: the community of citizens, geothermal project developers, and local authorities. These outputs are the following: 1) Assistance on the development of an economic model of a geothermal project; 2) Step plan regarding finance and risk mitigation tools to be considered; 3) Meta-database of current geothermal projects in Europe; 4) Self-learning materials on geothermal energy, alternative finance, social aspects, and risk mitigation; and 5) An online decision tree algorithm: a workflow with a sequence of questions that follow a logical order, with the purpose of selecting which strategies are the most appropriate for a specific phase of a geothermal project related to social, environmental, resource risk and financial factors.

These CROWDTHERMAL Core Services are designed to continue beyond the EC-funded period. From these pre-defined outputs of the project, the partners will further elaborate the exploitation strategy and transform some of them into added value services that will be commercialized, with an embedded consultancy from experts in CROWDTHERMAL consortium. For example, communities can be guided on how to transform community initiatives into geothermal projects through co-financing; geothermal project developers will learn more about mechanisms for social acceptance and engagement, as well as economic modelling of a geothermal project; and public authorities will be able to bridge private initiatives and the community – fostering the uptake of geothermal energy in Europe.

How to cite: Bodo, B., Fernández Fuentes, I., Tameirão Pinto, M., Kleverlaan, R., Friederichs, G., and Baisch, C.: CROWDTHERMAL - developing financial and social engagement strategies for geothermal projects, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13573, https://doi.org/10.5194/egusphere-egu22-13573, 2022.

EGU22-10 | Presentations | ERE2.4

Geothermal research in Uzbekistan 

Irina Sidorova

A large scientific project is being implemented in Uzbekistan (2019-2021) to study Heat Flow Density anomalies оn the territory of the Republic. Long-term studies by geophysicists of the Institute of Geology and Geophysics have allowed the creation of a geothermal database and a new Heat Flow distribution map. Comprehensive geophysical work is being carried out, including gravimetric, seismic and magnetotelluric studies in three areas (1) Muruntau, (2) Krasnogorsk, (3) Bayangora. According to the constructed gravimetric maps, zones of decompression and faults were identified. Low and high velocity areas have been identified from seismic sections. Magnetotelluric sounding made it possible to identify conduction zones that correlate with anomalous Heat Flow Density. Based on the complex of geophysical data, a three-dimensional model of the deep structure was built for the promising area ​​Muruntau. The locations of wells for the construction of a geothermal station have been determined.

How to cite: Sidorova, I.: Geothermal research in Uzbekistan, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10, https://doi.org/10.5194/egusphere-egu22-10, 2022.

EGU22-1578 | Presentations | ERE2.4

S-wave velocity structure in Kenyan potential geothermal fields inferred from ambient seismic noise data analysis 

Chanmaly Chhun, Takeshi Tsuji, and Tatsunori Ikeda

To reveal the seismic velocity structure and anisotropy in potential geothermal fields, Kenya, we analyzed ambient noise data from nine vertical components of broadband seismometer stations. Our analysis is based on the cross-correlation of ambient noise data by extracting phase velocity dispersion curves via the zero-crossing method and then applying surface-wave inversion to estimate S-wave velocity structures. The results for both phase velocity and S-wave velocity structures show a clear velocity contrast in volcanic systems (i.e., Korosi-Paka-Silali) in the Kenyan Great Rift (KGR). The phase velocity structure (i.e., 1400 - 2200 km/s) significantly drops in the Silali trachytic shield volcano and the Pleistocene Paka shield volcano. Such velocity contrasts are also observed where they are parallel and perpendicular to the geological structure of the KGR. Most decreasing seismic velocities are normal to abundant faults and fractures in the inner trough of the KGR. This direction is aligned with local extension direction, linked to divergent plate boundaries. The resulting S-wave velocity structures further disclose the anomaly features that can indicate permeable or non-permeable layers. Permeable layers are extensively existing that can provide potential geothermal fluid accumulations. Most potential areas are below the rift floor between the Paka and Silali volcanoes, involved in intense faulting/fractures and young porous rocks (i.e., intercalated pyroclastic, trachyte, and basalt lavas). The lithocap zones are mostly less than 1 km. The magma heat sources are most likely deeper than 3 km at Paka and 4 km at Silali. Therefore, geothermal reservoirs can be relatively interconnected due to shallow magma-volcanic systems, existing groundwater, porous volcanic rocks (i.e., pumice) and intensive fractures controlled by main graben faults in the KGR, regardless of impermeable volcanic rocks or (ore) mineralization in this study area. This work was supported by Leading Enhanced Notable Geothermal Optimization (LENGO) of SATREPS (JICA-JST), Japan.

Keywords: ambient noise, S-wave velocity, seismic anisotropy, shallow magma-reservoir systems, rifting and volcanism

How to cite: Chhun, C., Tsuji, T., and Ikeda, T.: S-wave velocity structure in Kenyan potential geothermal fields inferred from ambient seismic noise data analysis, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1578, https://doi.org/10.5194/egusphere-egu22-1578, 2022.

Multiple operators use geothermal wells in Lower Bavaria and Upper Austria for balneological (medical and wellness) applications and for energy and/or heat mining purposes. These applications depend heavily on the well‘s hydrochemical and geophysical stability (mineralization, pressure, temperature).

At the moment, wells are submitted to inspection once a year, which includes the analysis of ions, pH, pressure, temperature etc. These „offline“ analyses, while covering a large set of parameters, obviously fail to show intra-annual variability within the measured parameters. On the other hand, some geothermal wells are being monitored quasi-continually. These „online“ sensors, however, only cover a small set of selected parameters, such as electric conductivity, temperature and pressure.

This study aims at forecasting hydrochemical and physical stability based on annual measurements by assessing the degree of intra-annual variability covered or neglected by the yearly measurements. The results are required for a sound assessment of possible adverse effects of other exploration activities and short term variations of the withdrawal rates reflecting the demand for heat, energy and/or spa water. To do this, we followed the concept of virtual sensors and their correlation to detailed yearly measurements.

We found that, while annual measurements, when taken approximately in the same season of the year, do match the data sampled online quite well, intra-annual variability at the examined wells was quite strong for some parameters and not represented by the offline data. Thus, annual data can be used to make predictions regarding long-term variability. In order to forecast intra-annual variability, higher temporal resolution is necessary. While not a replacement for the detailed analyses, the virtual sensors presented here provide a robust method to trigger further actions.

How to cite: Dietmaier, A. and Baumann, T.: Forecasting high resolution variations in deep geothermal wells based on low resolution measurements utilizing virtual sensors, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2634, https://doi.org/10.5194/egusphere-egu22-2634, 2022.

EGU22-2751 | Presentations | ERE2.4

Gas phase induced carbonate precipitation - experimental proof and model verification 

Lilly Zacherl and Thomas Baumann

Successful development of the geothermal energy sector requires an understanding of the geological systems and processes that occur within. In the North Alpine Foreland Basin, a hydrogeothermal play type, most sites are affected by inorganic precipitates which reduce the efficiency and safety of plants. Although the gas concentrations in the geothermal waters are generally low, any formation of an independent gas phase induces carbonate precipitation. A quantitative prediction of the precipitates, however, is not yet possible because kinetic data for gas phase induced precipitates is not available.

To address this issue laboratory experiments were run where a gas (CO2, air) was induced into a column containing an aqueous solution (tap water, water with high salinity). The scalings produced were analyzed by Raman spectroscopy, a mass balance of the process including the dissolving of scaling by inducing CO2 into the scaled column was based on ion chromatography data. The experiments show that by injecting air into tap water a full stripping of CO2 occurs which is the experimental proof of the disruption of the lime carbonic acid equilibrium by gas bubbles. The salinity of the initial solution influences - in agreement to previous investigations - the polymorph: only aragonite crystals were detected in tap water (ionic strength: 8.5e-03 mol/L), whereas only calcite crystals showed up in tap water with additional 0.2 g/L NaCl (ionic strength: 1.2e-02 mol/L).  Precipitation was inhibited when 120 g/L NaCl were added to the tap water before stripping (ionic strength: 2.1 mol/L).

The data were evaluated using a combination of hydrogeochemical calculation and precipitation kinetics (PhreeqC) with gas bubble kinetics (Python) and PEST++ for the final parameter adjustment. We successfully modelled the process of stripping, CO2-injection and the experiments with higher salinity with one model.  This experimental proof of the gas phase induced carbonate precipitation and the new adequate description of the scaling process is a further step to predictive maintenance for geothermal sites and a more reliable holistic site assessment during the planning stage. Together, this improves the sustainability and the attractiveness of the geothermal energy sector to investors.

How to cite: Zacherl, L. and Baumann, T.: Gas phase induced carbonate precipitation - experimental proof and model verification, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2751, https://doi.org/10.5194/egusphere-egu22-2751, 2022.

EGU22-3556 | Presentations | ERE2.4

Geospatial analysis of thermal and structural data for the characterization of shallow geothermal systems: the Parco Naturalistico delle Biancane (Tuscany/Central Italy) study case 

Federico Rabuffi, Paola Cianfarra, Massimo Musacchio, Malvina Silvestri, Francesco Salvini, and Maria Fabrizia Buongiorno

Geothermal energy plays a major role in the energy transition context. This presents a constant increasing rate in electricity generation, even if it today represents a smaller part of the renewable energy package. To sustain this natural resource, it is necessary to better understand the geotectonic framework of key places that are historically relevant in terms of innovation, exploration and development of geothermal energy resources. These places represent strategic cases study: i) to better understand the surface manifestation related to a geothermal area; ii) to test new methodologies that can help in the monitoring and identification of new natural resource; iii) to better understand the geodynamic context that characterizes the geothermal area in terms of thermal anomalies, soil alteration, stress field, and fracture distribution inducing secondary permeability.

This work is linked to a PhD project focused on Parco Naturalistico delle Biancane (PNB) area, in southern Tuscany (Italy), the main Italian geothermal region, where geothermal energy production started in 1916.

The aim of the project was to merge original remote sensing techniques and classical structural geology field data to improve the knowledge of the geological setting of PNB geothermal area. Deepening the confidence on this methodological approach, some considerations on its exportability has been carried out. According to the methodology a remote sensed analysis has been performed, leading us to highlights the correlation between the morpho-geological and geothermal features, in terms of thermal anomalies. An automatic lineaments detection has been done by analyzing Digital Elevation Model (DEM) and Land Surface Temperature (LST) maps derived from Landsat8 satellite data. The results obtained by this analysis highlights the NE-SW lineaments domain as the most relevant from both point of view: thermal and structural. The analysis shows a good relationship between the two datasets and allowed to understand how tectonic setting acts on shallow fluid circulation. These data have been compared with the field structural data including faults, joints, fault-synthetic cleavage, shear fractures and beddings. A multi scale spatial analysis has been conducted and includes: the structural data distribution, density of the geo-morphological lineaments derived from the DEM, LST maps, high resolution surface temperature map, and surface classification map (based on ground spectral data acquired in the field). In this spatial analysis each dataset has been considered as a single, independent layer of information, and the spatial distribution of the “anomalies”, recognized in every layers, allowed us to identify and to define the areas that are strategically relevant to understand how a shallow geothermal system works and how to improve it.

How to cite: Rabuffi, F., Cianfarra, P., Musacchio, M., Silvestri, M., Salvini, F., and Buongiorno, M. F.: Geospatial analysis of thermal and structural data for the characterization of shallow geothermal systems: the Parco Naturalistico delle Biancane (Tuscany/Central Italy) study case, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3556, https://doi.org/10.5194/egusphere-egu22-3556, 2022.

EGU22-3608 | Presentations | ERE2.4

Performance analysis of deep borehole heat exchangers in the Pannonian Basin 

Eszter Békési, Adrienn Szekszárdi, Kristóf Porkoláb, Krisztina Tóth, and Mátyás Gáti

Primarily due to the lack of production of geothermal fluids from subsurface aquifers, closed-loop geothermal systems are promising solutions for sustainable and cost-effective exploitation of geothermal energy. Compared to conventional or unconventional open-hole geothermal systems, the performance of deep borehole heat exchangers (DBHE) are relatively low. However, DBHEs may become favorable choices in certain areas due to the significantly lower exploration risks and their potential to be constructed in abandoned deep boreholes. We investigate the thermal performance of DBHEs in the Pannonian basin, exhibiting one of the hottest regions within Europe, with an average geothermal gradient of ~45 °C/km. We analyze the effect of various geological and technical parameters on the resulting outflow temperatures and output thermal powers in order to find the optimal sets of parameters for the long-term sustainable operation of DBHEs in the Pannonian basin. We approximate the performance of coaxial DBHEs through finite-element numerical modelling using the FEFLOW software. We construct the reference model in a geological environment representative for the Great Hungarian Plain based on information from well logs and literature data. The most important geological parameters we consider in the parameter tests include the geothermal gradient, lithologies, and the presence and significance of natural groundwater flows in the surroundings of the DBHE. Furthermore, we test the influence of various technical and operational parameters such as the type of working fluids, the depth of the DBHE, the thermal conductivity of the tubes, and the temperature and flow rate of the injected fluids. We predict the thermal output for the period of 10 years in order to find realistic parameter combinations that can facilitate sustainable production and reveal the most critical parameters that influence system performance in Pannonian basin settings. These results can help estimating system performance in case of actual geothermal projects and can be used as input parameters for economic calculations.

How to cite: Békési, E., Szekszárdi, A., Porkoláb, K., Tóth, K., and Gáti, M.: Performance analysis of deep borehole heat exchangers in the Pannonian Basin, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3608, https://doi.org/10.5194/egusphere-egu22-3608, 2022.

Geothermal energy is considered as one of the renewable energy resources to meet the world's growing low-carbon energy demand. There are increasing number of oil wells to be abandoned and these wells could be potentially retrofitted to geothermal wells for sustainable purpose. There have been some studies and practices on retrofitting oil wells, but most of the existing retrofitting methods suffer from either low efficiency or high cost. In this study, we designed and modelled a novel retrofitting pattern to a single well featured with enhanced reservoir system (ERS). We established numerical models of ERS in abandoned oil reservoirs configured with a vertical well. We simulated the effects of reservoir initial oil saturation, thickness, permeability and different ERS designs on the production temperature and output power after 50 years. We found these effects have positive feedback on the production temperature and output power. In addition, we also modeled the temperature effect on oil-gas-water relative permeability as it would highly affect the oil viscosity and mobility in the oil reservoir. Moreover, through sensitive analyses of this retrofitted single well and the traditional doublet geothermal well, we found the retrofitted single well in our study could be as high as that from doublet geothermal well, implying that one single abandoned oil well could work either for direct use or power generation with economic yield but little retrofitting investment. Lessons learned in this study might also be applied to other geothermal scenarios, such as enhanced geothermal system.

How to cite: Jia, L., Li, K., and Zhang, C.: Modelling of a retrofitting methodology to revive abandoned oil reservoirs for geothermal exploitation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4982, https://doi.org/10.5194/egusphere-egu22-4982, 2022.

EGU22-5160 | Presentations | ERE2.4

Geothermal potential of small sub-volcanic intrusions in a typical Icelandic caldera setting 

Steffi Burchardt, Mohsen Bazargan, Einar Bessi Gestsson, Erika Ronchin, Hugh Tuffen, Michael J. Heap, Jonathan Davidson, Ben Kennedy, Alex Hobé, Christoph Hieronymus, and Elodie Saubin

Geothermal exploration targets large magmatic intrusions as heat sources because of their size, longevity, and amount of stored energy, but as shallow volcanic plumbing systems comprise numerous smaller intrusions, their geothermal potential warrants consideration. Here, we evaluate the geothermal impact of dykes and sills on caldera-infill rocks. We present geological data and geothermometry on intrusions in the eroded Breiðuvík caldera in Northeast Iceland, which serves as an analogue to the active, and geothermally exploited, Krafla volcano. This data informs 2D finite element models of dyke and sill intrusions that consider heat transfer in porous media. Our results indicate small intrusions create considerable thermal anomalies in their immediate vicinity. These anomalies are larger-magnitude and longer-lasting for individual thick sills and dykes, but networks of smaller sills and dykes emplaced close in time and space can create more widespread thermal anomalies that may be viable economic targets for decades after their emplacement.

How to cite: Burchardt, S., Bazargan, M., Bessi Gestsson, E., Ronchin, E., Tuffen, H., Heap, M. J., Davidson, J., Kennedy, B., Hobé, A., Hieronymus, C., and Saubin, E.: Geothermal potential of small sub-volcanic intrusions in a typical Icelandic caldera setting, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5160, https://doi.org/10.5194/egusphere-egu22-5160, 2022.

EGU22-5300 | Presentations | ERE2.4

Insights into the deep geothermal potential from heat in place calculations of the Berlin/Brandenburg region (Germany) 

Laureen Benoit, Judith Bott, and Magdalena Scheck-Wenderoth

In geothermal exploration, regional 3D geological models, covering the full extent of a sedimentary basin, can be an efficient basis to assess spatial variations in the deep thermal field and related extractable energy. The term “geothermal potential” has been defined in different ways, considering characteristics of an intended geothermal plant and/or the geological reservoir. In this contribution, we concentrate on the latter geological aspects and combine 3D geological with 3D thermal models of the Berlin/Brandenburg region to assess “heat in place” as a quintessential part of the geothermal potential of differently composed geological units.

Our “heat in place” calculations correspond to a volumetric quantification of contained energy distributed across a series of litho-stratigraphic units showing variable thickness, mean temperature, porosity, density, and specific heat capacity. We set special focus on estimating how the calculated heat varies between different thermal models, derived from either purely conductive heat transport or coupled thermal-hydraulic simulations.

As part of the Northeast German Basin, the Berlin/Brandenburg region is known to be potentially suitable for deep geothermal energy exploitation. As this source of energy is not well-established yet, while energy demand from renewables is increasing in the metropolitan area of Berlin, this study aims at contributing to a more efficient decision making on promising sites for geothermal energy production by means of a series of new geothermal potential maps.

How to cite: Benoit, L., Bott, J., and Scheck-Wenderoth, M.: Insights into the deep geothermal potential from heat in place calculations of the Berlin/Brandenburg region (Germany), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5300, https://doi.org/10.5194/egusphere-egu22-5300, 2022.

EGU22-5775 | Presentations | ERE2.4

Electrical geophysical exploration of Lac Abhé’s geothermal system, Djibouti 

Loris Piolat, Yves Géraud, Marc Diraison, Bastien Walter, Nadjib Chibati, Alexiane Favier, Nasradin-Ahmed Ibrahim-Ahmed, and Hassan-Mohamed Magareh

   With the development of geothermal energy in response to the 21st century environmental challenges, it appears that developing geothermal energy in off-grid regions can be a durable investment, providing electricity production and various direct thermal use, and bypassing the usual development of fossil energy in remote areas. In this context, the European Union funded project “Geothermal Village”, within the Horizon 2020 LEAP-RE program, aims to set up the geothermal exploration process for isolated areas in the East African Rift Valley. A field mission at Lake Abhé (Djibouti) was set up in late 2021, with geophysical, geochemical and geological researchers, in order to investigate the hydrothermal features of the area and to assess the feasibility of setting up a small-scale geothermal plant for local communities. 

    The area analysed with electrical resistivity tomographies (ERT) on the lake’s eastern shore is characterized by the presence of linear chains of active travertine chimneys built up on top of fluvio-lacustrine deposits. Chimney alignment orientations match those of the major structural lineaments observed through the basaltic units surrounding the lake. The ERT survey was set up with the aim of describing the main accessible fault structures, getting the resistivity information of the local lithologies to calibrate the magneto-tellurics (MT) survey, and getting the chargeability information to describe alteration processes over the geothermally active zones. Profiles of spontaneous polarization have also been done over the majority of ERT profiles.

    The method used was technically challenging, because of field conditions (especially because of the very low resistivity top layers) and incompatibilities between the data logger and the cable set. To process the data, pre-processing has been implemented with Python scripts, which allows poor quality data to improve, essentially thanks to geometrical reallocation of electrodes. The injection protocol is a randomized Wenner, in order to minimize noise due to near-electrode polarisation with steel electrodes.

    The main results show fault structures, and allow to determine fault offsets for some basalt blocs. It also provides resistivity values for the sedimentary top layer, allowing with the basalt resistivity for a low depth calibration of the MT survey, and a preliminary assessment of the distribution of pore water salinity across the area. The chargeability values are less accurate, showing in the best cases good signatures of the chimney’s structure, and demonstrating in the worst cases the artefact effects of the very conductive values of this salty area. 

    In conclusion, this survey has faced a lot of technical issues, but the results are defining more precisely the previous surveys done on this area. The results can be used for geothermal modelling (describing the fluid path within the reservoir and along the chimney’s structures), water exploration (with the salinity assessment), and geotechnical safety (depth of hardened rock for drilling).

How to cite: Piolat, L., Géraud, Y., Diraison, M., Walter, B., Chibati, N., Favier, A., Ibrahim-Ahmed, N.-A., and Magareh, H.-M.: Electrical geophysical exploration of Lac Abhé’s geothermal system, Djibouti, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5775, https://doi.org/10.5194/egusphere-egu22-5775, 2022.

EGU22-6705 | Presentations | ERE2.4

Plasma Pulse Geo-Drilling as a Low-cost Drilling Technology for Deep-geothermal Energy Utilization: Status and Challenges 

Mohamed Ezzat, Jascha Börner, Daniel Vogler, Volker Wittig, and Martin O. Saar

Geothermal energy can be a limitless and CO2-free energy resource. However, moderate geothermal temperature gradients of ∼30 oC/km in most regions typically require employing so-called "Advanced" or "Enhanced" geothermal systems, called AGS and EGS, respectively, which require reservoirs with temperatures >150 oC. To access such high temperatures, we need to drill deeper than 5 km, i.e., in hard rock. The costs of drilling to such depths, using traditional rotary drilling, increase exponentially with depth and can be up to 80% of the total geothermal project investment. These high drilling costs can be reduced significantly with contactless drilling technologies (e.g., thermal spallation drilling, laser drilling, microwave drilling, and Plasma Pulse Geo-Drilling), as they avoid the lengthy tripping times associated with drill-bit damage.

PPGD uses high-voltage pulses of a few microseconds duration to fracture the rock, thereby drilling without any mechanical abrasion. Future PPGD costs may be as low as 10% of mechanical rotary drilling costs (Schiegg et al., 2015). Our PPGD research addresses two outstanding questions: (1) Understand the fundamental physics of the electric breakdown inside the rock and associated rock fracturing processes, which we investigate numerically (Ezzat et al., 2022, 2021; Vogler et al., 2020; Walsh and Vogler, 2020). (2) Evaluate the PPGD performance under deep-wellbore conditions of  ~5 km (i.e., high pore and lithostatic pressures, and high temperatures). Our ongoing numerical and experimental studies are expected to provide further insights into the applicability of PPGD for geothermal energy utilization.

First, we numerically model the formation of a plasma in rock pores, which constitutes the onset of rock failure during the PPGD process. These numerical models show the significant effect of the pore characteristics on the PPGD process and give insight into how future PPGD operations should be designed. Second, we conduct PPGD physical experiments, where we employ lithostatic pressures of up to 1500 bar, pore pressures of up to 500 bar, temperatures of up to 80 oC, and voltages of up to 300 kV. Concluding these experiments with the associated challenges shall demonstrate whether PPGD is efficient at great depths of up to 5 km. Combining our numerical and experimental results allows optimizing future PPGD operations.

 

References

Ezzat, M., Adams, B. M., Saar, M. O., and Vogler, D. (2022). Numerical modeling of the effects of pore characteristics on the electric breakdown of rock for plasma pulse geo drilling. Energies, 15(1).

Ezzat, M., Vogler, D., Saar, M. O., and Adams, B. M. (2021). Simulating plasma formation in pores under short electric pulses for plasma pulse geo drilling (ppgd). Energies, 14(16).

Schiegg, H. O., Rødland, A., Zhu, G., and Yuen, D. A. (2015). Electro-pulse-boring (epb): Novel super-deep drilling technology for low cost electricity. Journal of Earth Science, 26(1):37–46.

Vogler, D., Walsh, S. D., and Saar, M. O. (2020). A numerical investigation into key factors controlling hard rock excavation via electropulse stimulation. Journal of Rock Mechanics and Geotechnical Engineering, 12(4):793–801.

Walsh, S. D. and Vogler, D. (2020). Simulating electropulse fracture of granitic rock. International Journal of Rock Mechanics and Mining Sciences, 128:104238.

How to cite: Ezzat, M., Börner, J., Vogler, D., Wittig, V., and Saar, M. O.: Plasma Pulse Geo-Drilling as a Low-cost Drilling Technology for Deep-geothermal Energy Utilization: Status and Challenges, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6705, https://doi.org/10.5194/egusphere-egu22-6705, 2022.

EGU22-6919 | Presentations | ERE2.4

The Value of Scientific Machine Learning for Geothermal Applications 

Denise Degen, Mauro Cacace, s.Mohammad Moulaeifard, and Florian Wellmann

For geothermal applications, we aim to obtain an understanding of the physical processes in the subsurface, to predict the geothermal potential reliable. Naturally, the reliability of the prediction of the physical processes directly relates to the reliability of the evaluation of the geothermal potential. Unfortunately, predicting the physical processes reliable is a non-trivial task because of high uncertainties related to these processes. These uncertainties may arise, for instance, from uncertainties of the rock properties (e.g. thermal conductivity, permeability), structural uncertainties, and not considered physical processes.

Considering the various sources of uncertainties yields a high-dimensional and therefore computationally extremely demanding problem that is not solvable even with state-of-the-art high-performance software packages. To address this curse of dimensionality, we employ a methodology, namely the non-intrusive RB method, combining advanced mathematical algorithms and machine learning methods. This method aims to significantly reduce the dimensionality of the problem while maintaining the physical principles. In contrast to other machine learning methods, the method produces interpretable and scalable models, which are crucial to obtain reliable and robust predictions.

In this work, we show how the method constructs surrogate models for coupled geothermal applications, which allow, in turn, the performance of global sensitivity analysis and uncertainty quantifications. Both methods are essential for improving our model understanding. Furthermore, we demonstrate how the method in combination with developments from the field of computer graphics (e.g. NURBS, and subdivision surfaces) can be used to quantify the influence of structural uncertainties on the temperature distribution.

How to cite: Degen, D., Cacace, M., Moulaeifard, s. M., and Wellmann, F.: The Value of Scientific Machine Learning for Geothermal Applications, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6919, https://doi.org/10.5194/egusphere-egu22-6919, 2022.

Interpretation and monitoring of hydraulically active zones in hydro-geothermal wells is critical for assessing the hydraulics of a reservoir and for understanding sustainable reservoir management. For this purpose, flowmeter runs are often performed during injection at the end of short-term pumping tests after the well is completed. Because conventional well designs do not allow direct monitoring in the reservoir once the well is in operation, it is often not clear whether the flowmeter's interpreted injection zones reflect subsequent production zones.

To gain insight into the long-term hydraulic and thermal behavior of geothermal wells in operation, a fiber-optic monitoring system was installed down to 3683 m MD of a geothermal production well in 2019 and below the electric submersible pump into the reservoir in 2021. The well is part of the Schäftlarnstraße geothermal site in Munich, Southern Germany, where six doublets develop the deep hydrothermal Upper Jurassic “Malm” reservoir of the Northern Alpine Foreland Basin. The fiber-optic monitoring system is the first of its kind installed permanently in a geothermal production well. It allows monitoring of temperature (distributed temperature sensing, DTS) and acoustic/strain (distributed acoustic sensing, DAS) continuously in space and time and of pressure and temperature at a fiber-optic gauge located at top of the reservoir at 2748 m MD.

Using DTS technology, the temperature inside the borehole was monitored when the wells at the geothermal site started production. The recorded data were used to analyze the temperature signature at the hydraulically active zones known from previous hydraulically injection tests (flowmeter and temperature monitoring during cold-water injection).

The results show that both hydraulics and production temperature are dominated by an active, karstified zone in the uppermost part of the reservoir of the monitored well. The production of another well of the three doublets geothermal site also strongly affects the temperature distribution in the monitored well. We highlight the importance of continuous monitoring and show the benefit of the permanent fiber-optic monitoring system for sustainable reservoir management.

How to cite: Schölderle, F., Pfrang, D., Meinecke, M., Dirner, S., and Zosseder, K.: Characterization and permanent monitoring of the hydraulically active zones of a deep geothermal reservoir using a fiber-optic monitoring system in a production well in the Bavarian Molasse Basin, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7285, https://doi.org/10.5194/egusphere-egu22-7285, 2022.

EGU22-7690 | Presentations | ERE2.4

Spatial variation of radiogenic heat production related to the crystalline rock types in the western Himalaya-Karakoram region of Pakistan 

Muhammad Anees, Jonas Kley, Bernd Leiss, Bianca Wagner, and Mumtaz Muhammad Shah

The western Himalaya-Karakoram region in northern Pakistan has such hydrothermal features as hot springs and alteration zones. The heat source for these features remains unclear, with suggested mechanisms including radiogenic heat production from minerals, frictional heating caused by shearing along faults, residual heat from Miocene plutonic intrusions, metamorphic heat caused by tectonic collision, and heat advection related to rapid exhumation. In this study, we provide a quantitative estimation of the radiogenic heat production of 158 locations from different crystalline lithologies exposed in the three distinct tectonic domains of the western Himalayan-Karakoram region, i.e., Nanga Parbat-Haramosh Massif, Kohistan-Ladakh Batholith, and Karakoram Batholith. The radiogenic heat production values are calculated from the concentrations of the uranium (ppm), thorium (ppm), and potassium (wt%), which are determined directly in the field using a portable gamma spectrometer on exposures of Proterozoic to Tertiary crystalline rocks. The radiogenic heat production in the Nanga Parbat-Haramosh Massif ranges between 0.72 and 18.46 µWm-3, with mean and median values of 7.12 and 6.74 µWm-3, respectively. Furthermore, Proterozoic gneisses, Tertiary granites, and pegmatites within the Nanga Parbat-Haramosh Massif have mean radiogenic heat production values of 7.86, 10.67, and 6.47 µWm-3, respectively. The radiogenic heat production in the Kohistan-Ladakh Batholith ranges between 0.42 and 5.16 µWm-3, averaging at 2.49 µWm-3 with the highest mean of 3.68 µWm-3 in granites and lowest 0.74 µWm-3 in tonalites. The radiogenic heat production of the Karakoram Batholith ranges between 1.04 and 23.54 µWm-3 with a mean of 5.84 µWm-3 and a median of 4.45 µWm-3. Within the Karakoram Batholith, the Tertiary granites have the highest mean radiogenic heat production of 11.17 µWm-3,  while the lowest mean radiogenic heat production of 2.86 µWm-3 is found in the Cretaceous diorites. Our results suggest that the Nanga Parbat-Haramosh Massif, which is composed of Proterozoic Indian plate basement rocks, has high concentrations of uranium, thorium, and potassium, and consequently a higher radiogenic heat production. This also correlates with similar high radiogenic heat-producing basement rocks exposed in southern India. The presence of high radiogenic heat production in Tertiary granites and pegmatites indicates mobilization and enrichment of incompatible uranium and thorium due to crustal evolution processes related to the Himalayan Orogeny. We suggest that high radiogenic heat production in Proterozoic rocks may have contributed significantly to the enhanced heat flux in the active Himalayan Orogen.

How to cite: Anees, M., Kley, J., Leiss, B., Wagner, B., and Shah, M. M.: Spatial variation of radiogenic heat production related to the crystalline rock types in the western Himalaya-Karakoram region of Pakistan, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7690, https://doi.org/10.5194/egusphere-egu22-7690, 2022.

EGU22-8257 | Presentations | ERE2.4

Injection of geothermal gases at the Kızıldere field: A pre-injection overview 

Taylan Akın, Selçuk Erol, Serhat Akın, Erdinç Şentürk, and Raziye Şengün Çetin

Emissions of greenhouse gases such as CO2 emitted at Turkish geothermal power plants are an obstacle to accepting geothermal energy as green power. However, recent advances in carbon capture and storage technologies have enabled low emissions by re-injecting produced CO2. Carbfix is one of the recent projects where geothermal gases are re-injected into the reservoir. In the Carbfix project, waste gases from Hellisheidi Power Plant are dissolved in effluent water and gas-charged fluid is injected into the basaltic subsurface where some portion of the gases precipitate as minerals. To understand whether the Carbfix methodology can be a standard application for the geothermal industry worldwide, an international research project called Geothermal Emission Control (GECO) was started in 2018. GECO is funded by the EU through the H2020, and the project consortium is consisting of 18 partners from 9 countries across Europe.

GECO aims to develop near-zero-emission geothermal power plants in four sites by providing clean geothermal energy at a lower cost. Kızıldere (Turkey) geothermal field (KGF) is one of the demonstration sites in the project where emission gases are injected into Menderes Metamorphic units. Zorlu Energy and METU are partners of the project from Turkey, and they operate the demonstration and monitoring of CO2 injection in KGF. We present here a geological overview of the Kızıldere injection site, baseline monitoring studies, fluid chemistry of the reservoir, and the predicted chemistry of the gas-charged fluid at the site. Moreover, geochemical simulation conducted for predicting fluid-rock interaction taking place in the geological formation is being assessed.

This work was done in the framework of the GECO Project, funded by the European Union’s Horizon 2020 research and innovation program under grant agreement No. 818169.

How to cite: Akın, T., Erol, S., Akın, S., Şentürk, E., and Şengün Çetin, R.: Injection of geothermal gases at the Kızıldere field: A pre-injection overview, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8257, https://doi.org/10.5194/egusphere-egu22-8257, 2022.

EGU22-9083 | Presentations | ERE2.4

CO2 flow in supercritical geothermal systems 

Francesco Parisio and Victor Vilarrasa

Technological advances have allowed to target geothermal systems at greater depth and higher temperature in the supercritical regime. Supercritical geothermal systems (SCGS) could potentially provide a drastic increase in power generation, with estimates up to 50 MW per well. A handful of wellbores worldwide have either (or have shown potential to) reached supercritical resources in magmatic provinces. As a common occurrence in volcanic area, the resident fluid is not pure and mixtures of water and CO2 are the norm. In this contribution, we will explore the flow conditions of H2O-CO2 mixtures at temperature and pressure conditions above the critical point of water. The multi-phase and multi-component problem of H2O-CO2 mixture flow is a non-trivial problem and few studies have been done in the past. We present finite element simulations with the open-source multi-physics framework MOOSE that explore the flow conditions of H2O-CO2 mixtures at high temperature and pressure. As a benchmark problem, we assume an injection of cold CO2 into a water filled reservoir. We analyse the pressure and temperature changes and the evolution of the injected CO2 in time. We show how gravity forces play a role in the long term and at relatively large distance from the injection. We discuss the potential of employing CO2 as a working fluid in SCGS.

How to cite: Parisio, F. and Vilarrasa, V.: CO2 flow in supercritical geothermal systems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9083, https://doi.org/10.5194/egusphere-egu22-9083, 2022.

EGU22-9238 | Presentations | ERE2.4

Investigation of Stibnite (Antimony) Scale in Germencik Geothermal Site, Büyük Menderes Graben, Western Turkey 

Serhat Tonkul, Alper Baba, Mustafa Muammer Demir, and Simona Regenspurg

Scale problems in geothermal power plants are one of the reasons that reduce power plant efficiency. Silica scaling, calcite scaling, and sulfide scaling are the most common scale types in geothermal power plants. These scale problems in geothermal power plants can be seen in geothermal wells and surface equipment systems. In this context, various measures should be taken to control the scale problems in geothermal power plants. In this study, the stibnite scaling observed in the preheater system of the Germencik geothermal power plant in the west of Turkey is discussed in full detail. Possible types of scale that may occur in the geothermal wells in the power plant were revealed, and the optimum reinjection temperature was determined for stibnite scaling, which reduces the efficiency of the power plant. Within the 3D modeling of the geothermal power plant and different geochemical models, the precautions to be taken at the power plant are examined in all details.

Keywords: Stibnite, Scaling, Binary power plants, Germencik, power plant efficiency

Acknowledgments: This study has received funding from the European Union’s Horizon 2020 research and innovation programme under agreement, REFLECT Project,  No: 850626.

How to cite: Tonkul, S., Baba, A., Demir, M. M., and Regenspurg, S.: Investigation of Stibnite (Antimony) Scale in Germencik Geothermal Site, Büyük Menderes Graben, Western Turkey, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9238, https://doi.org/10.5194/egusphere-egu22-9238, 2022.

Vintage seismic lines from the area of the city of Aachen from the early 1980s were reprocessed and interpreted in order to characterize the deeper subsurface for its geothermal energy potential. In focus are Lower Carboniferous and Middle to Upper Devonian carbonates as possible karstification is assumed due to the occurrence of thermal springs in the region. Further, extensional NW-SE striking faults of the Tertiary Lower Rhine Graben Rift may provide opportunities for geothermal field development.

The Paleozoic units northwest of the Variscan Rhenish Massif range from Lower Devonian to Upper Carboniferous. Upper Devonian to Upper Carboniferous strata was thrusted onto folded Upper Carboniferous rocks of the foreland molasse basin (e.g. Wurm Syncline) during the Variscan orogeny. As a result, a complex tectonized belt with (at least) three major NE-SW striking thrusts developed, which are cropping out in the region of the city of Aachen. Later, during Upper Cretaceous and Cenozoic times, the region experienced SW-directed rifting and block faulting orthogonal to the Variscan strike as well as inversion movements. Along two of these Paleozoic thrusts, the Aachen Thermal Springs are arising from the subsurface with a temperature of up to 72°C assuming pathways for thermal water from karstified rocks in the deeper subsurface of the Inde Synclinorium. In addition, the strata is exposed along the margins of the Inde Synclinorium or was encountered in wells such as the RWTH-1 well located in the Wurm Syncline or Frenzer Staffel 1 in the Inde Syncline. While the stratigraphy of the geological units is well known from outcrops, their facies distribution and related lithology in the subsurface and within the different fault blocks of the thrust system remains fairly unknown. This was shown from the drilling of the well RWTH-1 in 2004 where the Kohlenkalk (platform carbonates) and the Massenkalk (reef carbonates) were expected but not encountered despite cropping out 10 kilometers to the southwest.

For this investigation, two roughly NW-SE trending seismic lines (~70 km long) were interpreted. The lines were acquired perpendicular to the strike of the Variscan structural elements. The seismic data imaging is challenging due to highly consolidated rocks and very high impedances, partly steep inclination of bedding planes due to thrusting and back-thrusting, low angle faulting (thrust planes), and possible 3D effects where migration is difficult. However, based on the new processing, surface geology correlation, integration of well data, and back-stripping check-ups, we were able to map the key thrust outlines at depths and lithology targets based on their characteristic reflectivity pattern. The most prominent feature on the seismic data is a sharp reflection, which dips approx. south from a very shallow level (~1.000 m) below 6.000 m. The feature was also evident on vintage DEKORP-data and is interpreted as the seismic expression of the Aachen Thrust. Current models can thus be validated or adapted based on our sweet spot maps including the deeper tectonic fabric of the region and regional distribution of carbonate sequences with possible insights on karstification to de-risk future geothermal developments in the area.

How to cite: Jüstel, A., Ritzmann, O., Strozyk, F., and Kukla, P.: Interpretation of seismic reflection vintage lines from the Variscan Fold and Thrust Belt in the Aachen region, Germany: Implications for geothermal exploration, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9276, https://doi.org/10.5194/egusphere-egu22-9276, 2022.

EGU22-9572 | Presentations | ERE2.4

The effect of utilization of the Theistareykir (N-Iceland) high temperature field on the natural geothermal surface manifestations and groundwater composition 

Iwona Galeczka, Finnbogi Óskarsson, Deirdre Clark, Sigurður Garðar Kristinsson, Magnús Ólafsson, Auður Agla Óladóttir, Heimir Ingimarsson, Steinþór Nielsen, and Ásgerður K. Sigurðardóttir

The global framework of the Paris Agreement aims for rapid reduction of GHG emissions to keep the global average temperature below 2 °C above pre-industrial levels. Renewables including geothermal are crucial in transition from a current carbon intensive to carbon neutral or carbon negative energy sources. Although considered as green and sustainable, the subsurface pressure changes caused by thermal fluid extraction might affect the spatial distribution and content of surface manifestations, e.g., fumaroles and may disturb the groundwaters system in the area. As such monitoring of natural features and groundwaters during the geothermal utilization is crucial in the sustainable management of the power plant and it contributes to the understanding of the hydrothermal system through its production lifetime. The aim of this study is to assess the possible effect of the Theistareykir power plant operation on the fumaroles and groundwater chemical composition.

The deep exploration wells in Theistareykir drilled in 2002-2012 confirmed predicted downhole temperatures of >300 °C and high energy generation capacity of the field. The production drilling in 2016-2017 and construction of the power plant carried out in 2015-2017 resulted in a 45 MWe production unit that started commercial operation in 2017. In 2018 a second 45 MWe unit was added increasing the total power output to 90 MWe. Today 12 production and 2 reinjection wells are in use. The results of the continuous fumarole monitoring within the geothermal field since 2012, show no substantial differences in the gases’ concentrations. The current temperature of the reservoir based on the gas geothermometers is similar to the one obtained during the exploration stage (270-315 °C). The fumaroles located in the center and eastern parts of the production field show a continuous decrease in H2S and H2 since 2015, before commencement of the power plant. The concentrations of the elements of concern such as As, Al, Cu, Zn, Cd, Pb, Cr, Ni in groundwaters show no major variations since monitoring first began in 2011. Furthermore, they have not exceeded limits established by the Icelandic directive for surface waters to protect sensitive biota. Even though the absence of noticeable changes in the compositions of the fumaroles and groundwater indicate that the production that started in 2017/18 has currently not posed an environmental threat, observations made in the other production fields suggest that this can be expected in the future. 

How to cite: Galeczka, I., Óskarsson, F., Clark, D., Kristinsson, S. G., Ólafsson, M., Óladóttir, A. A., Ingimarsson, H., Nielsen, S., and Sigurðardóttir, Á. K.: The effect of utilization of the Theistareykir (N-Iceland) high temperature field on the natural geothermal surface manifestations and groundwater composition, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9572, https://doi.org/10.5194/egusphere-egu22-9572, 2022.

Medium-depth and deep geothermal systems hosted in carbonate rocks are amongst the most promising geothermal resources in the world due to their favorable geological and stress- and temperature-sensitive petrophysical heterogeneity. In general, structural heterogeneities such as natural fractures, karstifications, cavities or entire fracture networks mainly dominate geothermal fluid flows and storages and, thus, dictate the reservoir quality. However, especially for carbonate reservoirs, it is even more complex, as a profound understanding of the links between diagenetic processes, facies, deformations, porosities, and fluid flow properties is essential to estimate the distribution of reservoir quality. This assessment is further complicated by the spatially and temporally varying pressure and temperature conditions (e.g., recharge and discharge of geothermal systems).

In the wake of Bavaria’s (southern Germany) success story in exploiting the geothermal systems hosted in deep carbonates, there are extensive investigations to determine the geothermal potential of Devonian carbonates in North Rhine-Westphalia (western Germany). The geothermal potential of these Devonian carbonates strongly depends upon how and to what extent the tectonically influenced burial history and diagenetic processes have modified the pore network and promoted heterogeneities such as fractures and karstifications. In our triaxial experiments, we examined the influence of in-situ stress and temperature and their histories as well as the influence of brittle faulting on porosities and hydraulic properties of different Devonian carbonate rocks. From analogue outcrops limestone, dolomitic limestone, dolostone, and fractured carbonates were sampled and petrophysically investigated. The stresses simulated covered both hydrostatic and triaxial states. Furthermore, the influence of elevated temperature and stress on the hydraulic properties of samples triaxially compressed at effective confining pressures was also studied systematically. Our results show that the interplay of temperature and stress state, and their histories, are fundamental for the evolution of hydraulic properties in the reservoir. Depending on the rock’s mineralogy, the mineral expansion caused by the increased temperature can surpass the effect of microcracking due to heating, resulting in a significant decrease in hydraulic properties. Our results were supplemented by micro-CT images of the microstructure of the samples before and after triaxial testing. It is shown that the interaction of temperature and stress is fundamental for the assessment of the geothermal potential of both intact and fractured carbonate reservoirs.

How to cite: Ahrens, B., Lippert, K., and Nehler, M.: Fluid flow properties of carbonate rocks under simulated in-situ conditions: Implications for geothermal reservoir quality, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9858, https://doi.org/10.5194/egusphere-egu22-9858, 2022.

EGU22-9905 | Presentations | ERE2.4

Single well pore pressure preconditioning for EGS 

Barnaby Fryer, Mathias Lebihain, and Marie Violay

The stress state in the subsurface has been shown to be a hugely important parameter for a wide variety of considerations related to seismicity, both natural and anthropogenic. Industrial operations have been shown to be capable of influencing this subsurface state of stress, as most notably evidenced by instances of induced seismicity related to mining, reservoir impoundment, and reservoir-engineering applications such as production- and injection-induced seismicity related to pore pressure increase. The recognized significance of the stress state for many industrial operations as well as operators' proven ability to influence it, has led to the notion that the stress state can be intentionally preconditioned prior to an operation to that operation’s eventual benefit. The idea of preconditioning was first introduced by the mining industry in the late 1950's as a way to improve rockburst conditions in mines, by blasting to relieve stress in near-face regions. This idea of stress preconditioning has since been extended to the petroleum industry, beginning in the 1970’s and typically focused around hydraulic fracturing. Enhanced Geothermal Systems (EGSs) have been plagued by a number of instances of high-profile induced seismicity, most notably in Basel, Switzerland. This has led to the realization that the development of new reservoir stimulation techniques is crucial for the development of EGS. Here, we propose that the effective stress along a fault intersected by an EGS well be preconditioned prior to stimulation through an extended period of fluid production. Following this production phase, the fault is stimulated through high-pressure injection. Through analytical models related to pressure diffusion, earthquake nucleation, and earthquake rupture, it is suggested that this methodology would result in the halting of near-well nucleated events as they rupture towards the zone of reduced pore pressure. These models assume a constant permeability, linear slip weakening, and a near-critically stressed fault. The investigation is supported by a scaling analysis, shedding light on the suggested required magnitude of the preconditioning phase.

Figure: A schematic illustrating the proposed strategy. On the left, a well (A) is drilled into a fault, shown in plane-view. Fluid is produced from this well, reducing the pore pressure. This production is continued for a significant amount of time, allowing the reduction of pore pressure to be significant and far reaching (D). The well is then stimulated with a short high pressure burst of injection (B). The stimulated zone shears near the well in this high-pressure zone, but is halted by the low-pressure zone (C). The corresponding pore pressure as a function of the radial distance is plotted on the right.

How to cite: Fryer, B., Lebihain, M., and Violay, M.: Single well pore pressure preconditioning for EGS, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9905, https://doi.org/10.5194/egusphere-egu22-9905, 2022.

EGU22-10526 | Presentations | ERE2.4

Geothermal Study of Southern Ireland: DIG Project 

Duygu Kiyan, Emma L. Chambers, Brian M. O'Reilly, Meysam Rezaeifar, Gaurav Tomar, Tao Ye, Javier Fullea, Sergei Lebedev, Christopher J. Bean, and Patrick Meere and the DIG team

One aim of the DIG Project (De-risking Ireland’s Geothermal Potential: Chambers et al., this conference) is to evaluate the geothermal energy potential of the Upper Devonian Munster Basin within the Variscides of southern Ireland. One of our primary targets is the Mallow Warm Springs Area (MWSA) which is sited along the Killarney-Mallow Fault Zone (KMFZ). The fault zone represents the major basin-bounding normal fault system to the basin and regionally controls sediment facies and thickness distribution. The KMFZ was re-activated as a compressional reverse fault in late Carboniferous-early Permian time, during the Variscan Orogeny. Tectonic strain variation is well understood from structural/geological analysis and increases towards Killarney, where the highest strain is associated with a large Bouguer gravity low in the (Avalonian) Caledonian basement. The basin-fill sediments are dominated by siliciclastic sediments, deposited in thick alluvial fan systems, that are succeeded by lower Carboniferous carbonate-prone marine limestones.

Primary porosity in sediments is obliterated by sub-green-schist metamorphism and Variscan deformation fabrics. Fluid flow within the crust around the KMFZ is likely related to the Cenozoic tectonic reactivation of faults and thermally driven uplift as revealed by recent thermo-chronological results in the vicinity of the fault. There was also significant fluid flow during the Munster basin extension and Variscan basin inversion. The focussed part of the DIG study uses potential field (gravity/magnetic) and legacy wide-angle seismic data from the Munster Basin to develop a “new” geological model for crustal structure, with direct application to geothermal research. Critical properties such as thermal conductivity and heat production measurements will also encompass the island-wide aspect of the DIG Project. 

The constraints gathered by the magnetotelluric and passive seismic data within the KMFZ will be integrated with rock physics and geochemical data. This substantial body of work will also include a fluid chemistry program to understand the fluid rock interactions within the KMFZ and their impact on physical properties (electrical conductivity and velocity). Collectively, using this expertise, the study evaluates the geothermal and economic potential of the region and more specifically the MWSA. This local focus on the MWSA aims to directly image fault conduits and fluid aquifer sources at depth, within a convective/conductive region associated with the known occurrence of warm thermal springs. This will determine the scale of the geothermal anomaly, its correlation with our gathered data and will so evaluate the potential for both local and industrial-scale space heating in the survey locality.

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: Kiyan, D., Chambers, E. L., O'Reilly, B. M., Rezaeifar, M., Tomar, G., Ye, T., Fullea, J., Lebedev, S., Bean, C. J., and Meere, P. and the DIG team: Geothermal Study of Southern Ireland: DIG Project, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10526, https://doi.org/10.5194/egusphere-egu22-10526, 2022.

EGU22-10870 | Presentations | ERE2.4

Ambient Noise Tomography applied to a large-N nodal network in Aargau, Switzerland. 

Genevieve Savard, Thomas Planès, and Matteo Lupi

Affordable geophysical survey methods to image in detail the upper crust are critically needed to encourage the growth of the geothermal sector and ensure safe operation conditions. Recent ambient noise imaging studies using surface or body waves retrieved from dense nodal networks have shown that it is a promising technique for reliable, low-cost geothermal prospection and monitoring. The northern canton of Aargau is one of a few regions in Switzerland being investigated for its high geothermal potential. The local positive heat flow anomaly is thought to be linked to hydrothermal circulation along faults bounding the Permo-Carboniferous trough crossing the area. In the Winter of 2020-2021, we deployed a temporary dense network of 210 nodal stations that recorded for about 30 days The goal was to assess the performance of ambient noise tomography by comparing the derived images against existing 2D seismic reflection profiles and geological data. In this study, we invert for the 3D S-wave velocity structure using surface wave dispersion. We discuss the challenges and solutions we encountered in processing the large-N data such as the automatic picking of the large number (~43k) of dispersion curves and a few solutions we applied, including machine-learning-derived techniques

How to cite: Savard, G., Planès, T., and Lupi, M.: Ambient Noise Tomography applied to a large-N nodal network in Aargau, Switzerland., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10870, https://doi.org/10.5194/egusphere-egu22-10870, 2022.

EGU22-11017 | Presentations | ERE2.4

Exploration, utilization and monitoring of conventional and unconventional geothermal resources 

Berker Polat, Volker Wittig, Jascha Boerner, Niklas Geissler, Sebastian Krusenbaum, and Marian Bunk

Geothermal energy out of deep and thus, hot reservoirs do pose viable means to supply and well support the changeover to renewables and still increasing energy demand worldwide as it is virtually available everywhere 24/7, having a carbon neutral footprint and being so-called baseload capable. Therefore, application of enhanced geothermal and petrothermal systems do require the exploitation of such deep geothermal resources to provide more and better geothermal energy. The EU ZoDrEx project and consortium recently demonstrated that installation and exploitation of such geothermal resources can be done safely and economically. Fraunhofer IEG and project partners proved superb hydraulic improvement between wellbore and surrounding reservoir, via Fraunhofer´s high pressure jetting and milling operation, leading to subsequent, much improved reservoir flow by further micro well enhancing measures of Partner GES and others. A variety of high-pressure based water jet technologies for general mineral and rock weakening, erosion and destruction via ultra-short radius deviation were field tested in downhole operation to better connect main wellbore with surrounding reservoir through micro sidetracking and notching. The incorporation of these rock penetration type measures into a functional, downhole EGS system constituted the field work being done in ETH’s Bedretto Underground Laboratory with partners from the ZODREX consortium.

How to cite: Polat, B., Wittig, V., Boerner, J., Geissler, N., Krusenbaum, S., and Bunk, M.: Exploration, utilization and monitoring of conventional and unconventional geothermal resources, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11017, https://doi.org/10.5194/egusphere-egu22-11017, 2022.

As part of the energy transition effort in Switzerland, the ‘GEothermies’: exploration program carried out in the Geneva Basin and its neighbouring areas (Fig. 1) for direct geothermal heat production and storage is ongoing in the Molasse sedimentary basin. Results from previous hydrocarbon exploration and subsequent geothermal drilling campaigns confirmed the presence of five possible stratigraphic targets for geothermal projects.

This study focuses on the shallowest: the Cretaceous-Cenozoic Transition (CCT), a poorly known stratigraphic interval marked by a sedimentary hiatus related to the tectonic phase and the climate that dominated the area at this period. It displays good geothermal potential for its flow rate due to the occurrence of karstification and open fracture systems in the Lower Cretaceous characterized by low-porosity carbonates. The Alpine orogenesis has subaerially exposed and faulted the Lower Cretaceous generating karsts that were infilled with Eocene and Oligocene coarse sediments: the ‘Sidérolithique’, a quartz-rich sandstone facies, and the ‘Gompholite’, a polygenic conglomerate facies.

A better understanding of this stratigraphic interval is provided by tackling the following aspects:

  • Sedimentological framework and diagenetic history of the Cenozoic sediments based on outcrop data and description of cores, further refined by geochemical and mineralogical analyses aimed at reconstructing their depositional processes and environment,
  • Petrophysics, reservoir properties and evaluation of their geothermal reservoirs potential,
  • Regional 2D geological model based on outcrops, wells record, 2D and 3D seismic data in order to predict their lateral and vertical distribution.

The CCT is identified in a few outcrops in the Salève, the Vuache and the Jura, in 35 wells (Fig. 1) and in seismic data, with a depth ranging between 31.20 m (well SPM-3) and 1376 m (well Thônex; Fig. 1). The most significant ‘Sidérolithique’ deposit of 130 m thickness was recorded at 630 m depth in the geothermal exploration well GEo-02 drilled in 2019. According to cores and outcrops observations, the ‘Sidérolithique’ facies have a variable clay content of kaolinite and chlorite as well as a variable abundance of siderite. In the Geo-02 well, a kaolinite-rich content at the bottom of the 'Sidérolithique' shows a mixed signature of the doline palaeosol with the sandstone fill. Despite the presence of clay and siderite, in the Gex wells, porosity values in the CCT deposits ranges from 0 to 20 % while permeability values can reach up several hundreds of mD (Fig. 2) indicating overall good reservoir potential.

Ultimately, this study aims at improving the predictive capability of the geological model of the Canton of Geneva and neighbouring France and provides new insights on the potential of the CCT deposits as geothermal reservoirs.

Figure 1. Location of the study area with the 35 wells that recorded the CCT. Two NW-SE major faults are showed in red: the Vuache Fault and the Arve Fault.

Figure 2. Summary of porosity and permeability values from 86 plugs sorted by facies from the Gex wells including different units in the CCT interval from younger Molasse (left) to older Lower Cretaceous units (right).

How to cite: Crinière, A. and Moscariello, A.: Reservoir geology of the Cretaceous-Cenozoic Transition in the context of geothermal exploration in the Geneva Basin and neighbouring France (Switzerland & France), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11499, https://doi.org/10.5194/egusphere-egu22-11499, 2022.

EGU22-12358 | Presentations | ERE2.4

Geothermal reservoir modelling by using dynamic unstructured meshes for improved heat recovery in highly heterogeneous reservoirs 

Pablo Salinas, Geraldine Regnier, Carl Jacquemyn, Christopher C. Pain, and Matthew D. Jackson

Numerical modelling of fluid flow and heat transport in geothermal reservoirs can be very challenging. One reason is the broad range of length-scales that control the flow behaviour, spanning several orders of magnitude from fractures (millimetre-scale) and wells (metre-scale) to facies architecture and faults (kilometre-scale). The usual approach for modelling geothermal reservoirs is to discretise the equations using the finite-volume method and variants thereof to ensure mass conservation, subdividing space onto a fixed, structured mesh. However, using a fixed mesh resolution across the entire model domain can be very computationally expensive, and prohibitive if the model must resolve many length-scales.

Here we report an efficient method to apply dynamic mesh optimisation (DMO) to model geothermal reservoirs. DMO is widely used in other areas of computational fluid dynamics because it offers significant advantages in providing higher resolution, multi-scale solutions at much lower computational cost. However, application of DMO to geothermal reservoir modelling has so far been very limited.

The method reported here uses a surface-based representation of all geological heterogeneity that should be captured in the model. The numerous surfaces in the model represent geologic features such as faults, fractures, and boundaries between rock types with different material properties. The surfaces bound rock volumes, termed geologic domains, within which material properties are constant. When simulating flow and heat transport, the mesh dynamically adapts to optimize the representation of key solutions metrics of interest such as temperature, pressure, flow velocity or fluid saturation, but the surface architecture is preserved. The advantage of this approach is that up-, cross- or down-scaling of material properties during DMO is not required, as the properties are uniform within each geologic domain.

We demonstrate the method using a number of example problems, including complex wells. Another advantage of our approach is that well trajectories are accurately represented as the mesh conforms to the wells. The well trajectory is also preserved during DMO. We show that more accurate results are obtained at lower computational cost as compared to conventional, fixed mesh approaches.

How to cite: Salinas, P., Regnier, G., Jacquemyn, C., Pain, C. C., and Jackson, M. D.: Geothermal reservoir modelling by using dynamic unstructured meshes for improved heat recovery in highly heterogeneous reservoirs, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12358, https://doi.org/10.5194/egusphere-egu22-12358, 2022.

EGU22-12492 | Presentations | ERE2.4

Geothermal exploitation in the inverted part of the Lower Saxony Basin: A case study from the Minden area 

Olga Knaub, Alexander Jüstel, Gregor Bussmann, Florian Wellmann, and Peter Kukla

Issues of sustainability and climate change are among the driving forces of current research aiming to remedy the grave consequences of greenhouse gas emissions. The consequent system change into the usage of regenerative energy sources through the replacing of fossil fuels represents the most promising solution. This structural change poses large challenges not only for metropolitan areas, but also for smaller towns, which intend to increasingly utilize renewable energies. One such example is the city of Minden in the northernmost part of the state of North Rhine-Westphalia, which serves as case study for this project. The city is geologically situated in the inverted part of the Lower Saxony Basin. This represents a sub-basin in the western part of the North German Basin, which is one of three economically viable regions for geothermal energy production in Germany. The investigation of the feasibility of generating electricity and heat through the exploitation of the deep geothermal reservoirs was driven based on the requirements of a company situated in Minden, which exclusively uses fossil fuels for their industrial processes. In order to generate steam, the production requires high temperatures from the subsurface (> 140°C).

The evaluation of geothermal projects conducted in the North German Basin, regional studies and interpretation of 2D seismic data confirmed the existence of the so-called Wiehengebirge Syncline with outcropping Jurassic rocks in the mountain range to the south of Minden. The compilation of all available data and models highlighted Mesozoic layers of the middle Bunter sandstone (Volpriehausen-Solling formations, 4.0-4.5 km), the Keuper (Stuttgart formation, 3.0-3.3 km) and the Dogger (Bathonium-Callovium formations, 1.8-2.4 km) as potential target horizons within the syncline. Moderate to good hydraulic properties are anticipated for the siliciclastic targets. Furthermore, the hydraulic productiveness of a fault mapped in the immediate vicinity of the investigation site was determined through dynamic reservoir simulations.

Moreover, drilling data provided by the hydrocarbon industry from the gas fields to the north of the city (e.g. Uchte) were used to set up a thermo-hydraulic model in order to determine temperatures and flow rates. These should ultimately specify the most promising formations within the afore mentioned Mesozoic units for further geothermal exploration and developments.

Summarizing, first results of this study have confirmed the deep geothermal energy potential of the western part of the North German Basin and the city area of Minden.

How to cite: Knaub, O., Jüstel, A., Bussmann, G., Wellmann, F., and Kukla, P.: Geothermal exploitation in the inverted part of the Lower Saxony Basin: A case study from the Minden area, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12492, https://doi.org/10.5194/egusphere-egu22-12492, 2022.

There is an increased interest in Scandinavia for development of deep geothermal energy as fossil-free heat-source of district heating system. As part of exploration for Enhanced Geothermal System (EGS) to 5-7 km depth where the groundwater temperature is 120°C can potentially be extracted at 5-7 km depth, Göteborg Energi AB has cored a 1 km deep borehole in Högsbo, southwest Sweden. The objectives of testing was to (1) measure in situ temperatures and derive the geothermal gradient, (2) measure thermal properties of the bedrock, and (3) constrain hydrogeological and mechanical properties of the fracture zone.

The target for drilling and a subsequent EGS facility, is a heat-producing granite that is overlain by a regional fracture zone with inferred elevated permeability. The in-situ temperature of this type granite is boosted by radioactive gamma-ray decay from heat producing elements (K, U, Th).

Knowledge of the state of stress is central to understand bedrock stability, induced seismicity and fluid flow patterns. Acoustic borehole televiewer logging was conducted to map fracture occurrence and their geometry, as well as to investigate of 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.

An unexpected large number of stress indicators has been observed, both borehole breakouts and drilling induced tensile fractures. We observed two types of borehole breakouts: (1) Well-developed borehole breakouts that are clearly visible on both travel-time and amplitude logs; and (2) Poorly-developed borehole breakout that are best visible on the Amplitude log. The shallowest stress indicators are observed from 172-174 m depth, where both types of indicators show NNW-SSE orientation of maximum horizontal stress. This orientation is confirmed from deeper observation, regardless of type of stress indicator. It appears that the regional fracture zone is not influencing the orientation of the stress field in the borehole.

The observations of overlapping drilling induced tensile fractures and borehole breakouts, from such a shallow depth is interesting. It raises questions regarding the magnitudes of stress and the strength of the rock mass. We note that elevated temperature during drilling may induce thermal stresses that favors the formation of drilling induced tensile fractures. On the other hand, the heat producing granites also are known to be probe to weathering. Further studies are required to understand the observed stress indicators, but it appears that the stress orientation is uniform.

How to cite: Ask, M. and Pierdominici, S.: Constraining horizontal stress orientations from acoustic borehole televiewer logs in Högsbo, Southwest Sweden: geothermal exploration, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12768, https://doi.org/10.5194/egusphere-egu22-12768, 2022.

EGU22-12849 | Presentations | ERE2.4

Geochemical monitoring of the geothermal reservoirs using a high-temperature downhole sampler 

Deirdre Clark, Gunnar Skúlason Kaldal, Bjarni Steinar Gunnarsson, Iwona Galeczka, Ingólfur Örn Þorbjörnsson, Steinþór Nielsen, and Ásgerður K. Sigurðardóttir

The monitoring of a geothermal reservoir during its development and production stage is crucial for sustainable and long-lasting utilization. Production wells can cut through several feeding aquifers resulting in discharging of a mixture of fluids originating from these different zones. As such, a sample obtained from a well head during conventional sampling represents an average chemical composition of the subsurface fluids. In contrast, a downhole sampler can collect fluids at precise depths and therefore providing an information about fluid properties at individual feed zones. As it has been observed in high temperature geothermal fields, lack of such a knowledge can lead to a decreased production efficiency and high cost of utilization. For example, extreme corrosion rates of perforated liners have been observed at specific depths due to localized mixing of fluids characterized by distinct compositions. Such damages could be avoided by identifying of such mixing depths before well flow test and by casing off these mis-matching feed zones through cement plugs or tiebacks. Similarly, scaling induced by fluid mixing, could be reduced by assessing appropriate casing depth, and therefore preventing the inflow of problematic fluids into the well.

The aim of this study is to design the downhole sampler that is capable of collecting fluids from high temperature wells at up to 300-400 °C during every stage of the geothermal utilization. The chemical data obtained from fluids at different depths will not only help to select the most energy efficient discharge fluids for improved productivity of the well. It will also contribute to the conceptual models of the reservoirs, hence, to better understanding of hydrothermal reservoirs through their production lifetime.

How to cite: Clark, D., Kaldal, G. S., Gunnarsson, B. S., Galeczka, I., Þorbjörnsson, I. Ö., Nielsen, S., and Sigurðardóttir, Á. K.: Geochemical monitoring of the geothermal reservoirs using a high-temperature downhole sampler, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12849, https://doi.org/10.5194/egusphere-egu22-12849, 2022.

The main objective of a thermal response test is to identify the thermal properties near ground heat exchangers. In standing column wells, the groundwater acts as the heat carrier fluid, rending hydraulic and thermal responses strongly related. Consequently, the identification of hydraulic properties through thermal response test is possible. In this study, the Bayesian framework is employed to infer joint and marginal distributions of thermal and hydraulic properties based on the experimental data gather during a 160-hour thermal response test. This test was conducted on a standing column well constructed in a layered aquifer having locally high groundwater velocities. To simulate the thermal response test, a finite element numerical model is first used to generate a training dataset. Then, a neural network is trained to emulate the ground heat exchanger response in fractions of seconds. This strategy accelerates the computation of the Markov chain Monte Carlo slice sampling algorithm.  A closed-form expression of the likelihood that takes into account the temporal correlation of the data is also used to obtain additional speedup. Main results indicate an accurate estimation of the hydraulic properties in comparison to results found by complementary experimental pumping tests completed at the same site. In accordance with the high velocities observed while drilling at this particular site, high hydraulic conductivity is obtained at the bottom of the borehole. It was possible to draw robust statistical distributions of hydraulic properties with only a thermal response test, while also assessing the thermal properties and their uncertainties.

How to cite: Jacques, L. and Pasquier, P.: Interpretation of a thermal response test in a Bayesian framework to infer the hydraulic properties surrounding a standing column well, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6638, https://doi.org/10.5194/egusphere-egu22-6638, 2022.

EGU22-6768 | Presentations | ERE2.5

A Comparative Study on Factors Affecting Thermal Response Test Analysis 

Hae-Rim Oh, Byeong-Hak Park, Ji-Young Baek, and Kang-Kun Lee

Accurately estimating thermal parameters of ground is important for the sustainable and efficient operation of shallow geothermal systems. A thermal response test (TRT) has been widely performed for the thermal characterization. In this study, four cases (three field tests and one laboratory test) were analyzed using four analytical models with different assumptions of heat source to investigate the influence of three factors (starting time, test duration, and data acquisition interval (DAI)) related to the experimental condition. To compare effects of each factor, the base case was established and various comparison scenarios were generated by varying the factors within specific ranges. The influence degree was demonstrated in the order of starting time, test duration, and DAI, and in particular, the starting time significantly contributed to the thermal conductivity change up to 27.18%. On the other hand, the test duration and the DAI, the other two factors, had maximum impacts of 7.32% and 1.07%. As a result, it was confirmed that the factors should be taken into account when setting the experimental condition of TRT.

Acknowledgement: This research was supported by the National Research Foundation of Korea (NRF) grant funded by the Ministry of Science and ICT (MSIT) of South Korean government (No. 2017R1A2B3002119). This work was also supported by Korea Environment Industry & Technology Institute(KEITI) through "Activation of remediation technologies by application of multiple tracing techniques for remediation of groundwater in fractured rocks" funded by Korea Ministry of Environment (MOE) (Grant number: 20210024800002/1485017890). This work was also supported by the Institute for Korea Spent Nuclear Fuel (iKSNF) and National Research Foundation of Korea (NRF) grant funded by the Korean government (Ministry of Science and ICT, MSIT) (Grant number: 2021M2E1A1085200).

How to cite: Oh, H.-R., Park, B.-H., Baek, J.-Y., and Lee, K.-K.: A Comparative Study on Factors Affecting Thermal Response Test Analysis, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6768, https://doi.org/10.5194/egusphere-egu22-6768, 2022.

EGU22-6991 | Presentations | ERE2.5

Laboratory assessment of carbon steel corrosion rate of grout-less ground heat exchangers 

Gianluca Cadelano, Alessandro Bortolin, Eloisa Di Sipio, Giovanni Ferrarini, Paolo Bison, Adriana Bernardi, Giorgia Dalla Santa, and Antonio Galgaro

The material used to make ground heat exchangers for shallow geothermal applications plays a key role in the overall performance of the system, especially if no grout is used to seal the borehole where the heat exchanger is installed. In this case, the coaxial steel probe is directly coupled with the ground, without any added layer providing thermal resistance between the heat exchanger and the ground. This kind of metallic heat exchanger provides a higher heat exchange efficiency and, in addition, the installation time and costs in unconsolidated deposits are reduced by innovative drilling technique, which has been developed on purpose, where the piling methodology has been combined with a vibrating head and high pressure water injection [1]. Among the materials proposed for the novel vertical ground heat exchangers within the European Horizon 2020 GEO4CIVHIC project, carbon steel is convenient for its low cost and high thermal conductivity [2]. As the main drawback, this material suffers from corrosion, and the physical characteristics of the subsoil directly affect the development of this phenomenon, which afflicts the buried metal bodies and which affects the aging of the ground heat exchange probes. In this study, the corrosion behavior of carbon steel used for an experimental shallow geothermal installation was investigated. The corrosion rates of steel samples were measured in the laboratory using the weight loss method [3] after exposure for certain periods of time in selected ground environments. Different soil conditions were tested, in turn varying the compactness and moisture content of the soil samples collected on site. Based on the results, the corrosion rate of carbon steel was evaluated as a function of both variable parameters. This information made it possible to advance in more precise quantitative forecasts on the expected life of the installed ground heat exchangers and their safety over time.

 

[1] Pockele’ L, Mezzasalma G, Righini D, Vercruysse J, Cicolin F, Cadelano G, Galgaro A, Dalla Santa G, De Carli M, Emmi G, Mendrinos D, Pasquali R, Bernardi A (2020) Innovative Coaxial Heat Exchangers for Shallow Geothermal. Proceedings World Geothermal Congress 2020. Reykjavik, Iceland, 2020

[2] Cadelano G, Bortolin A, Ferrarini G, Bison P, Dalla Santa G, Di Sipio E, Bernardi A, Galgaro A (2021). Evaluation of the effect of anti-corrosion coatings on the thermal resistance of ground heat exchangers for shallow geothermal applications. Energies 14, 2586. Doi: 10.3390/en14092586

[3] ASTM Committee G162-18 Standard Practice for Conducting and Evaluating Laboratory Corrosion Tests in Soils

 

GEO4CIVHIC project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 792355

How to cite: Cadelano, G., Bortolin, A., Di Sipio, E., Ferrarini, G., Bison, P., Bernardi, A., Dalla Santa, G., and Galgaro, A.: Laboratory assessment of carbon steel corrosion rate of grout-less ground heat exchangers, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6991, https://doi.org/10.5194/egusphere-egu22-6991, 2022.

EGU22-7010 | Presentations | ERE2.5

Experimental and numerical investigation of heat transfer from a high temperature borehole heat exchanger under saturated and unsaturated conditions 

Victorien Djotsa Nguimeya Ngninjio, Christof Beyer, and Sebastian Bauer

The performance of borehole heat exchangers (BHE) for borehole thermal energy storage may be deteriorated by the occurrence of permeable water-bearing intermediate layers in the subsurface due to convective flow and heat transport especially at high storage temperatures. Under partly saturated conditions, e.g. in the shallow unsaturated zone, low water contents will reduce the storage capacity as well as the heat transfer rate as compared to fully saturated conditions. This study combines experimental work and numerical simulations in order to quantify these effects on the performance of high temperature BHEs under fully and partly saturated conditions.

A laboratory scale analogue of a coaxial BHE in a water saturated sand medium is constructed in a cylindrical storage cell of 1.2 m height and 1.4 m³ volume. Four short-term heat storage experiments in a temperature range from 30 to 90°C were carried out with six days of continuous heat injection at constant temperature (30, 50, 70, or 90°C), followed by 3 to 4 days of heat extraction, respectively. Temperatures and water contents were continuously monitored on a grid of 68 thermocouples and 20 SMT100 moisture sensors. The water level was then lowered to 0.2 m above the bottom of the system and the experiments were repeated under partly saturated conditions.

Under saturated conditions the observed temperatures in the 30°C experiment show an almost radial distribution with a maximum along the BHE, while for higher injection temperatures an increasing thermal stratification and tilted temperature fronts are observed, which clearly point at an increasing convective impact on heat transport. These results are corroborated by the model simulations, which show an increase of the mean vertical flow velocity from 0.1 to 0.6 m/d between 30 and 90°C due to convection. Additional simulations for purely conductive conditions generally showed lower steady state BHE heat transfer rates during the charging process. This allowed a quantification of the contribution of convection to overall heat transfer, which increases from 5.7% at 30°C to about 38% at 90°C during the charging process. During discharging, however, the thermal stratification due to convection reduces heat transfer rates by up to -38% at 90°C.

Under partly saturated conditions, heat is mainly stored in the direct vicinity of the BHE and the measured temperatures show a radial evolution with no stratification or indications for convection. This points out a conduction dominated heat transport. A decrease of heat transfer rates by about 40% (30°C) to 50% (90°C) is observed in comparison to saturated conditions, which is due to decreased thermal conductivities and heat capacities of the unsaturated porous sand. No indications for significant moisture transport in the gas phase were observed during the experiments.

These results suggest, that high permeable saturated interlayers may severely deteriorate the efficiency of borehole thermal energy storage and increase heat loss and thus environmental impacts, while for unsaturated layers a general reduction of storage rates and capacities must be expected.

How to cite: Djotsa Nguimeya Ngninjio, V., Beyer, C., and Bauer, S.: Experimental and numerical investigation of heat transfer from a high temperature borehole heat exchanger under saturated and unsaturated conditions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7010, https://doi.org/10.5194/egusphere-egu22-7010, 2022.

EGU22-7617 | Presentations | ERE2.5

Fully coupled 3D Thermo-Hydro-Mechanical analyses of a single Energy Micropile subjected to heating-cooling cycles 

Diana Salciarini, Arianna Lupattelli, and Federica Ronchi

Energy Geo-Structures are being increasingly employed over the last decade. They combine the structural and energetic function, allowing the savings related to the absence of additional drilling, required instead by the common geothermal boreholes. Currently, they are a rather mature and deeply investigated technology, with a number of successful applications worldwide; however, some issues related to the thermo-hydro-mechanical (THM) effects induced in soils during heating/cooling cycles still deserve some more analyses, particularly for what concerns the possible non-linear behavior of soil under thermal loading. In this work, this issue has been investigated by means of fully coupled 3D FE modeling, considering a single, small diameter Energy Pile. The emphasis of the FE numerical modeling activity is the investigation of the effects induced by the pore pressure variations close to the pile during the thermal loading stage, and the assessment of the potential influence of the soil thermal softening effect on the pile behavior. Two different constitutive models have been adopted for the considered fine–grained soil, both based on the standard critical state theory: i) the classical Modified Cam Clay (MCC) model; and, ii) a similar critical state model incorporating a thermal hardening/softening mechanism for the critical friction angle, assumed as an internal variable that can be modified with temperature. In the FE model, first the mechanical load is applied at the pile head in almost undrained conditions, followed by a consolidation period during which the excess pore pressure dissipates. Thus, the pile is thermally loaded, with the temperature that is assumed to vary with a harmonic function law over periods of 1, 5 and 10 years, to investigate the short term and long–term effects. The results show that: a) for the considered case study, the thermal loading conditions produce very small changes in pore water pressure at the pile-soil interface; and no effects observed on the pile head displacements can be related to thermally-induced pore pressure changes; on the contrary, b) significant additional pile head settlements are observed in presence of thermal softening, due to by plastic shear deformations at the soil-pile interface.

How to cite: Salciarini, D., Lupattelli, A., and Ronchi, F.: Fully coupled 3D Thermo-Hydro-Mechanical analyses of a single Energy Micropile subjected to heating-cooling cycles, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7617, https://doi.org/10.5194/egusphere-egu22-7617, 2022.

EGU22-7806 | Presentations | ERE2.5

Innovative Geothermal Application Development to support in situ workers 

Eloisa Di Sipio, Silvia Contini, Giulia Mezzasalma, Giorgia Dalla Santa, Antonio Galgaro, Michele De Carli, Laura Carnieletto, Angelo Zarrella, Amaia Castelruiz, Luc Pockelè, and Adriana Bernardi

An innovative user-friendly smart phone/tablet-based Application (App) to support users (drillers, owners, designers) on site to complete a preliminary evaluation of the shallow geothermal heat exchangers and heat pump system feasibility was developed in the framework of the EU funded GEO4CIVHIC Project. The App is expected to provide a preliminary evaluation of drilling time and costs, allowing users to design a first version of the geothermal system, including number of probes and recommended drilling method.

The App requires the geolocation, the underground and building structure, the feasibility and the best drilling solution for the site to be analysed. Hence, the reference data defined by the project concerning the fundamental ground parameters (thermal conductivity, lithology etc…), the climatic classes typical of the European territory and the energy profile of a selection of buildings, representative of the European buildings’ typology, are stored in a specific database internal to the application itself.

Once the site geolocation is defined, automatically or manually, the user is required to insert geological information. The geological section is developed for non-expert users to allow them a simplified underground geological characterization based on intuitive information related to the form of the landscape (geomorphology) and a rough idea of the rocks/sediments present in the area. Selecting an environment, a sub-environment and a lithology, the App, considering a simplified stratigraphy of about 100 m depth characterized by a homogenous material in saturated conditions, provides an output related to (i) the best method to drill the underground, (ii) the evaluation of time and cost for the drilling method suggested, (iii) the thermal conductivity value linked to the main lithology.

In the Building section, an estimate of the maximum energy requirement for both heating and cooling knowing the latitude and longitude coordinates and the building typology of the test site is obtained. In the App database, the European cities, based on their geographic coordinates, are grouped in four simplified climatic zone domains according to the Köppen-Geiger climate classification. This allow to obtain the average annual degree days (DD) for heating and cooling necessary to calculate the cooling and heating loads of the building. Then, selecting the reference building typology (residential/non-residential) and the ground characteristics, the App automatically calculate the geothermal field size necessary to meet its energy needs.

The validation in the Mechelen (Belgium) case study of GEO4CIVHIC project shows a good agreement between the App simplified information and the real case condition. Next future more validation will be provided. However, the App outputs are a preliminary, not refined estimate of the geothermal feasibility to realize shallow geothermal systems and cannot be considered as sufficiently detailed to plan these systems. On this regard it is mandatory to acquire more detailed local information, consulting local experts and/or referring to the Decision Support System (DSS) of GEO4CIVHIC Project.

GEO4CIVHIC project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 792355.

How to cite: Di Sipio, E., Contini, S., Mezzasalma, G., Dalla Santa, G., Galgaro, A., De Carli, M., Carnieletto, L., Zarrella, A., Castelruiz, A., Pockelè, L., and Bernardi, A.: Innovative Geothermal Application Development to support in situ workers, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7806, https://doi.org/10.5194/egusphere-egu22-7806, 2022.

EGU22-7838 | Presentations | ERE2.5

Evaluation of the efficiency and impact of a shallow geothermal installation. Case of Can Batlló, Barcelona. 

Franco Tomás Coscia, Rotman Criollo, Laura Scheiber, Ignacio Bulboa, Estanislao Pujades, and Enric Vázquez-Suñé

The “Can Batlló” factory was built on the Can Mangala between 1877 and 1879, as a cotton yarn and fabric, as well as bleaching, printing and sizeing factory. It is intended to install a geothermal system for the air conditioning of an administrative building in the city of Barcelona in one of the factory´s buildings.

The purpose of this study is to confirm whether the proposed energetic demand can be achieved in a sustainable manner and to assess potential impacts in the subsurface over time.

The numerical model of flow and heat has been pre-calibrated with the regional flow model and thermal response test (TRT) of the area. The results indicate that the extracted geothermal energy could be higher (12-20% more) than the initial design. This higher performance would imply an optimisation of the system. It could be implemented by means of modifying the design of the heat exchangers, by reducing their amount and their length, or by changing the location of the exchangers to the whole location of Can Batlló, and not reducing their installation to a single building. Therefore, in addition to being able to design a more efficient and economic geothermal system, the investment could be recovered sooner[Rotman Cr1] .

Simulations at 10 years of geothermal exploitation indicate that a downstream plume may occur. This variation of the natural subsurface temperature can affect the environment.

Although the analyses carried out have made it possible to know the behavior of the subsurface in the front of this geothermal installation, to make a deeper study would be advisable to determine in more detail the long-term effects (more than 10 years) that it can cause in the subsurface. For this reason, the following tasks are recommended: (1) To create a control network at the scale of the study area to monitor the performance and the effects of the geothermal field once its installation is on operation; (2) To define the optimal characteristics of the exchangers to obtain a better geothermal performance; (3) To perform a drilling of a minimum depth of 200 meters to verify the materials described in the data collection; (4) To perform hydrochemical and isotopic analysis of the executed point to analyze the feasibility of possible groundwater uses; and (5) To carry out the conceptual and numerical modelling of the local and regional hydrogeological and geothermal system with the detail obtained with the previous point and to analyze the optimisation scenarios mentioned above.

How to cite: Coscia, F. T., Criollo, R., Scheiber, L., Bulboa, I., Pujades, E., and Vázquez-Suñé, E.: Evaluation of the efficiency and impact of a shallow geothermal installation. Case of Can Batlló, Barcelona., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7838, https://doi.org/10.5194/egusphere-egu22-7838, 2022.

EGU22-9313 | Presentations | ERE2.5

The COOLGEOHEAT project: Geothermal 5th generation district heating and cooling (Geo5GDHC/thermonet) in Denmark 

Søren Erbs Poulsen, Marwan Abugabbara, Karl Woldum Tordrup, Søren Skjold Andersen, Christian Preuthun Pedersen, Saqib Javed, and Theis Raaschou Andersen

Nearly two thirds of all Danish (DK) households utilize 3rd and 4th generation (3G and 4G) district heating (DH) for space heating and hot water. Despite being the most mature district heating system in the world, projections show that the maximum extent of traditional DH in DK is limited to 65-70%. Currently, the remaining one-third of Danish households are left with no choice but to invest in individual heat supply systems, typically air-source heat pumps. As an alternative, the concept of geothermal 5th generation district heating and cooling (Geo5GDHC) has emerged recently. Geo5GDHC connects distributed prosumer heat pumps to a grid of uninsulated pipes that distribute energy at ambient temperatures from shallow geothermal drillings (open or closed), energy geostructures and sources of excess heat, to supply room heating and domestic hot water. This allows for combined heating and passive cooling with a single grid, capable of shifting thermal loads by seasonal energy storage. Geo5GDHC grids can be recharged and balanced by utilizing waste heat and by storing heat from passive cooling of the building mass during summer.

Currently, there are twelve commercial Geo5GDHC grids (thermonet) in Denmark using different energy sources and models for ownership and operation. However, in the case of Denmark, the maximum extent of Geo5GDHC is much larger. Geo5GDHC is complementary to 4th generation district heating and cooling (4GDHC) as it is less affected by economies of scale. Consequently, Geo5GDHC is often economically feasible when traditional DHC is not, typically in rural areas, and therefore serves as an extension of existing DHC technologies. As such, Geo5GDHC potentially ensures that the majority of Danish households are connected to a collective heating and cooling grid in the future when combined with 4GDHC. A similar potential for Geo5GDHC exists in Europe and the USA, however, despite its significant potential, the Geo5GDHC market is still very much in its infancy.

The Interreg ÖKS project COOLGEOHEAT addresses both technical and economic aspects of Geo5GDHC in a joint collaboration between stakeholders and research institutions in Sweden and Denmark. We present results from the ongoing project including the development of design models in the Modelica simulation platform, that serve to estimate the thermal performance of the grid and the associated upfront investment and costs of operation, to support decision-makers. The project further explores business models for ownership and operation and the possibilities for financing grids with green investments of pension funds.

How to cite: Poulsen, S. E., Abugabbara, M., Tordrup, K. W., Andersen, S. S., Pedersen, C. P., Javed, S., and Andersen, T. R.: The COOLGEOHEAT project: Geothermal 5th generation district heating and cooling (Geo5GDHC/thermonet) in Denmark, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9313, https://doi.org/10.5194/egusphere-egu22-9313, 2022.

EGU22-9446 | Presentations | ERE2.5

Combining green infrastructure and ground heat exchangers in urban areas 

Anil Yildiz and Ross Stirling

Ground Source Heat Pump (GSHP) systems are one of the many alternatives that will help to decarbonise the space heating and cooling – especially in residential sector. High capital costs of drilling for borehole heat exchangers and added complexity of space dedication in densely populated urban areas are hindering the market development. We propose combining GSHP systems with Sustainable Drainage Systems (SuDS) for a more efficient heat exchange, which provide opportunities to significantly improve the resilience and sustainability of our built environment. This combined system removes the need to dedicate space to accommodate shallow ground heat exchangers in areas where the unit price of land is high. Furthermore, hydrological conditions prevalent in the substrate of SuDS provide demonstrably beneficial thermo-hydrological interactions. We built an at-scale SuDS component, i.e. a 950-mm high soil column with a diameter of 1800 mm, as a lysimeter setup at the National Green Infrastructure Facility to test the heat injection into the substrate. A range of field testing scenarios (thermal load and cycling) were applied under natural, external ambient conditions. Soil temperature during heat injection was also simulated numerically by solving a transient heat conduction equation with a finite difference modelling scheme. The developed model was validated using measurements from the lysimeter setup which then enabled numerical experiments into the effects of varying hydrological regimes to be performed.

How to cite: Yildiz, A. and Stirling, R.: Combining green infrastructure and ground heat exchangers in urban areas, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9446, https://doi.org/10.5194/egusphere-egu22-9446, 2022.

Over 50% of the energy consumption in Europe is used for heating and cooling, of which the majority still comes from fossil fuels. For the heating and cooling supply of buildings, heat pumps using borehole heat exchangers (BHE) are an efficient and sustainable alternative. Design and performance of BHE fields strongly depend on the thermal properties of the subsurface. For the dimensioning of BHE fields, the subsurface properties are assessed using geothermal potential maps published by federal states or authorities.

Such maps are created based on available geological and hydrogeological subsurface data. From these data, the stratigraphic sequence a BHE would intersect is inferred and thermal properties are assigned to the rock sequence. The mean thermal conductivity of the intersected sequence has a high uncertainty that is not quantified in most geothermal potential estimates. Moreover, geothermal potential maps are often not comparable because the used calculation methods differ in terms of complexity and calculated quantity. In Germany, for example, almost each of the federal states published its own geothermal potential map showing different quantities.

For these reasons, we propose an approach to estimate the subsurface thermal conductivity together with its uncertainty. To enable applicability to datasets of different regions, e.g., all German federal states, the method takes only publicly available and standardized hydrogeological and geological data as input. Thermal conductivity estimation takes place on

1) a large scale, to obtain a general estimate of thermal conductivity, and

2) on a fine scale, to update the large-scale estimate in smaller target areas.

For both estimations, we consider uncertainty by assigning not only the mean but also the minimum and maximum thermal conductivities of each rock type to the intersected sequence. Data handling and initiation of calculations is done via a geoportal. It connects the calculation method to geodata servers, instead of storing data locally, thus ensuring data up-to-dateness. This way, the approach does not only estimate the thermal conductivity, but also automatizes the cumbersome step of geological data gathering for all types of subsurface investigations.

We demonstrate the approach using data from the federal state of Hamburg and compare our results to a thermal conductivity map published by the city of Hamburg.  The partly considerable differences between the two estimates illustrate the uncertainty of the geothermal potential, and thus the need to communicate it.

How to cite: Heim, E., Laska, M., Becker, R., and Klitzsch, N.: Estimating the subsurface thermal conductivity and its uncertainty for shallow geothermal energy use – a methodology based on publicly available data, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9853, https://doi.org/10.5194/egusphere-egu22-9853, 2022.

EGU22-12191 | Presentations | ERE2.5

Investigating the environmental impact of Shallow Geothermal Energy systems across Europe 

Lazaros Aresti, Paul Christodoulides, Christos Makarounas, and Georgios Florides

Geothermal energy finds application with Shallow Geothermal Energy (SGE) systems for space heating and cooling. Ground Source Heap Pumps (GSHPs) constitute the main systems used in SGE when coupled with Ground Heat Exchangers (GHEs). GHEs are essentially a network of tubes that extract or reject heat to and from the ground. GSHP systems have recently gained more attention and are recruited for the reduction of fossil fuels and CO2, as an alternative to Air Source Heat Pump (ASHP) systems. However, recent advancements of the ASHP systems through the improvement of their coefficient of performance (COP) classify these at a very competitive scale against GSHP systems.

The directive of the European Union (EU) on the nearly Zero Energy Buildings (nZEB) is already in effect, and requires the residential buildings to have better insulation on the building’s envelop, leading to a reduced heating and cooling demand. Such cases could further weaken the higher energy performance of GSHPs and make these systems a not so attractive alternative compared to ASHP systems. 

This research aims to investigate such scenarios using seven case studies, at seven different locations across Europe. The same residential building is used in all cases with nZEB technical characteristics. To this extent, a Life Cycle Analysis (LCA) is performed for the environmental evaluation using the ReCipe impact method from a midpoint perspective. The openLCA software is considered, coupled with the Ecoinvent 3.6 dataset for the impact methods and databases. A comparison is made of the case studies through an analysis of the global warming potential impact category. The results show that the northern European countries exhibit a better comparison performance between the ASHP and GSHP systems, compared to the southern European countries.

How to cite: Aresti, L., Christodoulides, P., Makarounas, C., and Florides, G.: Investigating the environmental impact of Shallow Geothermal Energy systems across Europe, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12191, https://doi.org/10.5194/egusphere-egu22-12191, 2022.

EGU22-699 | Presentations | HS5.2

Exploration of the theoretical, financial, technical and sustainable hydropower generation potential in the Upper Indus basin 

Sanita Dhaubanjar, Arthur Lutz, David Gernaat, Santosh Nepal, Saurav Pradhananga, Sonu Khanal, Arun Bhakta Shrestha, and Walter Immerzeel

Hydropower investment decisions in the Upper Indus take a short-sighted approach based on energy generation potential at individual hydropower sites considering historical hydro-climatology. But hydropower will increasingly be affected in the future by changing climate and demands for water, energy and food – all heavily dependent on water resources availability. The seasonality and variability in runoff are changing. Anthropogenic water consumption may see a two to three fold increase by the end of the century with socio-economic development. Climate change and interlinkages with the water-energy-food nexus are emerging as primary stressors to land and water resources availability for hydropower in the Indus. Hence, we assess the extent of the challenges posed by climate change versus the nexus linkages on hydropower potential in the Upper Indus. Our sustainable hydropower exploration framework takes a systems approach to quantify theoretical, technical, economic and sustainable hydropower potential by successively considering the impact of natural, technical, financial, anthropogenic, environmental, and geo-hazard constrains on hydropower potential at both the individual site and the basin scales. The framework explicitly considers the water available for hydropower versus other nexus usages. We combine the framework with downscaled CMIP6 general circulation models and water consumption projections to compare current and future hydropower potential. Thus, we present hydropower development portfolios that are more robust under climate change and changes across the water-energy-food nexus. Future changes in climate and water demands will increase the need for a multi-sectoral approach in the identification of potential sites to achieve sustainable hydropower development. We present a basin-scale analysis of hydropower potential in the Upper Indus, now and in the future, considering growing demands for water, food and energy to fulfill the Sustainable Development Goals.

How to cite: Dhaubanjar, S., Lutz, A., Gernaat, D., Nepal, S., Pradhananga, S., Khanal, S., Bhakta Shrestha, A., and Immerzeel, W.: Exploration of the theoretical, financial, technical and sustainable hydropower generation potential in the Upper Indus basin, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-699, https://doi.org/10.5194/egusphere-egu22-699, 2022.

In the United Kingdom (UK), the amount of electricity generated from small-scale hydropower has nearly tripled since 2010. One of the key areas of growth within the sector has been run-of-river hydropower schemes, with several hundred now operating across the UK and the Republic of Ireland (RoI), the majority situated in mountainous areas of Scotland and Wales. Although the overall grid contribution of these schemes is small (~2%), they still play an important role, not only in decarbonising the grid and contributing to national emission reduction goals, but also at local scales, where schemes often provide financial benefit to local communities and individuals. However, future climate change threatens to alter precipitation patterns and therefore streamflows, potentially impacting both the timing of hydropower generation and the total power output potential.

In this study, we quantify the impact of a worst-case future climate change scenario (Representative Concentration Pathway 8.5) on the generation potential of run-of-river hydropower schemes in the UK and RoI. EXP-HYDRO hydrological model is used to simulate future daily streamflow for the 2021-2080 hydrological years in 178 catchments containing 531 hydropower abstractions. We estimate daily abstraction potential at each site based on the local environmental regulators’ (for Scotland, England, Wales, Northern Ireland, and Ireland) general abstraction conditions. We then perform seasonal and annual Mann-Kendall trend analysis at each site to analyse changes in: 1) the number of days when abstraction is possible, 2) the number of days when maximum abstraction is reached, 3) mean abstraction volume on days when abstraction is possible, and 4) the total abstractable volume. The scale of study undertaken allows for characterisation of both the impact of regional variation in future climate forcing, as well as analysis of the impact of local environmental regulation, on the future generation potential of run-of-river hydropower in the UK and RoI.

Results show increasing annual total abstraction potential in northern England and Scotland, while a decline is seen in Wales; little change is seen in Ireland and Northern Ireland. The number of days per year that abstraction is possible declines in all areas except the northwest of Scotland, while the number of days that maximum allowable abstraction is reached increases; mean daily abstraction therefore increases. A disparity can be seen in different nations between the magnitude, and in some cases direction, of change in annual mean streamflows compared to annual abstraction potential. This is likely caused by differences in water abstraction regulations between UK nations. This poses an interesting question in terms of the impact of environmental regulations for the different nations of the UK, and how best to maximise renewable energy output by hydropower, while protecting the natural environment.

How to cite: Dallison, R. and Patil, S.: Water availability assessment for run-of-river hydropower under future climate change in the UK and Ireland, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-806, https://doi.org/10.5194/egusphere-egu22-806, 2022.

EGU22-2132 | Presentations | HS5.2

Application on the Micro-hydropower generation Benefits of Agricultural Channels and the Water- Energy-Food nexus 

Jen-Chieh Shih, Fu-Yuan Lin, Ming-Der Hong, Hong-Ru Lin, and Jet-Chau Wen

Micro-hydropower is necessary renewable energy to provide baseload, and it has the advantages of sustainable development and reduction of greenhouse gas emissions. There is an interrelationship between irrigation water and energy from micro-hydropower with micro-hydropower development in agricultural irrigation systems. Li et al. (2019) mentioned that the agricultural system estimated the water supply-demand, energy supply-demand, land demand, and food production and was quantitatively analyzed under different scenarios. However, the study of water for electricity generation was neglected in the agricultural system. Zhou et al. (2019) apply small-hydropower into water supply systems to lift renewable power output and uplift the synergistic benefits of the Water-Food-Energy (WFE) Nexus steered by the optimal water allocation and small-hydropower installation. Still, the adjustment of the water source by the reservoir makes the flow of the water supply system unstable, which leads to inconsistent electricity generation of small hydropower. Gaudard et al. (2018) research that hydropower plants' relationship between water and energy is set-upstream. The results show that seasonality slightly affects hydroelectric power generation.

Therefore, the study set up a micro-hydropower generation system in the Linnei channel of the Zhuoshuixi river watershed in the middle of Taiwan. Collected channel background information and used Doppel (Teledyne StreamPro ADCP) to measure the water level, velocity, and discharge of the study site, analyze potential power generation, and evaluate the profit and payback period micro-hydropower generation and the impact of micro- hydropower systems in agriculture. Furthermore, to investigate the relationship nexus of WFE and assess micro-hydropower's effectiveness in reducing carbon dioxide emissions. According to the results of this study, it can be used as a reference basis for setting up other micro-hydropower systems in the future.

How to cite: Shih, J.-C., Lin, F.-Y., Hong, M.-D., Lin, H.-R., and Wen, J.-C.: Application on the Micro-hydropower generation Benefits of Agricultural Channels and the Water- Energy-Food nexus, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2132, https://doi.org/10.5194/egusphere-egu22-2132, 2022.

The European Union’s endeavors to find the right path to a climate-neutral future in 2050, the so-called green shift, is the subject of heated debate. One of the currently most discussed question is: What are the electricity sources of the future? While EU’s member states arguing about the advantages and disadvantages of nuclear and gas-fired power plants during this green shift, other countries have already succeeded in achieving extensive climate-neutrality in the electricity sector. Norway is currently one of the largest producers of sustainable electricity in Europe with an annual hydropower production capacity of 136.6 TWh from around 33,000 MW installed capacity (2021)[1]. Moreover, one of Norway’s possible strategies is to become the green battery of Europe – enabling neighboring countries to store energy peaks from renewable electricity generation in the Norwegian energy system.

Its geological and climate prerequisites enabled Norway to become a forerunner for renewable energies in the global electricity market. The advantages of hydropower technology found unbroken success in Norway in the first decades after World War II, heralding the beginning of the “most intense period for hydropower development in Norway”[2]. This period ended in 1990 when most of today’s hydropower capacities were fully developed and new legislation was introduced. Today we take Norway’s hydropower legacy for granted and therefore know little about the country’s own electricity debates during this expansion period.

As part of the PhD research project “Norway’s hydropower development boom in the perception of society”, this contribution to the EGU General Assembly 2022 is intended to shed light on these electricity debates by elaborating the sociotechnical imaginaries of electricity futures in Norway from 1945 to 1990[3]. Different public debates facing electricity capacity building of this period will be presented by analyzing 62 articles of Norway’s most important newspaper of public record Aftenposten. Who participated in these debates? What is the respective imagination about Norway’s electricity future about and for what reason?

It turns out that the renewables pioneer in the north of Europe was not a hermetically sealed land of hydropower enthusiasts. Quite the opposite: In the public debates of scientists, engineers, politicians and residents in Norway, developments on the global electricity market were taken seriously, such as the introduction of nuclear power technology, the onset of transnational electricity trading, and the emerging social skepticism about ecological damages caused by hydropower. As a final remark, this contribution will face the question why hydropower remained the ‘royal road’ for Norway’s electricity development.


[1] Norges vassdrags- og energidirektorat (ed.). 2021. Vannkraft. https://www.nve.no/energi/energisystem/vannkraft/

[2] Lia, L. et al. 2015. “The current status of hydropower development and dam construction in Norway”. International journal of hydropower and dams. Vol. 22(3): 42.

[3] The wording refers to the concept of “sociotechnical imaginaries” as described in Jasanoff, S. 2015. “Future Imperfect: Science, Technology, and the Imaginations of Modernity’” in Jasanoff, S. and Kim, S. H. (eds.) Dreamscapes of Modernity: Sociotechnical Imaginaries and the Fabrication of Power. Chicago: The University of Chicago Press, pp. 1–33.

How to cite: Fischer, M. and Lia, L.: The reasons why hydropower remained. Sociotechnical imaginaries of electricity futures in Norway from 1945 to 1990. A media analysis based on articles from the Norwegian daily newspaper Aftenposten, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4651, https://doi.org/10.5194/egusphere-egu22-4651, 2022.

EGU22-4726 | Presentations | HS5.2

Climate change impacts on Alpine hydropower in the context of environmental impacts and technical constraints 

Tobias Wechsler, Dorothea Hug Peter, Massimiliano Zappa, and Bettina Schaefli

Hydropower production affects different stakeholders, levels of administration and ecosystems, which makes the question of its sustainability complex. Hydropower delivers energy, storage capacity, jobs, economic value, but also involves altered streamflow, water temperature and sediment transport conditions, fractioning of aquatic habitats and modification of the landscape. Thus, an increasing demand for renewable and climate friendly energy from hydropower also results in more pressure on aquatic habitats, thereby potentially calling into question its sustainability.

In this work, we compare climate change impacts on the future energy production of 21 hydropower plants in Switzerland, to impacts related to environmental flow requirements and to site-specific technical optimisation potential. The simulation-based study corresponds to three future periods (2020–2049, 2045–2074 and 2070–2099) under three emission scenarios (RCP2.6, RCP4.5, RCP8.5), assuming unchanged environmental flow requirements and installed machinery. The results show an increase of winter production and a decrease of summer production, which in conjunction leads to an annual decrease. The simulated impacts strongly depend on the elevation and the plant-specific characteristics. The climate induced changes in production are of a similar order of magnitude as the production loss due to environmental flow requirements and the increase potential due to technical optimisations. A key result is that the climate induced reduction is not linearly related to the underlying streamflow reduction, but is modulated by environmental flow requirements, the design discharge and streamflow projections. Taken a step further, a change in production does not necessarily mean a linear change in financial revenue. The Water-Energy Nexus in terms of hydropower concerns more than just a m3s-1–kWh relationship: it is part of a complex framework that is namely sensitive to legal adjustments and to long lasting technical decisions taken in the past.

How to cite: Wechsler, T., Hug Peter, D., Zappa, M., and Schaefli, B.: Climate change impacts on Alpine hydropower in the context of environmental impacts and technical constraints, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4726, https://doi.org/10.5194/egusphere-egu22-4726, 2022.

EGU22-4882 | Presentations | HS5.2

A quantitative technology for supporting multi-objective decision making in hydropower operation 

Xiaokuan Ni, Zengchuan Dong, Yong Jiang, Hongyi Yao, Wenhao Jia, and Guang Yang

There is a conflict between the hydropower benefit of hydraulic engineering and other functions such as ecological protection, water supply, flood control, etc. Deciding on an appropriate scheme to balance the interests among multiple objectives is a crucial issue in hydropower operation management. The Pareto set is the carrier and embodiment of a multi-objective mutual feedback relationship. It has a constant increasing or decreasing tendency, and most distribute unevenly, meaning different change rates and sensitivities are embedded. Based on this understanding, a new idea of "profit/loss ratio" is obtained, which constructed the average change rate of each neighbouring non-inferior solution on the Pareto frontier. Processed dimensionless, a new non-dominated subset of Pareto non-inferior solutions is filtered out according to the dominance relationship to limit scheme selection scope. On this basis, a method for calculating the "bias degree" of each Pareto non-inferior solution relative to different objective functions is proposed, which leads to the quantitative evaluation of Pareto solutions and provides quantitative support for decision-makers select operation schemes according to their preferences. Taking the cascade reservoirs in the lower reaches of the Jinsha River Basin in China as a case, the trade-off between the two objectives of hydropower generation and ecological protection is investigated, and the feasibility and effectiveness of the methodology are verified.

How to cite: Ni, X., Dong, Z., Jiang, Y., Yao, H., Jia, W., and Yang, G.: A quantitative technology for supporting multi-objective decision making in hydropower operation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4882, https://doi.org/10.5194/egusphere-egu22-4882, 2022.

EGU22-5384 | Presentations | HS5.2

Hard-coupling of water and power system models increases the complementarity of renewable energy sources 

Rachel Koh, Jordan Kern, and Stefano Galelli

Multi-sector modelling frameworks are fundamental platforms for exploring the complex interactions between the water and energy sectors. While acknowledging the pivotal role of hydropower within the energy system, it is essential to understand the feedback mechanisms between power and water systems to guide the design of hydropower operations and enhance water-energy management strategies. Here, we developed a novel modelling approach that hard-couples a reservoir system model and a power system model. The two-way dynamic feedback mechanism between the models allows for operational decisions to be made contingent upon the states of both water and energy systems. Operating the system as a whole offers flexibility in managing the physical storage of hydropower reservoirs to buffer the variability in other renewables, such as wind or solar. We evaluate the framework on a real-world case study based on the Cambodian grid, which relies on hydropower, coal, oil and imports from neighboring countries. In light of the country’s plan to further decarbonize its grid, we tested the framework on three grid configurations, the as-is grid, and the grid with two different levels of installed solar. To evaluate the effects of hard coupling, the experiments were simulated with and without feedback, and external inputs were varied with 1,000 stochastic generations of streamflow, solar and load. As demonstrated in our results, hard-coupling the water and energy systems brings benefits such as reduced operating costs, and boosts decarbonization efforts by supporting the integration of renewables in the grid. The two main external factors that determine the effectiveness of the feedback mechanism are streamflow and load. Under favorable conditions (large reservoir inflow and low electricity demand), the system experienced a 44% saving in annual operating costs and 53% reduction of CO2 emissions. A spatio-temporal analysis on the reservoir operations and transmission line usage reveals that the timing of the monsoon and interconnections between the grid components also play significant roles in influencing the system’s responses to the hard coupling. Overall, our modeling framework paves way for optimized operations within the water-energy nexus. By accounting for the interdependencies between the reservoir and power system, a more efficient operating scheme for hydropower reservoirs can be derived, leading to greater complementarity of renewable energy sources.

How to cite: Koh, R., Kern, J., and Galelli, S.: Hard-coupling of water and power system models increases the complementarity of renewable energy sources, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5384, https://doi.org/10.5194/egusphere-egu22-5384, 2022.

EGU22-5468 | Presentations | HS5.2

Towards energy autonomy of small Mediterranean islands: Challenges, perspectives and solutions 

Athanasios Zisos, Maria-Eleni Pantazi, Marianna Diamanta, Ifigeneia Koutsouradi, Anna Kontaxopoulou, Ioannis Tsoukalas, Georgia-Konstantina Sakki, and Andreas Efstratiadis

The energy autonomy of small non-interconnected islands in the Mediterranean, taking advantage of their high renewable energy potential, has been a long-standing objective of local communities and stakeholders. This is also in line with the recently implemented European Green Deal, which has set the goal of increasing the renewable energy penetration in European countries’ power systems. However, the islands have further challenges than the large-scale inland areas. On the one hand, their population fluctuates significantly across seasons, as result of tourism, which is their key economic activity. The footprint of tourism is a substantial stress to all associated resources and infrastructures during the summer period. On the other hand, most of these areas suffer from both water and land scarcity. These features raise several challenges regarding the development of really autonomous energy systems, based on renewables and essential storage works to regulate the energy surpluses and deficits in the long run. Taking as example the Cycladic island of Sifnos, Greece, we investigate the design of a hybrid power system, combining wind, solar and hydroelectric energy. A major component of the proposed layout is the pumped-storage system. Due to the limited surface water resources of the island, we configure an upper tank at an elevation of 320 m, recycling seawater. This peculiarity introduces a significant level of uncertainty in hydraulic calculations, as well as various technical challenges, such as the erosion of pipes and the electromechanical equipment, and the waterproofing of the tank. An additional challenge is raised by the peculiar wind regime of the island, that makes essential to choose a hub height of turbines to minimize the frequency of power cut-offs. The basis of a rational design procedure for the main system components is the financial optimization that ensures a desirable level of reliability. This is achieved through a stochastic simulation approach that takes into account the stochastic nature of the underlying hydrometeorological drivers (wind velocity and solar radiation) and the energy demand.

How to cite: Zisos, A., Pantazi, M.-E., Diamanta, M., Koutsouradi, I., Kontaxopoulou, A., Tsoukalas, I., Sakki, G.-K., and Efstratiadis, A.: Towards energy autonomy of small Mediterranean islands: Challenges, perspectives and solutions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5468, https://doi.org/10.5194/egusphere-egu22-5468, 2022.

EGU22-7787 | Presentations | HS5.2

The role of innovative econometric models in short-term hydropower optimization 

Diego Avesani, Ariele Zanfei, Di Marco Nicola, Andrea Galletti, Ravazzolo Francesco, Righetti Maurizio, and Bruno Majone

The recent transformation of the electricity market has modified the hydropower production paradigm, especially for storage reservoir systems. In particular, the process of market liberation has led to a shift in hydropower management approaches. These have moved from strategies oriented to maximizing energy production to strategies aimed at revenue maximization. Indeed, hydropower producers bid their energy production scheduling in advance, attempting to align the operational plan for the ensuing day (i.e., allocating 1-day ahead the hourly time series of turbined water discharges) with hours where the expected electricity prices are higher. As a result, the accuracy of 1-day ahead electricity prices forecasts, as given by econometric models, has started to play a key role in the short-term optimization of storage reservoir systems. Though recognized, this aspect has so far received limited attention in the literature.

This work aims to contribute to the topic by presenting a comparative assessment of revenues provided by the solution of short-term hydropower optimization problems driven by two econometric models during an entire year of simulation. Both models are autoregressive time-adapting hourly forecasting models which exploit the information provided by past values of electricity prices. One model, referred as Autoarimax, can be considered as the state-of-the-art in electricity prices forecasting, the peculiarities of which are rooted in the use of time-varying exogenous variables related to electricity demand and production, while the other, referred to as the Benchmark, can be considered a standard autoregressive model.

The added value of using an innovative econometric model is exemplified in two selected hydropower systems with different storage capacities located in the south- eastern Alpine region. The enhanced accuracy of electricity prices forecasting is not constant across the year due to the large uncertainties characterizing the electricity market, the fluctuations of which are controlled by short-term and seasonal imbalances in factors affecting electricity demand and production. Our results also show that the adoption of this more accurate econometric model leads to larger revenues with respect to the use of a standard model. The increased revenues depend strongly on the hydropower system characteristics, such as reservoir capacity and the ratio between inflows and maximum turbined water discharge that can be conveyed to the plant. Specifically, we showed that, for the reservoir characterized by a larger storage capacity, the use of Autoarimax forecasts led to a revenue increase of up to 2.31% at monthly scale with respect to the case in which Benchmark forecasts are used in the optimizations. This revenue gain can reach up to a 31.06% increase if we consider the maximum daily deviations.

How to cite: Avesani, D., Zanfei, A., Nicola, D. M., Galletti, A., Francesco, R., Maurizio, R., and Majone, B.: The role of innovative econometric models in short-term hydropower optimization, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7787, https://doi.org/10.5194/egusphere-egu22-7787, 2022.

EGU22-8044 | Presentations | HS5.2

Hydropower Portfolio Site and Design using a Simulation - Optimisation Model incorporating High Resolution Hydraulic Modelling in Data Scarce Regions 

Simbi Hatchard, Rafael J. P. Schmitt, Francesca Pianosi, James Savage, and Paul Bates

Development of hydropower in developing countries carries economic development rewards, particularly for storage hydropower which can be used to balance fluctuating supply of other renewables. Yet, dams and reservoirs carry significant environmental impacts, e.g., network fragmentation and flow alteration. While flood control has often been a motivator for reservoir construction, one environmental impact of storage hydropower on tropical rivers is the reduction of peak flows resulting in less hydraulic connectivity between floodplains and channels. In many tropical rivers, where most future dams are planned, this reduced lateral connectivity will create negative impacts on biodiversity, the biophysical functioning of floodplains, and human uses such as recession agriculture. Determining the optimal siting, design, and operation (SDO) of dam portfolios which maximises power generation and minimises this environmental impact, e.g., in terms of maintaining lateral connectivity, is a complex problem.

Simulation - Optimisation models of hydropower portfolios have often included impact on annual flood peak as a proxy objective for floodplain impacts, but have rarely explicitly included inundated area as an objective. Furthermore, when this type of analysis is done, it is usually performed at a monthly timescale, which underestimates flood peaks and neglects in-channel and floodplain hydraulics.

This work presents a multi-dam simulation - optimisation framework which uses a high-resolution hydrodynamic modelling framework (LISFLOOD-FP) to explicitly model the impact of SDO of many different dam portfolios on inundated floodplain extent, and to include this modelled extent as an optimisation objective. This incorporates channel and floodplain hydraulics at a fine time resolution, allowing a more realistic representation of the impact of hydropower development on biodiversity.

The optimisation framework is applied to the data scarce Pungwe Basin in Mozambique / Zimbabwe, and identifies significant trade-offs from mainstem damming between power production and downstream hydraulic connectivity between rivers and floodplains. It identifies Pareto Optimal combinations of site and design (large dam, small dam, and run-of-the-river installations) for these two objectives. The inclusion of hydraulically modelled inundated area represents a step forward for increasing the ability of simulation - optimisation frameworks to model complex downstream impacts of hydropower development and operation related to changing discharge and channel hydraulics.

How to cite: Hatchard, S., Schmitt, R. J. P., Pianosi, F., Savage, J., and Bates, P.: Hydropower Portfolio Site and Design using a Simulation - Optimisation Model incorporating High Resolution Hydraulic Modelling in Data Scarce Regions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8044, https://doi.org/10.5194/egusphere-egu22-8044, 2022.

EGU22-8110 | Presentations | HS5.2

New environmental restrictions - aggregate effects on the Norwegian power system 

Lennart Schönfelder, Atle Harby, Anders Arvesen, and Ingeborg Graabak

Over 93% of Norway's power production stems from hydropower. The Nordic power market is constantly transforming, current main drivers include climate change effects on hydrology, an increase of variable renewable energy production, increasing interconnector capacity, and revision of concession terms for hydropower plants. A common plant layout is comprised of a reservoir and an underground penstock leading to a downstream located hydropower plant (HPP); in many cases several reservoirs and power plants are interconnected in complex systems. Consequently, the natural hydrology of many lakes and rivers are heavily impacted by hydropower operation.

Hydropower operation is legally regulated by concessions that include regulations to limit negative environmental and societal impacts. More than 400 HPPs currently undergo a revision of terms of their concessions, which will likely impact hydropower operations and subsequently the Nordic power market. Updated or new environmental restrictions of three main types may have significant impact: 1) r 2) requirements for minimum discharge and restricted flow variation downstream of power plants and 3) filling requirements for hydropower reservoirs for the summer season. The joint effect likely has impacts on the power-balance and the hydropower system’s flexibility at multiple timescales from seconds to seasons.

The objective of this cross-disciplinary study was to investigate the impacts of an ensemble of updated or new environmental restrictions on hydropower operations and on the Norwegian power market in the future. We developed a nationwide framework to quantify probable future environmental restrictions. . Additionally, a market model dataset for a 2030 scenario was created and input data adjusted, e.g. energy mix development in grid-coupled regions such as central Europe. Implemented in a state-of-the-art market optimization model, we modelled a range of restriction scenarios for the year 2030,

We analyzed resulting future price scenarios. Preliminary results show an increase in average yearly production loss in the range of 5 TWh (or 3% of total hydropower production) due to new environmental restrictions. Modelled market response is an increase of average spot-price by about 0.8 €/MWh for all regions of Norway. Norwegian export of electricity to other countries is reduced. Another effect is that reservoir filling levels are typically higher than in the current situation, likely due to filling restrictions and model tendencies to avoid risk of violating reservoir filling restrictions, as well as increased inflow during winter.

How to cite: Schönfelder, L., Harby, A., Arvesen, A., and Graabak, I.: New environmental restrictions - aggregate effects on the Norwegian power system, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8110, https://doi.org/10.5194/egusphere-egu22-8110, 2022.

EGU22-8993 | Presentations | HS5.2

An Approach to Representing Wind Uncertainties in the Long-Term Operation Planning of Systems with Hydropower Predominance 

Maria Elvira Maceira, Albert Melo, José Francisco Pessanha, Cristiane Cruz, Victor Almeida, and Thatiana Justino

Intermittent sources, especially wind, have experienced accelerated growth - in the last decade, wind power grew 13 times in Brazil, reaching 19 GW of installed capacity in 726 wind farms and became the second largest source in the electricity mix (10%). According to the Ten Year Expansion Plan, in 2029 the wind power installed capacity will increase more than 2.5 times, reaching 39,500 MW (17.3% of the country's electricity mix).

 In Brazil, expansion and long term operation planning studies have been carried out since 1998 with the support of the NEWAVE model, which has been used in the routine and official activities of sector entities: generation dispatch by the National System Operator; calculation of the spot prices by the Whole Sale Energy Market Entity; expansion planning by the Ministry of Mines and Energy and the Energy Research Company; parameters of public auctions for the purchase of electricity by the Electricity Regulatory Agency; as well as by utilities of the power industry to develop corporate strategies.

 Currently, in accordance with the guidelines of the Electricity Regulatory Agency, the representation of wind generation in the NEWAVE model is currently carried out in a simplified manner, based on the monthly average of the last five years of net generation of each wind farm, aggregated by sub-system and load level, for the entire planning horizon.

 The objective of this work is to describe an approach to be used by the Brazilian power industry to represent the uncertainties of monthly wind power production in the SDDP algorithm applied in the long-term operation planning model, keeping the large-scale stochastic problem still computationally viable, when applied to large interconnected systems, especially with hydroelectric predominance, as is the case of the Brazilian system.

 The approach consists of four main stages: (i) statistical clustering of wind regimes and definition of equivalent wind farms; (ii) evaluation of monthly transfer functions (MTFs) between wind speed and power production; (iii) an integrated model for the generation of monthly multivariate synthetic series of inflows and winds, considering the correlations between wind speeds, between inflows and between wind speeds and inflows; and (iv) representation of the monthly wind power obtained through MTFs in the SDDP algorithm.

 Initial results obtained from the application of the proposed approach to actual configurations of the Brazilian interconnected power system are presented and discussed.

How to cite: Maceira, M. E., Melo, A., Pessanha, J. F., Cruz, C., Almeida, V., and Justino, T.: An Approach to Representing Wind Uncertainties in the Long-Term Operation Planning of Systems with Hydropower Predominance, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8993, https://doi.org/10.5194/egusphere-egu22-8993, 2022.

EGU22-9249 | Presentations | HS5.2

Run of River hydropower: in an uncertain world, is smaller financially smarter? 

Veysel Yildiz, Solomon Brown, and Charles Rougé

Run of River (RoR) hydropower plants are one of the most cost-effective energy technologies available for rural electrification and sustainable industrial expansion. These plants are characterised by a negligible storage capacity and by generation almost completely dependent on the timing and size of river flows. Their environmental footprint is minimal compared to that of reservoir-powered plants, and they are much easier to build.

RoR plants are deployed in a world with a changing hydro-climate, and in an uncertain economic context (electricity prices, interest rates, cost overruns). Through seven plants proposed in a range of hydro-climatic regions of Turkey, this work investigates whether maximising NPV (net present value), the usual design criterion, leads to financial viability for a range of possible climatic and economic futures. To assess this financial robustness, it uses and extends HYPER, a state-of-the-art toolbox that computes technical performance, energy production, maintenance and operational costs of a design at a given site (hydraulic head, flow record).

It combines HYPER with many-objective robust decision making (MORDM) to find alternatives to NPV design and assess their robustness to changing climatic and financial conditions. Our application of MORDM uses the following steps: (1) an explicit three-objective formulation is introduced to find design parameters that balance cost, revenue, and dry year (first percentile) power generation objectives, (2) coupling of a multi-objective evolutionary algorithm with HYPER to solve the problem using 1,000 years of synthetic streamflow data obtained with the Hirsch-Nowak synthetic streamflow generator, (3) sampling of deeply uncertain factors to analyse robustness to uncertain climatic and financial futures, (4) quantification of robustness based on the probability to make the plant financially viable within 10 and 20 years in each future.

Preliminary results suggest that applying MORDM approach to RoR hydropower plant design provides insights into the trade-offs between installation cost and hydropower production, while supporting design with a range of viable alternatives to help them determine which design is most robust and reliable for given site conditions and river stream characteristics. When contrasting robustness of a design with its NPV, designs with the highest NPVs do not necessarily perform well in terms of dry period revenue unless a small turbine is installed in triple turbine configuration. They also show less robustness to both climate change (and associated drying) and to evolving financial conditions than smaller design alternatives with less installed capacity. These better balance average annual revenue with dry period revenue. Preliminary results also suggest that maximising the benefit cost ratio (BCR) yields more robust and financially viable solutions than maximising NPV, as it leads to less costly designs that generate slightly less revenue on average but tend to better exploit low flows.

How to cite: Yildiz, V., Brown, S., and Rougé, C.: Run of River hydropower: in an uncertain world, is smaller financially smarter?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9249, https://doi.org/10.5194/egusphere-egu22-9249, 2022.

EGU22-10162 | Presentations | HS5.2

Potential for virtual energy storage in a wind-PV-hydropower system in Yalong River Basin, China. 

Jing Hu, Anders Wörman, Yu Li, Bingyao Zhang, Wei Ding, and Huicheng Zhou

Wind and hydropower are generally more prevalent in stormy weather conditions when solar radiation is relatively lower, which is why these renewables show complimentary characteristics over time. Similarly, weather patterns show spatial covariance. This means that spatio-temporal coordination of renewable energy production can reduce significantly the variance in the system power, hence, contribute to a virtual energy storage similar as has previously been done by matching the demand response to power availability. The 130,000 km2 Yalong River Basin in southwest China is used as an example in this study and for this basin we found typical climate-controlled periods in the renewable energy variations on periods of half a year, one year and 11-years. Based on historical hydro-climatic records, results for a planned combined wind-PV-hydropower system show that the maximum virtual energy storage has similar trends under different periods, i.e. it decreases with coordination distance and stabilizes on a coordination range of between 200 – 400 km. The maximum virtual energy storage gain was found to be 737 MWh . The project developed an existing spectral method for the analysis of the variance of the potential power and virtual energy storage in combined wind-PV-hydropower systems under different climate periods. Two different scenarios were analyzed, one in which all power stations were matched regardless of transmission constraints and one in which coordination of PV and wind power is fully centralized around single hydropower stations. The virtual energy storage gain obtained at decadal long periods, such as the 11-year cycle, can also be seen as an alternative to reserve power capacity that is activated only to avoid energy droughts. This study focused on the theoretical maximum potential for virtual energy storage, but the feasibility of this potential is limited by the uncertainty associated with production optimization and the meteorologic forecasts of future energy availability.

 
 
 
 
 

How to cite: Hu, J., Wörman, A., Li, Y., Zhang, B., Ding, W., and Zhou, H.: Potential for virtual energy storage in a wind-PV-hydropower system in Yalong River Basin, China., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10162, https://doi.org/10.5194/egusphere-egu22-10162, 2022.

EGU22-10328 | Presentations | HS5.2

Territorial analysis for energy supply of western Turin area from alternative renewable sources: impact and potential 

Arianna Paschetto, Chiara Caselle, Claudia Leso, Fabrizio Manfroni, and Sabrina Maria Rita Bonetto

It is now generally assumed that a radical reversal in economy is needed in order to cope with the effects of climate changes and to improve the resilience of populations in relation to these effects.

In fact, European policies for climate change and economic recovery due to Covid-19 (Guidance to Member States, Recovery and Resilience Plans, 8th Environmental Action Program) are supposed to work in synergy to promote green and efficient energies, shifting the cost/benefit ratio in favor of renewable natural resources. As part of these policies, Italy is increasing the number of mini hydroelectric plants (max. power of 1000 kW), which are considered advantageous both in economic and environmental terms without being in contrast with the surrounding environment.

The aim of this study is the evaluation of potential production of hydroelectric energy, by means of mini hydroelectric, in the western area of ​​Turin, considering lowland areas (such as the Municipalities of Collegno, Druento and Alpignano) and high valley areas such as the Municipality of Coazze and upper Sangone Valley. In these investigated area, the development of mini hydroelectric could possibly result in partial or entire energy self-sufficiency.

In order to comply with environmental policies, a feasibility study will be conducted, based on geological, hydrogeological, morphological, ecological and climatic components.

The study will also be congruent with European and national guidelines regarding the Environmental Impact Assessment, so as to evaluate any possible plant locations in terms of environmental impact.

The geological and geomorphological data collected will also be employed to evaluate the possibility of reuse of the materials which could possibly accumulate in the reservoirs, in accordance with the policies of the Green Communities.

How to cite: Paschetto, A., Caselle, C., Leso, C., Manfroni, F., and Bonetto, S. M. R.: Territorial analysis for energy supply of western Turin area from alternative renewable sources: impact and potential, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10328, https://doi.org/10.5194/egusphere-egu22-10328, 2022.

As an important renewable energy source, hydropower can meet China's needs for sustainable decarbonization. But it is very sensitive to climate change, and the occurrence of hydrological droughts will have a severe impact on hydropower. The significant decline in hydropower supply in dry years or seasons increases the demand for other power resources, especially fossil fuel, which will further increase greenhouse gas emissions. In the future, seasonal droughts are expected to change in the context of global warming, and their impact on hydropower generation needs to be studied, especially over the Yangtze River basin that has the largest hydropower resources and potential in China. In this study, the characteristics of seasonal hydrological drought events under historical and future climate conditions are analyzed in the Yangtze River Basin, and the PCR-GLOBWB hydrological model is further used to simulate the changes of water resources and hydropower generation under drought conditions. This study is beneficial to bring extreme events into the consideration of hydropower development and operation planning in China, and provides scientific basis for ensuring the safety of hydropower system.

How to cite: Liu, X. and Yuan, X.: Impacts of future changes in seasonal hydrological drought on hydropower potential in the Yangtze River Basin, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10963, https://doi.org/10.5194/egusphere-egu22-10963, 2022.

EGU22-12440 | Presentations | HS5.2

The value of incorporating technological uncertainty in adaptive infrastructure planning – a conceptual example in hydropower investment 

Kevis Pachos, Jose M. Gonzalez, Tohid Erfani, Mohammed Basheer, Eduardo Martínez-Ceseña, Mathaios Panteli, and Julien J. Harou

In response to the increasing environmental concerns, there has been significant research and development of power generation technologies based on renewable energy sources (RES) such as solar, and hydrogen. On the one hand, the technologies are becoming more attractive by offering higher efficiencies and lifetimes, and lower costs. On the other hand, it has become challenging to cost-effectively plan and deploy RES technologies as their characteristics have become significantly more uncertain. This can have strong impacts on other established renewable generation technologies, such as hydropower, which might become less or more attractive depending on technological change. Furthermore, in the context of interlinked water-energy systems, RES impacts on hydropower can have cascading effects on water use. Accordingly, decision makers require improved planning strategies to “adapt” to technological change when making long-term planning and investment decisions. 

This work explores how considering RES, namely solar and hydrogen, alongside their technological uncertainties related to installation costs and lifetimes, would impact hydropower investments in an adaptive plan. Based on a conceptual case study of a water-energy system, we demonstrate that hydropower investments could be delayed and/or reduced because of the possibility of efficiency improvements related to renewable energy technologies. Furthermore, we quantify the forgone financial value from not using adaptive approaches to design and plan infrastructure projects under technological uncertainty.

How to cite: Pachos, K., Gonzalez, J. M., Erfani, T., Basheer, M., Martínez-Ceseña, E., Panteli, M., and Harou, J. J.: The value of incorporating technological uncertainty in adaptive infrastructure planning – a conceptual example in hydropower investment, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12440, https://doi.org/10.5194/egusphere-egu22-12440, 2022.

EGU22-13005 | Presentations | HS5.2

On the needs to evaluate power grid models’ hydropower scheduling with a river operations model 

Nathalie Voisin, Tim Magee, Sean Turner, Mitch Clement, Konstantinos Oikonomou, and Edith Zagona

Production Cost Models (PCMs) simulate the economic dispatch of generators across a large power grid and are used widely by planners to study the reliability of electricity supply. As energy systems transition away from the thermoelectric technologies that have traditionally balanced electricity supply and demand, hydropower and its representation in PCMs is of increasing importance for storage and ramping capabilities. A limitation of PCMs applied to continental power grids with diverse generation portfolios is that hydropower generation is simulated without full consideration of complex river dynamics, leading to possible misrepresentation of grid flexibility and performance.

Using a detailed hydropower model, we evaluate whether the hourly hydropower schedule from a PCM with simplified monthly parameterization can be attained when accounting for realistic river dynamics, such as spill requirements and general water movement through a cascading reservoir system. We perform this hydropower generation test for the “Big 10” hydropower system on the Columbia River (part of the Western Interconnect of the United States), revealing 9% overestimation of available hydropower generation in a PCM solution in an average hydrologic year.

We reflect on the sources of differences with implications onto long term planning practices expected to address uncertainties associated with energy transitions, climate change, environmental regulation and competing water uses.

How to cite: Voisin, N., Magee, T., Turner, S., Clement, M., Oikonomou, K., and Zagona, E.: On the needs to evaluate power grid models’ hydropower scheduling with a river operations model, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13005, https://doi.org/10.5194/egusphere-egu22-13005, 2022.

ERE3 – Geo-storage

EGU22-375 | Presentations | ERE3.1

Regional characterization of stacked storage units for potential CO2 sequestration in Western Nebraska, USA 

Samuel Fleagle, Caroline Burberry, and Seunghee Kim

 

In Nebraska, most electricity comes from burning fossil fuels, which is estimated to emit 15 million tons of CO2 per year. Additionally, ethanol plants in Nebraska are estimated to emit 4 million tons of CO2 annually. CCS enables those industries to continually operate whilst emitting far fewer greenhouse gases. The study area of this project covers Western Nebraska  not fully evaluated to date.  We postulate there is extensive storage space in the subsurface of Western Nebraska.  The storage space needs to be a formation or formations that meet the following criteria: extensive in the study area, porous, deep (greater than 2600 feet below ground surface) and situated below a primary and secondary stratigraphic or structural seal. 

We plan on using existing well call outs (available through Nebraska Oil and Gas Commission’s website) and wireline logs to construct a lithostratigraphic and structural framework for potential storage and seal units.  Additionally, we will use GIS to create maps of formations and isopach maps to model unit thickness.  We also propose to log core in Denver at the USGS Core Storage facility or at the Nebraska Conservation and Survey Division to further understand the stratigraphy.  Subsequently, geophysical data (seismic, aeromagnetic, and gravimetric) will be utilized to delineate regional structures in detail. Lastly, we will conduct geomechanical tests on core samples to evaluate porosity, permeability, stiffness, and strength of target units to estimate specific CO2 storage volume capacity. 

The hope is to provide Western Nebraska with storage space for 50 million tons of CO2 within the project area.   The subsurface storage of CO2 is critical to global efforts to reduce the effects of greenhouse gas- induced climate change.   Reducing emissions will improve local air quality and aid in the larger goal of curtailing emissions of greenhouse gases to mitigate the impacts of climate change. 

 

  

How to cite: Fleagle, S., Burberry, C., and Kim, S.: Regional characterization of stacked storage units for potential CO2 sequestration in Western Nebraska, USA, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-375, https://doi.org/10.5194/egusphere-egu22-375, 2022.

EGU22-576 | Presentations | ERE3.1

Using small, land-based seismic arrays to monitor microseismicity induced by CO2 storage 

Victor Vescu, Tom Kettlety, J. Michael Kendall, James P. Verdon, Antony Butcher, and Shawn Goessen

Carbon capture and storage involves removing CO2 from industrial emissions or the atmosphere and sequestering it in a pressurised form. Onshore or offshore injection sites pump the liquefied CO2 below ground, preventing its release into the atmosphere. Earthquakes can occur when fluid is injected into a formation, inducing stress changes that can act on nearby faults, resulting in a rupture. The physics of these ruptures and the effect that fault lubrication processes have in triggering them remain key topics of research. Real-time microseismic monitoring at injection sites is the most readily available tool for painting a better picture. Injection sites on land are easier to monitor, with instruments requiring relatively little maintenance. Offshore sites, however, are more costly and less convenient because local monitoring could require expensive ocean-bottom instruments and complex deployment procedures. Induced microseismicity at CO2 injection sites is a critical measure of the reservoir and cap rock's response to injection. Thus, there is a need to locate events with low uncertainty, particularly in-depth.

There are plans for several megatonne-scale offshore CO2 injection projects around the UK. Microseismicity at these sites must be well monitored over decades to ensure long term storage security, requiring novel, cost-effective monitoring strategies. We attempt to constrain the effectiveness of small, land-based arrays that could be used to deliver relatively low-cost monitoring and map out the areas of highest risk from induced seismicity. This study compares the data of such an array installed in northwest England with the national seismic network operated by the British Geological Survey (BGS). We analyse the capability of the array to detect and locate low magnitude (M<3) seismic events. Finally, we examine how to perfect array deployment for CO2 storage monitoring by modelling the optimum size and spatial distribution of small seismic arrays.

How to cite: Vescu, V., Kettlety, T., Kendall, J. M., Verdon, J. P., Butcher, A., and Goessen, S.: Using small, land-based seismic arrays to monitor microseismicity induced by CO2 storage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-576, https://doi.org/10.5194/egusphere-egu22-576, 2022.

EGU22-1645 | Presentations | ERE3.1

Geological perspectives of offshore underground hydrogen storage in Ireland 

Zhipeng Xiao, Cian Desmond, Paul Stafford, and Zili Li

Rapid development of renewable sources (e.g., wind turbines and geothermal energy) has been increasing the market share of renewable energy in electricity production in Ireland with a target of 70% by 2030. However, the production of renewable energy is usually fluctuating, which necessitates the strategies and technologies to match intermittent electricity generation surplus with time-varying market demand. Hydrogen gas generated from surplus renewable electricity has been acknowledged to be a promising energy carrier for balancing this energy gap. In particular, underground hydrogen storage in geological formation emerges as an economically effective and reliable method to store the gas on a large scale. To this end, it is essential to develop a comprehensive understanding of the suitable geological settings for underground hydrogen storage.

This paper investigates various geological settings in Ireland for different types of offshore underground hydrogen storage (e.g., salt caverns, depleted hydrocarbon fields, and aquifers). For each Irish offshore basin, an assessment is conducted to evaluate the potential application of underground storage methods and associated safety & serviceability concerns. The result confirms some prospective areas for different options of hydrogen underground storage at specified conditions. In particular, the offshore sedimentary basins of western and southern Ireland are considered to be suitable UHS geological settings. These shortlisted suitable geological settings deserve further investigation in greater details for the subsequent design & construction of hydrogen underground storage projects.

How to cite: Xiao, Z., Desmond, C., Stafford, P., and Li, Z.: Geological perspectives of offshore underground hydrogen storage in Ireland, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1645, https://doi.org/10.5194/egusphere-egu22-1645, 2022.

EGU22-1787 | Presentations | ERE3.1

Stress history and reservoir pressure for improved quantification of CO2 storage containment risks (SHARP Storage) 

Tine B. Larsen, Elin Skurtveit, Philip Ringrose, Kees K. Hindriks, Daniela Kühn, Dan Roberts, J. Michael Kendall, Marie Keiding, Auke Barnhoorn, and Devendra N Singh and the SHARP Team

The SHARP project was launched in late 2021 as a collaboration between 16 research institutions and commercial companies in Norway, UK, the Netherlands, Denmark, and India under the ACT3 Programme. The project is interdisciplinary with a strong focus on understanding and reducing the uncertainties related to subsurface CO2 storage containment risk focusing on the geomechanical aspects of CO2 storage.

The geomechanical response to CO2 injection is one of the key uncertainties in assessing proposed storage sites. The main aim of the SHARP project is to mature the technology for quantification of subsurface deformation by the development and integration of models for subsurface stress, rock mechanical failure and seismicity. Key activities for the project include: developing basin-scale geomechanical models that incorporate tectonic and deglaciation effects and use newly developed constitutive models of rock/sediment deformation (WP1);  improving knowledge of the present-day stress field in the North Sea from integrated earthquake catalogues and developing a database of earthquake focal mechanisms (WP2); quantifying rock strain and identifying failure attributes suitable for monitoring and risk assessment using experimental data (WP3); developing more intelligent methods for in situ monitoring of rock strain and failure as part of the overall monitoring programmes (WP4); quantifying containment risks using geomechanical models and observations from the field and laboratory (WP5); and communicating technology development on containment risk to industry and regulators (WP6).

The SHARP project is expected to accelerate the maturation of six sites from the North Sea region and India. The case study sites range from very mature projects such as the Northern Lights CO2 storage project in the Horda area (N) to emerging storage prospects such as the Endurance site (UK) and the Hanstholm structure (DK). Furthermore, application of the methods to well-characterised offshore depleted oil and gas fields as Nini (DK) and Aramis (NL) will accelerate their transformation into viable and safe CO2 storage sites. India has high focus on emission reduction including development of CCUS and an onshore case study for CO2 injection will be matured using lessons learned from the European projects in order to kick-start CO2 injection and storage projects in India.

Involvement of international CO2 storage operators in the consortium ensures that the SHARP project has a high impact on CCS development in Europe and India, as well as globally. New technologies for quantification of subsurface deformation and strategies for monitoring deformation and fluid flow will provide cost-efficient tools for CO2 subsurface risk management. The results of the project will be communicated to storage site operators and regulators to increase confidence in storage safety and seismicity risk assessment.

How to cite: Larsen, T. B., Skurtveit, E., Ringrose, P., Hindriks, K. K., Kühn, D., Roberts, D., Kendall, J. M., Keiding, M., Barnhoorn, A., and Singh, D. N. and the SHARP Team: Stress history and reservoir pressure for improved quantification of CO2 storage containment risks (SHARP Storage), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1787, https://doi.org/10.5194/egusphere-egu22-1787, 2022.

As an alternative to water, CO2 can be used for heat mining from geothermal reservoirs, while also trapping most of the injected CO2 underground. In addition, supercritical CO2 has higher mobility and heat capacity than water, rendering CO2 capture, utilization and storage (CCUS) in geothermal reservoirs a very attractive option in a circular carbon economy. CCUS is also in line with Saudi Vision 2030, which includes the strategic framework to reduce Saudi Arabia’s dependence on hydrocarbons and diversify its economy. The western coast of Saudi Arabia, where the young and high-heat-flow Red Sea rift basins are located, are considered suitable for geothermal heat extraction and CO2 storage. In this study, we explore the potential of CCUS for geothermal power generation and CO2 storage in the hydrothermal reservoirs of Al Wajh basin located on the Red Sea coast.

Geological studies in Al Wajh basin report that the hot fluid bearing, thick, porous, siliciclastic formations, such as Al Wajh (formation’s top depth, TD= 3900 meters), Burqan (TD = 2880 m) and Jebel Kibrit (Umluj member with TD = 1930 m) are sealed by the overlying anhydrite (Kial) and salt formations (Mansiyah). We combine publicly available data with different resolution scales, such as satellite gravity, seismic sections and well-log information to build a 3D geologic model, which enables us to constrain the 3D gross rock volume and the Net-to-Gross ratio/distribution of the target hydrothermal reservoirs. A 3D temperature model shows that the average surface temperature in the region and the subsurface temperature gradient create formation fluid temperature of over 120o C at 3 km depth.

We conduct reservoir simulation of coupled transport of formation fluid, injected non-condensable gas (CO2) and heat in heterogeneous 3D reservoir model, using CMG STARS. We then estimate the geothermal energy extracting capacity and storage efficiency of CO2 in the prospective hydrothermal reservoirs in the Al Wajh basin. Our study provides the first semi-realistic reservoir model and simulation study in Saudi Arabia for combined CO2-based geothermal power generation and CO2 storage potential at a designated target site. The work-flow we propose is transferable to other suitable hydrothermal reservoirs in different locations in Saudi Arabia, thereby enabling CCUS technology implementation along the Red Sea.

How to cite: Yalcin, B., Ezekiel, J., and Mai, P. M.: CO2 injection and storage for geothermal power generation in hydrothermal reservoirs along the Red Sea of Western Saudi Arabia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2199, https://doi.org/10.5194/egusphere-egu22-2199, 2022.

EGU22-2321 | Presentations | ERE3.1

Bridging experimental analysis to reservoir models: a geochemical modelling approach for Carbon Capture Storage 

Maria Vittoria Beduschi, Claudio Geloni, Fabrizio Gherardi, Simone Ricci, and Giovanni Toscani

Geological storage of carbon dioxide in depleted gas reservoirs or deep saline aquifers is one of the techniques to reduce CO2 in atmosphere and mitigate the greenhouse effects on climate changes.

A Carbon Capture Storage (CCS) plan is composed of different steps (capture, transportation, injection, monitoring just to cite a few) and a comprehensive multidisciplinary investigation must be carried out to define site-specific storage capacity/efficiency, formation injectivity and monitoring, both in short and long terms.

Especially in studying subsurface processes, geological, hydrogeological, petrophysical, mineralogical and geochemical information must be integrated, to evaluate, and possibly predict/quantify, the effects of the dissolution-precipitation processes driven by CO2injection and the consequent changes in petrophysical properties of the rocks.

In this framework, numerical modelling can play a role of primary importance especially if it can be supported by a complete set of experimental data. To this purpose, a workflow has been recently developed according to the following steps:

  • Core description and sample selection, to assure representativeness for the storage complex
  • Mineralogical, petrographic, petrophysical, gas and water chemical data acquisition
  • Data elaboration and integration to propose a conceptual model
  • Numerical simulations
  • static models: geochemical validation
  • dynamic: CO2injection and reactive migration

Point 4 is the main focus of this work which aims at describing (i) the near wellbore migration of CO2and its effects on injectivity, and (ii) the behavior of specific sedimentary lithologies once they have come into contact with CO2. For this purpose, a sequence of models has been developed, with a growing degree of complexity. 0D pure geochemical models are used to investigate rock reactivity (thermodynamic and kinetic) by taking advantage of the very low computational cost of these models.

The limitations of neglecting mass migration are then overcome by performing 1D cartesian models which are in turn also used to calibrate petrophysical parameters of more CPU-demanding 2D radial models set up for simulating CO2injection at well scale.

The numerical investigation will be concluded by using a real 3D reservoir model to predict more realistically the dynamics of CO2migration in the storage complex and its effects on the lithology and petrophysical properties. This last step represents the ideal link/bridge between experimental activity and reservoir models.

All the numerical simulations are carried-out with an Eni-internal software platform (e-muflot, Multiphase Flow and Transport) developed to represent reactive transport in dynamic reservoir models.

How to cite: Beduschi, M. V., Geloni, C., Gherardi, F., Ricci, S., and Toscani, G.: Bridging experimental analysis to reservoir models: a geochemical modelling approach for Carbon Capture Storage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2321, https://doi.org/10.5194/egusphere-egu22-2321, 2022.

Gas leakage from deep geologic storage formations to the Earth’s surface is one of the main hazards in geological carbon sequestration and storage. Permeable sediment covers or natural and artificial pathways, such as faults and well structures, are the main factors controlling surface leakages. Therefore, the characterization of natural systems, where large amounts of CO2 are released, can be helpful for understanding the effects of potential gas leaks from storage carbon systems. In this framework, we propose a combined use of geoelectrical investigations (i.e., resistivity tomography and self-potential surveys) for characterizing natural CO2 leakage areas, as well as gas storage sites. Such methodologies appear to be among the most suitable for revealing spatial distributions of carbon dioxide and monitoring subsurface fluid migration processes, because of the strong dependence of the electrical properties of water-bearing permeable rock, or unconsolidated materials, on many factors relevant to CO2 storage (i.e., porosity, fracturing, water saturation, etc.). Indeed, the electric resistivity of porous water-bearing sediments decreases significantly when CO2 dissolves in pore-water, in contrast to the effect in the gas phase and supercritical CO2, while the anomalous concentrations of natural electric charge are directly related to carbon dioxide migration along porous and fractured rock systems. The effectiveness of the suggested multi-methodological geoelectrical approach is tested in some areas of natural CO2 degassing located in the Southern Apennines (Italy), which could represent natural analogues of gas storage sites. Specifically, electrical resistivity and self-potential surveys are targeted at reconstructing shallow buried fracture networks in the cap-rock and detecting preferential CO2 migration pathways. Our findings are promising for imaging the CO2 plume within a carbon storage reservoir and for identifying possible CO2 leakages through the cap-rock formation, suggesting that the proposed approach can be very helpful also for the monitoring of carbon sequestration systems.  

How to cite: Salone, R., De Paola, C., Ferranti, L., and Di Maio, R.: Understanding the effects of leaking gas in geological carbon sequestration through geophysical characterization of natural CO2 gas emission systems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2440, https://doi.org/10.5194/egusphere-egu22-2440, 2022.

EGU22-2458 | Presentations | ERE3.1

Hydrogen recovery from porous media decreases with brine injection pressure and increases with brine flow rate    

Eike Marie Thaysen, Ian B. Butler, Damien Freitas, Aliakbar Hassanpouryouzband, Fernando Alvarez-Borges, Robert Atwood, Bob Humphreys, and Katriona Edlmann

Zero carbon energy generation from renewable sources can reduce climate change by mitigating carbon emissions. A major challenge of renewable energy generation is the imbalance between supply and demand. To overcome the energy imbalances, subsurface storage of hydrogen in porous mediais suggested as a large-scale and economic solution, yet its mechanisms are not fully understood. Important unknowns are the effect of the high migration potential of the small and mobile hydrogen molecule and the volume of recoverable hydrogen.

We conducted non-steady state, cyclic hydrogen and brine injection experiments at 2-7 MPa and flow rates of 2-80 µl min-1 using water-wet Clashach sandstone cylinders of 4.7 mm diameter and 53-57 mm length (Clashach composition: ~96 wt.% quartz, 2% K-feldspar, 1% calcite, 1% ankerite). Two sets of experiments were performed using our new transparent flow-cell designed for x-ray computed microtomography: 1) Experiments using a laboratory x-ray source (University of Edinburgh) imaged the flow, displacement and capillary trapping of hydrogen  by brine as a function of saturation after primary drainage and secondary imbibition. 2) Experiments using synchrotron radiation (Diamond Light Source, I12-JEEP tomography beamline) captured time-resolved hydrogen and brine flow and displacement processes. Pressure and mass flow measurements across the experimental apparatus complemented the microtomography volumes in both sets of experiments.

Results from a water-wet rock show that hydrogen behaves as a non-wetting phase and sits in the centre of the pore bodies, while residual brine sits in corners and pore throats. Hydrogen saturation in the pore volume is independent of the injection pressure and increases with increasing hydrogen/brine injection ratio up to ~50% saturation at 100 % hydrogen. Capillary trapping of hydrogen during brine imbibition occurs via snap off and is greatest at higher brine injection pressures, with 10 %, 12% and 21% hydrogen trapped at 2, 5 and 7 MPa, respectively. Higher brine flow rates reduce capillary trapping and increase hydrogen recovery at any given injection pressure. Based on these results, future hydrogen storage operations should inject 100% hydrogen and manage the reservoir pressure to avoid high pressures and minimize capillary trapping of hydrogen during brine reinjection.

Ongoing analysis of time-resolved experimental data will provide further insight into the critical pore-scale processes that ultimately influence the potential for geological hydrogen storage and recovery.

How to cite: Thaysen, E. M., Butler, I. B., Freitas, D., Hassanpouryouzband, A., Alvarez-Borges, F., Atwood, R., Humphreys, B., and Edlmann, K.: Hydrogen recovery from porous media decreases with brine injection pressure and increases with brine flow rate   , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2458, https://doi.org/10.5194/egusphere-egu22-2458, 2022.

EGU22-3064 | Presentations | ERE3.1

GPSFLOW: A Novel Simulator for Modelling Underground Hydrogen, CO2 and Gas Mixture Storage 

Zuansi Cai, Keni Zhang, and Chaobin Guo

Underground hydrogen storage can store grid-scale energy for balancing both short-term and long-term inter-seasonal supply and demand. However, there is no numerical simulator which is dedicated to the design and optimisation of such energy storage technology at grid scale. This study develops novel simulation capabilities for GPSFLOW (General Purpose Subsurface Flow Simulator) for modelling grid-scale hydrogen and gas mixture (e.g., H2-CO2-CH4-N2) storage in cavern, deep saline aquifers and depleted gas fields.

The accuracy of GPSFLOW is verified by comparisons against the National Institute of Standard and Technology (NIST) online thermophysical database and reported lab experiments, over a range of temperatures from 20-200 oC and pressure up to 1000 bar. The simulator is benchmarked against an existing model for modelling pure H2 storage in a synthetic aquifer. Several underground hydrogen storage scenarios including H2 storage in a synthetic salt cavern, H2 injection into a CH4-saturated aquifer experiment, and hydrogen storage in a depleted gas field using CO2 as a cushion gas are used to test the GPSFLOW’s modelling capability. The results show that GPSFLOW offers a robust numerical tool to model underground hydrogen storage and gas mixture at grid scale on multiple parallel computing platforms.

How to cite: Cai, Z., Zhang, K., and Guo, C.: GPSFLOW: A Novel Simulator for Modelling Underground Hydrogen, CO2 and Gas Mixture Storage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3064, https://doi.org/10.5194/egusphere-egu22-3064, 2022.

Carbon capture and storage (CCS) gains much attention as it contributes to mitigating climate change. However, during CCS, the periodic injection of pressurized CO2 leads to strong thermal cycling and shocks in the subsurface, due to the endothermic expansion of pressurized CO2 upon injection. Under these temperature variations, the wellbore and subsurface formations cyclically contract and expand. As a result, leakage pathways such as micro-annuli between wellbore casing and cement, and cracks in the cement can develop. They impair well integrity, and thus impede safe geological storage of CO2. Therefore it is of significance to understand how the sealing ability of the cement sheath of CCS wells is affected by thermal cycling or shocks.

In this paper, we report a novel technique to investigate cracking in cement by thermal shocks under in-situ temperature and pressure. To this end, we use a triaxial deformation apparatus capable of mounting a cement sample in a vessel at a confining pressure of up to 70 MPa, with an axial stress up to 26 MPa. An internal furnace is used to achieve an elevated temperature in the vessel. Pore fluid lines are fitted in upper and lower axial pistons to allow water injection. In this study, we use a solid neat cement sample ( Φ30*70 mm, water-to-cement ratio: 0.3) cured at 20ºC and ambient pressure for 28 days. During the experiments, the triaxial vessel is filled with heat-resistant oil which provides the confining pressure. The cement sample is isolated from the oil using a thin Teflon jacket. We load the sample at different in-situ states of hydrostatic stress and heat the sample assembly to various elevated temperatures (60 - 120ºC). We then inject cold water (20ºC) through the sample using two high-pressure syringe pumps at a designated flow rate for a given time. In the vessel, three linear variable differential transducers (LVDT) mounted parallel to, and span around the sample are used to calculate axial and radial strain, respectively. Two thermocouples, one mounted on the middle of the sample (outside the jacket), and another inside the upper pore fluid line, are used to measure temperature. To study how and where cracks initiate and grow in the cement under thermal shocks, we measure permeability with a differential pressure transducer measuring the difference between the up- and down-stream pore fluid line, and we use a micro-computed tomography ( μ-CT) scanner to characterize the microstructure of the cement sample before and after the experiments. This provides valuable expedience to investigate the thermal effects on the integrity of cement under different in-situ conditions for CCS wells. The pistons of the setup can also be readily adjusted to study how de-bonding between casing and cement, and cracks in the cement develop for composite cement samples (with analogous casing) under thermal cycling.

 

 

How to cite: Li, K. and Pluymakers, A.: A Novel Technique to Investigate Thermal-Induced Cracking in Cement under In-Situ Conditions for CCS Wells, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3186, https://doi.org/10.5194/egusphere-egu22-3186, 2022.

EGU22-4396 | Presentations | ERE3.1

Storing CO2 in Geothermal Reservoir Rocks: A Laboratory Study on Acoustic and Mechanical Properties 

Martijn Janssen, Elara Redondo Garcia, Auke Barnhoorn, Deyan Draganov, and Karl-Heinz Wolf

This work is conducted within the framework of SUCCEED, a research consortium with the aim to validate the utilization of produced CO2, from the Hellisheiði geothermal plant in Iceland, for re-injection into the field for: i) pressure maintenance, and thus promoting geothermal production, and ii) permanent storage in basaltic formations through CO2 mineralisation. The objective of work carried out at Hellisheiði in SUCCEED is to provide a state-of-the-art, cost-effective, and low-environmental impact coupled geothermal-CO2 storage monitoring technique. In this work, a detailed seismic-velocity and mechanical behaviour-characterisation study was carried out on various rock formations present at the outcrops near the Hellisheiði geothermal site.

Laboratory experiments include well-controlled active-source acoustic-assisted unconfined (UCS) and confined (CCS) compressive strength tests. Where the former, i.e., UCS, allow for investigating the mechanical behaviour, or static elastic properties, of the assessed rock formations, the latter, i.e., CCS, shed light on the seismic velocities at field-representative stress conditions (up to 70 MPa). The abovementioned experiments were conducted at ambient temperature and at dry pore-space conditions. For studying pore-scale phenomena (e.g., number of connected pores, mineralogy, etc.), several thin sections were prepared and micro computed tomography (micro-CT) scans were taken.

The studied rock formations included basalts with varying porosities (ranging from 22 to 51 %), i.e., the main reservoir formation, hyaloclastites, and dykes. Micro-CT scan analyses, conducted on the basaltic reservoir formation in Hellisheiði, revealed that its pore structure is highly heterogeneous. Active-source acoustic-assisted UCS tests showed similar velocity – stress trends: a rapid increase in velocity at low stress levels, related to closure of potential microcracks (and thus compaction), followed by a more modest increase at higher levels of axial stress. The pyroclastic hyaloclastite appeared to be the weakest material assessed, revealing relatively low seismic velocities, a static Young modulus of 2.54±0.09 GPa, and an ultimate strength of around 4.3 MPa. On the contrary, the igneous intrusion, i.e., dyke, is by far the stiffest material studied, yielding a Young modulus of 34.85±0.39 GPa and an ultimate strength of more than 200 MPa. The investigated basalt samples indicated a porosity-dependent Young modulus and compressional-wave velocity, where both the modulus and velocity decrease significantly with increasing (connected) porosity following a power-law function.   

How to cite: Janssen, M., Redondo Garcia, E., Barnhoorn, A., Draganov, D., and Wolf, K.-H.: Storing CO2 in Geothermal Reservoir Rocks: A Laboratory Study on Acoustic and Mechanical Properties, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4396, https://doi.org/10.5194/egusphere-egu22-4396, 2022.

EGU22-5158 | Presentations | ERE3.1

Mineralogical and chemical changes induced by experiments of interaction between supercritical CO2 and plutonic mafic rocks. A case study in Portugal. 

Patrícia Moita, Edgar Berrezueta, Halidi Abdoulghafour, Massimo Beltrame, José Mirão, Carlos Ribeiro, Pedro Barrulas, Jorge Pedro, and Júlio Carneiro

The focus of this research is a qualitative study of mineralogical and chemical changes in plutonic mafic rock samples after exposure to a CO2-rich brine, under supercritical conditions (SC), to clarify the behavior of brine and rock in the initial stages of mineral carbonation. The studied rock consists of a gabbro-anorthosite from the Odivelas massif, in southern Portugal. The sample was exposed to a SC CO2-rich brine (P≈8 MPa, T≈40C) for runs of 0, 30 and 90 days. Experiments were conducted in batch mode, ie. with no CO2 flow, and with a proportion of CO2 to brine of 0.226 for 30 days and 0.033 for 90 days. In addition, numerical modeling was applied to complement the experimental observations, reproducing the experimental observations and simulate the chemical behavior for longer times. The chemical analysis of the brine, before and after, the experiment, shows: (i) increase of magnesium (Mg2+), calcium (Ca2+) and silica (SiO2) for the 30 and 90 days runs and (ii) decrease of pH (8.1 to 6.1 and 8.1 to 6.3, respectively). Experimental and numerical results indicate that the rock sample suffered a slight dissolution process with mineralogical/textural readjustments on the external area of the specimens studied. This is thought to mimic the initial dissolution process under early-stage mineral carbonation. After 90 days, apart from halite, there are no significant new mineral phases. However, the elemental association in the EDS maps of carbon and magnesium dissociated from silicon suggests the residual crystallization of magnesite.

 

How to cite: Moita, P., Berrezueta, E., Abdoulghafour, H., Beltrame, M., Mirão, J., Ribeiro, C., Barrulas, P., Pedro, J., and Carneiro, J.: Mineralogical and chemical changes induced by experiments of interaction between supercritical CO2 and plutonic mafic rocks. A case study in Portugal., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5158, https://doi.org/10.5194/egusphere-egu22-5158, 2022.

EGU22-5406 | Presentations | ERE3.1

Can remote green hydrogen production play a key role in decarbonizing Europe? A cradle to gate LCA of hydrogen production in Austria, Belgium and Iceland. 

Kristjan Vilbergsson, Kevin Dillman, Nargessadat Emami, Einar Ásbjörnsson, Jukka Heinonen, and David Finger

There has been a global spike in interest in using hydrogen as an energy carrier to decarbonize hard-to-abate sectors. From a European perspective, with the interest in greater use of hydrogen for this purpose, EU member states are considering varied means to either produce hydrogen nationally or to import remotely-produced H2. However, the mitigation potential of hydrogen is heavily dependent on how the hydrogen is produced (i.e. steam methane reforming or electrolysis) and under what conditions (i.e. using CCS technologies or for electrolysis the source of the electricity used). Thus, a variety of studies have considered the life cycle impacts of different hydrogen production conditions, taking into account different sources of electricity during electrolysis, operating hours (i.e. for when using intermittent renewable energy technologies), and transportation of the hydrogen. However, these different conditions are often studied in isolation, making cross-comparisons needed to assess the environmental trade-offs of locally produced versus imported hydrogen difficult. Therefore, to allow for such an assessment in this study, we consider the life cycle impacts of H2 production temporally and spatially, at three different locations in Iceland, Austria, and Belgium using locally available renewable energy sources, as well as the local grids in each location. Our cradle to gate life cycle assessment includes the transport from the production site to the final utilization site at potential gates in Europe. Our results indicate that the carbon footprint of H2 production depends primarily on the energy mix, while transportation of H2 generates a minor impact.

How to cite: Vilbergsson, K., Dillman, K., Emami, N., Ásbjörnsson, E., Heinonen, J., and Finger, D.: Can remote green hydrogen production play a key role in decarbonizing Europe? A cradle to gate LCA of hydrogen production in Austria, Belgium and Iceland., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5406, https://doi.org/10.5194/egusphere-egu22-5406, 2022.

EGU22-5460 | Presentations | ERE3.1

Hydrogen storage potential in the Upper Rhein Graben area 

Johannes Miocic and Niklas Heinemann

Energy storage is thought to be a crucial part of renewable energy systems as it helps to alleviate the main drawbacks of renewable energy generation: their intermittency and seasonal and geographical constrains. Subsurface storage of hydrogen is one often cited option for geological energy storage and may facilitate the energy transition. Hydrogen can be stored in porous media, such as saline aquifers and depleted hydrocarbon reservoirs, and in engineered salt caverns.

The Upper Rhine Graben (URG) lies within the tri-national Upper Rhine Region where across-boarder decarbonisation scenarios require energy storage infrastructure. Here, we analyse the hydrogen storage potential of sedimentary formations within the URG based on available geological data and models. While the deeply buried sandstones of the Permo-Triassic have generally low permeabilities and porosities and only form fractured reservoirs which have limited suitability for hydrogen storage, Paleogene deposits have some storage potential and host also numerous hydrocarbon reservoirs which may be reutilised. Salt diapirs in the southern URG have the potential to hold many engineered salt caverns with significant storage potential, however the geological knowledge of the internal structure of the salt diapirs is limited. Overall, the potential of geological hydrogen storage within the URG is in the order of several TWh.

 

How to cite: Miocic, J. and Heinemann, N.: Hydrogen storage potential in the Upper Rhein Graben area, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5460, https://doi.org/10.5194/egusphere-egu22-5460, 2022.

Recently, CO2 storage has become one of the most effective ways to counteract greenhouse gas emissions and contribute to the global carbon neutrality agreement. To ensure containment, it is important to know how geological layers surrounding the targeted reservoirs will serve as a seal to injected fluids, in particular where the overburden and reservoirs are affected by faults. One of the main controlling factors for gas leakage is through fault networks. Studying worldwide areas of natural gas emission is therefore useful in understanding the risk of potential gas leakage associated with CO2 storage. From a range of geological scales, reviewing cases of natural gas leakage through in-house and published datasets, can help us understand the various geological factors which influence a region to be more or less susceptible to vertical fluid escape. In this study, a review of CO2 and CH4 (Methane) surface leaks is mapped using Geographical Information Systems (ArcGIS Pro). Moreover, a relationship between CO2 and CH4 leakages and the global strain map, stress map, heat flow maps, and world lithologies is generated. Strain rates and deformation styles are based on the global strain rate map of Kreemer et al. (2014). Plate boundary zones are defined and categorized into extensional, transtensional, strike-slip, transpressional and compressional settings. Deformation styles associated with these categories are represented between values 1 and -1 respectively. Furthermore, numerical values of the strain rate are divided into three classes: high, low, and negligible deformation rates. Stress regimes independently derived from the world stress map dataset (Heidbach et al., 2018) are generally consistent with deformation styles in the high and low deformation rate zone and provide additional constraints in the plate interiors. Our results indicate that high strain rates are not a necessary condition to leakages. CO2 leakage is generally concentrated around regions with high volcanic activity, hydrothermal and geothermal area within zones of extensional regimes such as normal and transtensional strike-slip faulting whereas CH4 leakage is more commonly associated with oil and gas seeps, mud volcanoes, and other gas vents such as mofettes within zones of transpressional regimes or reverse faulting. Both CO2 and CH4 leakages can be present in a few sedimentary basins, generally of extensional origin which experienced reactivation of normal faults.

References

1) Heidbach, . Heidbach, O., Rajabi, M., Cui, X., Fuchs, K., Müller, B., Reinecker, J., Reiter, K., Tingay, M., Wenzel, F., Xie, F., Ziegler, M.O., Zoback, M.L., Zoback, M.D., 2018. The World Stress Map database release 2016: crustal stress pattern across scales Tectonophysics, 744 (2018), pp. 484-498, 10.1016/j.tecto.2018.07.007.

2) Kreemer, C., Blewitt, G., Klein, E.C., 2014. A geodetic plate motion and Global Strain Rate Model Geochem. Geophys. Geosyst., 15 (2014), pp. 3849-3889

How to cite: Levendal, T., Henry, P., Wibberley, C., Gassier, G., and Boisson, M.: A worldwide catalogue of natural CO2 and CH4 surface leakages: An approach on undesirable geological contexts for CO2 storage, taking into account strain rate, stress, and tectonic regime., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6151, https://doi.org/10.5194/egusphere-egu22-6151, 2022.

EGU22-6162 | Presentations | ERE3.1

The Geochemistry of Pure Minerals with Pure Hydrogen in Aqueous Solutions 

Aliakbar Hassanpouryouzband, Eike Marie Thaysen, Mark Wilkinson, and Katriona Edlmann

In alignment with the Paris Agreement, more than 120 countries have now committed to reaching net zero by mid-century. Among the future energy storage technologies required for limiting global warming to well below 2 °C, geological storage of hydrogen is considered as a strong candidate to support increased renewable electrification. It is therefore crucial to understand the impact of injected hydrogen on geochemical equilibrium in these geological storage settings. Here, we investigate the potential for hydrogen reactions with different pure minerals using our custom high pressure/temperature batch reactors. Minerals examined include Gypsum, Calcite, Dolomite, and two types of Pyrite. We conducted the experiments at high pressure and temperature conditions with simulated reservoir brine, representing real geological conditions. Moreover, we conducted control experiments with inert nitrogen to ensure confidence that any identified geochemical reactions are induced by hydrogen, rather than elevated, temperature, pressure or brine chemistry. Our results suggest that abiotic geochemical reactions are not likely to result in hydrogen loss within the time scales of geological hydrogen storage.

How to cite: Hassanpouryouzband, A., Thaysen, E. M., Wilkinson, M., and Edlmann, K.: The Geochemistry of Pure Minerals with Pure Hydrogen in Aqueous Solutions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6162, https://doi.org/10.5194/egusphere-egu22-6162, 2022.

EGU22-6644 | Presentations | ERE3.1

Numerical Assessments of Repurposing a Natural Gas Cavern for Hydrogen Storage 

Richard Wallace and Zuansi Cai

Utility-scale hydrogen storage will be essential in the UK for meeting carbon emission goals[1]. It is estimated that approximately 150TWh of seasonal energy storage is necessary to negate seasonal variations in natural gas production[2]. This capacity can be easily met through compression and storage of hydrogen within depleted gas reservoirs and deep saline aquifers[2]. However, there are several limitations to porous storage, such as the mixed composition of the produced fluid, higher cushion gas requirements, slower release kinetics and longer storage cycles.

Due to the storage dynamics of salt caverns, single gasses can be stored with minimal mixing, allowing for reduced post-storage processing and higher deliverability. This provides caverns with an essential role in both seasonal and daily load management as well as providing a source of energy for high purity hydrogen applications (i.e. transport and fuel cells). The national grid estimates 51TWh of cavern storage will be necessary by 2050[3].

Although new caverns will be necessary, there are several benefits to repurposing current facilities:

  • Above ground infrastructure is already available
  • Freshwater savings, approximately 7-8m3 per m3 cavern size[4]
  • Shorter lead times on storage development
  • The reduced expense for geological exploration

Current methods for repurposing suggest the reflooding of the cavern with high salinity brine to replace the gas within, brine production and hydrogen injection then follows this; a process estimated to take 3-7 years. Although less time than for new developments, the risk of unacceptable leakage and the still considerable cost acts as barriers to its implementation.

Our research aims to provide the first investigation into repurposing through gas replacement, determining the number of cycles necessary before an acceptable purity can be attained. This will be simulated with GPSFLOW (General Purpose Subsurface Flow simulator), a software capable of modelling multiphase-multicomponent storage within salt caverns, deep saline aquifers and depleted gas fields[5]. The geological model utilised will be an idealised version of the Stublach cavern in Cheshire, England.

Two approaches are proposed, the first being an injection cycle of high purity hydrogen and the monitoring of hydrogen quality in the produced fluid as the number of cycles increases. Alternatively, the use of CO2 as means to replace the CH4 and then the subsequent hydrogen injection cycles will be simulated. The significance of this work is to provide an initial insight into repurposing through gas replacement which, if functional, may provide a reduced transitionary period and considerable resource savings.

References

  • 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.
  • Scafidi, J., M. Wilkinson, S.M.V. Gilfillan, N. Heinemann, and R.S. Haszeldine, A quantitative assessment of the hydrogen storage capacity of the UK continental shelf. International Journal of Hydrogen Energy, 2021. 46(12): p. 8629-8639.
  • National Grid, Future Energy Scenarios. 2021.
  • Warren, J.K., Solution Mining and Salt Cavern Usage, in Evaporites: A Geological Compendium, J.K. Warren, Editor. 2016, Springer International Publishing: Cham. p. 1303-1374.
  • Cai, Z., K. Zhang, and C. Guo, Development of a Novel Simulator for Modelling Underground Hydrogen and Gas Mixture Storage. International Journal of Hydrogen Energy, 2021.

How to cite: Wallace, R. and Cai, Z.: Numerical Assessments of Repurposing a Natural Gas Cavern for Hydrogen Storage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6644, https://doi.org/10.5194/egusphere-egu22-6644, 2022.

EGU22-8250 | Presentations | ERE3.1

Broadband seismic instrumentation for monitoring CCS sites 

Marcella Cilia, Will Reis, Neil Watkiss, Sally Mohr, Rui Barbara, and Phil Hill

Carbon Capture and Storage (CCS) sites require microseismic monitoring before, during and after operations to ensure safety of operational personnel and the wider public.

The high dynamic range and low self-noise of broadband seismometers allows for the detection of low magnitude microseismic events which fall below the threshold of less sensitive geophones. Higher long-period sensitivity also allows the full source spectra of earthquakes to be accurately measured, resulting in more accurate magnitude estimations which improve the integrity of any microseismic monitoring system.

Borehole instruments such as the Güralp Radian are a natural fit for detecting low magnitude microseismic events. Optional high gain at the higher frequencies makes the Radian extremely suitable for monitoring low-magnitude induced events while retaining long-period sensitivity for larger ruptures. The slim form factor and omni-angle operation allows the instrument to easily be lowered into decommissioned wells with little information about the orientation at depth.

The Radian is currently being utilised by the British Geological Survey as part of the UK GeoEnergy Test Bed (GTB) to monitor and improve understanding of fluid flow through natural subsurface pathways. A string of 6 interconnected Radians provides vertical profiling around the injection site with a maximum of 8 units able to join in a single string. The Radian will detect and monitor small changes in the subsurface at the GTB as part of the suite of monitoring technologies deployed onsite. 

In addition to onshore networks, offshore depleted gas fields are becoming increasingly scrutinised for potential to store CO2. The advent of Güralp omnidirectional sensor technology combined with acoustic near-real-time data transmission means the Aquarius OBS provides a cost-effective solution for monitoring offshore CCS sites, with infrequent and rapid battery recharging and acoustic data extraction while the unit is still on the seafloor.

How to cite: Cilia, M., Reis, W., Watkiss, N., Mohr, S., Barbara, R., and Hill, P.: Broadband seismic instrumentation for monitoring CCS sites, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8250, https://doi.org/10.5194/egusphere-egu22-8250, 2022.

EGU22-9102 | Presentations | ERE3.1

Subsurface characterization of geological CO2 storage sites from gravity, passive seismic and seismic data; a case study from the southern Ebro basin (Spain) 

Conxi Ayala, Beatriz Benjumea, José Francisco Mediato, Félix Rubio, Carmen Rey-Moral, Jesús García-Crespo, Pilar Clariana, Ruth Soto, Emilio L. Pueyo, and Paula Fernández-Canteli Álvarez

The geological storage of CO2 requires the search and characterization of a suitable porous formation and caprock to ensure a favorable and safe trap. One of the first steps of this search consists of performing a detailed definition of its geometry at depth.  The structure of Lopín (southern Ebro basin, Spain) was identified as a potential structure valid for CO2 storage in the frame of the ALGECO2 project (Selection and characterization plan of favorable areas and structures for Geological CO2 Storage in Spain, 2009-2014) led by IGME. A preliminary characterization carried out during these years showed positive conditions for the storage of this gas. However, the poor quality of the available reflection seismic data precluded accurate enough conclusions to select this location as geological storage site. The biggest uncertainty was the closure of the structure in its SE margin and further exploration was ruled out at that time. Within the PilotStrategy project (2021-2026), funded by UE on the frame of the H2020, the structure of Lopin is proposed for further studies and a gravimetric and passive seismic surveys have been carried out for in order to resolve this question.  The Lopín structure constitutes an antiform affecting Paleozoic and Mesozoic sequences overlain by subhorizontal Neogene deposits located in the southern Ebro basin. It is defined by NW-SE and NNW-SSE oriented faults several tenths of kilometres long which are subparallel to the orientation of the dominant structures of the Iberian Chain, located to the South of the study area. At the Lopín structure, the target reservoir and seal formations consist of the Lower and Upper Triassic rocks, respectively.  

 The aim of the new geophysical surveys is to improve the geometric characterization at depth of the Lopín structure.  The gravimetric surveys have coverage of two stations for km2 in the structure area. In addition, 7 profiles have been built up in the uncertainty area with a coverage of a station every 250 m. The models have been constrained by the newly acquired passive seismic data and the reinterpretation of some of the vintage seismic reflection profiles. The preliminary results of the joint modelling improve the geometrical characterization of the Lopín structure at depth in order to define its suitability as geological CO2 reservoir site. 

How to cite: Ayala, C., Benjumea, B., Mediato, J. F., Rubio, F., Rey-Moral, C., García-Crespo, J., Clariana, P., Soto, R., Pueyo, E. L., and Fernández-Canteli Álvarez, P.: Subsurface characterization of geological CO2 storage sites from gravity, passive seismic and seismic data; a case study from the southern Ebro basin (Spain), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9102, https://doi.org/10.5194/egusphere-egu22-9102, 2022.

EGU22-9795 | Presentations | ERE3.1

Climate-Benign Direct Air CO2 Capture, Utilization, and Storage (DACCUS) 

Martina Leveni and Jeffrey M. Bielicki

Transitioning towards a carbon managed energy infrastructure is essential to mitigate climate change. Negative emission technologies, such as direct air CO2 capture (DACC), together with renewable energies will likely to be necessary components in the effort to slow, stop, reverse the flow of carbon dioxide (CO2) to the atmosphere. The DACC process requires heat and electricity to capture CO2 from the ambient air, the sources of which may not be climate-benign. We present an approach that combines DACC, long-term CO2 storage, and geothermal energy production: a climate-benign direct air capture, carbon utilization, and storage (DACCUS). The CO2 captured from the ambient air, is geologically stored in sedimentary basins, and circulated to the surface in a closed system to extract the available geothermal heat.  The produced heat can be used directly or converted to electricity by a power plant and used in the DACC process.  We investigate the performance of DACCUS systems, including sensitivity analyses of key parameters, such as the sorbent regeneration temperature (80-120°C), the outlet temperature the CO2 stream from the DACC (70-22°C), and reservoir permeability (1x10-15-1x10-11 m2), among others.  The results indicate that DACCUS has a promising potential for using the CO2 from DACC to produce process energy requirements. For example, with a regeneration temperature of 100°C and a DACC outlet temperature of 70°C, reservoirs with depths equal or above 3.5 km, and geothermal temperature gradients equal or above 35°C/km, can provide sufficient wellhead temperatures. In addition, the maximum DACC capacity for those temperatures increases considerably for reservoir permeability up to 5x10-14 m2, and can provide the make-up CO2 for that which migrates outside of the region in the aquifer where CO2 is circulated between the subsurface and the surface. Costs estimates for DACC are $500–600/tCO2. While also the cost of the integrated system is important, the integration with CO2-geothermal production could yield substantial savings for DACC ($0.64M - $30.6M annually of avoided electricity costs). 

 

How to cite: Leveni, M. and Bielicki, J. M.: Climate-Benign Direct Air CO2 Capture, Utilization, and Storage (DACCUS), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9795, https://doi.org/10.5194/egusphere-egu22-9795, 2022.

EGU22-12259 | Presentations | ERE3.1

Carbon sequestration potential of the Lorestan area, Iran 

Pegah Soleimani Dinani, Giampaolo Proietti, Valentina Romano, Seyed Ali Moallemi, Fabio Trippetta, and Sabina Bigi

Current climate policies are not being implemented at a sufficient rate to mitigate global warming and as a result evaluation for the potentiality of more sites for a purpose of Greenhouse gas storage, in particular Carbon Dioxide, is on the rise. Iran is a country that ranks 7th in the emission of Carbon Dioxide in 2020 by 0.72 GT and is the 4th largest and 2nd largest reserve holder of oil and natural gas, respectively. For this reason and due to its potential, could play an important role in the context of CCS. Since the Zagros area is one of the most important foreland basins in the world hosting oil and gas fields, we addressed this zone for a purpose of Carbon sequestration. The existence of potential reservoirs in the Lorestan zone and vicinity to the source of emissions made us more decisive to focus on this area.

In this work, we evaluate the potentiality of four anticlines by using the data of abandoned oil and gas wells. Through the analysis of seismic lines and well data provided by NIOC (National Iranian Oil Company), we confirmed the geometrical potential and petrophysical characteristics of these structures for a purpose of carbon sequestration.

Required geological storage criteria such as geometry, pressure, depth, and petrophysical parameters are applied with the aim of screening the exploitable structures in the mentioned zone. In the final step, geological models of the structures have been built to represent petrophysical properties three-dimensionally, in order to evaluate the reservoir volumes and more importantly to estimate the storage capacity of this area.

How to cite: Soleimani Dinani, P., Proietti, G., Romano, V., Moallemi, S. A., Trippetta, F., and Bigi, S.: Carbon sequestration potential of the Lorestan area, Iran, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12259, https://doi.org/10.5194/egusphere-egu22-12259, 2022.

EGU22-12726 | Presentations | ERE3.1

Microbiological impacts of hydrogen injection into underground storages 

Martin Wagner, Guido Nowack, Theresa Pretzien, and Lydia Krasper

As the integration of wind and solar energy increases, so does the need for large-volume and efficient storage to balance fluctuations in power generation and demand.

In order to meet this demand, the proportional injection of renewable hydrogen into the natural gas grid or directly into underground storage facilities (UGS) is already being investigated in several pilot studies. Large-scale hydrogen storage, especially in salt caverns, is considered to have great potential in the context of carbon-free energy supply. From microbiological studies of numerous cavern and porous storage facilities, it is known that most UGS are already colonized with microorganisms that can use hydrogen as their sole energy source.

The results of several research projects and analyses of numerous underground storage facilities with regard to the stimulation potential of existing microorganisms give clear indications of associated risks. The results of these studies also contradict the widespread assumption that saturated brine in caverns generally provides sufficient protection against microbial colonization.

Long-term analyses with over 70 active cultures enriched from different underground storage and reservoir samples and tests with original formation waters show significant hydrogen consumption even in saturated brine with simultaneous H2S formation by SRB. Carbonates from the minerals of the rock matrix can be used as a necessary carbon source. For a practical simulation of hydrogen storage, in addition to microcosm experiments, numerous high-pressure tests were carried out at storage-relevant conditions over several months with original brine and core samples from different storage types. In some cases, considerable hydrogen conversions and sulfide formation rates were found.

In addition to the influence of hydrogen injection on microorganisms in storage facilities, two projects are also investigating dedicated biological methanogenesis in 11 porous UGS. Presence of microorganisms was detected in almost all reservoirs. Active methanogenic archaea were enriched from three facilities and their ability for methanogenesis was studied and confirmed under different conditions (pressure, temperature, salinity). However, microorganisms with competing metabolic pathways were also detected (e.g. sulfate reducers and acetogens).

The presentation summarizes the results of microbiological investigations on storage and reservoir samples from more than 10 years and gives an overview of relevant microbial processes and their potential impact on technical operations.

How to cite: Wagner, M., Nowack, G., Pretzien, T., and Krasper, L.: Microbiological impacts of hydrogen injection into underground storages, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12726, https://doi.org/10.5194/egusphere-egu22-12726, 2022.

EGU22-1012 | Presentations | ERE3.3

Pore Super Segmentation in Opalinus Clay on Artificially Enhanced SEM Images with Voting Classification 

Marco Brysch, Ben Laurich, Christoph Schettler, and Monika Sester

A material's porosity controls all of its physical properties. Hence, many studies have dealt with its exact determination. In researching potential host rocks for radioactive waste disposal, there is a particular interest in pore distribution and connectivity as this defines the rock's permeability and rheological behavior, e.g. in [Houben et al., 2013], [Hemes et al., 2011], [Klaver et al., 2012], and [Keller, 2021]. All these studies made use of specialized scanning electron microscopy (SEM). This analysis allows the evaluation of pores by size, location, orientation, and frequency by using a binary segmentation mask. The preparation of these masks is associated with some difficulties caused by the interpretation margins, non-uniform procedures, and, especially, by the resolution limit of the SEM. In addition, the overlap of gray values of grain and pores renders conventional methods such as pixel-thresholding unfeasible.

We present a method that deals with this problem in two stages. The first stage consists of an up-sampling technique of the SEM images. Here, the resolution of the images is artificially enhanced. In the second stage, this up-sampling is combined with an algorithm that computes a probability field using multiple learning classifiers (MLC). First, we trained and implemented an enhanced super-resolution generative adversarial network (ESRGAN) [Wang et al., 2018] for upsampling SEM images. The enhanced images show a much finer detail of pore edges, making even the smallest pores more apparent and detectable. In the second stage, nine different MLC's have been trained and examined for their segmentation results. Here, the characteristic segmentation properties of the trained MLC's are particularly noticeable. Their differences show that no single MLC alone can provide sufficient segmentation quality compared to manual interpretation. Hence, a voting classifier combines the individual MLC-masks into a probability field. This combination allows the derivation of confidence levels that reduce spurious pore segmentation and capture pore edges more organically and uniformly. 

Finally, we have combined the voting classifier and the super-resolution to the so-called Super-Segmentation (SSM). The segmentation of the pores is now performed on the artificially enhanced SEM image. Eventually, the final binary segmentation mask is down-sampled to the resolution of the input image. Compared to other segmentation methods, SSM shows a clearer detection of the pore edges with enhanced quality even for the smallest pores. In a test case on Opalinus clay, we were able to detect pores that were undetected or insufficiently segmented. We discuss the result and ongoing work to improve the reliability of MLCs with ESRGAN images with the goal to lower the truncation limit [Bonnet et al., 2001].

How to cite: Brysch, M., Laurich, B., Schettler, C., and Sester, M.: Pore Super Segmentation in Opalinus Clay on Artificially Enhanced SEM Images with Voting Classification, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1012, https://doi.org/10.5194/egusphere-egu22-1012, 2022.

EGU22-1728 | Presentations | ERE3.3

Numerical assessment of the barrier integrity from a generic nuclear waste repository in crystalline rock 

Carlos Guevara Morel, Jobst Maßmann, and Jan Thiedau

Safe deep geological disposal of heat generating nuclear waste requires a detailed assessment of the geotechnical integrity of potential host rocks. In Germany, several repository systems are under discussion, in which clay stone, salt or crystalline rock could serve as host rock. This contribution proposes a modelling concept for the numerical analysis of the thermal, hydraulic and mechanical (THM) coupled processes used for the barrier integrity assessment of a nuclear waste repository in crystalline rock. In particular, focusing on repository systems where the Containment Providing Rock Zone (CRZ) represents the essential barrier. This implies that understanding the potential changes in the geological barrier caused by the disposal of the waste is fundamental in order to avoid the creation of preferential flow paths for the disposed waste into the biosphere. Furthermore, in Germany, the host rocks must comply with the safety requirements stipulated by the German Federal Ministry for the Environment, Nature Conservation, Nuclear Safety and Consumer Protection in 2020.

Crystalline rock, in contrast to clay stone and salt rock, is usually characterised by fractures and other types of discontinuities. Therefore, it cannot be assumed that a single sufficiently large unfractured area can be found in which all of the nuclear waste could be emplaced. In consequence, multiple smaller CRZs, each providing undisturbed rock, have to be defined. Moreover, the fracture network is expected to influence the hydraulic behaviour 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.

The proposed modelling concept is applied to a generic geological model reflecting a realistic geological situation. A Discrete Fracture Network (DFN) model is used to determine the hydraulic properties that are then upscaled and mapped into a continuum Finite Element (FE) model. The preliminary numerical results (e.g. stresses and pore fluid pressures) from the parameterized continuum model are used to exemplary assess the barrier integrity using criteria which take into account the dilatancy strength and fluid pressure.

How to cite: Guevara Morel, C., Maßmann, J., and Thiedau, J.: Numerical assessment of the barrier integrity from a generic nuclear waste repository in crystalline rock, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1728, https://doi.org/10.5194/egusphere-egu22-1728, 2022.

EGU22-1925 | Presentations | ERE3.3

Different strategies in attempting nuclear waste disposal – A comparative study based on four countries 

Jayjayanti Basumallik, Wolfram Rühaak, and Miranda Schreurs

Across the world, about thirty countries are generating power from nuclear energy, but adopting different strategies to deal with high-level radioactive waste (HLW) produced during the process. A brief comparative analysis of four countries, namely, Finland, Germany, China, and India, is conducted in order to understand the key geopolitical, technical, and social factors that drive these different strategies. There are significant differences in their preparedness related to planning and implementing a final disposal facility for the HLW in deep geological repositories. The research explores the extent of public awareness and acceptance of the nuclear waste management strategies in these four countries. Of special interest is the scope of public participation in the decision-making process related to repository site-selection, and the safety assurances of the proposed HLW disposal techniques. The analysis finally delves into the subject of protracted timelines of the ongoing HLW management projects and the associated challenges.

How to cite: Basumallik, J., Rühaak, W., and Schreurs, M.: Different strategies in attempting nuclear waste disposal – A comparative study based on four countries, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1925, https://doi.org/10.5194/egusphere-egu22-1925, 2022.

EGU22-1936 | Presentations | ERE3.3

Generalizing the simulation of temperature distributions in a deep geological nuclear waste repository 

Wolfram Rühaak, Michael Werres, Thomas Lohser, and Klaus-Jürgen Röhlig

Based on representative data for the geologic situation in Germany the temperature evolution around a nuclear waste canister was modeled in detail. The surrounding rock data for this specific case study represent crystalline rock properties. Heat production was estimated based on the German radioactive waste inventory. Using FEFLOW a high-resolution 3D numerical thermal model of one single canister was set up. The respective canister design was selected according to the Scandinavian KBS-3V concept. Based on this model representative temperature data in space and time were computed. By using these detailed reference results a strongly simplified model with just single node heat sources representing a repository section with 15 emplaced canisters was calibrated.

Tests showed that this approach allows to compute large arrays of canisters with a good quality.

Results of the study will be shown and further potential improvements are discussed.

How to cite: Rühaak, W., Werres, M., Lohser, T., and Röhlig, K.-J.: Generalizing the simulation of temperature distributions in a deep geological nuclear waste repository, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1936, https://doi.org/10.5194/egusphere-egu22-1936, 2022.

EGU22-2019 | Presentations | ERE3.3

Comparing uncertainty quantification methods based on distributions or statistical moments in thermal design calculations 

Merle Bjorge, Aqeel Afzal Chaudhry, Wolfram Rühaak, and Thomas Nagel

The presented work investigates aspects of uncertainty quantification in thermal design calculations of deep geological repositories for nuclear waste. The expected evolution of thermal conditions is a key element in the design process of the repository layout. Due to the radioactive decay and the associated emission of heat, temperatures increase in the repository system, potentially affecting processes relevant to the repository negatively. In order to quantify the temperature evolution and assess its effects on the various barriers, such as the host rock, models are set up and thermal calculations are conducted. Often specific distributions are assigned to model parameters, which are not known precisely.

To achieve a robust understanding and design despite this limited knowledge, it is necessary to assess the uncertainties associated with both parameters and models as part of these calculations. However, an uncertainty quantification, which includes calculations based on full distributions is expensive. To compare different uncertainty quantification methods applied to thermal design calculations, a benchmark is created. This benchmark is based on an analytical solution for a 1-D, thermal heat conduction problem using Python. Results of uncertainty quantification calculations based on full distributions, utilizing statistical moments or employing series expansion such as the first-order-second-moment method are compared.

This benchmark can help assess methods of uncertainty quantification in context of thermal design calculations.

How to cite: Bjorge, M., Chaudhry, A. A., Rühaak, W., and Nagel, T.: Comparing uncertainty quantification methods based on distributions or statistical moments in thermal design calculations, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2019, https://doi.org/10.5194/egusphere-egu22-2019, 2022.

EGU22-2343 | Presentations | ERE3.3

The influence of sedimentary heterogeneity on the diffusion of radionuclides in the sandy facies of Opalinus Clay at the geological scale 

Chaofan Chen, Tao Yuan, Renchao Lu, Cornelius Fischer, Vanessa Montoya, Olaf Kolditz, and Haibing Shao

Radionuclide migration in clay-rich formations is dominated by molecular diffusion due to the low permeability of the claystone. Accurate estimation of radionuclide migration in host rock using numerical tools plays a key role in the safety assessment of disposal concepts for nuclear waste. In the sandy facies of the Opalinus Clay (SF-OPA), the spatial variabilities of the pore network and compositional heterogeneities at the pore scale (nm to µm) cause heterogeneous diffusion at the core scale (cm to dm). Such heterogeneous diffusion patterns affect the migration of radionuclides in the various sedimentary layers even above the core scale (~m). Small-scale heterogeneities of diffusive transport could play an important role in upscaling to larger length scales of SF-OPA, particularly because of differences in sedimentary and diagenetic facies. Therefore, a meaningful estimation of radionuclide migration in the host rock above the core scale requires a comprehensive study of the influence of sedimentary layers on the heterogeneous diffusion.

In this work, we study the heterogeneous diffusion of radionuclides based on a two-dimensional (2D) structural model from the geological data of SF-OPA in the Mont Terri rock laboratory at the m-scale. As key parameters for the diffusive transport calculation, the effective diffusion coefficients in different sedimentary layers are quantified based on the developed upscaling workflow from pore- to core-scale simulation combined with the multi-scale digital rock models [1]. The heterogeneous effective diffusivities are then implemented into the large-scale structural model for diffusive transport simulation using the FEM-based OpenGeoSys-6 simulator. Results show that the various heterogeneous effective diffusivities under different mesh resolution (length scales) in the large-scale simulations strongly affect the evolution of radionuclides concentration in SF-OPA, especially in the vicinity of the canister. The sensitivity analysis focuses on the effects of length, bedding angle and thickness of the sedimentary layer on the spatio-temporal evolution of radionuclide concentrations. The numerical results provide insight into the heterogeneous diffusion of radionuclides, contributing to enhanced long-term predictability of radionuclide migration in the host rock of the deep geological repository.

[1] Yuan, Tao, and Cornelius Fischer. "Effective Diffusivity Prediction of Radionuclides in Clay Formations Using an Integrated Upscaling Workflow." Transport in Porous Media 138.2 (2021): 245-264.

How to cite: Chen, C., Yuan, T., Lu, R., Fischer, C., Montoya, V., Kolditz, O., and Shao, H.: The influence of sedimentary heterogeneity on the diffusion of radionuclides in the sandy facies of Opalinus Clay at the geological scale, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2343, https://doi.org/10.5194/egusphere-egu22-2343, 2022.

A potentially novel disposal pathway for small volumes of radioactive waste originating from reprocessing of spent nuclear fuels is in deep boreholes (DBs). The waste packages are stacked in a disposal zone at depths that would be considerably deeper than the typical depth of conventional mined repositories. DB disposal still requires considerable research and development to bring the science and technology to a similar level as the conventional disposal geological disposal facilities [1]. The half-life of several of the radionuclides in reprocessed spent nuclear fuel is on the order of 105 - 109 years. Such wastes generate heat for hundreds of years. Containers should have a lifetime long enough to survive at least the heat-production period [2]. In the geosphere surrounding the borehole, nonlinear interactions between transport phenomena and long time scales necessitate modelling as the most realistic tool to assess the risks. Coupling the flow, natural hydrostatic and temperature profiles with heat and solute mass transport is not computationally trivial.      

We study a complex domain including geological faults, stratified lithology, and an engineered DB with its surrounding damaged zone and backfilling materials. The system has an assumed groundwater flow above the low-permeable host rock, a diagonally-oriented fault and a cylindrical representation of the borehole. Such objects require a domain which is neither axisymmetric nor 2D Cartesian. A structured mesh to represent such a domain in 3D, with the required fine-scale near-field resolutions essential for simulation of the slow advective and diffusive transport, significantly increases the computational cost. For the first time a fully-3D unstructured Voronoi mesh was developed to represent such a layout with various petrophysical features and engineering objects to conduct a preliminary safety assessment.  

We present a coupled heat-solute mass transport modelling framework, subjected to depth-dependent temperature, pressure, and viscosity profiles - assuming an instantaneous release of radionuclides, as the most conservative “what if” scenario. Several scenarios of heat-generation were investigated to test if the additional heat produced by the waste affects radionuclide migration, e.g., by generating convection-driven transport.  The state-of-the-art TOUGHREACT-OMP was run on the CSIRO supercomputer to model the 3D Cartesian domain 3 km in length, 400 m in width and 3 km in depth. We present our meshing approach through linking voro2mesh, T2Viewer and in-house codes to develop a fully-3D unstructured mesh, compatible with the core model [3].

We tested the effect of lithology on the diffusion process (effective diffusion) for quantifying the radionuclide concentrations and annual dose rates for a potential human receptor (e.g., through a well).  We show the dose rate is highly sensitive to the diffusion parameter and fault configuration, while the effect of heat generation on convection-driven transport is of lesser importance.

 

1-Mallants, D., et al., The State of the Science and Technology in Deep Borehole Disposal of Nuclear Waste. Energies, 2020. 13(4).

2-IAEA, Geological disposal facilities for radioactive waste. 2011, International Atomic Energy Agency: Viena.

3-Bonduà, S. and V. Bortolotti, TOUGH2Viewer 2.0: A multiplatform tool for fully 3D Voronoi TOUGH grids. SoftwareX, 2020. 12: p. 100596.

How to cite: Sookhak Lari, K. and Mallants, D.: Coupled heat-mass transport modelling for safety assessment of deep borehole disposal of long-lived radioactive waste in a complex 3D petrophysical condition, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3295, https://doi.org/10.5194/egusphere-egu22-3295, 2022.

Any safety assessment of radioactive waste disposal sites is done based on the simulation of migration lengths of radionuclides through the host formation. This is done by the application of transport parameters obtained from experiments with homogeneous, e.g. geochemically and mineralogically constant, conditions. However, such an assumption of homogeneity is no longer applicable on the host rock scale (>200 m). Consequently, experimentally determined transport parameters might no longer represent the host rock on larger scales.

Uranium, as main component of spent fuel, is used here as an example to evaluate the impact of heterogeneous systems on the total migration lengths compared to homogeneous ones. For this, the hydrogeological system of the Swiss Opalinus Clay, a potential host rock, is modelled in one-dimensional diffusion simulations with PHREEQC. Since sorption and hence migration of uranium is primarily governed by pCO2 > Ca2+ > pH > pe > clay mineral quantity [1], the focus is on the simulation of the geochemically heterogeneity, and thus on the hydrogeological system. Sorption is quantified with mechanistic surface complexation models and cation exchange. At Mont Terri, geochemical gradients established towards the embedding aquifers due to diffusive exchange over millions of years as a consequence of the Jura folding and associated erosion history [2].

First, measured pore water profiles were confirmed by the simulations. They served as starting profiles for the subsequent uranium migration that was quantified in a second step. By comparing migration lengths after a simulation time of one million years with results of homogeneous simulations, it has been shown that uranium migration is enhanced by up to several tens of meters depending on the pCO2. Consequently, the entire hydrogeological system needs to be taken into account and the governing parameters can be prioritized as follows: pCO2 > hydrogeology > mineralogy.

 

[1] Hennig T., Stockmann M. and Kühn M. (2020): Simulation of diffusive uranium transport and sorption processes in the Opalinus Clay. Applied Geochemistry, 123. DOI:10.1016/j.apgeochem.2020.104777.

[2] Mazurek M., Alt-Epping P., Bath A., Gimmi T., Waber H. N., Buschaert S., De Cannière P., De Craen M., Gautschi A., Savoye S., Vinsot A., Wemaere I. and Wouters L. (2011): Natural tracer profiles across argillaceous formations. Applied Geochemistry 26 (7), 1035–1064.DOI:10.1016/j.apgeochem.2011.03.124

 

How to cite: Hennig, T. and Kühn, M.: Migration lengths of uranium in the Opalinus Clay are determined by the pore water geochemistry and hydrogeological setting, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4115, https://doi.org/10.5194/egusphere-egu22-4115, 2022.

EGU22-5660 | Presentations | ERE3.3

Challenges in modelling radionuclide transport in the German nuclear waste repository search 

Christoph Behrens, Elco Luijendijk, Phillip Kreye, Florian Panitz, Merle Bjorge, Marlene Gelleszun, Alexander Renz, Shorash Miro, and Wolfram Rühaak

The current phase of the site selection procedure for a high-level nuclear waste repository in Germany includes representative preliminary safety assessments of potential suitable areas that cover approximately half of the territory of Germany. These safety assessments rely in part on numerical models of radionuclide transport. The modelling of radionuclide transport faces several challenges: 1) Estimation of radionuclide transport for a large set of potentially suitable areas with different hydrogeological settings and 2) scarcity of site-specific hydrogeological data for the parameters that govern radionuclide transport. To overcome these challenges we discuss potential workflows that combine the analysis of hydrogeological data and numerical models of radionuclide transport. We introduce a suite of numerical model codes that combines computationally efficient one-dimensional codes with more computationally demanding 2D and 3D codes. The 2D and 3D codes will be employed to simulate regional groundwater flow fields. These are subsequently combined with large sets of 1D model runs to quantify the effects of parameter variation and future geological developments on radionuclide transport. We discuss methods to combine site-specific data with global data to constrain the bandwidths of hydrogeological parameters and the range of radionuclide transport. Our contribution aims for an open discussion of model strategy and exchange with the scientific community.

How to cite: Behrens, C., Luijendijk, E., Kreye, P., Panitz, F., Bjorge, M., Gelleszun, M., Renz, A., Miro, S., and Rühaak, W.: Challenges in modelling radionuclide transport in the German nuclear waste repository search, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5660, https://doi.org/10.5194/egusphere-egu22-5660, 2022.

According to the 'Repository Site Selection Act' (a governmental law, called in German the Standortauswahlgesetz – StandAG), the German National Waste Management Organisation (BGE) has been assigned to be the implementer for the German site selection procedure. As such, the BGE is responsible to identify a site for a high-level radioactive waste repository in a deep geological formation with best possible safety conditions for a period of at least one million years.

The German site selection procedure is an iterative process and consists of three phases with an increasing level of detail while the survey area becomes smaller during the process. An immanent part is the repetitive application of exclusion criteria, minimum requirements and the geoscientific weighting criteria (Sections 22 – 24 StandAG) during each phase. Starting with an empty, so-called white map of Germany, the BGE completed Step 1 of Phase I in September 2020 with the submission of the sub-areas interim report. Therein, 90 individual sub-areas were identified, where a favourable geological condition for the safe disposal of radioactive waste is possible. According to the site selection act the host rocks claystone, rock salt and crystalline rock are considered. In the current Step 2 of Phase I, both the representative preliminary safety assessments (Section 27 StandAG) and the repeated application of the above-mentioned criteria and requirements as well as the planning-scientific weighing criteria according to Section 25 StandAG are applied to localise siting regions within the 90 sub-areas.

Surface exploration, including geophysical surveys, geological mapping, hydrogeological investigation and drilling of boreholes, will take place within these siting regions in the scope of Phase II. Currently, exploration targets are defined, which arise from the safety assessments and the mentioned requirements and criteria. Existing data from former exploration activities such as seismic and borehole data, but also other geoscientific data are considered. These data have to be selected, procured and possibly reprocessed with a new focus on a high-level radioactive waste repository. After comparison of the principal demand of information as mentioned above and the already existing data, the exploration demand for every siting region will be derived by a thorough gap analysis. Based on that, the surface exploration programs will be developed.

Phase III is characterized by higher-grade, more detailed subsurface exploration activities, which again provide the base for preliminary safety assessments. Phase III ends with a proposal for a site for a high-level radioactive waste repository.

How to cite: Bairlein, K., Perner, M., Meier, F., and Schamp, J.: The site selection procedure for a high-level radioactive waste repository in Germany: an overview of the process and upcoming exploration activities, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7801, https://doi.org/10.5194/egusphere-egu22-7801, 2022.

EGU22-8693 | Presentations | ERE3.3

On the role of crustal deflection in the hydraulic-mechanical simulation of sedimentary basins during glacial cycles 

Christian Silbermann, Dominik Kern, Rebekka Steffen, Holger Steffen, Victor Bense, and Thomas Nagel

While guidelines for the location and licensing of a deep geological repository (DGR) for high-level radioactive waste depend both on national government policies and international regulations, it is mandatory to select a site where the hydrogeological setting provides sufficiently safe natural conditions for long-term waste isolation from groundwater flow. Therefore, safety assessments of a suitable location of a DGR require the evaluation of future external events and processes that may affect its long-term evolution.
Here, glaciation cycles are of special importance: Ice sheets evoke crustal deflections  (including deformation), and impose pronounced hydraulic heads, both of which change the large-scale hydrogeological conditions. To properly assess the present and future conditions of a DGR site, its evolution in the past should be understood. For this, a sedimentary basin [3] is considered here as a large-scale hydrogeological benchmark. The evolution during one glacial cycle is simulated using the open-source multi-field finite element code OpenGeoSys. The hydraulic-mechanical impact of the glacial loading is taken into account using appropriate time-dependent boundary conditions. For comparison with a previously published study [3], the same (heuristic) displacement field is prescribed and the groundwater evolution is regarded. Then, a more realistic displacement field obtained from large-scale GIA simulations [1,2] is prescribed. Using a one-sided mechanical-hydraulic coupling with a staggered solution scheme it is possible to consider not only the hydraulic head from the glacier and the crustal deflection but also the crustal compression. Especially in regions at the margin of the glacier this is could have an impact on the hydraulic behavior at the depth of a DGR.

References & Funding

This research is funded by the Federal Office for the Safety of Nuclear Waste Management under Grant No. 4719F10402 (AREHS project)

[1] Patrick Wu. “Using commercial finite element packages for the study ofearth deformations, sea levels and the state of stress”. In: Geophysical Journal International 158.2 (2004), pp. 401–408.

[2] G. Spada et al. “A benchmark study for glacial isostatic adjustment codes”. In: Geophysical Journal International 185.1 (2011), pp. 106–132.

[3] V.F. Bense and M.A. Person. “Transient hydrodynamics within intercratonic sedimentary basins during glacial cycles”. In: Journal of Geophysical Research: Earth Surface 113.F4 (2008).

How to cite: Silbermann, C., Kern, D., Steffen, R., Steffen, H., Bense, V., and Nagel, T.: On the role of crustal deflection in the hydraulic-mechanical simulation of sedimentary basins during glacial cycles, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8693, https://doi.org/10.5194/egusphere-egu22-8693, 2022.

EGU22-8733 | Presentations | ERE3.3

Fault reactivation in crystalline rock as consequence of glaciation 

Dominik Kern, Christian B. Silbermann, Fabien Magri, Rebekka Steffen, Holger Steffen, Victor Malkovsky, and Thomas Nagel

One of the most important aspects for Deep Geological Repositories (DGRs) in crystalline rock is the presence and evolution of fractures and faults, since they dominate the subsurface flow regime and thus the possible transport of contaminants. In the considered period of one million years, it is expected that cold and warm period 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). 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 safety assessments for DGRs, we analyze GIA-induced far-field stress and pore pressure changes and their impacts on existing faults.

For that purpose, we use Finite-Element methods (FEM) to simulate the hydromechanical processes around an exemplaric DGR of the Yeniseiskiy Site, Russia, applying boundary conditions derived from established GIA models [1,2]. As result, we obtain the Coulomb failure stress for varying instances of assumed faults.

The INFRA project is funded by the DFG-RFBR program:
DFG funds: NA1528/2-1 and MA4450/5-1
RFBR funds: 20-55-12009, АААА-А20-120012190168-5

References

[1] Patrick Wu. “Using commercial finite element packages for the study of earth deformations, sea levels and the state of stress”. In: Geophysical Journal International 158.2 (2004), pp. 401–408.

[2] G. Spada et al. “A benchmark study for glacial isostatic adjustment codes”. In: Geophysical Journal International 185.1 (2011), pp. 106–132.

How to cite: Kern, D., Silbermann, C. B., Magri, F., Steffen, R., Steffen, H., Malkovsky, V., and Nagel, T.: Fault reactivation in crystalline rock as consequence of glaciation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8733, https://doi.org/10.5194/egusphere-egu22-8733, 2022.

A proposed strategy for the use of natural analogue (NA) studies in Nuclear Waste Services1 (NWS) UK geological disposal facility programme and safety case has been developed based on an extensive review of past and current international practices. In the review, it was found that information on the strategic implementation of NA information is not readily available. This may be partly due to lack of strategic planning for the utilisation of NAs, or simply because waste management organisations do not generally publish internal strategic discussions. Nevertheless, it is seen of importance that the topic is discussed in public to increase the visibility of NA information and its implementation in geological disposal programmes. Another main conclusion concerns the cultural aspects of treatment of NAs in international fora, which seems to set NA information in the category of complementary/alternative evidence rather than equal part of the knowledge base. Often, the emphasis is set on the uncertainties and qualitative nature of NA. However, this ignores the fact that uncertainties are also present in laboratory, URL (underground rock laboratory) and modelling studies: for example, NA uncertainties are related generally to ill-defined boundary conditions, while short term experiments have uncertainties in both spatial and temporal scales. When NAs are used only as “alternative” lines of evidence, there is a risk that the information is devolved from the other evidence and this creates a risk of over or underestimating processes if extrapolated.

The strategy presented highlights the importance of:

  • knowledge management and systematic approaches to the use of data from the broadest range of sources (i.e. laboratory, URL, modelling and NA) possible
  • the continuous review of existing NA information
  • the potential benefits of new NA projects in the future national programme
  • the significance and experience of communication with NA information (at various levels across a broad range of stakeholder groups)

The strategic study also includes an update of RWM’s NA catalogue (Milodowski et al. 2015), a starting point of the NWS’s NA knowledge base. Development of a strategic approach to utilise NA information naturally leads to activities to be undertaken in the immediate future and one of the activities emphasised is the potential use of regional (or self) analogues in support of the site characterisation programme. The emphasis and requirements for NA research will evolve and change as the focus of the geological disposal programme develops naturally as the programme matures so, for example, preliminary discussion on the operational phase is also included. 

References

Milodowski, A.E., Alexander, W.R., West, J.M., Shaw, R.P., McEvoy, F.M., Scheidegger, J.M. & Field, L.P., 2015. A Catalogue of Analogues for Radioactive Waste Management. BRITISH GEOLOGICAL SURVEY COMMISSIONED REPORT CR/15/106. Keyworth, Nottingham British Geological Survey 2015. 1849p.

1 Following a merger with Low Level Waste Repository Limited, Radioactive Waste Management (RWM) is now part of Nuclear Waste Services (NWS)

How to cite: Reijonen, H., Alexander, R., and Norris, S.: Natural Analogues – A proposed strategy for implementation within the Nuclear Waste Services (NWS), UK, programme of geological disposal, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9127, https://doi.org/10.5194/egusphere-egu22-9127, 2022.

Bentonite is a versatile material that is, among other things, envisaged for designs for radioactive waste repositories to protect the waste canisters against groundwater. The thermo-hydraulic-mechanical (THM) coupled process of bentonite saturation is commonly based on two-phase flow. As an alternative to the formulations in THM-models, a thermo-hydraulic coupled saturation model for confined conditions (as expected in a repository) has been developed and realised for 1D-problems in the FORTRAN-code VIPER. In order to enhance the inherent limited range of possible applications of this code, the underlying partial differential equations have been transferred to COMSOL Multiphysics®. This has been done for the most simple, isothermal form at first, and subsequently for the non-isothermal formulation by coupling the hydraulics to the heat transfer interface of COMSOL.

The model concept for the hydraulics, qualified for a number of different problems using the VIPER code, is comparatively simple. Vapour diffusion in the pore space is coupled to diffusive water migration in the interlamellar space by instantaneous hydration. This results in a double-continuum model that calculates re-saturation rather efficiently for cases where the bentonite is subject to confined conditions and only little internal swelling occurs.

At first, a COMSOL-model has been developed that matches an isothermal water uptake test performed at GRS as well as the earlier performed simulations with code VIPER. An important motivation for the transfer of the VIPER-concept to COMSOL Multiphysics is broadening the range of possible applications from 1D to 3D modelling tasks.

After successfully completing this first step, further terms in the balance equation as well as equations of state were added which are required for calculating non-isothermal water transport. Furthermore, the simplified treatment of heat flow in VIPER could now be replaced by implementing a full coupling of the hydraulic formulations to the heat flow interface included in COMSOL Multiphysics.

The new implementation in COMSOL has been checked on the basis of temperature and humidity measurements from the FEBEX in-situ experiment performed at the Grimsel hard rock laboratory in Switzerland. The FEBEX-experiment was intended to represent the deposition of heat-producing nuclear waste canisters that were enclosed in a layer of compacted bentonite blocks in a tunnel in granitic rock. Wetting of the bentonite buffer was provided by the rather highly conductive host rock. Measured and simulated temperature evolution as well as wetting dynamics in the buffer matched each other reasonably well.

The presented work opens up the possibility to apply the alternative re-saturation concept to a wide range of three-dimensional problems not solvable by code VIPER. However, a number of further enhancements of the new model for instance concerning boundary conditions for water vapour or swelling into free space are conceivable as a follow-up.

How to cite: Kröhn, M. and Fromme, L.: An alternative thermo-hydraulic model for bentonite re-saturation exclusively based on diffusive water transport and its implementation in 3D, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9735, https://doi.org/10.5194/egusphere-egu22-9735, 2022.

EGU22-11278 | Presentations | ERE3.3

Michigan International Copper Analogue (MICA) project – assessment of long-term behaviour of copper in repository relevant environments 

Axel Liebscher, Heini Reijonen, Ismo Aaltonen, Xuan Liu, Christina Lilja, Simon Norris, Lindsay Waffle, Peter Keech, and Nikitas Diomidis

One of the key requirements for the deep geological disposal of high-level nuclear waste is the assessment of its long-term performance and safety. As any other barrier of the disposal system, waste containers must fulfil their respective safety functions for the required duration, which can vary from a few hundreds of years to several hundreds of thousands of years, depending on disposal system requirements. Sufficient corrosion resistance under repository conditions is one key requirement for container material to provide complete waste containment. Copper is an important part of many waste packaging and disposal concepts, e.g. KBS-3 developed in Sweden and Finland and Mark II developed in Canada. Much of the data available regarding its behaviour under repository conditions comes from short-term investigations, such as laboratory experiments at different scales and under controlled conditions. Observations made from copper analogue studies provide additional information on copper behaviour during the assessment time scale and under real geological environments. By this, they can support the argumentation in the safety case.

Keweenaw native copper occurrences (Lake Superior, US) reflects more than one billion years of deposit evolution covering various geological (from bedrock to sediments and even anthropogenic mine site remnants) and geochemical environments (e.g., brines to meteoric water, anoxic vs. oxic, sulphur-free vs. sulphur-bearing). These deposits have been mined for a long time and there is a great deal of knowledge related to them as well as samples collected. However, data to be used in process based safety assessments for geological disposal is lacking and no formal review has been made from the geological disposal point of view. The current MICA Project Phase I systematically collect and review the existing literature and data on the Michigan copper analogue sites and available sampling potential. Based on the outcome, MICA Project Phase II will then study and analyse prospective sites and samples to address relevant questions regarding long-term behaviour of copper under disposal conditions. The MICA Project thus will provide a unique complementary data source to estimate processes governing behaviour of metallic copper and to support safety cases.

How to cite: Liebscher, A., Reijonen, H., Aaltonen, I., Liu, X., Lilja, C., Norris, S., Waffle, L., Keech, P., and Diomidis, N.: Michigan International Copper Analogue (MICA) project – assessment of long-term behaviour of copper in repository relevant environments, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11278, https://doi.org/10.5194/egusphere-egu22-11278, 2022.

EGU22-11557 | Presentations | ERE3.3

Modelling of carbon steel canister and Ca-Mg bentonite boundary development 

Václava Havlová, Martin Klajmon, Angela Mendoza, David Dobrev, and Antonin Vokal

The “Assessment of the Chemical Evolution of ILW and HLW Disposal Cells” (abbreviation ACED) Work Package of the EURAD EJP project concerns the assessment of chemical evolution at the disposal cell scale involving component/material interactions and thermal, hydraulic and/or chemical gradients via the consideration of ILW and HLW disposal concepts that are representative of the various approaches being followed in Europe. The general objective of the modelling approach presented here is to create a geochemical and coupled reactive transport model for the assessment of the geochemical evolution along a carbon-steel canister/Ca-Mg bentonite boundary in terms of corrosion rates and geochemical alterations.

The modelling, conducted in the PHREEQC geochemical code, focused on the representation of 3 completed corrosion experiments (temperatures of up to 90°C) that provided data on the corrosion trends of C-steel under compacted Ca-Mg bentonite conditions under both laboratory and in-situ conditions.  

To date, the development of the geochemical modelling in the PHREEQC code includes: 

  • The modelling of the bentonite pore water chemistry
  • The equilibrium modelling of the canister - bentonite boundary
  • The kinetic modelling of corrosion processes at the canister - bentonite boundary

The final step will comprise the development of a complex reactive transport model, including the consideration of Fe migration into the bentonite.

It is planned that the model will also be used for the evaluation of experiments conducted at temperatures of up to 150°C which are currently underway as part of the ConCord WP of the EURAD EJP project.

How to cite: Havlová, V., Klajmon, M., Mendoza, A., Dobrev, D., and Vokal, A.: Modelling of carbon steel canister and Ca-Mg bentonite boundary development, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11557, https://doi.org/10.5194/egusphere-egu22-11557, 2022.

EGU22-12179 | Presentations | ERE3.3

Retention of radionuclides in a fracture infill 

Filip Jankovský, Karol Kočan, Eva Hofmanová, Václava Havlová, Milan Zuna, and Jan Smutek

The EURAD European Joint Project (www.ejp-eurad.eu) is a European project supported by the European Commission via the Horizon 2020 framework programme. WP 5: Fundamental understanding of radionuclide retention (FUTURE) concerns the quantification of the long-term retention of key radionuclides in solid phases aimed at developing models of reactive transport in the host rock in close cooperation with the Development and improvement of numerical methods (DONUT) WP. The Mobility of radionuclides in crystalline rock Task of the WP is aimed at the observation of the retention of DGR-relevant radionuclides in a crystalline host rock fracture filling and the evaluation of its contribution to the safety function of the crystalline host rock. A calcite fracture filling, nickel as the radionuclide of interest and caesium as the reference radionuclide were selected so as to allow for the study of sorption processes in the crystalline fracture environment. Samples of a natural calcite fissure infill and migmatite host rock extracted from the Bukov URF, Czech Republic, were distributed to the various project partners for experimental research purposes. Batch sorption experiments were subsequently performed on both materials using Ni, Cs and other elements in synthetic ground water and CaCl2 for the calcite. The results of Ni sorption on natural calcite revealed a lower level of retention than that of the surrounding host rock (migmatite).

How to cite: Jankovský, F., Kočan, K., Hofmanová, E., Havlová, V., Zuna, M., and Smutek, J.: Retention of radionuclides in a fracture infill, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12179, https://doi.org/10.5194/egusphere-egu22-12179, 2022.

The work is based on long term work of Helsinki commission of Baltic sea and own field and laboratory researches. High rate of knowledge is possibility of forecast. The highest rate is possibility of control. Baltic sea has giant importance in Europe ecology, economic and policy as sea dividing and uniting many states. The growth of instability of environmental-climatic processes, an increase in the number of natural disasters, has been observed since the beginning of the XX century and requires the improvement of methods of environmental-climatic forecasts. The economic situation makes relevant low-cost and progressive forecasting methods. Of particular importance is the logical-mathematical modeling, combining two types of models - dynamic and static. Dynamic based on the analysis of trends. Static models are cheaper and more intellect. They are based on an assessment of the state of the systems (primarily ecological) at the moment, taking into account the element of anticipatory reflection characteristic of living systems. Monitoring the behavior of animals can be the basis of predictions and the creation of static prognostic models. An important and little developed direction of environmental forecasting is the phenogenetic indication. It is based on the analysis of morphologic characteristics of biological populations, quantitative and qualitative variability, sex ratio, sexual dimorphism. The level of development of population and ecological genetics makes this method a promising direction of environmental forecasting. Modeling of environmental processes in the Baltic zone requires taking into account both global processes (increase in climatic instability and the number of extreme natural events, increase in anthropogenic pressure), as well as regional processes (melting ice in the Arctic due to the “pseudo-greenhouse effect” and an increase in the concentration of methane in the atmosphere, cyclical changes in salinity with a period of 55 - 50 years, etc.). Comprehensive assessment of remote and contact monitoring data can be the basis for integrated static and dynamic modeling and a promising direction for the development of environmental safety. The expected trend in the Baltic zone for 10 to 20 years is a slight decrease in temperature, a continuing increase in the number of extreme events and an increase in the biomass and biodiversity of both desirable and undesirable species.

How to cite: Sapunov, V.: Ecological prediction of Baltic region basing on combination of static and dinamic modeling, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-73, https://doi.org/10.5194/egusphere-egu22-73, 2022.

EGU22-789 | Presentations | ERE3.5

Structure of the Hydrocarbon Sphere of the Earth's Crust 

Yuri Galant

 

Earlier (GeoBio 2014, Moscow ) it was reported that an independent domain is observed in the Earth's Сrust - the Hydrocarbon Sphere (HCS). HCS is a sequential alternation of hydrocarbon fields in accordance with geological objects. HCS is a material space-time continuum spread throughout Earth Crust, from Archean to modern precipitation. On the scale of the Earth's crust, HCS is represented by the entire HC spectrum (light CH4, heavy HHC, normal, isoforms, etc.). Globally, chemically, the HCS gas composition of the Earth's Crust of the granite layer is similar to the HCS composition of gas fields and is equal to CH4-HHC, while the basalt layer corresponds to the HCS composition of oil fields and is equal to HHC - CH4. Structure of HCS   of the Earth Crust based on 1 layer  Мodel of the Earth's Crust Galant (MECG), ( AAPG Athens 2007, EGU Vienna 2013) сonsist of separated layers of CH4-HHC (Granite HC Sphere)and separated layers of HHC - CH4 (Basalt HC Sphere ).   Considering that, according to the MECG model, “there is no basalt crust under the granite crust, and there is no granite crust under the basalt crust”, both HCS of the Earth's Crust - Granite HC Sphere and Bazalt HC Sphere lies directly on mantle.

 

How to cite: Galant, Y.: Structure of the Hydrocarbon Sphere of the Earth's Crust, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-789, https://doi.org/10.5194/egusphere-egu22-789, 2022.

EGU22-5103 | Presentations | ERE3.5 | Highlight

Evaluation of the geological context for deep disposal options in Serbia 

Koen Beerten, Koen Lenie, Petar Stejić, and Dalibor Arbutina

The Republic of Serbia wishes to evaluate the various options for disposal of radioactive waste and used sources. The evaluation is supposed to be based on international solutions for radioactive waste, the current and future waste inventory of Serbia, and the various possible solutions for final disposal. A high-level assessment of the geological situation in Serbia, as well as an initial screening for suitable host rock material, is inherently included in such an evaluation, and is the aim of the current work.

Based on available information such as orohydrographical and morphostructural maps, the 1:300.000 geological map, individual but undisclosed 1:100.000 geological mapsheets, the 1:500.000 neo-Alpine tectonic map of Serbia, seismic hazard maps for different return periods, and various scientific publications dealing with the geological and tectonic evolution of Serbia and surroundings, several initial recommendations can be formulated that will support and assist the decision-making process in finding a suitable site (and host rock).

Roughly, the territory can be divided into two different regions with contrasting tectonic behaviour. South of the Danube, the relief intensity is significant and mountain massives with altitudes up to 2000 m and more are present. The most important morphostructural units include the Dinarides, the Vardar Zone, the Serbo-Macedonian Massif and the Carpatho-Balkanides. This region is characterised by outcropping and subcropping material that underwent significant deformation during various tectonic pulses in the past, resulting in a vast area with rather impermeable meta-sedimentary and metamorphic rocks. Neo-Alpine tectonics from the Oligo-Miocene onwards resulted in significant vertical uplift of the southern massifs, this pattern being interrupted by isolated and closed subsiding depressions. Throughout the region south of the Danube, magmatic rocks of various age, type and composition can be found, which are elsewhere being considered in international solutions for geological disposal. The same is valid for the previously mentioned meta-sedimentary and metamorphic rocks, which include flysch sequences, and several schist and gneiss occurrences.

North of the Danube, the Pannonian Basin is characterised by significant subsidence, up to several thousand meters since the Oligo-Miocene. The basin is filled with continental clastic deposits, with several prominent clay occurrences of sufficient thickness and depth. Clay rock and (plastic) unlithified clay are often being considered in international solutions for geological waste disposal.

The neo-Alpine tectonic map indicates the presence of numerous faults: gravitational, reverse and strike-slip. Quite a number of these have shown significant activity in the Pliocene and Quaternary, most notably those that mark the boundary between outcropping massifs and subsiding areas (e.g., between the Carpatho-Balkanides and the marginal part of the Pannonian Basin). Near those faults, historical seismic activity has been recorded with magnitudes up to M = 6.5. Seismic hazard seems to be highest in the central and southern part of the country.

In summary, this short geological reconnaisance of Serbia suggests that basic geological knowledge is available that will help evaluating the various disposal options, both in terms of host rock material (thickness and depth) and a stable geological environment.

How to cite: Beerten, K., Lenie, K., Stejić, P., and Arbutina, D.: Evaluation of the geological context for deep disposal options in Serbia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5103, https://doi.org/10.5194/egusphere-egu22-5103, 2022.

EGU22-5534 | Presentations | ERE3.5

Assessing long-term microbial impact on mineralogical trapping of uranium from deep groundwater at Äspö Hard Rock Laboratory, Sweden 

Ivan Pidchenko, John Christensen, Ignasi Puigdomenech, Konstantin Ignatyev, and Henrik Drake

Natural uranium (U) in deep groundwater has been extensively studied in connection to the search for suitable locations for final disposal of spent nuclear fuel (SNF).[1] The U removal process depends on environmental and geochemical conditions and is often associated with fractionation of the main ‘stable’ isotopes, 238U and 235U (δ238U). The latter thus serves as an important tracer for redox specific scenarios, in local to global temporal and spatial scales. In this contribution, one specific borehole drilled at 415 m depth into Paleoproterozoic granitoid rock at the Äspö Hard Rock Laboratory (HRL), Sweden, is investigated after 17-year experiment period (1995-2012).[2] The HRL is built and operated by the Swedish Nuclear Fuel and Waste Management Co. and serves as a full-scale tunnel as a test-facility for the actual SNF repository to be built at Forsmark. We show how various micro-analytical techniques, modelling methods, and isotope analyses can be utilized to reveal U speciation and removal pathways, associated redox changes and related U isotope fractionations in the deep aquifer and during U mineralogical trapping. Spectroscopic techniques reveal that calcite precipitated on the borehole equipment contains intermittent highly elevated U, occurring as U(IV), and thus serves as a sink for U. Thermodynamic modelling shows that aqueous Fe(II) is the main driving force for the reduction of U(VI) in the borehole water, alongside sulfides formed from bacterial sulfate reduction. The bacteria-driven degradation of technical polymer constituents present in the borehole equipment is central to processes forming the sulfides and carbonates that facilitate reduction of U(VI) and subsequent immobilisation of U(IV) into the calcite. We use δ238U to show that U undergoes several redox events in granitic rock aquifers, involving mineralogical and microbial pathways. The recorded δ238U provides evidence for reductive removal of U from fracture water, presumably taking place along redox fronts in the fracture network. The obtained data on U(IV) removal by calcite provide important insights for the assessment of the geochemical behaviour of U and other redox-sensitive species in deep anoxic aquifers, that is relevant for trace metal mobility and long-term storage of SNF and nuclear waste.

References

[1]. J. Suksi et al., (2021), Chemical Geology 584: 120551.

[2]. H. Drake et al., (2018), Environmental Science & Technology 52(2): 493-502.

How to cite: Pidchenko, I., Christensen, J., Puigdomenech, I., Ignatyev, K., and Drake, H.: Assessing long-term microbial impact on mineralogical trapping of uranium from deep groundwater at Äspö Hard Rock Laboratory, Sweden, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5534, https://doi.org/10.5194/egusphere-egu22-5534, 2022.

EGU22-7519 | Presentations | ERE3.5

Unified computational workflow framework for radionuclide migration assessment in deep geological repositories in clay rock 

Jaime Garibay-Rodriguez, Renchao Lu, Chaofan Chen, Haibing Shao, Olaf Kolditz, and Vanessa Montoya

In the context of deep nuclear waste disposal, a critical aspect in their safety assessment is the potential radionuclide release and migration into the geosphere during the required long period of disposal times. It is established that the multi-barrier system of underground repositories for nuclear waste will provide retardation for radionuclides migration. In this context, the understanding of the sorption mechanisms of radionuclides onto mineral surfaces (i.e., montmorillonite, illite) is essential [1]. On the other hand, reactive transport mechanistic-based radionuclide migration simulations, typically for 1 million years, pose a computational challenge. Surrogate-based simulations can be useful to enable sensitivity/uncertainty analysis that would be prohibitive otherwise from a computational point of view. Considering the current challenges in modelling radionuclide migration in low permeable clays and the importance of the results and implications of these simulations in socio-political decisions, it is necessary to provide appropriate computational tools in a transparent and easy-to-use way. In this work, we aim to provide such tools in a framework that combines the simulation capabilities of OpenGeoSys6 for radionuclide diffusion in porous media and the approachable nature of Project Jupyter [2] (i.e., JupyterLab), which provides a modular web-based environment for development, simulation and data integration. Several examples of the migration of different sorbing and non-sorbing radionuclides in a clay host rock for 1 million years are shown. Simulations results are obtained by using two numerical approaches, i) adopting a mechanistic model with multiple chemical species through OpenGeoSys-6#iPHREEQC and ii) the so-called single species approach by employing a pre-calculated look-up table to speed up the simulations [3]. In this way, we aim to promote the collaborative research of radionuclide migration assessment and, at the same time, to guarantee the availability and reproducibility of the scientific outcome through the OpenGeoSys initiative [4].

1. Mazurek, M. (2017). Far-field process analysis and radionuclide transport modeling for saturated media. In Geological Repository Systems for Safe Disposal of Spent Nuclear Fuels and Radioactive Waste (pp. 229-266). Woodhead Publishing.

2. Kluyver, T., Ragan-Kelley, B., Pérez, F., Granger, B. E., Bussonnier, M., Frederic, J., ... & Willing, C. (2016). Jupyter Notebooks-a publishing format for reproducible computational workflows (Vol. 2016, pp. 87-90).

3. Águila, J. F., Montoya, V., Samper, J., Montenegro, L., Kosakowski, G., Krejci, P., & Pfingsten, W. (2021). Modeling cesium migration through Opalinus clay: a benchmark for single-and multi-species sorption-diffusion models. Computational Geosciences, 25, 1405–1436.

4. Kolditz, O., Bauer, S., Bilke, L., Böttcher, N., Delfs, J. O., Fischer, T., ... & Zehner, B. (2012). OpenGeoSys: an open-source initiative for numerical simulation of thermo-hydro-mechanical/chemical (THM/C) processes in porous media. Environmental Earth Sciences, 67(2), 589-599.

How to cite: Garibay-Rodriguez, J., Lu, R., Chen, C., Shao, H., Kolditz, O., and Montoya, V.: Unified computational workflow framework for radionuclide migration assessment in deep geological repositories in clay rock, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7519, https://doi.org/10.5194/egusphere-egu22-7519, 2022.

EGU22-7779 | Presentations | ERE3.5

The Rock Mass Quality Index (RQI): a quantitative tool for the quality evaluation of near-surface rock masses 

Enrico D'Addario, Leonardo Disperati, Gianni Lombardi, and Lorenzo Marzini

The knowledge of rock masses behaviour is an important information in various fields such as civil engineering, land use planning and hazard/risk zoning. Different rock mass classification methods, initially aimed at assisting underground excavations (Hoek, 2007), are widely used nowadays for preliminary design procedures (Bieniawski, 1989; Hoek, 2007), like the RMR (Bieniawski, 1976) and the Q (Barton et al., 1974) and their modifications. These methods incorporate geological, geomechanical and geometric parameters in order to obtain a quantitative estimation of the rock mass quality, but, on the other hand, their implementation is time-consuming. Despite the dominance of these two methods, further rock mass classifications systems have been proposed in the last decades and, among these, the Geological Strength Index (GSI) classification system is currently widely used as it allows to estimate the strength of rock mass through empirical semi-quantitative evaluation (Hoek, 1994; Cai et al., 2004), based on both rock mass structure and condition of the joints (Hoek et al., 1995). Estimating the GSI is straightforward and fast, but it comes at the cost of a certain degree of subjectivity. Moreover, the index does not adequately account for the lithology of the rock mass matrix. Hence, for the above reasons, these classification methods are not fully suitable to collect rock mass data over wide scale areas for engineering geological mapping. The Rock mass Quality Index (RQI, Disperati et al., 2016; Mammoliti et al., 2018) is a rock mass classification system developed for cartographic purposes and it is based on the systematic fieldwork measurement and processing of sets of the Schmidt hammer rebound values (R). Each representative rock mass outcrop is analysed by collecting ca. 20 R values at the 15-25 nodes of a regular grid conceived to investigate the typical features of the rock mass. This allows to perform statistical analyses and to calculate the RQI, a quantitative indicator of the global strength and quality of the rock mass. In the last decade, a dataset of ca 1100 outcrops sites spreading over a large area (ca. 12000 km2) were acquired in Tuscany (Italy), according to different lithology, weathering, jointing conditions. The dataset consists of both RQI measurements and GSI estimations for the main different lithological groups (flysch, limestones, marls, magmatic rocks and schists) of the Northern Apennines (Italy), as well as the laboratory determinations of the Slake Durability Index (Id2; Franklin & Chandra, 1974) obtained by testing representative outcrop rock samples. The large dataset has allowed to analyse the correlation among RQI, GSI and Id2 and to perform an in-depth critical analysis of the relationships among RQI, lithology, rock mass structure, as well as the suitability of the RQI as reference index for engineering geological mapping of near-surface rock mass quality.

How to cite: D'Addario, E., Disperati, L., Lombardi, G., and Marzini, L.: The Rock Mass Quality Index (RQI): a quantitative tool for the quality evaluation of near-surface rock masses, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7779, https://doi.org/10.5194/egusphere-egu22-7779, 2022.

EGU22-8857 | Presentations | ERE3.5

Borehole Disposal of Radioactive Waste in Israel 

Ofra Klein-BenDavid, Geoff Freeze, David Sassani, Ran Calvo, Noa Balaban, and Gilboa Peer

Israel is assessing borehole disposal of radioactive waste. With limited geological options for disposal, intermediate-depth borehole disposal is being considered in the arid Yamin Plain region of the northeastern Negev desert at depths of several hundred meters below ground surface in the vadose zone. Unlike deep borehole disposal of several kilometers, which relies on emplacement below the depth of recirculating groundwater, the safety case for intermediate-depth borehole disposal relies more on the aridity of the vadose zone, the robustness of the engineered barriers (e.g., canister, seals, backfill materials) in the disposal borehole.

To study the suitability of the Yamin Plain region for borehole disposal a small-diameter characterization borehole is planned, to retrieve core samples and to better understand the vadose zone geo-mechanical and hydrogeochemical properties and percolation flux. Moreover, a wide range of laboratory geochemical, hydrological, and mechanical studies as well as a new seismic survey are being carried out. The information from the characterization borehole as well as the supplementary laboratory and seismic studies will inform the safety case, and together with performance assessment analyses will help to identify key areas of uncertainty and guide future research and development activities aimed at demonstrating the feasibility of the intermediate-depth borehole disposal concept in Israel.

How to cite: Klein-BenDavid, O., Freeze, G., Sassani, D., Calvo, R., Balaban, N., and Peer, G.: Borehole Disposal of Radioactive Waste in Israel, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8857, https://doi.org/10.5194/egusphere-egu22-8857, 2022.

EGU22-9706 | Presentations | ERE3.5 | Highlight

Calibration of a channel network model against Äspö field data and its application to long term prediction of tracer transport 

Benoit Dessirier, Kunwar Mrityunjai Sharma, Jonas Pedersen, Chin-Fu Tsang, and Auli Niemi

Final radioactive waste disposal in deep crystalline bedrock demands a thorough understanding of flow and transport mechanics in sparsely fractured rock formations. The structural complexity and heterogeneity of crystalline bedrock, and the scarcity of field data for the hydraulic characterization motivates the development of multiple alternative conceptual and numerical models, both to test our understanding and to evaluate prediction uncertainties. Discrete fracture network (DFN) models are widely used in radioactive safety assessment programs in hard crystalline rocks while channel network models offer another representation of flow networks and preferential pathways, in line with indications that flow and transport in deep fractured media are usually dominated by a relatively small number of long preferential pathways. This study applied the channel network modeling approach to understand the hydraulic behavior in a fractured granite system (approximately 450 m deep), at the Äspö Hard Rock Laboratory in Sweden. The channel network model is built from a hydro-structural model of the site including known fracture geometries, with the help of a python scripting library, pychan3d. The study focused particularly on an evaluation of the usefulness of different characterization data to build and calibrate such a channel network model, and to compare this to a calibrated DFN model of the same site. An evolutionary algorithm (CMAES_P implemented in the PEST code) was used to semi-automatically calibrate the channel conductances in the channel network model against the field characterization data (flow rates, drawdowns, and tracer recoveries) in multiple phases. It was observed during the calibration process that some proposed CNM connectivity maps lent themselves to conductance calibration, while others failed to do so. Channel tortuosity and width were then critical to describe transport appropriately in terms of peak arrival and dispersion. The CNM was shown to be more responsive to calibration and to general alterations than a DFN with uniform fracture planes. After calibration, the CNM could match the flow measurements closer than the reference DFN model for the tested characterization phases. The CNM and DFN with the calibrated conductances and fitted geometric parameters were then used to investigate a long-term tracer transport scenario. This comparative study highlights the potential differences and associated uncertainties in the behavior of the two distinct types of models used in the study of crystalline hard rock fractured system.

How to cite: Dessirier, B., Sharma, K. M., Pedersen, J., Tsang, C.-F., and Niemi, A.: Calibration of a channel network model against Äspö field data and its application to long term prediction of tracer transport, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9706, https://doi.org/10.5194/egusphere-egu22-9706, 2022.

EGU22-11213 | Presentations | ERE3.5 | Highlight

Fracture network modelling of a potential high-level nuclear waste repository site 

Emese Tóth, Ervin Hrabovszki, Schubert Félix, and M. Tóth Tivadar

The potential host rock for the high-level nuclear waste repository of Hungary is the Boda Claystone Formation (BCF) located in SW Hungary, a homogeneous formation with a thickness of 1000 m. The BCF consists of well-compacted reddish-brown claystone, siltstone, and albitolite (authigenic albite >50%) with dolomite and sandstone intercalations. Fracture network modelling and hydrological assessment were performed in the BAF–2 well, which is over 900 m deep. The fracture network was modelled using a discrete fracture network (DFN) algorithm based on acoustic borehole televiewer (BHTV) images and core sample images. This modelling approach can be used to calculate the permeability and porosity of the fracture system if the hydrologic aperture of the fractures is known. Fracture aperture can be defined in several ways. In hydrodynamic processes, the hydraulic aperture should be used, which is defined as a theoretical conduit that produces the same flow rate as the real fracture. The hydraulic aperture was estimated using a calibration algorithm comparing the measured permeability values of the borehole to the modelled permeability values of the fracture system. Hydrological evaluation of the borehole was performed by calculating flow zone indices (FZI). This parameter is based on the covariation of porosity and permeability and is usually used to evaluate reservoir quality. FZI values denote hydraulic units within the rock column where the properties controlling flow are internally uniform. Based on the geometry of the fracture network and hydraulic flow units, most parts of the well behave uniformly, while three narrow zones exhibit different hydrologic characteristics. The first zone is located in the upper 100 m of the well and is likely formed by weathering and diagenetic processes. The second zone is at about 400 m, where a large-scale structural boundary is suspected. In the third zone at 700 m, coarsening of the host rock strongly affects the hydrological properties, but the influence of tectonic processes cannot be excluded either.

How to cite: Tóth, E., Hrabovszki, E., Félix, S., and Tivadar, M. T.: Fracture network modelling of a potential high-level nuclear waste repository site, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11213, https://doi.org/10.5194/egusphere-egu22-11213, 2022.

EGU22-11455 | Presentations | ERE3.5

Assessment of the condition of Enguri High Dam in Georgia: the organisation of geodynamic monitoring 

Nino Goguadze, George Melikadze, Birgit Mueller, and Thomas Niederhuber

 In order to assess the reaction Enguri Dam nearby fault systems a monitoring system to study the seismicity and geodynamic situation has been set-up in recent years. To monitor the development of geodynamic processes, boreholes in the vicinity of the dam have been logged, intensively and permanent water level, temperature and conductivity monitoring was installed and where those parameters observations started to provide information about the stress field variation. The EGU presentation will introduce the different monitoring systems and present first results of data analysis. It also will show how repeated monitoring in boreholes can provide insight in the system stability.

How to cite: Goguadze, N., Melikadze, G., Mueller, B., and Niederhuber, T.: Assessment of the condition of Enguri High Dam in Georgia: the organisation of geodynamic monitoring, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11455, https://doi.org/10.5194/egusphere-egu22-11455, 2022.

EGU22-11632 | Presentations | ERE3.5

Engineering geological mapping of near-surface rock mass quality of folded and thrusted arenaceous flysch units in the Northern Apennines (Italy) 

Gianni Lombardi, Enrico D’Addario, Leonardo Disperati, and Francesco Ferrarelli

The regionalized knowledge of the quality of near-surface rock masses is an important tool for land management/planning, as well as for guiding further in-depth studies aimed at landslide and earthquake risk assessment and civil engineering planning. The characterization of heterogeneous rock masses like flysch units represents a relevant challenge to engineering geologists due to the complex structure of these materials, which results from both their depositional context and tectonic history. Flysches are widespread all over the Apennines chain and their mechanical characterization is a difficult task given the occurrence of intercalation of layers with different lithology and strength. Moreover, the complexity of the thrust and fold tectonic framework makes the regional distribution of these characters difficult to predict. The aim of this work is to provide a method to map the near-surface rock masses quality for an arenaceous flysch widely cropping out in the outer Northern Apennines (Torrente Carigiola Formation, Aquitanian; Bettelli et al., 2002). This formation is mapped in both the geological map of the Regione Toscana (Italy) at the scale of 1:10,000 and the geological sheet “252 – Barberino di Mugello” (Bettelli et al., 2002) of the Italian Geological Map at the scale of 1:50,000 (CARG). It is made up by intercalated arenaceous (A) and pelitic (P) layers characterized by variable A/P ratio. The rock mass quality is evaluated by estimating, for a set of representative rock outcrops, the Rock Mass Quality Index (RQI; Disperati et al. 2016; Mammoliti et al. 2018). This index results from the analysis of both systematic Schmidt hammer rebound measurements (R) acquired at the nodes of a regular grid (ca. 20 R measurements for ca. 15-25 nodes) and the determination of the unit weight for representative outcrop rock samples. For the same outcrops, also the A/P ratio and bedding attitude are determined. The results show a positive linear correlation between RQI and the A/P ratio, confirming that the latter parameter is an important feature controlling the rock mass strength. This correlation is used to assess the distribution of both parameters within a set of geological cross sections traced normal to the regional structures trend (main thrusts and km-scale folds). Then, the structural features available from the literature geological maps allow us to extrapolate both the RQI and A/P ratio from the profiles to the map scale. Finally, a further set of the same rock outcrop data acquired after the above-described modelling procedure is used to check the accuracy of the method.

How to cite: Lombardi, G., D’Addario, E., Disperati, L., and Ferrarelli, F.: Engineering geological mapping of near-surface rock mass quality of folded and thrusted arenaceous flysch units in the Northern Apennines (Italy), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11632, https://doi.org/10.5194/egusphere-egu22-11632, 2022.

EGU22-13268 | Presentations | ERE3.5 | Highlight

The DR-D experiment in the Mont-Terri rock laboratory, heterogeneity of the Sandy Facies of Opalinus Clay across scales, from seismic surveys to radionuclide diffusion 

Frank Heberling, Hendrik Albers, Thies Beilecke, Guido Deissmann, Markus Furche, Horst Geckeis, Eva Maria Hoyer, Claudia Joseph, Axel Liebscher, Stefan Lüth, Volker Metz, Katharina Müller, Ulf Nowak, Dorothee Rebscher, Friedhelm Schulte, Florian Steegborn, and Torsten Tietz

Clay rocks are investigated as potential host rocks for high-level nuclear waste (HLW) repositories in many countries. The Sandy Facies of Opalinus Clay (SF-OPA), as accessible in the Mont Terri rock laboratory, exhibits a pronounced heterogeneity, which is as well expected for lower cretaceous clay rocks, that are among the potential host rocks for the German HLW repository.

Aim of the DR-D experiment is to characterize the heterogeneity of SF-OPA on the m-cm scale via seismic tomography and borehole seismic characterization. Borehole logging and ex-situ drill core characterization provide information on rock heterogeneity on smaller scales.

Within the area, characterized by seismic tomography, a radio-tracer diffusion experiment will be set up, with the aim to correlate the observed diffusion behavior with the heterogeneous rock structure.

The first drilling campaign took place in May 2021. The seismic tomography survey of the experimental area was performed in October 2021. Processing and analysis of the seismic data, as well as drill core characterization are currently underway.

In this contribution we present the general concept and layout of the DR-D experiment, as well as first results.

We acknowledge funding by the German Federal Ministry of Education and Research (BMBF) (Grant 02NUK053A-E), the Helmholtz Association (Grant SO-093), BGR, and BGE. Special thanks to swisstopo and the Mont-Terri project for help, advice, and support.

 

How to cite: Heberling, F., Albers, H., Beilecke, T., Deissmann, G., Furche, M., Geckeis, H., Hoyer, E. M., Joseph, C., Liebscher, A., Lüth, S., Metz, V., Müller, K., Nowak, U., Rebscher, D., Schulte, F., Steegborn, F., and Tietz, T.: The DR-D experiment in the Mont-Terri rock laboratory, heterogeneity of the Sandy Facies of Opalinus Clay across scales, from seismic surveys to radionuclide diffusion, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13268, https://doi.org/10.5194/egusphere-egu22-13268, 2022.

EGU22-13279 | Presentations | ERE3.5

Evolution of pH induced by salt concentration change under flowthrough conditions 

Johannes Lützenkirchen, Khalil Hanna, and Remi Marsac

Column experiments are more sensitive to surface reactions than batch studies due to the increased surface area to liquid volume ratio. Moreover, these dynamic set-ups allow for stringent tests concerning the validity of equilibrium models for surface protonation and adsorption of pollutants.  In the present study, column experiments were carried out at constant pH, where the concentration of background electrolyte consisting of monovalent electrolytes like NaCl at the inlet were varied. Due to the charging phenomena caused by ionic-strength dependent acid-base reaction, the pH at the outlet of column varied. On a positively charged surface (such as alumina at pH 5.8) the increase in salt concentration at the inlet caused a transient increase in pH due to enhanced protonation of surface hydroxyls. On a negatively charged surface (PTFE at pH 5.8) the increase in salt concentration caused a decrease in pH at the column outlet due to enhanced uptake of hydroxide ions at higher salt concentrations. The charging behavior of both surfaces was independently determined by streaming potential measurements. For PTFE column experiments at different pH values were carried out to further relate them to the streaming potential data. Indeed below the isoelectric point, the trend of the pH-jump at the outlet of the column was inversed which suggests pH dependent charging of this inert surface due to protons and hydroxide ions.

Overall, the experiments show the high sensitivity of column experiments to changes in solution composition and the kind of experiments may allow for determining points of zero charge in an elegant way.

How to cite: Lützenkirchen, J., Hanna, K., and Marsac, R.: Evolution of pH induced by salt concentration change under flowthrough conditions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13279, https://doi.org/10.5194/egusphere-egu22-13279, 2022.

EGU22-13385 | Presentations | ERE3.5 | Highlight

The FE-M Task Force: 3D modelling of THM repository induced effects in the Full-scale Emplacement Experiment (FE) – Mont Terri Rock Laboratory. Current status and the path forward. 

Andres Alcolea, Ivan P. Damians, Berrak Firat-Lüthi, Benoit Garitte, Antonio Gens, Olaf Kolditz, Lyesse Laloui, Bill Lanyon, Aldo Madaschi, Paul Marschall, Thomas Nagel, Sebastia Olivella, Andreas Reinicke, Hua Shao, Wenqing Wang, and Matthias Wojnarowicz

The construction and operational phases of a deep geological repository imply potential perturbations of the host rock, so-called Repository Induced Effects (RIE). Amongst them, spent fuel and high level waste (SF/HLW) produce decay heat even after long times of cooling, which may impair the long-term safety of the Engineered Barrier System and of the geological barrier. The Opalinus Clay (OPA), is currently being assessed as host rock for the deep geological repository in Switzerland. OPA is an indurated clay of Jurassic age (ca. 180 My), whose main features are (1) a very low hydraulic conductivity, (2) an excellent retention capacity for dissolved radionuclides, and (3) a significant self-sealing capacity.

The on-going Full-scale Emplacement (FE) Experiment at the Mont Terri Underground Rock Laboratory simulates, as realistically as possible, the construction, waste emplacement, backfilling and early-stage post-closure evolution of a single SF/HLW emplacement tunnel in OPA, using heaters instead of disposal canisters. The main goal of the FE experiment is the investigation of RIE on the host rock (and, to a lesser extent, on the the backfill material) at true scale and the validation of existing coupled thermo-hydro-mechanical (THM) models. In this context, Nagra has developed a new RD&D initiative, i.e., the FE modelling Task Force (FE-M TF), which involves three modelling teams with corresponding software packages (Code Aster, Code Bright and OpenGeoSys). So far, the TF has defined three main tasks:

  • Code comparison and calculation verification: the TF designed a simplified (though realistic) 3D conceptual model of the FE experiment that includes the actual geometry of the main elements, materials and phases of the FE experiment, including tunnel excavation and ventilation. Such conceptual model was implemented by the modelling teams. Finally, code outputs were analysed and compared by the TF.
  • Back-analyses of THM-observations in the host rock: monitoring data from radial
    and oblique boreholes around the backfilled FE tunnel are used for model calibration,
    including the derivation of parameter best estimates and inherent uncertainties, and model
  • Model validation in the context of a prediction-evaluation exercise: the evolution
    of the THM conditions in the rock in response to a change of thermal loads (e.g., increase/decrease of heater output) will be predicted using the calibrated models. Finally, model predictions will be validated in the near future using the acquired measurements.

This presentation summarizes the current status of Tasks 1 and 2 and the path forward to Task 3.

How to cite: Alcolea, A., Damians, I. P., Firat-Lüthi, B., Garitte, B., Gens, A., Kolditz, O., Laloui, L., Lanyon, B., Madaschi, A., Marschall, P., Nagel, T., Olivella, S., Reinicke, A., Shao, H., Wang, W., and Wojnarowicz, M.: The FE-M Task Force: 3D modelling of THM repository induced effects in the Full-scale Emplacement Experiment (FE) – Mont Terri Rock Laboratory. Current status and the path forward., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13385, https://doi.org/10.5194/egusphere-egu22-13385, 2022.

EGU22-13412 | Presentations | ERE3.5

Barite Recrystallization to Witherite in the Presence of Carbonate, and the Impact on Radium Retention 

Mohammed Alzaydan, Thomas Roth, Frank Heberling, Robert Polly, Dieter Schild, and Volker Metz

In deep geological repositories for nuclear waste, groundwater may saturate the (geo-) technical barriers, and waste container corrosion may be occurring. This may finally lead to radionuclides being released from the waste [1]. The sorption capacity of potential host rocks, such as crystalline rocks and clay rocks, and of potential secondary phases is an essential aspect in the Safety Case. Barite (BaSO4) can be present in crystalline rocks as a fracture filling material. In clay rocks, sulfate minerals ((Ba,Sr)SO4) are found as accessories. Barium (Ba) is present in the waste as a fission product and as sulfate containing groundwater contacts the waste, barite may form. Ra uptake by barite occurs when dissolved Ra reacts with barite, leading to Ra retention by (Ba,Ra)SO4 solid-solution formation [2]. Barite reaction with aqueous carbonate at high pH, e.g. due to cementitious material alteration inside a repository, may cause barite to convert into witherite (BaCO3) [3]. The presence of carbonate likely alters the chemical behaviour of barite surfaces, via surface mixing or by witherite layer formation through dissolution-precipitation [4]. Aim of this study is to investigate the effect of carbonate on Ra retention by barite.

The presented results highlight barite transformation into witherite in the absence and presence of Ra. Barite suspensions were contacted with carbonate solutions (1-100 mM, pH 7-11). X-ray diffraction (XRD) showed shifts of reflection peaks in batches with pH 9-11 and carbonate concentrations of 10-100 mM, indicating a witherite-barite solid-solution formation [3], though this is not energetically favorable according to Density Function Theory calculations. Reaction rates depend on the type of barite. Generally, reactions slow down after about 7 days, likely due to surface passivation. Cubes of natural barite were reacted with 100 mM carbonate solutions at pH 11. As a result, a porous witherite layer with (271±32) μm formed, giving insight into recrystallization process progress and mechanism. Atomic Force Microscopy measurements were conducted for witheritegrowth. Barite was equilibrated at 35°C and contacted with a carbonate solution (0.01M, pH 10). Orientated particles with different shapes grew. More measurements will be conducted with different conditions to obtain a distinct growth. For Ra uptake, witherite batches(S/L 0.01, pH 8.7) were prepared for Ra to be spiked subsequently.  

We acknowledge KACST funding and the German federal ministry for education and research for funding the travel through the collaborative project KRIMI, grant agreement 02NUK056A.

 

[1]       Curti, E., et al. (2010) Geochim. Cosmochim. Acta 74.12, 3553-3570.

[2]        Heberling et al. (2018) Geochim. Cosmochim. Acta 232, 124-139.

[3]        Rendón-Angeles et al. (2008) J. Materials Science 43, 2189-2197.

[4]        Putnis and Putnis (2007) J. Solid State Chemistry 180, 1783-1786.

 

How to cite: Alzaydan, M., Roth, T., Heberling, F., Polly, R., Schild, D., and Metz, V.: Barite Recrystallization to Witherite in the Presence of Carbonate, and the Impact on Radium Retention, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13412, https://doi.org/10.5194/egusphere-egu22-13412, 2022.

EGU22-13436 | Presentations | ERE3.5

The impact of Se and Np on Calcite growth 

Lukas Zunftmeister, Dieter Schild, Eva Soballa, and Heberling Frank

Calcite is an ubiquitous mineral in numerous natural settings as well as in potential host rocks for high level nuclear waste repositories. Its retention capacity for Se and Np is critical for the safety assessment of nuclear waste repositories.

If the waste containers come into contact with groundwater, tank failure due to corrosion will eventually lead to the release of radionuclides from the waste. In this case, the retention capacity of the surrounding host rock governs the mobility of radionuclides. The understanding of said retention processes and underlying KD values can be applied in preliminary saftey assessments of potential disposal sites. In natural geological systems, Calcite may be subjected to dynamic dissolution and re-precipitation processes (recrystallization). This study addresses the incorporation of Se and Np into Calcite and the complex interplay between ion uptake and recrystallization rates. The recrystallization from aragonite to calcite allows us to investigate the growth of calcite under relatively constant, low supersaturations. Long-term recrystallization experiments have been performed both under the presence of Np(V)O2+ and Se(IV)O32-. Both ions were observed to inhibit the recrystallization process in seperate long-term batch experiments. Under the presence of Se, growth on certain crystal faces is inhibited more strongly, leading to changes in the crystal habit, which have been observed through SEM and XRD. AFM studies have been conducted to get a better understanding on the mechanisms involved.

 

Funding acknowledgements:

This research was supported by the federal ministry of education and research (BMBF), grant agreement 02 NUK 056A (KRIMI)

How to cite: Zunftmeister, L., Schild, D., Soballa, E., and Frank, H.: The impact of Se and Np on Calcite growth, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13436, https://doi.org/10.5194/egusphere-egu22-13436, 2022.

EGU22-13448 | Presentations | ERE3.5 | Highlight

Nagra's Approach to Gas Release from Deep Geological Repositories 

Olivier Leupin, Nikitas Diomidis, Andreas Reinicke, and Alexandros Papafotiou

Geological disposal of low and intermediate-level and high-level waste in Switzerland may - due to corrosion and degradation related processes - result in the production of gas. In our presentation we will focus on the integration of gas related processes and phenomena in the safety case and site selection. In addition, we will elaborate on what technical strategies Nagra follows to limit the potentially detrimental effects on the safety related properties of the technical and natural barriers.

Geological disposal of low and intermediate-level and high-level waste in Switzerland may - due to corrosion and degradation related processes - result in the production of gas. In our presentation we will focus on the integration of gas related processes and phenomena in the safety case and site selection. In addition, we will elaborate on what technical strategies Nagra follows to limit the potentially detrimental effects on the safety related properties of the technical and natural barriers.

How to cite: Leupin, O., Diomidis, N., Reinicke, A., and Papafotiou, A.: Nagra's Approach to Gas Release from Deep Geological Repositories, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13448, https://doi.org/10.5194/egusphere-egu22-13448, 2022.

ERE4 – Raw materials

EGU22-1268 | Presentations | ERE4.1

Characterisation and Historical Quarries Location of Marbles from Guarrazar Archaeological Site (Toledo, Spain). 

David Freire-Lista, Jose Francisco Santos, and Luis Lopes

Marbles have been used for the beautification of cities, temples and palaces throughout history. These building stones are compositionally analogue but show differences in texture and colour that can be associated with some petrographic and petrophysical properties, which makes possible to identify their origin.

A variety of building marbles from Guarrazar archaeological site (Toledo, Spain) was investigated. This site was a monastic-palatial complex linked to the Spanish Visigoth kings. It is archaeologically significant because Guarrazar's treasure, composed of gold votive crowns and crosses of the 7th century, were found in this site and are preserved in the National Archaeological Museum of Spain, in the Armory of the Royal Palace of Madrid and in the Cluny Museum of Paris, France.

The marbles were characterised petrographically, with polarisation optical microscopy; mineralogically with XRD; petrophysically with ultrasound pulse velocity, Hg intrusion porosity and colour measurements and chemically with isotopic analysis, which is carried out by mass spectrometry. All these analyses were carried out to locate the historical quarries of the marbles used in the basilica of the Guarrazar archaeological site.

Most of the analysed samples were reused marbles from Roman structures. The calcitic marbles are white and pinkish, and some of them have an irregular distribution of small greyish veins. They are medium grained, showing grain sizes from 103 μm up to 1.75 mm, and an average value of 423 μm. Mercury intrusion porosity ranges between 0.77 and 0.42 %. The main type of marbles comes from Estremoz Anticline, Ossa-Morena Zone (Southern Branch of the European Variscides in Portugal), distant approximately 300 km from the site. This 40 km NW–SE structure has been mined intensively since the Roman Period.

Estremoz marble is designated as Global Heritage Stone Resource (GHSR) by Heritage Stones Subcommission of the International Union of Geological Sciences (IUGS) . This designation seeks international recognition of those natural stone resources that have achieved widespread utilization in human culture.

 

How to cite: Freire-Lista, D., Santos, J. F., and Lopes, L.: Characterisation and Historical Quarries Location of Marbles from Guarrazar Archaeological Site (Toledo, Spain)., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1268, https://doi.org/10.5194/egusphere-egu22-1268, 2022.

The city of Ouro Preto, located in Minas Gerais, Brazil, a cultural heritage of humanity since 1980, has still preserved within its listed urban site, buildings built from the 18th century, when Brazil was still a Portuguese colony. In a geological context, it is certain that the city grew in the middle and is surrounded by mountain ranges formed by quartzite crests with some occurrence of schist and steatites in the regions of its valleys. Based on comparisons with other regions of the country, it can be stated that due to this particular geodiversity, the city stands out even from others in Minas Gerais, due to the volume and diversity of quartzite material used in its buildings. The architectural ensemble that served as the basis for the granting of the title by Unesco includes buildings and monuments with public, religious and private purposes, which make up a legacy of importance for the history of Minas Gerais and Brazil. The set built using quartzite material, however, inspires attention, since the artisanal process of extracting and processing the pieces did not take into account properties suitable for applications, which until then were little known. Taken from known areas around the city and located in the mountains known as Ouro Preto and Itacolomy, it appears that the process did not involve steps and procedures that are typical of quarries, especially those we know today. These rocks were, for the most part, collected both in the form of blocks and plates, later undergoing some kind of processing. The blocks were widely used as structuring elements, such as pillars and columns, door and window frames and the plates, used in external and internal coatings. With some frequency, blocks were also used in decorative elements in masonry, such as portals on church facades and even in sculptural art, with the production of elements that make up various building facades such as, for example, the former Chamber and Prison House, currently headquarters of the Museum of the Inconfidence. With a greater or lesser degree of detail, these works can also be seen in the nineteen churches and chapels inserted in the listed perimeter. Sculptural elements are also present in a good part of the various fountains built in different parts of the old city, among them, six individually listed and whose objective was to facilitate the supply of water to the city. With some rarity, compositions involving the use of schists and steatite in decorative arrangements with quartzites are observed. It is understood that the survey of information on the former extraction areas of these rocks, on the various types of applications and on the buildings that are part of this architectural set, as well as on their deterioration processes, will be of importance to support conservation actions of this cultural heritage.

How to cite: Costa, A. and Boas, P.: Built cultural heritage of Ouro Preto, Brazil: an architectural legacy edified in quartzite stone, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1901, https://doi.org/10.5194/egusphere-egu22-1901, 2022.

Solid brick is a very old construction material used in the construction of monuments and buildings, the manufacture of solid brick is essentially based on the use of terracotta, this used earth conditions the specific characteristics of the brick and its mechanics behavior and its lifespan in the monument.

 In this work and recognizing the importance of characterizing the traditional building materials we plan to study some samples of solid bricks made and used during the Marinid dynasty recovered from the historic site of Chellah which is located in the named city of Rabat as a shared heritage in 2012 and also the solid bricks used in restoration to deduce the similarities and differences.

We will study them under an optical electron microscope and we will expose them to the X-ray diffraction and fluorescence tests, this will allow us to identify the pathologies and degradations of the two types of bricks and the origins of the materials used and their primary compositions.

How to cite: Belhaj, S. and Belhaj, O. E.: Study and Comparison of Solid Bricks Used by Merinids and those For Restoration Within the Chellah Historical Site, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2069, https://doi.org/10.5194/egusphere-egu22-2069, 2022.

EGU22-2694 | Presentations | ERE4.1

Mortar damage to stone built heritage 

Lisa Mol, Charlotte Brassey, and Emma Cunliffe

Stone built heritage in conflict areas is increasingly at risk of accelerated deterioration, as explosive and ballistic damage not only create damage to the surface, but also inherently change the mineral fabric of the stone to deep within the structure. In particular, remotely detonated high-power explosive ordnance has become more accurate and economically viable for state forces, especially given the availability of remote-controlled military aircraft. Concurrently, armed non-state groups engaged in asymmetric warfare rely on (improvised) ground-based explosive devices, seen to devastating effect at high-profile sites like Palmyra.

Stone in historic buildings is pre-weakened through centuries/millennia of exposure to weathering, and may be particularly vulnerable to subsequent heat and shock waves generated by explosives. Whilst appearing unaltered externally, exposure to high-pressure explosive force can result in the growth of microfractures and loss of cohesion within the cement matrix of stone, potentially leading to fracturing and crumbling, particularly if such stones are load-bearing within a rebuilt structure. The loss of density associated with explosive damage is particularly problematic. We show that our preliminary testing of the effect of an 81 mm HE mortar bomb blast in the vicinity of sandstone structures indicates changes in rock surface hardness as well as complex fracturing of the surface. Both visible and non-visible damage were recorded using high speed cameras, rock surface hardness surveys pre- and post-detonation, and photogrammetry. We conclude that even if not directly exposed to an explosive blast, stonework can be inherently altered.

 

How to cite: Mol, L., Brassey, C., and Cunliffe, E.: Mortar damage to stone built heritage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2694, https://doi.org/10.5194/egusphere-egu22-2694, 2022.

EGU22-5310 | Presentations | ERE4.1

Natural stones in the cities - an easy way to focus on rocks and geology 

Angela Ehling and Ferdinand Heinz

Stones and thus building stones are very rarely in the focus of public interest. Geologists working with building stones use every opportunity to interest and sensitize people to this topic. Natural stones have served as building stones since time immemorial and they can be found in almost every town and village right before our eyes. They only need to be made visible to the viewer. Besides the explanation of the rocks, their petrographic and mineralogical composition, contained fossils and structures, technical features as well as their weathering behavior, one can point out many other aspects. This includes the geology of the area, geological timetable, mining, processing, transportation and use in past times and today, as well as aspects of restoration. Many geologists took and take advantage of this opportunity for geological and cultural education. They have written natural stone guides for several cities and organize natural stone excursions through their cities.

 

The German network “Stones in the city” has compiled a bibliography on this topic, which is constantly updated (www.steine-in-der-stadt.de). The bibliography contains just over 1100 entries on publications of dimension stones in cities worldwide. The time frame of the recorded publications is between the middle of the 19th century and the current year. The focus of this bibliographic collection includes the subject area of European building and decorative stones with a view of cultural geology. Some interesting aspects about the natural stone guides are presented in evaluation of this bibliography.

How to cite: Ehling, A. and Heinz, F.: Natural stones in the cities - an easy way to focus on rocks and geology, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5310, https://doi.org/10.5194/egusphere-egu22-5310, 2022.

EGU22-8148 | Presentations | ERE4.1

Different varieties of black marble from “Monregalese” district in Piedmont (Italy) 

Rossana Bellopede, Paola Marini, Claudia Chiappino, and Bartolomeo Vigna

In Piedmont, where five main quarry districts  can  be recognized (Barale et al 2020), Maritime and Ligurian Alps,  corresponding to the mountain area of southern Piedmont and characterized by a  wide variety of marble and sedimentary carbonate rocks, includes the historic ‘Monregalese’ district (G.A.L. Mongioie, 2005).

Among the several varieties of “Monregalese” marble exploited in the past, Nero di Frabosa, Nero Nuvolato di Miroglio, Nero Vallone , Nero di Ormea and Nero di Garresio are  black marble known and identified in Piedmont Cultural Heritage. These varieties of marble come from a small portion of the Mesozoic carbonate succession called Calcari di Rio di Nava and referable to the Middle Jurassic (Dogger). The entire stratigraphic series of the Brianzonese area consists of a limestone-dolomitic sequence of Trias, greater than 300 m in thickness, followed by pure Jurassic limestones (about 100 m thick) and Cretaceous marly-arenaceous limestones (thickness greater than 150 m). In the innermost sector of the Alpine chain, metamorphism and tectonic deformation were much more intense than in the outer portion. The result of this deformation is a high fragmentation of the entire stratigraphic succession with the formation of flakes and bands of carbonate rocks with sharply vertical geometries and small dimensions that alternate with the quartzites and metavulcanites of the base. The succession of Rio di Nava limestones consisting of dark limestones with abundant organic substance and the presence of levels rich in bioclasts, with an original thickness of about 50 meters, was affected by this metamorphic phase, originating the aforementioned Monregalese black marble varieties.

Nero di Frabosa has been employed in lower part of the Chapel of the Shroud (Turin), Vicoforte Sanctuary; Church of San Giorgio (Frabosa Sottana); Nero Nuvolato in the Mussocco cemetery (Milan), in the Church of San Madre di Dio (Turin); Nero Vallone in the Church of Santa Maria Assunta (Montaldo).

From the technical documents there are informations only on the employ in the past years of Nero Garessio (and none related to Nero di Ormea), characterized by numerous and thin white veins. Nero di Ormea differs from it for the darker color of the veins. All these black marble were used inside therefore their resistance to weathering is not well known. Only for Nero di Ormea, the last quarried one, there are data on ageing tests in order to assess their suitability to be used outside and not only for inner and aesthetical purpose.

 

How to cite: Bellopede, R., Marini, P., Chiappino, C., and Vigna, B.: Different varieties of black marble from “Monregalese” district in Piedmont (Italy), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8148, https://doi.org/10.5194/egusphere-egu22-8148, 2022.

EGU22-8826 | Presentations | ERE4.1

The Geoheritage value of the iconic buildings of Iaşi City, Romania 

Ana-Maria Anastasiei, Lilian Niacşu, and Andrei Enea

Iconic buildings in Iași City are an expression of the local geologic and geomorphologic settings, because building materials are locally procured. We analyse and highlight the reasons why this particular city – characterised by many emblematic buildings and a high potential in terms of building materials, may successfully develop its geotourism sector. A case study of the geotourism enhancement of the Repedea site as a source of construction and ornamental stone for some iconic buildings in Iasi City is presented. We want to argument that geotourism in Iasi city can be integrated as part of urban tourism. Its traditional sense, namely as the kind of tourism specific to such landscapes, should be understood as a catalyst of urban architecture and building materials. These explicitly reflects the local geomorphological and geological environment, thus being an important element of the trips that aim to offer the experience of a special place in the city.

How to cite: Anastasiei, A.-M., Niacşu, L., and Enea, A.: The Geoheritage value of the iconic buildings of Iaşi City, Romania, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8826, https://doi.org/10.5194/egusphere-egu22-8826, 2022.

EGU22-10687 | Presentations | ERE4.1

Alabaster, a millenary stone of European cultural heritage 

Wolfram Kloppmann, Lise Leroux, Philippe Bromblet, Sophie Jugie, Pierre-Yves Le Pogam, and Aleksandra Lipinksa

Because of its ease of working in minute detail and its whiteness, gypsum alabaster was one of the preferred materials for European sculpture rivalling marble in the late Middle Ages and early modern period.  Its natural deposits are spread all over Europe, from the English Midlands to the Ukraine, from the Ebro basin to Tuscany, from the Alps and the Jurassic to central Germany (Fig. 1).  The close connection between natural alabaster deposits and artistic centres, which has emerged in recent work, is related to the ecological perspective currently much discussed in art history, which emphasises the convergence of nature and culture. This new approach is based on a combination of art historical, historical and natural scientific methods and has been employed in several research projects over the last decade, involving geologists, geochemists, art historians, and conservators in a network of heritage research institutions, geological surveys, and museums. Progressively, the links established by this transdisciplinary work between historical alabaster deposits and artworks outline the evolution of the networks of European “alabaster routes”, of transfer of unworked stone, art, artists and technical and artistic knowledge which confers to this heritage stone a unique role in European integration.

Here we present the current state of the art on prominent historical alabaster quarries, notably in France and Germany, and research perspectives in the framework of the upcoming Franco-German Materi-A-Net project co-funded by ANR and DFG.

Fig. 1 Principal alabaster deposits used for sculpture in Late Medieval and Early Modern times. Transdisciplinary network of the Materi-A-Net project.

How to cite: Kloppmann, W., Leroux, L., Bromblet, P., Jugie, S., Le Pogam, P.-Y., and Lipinksa, A.: Alabaster, a millenary stone of European cultural heritage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10687, https://doi.org/10.5194/egusphere-egu22-10687, 2022.

EGU22-2411 | Presentations | ERE4.2

MSWI fly ash incorporation into acid-based geopolymer: reactivity and performance impact 

Davide Bernasconi, Alberto Viani, Petra Mácová, Lucie Zárybnická, Caterina Caviglia, Enrico Destefanis, Simone Bordignon, 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, many studies have evaluated the incorporation of FA into alkali silicate-based geopolymer. This material is obtained by the reaction between an aluminosilicate source (metakaolin, MTK) and alkali hydroxide (NaOH, KOH), to obtain polymer-like condensation product (Wang et al, 2019). This material is characterized by higher durability and greenness with respect to the conventional Portland cement (OPC), thus gaining interest recently as a promising partial substitute to OPC. On the other hand, much less attention has been focused on acid-based geopolymer, in which the alkali hydroxide is substituted by phosphoric acid, thus producing an Al-O-P/Si-O-P polymeric matrix (Wang et al, 2019). This material has displayed better performance than the traditional alkali-silicate geopolymer, in terms of corrosion resistance (Wagh et al, 2011), thermal stability (Celerier et al, 2019) and mechanical strength. However, there are also some drawbacks, mainly related to the expensive cost of the starting materials, since MTK is obtained by high-temperature (750°C) calcination of kaolinite. The introduction of FA would be economically beneficial both by reducing the amount of MTK needed and providing a destination for a waste residue which otherwise would require important management costs.

In this work, (previously washed) FA partial replacement of MTK has been tested in the phosphate-based geopolymer formulation, up to 50 wt%. Different synthesis conditions have been evaluated, in terms of Al/P molar ratio, liquid-to-solid ratio and curing temperature. The resulting reaction products have been investigated by a combined analytical approach, involving spectroscopies (ATR-FTIR and Solid-state NMR) and powder X-ray diffraction techniques, while their morphology was inquired by SEM-EDS analysis. Moreover, compressive strength tests have been employed to evaluate the mechanical properties, which demonstrated the good performances of FA blended phosphate-based geopolymers, with compressive strength values over 30 MPa.

 

Reference

  • 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.
  • Y. Wang, Y. Alrefaei, J. Dai. Silico-Aluminophosphate and Alkali-Aluminosilicate Geopolymers: A Comparative Review, Frontiers in Materials, 6 (2019), 106.
  • A.S. Wagh. Phosphate geopolymers, Ceramic Engineering and Science Proceeding, 32, 10 (2011), 91-103.
  • H. Celerier, J. Jouin, A. Gharzouni, V. Mathivet, I. Sobrados, N. Tessier-Doyen, S. Rossignol. Relation between working properties and structural properties from 27Al, 29Si and 31P NMR and XRD of acid-based geopolymers from 25 to 1000 °C, Materials Chemistry and Physics, 228 (2019), 293-302.

How to cite: Bernasconi, D., Viani, A., Mácová, P., Zárybnická, L., Caviglia, C., Destefanis, E., Bordignon, S., Gobetto, R., and Pavese, A.: MSWI fly ash incorporation into acid-based geopolymer: reactivity and performance impact, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2411, https://doi.org/10.5194/egusphere-egu22-2411, 2022.

EGU22-3176 | Presentations | ERE4.2

Role of Basalt in Green Mining 

Hamdy El Desouky

The growth of the world population pressures for an increasing demand for the extraction of the Earth's non-renewable mineral resources, which are essential for modern living. The heavy mining operations associated with this extraction have several negative environmental and societal impacts, including the emission of greenhouse gases and the production of large volumes of solid waste. Green mining aims to adapt the mining operations to reduce the negative impacts, while maintaining the interests of stakeholders.

Basalt is a mafic volcanic rock that is widely available in the Earth's surface and often occurs in a variety of ore deposit systems. Traditionally, basalt is used in various ornamentation and construction purposes. However, recently, novel agricultural, environmental and even industrial applications of basalt emerged. When basalt is crushed to a reasonable size (preferably ≤250 µm) and applied to soils in an adequate application rate (5 to 20 t ha-1), it acts as a natural fertilizer. Basalt is predominantly composed of Ca-rich plagioclase, pyroxene and olivine. These rock-forming minerals have a fast weathering rate compared to other silicate minerals. When they come in contact with water and CO2, from the atmosphere, they dissolve releasing a broad spectrum of macronutrients, micronutrients and beneficial elements (e.g., Si, Fe, Ca, Mg, Mn, Na, K, P, S, Ti, V, Cu, Zn, Co & REEs), which are important for plant growth. During this natural enhanced weathering process, an adequate amount of CO2 is sequestered from the atmosphere.

Here, a novel green mining technique is proposed for ore deposits, hosted in or associated with basalt. This technique proposes the separation of the barren or very weakly mineralized basaltic bodies from the remaining solid waste. These bodies should be further crushed and distributed over local farmlands and forests. Crushed basalt will act as a slow release, natural fertilizer, which will rejuvenate weathered soils, boost soil fertility, neutralize soil acidity and enhance plant growth. This will increase the green cover and yield and will reduce the farming costs, which will have positive socio-economic impacts on the local community. More importantly, this green mining technique will reduce the amount of solid mining waste and will sequester a considerable amount of CO2 from the atmosphere, during the enhanced weathering process, which could compensate for the CO2 emitted from the mining operations. Although the process appears straightforward and of high benefit for the environment, the mining sector and the local society, a special monitoring program should be initiated to assess the heavy metal content of the distributed basalt dust to avoid contaminating soils, especially in the case of high application rates (>5 t ha-1).

This ongoing research aims to develop sustainable green mining programs to recycle and reuse the solid mine waste for CO2 sequestration and for the development of natural, slow release, low cost, eco-friendly fertilizers.

How to cite: El Desouky, H.: Role of Basalt in Green Mining, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3176, https://doi.org/10.5194/egusphere-egu22-3176, 2022.

EGU22-3852 | Presentations | ERE4.2

Investigation of custom-made metakaolin-based geopolymers for stone conservation: preliminary results on activation 

Sophie van Roosmale, Tim De Kock, and Johan Blom

Geopolymers are an interesting material because they are inorganic and non-toxic, they are inexpensive because the raw materials are easy to obtain, and they also have high strength and are able to process and adjust. These properties make them an innovative alternative to restoration mortars, which carry out current restoration treatments of stone heritage, but which often cause more damage because they are not fully compatible with the original.

Geopolymers are stone-like materials placed between binders, such as cements and ceramics. Different types of geopolymers exist, depending on the raw materials and the system through which they are activated. In this research we focus on geopolymers with a base of metakaolin. Metakaolin based geopolymers improve the properties of the end product compared to geopolymers based on fly-ash and ground granulated blast furnace slag. For curing the geopolymer, certain requirements have been set that take into account the application of the geopolymer in the restoration sector in the future, like curing by room temperature and ambient relative humidity in less than 48 hours. A set of reactivity tests have been performed to determine the appropriate activator and to optimize their ideal molarity. These tests shows that calcium hydroxide give the best results in forming a matrix of geopolymer.

In the next phase of the research, the compatibility between the geopolymer and porous sedimentary building stones will be investigated. The properties that are important for technical compatibility include: porosity, pore size distribution, capillary water absorption, frost resistance, structure, texture, compressive and bending strength. Samples are made with standardized aggregates of marl flour (porous calcium carbonate flour), limestone flour (non-porous calcium carbonate flour) and relatively pure sand with various grain size distribution to evaluate the compatibility and to investigate the effects on reactivity. It is critical this test phase is carried out with pure products, so that any contamination cannot affect the results. In the following stage it is then possible to experiment with the effect of degraded and contaminated original material as aggregate.

How to cite: van Roosmale, S., De Kock, T., and Blom, J.: Investigation of custom-made metakaolin-based geopolymers for stone conservation: preliminary results on activation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3852, https://doi.org/10.5194/egusphere-egu22-3852, 2022.

EGU22-4272 | Presentations | ERE4.2

Environmental suitability of MSWI fly ash geopolymers: evaluation by leaching tests 

Caterina Caviglia, Enrico Destefanis, Davide Bernasconi, Linda Pastero, Alessandro Pavese, Alberto Viani, Petra Mácová, and Lucie Zárybnická

This work is focused on the possible reutilization of municipal solid waste incinerator (MSWI) fly ash as a metakaolin replacement in the acid-based geopolymer. This type of geopolymer, obtained by the reaction between an aluminosilicate source (metakaolin) and phosphoric acid to form an Al-O-P/Si-O-P matrix (Wang et al, 2019), have displayed better performance than the traditional alkali-silicate geopolymer, in terms of corrosion resistance (Wagh et al, 2011), thermal stability and mechanical strength (Celerier et al, 2019). The replacement of up to 30 % wt has proved to not significantly alter the remarkable performance of the material, obtaining compressive strength values higher than 30 MPa. However, since fly ash contains dangerous substances as chlorides, sulfates, and heavy metals, which must be stabilized, it is important to evaluate the leching stability of the final materials.

Therefore, test cube blocks of 1x1x1 cm size, containing 10, 20 and 30 % wt of previously washed fly ash replacement with respect to metakaolin are prepared, with Al/P molar ratio of 1, liquid-to-solid ratio raging from 0.95-1 and 3 days at 60°C as curing temperature. 

Leaching tests, according to the European standards EN-12457 (2002), using deionized water at a ratio liquid to solid of 10, are applied to geopolymers blocks to evaluate the concentration of salts and heavy metals that usually exceeds the law threshold in the raw fly ash. Leachates are analyzed by ionic chromatography and ICP-MS: the results show that the concentrations of chlorides are under the legislation limits provided for not dangerous waste, as well as sulfates and fluorides; relatively to heavy metals Zn, Pb, Cd exceed the concentrations limits. Further tests and analyses are carried out to evaluate the impact of synthesis parameters on the leaching stability of these materials.

 

Reference

 

  • Wang, Y. Alrefaei, J. Dai. Silico-Aluminophosphate and Alkali-Aluminosilicate Geopolymers: A Comparative Review, Frontiers in Materials, 6 (2019), 106.

 

A.S. Wagh. Phosphate geopolymers, Ceramic Engineering and Science Proceeding, 32, 10 (2011), 91-103.

 

  • Celerier, J. Jouin, A. Gharzouni, V. Mathivet, I. Sobrados, N. Tessier-Doyen, S. Rossignol. Relation between working properties and structural properties from 27Al, 29Si and 31P NMR and XRD of acid-based geopolymers from 25 to 1000 °C, Materials Chemistry and Physics, 228 (2019), 293-302.

How to cite: Caviglia, C., Destefanis, E., Bernasconi, D., Pastero, L., Pavese, A., Viani, A., Mácová, P., and Zárybnická, L.: Environmental suitability of MSWI fly ash geopolymers: evaluation by leaching tests, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4272, https://doi.org/10.5194/egusphere-egu22-4272, 2022.

EGU22-4563 | Presentations | ERE4.2

The use of a natural chabazite-rich zeolitic tuff improved struvite precipitation and nutrient recovery from anaerobically digested wastewater 

Giulio Galamini, Giacomo Ferretti, Valeria Medoro, Negar Eftekhari, Barbara Faccini, and Massimo Coltorti

Both nitrogen (N) and phosphorous (P) are essential for life and their supply sustain the global population growth, thus, the question about “how correctly manage nutrient-rich wastewaters?” is a primary issue for many countries. The storage and the subsequent thoughtless use of these materials, as breeding farm and biogas plants wastewaters, has enormous impacts on the environment, causing eutrophication of water bodies and greenhouse gas emissions. The development of low-cost, low environmental impact and high yield treatment technologies is thus necessary to incentivize the circularity of resources, promoting their reuse and encouraging recycling in agri-food systems.

The recovery of N and P by struvite precipitation (MgNH4PO4·6H2O) is a promising strategy, but these technologies are in general too expensive, energy-demanding, or they alter the treated wastewaters, making them not suitable for agricultural purposes unless additional treatments are carried out.

This work investigates an innovative wastewater treatment processes that foresee the use of a natural chabazite-rich zeolitite (rock containing more than 50 % of zeolite minerals) in combination with struvite chemical precipitation. The adsorption batch (phase 1) is intended to improve the NH4+/Mg2+ and NH4+/PO43- molar ratios, to enhance struvite yield (phase 2) with fewer amounts of reagents required, thus to improve both the efficiency and the cost-effectiveness of struvite production. For the 1st phase, both natural zeolitite (NZT) and the K+-enriched (KZT) zeolitite were tested. KZT was intended to counteract any possible interference for struvite precipitation, which could instead happen with NZT due to the input of Ca2+ ions in solution.

In the 2nd phase (struvite precipitation), 2 different Mg:NH4:PO4 molar ratios were tested, in particular a condition of NH4+ excess (MR1) and a condition with Mg2+ in excess (MR2).

Treatments in which NZT (NZT-S) and KZT (KZT-S) were added prior to struvite precipitation were compared to a conventional struvite precipitation method without the use of zeolitites (CNTR).

NZT-S_MR1 was found to be the most feasible strategy because of the highest NH4+-N removal efficiency, highest struvite precipitation efficiency (less waste of reagents), and less unwanted alterations of the treated wastewater. The precipitate obtained was 89.9 mass % composed of struvite with 3.5 % N, poor in hazardous heavy metals.

The NH4+-N removal efficiency was in order: NZT-S > KZT-S > CNTR, with the highest reduction of 84.8 % recorded by NZT-S_MR1 and the lowest recorded by the CNTR (67.2 and 75.0 % for MR1 and MR2 respectively).

The addition of a “zeolite phase” in struvite precipitation process thus represents i) a valuable method for improving the efficiency of struvite production ii) a method for saving chemical reagents in struvite production and iii) an efficient way to recover and recycling N in agriculture.

How to cite: Galamini, G., Ferretti, G., Medoro, V., Eftekhari, N., Faccini, B., and Coltorti, M.: The use of a natural chabazite-rich zeolitic tuff improved struvite precipitation and nutrient recovery from anaerobically digested wastewater, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4563, https://doi.org/10.5194/egusphere-egu22-4563, 2022.

EGU22-4819 | Presentations | ERE4.2

Analysis of the production of residual vegetable oils from the food and culinary industry in the city of Cuenca (Ecuador) using GIS tools 

Katerine Elizabeth Ponce Ochoa, María Elena Rodrigo-Clavero, and Javier Rodrigo-Ilarri

Current population growth has generated an increase in the food and culinary industry production, which has resulted in an increase in the consumption of vegetable oils on large restaurant chains as well as on small food stalls. This situation justifies the increasing generation of large amounts of residual vegetable oils that lead to serious problems in their purification due to their slow degradation.

This research is focused in the city of Cuenca (Ecuador) where a program for the collection of residual vegetable oils run by the company ETAPA – EP is being developed. It must be taken into account that this program has been implemented for a selected number of large restaurants but does not include other waste production sources, such as small restaurants, food carts and fast-food stalls that are usually quite frequent in the city and do not integrate an adequate management control over this type of residual waste.

This work explores for the first time the possibility of turning residual vegetable oils management into a source of income and job positions while protecting the environment. In order to carry out this study, information about the location of waste generation points and the amount of residual oil has been collected and processed using GIS tools.

How to cite: Ponce Ochoa, K. E., Rodrigo-Clavero, M. E., and Rodrigo-Ilarri, J.: Analysis of the production of residual vegetable oils from the food and culinary industry in the city of Cuenca (Ecuador) using GIS tools, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4819, https://doi.org/10.5194/egusphere-egu22-4819, 2022.

EGU22-4981 | Presentations | ERE4.2

Reuse of deactivated cement-asbestos waste as inorganic filler in elastomers and epoxy resins 

Vergani Fabrizio and the Progetto Dear

Asbestos minerals, namely chrysotile and fibrous amphiboles, have long been used as components in construction materials, as for instance the cement-asbestos (CA) slates used in roofing, exploiting their capability to increase mechanical strength. As well known, asbestos minerals have been recognised toxic and banned almost worldwide. Current remediation approaches include confinement, encapsulation and removal (followed by disposal in controlled landfills). A more attractive solution, strongly recommended by the EC, is detoxification and reuse, in a perspective of circular economy.

In the present contribution we explored the possibility to reuse thermally treated and deactivated CA powder (a mixture of glass and Ca-Mg silicates typical of cement – details in Vergani et al. 2021) as filler in: i) flour-elastomers (FKM type, characterized by high resistance to oil and temperature) and bi-component epoxy resins (bisphenol-A, epichlorohydrine based resins) used in flooring. For each application, different formulations (different proportions of conventional raw materials and deactivated CA powder) have been prepared and tested according to conventional quality test protocols and SEM micro-textural observations.

As regard the reuse in epoxy resin, the inert CA powder was used either as unique inorganic filler (up to 30 wt%) or admixed to conventional ones (barite), in varying proportions (up to 10 wt%). Mechanical tests and SEM observations have shown encouraging results for all formulations, suggesting feasible reuse in this field.

The application of the inert CA powder as filler in fluor-elastomers in substitution of wollastonite (~22 wt%) or barite (~7 and ~14 wt%), has given some controversial results. Although rheological properties such as cure kinetics, viscosity and scorch temperature are comparable to the standard reference samples, some important physical-mechanical properties worsen because of compatibilization and dispersion problems. As demonstrate by SEM observations, the CA powder tends to agglomerate, and similarly to the coarser particles saved from ball-milling – the grain size distribution of the CA powder is tri-modal with peaks at ~35-40, ~4-5 and ~0.7-0.8 µm – separate from the elastomer, adding porosity with detrimental effects on breaking load, elongation at fracture and related M50 and M100 modules.

At the moment, in a perspective to keep the fine fraction low and to reduce the coarse particles, alternative milling procedures, including microwave and ultrasonic treatments and sieving, are evaluated.

Reference: Vergani et al. (2021) J. Mater. Cycles Waste. https://doi.org/10.1007/s10163-021-01320-6

How to cite: Fabrizio, V. and the Progetto Dear: Reuse of deactivated cement-asbestos waste as inorganic filler in elastomers and epoxy resins, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4981, https://doi.org/10.5194/egusphere-egu22-4981, 2022.

EGU22-5607 | Presentations | ERE4.2

Screening dilute sources of rare earth elements for their circular recovery 

Ana Teresa Lima, Gunvor Kirkelund, Freeman Ntuli, and Lisbeth M. Ottosen

Metals, including rare earth elements (REE), are the cornerstone of our current and future low-carbon urban infrastructure. This study looks at different waste resources and contaminated materials present in the urban setting as REE sources. Wastes and other dilute sources such as incineration ashes, sediments, and mine tailings are not only essential sources of REE in achieving a circular, carbon-neutral economy but may be the most realistic one. E-waste, being the most REE concentrated waste, faces serious reservations regarding handling in largescale facilities, and this waste is generally landfilled. After analyzing different residues, coal fly ashes and stormwater retention pond sediments present the most promising ones. While coal fly ashes have the highest critical REE contents from the studied wastes, the sediments collected from a stormwater retention pond showed the highest REE leachability. Critical REE Nd, Dy, and Er can mainly be found in sediments/soils near highways, coal ashes, and bauxite residue. Overall, coal fly ashes contain the highest critical REE contents found in the studied wastes but sediments collected from stormwater water ponds present the highest leachable REE. In fact, up to 100% of total REE found in these sediments are leachable at room temperature low pH. Future REE resource extraction efforts should account for REE speciation in wastes and not only total contents.

How to cite: Lima, A. T., Kirkelund, G., Ntuli, F., and Ottosen, L. M.: Screening dilute sources of rare earth elements for their circular recovery, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5607, https://doi.org/10.5194/egusphere-egu22-5607, 2022.

EGU22-6391 | Presentations | ERE4.2

Circular Economy Rebound: A case-based management guideline 

Pierluigi Zerbino and Davide Aloini

Abstract. The Circular Economy (CE) aims to reduce harmful emissions and soothe the pressure on raw material extraction by slowing, closing, and narrowing material and energy loops (Geissedoerfer et al., 2017). In stark contrast to this objective, CE can be environmentally unsustainable. A prominent reason is the Circular Economy Rebound (CER). CER is a phenomenon that occurs when a CE practice, which reduces per-unit production environmental impacts, causes increased levels of production and consumption that offset the environmental benefits (Zink and Geyer, 2017).
CER can impede CE strategies from achieving the intended benefits (Levanen et al., 2021). Moreover, overlooking it may lead firms to overstate their environmental performance. Nevertheless, CER is a largely unaddressed topic that deserves further empirical attention (Goyal et al., 2021). In particular, little to none has been conceived to cope with it (Salvador et al., 2020). Accordingly, this work aims to respond to the following research question: “What strategies may a firm undertake to manage CER?”.
To answer the research question, an exploratory single case study was developed. The chosen case was a marble import-export Italian firm. The unit of analysis was the CE initiative that allowed the firm to “close the loop” in its Supply Chain. The data were collected through semi-structured interviews and analysis of documentation and archival records concerning production.
The selected firm purchases marble blocks and transforms them into slabs that are sold worldwide. The transformation generates 240 t/year of slats that, before 2018, were disposed of. Since 2018, the firm has been remanufacturing the slats to create upcycled slabs that are similar to mosaics. However, this strategy exhibits massive CER (111.7%) due to the complete lack of displacement between primary and secondary products.
Through the analysis of the evidence, a guideline was developed to manage CER. The guideline presents five actionable insights that may help firms in pursuing their CE addresses through a set of Supply-Chain-wide strategies.

References
Geissdoerfer, M., Savaget, P., Bocken, N.M.P. and Hultink, E.J. (2017), “The Circular Economy – A new sustainability paradigm?”, Journal of Cleaner Production, Vol. 143, pp. 757-768
Goyal, S., Chauhan, S. and Mishra, P. (2021), “Circular economy research: A bibliometric analysis (2000–2019) and future research insights”, Journal of Cleaner Production, Vol. 87.
Levanen, J., Uusitalo, V., Harri, A., Kareinen, E. and Linnanen, L. (2021), “Innovative recycling or extended use? Comparing the global warming potential of different ownership and end-of-life scenarios for textiles”, Environmental Research Letters, Vol. 16, No. 5.
Salvador, R., Barros, M.V., Luz, L.M.D., Piekarski, C.M. and de Francisco, A.C. (2020), “Circular business models: Current aspects that influence implementation and unaddressed subjects”, Journal of Cleaner Production, Vol. 250.
Zink, T. and Geyer, R. (2017), “Circular Economy Rebound”, Journal of Industrial Ecology, Volume 21, No. 3, pp. 593-602.

How to cite: Zerbino, P. and Aloini, D.: Circular Economy Rebound: A case-based management guideline, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6391, https://doi.org/10.5194/egusphere-egu22-6391, 2022.

EGU22-6971 | Presentations | ERE4.2

Gallium and germanium in metallurgical slags: mineralogy and potential recovery 

Vojtech Ettler, Martin Mihaljevic, Radim Jedlicka, Bohdan Kribek, Ben Mapani, Fred Kamona, Rob J. Bowell, and Tomas Hrstka

Gallium (Ga) and germanium (Ge) are technologically essential critical elements. This study focuses on old metallurgical slags generated by processing non-ferrous metallic ores in Tsumeb, northern Namibia, containing interestingly high concentrations of these elements (up to 156 ppm Ga and 441 ppm Ge). Mineralogical investigation indicated that the slags were composed of olivine-, melilite- and spinel-group phases, metal(loid)-rich glass, and sulfide/metallic inclusions. The FEG-EPMA and LA-ICP-MS data confirmed that major carriers of Ga were Zn-Fe-Al spinels (up to 1370 ppm), and Ge was primarily bound in a glassy phase (up to 470 ppm), especially in the case of granulated slags. The abiotic extraction tests, simulating a hydrometallurgical recovery via agitation leaching, were carried out in sulfuric, nitric, and hydrochloric acids (pH = 0.2-0.3, 25 °C and 70 °C, pulp density of 1%) to determine the release of Ga and Ge from slags. Their leaching attained a steady state after 6 hours for granulated slags and 2 hours for finely ground slags. The extractability of both Ga and Ge was slightly higher for the high-temperature trials. The overall recovery was the best for the sulfuric acid extractions and attained 100% and 96% for Ga and Ge, respectively. Our investigation indicates that understanding the specific binding of critical elements is crucial for their potential recovery from slags. This study was supported by the Czech Science Foundation project (GAČR 19-18513S).

How to cite: Ettler, V., Mihaljevic, M., Jedlicka, R., Kribek, B., Mapani, B., Kamona, F., Bowell, R. J., and Hrstka, T.: Gallium and germanium in metallurgical slags: mineralogy and potential recovery, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6971, https://doi.org/10.5194/egusphere-egu22-6971, 2022.

EGU22-7014 | Presentations | ERE4.2

Recycling of thermically treated asbestos-containing material in the production of sanitary-ware vitreous bodies 

Luca Pellegrino, Andrea Bernasconi, Lucia Galimberti, Fabrizio Vergani, Narcisa Mihaela Marian, Cecilia Viti, and Giancarlo Capitani

Asbestos-containing material (ACM) still represents an emergency in Europe because of the related health problems. Based on dedicated legislation, ACM must be managed through several different operations such as: i) confinement, ii) encapsulation and iii) removal (with disposal in controlled landfills). A more attractive alternative to these non-ideal solutions, safer and sustainable, is the transformation of the ACM through thermal, thermo-chemical or thermo-mechanical methods into a non-hazardous secondary raw material. In this contribution, we explore the re-use of ACM thermally treated at 1100 °C in the production of sanitary ware ceramics.

Sanitary-ware vitreous bodies (VB) are generally obtained from mixtures of three fundamental raw materials: i) clay, mostly kaolinite, which provides plasticity to the ceramic mixture; ii) quartz, which acts as filler, forming the skeletal network of the ceramic body; iii) feldspar, a fluxing agent, which promotes the greification of the body and the dissolution of component like quartz upon firing (buller T 1200-1240 °C; Carty & Senapati, 1998).

The product of the thermally treated ACM, i.e. a mixture of non-hazardous Ca-Mg-rich silicates (akermanite, bredigite, merwinite and larnite) and glass, was added to a ceramic mixture as a partial substitute (5 wt%) of feldspar (mixture VBX), and characterized according to a standard protocol before and after firing in the industrial tunnel kiln (buller T 1230°C). The results pointed out a very good greification level of the VBX slip, as corroborated by very low water absorption. These results motivated us to better evaluate the greification behavior of the VBX slip at 6 different buller T by means of gradient kiln. From the mixture VBX, we prepared six samples which were heated at 1140, 1160, 1180, 1200, 1220, and 1240 °C, and characterized the mechanical, mineralogical and microstructural properties. For comparison, the same T steps and analyses were applied to six standard ceramic mixtures (i.e., vitreous China, VC).

XRPD indicates that VBX and VC have very similar mineralogical composition, with glass, quartz, feldspar and mullite as major constituents and minor Fe and Ti oxides. SEM observations suggest that VBX and VC have also similar microstructure, dominated by a glassy matrix embedding numerous 10-60 µm-sized particles of quartz, feldspar and mullite. Overall, thermally treated ACM seems a good candidate to substitute feldspar up to 5 wt% in the production of sanitary ware ceramics. This conclusion is further supported by the fact that VBX and VC display a very similar greification level at T>1200°C.

Carty, W. M., & Senapati, U. (1998). Porcelain—raw materials, processing, phase evolution, and mechanical behavior. Journal of the American Ceramic Society, 81(1), 3-20.

How to cite: Pellegrino, L., Bernasconi, A., Galimberti, L., Vergani, F., Marian, N. M., Viti, C., and Capitani, G.: Recycling of thermically treated asbestos-containing material in the production of sanitary-ware vitreous bodies, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7014, https://doi.org/10.5194/egusphere-egu22-7014, 2022.

EGU22-7741 | Presentations | ERE4.2

Greenhouse gas emissions from worm-compost-biochar combinations from farm to production to fork 

Patrick Cito Namulisa, Maria Heiling, Alfred Grand, Christian Resch, Gerd Dercon, and Rebecca Hood-Nowotny

Studies on worm-composting or vermicomposting, the addition and use of worms to recycle food and other organic wastes into a nutrient-rich product called vermicast, have shown that when used as soil amendment or activator, they have numerous positive effects on soil physico-chemical properties including: soil aeration, water-holding capacity, nutrient supply and they could be valuable peat substitutes in nursery production. Furthermore, vermicompost is an interesting proposition in the circular economy, particularly with food wastes in peri-urban areas. Despite these advantages, some studies have indicated that worm produce potent greenhouse gases (GHG), notably nitrous oxide (N2O). It has been suggested that the addition of biochar (BC) to the systems worm-compost-soils could substantially reduce the N2O emissions. The use of Biochar (BC), a biomass pyrolysis by-product, as soil amendment has been proposed essentially for its vast carbon sequestration potential as a “nature based solution” to combat anthropogenic induced climate change.

In this study, in addition to quantifying the GHG emissions from the entire worm-composting process and assessing the impact of BC addition on the vermicomposting process, particularly the nitrous oxide emissions (N2O), we determined the potential influence of the timing of the BC addition, whether biochar added before (BC-Compost-worms) or after (Compost-BC-worms) in the initial hot composting process had an influence on overall GHG emission; targeting essentially how biochar (BC) reduces the GHG emissions from the wormication process. We followed right through to the crop production stage using spinach as a test crop, to both determine and compare the N2O emissions from conventionally grown and organically produced products in a greenhouse experiment. To fully assess and compare these emissions from compost, compost-worms and biochar (BC) additions, we also added a treatment with equivalent inorganic fertilizer using nitrogen stable isotope (15N) labelling with the aim to see the pathway of the fertilizer, matching the nitrogen uptake with observed emissions.

In all seven treatments were established: compost only, compost worms, BC-Compost worms, Compost-BC worms, equivalent inorganic 15N fertilizer, soil only, and soil only no plants. Using a novel experimental set-up and cavity ring down laser based flow through system for analysis we explored the impacts of treatments on both GHG emissions and plant production. Our central hypothesis is that biochar will reduce N2O emissions from the worm treatments and that, this will lead to greater reductions in worm emissions when BC is added after (Compost-BC-worms) the initial hot composting process than compared to when added before (BC-compost-worms). The results and conclusions of this study will be presented.

How to cite: Namulisa, P. C., Heiling, M., Grand, A., Resch, C., Dercon, G., and Hood-Nowotny, R.: Greenhouse gas emissions from worm-compost-biochar combinations from farm to production to fork, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7741, https://doi.org/10.5194/egusphere-egu22-7741, 2022.

EGU22-9769 | Presentations | ERE4.2

Recycling Etna volcanic ash for the production of ceramic materials 

Cristina Maria Belfiore and Marco Viccaro

The presence of active volcanoes often influences human life both in terms of health impact and socio-economic consequences. Explosive eruptions can release into the atmosphere huge quantities of ashes which then fall to the ground, causing many inconveniences to communities living and working in close proximity to the volcano. A further problem is represented by the high costs that the involved administrations (Civil Protection or Municipalities) of the interested areas must face whenever this material, considered as waste, needs to be collected and disposed of in landfill.

To overcome this problem, it would be suitable to find ‘‘end of waste” alternatives for volcanic ash as raw material in the productive sectors, e.g., in building materials (tiles, bricks, mortars, concretes, etc.). A paradigm shift leading to consider ashes no longer as a waste but a resource.

This contribution deals with an experimental study aimed at assessing the possible re-use of volcanic ash as temper in the manufacture of ceramic tiles. Volcanic ashes recently erupted by Mount Etna volcano in Sicily (Southern Italy), one of the most active basaltic volcanoes in the world, have been here chosen as case study for such a purpose. Ceramic test-tiles were manufactured by mixing volcanic ash with a calcareous clayey raw material, by using specific proportions of clay/temper. In order to assess the quality of the products, the tiles underwent several physical–mechanical tests including: a) water absorption; b) bending resistance; c) impact resistance; d) resistance to deep abrasion; e) thermal shock resistance; f) frost resistance; and g) accelerated aging test by salt crystallization (Belfiore et al. 2020). The obtained results have been then compared with those of a reference product manufactured by using another volcanic material known as azolo (i.e., finely ground basalt) for a long time on the market. Our data demonstrate how basaltic ash recovering through this methodological approach is highly promising in the sector of building materials.

Reference

Belfiore C.M., Amato C., Pezzino A., Viccaro M., 2020. An end of waste alternative for volcanic ash: A resource in the manufacture of ceramic tiles. Construction and Building Materials, 263, 120118, doi: 10.1016/j.conbuildmat.2020.120118

How to cite: Belfiore, C. M. and Viccaro, M.: Recycling Etna volcanic ash for the production of ceramic materials, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9769, https://doi.org/10.5194/egusphere-egu22-9769, 2022.

EGU22-11232 | Presentations | ERE4.2

Structure Transition and Circularity Gap of Sand and Gravel Resources in China 

Zijian Ren, Meng Jiang, Dingjiang Chen, Yadong Yu, Fei Li, Ming Xu, Stefan Bringezu, and Bing Zhu

Aggregates (collectively sand, gravel, and crushed stone) are the most extracted material by weight over the world, and they are important raw materials for buildings and infrastructure. Owing to its rapid development, China is the largest aggregate consumer and producer, accounting for over half of the global aggregate consumption. However, aggregates in China are now facing shortages and low resource circulation. As a long-neglected resource, it is difficult to provide sufficient support for relevant policy-making without a comprehensive quantitative basis. To bridge the knowledge gap, first, we established a systematic material flow and stock accounting framework to map the social metabolism of aggregate resources in China. Then we discussed the results in the global context for international comparison to figure out the circularity gaps of aggregates in China. Our results show during 1978–2018, the inflows of China’s aggregates increased by 13 times (1.3 to 17.3 billion tons), the stocks increased by 15 times (18.3 to 285.5 billion tons), and the outflows, the main component of CDW, increased 9 times (from 445 million tons to 4.4 billion tons). On the supply side, a transition of the primary supply structure is observed. The manufactured aggregates gradually replaced the natural aggregates as the main supply source in the past decade. On the demand side, the demand for aggregates stepped to a peak of around 18.5 billion tons. The infrastructure rather than building becomes the main consumer since 2014. However, the model shows the recycling rate of outflows is less than 5%, indicating a circularity gap compared to the rate that could be as high as 70%–95% in certain advanced economies. The market acceptance, policy supports, and the structures of demolished buildings are the main reasons for the current circularity gap of aggregates. Regarding a large amount of aggregates accumulated in the material stocks, it is expected to see rapid growth of aggregate waste in the near future. It is essential to foster a well-functioned circular system to achieve the sustainable development of the aggregate industry.

How to cite: Ren, Z., Jiang, M., Chen, D., Yu, Y., Li, F., Xu, M., Bringezu, S., and Zhu, B.: Structure Transition and Circularity Gap of Sand and Gravel Resources in China, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11232, https://doi.org/10.5194/egusphere-egu22-11232, 2022.

EGU22-13539 | Presentations | ERE4.2

The RAMSES-4-CE project – developing a smart sensor network for e-waste characterisation 

Margret Fuchs, Andréa de Lima Ribeiro, Elias Arbash, Christian Röder, Nadine Schüler, Kay Dornich, Yang Xiao Sheng, Richard Gloaguen, and Johannes Heitmann

The steeply increasing demand for electronic devices and fast innovation cycles, combined with the recent political and societal orientations towards e-mobility and energy transition leads to vast amounts of e-wastes (i.e. Waste of Electrical and Electronic Equipment – WEEE). Most of the million tons of WEEE generated annually are only partially recycled up to now. This impedes dramatically EU goals towards Circular Economy. In order to improve recycling efficiency and thus minimize our environmental footprint, modern recycling plants need multi-component sensors that can identify complex materials rapidly and accurately. We address this challenge by using a combination of imaging sensors to identify key chemical compounds in material streams. Our main objective is the rapid mapping of the critical compounds in unknown, variable WEEE material streams. Such digital information is then immediately available for an adequate sorting and inherently adapted recycling that will enable Circular Economy. In this context, the RAMSES-4-CE project, which is funded by EIT innovates optical spectroscopy-based multi-sensor systems for the recycling industry. By means of hyperspectral (HSI) reflectance spectroscopy in the near- and mid-infrared range certain alloys, ceramics, and plastics can be identified and classified. Laser-induced fluorescence (LiF) spectroscopy enables the detection of rare earth elements (REEs) and low-reflective black plastics among others. In order to expand the range of WEEE classes which can be identified by our system, we propose to add a rapid, non-destructive and cost-efficient Raman sensor.  

To achieve the required innovation towards an efficient and smart sensor network, we focus on three major aspects: (1) developing a Raman sensor, (2) its integration in an existing LiF-HSI system (EIT inSPECtor project), (3) advanced multi-source data fusion via a rapid machine learning-based data integration. The combination of fast imaging sensors with a precise point validation sensor addresses the need for the identification of shredded recycling materials at high measurement speeds (up to 1 m/s) as well at high spatial resolution (about 2 mm) in industrial applications of sensor-based sorting. In this contribution, we present the RAMSES-4-CE sensor network concept of two integrated line-scan sensors (HSI, LiF) for rapid mapping combined with an adapted Raman point-sensor. The sensor network is mounted on top of a conveyor belt of about 50 cm width and can be adapted for the characterization of minerals/rocks in exploration and mining applications as well. Component identification is based on the comprehensive work on spectral fingerprints for plastics, semiconductors, REE and other critical WEEE components. In addition, we present our concept for a time-efficient data processing workflow to enable sensor communication and accordingly, allow for selected validation analysis to update the mapping results. The temporally and spatially resolved information enables then subsequent decision making in recycling processes. 

 

How to cite: Fuchs, M., de Lima Ribeiro, A., Arbash, E., Röder, C., Schüler, N., Dornich, K., Sheng, Y. X., Gloaguen, R., and Heitmann, J.: The RAMSES-4-CE project – developing a smart sensor network for e-waste characterisation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13539, https://doi.org/10.5194/egusphere-egu22-13539, 2022.

EGU22-13557 | Presentations | ERE4.2 | Highlight

Dredged sediments: A new source of nutrients as a plant-growing substrate 

Laura Ferrans, Frank Schmieder, and William Hogland

Dredging activities are carried out worldwide to increase water levels in harbours and bays or restore the aquatic ecosystem. As a result, a large amount of extracted sediments are produced, and the material is widely disposed of at open seas or landfills. Legal and environmental regulations constrain traditional sediment disposal methods due to their potential contaminant pathways, lack of long-term stability, and limited space capacity. Finding new disposal routes for sediments becomes a challenge. Implementing beneficial uses for dredged material represents a proper way to eliminate sea dumping and embodies adequate disposal, reducing the extraction of raw materials. Around the world, several beneficial uses of sediments have been implemented. Productive and positive uses of dredged material include incorporation in construction, agriculture, land reclamation and habitat restoration, among others.

The recycling of dredged sediments depends on their composition. The material typically contains nutrients, metals and organic compounds, according to the discharges to water bodies since sediments are the final sink of discharged compounds. Sediments with a high organic matter content and nutrients and low pollution concentrations are feasible for soil conditioning purposes. Nutrients are essential for life, and elements such as phosphorous receive high importance since the element is limited on Earth. Additionally, phosphate mines are only located in a few parts of the world, potentially causing shortages due to geopolitics. Hence, investigating new sustainable sources of nutrients is required, and dredged sediments could be employed as an option. This study aims to present dredged material as a plant-growing substrate to cultivate lettuce (L. Sativa), tested under greenhouse conditions. Moreover, another objective was to assess the risk of metal pollution related to vegetable consumption. The case study is in Kalmar, southeast of Sweden. The dredged material comes from Malmfjärden bay. The water body is currently shallow, and its biodiversity is threatened by eutrophication and continuing siltation. Therefore, a dredging project was initiated to recover the bay.

Sediments from the dewatering system of the project were extracted to be employed in the greenhouse experiment. The material presented high content of nutrients and organic matter and medium-low content of metals. The sediments were mixed with compost to improve the physical conditions since they were mainly clay and silt (90%). The selected substrates were (1) 100% compost and (2) 50% sediments - 50% compost. The seeds were pre-germinated and transplanted into pots. The experiment was carried out for 3 months in stable conditions. The obtained lettuces (leaves and roots) were analysed to measure their metal content. The results showed that the plants grew in both substrates, and the harvested lettuce had leaves of a medium length. The metal contents in the vegetables were below critical levels detrimental to human health. The study concluded that the sediments were a potential source of nutrients, using the material as a plant-growing substrate. However, mixing with other organic materials (like compost) is recommended to improve the physical properties of sediments and improve their nutrient distribution and availability.

How to cite: Ferrans, L., Schmieder, F., and Hogland, W.: Dredged sediments: A new source of nutrients as a plant-growing substrate, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13557, https://doi.org/10.5194/egusphere-egu22-13557, 2022.

Bauxite residues (BR) from the Bayer process to produce alumina are highly alkaline and saline, containing high-level toxic elements (such as vanadium (V)), which are soluble in water under the alkaline pH condition. Ecological engineering of the BR can significantly improve physicochemical, mineralogical, and biological conditions, leading to the productive growth of pioneer plants. However, it remains unknown the fate of vanadium in response to the eco-engineering-driven changes of mineralogy, geochemistry, and organic matter decomposition.

The primary distribution of V in the BR-technosols will be characterized in sequential extraction and fractionation. The results of sequential extraction over show that the main vanadium pools in BR-technosols are in the iron oxide and organic matter phases, which provoked an investigation into the controlling mechanisms and specific sorbents, through microstructural and spectroscopic analysis combined with multivariate analysis. The alkaline environment was found to be the main controlling factor leading to elevated bioavailable vanadium in the bauxite residue. Within the iron oxide phase, amorphous iron oxides are expected to play an important role in sorption and therefore the conversion of crystalline iron-bearing minerals to the amorphous phase during weathering will be a direction of concern during long-term rehabilitation. Organic matter under natural soil conditions is an important vanadium sorbent, and additional additions of organic matter did not observe a significant improvement in this study sample, but when combined with P additions, a significant reduction in pH occurred, as did water-soluble vanadium. More investigation needs to be stimulated in terms of the role of P in promoting the addition of organic matter.

The expected results will aid the risk assessment of the eco-engineered BR-technosols and necessary intervention to mitigate the identified risks of V pollution in seepage and surface runoff in the future. 

How to cite: Ren, C., Saha, N., Parry, D., and Huang, L.: Influence of exogenous organic matter and P synergies on the geochemical behavior of vanadium in the rehabilitation of bauxite residues, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-812, https://doi.org/10.5194/egusphere-egu22-812, 2022.

Sulfide-modified nanoscale zerovalent iron (S-nZVI) is attracting a lot of attention due to its ease of production and high reactivity with hexavalent chromium (Cr (VI)). However, until now, the most commonly used is the use of NaS2O4 sulfide nano zero valent iron. The study on the removal of hexavalent chromium from water by nanometer zero-valent iron with calcium sulfide is not comprehensive enough. Herein, the removal of high concentration of hexavalent chromium from wastewater by nanometer zero-valent iron with calcium sulfide and its structure were carefully investigated. Scanning electron microscopy (SEM) with EDS analysis demonstrated that sulfur was incorporated into the zero valent iron core and homogeneously distributed within the nanoparticles. S-nZVI had an optimal Cr (VI) removal capacity of 200mg/L, which was >100% higher than for pristine nZVI. Different molar ratio of polycalcium sulfide and zero-valent iron, initial zero-valent iron addition amount, initial pollutant concentration and initial pH value have different effects on the removal effect. While the S/Fe=0.2, 200mg/L initial Cr (VI) concentration, 2g/L S-nZVI additive amount, pH<5, have the optimum removal rate. Contrast to pristine nZVI, S-nZVI can efficiently sequester high concentration of hexavalent chromium from different contaminated groundwater matrices.

How to cite: Yu, J. and Li, Y.: Removal of High Concentration of Chromium Hexavalent Wastewater From Groundwater by S-NZVI, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1011, https://doi.org/10.5194/egusphere-egu22-1011, 2022.

EGU22-1041 | Presentations | ERE4.3

A novel Zirconium-modified Coal Gasification Coarse Slag for phosphate adsorption 

Baoguo Yang and Yilian Li

The excess phosphate in water leads to eutrophication, and hence finding cost effective adsorbing material for removing phosphorus from water is of great significance. Meanwhile, Coal Gasification Coarse Slag (CGCS) as a general solid waste, poses a potential threat to the environment. To solve these problems, herein, a novel low cost and high-efficiency adsorbing material was synthesized from CGCS by a facile method. The (CGCS)/ZrOCl2⋅8H2O mass ratio of 5:4 (denoted as CGCS-Zr4) was selected from a series of adsorbents with different mass ratios for subsequent sorption researches. The performance for phosphorus removal and related adsorption mechanism were investigated. The results showed CGCS-Zr4 had good adsorption property within a broad pH range. The Langmuir isothermal model, the pseudo-second-order kinetic and intra-particle diffusion model described the experiment data well, indicating that 1) the reaction process was monolayer and chemical adsorption; 2) rate determining step were both boundary layer effect and intraparticle diffusion. The adsorption mechanism of phosphorus on CGCS-Zr3 could be mainly achieved by electrostatic attractions and coordination reactions, forming inner-sphere phosphate complexes. The experiment results suggest that using Coal Gasification Slag (CGS) for removing phosphate could be a promising method in the wastewater treatment and resource utilization of solid waste.

How to cite: Yang, B. and Li, Y.: A novel Zirconium-modified Coal Gasification Coarse Slag for phosphate adsorption, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1041, https://doi.org/10.5194/egusphere-egu22-1041, 2022.

EGU22-1736 | Presentations | ERE4.3

Immobilisation of metal(loid)s in building materials made with mine waste 

Valérie Cappuyns, Lugas Raka Adrianto, and Jillian Helser

In the framework of the H2020 ETN SULTAN (European Training Network for the Remediation and Reprocessing of Sulfidic Mining Waste Sites) project, the release of metal(loid)s from different building materials, in which mining waste (including mine tailings and waste rock) was used as a raw material, was investigated. The waste rock and mine tailings originated from an active Cu-Zn mine and were characterized by a high content of Cu, Zn, Pb, and As. Part of the waste rock was cleaned by flotation before use, while the mine tailings were used without pre-cleaning. 

Bricks, clinkers, cements, and inorganic polymers in which from 14 wt% up to 100 wt% of primary raw materials had been replaced by mine tailings or (cleaned) waste rock, were subjected to various leaching tests: (i) a single batch leaching test (EN 12457-2), (ii) the Toxicity Characteristic Leaching Procedure (TCLP), and (iii) a cascade leaching test (NEN 7349). The influence of the processing of the mine waste, the pH of the leachates, and the mineralogical composition of the building materials on the immobilisation of metal(loid)s were assessed.

Clinkers and cements were the most efficient building materials to immobilise all metal(loid)s, even when uncleaned waste materials were used as a raw material. For the inorganic polymer produced from uncleaned mine waste rock, the leaching of Zn, Pb, Cu, and As was a point of concern, promoted by the alkaline pH of this material. The bricks had a lower release of metal(loid)s  compared to the inorganic polymers, which also showed the importance of an efficient cleaning procedure before using the mine waste as a raw material.

 

How to cite: Cappuyns, V., Adrianto, L. R., and Helser, J.: Immobilisation of metal(loid)s in building materials made with mine waste, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1736, https://doi.org/10.5194/egusphere-egu22-1736, 2022.

EGU22-2020 | Presentations | ERE4.3

Gravity and Magnetic Separation for Recycling of Granite Scraps in the Buddusò Quarrying District (Northern Sardina, Italy) 

Carmela Vaccaro, Antonello Aquilano, Chiara Telloli, and Elena Marrocchino

In recent decades, the recovery of materials and energy from waste materials has received attention, with the aim of finding a sustainable solution to reduce the exploitation of natural resources and reduce the use of landfills, stimulating a growing interest in the reuse of waste. In recent years new digital technologies continuously require rare metals, the abundance of which in the earth's crust is limited, and, for this, they are classified with me as critical raw materials. The Green Deal requirements call for improvements in the treatments for the extraction of raw materials also, and above all, from the gangues and waste materials from mining activities. Quarrying and processing of granite, for example, produce large amounts of waste residues, that besides being a loss of resources, improper disposal of these wastes results in pollution of the soil, water and air around the dumpsites.

This work aims to investigate the magnetic properties of mineral constituents of Buddusò Granites (Northern Sardinia) through the use magnetic separator in conjunction with gravity pre-concentration steps, using a shaking table to concentrate the valuable minerals and eliminate the undesired gangue minerals. These can be preliminary treatments for the possible use of granite scraps from quarries in the granite quarrying district of Buddusò as secondary raw materials. The granite waste samples were initially crushed using a jaw crusher and subsequently sieved to retain the part of the material with a grain size between 0.850 mm and 0.125 mm at a laboratory scale. The material was subjected to a preliminary separation process using a shaking table and obtaining seven subsamples were obtained starting from the initial one. Gravity separation was carried out in this work to discard the light gangues and obtain heavy mineral concentrate. The concentration process using shaking table is controlled by a number of operating variables, such as feed rate, wash water, feed pulp density, deck slope, amplitude particle size range, and as well as particle shape and the shape of the deck, play an important part in table separations. The sub-samples obtained by gravimetric separation were first placed to dry in an oven at 105 ° C for 24 hours and then has been treated by magnetic separation, which has been carried out in this work to separate paramagnetic (weakly magnetic) materials from non-magnetic materials. Each subsample, after being quartered, was then subjected to magnetic separation using the Frantz instrument, to separate the magnetically susceptible minerals from the others. This operation was first performed at low magnetic field strength to separate minerals with lower susceptibility and subsequently performed at high magnetic field strength to separate minerals with higher susceptibility.

According to Raslan et al., 2021, the preliminary results obtained, it is clear that the combination of gravity pre-concentration, using a shaking table, combined with magnetic separation, using dry high-intensity magnetic separator, is able to successfully concentrate heavy, paramagnetic and diamagnetic minerals phases, all of them with high mining potential.

How to cite: Vaccaro, C., Aquilano, A., Telloli, C., and Marrocchino, E.: Gravity and Magnetic Separation for Recycling of Granite Scraps in the Buddusò Quarrying District (Northern Sardina, Italy), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2020, https://doi.org/10.5194/egusphere-egu22-2020, 2022.

EGU22-3156 | Presentations | ERE4.3

Quartz, feldspars and REE from gneiss waste materials: an example from the VCO province (Piedmont, northern Italy) 

Alessandro Cavallo and Giovanna Antonella Dino

Raw materials and critical raw materials (e.g. REE, PGM) supply is a matter of concern and a global challenge to face in a sustainable way: they can be exploited from ore deposits and be recovered from landfills (both urban and industrial), extractive waste facilities, and/or from waste streams. In a modern perspective of circular economy, the rational exploitation of mineral resources is essential, as well as a recovery and valorization of extractive and processing waste. In this research we present preliminary results related to the recovery of Beola and Serizzo extractive and processing waste, two commercial varieties of gneiss (dimension stone), quarried in Piedmont (northern Italy) and exported worldwide. Both Beola and Serizzo are varieties of orthogneiss, the former being very foliated and suitable for splitting, the latter more massive and used as granite for flooring and cladding. The percentage of extractive waste from quarry sites represents about the 60% of the total exploited material: it is possible to estimate an amount of about 110,880 t/y. Another important waste, whose management is very challenging, is represented by residual sludge (EWC 010413): sludge production is estimated in about 17,700 t/y. A critical point is represented by the regulatory framework of waste materials, with a view to their possible recovery. The relatively monotonic mineralogical composition of the gneisses consists of quartz, feldspars (oligoclase and microcline), and fair amounts of micas (muscovite and biotite). Typical accessory minerals are allanite (an epidote variety rich in REE), chlorite, and zircon. If from a mineralogical point of view there is substantial equality between Beola and Serizzo, the main differences lie in grain size and texture (finer grain and mylonitic microstructure for Beola). In the same mining district also granites are extracted, whose waste, after a series of treatments to remove ferromagnetic minerals (mainly biotite), are successfully reused in the ceramic sector (quartz – feldspars mix). For these reasons, also Beola and Serizzo could also have similar applications, if they undergo suitable mineral processing.  After extensive sampling and a robust mineralogical (OM and XRD), chemical (XRF and ICP-MS) and mineral chemistry (SEM-EDS and WDS) database, we have a complete picture of the characteristics of the waste materials from the different quarries. The main criticalities for the recovery of quartz and feldspars are represented by the grain size (especially for Beola varieties) and the relative abundance of phyllosilicates, which is higher than for granites. However, some varieties lend themselves much more than others to possible recovery, both for reasons of grain size and for the lower amount of mica. All varieties of gneiss contain fair amounts of allanite: this is a potential ore mineral for REE. One of the most easily processed waste materials for allanite extraction and concentration is sawing sludge: with relatively simple separation processes it would be possible to concentrate the heavy fraction, which also includes monazite (another important REE ore mineral). The efficient recovery of quarrying waste could therefore contribute to both the industrial minerals (quartz and feldspars) and the ore minerals sectors (REE).

How to cite: Cavallo, A. and Dino, G. A.: Quartz, feldspars and REE from gneiss waste materials: an example from the VCO province (Piedmont, northern Italy), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3156, https://doi.org/10.5194/egusphere-egu22-3156, 2022.

EGU22-3996 | Presentations | ERE4.3

Geochemical analysis of microbiologically treated red mud 

Hana Fajković, Laura Huljek, Ivana Vrkić, Tomislav Ivanković, Željka Fiket, Suzana Gotovac Atlagić, Sunčica Sukur, and Nenad Tomašić

Historical disposal sites of red mud can be found all around Europe, most notably at Sardinia, in Hungary, or at many locations in East-Southeast Europe. Red mud contains dominantly iron, aluminum, and silicon oxides, with races of various metals and compounds that can still be reprocessed if appropriate methods are applied. Some of the promising methods include microorganisms, and in particular bacteria.

The main objective of the study was to determine whether prolonged bacterial activity changes the geochemistry of the red mud. The bacteria for the experiment were isolated through several selective steps from activated sludge of wastewater treatment plant and red mud from three different locations: Dobro Selo and Zvornik (Bosnia and Herzegovina), and Almásfüzitő (Hungary).

After successful isolation, the bacteria were applied to the homogenized red mud samples, with nutrient media and water added in different combinations and ratios. The experiment lasted for 6 months after the bacteria were first applied to the red mud samples. During this period, geochemical analyses of the red mud were carried out twice, after 4 weeks and after 24 weeks, while the analysis of bacterial survival and quantity in the red mud samples were carried after 4, 8, and 24 weeks. The goal of geochemical analyses was to determine whether the bacteria caused changes in the concentrations of the elements of interest in the red mud when used as cultivating substrate and whether the elements of interest became more available to the bacteria due to their growth and adaptation to the red mud.

Prior to geochemical analysis, subsamples were heated at 100°C for 60 minutes to induce bacteriolysis and filtered twice with MiliQ water (red band filter paper). The eluates were stored in plastic cuvettes and kept in a dark place at 4°C until analysis (HR-ICP-MS). The filter papers containing the treated red mud were dried, sealed, and stored for further geochemical analysis of total major and trace element concentrations by ICP-MS and mineralogical (XRPD) analyses. Detailed results of the geochemical and mineralogical analyses are pending.

This work has been supported by EIT Raw Materials project RIS-RESTORE, project number 19269.

How to cite: Fajković, H., Huljek, L., Vrkić, I., Ivanković, T., Fiket, Ž., Gotovac Atlagić, S., Sukur, S., and Tomašić, N.: Geochemical analysis of microbiologically treated red mud, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3996, https://doi.org/10.5194/egusphere-egu22-3996, 2022.

EGU22-4187 | Presentations | ERE4.3

Eco-sustainable solutions to transform quarry waste of granite rocks into resources for the ceramic and glass industry. 

Aida Maria Conte, Daniela Guglietta, Cristina Perinelli, Elena Marrocchino, and Giovanni Soro

Raw materials are essential for the sustainable development of modern societies. Access to and cost-effectiveness of mineral raw materials are critical to the smooth functioning of the EU economy. The growing demand for raw materials raises increasing concerns about mineral resources. Feldspars along with quartz, the main components of granitoid rocks, are widely used in ceramic and glass industry. The need to meet the demands of the ceramic industry has stimulated research and development of new ceramic flows in granite complexes.

Italy is the world’s second-largest feldspar producer (22% of total) and the world biggest importer (22% of global world trades) (European Commission). Since the strong demand is rapidly depleting the proven reserves in EU Member States, the EU ceramics sector is increasingly dependent on feldspar imports from Turkey. Thus, it is necessary to find additional sources of feldspar or to further increase inter-continental transport. At present, Buddusò-Alà dei Sardi (Sardinia-Italy) is the most important granite production area in Italy. However, granite mining activities cause serious environmental problems. Feldspar production and trade generate large amounts of pollutant and greenhouse gas emissions, due either to the energy consumption of mining activities or the transport of the finished product from the exporting countries. The areas where quarries are active suffer from landscape degradation, due to incomplete compliance or non-compliance with quarry recovery plans, considering that opening new quarries is cheaper than moving large amounts of waste. Finally, granite mining accounts for huge amounts of soil consumption, as it requires large areas in which the quarry waste accumulates.

The LIFE REGS II project (LIFE19 ENV/IT/000373 LIFE REGS II) aims at demonstrating an innovative and economically-viable extraction technology to produce feldspars, of the same quality to those obtained from virgin raw material, using granite scraps. This will reduce demand for feldspar from environmentally-damaging granite mining operations as well as to minimize the soil consumption and to boost the awareness about the importance of recycling granite scraps.

To this respect, samples of the granite scraps accumulated in 18 landfills located in the Buddusò-Alà dei Sardi granite quarries have been analyzed for their mineral texture and composition. Modal variability of the main mineral constituents (quartz+plagioclase±potassium-feldspar+biotite/chlorite) allowed to distinguish three main groups characterized by different ratios of feldspars/mafic phases with the exception of samples from a specific landfill that display an increase in the plagioclase at the expense of potassium-feldspar+quartz along with an increase in epidote at the expense of biotite/chlorite.

Texturally potassium-feldspar occasionally occurs as microcline perthite while plagioclase is always affected by extensive alteration resulting in a variety of textural intergrowths of neoformed minerals. Such features are reflected in the inter/intra-crystalline compositional variations in terms of feldspar end-members and in the type of the alteration products. This provides the elements for a first estimate of the technological properties of felsdpars, allowing to recognize the material stored in the 18 landfills qualitatively better for commercial purpose, and to experimentally identify the most effective methods of physical treatments to enrich and extract feldspars useful for industrial uses.

How to cite: Conte, A. M., Guglietta, D., Perinelli, C., Marrocchino, E., and Soro, G.: Eco-sustainable solutions to transform quarry waste of granite rocks into resources for the ceramic and glass industry., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4187, https://doi.org/10.5194/egusphere-egu22-4187, 2022.

EGU22-5091 | Presentations | ERE4.3

Diagnostic process of an ancient colonnade using non-invasive volume visualization multi techniques 

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

The diagnostic process on the cultural heritage by non-invasive multi techniques generates multiple volumes of different data sets. Such volumes can be applied to a whole range of problems from diagnostics of the building stone materials to their in-time monitoring for maintenance and conservation. The results of the diagnostic process in multimodal data sets can be rendered effective by comparing multiple volumes at the same time and over time since the safety of monumental structures requires periodic monitoring. As already shown in recent works that focused on the integration of heterogeneous data from complementary techniques, the use of a single technique is generally insufficient to obtain a reliable diagnostic process.

The multi-technique high resolution 3D models described in this paper was aimed to investigate the conservation state of a precious carbonate colonnade in the ancient church of Saints Lorenzo and Pancrazio, dating to about the second half of the thirteenth century and located in the old town of Cagliari (Italy). The diagnostics of the carbonate colonnade was made by 3D non-invasive multi-techniques, i.e. Terrestrial Laser Scanner (TLS), close range photogrammetry (CRP) and ultrasonic tomography supported by petrographic investigations. To obtain a natural colour texturized 3D model of the columns with calibrated scale and coordinates both the TLS and CRP techniques were applied. The geometrical anomaly and reflectivity maps derived from the data of the TLS-CRP survey show presence of some anomalies worthy of attention. The 3D reconstruction with previous techniques was the essential base for the planning and execution of the 3D ultrasonic tomography that played an important role in detecting internal defects and voids and flaws within the materials by analysing the propagation of ultrasonic waves.

The results of the non-invasive diagnostic techniques on the building carbonate materials of the ancient colonnade were supported by thin section and mercury intrusion porosimetry (MIP) analyses in order to study their porosity and other textural characteristics such as the grains-matrix or grains-cement relationships, the bioclasts packing, the pore network and other petrophysical parameters (i.e. permeability and tortuosity). Knowledge of these characteristics is key to understanding the different susceptibility of the building carbonate materials to degradation and recognizing any forms of degradation while providing fundamental support to the interpretation of the geophysical data.

 

Acknowledgements

This work was supported by Regione Autonoma della Sardegna (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.: Diagnostic process of an ancient colonnade using non-invasive volume visualization multi techniques, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5091, https://doi.org/10.5194/egusphere-egu22-5091, 2022.

EGU22-5522 | Presentations | ERE4.3

Analysis of support media in packaged bioreactors for landfill leachate treatment systems 

Zully Gómez, Johanna Solano, David Orjuela, María Rodrigo, and Javier Rodrigo

One of the primary environmental problems connected to the growth of cities is the proportional increase of solid waste production and the corresponding leachate generation in the final disposal sites. A research line on the definition of technical systems that facilitate the proper treatment of these leachates to minimize groundwater, surface water, air and soil pollution is currently being developed.

One of the leachate-treatment alternatives is installing biofilm anaerobic biological reactors, in which microorganisms take charge of degrading organic matter while minimizing the leachate pollutant load. Optimal conditions are sought to develop this technology in order to achieve the highest bioreactor efficiency. Variables such as pH, temperature, retention time and the support media where the biofilm will be formed must be considered, in addition to its design and the material use to make it.

Therefore, the support media is one of the most important factors in anaerobic biofilm reactors design, given its function of creating the surface where the microorganisms adhere to form the biofilm. A proper design of this packing facilitates having a greater surface area per unit volume, thus increasing contact with the microorganisms, which is expected to increase the removal rate. Taking this into account, this study analyzes the types of materials currently used for packaging, along with their efficiency in biofilm reactors for first-stage leachate treatment. The evaluation is made using a specific polymeric material composed of polyethylene and expanded polystyrene waste as support media for bioreactors

How to cite: Gómez, Z., Solano, J., Orjuela, D., Rodrigo, M., and Rodrigo, J.: Analysis of support media in packaged bioreactors for landfill leachate treatment systems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5522, https://doi.org/10.5194/egusphere-egu22-5522, 2022.

EGU22-5667 | Presentations | ERE4.3

The legacy of hard coal mining in Germany: hydrochemistry and stable isotopes of mine waters 

Oliver Weisser and Harald Strauss

           Underground hard coal mining occurred in Germany over several centuries in the Ruhrgebiet in Northrhine-Westphalia and ceased in 2018. Nineteen mine waters draining historic and (sub)recent mines were studied in respect to their hydrochemistry and selected stable isotopes (H, O, C, S) in order to identify prevailing processes that determine their chemical composition.

All mine waters show near neutral pH values. Electrical conductivity displays a wide range with values between 370 and 1690 μS/cm (average value of 700 μS/cm). Major ions are in decreasing importance: dissolved inorganic carbon, calcium, sulfate, magnesium, sodium and chloride.

Sulfate concentrations range from 27 to 363 mg/L, showing a positive correlation with electrical conductivity. Sulfate sulfur and oxygen isotopes display some variability between -4.9 and +20.4 ‰ (average value of +4.5 ‰) and between +0.7 and +12.7 ‰ (average value of +4.5 ‰), respectively. Most isotope values suggest that sulfate derived from pyrite oxidation and/or the oxidation of organo-sulfur compounds in the coal. In contrast, the very positive sulfur and oxygen isotopes could indicate dissolution of sulfate minerals.

Apart from sulfate, dissolved inorganic carbon (DIC) is a major ion with concentrations ranging from 60 to 600 mg/L (average value of 249 mg/L). The carbon isotopic composition of DIC is somewhat variable with values between -19.3 and -4.5 ‰. Samples center around an average value of -11,40 ‰, suggesting the dissolution of carbonate minerals through carbonic acid.

In summary hydrochemical and stable isotope data from these mine waters suggest water-rock interaction as the main compositional driver, specifically carbonate dissolution, pyrite oxidation and sulfate dissolution.

How to cite: Weisser, O. and Strauss, H.: The legacy of hard coal mining in Germany: hydrochemistry and stable isotopes of mine waters, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5667, https://doi.org/10.5194/egusphere-egu22-5667, 2022.

EGU22-6229 | Presentations | ERE4.3

Analysis of methodologies to evaluate the environmental impacts of solid waste management in the city of Bogotá 

Ana Paola Becerra Quiroz, Johanna Karina Solano Meza, Javier Rodrigo Ilarri, and María Elena Rodrigo Clavero

Solid waste management produced in megacities is usually being transformed under a linear treatment scheme which considers the circular economy model guidelines (waste reduction, reuse and recycling). The comprehensive solid waste management plan (PGIRS 2020) proposed for the city of Bogotá (Colombia) implements this circular economy approach through different strategies, such as increasing the separation levels at the source, optimizing collection and recycling, including waste as raw materials in production processes and designing technological alternatives different from landfills for the use and treatment of solid waste. Under this new vision, the design of waste management systems must consider those environmental impacts generated throughout the life cycle of waste while integrating ways to address these impacts in comprehensive waste management plans. Furthermore, health and environmental impacts that will result from new forms of waste use or mismanagement must be considered, including the mitigation of climate change effects by diverting waste that would potentially go to a landfill. Therefore, the methodologies adopted to evaluate environmental impacts must be aligned with these new trends while being capable of providing the required and appropriate results for decision-making to achieve established goals.

This work shows the methodologies used to evaluate the environmental impacts generated by solid waste in Bogotá. These methodologies have generally been qualitative so far: checklists, double-entry matrices, indicators and problem trees. They have been selected based on the availability of information, ease of calculation and the physical and technical availability of infrastructures. While different phases of solid waste management may require different methodologies, progress must be made in using more precise methods to reduce uncertainty in the evaluation and become more effective decision-making tools. One of these tools is the Life Cycle Analysis methodology (LCA). LCA provides an opportunity to make progress in including the circular economy approach in the comprehensive solid waste management of the city of Bogotá.

How to cite: Becerra Quiroz, A. P., Solano Meza, J. K., Rodrigo Ilarri, J., and Rodrigo Clavero, M. E.: Analysis of methodologies to evaluate the environmental impacts of solid waste management in the city of Bogotá, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6229, https://doi.org/10.5194/egusphere-egu22-6229, 2022.

EGU22-6887 | Presentations | ERE4.3

Radioactivity in building materials 

Chiara Telloli, Stefano Salvi, Antonietta Rizzo, Fabio Taddei, Alice De Maria, Elena Marrocchino, and Carmela Vaccaro

All building materials have a small but not negligible amount of natural radioactivity; since they come from the earth’s crust, this radioactivity is due to the radioactive families of Uranium (U-238), Thorium (Th-232), and Potassium (K-40), in varying concentrations depending on the type and origin of the original rocks.

Some granites and some tuffs can sometimes record significant concentrations of radioisotopes, while in marbles and carbonate stones radioactivity is rarely present unless they are settled in lagoon environments (i.e., Lecce, Italy limestones). Also building products fabricated with naturally occurring radioactive materials (NORM) can exhibit residual radioactivity, such as in various types of sand, ceramics, or cements.

The radioactive content in the materials used to build is therefore of a certain importance because it can significantly affect the annual effective dose equivalent absorbed due to the long residence time of people inside the buildings.

In Italy the reference regulatory device in the field of work activities involving the presence of natural sources is Legislative Decree 230/95 (including subsequent amendments and additions), while the radioactive content of construction materials is regulated by the Legislative Decree 101/2020.

In order to avoid excessive alarms or, on the contrary, to underestimate the problem, a cognitive investigation was carried out on the radioactivity content in ornamental and structural building materials, in order to possibly identify critical radioactivity concentration. The natural stones analyzed are granite rocks sampled in Sardinia (Ornamental Stones District of Gallura).

The analyses were done in the ENEA’s Environmental Traceability and Radiometry Laboratory specialized in low and very low activity concentration of radioisotopes in the environment. The gamma spectrometry analyses were carried out on the samples reduced to grains, to which, following the EC guidelines, the criteria on the criticality of the materials were applied, calculating three parameters: the activity concentration index (I), the gamma absorbed dose rate (Da) and the annual effective dose (He). The results indicate low concentrations of Uranium and Thorium and therefore compliance with the legislation limits concerning the radio-exposure from minerals, so that they can be used for ornamental purpose in buildings.

How to cite: Telloli, C., Salvi, S., Rizzo, A., Taddei, F., De Maria, A., Marrocchino, E., and Vaccaro, C.: Radioactivity in building materials, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6887, https://doi.org/10.5194/egusphere-egu22-6887, 2022.

EGU22-6913 | Presentations | ERE4.3

Relationship between structure and hydration process in heat-activated serpentine-group minerals (antigorite, chrysotile, and lizardite) 

Tatiana Ivanova, Marina Slukovskaya, and Irina Kremenetskaya

Metal ore mining and beneficiation led to the formation of mine waters and artificial effluents with high metal concentrations, which need cleaning to prevent vertical and lateral metal propagation in the environment. Metal precipitation in the form of hydroxides is the most common method of wastewater purification with high metal concentrations. Serpentines are common in the Earth’s crust and often are by-products of overburden and enclosing rocks. Unlimited reserves of serpentines have stimulated the search for new technology for processing these raw materials. Serpentine structure and properties allow the production of materials used in environmental management. Serpentines heat treatment increases the ability to neutralize acids and precipitate metals from water solutions. The ability of heat-activated serpentines to form a binder through water mixing allows producing granular material. It can be used as an alkaline reagent in a bulk filter to purify highly concentrated solutions with the possibility of separate precipitation of metals.

The influence of the type of serpentine mineral (antigorite, chrysotile, and lizardite) on the hydration of thermally activated materials and the formation of magnesium silicate binder was studied. The serpentine samples were studied using X-ray diffraction analysis, differential scanning calorimetry, and surface texture analysis. The hydration of heat-activated serpentines through their interaction with water vapor and the strength characteristics of the resulting binder agents were investigated. The results show an essential role of serpentine structure in destroying mineral crystal lattices during heat treatment. The lower the activation energy of dehydroxylation, the higher the transformation of serpentines into the active metastable phase. It was found that thermo-antigorite does not sorb water, in contrast to thermally activated chrysotile and lizardite. The acid-neutralizing ability of latter minerals significantly differed with the higher values for thermo-chrysotile. The weight loss of hydrated samples at the temperature of 350-600℃ decreased in the same sequence – from chrysotile to antigorite. Therefore, this characteristic could be considered an indirect indicator of the total content and precursor of binder formed during the thermo-serpentine hydration.

In contrast, the strength of the samples based on heat-activated serpentines decreased in the row chrysotile–antigorite–lizardite. The structural features of chrysotile determined the greatest strength of serpentine binder samples compared with antigorite and lizardite. Lizardite acid-neutralizing ability (activity) was noticeably higher than antigorite, but its strength was lower due to the layered mineral structure and the presence of impurities reducing the strength of the resulting material.

Thus, the structural features of serpentines played a crucial role in the mineral hydration and, as a result, in selecting a material for producing a granular magnesium silicate reagent. Chrysotile is a promising mineral for obtaining granular materials, whereas lizardite is advisable to use in fractionated powders. Antigorite differs from the other two serpentines because it has a less acid-neutralizing ability and can be used for magnesia and silicate products.

The work was supported by the Russian Science Foundation project #21-77-10111.

How to cite: Ivanova, T., Slukovskaya, M., and Kremenetskaya, I.: Relationship between structure and hydration process in heat-activated serpentine-group minerals (antigorite, chrysotile, and lizardite), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6913, https://doi.org/10.5194/egusphere-egu22-6913, 2022.

EGU22-7488 | Presentations | ERE4.3

Using blast furnace slag as an alkaline agent in remediating acid mine drainage from the Iberian Pyrite Belt and removal efficiencies for Rare Earth Elements 

Dileesha Jayahansani Kotte Hewa, Delphine Durce, Sonia Salah, and Erik Smolders

Blast Furnace Slag (BFS) is a waste product generated during smelting of iron ore in a blast furnace. It is composed of, among other oxides, CaO and MgO due to which BFS is capable of generating alkalinity above pH 8 thus has a high neutralizing potential. This characteristic feature makes BFS a potential remediation agent for acid mine drainage (AMD) generated from abandoned mines. Passive treatment systems (PTS) of AMD generally make use of alkaline materials such as limestone to neutralize the acidity and to precipitate metals. Moreover, the use of BFS as an alkaline material in remediating AMD can be considered as a way of achieving industrial symbiosis and hence sustainability. However, researches conducted to investigate suitability of BFS in remediating highly acid (pH≤3) and metal rich AMDs are absent in the literature despite the promising properties of BFS. In addition, Rare Earth Elements (REE), which are considered as technology-critical elements, are present in higher concentrations in such AMDs than those found in natural water bodies. Therefore, in addition to the AMD remediation, it would be worth to investigate the effectiveness of BFS to also retain REE in PTS. This study aimed at investigating the efficiency of BFS in remediating highly acidic and metal rich AMD generated at the Iberian Pyrite Belt (IPB) and especially in retaining REE. Three AMD samples having different chemical properties were collected from the Tharsis mining area situated in the IPB. Various amounts of BFS were added to aliquots of AMD samples in  such a way to collect solids and solution per each pH unit until neutralization (from pH 3-7). Suspensions were then kept in an orbital shaker for a week to ensure proper contact between the added BFS and AMD solution. Afterwards, the suspensions were centrifuged at 4000 rcf for 5 min to separate the supernatants from the precipitated solids and BFS. The supernatants were then analyzed by ICP-MS and the removal efficiencies for Al, Fe, trace metals and REE were calculated. BFS showed high removal efficiency for Al (97.8±2.1%), Fe (98.8±1.2%), Zn (93.2±2.7%), Cu (99.7±0.3%), Mn (92.2±0.1%), As (99.8±0.2%), Cr (98.2±1.5%), Cd (99.6±0.7%) and REE (98±0.8%) at pH 7. This result shows that BFS is also suitable to be used as an alkaline agent in treating highly acidic and metal rich AMDs and in retaining REE. Precipitated solids during alkalinization of AMD with BFS will also be characterized by XRD, SEM/EDX and LA-ICP-MS to identify the nature of the precipitated solids and the association of REE with the mineral phases contained in the precipitated solids. The fate of toxic metals and REE during alkalinization will be modeled based on the results from solid and solution characterization It is thereby intended to reach a better understanding of the AMD remediation and REE retention mechanisms using BFS as alkaline material in passive AMD remediation.

Keywords: Blast furnace slag, Acid mine drainage remediation, Passive treatment systems, Rare Earth Elements

How to cite: Kotte Hewa, D. J., Durce, D., Salah, S., and Smolders, E.: Using blast furnace slag as an alkaline agent in remediating acid mine drainage from the Iberian Pyrite Belt and removal efficiencies for Rare Earth Elements, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7488, https://doi.org/10.5194/egusphere-egu22-7488, 2022.

The mining and minerals sector faces a dilemma: the transition away from hydrocarbons and race to net-zero requires enormous quantities of mineral resources for low-carbon technologies. However, mining and processing can be hugely energy-intensive and sometimes environmentally harmful, thus there is a need for novel solutions in extraction and processing. Gold ore processing in particular often features cyanide, which is highly toxic and has a large carbon footprint [1], and the often low Au concentrations can result in relatively large volumes of waste rock.

In addition, gold deposits are often also enriched in other metals, and the Björkdal mine produces gold concentrates and tailings that also contain Te, Bi and W. Initial data indicates a high degree of liberation for bismuth-tellurides which is promising for extraction. Currently, there is little incentive and few options by which to process and extract these additional metals for Mandalay Resources, the mine operator [2]. Developing a way in which these metals could be recovered rather than sent to tailings would be ideal for meeting some of the demand for these metals, without opening any new mines.

Deep Eutectic Solvents (DES), developed at the University of Leicester, are a promising advancement for both gold and by-product extraction [3][4]. DES are eutectic mixtures of an organic salt and a hydrogen-bond donor, which are powerful solvents and liquid at room temperature. The components are cheap, readily available and environmentally-benign compounds, such as choline chloride (Vitamin B4) and urea, and can be recycled and reused. Previous work on DES has demonstrated rapid leaching of Au, Ag, Sb, Te and other metals [1], including success with dissolution of tellurides and bismuth tellurides [5].

This project aims to understand the flows of Te, Bi and W through the Björkdal processing plant, and mineralogically characterise tailings and concentrates. This will be used to test the feasibility and impacts of inserting DES leaching stages, and/or altering the processing procedure or reprocessing tailings, in order to maximise by-product recovery in an environmentally-friendly and low energy process.

References:

[1] Norgate T and Haque N (2012) J Clean Prod 29-30:53-63

[2] Jenkin G et al. (2019) 15th SGA Biennial Meeting 4:1512-1515

[3] Abbott A et al. (2004) J Am Chem Soc 126 (29):9142-9147

[4] Smith E et al. (2014) Chem Rev 224 (21):11060-11082

[5] Jenkin G et al. (2016) Min Eng 87:18-24

How to cite: Tritton, L., Jenkin, G., and Smith, D.: Recovery of Te, Bi and W from mine tailings and concentrates, using environmentally-benign Deep Eutectic Solvents at Björkdal Gold Mine, Sweden, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8697, https://doi.org/10.5194/egusphere-egu22-8697, 2022.

EGU22-8747 | Presentations | ERE4.3

Sustainable Raw Material supply: towards a more “domestic” approach 

Giovanna Antonella Dino and Alessandro Cavallo

Mines have been (and still are) fundamental for the economic and social development of Countries: indeed, mining exploitation is aimed to meet the demand for natural resources to improve the life quality of population. Raw Materials (RM), including the Critical ones (CRM), are essential for the sustainable functioning of modern societies; they are used in several clean and low carbon technologies (batteries for electric vehicles, turbines for wind energy, solar panels, etc.), as well as employed in the electronic industry (capacitors, electronic devices, etc.). Furthermore, as for clean and low carbon technologies, the demand for CRM is dependent on which wind, solar, and battery technologies will become dominant in the marketplace. Indeed, the acceleration in deployment of the key low carbon technologies has real implications for the commodities market; thus, not only REE but also aluminum, copper, silver, iron, lead, and others all stand to potentially benefit from a strong shift to low carbon technologies. All literature examining material and metals implications for supplying clean technologies strongly agrees that building these technologies will result in considerably more material-intensive demand than would traditional fossil fuel mechanisms.

The availability of CRM/RM is increasingly under pressure, and the criticality of the processing infrastructure and the recovering of these elements from various resources, leads the EU to be dependent on their imports, often from non-EU countries, which have been always affected by: fluctuating policies of the market, potential conflicts in the areas interested by their exploitation, higher environmental impacts connected to their exploitation, processing and waste management. China is the biggest producer of the 30 CRM for the EU; other countries have dominant supplies of specific CRM, such as USA (Beryllium), Brazil (Niobium), Chile (Lithium), South Africa (Iridium, Platinum, Rhodium, Ruthenium), Kazakhstan (Phosphorous), Guinea (Bauxite), DRC (Cobalt).

There is still a high potential for RM/CRM available in Europe, but their exploration and extraction have faced a strong competition due to highly regulated environmental protection and different land uses. Several studies show that in many regions massive amounts of strategically important materials, such as metals, have been accumulated in landfills and extractive waste facilities. EU legislation aims to reduce the amount of wastes disposed in waste facilities and landfills and to foster the recovery and recycling of waste. The objective set by the measures of Circular Economy packages is not to allow any more landfills by 2050. Contemporary, EU policies intend to boost the domestic exploitation, which need to be faced in a sustainable way (also applying new financial instruments for companies, such as the “Sustainable Finance”). Thus, wastes (including extractive waste) have to be intended as resources and landfills (including extractive waste facilities) have to be considered as “raw material reserve” to be exploited. To face the challenges connected to sustainable RM/CRM supply, an interdisciplinary approach and a wider knowledge about waste characteristics, volumes, localization, suggested processing activities, main impacts on environment and human health are needed.

 

How to cite: Dino, G. A. and Cavallo, A.: Sustainable Raw Material supply: towards a more “domestic” approach, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8747, https://doi.org/10.5194/egusphere-egu22-8747, 2022.

EGU22-10374 | Presentations | ERE4.3

Research on the heavy sands of the floodplain of the River Zambezi (Republic of Mozambique). Mining potential and economic evaluation. 

Carmela Vaccaro, Francesco Zarlenga, and Elena Marrocchino

In the last decades, the demand for raw materials, such as Heavy Metals (HM) and Rare Earth Elements (REE) is constantly grown due to the increasing demand from the new technologies. In particular, the REEs are mainly concentrated in apatite and zircon, largely present in pre-Paleozoic and Paleozoic cratonic rocks. Although many countries, such as Brazil, China and Iran have important deposits of HM and REE, they may only partially satisfy the increasing technology market demand. At present, extraction possibility is decreasing, and it is important to find new exploitable zones. For these reasons, mineral industries prefer to invest in exploration licenses before the mining activity.

Mozambique has a large and diverse mineral resource potential and is one of the most important exporting nations of raw materials.  Between 2009-2017 ENEA (National Agency for New Technology, Energy and Sustainable Economic Development) in collaboration with the University of Ferrara carried out explorative research to verify the presence of raw strategic materials in the Republic of Mozambique.

This research aims to investigate the sediments from the placer deposits of the Zambezi River in order to elaborate on the basis of analytical data an environmental friend extractive plan for mining activities that take into account also the environment and its preservation. The placer deposits are due to the mechanical agent, like marine, aeolian or lacustrine where minerals with high density and hardness, such as HM, are in high concentration, together with more than one economic mineral. The alluvial plain of the Zambesi River is characterized by the presence of sands, which contain heavy minerals in a percentage comprised of between 10-30%. A wide number of geochemical and mineralogical analyses (Diffractometry, XRF and ICP-MS) has been performed on samples, taken along 200 km of the river course. These data show a good presence of precious elements (Au, Ag, Pt, Pd, Os and Rh), a strong presence of minerals containing Fe and Ti, Zr, Hf and subordinately Ta, Ni and others. Moreover, Rare Earth Elements are present, in particular, is evident a good presence of Sc and Y from an economical point of view.

How to cite: Vaccaro, C., Zarlenga, F., and Marrocchino, E.: Research on the heavy sands of the floodplain of the River Zambezi (Republic of Mozambique). Mining potential and economic evaluation., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10374, https://doi.org/10.5194/egusphere-egu22-10374, 2022.

EGU22-11775 | Presentations | ERE4.3

Post-solidification features in granite natural stone and implication for its possible use and re-use in construction 

Richard Prikryl, Martin Racek, Vendula Natherova, Daniela Rimnacova, Jirina Prikrylova, and Aneta Kucharova

Granitoids are among the most common rock types used in construction. Along with their typical dominant mineralogical composition and rock microfabric, these rocks contain numerous minor/accessory phases and microfabric features that can be attributed to post-solidification development associated with e.g. hydrothermal alteration (HA). HA can be manifested both by microcracking, and by discrete changes in mineralogical composition – e.g., alteration of more basic cores of plagioclases, recrystallization of quartz aggregates, and/or by formation of clay mineral fillings of microcracks. Additional changes can occur due to various decay processes, and interactions with other construction materials (such as mortars) and/or conservation agents. Current study aims to show how these changes can influence physical and mechanical properties specifically when considering granitic natural stone used in important load-bearing infrastructural structures such as bridges. This issue can be of great importance for structures where individual stone elements were re-used from older ones or for those structures which require current repair.

How to cite: Prikryl, R., Racek, M., Natherova, V., Rimnacova, D., Prikrylova, J., and Kucharova, A.: Post-solidification features in granite natural stone and implication for its possible use and re-use in construction, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11775, https://doi.org/10.5194/egusphere-egu22-11775, 2022.

EGU22-12274 | Presentations | ERE4.3

Stone materials processing waste used as secondary raw material for construction adhesives: preliminary results. 

Sossio Fabio Graziano, Paolo Marone, Antonio Trinchillo, and Piergiulio Cappelletti

As is now widely known, any industrial activity produces wastes. These materials, more and more often, represent a logistic and environmental problem since they require regulations and treatments for disposal/storage that inevitably affect the general costs of the final product.

Wastes from stone materials processing, in short, retain all the mineralogical and compositional characteristics of the original materials even if, in some way, may be contaminated by the processing itself, or by wearing and tearing of industrial tools.

This research presents preliminary results from testing prototypes of construction adhesives made up recycling 1) a quartzite (India) stone waste mixed with 2) sand (also from India) as fine aggregates in mix design of the adhesives.

First, both wastes were characterized by physical, chemical and mineralogical points of view.

Particle size distribution along with X-ray Diffractometry, X-ray fluorescence and Scanning Electron Microscopy were carried out to acquire precise physical, mineralogical, and chemical information on wastes.

Experimental research started by mix designing different recipes considering a reference adhesive and a waste containing ones. Fresh doughs, as reported in European standard EN12004-2:2017, were cured for 28 days and used to stick on a concrete support three types of tiles with different grip: i) a polished metal plate, ii) a ceramic tile and a iii) natural stone slab. For each type a statistical valid number of sticked samples was tested.

After curing time, adhesive capabilities were tested by the Pull Off - Adhesion Test, as reported in European standard EN12004-2:2017, with very promising results, comparable to those obtained by normally marketed adhesives.

Further mix design additions useful for improving adhesive capabilities are currently under development.

Experimental procedures and results carried out in this research by using wastes from India can be safely extended to materials of different origins, proposing itself as an alternative method to storage for the reuse of these kind of wastes.

How to cite: Graziano, S. F., Marone, P., Trinchillo, A., and Cappelletti, P.: Stone materials processing waste used as secondary raw material for construction adhesives: preliminary results., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12274, https://doi.org/10.5194/egusphere-egu22-12274, 2022.

EGU22-12787 | Presentations | ERE4.3

Porphyry extractive activity in the Atesino Volcanic District (North of Italy): petrochemical characterization of materials placed in landfill 

Elena Marrocchino, Chiara Telloli, Maria Grazia Paletta, and Carmela Vaccaro

In the Trentino-Alto Adige region different types of stone materials are extracted, including the porphyry of the Atesino Volcanic Complex. Trentino porphyry from natural splitting stone has gradually gained more and more space in the last 25-30 years also in the market of sawn, flamed and polished products, which bring it back fully in the family of ornamental stones. This evolution has led to a significant increase in mining in the Trentino area with a consequent increase in the quantities of materials placed in landfills.

Porphyry landfills represent one of the most significant landscape-environmental and economic problems for the Trentino region. This involves a waste of natural resources, an increasing occupation of areas by processing waste, as well as profound morphological alterations of the landscape which can have repercussions on the stability of the slopes, also due to the difficulty of taking root.

The problem of the disposal of waste materials is becoming more and more pressing. From this arises the need to investigate possible sectors of interest for an alternative use of these materials.

In this regard, some landfills were sampled in the area between the towns of Baselga di Pinè to the east, Lavis to the west, bounded by an imaginary line that joins the towns of Fornace and Meano to the south and joins the towns of S. Michele all’Adige and Segonzano to the north.

Different samples collected were petrographically studied, through microscopically observation of thin sections, and petrochemically characterized by analysis in X-ray fluorescence spectrometry (XRF), at the laboratories of the University of Ferrara.

This study has highlighted the possible reuse in the ceramic sector of part of the materials placed in some of the landfills examined. A more in-depth and extensive study of the materials of the landfills in the stone Atesino District would allow the creation of a complete database useful for identifying the most suitable sites where to find atypical raw materials to be used in ceramic mixtures.

How to cite: Marrocchino, E., Telloli, C., Paletta, M. G., and Vaccaro, C.: Porphyry extractive activity in the Atesino Volcanic District (North of Italy): petrochemical characterization of materials placed in landfill, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12787, https://doi.org/10.5194/egusphere-egu22-12787, 2022.

EGU22-12973 | Presentations | ERE4.3

Use of basaltic quarry waste in renders, examples from Hungary 

Ákos Török and Zsuzsanna Kósa

A particular use of quarry waste is presented in this study. The aggregate quarries produce high amounts of quarry waste, especially dust, that has been considered for many years as ’no need materials. One possible use of this dust is as aggregate in renders. Four Hungarian basaltic quarries provides a high amount of dust: Uzsa, Recsk, Egerbakta and Vidornyaszőlős. 15% of the mass waste of dust from these quarries were added to the renders. Both standard size (quarry fresh) and nano-grinded dust were tested. Test specimens were made from the dust added render, and physical properties were tested 28 days after casting. Bending strength tests, uniaxial compressive strength tests were made to assess the mechanical properties of the renders. Carbonate formation, porosity and pore-size distribution were also analyzed to obtain valuable information on the binding and textural characteristics. Reference samples without basalt dust were also cast, and the test results were compared in order to assess the performance of basalt dust containing renders. The basalt dust and nano dust containing samples have lower bending strength than the reference ones, while the uniaxial compéressivbe strength increased when basalt dust was added. Nano dust containing samples show an increased porosity but a decrease in mean pore diameters. Our results show that adding basalt dust to renders could be a useful solution in the reduction of quarry waste and the obtained render has fairly good mechanical properties.

How to cite: Török, Á. and Kósa, Z.: Use of basaltic quarry waste in renders, examples from Hungary, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12973, https://doi.org/10.5194/egusphere-egu22-12973, 2022.

EGU22-2716 | Presentations | ERE4.4

Self-awareness for robust miner robot autonomy 

Esther Aguado, Ricardo Sanz, and Claudio Rossi

Robustness and resilience are crucial requirements for robots operating in unstructured and hazardous environments, such as the systems developed within the ROBOMINERS project. The miner robot shall handle, at least to some extent, the disturbances it may suffer; especially given the reduced possibility of human intervention in deep, small, and difficult-to-access deposits. In ROBOMINERS, we use self-awareness mechanisms to enhance robot miner autonomy. This capability enables the robot to be aware of the state of all its components (both hardware and software) and to what extent they are complying with their functions. Moreover, self-aware systems can reason about the run-time state and detect the causes of system failures. Depending on the specific characteristics of the affected robot, failure management mechanisms can be implemented at different levels. Robots can be designed to change their physical or software configuration, change the functions of some of their components, or adapt their behaviour to match mission needs. Our approach uses the knowledge of the systems engineer through machine-readable metamodels to provide the robot with information about the mission, the environment, and itself. These formal models allow the system to reason about its run-time situation. The ROBOMINERS resilience-augmenting solution is based on deep modeling of the functional architecture of the autonomous robot in combination with runtime reasoning. The reflective reasoning of the robot allows for both self-diagnosis and reconfiguration during mining operations. One of the main advantages of this knowledge-centric approach is the explicit definition, allocation, and linkage of system requirements, design decisions, system realization, and run-time information. This approach can transparently use robot structural and functional redundancy to ensure mission satisfaction, even in the presence of faults. Moreover, the use of several meta-models and ontologies allows the segmentation of information into different domains and levels of abstraction. These independent assets can then be re-targeted and adapted to a variety of systems, sub-systems, and contexts to improve asset reuse.

How to cite: Aguado, E., Sanz, R., and Rossi, C.: Self-awareness for robust miner robot autonomy, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2716, https://doi.org/10.5194/egusphere-egu22-2716, 2022.

EGU22-2740 | Presentations | ERE4.4

Modular collaborative resilient robots for mining operations 

Virgilio Gomez and Miguel Hernando

In the framework of the ROBOMINERS project, we are developing a set of modular collaborative robots that can perform mining operations. The purpose of this work is to face the challenge of taking modular robots out of the academic context and to provide robotic miners with the needed resilience which will be based on four pillars: redundancy, physical reconfiguration, adaptive behavior, and system reconfiguration. To do so, we are working on a scaled prototype based on a highly configurable modular robot that allows the connection between several autonomous robots (modules) and functional submodules (e.g., sensors, mining tools, locomotion devices) where resilience, energy sharing, self-reconfigurability, modularity, and self-awareness capabilities will be tested both in simulation and real-world scenarios. For each robot module, a lightweight and compact main structure is composed of three compartments and three docking ports for each of the robot legs. In each of these compartments most of the electronic components that allow the proper functioning of the robot are located, while in the legs a 4 degrees of freedom closed chain parallel mechanism powered by multi-turn servomotors is responsible of moving the interchangeable end effectors (screws, continuous tracks, legs) designed with a common coupling interface. In addition, an innovative soft telescopic robot arm (Patent pending) is placed at the front of the robot module and allows the coupling of another robot, sensing or actuation module. In parallel to the robot prototype development, a digital twin is being developed in order to test and improve different configurations, localization, mine mapping, and control algorithms techniques before deploying them in the robot.

How to cite: Gomez, V. and Hernando, M.: Modular collaborative resilient robots for mining operations, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2740, https://doi.org/10.5194/egusphere-egu22-2740, 2022.

EGU22-5726 | Presentations | ERE4.4

Dynamic modelling of a screw actuator for improved locomotion control on various terrains 

Walid Remmas, Roza Gkliva, and Asko Ristolainen

Different types of terrains can be encountered in mining environments, varying from hard rock bottom to mud, including gravel and sand. In our research we are investigating the usage of Archimedean screw actuators for locomotion in mining environments, as they are mechanically robust and can work on various substrates. The limitations on using screw locomotion in autonomous robotics include its inherent property of slippage that varies depending on the type of terrain. Moreover, the dynamic model of an Archimedean screw depends on variables such as shear stress or sinkage, which are difficult to measure with the onboard sensors. To accurately model and later control such robots, we focus on the dynamic modelling of the screw-ground interaction based on real experiments. In this work, we approximate the dynamics of an Archimedean screw to those of different tire models available in the literature. The proposed models are used to; (1) Simulate the ground-screw interaction with several types of grounds. (2) Estimate the robot pose based on odometry. (3) Design adaptive controllers able to control the robot in grounds with varying properties. We validate the proposed dynamic models based on experimental force measurements, and we evaluate the accuracy of the derived odometry models based on visually measured ground truth data.

How to cite: Remmas, W., Gkliva, R., and Ristolainen, A.: Dynamic modelling of a screw actuator for improved locomotion control on various terrains, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5726, https://doi.org/10.5194/egusphere-egu22-5726, 2022.

EGU22-7427 | Presentations | ERE4.4

UNEXUP, towards the exploration of underwater environments with a robotic solution 

Márcio Pinto, Norbert Zajzon, Luís Lopes, Balazs Bodo, Stephen Henley, José Almeida, Jussi Aaltonen, and Gorazd Žibret

UNEXUP is a project co-funded by EIT RawMaterials that started in January 2020 and will be concluded in December 2022. The main objective is to develop, test, and commercialize a novel robot-based technology to survey flooded mines and other underwater structures. The robots are equipped with geoscientific and navigation instruments that allow the collection of valuable data from sites that cannot be assessed without human risks or high investments for dewatering, for example.

This technology was initially developed during the H2020 UNEXMIN project – UNEXUP predecessor, during which three (UX-1) robots were built and tested in five different underwater sites in Europe with increasingly challenging conditions. From the lessons learned on these pilot tests, the engineers collected crucial points for improvement – in close connection with the feedback and requirements from potential users of technology.

In UNEXUP the objective is to build two new robots, with improved software and hardware compared to the previous generation, and to launch them to the market as a commercial service. The first robot, UX-1Neo, was developed in 2020; while UX-2 will be ready in 2022.

UX-1Neo is the upscaled version of the UX-1, equipped with improved navigational and geoscientific instruments and sensors. The upscaling robot has performed four field missions in 2021 – ranging from flooded mines, a water well, and an underwater cave.

The field missions proved the added value that the technology can provide to the mining community and other sectors involving underwater structures. UX-1Neo is a modular vehicle, ca. 90 kg, with swappable batteries, autonomy of approximately 9 hours, and depth capacity of 500 m. An IMU and DVL support the navigation of the robot, to measure the position and depth during the missions. The multibeam (1) and scanning sonars (2) allow the robot to map close, mid, and long-range cavities, and to detect and avoid obstacles in the environment. In addition, the robot is equipped with six SLSs (Structured Light Systems) for more detailed mapping when visibility and turbidity allow. Six cameras – natural light – allow the visualization of the environment and identification of rock types and geological structures. The motion control is supported by eight thrusters, and a mechanical pendulum, for pitch position lock.

The geoscientific instrumentation in UX-1Neo includes a hyperspectral unit, water sampler unit, water chemistry unit (pH, oxygen concentration, EC, temperature, pressure), sub-bottom profiler and a fluxgate magnetometer. This payload allows geoscientists to collect and interpret spatial and geoscientific data from underwater sites.

UX-2 is being developed with increased modularity and depth range compared to UX-1Neo, and some instruments and sensors in UX-1Neo were designed to be compatible with UX-2. It will have higher Technology Readiness Level; and a rock sampling unit supported by a robotic arm. Therefore, the UX-2 will be able to perform in even more challenging environments – broadening the applications of the commercial service – and extending its reliability to perform.

How to cite: Pinto, M., Zajzon, N., Lopes, L., Bodo, B., Henley, S., Almeida, J., Aaltonen, J., and Žibret, G.: UNEXUP, towards the exploration of underwater environments with a robotic solution, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7427, https://doi.org/10.5194/egusphere-egu22-7427, 2022.

EGU22-10299 | Presentations | ERE4.4

Overcoming the challenges of 3D modeling in harsh, confined, underwater environments: A case study 

Zorana Milosevic, Richard Zoltan Papp, and Hilco van Moerkerk

It is estimated that there are more than 8000 abandoned, flooded mines in Europe, many of which lack any information on their status and layout. Accurate and detailed 3D modeling plays a key role in fully understanding these complex environments and determining their remaining hidden potential. However, acquiring the needed data is a challenging task since these environments are extremely hazardous for traditional methods such as human diving. Additionally, human divers can reach only a limited depth range, much smaller than that of a standard mine. Therefore, underwater vehicles appear as a natural alternative for overcoming the disadvantages of direct human exploration. The UX1-Neo is a semi-autonomous underwater robotic system built precisely for this use. This small spherical robot with a 0.7m diameter has a 500m depth rating and various sensors for surveying the environment, such as multibeam and scanning sonars, structured light projectors, and multispectral cameras. 

 

The unfavorable properties of the water medium, such as light scattering and attenuation, pose additional difficulties for data acquisition in these complex environments. Furthermore, mine tunnels are a GPS-denied environment, which makes the modeling system rely entirely on the robot's inertial navigation system, which is prone to error due to the dead-reckoning drift. Conventional methods for correcting this drift, such as SLAM, face additional challenges in these repetitive environments (shafts and tunnels) due to their highly symmetric structures and lack of distinctive features. Additionally, during the exploration of a salt mine, Solotvyno (Ukraine), we faced a new challenge, a refraction of the sonar data due to the salty water, which required further processing in order to create an accurate 3D map of the mine. 

 

Rapid developments in the field of underwater photogrammetry are producing impressive results; however, they still have difficulties with the environments with low light, which causes blurring of details, low image contrast, and in general, lack of features needed for image matching. Also, underwater images are prone to contain an excessive amount of blue light, making the features even less visible. Moreover, photogrammetry technology struggles with repetitive environments due to the same reasons as SLAM.

 

In this work, we demonstrate the challenges faced during our exploration of the Solotvyno salt mine with the UX1-Neo robot and how we overcame them in order to produce a detailed 3D model. In particular, we illustrate that sensor and data redundancy is vital during operations and post-processing. Each UX1-Neo sensor contributes to a complete, coherent picture of the environment. However, using many sensors produces an enormous amount of data that require further filtering: hundreds of millions of points are reduced to a few million using both automated and manual methods. Images also require processing due to the aforementioned reasons: using CLAHE contrast enhancement together with white balancing algorithms, we produce suitable images for photogrammetry. Additionally, data gathered from multiple missions need to be combined for a complete model: we show the importance of robot orientation initialization and external surveying of the robot's launch location to correctly align scans of different missions.

How to cite: Milosevic, Z., Papp, R. Z., and van Moerkerk, H.: Overcoming the challenges of 3D modeling in harsh, confined, underwater environments: A case study, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10299, https://doi.org/10.5194/egusphere-egu22-10299, 2022.

In Europe there are a lot of abandoned mines that could be reopened with the use of innovative techniques; this is one of the aims of the ROBOMINERS project.

The use of the mining robots will especially be relevant for mineral deposits that are small or difficult to access.

Knowledge of type and dimensions of this mines is fundamental aiming to design and plan on-site tests of this robot.

In this article are explained the selection criteria of some mines in Italy among all the abandoned mines available at national level that could be investigated with robot miner.

In Italy there are about 3000 abandoned mining sites. Among these, eleven sites distributed throughout the national territory were selected.

Starting from a national public database containing all the abandoned mining sites and using an ad hoc KPI-matrix, some pilot sites were selected that met the required features.

The selection was carried out, according to the objectives of the project, preferring mining sites in urban areas, located at great depths or considered not economically relevant by traditional mining.

Among these, preference was given to metal-bearing ore deposits that could be better excavated with robot.

In order to characterize the selected sites, the following data have been collected for every site:

  • Geographic informations;
  • Historic time range of exploration ;
  • Deposit type;
  • Commodities available;
  • Main host rock.

Data collection was performed starting from the national database and subsequently integrating the informations with further data from bibliographic sources.

Data collection for the selected mines is of primary importance because the type of deposits can affect the correct functioning of the robot.

In order to design robot tools correctly is therefore essential to know in advance the geographic and geological features of the mine in order to carry out on-site tests.

How to cite: Tucci, E. and Ruggeri, R.: Robotics for raw material: the importance of data collection in the design of the appropriate equipments for exploring abandoned mines, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10484, https://doi.org/10.5194/egusphere-egu22-10484, 2022.

EGU22-11184 | Presentations | ERE4.4

Robotic mining: a new approach to geological modelling 

Hilco van Moerkerk and Paulina Dobrowolska

Within the EU funded Horizon 2020 project ROBOMINERS (www.robominers.eu) we were challenged to consider how autonomous robotic mining could be integrated with geological modelling. How would an autonomous robotic miner know where and whether an orebody is worth extracting? The orebody and all related geological aspects would need to be modelled in a comprehensible, self-containing format the robot can use directly.  To this end we envisioned a robot that would know where the orebody is, its important characteristics, and would have the ability to interpret the orebody in real-time and update its geological knowledge of the orebody as it excavates.

The modelled orebody could only be approximate at the robot scale (estimated at 1m maximum diameter!) as detailed information would be lacking. This led to re-evaluating existing geological modelling practices to see how they would fit within the robotic mining concept.

In our work we developed a novel approach to traditional geological modelling by combining three essential elements:

  • Replacement of blocks in block modelling with tetrahedra
  • Functional modelling framework to create model descriptors
  • Machine Learning

A tetrahedron is the most basic 3D element, similar to a triangle being the most basic 2D element to represent objects. Tetrahedra can be made to accurately reflect a boundary and are therefore always either inside or outside of that boundary. They are commonly used in Finite Element Methods (FEM) and have found their way into geophysics, geomechanics and flow modelling, but until now, not into geological modelling. Another major advantage is that a tetrahedral grid can be constructed at multi-resolution scales. However, it also means geological features need to be described in a way that allows them to be represented at those scales (e.g. mine scale versus robot scale).

One method to deal with these scale issues is to use a functional representation: representing geological features with (mathematical) functions. With functions, a value from that function at ANY point in 3D space can be retrieved to see if  that point is either inside or outside of a unit. Functions have been used under the Implicit Modelling (IM) banner. However, the functions can be also seen as classifiers between regions. Machine Learning’s (ML) core functionality is to provide is a mechanism for classifying data and estimate values or labels to unknown points. In our work, were therefore integrated high performance ML algorithms into IM.

With these three key elements we developed a system that can represent a complete 3D geological model in a consistent and ordered way by describing it rather than actually creating it. The model description can then create an optimized FEM model at any resolution when needed, even though the descriptor does not change. The ultimate aim is that the descriptors and functions will be used directly by the robot to optimize its path planning, without needing large data transfers.

How to cite: van Moerkerk, H. and Dobrowolska, P.: Robotic mining: a new approach to geological modelling, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11184, https://doi.org/10.5194/egusphere-egu22-11184, 2022.

EGU22-11395 | Presentations | ERE4.4 | Highlight

Robot-miners for a new mining future 

Luís Lopes, Claudio Rossi, Balazs Bodo, Giorgia Stasi, Christian Burlet, Stephen Henley, Vítor Correia, Tobias Pinkse, Alicja Kot-Niewiadomska, Jussi Aaltonen, Michael Berner, Nelson Cristo, Éva Hartai, Gorazd Žibret, Janos Horvath, and Asko Ristolainen

A multi-disciplinary team – the ROBOMINERS consortium – is creating a robot-miner for the future exploitation of difficult to access deposits. The approach builds on using robotics-related capacities for the mining sector. In particular, the ROBOMINERS vision foresees the use of a modular and reconfigurable robot in a mining setting where activities are nearly invisible. Mining will be more socio-environmentally viable, thus contributing to a more safe and sustainable supply of mineral raw materials fostered by the EU Raw Materials policies. When compared to current mining methods, the ROBOMINERS approach aims at: no presence of people in the mine, less mining waste produced and mining infrastructure needed, less investment, the possibility to explore currently uneconomic resources and development of new underground small-sized mines.

In the past two years, work focused on studying and designing enabling technologies, robot components and capabilities. The next steps will include integration of different software and hardware components leading to the development of the first robotic prototype (December 2022). Critical aspects of previous studies included 1) biological inspiration, 2) perception and localisation tools, 3) robot's behaviour, navigation and control, 4) actuation methods, 5) modularity, 6) autonomy and resilience, and 7) the selective mining ability, including development of ore perception and specialized production tools. Knowledge and technology transfer from these sub-fields to the robot-miner concept were possible thanks to collaborative work developed by the different mining and robotics teams in the laboratory and online, even during the COVID-19 times.

At the same time, the vision of a new mining robotic "ecosystem" is being developed: 1) computer models and simulations, 2) data management and visualisation systems, 3) rock mechanical and geotechnical characterisation, 4) analysing ground/rock support methods, bulk transportation methods, backfilling types and mining methods, and 5) sketching  upstream and downstream mining industry analogues for the ROBOMINERS concept.

Merging of robotics and geoscientific know-how for the purpose of creating test environments (simulated and real), construction of scale models (actual and virtual), iterative development and testing key robotic functions, together with the creation of a pool of deposits that could become viable targets for future extraction, and economical studies, back up the implementation capacity of the technology.

Thanks to the integration of the previous mentioned aspects, the mining machine will be able to perform autonomous selective ore extraction. The prototype will be tested at targeted areas representatives, including abandoned and/or operating mines, small but high-grade mineral deposits, unexplored/explored non-economic occurrences and ultra-depth, not easily accessible environments. Possible current candidates for testing purposes include mines in Estonia, Slovenia or Belgium. The trials are scheduled for 2023 and will provide a first case for the operability of this new mining machine and concept.

ROBOMINERS aims at delivering a proof of concept for the feasibility of this technology line at Technology Readiness Level 4, being validated in the lab and in the test mine locations. With future-proof improvements to the technology (deriving from roadmapping) it could enable the EU to access mineral raw materials from domestic sources that are otherwise inaccessible or uneconomic.

How to cite: Lopes, L., Rossi, C., Bodo, B., Stasi, G., Burlet, C., Henley, S., Correia, V., Pinkse, T., Kot-Niewiadomska, A., Aaltonen, J., Berner, M., Cristo, N., Hartai, É., Žibret, G., Horvath, J., and Ristolainen, A.: Robot-miners for a new mining future, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11395, https://doi.org/10.5194/egusphere-egu22-11395, 2022.

EGU22-12566 | Presentations | ERE4.4

The ROBOMINERS mineralogical sensors: spectrometer prototypes for autonomous in-stream, in-slurry geochemical diagnostics. 

Christian Burlet, Giorgia Stasi, Tobias Pinkse, Laura Piho, and Asko Ristolainen

ROBOMINERS (Bio-Inspired, Modular and Reconfigurable Robot Miners, Grant Agreement No. 820971, http://www.robominers.eu) is an European project funded by the European Commission's Horizon 2020 Framework Programme. The project brings roboticists and geoscientists together to explore new mining and sensing technologies and demonstrate a small robot-miner prototype designed to exploit unconventional and uneconomical mineral deposits (technology readiness level 4 to 5). This approach could change the current mining paradigms dictated by larger existing machines, while reducing mining waste and environmental footprint (Lopez and al. 2020).

One of the key function of ROBOMINERS is the “selective real-time mining”, in other words the ability for the miner to choose an optimal progression path while mining in a particular orebody geometry (inspired by the petroleum industry geo-steering technique). This will be done by a continuous monitoring of the surrounding rock properties (hardness, abrasivity, electrochemistry, thermal conductivity, 3D electrical/induced polarization tomography), and by a “digestive mineralogy” unit, performing on-board mineralogical/geochemical diagnostics of the extracted material.

After an extensive review and tests on existing sensing techniques, the consortium selected a few sensing methods, based on the considered environment (underground gallery drilling, mud/slurry-filled environment with very limited to no visibility) and the opportunity to test proven techniques as well as original methods that can be distributed on and in the miner body.

Mineralogical sensor prototypes on ROBOMINERS are articulated on 3 techniques : multi/hyperspectral reflectance, UV fluorescence and Laser-induced breakdown spectrometry (LIBS). The first two techniques are well established and easily integratable on a robotic platform. ROBOMINERS will demonstrate how miniatirization/distribution of these sensors on and in the robot can yield fast diagnostics from the excavated material. LIBS is a very interesting atomic emission technique for real-time monitoring of slurries with fast multi-element detection and low detection limits, even on light elements. It has been already used as a competitive approach to monitor slurries using flow cells in mining (Khajehzadeh et al., 2017) and inside molten metals in metallurgy applications (Moreau et al., 2018). LIBS typically achieve fast and sensitive analysis in a few micro- to milli- seconds. While true quantitative measurements remain a challenge outside a controlled lab environment, qualitative and semi-quantitative measurements are possible and is very relevant for ROBOMINERS selective mining application.

The work presented here deals with the conceptualization of the spectrometer suite. Tested slurry analogs include mixtures of lead-zinc sulfides, copper cobalt oxides, phosphorites and oil shales. Once an fixed instrumental setup is selected, the next development steps include retrofitting for testing in an industrial scale slurry circulation system at the K-UTEC facilities (Sondershausen, Germany) and, after validation of all components, integration on the ROBOMINERS prototype for the field demonstrations planned in 2023.

References.

Lopes, B. Bodo, C. Rossi, S. Henley, G. Žibret, A. Kot-Niewiadomska, V. Correia, Advances in Geosciences, Volume 54, 2020, 99–108

Khajehzadeh, O. Haavisto, L. Koresaar, , Minerals Engineering, Volume 113, 2017, pp 83-94

Moreau, A. Hamel, P. Bouchard, and M. Sabsabi, , CIM Journal, Volume 9, No. 2, 2018

How to cite: Burlet, C., Stasi, G., Pinkse, T., Piho, L., and Ristolainen, A.: The ROBOMINERS mineralogical sensors: spectrometer prototypes for autonomous in-stream, in-slurry geochemical diagnostics., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12566, https://doi.org/10.5194/egusphere-egu22-12566, 2022.

EGU22-863 | Presentations | GMPV5.2

Characteristics of non-spherical manganese nodule from the East Siberian Sea 

Hyen Goo Cho, Hyo-Jin Koo, Mu Seong Park, and Chung Man Seo

Manganese nodules have been found in the shallow water depth of the Arctic Ocean as well as in the abyssal plains of the Pacific and Indian Oceans, but detailed study for them were rarely investigated. Manganese nodules, collected from the East Siberian Sea through the Arctic Expedition using Araon ice braking vessel, have a high potential for Mn mineral resources because they have high Mn content with high Mn/Fe ratio. This study investigated the external form, size and weight, internal texture for the non-spherical manganese nodule, which has about 7 % of total nodule from the East Siberian Sea. This study also researched the relative Mn-oxide mineral composition using the peak area ratio of X-ray diffraction pattern and their chemical composition. All data obtained from non-spherical nodules were compared with the spherical ones. Ellipsoidal, platy and irregular types are common among 5 groups of non-spherical manganese nodule based on the external form, and major axis and weight have positive relationship. All non-spherical manganese nodules have core mainly composed of mud sediments. The average Mn oxide mineral contents in nodules are birnessite, buserite and todorokite in descending order. Although mineral composition does not show any correlation with the external form, kind of core or internal structure, todorokite and buserite contents tend to increase and birnessite content decrease from the surface to the core in the nodule. Non-spherical manganese nodules have higher Mn content and Mn/Fe ratio than those from the shallow water depth of the Arctic Sea and even in the deep-sea of the Pacific and Indian Ocean. Almost all manganese nodules from this study are attributed to diagenetic process, because they are higher than 5 in Mn/Fe ratio.

How to cite: Cho, H. G., Koo, H.-J., Park, M. S., and Seo, C. M.: Characteristics of non-spherical manganese nodule from the East Siberian Sea, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-863, https://doi.org/10.5194/egusphere-egu22-863, 2022.

Shallow seawater-hydrothermal circulation plays a crucial role in the subseafloor mineralization of the hydrothermal system. However, its key fluid processes and impacts on the metal mobilization and sulfur cycles in the stockwork mineralization are still poorly understood. We first present the systemic variations in micro-scale trace element and sulfur isotope compositions of pyrite varieties in a stockwork-like sulfide from the Longqi hydrothermal field to constrain the metal transport and deposition and sulfur origins and cycles in the shallow seawater-hydrothermal circulation. Pyrites considered as the dominant sulfides can be clarified into disseminated fine-grained (Py-I), euhedral (Py-II), and subhedral-euhedral (Py-III) varieties based on texture. The wall-rock-derived elements Ti, Cu, Ni, Mg, and Mn and seawater-derived elements Mo, V, and U are concentrated in Py-I within the breccias and related to the fluid-rock reaction and fluid-seawater mixing in the shallow seawater-hydrothermal circulation system. Short-lived shallow circulation results in fluid fluctuation and oscillatory-zoned Py-II with depletion of Co, Ni, Cu, As, and Se in the mantles relative to those in the rims and cores. As the later hydrothermal activity was active, Py-III that was overgrown from Py-II is rich in hydrothermally inherited metals Se, Te, and Co, possibly implying the hydrothermal field is coming into the main mineralization. The sulfur isotope compositions of pyrites range from 4.30 to 9.98‰ (n=37), with distinct δ34S variations in the individual Py-I crystal (> 1.5 ‰ within a 20 × 20 µm2 region). This variation is attributed to changes in the relative proportion of sulfur sourced from (i) the shallow-origin reduced seawater via reduction by ferrous iron released from basalt (ii) the reduction of pre-existing anhydrite by later hydrothermal overprinting in the shallow subseafloor. These findings provide evidence for a model to better understand the effect of shallow seawater-hydrothermal circulation on the subseafloor stockwork mineralization of hydrothermal fields.

How to cite: Meng, X., Li, X., Jin, X., Chu, F., Zhu, J., and Wang, Y.: Subseafloor mineralization related to shallow seawater-hydrothermal circulation in the Longqi hydrothermal field, Southwest Indian Ridge (49.6°E): Evidence from in situ trace element and sulfur isotope compositions of pyrite varieties, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-907, https://doi.org/10.5194/egusphere-egu22-907, 2022.

EGU22-1018 | Presentations | GMPV5.2

Bi-minerals occurrence in various ore deposits of Southern Sardinia: a short review. 

Matteo Luca Deidda, Dario Fancello, Naitza Stefano, Marilena Moroni, and Ignazio Scano

Bismuth is recognized as a Critical Raw Material by the EU Commission and it is found in many ore deposits across the world. In Southwestern (SWS) and Southeastern (SES) Sardinia, Bi-minerals are commonly found in two main groups of ore deposit: 1) late Variscan granite-related orebodies including greisens, W-Mo(-Sn) HT hydrothermal veins, skarns and  hornfelses; and 2) late- to post-Variscan five-element (Ni-Co-As-Bi-Ag) LT hydrothermal veins.

In the first group, greisens (Flumini Binu prospect, SWS) and HT hydrothermal W-Mo(-Sn) veins (Perd’e Pibera mine and Togoro prospect, SWS; Perda Majori-Bruncu Spangas prospects, SES) tipically host native Bi, bismuthinite and, subordinately, Pb-Ag-Bi-sulfosalts interstitial to molybdenite and/or scattered in the quartz-feldspar(-fluorite-topaz) gangue. Locally, maldonite (Au2Bi), Bi-tellurides (hedleyite Bi7Te3, and Bi2Te) and probable russellite (Bi2WO6) are abundant in wolframite-rich veins (Togoro prospect), associated with native Au. Small grains of native Bi have also been found in some poorly mineralized garnet-vesuvianite-epidote calc-silicate hornfelses (Domus De Maria, SWS). Besides native Bi and bismuthinite, skarn orebodies frequently host wider assemblages consisting of Bi-Pb-Ag-Cu-sulfosalts intergrowths, once again associated with wolframates (scheelite at Monte Tamara prospect and Sa Marchesa mine, SWS) and molybdenite (Monte Tamara, Sa Marchesa and Morettu prospect, SWS). As a reference, the Monte Tamara assemblage includes “phase 88.6” (Cu0.33Pb0.33Bi7.67S12), pekoite (PbCuBi11S16Se2), salzburgite-paarite (Cu1.58-1.67Fe2+0.03-0.01Pb1.65-1.72Bi6.38-6.3S12-12.06), gustavite (PbAgBi3S6) xilingolite-lillianite (Pb3Bi2S6), cosalite (Pb2Bi2S6), berryite (Cu3Ag2Pb3Bi7S16), ourayite (Pb4Ag3Bi5S13) and cupropavonite (Cu0.9Ag0.5Pb0.6Bi2.5S5), identified by means of EPMA analyses. Moreover, since high Bi(-Ag-Te) contents have been detected in sulfides (sphalerite, galena, arsenopyrite), micro-inclusions of -sulfosalts and/or -tellurides may also occur. In the same area, wittichenite ((Bi,Cu)2S3) and hammariite (Pb2Cu2Bi4S9) have been previously identified, while schapbachite (AgBiS2) has been reported at the Sa Marchesa mine.
The second group of Bi-bearing orebodies includes the five-element veins of the Arburèse district (Pira Inferìda, Acqua Is Prunas and Sa Menga mines, SWS), where native Bi and bismuthinite tipically occur at the core of Ni-Co arsenides-sulfarsenides (e.g. nickeline and gersdorffite-cobaltite) concentric growths.

Therefore, the strong affinity of bismuth for granite-related W-Mo(-Sn) deposits of Southern Sardinia indicates that the late-Variscan (Early Permian) granites represent its main metallogenic source. However, the formation of such diverse Bi-minerals assemblages is seemingly controlled by local-scale conditions. In skarn ores, the Bi-Pb-Ag-Cu-sulfosalts intergrowths formed during the sulfide stages, apparently after the interaction between primary Bi-phases and Pb-Ag-Cu-bearing hydrothermal fluids and under oscillatory variations of metals availability and stability. Conversely, in W-Mo(-Sn) hydrothermal veins and greisens, where sulfides are apparently more scarce, the array of Bi-phases is usually more limited. Furthermore, field and analytical data point towards a selective remobilization of bismuth from the primary native and -tellurides assemblage of HT wolframite-quartz veins (Togoro, SWS) by late cross-cutting LT five-element veins, suggesting that multiple, spaced over time hydrothermal-veining events occurred in the same area.
In conclusion, bismuth and related mineral phases could serve as important markers, providing useful qualitative indications regarding the source of metals, the ore-forming processes and the relationships between different ore deposits at the district-scale.

How to cite: Deidda, M. L., Fancello, D., Stefano, N., Moroni, M., and Scano, I.: Bi-minerals occurrence in various ore deposits of Southern Sardinia: a short review., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1018, https://doi.org/10.5194/egusphere-egu22-1018, 2022.

EGU22-1067 | Presentations | GMPV5.2

Cobalt and REE distribution at the Zinkgruvan Zn-Pb-Ag and Cu deposit, Bergslagen, Sweden 

Nils Jansson, Ingeborg Hjorth, Filip Ivarsson, Thomas Aiglsperger, Amir M. Azim Zadeh, Ellen Kooijman, Melanie Kielman-Schmitt, Foteini Drakou, and Gabriela Kozub-Budzyń

The metamorphosed, stratiform, c. 1.9 Ga Zinkgruvan Zn-Pb-Ag deposit is one of Europe’s largest producers of Zn. Since 2010, disseminated Cu mineralization is also mined from dolomite marble in a hydrothermal vent-proximal position in the stratigraphic footwall. Local enrichments of Co and REE exist in the vent-proximal mineralization types, albeit their distribution is poorly known. This contribution provides new data on the distribution of Co and REE within the Zinkgruvan deposit.

LA-ICP-MS analysis suggest that lattice-bound cobalt in sphalerite range between 44 ppm and 1372 ppm, with the lowest and highest values occurring in distal and proximal mineralization, respectively. Proximal Co-rich sphalerite is always Fe-rich. Lattice-bound Co also occur in pyrrhotite; ranging from 52 ppm in distal ore to 1608 ppm in proximal ore. There is a concurrent increase in lattice-bound Ni from 3 ppm to 529 ppm. In proximal ore, Co is also hosted by cobalt minerals such as costibite (27.37 wt.% Co), safflorite (16.21 wt.% Co), nickeline (7.54 wt.% Co), cobaltite (32.74 wt.% Co) and cobaltpentlandite (25.49 wt.% Co). Automated quantitative mineralogy suggest that these minerals are highly subordinate to sphalerite (<70.11%) and pyrrhotite (<14.69%), amounting to <2.88% cobalt minerals with safflorite being most common (up to 2.67%). Cobalt deportment calculations suggest that the proportion of whole-rock Co that is lattice-bound to sphalerite and pyrrhotite ranges from 7.80% to 100%, with sphalerite being the main host. Whole-rock As and Ni contents pose a strong control on whether Co occurs lattice-bound or as Co minerals.

LA-ICP-MS analysis show that accessory apatite in proximal, marble-hosted Cu mineralization carries a few thousand ppm ∑REE, but locally up to c. 1.6 wt.% ∑REE. The apatite can be subdivided into two types. Type 1 apatite is characterized by dumbbell-shaped chondrite-normalized REE profiles with relative enrichment of in particular Sm-Tb, depletion of Yb-Lu relative to La-Pr, local positive Gd anomalies, and weak positive to negative Eu anomalies. Type 2 apatite is characterized by flat to negatively sloping REE profiles from La to Gd and relative HREE depletion. Additional REE is hosted by monazite. Type 1 apatite was only found as a gangue to Cu mineralization. The Type 1 apatite REE signature is characteristic of hydrothermal apatite, and a direct genetic association with vent-proximal Cu mineralization can be inferred.

Comparison with published REE contents in apatite suggest that vent-proximal Zinkgruvan apatite is locally as REE-rich as apatite from Kiruna-type apatite iron oxide deposits, and more REE-rich than apatite in other metamorphosed sediment-hosted sulphide deposits in the world, such as the Gamsberg deposit (RSA).

How to cite: Jansson, N., Hjorth, I., Ivarsson, F., Aiglsperger, T., M. Azim Zadeh, A., Kooijman, E., Kielman-Schmitt, M., Drakou, F., and Kozub-Budzyń, G.: Cobalt and REE distribution at the Zinkgruvan Zn-Pb-Ag and Cu deposit, Bergslagen, Sweden, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1067, https://doi.org/10.5194/egusphere-egu22-1067, 2022.

EGU22-1110 | Presentations | GMPV5.2

Geological and chemical controls in ore shoot mineralization of polymetallic veins: insights from the five-elements Ni-Co-As-Ag-Bi hydrothermal veins of SW Sardinia 

Ignazio Scano, Matteo Luca Deidda, Dario Fancello, Marilena Moroni, and Stefano Naitza

Several studies on polymetallic hydrothermal veins of western Europe recently highlighted the role of physicochemical controls in determining and enhancing mineralizing processes in structurally defined, spatially limited environments (vein “ore shoots”). Host rocks have critical roles: a) the development and geometry of the structures and veins depend on their rheological features; b) they may act as sources of elements and c) regulate the type and kinetics of chemical reactions after fluid-rock interaction. An excellent example is provided in SW Sardinia by the five-elements (Ni-Co-As-Ag-Bi) veins of the Arburèse District. These late- to post-Variscan low-temperature veins are hosted in Ordovician-Silurian very low-grade metamorphic siliciclastic rocks outcropping between the Arbus granitoid (304±1 Ma) and the Mt. Linas granite (289±1 Ma). Ordovician host rocks mostly include sandstones and siltstones, while Silurian rocks are dominated by carbonaceous argillites (black shales). The distinct competence of these host rocks resulted in different geometries of spaces opened to fluid circulation, leading to the formation of orebodies with different shapes: large veins mainly occur in Ordovician sandstones and siltstones (e.g., Pira Inferida mine), while thinner, often anastomosed veins occur in Silurian black shales (e.g. Acqua Is Prunas mine). Vein formation is triggered by seismic cycles in faults at shallow crustal levels, as testified by widespread breccia and cockade textures. The ore shoots display complex mineral assemblages: native Bi; Ni-Co-Fe arsenides and antimonides (nickeline, breithauptite, rammelsbergite, safflorite, skutterudite, loellingite); Ni-Co-Fe sulfarsenides-sulfantimonides (gersdorffite, cobaltite, ullmannite, arsenopyrite); and Pb-Zn-Cu-Fe sulfides (galena, sphalerite, chalcopyrite, pyrite); Ag-Sb-As and Se sulfosalts. Carbonates (mainly siderite, minor ankerite, dolomite-calcite) and quartz are the main gangue minerals. Field, textural and analytical data support an overall rapid formation of ore minerals under multiple and distinct mineralizing pulses, starting with native elements and arsenides, followed by sulfarsenides and sulfides. Ore shoots must have formed in relatively restricted environments chemically marked by the abundant redox agents (carbonaceous matter, pyrite and, possibly, hydrocarbons) provided by Silurian black shales, which may have supplied sulfur and other elements (e.g., Se) for mineralization. Thus, differences in host rock geochemistry may explain local differences in ore shoots composition and paragenetic sequences. A further control at the district scale is represented by the repeated intersections of the five-elements vein system with earlier Mt. Linas granite-related Sn-As and W-Bi-Te-Au veins, documented in several ore shoots of the district (Pira Inferida, Acqua is Prunas and Sa Menga mines). Such intersections formed preferred pathways for fluid circulation and wider spaces for mineral precipitation during ore-forming processes; moreover, main components of five-elements ores (e.g., As, Bi) appear to be inherited by remobilization from granite-related veins. In summary, ore shoot mineralization in the studied vein system may have been controlled by multiple factors (host structures; host rock rheology and composition; intersections with other vein systems) that may be assumed as key prospection guidelines for further mineral exploration in the area; until now this vein system has only been explored in its shallower parts, and it is possible that much of the ore shoots has yet to be discovered.

How to cite: Scano, I., Deidda, M. L., Fancello, D., Moroni, M., and Naitza, S.: Geological and chemical controls in ore shoot mineralization of polymetallic veins: insights from the five-elements Ni-Co-As-Ag-Bi hydrothermal veins of SW Sardinia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1110, https://doi.org/10.5194/egusphere-egu22-1110, 2022.

EGU22-1555 | Presentations | GMPV5.2

Metallogeny of Manto-type Copper Deposits of Iran: A Possible Link to the Evaporitic basins 

Sara Momenipour, Abdorrahman Rajabi, and Somaye Rezaei

Abstract

Iran is one of the most significant producers of copper in the world and hosts varieties of copper deposits, including porphyry Cu-Mo, vein-type, volcanogenic massive sulfide (VMS), sediment-hosted stratabound copper (SSC), Manto-type, and skarn.

Manto-type deposits are the second producer of copper in Iran, mostly hosted in basalt, basalt-andesite to andesite volcanic rocks. There are more than 40 Manto-type copper deposits and occurrences in Iran, such as Mari, Abbas-Abad, Vorezg, Robat, Simakan, and Sorkho, and most of them are economically deposits. Most of these deposits occur in Eocene volcanic rocks, and a small amount of them (such as KeshtMahki, Hassanabad, Khorjan, and Simakan) are hosted in the Early Cretaceous volcanic rocks that mainly concentrated in the Saveh-Yazd (in the Urumieh-Dokhtar magmatic belt), Qazvin-Zanjan, Sabzevar-Neishabour, Semnan-Shahroud volcanic zones, and eastern Iran.

The stratabound sulfide ores in these Manto-type copper deposits include chalcocite, chalcopyrite, and bornite, associated with covellite, malachite, atacamite, chrysocolla, and minor azurite in the oxidized and supergene ore zones. Sulfide mineralization usually occurs as a replacement in pyrites and feldspars, vein and veinless, and breccia, which is accompanied by carbonatization, propylitic, and minor sericite alterations. Geological and geochemical data indicate that most of these deposits formed within plate failed continental rift and back-arc extensional environments related to the subduction of the oceanic crust of neo-Tethys beneath the Iranian Plateau.

Furthermore, the temporal and spatial distribution of these deposits in terms of time shows a close relationship with evaporitic basins. This phenomenon suggests a genetic relationship between the formation of Manto-type deposits and the circulation of brines from adjacent evaporitic basins in shallow extensional tectonic environments.

How to cite: Momenipour, S., Rajabi, A., and Rezaei, S.: Metallogeny of Manto-type Copper Deposits of Iran: A Possible Link to the Evaporitic basins, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1555, https://doi.org/10.5194/egusphere-egu22-1555, 2022.

EGU22-2508 | Presentations | GMPV5.2

Metasomatic aureoles of highly mobile elements related to evolved granitic aplite-pegmatites from Fregeneda–Almendra (Spain–Portugal) 

Jon Errandonea-Martin, Idoia Garate-Olave, Encarnación Roda-Robles, Joana Cardoso-Fernandes, Alexandre Lima, Maria dos Anjos Ribeiro, and Ana Cláudia Teodoro

Granitic pegmatites represent an important source of numerous critical raw materials, and subsequently, the exploration of new deposits has become a crucial objective in the energy transition towards green technologies. Systematic studies of geochemical aureoles related to late-Variscan Lithium-Cesium-Tantalum (LCT) pegmatites at the Fregeneda–Almendra Pegmatite Field (Central Iberian Zone; Iberian Massif), have provided valuable information to consider in mineral exploration. Due to the relative homogeneity of host psammitic and pelitic metasediments (SiO2/Al2O3 of 2.57–5.59 wt.%, and Fe2O3t/K2O values of 0.24 to 4.19 wt.%), it has been possible to establish an ideal composition for the country rocks to assess the chemical behavior of some key elements associated to the studied LCT pegmatites.

The performed geochemical modelling (based on Gresens’ (1967) equation) shows that the intrusion of evolved aplite-pegmatites (Li-mica- and spodumene-bearing) produced an enrichment in the host rocks of several elements defined as highly mobile (F, B, Li, Rb, Cs, Sn, Be and Tl) in comparison with the determined immobile elements (Si, Al and Ti). Calculated gains and losses of such highly mobile elements display exponential decreasing trends according to the distance from the pegmatitic dyke, with Li and Cs reaching furthest from the dykes (first evidence of anomalous contents starting at distances of 4–5 times the thickness of the dyke). In terms of mineral exploration, the extent of such aureoles associated with potentially economically interesting dykes may be traceable by different small-footprint exploration tools as remote sensing, X-Ray Fluorescence, or Laser-Induced Breakdown Spectroscopy (LIBS).

Gresens, R. L. (1967). Composition–volume relationships of metasomatism. Chemical Geology 2, 47–55.

Financial support: European Commission’s Horizon 2020 Innovation Programme [grant agreement No 869274, project GREENPEG: New Exploration Tools for European Pegmatite Green-Tech Resources]

How to cite: Errandonea-Martin, J., Garate-Olave, I., Roda-Robles, E., Cardoso-Fernandes, J., Lima, A., Ribeiro, M. D. A., and Teodoro, A. C.: Metasomatic aureoles of highly mobile elements related to evolved granitic aplite-pegmatites from Fregeneda–Almendra (Spain–Portugal), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2508, https://doi.org/10.5194/egusphere-egu22-2508, 2022.

EGU22-2962 | Presentations | GMPV5.2

Geology, mineralization, and alteration of B prospect of the epithermal Au-Ag deposit in central Thailand: A study on Chatree’s peripheral deposit for further gold exploration. 

Sirawit Kaewpaluk, Abhisit Salam, Thitiphan Assawincharoenkij, Takayuki Manaka, Sopit Poompuang, and Surachat Munsamai

The B prospect is located at the southeast of the Chatree gold-silver deposit. The mineralization is hosted in the Late Permian-Early Triassic Chatree volcanic sequence consisting of volcaniclastic and volcanogenic-sedimentary rocks ranging in composition from basaltic andesite to rhyolite. At the study area, the total thickness of volcanic succession is about 300 meters, and the succession can be divided into three main stratigraphic units from bottom to top, namely, 1) porphyritic andesite unit (Unit 3), 2) polymictic intermediate breccia unit (Unit 2), and 3) volcanogenic sedimentary unit (Unit 1). The ore zones are mainly confined to polymictic intermediate breccia and volcanogenic sedimentary units (Units 1 and 2). At least three stages of mineralization have been identified, namely 1) quartz -pyrite (Stage 1), 2) quartz-chlorite-calcite-sulfides-electrum (Stage 2) and 3) quartz-calcite (stage 3) veins/veinlets. Gold occurs chiefly in Stage 2 mineralization which is characterized by typical vein textures of low sulfidation epithermal deposit (e.g., crustiform, colloform banding, comb textures). Pyrite is a primary sulfide mineral with minor sphalerite, chalcopyrite, and galena. Gold occurs as electrum with fineness ranging from 506 to 632 ppm. The hydrothermal alteration at B prospect is composed of two main types: 1) quartz-adularia (silicic alteration) assemblage close to ore zone, and 2) adularia-quartz-illite-calcite-chlorite (phyllic alteration) assemblage distal to ore zone. Based on characteristics of mineral assemblages, textures, and alterations the mineralization at B prospect can be classified as a low sulfidation epithermal gold-silver style deposit. 

How to cite: Kaewpaluk, S., Salam, A., Assawincharoenkij, T., Manaka, T., Poompuang, S., and Munsamai, S.: Geology, mineralization, and alteration of B prospect of the epithermal Au-Ag deposit in central Thailand: A study on Chatree’s peripheral deposit for further gold exploration., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2962, https://doi.org/10.5194/egusphere-egu22-2962, 2022.

EGU22-3480 | Presentations | GMPV5.2

Pressure–temperature–time assessment for the intrusion of the spodumene-bearing dyke from Alijó (northern Portugal) 

Nora Santos-Loyola, Encarnación Roda-Robles, Idoia Garate-Olave, Jon Errandonea-Martin, and Alexandre Lima

The Barroso–Alvão Pegmatite Field (Galicia-Trás-os-Montes Zone of the Iberian Massif) has been a target of abundant geological and mineral resource exploration studies in the last decades. Since lithium demand is increasing significantly at global scale as critical raw material for green technologies, the region has acquired a special relevance in terms of Li exploration. Within the distinguished aplite-pegmatite types in the area, the dyke of Alijó (currently in exploitation) corresponds to the spodumene-bearing type. The estimation of the P-T-t conditions for its intrusion provides useful information to constrain petrogenetic processes related to the origin of the cited pegmatite field.

The presence of albite and K-feldspar coexisting in the studied dyke point to a high H2O activity in the pegmatitic melt, which would decrease the temperature (T) of the solidus. Additionally, the lattice twin observed in microcline indicates that the crystallization of orthoclase took place followed by a rapid decrease of T, leading to the conversion of orthoclase to microcline. Thus, the presence of the lattice twin shows that the crystallization T must have been above 450–500°C (Ribbe, 1983). Considering the abovementioned minimum crystallization temperatures, the paragenesis of both primary and secondary spodumene (the later as a result of primary petalite replacement) restricts the primary pressure conditions to 2–3 kbar (e.g. London, 1984). Besides this paragenesis, the occurrence of eucryptite supports a sufficiently rapid decrease of T (and P) to allow the coexistence of these phases in the studied aplite-pegmatite. In agreement with the mentioned, the frequently observed ‘comb-like’ Unidirectional Solidification Textures (UST) in the margins of the dyke imply a strong and rapid undercooling of the system, probably caused by the exsolution of a H2O-rich fluid phase from the pegmatitic melt, once intruded into the open fracture where it occurs, combined with the high contrast of T between the pegmatitic melt and the relatively cooled host metasedimentary rocks.

London, D., 1984. Experimental phase equilibria in the system LiAlSiO4–SiO2–H2O: a petrogenetic grid for lithium-rich pegmatites. American Mineralogist, 69: 995-1004

Ribbe, P. H., 1983. Feldspar mineralogy 2nd edition. De Gruyter, Berlin, 362pp

Financial support: European Commission’s Horizon 2020 Innovation Programme [grant agreement No 869274, project GREENPEG: New Exploration Tools for European Pegmatite Green-Tech Resources]

 

How to cite: Santos-Loyola, N., Roda-Robles, E., Garate-Olave, I., Errandonea-Martin, J., and Lima, A.: Pressure–temperature–time assessment for the intrusion of the spodumene-bearing dyke from Alijó (northern Portugal), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3480, https://doi.org/10.5194/egusphere-egu22-3480, 2022.

EGU22-4200 | Presentations | GMPV5.2

Characteristics of Magnetite and Calc-Silicate Minerals in the Gryll’s Bunny Skarn in the Land's End Aureole, SW England 

Ece Kirat, Jens C.Ø. Andersen, and Ben J. Williamson

The skarns at Gryll’s Bunny are dominated by garnet and magnetite with small amounts of hornblende, epidote, apatite and tourmaline. They formed discordantly within a succession of metabasalts and metapelites (the Mylor Slate formation) within the metamorphic aureole of the Land’s End granite. The skarns subdivide into discrete mineralogical types that include garnet-skarn with medium-coarse grained garnet, epidote, tourmaline, amphibole and biotite; hornblende-skarn with coarse-grained tabular hornblende, medium grained garnet, epidote, titanite, apatite and tourmaline; the foliated metapelite contains fine-grained hornblende and garnet with alkali feldspar, sericite, muscovite, titanite, quartz, epidote, apatite and tourmaline; cassiterite-rich “tin floors” are overlain by (variably metasomatized) metabasite that include horizontal bodies of tourmalinite with cassiterite, titanite, chlorite and apatite.

The lithologies contain variable amounts of magnetite that can be classified into 5 types. Magnetite in the metapelite (type 1) is very fine grained. Magnetite in hornblende-skarn associated with the metapelite (type 2) is fine grained with ilmenite lamellae and is associated with maghemite. Magnetite in the hornblende skarn adjacent to garnet skarn (type 3) contains abundant ulvöspinel lamellae. Magnetite in the garnet skarn is medium to coarse-grained with a granular recrystallized texture and spinel exsolutions (type 4). All of these types have been partially replaced by hematite along edges and cracks. Magnetite related with the tourmaline zone (type 5) is generally euhedral and free of exsolution lamellae. In addition, the tourmaline-cassiterite zone has abundant titanite with ilmenite laths.

Fluid inclusions in garnet, amphibole and epidote of the metasomatized rocks, garnet related with type-3 magnetite has higher homogenization temperature (291- >600 oC) and almost similar low-moderate salinity (2.4-13.7 wt. % NaCl equiv.) than that of type-2 magnetite (222-428 oC and 3.9-14.8 wt. % NaCl equiv).

EPMA and LA-ICP-MS analysis demonstrate that garnets are of grossular (60-76)-andradite (13-32) composition and rich in TiO2; amphiboles are sadanagaite-pargasite, tourmalines are shorl-feruvite and apatites are fluor- and hydroxyl-apatite composition. V/Ti and Ga/Ti in magnetite decrease progressively from type 1 to 5, indicating that type 1 and 2 retain characteristics of their mafic host rock as well as metamorphic process, development towards type 5 is interpreted by the increasing significance of granitic fluids. All of the magnetite types have elevated Sn and Zn whilst Zr, Mg and Al are low. The homogeneity of type 5 magnetite supports a purely metasomatic origin at the final stage of skarn development.

Key words: SW England, Gryll’s Bunny skarns, Botallack, Magnetite, Mineralogy, Geochemistry, Fluid inclusions

How to cite: Kirat, E., Andersen, J. C. Ø., and Williamson, B. J.: Characteristics of Magnetite and Calc-Silicate Minerals in the Gryll’s Bunny Skarn in the Land's End Aureole, SW England, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4200, https://doi.org/10.5194/egusphere-egu22-4200, 2022.

EGU22-5712 | Presentations | GMPV5.2

Slow and Steady or Episodically Catastrophic?  Timescales and Processes for Hydrocarbon and Metallic Resource Development 

Holly Stein, Judith Hannah, Niels Rameil, and Jon Halvard Pedersen

A range of geochemical data has been used to navigate the complexity of systems that build critical energy resources.  Society’s need for hydrocarbons and metals are among these resources.  However, petroleum and ore deposits are traditionally studied as two completely different disciplines in geoscience.  We argue that they share a common heritage, or at a minimum an intersection in that the source rocks for oil also present source rocks for metals in sedimentary basins. 

In this presentation, we demonstrate the value of merging the study and teaching of these two disciplines: petroleum geology and ore deposit geology associated with sedimentary basins.  We present several possibilities, for example, (1) the hydrothermal fluid may be the hydrocarbon-carrying fluid, and (2) mixing of a hydrocarbon-bearing fluid with a metalliferous brine may precipitate sulfide intermingled with oil.  The end locations for the two resulting resources, however, may be spatially displaced from one another. 

Using a petroleum discovery from the Barents Sea as an example, we will illustrate the intimacy between metal and hydrocarbon deposition, and we will show petrographically the episodic, locally catastrophic events that formed the two resources in the same space.  We will show critical relationships between replacement textures and explosive overpressure textures, the latter leading to capture of chalcedony-oil and barite-oil emulsions.  We will show sulfide veins with visible oil inclusions.  Sphalerite-galena-fluorite are all critical players.  Our results highlight poorly understood infusions of sphalerite, co-mingled with oil, residing in biogenic carbonate rocks. 

Further, from the perspective of ore geology, our interpretations challenge classic replacement textures in some ore-forming environments.  Seemingly abrupt changes in sulfide mineralogy, or the switch to oxide minerals, may be violent rupture of earlier sulfides by catastrophic fluid ingress and infilling with a new mineralogy – rather than passive replacement as is the common interpretation. 

Designing strategic sampling in these complex environments often requires many analyses to build a forest of persuasive evidence to inform exploration models.  Reliance on small or isolated data sets may lead to highly erroneous interpretations.  Application of Re-Os geochronology and trace element geochemistry places fluid compositions in a time context, useful in both petroleum and sulfide settings.  At the same time, this information distinguishes slow continuous deposition from small catastrophic events during construction of petroleum and ore systems.  Long-term investment of industry in resource-related research rewards all parties, with the common goal of meeting the needs of society and expanding the technologies that will give humanity a more sustainable future.  Cross-disciplinary approaches, marrying metals and hydrocarbons, will be essential for efficient exploration and advancement of resource knowledge. 

Funding – Partial funding for this project was provided by Lundin Energy Norway.  Colorado State University-Geosciences provides no funding for the personnel and operation of the AIRIE Program and its Re-Os laboratories. 

How to cite: Stein, H., Hannah, J., Rameil, N., and Pedersen, J. H.: Slow and Steady or Episodically Catastrophic?  Timescales and Processes for Hydrocarbon and Metallic Resource Development, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5712, https://doi.org/10.5194/egusphere-egu22-5712, 2022.

EGU22-6130 | Presentations | GMPV5.2

The Sesmarias massive sulfide discovery in Portugal (Iberian Pyrite Belt): preliminary geochemical and petrological studies 

Marta Codeço, Sarah Gleeson, Carlos Rosa, Paul Kuhn, Robert Trumbull, Philipp Weis, Anja Schleicher, Jessica Stammeier, and Franziska Wilke

The Iberian Pyrite Belt (IPB) in Portugal and Spain is a world-class metallogenic province that contains more than 1800 Mt of massive sulfide ore in over 100 deposits. The orebodies are hosted by submarine lithologies comprising felsic and mafic volcanic rocks and sedimentary units from the Volcanic-Sedimentary Complex (VSC) of Devonian-Carboniferous age. This study reports preliminary geological, mineralogical, and geochemical results from the Sesmarias prospect.

The Sesmarias VMS prospect is a blind discovery (~100 m of Tertiary cover) with the first lens intersected by drilling in 2014 (10.85 meters @ 1.81% Cu, 2.57% Pb, 4.38% Zn, 0.13% Sn, and 75.27 g/t Ag). Recent drilling has encountered 39.2 meters @ 0.44% Cu, 0.71 g/t Au, 27.1 g/t Ag, 2.07% Zn, and 0.79% Pb and 36.45 meters @ 0.72% Cu, 0.36 g/t Au, 0.82% Pb, and 21 g/t Ag in separate holes, and has extended the mineralization further to the SE. Through all phases of drilling, the company intersected copper-zinc massive sulfide mineralization in various lenses over a strike length of about 1.7 km; however, this value may easily increase with the continuation of the drilling program.

The Sesmarias massive sulfide system is heavily folded and strongly modified by several post-mineralization deformation events. The VSC at Sesmarias comprises black shales and felsic volcanics that are the primary hosts of the massive and semi-massive sulfide mineralization and a younger thick sequence of mafic volcanics (including intrusives) which overlap grey/green shales. Macroscopic observations complemented by petrographic studies and bulk rock chemistry of the volcanic rocks allowed to distinguish two main groups of volcanics rocks. The-mafic rocks are composed of plagioclase, relics of amphibole and pyroxene (±quartz), and are dominated by an alteration assemblage that includes chlorite, calcite, dolomite, epidote, (±quartz), and iron (hydro-)oxides. The felsic rocks include lavas and associated volcaniclastic rocks that are composed of quartz, plagioclase and are altered to muscovite ± chlorite. Compositionally, all major elements except for Na2O, K2O, and Al2O3, show roughly negative correlations with SiO2 and allow the discrimination of mafic from felsic rocks; however, the trends of magmatic differentiation are compromised due to secondary alteration. The results show that the VSC at Sesmarias is dominated by mafic rocks of basaltic composition (alkaline basalts) which are strongly spilitized. In contrast, the felsic rocks that host the mineralization are manly rhyodacites and dacites. Overall the magmatism at Sesmarias is more mafic in comparison with other mineralized areas such as Aljustrel and Neves Corvo, where the volcanism is predominantly rhyolitic.

How to cite: Codeço, M., Gleeson, S., Rosa, C., Kuhn, P., Trumbull, R., Weis, P., Schleicher, A., Stammeier, J., and Wilke, F.: The Sesmarias massive sulfide discovery in Portugal (Iberian Pyrite Belt): preliminary geochemical and petrological studies, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6130, https://doi.org/10.5194/egusphere-egu22-6130, 2022.

Bastnäsite [REE(CO3)F] is the main mineral of REE ore deposits in carbonatites. Synthetic bastnäsite-like compounds have been precipitated from aqueous solutions by many different methods but previous attempts to model magmatic crystallization of bastnäsite from hydrous calciocarbonatite melts were unsuccessful. Here we present the first experimental evidence that bastnäsite and two other REE carbonates, burbankite and lukechangite, can crystallize from carbonatite melt in the synthetic system La(CO3)F – CaCO3 – Na2CO3 at temperatures between 580 and 850 °C and pressure 100 MPa. The experiments on starting mixtures of reagent-grade CaCO3, Na2CO3, La2(CO3)3 and LaF3 were carried out in cold-seal rapid-quench pressure vessels. The studied system is an isobaric pseudoternary join of a quinary system where CO2 and fluorides act as independent components.  Liquidus phases in the run products are calcite, nyerereite, Na carbonate, bastnäsite, burbankite solid solution (Na,Ca)3(Ca,La)3(CO3)5 and lukechangite Na3La2(CO3)4F. Calcite and bastnäsite form a eutectic in the boundary join La(CO3)F – CaCO3 at 780 ± 20 °C and 58 wt% La(CO3)F. Phase equilibria in the boundary join La(CO3)F – Na2CO3 are complicated by peritectic reaction between Ca-free endmember of burbankite solid solution petersenite (Pet) and lukechangite (Luk) with liquid (L):

Na4La2(CO3)5 (Pet) + NaF (L) = Na3La2(CO3)4F (Luk) + Na2CO3 (Nc)

The righthand-side assemblage becomes stable below 600 ± 20 °C. In ternary mixtures, bastnäsite (Bst), burbankite (Bur) and calcite (Cc) are involved in another peritectic reaction:

2 La(CO3)F (Bst) + CaCO3 (Cc) + 2 Na2CO3 (L) = Na2CaLa2(CO3)5 (Bur) + 2 NaF (L)

Burbankite in equilibrium with calcite replaces bastnäsite below 730 ± 20 °C. Stable solidus assemblages in the pseudoternary system are: basnäsite-burbankite-fluorite-calcite, basnäsite-burbankite-fluorite-lukechangite, bastnäsite-burbankite-lukechagite, burbankite-lukechangite-nyerereite-calcite and burbankite-lukechangite-nyerereite-natrite. Addition of 10 wt% Ca3(PO4)2 to ternary mixtures resulted in massive crystallization of La-bearing apatite and monazite, and complete disappearance of bastnäsite and burbankite. Our results confirm that REE-bearing phosphates are much more stable than carbonates and fluorocarbonates. Therefore, primary crystallization of the latter from common carbonatite magmas is unlikely. Possible exceptions are carbonatites at Mountain Pass that are characterized by very low P2O5 concentrations (usually at or below 0.5 wt%) and extremely high REE contents in the order of a few weight percent or more. In other carbonatites, bastnäsite and burbankite probably crystallized from highly concentrated alkaline carbonate-chloride brines that have been found in melt inclusions and are thought to be responsible for widespread fenitization around carbonatite bodies.

This study was supported by RSF grant № 19-17-00013.

How to cite: Veksler, I., Nikolenko, A., and Stepanov, K.: Experimental study of phase equilibria between bastnäsite, burbankite and La phosphates in the system La(CO3)F – CaCO3 – Na2CO3 - Ca3(PO4)2 at 100 MPa, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6360, https://doi.org/10.5194/egusphere-egu22-6360, 2022.

EGU22-6717 | Presentations | GMPV5.2

Formation conditions for magnetite of phoscorites of the Tomtor massif (NE, Russia) 

Leonid Baranov and Alexander Tolstov

The Tomtor carbonatite complex with the area of 250 km2 is confined to the Eastern framing of the Anabar Anteclise. It is located in the Udja province of ultrabasic alkaline rocks and carbonatites (Northeast of Siberian Platform). The Tomtor apatite-magnetite deposit is located on the Northeastern border of the carbonatite core. Apatite-magnetite ores (camaforites, phoscorites, nelsonites) form a series of ore steeply dipping (75-80o) lenticular bodies of the Northwestern strike. The resources of the apatite-magnetite ores of the Tomtor massif are about 1 billion tons of iron (Tolstov, 1994).

The subject of research is magnetite with ilmenite decomposition structures, which composes up to 70% of phoscorite. The microprobe analysis established the compositions of 34 grains of magnetite isolated from the core of well No. 801; and ilmenite, which forms decomposition structures in these grains. Based on the compositions, the temperatures of their formation and oxygen fugacity were calculated.

Magnetite forms massive accumulations with hypidiomorphic crystals up to a few centimeters in size. Magnetite contains (in wt%): TiO2 (1,21-4,72), MnO (0,48-1,9), MgO (0,08-0,41); Cr2O3 (до 0,14); BaO (до 0,32); ZnO (0,06-0,53); V2O3 (0,25-0,52).

Ilmenite varies within a wide range in the content of hematite minal (2.15 - 62.19%), corresponding to the ilmenite-hematite trend on the diagram in the coordinates TiO2-Fe2O3-FeO. Ilmenite has a significant range of Mn contents (1.34-14); it may contain MgO (up to 1.57), Cr2O3 (up to 0.21), BaO (up to 1.09), ZnO (up to 0.2), V2O3 (up to 0.2).

It was established that the temperatures of magnetite formation create a continuous series from 459 to 914 ° C; oxygen fugacity (fO2) varies respectively in the range from -10 to -24. These data confirm the magmatic nature of magnetite.

Magnetite is the main and one of the highest-temperature minerals of the Tomtor phoscorites. Accordingly, the upper limit of the obtained temperatures is the minimum for fractionation of the P-Fe melt and characterizes the onset of crystallization of phoscorites.

The obtained results confirm the magmatic nature of the phoscorites of the Tomtor massif from the initial P-Fe melt with the participation of the crystallization differentiation mechanism and reaffirm the conclusions of previous studies based on the results of studies of the mineralogical-geochemical (thermo-barometric) and structural and textural features of apatite-magnetite ores (Baranov, 2018; Baranov, 2020).

References

  • Baranov L.N., Tolstov A.V. Typomorphic features of magnetite from tomtor massif camaphorites. Proceedings of higher educational establishments. Geology and Exploration. 2020;63(5):96—106. https://doi.org/10.32454/0016-7762-2020-63-5-96-106 (in Russian).
  • Baranov, L.N., Tolstov, A.V., Okrugin, A.V., & Sleptsov, A.P. (2018). New in mineralogy and geochemistry of apatite-magnetite ores of the Tomtor massif, northeast of the Siberian platform. Ores and metals, (2) (in Russian).
  • Tolstov, A.V., 1994. Mineralogy and geochemistry of apatite-magnetite ores of the Tomtor Massif (NorthwesternYakutia). Russ.Geol. Geophys.35,76–84.

How to cite: Baranov, L. and Tolstov, A.: Formation conditions for magnetite of phoscorites of the Tomtor massif (NE, Russia), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6717, https://doi.org/10.5194/egusphere-egu22-6717, 2022.

EGU22-7104 | Presentations | GMPV5.2

Formation of deep hydrothermal vein-type Mo greisen and base metal mineralization at the Sweet Home mine, Colorado (USA) 

Malte Stoltnow, Volker Lüders, Stefan de Graaf, and Samuel Niedermann

Deep hydrothermal Mo, W, and base metal mineralization at the Sweet Home mine (Detroit City portal) formed in response to magmatic activity during the Oligocene. Fluid inclusions in early-stage greisen quartz and fluorite precipitated from low- to medium-saline (1.5-11.5 wt.% equiv. NaCl), CO2-bearing fluids at temperatures between 360 and 415°C and at depths of at least 3.5 km. Stable isotope data indicate that greisen formation and base metal mineralization at the Sweet Home mine was related to fluids of different origins. Early magmatic fluids were the principal source for mantle-derived volatiles (CO2, H2S/SO2, noble gases), which subsequently mixed with significant amounts of heated meteoric water. Mixing of magmatic fluids with meteoric water is constrained by δ2Hw18Ow relationships of fluid inclusions. The deep hydrothermal mineralization at the Sweet Home mine shows features similar to deep hydrothermal vein mineralization at Climax-type Mo deposits or on their periphery. This suggests that fluid migration and the deposition of ore and gangue minerals in the Sweet Home mine was triggered by a deep-seated magmatic intrusion. The findings of this study are in good agreement with the results of previous fluid inclusion studies of the mineralization of the Sweet Home mine and from Climax-type Mo porphyry deposits in the Colorado Mineral Belt.

How to cite: Stoltnow, M., Lüders, V., de Graaf, S., and Niedermann, S.: Formation of deep hydrothermal vein-type Mo greisen and base metal mineralization at the Sweet Home mine, Colorado (USA), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7104, https://doi.org/10.5194/egusphere-egu22-7104, 2022.

EGU22-7751 | Presentations | GMPV5.2

Solubility of niobium in peralkaline silica-undersaturated melts at 750–850 °C, 100–200 MPa 

Anna Nikolenko, Christian Schmidt, and Ilya Veksler

Solubility and complexation data are necessary for understanding conditions for the formation of magmatic and hydrothermal ore deposits. The magmatic HFSE deposits imply high solubility of these elements in alkaline silicate melts, with the most important parameters being alkalinity, halogen and water contents, temperature of the magma, and silica activity. We have conducted a series of experiments on the solubility of Nb in alkaline silica-undersaturated melts. Experiments were carried out with using two synthetic silicate glasses with different Na/Al values: NAS4 (Na2O 26.0 %(m/m), Al2O3 12.5 %(m/m), SiO2 61.5 %(m/m)) with molar Na/Al = 3.36, and NAS2 (Na2O 20.9 %(m/m), Al2O3 17.8 % (m/m), SiO2 61.3 %(m/m)) with  Na/Al = 1.93.  The glasses were prepared from finely ground mixtures of quartz, aluminium oxide, and sodium carbonate. The mixtures were heated in a Pt crucible at 900 °C and subsequently at 1100 °C, and then crushed and remelted three times. Various amounts of Nb2O5 + glass (NAS4/NAS2) were placed in 1 cm long and 3mm wide Pt capsules and arc-welded shut. Then the capsules were placed in a cold-seal autoclave and run at 200 MPa and 750 °C for about 2 weeks. Rapid quench pressure vessels were used for experiments at 850 °C, 100 MPa, and run durations of 48 – 72 hours. In some runs, distilled water and/or CaF2, NaCl were added to the reactant mixtures. Experimental products were analyzed by EMPA.

Liquids in all experiments quenched to transparent glass with small (5-10 μm) euhedral crystals of NaNbO3 composition. These NaNbO3 crystals are the only solid phase at the liquidus. In low-temperature experiments (750 °C) using the highly peralkaline glass NAS4, the Nb solubility increases substantially with addition of water from 2.54 %(m/m) Nb2O5 at dry conditions up to 2.91 %(m/m) Nb2O5 at 5 %(m/m) H2O. The Nb solubility at dry conditions at 850 °C is higher in NAS4 in comparison with less alkaline NAS2 melt (3.72 %(m/m) Nb2O5 and 2.04 %(m/m) Nb2O5, respectively). Our data at 850 °C show that the solubility of Nb in the liquid increases significantly with the addition of water and NaCl for NAS4 (4.16 %(m/m) Nb2O5 and 4.35 %(m/m) Nb2O5, respectively) and for NAS2 (2.77 %(m/m) Nb2O5 and 2.17 %(m/m) Nb2O5). The effect of CaF2 addition on the Nb solubility was insignificant.

In conclusion, the Nb solubility in silica-undersaturated melts is already high at 750 °C, and increases substantially with temperature. It also increases strongly with Na/Al ratio in the melt, with the addition of water and NaCl, but not in the presence of CaF2. This suggests that chlorine, unlike fluorine, is a ligand strongly enhancing Nb solubility in alkaline silicate melts.

This work was supported by the Deutsche Forschungsgemeinschaft via SPP2238 grants SCHM2415/7-1 and VE 619/7-1.

 

 

How to cite: Nikolenko, A., Schmidt, C., and Veksler, I.: Solubility of niobium in peralkaline silica-undersaturated melts at 750–850 °C, 100–200 MPa, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7751, https://doi.org/10.5194/egusphere-egu22-7751, 2022.

EGU22-7854 | Presentations | GMPV5.2

Application of a comprehensive workflow to characterize the petrology and mineralogy of ore samples in 3D. 

Florian Buyse, Stijn Dewaele, Matthieu Boone, and Veerle Cnudde

Ore geology research conventionally relies on macroscopic and microscopic two dimensional (2D) observations of hand specimens and thin or polished sections. Although 2D techniques such as optical microscopy and scanning electron microscopy (SEM) are well-known and, therefore, commonly used for the characterization of ore samples, they are not capable of reproducing the real three-dimensional (3D) interior (Wang & Miller, 2020). A rising number of new developments in innovative characterization methods and data analysis methods in the field of ore geology research (e.g. Pearce et al., 2018; Warlo et al., 2021 & Guntoro et al., 2019) indicates the current necessity for adequate 3D ore characterization.

By combining X-ray micro-computed tomography (µCT) and SEM within a comprehensive workflow, we investigated a case study of the pegmatite-hosted Sn-Nb-Ta mineralization of the Gatumba area (Rwanda) (Dewaele et al., 2011). In this research, we present the possibilities to both visualize and quantify mineralogical data in 3D.

Automated mineralogy software within a SEM equipped with a field emission gun (Hrstka et al. 2018) served as an ideal tool to provide us the ground truth to interpret 3D µCT data. A new depth of information was obtained by describing the shape and orientation of individual minerals and the 3D inter-relationships between different mineral phases, by respectively using the Pearson correlation coefficient and the coefficient of variation. Additionally, relative elemental concentrations of niobium and tantalum for the solid-solution series columbite-tantalite and the concentration of economic interesting low atomic number elements (e.g. lithium) were deduced from µCT images.

The combination of SEM and µCT, within a lab-based workflow, enables the description of ore samples into 3D, which is especially important to provide representative mineral inter-relationships and quantitative estimations of economically interesting elements. Extending the potential of this technique to economic geology studies (e.g. core logging for exploration studies or to improve extraction procedures) will improve the sustainable management of ore deposits.

Acknowledgement
This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 101005611.

References
Dewaele et al., 2011. Late Neoproterozoic overprinting of the cassiterite and columbite-tantalite bearing pegmatites of the Gatumba area, Rwanda (Central Africa). Journal of African Earth Sciences 61(1): 10-26.

Guntoro et al., 2019. X-ray Microcomputed Tomography (μCT) for Mineral Characterization: A Review of Data Analysis Methods. Minerals 9(3): 183.

Hrstka et al., 2018. Automated mineralogy and petrology – applications of TESCAN Integrated Mineral Analyzer (TIMA). Journal of Geosciences 63(1): 47-63.

Pearce et al., 2018. Microscale data to macroscale processes: a review of microcharacterization applied to mineral systems. In Gessner, K., Blenkinsop, T. G. & Sorjonen-Ward, P. (eds), Geological Society, London, Special Publications 453(1): 7-39.

Wang & Miller, 2020. Current developments and applications of micro-CT for the 3D analysis of multiphase mineral systems in geometallurgy. Earth-Science Reviews 211: 103406.

Warlo et al., 2021. Multi-scale X-ray computed tomography analysis to aid automated mineralogy in ore geology research. Frontiers in Earth Science 9: 789372.

How to cite: Buyse, F., Dewaele, S., Boone, M., and Cnudde, V.: Application of a comprehensive workflow to characterize the petrology and mineralogy of ore samples in 3D., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7854, https://doi.org/10.5194/egusphere-egu22-7854, 2022.

EGU22-8165 | Presentations | GMPV5.2

The mineralizing fluids of the Santa Helena Breccia- a unique W deposit in the Iberian Peninsula 

Luís Lima, Alexandra Guedes, Iuliu Bobos, and Fernando Noronha

The Santa Helena Breccia (SHB) is a unique case of a collapse breccia with a late injection breccia in the Iberian Peninsula. The SHB is located in the NE Portugal in the contact between the Central Iberian Zone and the Galiza Trás os Montes Zone. This type of W deposit is a very uncommon example in the European Variscan Belt with only another similar deposit known, the Puy le Vignes in French Central Massif. The SHB is a sub-vertical structure, with an ellipsoidal shape with N-S major axis revealing at least 575 m in length, over 150 m in width, and at least 200 m in depth. This structural body occurs in the contact between synorogenic Variscan granites and metasedimentary rocks (Silurian in age). The lithological composition of the fragments is identical to the surrounding rocks cemented by quartz and lately cute by an injection breccia cemented by a leucocratic matrix. In the 60s of last century, a small exploitation of the SHB was performed in outcrops near two N-S subvertical quartz veins that limit SHB at east and west. The main goal of this study was to characterize and understand the behaviour of the mineralizing fluids in the breccia body.

The study of fluid inclusions in different types of quartz revealed the presence of four distinct types of fluids. The fluid 1 occurs in two phase aqueous fluid inclusions (FI) with an average salinity of 3.91 wt% Eq. NaCl, an average bulk density of 1.03 g/cc and an homogenization temperature (Th) between 250 to 300º C. Fluid 2 occurs in in three phase aqueous-carbonic FI with an average salinity of 5.93 wt% Eq. NaCl and an average bulk density of 1.07 g/cc. The lower entrapment temperature for fluid 2 was 250º C. Later in the SBH occur a fluid 3 which characterized by a lowest average salinity. The fluid 3 show an average salinity of 3.03 wt% Eq. NaCl and an average bulk density of 1.02 g/cc. The lowest Th of this fluid is 190ºC. A last fluid 4 shows an average salinity of 4.00 wt% Eq. NaCl and an average bulk density of 1.03 g/cc. This fluid was entrapped at the lowest temperatures (Th between 90º and 190ºC).

The FI results together with ore petrography showed that although the presence of four distinct fluids, two main ore stages occurred at SHB genetic model. The first one is characterized by the presence of the oxide minerals associated with fluids 1 and 2) and characterize the collapsing and the injection of the leucocratic rock into the SHB at higher temperature and pressure that were responsible for the W mineralization. After, a late stage where fluids 3 and 4 were responsible by a scarce sulfidic mineralization at lower pressure and temperature.  

Acknowledgements: The work was supported by the Portuguese Foundation for Science and Technology (FCT) project UIDB/04683/2020 - ICT (Institute of Earth Sciences). Lima, L is financed by FCT trough the PhD. scholarship SFRH/BD/144894/2019.

How to cite: Lima, L., Guedes, A., Bobos, I., and Noronha, F.: The mineralizing fluids of the Santa Helena Breccia- a unique W deposit in the Iberian Peninsula, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8165, https://doi.org/10.5194/egusphere-egu22-8165, 2022.

The Kayad Zn-Pb deposit in Ajmer, Rajasthan is a Proterozoic SEDEX deposit located in the Aravalli-Delhi fold belt of western India. The ore mineralization comprising predominantly of sphalerite and galena and subordinate chalcopyrite and pyrrhotite occurs in quartz mica schist (QMS), calc-silicate, quartzite and pegmatite, of which QMS hosts the majority of it. Other minerals such as arsenopyrite, lollingite and sulfosalts such as pyrargyrite, gudmundite and breithauptite are commonly associated with the massive ores in QMS.

The mineralization occurs as dissemination in calcsilicate and quartzite, in veins intruding pegmatite or on the wall rock of pegmatite, and occurs as lamination and massive ores in QMS. The laminated ores conform to the schistosity whereas the coarse, massive ores disrupt and overprint the metamorphic fabric. The massive sphalerite and galena (± chalcopyrite and pyrrhotite) ores are commonly associated with one or more of the hydrothermal minerals such as prehnite, Al-pumpellyite, albite and allanite replacing K-feldspar and plagioclase which indicates episode of Ca-Na metasomatism. On the other hand, pyrrhotite and chalcopyrite are mostly associated with chamosite, albite and potash-feldspar replacing other minerals in the host rock suggesting  -Fe-Na-K metasomatism. Sphalerite, galena, and arsenopyrite have been analysed by the SHRIMP SI ion microprobe for δ34S while multiple sulfur isotope (32S, 33S, 34S, and 36S) study has been attempted on pyrrhotite and chalcopyrite. δ34S of chalcopyrite (+6.4 to +8.8‰), pyrrhotite (+6.1 to +11.3‰) and arsenopyrite (+7.1 to +9.4‰) are relatively compact and consistent while sphalerite shows a larger variation from +2.7‰ to +8.9‰ across host rocks. Galena, however, shows the highest δ34S values ranging from +7.8 to +24.3‰. Such high variations for both sphalerite and galena can result partly from crystal orientation effect during analysis. Average ∆33S and ∆36S of pyrrhotite are -0.01±0.06‰ (2 S.D.) and 0.03±0.02‰ (2 S.D.) respectively that show no MIF-S signatures. However, in the case of chalcopyrite, a few ∆33S values deviate up to 0.33‰ from the mean of 0.11±0.15 (2 S.D.)‰.

Various microscale and mesoscale textures in massive sulfides, like attenuation of fold limbs of QMS and accumulation of sulfides at fold hinges, discrete blebs of galena and chalcopyrite in a matrix of sphalerite and extremely low dihedral angles among them, and prominent durchbewegung textures indicate the ores have been mobilized. Mineralogy (presence of sulfosalts) and geochemical analysis of the massive sulfides show enriched concentrations of low chalcophile elements like Ag, Sb, As, Bi, Se, Tl which indicate metamorphism-induced sulfide melting might have been an important process in migration of pre-existing ore. However, presence of hydrothermal alterations in close proximity with the mobilized massive ores suggests that fluid-mediated chemical mobilization also played a crucial role in such remobilization. Consistently high positive values of δ34S hint at a thermochemical reduction of seawater sulfate during SEDEX mineralization and recycling of the sulfur during remobilization that formed massive ores.

How to cite: Das, E., Pal, D. C., and Fu, B.: Hydrothermal alteration and multiple sulfur isotope chemistry of Kayad Zn-Pb deposit, Ajmer, Rajasthan, western India: Implications for ore genesis, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9098, https://doi.org/10.5194/egusphere-egu22-9098, 2022.

Lateritic Ni-Co deposits are supergene deposits that develop due to intense weathering of the underlying ultramafic parent rocks and/or their serpentinized equivalents under tropical to sub-tropical climatic conditions. These deposits are important sources of valuable products such as iron, aluminium, nickel and cobalt. On the other hand, they directly point out typical climatic conditions. In this regard, geochronological studies on these deposits are very valuable to determine the timing of these paleo-climatic conditions that is not only important for better understanding of the paleoclimate of a region but also implying the favourable weathering period that can be targeted in exploration of undiscovered lateritic deposits in a region. Although there are limited studies about absolute dating of lateritic Ni-Co deposits by Ar/Ar dating of Mn oxides, there is no study on application of (U+Th)/4He hematite geochronology to these deposits.

The main aim of this study is to apply hematite (U+Th)/4He dating to the well-preserved Çaldağ lateritic Ni-Co deposit in Western Turkey. In this regard, we sampled the different parts of the lateritic profile from the different laterite zones at the Çaldağ deposit. In addition, we determined the different phases of iron oxides in order to identify the primary hematite, formed during primary lateritization with the help of polished thin section analyses. Then, we applied Scanning Electron Microscopy (SEM) analysis and TESCAN Integrated Mineral Analyser (TIMA) mineral mapping to identify the suitable areas on primary hematites for (U+Th)/4He dating. Finally, we obtained credible (U+Th)/4He ages from the four selected hematites.

We detected primary hematites at the base of the lateritic profiles (transition between the limonite zone and altered serpentinite) that are only in-situ parts of the laterites exposed in two different pits in the deposit. The ages we obtained from the hematites indicate 501.5 ky, 205.8 ky, 175.4 ky and 63.4 ky that are getting younger at the direction of weathering and corresponding to the interglacial periods recorded for the surrounded region. The ages propose that although the main intensive lateralization period is suggested as Middle Eocene or Miocene, the weathering processes should have lasted until Quaternary by some interruptions (?) during interglacial periods. Permeability of the overlying limestone should have been enhanced by the active tectonics of the region that in turn caused progressive deeper weathering during humid (and warm?) climates at interglacial periods. Briefly, our results suggest that in contrast to the short-living lateritization model for lateritic Ni-Co deposits, they may have multi-stage weathering history throughout their long-lasting development.

 This study presents the first hematite (U+Th)/4He dating of lateritic Ni-Co deposits and demonstrates the reliable use of this method on these deposits after a careful selection of hematite samples. In addition, the study has implications on potential contribution of dating lateritic weathering on understanding the paleoclimate of a region. Finally, knowledge of the favourable paleoclimatic periods of weathering of a region may help in determining the potential areas on ultramafic exposures for discovering new lateritic deposits.

This study was supported by the Scientific and Technological Research Council of Turkey (Grant No: 120Y275)

How to cite: Gülyüz, N., Kuşcu, İ., and Danisik, M.: Application of (U+Th)/4He hematite geochronology to the Caldag lateritic Ni-Co deposit, Western Turkey: implications for multi-stage weathering events during interglacial periods, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11734, https://doi.org/10.5194/egusphere-egu22-11734, 2022.

EGU22-11806 | Presentations | GMPV5.2

Element redistribution by greisenization in rhyolite, Zinnwald/Cinovec 

Shilei Qiao, Timm John, and Anselm Loges

The Zinnwald/Cinovec Sn-W-Li deposit on the border between Germany and Czech Republic in the eastern part of Krušné Hory/Erzgebirge represents a fluorine-rich hydrothermal alteration of a granite-rhyolite association. The host rock can be divided into two parts: 1) zinnwaldite granite (upper part) with massive greisen body and various hydrothermal veins and 2) homogeneous protolithionite granite (lower part). The basement is the Krušné Hory/Erzgebirge crystalline complex with different metamorphic grades, overlain by the Teplice rhyolite, which also contains greisen veins and is the focus of this study.

In this study, we focus on the effects of fluid-rock interaction on distal rhyolites of the deposit. We combine whole rock chemistry with petrological data to constrain mass gain or loss of economically interesting elements. The samples were selected from the upper contact zone between granite and rhyolite. Three distinct zones of high- and low-degree greisenization (HG and LG) and albitization (A) developed with different textures, mineral assemblages and mineral compositions. Beyond the albitization zone, a continuous transition to the least altered rhyolite was observed. In the greisen part, the predominant minerals are quartz (~80 vol%) and topaz (~10 vol%) with minor biotite (~5 vol%). The albitization zone contains mostly albite (~40 vol%), quartz (~25 vol%), orthoclase (~25 vol%), and biotite (~10 vol%). In comparison to the composition of the rhyolite wall rock, mass balance calculations show that the greisen has 50%-100% loss of LILEs, 15%-20% loss of HREEs, and 7%-11% gain of LREEs.  The Th/U, Zr/Hf, Y/Ho, and La/Yb ratios are similar between the rhyolite and the greisen zone but very different for the albitization zone. This suggests a dynamic dissolution/precipitation process in the albitization zone caused by the particularly high F- and Na-activity in this zone compared to the unaltered rhyolite but also the greisen (where F is precipitated as topaz and fluorite whereas Na is lost to the fluid). The chemical changes show that the F-rich fluid carried LILEs and LREES to the greisen, and also resulted in the loss of HREEs and alkaline elements.

How to cite: Qiao, S., John, T., and Loges, A.: Element redistribution by greisenization in rhyolite, Zinnwald/Cinovec, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11806, https://doi.org/10.5194/egusphere-egu22-11806, 2022.

In porphyry copper deposits, where ore grades are low, the volume of the ore body determines its economic potential. However, the factors that control their size are still an open question and understanding them is crucial for finding new and large porphyry copper deposits (PCDs); especially in a society with an ever-increasing Cu demand. One of the most important, but highly debated size-modulating factors, time, could make the difference for a magmatic system to form small or large PCDs. The limited access to the plutonic roots of PCDs hinders our ability to study the plutonic and the porphyritic systems as a whole. However, Cenozoic tilting of the Yerington district (Nevada, USA) make it the perfect place for a key study as the Yerington batholith and associated volcanic sequences, porphyritic dikes and Cu mineralized centers are exposed. The complex upper-crustal batholith is comprised of three consecutive plutons that with time increase in silica content, granulometry and depth of emplacement while decreasing in volume: the McLeod quartz monzodiorite, the Bear quartz monzonite and the Luhr Hill granite with associated porphyritic dikes that formed Cu mineralization. Field observations show sharp intrusive contacts between the three plutons, until now have been interpreted as periods of magmatic quiescence that separate the emplacement of the three intrusions, overall accounting for 1 Ma of magmatic activity (Dilles & Wright, 1988; Schöpa et al., 2017). However, our new high-precision zircon U-Pb ID-TIMS dates spread over 2 Ma and show a continuum in zircon crystallization from the McLeod quartz monzodiorite and coeval volcanics to the Luhr Hill granite and porphyritic dikes with no hiatuses. In-situ trace element LA-ICPMS analyses on zircon further indicate a continuous geochemical evolution from intermediate compositions and higher Ti-in-zircon temperatures in the oldest zircons towards colder and evolved ones in the youngest ones, following normal fractional crystallization trends with the onset of titanite crystallization during evolution. These data argue for a sustained crystallization of the three main plutonic bodies. Our new lifetime of the magmatic system in view of zircon crystallization ages changes the previously defined thermal models for the Yerington district and affects how we assess its mineralizing potential. This questions the thermal budget of these upper crustal magma chambers, which should remain partially molten for about a million years to produce the observed zircon age spectra in each pluton. Such considerations open the discussion of zircon crystallization in the deep crust, reconciling these new high-precision data and the well-stablished field crosscutting relationships, and impacting the current understanding and application of zircon petrochronology in porphyry copper systems.  

 

John H. Dilles, James E. Wright; The chronology of early Mesozoic arc magmatism in the Yerington district of western Nevada and its regional implications. GSA Bulletin 1988; 100 (5): 644–652. 

Anne Schöpa, Catherine Annen, John H. Dilles, R. Stephen J. Sparks, Jon D. Blundy; Magma Emplacement Rates and Porphyry Copper Deposits: Thermal Modeling of the Yerington Batholith, Nevada. Economic Geology 2017; 112 (7): 1653–1672. 

How to cite: Castellanos Melendez, M. P. and Chelle-Michou, C.: Emplacement of the Yerington batholith and associated porphyry dikes, Nevada, USA: a conciliation challenge between field observations and high precision zircon petrochronology, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12753, https://doi.org/10.5194/egusphere-egu22-12753, 2022.

EGU22-2112 | Presentations | HS8.1.2

Effect of surfactant concentration on the decomposition rate of alkaline activated persulfate 

Pejman Abolhosseini, Thomas Robert, Richard Martel, and Satinder Kaur Brar

Hydrocarbon contamination is among the most frequent sources of soil and water environmental impacts. Many remediation methods have been implemented to clean up the contaminated environment so far. In-Situ Chemical Oxidation has attracted attention as it has shown efficiency in contaminants removal and cost-effectivity. In addition, soil washing by surfactant foam has been recently proven as a promising method. The combination of these two methods can take the advantage of oxidation while eliminating the challenges regarding the poor distribution of treatment fluid in a heterogeneous porous media. The ultimate goal of this study is to use surfactant foam for delivering oxidant (persulfate) through diesel-contaminated soil in permafrost. However, the interaction between the surfactant and the oxidant needs to be studied first. A better understanding of the impact of surfactants and oxidants on each other can lead to an optimized process. At the first stage of this study, different concentrations of surfactant solutions (sodium dodecyl sulfate: cocamidopropyl betaine in a mass ratio of 1:1) were mixed with a constant persulfate concentration activated with alkali, in absence of hydrocarbon. The preliminary results showed that the initial concentration of the oxidant has no significant effect on its decomposition rate. Also, as the concentration of surfactant was increased above the Critical Micellar Concentration (CMC), the persulfate decomposition rate decreased, likely due to the formation of micelles. However, as the micelles started to be destroyed, the decomposition rate of the oxidant increased gradually and the highest rate was observed when the concentration of surfactant was close to the CMC. When no micelle was left in the solution, the decomposition rate of the oxidant waned to a low value. Thus, coupling the surfactant and the oxidant can be effective for the degradation of hydrocarbon contaminants. Micelles bring part of the hydrocarbon into the aqueous phase and then the micelles are destroyed by the oxidant that can also degrade the hydrocarbon effectively over time.

How to cite: Abolhosseini, P., Robert, T., Martel, R., and Kaur Brar, S.: Effect of surfactant concentration on the decomposition rate of alkaline activated persulfate, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2112, https://doi.org/10.5194/egusphere-egu22-2112, 2022.

EGU22-2970 | Presentations | HS8.1.2

Effect of CO2-rich water injection on the hydromechanical properties of Pont Du Gard limestone 

Atefeh Vafaie, Jordi Cama, and Josep M Soler

CO2 storage in deep geological formations (e.g., saline aquifers) is essential for global warming mitigation. Storage of large amounts of CO2 in the saline aquifers results in acidification of the resident brine, inducing chemical reactions that change the pore structure of the host rock. Hence, the hydromechanical properties of the host rock are likely to alter, which affects the long-term injectivity and mechanical integrity of the reservoir.

To improve our understanding of the alteration of carbonate rocks after the injection of CO2, we have conducted percolation experiments under supercritical CO2 conditions. CO2-saturated water was injected at a constant rate of 0.15 mL/min through cylindrical core samples of Pont Du Gard limestone (diameter of 2.5 cm and length of ~5 cm) at 100 bar PCO2 and 60°C for 14 and 28 days. Fluid chemistry analyses were combined with X-ray microtomography imaging (XCMT) and porosity, permeability, and ultrasonic waves velocity (i.e., compressional and shear) measurements to assess the induced changes in rock properties.

Measured chemical parameters of the effluent solutions revealed rapid calcite dissolution correlating with 4% and 9.6% porosity enhancements for the 14-day and 28-day injections, respectively. Porosity enhancement affected mostly the inlet of the cores. Permeability increased by three orders of magnitude in both cases (from 10-14 to 10-11 m2). XCMT images disclosed that the substantial increase in permeability coincides with the formation of large wormholes along the cores, likely controlled by their intrinsic heterogeneity. Ultrasonic waves velocity measurements under ambient conditions demonstrated that the observed alterations in the pore structures degrade the mechanical stiffness of the rock by up to 40%. Our findings provide insight into the key role of natural heterogeneity in the reactivity of the rock and in the resulting evolution of its hydromechanical properties during CO2 storage.

How to cite: Vafaie, A., Cama, J., and M Soler, J.: Effect of CO2-rich water injection on the hydromechanical properties of Pont Du Gard limestone, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2970, https://doi.org/10.5194/egusphere-egu22-2970, 2022.

EGU22-3303 | Presentations | HS8.1.2

Evolution characteristics and model of nanosclae pores in organic-rich shale during thermal maturation 

Liangwei Xu, Lei Chen, Keji Yang, and Hao Wei

         Shale is an unconventional and complex oil-bearing system with the trinity of source, reservoir and cap. The coupling evolution of thermal maturation hydrocarbon generation, diagenesis and nanoscale porosity is the key scientific problem affecting the accumulation and accumulation of shale gas. In this research, the low matured marine shale of Mesoproterozoic Xiamaling shale in Zhangjiakou, Hebei were selected to conduct the thermal simulation experiments, then the pyrolysis products at each temperature point were recovered and were subject to an ongoing multidisciplinary analytical program. The simulation experiment results show that, in the process of simulated temperature increasing, the maturity of the shale sample is risen generally. the role of hydrocarbon expulsion of the shale at the same time, also to form the inner groove and the shrinkage hole edge groove organic matter more, side by side out of a large number of organic acid, the acid fluid for inorganic pore formation and evolution of simulated sample plays an important role in promoting, It also affects the diagenetic evolution of mud shale. Along with the hydrocarbon generation and expulsion, shale also forms a large number of internal multi-pore and contractive margin pores, and expel a large number of organic acids. These acidic fluids play an important role in promoting the generation and evolution of inorganic pores in the simulated samples, and also affect the diagenetic evolution process of shale.

        The increased temperature accelerates the dissolution of unstable brittle minerals and produces dissolution pores, promotes the transformation of clay minerals, and accelerates the formation and development of clay mineral pores. The nanoscale pore diameter did not change significantly during the simulation process, while the pore volume decreased first and then increased, reaching the minimum and maximum values at 350°C and 650°C, respectively. The surface area of micropores and mesoporous pores firstly decreased and then increased, reaching the minimum value at 350°C, while the surface area of macropores firstly increased and then decreased, reaching the minimum value and maximum value at 350°C and 650°C, respectively(Figure 1).

Figure 1. The pore volume and surface area variation characteristics of micropore (a,a'), mesopore(b, b'), macropore(c, c') during the increase of the thermal temperature.

         The diagenetic evolution during simulated temperature rise can be divided into four stages, and the main diagenetic types are dissolution, clay mineral transformation, thermal maturation hydrocarbon generation, compaction and recrystallization. In our research, the diagenetic evolution process and pore evolution model of shale were roughly divided, and the coupling evolution model of thermal mature hydrocarbon generation, diagenesis and pore structure of shale was established based on thermal simulation experiment (Figure 2).

Figure 2. Comprehensive diagram of the diagenetic evolution sequence and pore evolution model based on the hydrous pyrolysis experiment

 

         The coupling evolution model  provides qualitative and quantitative characterization and evaluation methods for hydrocarbon generation, diagenesis and nanoscale pore structure evolution of organic-rich shale. 

 

How to cite: Xu, L., Chen, L., Yang, K., and Wei, H.: Evolution characteristics and model of nanosclae pores in organic-rich shale during thermal maturation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3303, https://doi.org/10.5194/egusphere-egu22-3303, 2022.

EGU22-3823 | Presentations | HS8.1.2

Mobility of Fluopyram in soils under saturated flow conditions 

Mariana Vasconcelos Barroca and Gilboa Arye

A new generation of non-fumigant nematicides has recently been introduced and is essential to enable efficient and sustainable agricultural production. Fluopyram (FL) is a new compound with a novel mode of action and an improved safety profile. The aim of this study was to quantify the adsorption and transport of FL in 3 soils with different texture under increasing water flows. Initially, equilibrium adsorption isotherms were measured by batch method. Then, FL transport characteristics were analyzed by flowthrough experiments under saturated flow conditions in soil columns. A pulse input of FL was given together with Bromide (Br), used as a conservative tracer. The flowthrough experiments were performed with 3 different soil types, loamy sand, loam and clay under 3 water flow rates, 0.3, 1 and 4 ml min-1, then analyzed and simulated with the convection–dispersion equation (CDE). Equilibrium and kinetic reaction terms were employed to consider sorption of FL. The adsorption isotherms of FL exhibited linear behavior for all soils, with distribution coefficient (Kd) varying from 0.72 to 1.87 L Kg-1 for loam and clay respectively. The established breakthrough curves (BTCs) obtained for bromide exhibited a symmetrical pattern, regardless of soil texture and flow rates, with an average of 100% of Br recovered, suggesting that physical equilibrium is prevailing in all columns. The FL BTCs exhibited sharp increase in concentration after pulse input and long tailing during leaching phase, not fully completed after leaching for 17 pore volumes (PV). The experimental mass balance demonstrated a maximum of 90% recovery on sandy soil and a minimum of 79% in clayey texture. This might indicate that FL has fast adsorption on soil and slow desorption kinetics or even some irreversible adsorption. To understand better the processes affecting FL transport in soils, two models of solute transport were used, a Two-sites sorption model (TSM) and Two-kinetic sites model. When irreversibility was assumed, both models underestimated the tailing of BTCs, trending the curve to zero; showing that instead of irreversible desorption, the long-term leaching behavior is due to a very slow desorption rate. All the models could describe well the adsorption process and confirmed that part of FL has quick adsorption in soil which is in agreement with the low mobility observed. Further evaluation on FL transport characteristics and the adequacy of the different numerical model will be discussed. 

How to cite: Vasconcelos Barroca, M. and Arye, G.: Mobility of Fluopyram in soils under saturated flow conditions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3823, https://doi.org/10.5194/egusphere-egu22-3823, 2022.

EGU22-3964 | Presentations | HS8.1.2

A pore-scale study of bacterial chemotaxis with segregated and controlled nutrient sources 

Maximilian F. Stoll, Roman Stocker, and Joaquin Jimenez-Martinez

Natural porous systems, like soils and aquifers, are physically and chemically highly heterogeneous. Microorganisms inhabiting these environments are therefore exposed to heterogeneous fluid flow velocities and nutrient landscapes. Bacteria capable of biasing their motion to swim along chemical gradients – known as chemotaxis – profit from their ability to localize and navigate towards nutrient hot spots, such as soil aggregates or plant roots.
We propose a novel experimental microfluidic platform to study chemotaxis at the pore-scale, allowing full optical access to the pore space and simultaneously enabling control over the spatio-temporal availability of nutrients. The microfluidic device contains hydrogel features, acting as nutrient hotspots, embedded in a porous medium, made out of transparent polydimethylsiloxane (PDMS) pillars. Nutrients are transported by diffusion from the access channels through the hydrogel into the porous medium, where they are released. The generated nutrient gradients downstream of the hotspots under flow conditions drive the swimming of chemotactic bacteria.
This approach enables the study of subsurface processes at the pore-scale under more realistic conditions, and shed new light onto the influence of physical and chemical heterogeneity on bacterial dispersion and residence time in the subsurface.

Keywords: porous media, soil, chemotaxis, microfluidics, heterogeneity

How to cite: Stoll, M. F., Stocker, R., and Jimenez-Martinez, J.: A pore-scale study of bacterial chemotaxis with segregated and controlled nutrient sources, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3964, https://doi.org/10.5194/egusphere-egu22-3964, 2022.

EGU22-5191 | Presentations | HS8.1.2

Effect of chaotic advection generated by oscillatory flow on mixing-induced precipitation 

Guido Gonzalez-Subiabre, Daniel Fernàndez-Garcia, Michela Trabucchi, and Jesús Carrera

Chaotic advection can be created by engineered sequence of extraction and injection of groundwater in aquifers and by creating an engineered oscillatory flow. It has been used in a wide range of applications, including enhancement of degradation during aquifer remediation, in-situ leaching of metals to enhance mining recovery, and dissipation of energy in geothermal systems. Most of these works are based on numerical simulations and little experimental evidence are reported in the literature. In this work, we analyze how an engineered oscillatory flow can favor mixing-induced precipitation, increasing the total amount and the extension of precipitation zone, with the objective to provide new corrective measures based on permeability reduction. For instance, one can isolate a target aquifer region hydraulically by creating an impervious barrier in the mixing zone. Laboratory experiments were used to study the effect of chaotic advection on mixing-induced precipitation. The experiments were performed in a transparent horizontal two-dimensional tank made of plexiglass filled with glass beads. In the experimental investigation, two different chemical solutions containing CaCl and NaCO3 were injected in separate inlet ports with different concentration. oscillatory flow was created by tuning the inflow rate, we analyze the effect of different injection rates on precipitation. As a result, a calcite precipitate layer with different width was formed between the individual solutions. Color tracer tests were injected before and after the experiment to visualize the impact of precipitation.

How to cite: Gonzalez-Subiabre, G., Fernàndez-Garcia, D., Trabucchi, M., and Carrera, J.: Effect of chaotic advection generated by oscillatory flow on mixing-induced precipitation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5191, https://doi.org/10.5194/egusphere-egu22-5191, 2022.

EGU22-5286 | Presentations | HS8.1.2

Effect of radial geometry on autocatalytic reaction-diffusion-advection fronts 

Alessandro Comolli, Fabian Brau, and Anne De Wit

The understanding of the dynamics of reaction diffusion (RD) fronts is crucial for a wide variety of applications in chemistry, biology, physics and ecology, and it is especially important for hydrogeological problems involving chemical reactions. Reactive transport in geological media is generally controlled by the interplay of physical and chemical processes, which can give rise to complex dynamics of the reaction front. An important subset of RD fronts is represented by autocatalytic fronts, for which it is well known that the coupling of diffusion and chemical processes gives rise to self-organization phenomena and pattern forming instabilities [1]. When the initial interface between the reactant and the catalyst is a straight line, the autocatalytic front behaves as a solitary wave, which means that the shape of the front remains unchanged as it travels towards the nonreacted species [2]. The coupling with uniform advection does not change the picture, provided that the system is described in the proper comoving reference frame.

However, in this work we show that the geometrical properties of the injection source have a significant impact on the reaction front dynamics. Indeed, if the injection of one reactant into the other is performed radially at a constant flow rate, the pre-asymptotic dynamics of the front is strongly affected by the nonuniform velocity field. Moreover, although at long times the front still behaves as a solitary wave, the efficiency of the reaction is strongly increased in virtue of the increasing volume occupied by the radial front. We show how injecting a finite amount of reactant into the catalyst gives rise to collapsing fronts and we characterize their dynamics in terms of their position, width and the production rate. In contrast, when the reactant is injected into the catalyst at a constant flow rate, a stationary regime is reached where, unlike the case of solitary waves, the autocatalytic front does not move.      

 

References:

[1] I. R. Epstein and J. A. Pojman, An Introduction to Nonlinear Dynamics: Oscillations, Waves, Patterns, and Chaos (Oxford University Press, Oxford, 1998)

[2] P. Gray, K. Showalter, and S. K. Scott, J. Chim. Phys. 84, 1329 (1987)

How to cite: Comolli, A., Brau, F., and De Wit, A.: Effect of radial geometry on autocatalytic reaction-diffusion-advection fronts, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5286, https://doi.org/10.5194/egusphere-egu22-5286, 2022.

EGU22-6000 | Presentations | HS8.1.2

Forced air and water flow in porous media – Dynamics, Saturation degree, and phase distribution 

Ilan Ben-Noah, Shmulik P. Friedman, Brian Berkowitz, Juan J. Hidalgo, and Marco Dentz

Air saturation degree and flow pattern significantly affect physical, biological, and chemical processes in natural and industrial multiphase systems. However, despite long-standing and current research of multiphase flow, the predictive capabilities in conditions where unstable flow patterns prevail and their consequence on the phase distribution remain extremely limited.

We demonstrate the strong coupling between flow dynamics and phase saturation by analyzing experimental data of steady air injection into background (initially) saturated granular media. Next, we evaluate, using image analysis of recent multiphase experiments in microfluidic devices, the decoupled effect of the saturation degree on the micro-scale distribution of the phases.

We present a simple evaluation of the effects of the steady air flow velocity and of the media’s grain diameter on the macroscale air saturation degree. Using only two variables, one for the matrix (grain diameter) and one for the flow (air velocity), for estimating the air (and water) saturation degree seems to be an oversimplification, especially if one considers the complexity of the two-phase flow problem and the differences between flow patterns and geometries. Nevertheless, the suggested power-law model explains about 90% of the value of the phase saturation across a wide range of saturation degrees and different flow patterns and geometries. Moreover, analysis of this data set reveals a positive effect of both flow velocity and grain diameter on the air saturation degree. Using dimensional analysis, we conclude that viscous and buoyancy forces increase air saturation while capillary forces decrease the saturation degree. Our findings also suggest a significant effect of inertial forces on air saturation in coarse granular media (glass beads). The effect of phase saturation on the flow pattern is significant as deduced from the two extremum conditions of continuum air flow in dry media and predominant unstable flow in initially water-saturated media. However, the effects of the air saturation and flow dynamics cannot be easily evaluated as these are strongly correlated. Recent experimental studies of nearly simultaneous steady air and water injection into microfluidic devices allow a morphological analysis of the phase distribution (e.g., water-filled pore size distribution, coordination number distribution), decoupled from the flow dynamics, i.e., for different saturation degrees of the same capillary number and vice-versa.

Quantifying the impact of macroscale phase saturation and flow dynamics on microscale phase distribution will enable a better prediction of the flow patterns (at the different scales), the local flow velocity distribution, and the effective hydraulic characteristics of the media. In this context, this work, for example, can refine Buckingham’s “law” for different capillary equilibrium conditions.

How to cite: Ben-Noah, I., P. Friedman, S., Berkowitz, B., J. Hidalgo, J., and Dentz, M.: Forced air and water flow in porous media – Dynamics, Saturation degree, and phase distribution, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6000, https://doi.org/10.5194/egusphere-egu22-6000, 2022.

The kinetic interface-sensitive (KIS) tracer, relying on a zero-order reaction on the fluid-fluid interface, is a newly developed method to measure the fluid-fluid interfacial area (FIFA) in drainage processes. The concentration of the reaction product, obtained by measuring the water samples after the breakthrough, is interpolated with numerical model to determine the FIFA. However, a major limitation of the previous method is that the volume of available water sample is highly dependent on the sand type and the system parameters, and the measurement is not applicable when the water sample is not sufficient. An alternative is to apply the KIS tracer in the “push-pull” test, meaning the drainage process is followed by an imbibition process with the flow direction reversed. This study applies the pore-scale numerical simulation and the column experiment to study the KIS tracer reactive transport during a push-pull test. The breakthrough curve of the product concentration is interpolated with both macro-scale numerical model and a modified analytical solution for the push-pull process. It is found the shapes of the concentration breakthrough curves from the pore-scale simulations and the column experiments are fit, showing a non-linear descending trend with respect to time. The KIS tracer reactive transport process in the push-pull test and the validation of the measured FIFA from the concentration breakthrough curve, are demonstrated based on the pore-scale simulation results. Finally, for the (n-octane/water) displacement process in the column packed with the glass beads with diameter of 240 μm (at the capillary number of 5×10-7), the FIFA is measured 210 m-1 at the water saturation of 0.33, which is consistent with some literature data.

 

How to cite: Gao, H., Tatomir, A., Abdullah, H., and Sauter, M.: A push-pull kinetic interface-sensitive tracer method to quantify the fluid-fluid interfacial area in dynamic two-phase flow in porous media, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6606, https://doi.org/10.5194/egusphere-egu22-6606, 2022.

EGU22-8398 | Presentations | HS8.1.2

On the effect of probabilistic nucleation on the distribution of mineral precipitates in porous media 

Mohammad Masoudi, Mohammad Nooraiepour, and Helge Hellevang

The process of mineral precipitation and crystal growth begins with nucleation, which is usually overlooked in reactive transport simulators. Nucleation controls the location and timing of solid mineral formation in porous media. For an accurate prediction of the hydrodynamics of the porous medium after mineral precipitation, it is crucial to know the spatial distribution of stable secondary nuclei. We developed a novel probabilistic nucleation approach wherein induction time is treated as a random variable in order to better understand the nucleation process. The probabilistic induction time statistically spreads around the measured or reported induction time, either obtained from experiments or approximated by the exponential nucleation rate equation suggested by the classical nucleation theory (CNT). In this study, we used the classical nucleation theory. The location and time of nucleation are both probabilistic in our model, affecting transport properties at different time and length scales.

We developed a pore-scale Lattice Boltzmann reactive transport model incorporated with the new probabilistic nucleation model to investigate the effect of nucleation rate and reaction rate on the extent, distribution, and precipitation pattern of the solid phases. The simulation domain is a 2D substrate with an infinite source of the supersaturated solution. We use Shannon entropy to measure the disorder of the spatial mineral distributions. The results of the simulations show that all the reactions follow similar random behavior with different Gauss-Laplace distributions. The simulation scenarios start from a fully ordered system with no solid precipitation on the substrate (entropy of 0). Entropy starts to increase as the secondary phase precipitates and grows on the surface until it reaches its maximum value (entropy of 1). Afterward, the overall disorder declines as more surface areas are being covered, and eventually, entropy approaches a constant value. The results indicate that the slower reactions have longer windows of the probabilistic regime before entering the deterministic regime. The outcomes provide the basis for implementing mineral nucleation and growth for reactive transport modeling across time-scales and length-scales.

How to cite: Masoudi, M., Nooraiepour, M., and Hellevang, H.: On the effect of probabilistic nucleation on the distribution of mineral precipitates in porous media, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8398, https://doi.org/10.5194/egusphere-egu22-8398, 2022.

EGU22-9633 | Presentations | HS8.1.2

Dynamic instabilities caused by reaction-cross-diffusion waves in compacting porous media 

Manman Hu, Qingpei Sun, Christoph Schrank, and Klaus Regenauer-Lieb

Patterns in nature are often interpreted as a product of reaction-diffusion processes which result in dissipative structures. Thermodynamic constraints allow prediction of the final state with the dynamic evolution of the micro-processes refrained. Here we introduce a new micro-physics based approach that allows us to discover a family of soliton-like excitation waves - coupling the micro-scale cross-constituent interactions to the large scale dynamic behaviour of the open system. These waves can appear in hydromechanically coupled porous media under external loads. They arise when mechanical forcing of the porous skeleton releases internal energy through a phase change, leading to tight coupling of the pressure in the solid matrix with the dissipation of the pore fluid pressure. In order to describe these complex multiscale interactions in a thermodynamic consistent framework, we consider a dual-continuum system, where the large-scale continuum properties of the matrix-fluid interaction are described by a reaction-self diffusion formulation, and the small-scale release of internal energy by a reaction-cross diffusion formulation that spells out the macroscale reaction and relaxes the adiabatic constraint on the local reaction term in the conventional reaction-diffusion formalism. Using this approach, we recover the familiar Turing bifurcations (e.g., rhythmic metamorphic banding), Hopf bifurcations (e.g., Episodic Tremor and Slip), and present the new excitation wave phenomenon. The parametric space is investigated numerically and compared to  serpentinite deformation in subduction zones.

How to cite: Hu, M., Sun, Q., Schrank, C., and Regenauer-Lieb, K.: Dynamic instabilities caused by reaction-cross-diffusion waves in compacting porous media, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9633, https://doi.org/10.5194/egusphere-egu22-9633, 2022.

EGU22-10079 | Presentations | HS8.1.2

Complex Pattern Formation and Viscous Fingering Stabilization in Radial Flow 

Darío Martín Escala and Alberto Pérez Muñuzuri

Interfacial fluid instabilities are ubiquitous in Nature and are responsible for many important phenomena. In some cases, they play a constructive role like in the redistribution of energy in a system but, in some other cases, the role is destructive and may pose a serious threat to technical or industrial applications. In most cases, these fluids involve reactants that are known to modify the instability itself.

Fingering instabilities are special cases of fluid instabilities that occur when a high mobility fluid displaces a low mobility one [1]. Processes like enhanced oil recovery or other fluid displacements in porous media, such as chromatography, are examples in which the existence of fingering instability is crucial for the overall extraction performance. At a laboratory scale, these instabilities are studied in experimental arrangements known as Hele-Shaw cells. A particularity of these cells is that the flow inside them is representative of the flow in porous media.

In this work, we propose a chemical system likely to produce instabilities. We endow it with the appropriate chemical reactions at the interface that make it possible to control the activation or deactivation of the fingering instability at will. In particular, we consider two different fluids with different viscosities and analyze the displacement of one fluid by the other injected into a radial Hele-Shaw cell. We studied two different scenarios depending on which fluid is used as displacing/displaced solution [2].

In the first case, where the most viscous fluid displaces the less viscous one (initially stable configuration), pattern formation is observed when the characteristic flow and reactive timescales are similar. The patterns show complex dynamics in which fingers not only grow but move forward/backward. In the second case (initially unstable configuration), the unfavorable mobility ratio produces complex wormhole structures similar to those observed in dissolving rock fractures [3,4]. The displacement stabilizes when flow, diffusive, and reactive timescales are comparable.

We extensively characterized and numerically modeled both scenarios. Our results establish the basis to control fluid instabilities that may arise in a broad variety of contexts.  

REFERENCES:

[1] Homsy, G. M. (1987). Viscous fingering in porous media. Annual review of fluid mechanics, 19(1), 271-311.

[2] Escala, D. M., & Muñuzuri, A. P. (2021). A bottom-up approach to construct or deconstruct a fluid instability. Scientific reports, 11(1), 1-16.

[3] Szymczak, P., & Ladd, A. J. C. (2009). Wormhole formation in dissolving fractures. Journal of Geophysical Research: Solid Earth, 114(B6).

[4] Kalia, N., & Balakotaiah, V. (2007). Modeling and analysis of wormhole formation in reactive dissolution of carbonate rocks. Chemical Engineering Science, 62(4), 919-928.

How to cite: Escala, D. M. and Pérez Muñuzuri, A.: Complex Pattern Formation and Viscous Fingering Stabilization in Radial Flow, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10079, https://doi.org/10.5194/egusphere-egu22-10079, 2022.

The kinetic interface sensitive (KIS) tracers have been the focus of research in the past decade, as a new, reactive tracer method to estimate the interfacial area between immiscible fluids in porous media. We present here a novel experimental approach to measure the capillary associated fluid-fluid interfacial area using the KIS tracers in simultaneous two-phase flow conditions. The new approach is applied in a sand column filled with glass-beads (d50 = 170µm). Four laboratory experiments are performed in a simultaneous two-phase injection scheme using different fractional flow ratios (Flow rate of wetting phase: total flow rate). The different fractional ratios create different saturations inside the column, which correlate to different fluid-fluid interfacial areas. The new method, introduces also a new analytical method to handle reacted by-product concentration data acquired, different from the KIS tracer method in dynamic conditions. By comparing the results to other established techniques reported in the literature (i.e., interfacial partitioning tracer test and computed micro-tomography) used to measure fluid-fluid interfacial area we observe a good agreement.  The capillary associated interfacial area increases with decreasing wetting saturation until a maximum value, which then drops near the residual saturation. The maximum capillary associated interfacial area occurs at wetting saturation ranges between 0.45 < Sw < 0.6, which is slightly shifted towards the higher wetting saturation when compared to the other techniques. Furthermore, the results are simulated using a Darcy-scale reactive transport multiphase flow in porous media numerical model.

How to cite: Abdullah, H., Tatomir, A., and Sauter, M.: Experimental approach to measure capillary associated interfacial area using kinetic interface sensitive tracers in a simultaneous two-phase flow, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11132, https://doi.org/10.5194/egusphere-egu22-11132, 2022.

EGU22-11813 | Presentations | HS8.1.2

Experimental study of miscible Rayleigh-Taylor convection in a granular porous medium 

Shabina Ashraf, Jayabrata Dhar, François Nadal, Patrice Meunier, and Yves Méheust

More than 60% of greenhouse gas emissions are due to CO2 released from fossil fuels and industrial processes [1]. It is expected that by 2035, the expected increase in CO2 emissions will be 37.2 Gt/yr [2]. To reduce the resulting further adverse effects in climate changes, geological sequestration of CO2 provides an effective solution for carbon capture and storage (CCS) [2-4]. Dissolution trapping of CO2 in deep saline aquifers is a trapping mechanism that allows for long term storage. When CO2 is injected into the subsurface geological layers, the supercritical CO2 (sCO2) dissolves into the aquifer’s aqueous solution positioned below. The formation of a layer of CO2-enriched brine at the upper interface of the liquid domain results in unstable stratification which evolves into gravitational convection [2-5].

To evaluate the storage capacity and the efficiency of the trapping, it is necessary to understand the dynamics of the instabilities and convection, and the affect of granular media properties on them. To do so, we perform a 2D experimental study in a 3D granular medium and use Darcy scale simulations to complement our experimental findings [6]. Analog experiments are performed by using two miscible fluids with a density contrast between them. In doing so we decouple the gravitational instability process from the dissolution process; the latter is not modeled in our experiment. We match the refractive index of the fluids to that of the granular medium to allow for optical measurement of the concentration field. We observe that there is substantial difference in convection development time scales between the experimental results and the Darcy scale simulations performed with the experimental macroscopic parameters (porosity, permeability, dispersivity lengths, density contrast). We attribute this to the role played by pore scale heterogeneity of the velocity field, which cannot be predicted by Darcy scale models. This would suggest that Darcy scale simulations [2, 4,6] significantly overestimate the typical time scale of the convection.

[1] Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, IPCC 2014.

[2] Emami-Meybodi, H., Hassanzadeh, H., Green, C. P., & Ennis-King, J. (2015). Convective dissolution of CO2 in saline aquifers: Progress in modeling and experiments. International Journal of Greenhouse Gas Control, 40, 238-266.

[3] Bachu, S. (2008). CO2 storage in geological media: Role, means, status and barriers to deployment. Progress in energy and combustion science, 34(2), 254-273.

[4] Pau, G. S., Bell, J. B., Pruess, K., Almgren, A. S., Lijewski, M. J., & Zhang, K. (2010). High-resolution simulation and characterization of density-driven flow in CO2 storage in saline aquifers. Advances in Water Resources, 33(4), 443-455.

[5] Nadal, F., Meunier, P., Pouligny, B., & Laurichesse, E. (2013). Stationary plume inducedby carbon dioxide dissolution. Journal of Fluid Mechanics, 719, 203-229.

[6] Dhar, J., Meunier, P., Nadal, F. & Méheust, Y. (2021). Convection dissolution of CO2 in  2D and 3D porous media: the impact of hydrodynamic dispersion. Submitted to Physics of Fluids.

How to cite: Ashraf, S., Dhar, J., Nadal, F., Meunier, P., and Méheust, Y.: Experimental study of miscible Rayleigh-Taylor convection in a granular porous medium, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11813, https://doi.org/10.5194/egusphere-egu22-11813, 2022.

EGU22-12516 | Presentations | HS8.1.2

Identification of the leading role of pore structure in determining recovery during low salinity water flooding 

Edward Andrews, Alistair Jones, Ann Muggeridge, and Samuel Krevor

Low salinity water flooding is a promising enhanced oil recovery technique that has been observed, in experiments over a range of scales, to increase oil production by up to 14% in some systems. However, there is still no way of reliably predicting which systems will respond favourably to the technique. This shortcoming is partly because of a relative lack of pore scale observations of low salinity water flooding. This has led to a poor understanding of how mechanisms on the scale of micrometres lead to changes in fluid distribution on the scale of centimetres to reservoir scales. In this work, we present the first systematic comparison of the pore scale response to low salinity flooding across multiple sandstone samples. We use X-ray micro-CT scanning to image unsteady state experiments of tertiary low salinity water flooding in Berea, Castlegate, and Bunter sandstone micro-cores. We observe fluid saturations and characterise the wetting state of samples using imagery of fluid-solid fractional wetting and pore occupancy analysis. In the Berea sample, we observed an additional oil recovery of 3 percentage points during low salinity water flooding, with large volumes of oil displaced from small pores but also re-trapping of mobilised oil in large pores. In the Bunter sandstone, we observed 4 percentage point additional recovery with significant displacement of oil from small pores and no significant retrapping of oil in large pores. However, in the Castlegate sample, we observed just 1 percentage point of additional recovery and relatively small volumes of oil mobilisation. We observe a significant wettability alteration towards more water-wet conditions in the Berea and Bunter sandstones, but no significant alteration in the Castlegate sample. We hypothesise that the pore structure, specifically the connectivity of the largest pores in each sample, significantly affected production. This work gives the first pore scale insights into the role of pore geometry and topology on the mobilisation and retrapping of oil during low salinity water flooding.   

How to cite: Andrews, E., Jones, A., Muggeridge, A., and Krevor, S.: Identification of the leading role of pore structure in determining recovery during low salinity water flooding, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12516, https://doi.org/10.5194/egusphere-egu22-12516, 2022.

EGU22-13563 | Presentations | HS8.1.2

Convective dissolution of Carbon Dioxide in two- and three-dimensional porous media: the impact of hydrodynamic dispersion 

Yves Méheust, Jayabrata Dhar, Patrice Meunier, and François Nadal

Convective dissolution is the process by which CO2 injected in geological formations dissolves into the aqueous phase and thus remains stored perennially by gravity. It can be modeled by buoyancy-coupled Darcy flow and solute transport. The transport equation should include a diffusive term accounting for hydrodynamic dispersion, wherein the effective diffusion coefficient is proportional to the local interstitial velocity. We investigate the impact of the hydrodynamic dispersion tensor on convective dissolution in two-dimensional (2D) and three-dimensional (3D) homogeneous porous media. Using a novel numerical model we systematically analyze, among other observables, the time evolution of the fingers’ structure, dissolution flux in the quasi-constant flux regime, and mean concentration of the dissolved CO2; we also determine the onset time of convection, ton. For a given Rayleigh number Ra, the efficiency of convective dissolution over long times is controlled by ton. For porous media with a dispersion anisotropy commonly found in the subsurface, ton increases as a function of the longitudinal dispersion’s strength (S), in agreement with previous experimental findings and in contrast to previous numerical findings, a discrepancy which we explain. More generally, for a given strength of transverse dispersion, longitudinal dispersion always slows down convective dissolution, while for a given strength of longitudinal dispersion, transverse dispersion always accelerates it. Furthermore, systematic comparison between 2D and 3D results shows that they are consistent on all accounts, except for a slight difference in ton and a significant impact of Ra on the dependence of the finger number density on S in 3D.

How to cite: Méheust, Y., Dhar, J., Meunier, P., and Nadal, F.: Convective dissolution of Carbon Dioxide in two- and three-dimensional porous media: the impact of hydrodynamic dispersion, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13563, https://doi.org/10.5194/egusphere-egu22-13563, 2022.

The reduction of carbon dioxide concentration in the atmosphere has become an important objective to diminish the predicted exponential increase in global temperatures. A promising long-term solution is carbon capture, and sequestration (CCS), whereby CO2 is injected into saline aquifers containing high concentrations of divalent cations leading to the mineralization of carbonate salts. These precipitation reactions provide a potential long-term solution for storing and preventing reentry of this greenhouse gas into the atmosphere. Our study aims to understand the influence of the initial host solution composition on CCS. Using two glass plates separated by a thin gap (~1 mm), we steadily inject CO2 gas above an alkaline aqueous solution of either calcium chloride and/or magnesium chloride and monitor the convective uptake of CO2 and subsequent mineralization into calcium carbonate (e.g., calcite, aragonite, and vaterite), magnesium carbonate (e.g., hydromagnesite), or calcium magnesium carbonate (e.g., dolomite). The buoyancy-driven convective dynamics from the dissolution of CO2 is monitored using schlieren imaging techniques. In addition, a pH indicator in the initial metal salt solution shows its acidification from the continuous uptake of CO2. The mineral products are analyzed using X-ray diffraction, Raman spectroscopy and scanning electron microscopy to determine the composition, crystal structure, and crystal habit.

How to cite: Knoll, P. and De Wit, A.: The Effect of Calcium and Magnesium Ions on CO2 Convective Dissolution and Carbonate Precipitation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13570, https://doi.org/10.5194/egusphere-egu22-13570, 2022.

ERE5 – Process coupling and monitoring related to geoenergy applications

EGU22-16 | Presentations | ERE5.1

Statistical bounds on how induced seismicity stops 

Ryan Schultz, William Ellsworth, and Gregory Beroza

Earthquakes caused by human activities receive scrutiny due to the risks and hazards they pose.  Seismicity that occurs after the causative anthropogenic operation stops has been particularly problematic – both because of high-profile cases of damage caused by this trailing seismicity and due to the loss of control for risk management.  With this motivation, we undertake a statistical examination of how induced seismicity stops.  We borrow the concept of Båth’s law from tectonic aftershock sequences.  Båth’s law anticipates the difference between magnitudes in two subsets of seismicity as dependent on their population count ratio.  We test this concept for its applicability to induced seismicity, including ~80 cases of earthquakes caused by hydraulic fracturing, enhanced geothermal systems, and other fluid-injections with clear operational end points.  We find that induced seismicity obeys Båth’s law: both in terms of the magnitude-count-ratio relationship and the power law distribution of residuals.  Furthermore, the distribution of count ratios is skewed and heavy-tailed, with most earthquakes occur during stimulation/injection.  We discuss potential models to improve the characterization of these count ratios and propose a Seismogenic Fault Injection Test to measure their parameters in situ.  We conclude that Båth’s law quantifies the occurrence of earthquake magnitudes trailing anthropogenic operations.

How to cite: Schultz, R., Ellsworth, W., and Beroza, G.: Statistical bounds on how induced seismicity stops, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-16, https://doi.org/10.5194/egusphere-egu22-16, 2022.

EGU22-2160 | Presentations | ERE5.1

Identification of The Processes Triggering Induced Seismicity at the Enhanced Geothermal System of Basel (Switzerland) 

Auregan Boyet, Silvia De Simone, and Vìctor Vilarrasa

Felt induced seismicity compromises the public perception on the deployment of geothermal power-plants in urban areas. Large induced earthquakes have led to the shutdown of Enhanced Geothermal Systems (EGS), such as Basel (Switzerland) and Pohang (Republic of Korea). In the majority of induced seismicity cases in EGS, the largest events occur after shut-in. Different mechanisms can trigger induced seismicity. Pore pressure diffusion is established as the most common triggering mechanism. It reduces the effective normal stress acting across pre-existing fault surfaces, weakening the shear resistance and allowing slip of faults. However, this is not the only triggering mechanisms and it cannot explain the large magnitude of post-injection induces seismicity. Additional influencing processes are poromechanical elastic stressing, shear stress transfer and local tectonic settings. Considering theses mechanisms simultaneously can provide a better understanding of the causes of post-injection seismicity and could allow to develop strategies to mitigate the occurrence of earthquakes with high magnitude. To explain these processes, we investigate the induced seismicity that led to the closure of the Basel EGS project. We set-up a hydro-mechanical finite element numerical model which contains faults corresponding with the clusters of induced events at Basel. We study the reactivation of these pre-existing fractures using a viscoplastic model. We are able to identify the process combinations bringing faults to failure. During injection, faults fail due to pore pressure diffusion in the vicinity of the well, and due to poroelastic stressing further in the reservoir. After the injection shut in, poroelastic stressing and shear stress transfer trigger seismicity, being the most relevant triggering mechanisms of post-injection induced seismicity.

How to cite: Boyet, A., De Simone, S., and Vilarrasa, V.: Identification of The Processes Triggering Induced Seismicity at the Enhanced Geothermal System of Basel (Switzerland), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2160, https://doi.org/10.5194/egusphere-egu22-2160, 2022.

Occurred in the Delaware Basin, western Texas, near the town of Mentone, the Mw 5.0 Mentone earthquake is one of the largest induced earthquakes in the central US. Within 25 km of the epicenter, there are a few deep injection wells to the northwest injecting in the high permeable limestone layer at about 22 km averagely, as well as a lot of shallow wells injecting in the upper high permeable sandstone layer at around 18 km averagely. Between the shallow sandstone and deep limestone layers is a thick shale layer with low permeability, which excludes the possibility of downward percolation of the injected fluid in the shallow injection layer. However, the cumulative injection volume of shallow injection wells is about five times as much as that of deep injection wells. Motivated by this, we investigate whether the shallow injection wells may play a role in triggering the Mw 5.0 Mentone earthquake through the injection-induced coupled poroelastic stress perturbations. We first perform focal mechanism inversion and earthquake relocation with the Cut and Paste (CAP) and hypoDD methods, respectively, to constrain the fault plane on which the Mw 5.0 event occurred. A south-facing fault plane with strike/dip of 81o/52o is successfully fitted. We then calculate the change of the Coulomb failure stress (ΔCFS) caused by the shallow injection wells at the mainshock location based on the linear fully coupled poroelastic stress model. The calculated ΔCFS of shallow injection wells is approximately 20 kPa and it is mostly contributed by the change in coupled poroelastic stress. Based on findings from other studies, this value of ΔCFS is sufficient in reactivating faults that are well aligned with the local stress field. Since we only account for about half of the total injection volume from the shallow wells in the calculation, we also hypothesize that the actual perturbations caused by shallow injection wells via the coupled poroelastic stress change would be more prominent. Our result reveals the vital role of injection-induced coupled poroelastic stress in triggering seismicity, especially in low permeable geologic settings.

How to cite: Tan, X. and Lui, S. K. Y.: The non-negligible contribution of shallow injection wells on the triggering of the Mw 5.0 Mentone earthquake via coupled poroelastic stress perturbations, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3271, https://doi.org/10.5194/egusphere-egu22-3271, 2022.

EGU22-4117 | Presentations | ERE5.1

Acoustic Precursors to Laboratory Induced Fault Slip and Failure 

Aukje Veltmeijer, Milad Naderloo, and Auke Barnhoorn

With human activities in the subsurface increasing, so does the risk of induced seismicity. For mitigation of the seismic hazard and limiting the risk, monitoring and forecasting are essential. A laboratory study was performed to find precursors to fault failure. In this study, Red Pfaelzer sandstones samples were used, which are analog to the Groningen gas reservoir sandstones. A saw-cut fault was cut at 35 degrees, and the samples were saturated. Fault slip was induced by loading the sample at a constant strain rate, and simultaneously active acoustic transmission measurements were performed. Every 3 seconds 512 S-waves were sent, recorded, stacked to reduce the signal-to-noise ratio, and analyzed. The direct seismic wave velocity, coda wave velocity, and transmissivity were monitored before and during the reactivation of the faulted samples. Different loading patterns and confining pressures were investigated in combination with active acoustic monitoring. Velocity and amplitude variations were observed before the induced fault slip and can be used as precursory signals. Two methods to determine changing velocities were used. Direct S-wave velocities are compared to velocity change obtained by coda wave interferometry. Both analyses gave similar precursory signals, showing a clear change in slope, from increase to decreasing velocities and amplitudes prior to fault reactivation. Fault reactivation is preceded by fault creep and the destroying of some of the asperities on the fault plane, causing the seismic wave amplitude and velocity to decrease. Combining all precursors, the onset of fault slip can be determined and therefore upcoming slip can be forecasted in a laboratory setting. Our results show precursory changes in seismic properties under different loading situations and show a clear variation to the onset of fault reactivation. These results show the potential of continuous acoustic monitoring for detection and forecasting seismicity and help the mitigation of earthquakes.

How to cite: Veltmeijer, A., Naderloo, M., and Barnhoorn, A.: Acoustic Precursors to Laboratory Induced Fault Slip and Failure, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4117, https://doi.org/10.5194/egusphere-egu22-4117, 2022.

EGU22-4177 | Presentations | ERE5.1

Fault reactivation process in the laboratory: The role of stress cycling and pressurization rate 

Milad Naderloo, Aukje Veltmeijer, and Auke Barnhoorn

Over the last few decades, it has become apparent that different human activities in the subsurface, such as water waste injection, hydraulic fracturing, and geothermal energy production can lead to induced seismicity. Understanding the effects of fluid injection-related parameters on seismic response or evolution of it is essential for finding a method to manage and minimize the induced seismicity risk. Experimental and numerical studies indicate that varying injection patterns and rates can be used to effect and/or mitigate seismicity. However, most of the studies are for intact rock medium, and the mechanism of injection-induced seismicity of faulted rock medium is not clear yet. In this study, we performed fault reactivation experiments on faulted (saw-cut) Red Pfaelzer sandstones to provide new insight into the effect of stress/pressure cycling and rate on fault slip behavior and seismicity evolution. The saw-cut samples were subjected to two different reactivation mechanisms: 1) stress-driven and 2) injection-driven fault reactivation. Three different reactivation scenarios were performed during the stress-driven fault reactivation experiments: continuous sliding, cyclic sliding, and under-threshold cycling sliding. Ten AE transducers were used to detect microseismicity during the fault reactivation experiments, and consequently, different microseismic parameters, such as frequency-magnitude distribution (b-value), AE energy, and AE rate were estimated. Stress-driven fault reactivation experiments showed that (i) a below-threshold cycling scenario prevents seismicity and pure shear slip; however if the shear stress exceeds the previous maximum shear stress, seismicity risk increases drastically in terms of b-value, maximum AE energy, and magnitude. (ii) Compared to continuous sliding, cyclic sliding triggers less seismicity in terms of total b-value and large AE events due to the uniform reduction in roughness and asperity on the fault plane. (iii) By increasing the number of cycles, in general, the number of generated events and AE energy per cycle is reduced. Nevertheless, there is a risk of generating large AE events during the first cycles. In addition, results from the injection-driven fault reactivation experiments demonstrated that high injection rate results in higher peak slip velocity. Compared to the stepwise injection pattern, the cyclic recursive injection scenario showed higher peak slip velocity, due to the high hydraulic energy budget and fault compaction. A proper injection strategy needs to consider various factors, such as fault drainage, critical shear stress, injection rate, and injection pattern (frequency and amplitude). Our results demonstrate that selecting proper stress/pressure amplitude, and pressurization rate for the injection design strategy can help to reduce seismicity risk.  

How to cite: Naderloo, M., Veltmeijer, A., and Barnhoorn, A.: Fault reactivation process in the laboratory: The role of stress cycling and pressurization rate, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4177, https://doi.org/10.5194/egusphere-egu22-4177, 2022.

EGU22-4204 | Presentations | ERE5.1

Injection-rate control on deformation and stress of an experimental fault in granite 

Yinlin Ji, Lei Wang, Hannes Hofmann, Grzegorz Kwiatek, and Georg Dresen

In this study, we conducted injection-driven shear tests on a sawcut fault in granite samples using a triaxial deformation apparatus. The granite samples were drilled from Odenwald basement rocks in Germany. The sawcut fault, inclined 30° to the sample axis, was ground using sandpaper with a particle size of 201 µm. Two boreholes (nominal diameter 1.8 mm) were drilled near the short edge of each sample half to allow direct fluid access to the fault surface. Eight strain gauges, and eight pairs of acoustic emission (AE) sensors attached on the sample surface were used to monitor the deformation, local strain and AE events. 

During the experiments, we first measured the peak shear strength of the faulted sample by advancing the axial piston at a constant rate of 1 µm/s under 36 MPa confining pressure and 1 MPa pore pressure. We then adjusted the shear stress to be 90% of the peak shear strength. Subsequently, the piston was fixed, and the first injection-driven shear test was initiated by injecting distilled water from the bottom borehole at a rate of 0.2 mL/min. We observed three full cycles of fast slip events until the injection pressure was increased up to approximately 18 MPa. We then reduced the pore pressure to the initial 1 MPa and the axial force was removed, followed by the second injection-driven shear test conducted at a higher injection rate of 0.8 mL/min using the same procedure as in the first test. We also observed three episodes of fast slip events until the injection pressure was increased to about 20 MPa. Fluid pressures were monitored continuously at the top and bottom boreholes. We employed a COMSOL model to obtain the time-dependent fluid pressure distribution along the sawcut fault during fluid injection.

For slow fluid injection, we find that the fault surface near the center experiences slight normal dilation and gradual shear stress release prior to the fast slip event. In contrast, for high-rate fluid injection, the same fault patch exhibits normal compaction and shear stress increase preceding fast slip. In both cases, significant normal dilation and abrupt shear stress drops were observed near the fault center during fast slip events. The distinct evolution of local fault deformation and stress are likely attributed to the distribution of slow slipping patches, as signified by the fluid pressure distribution and Mohr-Coulomb failure envelope. At slow injection rate, slow precursory slip may have occurred on the entire fault, initiating a fast slip event. In contrast, at higher rates, slow slip may have been localized around the injection port, resulting in local stress concentration beyond the slow slipping patch. Our results demonstrate that the evolution of local fault deformation and stress can be diverse in different fault patches, depending on the relative location to the fluid pressurized zone and the resulting slow slipping patch. This suggests that the strongly heterogeneous fault deformation should be considered when analyzing the precursors to injection-induced fault reactivation.

How to cite: Ji, Y., Wang, L., Hofmann, H., Kwiatek, G., and Dresen, G.: Injection-rate control on deformation and stress of an experimental fault in granite, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4204, https://doi.org/10.5194/egusphere-egu22-4204, 2022.

EGU22-4703 | Presentations | ERE5.1

The DEEP Project: Innovation for De-Risking Enhanced Geothermal Energy Projects 

Federica Lanza and Stefan Wiemer and the DEEP team

The Swiss Energy Strategy 2050 anticipates that by 2050 up to ~7% of the future energy production will come from deep geothermal energy. Likewise, many other countries worldwide are investigating the potential of harnessing deep geothermal energy as a renewable solution. However, seismic risk reduction and reservoir efficiency is the current major coupled problem faced by Enhanced Geothermal System (EGS) reservoirs. Balancing risk and economic output is a key requirement in all EGS projects. The DEEP (Innovation for De-risking Enhanced geothermal Energy Projects) project is an international collaboration whose research-goal is to establish a full-scale protocol for real-time monitoring and risk analysis of potential seismicity triggered by EGS operations. To this end, the project will employ innovative seismic sensors, improved event-cataloguing techniques, fully probabilistic data-driven seismicity forecasts, and loss assessment strategies. In DEEP we plan to apply the so-called Adaptive Traffic Light System (ATLS) where forecasts are continuously updated with real-time data-feeds, providing an integrated and dynamic assessment of the seismic risk to the operators. Field test sites include the Frontier Observatory for Research in Geothermal Energy (FORGE) in Utah (USA), as well as at EGS sites in Germany and France. Parallel to the technology development, the project aims also at defining the next-generation good-practice guidelines and risk assessment procedures in order to reduce commercial costs and enhance the safety of future projects. Here, we will present an overview of the DEEP project to provide a framework for other DEEP presentations. We will also showcase a selection of results from new event detection and location algorithms based on machine learning and using Distributed Acoustic Sensing (DAS), as well as the results from a pilot test of the ATLS workflow for seismicity forecast models for the upcoming FORGE stimulation strategy.

How to cite: Lanza, F. and Wiemer, S. and the DEEP team: The DEEP Project: Innovation for De-Risking Enhanced Geothermal Energy Projects, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4703, https://doi.org/10.5194/egusphere-egu22-4703, 2022.

EGU22-5332 | Presentations | ERE5.1

Thermal stressing is likely to reactivate distant faults in hot sedimentary aquifers 

Iman Rahimzadeh Kivi, Estanislao Pujades, Jonny Rutqvist, and Victor Vilarrasa

The widespread development of geothermal energy is deemed to accelerate the transition to a low-carbon future. Hot Sedimentary Aquifers (HSA) provide cost-effective and non-intermittent geothermal resources. However, HSA development has reportedly been associated with seismic events, harming the public perception of exploiting these resources. This work digs deeper into thermo-hydro-mechanical (THM) mechanisms raised by water circulation in a HSA and their control on fault reactivation. We numerically simulate the problem by a 2D plane-strain model. The model consists of a porous and permeable hot aquifer sandwiched between the tight seal and base rocks and laterally bounded by two normal faults, representative of extensional tectonic environments. The horizontal injection-production well pairs are spaced 500 m apart at the middle of the aquifer, and the faults are located on each side of the doublet at a distance of 1 km. We consider two scenarios: low-permeability faults, mimicking a compartmentalized reservoir, and high-permeability faults, across which fluid flow takes place with further ease. We show that the fault permeability governs the hydraulic response of the reservoir. While the pore pressure slightly increases around the injector and decreases around the producer for the case of high-permeability faults, the compartmentalized reservoir experiences a global pore pressure decline. The latter is supported by the fact that the injected cold water is denser than the extracted hot water and occupies less space in the pore system. As soon as the thermal breakthrough occurs, which is after 12 years in the current setting, a more uniform temperature distribution across the doublet is established and the pressure begins to increase in the vicinity of the injector. Provided the high permeability of the reservoir rock, pore pressure and poroelastic stress perturbations impose rapid but minor effects on the fault stability. On the contrary, the cooling front formed around the injector lags much behind the pore pressure front toward the fault. The reservoir cooling contracts the rock and triggers stress reductions. Thermal stresses are transmitted much ahead of the cooled region and destabilize the fault located on the injection side. The fault begins to slip after 18 and 21 years of circulation for the high- and low-permeability scenarios, respectively. The reservoir pressure decrease in the latter case, attenuating the fault slip tendency, feeds into the observed difference in reactivation timings. Although thermal stresses initiate the slip, the static stress transfer jointly contributes to rupture nucleation along the fault. Interestingly, the slip-induced shear stress release, tied to a slip weakening frictional behavior, slows down elastic energy build-up on the other fault closer to the production well and impedes its reactivation. Our findings on the prolonged but dominant role of thermal stresses on the reactivation of distant faults have direct implications for safe and long-term production from geothermal systems.

How to cite: Rahimzadeh Kivi, I., Pujades, E., Rutqvist, J., and Vilarrasa, V.: Thermal stressing is likely to reactivate distant faults in hot sedimentary aquifers, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5332, https://doi.org/10.5194/egusphere-egu22-5332, 2022.

EGU22-5398 | Presentations | ERE5.1

Characterizing induced seismic events in the Groningen gas field using an efficient Hamiltonian Monte Carlo sampler: a case study 

La Ode Marzujriban Masfara, Cornelis Weemstra, and Thomas Cullison

In May 2019, an earthquake with a magnitude of 3.4 (local magnitude) hit the area of the Westerwijtwerd village in the province of Groningen, the Netherlands. The event is the result of the gas extraction in the Groningen gas field and is one of the largest events to date. To better understand the source characteristics of the event, we apply a probabilistic full-waveform inversion technique that we recently developed to the event's recordings. Specifically, we use a variant of the Hamiltonian Monte Carlo (HMC) algorithm. When sampling high-dimensional model spaces, HMC is proven to be more efficient than the generic Metropolis-Hasting algorithm. Compared to probabilistic inversions of tectonic events, two main challenges arise while applying the algorithm. First, the prior information of the event is usually incomplete and inaccurate. That is, the only available information is (an estimate of) the hypocenter and origin time. Second, the frequency content of the induced event's seismograms is higher than that of typical tectonic events. This implies a higher non-linearity, which in turn complicates the ability of a probabilistic inversion algorithm to sample the model spaces, particularly when considering the first challenge. Consequently, to address both challenges, first, we develop a procedure to estimate the necessary prior information and use it as input to the HMC variant. Second, we run our HMC algorithm iteratively to mitigate the non-linearity. Using the relatively detailed velocity model of the Groningen gas field, we eventually estimate ten posteriors of the source parameters. The latter being the hypocenter (three parameters), the moment tensor (six independent parameters), and the origin time.  

How to cite: Masfara, L. O. M., Weemstra, C., and Cullison, T.: Characterizing induced seismic events in the Groningen gas field using an efficient Hamiltonian Monte Carlo sampler: a case study, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5398, https://doi.org/10.5194/egusphere-egu22-5398, 2022.

EGU22-5536 | Presentations | ERE5.1

Modeling of injection-induced seismicity in fractured rock masses with TOUGH3-seed hybrid solver 

Federico Ciardo and Antonio Pio Rinaldi

Injection of fluid in fractured reservoirs triggers seismicity that migrates away from injection point. The enlarging cloud of (micro-)seismicity can be driven by pore-fluid diffusion within fractured rock mass, thus propagating in space proportional to square root of time for an effective isotropic and homogenous medium, or by elastic-stress interactions between over-stressed pre-existing fractures.

In this contribution we adopt an hybrid approach to model seismicity evolution driven by pore-fluid propagation into a Discrete Fracture Network and apply it to a large-scale injection experiment at FORGE Test Site in Utah (USA). We couple a statistical seed model for seismicity with a physic-based solver for non-linear pore-fluid diffusion into a three-dimensional DFN (using TOUGH3). Local inelastic permeability changes mimick irreversible deformations and affect pore-fluid evolution and hence seismicity cloud.

Several synthetic catalogs are generated and compared with one generated with a pure physic-based numerical solver.

 

How to cite: Ciardo, F. and Rinaldi, A. P.: Modeling of injection-induced seismicity in fractured rock masses with TOUGH3-seed hybrid solver, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5536, https://doi.org/10.5194/egusphere-egu22-5536, 2022.

EGU22-5576 | Presentations | ERE5.1

Deciphering fluid extraction-induced earthquake nucleation in Groningen under rate-strengthening friction 

Meng Li, Andre R Niemeijer, Femke C Vossepoel, and Ylona van Dinther

Induced seismicity triggered by fluid injection or extraction has been studied extensively in recent years. However, models relying on a Mohr-Coulomb yield criterion for interseismic loading or using a linear slip-weakening friction law for dynamic earthquake rupture cannot quantify well how much aseismic slip accumulates prior to nucleation or how to explain nucleation. Instead, a rate-and-state friction law is extensively utilized in earthquake cycle models to resolve and understand earthquake nucleation. Moreover, laboratory experiments indicate that the relevant lithologies in the Groningen subsurface are velocity-strengthening under in-situ temperature, pressure and fluid chemistry conditions [1]. This property should in theory lead to a lower chance of earthquake nucleation, which makes it difficult to explain the occurrence of earthquakes in Groningen. We study how to explain earthquake nucleation under velocity-strengthening friction and how much aseismic slip can be expected. In this study, we model the normal-fault setup of the Groningen field under reservoir depletion with rate-and-state friction. Initial conditions are chosen to mimic healing over millions of years prior to gas production. We implement fault loading due to fluid pressure reduction and validate our loading stresses with analytical predictions in Jansen et al. [2]. We provide constraints on how much aseismic slip to expect during nucleation and evaluate its relevance to induced seismicity in Groningen. We systematically investigate scenarios with various fluid extraction rates and different rate-and-state friction properties (including rate-strengthening, rate-weakening and a mixture of both) of surrounding lithologies using constraints from laboratory observations. In this way we explore the rate of stress change needed for nucleation under rate-strengthening friction. Currently, we produced an event with slip rate below seismic rate. If seismic rates cannot be reached, we will add a second state variable describing cohesion weakening with time to assess how it affects earthquake nucleation. The impact of frictional property and stress rate to aseismic slip build-up and earthquake nucleation is compared to what is caused by varied reservoir off-set distance and fault dipping angle. Sequences of earthquakes and aseismic slips are studied to understand the long-term effect of fluid extraction, with the influence of the planned gas production termination taken into account. We find that during continuous fluid depletion earthquakes reoccur at increasing recurrence interval. Large dipping angle and relatively low Poisson ratio are necessary to achieve this if reservoir offset is zero. Slip or strain nucleation and distribution patterns produced by our models provide hints that can guide seismologists to identify aseismic slip from natural observations, which can in turn, support this study and constrain simulated fault properties. Ultimately, this will help to better understand the nucleation of induced seismicity with similar lithologies that are present across northwestern Europe and lead to a better understanding of the relevance of aseismic slip.

 

References

[1] Hunfeld, L. B., Niemeijer, A. R., & Spiers, C. J. (2017).  Journal of Geophysical Research: Solid Earth, 122(11), 8969-8989.

[2] Jansen, J. D., Singhal, P., & Vossepoel, F. C. (2019).  Journal of Geophysical Research: Solid Earth, 124, 7193– 7212.

 

How to cite: Li, M., Niemeijer, A. R., Vossepoel, F. C., and van Dinther, Y.: Deciphering fluid extraction-induced earthquake nucleation in Groningen under rate-strengthening friction, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5576, https://doi.org/10.5194/egusphere-egu22-5576, 2022.

EGU22-5699 | Presentations | ERE5.1

Seismic to aseismic slip scaling during fluid injection experiments 

Luigi Passarelli, Louis De Barros, Antonio Pio Rinaldi, and Stefan Wiemer

A growing number of direct and indirect measurements and observation indicates that aseismic slip transients are often induced during fluid injection operation alongside with swarm-like seismicity. The detection of fluid-induced aseismic slip has made a paradigm shift on our understanding of the spatio-temporal evolution of earthquake activity during injection operation, classically interpreted as triggered by a diffusive front of high pore pressure. Instead, unclamping of the fault by pressurization induced by fluid injection creates the condition to nucleate synchronous aseismic and seismic slip transients.  In this scenario, the spatio-temporal evolution of the induced seismicity is driven by the stressing rate imparted at the leading edges of the aseismic rupture front. However, the relationship between the magnitude of aseismic slip and the hydraulic energy input in the system remains still elusive. A similar mechanism has been proposed for natural earthquake swarms triggered by shallow (5-10 km depth) slow slip events (SSEs), for which a robust power-law scaling has been demonstrated between seismic and aseismic slip. Notably, the power-law moment scaling of shallow SEEs and associated earthquake swarms has been interpreted with a mechanism of fault pressurization enhanced by intense fracturing in a seismogenic volume with abundance of crustal fluids. Similar fault conditions are at play for fluid-induced seismicity. Here, we collected several case studies of recorded induced aseismic deformation during injection experiments together with the accompanying seismic activity. We investigated the spatial distribution and temporal evolution of the seismicity with respect to the ongoing transient aseismic slip. We focused in particular on the seismic and aseismic slip budget of induced seismicity and compared it with previous scaling of SSEs. The aseismic and seismic moments of induced events are compatible with the power-law scaling of shallow natural earthquakes swarms triggered by SSEs, although a data gap exits for SSEs in 0-4 magnitude range, where no SSEs have never been recorded due to the low resolution of surface geodetic instrumentation. We performed also numerical simulation using a 3D hydro-mechanical model using realistic fault and hydraulic parameters in order to fill in the data gap. Our results serve as a basis to build up empirical models that incorporate aseismic slip together with injected volume and pressure to forecast seismicity during fluid-injection experiments.

How to cite: Passarelli, L., De Barros, L., Rinaldi, A. P., and Wiemer, S.: Seismic to aseismic slip scaling during fluid injection experiments, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5699, https://doi.org/10.5194/egusphere-egu22-5699, 2022.

EGU22-6361 | Presentations | ERE5.1

A 3D ETAS model for forecasting spatio-temporal distribution of induced seismic events 

Hossein Ebrahimian, Fatemeh Jalayer, and Vincenzo Convertito

Methodology:

Induced earthquakes have peculiar characteristics such as, relatively shallow depths, small magnitude, correlation with field operations, non-GR recurrence law, and eventually non-homogenous Poisson recurrence time. Indeed, induced seismicity tends to cluster in limited volumes near the wells where field operations (e.g., fluids injection, extraction, fracking, etc.) are performed. A novel and fully-probabilistic simulation-based procedure is presented for providing temporal and volumetric predictions of induced events’ occurrence in a prescribed forecasting time interval (in the order of hours or days). The procedure aims at exploiting the information provided by the ongoing sequence in quasi-real time (even in the presence of very limited registered data) to adaptively update the seismicity forecasts based on the incoming information as it becomes available. The clustering of seismic events in volume (3D seismicity) and time is modelled based on an Epidemic Type Aftershock Sequence (ETAS) model. The proposed 3D ETAS model encompasses a decoupled depth-area volumetric probabilistic kernel that incorporates kernel density functions for areal extent as well as the focal depth. The ETAS parameters are going to be re-calibrated in order to take into account non-GR long-term temporal boundary conditions in case of induced seismicity. Moreover, exact spatial integrals will be used to consider the 3D boundary conditions. The proposed procedure considers the uncertainties in the earthquake occurrence model parameters in a Bayesian updating framework. Pairing up the Bayesian inference and the suitable efficient simulation schemes (using Markov Chain Monte Carlo Simulation) provides the possibility of performing the forecasting procedure with minimum (or no) need of human interference.

Application:

The procedure is demonstrated through retrospective forecasting of induced seismicity recorded at the Geysers geothermal field in northern California in the time period of 2011-2015. Injection of cold water and heavier liquids in the hot reservoir caused induced earthquakes with moment magnitudes in the range of [0.0, 4.0] and depth ranging up to 5 km. The proposed procedure is examined for both Bayesian updating of the proposed 3D ETAS model parameters and forecasting of the number of events of interest expected to occur in various time intervals before and after a number of main events within the seismic sequence. The seismicity is predicted within a confidence interval from the mean estimate. Adding a kernel density for the focal depth and moving towards the 3D seismicity forecasting leads to the forecasted number of events that better match the events that actually took place in the forecasting interval, as compared to the 2D ETAS model. Therefore, it is concluded that the proposed 3D ETAS model is quite effective in case of induced seismicity.

How to cite: Ebrahimian, H., Jalayer, F., and Convertito, V.: A 3D ETAS model for forecasting spatio-temporal distribution of induced seismic events, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6361, https://doi.org/10.5194/egusphere-egu22-6361, 2022.

EGU22-7486 | Presentations | ERE5.1

Magnitude estimates of earthquakes induced by the geothermal stimulations in Espoo/Helsinki, southern Finland: a comparison of different approaches 

Amir Sadeghi-Bagherabadi, Tom Eulenfeld, Tommi A.T. Vuorinen, Annukka E. Rintamäki, and Gregor Hillers

In 2018 and 2020, two weeks-long geothermal reservoir stimulations were performed some 6 km below the Helsinki capital area, Finland. The seismic activity was recorded by a set of surface broadband sensors and 100 geophones installed by the Institute of Seismology, University of Helsinki, as well as Finnish National Seismic Network stations. The local magnitudes (ML) of the recorded earthquakes are estimated using a Finnish local magnitude scale and the local magnitude of the largest induced event was 1.8. We apply three different approaches for estimation of moment magnitudes (MW) to a data base of ~400 induced seismic events from the 2018 stimulation to explore the variability and sensitivity of the magnitude estimates. This is important for real-time monitoring and decision making when the induced event magnitudes approach the pre-defined magnitude limit, and to assess which trends can be robustly associated to earthquake source physics. (1) We employ a time-domain calculation of source parameters based on the application of Parseval's theorem to the integrals of the squared spectral displacement and velocity for the horizontal S-wave trains. The time window between the S-wave arrival time and twice the length of the S-wave travel time is considered for the S-wave train isolation. (2) We obtain moment magnitude estimates from an inversion of 50 s long three-component envelopes based on radiative transfer. (3) We apply a moment tensor inversion to 0.71 s long P and 0.81 s long S-wave signals. We fit a linear ML-MW conversion model to the values obtained from the different approaches. Considering the available local magnitude range between –0.5 and 1.8, a comparison of the linear conversion models shows that the moment magnitudes form the envelope inversion are systematically larger by ~0.2 units compared to those obtained from the moment tensor inversion. While the moment magnitudes determined by the time-domain calculation consistently exceed those of the envelope inversion for small local magnitudes (by ~0.2 units), they tend to yield similar estimates towards the larger local magnitudes. Other source parameter systematics include that the smallest seismic moment is obtained with the moment tensor inversion, and the largest with the time-domain equivalent of the spectral integrals. An initial extension of the analysis to 2020 data yields ML-MW as well as corner frequency-MW scaling relations that are, interestingly, different compared to the 2018 results; we will present updated results that inform about the reliability of these trends.

How to cite: Sadeghi-Bagherabadi, A., Eulenfeld, T., Vuorinen, T. A. T., Rintamäki, A. E., and Hillers, G.: Magnitude estimates of earthquakes induced by the geothermal stimulations in Espoo/Helsinki, southern Finland: a comparison of different approaches, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7486, https://doi.org/10.5194/egusphere-egu22-7486, 2022.

EGU22-7900 | Presentations | ERE5.1

Seasonal stress inversion trends and Coulomb stress changes of RTS in Song Tranh2 reservoir, Vietnam 

Izabela Nowaczyńska and Grzegorz Lizurek

The Song Tranh 2 hydropower construction is located in the Quang Nam province (central Vietnam), it has a reservoir volume of 740 million cubic meters of water and a dam height of 96 m. The reservoir was filled to capacity for the first time in February 2011. The seismicity in the vicinity of reservoir is example of reservoir triggered seismicity (RTS).  The natural seismic activity of the Song Tranh 2 reservoir is very low. After the reservoir was filled, the seismic activity increased, and the number and frequency of the tremors also changed as the water level changed. Water level changes are accelerating the tectonic process leading the critically stressed faults to slip. Data suggest that reservoir exploitation stress field changes as triggering origin of this seismicity. The stress inversion method was used to check if there were any seasonal trends. The inverted stress tensor and, in particular, the stress ratio, which is very sensitive to data quality and scope and difficult to accurately retrieve, can be influenced by porous pressure changes. Has been checked, how the average annual seismic activity is related to the change of the water level and if it implies the orientation of the principal stress during high and low water levels in the reservoir.  The pore pressure changes and the stress ratio changes were also estimated in relation to the high and low water level periods. Coulomb stress transfer is a seismic-related geological process of stress changes to surrounding material caused by local discrete deformation events.Importantly, Coulomb stress changes have been applied to earthquake-forecasting models that have been used to assess potential hazards related to earthquake activity. It is also often assumed that changes in pore fluid pressure induced by changes in stress are proportional to the normal stress change across the fault plane. Coulomb stress changes was also calculated for low and high water period.

How to cite: Nowaczyńska, I. and Lizurek, G.: Seasonal stress inversion trends and Coulomb stress changes of RTS in Song Tranh2 reservoir, Vietnam, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7900, https://doi.org/10.5194/egusphere-egu22-7900, 2022.

EGU22-7969 | Presentations | ERE5.1

Source mechanisms of earthquakes induced by the 2018 and 2020 geothermal stimulations in Espoo/Helsinki, southern Finland 

Annukka Rintamäki, Sebastian Heimann, Torsten Dahm, and Gregor Hillers

An experimental ~6 km deep enhanced geothermal system in Otaniemi, in the Helsinki capital region, southern Finland, was stimulated in 2018 and 2020. During the two stimulations that lasted seven and three weeks, respectively, signals of the induced earthquakes with a maximum local magnitude of 1.8 were recorded with dense and diverse seismic networks. The intraplate southern Finland setting of the experiment yields an intriguing opportunity to study earthquake and rock failure processes in the precambrian Fennoscandian Shield where the level of natural seismicity is comparatively low. The high confining pressure of 180 MPa at 6 km depth defines the key characteristics of the stress field, together with the previously estimated North-110-degrees-East direction of the maximum horizontal stress. The competent crystalline bedrock has very low attenuation, and yields high signal-to-noise ratio seismograms even at relatively high frequencies. We study the source mechanisms of ~250 induced earthquakes with Mw > 0.5. We perform probabilistic full moment tensor analysis with the Grond package of the software suite Pyrocko. We use data sets from the 2018 and 2020 stimulation experiments. Both experiments were monitored with more than 100 three-component surface stations operated by the Institute of Seismology, University of Helsinki, and 12 three-component borehole stations maintained by the St1 developer company installed at around 300 m depth. The diverse network elements help to evaluate the consistency of the results. We first present results of a detailed analysis of a small event subset characterized by the best data quality and solutions to assess the robustness of the different tensor components to different processing choices. This includes a comparison of surface and borehole sensor data. This allows us to conclude that the majority of the analysed earthquakes have a dominant reverse faulting mechanism and a small subset of events has strike slip mechanisms, which is compatible with solutions reported by the developer group. The predominant fault plane orientations are in agreement with the ambient stress conditions that also seem to control the thrust mechanism. Based on the best quality solutions we discuss the significance of the obtained non-double couple moment tensor components to assess if significant opening or closing elements in the induced earthquake source reflect genuine physical processes or spurious effects associated with imperfect resolution.

How to cite: Rintamäki, A., Heimann, S., Dahm, T., and Hillers, G.: Source mechanisms of earthquakes induced by the 2018 and 2020 geothermal stimulations in Espoo/Helsinki, southern Finland, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7969, https://doi.org/10.5194/egusphere-egu22-7969, 2022.

EGU22-8224 | Presentations | ERE5.1

Broadband seismic instrumentation for monitoring CCS sites 

Will Reis, Marcella Cilia, Neil Watkiss, Sally Mohr, Rui Barbara, and Phil Hill

Carbon Capture and Storage (CCS) sites require microseismic monitoring before, during and after operations to ensure safety of operational personnel and the wider public.

The high dynamic range and low self-noise of broadband seismometers allows for the detection of low magnitude microseismic events which fall below the threshold of less sensitive geophones. Higher long-period sensitivity also allows the full source spectra of earthquakes to be accurately measured, resulting in more accurate magnitude estimations which improve the integrity of any microseismic monitoring system.

Borehole instruments such as the Güralp Radian are a natural fit for detecting low magnitude microseismic events. Optional high gain at the higher frequencies makes the Radian extremely suitable for monitoring low-magnitude induced events while retaining long-period sensitivity for larger ruptures. The slim form factor and omni-angle operation allows the instrument to easily be lowered into decommissioned wells with little information about the orientation at depth.

The Radian is currently being utilised by the British Geological Survey as part of the UK GeoEnergy Test Bed (GTB) to monitor and improve understanding of fluid flow through natural subsurface pathways. A string of 6 interconnected Radians provides vertical profiling around the injection site with a maximum of 8 units able to join in a single string. The Radian will detect and monitor small changes in the subsurface at the GTB as part of the suite of monitoring technologies deployed onsite. 

In addition to onshore networks, offshore depleted gas fields are becoming increasingly scrutinised for potential to store CO2. The advent of Güralp omnidirectional sensor technology combined with acoustic near-real-time data transmission means the Aquarius OBS provides a cost-effective solution for monitoring offshore CCS sites, with infrequent and rapid battery recharging and acoustic data extraction while the unit is still on the seafloor.

How to cite: Reis, W., Cilia, M., Watkiss, N., Mohr, S., Barbara, R., and Hill, P.: Broadband seismic instrumentation for monitoring CCS sites, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8224, https://doi.org/10.5194/egusphere-egu22-8224, 2022.

EGU22-8688 | Presentations | ERE5.1

Analysis of the spatio-temporal evolution of the seismicity induced by hydraulic fracturing operations in Preston New Road, UK 

Riccardo Minetto, Agnès Helmstetter, and Ben Edwards

In August 2019 an hydraulic fracturing operation was carried out at the PNR-2 well in Preston New Road, UK. Hydraulic fracturing caused abundant seismic activity that culminated with a ML 2.9 event. This event prompted the operator (Cuadrilla Resources Ltd.) to halt any further stimulation of the well. The seismic activity was recorded by a downhole array of 12 sensors located in a monitoring well (PNR-1z). The operator released a seismic catalog created in real time during the fracturing operation. The catalog consists of 55555 events detected and located with a coalescence microseismic mapping method. The catalog also reports moment magnitudes, but no precise information on the method and on the parameters used to estimate them is available. In our study, we attempt to improve the number of detections and the location accuracy of the events by applying template matching and a double-difference relocation method, respectively. We also recalculate moment magnitudes using spectral fitting to look for any inconsistencies in the real-time catalog. Finally, we use the new information to better understand the spatio-temporal evolution of the seismicity and the dynamics that led to the ML 2.9 event.

How to cite: Minetto, R., Helmstetter, A., and Edwards, B.: Analysis of the spatio-temporal evolution of the seismicity induced by hydraulic fracturing operations in Preston New Road, UK, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8688, https://doi.org/10.5194/egusphere-egu22-8688, 2022.

EGU22-8716 | Presentations | ERE5.1

Numerical investigation of hydraulic stimulation strategies to mitigate post-injection seismicity in Enhanced Geothermal Systems 

Sri Kalyan Tangirala, Francesco Parisio, and Victor Vilarrasa

Enabling a widespread exploitation of Enhanced Geothermal Systems (EGS) around the world by tapping into the heat trapped by the radioactive granites demands a better understanding of the fluid-induced seismicity associated with their stimulation. Induced seismicity occurs not only during hydraulic stimulation, but also after shut-in. The induced earthquakes of Mw > 3 at Basel and Mw = 5.5 at Pohang are two well-known examples that have caused a negative public perception on EGS. Here, we numerically compare the effect of bleed-off on the mitigation of post-injection seismicity for three stimulation schemes: constant rate, step rate and cyclic injection. We find that applying bleed-off in the post-injection phase significantly reduces the post-injection induced seismicity when compared to not applying bleed-off in all the injection schemes.

How to cite: Tangirala, S. K., Parisio, F., and Vilarrasa, V.: Numerical investigation of hydraulic stimulation strategies to mitigate post-injection seismicity in Enhanced Geothermal Systems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8716, https://doi.org/10.5194/egusphere-egu22-8716, 2022.

EGU22-9233 | Presentations | ERE5.1

Analysis of the pico-seismic response of a fractured rock volume to fluid injections in the Bedretto Underground Laboratory, Switzerland 

Virginie Durand, Martina Rosskopf, Katrin Plenkers, Anne Obermann, Miriam Schwarz, Linus Villiger, Men-Andrin Meier, Hansruedi Maurer, Domenico Giardini, and Stefan Wiemer and the Bedretto Team

The Bedretto Underground Laboratory for Geoenergies and Geosciences (BULGG) is a multidisciplinary laboratory on the hundred meter scale run by ETH Zurich. It is located in the Swiss Alps, in the middle of a 5.2km long horizontal tunnel, 1.0km below the surface. 
Seven 250-300m long boreholes have been equipped with different instruments: Acoustic Emission Sensors, Accelerometers, Fiber Optics (allowing simultaneous DTS, DSS and DAS measurements), Strainmeters and Pore Pressure Sensors. The variety of the instrumentation allows a multidisciplinary analysis of the response of the rock volume to fluid injections. The fluid injections are realized through a 400m injection borehole located in the center of the instrument network. It is divided into 14 intervals, allowing us to make injections at different depths.
We will first present the methods used to generate a pico-seismic catalog with precise locations and a magnitude of completeness as low as -5, and the associated challenges. Then, we show a preliminary analysis of the spatio-temporal evolution of the pico-seismicity generated by different injection protocols. We interpret the evolution of the seismicity in comparison with the injection parameters (i.e., injection pressure and rate) and the stimulated intervals.

How to cite: Durand, V., Rosskopf, M., Plenkers, K., Obermann, A., Schwarz, M., Villiger, L., Meier, M.-A., Maurer, H., Giardini, D., and Wiemer, S. and the Bedretto Team: Analysis of the pico-seismic response of a fractured rock volume to fluid injections in the Bedretto Underground Laboratory, Switzerland, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9233, https://doi.org/10.5194/egusphere-egu22-9233, 2022.

EGU22-9373 | Presentations | ERE5.1

Variation in induced seismicity productivity by alteration of injection parameters: a comparative case study at three hydraulic fracturing wells in the Kiskatinaw area, British Columbia, Canada 

Marco Pascal Roth, Kilian B Kemna, Alessandro Verdecchia, Ricarda M Wache, Andres F Pena Castro, Rebecca M Harrington, and Yajing Liu

The Western Canada Sedimentary Basin (WCSB) has experienced an increase in hydraulic fracturing (HF) operations in the last decade, accompanied by an increase in the number of felt earthquakes, including a Mw 4.6 on 17 August 2015 near Fort St. John and a ML 4.5 (Mw 4.2) on 30 November 2018 near Dawson Creek. While only a small percentage of HF operations induce seismicity, the majority of moderate-sized earthquakes occur in close spatial proximity to HF wells and temporal proximity to individual HF injection stages within the tight shale play of the Montney Formation. Whereas statistical analysis of an enhanced seismicity catalog suggests that the majority of seismicity occurs following HF operations in the relatively older and deeper compartments of the Montney Formation (Lower Montney; LM) and a low number of events are associated with the relatively younger and shallower layers (Upper Montney; UM), the detailed association and triggering mechanism(s) remains unclear.

In this study, we investigate induced earthquake source parameter variations resulting from spatial and/or temporal alteration of injection parameters, including injection time, depth, and volume, at three well pads operating between 2018 and 2020 in the Kiskatinaw area. We use dense local station coverage to create an enhanced seismicity catalog with double-difference relative hypocenter relocations to highlight potential fault orientations, confirmed by focal mechanism solutions. We estimate static stress drop values at the individual well pads and their variation over time as well as variation with the choice of empirical Greens function. We also investigate the temporal changes of the VP/VS-ratio in localized areas following HF operations as a proxy for increased fracture density and/or compliance.

The case study at three specific sites targeting both the UM and LM layers investigates the relative influence of a number of factors on the spatial and temporal distribution of source properties. Factors include the scale of HF injection parameters, the target formation layer, and site-specific factors, such as localized fluid accumulation. Preliminary results show that injection in the UM generally leads to significantly fewer earthquakes than injection in the LM, and that lateral variations in compartment properties may significantly influence the seismic response. Moreover, we investigate if repetitive injection at the same wellhead may repeatedly (re)activate sets of faults/fractures and lead to increased hydraulic connectivity between the target sedimentary layers and deeper, pre-existing basement faults. An increase in connectivity would imply an increased potential for triggering large mainshocks.

How to cite: Roth, M. P., Kemna, K. B., Verdecchia, A., Wache, R. M., Pena Castro, A. F., Harrington, R. M., and Liu, Y.: Variation in induced seismicity productivity by alteration of injection parameters: a comparative case study at three hydraulic fracturing wells in the Kiskatinaw area, British Columbia, Canada, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9373, https://doi.org/10.5194/egusphere-egu22-9373, 2022.

EGU22-9575 | Presentations | ERE5.1

Reservoir triggered seismicity in tectonically stable and seismically active areas of Vietnam 

Grzegorz Lizurek, Konstantinos Leptokaropoulos, Monika Staszek, Izabela Nowaczyńska, and Anna Tymińska

Water reservoirs play important role in energy production in Vietnam. Numerous dams were designed and built for hydropower plants and water storage during the wet season and its release during dry season. They were built in a different tectonic settings. We present our experience of several years of monitoring and research on two sites: first, tectonic active area of Lai Chau (North Vietnam) and relatively stable area of Song Tranh in Central Vietnam. We observed different seismicity patterns in this areas. Area of active tectonics in Lai Chau was less active in terms of reservoir triggering, while almost aseismic area of Song Tranh was highly active after reservoir impoundment. We proved, that this activity was related with seasonal water level changes in reservoir. Moreover, low water period during service works was proved to be more active and with significantly higher seismic hazard than during initial production regime and after the refilling. It suggests that decrease of water level and following pore-pressure change destabilize minor faults being closer to failure, than main faults in the area. We also found multiplet events triggered on minor normal faults in shallow depth despite the strike-slip regime of regional tectonic stress field. On the other hand in the active area of Lai Chau we observed triggering both on existing active strike-slip faults and minor normal fault discontinuities. However, the difference between seismic activity parameters before and after impoundment except spatial distribution directly after first filling didn’t differ substantially. We can conclude, that in stable tectonic setting triggering effect is clear and related with pore-pressure changes caused by reservoir water level fluctuations, which is main seismogenic factor. On the other hand in active seismic area reservoir water level fluctuation seems to be too small to significantly influence seismic activity in the long term.

This work was partially supported by the research project no. 2017/27/B/ST10/01267, funded by the National Science Centre, Poland under the agreement no. UMO-2017/27/B/ST10/01267 (GL and IN) and partially supported by the research project no. 2021/41/B/ST10/02618, funded by the National Science Centre, Poland under the agreement no. UMO-2021/41/B/ST10/02618 (GL and AT) and partially by National Statutory Activity of the Ministry of Education and Science of Poland No 3841/E-41/S/2022 (MS)

How to cite: Lizurek, G., Leptokaropoulos, K., Staszek, M., Nowaczyńska, I., and Tymińska, A.: Reservoir triggered seismicity in tectonically stable and seismically active areas of Vietnam, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9575, https://doi.org/10.5194/egusphere-egu22-9575, 2022.

EGU22-9826 | Presentations | ERE5.1

Structurally controlled regional groundwater circulation: Origin of geothermal springs in Sri Lanka 

Dilshan Bandara, Thomas Heinze, Jeroen Smit, and Stefan Wohnlich

In the context of switching power generation towards renewable energy sources, the geothermal exploration of low enthalpy systems has gained interest also in regions with little to no recent tectonic or magmatic activity such as Sri Lanka. Sri Lanka has 9 low enthalpy systems with yet unknown heat generating mechanisms besides several existing hypotheses. Recent studies of such kind of low enthalpy geothermal systems hypothesize that fault network and recharge elevations are the main factors controlling the origin of the hot springs.

We studied the fault network, shear zones, and regional fracture networks to understand the heat flow causing the Sri Lankan hot springs. Remote sensing and geophysical methods were used to identify and analyze lineaments. We find that (1) The peak circulating temperatures of deeply circulating meteoric water depend on the elevation of the recharge zone for the corresponding hot spring. (2) Hot springs are formed in a terrain with a long fault / shear zone (starting from the highlands) when cross cuts with a regional fracture network occur in or near to the hot spring fields. (3) Highest number of hot springs in the country relates with the fault network that crosses the Mahaweli shear zone at the boundary of the two geological complexes Highland and Vijayan.

We conclude that the fault network that crosses both the central highlands and the Vijayan Complex plays a major role in the heating of deep percolating water, as it transports the water over more than hundred kilometers distance from the recharge zones to the hot springs. 

How to cite: Bandara, D., Heinze, T., Smit, J., and Wohnlich, S.: Structurally controlled regional groundwater circulation: Origin of geothermal springs in Sri Lanka, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9826, https://doi.org/10.5194/egusphere-egu22-9826, 2022.

EGU22-9880 | Presentations | ERE5.1

Numerical modelling of fluid-induced fault slip reactivation,application to Geo-Energy systems 

Jinlin Jiang, Pierre Dublanchet, Franҫois Passelègue, Dominique Bruel, and Frederic Pellet

Geothermal energy is one of the most promising techniques to exploit renewable energy resources from the Earth and to limit emissions of greenhouse gas. Deep geothermal exploitations are associated with long term fluid circulation and pressure perturbations at great depth, in fractured and faulted zones and are likely associated with a risk of triggering earthquakes. Such earthquakes are usually interpreted as the reactivation of rapid (m/s) shear slip on critically stressed faults caused by fluid flow and poroelastic stress changes. In some cases however, slow aseismic slip (m/d) can take place on faults in response to fluid flow. How fluid pressure perturbations reactivate aseimic or rapid slip still remains poorly understood. A better understanding of the hydromechanical processes controlling fault slip is therefore crucial to mitigate seismic hazards associated with geothermal exploitation.

In this framework, our study aims at constraining the influence of stress state, fluid injection rate, diffusivity and frictional failure criterion on the reactivation of slip on pre-existing faults through mechanical modelling of a set of laboratory experiments. The experiments consist of a fluid injection into a saw-cut rock sample loaded in a triaxial cell. Fault reactivation is triggered by injecting fluids through a borehole directly connected to the fault. This experimental setup is modelled by a 3D Finite Element Method (FEM) coupled with a solver of the fluid diffusion. The sample fault is modelled as a contact surface obeying slip-weakening Mohr-Coulomb friction law. This approach allows to compute slip and stress evolutions, as observed during the laboratory experiment. The FEM model is calibrated and is able to reproduce the experimental results. We show that fluid injection triggers a shear crack that propagates varying from 1 to 300 m/d along the fault. This approach can be used to investigate the relationship between fluid front and slip front during reactivation, which is an important issue to control the effects of fluid injections at depth.

How to cite: Jiang, J., Dublanchet, P., Passelègue, F., Bruel, D., and Pellet, F.: Numerical modelling of fluid-induced fault slip reactivation,application to Geo-Energy systems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9880, https://doi.org/10.5194/egusphere-egu22-9880, 2022.

EGU22-10043 | Presentations | ERE5.1

The dynamic Coulomb stress changes caused by remoteearthquakes based on the borehole strainmeter data 

Fuzhen Li, TianXiang Ren, ShunLiang Chi, Huai Zhang, and YaoLin Shi

Sufficient shreds of evidence have proved the existence of the remote triggering effect of large earthquakes. To understand its mechanism, it is necessary to conduct detailed investigations on the influence of the far-field dynamic stress changes on the stress state of faults. As an important tool of ultra-broadband crustal stress monitoring, a four-component borehole strainmeter can directly record the dynamic changes of horizontal strain and stress caused by seismic waves. These data are of great importance to study the dynamic Coulomb stress changes and related triggering effects, but have not been paid sufficient attention to so far. This paper analyzes the data of the four-component borehole strainmeter at Gaotai and Tonghua stations, which recorded the far-field strain changes of four major earthquake events in the Pacific region in 2018. We successfully identify the seismic phases of P, S, and surface waves, and analyze the characteristics of different phases through the stress petal method. The dynamic stress changes are calculated, demonstrating the feasibility of using borehole strainmeter data to quantitatively study the triggering effect of teleseismic waves of earthquakes with different magnitudes at different epicentral distances. We find that the direction of the principal stress axis of the dynamic stress changes is generally consistent with the azimuth of the earthquake epicenter. We further discuss the Coulomb stress changes on the major faults near the stations. According to the results, the peak values of the dynamic Coulomb stress changes produced by four earthquakes on the fault planes near Gaotai and Tonghua stations are at the magnitude of hundreds of Pa, which are lower than the threshold value of dynamic triggering. This is also consistent with the observation that no dynamically triggered earthquakes are found on the faults. However, the idea and method of this paper provide useful insight into the detection of possible dynamic triggering of large earthquakes.

How to cite: Li, F., Ren, T., Chi, S., Zhang, H., and Shi, Y.: The dynamic Coulomb stress changes caused by remoteearthquakes based on the borehole strainmeter data, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10043, https://doi.org/10.5194/egusphere-egu22-10043, 2022.

EGU22-10183 | Presentations | ERE5.1

The variability of seismo-acoustic nuisance patterns: a case study from the Helsinki geothermal stimulation 

Lukas Krenz, Sebastian Wolf, Alice-Agnes Gabriel, Gregor Hillers, and Michael Bader

With this contribution, we expand the discussion of effects that earthquakes induced by geo-energy projects can have on local communities, and that should probably be considered in future legislation or permitting processes. Inspired by consistent reports of felt and heard disturbances associated with the weeks-long stimulation of a 6-km-deep geothermal system in 2018 below the Otaniemi district of Espoo, Helsinki, we conduct numerical simulations of wave propagation in the solid earth and the atmosphere to assess the sensitivity of the ground shaking and audible noise patterns to various parameters. We explore the effects of three different local velocity models, realistic topography, variations of the source mechanism, and earthquake size on the loudness of the synthetic waves at frequencies up to 20 Hz, therefore reaching the lower limit of human sound sensitivity. We discuss the results of 18 elastic-acoustic coupled scenario simulations conducted on the Mahti high-performance computing infrastructure of the Finnish IT Center for Science CSC using the SeisSol wavefield solver. The computationally challenging simulations target the Otaniemi case study, i.e., we discretize a 12 km x 12 km x 15 km domain with a 2 km thick air layer over the solid earth domain. The earthquake point source is located at the 6.5 km deep location of the largest M1.8 event induced by the stimulation. In the target central area, we use a mesh with element lengths of about 14 m in the air and 97 m in the solid earth. Inside each element, we approximate the solution by a fifth-degree polynomial, by which we achieve a resolution of roughly 2.3 m in the air and 16 m in the earth. We develop an interactive visualization to facilitate instant access to the results governed by the different parameter combinations, where the synthetics are shown on top of a map of the Helsinki metropolitan region. This tool facilitates “what-if” analyses by quickly comparing the effects of fault orientation, source mechanism, and the velocity model. This supports effective communication of physics-based nuisance analysis to decision-makers and stakeholders, not only in environments such as the case study where there is little experience with natural earthquake phenomena. Together, these results resolve for the first time synthetic nuisance sound patterns at the 50 – 100 m scale in a densely populated capital region. The study highlights the mostly disregarded spatially variable audible effects that can negatively impact the public attitude towards geothermal stimulations, even if the ground shaking limits are safe, and it provides first estimates of the resources needed for comprehensive scenarios for future stimulation projects.

How to cite: Krenz, L., Wolf, S., Gabriel, A.-A., Hillers, G., and Bader, M.: The variability of seismo-acoustic nuisance patterns: a case study from the Helsinki geothermal stimulation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10183, https://doi.org/10.5194/egusphere-egu22-10183, 2022.

EGU22-10392 | Presentations | ERE5.1

Modelling injection induced seismicity in the Hengill geothermal field 

Antonio Pio Rinaldi, Vanille Ritz, Shyam Nandan, Raymi Castilla, Dimitrios Karvounis, and Stefan Wiemer

The Hellisheiði Geothermal Field is situated in Southwest Iceland and composes the Southern part of the Hengill Volcanic System. This area is characterized by a complex triple junction between three tectonic features: the Reykanes Peninsula rifting, South Iceland Volcanic Zone and West Volcanic  Zone. Reinjection of spent geothermal fluids is distributed mostly in two areas (Gráuhnúkar and Húsmúli), comprising respectively 6 and 5 active injection wells. The Húsmúli reinjection area, commissioned in September 2011 and has seen significant seismicity associated with drilling and injection operations.
In the framework of the Geothermica project COSEISMIQ (http://www.coseismiq.ethz.ch/en/home/), a dense temporary network was installed to monitor the seismicity in the Hengill region between December 2018 and August 2021. With this enhanced network, novel analysis and relocation techniques, a high resolution relocated catalogue was curated and comprises over 3600 events in the Húsmúli area.
We use numerical models, some purely statistical (ETAS and Seismogenic index) and a hybrid model (TOUGH2-Seed) to reproduce observed seismicity in the Húsmúli reinjection area during the COSEISMIQ project. We employ a pseudo-forecasting approach and compare models performances
and fit to the recorded data.

How to cite: Rinaldi, A. P., Ritz, V., Nandan, S., Castilla, R., Karvounis, D., and Wiemer, S.: Modelling injection induced seismicity in the Hengill geothermal field, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10392, https://doi.org/10.5194/egusphere-egu22-10392, 2022.

Heightened seismic activity due to human activities, such as wastewater injection, carbon storage and geothermal energy production, has been a rising problem in recent years. Various injection parameters and geological conditions have been shown to affect fault behaviour differently when fluid is injected on the faults, although existing observational studies about their effects often show contradictory results. Aseismic slip is also known to affect seismicity, but its exact contribution remains elusive.

To address these, we perform numerical modelling to study the effects of various injection parameters on fault slip behaviour. Our fully dynamic fault model is governed by the rate-and-state friction laws and spontaneously resolves all stages of an earthquake cycle and long-term fault slip. Our results show several interesting observations on the role of injection volume and rate: First, the injected volume can advance or delay the next earthquake if no earthquakes are directly triggered during perturbation. Second, if earthquakes are triggered, the number of triggered earthquakes is controlled by the rate at which fluid is injected, while the timings of the triggered earthquakes are controlled by the injected volume. Large triggered earthquakes are usually preceded by smaller precursors. Third, the pore-pressure threshold at which earthquakes are triggered changes depending on the injection parameters. In most cases, it increases with the volume of injected fluid, but in some cases when the injection is slow, it can also depend on the rate of injection. The change with respect to injection rate is not a smooth positive trend, however, as increasing the rate causes aseismic transients to grow stronger and transition into seismic events, thus advancing the triggering time and causing decrease in the threshold pore pressure in the process. Overall, the effects of perturbation do not end as soon as injection stops. Instead, heightened aseismic activities, as well as oscillating earthquake timings and magnitudes occur for multiple seismic cycles after the end of pore-pressure perturbation. We also see large variations in aseismic moment release under different perturbation scenarios and its intricate relationship with the resulted seismicity pattern, which confirms the vital role of aseismic slip in earthquake triggering. Similar to previous studies, we find that energy on the fault is primarily released aseismically.

Our results thus far are based on spatially uniform pore-pressure evolution, and we are currently developing models that resemble environments with temporally and spatially heterogeneous pore pressure by coupling the temporal evolution of pore pressure with spatial diffusion. We are also incorporating geologic information of the crustal medium, which will be more fitting for modelling realistic scenarios such as the injection-induced earthquakes in Oklahoma.  

How to cite: Mandal, R. and Lui, S.: Quantifying the effects of injection parameters on fault response under spatially homogenous and heterogenous pore-fluid conditions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10601, https://doi.org/10.5194/egusphere-egu22-10601, 2022.

Seismicity in western Romania is the result of tectonic processes that continuously shaped the landscape generating a fractured crust, which showed significant movements as a result of overall tectonic stress in the area as well as secondary effects such as erosion or lateral density fluctuations. At the same time, this region has an important natural resource, being identified here various deposits that have been intensively explored lately. The exploitation of these resources, as well as the development of the infrastructure in the region, led to the generation of anthropogenic seismic events. Due to the recent improvement of the Romanian Seismic Network, the coverage with seismic stations increased and these events were detected and located as natural tectonic events, contaminating the Romanian earthquakes (ROMPLUS) catalog.

To eliminate anthropogenic event contamination in the ROMPLUS catalog, we ran a complex statistical approach on the catalog data. In addition, to build a robust discriminant, we further applied cross-correlation and spectral analysis algorithms on the seismic waveforms recorded between 2014 and 2021 by the Surduc (SURR) and Gura Zlata (GZR) stations, which are located in the proximity of the major clusters of seismic events.

Our results showed a good distinction between tectonic and anthropogenic events and revealed that most of the clustered events are located near the explorations sites. We also noted that most of the events occurred during working hours. At the same time, the high similarity among these events indicates the existence of repetitive seismic sources.

How to cite: Varzaru, L.-C. and Borleanu, F.: Identifying anthropogenic seismic events generated in western Romania using statistical approaches and novel waveform processing techniques, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10911, https://doi.org/10.5194/egusphere-egu22-10911, 2022.

EGU22-11183 | Presentations | ERE5.1

Detailing the relationship between hydraulic fracturing parameters and induced seismicity using small-magnitude earthquakes 

Rebecca M. Harrington, Kilian B. Kemna, Marco P. Roth, Ricarda M. Wache, and Yajing Liu

The extensive development over the last decade of low-permeability tight shale formations in the Western Canada Sedimentary Basin (WCSB) using hydraulic fracturing (HF) techniques for oil and gas exploration has been associated with  an increasing number of M3+ earthquakes (e.g., ML 4.5 on 30 November 2018 near Dawson Creek, and a Mw 4.6 on 17 August 2016 near Fort St. John). Avoiding economic losses due to operational shutdowns and mitigating damage caused by ground shaking requires developing quantitative relationships between operational parameters and the rate of fault activation in areas of low historical seismicity rates such as the WCSB.

Here we present the first results of a detailed study of the relationship between earthquake occurrence and operational parameters using dense seismic array and the British Columbia Oil and Gas Commission operational database to quantitatively assess the relative influence of operational parameters and geological conditions on earthquake generation. We first enhance a local, automatically generated seismic catalog of > 8000 events in the Kiskatinaw (Montney Formation) in the time period between July 2017 -  December 2020 area using a multi-station matched-filter approach.  We then use a machine learning picker as an independent detection algorithm for the same time period and retain events with the best initial locations detected by both the matched-filter and machine-learning approaches. The combined approach leads to  > 30,000 additional earthquakes, which we relocate using a double-difference technique, lowering the magnitude of completeness Mc from ~1.3 to ~0.2.

As shown by several previous studies, while most earthquakes show a clear spatio-temporal correlation with HF operations, the majority of HF operations are not associated with felt earthquakes (e.g., M3+). To investigate the correlation between individual HF stage stimulation and earthquake occurrence, we correlate operational and geological characteristics with > 13000 HF stages. Geological data consists of the target formation for injection, which consists of either the Lower or Upper Montney Formations for the majority of stages. We then use a gradient-boosted decision tree machine learning algorithm combined with an approach to explain the model predictions to assess whether a specific stage is seismogenic. The decision-tree-algorithm allows us to estimate the importance of each injection parameter for the generation of seismicity. First results show that the target formation is the most influential parameter, where the Lower Montney Formation is more prone to higher rates of seismicity. In addition, the total pumped fluid volume and the maximum treating pressure are the important injection parameters that are positively correlated with seismicity. In contrast, the average injection rate and breakdown pressure may be relatively less influencial. We will present the results for specific stages and discuss the importance of their injection parameters in relation to seismicity. Our results could help to determine why only some HF wells are seismogenic.

How to cite: Harrington, R. M., Kemna, K. B., Roth, M. P., Wache, R. M., and Liu, Y.: Detailing the relationship between hydraulic fracturing parameters and induced seismicity using small-magnitude earthquakes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11183, https://doi.org/10.5194/egusphere-egu22-11183, 2022.

EGU22-11535 | Presentations | ERE5.1

Development of slow slip front during the nucleation of laboratory fluid-induced earthquakes 

Francois Passelegue and Pierre Dublanchet

Fluid injections are known to induce earthquakes in the upper crust. Recent studies have highlighted that fluid injections can contribute to the nucleation of instabilities close to or far from the injection site due to stress transfer induced by poroelastic processes. In addition, recent studies have suggested the maximum magnitude earthquake is expected to be a function of the volume injected. However, the development of the slip front related to the fluid pressure front, as well as its implications on the induced seismic sequence in time and space, remain poorly constrained in the laboratory and in natural fault systems.

Here, we investigated the influence of the initial normal stress (i.e., the permeability of the fault plane) and of the injection rate on the development of both the fluid pressure front and associated slip front during the nucleation stage of laboratory fluid-induced earthquakes. Experiments were conducted on saw cut samples of andesite, presenting a negligible bulk permeability compared to the fault plane one. Strain gauges were glued all around the fault surface to track, (i) the strain transfer associated with slip front propagation during injection and the rupture velocity during dynamic rupture propagation. The dynamics of the fluid pressure front was inverted from pore pressure measurements located at both edges of the fault. The evolution of the slip distribution due to the change in fluid pressure around the injection site was inverted from strain gauge measurements, assuming a 3D modelling of the sample specimen using the Finite Element Method. Our preliminary results show that the initial stress acting on the fault controls the development of the slip front during the nucleation of the instability. In addition, the larger the injection rate, and the faster the propagation of the slip front compared to the fluid pressure front. Finally, the scaling between the volume of fluid injected and the associated nucleation moment differs from the one relating the volume injected to the seismic moment.

 

How to cite: Passelegue, F. and Dublanchet, P.: Development of slow slip front during the nucleation of laboratory fluid-induced earthquakes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11535, https://doi.org/10.5194/egusphere-egu22-11535, 2022.

EGU22-11538 | Presentations | ERE5.1

Triggering mechanisms of the induced seismicity at the Underground Gas Storage of Castor, Spain 

Victor Vilarrasa, Silvia De Simone, Jesus Carrera, and Antonio Villaseñor

Cushion gas injection at the Underground Gas Storage (UGS) project of Castor, Spain, induced hundreds of events, including thirteen with magnitude higher than 3.5 that were felt by the local population and led to project cancellation. The sequence of felt events comprises the three largest earthquakes (M4.08, M4.01 and M3.97) ever induced by any of the more than 640 UGS facilities around the world. The largest earthquakes occurred 20 days after shut-in, when pore pressure buildup had already dissipated. The induced earthquakes nucleated at depths ranging from 4 to 10 km, significantly deeper than the storage formation, which is located at 1.7 km depth. These features of the induced seismicity disregard pore pressure buildup as the triggering mechanism. Our analyses show that seismicity was induced by gas injection, which reactivated the critically stressed Amposta fault. The Amposta fault, which bounds the storage formation, is a mature fault with very low permeability as a result of clay accumulation into its core resulting from its 1,000-m offset. Pore pressure buildup, but specially buoyancy of the gas, which continued to act after shut-in, destabilized the Amposta fault aseismically. The accumulation of aseismic slip caused stress transfer, destabilizing a deep critically stressed fault. Subsequently, shear slip stress transfer combined with slip-driven pore pressure changes, induced the sequence of felt earthquakes. We conclude that the induced earthquakes at Castor could have been avoided because fault stability analysis reveals the high risk of inducing seismicity.

 

Reference

Vilarrasa, V., De Simone, S., Carrera, J. and Villaseñor, A., 2021. Unravelling the causes of the seismicity induced by underground gas storage at Castor, Spain. Geophysical Research Letters, 48, e2020GL092038

How to cite: Vilarrasa, V., De Simone, S., Carrera, J., and Villaseñor, A.: Triggering mechanisms of the induced seismicity at the Underground Gas Storage of Castor, Spain, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11538, https://doi.org/10.5194/egusphere-egu22-11538, 2022.

EGU22-12474 | Presentations | ERE5.1

Impact of fracture length distribution on the injection-induced seismicity in fractured rocks 

Mohammad Javad Afshari Moein and Qinghua lei

Induced seismicity is a major challenge for fluid injection operations performed by geo-energy industry to exploit the underground resources. Despite recent developments in the understanding of induced earthquakes, many high-pressure fluid injection operations can still trigger unexpectedly large-magnitude events. A physical understanding of geological parameters controlling the induced seismicity is of central importance for improving our ability to forecast and mitigate the risk of inducing large earthquakes. Current physics-based numerical models are typically based on some simplifications that disregard the multiphysical interactions among fractures and faults. Therefore, the physical linkage between geometrical attributes of the fracture system and the statistics of induced seismicity is poorly understood. The final objective of this research is to determine the impact of fracture network properties on the spatiotemporal evolution of injection-induced seismicity and the emergence of large earthquake events.  

Here, we numerically capture the occurrence of seismic and aseismic slips in fracture systems, represented as discrete fracture networks (DFNs), spanning over two orders of magnitude over the length scale (1-100 m). Then, a 2D finite element model is used to simulate the coupled hydraulic and mechanical processes during fluid injection and analyze the occurrence of earthquakes. We present some preliminary results of our numerical simulations based on synthetic fracture network realizations. We particularly focus on power-law exponent of fracture length distribution and analyze the potential controls on the magnitude frequency of induced seismic events. The results of the analysis could have significant implications injection-related activities such as enhanced geothermal systems.

How to cite: Afshari Moein, M. J. and lei, Q.: Impact of fracture length distribution on the injection-induced seismicity in fractured rocks, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12474, https://doi.org/10.5194/egusphere-egu22-12474, 2022.

EGU22-12568 | Presentations | ERE5.1

Performance comparison of induced seismicity forecasting models with existing datasets 

Victor Clasen Repolles, Antonio Pio Rinaldi, Federico Ciardo, and Luigi Passarelli

Within the workflow of Adaptive Traffic Light System, it is important to evaluate the performance of different induced seismicity forecasting models in order to properly weight the forecasts during seismic hazard calculation. In this respect, we propose a standardize test bench approach capable of comparing outputs’ models (in terms of seismicity rate) and their uncertainties in real time. We test this approach using different models that are trained using existing datasets from geothermal exploration campaigns. Notably, we use two statistical models that link injection volumetric rate to seismicity rate with the difference that a Bayesian approach (EM1_BH) additionally adds epistemic uncertainty to the aleatoric uncertainty introduced in a purely frequentist approach (EM1_MLE), one pressure-based seismicity model (HM0_CAPS) based on 1D analytical solution for linear pore-fluid diffusion and finally one hybrid 1D model that includes a physic-based module for linear and non-linear pore-fluid diffusion linked to a stochastic model for seismicity generation using a seed approach (HM0_SEED and HM1_SEED). By using these different models and their uncertainties in our numerical investigations, we show the robustness of the proposed testbench approach.

How to cite: Clasen Repolles, V., Rinaldi, A. P., Ciardo, F., and Passarelli, L.: Performance comparison of induced seismicity forecasting models with existing datasets, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12568, https://doi.org/10.5194/egusphere-egu22-12568, 2022.

EGU22-66 | Presentations | ERE5.2

Influence of brittle deformation on the permeability of granite: assessing the geothermal potential of crustal fault zones 

Lucille Carbillet, Michael J. Heap, Hugo Duwiquet, Luke Griffiths, Laurent Guillou-Frottier, Patrick Baud, and Marie Violay

Economically viable geothermal systems rely on the efficiency of fluid circulation and heat transfer. Permeable fault zones are therefore excellent candidates for geothermal exploitation. In crustal fault zones, hot fluids from depths that correspond to the brittle-ductile transition are brought to the surface via crustal-scale permeable fault zones and may therefore constitute a new kind of geothermal system. To assess their geothermal potential, we measured the permeability of reservoir rock during deformation to large strains (up to an axial strain of about 0.1) in the brittle regime - fault formation and sliding on the fault - by performing triaxial experiments on samples of well-characterised Lanhélin granite (France). Prior to deformation, samples were thermally-stressed to 700°C to ensure that their permeability was sufficiently high to measure on reasonable laboratory timescales. All experiments were conducted on water-saturated samples under drained conditions, at a constant pore pressure of 10 MPa and confining pressures of 20, 40, and 60 MPa (corresponding to a maximum depth of about 2 km), and at room temperature. Our data show that permeability decreases by about an order of magnitude prior to macroscopic shear failure. This decrease can be attributed to the closure of pre-existing microcracks which outweigh the formation of new microcracks during loading up to the peak stress. As the macroscopic shear fracture is formed, sample permeability increases by about a factor of two. The permeability of the sample remains almost constant during sliding on the fracture to large strains (corresponding to a fault displacement of ~7 mm), suggesting that the permeability of the fracture does not fall below the permeability of the host-rock. The permeability of the sample at the frictional sliding stress is lower at higher confining pressure (by about an order of magnitude between 20 and 60 MPa) but, overall, the evolution of sample permeability as a function of strain is qualitatively similar for confining pressures of 20−60 MPa. These experimental results will serve to inform numerical modelling designed to explore the influence of macroscopic fractures on fluid flow within a fractured geothermal reservoir.

How to cite: Carbillet, L., Heap, M. J., Duwiquet, H., Griffiths, L., Guillou-Frottier, L., Baud, P., and Violay, M.: Influence of brittle deformation on the permeability of granite: assessing the geothermal potential of crustal fault zones, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-66, https://doi.org/10.5194/egusphere-egu22-66, 2022.

EGU22-981 | Presentations | ERE5.2

Friction behavior of gabbro under hydrothermal conditions 

Wei Feng, Lu Yao, Rodrigo Gomila, Shengli Ma, and Giulio Di Toro

Fault friction is one of the most significant parameters controlling fault slip behavior and earthquake mechanics. Great success has been achieved in understanding the stability of fault slip, nucleation of earthquake and dynamic weakening mechanism in the past decades by performing low (~1 μm/s, sub-seismic conditions) to high (~1 m/s, seismic conditions) velocity friction experiments. However, extrapolating these experimental results to nature remains limited. In fact, for low velocity experiments, usually performed with tri-axial machines, though the hydrothermal conditions can be imposed, the shear displacement is limited to several millimeters neglecting the effect of cumulative displacement. For high velocity experiments aiming at reproducing coseismic fault slip, the implementation of hydrothermal conditions has been hindered by technical difficulties leaving high-velocity friction property of faults under realistic crustal conditions still ambiguous.

Here we exploited a Low to High Velocity rotary shear apparatus (LHV) equipped with a dedicated hydrothermal pressure vessel installed at the Institute of Geology, China Earthquake Administration, to investigate the frictional behavior of gabbro under realistic hydrothermal conditions. The samples were sheared at effective normal stresses of 10 MPa and 20 MPa, velocities (V) spanning from 1 μm/s to 0.1 m/s, displacement up to 3 m, under temperature conditions (T) up to 400 ℃ and pore pressure (Pf) up to 30 MPa. Our results showed that at T = 300 ℃ and Pf = 10 MPa (pore fluid as liquid), dramatic slip weakening happened at all tested velocities. At slip initiation the friction coefficient increased sharply to a peak value (~0.7±0.05), then decayed toward a residual value of ~0.35. Instead at T = 400 ℃ and Pf =10 MPa (pore fluid as vapor), we observed that friction remained high (~0.7) at V < 10 mm/s and slip weakening only occurred for V ≥ 10 mm/s. For experiments at T = 400 ℃ and Pf =30 MPa (pore fluid in supercritical conditions), slip weakening behavior occurred in most cases. The evolution of friction coefficient with displacement was complex, e.g., two peaks, large variations. Moreover, comparative experiments conducted at relatively low temperature suggested that mechanisms leading to the dramatic weakening under such a wide velocity range could be closely linked with both fluid-rock interactions and the physical state of the fluid. However, what exact fluid-rock reactions are involved is still an open question, which will be investigated by further microstructural and mineralogical analysis. The unique frictional behavior observed in this study challenges the results obtained from small-displacements experiments in many aspects and improves our understanding on friction behavior of faults in geothermal applications.

How to cite: Feng, W., Yao, L., Gomila, R., Ma, S., and Di Toro, G.: Friction behavior of gabbro under hydrothermal conditions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-981, https://doi.org/10.5194/egusphere-egu22-981, 2022.

Upper Cretaceous (Turonian and Cenomanian) carbonates in the Münsterland Cretaceous Basin, NW Germany, have become a target for geothermal energy production in recent years. These carbonates are present at depths of up to ca. 1,800 m in the region of the city of Münster in the center of the basin (e.g. Münsterland-1 well) and at depths beyond 2,000 m in the so-called Vorosning Depression. They represent the shallowest calcareous strata within the sedimentary succession of the Münsterland Basin and the underlying Rhenish Massif. Previous industrial drilling campaigns mostly focused on potential hydrocarbon gas reservoirs of the Upper Carboniferous. In the context of geothermal reservoir exploration, analog studies in outcrops of the Cretaceous carbonates are a prerequisite for reservoir quality assessment since subsurface/in situ data of these stratigraphic units, and especially petrophysical properties, are very sparse, not accessible or even absent in some areas. Investigations of quarries with Cretaceous carbonates mostly focused on paleontological and facies related research in the past rather than on their petrophysical properties. Three quarries in the Lengerich and Oerlinghausen areas, all at the northern margin of the basin, were now sampled for petrophysical laboratory experiments of Cenomanian and Turonian rocks. Additionally, scanline investigations, which involve collecting information such as length and aperture and others of each fracture along a line intersecting the rock mass, capturing of Unmanned Aerial Vehicle (UAV, commonly called drones) footage and laser scanning was performed at the three Cenomanian outcrops in Lengerich and one Turonian outcrop in Oerlinghausen. Further UAV footage and laser scans were collected for other outcrops within the quarries. The facies of the investigated rocks are expected to be comparable to what can be anticipated in the center of the Münsterland Basin according to the current paleogeographical understanding. Their analysis can thus be helpful in predicting the conditions that may be encountered in the central part of the basin. However, since the data was collected at the northern margin of the basin, the influence of the Osning Fault Zone (Upper Cretaceous inversion tectonics) has to be taken under consideration when further interpreting the data. The drone footage was processed, and Virtual Outcrop Models (VOM) were created using Agisoft Metashape. The point clouds of both, the laser scanning and processed UAV footage, were analyzed using the open-source package CloudCompare with its Facets and Compass plugins. The plugins allowed the detection of differently oriented fracture sets in the point clouds. This allowed to characterize fracture distributions and the comparison between the virtual outcrop data and the scanline data. Subsequently, the parameters of the fracture distributions of these structural features together with the laboratory measurements on bulk petrophysical properties were combined in a discrete fracture network (DFN). This representation of the reservoir, and in particular the 3D distribution of permeability, will be used for reservoir analog modelling to characterize fluid flow in the subsurface.

How to cite: Slama, S., Jüstel, A., Lippert, K., and Kukla, P.: Characterizing fracture networks and petrophysical bulk properties of carbonates from the margin of the Münsterland Cretaceous Basin, NW Germany, from outcrops, virtual outcrop models and laboratory testing, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2503, https://doi.org/10.5194/egusphere-egu22-2503, 2022.

EGU22-3309 | Presentations | ERE5.2

CT scan of a small-scale fault network: 3D fault geometries and their interpretation 

Inbar Vaknin and Andy Nicol

Fault surfaces and networks have been shown to have complex geometries. Outcrop observations are typically two-dimensional and limited in size by the exposure dimensions, while three-dimensional (3D) seismic data lack the resolution to characterize and quantify fault complexities on length scales less than a decameter. Defining the geometries of faults and their networks (high-resolution in 3D) is critical for understanding the interactions between faults and fluids. This presentation will examine the geometries of a network of small-scale normal faults displacing (by <1 cm) well bedded sand and silt layers in the Mount Messenger and Mohakatino formations in Taranaki, New Zealand. A 3D model of faulting was produced from high-resolution multi-band CT scanner (MARS Bioimaging Ltd.) imagery of a 10x8x3 cm rock sample. The digitally sectioned rock contains calcified fault rock that is distinguishable from wall rock and mapped throughout the rock volume at sub-millimeter scale. Fault-rock thicknesses vary by in excess of an order of magnitude, with greatest thicknesses at fault steps and fault bends. Fault zones comprise a series of lenses that have strike lengths greater than dip lengths and lens shapes that are often elongate parallel to bedding. The fault network is highly connected with branch lines, fault steps and fault bends most often sub-parallel to bedding. These observations suggest that mechanical heterogeneity of beds may partly control the geometries of both fault zones and the fault network. At the time of formation, the interconnected fault network likely increased bedding-parallel permeability (at scales from sub-millimeter and above) along fault zones.

How to cite: Vaknin, I. and Nicol, A.: CT scan of a small-scale fault network: 3D fault geometries and their interpretation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3309, https://doi.org/10.5194/egusphere-egu22-3309, 2022.

EGU22-3414 | Presentations | ERE5.2

Fluid pressure diffusion in fractured media: insights from harmonic and non-harmonic periodic pumping tests 

Nicolás D. Barbosa, Nima Gholizadeh Doonechaly, and Jörg Renner

Fractures can significantly impact fluid flow and pore pressure distribution in the subsurface. Understanding the mechanisms and conditions influencing their ability to transport fluids and to promote pore pressure diffusion is key for many activities relying on fracture-controlled flow such as, for example, enhanced geothermal systems. In situ characterization of these properties is typically done by performing hydraulic tests in selected intervals of a borehole and their interpretation relies on the solution of a linear pressure diffusion equation. However, it has been shown that the hydraulic behavior of fractures as well as the associated near borehole flow regimes can be largely affected by the coupling between the solid deformation and fluid pressure upon injection/production. In this work, we explore these effects by performing a series of harmonic injection tests (HIT) as well as non-harmonic production tests (NHPT) in a packed-off interval of a borehole containing multiple natural fractures. The borehole is located in the Bedretto Underground Laboratory for Geosciences and Geoenergies in Switzerland and penetrates granitic rock mass. The two kinds of tests consist of a periodic repetition of the same injection or production protocol. Flow rates, interval pressures as well as pressures above and below the double-packer probe are recorded at the surface. An important advantage of periodic testing is that it permits a continuous tracking of hydraulic changes during the test. For our study, we conducted a so-called injectivity analysis, in which the phase-shift (time delay) and amplitude ratio between flow rate and interval pressure are used to infer effective hydraulic properties. We performed over 200 periodic tests including both HIT and NHPT with a large range of periods (7.5 s to 1800 s) as well as varying mean interval pressures (~1300 kPa to 2100 kPa) and flow oscillation amplitudes. As a result, we obtained a robust constraint of the radial flow regime prevailing in the fractures. Overall, we found that results from HIT and NHPT are in very good agreement despite the remarkably different injection protocols. For all cases, a prominent and consistent period dependence of phase shifts and amplitude ratios of flow rates and interval pressure was observed, in which both increase as the oscillatory period decreases. Amplitude ratios showed almost no variation with mean interval pressure regardless of the injection protocol. In contrast, a prominent pressure dependence of the phase shifts is captured by the HIT but not the NHPT data. Using the pressure-independent NHPT results, we reconstruct the general hydraulic response of the tested fractured section, which can be well represented by an analytical solution of the pressure-diffusion equation. This general trend explains the HIT data as well, although evidence of significant variations that are correlated with the amplitude of the pressure oscillations points to the predominant role of hydromechanical coupling effects on the fluid pressure diffusion process.

How to cite: Barbosa, N. D., Gholizadeh Doonechaly, N., and Renner, J.: Fluid pressure diffusion in fractured media: insights from harmonic and non-harmonic periodic pumping tests, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3414, https://doi.org/10.5194/egusphere-egu22-3414, 2022.

Flow through faults and fractures has been studied extensively in the context of hydrocarbon exploration and production, to understand charge and migration, hydrocarbon column heights and fault transmissibility. Learnings have typically been captured in pragmatic models, such as the Shale-Gouge-Ratio (SGR) concept, providing dimensionless or relative fault permeability definitions based on limited subsurface data.

The resulting coarse predictions are however not suitable for geoenergy applications, including CO2 sequestration (CCS) or underground hydrogen storage (UHS), where injection into a storage reservoir requires assurance that the injected fluids or gases will not leak out of the storage complex via faults or fractured caprocks. The conventional fault seal analyses do not provide this containment assurance.

A new paradigm is required for characterizing faults and fractures in geoenergy projects, focused on derisking leakage of injected fluids and gases along faults. Such approach is not necessarily about accurately predicting the permeability of a fault or fracture, but rather about understanding what geometric properties and mechanical or chemical mechanisms would contribute to either permeable or sealing behaviour of faults. Improved insights in any of these areas would help in screening fault leakage risks in prospective subsurface geoenergy projects.

Analogue data, both from outcrops for geometric fault attributes and from the lab for mechanical and chemical properties, can help gain those fundamental insights into what controls fault leakage. Properties can be quantified and processes studied at a level of detail that cannot be matched by in-situ subsurface datasets, particularly not in the context of geoenergy systems, where operational subsurface projects are still limited. Outcrop studies can help improve our understanding of vertical connectivity, with focus on lower-permeability ductile rocks analogues to typical reservoir seals. Lab studies and in-situ experiments can provide insights into injected fluids such as CO2 or H2 affect the mechanical and chemical integrity of faults and subsequent flow behaviour. For geoenergy systems in particular, experiments should focus on the impact of rapid pressure or temperature cycling. Induced seismicity is another potential threat to containment integrity and requires further research to understand what fault geometries are most prone to reactivation as well as how reactivation affects the sealing behaviour of a fault.

In recent years, integrated studies such as the multi-scale, multiphysics ACT-DETECT project have started to provide some answers to these questions, resulting in novel insights and workflows that provide a first-order fault leakage risk assessment that can be used to identify ideal storage sites. However, with the envisioned increase in the number of geoenergy projects to meet carbon emission reduction targets, the need for more refined screening criteria will increase too as the flexibility in selecting ideal storage locations will decrease.

How to cite: Bisdom, K.: A new paradigm for flow through faults and fractures in the context of geoenergy, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3553, https://doi.org/10.5194/egusphere-egu22-3553, 2022.

At the Äspö hard rock underground laboratory in Sweden, six in situ hydraulic fracturing experiments took place at 410 m depth. A multistage hydraulic fracturing approach is tested with a low environmental impact, e.g., induced seismicity. The idea is to mitigate induced seismicity and preserve the permeability enhancement process under safe conditions. The fractures are initiated by two different injection systems (conventional and progressive). An extensive sensor array is installed at level 410 m, including simultaneous measurements of acoustic emissions, electric self-potential, and electromagnetic radiation sensors. The monitoring catalog includes more than 4300 acoustic emission events with estimated magnitudes from the continuous monitoring setup (in-situ sensors between 1-100 kHz). The experiment borehole F1 is drilled in the direction of Shmin, perpendicular to the expected fracture plane. Two electromagnetic radiation sensors are installed and aligned to (i) Shmin and (ii) the expected fracture plane with a sampling rate of 1 Hz and a frequency range between 35-50 kHz. The self-potential sensors are installed at level 410 with a distance of 50-75 m from the borehole F1, including nine measuring probes and one base probe. A second self-potential setup is deployed at level 280 m in the far-field with a distance of 150-200 m from F1. The self-potential data were measured with a sampling rate of 1 Hz. For the first time (to our knowledge), the results of electric and electromagnetic monitoring of two hydraulic stimulation at meter-scale are presented.

How to cite: Haaf, N. and Schill, E.: Electric self-potential and electro-magnetic monitoring of hydraulic fracturing experiments in the Äspö Hard Rock Laboratoy, Sweden., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3837, https://doi.org/10.5194/egusphere-egu22-3837, 2022.

EGU22-6166 | Presentations | ERE5.2

Assessing damage pattern at depth near the Alpine Fault, New Zealand 

Mai-Linh Doan, Virginia Toy, Rupert Sutherland, and John Townend

 

The Alpine Fault is the principal component of the plate boundary through the South Island of New Zealand, separating the Pacific and Indo-Australian Plates. It is recognised internationally as an important site for studying earthquake physics and tectonic deformation, as it produces large (M7-8) earthquakes approximately every 330 years and last ruptured in 1717. Therefore, the fault is considered to be late in its seismic cycle. It accommodates dextral-slip at a rate of 26 mm/yr with reverse slip at a maximum rate of 10 mm/yr in its central part, thus exhumed a fossil ductile shear zone, that was damaged brittlely during its exhumation.

 

The central Alpine Fault is the focus of the Deep Fault Drilling Project (DFDP), sponsored by the International Continental Drilling Project, which takes advantage of its globally rare tectonic situation to determine what temperatures, fluid pressures, and stresses exist within a plate-boundary fault in advance of an expected large earthquake. During DFDP phase II in 2014, an ~ 900 m drilled well that encountered an exceptionally high geothermal gradient (120 °C/km was measured in the borehole), was extensively characterized by repeated electric and sonic logs. These logs enable detailed study of fracture patterns near a major fault. The more than 19 km of logs run within the borehole gathered datasets covering, among others, thermal resistivity, sonic velocities, acoustic borehole imaging, and electrical resistivity. They show that the hanging wall is extensively fractured, explaining the high geothermal gradient measured in the borehole by lateral flow of hot water deep seated in the mountains.

 

We particularly focus on seven dual laterolog logs that provide a robust and reproducible dataset from which to determine the positions and orientations of conductive fractures. From these, different patterns of damage could be identified within the well. A first pattern consists of an extensive and dense pattern of isolated fractures that could be identified throughout the borehole. A second pattern suggests that decametric  zones of low resistivity localize damage and focus thermal anomalies. This suggests hierarchy of damage zone evolution of the damage zone of the Alpine Fault. A possible explanation is an initial phase of diffuse fracturing (pattern 1) that is followed by subsequent alteration of the major shear zone, which focuses fluid and heat flow (pattern 2).

How to cite: Doan, M.-L., Toy, V., Sutherland, R., and Townend, J.: Assessing damage pattern at depth near the Alpine Fault, New Zealand, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6166, https://doi.org/10.5194/egusphere-egu22-6166, 2022.

The regionalization of hydraulic properties like specific yield/storativity or permeability in fractured crystalline rock is of utmost importance for a variety of applications, such as geothermal and other resources, waste disposal or underground construction. However, accurate predictions for these properties – particularly for undrilled sites – bear a high degree of uncertainty as already direct observations through hydraulic in-situ tests show a variance of about 2 orders of magnitude at any depth (Achtziger-Zupančič et al., 2017).

Permeability-depth relationships using multiple log-log regressions conducted on an extended version of the worldwide permeability compilation of crystalline rocks (roughly 30000 entries in Achtziger-Zupančič et al., 2017; now consisting of about 50000 single in-situ permeability measurements to depths of 2000 mbgs) indicate that depth is generally the most important geological factor, resulting in a permeability decrease of three to four orders of magnitude in the investigated depth range. Specific yield and storativity show a similar but less pronounced depth trend. Beside depth, most influential factors for permeability in crystalline rock are the long-term tectono-geological history described by geological province which locally is overprinted by current seismotectonic activity as determined by peak ground acceleration (Achtziger-Zupančič et al., 2017). Although petrography might be of local importance, only a low impact has been observed for the global dataset, besides lithologies allowing for karstification. Ongoing vertical movements – particularly resulting from glacial isostatic adjustment – alter the permeability trend with depth.

The latter shows distinct trends starting at about logK -14.5 to -14.8 m² at 100 mbgs and showing diversion of about 1.5 orders of magnitude at 1 km depth between areas without significant uplift and areas with uplift of more than 4 mm/y as determined from a probabilistic interpolation of global geodetic measurements (Husson et al., 2018). The difference is attributed either to glacial loading (normal faulting or reactivation) induced destruction preserved during glacial induced rebound and/or uplift-caused horizontal fracture growth which improved connectivity in the rock mass. Areas undergoing subsidence show similar trends like highly uplifting areas which is attributed to efficient normal faulting induced destruction of the rock mass.

References:

Achtziger-Zupančič, P, Loew, S and Mariéthoz, G (2017). A new global database to improve predictions of permeability distribution in crystalline rocks at site scale. JGR: Solid Earth 122(5): 3513-3539.

Husson, L, Bodin, Th, Spada, G, Choblet, G and Kreemer, C (2018). Bayesian surface reconstruction of geodetic uplift rates: Mapping the global fingerprint of Glacial Isostatic Adjustment. J Geodyn 122: 25-40.

How to cite: Achtziger-Zupancic, P.: The influence of glacial induced adjustment and other geological factors on the depth distribution of permeabilities in crystalline rocks, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7157, https://doi.org/10.5194/egusphere-egu22-7157, 2022.

EGU22-7835 | Presentations | ERE5.2

Fracture energy variations of rocks: a mechanical investigation 

Antoine Guggisberg, Mathias Lebihain, and Marie Violay

Crack propagation is critical for the assessment of the strength of rocks. Linear Elastic Fracture Mechanics (LEFM) theory is commonly used to describe its propagation. However, the variation of the fracture energy, its key parameter, is generally poorly understood as its experimental measurements are influenced by temperature, stress biaxiality, and rupture velocity. This indicates other dissipative processes may occur in the vicinity of the crack.

We conduct Modified Ring Tests (MRT) on Carrara marble to investigate these mechanisms. MRT provides stable mode I crack propagation under controlled velocity and stress biaxiality conditions. Coupled with a compliance method calibrated through Finite Element Method (FEM), we obtain multiple local measurements of the fracture energy within a single test. FEM also provides estimation of stress biaxiality levels as well as higher order terms of the Williams’ expansion of the stress field.

The method is validated on PMMA through Digital Image Correlation (DIC) techniques. Experiments on Carrara marble show that the stress biaxiality can directly influence the fracture energy measurements. A microscopic investigation on marble is performed to look for micro-mechanisms which may cause observed variations of fracture energy.

How to cite: Guggisberg, A., Lebihain, M., and Violay, M.: Fracture energy variations of rocks: a mechanical investigation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7835, https://doi.org/10.5194/egusphere-egu22-7835, 2022.

Between 2018 and 2021, the STIMTEC and STIMTEC-X hydraulic stimulation experiments were conducted at 130 m depth in the Reiche Zeche underground research laboratory in Freiberg/Germany. The STIMTEC experiment was designed to investigate the rock damage resulting from hydraulic stimulation and to link seismic activity and enhancement of hydraulic properties in anisotropic metamorphic gneiss. The following STIMTEC-X experiment aimed at better constraining the stress field in the rock volume to investigate the mechanisms leading to induced acoustic emission (AE) activity. Here, we present results from focal mechanism analysis of high-frequency (>1 kHz) AE events, associated with brittle deformation at the cm- to dm-scale induced by hydraulic stimulations. Focal mechanisms are calculated using full moment tensor inversion of first P-wave amplitudes using the hybridMT package. We use polarity and amplitude data from a (near) real-time seismic monitoring network, consisting of AE sensors, AE-hydrophones, accelerometers, and one broadband sensor. We observe changes in the predominant type of faulting from reverse faulting focal mechanisms during the frac and refrac cycles to oblique strike-slip focal mechanisms observed during subsequent high-volume fluid-injections performed during periodic pumping test. The observed differences in dominant focal mechanisms are consistent with the activation of less favourably oriented faults at increased pore fluid pressure during extended periodic pumping. We observe a reverse-faulting stress regime from focal mechanism inversion of low-volume injection stages for different boreholes, representative for the rock volume (typically ~5 m radially) surrounding the injection intervals. In contrast, stress field estimates obtained from analysing the instantaneous shut-in pressures of hydraulic stimulations in different boreholes indicate a regime change from thrust to strike-slip faulting in the investigated rock volume. The reservoir complexity seen at the scale of the experiment (30m x 30m x 20m) is large and is reflected by the significant variations in AE event activity in response to stimulation as well as small-scale rock, stress and structural heterogeneities.

How to cite: Boese, C., Kwiatek, G., Renner, J., and Dresen, G.: Stress field observations from hydraulic fracturing and focal mechanism inversion at the STIMTEC underground research lab, Reiche Zeche mine, Germany, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7986, https://doi.org/10.5194/egusphere-egu22-7986, 2022.

Fluid flow in low-porosity/permeability reservoir rocks such as tight carbonates is mostly restricted to structural discontinuities (e.g. faults, fractures, karstified zones). Fault zones, in particular in such rocks, offer both suitable fluid flow pathways, but may also act as impermeable barriers. The heterogeneous permeability structure of fault zones, however, impedes pre-drilling investigations of exploration targets by numerical models. A better understanding of the factors that control the fluid flow and the heterogeneity of permeability distribution along fault zones in tight reservoirs is a pre-requisite for the definition of drilling targets.

In this study, a hydraulic field laboratory with a volume of 30 m x 30 m x 20 m was set up in a quarry in SE Germany to investigate the influence of fault zones on the general permeability structure of tight carbonates. The test field contained three WNW-ESE-striking, repeatedly reactivated normal faults with offsets in the order of <1 m and two roughly perpendicularly oriented NNE-SSW-striking fracture corridors. Fault zones and fracture corridors were targeted by 62 wells. Wells that exhibited a decent hydraulic connection the to the overall conductive fracture network were logged (e.g. borehole image logs, FWS, etcs.) and in selected wells hydraulic tests were conducted. Water levels were measured both during static conditions and during testing. Due to the density of wells we were able to constrain the controlling factors for fluid flow along and across the fault zones. Damage zones were considered as conduits while the fault core was expected to be impermeable. These general assumptions could be confirmed by our tests, however we found some exceptions. While fluid flow in general is restricted to few, well-connected fractures, the majority of the fractures are dead ends, solely serving as storage for fluids. With increasing displacement and complexity of the fault zone, enhanced permeability parallel to the fault zone could be inferred. At larger offsets, where a thicker fault core develops, fhe fault core itself acts as barrier and fractures and fracture corridors do not penetrate the faults. We think that this is related to the presence of the much less competent fault core of a certain thickness which is able to accommodate the brittle deformation. Where the faults offset is less than ~0.4 m, the integrity of the fault seal is breached by fracture corridors, cross cutting the faults. This is clearly shown by the pressure distribution in static and transient conditions. Faulting, hence leads to a compartmentalization of the reservoir, where the compartments do either communicate or interact with significant delay.

The information and data received from the conducted field tests furthermore serve as input parameters and validation for a newly developed numerical approach that aims to simulate fluid flow in this type of geological settings, results of which will be presented in an additional presentation by our project partners.

How to cite: Freitag, S., Bauer, W., Stollhofen, H., and Hähnel, L.: (1)   Transmissivity of fault zones in tight carbonates – results from a reservoir-scale hydraulic field laboratory in the Franconian Alb, SE Germany, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8457, https://doi.org/10.5194/egusphere-egu22-8457, 2022.

In outcrop-based fracture studies, the quantification of fracture intensity is often limited by the limitations of the manual sampling technique, characterized by punctual measurements (e.g. sampling spot, scanline, scanwindow) and moderate biases (e.g. fracture length truncation, technical and personal errors). The proximal remote sensing technologies, as terrestrial or Uncrafted Aerial Vehicle (UAV)-based LiDAR and photogrammetry, can help to overcome these limitations due to the possibility to obtain high-resolution and accurate quantitative data from the digital twin of the outcrop, the so-called Digital Outcrop Model (DOM). The DOMs can be very useful in outcrop-based fracture studies because their analysis allows to obtain several quantitative information with manual and/or automatic methods and with continuity in each position of the outcrop, increasing the accuracy of the fracture intensity estimations. However, due to the novelty of DOM technology and the lack of well-defined DOM-based fracture sampling procedures, these huge fracture datasets are often difficult to study and interpret, and therefore, the benefits of the DOM cannot be fully exploited. 

For this reason we present a complete workflow based on the DICE (Discontinuity Intensity Calculator and Estimator) open-source MATLAB© application that allows to quantitatively characterize the fractures of rocky outcrops from the 3D Digital Outcrop Models (DOMs). The proposed workflow consists in the following steps: (1) fracture mapping onto the 3D DOMs; (2) calculation of the fractures dimension, position and orientation; (iii) determination by DICE algorithm of the discontinuity parameters (persistence/dimension, distribution, spacing and intensity) using different 3D sampling techniques (3D scanline, 3D circular scan window and spherical scan volume). The differences of these sampling techniques and the fracture intensity parameters that can be obtained (p10, p21, p32) are discussed, showing the advantages and limitations of each DICE method.

How to cite: Menegoni, N., Giordan, D., and Perotti, C.: 3D Digital Outcrop Model-based quantification of fracture intensity: the Discontinuity Intensity Calculator and Estimator (DICE) open-source application, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10207, https://doi.org/10.5194/egusphere-egu22-10207, 2022.

EGU22-10259 | Presentations | ERE5.2

CHENILLE: Coupled beHavior undErstaNdIng of fauLts: from the Laboratory to the fiEld 

Audrey Bonnelye, Pierre Dick, Fabrice Cotton, Rüdiger Giese, Yves Guglielmi, Damien Jougnot, Jan Henninges, Grzegorz Kwiatek, and Stefan Lüth

The understanding of the coupled thermo-hydro-mechanical behaviour of fault zones in naturally fractured reservoirs is essential both for fundamental and applied sciences and in particular for the safety assessment of radioactive waste disposal facilities. In this framework, an international research program callled CHENILLE was built to address key questions related to the impact of high temperatures (up to 150°C) on shear zones as well as fault reactivation processes in shale formations. The project includes a thermally controlled in situ fluid injection experiment on a strike-slip fault zone outcropping atIRSN’s Tournemire Underground Research Laboratory (URL) and a series of laboratory experiments to understand the chemical and structural evolution occurring within the fault zones during the thermal and hydraulic loading. The in situ experiment includes a heating system installed around an injection borehole will enable a precise and controlled incremental increase of the thermal load. The injection borehole will be equiped with a Step-Rate Injection Method for Fracture In-Situ Properties (SIMFIP) probe, in order to perform step pressure tests. The probe will not only measure the flow and pressure rate inside the injection borehole but also allow to monitor the borehole’s 3D deformation during the hydraulic and thermal loading steps. In addition, an array of seismicifferent sensors will be implemented around the injection area to measure the seismic and aseismic deformation induced either by thermal or by hydraulic loading. The seismic monitoring system is composed of Acoustic Emission (sensitive between 1kHz and 60kHz) enabling monitoring fracturing processes of sub-decimeter size. Furthermore, a fibre optic network will be installed in the heating boreholes to measure spatially temperature variationsvia Distributed Temperature Sensing technology in the investigation area. Active seismic surveys, using different source types, are scheduled before and after the experiment to determine the structural network but also to detect the appearance of new structures triggered from the hydro-thermal pressurization of the fault by tomography and reflection seismic methods. The overall goal of our work is to present the interaction between the different geophysical methods that we are using as well as some preliminary results. A first part is dedicated to the description of the fault zone through field and core samples observations as well as borehole to borehole correlation, whereas the second is dedicated to preliminary results on the thermal diffusion expected in the fault.

How to cite: Bonnelye, A., Dick, P., Cotton, F., Giese, R., Guglielmi, Y., Jougnot, D., Henninges, J., Kwiatek, G., and Lüth, S.: CHENILLE: Coupled beHavior undErstaNdIng of fauLts: from the Laboratory to the fiEld, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10259, https://doi.org/10.5194/egusphere-egu22-10259, 2022.

EGU22-12748 | Presentations | ERE5.2

Crack healing in salt: time-resolved 3D microtomography 

Yuntao Ji, Christopher Spiers, Suzanne Hangx, Hans de Bresser, and Martyn Drury

Rocksalt caverns are considered or already used as storage for nuclear waste, petroleum, hydrogen, CO2, and compressed air energy because of the low permeability and potential of fracture healing of salt. An important concern is the sealing capacity. Undisturbed rocksalt deposits in nature generally have very low permeability. However, as a result of excavation stress, a network of fractures will be induced within the rocksalt formation, increasing the permeability. At low deviatoric stresses and/or at low effective stresses, a fracture network filled with brine is expected to heal, and the connectivity of the brine-filled network, consisting of grain boundaries, pores, and microcracks, is expected to decrease over time. The driving force for such a healing process is the tendency to reduce the interfacial energy by reducing the total interfacial area. In order to assess the rate of pore reconfiguration and permeability evolution in damaged salt and to capture the key process of crack network evolution during healing, we employ time-resolved 3D microtomography to study the long-term evolution of the fracture network of small-scale polycrystalline rocksalt samples. We found that precipitation prefers to occur in open spaces in the early stage of healing, such as new cracks. As a result, flat cracks evolve into zigzag cracks, which create narrow throats, thereby reducing the permeability of the crack network. Our study also offers a way to testify the thermodynamic models quantitatively.

How to cite: Ji, Y., Spiers, C., Hangx, S., de Bresser, H., and Drury, M.: Crack healing in salt: time-resolved 3D microtomography, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12748, https://doi.org/10.5194/egusphere-egu22-12748, 2022.

EGU22-12855 | Presentations | ERE5.2

Direct shear experiments to investigate the effect of chemical alteration on fault frictional behaviour in granitic geothermal systems 

Nick Harpers, Nathaniel Forbes Inskip, Michael John Allen, Daniel Faulkner, Hannes Claes, Andreas Busch, and Sabine den Hartog

Enhanced temperature gradients related to locally elevated heat production in granitic plutons offer the potential for low carbon geothermal energy production. Cornwall in SW England hosts several granitic plutons that are the subject of current geothermal projects (United Downs Deep Geothermal Power [UDDGP] Project and Eden Project). These projects target fault zones in crystalline rock that provide pre-existing pathways for fluid flow. Reinjection of cooler fluids into the reservoir after heat extraction may result in chemical disequilibrium with the host rock, potentially driving precipitation or chemical alteration. Such changes could influence the frictional properties of the fault zones, and hence require modifications to numerical risk-based calculations of the likelihood, or not, of induced seismicity.

In order to study the effects of such alterations, we have conducted a series of direct shear experiments under representative in-situ conditions on Cornish Carnmenellis granite samples which have undergone varying degrees of natural chemical alteration. The direct shear experiments were conducted on gouges (grain size < 125 μm) and at effective normal stresses of 80-105 MPa, pore fluid pressures of 25-50 MPa and temperatures of 16-180 °C. These conditions are relevant for the depths where the UDDGP project injection and production boreholes intercept the Porthtowan Fault zone, the assumed main conduit for fluid flow. In each test, load point velocity was stepped between 0.3 μm/s, 1 μm/s and 3 μm/s, and shear resistance of the sample was measured to determine the stability of sliding and thus the likelihood of induced seismicity as a function of degree of alteration. Initial shear tests at room temperature suggest little difference in the frictional response of altered and unaltered samples.

How to cite: Harpers, N., Forbes Inskip, N., Allen, M. J., Faulkner, D., Claes, H., Busch, A., and den Hartog, S.: Direct shear experiments to investigate the effect of chemical alteration on fault frictional behaviour in granitic geothermal systems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12855, https://doi.org/10.5194/egusphere-egu22-12855, 2022.

EGU22-12888 | Presentations | ERE5.2

A semi-automatic workflow for structural interpretation of large point-cloud Digital Outcrop Models on complex fractured metamorphic rocks (Aosta Valley, Italy) 

Bruno Monopoli, Andrea Bistacchi, Federico Agliardi, Gloria Arienti, Giovanni Dal Piaz, Davide Bertolo, and Stefano Casiraghi

Characterization of fracture networks, both in fault zones and in the less-fractured background, is essential for the analysis and modelling of mechanical and hydraulic properties of the rock mass (i.e. rock plus fractures). Here we present our experience in characterizing fracture networks and other structural features on large outcrops of different basement and metamorphic cover units in the Penninic, Austroalpine and Helvetic units of the Aosta Valley. These units show a variety of lithological, mechanical, and rheological characteristics and were subjected to different ductile and brittle tectonic evolution, resulting in complex combinations of compositional layering, metamorphic schistosity, and fracture networks.

Our methodology is based on a combination of traditional field surveys and remote-sensing techniques such as ground-based and UAS photogrammetric surveys, and terrestrial or helicopter laser scanning. The first task, whose importance is too often overlooked, is represented by selecting outcrops that are representative in terms of structural and lithological properties of a larger rock volume, based on a thorough knowledge of regional structural geology and tectonics. The field survey is carried out with traditional techniques, paying attention to the kinematics, relative chronology, and mineralization (e.g. veins or mineral coatings) of structures. These features, that are often overlooked in fracture studies, are fundamental to frame the evolution of a complex schistosity and fracture network, to separate tectonic fractures with respect to those related to slope dynamics, and to develop predictive models of fracturing at depth (where slope-related fracture will not be present). At the same time, remote-sensing datasets are collected. The choice of the survey technique (terrestrial vs. aerial, photogrammetry vs. laser scanning) depends on various conditions, but in all cases the output is a point cloud DOM, colorized with RGB values, that should have a density (points/area) sufficient to characterize the smallest relevant structural features. From this, also textured surface DOMs and/or DEM plus orthophotos (for almost flat outcrops) can be obtained.

The first step of DOM analysis is carried out “manually”, selecting facets and traces with suitable software tools (e.g. Compass plugin in CloudCompare). This allows selecting different sets of structures, characterizing their orientation statistics, and assigning them to sets defined in the field (with kinematics, chronology, etc.). This step also allows understanding how well the structural features recognized in the field are represented in the DOM. The second step of DOM analysis consists in an automatic segmentation (in case of a point cloud) or tracing (in case of a DEM of triangulated surface textured with images) with algorithms calibrated with results of the manual interpretation. Overall, this results in a supervised semi-automatic workflow, allowing to extract huge structural datasets in a reasonable time, maintaining the connection with kinematic and chronological observations carried out in the field.

The fracture datasets can be eventually characterized with tools allowing to measure statistical distributions of different parameters of the fracture sets using virtual scanlines and/or scanareas, and these distributions can be used to model different properties of the fracture networks or generate stochastic DFN models.

How to cite: Monopoli, B., Bistacchi, A., Agliardi, F., Arienti, G., Dal Piaz, G., Bertolo, D., and Casiraghi, S.: A semi-automatic workflow for structural interpretation of large point-cloud Digital Outcrop Models on complex fractured metamorphic rocks (Aosta Valley, Italy), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12888, https://doi.org/10.5194/egusphere-egu22-12888, 2022.

EGU22-1624 | Presentations | ERE5.3

Hydraulic fracture interactions with mineral grains 

Keita Yoshioka, Masafumi Katou, Kohei Tamura, Yutaro Arima, Yoshiharu Ito, Youqing Chen, and Tsuyoshi Ishida

Hydraulic fractures often turn or branch, interacting with pre-existing discontinuities (e.g. natural fracture, grain boundary). Such fracture complexities, especially in the proximity of borehole, impact the subsequent well conductivity. When a fracture finds a discontinuity, it either penetrates or deflects depending supposedly on the in-situ stress and the discontinuity geometry. However, our hydraulic fracture experiments on carbonates show that the fractures deflected more frequently at a grain boundary as they propagated farther away from the borehole. In other words, the fracture complexity consistently increases with the propagation distance. In this study, using energy release rate analyses, we show that the energy dissipation of a penetrating fracture increases with the distance away from the borehole. This means, the farther away the hydraulic fracture propagates, the more easily it deflects at a grain boundary from the energetic point of view. This tendency was also confirmed by numerical hydraulic fracture simulations based on a successive energy minimization approach. Our findings challenge the conventional hydraulic fracture penetration/deflection criteria based only on the in-situ stress and the discontinuity geometry. 

How to cite: Yoshioka, K., Katou, M., Tamura, K., Arima, Y., Ito, Y., Chen, Y., and Ishida, T.: Hydraulic fracture interactions with mineral grains, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1624, https://doi.org/10.5194/egusphere-egu22-1624, 2022.

EGU22-2089 | Presentations | ERE5.3

Anisotropic fault permeability upscaling and modeling of fault CO2 migration scenarios during geologic carbon sequestration 

Lluís Saló-Salgado, Steve Davis, and Ruben Juanes

Accurate assessment of fault-related CO2 migration hazard is required to deploy geologic carbon storage at the gigaton scale. First, we present a novel methodology, PREDICT, to model the intrinsic permeability of faults in siliciclastic sequences. PREDICT models realizations of the fault core consistent with the stratigraphy, and computes the probability distributions for the directional components (dip-normal, strike-parallel and dip-parallel) of the fault-scale permeability tensor. PREDICT accounts for uncertainty in the geologic variables influencing fault permeability and was developed for scenario building and risk management.

Second, we show how to leverage PREDICT to build geologically-realistic fault leakage scenarios using a model of the Miocene offshore Texas, Gulf of Mexico. The process includes selection of anisotropic, upscaled fault permeability values from PREDICT’s output, upscaling of multiphase-flow fault properties (relative permeability and capillary pressure), and CO2-brine numerical simulation for hundreds of years. CO2 migration through the fault and into overlying units is tracked in each scenario, and results are compared with SGR-based fault property modeling.

How to cite: Saló-Salgado, L., Davis, S., and Juanes, R.: Anisotropic fault permeability upscaling and modeling of fault CO2 migration scenarios during geologic carbon sequestration, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2089, https://doi.org/10.5194/egusphere-egu22-2089, 2022.

Temperature estimation in hydrothermal reservoirs is a critical point for the feasibility of geothermal projects and subsequent processes, such as chemical and biological activity as well as thermal stresses. As flowing fluid and surrounding host rock locally diverge in temperature until equilibrium occurs, heat transfer between phases needs to be described. However, this is a challenging task, especially in fractures, because the heat transfer coefficient depends on various parameters, such as flow velocity and aperture. Heat transfer characteristics in fracture networks, and their dependence on fracture network characteristics, have been rarely studied so far.

Starting from a newly developed analytical solution of heat transfer in single fractures, a consistent formulation for heat transfer in fractured reservoirs is presented. Using an intermediate step of bench-scale experiments, the sensitivity of the temperature field in the fracture network with respect to the heat transfer coefficient is investigated. Due to multiple flow paths within a reservoir, the heat transfer capabilities of individual fractures can become less relevant in well-connected reservoirs. On the other hand, single fractures with uncommon velocity or aperture values can cause local heterogeneities in the temperature field due to the velocity-dependent heat transfer.

Bridging the gap between well-defined networks with a limited number of fractures and large-scale fracture networks of arbitrary shape requires a change in the parameters used. On large scale, effective values such as fracture density and anisotropic permeability are more suitable and accessible than single fracture apertures. To incorporate such a change in parameterization, a new theoretical framework based on the assumption of fracture networks with a regular geometry is presented.

The presented work sheds new light on the heat transfer mechanisms in fractures and fracture networks and is the first attempt to derive a consistent mathematical framework for heat transfer in fractures across scales.

How to cite: Heinze, T.: Heat transfer across scales: from single fractures to fracture networks, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2163, https://doi.org/10.5194/egusphere-egu22-2163, 2022.

EGU22-3960 | Presentations | ERE5.3

Pore-scale modeling of acid etching in a carbonate fracture 

Renchao Lu, Xing-Yuan Miao, Olaf Kolditz, and Haibing Shao

Acid fracturing has been widely used in the oil and gas industry to increase permeability in carbonate reservoirs. In recent years this chemical stimulation technique has been borrowed from the oil and gas industry, employed in the enhanced geothermal systems at Groß Schönebeck, Germany (Zimmermann et al., 2010), and at Soultz-sous-Forêts, France (Portier et. al., 2009). In concept, acid fracturing utilizes strong acids that react with acid-soluble rock matrix in order to non-uniformly etch fracture surfaces. The permeability-enhancing effect depends upon the degree of surface irregularity after pore-scale acidizing which is affected by the compositional heterogeneity of the reacting rock matrix, fracture aperture heterogeneity, and flow and transport heterogeneity. In order to have an insight into these impacts on the acid etching process with the final goal of determining optimum operating conditions (e.g., acid type and acid injection rate), a pore-scale acid-fracturing model is needed. The core components of the pore-scale acid-fracturing model consist in tracking the motion of the fluid-matrix boundary surface induced by acid etching. To date, a number of front tracking approaches (e.g., local remeshing technique, embedded boundary method, immersed boundary method, and level-set method) have been proposed by many researchers in order for moving boundary problems. Each approach has its pros and cons. In this work, we propose employing the phase-field approach as an alternative to the existing front tracking approaches to capture the physically sharp concentration discontinuities across the liquid-solid interface. The developed pore-scale acid-fracturing model includes the Stokes-Brinkmann equations for fluid flow in the fracture-matrix system, the multi-component reactive transport equation for transport of solute species in the rough-walled fracture, and the phase-field equation for the reaction-driven motion of the fluid-matrix boundary surface. Through this numerical study, we demonstrate that the phase-field approach is viable to track recession of carbonate fracture surface by acid etching and to capture the solute concentration jump (w.r.t., Ca2+, H+, and HCO3) across the solid-liquid interface.

 

Reference

Zimmermann, G., Moeck, I. and Blöcher, G., 2010. Cyclic waterfrac stimulation to develop an enhanced geothermal system (EGS) — conceptual design and experimental results. Geothermics, 39(1), pp.59-69.

Portier, S., Vuataz, F.D., Nami, P., Sanjuan, B. and Gérard, A., 2009. Chemical stimulation techniques for geothermal wells: experiments on the three-well EGS system at Soultz-sous-Forêts, France. Geothermics, 38(4), pp.349-359.

How to cite: Lu, R., Miao, X.-Y., Kolditz, O., and Shao, H.: Pore-scale modeling of acid etching in a carbonate fracture, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3960, https://doi.org/10.5194/egusphere-egu22-3960, 2022.

EGU22-4116 | Presentations | ERE5.3

Towards validating numerical simulations of drawdown in unconfined fractured rocks with field experiments: A comparative study at sub-seismic scale 

Maximilian O. Kottwitz, Anton A. Popov, Simon Freitag, Wolfgang Bauer, and Boris J. P. Kaus

Quantifying the effective permeability structure of fault and fracture zones is crucial for numerous geo-energy applications, especially at sub-seismic scales. However, the multi-scale presence of fractures and the structural heterogeneity of faults and host rocks often cause highly non-stationary and anisotropic hydraulic properties. This usually impedes the definition of representative elementary volumes and complicates the upscaling process. Thus, progressively integrating these multi-scale complexities into 3D numerical models of exploration targets has gained increasing scientific interest in recent years and is crucial to make predictions of flow and transport through reservoirs.

Here, we aim to reproduce multiple drawdown curves obtained in analog field pumping tests with numerical models of fluid flow in order to develop a proof of concept for generating correct hydraulic representations of fault and fracture zones in numerical models with the final goal to upscale their effective permeabilities for numerical simulations above the sub-seismic scale.

The test subject is a 30- by 30-meter-wide area in a quarry in the Franconian Alb, Germany, featuring an intensively deformed Upper Jurassic limestone formation, frequently explored for geothermal energy production in the southern German Molasse Basin. First, an initial 3D structural model of the main faults, fractures, and layer surfaces, based on multiple borehole logs and pavement traces is constructed with the GemPy software. In the next step, we employ a newly developed discretization method to convert the initial 3D GemPy model into various equivalent continuum models of the test field by parameterizing fracture, fault, and rock matrix permeabilities/porosities, resulting in high-resolution 3D voxel models with individual, anisotropic permeability tensors. Those serve as input for numerical simulations of a pumping test, where we solve for transient, unsaturated/saturated Darcy-flow using a newly developed parallel, 3D finite element code that utilizes a van Genuchten approximation for the arising non-linearities, i.e., relative permeability and water content. As a final step, we compare the drawdown curves logged in three observation wells in an analog constant-head hydraulic test in the field to the ones obtained from the numerical simulations by computing a cumulative misfit. While changing the parameters of the employed permeability-porosity parametrizations for faults, fractures, and rock matrix in a classical forward-approach manner, we can determine a range of best-fitting models. Preliminary results show that with some educated initial guesses on the hydraulic properties of the reservoir, we could reproduce the drawdown curves in two observation wells with a relative error below one percent after a couple of tens of simulations. The uniqueness of those results will be assessed during the discussion.

How to cite: Kottwitz, M. O., Popov, A. A., Freitag, S., Bauer, W., and Kaus, B. J. P.: Towards validating numerical simulations of drawdown in unconfined fractured rocks with field experiments: A comparative study at sub-seismic scale, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4116, https://doi.org/10.5194/egusphere-egu22-4116, 2022.

EGU22-4620 | Presentations | ERE5.3

Discrete fracture network analysis of Devonian carbonate rocks in Western Germany: Implications for deep geothermal energy, heat exploitation and anthropogenic fault reactivation 

Alessandro Verdecchia, Chelsea Pederson, Luca Smeraglia, Kevin Lippert, Adrian Immenhauser, and Rebecca Harrington

Faults and fractures in carbonate reservoirs strongly influence subsurface fluid movement and can determine the success or failure of geothermal energy and heat production projects. Characterizing their physical and hydraulic properties is therefore crucial. Firstly, because they strongly control the secondary porosity and permeability of the reservoir, which are key parameters for the estimation of the reservoir quality, and for the planning of injection/extraction strategies. Secondly, because upon anthropogenic reactivation, they can lead to felt seismic activity, which could interrupt operations and potentially lead to damage to infrastructure and endanger the population.

Devonian carbonate rocks underlie a vast portion of North Rhine-Westphalia in Western Germany. Their stratigraphic thickness (up to 1,300 m), location, and depth, make them a potential reservoir for deep geothermal heat and energy exploitation. While estimated at depths between 1.3 km and 6 km, outcrop analogues of these Devonian carbonates are exposed in a number of quarries in the region.

This work quantitatively characterizes the fracture and fault distribution and permeability of the Devonian limestones and dolostones exposed at the the Steltenberg quarry, located at the northern margin of the Remscheid-Altena Anticline. The units outcropping in the quarry are tectonically affected by splays of the WSW-ENE-trending Ennepe thrust (Variscan), and by post-Variscan NNW-SSE-trending normal faults. We combine field structural analyses and fracture characterization using scan lines with a 3D digital outcrop model and fracture analyses using UAV imagery, to produce 3D Discrete Fracture Network (DFN) models. Preliminary results show three main fracture sets: WSW-ENE-trending and S-dipping fractures parallel to the Ennepe Thrust, WSW-ENE-trending and N-dipping bedding-parallel fractures, and NNW-SSE-trending sub-vertical fractures parallel to the regional post-Variscan normal faults. Our DFN modeling suggests that the latter represent the main pathways for fluid flow with permeability values up to 10-14 m2.

As next steps we will use the DFN modeling results (e.g., fractures sets, permeability tensor) as input for a 3D thermo-hydro-mechanical finite element model aimed at predicting fluid flow, pressure, and stress changes in a potential geothermal reservoir. Modeling, together with fault-related parameters such as slip tendency and fracture susceptibility, will help estimate the potential for fault reactivation and induced seismicity in the region.

How to cite: Verdecchia, A., Pederson, C., Smeraglia, L., Lippert, K., Immenhauser, A., and Harrington, R.: Discrete fracture network analysis of Devonian carbonate rocks in Western Germany: Implications for deep geothermal energy, heat exploitation and anthropogenic fault reactivation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4620, https://doi.org/10.5194/egusphere-egu22-4620, 2022.

EGU22-5614 | Presentations | ERE5.3

Phase Field Modelling of Interactions Between Hydraulic Fractures and Natural Fractures 

Xiaoxuan Li, Hannes Hofmann, Keita Yoshioka, Yongjiang Luo, and Yunpei Liang

Hydraulic fracturing is widely applied in unconventional reservoirs to generate fracture networks for productivity enhancement. Interactions between hydraulic fractures and natural fractures have a great impact on fracture propagation. In this study, we use a two-dimensional phase field model to investigate interactions between hydraulic fractures and different frictional or cemented fractures under different in-situ stress, injection rate, natural fracture orientation and strength. We find that with the increasing stress anisotropy, hydraulic fracture is more likely to cross natural fracture and leads to a lower fracture complexity. A moderate injection rate is conducive for complex fractures. The approaching angle between the hydraulic fracture and natural fracture impact fracture topology. Complex fractures are formed when the angles are not so steep. With the increasing strength contrast between natural fractures and the rock matrix, the material heterogeneity increases for hydraulic fractures to generate complex fractures. Compared with frictional NFs, opening stronger cemented NFs requires more pressure than hydraulic fracture propagating outside the interface. The numerical investigations in this study can provide theoretical support and design guidance for fracturing operations in complex geological conditions.

How to cite: Li, X., Hofmann, H., Yoshioka, K., Luo, Y., and Liang, Y.: Phase Field Modelling of Interactions Between Hydraulic Fractures and Natural Fractures, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5614, https://doi.org/10.5194/egusphere-egu22-5614, 2022.

EGU22-5748 | Presentations | ERE5.3

A numerical study on the thermo-mechanical response of deformable fractured systems to advective-diffusive heat transport 

Silvia De Simone, Benoit Pinier, Olivier Bour, and Philippe Davy

Geothermal energy applications involve heat circulation in naturally fractured reservoirs, which are in general difficult to characterize due to the multiscale complexity of the fracture network and therefore the flow. In this context, numerical modeling is key to forecast the performance of geothermal energy applications under a number of scenarios. Numerical modeling is challenging because fractures represent the main pathway for flow and advective transport, but diffusive thermal exchange with the host rock controls the geothermal performance - the two processes occurring on very different length and time scales. Moreover, the host rock cooling provokes thermal contraction which tends to increase the fracture aperture, with direct effects on the flow and the advective transport. Quantify these processes is crucial but in general computational demanding when dealing with large reservoirs with hundreds of thousands of fractures.

In this study we present a novel methodology to simulate thermo-mechanical (TM) heat transport. The method is based on the particle tracking approach in Discrete Fracture Networks (DFN) and it has been implemented in the DFN.Lab software platform. The contribution of the host rock matrix in terms of diffusive heat exchange and thermal contraction/expansion is analytically evaluated, which directly impacts the fracture aperture and therefore the advective heat transfer. The methodology enables investigating the reservoir behavior and optimizing the geothermal performance while keeping the computational effort within reasonable values. Results from simulations of cold fluid injection show that rock contraction accelerates the advective transport resulting in a faster recovery of cold fluid at the outlet. We analyze systems of fractures with different characteristics (density, aperture, geometrical patterns, ...) and we identify the parameters that mostly impact the TM response.

How to cite: De Simone, S., Pinier, B., Bour, O., and Davy, P.: A numerical study on the thermo-mechanical response of deformable fractured systems to advective-diffusive heat transport, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5748, https://doi.org/10.5194/egusphere-egu22-5748, 2022.

EGU22-9292 | Presentations | ERE5.3

The real potential of fractured aquifers for CO2 storage 

Giampaolo Proietti, Valentina Romano, Rajesh Pawar, and Sabina Bigi

The CCS (Carbon Capture & Storage) process involves the capture of CO2 produced by energy production plants, cement factories and refineries, transport to storage sites and injection into deep geological structures with physical and chemical characteristics suitable for long-term confinement. This technology can significantly assess the containment of CO2 emissions into the atmosphere, with an estimated reduction between 12% and 14%. One of the most important phases in which the role of the geoscientist is necessary is the screening of the structures with the suitable geological characteristics for CO2 trapping and the estimation of the injectable mass.

Storage capacity estimates are usually approximate and are based on the average geometric and physical values of the geological formations. Furthermore, not knowing in detail the heterogeneity and complexity of geological structures, many storage efficiency scenarios are presented, which consequently propose very different values. Fractured rocks are one of the largest resources on the earth's surface, and host many of the most important reserves of water, oil and natural gas, and can also be exploited for the storage of gas or carbon dioxide. Determining the dynamic behaviour of fluids within a fractured rock mass is a necessary step in the characterization and definition of a potential site for CO2 injection.

In this work a Discrete Fracture Network (DFN) approach is used to quantify the efficiency of fracture systems to the fluid transport, quantifying the mass of supercritical CO2 injectable in a volume of rock with different fracture intensity in a purely discrete approach, with the utilization of dfnWorks and FEHM software. Using multi-phase reservoir simulations of CO2 injection, we determine the efficiency and storage capacity of fractured rocks. The main result this approach is the introduction of the Efr index which quantifies the efficiency of fracture systems for supercritical CO2 injection. This index allows, starting only from the fracture intensity data and using the equations proposed in the literature for the calculation of the storage capacity, to obtain an immediate and reliable estimate of the volume of the aquifers, which consider the efficiency of fractured aquifers to the fluid flow.

How to cite: Proietti, G., Romano, V., Pawar, R., and Bigi, S.: The real potential of fractured aquifers for CO2 storage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9292, https://doi.org/10.5194/egusphere-egu22-9292, 2022.

EGU22-11289 | Presentations | ERE5.3

A numerical model for CO2 gas migration in a fault zone. 

Valentina Romano, Sabina Bigi, Heeho Park, Albert J. Valocchi, Jeffrey De'Haven Hyman, Satish Karra, Michael Nole, Glenn Hammond, Giampaolo Proietti, and Maurizio Battaglia

In a geological CO2 storage site, the main migration pathways in case of leakage would be compromised boreholes or gas permeable faults or fractures. In this work we propose a modeling workflow based on detailed field data acquired on a fault exposed in the Roman Valley Quarry (Majella Mountain, Italy), to simulate the three-dimensional migration of gas CO2 in the fault zone. The numerical modeling is performed using the open-source multiphase flow simulator PFLOTRAN. This study provides a new methodology to characterize the hydraulic behavior of a fault including all its components, the core and the damage zone, capturing in detail the impact of the fault zone architecture to the migration of CO2. Simulation test results point out the robustness of the modeling approach, highlighting its strong predictive power, and show how most of the gas migrates through the high permeable footwall damage zone, where the injection occurs, whereas some of the gas also migrates through the hanging wall damage zone and the fault core. The buildup of gas pressure in the vicinity of the injection wells demonstrates the need of increasingly accurate modeling of the injection conditions to avoid possible faults reactivation and CO2 leakage. While the technique presented here is applied to a case scenario on carbonate rocks, the proposed methodology can be extended to other geological scenarios, by the appropriate calibration of the geometric and petrophysical parameters of fractures and host rock, to understand the conditions under which faults can promote fluid flow from a reservoir and mitigate the risk of CO2 migration via faults.

How to cite: Romano, V., Bigi, S., Park, H., Valocchi, A. J., Hyman, J. D., Karra, S., Nole, M., Hammond, G., Proietti, G., and Battaglia, M.: A numerical model for CO2 gas migration in a fault zone., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11289, https://doi.org/10.5194/egusphere-egu22-11289, 2022.

EGU22-11415 | Presentations | ERE5.3

Counterintuitive fracturing in a multilayer of more or less competent rocks: Examples in porous carbonates and metamorphic rocks, and explanation with numerical modelling 

Andrea Bistacchi, Mattia Martinelli, Riccardo Castellanza, Gloria Arienti, Giovanni Dal Piaz, Bruno Monopoli, and Davide Bertolo

Characterizing and modelling geometrical and topological characteristics of fracture networks, both in fault zones and in the less-fractured background, is essential for the analysis and modelling of mechanical and hydraulic properties of rock masses (i.e. rock plus fractures). Here we present evidence of a counterintuitive behavior in mechanically layered sequences of different kinds of rocks, from porous carbonates to metamorphic rocks. In our case studies the more intense fracturing, both in terms of fracture density/intensity and number of fracture sets, is observed in the more competent layers, that can be therefore considered the more permeable ones.

In large outcrops of the Island of Gozo (Malta) we have characterized several damage zones in the Lower Globigerina Member (LGM) and Lower Coralline Limestone (LCL). A complete petrophysical and geomechanical characterization of these rocks shows the following properties (LGM vs. LCL): porosity 33% vs. 23%; Young’s modulus 2.4GPa vs. 5.5GPa; Poisson’s coefficient 0.18 vs. 0.15; UCS 14MPa vs. 36MPa; tensile strength 2.3MPa vs. 4.4MPa. Despite the LGM being by far the “softer” mechanical layer, we see that the thickness of the damage zone is about 1/30 in this unit with respect to the LCL, and that, comparing sections at the same distance to the fault core, fracture intensity is about 1/10.

In large outcrops in the Breuil-Cervinia area, at the foots of the Italian side of the Cervino-Matterhorn, we have observed a strikingly similar situation in uniformly fractured rocks (no major fault here) of the Dent Blanche and Combin Nappes. These are, in order of decreasing competence, greenschist facies (possibly formerly blueschist) meta-gabbros and meta-granitoids (Dent Blanche), and prasinites and calcschists (Combin). As in the Gozo case study, our quantitative characterization of fracturing reveals an inverse correlation between competence and fracturing parameters.

To understand the physics behind these observations, we have performed simulations with a geomechanical finite element code. During horizontal extension of a multilayer with variable elastic properties, deviatoric stresses build up much more quickly in less compliant, stiffer rocks. This is because all the different layers are subject to the same strain (horizontal stretching), and stress is controlled by the elastic moduli, resulting in higher deviatoric stresses in more rigid layers. At some point, brittle failure (simulated as plastic yield in continuous FEM codes) takes place in the stiff layers, well in advance with respect to failure in the soft ones. At this point, the simulation reveals a situation where fracturing is confined in the stiff layers. As horizontal stretching continues, failure can occur also in the soft layers, but always in a more limited way.

Even if in the Cervino-Matterhorn case study also pressure solution should have played a role in inhibiting fracturing in calcschists, we feel that this mechanical behavior, observed in very different tectonic environments and lithological units, can be of general relevance and might result in a reevaluation of paradigms used to predict fracturing and hydraulic properties of mechanically layered reservoirs in general.

How to cite: Bistacchi, A., Martinelli, M., Castellanza, R., Arienti, G., Dal Piaz, G., Monopoli, B., and Bertolo, D.: Counterintuitive fracturing in a multilayer of more or less competent rocks: Examples in porous carbonates and metamorphic rocks, and explanation with numerical modelling, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11415, https://doi.org/10.5194/egusphere-egu22-11415, 2022.

EGU22-11868 | Presentations | ERE5.3

Using fractured outcrops to calculate permeability tensors. Implications for geothermal fluid flow within naturally fractured reservoirs. 

Ruaridh Smith, Martin Lesueur, Ulrich Kelka, Daniel Koehn, and Thomas Poulet

Naturally fractured systems are an important component to fluid flow for a variety of applications, in particular geothermal energy extraction. Geothermal reservoirs often have low rock permeability (e.g. limestone reservoirs) where permeability anisotropy is governed at first order by fractured networks controlled by fracture density, orientation and connectivity. These are often difficult to assess and as such permeability estimates can lead to high uncertainties. Understanding how fracture networks influence permeability of reservoirs is an important aspect to geothermal exploration.

Where subsurface data (e.g. seismic and well) are limited, other data sources for characterising the reservoirs are required. Outcrop analogues are excellent areas for the analysis and characterisation of fractures within the host rocks found at depth. 2D fractured cliff faces and pavements provide information on variation in fracture arrangement, distribution and connectivity which can be utilised in thermohydraulic modelling of the geothermal system.

Through imaging of 2D fractured faces within target reservoir rocks and using efficient discretisation and homogenisation techniques, reliable predictions on permeability distributions in the geothermal reservoirs can be made. Using an example from an open pit quarry within the Franconian Basin, Germany, fracture network anisotropy in a geothermal reservoir (Malm) is assessed using detailed structural analysis and numerical homogenisation modelling of outcrop analogues.

Structural analysis shows several events affected the limestone reservoir unit in the area. The first major phase of deformation recorded are steep-angled reverse thrust and strike-slip faulting (stress orientated NNE-SSW) attributed to the Late Cretaceous Inversion. A second deformation phase causing normal faulting and fracturing within a NW-SE stress field is related to the European Cenozoic Rift System (e.g. Eger Rift). The final deformation phase recorded corresponds to the Alpine Orogeny where strike-slip faults and conjugate fractures are formed under a NW-SE compression and NE-SW extension. The faults and fractures are heavily influenced by the Kulmbach Fault, part of the Franconian Lineament Fault System that is observed 10m north of the quarry and active during the multiphase deformation culminating with a reverse throw of 800m.

2D imagery is used to capture the fracture networks interpreted through the structural analysis from which different sets of similar fractures are extracted. These are then digitised and meshed for numerical modelling and homogenisation using MOOSE Framework. Three fractured faces are imaged at increasing distance from the Kulmbach Fault to determine the fault impact on the potential flow within the system. The calculated permeability tensors from the homogenisation show differences in fluid transport direction where fracture permeability is controlled by orientation compared to a constant value which would be more pronounced for larger scale simulations. Therefore, for reliable predictions of geothermal flow within the networks, assigning permeabilities for sets is vital. As a result, it is observed that the orientation of the tensor is influenced by the Kulmbach Fault, and thus faults within the reservoirs at depth should be considered as important controls on the fracture flow of the geothermal system.

How to cite: Smith, R., Lesueur, M., Kelka, U., Koehn, D., and Poulet, T.: Using fractured outcrops to calculate permeability tensors. Implications for geothermal fluid flow within naturally fractured reservoirs., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11868, https://doi.org/10.5194/egusphere-egu22-11868, 2022.

Control volume finite element (CVFE) methods provide flexible framework for modelling flow and transport in complex geological features such as faults and fractures. They combine the finite element method that captures complex flow characteristics with the control volume approach known for its stability and mass conservative properties. The general approach of CVFE methods maps the physical properties of the system onto the element mesh (element-wise properties) while the node centred control volumes span element boundaries. In the presence of abrupt material interfaces between elements which are often encountered in fractured models, the method suffers from non-physical leakage in the saturation solution as the result of control volume discretization used for advancing the transport solution. In this work, we present a discontinuous pressure formulation based on control volume finite element (CVFE) method for modelling coupled flow and transport in highly heterogeneous porous media. We propose the element pair P(1,DG)-P(0,DG), a discontinuous first order velocity approximation combined with a discontinuous low order pressure approximation. The approach circumvents the non-physical leakage issue by incorporating a discontinuous, element-based approximation of pressure. Hence, the resultant control volume representation directly maps to the element mesh as well as to the projected physical properties of the system. Due to the low order nature of the formulation, low computational requirement per element and the improved control volume discretization, the presented formulation is proven more robust and accurate than classical CVFE methods in the presence of highly heterogeneous domains.

How to cite: Al Kubaisy, J., Salinas, P., and Jackson, M.: Discontinuous low order pressure formulation in control volume finite element method for simulating flow and transport in highly heterogeneous porous media, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12372, https://doi.org/10.5194/egusphere-egu22-12372, 2022.

The Wenchang 9/8 area is one of the most promising hydrocarbon accumulation zones in the Pear River Mouth Basin, China. In this area, oil and gas are mainly accumulated in the Zhuhai and Zhujiang formations and their hydrocarbon reservoirs are generally related to faults, which are mainly located at the intersection area between NW-striking faults and NE-striking faults. Furthermore, previous petroleum exploration indicates that oil and gas are mainly sealed by faults. Therefore, high-resolution fault sealing calculation like shale-gauge-ratio (SGR) has a significant influence on further petroleum production. Present methods can only calculate single or discontinuous points of SGR for one fault and does not provide the SGR for the entire fault plane, which could impact future petroleum exploration. Testing several methods, we established the 3D fault plane SGR calculation method, which is based on the Petrel software platform. We then used this method on proven oil-bearing structures and target structures in the Wenchang 9/8 area. The results show that: (1) the 3D fault plane SGR of the fault, which controls the Wenchang 9-3 oil-bearing structure, reaches 35%-45%; the 3D fault plane SGR of the fault, which controls the Wenchang 9-7 oil-bearing structure, reaches 40%-55%. Therefore, the 3D fault plane SGR in Wenchang 9-3 and 9-7 oil-bearing structures are consistent with petroleum production; (2) For the target structures the 3D fault plane SGR in target 1 reaches 35%-55%. This is very high and supposed to be the next promising area in the study area, while the 3D fault plane SGR in target 2 is just 20-25%, which indicates high exploration risk at this target. Accordingly, we will promote this method for exploration targets in other petroliferous basins.

How to cite: Xu, L., Wu, Z., Cheng, Y., and Xu, B.: 3D fault plane SGR calculation for fault sealing in Petrel software: An example from Wenchang 9/8 area of the Pear River Mouth Basin, China, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13140, https://doi.org/10.5194/egusphere-egu22-13140, 2022.

EGU22-531 | Presentations | ERE5.4

Temporal deformation in the Hellisheiði geothermal field and its adjacent Húsmúli injection field explained by poroelastic modelling 

Cécile Ducrocq, Elías Rafn Heimisson, Halldór Geirsson, Thóra Árnadóttir, Gudni Axelsson, Vala Hjörleifsdóttir, and Vincent Drouin

Crustal deformation allows us to monitor and understand critical properties of exploited geothermal systems around the world. The Hellisheiði high-temperature geothermal field (in 2011: 303MWe and 133MWth) in SW Iceland has been previously studied using Global Navigation Satellite Systems (GNSS) and Interferometry Synthetic Aperture Radar (InSAR) data between 2011 and 2015. These studies characterized the subsidence rate related to the extraction of fluids in the Hellisheiði area, as well as a 4-month uplift at the start of injection of geothermal fluids in the Húsmúli area. This uplift was accompanied by significant seismicity culminating with two ML >3.5 earthquakes felt in the surrounding region.

We carry out further analysis of GNSS and InSAR data between 2011 and 2019 that show a total of three uplift events, separated by periods of subsidence or little deformation in the Húsmúli area. The deformation episodes seem to correlate with heightened seismic activity despite the continued decrease of injected mass flow rate in the original injection boreholes.

Here we use a finite element poroelastic model (COMSOL Multiphysics) to relate the extraction and injection of the adjacent Hellisheiði and Húsmúli areas to the ground deformation within the same time span. We assume that the boreholes can be represented by three point-injector sources: one of negative mass flow rate in Hellisheiði, and two of positive mass flow rates in (west and east) Húsmúli. The three sources are necessary to explain the deformation observed between 2011 and 2019. The poroelastic model presents insights into the temporal response of geothermal systems from extraction/injection, changes in exploitations and variability in permeability all of which induce heightened strain and stress in the fractured Húsmúli region. We investigate if poroelastic effects may be responsible for triggering transient earthquake swarms and to what degree poroelasiticy can explain the spatially and temporally complex uplift and subsidence. We suggest this study offers new insights into the Hellisheiði geothermal system that are transferable to geothermal systems around the world.

How to cite: Ducrocq, C., Heimisson, E. R., Geirsson, H., Árnadóttir, T., Axelsson, G., Hjörleifsdóttir, V., and Drouin, V.: Temporal deformation in the Hellisheiði geothermal field and its adjacent Húsmúli injection field explained by poroelastic modelling, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-531, https://doi.org/10.5194/egusphere-egu22-531, 2022.

EGU22-734 | Presentations | ERE5.4

Geophysical and structural characterisation of a granodioritic MD-BTES test-site 

Claire Bossennec, Lukas Seib, Matthis Frey, Thomas Burschil, Anton Hermann Buness, Bastian Welsch, and Ingo Sass

Geothermal energy and thermal energy storage are essential components in balancing a decarbonated future energy supply. The north-eastern shoulder of the Upper Rhine Graben (URG), with its Variscan basement belonging to the Mid-German Crystalline High, is a potential target area for heat storage projects. Ganodioritic units in the city area of Darmstadt provide suitable thermo-mechanical properties to implement a Medium Deep Borehole heat exchanger Thermal Energy Storage (MD-BTES). This study focuses on the structural architecture of such crystalline units, representing a heterogeneous fracture and fault network. An approach combining geophysical characterisation and the analysis of surface fracture network analogue is performed to quantify the dimensions and topology of such a fracture network in the subsurface.

Two 2D seismic profiles helped to characterise the deep subsurface structures of the BTES demo site area and to localise the boundaries between the unweathered basement, the weathered basement, and the overlying sedimentary layers. The weathered basement and Permian volcano-sedimentary and Quaternary fluviatile units build the near-surface groundwater aquifer. This shallow aquifer requires a detailed investigation, performed through electrical resistivity mapping, near-surface S-wave refraction seismic survey, ground-penetrating radar lines and radon emanations profiles, combined with shallow geotechnical drillings. Selected surface analogues are located in the northern Odenwald Massif, the most extensive outcropping section of the Mid-German Crystalline High. The first analogue is a pit located 150 m apart from the BTES demo site. The second is the Mainzer Berg quarry in the Sprendlinger Horst, at a 12 km westbound distance, which belongs to Variscan granodioritic and granitic units with similar properties. Derived from these analogues, the fracture length distribution follows the power-law with an exponent about -2. The main relevant orientations identified are trending N030°E -N040°E, N090°E -N100°E, N120°E -N130°E and N165°E, with an overall fracture density of 3.06 frac.m-1 for the demo site subsurface. Additionally, the connectivity of the fracture network is heterogeneous due to clustering. Such clustering also affects weathered horizons, which constitute the near-surface groundwater aquifer.

These fracture network properties are then implemented into sub-surface semi-artificial discrete fracture network (DFN) models to quantify at the first-order the flow properties of such heat storage rocks. This approach allows a successful characterisation of the BTES site, improves the local reservoir model accuracy and ensures an optimal assessment of the storage system behaviour.

How to cite: Bossennec, C., Seib, L., Frey, M., Burschil, T., Buness, A. H., Welsch, B., and Sass, I.: Geophysical and structural characterisation of a granodioritic MD-BTES test-site, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-734, https://doi.org/10.5194/egusphere-egu22-734, 2022.

Efficient thermal energy storage concepts are key for achieving the ambitious international climate targets. Implemented in thermal energy networks with a high contribution made by volatile renewable energy sources, large-scale applications for sensible heat and cold storage are favourable. They compensate for short-term fluctuations in the energy demand profiles, and they enable solar energy harvested in summer to be recovered for use in winter. Especially when pre-existing infrastructure facilities (e.g., basin installations from disused industrial, water treatment, and stormwater retention facilities) are reused as framework structures for thermal energy storage devices, environmental boundary conditions are often adverse. This is, for example, due to interference with near-subsurface aquifers or due to a suboptimal geometry of the given storage structure. For identifying strengths and weaknesses of a storage facility, and for technological optimization, simulation of thermal processes is vital. By this, the role of subsurface heterogeneity and slowly evolving transient thermal conditions in the storage device as well as in the ambient ground can be analysed. Thus, different degrees of utilisation, potential lateral energy losses or gains, and ultimately the economic viabilities of potential solutions can be evaluated. Most of the existing modelling applications do not address these issues in full detail. In fact, previous studies revealed that originally predicted efficiencies and amortization periods are often not achieved. This can be attributed to insufficiently represented boundary conditions (e.g., steady and uniform ambient temperatures at all exterior storage interfaces) or to rigorous simplifications by symmetric modelling techniques (no possibility to implement asymmetric processes, e.g., groundwater flow in surrounding subsurface).

In our study, we use a new numerical model to represent hydrogeological processes around ground-based thermal storage devices at high resolution and in different respects. In a series of generic scenarios, we focus on fundamental parameters of groundwater and environmental conditions, such as different groundwater levels and flow velocities, and we inspect the influence of various thermophysical (thermal conductivity/storage capacity) and hydraulic material parameters (e.g., porosity, permeability). With these, we analyse effects on storage utilisation rates, thermal losses, and temperature conditions in the surrounding area. Finally, we provide insight into previously neglected influencing factors and offer improvement strategies for the planning and implementation of large-scale, closed, seasonal thermal energy storage systems.

How to cite: Bott, C. and Bayer, P.: Modelling environmental interactions of large-scale, closed seasonal thermal energy storage systems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-856, https://doi.org/10.5194/egusphere-egu22-856, 2022.

EGU22-3659 | Presentations | ERE5.4

Inferring aquitard hydraulic conductivity using transient temperature-depth profiles impacted by ground surface warming 

Victor Bense, Titus Kruijssen, Martine van der Ploeg, and Barret Kurylyk

Aquitard hydraulic properties are notoriously difficult to assess, yet accurate aquitard hydraulic conductivity estimates are critical to quantify recharge and discharge to and from semi-confined aquifer systems via hydraulic head gradients. Such flux quantification is required to evaluate the risks of aquifer exploitation by groundwater abstraction and aquifer vulnerability to surface contamination. In this study, we consider a regionally important aquitard and compare existing hydraulic conductivity estimates obtained through traditional methods to those inferred from long-term hydraulic head monitoring and thermally-derived vertical groundwater fluxes (0.04--0.25 m/y). We estimate the fluxes using numerical modeling to analyse the propagation of decadal climate signals into temperature-depth profiles and fitting the simulated and observed inflection point depths (minimum temperature). Results reveal that climate-disturbed temperature-depth profiles paired with multi-level head data can yield accurate vertical fluxes and aquitard hydraulic conductivities. This approach for characterizing groundwater systems and quantifying flows to and from sedimentary aquifers is more efficient but yields results that are comparable to conventional methods.

How to cite: Bense, V., Kruijssen, T., van der Ploeg, M., and Kurylyk, B.: Inferring aquitard hydraulic conductivity using transient temperature-depth profiles impacted by ground surface warming, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3659, https://doi.org/10.5194/egusphere-egu22-3659, 2022.

EGU22-4198 | Presentations | ERE5.4

Numerical modeling of a granodioritic MD-BTES test-site 

Lukas Seib, Claire Bossennec, Formhals Julian, Welsch Bastian, Matthis Frey, and Ingo Sass

Geothermal energy and thermal energy storages can significantly reduce the consumption of fossil energy resources by storing large amounts of heat in the subsurface, which is especially valuable when dealing with fluctuating renewable energy sources. Crystalline rocks with low hydraulic conductivity are a suitable target for such storage systems due to reduced convective heat losses. In the frame of the research project SKEWS (Seasonal Crystalline Borehole Thermal Energy Storage), a medium deep borehole thermal energy storage demonstrator with four 750 m deep borehole heat exchangers will be built at the Technical University of Darmstadt, Germany. In the preparation phase of this project, an extensive geophysical, petrophysical and structural dataset is gathered for the characterization of the project site’s subsurface.

This multi-disciplinary dataset is used for the creation of a first-order finite element method (FEM) model of the storage reservoir for thermo-hydraulic modelling. The input data includes a large petrophysical dataset for crystalline rocks and a stress-dependent Discrete Fracture Network (DFN) for the hydraulic characterization of the fractured granodioritic basement rock. For numerical analysis of the storage operation cycles, a novel co-simulation approach, using the FEM suite FEFLOW and the Modelica library MoSDH, is used to consider the interconnection between the subsurface heat-exchangers and the surface heating grid. This approach allows for detailed FEM modelling of the subsurface, while being able to take the complexity of the surface heating network into account at the same time. The model will be updated continuously by additional data during the building process of the pilot and the following experiments, to generate a highly detailed and validated numerical model of a heat storage system in a granodioritic reservoir. Ultimately, the presented workflow can serve for the accurate prediction of the performance of upscaled systems and therefore support a well-founded design process of this novel storage technology.

How to cite: Seib, L., Bossennec, C., Julian, F., Bastian, W., Frey, M., and Sass, I.: Numerical modeling of a granodioritic MD-BTES test-site, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4198, https://doi.org/10.5194/egusphere-egu22-4198, 2022.

The storage of low-temperature heat in the near surface underground is already widely used worldwide, whereas only little attempts of storing of higher temperatures have been made so far. However, this can become increasingly important in the heat transition strategy by contributing with this technology to medium and peak load supply. Previous works have demonstrated that a large part of the required thermal energy can be efficiently stored in former oil reservoirs in Tertiary sediments of the URG. The advantage of using depleted oil reservoirs as HT-ATES is that they have a lower overall project risk due to the knowledge of the subsurface from the exploration history and that the geological and geophysical data, which are mostly available, allow a more reliable forecast of efficiency and development costs.

KIT in Karlsruhe has now planned the "Deepstor" HT-ATES research infrastructure for its Northern Campus. The site is adjacent to the former Leopoldshafen oil field and can draw on a large amount of data from boreholes for assessment prior to drilling. The targeted reservoirs is the several meters in thickness consisting of fine-grained calcareous sandstones from the Oligocene Froidfontaine Formation at a depth of approx. 1,300 meters.

The baseline of this study is the interpretation of petrophysical data such as resistivity-, sonic-, gamma and SP-logs to derive hydrogeological and geothermal parameters in 15 deep wells in vicinity of the planned drilling site. An integrated data analysis is performed with simulations to gain a quantitative understanding of the fluid and heat flow of the HT-ATES site and to predict the storage and recuperation capacity. Poro-perm values from core material are used to calibrate the results. The aim is a statistically based assessment of the storage site for planning and cost estimation of the research infrastructure.

This work should provide further insights for the future development of geothermal heat storage and enable the integration of a HT-ATES in the KIT campus.

How to cite: Steiner, U., Ang, N., Bauer, F., and Schill, E.: Characterization of Oligocene Oil Reservoir Sandstones for High Temperature Aquifer Thermal Energy Storage (HT-ATES) in the Upper Rhine Graben (URG), SW Germany, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5084, https://doi.org/10.5194/egusphere-egu22-5084, 2022.

EGU22-5610 | Presentations | ERE5.4

Subsurface warming trends in response to climate change and local heat sources in Central Europe 

Peter Bayer, Susanne A. Benz, Kathrin Menberg, Philipp Blum, Maximilian Noethen, and Hannes Hemmerle

Under natural conditions the thermal signature at the Earth´s surface equilibrates with the geothermal heat flux. Given that downward propagation of heat by conduction and advection is magnitudes lower than the daily and seasonal variation at the surface, these short-phased patterns impart a dampened and long-phased temperature response in the shallow subsurface. While climate change manifests in temperature trends that correlate at decade scale this signature is integrated by the slow heat transfer in gradual subsurface warming. In many places land use and small scale anthropogenic structures overprint the thermal response of the subsurface to climate change at the surface. In our contribution we present evidence of subsurface warming in natural and anthropogenic settings for different case studies in Central Europe. Repeated temperature depth logs reveal that in natural environments shallow subsurface temperature rise is trailing when compared to the rise in surface temperature and diminishes towards greater depths (e.g. +0.35 K per decate at the surface, +0.28 at 20 m, and +0.09 at 60 m below ground level for 32 wells in Bavaria). While in general a coherent pattern is found for different locations in natural environments, site-specific trends have a high spread (e.g. +0.36±0.44 K per decade for 227 wells in Austria) and temperature can also be dependent on vertical or lateral groundwater flow in the region. In built-up areas temperature rise in the subsurface is characterised by a higher variance and often exceeds the rise of surface temperature. Especially in dense urban areas ground temperature is elevated indicating local extreme temperature rises that are magnitudes higher than temperature rise at the surface. The high variance originates partially from the scarcity of reliable and long-term monitoring. Monitoring data typically lacks either depth or time resolution as temperature is either continously logged at a single-depth, erratically measured as depth profile, or measured at the surface during groundwater quality measurements.

How to cite: Bayer, P., Benz, S. A., Menberg, K., Blum, P., Noethen, M., and Hemmerle, H.: Subsurface warming trends in response to climate change and local heat sources in Central Europe, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5610, https://doi.org/10.5194/egusphere-egu22-5610, 2022.

EGU22-5795 | Presentations | ERE5.4

The SAGE4CAN project: The use of shallow geothermal energy from oceanic volcanic islands 

Alejandro García-Gil, Juan Carlos Santamarta, Miguel Mejías Moreno, Carlos Baquedano, Eduardo Garrido Schneider, Teresa Alonso Sánchez, Miguel Ángel Rey Ronco, José Ángel Sánchez-Navarro, Miguel Ángel Marazuela, Alicia Andreu Gallego, and José Manuel Tiscar Cervero

The use of shallow geothermal energy (SGE) resources in oceanic volcanic environments entails additional challenges when compared to continental sedimentary/plutonic settings. The efficiency of shallow geothermal heat exchangers heavily depends on the geology and hydrogeology of the terrain where are placed. Volcanic rocks in small oceanic islands (<5,000 km2) are the result of volcanism, erosion, and tectonic collapse. All these processes conform highly heterogeneous formations with complex hydrogeology whose thermal response to shallow geothermal systems requires a good understanding of heat transfer in such environments. The SAGE4CAN project will concentrate on SGE resource assessment taking into account heterogeneity characteristic of volcanic formations, both at local and insular scale. To this end, the Canary Islands are selected as representative volcanic oceanic islands, to define SGE implementation barriers including but not limited to (1) heterogeneities of thermal properties intrinsic to volcanic formations (volcanic dikes, red layers, landslides, etc.), (2) heat advection in the context of complex groundwater flow in the unsaturated (dominate in midlands and highlands) as well as in the saturated medium (coast), (3) enhanced geothermal gradients, (4) transient effects of urban and volcanic activity, (5) heating and cooling demand, (6) shallow geothermal energy installations design and optimization, as well as (7) energy transition strategies in energy-dependent islands. The SGE4CAN project will investigate novel approaches to overcome such boundary conditions of oceanic volcanic islands in the estimation of the renewability of the resources, developing novel procedures to conduct cost-efficient and open-access Thermal Response Tests (TRTs), investigate the performance of existent SGE systems, assessing environmental impacts associated with SGE use. The knowledge generated from this project will be used on its final stage to identify adequate strategies for the integration of SGE into heating and cooling policies and action plans, as well as to raise awareness about the technology so that it gets recognition.

 

How to cite: García-Gil, A., Santamarta, J. C., Mejías Moreno, M., Baquedano, C., Garrido Schneider, E., Alonso Sánchez, T., Rey Ronco, M. Á., Sánchez-Navarro, J. Á., Marazuela, M. Á., Andreu Gallego, A., and Tiscar Cervero, J. M.: The SAGE4CAN project: The use of shallow geothermal energy from oceanic volcanic islands, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5795, https://doi.org/10.5194/egusphere-egu22-5795, 2022.

EGU22-6763 | Presentations | ERE5.4

Influence of Particle Sizes on Solute and Heat Transport Interpretation 

Ji-Young Baek, Byeong-Hak Park, and Kang-Kun Lee

Tracer experiments have been carried out for various scales to enhance the understanding of transport processes in porous media. The comparison between multi-tracers behaviors could provide insights in using tracers for the aquifer characterization. Especially, the comparison of heat and solute transports has been drawing attention in recent studies based on the similarity of governing equations. However, the difference between influences of particle sizes on heat and solute transport processes has yet to be clarified. In this study, to investigate the impacts of mean grain size (d50) difference on solute and heat transports, laboratory heat, and solute tracer experiments were conducted using two grain sizes of sand (d50 = 0.50, and 0.76 mm). Obtained experimental data were analyzed by mathematical models and those results were compared at 7 different flow conditions for two different mean grain sizes. Compared to other experimental data conducted with various particle sizes, normalized thermal dispersion coefficients showed a wider range of values to the different particle sizes under the same Pèclet number than normalized solute dispersion coefficients, even though the heat transport occurred in smaller Pèclet numbers. These results could indicate that the influence of particle size difference could be more critical in thermal dispersion coefficients.

Acknowledgements

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2017R1A2B3002119). This work was also supported by Korea Environment Industry & Technology Institute(KEITI) through "Activation of remediation technologies by application of multiple tracing techniques for remediation of groundwater in fractured rocks" funded by Korea Ministry of Environment (MOE)(Grant number:20210024800002/1485017890). This work was also supported by the Institute for Korea Spent Nuclear Fuel (iKSNF) and National Research Foundation of Korea (NRF) grant funded by the Korean government (Ministry of Science and ICT, MSIT) (Grant number: 2021M2E1A1085200).

 

How to cite: Baek, J.-Y., Park, B.-H., and Lee, K.-K.: Influence of Particle Sizes on Solute and Heat Transport Interpretation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6763, https://doi.org/10.5194/egusphere-egu22-6763, 2022.

EGU22-7500 | Presentations | ERE5.4

Assessing the geological potential of the Lower Muschelkalk as High Temperature - Aquifer Thermal Energy Storage (HT-ATES) horizon in Berlin (Germany) 

Christian Wenzlaff, Gerd Winterleitner, Lioba Virchow, Simona Regenspurg, Christoph Thielke, and Guido Blöcher

High Temperature - Aquifer Thermal Energy Storage (HT-ATES) offers a promising opportunity for climate-neutral heat supply in urban areas due to their high storage capacity and the possibility of direct integration into the regional district heating system. The assessment of the storage potential of HT-ATES requires reliable numerical models of the corresponding storage formation. To analyse the potential of the Lower Muschelkalk (Middle Triassic) as HT-ATES horizon, an unstructured 3D finite element model of the natural gas storage facility in Berlin/Spandau was developed. At this site, two porous layers (average porosity of 22 %) of oolithic grainstones characterize the target formation with a total thickness of about 30 m and a natural reservoir temperature of 32 °C in a depth of 535 m below ground surface. Beside lab analysis of core samples and fluid samples from the site, slug-withdrawal tests were performed in summer 2021 to identify hydraulic key parameters for the numerical simulations. The results indicate a productivity between 0.5 and 1.2 l/s/bar with reservoir permeability between 250 and 700 mD allowing maximum flow rates between 55 and 135 m³/h. In this study, we present a complete workflow from geological characterisation, lab analysis and field testing to detailed numerical HT-ATES simulations. Furthermore, we compare the storage potential based on different data sources such as solar heating systems and district heating networks. First results from the numerical simulations with storage volumes between 15,000 m³ (solar heating system) and 400,000 m³ (district heating system) show promising mean efficiency values between 60 % and 90 % within 25 years of operation. The hydraulic tests and the underlying numerical simulations indicate that the Lower Muschelkalk is suitable for HT-ATES.

How to cite: Wenzlaff, C., Winterleitner, G., Virchow, L., Regenspurg, S., Thielke, C., and Blöcher, G.: Assessing the geological potential of the Lower Muschelkalk as High Temperature - Aquifer Thermal Energy Storage (HT-ATES) horizon in Berlin (Germany), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7500, https://doi.org/10.5194/egusphere-egu22-7500, 2022.

EGU22-9128 | Presentations | ERE5.4

Thermal and hydraulic effects due to interaction between aquifer thermal energy storage systems 

Martin Bloemendal, Rogier Duijff, and Mark Bakker

Aquifer thermal energy storage (ATES) is a technology to provide energy-efficient heating and cooling to buildings by storage of warm and cold water in aquifers. In regions with large demand for ATES, ATES adoption has led to congestion problems in aquifers. The aquifer utilisation and the recovery of thermal energy stored in aquifers can be increased by reducing the distance between wells of the same temperature. Hence, this approach is implemented in practice, but the understanding of how this affects both the recovery efficiency and the needed pumping energy is missing.

In this research, the effect of well placement on the performance of individual systems is quantified using numerical modelling. Results show an increase in performance of individual systems when the thermal zones of wells of the same temperature are combined. The relative increase of the thermal recovery efficiency is 12% for average-sized systems with a storage volume of 250,000 m3/year, and 25% for small systems (50,000 m3/year). Performance of the combined system improves because the surface area of the thermal zone of the combined system, over which thermal losses occur, is smaller than the sum of the surface areas of the individual systems. Performance improvement is larger for systems with small storage volumes and long well screens. The optimal distance between wells of the same temperature is 0.5 times the thermal radius, following the trade-off between an increase of the thermal recovery efficiency and an increase in pumping energy. The distance between wells of opposite temperature must be larger than 3 times the thermal radius to avoid negative interaction.

How to cite: Bloemendal, M., Duijff, R., and Bakker, M.: Thermal and hydraulic effects due to interaction between aquifer thermal energy storage systems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9128, https://doi.org/10.5194/egusphere-egu22-9128, 2022.

EGU22-9212 | Presentations | ERE5.4

Degassing kinetics of high salinity geothermal fluids 

Chris Boeije, Wolfgang Weinzierl, Pacelli Zitha, and Anne Pluymakers

The formation of free gas bubbles (degassing) is a major issue during production of geothermal fluids. These often contain substantial amounts of dissolved gasses, such as CO2, CH4 and N2. Lower pressures in the region surrounding the production well can cause dissolved gas to come out of the solution. This can have detrimental effects on the production and generally on the operation, such as corrosion of the facilities or reduced water production as the gas limits the space where the water can flow. This study aims to improve the understanding of the conditions under which free gas nucleates, including determination of the bubble point pressure and temperature and the rate at which bubbles form during depressurization.

The focus of this study is on CO2 degassing from high salinity brines. We report a series of well-controlled depressurization experiments in a pressure cell that allows for visual monitoring of the degassing process. The cell is filled with brine saturated with dissolved CO2 at high pressure and temperature. The pressure within the cell can be reduced in a reproducible manner thus allowing for repeatable experiments. A high-speed camera paired with a uniform LED light source is used to record the degassing process. The pressure in the cell is monitored using a transducer synchronized with the camera. The resulting images were analysed using an in-house MATLAB code, which allows for determination of the bubble point pressure and rate of bubble formation. Experiments were performed at high pressure (up to 200 bar) and temperature (up to 200 °C) using a fixed CO2 concentration of 200 mmol/L (i.e. 8.8 g/L). Two saline brine solutions are used to assess the influence of the salt concentration on the bubble nucleation process: a low salinity (1 M NaCl) and a high salinity (1.5 M CaCl2 + 2 M NaCl) solution.

A model based on the geochemical software PHREEQC was also developed to predict the solubility of CO2 in high salinity geothermal brines. This model allows for simulating the degassing behaviour at the same conditions as those used in the experiments. From these simulations, the theoretical bubble point pressure and temperature can be estimated along with the rate of gas exsolution during a depressurization process. As there are several alternative equation-of-states for CO2 in solution with brines, a comparative matching of the depressurization experiments with individual formulations is presented.

How to cite: Boeije, C., Weinzierl, W., Zitha, P., and Pluymakers, A.: Degassing kinetics of high salinity geothermal fluids, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9212, https://doi.org/10.5194/egusphere-egu22-9212, 2022.

EGU22-9263 | Presentations | ERE5.4

Heat transport by flow through rough rock fractures 

Maria Klepikova, Yves Méheust, Clément Roques, and Niklas Linde

Fracture surface topography exhibits long-range spatial correlations resulting in a heterogeneous aperture field. This leads to the formation, within fracture planes, of preferential flow channels controlling flow and transport processes. We have investigated numerically the influence of the statistical properties of the aperture field and upscaled hydraulic behavior on heat transport in rough rock fractures with realistic geometries. Similarly to the rough fracture's hydraulic behaviour, we find that its heat transport behaviour deviates from the conventional parallel plate fracture model with increasing fracture closure and/or decreasing correlation length.  We demonstrate that the advancement of the thermal front is typically slower in rough fractures compared to smooth fractures having the same mechanical aperture. In contrast with previous studies that neglect temporal and spatial temperature variations in the rock matrix, we find that the thermal behavior of a rough-walled fracture can, under field-relevant conditions, be predicted from a parallel plate model with an aperture equal to the rough fracture's effective hydraulic aperture. The practical implication of our finding is that thermal exchanges at the scale of a single fracture is controlled by the effective hydraulic transmissivity. Provided that thermal properties of the host rock are known, this implies that (1) geothermal efficiency can be computed at field sites using hydraulic characterization alone, and predicted using well-known low-dimensional hydraulic parameterizations in terms of effective hydraulic properties and (2) heat tracer tests are reliable for inferring effective fracture transmissivity.

How to cite: Klepikova, M., Méheust, Y., Roques, C., and Linde, N.: Heat transport by flow through rough rock fractures, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9263, https://doi.org/10.5194/egusphere-egu22-9263, 2022.

EGU22-9562 | Presentations | ERE5.4

Rock Garden test site – hydraulics in porous fractured media 

Andreas Englert and Peter Bayer

Understanding of subsurface flow and transport is of major interest supporting optimal design for several societal relevant technologies, such as waste disposals, geothermal or groundwater production facilities. To advance measurement and modeling techniques and refine them for practical applications, we further developed the fractured aquifer test site Rock Garden at the Martin Luther University Halle. The Rock Garden test site is situated beneath the courtyard of the Faculty of Natural Sciences III and is 60 m x 60 m in size. Fractured Rotliegend series of conglomerates, sand- and siltstones are investigated at the site by 6 drillings. A central borehole (B3) is 40 m in depth and developed as an open borehole between 15 m - 40 m below surface. Five boreholes are developed as groundwater observation wells of about 20 m depth and are equipped with filter screens between 10 m - 20 m below surface. Natural groundwater levels are on average about 3 m below surface and vary about 0.5 m around this value. The average gradient varies as a function of time between 0.3 % and 0.5 %, direction east northeast. A first pumping test in B3 unraveled hydraulic connection to all of the five surrounding boreholes. The effective transmissivities are of the order of 10-5 m2/s and storativities are of the order of 10-4. To understand hydraulically active fractures or fracture zones and their connection to the rock matrix at the Rock Garden site, a first flowmeter experiment was performed in well B3. Under natural conditions no flowmeter signals have been detected suggesting vertical ambient flow to be smaller than 7 cm/min. Under pumping conditions, the flowmeter signals suggest diffuse horizontal inflow from conglomerate lenses (about 80 % of the total inflow) and discrete horizontal inflow from fractures in clay and siltstones (about 20 % of the total inflow). To characterize these fractured and porous zones in detail, we plan performing hydraulic and tracer tomography at the Rock Garden test site in the near future.

How to cite: Englert, A. and Bayer, P.: Rock Garden test site – hydraulics in porous fractured media, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9562, https://doi.org/10.5194/egusphere-egu22-9562, 2022.

EGU22-9581 | Presentations | ERE5.4 | Highlight

High Temperature ATES in combination with power-to-heat: maximizing renewable energy use for a local energy system 

Stijn Beernink, Els van der Roest, Jan Peter van der Hoek, Niels Hartog, and Martin Bloemendal

To reduce worldwide greenhouse gas (GHG) emissions, fossil fuels are being replaced by renewable energy in a rapid tempo. As a result, the energy system becomes more decentralized with e.g. PV systems as a source for local multi-energy systems, with aim to become as self-sustainable as possible. This is challenging because these systems often rely on an intermittent energy source (production mainly in summer), which is not aligned with energy demand (mainly in winter). One solution for this problem is the combination of power-to-heat (PtH) with High Temperature Aquifer Thermal Energy Storage (HT-ATES), which allows for flexible and effective utilisation and storage of available green electricity to match the availability and demand of sustainable electricity. Currently, insights in the practical potential of this solution and methods for effective integration of PtH and HT-ATES in multi-energy systems are lacking. Therefore, we assessed methods to improve the integration and control of a HT-ATES system and tested varying ways of integration for a local decentralized multi-energy system. To this end, we expanded and integrated a multi-energy system model with a numerical hydro-thermal model to dynamically simulate the functioning of the integrated HT-ATES. The impact of key design parameters (heat pump size, storage temperature, cut-off temperature) on overall energy performance and the effect of different methods for integration of the local energy system were simulated and analysed. 

Results show that the integration of HT-ATES with PtH allows for providing the local energy system with 100% of the yearly heat demand with a 25% smaller heat pump than without HT-ATES. Also, compared to Pth without storage, the yearly energy use pattern changes dramatically to match the availability of renewable electricity. An inventive mode of operation was designed which allows for lowering the threshold temperature of the HT-ATES by an innovative integration of the heat pump. This mode of operation increases the HT-ATES performance and decreases the overall costs of heat production. Overall, this study shows that the integration of HT-ATES in a multi-energy system is suitable to cost-effectively match annual heat demand and supply, and to increase local sustainable energy use. Solutions like these show high potential to decentralize energy production/use, to decrease pressure on the power grid and to increase total renewable energy use.

How to cite: Beernink, S., van der Roest, E., van der Hoek, J. P., Hartog, N., and Bloemendal, M.: High Temperature ATES in combination with power-to-heat: maximizing renewable energy use for a local energy system, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9581, https://doi.org/10.5194/egusphere-egu22-9581, 2022.

EGU22-9780 | Presentations | ERE5.4

A novel method for thermo-hydro-chemical models for Aquifer Thermal Energy Storage 

Rubén Vidal and Maarten W Saaltink

Aquifer Thermal Energy Storage (ATES) is a technology that injects heat into aquifers during low energy demand and extracts it during high demand. ATES generates variation of temperature in the underground that can lead to chemical reactions. These reactions can affect the efficiency of ATES and modify the groundwater chemistry and the properties of soils and rocks. We present a novel method that allows calculation of complex numerical models and understanding the thermo-hydro-chemical processes in ATES in a simple way. Aqueous and mineral reactions must be assumed in equilibrium.  The method decouples the chemistry from the thermo-hydraulic processes. The chemical part of the method consists of chemical batch calculations in which minerals dissolve/precipitate and water chemistry varies as a result of changing temperature. The thermo-hydraulic part consists of calculating temperature and spatial and temporal derivatives of temperature. From this, chemical composition of groundwater and precipitation/dissolution rates of minerals can be calculated straightforwardly.

We have applied the method to a HEATSTORE benchmark case, which is inspired by an ATES pilot project located in Bern, Switzerland. We used PHREEQC for the chemical calculations and for the thermo-hydraulic modelling we used the finite element code CODE_BRIGHT. The results permit us to understand better the reactive transport processes in the aquifer (which we divided into mixing, heat retardation and heat conduction), changes in the porosity of the rocks and the precipitation and dissolution of minerals.

 

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 (2021 FI_B 00940).

How to cite: Vidal, R. and Saaltink, M. W.: A novel method for thermo-hydro-chemical models for Aquifer Thermal Energy Storage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9780, https://doi.org/10.5194/egusphere-egu22-9780, 2022.

EGU22-11755 | Presentations | ERE5.4

GIS-based Aquifer Thermal Energy Storage (ATES) systems potential assessment in Spain 

Adela Ramos Escudero and Martin Bloemendal

Aquifer Thermal Energy Storage (ATES) is a technology that provides sustainable and cheap space heating and cooling. Its successful application is directly dependent on the presence of a suitable aquifer and local climatic conditions.

In Spain, there is not yet a mature market for ATES. There are no specific standards or norms and hardly any practical guidelines have been developed. This work presents a methodology that assesses the potential for ATES in Spain using subsurface and climatic data processed with GIS. The method identifies aquifers with possible thermal use and areas where the climatic conditions are favorable for ATES for the residential sector. Based on these conditions, urban areas located in favorable areas are identified. Their associated population allows making an approximation of the ATES market size in Spain. Results show that 38% of the aquifers in Spain show potential for ATES and 63% of large urban areas in Spain are located in such areas. Also, 50% of the population lives in areas where the residential sector appears to be suitable for ATES based on climatic conditions.

How to cite: Ramos Escudero, A. and Bloemendal, M.: GIS-based Aquifer Thermal Energy Storage (ATES) systems potential assessment in Spain, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11755, https://doi.org/10.5194/egusphere-egu22-11755, 2022.

EGU22-11934 | Presentations | ERE5.4

Numerical modelling of Aquifer Thermal Energy Storage systems with Surface-Based Geologic modelling and Dynamic Mesh Optimisation 

Geraldine Regnier, Pablo Salinas, Carl Jacquemyn, and Matthew D. Jackson

Aquifer Thermal Energy Storage (ATES) has significant potential to provide large-scale seasonal cooling and heating in the built environment, offering a low-carbon alternative to fossil fuels. To deliver safe and sustainable ATES deployments, accurate numerical modelling tools must be used to predict flow and heat transport in the targeted aquifers. However, numerical simulation of ATES systems is very challenging, due to the associated high computational cost of capturing fluid flow and heat transport at a high resolution and importance of accurately modelling complex geological heterogeneity.

Here, we present a novel approach to simulate ATES, based on the use of surface-based geologic models (SBGM), a double control-volume finite element method, and unstructured tetrahedral meshes with dynamic mesh optimisation (DMO). Previous use of DMO for a range of porous media flow applications has allowed an important reduction in the cost of numerical simulations. DMO allows the resolution of the mesh to vary over time and space to satisfy a user-defined solution precision for selected fields, refining where the solution fields are complex and coarsening elsewhere. SBGM allows accurate representation of complex geological heterogeneity and efficient application of DMO, essential for accurate simulation of ATES without excessive computational cost. 

We demonstrate application of these methods in two low-temperature ATES scenarios: a homogeneous aquifer, and a heterogeneous fluvial aquifer containing meandering, channelised sandbodies separated by mudstones. For both cases, cold and warm water are injected alternatively over 6-month periods via a well doublet. We demonstrate that DMO reduces the required number of mesh elements by a factor of up to 22 and simulation time by a factor of up to 15, whilst maintaining the same accuracy as an equivalent fixed mesh. DMO significantly reduces the computational cost of ATES simulations in both homogeneous and heterogeneous aquifers. This offers significant advantages compared to conventional methods in assessing the impact of uncertain geologic heterogeneity on ATES operation and efficiency, and in optimising individual and multiple ATES deployments.

How to cite: Regnier, G., Salinas, P., Jacquemyn, C., and Jackson, M. D.: Numerical modelling of Aquifer Thermal Energy Storage systems with Surface-Based Geologic modelling and Dynamic Mesh Optimisation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11934, https://doi.org/10.5194/egusphere-egu22-11934, 2022.

EGU22-12456 | Presentations | ERE5.4

Evaluating the sustainability of low enthalpy geothermal applications in a subsurface heat island 

Alberto Previati, Valerio Silvestri, Paolo Frattini, and Giovanni B. Crosta

Low enthalpy geothermal applications such as ground coupled heat pumps (GCHP) and groundwater heat pumps (GWHP) are an attractive low-carbon solution for heating and cooling of buildings. Their efficiency depends on the subsurface thermal properties (e.g. thermal conductivity, heat capacity) and the hydrogeological/thermal regimes (e.g. groundwater flow, depth of the water table, temperature profile). The geothermal potential is an indicator used to quantify and compare the ability to exchange heat with the subsurface/groundwater according to specific technologies. Even though it has no unique definition, it is often obtained as a combination of the subsurface hydrogeological/thermal properties and the thermal regime and, by means of GIS techniques it can be spatialized to obtain geothermal potential maps.

The subsurface thermal properties vary in space according to the geological setting, while the hydrogeological and thermal regimes can vary both in space and time according to the fluid and heat budgets of the aquifers. However, despite few studies consider the variability of the geothermal potential in time due to possible variations of the hydrogeological and thermal regimes, it is essential to evaluate the efficiency of geothermal systems in a changing environment such as subsurface urban heat islands. The hydrogeological/thermal regimes are not stationary, especially beneath big cities where land and subsurface uses control the elevation of the water table and the shallow subsurface thermal regime. Moreover, the heating and cooling demand of buildings may vary due to climate change effects such as global warming and atmosphere urban heat island.

The potential to exchange heat with the subsurface in the Milan metropolitan area was estimated from hydrogeological and thermal regimes simulated by a fluid-flow/heat-transport city-scale numerical model, calibrated on the current state. Several scenarios were generated changing the boundary conditions according to projected changes of (I) the air temperature (based on RCP 2.6, 4.5 and 8.5 scenarios), (II) the groundwater head, (III) the land use/city size and (IV) the geothermal uses (based on the increment of installations and changes of the thermal demand), to estimate the changes and the seasonal variability of the subsurface temperature at different depths in different zones of the city. Finally, the future variations of the thermal potential were estimated for heating and cooling seasons combining the scenarios-projected subsurface temperatures with the hydrogeological and thermal properties, also considering the variation of heating and cooling thermal loads.

How to cite: Previati, A., Silvestri, V., Frattini, P., and Crosta, G. B.: Evaluating the sustainability of low enthalpy geothermal applications in a subsurface heat island, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12456, https://doi.org/10.5194/egusphere-egu22-12456, 2022.

EGU22-12564 | Presentations | ERE5.4

Thermal Impact of High Temperature Aquifer Thermal Energy Storage on Overlying Layers 

Stefan Heldt and Sebastian Bauer

High temperature Aquifer Thermal Energy Storage (HT-ATES) is one option to compensate for the seasonal mismatch between supply and demand in a renewable dominated heating sector. The thermal impacts to be expected by a planned HT-ATES plant can be predicted by numerical modelling, which is necessary for the development of monitoring concepts, legal authorization and economical assessments. One aspect of numerical pre-investigations, which was mostly disregarded by previous studies, is the assessment of thermal impacts in layers above the storage formation, which are heated conductively by the warm well. Furthermore, a quantification of the related heat losses and the implications on storage efficiency need to be considered.

The thermohydraulic processes induced by the HT-ATES are numerically simulated by a radially symmetric model neglecting ambient groundwater flow. The model includes the discretised warm ATES well, which reaches to a depth of ≈250 m and the surrounding geological layers. The geology and the operational scheme are based on a typical setting representative for northern Germany. The simplified operational scheme consists of half a year injection and half a year extraction, repeated for 50 years, with an injection temperature of 85 °C, varying return flow temperatures and an initial subsurface temperature of 13 °C. The thermal properties of the well casing are varied in a sensitivity study to estimate the influence of different material choices.

The model results show, that a temperature increase of 5 °C propagates 7 m radially in cohesive layers around the well in the first year of operation. After 50 years, temperature increases of 5 °C or more are found within a distance of about 40 m, 30 °C within about 13 m and 50 °C within about 2 m. Density-driven buoyancy flow is observed in cohesionless layers, leading to heat accumulation near the top of these layers. The heat consequently propagates significantly further there than in the cohesive formations, e.g. a temperature increase of 5 °C propagates maximally 121 m from the well in 50 years. The conductive heat loss to the overlaying formations through the well casing is 2 % of the injected heat. The such derived estimation of thermal impacts in overlaying formations is conservative, since ambient groundwater flow is neglected, which would result in lower temperatures due to advective heat transport away from the well. The heat loss, however, would be larger with groundwater flow, since this would reduce temperatures around the well and thus increase the temperature gradients and the conductive heat transport. Material choices of the well material may increase or decrease the heat losses and thus the thermal impacts.

How to cite: Heldt, S. and Bauer, S.: Thermal Impact of High Temperature Aquifer Thermal Energy Storage on Overlying Layers, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12564, https://doi.org/10.5194/egusphere-egu22-12564, 2022.

EGU22-12929 | Presentations | ERE5.4

Exploration of high temperature aquifer thermal energy storage in Delft (The Netherlands) 

Philip Vardon, Martin Bloemendal, Stijn Beernink, Niels Hartog, Auke Barnhoorn, Tobias Schmiedel, Hemmo Abels, and Susanne Laumann

In conjunction with a deep geothermal project which is being implemented on the TU Delft campus in the Netherlands, a high temperature aquifer thermal energy storage (HT-ATES) is being considered. An initial feasibility study suggests that this could significantly reduce CO2 emissions from heating and be financially beneficial. As part of the research associated with the implementation of the geothermal well, a 500 m deep monitoring and exploration well has been drilled to further investigate two target layers for HT-ATES and to allow for scientific records before, during and after the production phase of the geothermal project. With this drilling, the potential for HT-ATES of multiple layers is investigated by means of innovative exploration methods. An extensive set of downhole geophysical logging tools was used, many cores from both consolidated and unconsolidated layers were taken and a pumping test was carried out in the deepest layer. This work presents an initial overview of the work carried out and provides insights into the initial results of this innovative exploration drilling. The Delft geothermal project is therefore a great example of a beneficial interplay of economic and societal interest (i.e. city heating, CO2-neutral campus) and scientific innovation.

How to cite: Vardon, P., Bloemendal, M., Beernink, S., Hartog, N., Barnhoorn, A., Schmiedel, T., Abels, H., and Laumann, S.: Exploration of high temperature aquifer thermal energy storage in Delft (The Netherlands), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12929, https://doi.org/10.5194/egusphere-egu22-12929, 2022.

The fluid's pore pressure represents the main geomechanics parameter to consider while planning for drilling operations and during production. Actually, a good understanding of overpressure origins leads to better characterize of the pore pressure, which materialized by the suggestion of several models to predict pore pressure. Therefore, the successful technical achievement of a drilling program is judged by the sustainable integrity of the well i.e. sealing effectiveness between different reservoirs. As a result, this should guarantee long-term water resources protection, rational production, and sustainable development.

                The studied cases (CI-11 and OKN-32 wells) reflect the direct effect of the integrity failure of the cased hole, leading to the groundwater and ecological safety of the major transboundary aquifers system in North Africa. This aquifer is known as the North-Western Sahara Aquifer System (NWSAS), which is shared between Tunisia, Algeria, and Libya. It's hosting huge reserves of non-renewable water, in an arid climate region. The assessment of the wells Jemna CI-11 in Tunisia and the Berkaoui OKN-32 in Algeria have concluded the integrity loss of the wellbore. These issues led to CI mass-water flowing behind the casing from the CI to the CT aquifers which characterize an internal blowout where water flows from the over-pressurized CI groundwater to the shallower CT groundwater. First, the case of the Haoud Berkaoui in 1984, (OKN-32 well) has induced a CI waters flow behind the casing causing the CT water resource contamination, which is ended with a surface crater collapse over a diameter of 320 m. Second, a quite similar accident happened in Jemna in 2015, (CI-11 well) where evidence of water flowing from CI to CT through a leaked-off casing has been discovered. Jemna CI-11, Berkaoui OKN-32, and probably many other ongoing similar accidents, could be classified as regional ecological disasters by massive water resources losses and contamination. The actual situation is far from being under control and the water contamination risk remains at a very high level.

                Finally, due to unsuitable drilling programs, drilling operation problems, and/or production casing corrosion, we suspect that dozens of oil and water wells may be involved in well integrity failure affecting the NWSAS groundwater resource. And since, we cannot diagnose easily internal blowout unless widespread contamination happened, we strongly recommend (1) a regional investigation and risk assessment plan which might offer better tools to predict and detect earlier well-bore isolation issues and (2) special attention to the cement bond settlement, evaluation, and preventive logging for existing wells to ensure effective sealing between the vulnerable water tables. Besides, in the CI-11 well accident, the recovery program was not efficient and there was no clear action plan. This increases the risk of action failure or time waste to regain control of the well. Consequently, we suggest preparing a clear and efficient action plan for such accidents in order to reduce their ecological consequences. This needs a further technical detailed study of drilling operations and establishment of the suitable equipment/action plan to handle blowout and annular production accidents.

How to cite: Khalfi, C., Ouhaibi, C., Ahmadi, R., and Dassi, L.: Role of the pore pressure profile on the protection of wellbore integrity and the groundwater: Case studies of well integrity issues of CI-11, in southern Tunisia, and OKN-32 in Algeria., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-278, https://doi.org/10.5194/egusphere-egu22-278, 2022.

EGU22-2425 | Presentations | ERE5.5

Effect of loading rate on mechanical behavior and deformation mechanisms in clay-bearing sandstones 

Takahiro Shinohara, Christopher Spiers, and Suzanne Hangx

Fluid extraction from subsurface reservoir sandstones frequently results in surface subsidence and induced seismicity, as observed in the Groningen Gas field (Netherlands). The cause lies in reservoir compaction driven by pressure depletion and the associated increase in effective overburden stress. Compaction in sandstones often includes elastic and significant inelastic components. The inelastic part is at least partly due to rate- or time-dependent processes, such as intergranular sliding or stress corrosion cracking. However, few mechanism-based rate/time-dependent compaction laws exist, despite the need to evaluate the impact of reservoir exploitation on field time scales (1-100 years). To help bridge this gap, we systematically investigated the effect of loading strain rate in the range from 10-3 to 10-9 s-1 in a series of triaxial compression experiments performed on water-saturated Bleurswiller sandstone samples with porosities of 21.07±0.15 % and composed of 66 % quartz, 28 % feldspar and 4 % clay. This material was chosen because of similarity to the Groningen sandstone but greater uniformity. We explored conditions of confining pressure (39 MPa), pore pressure (10 MPa) and temperature (100 °C) corresponding to in-situ values for Groningen. Axial strains up to 3 % were imposed. Our results showed combined elastic plus strain hardening (inelastic) loading behavior, up to a peak stress reached at 0.8-1.0 % strain, followed by strain softening towards a steady residual stress attained at 1.5-2.0 % strain. A systematic lowering of stress-strain curve levels was observed with decreasing strain rate, such that peak and residual stresses decreased respectively from 88 and 74 MPa at 10-3 s-1 to 70 and 61 at 10-9 s-1. No effect of loading rate is observed at differential stresses below ~ 50% of peak stress. At higher differential stresses up to peak, net sample stiffness (stress-strain curve slope) decreases with decreasing strain rate. Using the curve obtained at 10-3 s-1 as a reference, we determined the excess strains measured at rates of 10-4 to 10-9 s-1 at fixed differential stresses up to the peak. By extrapolating this empirical relation to field strain rates associated with gas production in Groningen (i.e. 10-12 s-1), it is estimated that ~30 % more compaction strain is developed under field conditions, at current differential stresses in the field (i.e. ~ 60 % peak stress), than in laboratory experiments at rates of 10-3 to 10-5 s-1. Additional experiments at varying temperature and confining pressure show sensitivities that suggest that the observed effect of strain rate is likely associated with a combination of time-dependent grain failure by stress corrosion and intergranular sliding. Work is in progress to assess the effect of varying mineralogy by conducting similar experiments on clay-free, quartz-rich Bentheimer sandstone. Our results show that time-dependent inelastic deformation plays an important role in estimating reservoir deformation and associated change in stress associated with fluid production from sandstone reservoirs, like the Groningen reservoir. Such effects could lead to underestimation of surface subsidence and induced seismicity, if not adequately accounted for. The present experiments thus provide important data for testing current models for rate-dependent reservoir compaction.   

How to cite: Shinohara, T., Spiers, C., and Hangx, S.: Effect of loading rate on mechanical behavior and deformation mechanisms in clay-bearing sandstones, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2425, https://doi.org/10.5194/egusphere-egu22-2425, 2022.

Predicting the growth of fluid-driven fractures in geological systems is essential for the sustainable and efficient engineering of oil and gas reservoirs. The linear elastic hydraulic fracture mechanics (LHFM), which combines the linear elastic fracture mechanics and lubrication theory, has described well the fracture growth in brittle materials. However, the quasi-brittle nature of reservoir rocks may result in deviations of the fracture propagation from LHFM predictions. We have experimentally investigated the propagation of hydraulic fractures in quasi-brittle rocks under true triaxial stress conditions. We have performed HF injections in 250x250x250 millimeters Zimbabwe gabbro samples in the toughness-dominated growth regime. We use active acoustic monitoring to measure the evolution of fracture radius from diffracted waves and estimate fracture width from transmitted waves (Liu et al., 2020). Assuming a radial and uniformly pressurized crack, we find that LHFM predictions overestimate fracture radius inverted from diffracted acoustic waves but underestimate the measured injection fluid pressure. Using the same radial uniformly pressurized linear elastic fracture model, we also estimate an apparent toughness from the measured fracture radius and pressure. This estimated apparent toughness is not constant and tends to increase with fracture extent in some cases up to a constant value. We also obtain another estimate of fracture toughness from fracture width back-calculated from transmitted waves for a few snapshots of the fracture evolution. These two estimates of the fracture apparent toughness are mostly consistent, although higher values are obtained when the estimation is based on pressure measurement. We also observe an attenuation of transmitted waves across the fracture plane prior to the arrival of the fracture front obtained from diffracted waves. This allows us to estimate a process zone size in the range of two to six centimeters (depending on experiments). In addition, post-test micro-CT images reveal the presence of a microscale fracture path with some 3D crack branches and bridges. The thickness of such a crack band is a few millimeters on par with both grain size and the roughness of the fracture surface measured after the test. These experiments document an increase of the process zone size at the early stage, which stabilizes afterward in some of the experiments. It is important to note that complete separation of scales between fracture radius, process zone, and sample size is hardly achieved in these experiments. A non-negligible influence of the process zone may thus explain the reported deviation from LHFM predictions in gabbro. No effect of the minimum confining stress was visible in the range investigated here (0 to 10 MPa). The applied minimum stresses were always smaller than the reported peak tensile strength for this rock, a domain where the effect of the quasi-brittle nature of rocks is not anticipated to be significant based on recent theoretical results (Garagash, 2019; Liu & Lecampion 2021).

How to cite: Liu, D. and Lecampion, B.: Does the linear hydraulic fracture mechanics predict well the fracture growth in quasi-brittle rocks under laboratory conditions?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3445, https://doi.org/10.5194/egusphere-egu22-3445, 2022.

The increasing emission of greenhouse gases and increasing demand for energy supply are reasons to investigate geothermal energy systems where scCO2 is the working fluid. However, the complex dissolution and reaction of minerals during the heat production processes affect the performance of geothermal reservoirs. Thus, a comprehensive numerical model that includes the Thermal-Hydraulic-Chemical (THC) coupled physical-chemical processes was implemented in the open-source simulator DuMuX, to model the phase displacement, chemical dissolution, heat transport, and mineral reactions. The aim is to investigate the influence of these parameters on the overall geothermal reservoir performance. More precisely, this study investigates the effects of salt precipitation, mineral reactions, injection rate, injection temperature, and geothermal reservoir size on heat production rate and scCO2 sequestration. The simulation results show that the scCO2- calcite reaction decreases the reservoir heat production rate but increase the sequestration of scCO2. Moreover, its effects are proportional to the scCO2 injection rate but inversely proportional to the geothermal reservoir size. On the other hand, the dissolution of scCO2 in brine has the same influence as the reaction between scCO2 and calcite, benefiting the CO2 sequestration but minimizing the heat production rate of the geothermal reservoirs. Furthermore, the sensitivity analysis presents that the influence of chemical dissolution and mineral reactions are only significant when the injection rate is large and the reservoir size is small.

How to cite: Zhou, D., Tatomir, A., and Sauter, M.: Numerical investigation of the effects of chemical dissolution and mineral reaction on reservoir performances in CO2-plume geothermal systems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6622, https://doi.org/10.5194/egusphere-egu22-6622, 2022.

EGU22-7156 | Presentations | ERE5.5

Hydro-mechano-chemical coupling in rock failure 

Anne Pluymakers, Aukje Veltmeijer, Milad Naderloo, Jon-Danilo Kortram, and Auke Barnhoorn

Understanding rock failure is key for the safe and efficient development of the subsurface. Gas storage (CO2, H2 or CH4), production of geothermal energy and the traditional extraction of hydrocarbons means fluid injection or extraction. These processes change the local stress state, but also local temperature or chemistry. Such use of the subsurface is about either keeping fluid where it is (storage) or making sure fluids come out with a sufficient but still safe rate. Since fault rocks are in many cases important fluid transport pathways, this needs a careful and complete understanding of how rocks fail. Therefore, a thorough understanding of the stages of deformation leading to failure is key, as well as any potential differences for different rock types and failure modes. We performed uniaxial compressive and triaxial experiments on limestone and sandstone to investigate the hydro-mechano-chemical coupling in rock failure, using active and passive acoustics to monitor the failure behaviour. All experiments are done at room temperature.

Using active acoustics for first arrival times is an established technique. We use here the more novel coda-wave interferometry technique to track deformation in triaxial tests at different confining pressures in sandstones and limestone, which deform respectively in a fully brittle or a semi-ductile manner. This shows that the first signs of failure can be picked up before the yield point, i.e. before the time it is picked up by any of the traditional bulk stress-strain signals used in experimental rock deformation. In uniaxial compressive experiments on the same brittle sandstone samples we show that the loading pattern can affect the final strength but also the maximum acoustic emission amplitude. Cyclic loading tends to systematically reduce the magnitude of the largest induced seismic event, whilst simultaneously also promoting more complex fracture patterns and disintegration. This implies that the risk of induced seismicity can be mitigated by changing the loading pattern in subsurface operations. Finally, we show that for reactive rocks under the right pressure and temperature conditions, changing the chemistry can have an effect on rock strength, where the effects depend on the internal rock structure. This research increases the understanding of rock failure and show the potential of monitoring for a safe and efficient development of the subsurface.

How to cite: Pluymakers, A., Veltmeijer, A., Naderloo, M., Kortram, J.-D., and Barnhoorn, A.: Hydro-mechano-chemical coupling in rock failure, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7156, https://doi.org/10.5194/egusphere-egu22-7156, 2022.

Wormholes are an effective fluid conduit that dominate the flow path in karst aquifers and are artificially induced in geo-energy applications through acid injection. As acidic fluids infiltrate geologic formations, they react with the minerals in the formation. The reaction localizes and forms a dendritic dissolution pattern under certain conditions, known as the reaction infiltration instability. This instability is instigated by material heterogeneities in most computational models. However, studies have demonstrated that injection of water into a homogeneous plaster can initiate and grow wormholes. In this study, we show that material heterogeneities suppress the wormhole growth in carbonate rocks compared with a homogeneous counterpart. Wormholes were numerically simulated through injection of a strong acid (hydrochloric acid) under both homogeneous and heterogeneous permeability fields using a phase-field approach. The phase-field variable represents calcite dissolution in a diffused manner and is coupled with a reactive flow model assuming convective and diffusive acid transport in the liquid phase and significantly high surface reaction rate, which emulate typical high-rate matrix acidizing treatments in carbonate reservoirs. Heterogeneous permeability fields localize the flow in high-permeability domains and enhance the splitting and branching of wormholes. The length of the dominant wormholes can be suppressed as an increasing amount of acid infiltrates into the branched wormholes. Our findings indicate that material heterogeneities should not be treated as a trigger for wormholes in the numerical simulation but as one of the parameters to control their nucleation and growth. 

How to cite: Furui, K. and Yoshioka, K.: A Numerical Study of Wormhole Formation and Growth in Homogeneous and Heterogeneous Carbonate Rocks, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8971, https://doi.org/10.5194/egusphere-egu22-8971, 2022.

EGU22-11543 | Presentations | ERE5.5

2D & 3D numerical modeling of fluid-driven frictional crack growth for geothermal hydraulic stimulation  

Brice Lecampion, Alexis Sáez, and Regina Fakhretdinova

Hydraulic stimulation of deep geothermal reservoirs is necessary in order to establish economical flow rates between the injector and producer wells. Previous field experience in deep crystalline reservoirs have highlighted the importance to stimulate the well by zones in order to create several fractures along the well instead of carrying out a single large stimulation which typically results in the reactivation of only a few fractures along the open-hole section – thus resulting in poor reservoir coverage and low flow transmissivity. Localized hydraulic stimulation can be performed via packer-systems, and although different in their details, share similarities with stimulation operations performed in unconventional oil and gas reservoirs. The main differences are that i) propping agents are not typically used in crystalline geothermal reservoirs, ii) the injection pressure often remains lower than the minimum in-situ stress and iii) the long-term increase of permeability relies on the self-propping effect associated with the shear dilatant behaviour of pre-existing fractures. The type of fractures propagated during hydraulic stimulation thus exhibit both shear and tensile modes of deformation (different than the purely tensile hydraulic fractures).

Physics-based models are necessary in order to design the injection sequence and are typically used in conjunction with uncertainty analysis. We report our developments of  two and three-dimensional numerical models for the hydraulic stimulation of pre-existing fractures accounting for both shear and opening modes of deformation. The fracture behavior is modelled via a non-associated Mohr-Coulomb frictional elasto-plastic law with possible weakening/hardening of friction and dilatancy with slip, while the host rock is assumed linearly elastic. The fluid flow behaviour of the fracture accounts for opening and the associated permeability / storativity changes (with the possibility to use different type of permeability law). We solve in a fully coupled manner the resulting non-linear moving boundary hydromechanical problem.

We present several verification tests for the growth of a frictional shear crack growth in the plane of a pre-existing frature under the injection of fluid at constant rate in both 2D and 3D. Especially, we compare our numerical results with recent analytical solutions for the case of constant friction and constant hydraulic properties of the pre-existing fracture. We then discuss several examples combining shear dilatancy and its effect on flow properties as well as the possible tensile opening of the pre-existing stimulated fracture. Accuracy, robustness and numerical performance – critical for the use of the solver for engineering design - will be discussed as well as future improvements.

This work is sponsored by Geo-Energie Suisse A.G. and the Swiss Federal Office of Energy.

How to cite: Lecampion, B., Sáez, A., and Fakhretdinova, R.: 2D & 3D numerical modeling of fluid-driven frictional crack growth for geothermal hydraulic stimulation , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11543, https://doi.org/10.5194/egusphere-egu22-11543, 2022.

EGU22-11737 | Presentations | ERE5.5

Influence of chemo-mechanical processes and microstructural geometry on the mechanical behavior of geomaterials 

Hadrien Rattez, Alexandre Guével, Martin Lesueur, and Manolis Veveakis

The mechanical behavior of geomaterials depends primarily on their microstructure and in particular the geometry of their pores. This microstructure and its evolution in time due to deformation or chemical transformations also strongly affects the thermo-hydro-mechanical-chemical (THMC) processes in these porous materials. In the last decades, the development of micro-computed tomography has allowed to obtain accurate images of the rock-microstructures and how they evolve subjected to various factors. Many studies have used these 3D geometries of the porous space to characterize primary properties that depend on the microstructure, such as porosity, permeability or elastic moduli, by numerically solving field equations on µCT scan images of rock. For most projects of energy production or waste storage in geological media though, rocks eventually reach their limit of elasticity and the complementary plastic properties are needed to describe the full mechanical behaviour. In this contribution, we will show how we can assess the mechanical behavior of geomaterials in the long-term by solving nonlinear equations directly on realistic microstructures. First, we will discuss the necessary morphometric invariants that can be used in an upscaled constitutive law and show how we can predict the yield surface and its evolution with the chemical alteration of the rock from µCT scan images. Then, a phase field model that allows to simulate interface evolution is applied to investigate pressure solution creep at the grain scale and how it is influenced by microstructural geometry and catalyzing/inhibiting effects like temperature or clay content.

How to cite: Rattez, H., Guével, A., Lesueur, M., and Veveakis, M.: Influence of chemo-mechanical processes and microstructural geometry on the mechanical behavior of geomaterials, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11737, https://doi.org/10.5194/egusphere-egu22-11737, 2022.

EGU22-259 | Presentations | ERE5.6

Hydrogeochemical impact assessment of pumped hydro power storage in open-pit lignite mines 

Tobias Schnepper, Michael Kühn, and Thomas Kempka

As recent developments regarding the increasing demand of renewable energy sources in the European energy sector demonstrate, the need for large-scale energy storage technologies intensifies. Since the availability of wind and photovoltaic energy are undergoing high fluctuations, excess energy has to be stored to be available at times of high energy demand. Implementation of pumped hydro power storage (PHS) plants in abandoned underground reservoirs are intensively studied as potential storage solution (e.g. Pickard, 2012), whereby open-pit lignite mines are also expected to contribute to this issue (Thema and Thema, 2019), but are hardly investigated, yet. PHS follows the concept of pumping and releasing water between two reservoirs located at different elevations.

The success of energy storage by PHS in abandoned mines highly depends on the geo- and hydrochemical processes in the reservoirs and the surrounding porous media (Pujades et al., 2018). Oxidation of sulphur bearing minerals, especially of pyrite, might trigger the generation of Acid Mine Drainage (AMD; Akcil and Koldas, 2006), which can impact groundwater chemistry as well as slope stability, and further induce corrosion at critical technical infrastructure (Pujades et al., 2018).

In the scope of the present study, we have investigated the major chemical reaction paths by numerical modelling to conceptualise comprehensive reactive transport simulations for environmental risk assessments. For that purpose, we considered available research findings from studies on the Lusatian and Rhenish lignite mining areas, and applied these to other European mining sites. Calcite buffering, mineral dissolution-precipitation balances, heavy metal contamination as well as mixing processes between the potential reservoirs and groundwater have been taken into account. In summary, geochemical impacts potentially occurring with PHS operation under hydrochemical boundary conditions representative for European open-pit lignite mines were investigated and quantified.

 

References

Akcil, A., and Koldas, S: Acid Mine Drainage (AMD): causes, treatment and case studies, Improving Environmental, Economic and Ethical Performance in the Mining Industry - Part 2, Life cycle and process analysis and technical issues, J. Clean. Prod., 14, 1139-1145, 2006.

Pickard, W. F.: The History, Present State, and Future Prospects of Underground Pumped Hydro for Massive Energy Storage, Proc. IEEE, 100, 473–483, 2012.

Pujades, E., Jurado, A., Orban, P., and Dassargues, A.: Hydrochemical changes induced by underground pumped storage hydropower: Influence of aquifer parameters in coal mine environments, Advances in Geosciences, 45, 45-49, 2018.

Thema, J., and Thema, M.: Pumpspeicherkraftwerke in stillgelegten Tagebauen am Beispiel Hambach-Garzweiler-Inden, Wuppertal Paper, 2nd ed., 194, 2019.

How to cite: Schnepper, T., Kühn, M., and Kempka, T.: Hydrogeochemical impact assessment of pumped hydro power storage in open-pit lignite mines, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-259, https://doi.org/10.5194/egusphere-egu22-259, 2022.

EGU22-275 | Presentations | ERE5.6

Assessment of brittleness and hydrocarbon potential of deep Permian shales in Krishna Godavari Basin, India 

Shubhangi Kala, Javaregowda Devaraju, and Mohammed Abdul Rasheed

The Permian-aged Kommugudem Formation has been identified as a potential candidate in the prospective Krishna Godavari basin for future shale gas exploration. Brittleness and hydrocarbon potential based on geochemical and mineralogical evidence is characterized from the conventional cores in the study area. According to petrographic, SEM, and XRD analysis, the shale is primarily composed of quartz, clays (kaolinite, chlorite and illite), siderite, muscovite, pyrite, and feldspar. The Mineralogical Brittleness Index (MBI) ranges from 60 to 80 percent, suggesting that the Kommugudem shale is a likely good fracking candidate. Natural microfractures in Formation can increase hydraulic fracturing performance by acting as hydrocarbon migration conduits and hydrocarbon storage sites. The low chemical maturity index of Kommugudem samples indicates an abundance of detrital minerals formed near provenance without significant recycling. Due to the insoluble nature and diagenetic immobility, the Nb and Th enrichment identified in Kommugudem samples further supports a possible detrital source of the quartz. Clay-sized microquartz cement seen in a few samples may bind silt-sized detrital quartz and promote brittleness. The development of recrystallized microquartz cement is also caused by the illitization of smectite clay, as evidenced by XRD data revealing the presence of illite. The mineralogical brittleness index does not take into account the mineral texture or the kind of clay mineral related. As a result, such computations must be used with caution. Kommugudem Formation is composed of Type III kerogen in admixture with Types II-III, with high TOC and Tmax predicting substantial organic matter concentration in the dry and wet gas windows. RockEval and FTIR examinations revealed that two wells had good hydrocarbon generation potential for oil and gas sources, while the other wells had comparatively lesser hydrocarbon potential. Brittleness appears to be substantially reliant on lithological heterogeneity, according to the proposed assessment. The examined area possesses lithological variability, and the Kommugudem shale shows compositional similarities to brittle sections of the Barnett and Marcellus shale plays. According to the integrated characterization, shale has high organic content and is brittle in nature. This comprehension is critical if the shale is to be considered for further investigation.

How to cite: Kala, S., Devaraju, J., and Rasheed, M. A.: Assessment of brittleness and hydrocarbon potential of deep Permian shales in Krishna Godavari Basin, India, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-275, https://doi.org/10.5194/egusphere-egu22-275, 2022.

EGU22-427 | Presentations | ERE5.6

Geochemical evolution and reaction mechanisms controlling groundwater chemistry in the Pra Basin (Ghana) 

Evans Manu, Marco De Lucia, Anja Maria Schleicher, Thomas Kempka, and Michael Kühn

As the demand for water supply increases with population growth, the quality of ground and surface water resources is deteriorating rapidly in many regions worldwide, particularly in Ghana. This situation has put supply systems under severe pressure as many of the available water resources are polluted by anthropogenic activities such as mining, agriculture, domestic and industrial sewage. Ghana's water quality problems are not different from current global challenges, as many surface waters and some aquifers have been polluted by mining activities and to some extent also by agriculture and industrial seepage. The Pra Basin is one of the most affected basins in Ghana with a total area of around 2,300 km2 and a population of over five million people. The economic history of the basin is unparalleled as it is home to the country's major mineral deposits, including gold, bauxite, manganese, and diamonds. Recent studies have shown significant amounts of water pollutants including mercury (Hg), arsenic (As), lead (Pb), iron (Fe), manganese (Mn), cadmium (Cd), selenium (Se) and nitrate (NO3). The underlying geology of the Pra Basin consists mainly of metasediments and granitoids. The occurrence of groundwater is controlled by the development of secondary porosities through fractures, joints, and faults. This study provides insights into the evolution and hydrogeochemical processes that control the groundwater quality in the Pra Basin. The methodology applied here includes field sample collection, statistical analysis of hydrochemical data, petrographic and mineralogical analysis of rock outcrops and geochemical modelling. Groundwater samples were taken from shallow (mainly hand-dug wells with depths <10 m) and deep aquifers (mainly boreholes with depths >30 m) throughout the basin. Samples were analysed for major ions, and trace metals using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Ion Chromatography (IC), and a Picarro L-2140i Ringdown Spectrometer. Multivariate statistical analyses, inverse and forward geochemical modelling were applied to the hydrochemical data of around 100 water samples. The mineral phases used as model input were obtained from X-ray Diffraction (XRD) measurements of rock outcrops from the study area and mainly include chlorite, albite, muscovite, biotite, and calcite. The analysis of the results shows that the geochemistry of the groundwater resources in the Pra Basin is mainly controlled by water-rock-interaction. Within the given uncertainty limits, the dissolution of carbonates and weathering of silicates are the drivers for the chemical development of the groundwater in the basin. The presented findings will support the development of sustainable water resources management strategies and contribute to mitigating future contamination.

How to cite: Manu, E., De Lucia, M., Schleicher, A. M., Kempka, T., and Kühn, M.: Geochemical evolution and reaction mechanisms controlling groundwater chemistry in the Pra Basin (Ghana), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-427, https://doi.org/10.5194/egusphere-egu22-427, 2022.

EGU22-2436 | Presentations | ERE5.6

Making sense of Isogeometric Analysis for geothermal applications: Parametric geomodelling (NURBS) for fast model construction, simulation and adaptation 

Daniel Escallon, Denise Degen, s.Mohammad Moulaeifard, and Florian Wellmann

Geological modelling is an essential aspect of a wide variety of geophysical and geological investigations related to geo-energy exploration and monitoring. A commonly-applied procedure is to use 3D geological models (often referred to as static models) to characterise the spatial distribution of material properties, which are then used in subsequent process simulations. The physical processes are described with partial differential equations that can be solved using different numerical methods by creating a discretisation in the space of the geometric object (i.e., a mesh). However, mesh generation can be a time-consuming step that generally only allows an approximation of the true geometric model. Several methods have been proposed to resolve these issues. We investigate here the use of the isogeometric analysis (IGA) technique, which exploits the finite element method (FEM) to numerically solve differential equations without the need of creating a mesh. Instead, it uses computer-aided design (CAD) tools, specifically Non-Uniform Rational B-splines (NURBS), to accurately represent any form of conic sections geometry. 

This presentation shows the link between NURBS representing geological interfaces and subsequent geothermal process simulations. The link is implemented in a user-friendly Python package (https://github.com/danielsk78/pygeoiga) with a simple but clear interface. It differs from other implementations by dealing with multipatch structures and focusing on geological modelling with multiple subdomains. A series of numerical examples are presented to show the use of the technique for solving the two-dimensional heat conduction problem. Results are contrasted to the results of a traditional FEM approach. The comparison shows that IGA requires fewer degrees of freedom (DoF) for convergence of the solution. Further, IGA provides a way to ease the workflow from the geological modelling to the results of process simulations, enabling tighter integration between modelling and simulation. Lastly, we describe shortly how the IGA concept can be implemented on top of existing standard FEM libraries.

How to cite: Escallon, D., Degen, D., Moulaeifard, s. M., and Wellmann, F.: Making sense of Isogeometric Analysis for geothermal applications: Parametric geomodelling (NURBS) for fast model construction, simulation and adaptation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2436, https://doi.org/10.5194/egusphere-egu22-2436, 2022.

Intrusion of deep saline waters into freshwater aquifers does not only endanger the regional drinking water supply, but also rivers and stagnant waters as well as their fauna and flora are threatened by salinisation. The upconing of highly mineralised saline waters in large parts of the North German Basin is favoured by the presence of Elsterian glacial erosion windows in the Lower Oligocene Rupelian Clay, the most important confining unit in this region. Lower precipitation rates and decreasing groundwater levels as a consequence of global climate change, but also anthropogenic interventions, such as increasing extraction rates or the utilisation of the geological subsurface, decrease the pressure potential in the freshwater column and may possibly accelerate primarily geogenic salinisation processes in the coming years [1, 2].

In this study, density-driven flow and transport modelling [3] was performed to investigate the upconing mechanisms of deep saline waters across Quaternary window sediments in the Rupelian. First, the main variables influencing the dynamics of the freshwater/saltwater boundary were determined using generic 2D models. For a site-specific analysis along a 20 km long transect in the Federal State of Brandenburg, Germany, the geological/hydrogeological conditions were then integrated into the 2D models, starting from the Mesozoic strata in the bedrock of the Rupelian sequence as the model basis, up to the Quaternary unconsolidated rock series at the ground surface. At site, the Rupelian Clay has been partially eroded and salinisation in the hanging freshwater column is already detectable.

Simulation results show that the interactions between influencing variables, e.g., the regional groundwater flow and seasonal dynamics of the groundwater recharge rate, as well as anthropogenic interventions such as extraction rates of drinking water wells, have a significant influence on the groundwater pressure potential in the freshwater aquifer and associated saltwater upconing. The temporal development of saltwater intrusion shows up quite differently, depending on boundary conditions and also strongly depends on flow rates and cross-section of the Rupelian windows. Depending on the topography, the fluid density gradient and its effect on flow conditions and pressure potential, creates a dynamic between deep saline and shallow freshwater aquifers, with ascending flow occurring locally in larger discharge areas. The next steps will comprise a 3D extension of the model as well as consideration of chemical rock-water interactions.

Literature

[1] 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.

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

[3] 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.

How to cite: Chabab, E., Kühn, M., and Kempka, T.: Upconing of deep saline waters via Quaternary erosion windows considering varying hydrogeological boundary conditions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2734, https://doi.org/10.5194/egusphere-egu22-2734, 2022.

EGU22-4676 | Presentations | ERE5.6

Hysteresis in permeability evolution of a virtual sandstone simulated by mineral precipitation and dissolution 

Maria Wetzel, Thomas Kempka, and Michael Kühn

Mineral dissolution and precipitation can substantially affect rock permeability, which is a critical parameter for a broad range of subsurface applications, including geothermal energy production, geological storage, petroleum engineering and subsurface contaminant transport. In order to quantify trends in rock properties, virtual experiments on digital pore-scale samples represent a powerful and flexible approach to fundamentally understand the impact of microstructural alterations on evolving permeability.

In the present study, cycles of secondary mineral precipitation and subsequent dissolution are simulated on a synthetic sandstone sample [1]. For that purpose, the flow velocity magnitude is used as a proxy for solvent flux to depict characteristic transport-limited alteration patterns, whereas the inner surface area is used to constrain reaction-limited processes [2,3]. The corresponding hydraulic property evolutions are computed for combinations of reaction- and transport-limited precipitation and subsequent dissolution. Hysteresis can be observed for most of the geochemical reaction pathways, where the permeability trend for the dissolution differs significantly from that of precipitation. Transport-limited mineral dissolution initially shows a considerably higher permeability increase due to the widening of existing main flow paths, whereas the subsequent dissolution of new flow paths leads to a comparably lower permeability increase. The determined discontinuity in permeability evolution clearly demonstrates that microstructural changes as the opening or closure of flow paths might not be simply an inversion of the geochemical processes on an identical reaction pathway. The simulated porosity-permeability relationships are further discussed in the context of property trends observed in nature. Current analytical approaches are not able to reflect the evolution for these dynamic processes, since they describe permeability as a simple function of porosity. Hence, pore-scale modelling approaches are required to describe permeability trends and further develop understanding of reservoir behaviour, since hydraulic property changes resulting from mineral precipitation and dissolution clearly depend on geochemical processes and their history.

[1] Wetzel M., Kempka T., Kühn M. (2021): Diagenetic trends of synthetic reservoir sandstone properties assessed by digital rock physics. Minerals, 11, 2, 151. DOI: 10.3390/min11020151

[2] Wetzel M., Kempka T., Kühn M. (2020): Digital rock physics approach to simulate hydraulic effects of anhydrite cement in Bentheim sandstone. Advances in Geosciences, 54, 33-39. DOI: 10.5194/adgeo-54-33-2020

[3] Wetzel M., Kempka T., Kühn M. (2020): Hydraulic and mechanical impacts of pore space alterations within a sandstone quantified by a flow velocity-dependent precipitation approach. Materials, 13, 4, 3100. DOI: 10.3390/ma13143100

How to cite: Wetzel, M., Kempka, T., and Kühn, M.: Hysteresis in permeability evolution of a virtual sandstone simulated by mineral precipitation and dissolution, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4676, https://doi.org/10.5194/egusphere-egu22-4676, 2022.

EGU22-4925 | Presentations | ERE5.6

Fast digital rock upscaling: from Stokes equation to Darcy equation 

Qinzhuo Liao, Gensheng Li, Zhongwei Huang, Mao Sheng, Jun Li, and Dongxiao Zhang

Permeability is a key parameter for characterizing fluid flow in digital rocks. It depends on pore geometry and topology and can be computed numerically via solving the Stokes equation. However, the associated computational effort can be enormous for large-scale models, even using the efficient Lattice-Boltzmann method. In this study, an efficient method is developed for computing the equivalent permeability of digital rocks by simplifying the Stokes equation to Darcy equation. The method is based on the idea that a 3D digital core can be approximated by the combination of multiple 2D slices/layers, and the property of each layer is governed by the Stokes equation. Specifically, to mimic the 2D fine-scale velocity solved from the Stokes equation, a local permeability is assigned according to the velocity for each voxel. In addition, the nearest distance from each voxel to the solid wall is used to approximate the 2D fine-scale velocity, without the need of solving the Stokes equation in 2D for each layer. By this means, the 3D Stokes equation can be simplified to multiple 2D cases that provide the local permeability distribution for the 3D Darcy equation, and thus the computational cost can be significantly reduced. Case studies have been conducted on various samples in different scales. The results demonstrate that the computed 3D permeabilities using finite difference method (based on the Darcy equation) agree well with those using Lattice-Boltzmann method (based on the Stokes equation), and a speedup factor of about O(10) is achieved. The method can be applied to both sandstone and carbonate rocks for fast estimation of block permeability.

How to cite: Liao, Q., Li, G., Huang, Z., Sheng, M., Li, J., and Zhang, D.: Fast digital rock upscaling: from Stokes equation to Darcy equation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4925, https://doi.org/10.5194/egusphere-egu22-4925, 2022.

Hangjinqi area is located in the northern margin of Ordos Basin in north China, the main body of which is on the inherited palaeo-uplift, and has been considered as a favorable oil-gas accumulation direction area. Duguijiahan block structurally located in the middle of Hangjinqi area, in the fault transition zone of Boerjianghaizi fault and Wulanjilinmiao fault, which is a transition area from quasi-continuous gas reservoir to continuous gas reservoir. By analyzing the reservoir characteristics and evolution process of tight sandstone gas reservoirs, the thermal maturation history of source rocks and the history of natural gas charging in Lower Shihezi Formation, this paper studies the natural gas accumulation process in the transition zone between quasi-continuous and continuous gas reservoirs, hoping to contribute to tight gas exploration in Ordos Basin and other basins with similar tectonic backgrounds in the world. The results show that the initial porosity of the Lower Shihezi Formation in Duguijiahan block is about 32~36%, and experienced the porosity decreasing of compaction (avg. = 18.58%) and cementation (avg. = 11.03%), and porosity increasing of dissolution (avg. = 1.24%). The sandstone densification (porosity <10%) occurred in the mid-late Jurassic (~170–150 Ma). Due to tectonic uplift from the end of the Early Cretaceous to the present day, the present porosity has basically inherited the characteristics of the end of the Early Cretaceous, and the average porosity is only 8.4%. On the other hand, based on the homogenization temperature test of fluid inclusions, laser Raman spectroscopy analysis of gas inclusions and basin simulation, the hydrocarbon charging time of the Lower Shihezi Formation gas reservoir in Duguijiahan block is early Cretaceous (~145-100Ma), indicating that the gas charging time of the gas reservoir in the study area is later than the reservoir densification time. Furthermore, the natural gas charging time in the study area is characterized by gradual charging from south to north, indicating that the early natural gas charging is mainly affected by the maturity of underlying source rocks. From the end of early Cretaceous to now, it is the adjustment period of natural gas accumulation in the study area. The continuous tectonic uplift leads to the decrease of geothermal temperature, the loss of reservoir pressure and the formation of fractures. The natural gas charged in the early stage gradually migrates and accumulates along the northern up-dip direction of the fracture zone. The Lower Shihezi Formation was pinched out in the northern Gongkahan uplift to form effective blocking. The migration process of natural gas has been confirmed by the present exploration findings, the relationship between porosity and permeability of reservoir physical properties and the difference of natural gas components in the north and south.

How to cite: Yu, H.: Study on tight sandstone gas accumulation process in transition zone of basin-margin: A case study of Duguijiahan block, Hangjinqi area, northern Ordos Basin, China, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4986, https://doi.org/10.5194/egusphere-egu22-4986, 2022.

EGU22-5367 | Presentations | ERE5.6

Verification of TRANsport Simulation Environment coupling with PHREEQC for reactive transport modelling 

Svenja Steding, Michael Kühn, and Thomas Kempka

Many types of geological subsurface utilisation are associated with fluid and heat flow as well as simultaneously occurring chemical reactions. For that reason, reactive transport models are required to understand and reproduce the governing processes. In this regard, reactive transport codes must be highly flexible to cover a wide range of applications, while being applicable by users without extensive programming skills at the same time. In this context, the TRANsport Simulation Environment (Kempka, 2020) was coupled with the geochemical reaction module PHREEQC (Parkhurst & Appelo, 2013), providing multiple features that make it applicable to complex reactive transport problems in various fields. Code readability is ensured by the applied high-level programming language Python which is relatively easy to learn compared to low-level programming languages. In the present study, common geochemical benchmarks are used to verify the numerical code implementation.

Currently, the coupled simulator can be used to investigate 3D single-phase fluid and heat flow as well as multicomponent solute transport in porous media. In addition to that, a wide range of equilibrium and nonequilibrium reactions can be considered. Chemical feedback on fluid flow is provided by adapting porosity and permeability of the porous media as well as fluid properties. Thereby, users are in full control of the underlying functions and equations of state. Both, the solution of the system of the partial differential equations and PHREEQC module, can be easily parallelised to increase computational efficiency.

The benchmarks used in the present study include density-driven flow as well as advective and diffusive reactive transport of solutes. Furthermore, porosity, permeability and diffusivity changes caused by kinetically controlled dissolution-precipitation reactions are considered to verify the main features of our reactive transport code. In future, the code implementation may be used to quantify processes encountered in different types of subsurface utilisation, such as geothermal energy production, geological energy, CO2 and nuclear waste storage.

References:

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

Parkhurst, D.L.; Appelo, C.A.J. (2013). Description of Input and Examples for PHREEQC Version 3 - a Computer Program for Speciation, Batch-reaction, One-dimensional Transport, and Inverse Geochemical Calculations. In Techniques and Methods; Publisher: U.S. Geological Survey; Book 6, 497 pp. (https://pubs.usgs.gov/tm/06/a43/)

How to cite: Steding, S., Kühn, M., and Kempka, T.: Verification of TRANsport Simulation Environment coupling with PHREEQC for reactive transport modelling, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5367, https://doi.org/10.5194/egusphere-egu22-5367, 2022.

EGU22-5401 | Presentations | ERE5.6

Life-span economic and environmental analysis of deep borehole heat exchanger coupled geothermal heat pump heating system with different drilling depths 

Wanlong Cai, Fenghao Wang, Chaofan Chen, Zeyuan Wang, Jinghua Jiang, Olaf Kolditz, and Haibing Shao

Geothermal energy stored in the 1~2 km depth, which has advantages in terms of its continuity and sustainability, has attracted more attention in recent decades in the building heating industry. To meet the carbon-neutral prospect in the building sector, a new-type deep borehole heat exchanger (DBHE) is proposed to extract geothermal energy and has been utilized in Europe and northern China. The DBHE is typically drilled to more than 2000 m depth, and it is usually coupled with a heat pump to supply heat to the buildings. In this work, a dual-continuum finite element method was implemented in the open-source software OpenGeoSys to mimic the heat transfer process between the DBHE and the surrounding subsurface. After validating against in-situ experimental data of the pilot DBHE heating project in Xi’an, a heat pump model was also included in the OpenGeoSys model so that the entire heating system can be simulated over the long-term operation. Results show that the circulation temperatures of the DBHE have a decreasing trend during the long-term operation. Through the energy analysis, the amount of heat extracted by the DBHE was found to be mainly supplied by the energy stored within the surrounding soil. With different drilling depths of the DBHE, long-term simulation results illustrate that the heat extraction rate increases with deeper depth. After considering the electricity consumption of the heat pump and circulation pump, the Levelized cost of heating (LCOH) of the DBHE heating system was evaluated over its life-span cycle, and the optimal drilling depth of the DBHE was found to be 2600 m based on the specific geological properties of Weihe Basin, Xi’an. The proposing evaluation method provides a reference for decision-makers when designing the DBHE heating system.

How to cite: Cai, W., Wang, F., Chen, C., Wang, Z., Jiang, J., Kolditz, O., and Shao, H.: Life-span economic and environmental analysis of deep borehole heat exchanger coupled geothermal heat pump heating system with different drilling depths, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5401, https://doi.org/10.5194/egusphere-egu22-5401, 2022.

The geothermal hot water reservoir below the small town of Waiwera in New Zealand has been known to the indigenous people, the Maori, for many centuries. Its use by European immigrants began in the 19th century. Until the end of the 1960s, all production wells drilled for the warm water were artesian. But, triggered by overproduction, the water which has a temperature of up to 50 °C, has to be pumped up since then. In the 1970s, the warm water springs on Waiwera beach also dried up. Therefore, the Auckland Council implemented a water management plan for a future sustainable use of the area in the 1980s (Kühn and Altmannsberger 2016). Just recently, there have been reports about recovered, temporary artesian flow from several wells. Further, there is indication for a renewed activity of the hot springs at the beach (Präg et al. 2020). For a comprehensive understanding and an environmentally friendly and balanced long-term usage of the aquifer, a fairly complex hydrogeological model is required.

Various approaches for a quantified hydrogeological description of the Waiwera reservoir have been implemented since the 1980s. Some are data driven (Kühn and Schöne 2017, Kühn and Grabow 2021) and others process based (Kühn and Altmannsberger 2016, Somogyvári et al. 2019) to finally understand and assess the constraints and impacts on the system (Kühn and Schöne 2018). However, none of the models directly delivers all the results needed for an all-encompassing water management. Disadvantage of all previous work is the independent model set-up and usage of only some of the acquired monitoring and simulation results. We present now a Geographic Information System (GIS) as a data base which integrates all geoscientific information known about the geothermal area of Waiwera combined with software tools for management. This will be the basis of the next generation of hydrogeological models for the geothermal area.

Literature

Kühn, M., Altmannsberger, C. (2016): Assessment of data driven and process based water manage-ment tools for the geothermal reservoir Waiwera (New Zealand). - Energy Procedia, 97, 403-410. https://doi.org/10.1016/j.egypro.2016.10.034

Kühn, M., Grabow, L. (2021): Deconvolution well test analysis applied to a long-term data set of the Waiwera geothermal reservoir (New Zealand). - Advances in Geosciences, 56, 107-116. https://doi.org/10.5194/adgeo-56-107-2021

Kühn, M., Schöne, T. (2018): Investigation of the influence of earthquakes on the water level in the geothermal reservoir of Waiwera (New Zealand). - Advances in Geosciences, 45, 235-241. https://doi.org/10.5194/adgeo-45-235-2018

Kühn, M., Schöne, T. (2017): Multivariate regression model from water level and production rate time series for the geothermal reservoir Waiwera (New Zealand). - Energy Procedia, 125, 571-579. https://doi.org/10.1016/j.egypro.2017.08.196

Präg, M., Becker, I., Hilgers, C., Walter, T. R., Kühn, M. (2020): Thermal UAS survey of reactivated hot spring activity in Waiwera, New Zealand. - Advances in Geosciences, 54, 165-171. https://doi.org/10.5194/adgeo-54-165-2020

Somogyvári, M., Kühn, M., Reich, S. (2019): Reservoir-scale transdimensional fracture network inversion. - Advances in Geosciences, 49, 207-214. https://doi.org/10.5194/adgeo-49-207-2019

How to cite: Kühn, M. and Kempka, T.: Geographic Information System (GIS) as a basis for the next generation of hydrogeological models to manage the geothermal area Waiwera (New Zealand), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5583, https://doi.org/10.5194/egusphere-egu22-5583, 2022.

EGU22-5778 | Presentations | ERE5.6

Hydraulic effects of porous media hydrogen storage for different future energy supply systems 

Firdovsi Gasanzade and Sebastian Bauer

Many countries worldwide have committed to mitigating global climate change by switching to renewable energy generation, leading to continuously increasing shares of renewable energy sources in the energy system. However, one major drawback is the strongly fluctuating nature of those energy sources. Power to gas technology to generate hydrogen and subsurface hydrogen storage is one of the options to balance this fluctuating availability. Depending on the specific development of the energy system, different scales of storage are needed with different scales of impacts on the subsurface that may arise. This study, therefore, quantifies the induced hydraulic effects of hydrogen storage in porous formations, accounting for four possible future energy system scenarios and based on an existing geological storage structure. The aim is to identify and quantify the large-scale and long-term hydraulic effects of the storage operations and to estimate the affected subsurface spaces using numerical simulation models.

The storage structure used was identified in a storage potential study and is located in the North German Basin at a depth of about 1000 m and consists of a Rhaetian sandstone formation. Formation permeability and porosity are derived from regional depth correlations, while boundary conditions are applied considering the local geological settings. For the storage operation, energy and mass balanced load profiles are derived from the four considered scenarios, with charging rates during times of surplus power varying from 1.9 GW to 6.4 GW and discharging rates during withdrawal from 4.7 GW to 15.9 GW, depending on the respective energy system scenario.

Simulation results show that up to 21 storage wells and 2.8 billion cubic meters of storage gas in place volume are required to support the required energy output for all scenarios considered. Scenario analysis shows that significant pressure responses at the well bottom hole are thus induced, which are limited to a geomechanically allowable range of 80 bar to 130 bar. Due to the high withdrawal rates required, storage design is mainly influenced by the lower pressure limit. In the far field, pressure responses of more than 3 bars and 5 bars are found within horizontal distances of up to 7.5 km and 5 km, respectively. The vertical pressure impact is much lower at 5 m and 20 m, respectively. This can be recalculated as a total impacted volume by 3 bars and 5 bars from 1.25×109 m3 - 4.63 ×109 m3 to 0.57×109 m3 - 1.10×109 m3, depending on the scenario, respectively. This study thus shows that for grid-scale energy storage subsurface space on the order of tens of millions of m3 for the hydrogen gas phase will be required, while a much larger volume of 4.6×109 m3 will be affected by pressure changes of 3 bar or more. On the other hand, at least from an energetic point of view the storage structure investigated is sufficient to accommodate the national storage demand. The study results and the approach presented can thus contribute during site selection and storage facility planning to characterize subsurface and energy system requirements.

How to cite: Gasanzade, F. and Bauer, S.: Hydraulic effects of porous media hydrogen storage for different future energy supply systems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5778, https://doi.org/10.5194/egusphere-egu22-5778, 2022.

EGU22-5823 | Presentations | ERE5.6

Structural Geologic Modelling and Restoration Using the Ensemble Kalman Filter 

David Oakley, Nestor Cardozo, Per Røe, and Ariel Almendral Vazquez

Structural restoration using kinematic principles of fault-related folding is a valuable tool in building realistic geological models. Models are, however, typically uncertain and non-unique. While data inversion methods can be employed to find a best-fit model and estimate uncertainty, their use is limited to relatively simple models involving a single fault in two dimensions. In this work, we employ an iterative form of the Ensemble Kalman Filter (EnKF) together with a kinematic model for deformation around normal faults to build and restore three-dimensional structural geologic models. The EnKF is ideally suited to data inversion problems that involve large numbers of model parameters and is frequently used in reservoir simulations, which often do not consider uncertainty in geologic structure. We develop a workflow in which fault geometry, the distribution of slip on a fault, and the geometry of folded horizons are all modelled using the EnKF. The models are constrained by observations of faults and horizons in the present deformed state together with the expectation that horizons should restore flat. We test two modelling approaches: a restoration-based approach in which the model is built in the deformed state and then restored, and a forward modelling-based approach in which the model is built in the restored state and then forward modelled to match present-day data. We test these methods first on a synthetic model involving a single fault and then on a real-world example involving five faults. Both the restoration- and forward modelling-based methods work well for the synthetic model, but forward modelling works best for the more complex real-world case study. The EnKF method provides not only a best-fit model but also an estimate of model uncertainty. The estimation of uncertainty is, however, hindered by the phenomenon of ensemble collapse, which results in underestimation of the uncertainty in model parameters at small ensemble sizes. We employ bootstrap-based localization and covariance inflation to help mitigate this issue and use a dummy parameter to identify whether significant ensemble collapse has occurred. While ensemble collapse remains a challenge in some cases, the EnKF nonetheless shows considerable promise as a tool for building complex many-parameter structural models that are kinematically restorable, and it holds the potential for future integration of structural modelling with other EnKF-based workflows in subsurface modelling.

How to cite: Oakley, D., Cardozo, N., Røe, P., and Almendral Vazquez, A.: Structural Geologic Modelling and Restoration Using the Ensemble Kalman Filter, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5823, https://doi.org/10.5194/egusphere-egu22-5823, 2022.

For geothermal reservoirs operated by production/re-injection wells, thermal lifetime is usually defined in terms of a temperature drop threshold, and estimated as a function of fluid turnover time and heat exchange surface-area-per-volume,

Theat  =  R · Tfluid  +  D · σ2 · Tfluid2  ,

with Tfluid supposed to be measurable by means of a tracer test; 
         σ is rather difficult to infer from tracer signals alone.

For ‘aquifer’-like reservoirs, the linear term prevails:

       R > (>>) 1 ,    D · σ2 · Tfluid << 1

For fracture-dominated (‘petrothermal’) reservoirs, the quadratic term prevails:

       R ≈ 1 ,           D · σ2 · Tfluid >> 1

Deriving Tfluid from artificial-tracer signals looks 'model-independent', but is subject to large-time extrapolation uncertainty (which 'restores' model-dependence).

Unlike thermal forecasting, tracer-based prognosis of solute co-production (more precisely, of its lower-bound level, assuming conservative transport by fluid turnover only, non-'replenished' from adjacent rocks) isn't impeded by large-time extrapolation uncertainty, nor by reservoir model/parameter ambiguity, since mass output prediction as a function of time,

Mout (t)   =   (Cini – Cresid)  [ VOLout(t) – ∫otot' Q(t’) Q(t’’) g(t’’) dt’’ dt’  ]

requires just knowledge of conservative-tracer fluxes within the forecasting time horizon.

Once a tracer test was conducted in accordance with the rules of the art [usually including observance of flux-type B.C. for tracer input and fluid sampling, cf. Kreft_and_Zuber_1978], the reservoir can be treated like a 'black box' with 'response function' (Green’s kernel surrogate) g.

This approach is adequate for (conservative) solute co-production, but not for heat transport.

 

 

Tracer test results from a particular Upper-Jurassic (Malm) carbonate aquifer near Munich illustrate the issue with Theat  as a 'function' of Tfluid. Tracer signals available to date yield Tfluid in the range of months (still subject to extrapolation uncertainty), and are compatible with both fracture-dominated and ‘aquifer’-like representations of reservoir structure; ‘compatible’ σ values span four(!) magnitude orders.

By contrast, tracer signals from a fractured-porous reservoir, Eastern side of the Upper Rhine rift could be used to predict 'geothermal lithium' output (and its gradual depletion in reservoir fluid turnover), irrespective of reservoir model availability/parametrization. The non-trivial challenge, however, is to foresee and quantify overall WRI effects of ‘spent fluid’ re-injection, the latter being depleted of its particular micro-constituent (albeit at trace levels only), but likely acidized / 'unreliably' buffered at major-ion levels. WRI cannot be told from conservative-tracer signals; hydrogeochemical modeling (Kölbel_et_al._2020, Maier_et_al._2021) becomes indispensable.

We gratefully acknowledge long-term support from Germany’s Federal Ministry for Economic Affairs and Energy (BMWi) within applied research projects “LOGRO”, “TRENDS”, “UnLimiteD”, funded under grant nos.  0325111B, 0325515, 03EE4023E (www.geothermal-lithium.org, https://sites.google.com/site/goetracerhydro/researchprojects, https://sites.google.com/view/bmwi-0325515-trends).

 

Kölbel L, Kölbel T, Maier U, Sauter M, Schäfer T, Wiegand B (2020) Water-rock interactions in the Bruchsal geothermal system by U-Th series radionuclides. GeoThermalEnergy, 8:24

Kreft A, Zuber A (1978) On the physical meaning of the dispersion equation and its solutions for different IBC. Chem Eng Sci, 33:1471–1480

Maier U, Tatomir A, Sauter M (2021) Hydrogeochemical modeling of mineral alterations following CO2 injection. Appl Geochem, 136:10515

How to cite: Ghergut, H. B. J., Wiegand, B., Wagner, B., and Sauter, M.: Do tracer tests enable model-independent predictions of georeservoir output? two examples from Southern Germany, involving thermal drawdown and solute co-production, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6133, https://doi.org/10.5194/egusphere-egu22-6133, 2022.

EGU22-10115 | Presentations | ERE5.6

Environmental hazard quantification toolkit based on modular numerical simulations 

Morgan Tranter, Svenja Steding, Christopher Otto, Konstantina Pyrgaki, Mansour Hedayatzadeh, Vasilis Sarhosis, Nikolaos Koukouzas, Georgios Louloudis, Christos Roumpos, and Thomas Kempka

Comprehensive risk assessments for subsurface utilisation projects such as in-situ coal conversion, deep geothermal energy, geological storage, and waste disposal are implemented to a limited extent in common practice. The impacts of subsurface processes on environmental hazards (e.g., migration of groundwater-borne contaminants, induced seismicity, and subsidence) are often convoluted and therefore not trivially to predict. Furthermore, decisions on project feasibilities are commonly based on expert knowledge subject to non-standardised approaches. However, an objectively and transparently developed risk assessment is imperative for a publicly accepted, long-term economic and environmentally friendly design of future subsurface utilisation.

We propose a new environmental hazard quantification framework based on modular simulations. The aim is to create a uniform basis for both project developers and authorities to carry out risk analyses. The approach streamlines state-of-the-art numerical models [1,2], accounting for multiphase flow, geomechanics, geochemistry, and heat transport, to determine the likelihood and severity of hazards. The method uses the results of the computational expensive Monte Carlo simulations of each module to train gradient boosting machine learning algorithms. These surrogate models facilitate loose coupling within the framework and a seamless integration into a graphical user interface for demonstrating hazard probability distributions.

The approach was applied to two example study areas with complex geological settings as part of a risk assessment for in-situ coal conversion. A substantial rock volume is extracted during this operation, and a contaminant pool is potentially left behind, which may put the environment at risk. With our presented approach, the shortcoming of using conceptually simplified models are substantially reduced, since subsurface complexities are accounted for. The transparency of the assessment basis should generally increase the acceptance of geoengineering projects, which is considered one of the crucial aspects for the further development and dissemination of geological subsurface utilisation.

[1] Hedayatzadeh et al.: Ground subsidence and fault reactivation during in-situ coal conversion assessed by numerical simulations, EGU22, https://meetingorganizer.copernicus.org/EGU22/EGU22-11736.html, 2022.
[2] Kempka et al.: Probability of contaminant migration from abandoned in-situ coal conversion reactors, EGU22, https://meetingorganizer.copernicus.org/EGU22/EGU22-11204.html, 2022.

How to cite: Tranter, M., Steding, S., Otto, C., Pyrgaki, K., Hedayatzadeh, M., Sarhosis, V., Koukouzas, N., Louloudis, G., Roumpos, C., and Kempka, T.: Environmental hazard quantification toolkit based on modular numerical simulations, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10115, https://doi.org/10.5194/egusphere-egu22-10115, 2022.

EGU22-11204 | Presentations | ERE5.6

Probability of contaminant migration from abandoned in-situ coal conversion reactors 

Thomas Kempka, Svenja Steding, Morgan Tranter, Christopher Otto, Torsten Gorka, Mária Hámor-Vidó, Wioleta Basa, Krzysztof Kapusta, and István Kalmár

In the context of a potential utilisation of coal resources located in the Mecsek mountain area in Southern Hungary (Püspöki et al.. 2012), an assessment of groundwater pollution resulting from a potential water-borne contaminant pool remaining in in-situ coal conversion reactors after site abandonment has been undertaken. The respective contaminants may be of organic (i.e., phenols, benzene, polycyclic aromatic hydrocarbons, etc.) and inorganic nature (i.e., ammonia, mercury, zinc, cyanide, heavy metals, etc.), whereby data for the Mecsek coal has been derived from extensive laboratory testing.

The probability assessment was carried out by means of numerical simulations of fluid flow as well as contaminant and heat transport including retardation using the TRANsport Simulation Environment (Kempka, 2020). Hereby, the main uncertainties, e.g., changes in hydraulic gradient and hydraulic contributions of the complex regional and local fault systems in the study area, were assessed in a deterministic way to identify the parameters relevant for the overall sensitivity study. Using Monte-Carlo analyses and Latin hypercube sampling, the uncertainty bandwidths of water table, retardation factors, dispersion coefficients, hydraulic conductivities of aquitards, faults and aquifers as well as groundwater recharge were considered.

The simulation results demonstrate that fluid flow via the regional faults is the main driver for a potential contamination of the shallow groundwater aquifers. Consequently, the numerical simulation results on potential fault reactivation due to coal extraction (Hedayatzadeh et al., 2022) were taken into account in view of probable hydraulic conductivity changes in the regional fault systems and the rock matrix surrounding the abandoned reactors. The probabilities of groundwater aquifer contamination within a time horizon of 50 years are presented based on maximum contaminant concentrations, cumulative mass balances as well as migration distances of the contaminant plume. The results of this analysis are essential for mining authorities as well as potential stakeholders to improve the understanding on potential environmental impacts, and have been integrated into a specific toolkit for risk assessment (Tranter et al., 2022) for that purpose.

References

Hedayatzadeh, M. et al. (2022) Ground subsidence and fault reactivation during in-situ coal conversion assessed by numerical simulations, https://meetingorganizer.copernicus.org/EGU22/EGU22-11736.html

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

Püspöki, Z. et al. (2012) Stratigraphy and deformation history of the Jurassic coal bearing series in the Eastern Mecsek (Hungary). International Journal of Coal Geology 102, 35–51. https://doi.org/10.1016/j.coal.2012.07.009

Tranter, M. et al. (2022) Environmental hazard quantification toolkit based on modular numerical simulations, https://meetingorganizer.copernicus.org/EGU22/EGU22-10115.html

 

How to cite: Kempka, T., Steding, S., Tranter, M., Otto, C., Gorka, T., Hámor-Vidó, M., Basa, W., Kapusta, K., and Kalmár, I.: Probability of contaminant migration from abandoned in-situ coal conversion reactors, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11204, https://doi.org/10.5194/egusphere-egu22-11204, 2022.

EGU22-11736 | Presentations | ERE5.6

Ground subsidence and fault reactivation during in-situ coal conversion assessed by numerical simulations 

Mansour Hedayatzadeh, Vasilis Sarhosis, Torsten Gorka, Mária Hámor-Vidó, and István Kalmár

One unconventional coal extraction method is in-situ coal conversion. In this process, the coal is gasified in an underground reactor. A crucial issue that should be considered in this approach is the assessment of short and long-term environmental hazards and risks to human health and the environment resulting from potential surface subsidence and fault activation in the presence of complex geological conditions. This research aimed to assess potential environmental impacts associated with a commercial-scale application of in-situ coal conversion in a high coal production area in the Maza-Varalja region in Hungary. The Maza-Varalja region is an environmentally protected forested area. In this research, the numerical modeling of surface subsidence and fault activation was implemented using the finite-volume numerical modeling software FLAC3D. A predictive three-dimensional geomechanical model has been developed using site-specific geological data. The material model is Mohr-Coulomb elastic-plastic. Zero thickness interfaces were employed to address the fault behavior with friction and cohesive characteristics. The in-situ stress was determined by geostatic loading and a horizontal stress factor. The boundary conditions were zero-displacement and positioned sufficiently far from the coal seams to not artificially influence the stress field. The initialized zone stresses were considered using the density of the zones above them and gravity. The horizontal to vertical stresses ratio was determined to be one. A series of sensitivity studies were conducted to address the importance of geologic parameters that have an impact on surface subsidence, fault activation, and pollutant migration to the surface. In order to achieve this, seven variables, including the unit weight, Young’s modulus, Poisson’s ratio, friction angle, cohesion, fault friction, and excavation sequence, were considered. Sixty-six simulations were undertaken and analyzed. The simulation results demonstrate that surface subsidence is affected by the average Young’s modulus of the geological strata and the fault activation to the friction angle of the faults. Also, shallower seams are more likely to produce surface subsidence, while as excavation depth increases, surface subsidence decreases. The model's results have been used to develop an Environmental Hazard and Risk Management toolkit (Tranter et al., 2022) for planning and decision-making processes during in-situ coal conversion to ensure that environmental risks and mitigation actions are clearly quantified and outcomes forecasted. 

How to cite: Hedayatzadeh, M., Sarhosis, V., Gorka, T., Hámor-Vidó, M., and Kalmár, I.: Ground subsidence and fault reactivation during in-situ coal conversion assessed by numerical simulations, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11736, https://doi.org/10.5194/egusphere-egu22-11736, 2022.

EGU22-645 | Presentations | ERE5.7

Analysis of geomechanical properties of an Indian unconventional shale reservoir using well logs 

Sanjukta De and Debashish Sengupta

The study of geomechanics is receiving substantial importance recently in the petroleum industry as various problems, encountered during drilling a well to the completion stage of the extraction of hydrocarbon from the reservoir, can be addressed and mitigated with the knowledge of geomechanics. Particularly, for unconventional shale reservoirs, where challenges are more to have well stability and to extract a significant amount of production from the reservoir with ultra-low permeability, geomechanics plays a key role.  Well logs can be used to analyze and estimate various parameters related to geo-mechanical properties of the rock formations in a time-efficient and cost-effective manner. The present work is aimed to study geomechanical properties of Cambay Shale, Jambusar-Broach block, Cambay Basin, India, with the application of basic and advanced well logs like Sonic Scanner, Elemental Capture Spectroscopy (ECS) and Formation Micro Imager (FMI).

Sonic Scanner log, with state-of-art sonic measurements, has been utilised to obtain a quantitative estimation of parameters related to elastic and geomechanical properties of the formation like Poisson’s ratio, VPVS ratio, Young’s modulus, Bulk modulus, Shear modulus and strength of the rock. These parameters are useful for manipulating drilling programmes with lesser complications, analysing wellbore stability and designing an effective hydro-fracture operation for optimum production. Analysis of FMI log has been used to get information on drilling-induced features like breakouts and drilling-induced fractures (DIFs) which are indicators of the orientation of horizontal stresses and provide useful information in controlling wellbore stability.

Brittleness index (BI) is commonly used as a key geomechanical parameter in evaluating fracturability of the formation. Two log-based methodologies have been used in the present study to evaluate continuous BI. In one method, Sonic Scanner measurements have been used to estimate elastic moduli-based BI.  The other method of BI estimation is based on the mineral composition of the formation. ECS log has been used to obtain the continuous mineralogical composition of the formation. As both of the methods for BI estimation are having intrinsic limitations, a combination of the two methods will provide more realistic information for brittle regions in the shale formation. The advantage of evaluation of the geomechanical properties of the studied shale formation using advanced well logs will be beneficial to the petroleum industry to reduce the cost and to have continuous information for targeting potential regions for hydrocarbon extraction with fewer complications.

 

Acknowledgement

The authors would like to thank Oil and Natural Gas Corporation Limited, India for providing the requisite dataset and core samples to carry out the present study.

How to cite: De, S. and Sengupta, D.: Analysis of geomechanical properties of an Indian unconventional shale reservoir using well logs, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-645, https://doi.org/10.5194/egusphere-egu22-645, 2022.

EGU22-3353 | Presentations | ERE5.7

A novel method to predict hydraulic fracturing breakdown pressure. 

Ben Powlay, Murat Karakus, Khalid Amrouch, and Chris Chester

Hydraulic fracturing is increasingly becoming utilized within Underground hard rock mines such as block caves and Sub Level Caves as a way to promote controlled cave propagation, increase resource recovery, and seismic hazard through the manipulation of rock mass properties through fracture surface creation and limiting of stress concentration.
While hydraulic fracturing is not a new application, it is still in its infancy in mining projects such as cave mining. It is used on entirely different scales, under different stress regimes and with varying motives. Therefore, more research needs to be carried out in understanding the fundamentals of fracture growths that can help improve hydraulic fracturing applied in mining projects.  

Predicting breakdown pressure is an important part of the designing of hydraulic fracturing with accurate prediction being the baseline of designing and implementing a successful preconditioning campaign in all industries, but especially so in block cave mining.
The most commonly used breakdown pressure theoretical model is the conventional breakdown model and is based on tensile strength and confining stresses acting upon the borehole. This might be imprecise within hard rock mining environments and increasingly so at depth of higher stresses. 

This work compares indirect tensile strength results and their fracture toughness, from both conventional Brazilian Disc Testing and the recently developed Adelaide University Snapback Indirect Tensile Testing (AUSBIT).
By using lateral strain control to stabilise the brittle material responses, AUSBIT allows for the capture of true post-peak behaviour, i.e. controlled fracture propagation can be achieved.

The captured post-peak behaviour allows practitioners to measure a more reflective tensile strength and fracture toughness from just one testing method, Alongside this are laboratory hydraulic fracture experiements on the same rock unit, which in turn is used to propose a new Hard Rock Breakdown Pressure prediction based on the conventional method which incorporates fracture toughness when checked against the results of the lab fracture experiments, and other lab studies. 

The results of this work factors in a progressive toughness of a rock at depths, and creates a more accurate predictor of breakdown pressure in underground hard rock mines under varying stress conditions.  

How to cite: Powlay, B., Karakus, M., Amrouch, K., and Chester, C.: A novel method to predict hydraulic fracturing breakdown pressure., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3353, https://doi.org/10.5194/egusphere-egu22-3353, 2022.

EGU22-4295 | Presentations | ERE5.7

Characteristics of microscopic pore throat changes in shale reservoir after CO2 fracturing 

Mengqing He, Tiantai Li, Xing Huang, Xiang Li, and Ke Wu

The interaction of CO2 with the shale reservoir in the process of CO2 fracturing can change the pore-throat structure characteristics of the rock. In order to determine the microscopic pore throat change characteristics in shale reservoir after CO2 fracturing , typical shale core samples before and after fracturing were selected, combined with casting thin slice(CST), field emission scanning electron microscope(FESEM), CT scan, high pressure mercury injection(HPMI), and nuclear magnetic resonance(NMR) test results, and quantitatively evaluate the change characteristics of micro pore throats in shale  reservoir after CO2 fracturing. The results show that various storage spaces such as intergranular pores, intragranular pores, organic pores, and microfractures can be observed in shale reservoirs before CO2 fracturing, which are with poor pore throat connectivity, and most of them are distributed in a dispersed and isolated state. The discharge pressure is low, 0.89Mpa on average, the mercury removal efficiency is low, and the maximum mercury saturation difference is large. Movable fluid saturation ranges from 2.72% to 41.24%, with an average of 26.78%. After CO2 fracturing the shale reservoir, FE-SEM photos often show dissolved pores. The proportion of micro-cracks increased, and the number of cracks observed for a single sample ranged from 1 to 11, with an average of 4. The average length, opening and spacing of micro-cracks are 27.75μm, 286.63μm, and 3.70μm. The average porosity and permeability of micro-cracks are 9.03% and 1.74×10-3μm2. The pore throat connectivity of the shale samples becomes better, the degree of development is higher, the displacement pressure is increased to 3.05MPa, and the mercury removal efficiency and the maximum mercury saturation are both increased. NMR results showed that the movable fluid saturation of shale core samples increased significantly after CO2 fracturing, and the movable fluid saturation was between 1.57% and 50.25%, with an average of 38.14%. CO2 fracturing shale reservoirs will not only produce secondary fractures, but also easily form complex fracture networks. In addition, it will also improve the dense micro-pore throat structure of the shale reservoir itself, increase fluid seepage capacity, and increase oil and gas recovery.

How to cite: He, M., Li, T., Huang, X., Li, X., and Wu, K.: Characteristics of microscopic pore throat changes in shale reservoir after CO2 fracturing, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4295, https://doi.org/10.5194/egusphere-egu22-4295, 2022.

EGU22-4374 | Presentations | ERE5.7

Assessment of Geothermal Potential in the Tbilisi Geothermal Reservoir 

Nino Kapanadze, George Melikadze, Mariam Todadze, Eka Tsutskiridze, and István Fórizs

Taking into account the world-wide energy crisis, the search and rational use of cheap and

ecologically pollution-free renewable energy sources are extremely important. Among these sources the geothermal energy is of great potentialities. Tbilisi has a high potential of geothermal sources, which have been in use since ancient times. The major areas of utilization are balneology and local heating of community and residential buildings. It also should be noted that most of the geothermal wells are non-operational. Therefore, a re-assessment of the geothermal potential of the Tbilisi deposit is of major importance from the standpoint of economic development based upon renewable, ecological cleaner energy sources. Field hydrogeophysical investigations (tentative testing, regime hydrodynamic and hydrochemical observations) have been carried out to assess the main thermo-hydrodynamic parameters of water containing horizons. In the field and laboratory conditions thermal properties of aquifer matrix rocks as well as vertical and horizontal zonality of thermal flow have been investigated.

During testing the hydrodynamic influence of well Lisi 5 on wells Lisi 7 and 8, as well as on well Saburtalo 1 was established. It appears that wells Saburtalo 4 and 6 are out of influence area, they are not influenced by well Lisi 5, which points to their independent regime. For the proper characterization of this water regime and assessing its influence area additional testing should be carried out in the future.

Based on previous and newly obtained geologic, hydrogeological and geophysical data, 3D model of Tbilisi thermal region was created which takes into account complexity of area, its separation into domains by faults, and their different hydrodynamic zonality. For modeling computer softwares such as Feflow 5.3, AquiferTestPro, etc. have been applied, which enabled to define hydrothermal resources and assess hydraulic parameters of water containing layers.  As a result of modeling work, the 10-year perspective of thermal deposit of Tbilisi was assessed at the present conditions of exploitation.

In the whole region subsidence of water horizon is expected. For example, in the Lisi district, if mean yearly discharge (exploitation rate) is preserved, water table drops by 2-5 m and the released thermal energy decreases from 5.5*1020  to 1.578*1017 J.  According to the simulated geothermal circulation system, when the used water of well 5 (1690 m3/day cooled down to 30 0C) was reinjected to the well 1 with negative level, ‘cooling of horizon and subsidence’ tendency became slower. Therefore, in the future creation and implementation of geothermal circulation systems are recommended.  This will help to achieve economical and ecologically approved exploitation of geothermal resources.

How to cite: Kapanadze, N., Melikadze, G., Todadze, M., Tsutskiridze, E., and Fórizs, I.: Assessment of Geothermal Potential in the Tbilisi Geothermal Reservoir, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4374, https://doi.org/10.5194/egusphere-egu22-4374, 2022.

For several decades, research on CCUS (carbon capture, storage, and utilization) have been extensively carried out to achieve substantial reduction of the amount of CO2 emitted into the atmosphere and effective resource development. In recent years, high temperature reservoirs have recently been considered as a target for CO2 injection. This aims at development of unconventional geothermal resources and CO2 mineralization.

Since the value of CO2-water interfacial tension is a fundamental property of fluid behavior in CO2-water-rock systems, many studies have been reported on CO2-water interfacial tension. However, the temperature of the geothermal reservoir in the above-mentioned technology may be up to 300 ℃, which is much higher than typical conditions for CCUS. It is not easy to perform measurements under such high temperature conditions, and no experimental data have been reported in existing studies.

Therefore, in this study, we performed molecular dynamics simulations to estimate the interfacial tension up to 300 ℃, and also studied the detailed properties such as density and dynamics.

How to cite: Shiga, M., Morishita, T., and Sorai, M.: Interfacial Tension of CO2-Water Under Conditions for High-Temperature Geothermal Systems: Prediction and Investigation by Molecular Dynamics Simulation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6837, https://doi.org/10.5194/egusphere-egu22-6837, 2022.

Oil production in karst areas often leads to negative consequences for ecosystems, including aquatic ones, since karst creates favorable conditions for the migration of oil mining pollution.

The study area is located in the oil and gas bearing zone of the Western Urals, the territory is assigned to the area of gypsum and carbonate-gypsum karst. The site (river basin) of one of the old-developed fields of the Perm Region was studied, which is characterized by a large number of oil mining infrastructure facilities.

The purpose of this study is to identify the features of technogenic transformation of ecosystems in karst conditions. For this, a field survey of the territory, sampling of surface and underground waters, grounds, bottom sediments and soils, measurements of the concentrations of pollutants in the air, the presence of the main ecological and trophic groups of microorganisms in water samples were carried out.

The process of hydrocarbons input (bitumization) covered karst cavities, springs, streams of the study area. In time, the concentration of hydrocarbons increased during periods of high water. Spatially, the hydrocarbon content gradually decreased from the polluted springs in the direction of the river mouth.

The increased content of hydrocarbons in bottom sediments (up to 54,872 mg/kg) was observed at almost all sample plots.

Areas with a tendency to accumulation of hydrocarbons were identified within the boundaries of the study area (soil pollution near the well cluster in the upper part of the river basin exceeds 100,000 mg/kg). Bottom sediments and soils are a deposit medium for pollutants, they can become secondary sources of pollution.

Microorganisms are an integral part of ecosystems, which serve as indicators of pollution. Quantitative changes in the group of heterotrophic and oil-oxidizing microorganisms of the spring microbocenosis are multidirectional. An increase in the number of heterotrophs and a decrease in the number of oil-oxidizing microorganisms are observed.

Technogenic salinization during oil production is an accumulation of salts (chlorides, sulfates, carbonates), which are contained in large quantities in high-mineralized stratal waters extracted along the way. The maximum values of chloride concentrations were recorded in the upper part of the river basin.

The karst region is composed of sulfate rocks, which have greater solubility compared to carbonate rocks, we believe that this primarily explains the high content of sulfate ion in water samples.

The increased salinity of the aquatic environment can be judged by the presence of halophilic microorganisms. At the points where halophilic organisms were detected, chloride concentrations exceeding background values were recorded. It should be noted that the number of halophiles is low.

Excess concentrations of benzene, hexane, toluene, hydrogen sulfide, and methane were recorded in the atmospheric air at certain points.

The transformation of ecosystems in the study area has a pronounced degradation orientation. Hydrocarbons make the greatest contribution to environmental pollution, and the presence of karst forms only aggravates the situation.

Measures to localize pollution and organizational recommendations to improve the environmental situation were proposed for each problem area.

 

The reported study was funded by Russian Foundation for Basic Research (RFBR) and Perm Territory, project number 20-45-596018.

How to cite: Khotyanovskaya, Y.: Technogenic transformation of ecosystems in the karst area during oil production, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6883, https://doi.org/10.5194/egusphere-egu22-6883, 2022.

EGU22-7882 | Presentations | ERE5.7

Mitigation of Seismic Hazards from Hydraulic Fracturing Using Cyclic Injection 

Dima Yassine, Alissar Yehya, and Elsa Maalouf

Hydraulic Fracturing (HF) aims at enhancing the permeability of oil and gas production reservoirs by injecting fluids at high pressures into the formation. However, this practice has been a concern to researchers; it causes perturbation to the underground system, alters the pressures and stresses along the nearby dormant faults, and may therefore, induce earthquakes under specific conditions. In this work, we study the efficacy of using a newly emerging technique, Cyclic Hydraulic Fracturing (CHF), to reduce the risk of induced seismicity while efficiently enhancing the reservoir permeability. Instead of injecting the fluid all at once at a high pressure during each stage, CHF increases the connectivity of the reservoir by injecting the same volume in a stage through different cycles. Each cycle represents a pressurization (injection) phase and a depressurization (zero-injection) phase. The effect of CHF on the stability of a fault at a close proximity to the HF operations is assessed using different injection strategies: conventional HF (constant injection per stage) and 2 CHF schemes (3 or 5 cycles per stage). For each strategy, we calculate the Coulomb Failure Stress (CFS) and the rate of seismicity along the fault using a 2D Finite Element poroelastic model. Our numerical simulations show that CHF delays the pore pressure diffusion along the fault due to the depressurization phases that allow the relaxation of the pore fluid pressure. It also reduces the seismicity rate on the fault when compared to conventional HF. Our results suggest that the mitigation of induced seismicity is possible by using a CHF procedure optimized to reduce the seismicity rate i.e., optimized number of cycles and pressurization/depressurization periods. This development paves a way to exploit sites that are abandoned due to seismic hazards.

How to cite: Yassine, D., Yehya, A., and Maalouf, E.: Mitigation of Seismic Hazards from Hydraulic Fracturing Using Cyclic Injection, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7882, https://doi.org/10.5194/egusphere-egu22-7882, 2022.

EGU22-9086 | Presentations | ERE5.7

A Novel Method for Natural Gas Hydrate Production: Depressurization and Backfilling with In Situ Supplemental Heat 

Shouding Li, Zhaobin Zhang, Yiming Sun, Tao Xu, Xiao Li, and Sijing Wang

Natural gas hydrate (NGH) is the most promising clean alternative energy resource for world. Based on the analysis of the bottleneck problems in hydrate recovery method, the achievement of reservoir-scale production of NGH by depressurization depend on three key factors, namely heat supply, reservoir stability and reservoir permeability. Based on the three principles of depressurization, in-situ supplemental heat and backfilling and increased permeability, the novel method, depressurization and backfilling with in-situ supplemental heat method was proposed. In this method, calcium oxide (CaO) powder is injected into the hydrate reservoir, which will provide a large amount of heat for the decomposition of NGH. At the same time, the Ca(OH)2 produced by the reaction will backfill the void volume left by hydrate decomposition and improve the permeability of the reservoir. The method is mainly implemented in three stages, i.e., horizontal well drilling and completion, powder injection and depressurization and backfilling. Currently, the two-dimension and three-dimension numerical simulations based on this novel method are completed. And the simulation results quantitatively verify the potential value of the depressurization and backfilling with in-situ supplemental heat method from the perspective of the theoretical calculation of numerical model. Based on the key procedures of this method, the related physical simulations for specific operating technique, such as CaO injection and corresponding production performance, are advancing. Combining above promising simulation results, this novel method is expected to be an effective hydrate recovery method.

How to cite: Li, S., Zhang, Z., Sun, Y., Xu, T., Li, X., and Wang, S.: A Novel Method for Natural Gas Hydrate Production: Depressurization and Backfilling with In Situ Supplemental Heat, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9086, https://doi.org/10.5194/egusphere-egu22-9086, 2022.

EGU22-11652 | Presentations | ERE5.7

Application of a dense network cross-correlation event detector to seismicity induced by hydraulic stimulations in Espoo/Helsinki, Finland 

Tommi Vuorinen, Gregor Hillers, Toni Veikkolainen, and Taavi Heikkilä

We have developed a cross-correlation based event detector with the primary application focus on dense, surface-installed temporary seismic networks monitoring the seismicity from a set target area. The event detector is capable of handling a terabytes-sized, noisy multi-channel dataset with hundreds of stations on a regular desktop PC. The detector works in 4 steps: 1. Generate templates from known events in a database. 2. Run cross-correlation for templates on continuous data. 3. Filter initial detections based on the surface network geometry. 4. Relocate the events in the filtered dataset applying correlation time delays and amplitude based magnitude corrections. The detector is accompanied with an event viewer designed to rapidly browse the resulting catalogue. We apply the detector on the induced seismicity of a planned Enhanced Geothermal System (EGS) doublet in Espoo, Finland. The company St1 Oy performed two hydraulic stimulations at around 6 kilometer depth beneath the Aalto University campus in Otaniemi, Espoo, Finland, in June-July 2018 and in May 2020. For both stimulations, the Institute of Seismology, University of Helsinki, installed a temporary ~100 geophone network to monitor the stimulation and post-stimulation stages. The network consisted of three-component 4.5 Hz geophones, mostly DATA-CUBE3s recording at 400 Hz. The geophone stations were organized into large arrays consisting of up to 25 stations, smaller 3-4 station arrays, and additional single stations for better azimuthal coverage. We present here the results from applying the detector on the datasets collected from the Otaniemi-EGS. The anatomy, such as magnitude of completeness, of the resulting event catalogue consisting of thousands of induced events will be discussed with the goal of publishing the finalized catalogue in near future. We also briefly discuss the impact of adding sub-surface borehole stations, and applying the detector to a sparser surface station network to broaden the scope of usefulness. 

How to cite: Vuorinen, T., Hillers, G., Veikkolainen, T., and Heikkilä, T.: Application of a dense network cross-correlation event detector to seismicity induced by hydraulic stimulations in Espoo/Helsinki, Finland, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11652, https://doi.org/10.5194/egusphere-egu22-11652, 2022.

EGU22-12104 | Presentations | ERE5.7

Geological characterisation of the Oliana anticline, an analogue of a geothermal reservoir (South Pyrenees) 

Pedro Ramirez-Perez, Irene Cantarero, Daniel Muñoz-López, Jean Pierre Sizun, and Anna Travé

The Oliana anticline in the Southern Pyrenees has been characterised as a potential outcrop analogue of a geothermal reservoir using field, petrographic and petrophysical analyses of fifty-two samples collected in the folded sequences that comprise conglomerates, sandstones, limestones, marls and gypsum. Five lithofacies (i.e., conglomerates, hybrid arenites, lithic arenites, carbonates and evaporites) were established based on the petrographic characteristics of sixty-three thin sections. Petrophysical measurements of forty samples from plugs oriented parallel and perpendicular to bedding indicate mineral densities varying from 2.334 to 2.767 g/cm3, bulk densities from 2.107 to 2.710 g/cm3, porosities from 0.42 to 22.14 %, permeabilities in the order of 10-19 to 10-13 m2 (0.001 to 393 mD, respectively) and velocity of compressional acoustic waves ranging from 2236 to 6322 ms-1.

These results evidence a negative linear correlation between porosity and bulk density and between compressional waves velocity and permeability. The lithofacies characterisation explains the petrophysical variability of the Oliana anticline. Thus, mineral composition, matrix content, and grain size were the most critical petrologic factors affecting porosity development and the consequent bulk density and permeability variability. In addition, petrophysical variability is also produced by diagenetic processes such as fracturing and dissolution. Fracturing significantly affected the rocks of the anticline’s northern limb, producing high permeabilities. In contrast, dissolution was the principal porosity-forming mechanism at the southern limb, producing punctual and disconnected porosity with low associated permeability.

The thermal conductivity measured in thirty-five samples using a TCi analyser and the Transient Plane Source (MTPS) method reveals a slight positive correlation between thermal conductivity and mineral density and between the samples stratigraphic position and thermal conductivity. Slight compositional heterogeneities between samples from different syn-orogenic units explain the last correlation. A low conductive (from 1.846 to 3.232 Wm-1K-1) area matched carbonatic and evaporitic succession, mainly located in the core of the anticline. In contrast, a high conductive zone (from 2.549 to 3.646 Wm-1K-1) is associated with the detrital syn-orogenic succession found in the fold limbs.

Our observations also suggest that thrusting in the north of the Oliana anticline conditionate the distribution of facies and precipitation of calcite cement. Proximal facies (i.e., conglomerates) are located at the northern limb, whereas distal facies (i.e., sandstones) are predominant at the southern limb of the anticline. Furthermore, higher fracture density and cementation have been observed at the north than at the south, probably associated with intense tectonic stress and fluid circulation through the principal thrust planes.

Based on rocks' thermal properties and permeability values, the Oliana anticline is classified as a petrothermal system because low permeabilities would disable convective heat transfer through sedimentary succession. Future research should study fracture permeability, as it could significantly improve the overall permeability of the structure.

How to cite: Ramirez-Perez, P., Cantarero, I., Muñoz-López, D., Sizun, J. P., and Travé, A.: Geological characterisation of the Oliana anticline, an analogue of a geothermal reservoir (South Pyrenees), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12104, https://doi.org/10.5194/egusphere-egu22-12104, 2022.

Hydraulic fracturing is a widely used technique for oil and gas extraction from the ultra-low porosity and permeability shale reservoirs. By injecting a large amount of fracturing fluids with specific chemical additives into shale reservoirs, porosity and permeability can be significantly improved, and thus enhances the recovery of oil and gas. However, hydraulic fracturing will not only bring economic benefits, but also cause a series of environmental issues, e.g., earth surface and water pollution. The Niutitang shale characterized by wide distribution, great thickness, high organic matter and brittle mineral contents is one of primary targets of shale gas development in South China. This research aims to simulate rock-fluid reaction and investigate the evolution of fluid composition and shale characteristics occurred during the hydraulic fracturing of the Niutitang shale. 

Two sets of shale samples from different depths of a well located in Central Hunan Province were exposed to fracturing fluids with different pH values. Afterwards, changes in the fluids and the shale matrix were investigated through a series of geochemical, mineralogical, and textural analysis. By comparing results of different experiments at different scales, key geochemical rock-fluid reactions occurred during this process were found, and their potential influences on shale gas production were discussed. 

Experimental results show obvious mineral dissolution, in particular the oxidation of pyrite.  Pyrite oxidation significantly alters fracturing fluids and subsequently impacts on the dissolution of other minerals. During the process of pyrite dissolution, hydrogen ions release into the fluids, leading to obvious acidification. The acidified solution dissolves carbonate and feldspar minerals. Meanwhile, in the process of mineral dissolution, heavy metals or radioactive elements release as well, e.g., Ba, U, and Sr, which are all primary toxic elements of flowback fracturing fluids. The interaction between shale and fracturing fluid also causes changes in the shale matrix. Comparisons between shale samples before and after experiments clearly show density decrease while porosity increase. In addition, pore types change from ink bottle-shaped thin neck hole dominance to long and narrow plate-shaped hole dominance. Through the theoretical calculation of saturation index and observation by scanning electron microscope, we found that mineral dissolution is accompanied by secondary mineral precipitation, e.g., Fe-(oxy) hydroxide and gypsum. These precipitates, nevertheless, could potentially restrict the migration of metal elements by adsorption or co-precipitation, occlude the pore systems, and finally decrease the recovery of shale oil and gas. Overall, we conclude that mineral compositions and physical properties of the shale are among primary factors controlling fluid-rock reactions. Therefore, mineral composition and textural analysis are critical to fracturing fluid design and important to lowering environmental risks caused by flowback fluids. 

How to cite: Tan, J. and Li, G.: On the shale-fluid reactions occurred in the hydraulic fracturing process of shale gas development: insights from lab simulation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13093, https://doi.org/10.5194/egusphere-egu22-13093, 2022.

EGU22-13103 | Presentations | ERE5.7

Laboratory study to better understand hydraulic fracturing-induced seismicity and fracture propagation 

Lei Li, Jingyu Xie, Jingqiang Tan, Biao Shu, Wen Zhou, Xinpeng Pan, and Jianxin Liu

Unconventional geo-energy resources, such as shale gas and geothermal energy, are supposed to play an essential role in energy transition and carbon neutrality. Currently, hydraulic fracturing is still the dominant stimulation strategy to obtain economic production. Hydraulic fracture (HF) propagation behavior is significant to characterize the reservoir and evaluate the stimulation efficiency. Interpretation of the reservoir fracture growth is challenging due to the coupled effects of geological and engineering conditions. Under controlled conditions, laboratory study can better reveal the physical mechanisms of induced seismicity and HF propagation. We conducted two separate laboratory studies using shale and granite samples, respectively. For the uniaxial loading experiments of shale samples, multifractal method, time-frequency analysis, event location, and micro-CT scanning techniques were utilized to quantitatively characterize acoustic emission events and HFs. The fracturing process could be divided into three stages as the initial stage, the quite stage, and the fracturing stage. For the true triaxial loading experiments of granite samples, the influence of multiple structural planes (SPs) on the HF propagations was studied. The HF geometry displayed four basic patterns when encountering SPs, namely, propagation along the SPs, branching, capture, penetration/non-dilation. The cementing strength and mechanical properties of the SPs influence the HF behaviors significantly. Laboratory fracturing experiments can help provide theoretical and technical guidance for field hydraulic fracturing operations in shale reservoirs and enhanced geothermal systems. Future work will involve a more systematic analysis and comparison between HF propagation behaviors for different rocks under different geological and engineering conditions.

How to cite: Li, L., Xie, J., Tan, J., Shu, B., Zhou, W., Pan, X., and Liu, J.: Laboratory study to better understand hydraulic fracturing-induced seismicity and fracture propagation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13103, https://doi.org/10.5194/egusphere-egu22-13103, 2022.

EGU22-13139 | Presentations | ERE5.7

Experimental investigation on the mechanical properties of shale soaked in supercritical CO₂ / water at dynamic pressures 

Qiao Lyu, Kaixi Wang, Jingqiang Tan, and David Wood

As shale gas exploitation proceeds, reservoir pressure progressively decreases. While using CO2 or water to enhance shale gas recovery, it is important to investigate their effects on the mechanical properties of shale under dynamic pressure conditions. In this study, we have investigated the effects of supercritical CO2 and water immersion on the mechanical properties of shale under different dynamic pressures (pressure change 1: decreasing from 20 MPa to 8 MPa; pressure change 2: decreasing from 42 MPa to 30 MPa). The testing results indicate that, after soaking in supercritical CO2 and water, the uniaxial compressive strength (UCS) of shale is decreased by 51.05% and 58.36% (pressure change 1), and by 35.98% and 36.84% (pressure change 2), respectively. The strength and Young's modulus of shale are decreased more significantly after water immersion compared to supercritical CO2 immersion. Due to the matrix compression effects, the mechanical properties of shale are changed more significantly under lower imbibition pressures. Supercritical CO2 immersion leads to an increase in the Poisson's ratio along with more complex fracture patterns, whereas water immersion results in a slight decrease in the Poisson's ratio associated only with shear fracture formation. The acoustic emission (AE) signals display obvious stage characteristics during the compressional deformation of the samples, and the AE energy is mainly generated in during the unstable crack propagation stage. Supercritical CO2 immersion plays an important role in crack generation, whereas water immersion is dominated by the alteration of the pore structure. Compared with the constant pressure imbibition, the dynamic pressure imbibition changes the microstructure of shale and weakens its mechanical properties more significantly. The results of this study provide a clearer understanding of the effects of CO2 and water on the mechanical properties of shale during exploitation of shale gas.

How to cite: Lyu, Q., Wang, K., Tan, J., and Wood, D.: Experimental investigation on the mechanical properties of shale soaked in supercritical CO₂ / water at dynamic pressures, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13139, https://doi.org/10.5194/egusphere-egu22-13139, 2022.

EGU22-13143 | Presentations | ERE5.7

Mechanical properties of shale following saturation with CO2 and CO2-based fluids: experimental and modeling study 

Bingbin Xie, Qiao Lyu, Jingqiang Tan, and David Wood

Impacts of saturation with CO2 and CO2-based liquids are vital for understanding shale's mechanical properties associated with supercritical-CO2 optimized shale gas extraction and geological capture and storage of CO2 in shale reservoirs. A sequence of triaxial compression tests is performed to examine the impact of subcritical CO2, supercritical CO2, subcritical CO2-water, supercritical CO2-water, subcritical CO2-NaCl, and supercritical CO2-NaCl saturation on shale strength. A statistical damage constitutive model of shale after CO2, CO2-water, and CO2-NaCl saturation is established to describe shale's stress-strain relationships under various immersion conditions.

The laboratory findings indicate that the change of the axial stress, Young's modulus, and axial strain of shale after immersion verifies the physical and chemical reactions that occur between shale and the soaking fluids. Mechanical properties of shale show the greatest variations after CO2-water saturation. The variation in mechanical properties of shale after CO2-NaCl saturation is smaller than those of shale under CO2-water saturation owing to the precipitation of NaCl crystals. Pure CO2 saturation has the smallest influence on shale's mechanical properties among the three types of liquids assessed. CO2 in a supercritical state shows a stronger impact on shale than the subcritical state for the same sort of fluids. Also, following saturation, all the shales display a mixed tensile-shear failure mode. The cohesion force of shale increments following pure CO2 saturation, whereas it diminishes following CO2-water and CO2-NaCl saturation. Decreases in the internal friction angles are observed for all the soaked shales. The anisotropy of shale leads to a slight difference between the actual failure angle and the failure angle measured by the Mohr-Coulomb criterion.

The stress-strain relationship of shale under different confining pressures is effectively described by the Weibull probability distribution and the principle of strain equivalence. This establishes statistical damage constitutive equations of shale under different soaking conditions. The values of key modeling parameters, including F0 and m, are highly dependent on the brittleness and strength of shale associated with various soaking conditions.

How to cite: Xie, B., Lyu, Q., Tan, J., and Wood, D.: Mechanical properties of shale following saturation with CO2 and CO2-based fluids: experimental and modeling study, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13143, https://doi.org/10.5194/egusphere-egu22-13143, 2022.

EGU22-13144 | Presentations | ERE5.7

Pore characteristics and hydraulic properties of shale samples under long-term exposure to hydraulic fracturing fluids 

Chenger Hu, Jingqiang Tan, Qiao Lyu, Jeffrey Dick, and David Wood

Fluids-shale interactions during hydraulic fracturing alters the pore characteristics and hydraulic properties of shale, thus affecting the oil and gas recovery efficiency and the geological storage capacity of shale reservoirs.  Short-term (0-1 month) and long-term (1-12 months) experiments are conducted to investigate the fluids-shale interaction behaviour during fracturing fluid injection and retention periods. The effects of fluids-rock interaction on pore characteristics and hydraulic properties are determined by characterizing the shale's mineralogy, surface morphology, pore structure characteristics, and hydraulic properties before and after the experiments. The experimental results show variability during the fluid injection and retention periods. In the short-term experiments, pyrite dissolution caused a rapid decrease in fluid pH (decreased by 1.7-5.1). In long-term experiments, feldspar and clay mineral dissolution caused a slow increase in fluid pH (increased by 0.5). The dissolution of minerals enlarged the native pores of the shale, thereby increasing the porosity, raising the average pore diameter, and increasing the gas adsorption capacity of the shale (by 14.1%). Measurements of fractal dimension D1 indicate that the pore surfaces become rougher during the short-term experiments, whereas the pore surfaces become smoother during the long-term experiments. The change in pore structure affects the hydraulic properties of the shale. In particular, the absolute permeability of the shale increased (60.0-129.1%), while the pore tortuosity decreased (26.1%-57.8%). However, as the pH rises above 4, substantial gypsum and iron hydroxide precipitation occurs, blocking shale fractures and pores. Such precipitation reduces shale porosity, hydraulic properties, and sorption capacity. On the other hand, lower pH (below 3.5) can inhibit the formation of secondary precipitation. Monitoring pH changes is, therefore, the key to improving oil and gas recovery by enhancing reservoir geological storage capacity following hydraulic fracturing.

How to cite: Hu, C., Tan, J., Lyu, Q., Dick, J., and Wood, D.: Pore characteristics and hydraulic properties of shale samples under long-term exposure to hydraulic fracturing fluids, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13144, https://doi.org/10.5194/egusphere-egu22-13144, 2022.

EGU22-2188 | Presentations | SM2.1

Locating Nearby Explosions in Fürstenfeldbruck, Germany, Combining 8 Rotational Sensors 

Gizem Izgi, Eva P.S. Eibl, Frank Krüger, and Felix Bernauer

The seismic wavefield can only be completely described by the combination of translation, rotation and strain. Direct measurement of rotational motions in combination with the translational motions allow observing the complete seismic ground motion. Portable blueSeis-3A (iXblue) sensors allow to measure 3 components of rotational motions. We co-located Nanometrics Horizon seismometers with blueSeis-3A sensors and measured the full wavefield.

An active source experiment was performed in Fürstenfeldbruck, Germany in November 2019, in order to further investigate the performance of multiple rotational instruments in combination with seismometers. Within the scope of the experiment 5 explosions took place. For the first two explosions, all 8 rotational sensors were located inside of a bunker while for the rest of explosions, 4 sensors each were located at 2 different sites of the field. One group was co-located with translational seismometers. This is the first time the recordings of 8 rotational sensors are combined for event analysis and location. We calculate and intersect the back azimuths and derive phase velocities of the five explosions.

We discuss the reliability of the data recorded by the rotational sensors for further investigations in other environments.

How to cite: Izgi, G., Eibl, E. P. S., Krüger, F., and Bernauer, F.: Locating Nearby Explosions in Fürstenfeldbruck, Germany, Combining 8 Rotational Sensors, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2188, https://doi.org/10.5194/egusphere-egu22-2188, 2022.

EGU22-2455 | Presentations | SM2.1

Understanding surface-wave modal content for high-resolution imaging with ocean-bottom distributed acoustic sensing 

Zack Spica, Loïc Viens, Mathieu Perton, Kiwamu Nishida, Takeshi Akuhara, Masanao Shinohara, and Tomoaki Yamada

Ocean Bottom Distributed Acoustic Sensing (OBDAS) is emerging as a new measurement method providing dense, high-fidelity, and broadband seismic observations from fiber-optic cables. Here, we use ~40 km of a telecommunication cable located offshore the Sanriku region, Japan, and apply ambient seismic field interferometry to obtain an extended 2-D high-resolution shear-wave velocity model. In some regions of the array, we observe and invert more than 20 higher modes and show that the accuracy of the retrieval of some modes strongly depends on the processing steps applied to the data. In addition, numerical simulations suggest that the number of modes that can be retrieved is proportional to the local velocity gradient under the cable. Regions with shallow low-velocity layers tend to contain more modes than those located in steep bathymetry areas, where sediments accumulate less. Finally, we can resolve sharp horizontal velocity contrasts under the cable suggesting the presence of faults and other sedimentary features. Our results provide new constraints on the shallow submarine structure in the area and further demonstrate the potential of OBDAS for offshore geophysical prospecting.

How to cite: Spica, Z., Viens, L., Perton, M., Nishida, K., Akuhara, T., Shinohara, M., and Yamada, T.: Understanding surface-wave modal content for high-resolution imaging with ocean-bottom distributed acoustic sensing, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2455, https://doi.org/10.5194/egusphere-egu22-2455, 2022.

EGU22-2563 | Presentations | SM2.1

On the Multi-component Information of DAS for Near-Surface Seismic: A Pilot Field Experiment in the Groningen Area 

Musab Al Hasani, Guy Drijkoningen, and Kees Wapenaar

In a surface-seismic setting, Distributed Acoustic Sensing (DAS) is still not a widely adopted method for near-surface characterisation, especially for reflection seismic imaging, despite the dense spatial sampling it provides over long distances. This is mainly due to the decreased broadside sensitivity that DAS suffers from when buried horizontally in the ground (that is when the upgoing wavefield (e.g. reflected wavefield) is perpendicular to the optical fibre). This is unlike borehole settings (e.g. zero-offset Vertical Seismic Profiling), where DAS has been widely adopted for many monitoring applications. Advancements in the field, like shaping the fibre to a helix, commonly known as helically wound fibre, allow better sensitivity for the reflections.

The promise of spatially dense seismic data over long distances is an attractive prospect for retrieving the local variations of near-surface properties. This is particularly valuable for areas impacted by induced seismicity, as is the case in the Groningen Province in the north of The Netherlands,  where near-surface properties, mostly composed of clays and peats, play an essential role on the amount of damage on the very near-surface and the structures built on it. Installing fibre-optic cables for passive and active measurements is valuable in this situation. We installed multiple cables containing different fibre configurations of straight and helically wound fibres, buried in a 2-m deep trench. The combination of the different fibre configurations allows us to obtain multi-component information. We observe differences in the amplitude and phase information, suggesting that these differences can be used for separating the different components of the wave motion. We also see that using enhanced backscatter fibres, reflection images can be obtained for the helically wound fibre as well as the straight fibre, despite the decreased broadside sensitivity for the latter.

How to cite: Al Hasani, M., Drijkoningen, G., and Wapenaar, K.: On the Multi-component Information of DAS for Near-Surface Seismic: A Pilot Field Experiment in the Groningen Area, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2563, https://doi.org/10.5194/egusphere-egu22-2563, 2022.

EGU22-3404 | Presentations | SM2.1 | Highlight

Fibre-optic observation of volcanic tremor through floating ice sheet resonance 

Andreas Fichtner, Sara Klaasen, Sölvi Thrastarson, Yesim Cubuk-Sabuncu, Patrick Paitz, and Kristin Jonsdottir

We report on the indirect observation of low-frequency tremor at Grimsvötn, Iceland, via resonance of an ice sheet, floating atop a volcanically heated subglacial lake.

Entirely covered by Europe’s largest glacier, Vatnajökull, Grimsvötn is among Iceland’s largest and most active volcanoes. In addition to flood hazards, ash clouds pose a threat to settlements and air traffic, as direct interactions between magma and meltwater cause Grímsvötn to erupt explosively. To study the seismicity and structure of Grimsvötn in detail, we deployed a 12.5 km long fibre-optic cable around and inside the caldera, which we used for Distributed Acoustic Sensing (DAS) measurements in May 2021.

The experiment revealed a previously unknown level of seismicity, with nearly 2’000 earthquake detections in less than one month. Furthermore, the cable segment within the caldera recorded continuous and nearly monochromatic oscillations at 0.23 Hz. This corresponds to the expected fundamental-mode resonance frequency of flexural waves within the floating ice sheet, which effectively acts as a damped harmonic oscillator with Q around 15.

In spite of the ice sheet being affected by ambient noise at slightly lower frequencies, the resonance amplitude does not generally correlate with the level of ambient noise throughout southern Iceland. It follows that an additional and spatially localised forcing term is required to explain the observations. A linear inversion reveals that the forcing acts continuously, with periods of higher or lower activity alternating over time scales of a few days.

A plausible explanation for the additional resonance forcing is volcanic tremor, most likely related to geothermal activity, that shows surface expressions in the form of cauldrons and fumaroles along the caldera rim. Being largely below the instrument noise at channels outside the caldera, the ice sheet resonance acts as a magnifying glass that increases tremor amplitudes to an observable level, thereby providing a new and unconventional form of seismic volcano monitoring.

How to cite: Fichtner, A., Klaasen, S., Thrastarson, S., Cubuk-Sabuncu, Y., Paitz, P., and Jonsdottir, K.: Fibre-optic observation of volcanic tremor through floating ice sheet resonance, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3404, https://doi.org/10.5194/egusphere-egu22-3404, 2022.

EGU22-3728 | Presentations | SM2.1

Detecting earthen dam defects using seismic interferometry monitoring on Distributed Acoustic Sensing data 

Aurelien Mordret, Anna Stork, Sam Johansson, Anais Lavoue, Sophie Beaupretre, Romeo Courbis, Ari David, and Richard Lynch

Earthen dams and embankments are prone to internal erosion, their most significant source of failure. Standard monitoring techniques often measure erosion effects when they appear at the surface, reducing the potential response time to address the problem before failure. Through their integrative sensitivity along their propagation, seismic signals are well suited to assess mechanical changes in the bulk of a dam. Moreover, seismic velocities are strongly sensitive to porosity, pore pressure, and water saturation, physical properties that vary the most for internal erosion. Here, we used fiber optics and a Distributed Acoustic Sensing (DAS) array installed on an experimental dam with built-in defects to record the ambient seismic wavefield for one month while the dam reservoir is gradually filled up. The position and nature of the dam defects are unknown to us, to allow an actual blind-detection experiment. We computed cross-correlations between equidistant channels along the dam every 15 minutes and monitored the relative seismic velocity changes at each location for the whole month. The results show a strong correlation of the velocity changes with the water level in the reservoir at all locations along the dam. We also observe systematic deviations from the average velocity change trend. We interpret these anomalies as the effects of the built-in defects placed at different positions in the bulk of the dam. The careful analysis of the residual velocity changes allows us to hypothesize on the position and nature of the defects. 

How to cite: Mordret, A., Stork, A., Johansson, S., Lavoue, A., Beaupretre, S., Courbis, R., David, A., and Lynch, R.: Detecting earthen dam defects using seismic interferometry monitoring on Distributed Acoustic Sensing data, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3728, https://doi.org/10.5194/egusphere-egu22-3728, 2022.

EGU22-3729 | Presentations | SM2.1

The Potential of DAS on Underwater Suspended Cables for Oceanic Current Monitoring and Failure Assessment of Fiber Optic Cables 

Daniel Mata, Jean-Paul Ampuero, Diego Mercerat, Diane Rivet, and Anthony Sladen

Distributed Acoustic Sensing (DAS) enables the use of existing underwater telecommunication cables as multi-sensor arrays. The great majority of underwater telecommunication cables are deployed from the water surface and the coupling between the cable and the seafloor is not fully controlled. This implies that there exists many poorly coupled cable segments less useful for seismological research. In particular, underwater cables include segments that are suspended in the water column across seafloor valleys or other bathymetry irregularities. However, it might be possible to use DAS along the suspended sections of underwater telecommunication cables for other purposes. A first one investigated here is the ability to monitor deep-ocean currents. It is common to observe that some particular sections of a cable oscillate with great amplitudes. These oscillations are commonly interpreted as due to vortex shedding induced by the currents. We investigate this hypothesis by estimating the oceanic current speeds from vortex frequencies measured in two underwater fiber optic cables located at Methoni, Greece, and another in Toulon, France. Our results in Greece are in agreement with in-situ historical measurements of seafloor currents while our estimations in Toulon are compatible with synchronous measurements of a nearby current meter. These different measurements therefore point to the possibility to exploit DAS measurements as a tool to monitor the activity of seafloor currents. A second possible application of DAS is to estimate how the cable is coupled to the seafloor, even in the absence of the strong oscillations associated to vortex shedding. For that, we have analyzed the spectral signature of the different cables. Some sections feature fundamental frequencies as expected from a theoretical model of in-plane vibration of hanging cables. By analyzing how the fundamental frequencies change along the cable, we are potentially inferring the contact points of the cable with the seafloor, which will promote fatigue of the cable and potential failure. This mapping of the coupling characteristics of the cable with the seafloor could also be useful to better interpret other DAS signals.

How to cite: Mata, D., Ampuero, J.-P., Mercerat, D., Rivet, D., and Sladen, A.: The Potential of DAS on Underwater Suspended Cables for Oceanic Current Monitoring and Failure Assessment of Fiber Optic Cables, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3729, https://doi.org/10.5194/egusphere-egu22-3729, 2022.

EGU22-4014 | Presentations | SM2.1

Near-field observations of snow-avalanches propagating over a fiber-optic array 

Patrick Paitz, Pascal Edme, Andreas Fichtner, Nadja Lindner, Betty Sovilla, and Fabian Walter

We present and evaluate array processing techniques and algorithms for the characterization of snow avalanche signals recorded with Distributed Acoustic Sensing (DAS).

Avalanche observations rely on comprehensive measurements of sudden and rapid snow mass movement that is hard to predict. Conventional avalanche sensors are limited to observations on or above the surface. Recently, seismic sensors have increased in their popularity for avalanche monitoring and characterization due to their avalanche detection and characterization capabilities. To date, however, seismic instrumentation in avalanche terrain is sparse, thereby limiting the spatial resolution significantly.

As an addition to conventional seismic instrumentation, we propose DAS to measure avalanche-induced ground motion. DAS is a technology using backscattered light along a fiber-optic cable to measure strain (-rate) along the fiber with unprecedented spatial and temporal resolution - in our example with 2 m spatial sampling and a sampling rate of 1kHz.

We analyze DAS data recorded during winter 2020/2021 at the Valleé de la Sionne avalanche test site in the Swiss Alps, utilizing an existing 700 m long fiber-optic cable. Our observations include avalanches propagating on top of the buried cable, delivering near-field observations of avalanche-ground interactions. After analyzing the properties of near-field avalanche DAS recordings, we discuss and evaluate algorithms for (1) automatic avalanche detection, (2) avalanche surge propagation speed evaluation and (3) subsurface property estimation.

Our analysis highlights the complexity of near-field DAS data, as well as the suitability of DAS-based monitoring of avalanches and other hazardous granular flows. Moreover, the clear detectability of avalanche signals using existing fiber-optic infrastructure of telecommunication networks opens the opportunity for unrivalled warning capabilities in Alpine environments.

How to cite: Paitz, P., Edme, P., Fichtner, A., Lindner, N., Sovilla, B., and Walter, F.: Near-field observations of snow-avalanches propagating over a fiber-optic array, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4014, https://doi.org/10.5194/egusphere-egu22-4014, 2022.

EGU22-4478 | Presentations | SM2.1

Non-linear ground response triggered by volcanic explosions at Etna Volcano, Italy 

Philippe Jousset, Lucile Costes, Gilda Currenti, Benjamin Schwarz, Rosalba Napoli, Sergio Diaz, and Charlotte Krawczyk

Volcanic explosions produce energy that propagates both in the subsurface as seismic waves and in the atmosphere as acoustic waves. We analyse thousands of explosions which occurred at different craters at Etna volcano (Italy) in 2018 and 2019. We recorded signals from infrasound sensors, geophones (GPH), broadband seismometers (BB) and Distributed Acoustic Sensing (DAS) with fibre optic cable. The instruments were deployed at Piano delle Concazze at about 2 to 2.5 km from the active craters, within (or onto) a ~300,000 m2 scoria layer deposited by recent volcanic eruptions. The DAS interrogator was setup inside the Pizzi Deneri Volcanic Observatory (~2800 m elevation). Infrasonic explosion records span over a large range of pressure amplitudes with the largest one reaching 130 Pa (peak to peak), with an energy of ca. 2.5x1011 J. In the DAS and the BB records, we find a 4-s long seismic “low frequency” signal (1-2 Hz) corresponding to the seismic waves, followed by a 2-s long “high-frequency” signal (16-21 Hz), induced by the infrasound pressure pulse. The infrasound sensors contain a 1-2 Hz infrasound pulse, but surprisingly no high frequency signal. At locations where the scoria layer is very thin or even non-existent, this high frequency signal is absent from both DAS strain-rate records and BB/GPH velocity seismograms. These observations suggest that the scoria layer is excited by the infrasound pressure pulse, leading to the resonance of lose material above more competent substratum. We relate the high frequency resonance to the layer thickness. Multichannel Analysis of Surface Wave from jumps performed along the fibre optic cable provide the structure of the subsurface, and confirm thicknesses derived from the explosion analysis. As not all captured explosions led to the observation of these high frequency resonance, we systematically analyze the amplitudes of the incident pressure wave versus the recorded strain and find a non-linear relationship between the two. This non-linear behaviour is likely to be found at other explosive volcanoes. Furthermore, our observations suggest it might also be triggered by other atmospheric pressure sources, like thunderstorms. This analysis can lead to a better understanding of acoustic-to-seismic ground coupling and near-surface rock response from natural, but also anthropogenic sources, such as fireworks and gas explosions.

How to cite: Jousset, P., Costes, L., Currenti, G., Schwarz, B., Napoli, R., Diaz, S., and Krawczyk, C.: Non-linear ground response triggered by volcanic explosions at Etna Volcano, Italy, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4478, https://doi.org/10.5194/egusphere-egu22-4478, 2022.

EGU22-4583 | Presentations | SM2.1

Dynamic weakening in carbonate-built seismic faults: insights from laboratory experiments with fast and ultra-localized temperature measurements 

Stefano Aretusini, Arantzazu Nuñez Cascajero, Chiara Cornelio, Xabier Barrero Echevarria, Elena Spagnuolo, Alberto Tapetado, Carmen Vazquez, Massimo Cocco, and Giulio Di Toro

During earthquakes, seismic slip along faults is localized in < 1 cm-thick principal slipping zones. In such thin slipping zones, frictional heating induces a temperature increase which activates deformation processes and chemical reactions resulting in dramatic decrease of the fault strength (i.e., enhanced dynamic weakening) and, in a negative feedback loop, in the decrease of the frictional heating itself.

In the laboratory, temperature measurements in slipping zones are extremely challenging, especially at the fast slip rates and large slip displacements typical of natural earthquakes. Recently, we measured the temperature evolution in the slipping zone of simulated earthquakes at high acquisition rates (∼ kHz) and spatial resolutions (<< 1 mm2). To this end, we used optical fibres, which convey IR radiation from the hot rubbing surfaces to a two color pyrometer, equipped with photodetectors which convert the radiation into electric signals. The measured signals were calibrated into temperature and then synchronized with the mechanical data (e.g., slip rate, friction coefficient, shear stress) to relate the dynamic fault strength to the temperature evolution and eventually constrain the deformation processes and associated chemical reactions activated during seismic slip.

Here, we reproduce earthquake slip via rotary shear experiments performed on solid cylinders (= bare rock surfaces) and on gouge layers both made of 99.9% calcite. The applied effective normal stress is 20 MPa. Bare rock surfaces are slid for 20 m with a trapezoidal velocity function with a target slip rate of 6 m/s. Instead, the gouge layers are sheared imposing a trapezoidal (1 m/s target slip rate for 1 m displacement) and Yoffe (3.5 m/s peak slip rate, and 1.5 m displacement) velocity function. The temperature measured within the slipping zone, which in some experiments increases up to 1000 °C after few milliseconds from slip initiation, allow us to investigate the deformation mechanisms responsible for fault dynamic weakening over temporal (milliseconds) and spatial (contact areas << 1 mm2) scales which are impossible to detect with traditional techniques (i.e., thermocouples or thermal cameras).

Importantly, thanks to FE numerical simulations, these in-situ temperature measurements allow us to quantify the partitioning of the dissipated energy and power between frictional heating (temperature increase) and wear processes (e.g., grain comminution), to probe the effectiveness of other energy sinks (e.g., endothermic reactions, phase changes) that would buffer the temperature increase, and to determine the role of strain localization in controlling the temperature increase. The generalization of our experimental data and observations will contribute to shed light on the mechanics of carbonate-hosted earthquakes, a main hazard in the Mediterranean and other areas worldwide.

How to cite: Aretusini, S., Nuñez Cascajero, A., Cornelio, C., Barrero Echevarria, X., Spagnuolo, E., Tapetado, A., Vazquez, C., Cocco, M., and Di Toro, G.: Dynamic weakening in carbonate-built seismic faults: insights from laboratory experiments with fast and ultra-localized temperature measurements, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4583, https://doi.org/10.5194/egusphere-egu22-4583, 2022.

EGU22-4963 | Presentations | SM2.1

A real-time classification method for pipeline monitoring combining Distributed Acoustic Sensing and Distributed Temperature and Strain Sensing 

Camille Huynh, Camille Jestin, Clément Hibert, Jean-Philippe Malet, Vincent Lanticq, and Pierre Clément

Distributed Fiber Optic Systems (DFOSs) refer to an ensemble of innovative technology that turns an optical fiber into a vast network of hundreds to thousands equally spaced sensors. According to the nature of the sensor, one can be sensitive to acoustic vibration (Distributed Acoustic Sensing, DAS) or to strain and temperature variation (Distributed Temperature and Strain Sensing, DTSS). DAS systems are well suited to detect short-term events in contrast to DTSS systems, which are intended to prevent long-term events. A combination of these two systems appears to be a good way to prevent against most possible events that can appear along an infrastructure. Furthermore, DFOS systems allow the interrogation of long profiles with very dense spatial and temporal sampling. Handling such amounts of data then appears as a challenge when trying to identify a threat along the structure. Machine learning solutions then proves their relevance for robust, fast and efficient acoustical event classification.

The goal of our study is to develop a method to handle, in real time, acquired data from these two DFOSs, classify them according to the nature of their origin and trigger an alarm if required. We mainly focus on major threats that jeopardize the integrity of pipelines. Our database contains leaks, landslides, and third-party intrusion (footsteps, excavations, drillings, etc.) simulated and measured at FEBUS Optics test bench in South-West France. Water and air leaks were simulated using electrovalves of several diameters (1mm, 3mm and 5mm), and landslides with a plate whose inclination was controlled by 4 cylinders. These data were acquired under controlled conditions in a small-scale model of pipeline (around 20m long) along different fiber optic cables installed along the structure.

Our method relies on several tools. A Machine Learning algorithm called Random Forest is used to pre-classify the DAS signal. Our implementation of this algorithm works in flow for a real time event identification. For DTSS signal, a simple threshold is used to detect if a strain or temperature variation occurs. Both results are then gathered and analyzed using a decisional table to return a classification result. According to the potential threat represented by its identified class, the event is considered as dangerous or not. Using this method, we obtain good results with a good classification rate (threat/non-threat) of 93%, compared to 87% if the DAS is used without the DTSS. We have noticed that the combination of both devices enables a better classification, especially for landslides hard to detect with the DAS. This combination enables to dramatically reduce the part of undetected threats from 16% to 4%.

How to cite: Huynh, C., Jestin, C., Hibert, C., Malet, J.-P., Lanticq, V., and Clément, P.: A real-time classification method for pipeline monitoring combining Distributed Acoustic Sensing and Distributed Temperature and Strain Sensing, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4963, https://doi.org/10.5194/egusphere-egu22-4963, 2022.

EGU22-5327 | Presentations | SM2.1

HDAS (High-Fidelity Distributed Acoustic Sensing) as a monitoring tool during 2021 Cumbre Vieja eruption 

José Barrancos, Luca D'Auria, Germán Padilla, Javier Preciado-Garbayo, and Nemesio M. Pérez

La Palma is the second youngest and westernmost among Canary Island. Cumbre Vieja volcano formed in the last stage of the geological evolution of the island and had suffered eight volcanic eruptions over the previous 500 years. In 2017, two remarkable seismic swarms interrupted a seismic silence from the last eruption (Teneguía, 1971). Since then, nine additional seismic swarms have occurred at Cumbre Vieja volcano. On September 11th, 2021, seismic activity began to increase, and the depths of the earthquakes showed an upward migration. Finally, on September 19th, the eruption started after just a week of precursors.

During recent years, the seismic activity has been recorded by Red Sísmica Canaria (C7), composed of 6 seismic broadband stations, which was reinforced during the eruption by five additional broadband stations, three accelerometers and a seismic array consisting of 10 broadband stations.

Furthermore, as a result of a collaboration between INVOLCAN, ITER, CANALINK and Aragón Photonics Labs, it was possible to install, on October 19th, an HDAS (High-fidelity Distributed Acoustic Sensor). The HDAS was installed about 10 km from the eruptive vent and was connected to a submarine fibre optic cable directed toward Tenerife Island. Since then, the HDAS has been recording seismic with a temporal sampling rate of 100 Hz and a spatial sampling rate of 10m for a total length of 50 km using Raman Amplification. For more than two months, in addition to the intense volcanic tremor, the HDAS recorded thousands of earthquakes as well as regional and teleseismic events. On December 13th, 2021, after an intense paroxysmal phase with an eruptive column that reached 8 km in height, the volcanic tremor quickly decreased, and the eruption suddenly stopped. Only a weak volcano-tectonic seismicity and small amplitude long-period events were recorded in the next month.

This valuable dataset will provide a milestone for the development of techniques aimed at using DAS as a real-time volcano monitoring tool and studying the internal structure of active volcanoes.

How to cite: Barrancos, J., D'Auria, L., Padilla, G., Preciado-Garbayo, J., and Pérez, N. M.: HDAS (High-Fidelity Distributed Acoustic Sensing) as a monitoring tool during 2021 Cumbre Vieja eruption, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5327, https://doi.org/10.5194/egusphere-egu22-5327, 2022.

EGU22-5551 | Presentations | SM2.1

A showcase pilot of seismic campaign using Distributed Acoustic Sensing solutions 

Camille Jestin, Christophe Maisons, Aurélien Chérubini, Laure Duboeuf, and Jean-Claude Puech

Distributed Acoustic Sensing (DAS) is a rapidly evolving technology that can turn a fibre optic cable into thousands of acoustic sensors. In this study, we propose to present a seismic survey conducted as a business showcase relying on a collaborative work supported by five partners: FEBUS Optics, RealTimeSeismic (RTS), Gallego Technic Geophysics (GTG), Petro LS and Well-SENSE. The project was carried out at a deep solution mining site developed for salt production, operated by KEMONE, and located nearby Montpellier (South of France).

The seismic campaign was based on two different cable deployments.

On the first hand, a Vertical Seismic Profile survey was conducted on borehole seismic measurements using two different fibre optic cables deployed in a 1800m deep vertical well. The first set of tests was performed along a Petro LS wireline cable including optical fibres. This deployment corresponds to a conventional wireline operation. The second set of data has been acquired along a FibreLine Intervention system (FLI) developed by WellSENSE. The deployment of the FLI system relies on the unspooling a bare optical fibre using a probe along a wellbore. This solution is single-use and sacrificial and can be left in the well at the end of the survey.

On another hand, a short 400m-surface 2D profile has been achieved along both a fibre optic cable and a set of STRYDE nodes deployed by GTG.

Fibre optic cables have been connected to FEBUS DAS interrogator to collect distributed acoustic measurements.  The seismic tests, performed in collaboration with GTG, have been achieved with basic “weight drops” (1T falling from 4m) for the checkshot surveys and with an "IVI Mark 4" 44,000-pound seismic vibrator for VSP shots at offset from wellhead reaching 865m. Acquired data have been analysed by RTS.

This work will describe the survey, present the results, and discuss the learnings in two ways:  the optimisation of acquisition setups and processing parameters to obtain the best exploitable results and seismic surveys perspectives and challenges using DAS technology.

How to cite: Jestin, C., Maisons, C., Chérubini, A., Duboeuf, L., and Puech, J.-C.: A showcase pilot of seismic campaign using Distributed Acoustic Sensing solutions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5551, https://doi.org/10.5194/egusphere-egu22-5551, 2022.

EGU22-5743 | Presentations | SM2.1

Making sense of urban DAS data with clustering of coherence-based array features 

Julius Grimm and Piero Poli

Seismic noise monitoring in urban areas can yield valuable information about near-surface structures and noise sources like traffic activity. Distributed Acoustic Sensing (DAS) is ideal for this task due to its dense spatial resolution and the abundance of existing fiber-optic cables below cities.
A 15 km long dark fiber below the city of Grenoble was transformed into a dense seismic antenna by connecting it to a Febus A1-R interrogator unit. The DAS system acquired data continuosly for 11 days with a sampling frequency of 250 Hz and a channel spacing of 19.2 m, resulting in a total of 782 channels. The cable runs through the entirety of the city, crossing below streets, tram tracks and a river. Various noise sources are visible on the raw strain-rate data. A local earthquake (1.3 MLv) was also recorded during the acquisition period.
To characterize the wavefield, the data is divided into smaller sub-windows and coherence matrices at different frequency bands are computed for each sub-window. Clustering is then performed directly on the covariance matrices, with the goal of identifying repeating sub-structures in the covariance matrices (e.g. localized repeating noise sources). Finding underlying patterns in the complex dataset helps us to better understand the spatio-temporal distribution of the occurring signals.

How to cite: Grimm, J. and Poli, P.: Making sense of urban DAS data with clustering of coherence-based array features, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5743, https://doi.org/10.5194/egusphere-egu22-5743, 2022.

EGU22-5952 | Presentations | SM2.1

Strombolian seismic activity characterisation using fibre-optic cable and distributed acoustic sensing 

Jean-Philippe Metaxian, Francesco Biagioli, Maurizio Ripepe, Eléonore Stutzmann, Pascal Bernard, Roberto Longo, Marie-Paule Bouin, and Corentin Caudron

Stromboli is an open-conduit volcano characterized by mild intermittent explosive activity that produces jets of gas and incandescent blocks. Explosions occur at a typical rate of 3-10 events per hour, VLP signals have dominant periods between 2 and 30 seconds. Seismic activity is also characterized by less energy short-period volcanic tremor related to the continuous out-bursting of small gas bubbles in the upper part of the magmatic column. The high rate of activity as well as the broadband frequency contents of emitted signals make Stromboli volcano an ideal site for testing new techniques of fibre-optic sensing.

In September 2020, approximately 1 km of fiber-optic cable was deployed on the Northeast flank of Stromboli volcano, together with several seismometers, to record the seismic signals radiated by the persistent Strombolian activity via both DAS and inertial-seismometers, and to compare their records.

The cable was buried manually about 30 cm deep over a relatively linear path at first and in a triangle-shaped array with 30-meters-long sides in the highest part of the deployment. The strain rate was recorded using a DAS interrogator Febus A1-R with a sampling frequency of 2000 Hz, a spatial interval of 2.4 m and a gauge length of 5m. Data were re-sampled at 200 Hz. A network of 22 nodes SmartSolo IGU-16HR 3C geophones (5 Hz) has been distributed over the fibre path. A Guralp digitizer equipped with a CMG CMG-40T 30 sec seismometer and an infrasound sensor were placed in the upper part of the path. The geolocation of the cable was obtained by performing kinematic GPS measurements with 2 Leica GR25 receivers. All equipment recorded simultaneously several hundreds of explosion quakes between September 20 and 23.

Data analysis provided the following main results:

  • DAS interrogator clearly recorded the numerous explosion-quakes which occurred during the experiment, as well as lower amplitude tremor and LP events.
  • DAS spectrum exhibits a lower resolution at long periods with a cut-off frequency of approximately 3 Hz.
  • VLP seismic events generated by Strombolian activity are identified only at a few DAS channels belonging to a specific portion of the path, which seems affected by local amplification. At these channels, they display waveforms similar to those sensed by the Güralp CMG-40T.
  • Comparison of DAS strain waveform to particle velocity recorded by co-located seismometers shows a perfect match in phase and a good agreement in amplitude.
  • Beamforming methods have been applied to nodes data located on the upper triangle and to strain rate data, both in the 3-5 Hz frequency band. Slightly different back-azimuths were obtained, values estimated via DAS point more to the southwest with respect to the crater area. Apparent velocities obtained with DAS recordings have lower values compared to those obtained with nodes.

How to cite: Metaxian, J.-P., Biagioli, F., Ripepe, M., Stutzmann, E., Bernard, P., Longo, R., Bouin, M.-P., and Caudron, C.: Strombolian seismic activity characterisation using fibre-optic cable and distributed acoustic sensing, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5952, https://doi.org/10.5194/egusphere-egu22-5952, 2022.

EGU22-6580 | Presentations | SM2.1

Quantifying microseismic noise generation from coastal reflection of gravity waves using DAS 

Gauthier Guerin, Diane Rivet, Martijn van den Ende, Eléonore Stutzmann, Anthony Sladen, and Jean-Paul Ampuero

Secondary microseisms are the most energetic noise in continuous seismometer recordings, and they are generated by interactions between ocean waves. Coastal reflections of ocean waves leading to coastal microseismic sources are hard to estimate in various global numerical wave models, and independent quantification of these coastal sources through direct measurements can therefore greatly improve these models. Here, we exploit a 40 km long submarine optical fiber cable located offshore Toulon, France using Distributed Acoustic Sensing (DAS). We record both the amplitude and frequency of ocean gravity waves, as well as secondary microseisms caused by the interaction of gravity waves incident and reflected from the coast. By leveraging the spatially distributed nature of DAS measurements, additional fundamental information are recovered such as the velocity and azimuth of the waves. On average, 30\% of the gravity waves are reflected at the shore and lead to the generation of local secondary microseisms that manifest as Scholte waves. These local sources can give way to other sources depending on the characteristics of the swell, such as its azimuth or its strength. These sources represent the most energetic contribution to the secondary microseism recorded along the optical fiber, as well as on an onshore broadband station. Furthermore, we estimate the coastal reflection coefficient R$^2$ to be constant at around 0.07 for our 5-day time series. The use of DAS in an underwater environment provides a wealth of information on coastal reflection sources, reflection of gravity waves and new constraints for numerical models of microseismic noise.

How to cite: Guerin, G., Rivet, D., van den Ende, M., Stutzmann, E., Sladen, A., and Ampuero, J.-P.: Quantifying microseismic noise generation from coastal reflection of gravity waves using DAS, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6580, https://doi.org/10.5194/egusphere-egu22-6580, 2022.

EGU22-6976 | Presentations | SM2.1

Comparison between Distributed Acoustic Sensing (DAS) and strain meter measurements at the Black Forest Observatory 

Jérôme Azzola, Nasim Karamzadeh Toularoud, Emmanuel Gaucher, Thomas Forbriger, Rudolf Widmer-Schnidrig, Felix Bögelspacher, Michael Frietsch, and Andeas Rietbrock

We present an original DAS measurement station, equipped with the Febus A1-R interrogator, which has been deployed at the Black Forest Observatory (Schiltach, Germany). The objective of this deployment is twofold. The first is to test the deployed fibre optic cables and to better characterise the recorded signals. The second is to define standards for the processing of these DAS measurements, with a view to using the equipment for passive seismic monitoring in the INSIDE project (supported by the German Federal Ministry for Economic Affairs and Energy, BMWi).

Testing sensors involving new acquisition technologies, such as instruments based on Distributed Fiber Optic Sensing (DFOS), is part of the observatory's goals, in order to assess, to maintain and to improve signal quality. Interestingly, reference geophysical instruments are also deployed on a permanent basis in this low seismic-noise environment. Our analyses thus benefit from the records of the observatory's measuring instruments, in particular a set of three strain meters recording along various azimuths. This configuration enables a unique comparison between strain meter and DAS measurements. In addition, an STS-2 seismometer (part of German Regional Seismic Network, GRSN) allows for additional comparisons.

These instruments provide a basis for a comparative analysis between the DAS records and the measurements of well-calibrated sensing devices (STS-2 sensor, strain meter array). Such a comparison is indeed essential to physically understand the measurements provided by the Febus A1-R interrogator and to characterise the coupling between the ground and the fiber, in various deployment configurations.

We present the experiment where we investigate several Fiber Optic Cable layouts, with currently our most successful setup involving loading a dedicated fiber with sandbags. We discuss different processing approaches, resulting in a considerable improvement of the fit between DAS and strain array acquisitions. The presented comparative analysis is based on the recordings of different earthquakes, including regional and teleseismic events.

How to cite: Azzola, J., Toularoud, N. K., Gaucher, E., Forbriger, T., Widmer-Schnidrig, R., Bögelspacher, F., Frietsch, M., and Rietbrock, A.: Comparison between Distributed Acoustic Sensing (DAS) and strain meter measurements at the Black Forest Observatory, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6976, https://doi.org/10.5194/egusphere-egu22-6976, 2022.

EGU22-6984 | Presentations | SM2.1

Array signal processing on distributed acoustic sensing data: directivity effects in slowness space 

Sven Peter Näsholm, Kamran Iranpour, Andreas Wuestefeld, Ben Dando, Alan Baird, and Volker Oye

Distributed Acoustic Sensing (DAS) involves the transmission of laser pulses along a fiber-optic cable. These pulses are backscattered at fiber inhomogeneities and again detected by the same interrogator unit that emits the pulses. Elastic deformation along the fiber causes phase shifts in the backscattered laser pulses which are converted to spatially averaged strain measurements, typically at regular fiber intervals.

DAS systems provide the potential to employ array processing algorithms. However, there are certain differences between DAS and conventional sensors. The current paper is focused on taking these differences into account. While seismic sensors typically record the directional particle displacement, velocity, or acceleration, the DAS axial strain is inherently proportional to the spatial gradient of the axial cable displacement. DAS is therefore insensitive to broadside displacement, e.g., broadside P-waves. In classical delay-and-sum beamforming, the array response function is the far-field response on a horizontal slowness (or wavenumber) grid. However, for geometrically non-linear DAS layouts, the angle between wavefront and cable varies, requiring the analysis of a steered response that varies with the direction of arrival. This contrasts with the traditional array response function which is given in terms of slowness difference between arrival and steering.

This paper provides a framework for DAS steered response estimation accounting also for cable directivity and gauge-length averaging – hereby demonstrating the applicability of DAS in array seismology and to assess DAS design aspects. It bridges a gap between DAS and array theory frameworks and communities, facilitating increased employment of DAS as a seismic array.

How to cite: Näsholm, S. P., Iranpour, K., Wuestefeld, A., Dando, B., Baird, A., and Oye, V.: Array signal processing on distributed acoustic sensing data: directivity effects in slowness space, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6984, https://doi.org/10.5194/egusphere-egu22-6984, 2022.

EGU22-7153 | Presentations | SM2.1

MEGLIO: an experiment to record seismic waves on a commercial fiber optic cable through interferometry measures with an ultra stable laser. 

Andre Herrero, Davide Calonico, Francesco Piccolo, Francesco Carpentieri, Aladino Govoni, Lucia Margheriti, Maurizio Vassallo, Rita di Giovambattista, Salvatore Stramondo, Cecilia Clivati, Roberto Concas, Simone Donadello, Fabio Simone Priuli, Filippo Orio, and Andrea Romualdi

The experiment MEGLIO follows the seminal work of Marra et al. (2018) where the authors demonstrate the possibility to observe seismic waves on fiber optic cables over large distances. The measure was based on an interferometric technique using an ultra stable laser. In theory, this active measurement technique is compatible with a commercial operation on a fiber, i.e. the fiber does not need to be dark. In 2019, Open Fiber, the largest optic fiber infrastructure provider in Italy, has decided to test this new technology on its own commercial network on land.

A team of experts in the different fields has been gathered to achieve this goal : besides Open Fiber, Metallurgica Bresciana; INRiM, which initially developed the technique, for their expertise on laser and sensors; Bain & Company for the analysis and the processing of the data; INGV for the expertise in the seismology field and for the validation of the observations.

The first year has been dedicated to developing the sensors. In the meantime, a buried optic cable has been chosen in function of its length and the seismicity nearby. The best candidate was the fiber connecting the towns of Ascoli Piceno (Marche, Italy) and Teramo (Abruzzo, Italy) for a length of around 30 km. Although  this technique allows using cable lengths larger than 5.000 km, for this first test we have decided to keep the length short. Actually the cable is mainly buried underneath a road with medium traffic, passes across different bridges and viaducts, starts in the middle of a town and loops in the middle of another town. Thus we expected a strong anthropic noise on the data.

The measurement on the field started in mid June 2020 and the system was operational in early July. We also installed a seismic station at one end of the cable. During these first six months, we have compared the observations on the fiber with the Italian national seismic catalog and the worldwide catalog for the major events. We consider the first results a success. We have detected so far nearly all the seismic activity with magnitude larger than 2.5 for epicentral distance lesser than 50 km. Moreover, we have recorded large events in Mediterranean region and teleseisms. Finally we have recorded new and interesting noise signals. Collecting additional events will be helpful for a better characterization of the technique, its performances and for a statistical analysis.

How to cite: Herrero, A., Calonico, D., Piccolo, F., Carpentieri, F., Govoni, A., Margheriti, L., Vassallo, M., di Giovambattista, R., Stramondo, S., Clivati, C., Concas, R., Donadello, S., Priuli, F. S., Orio, F., and Romualdi, A.: MEGLIO: an experiment to record seismic waves on a commercial fiber optic cable through interferometry measures with an ultra stable laser., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7153, https://doi.org/10.5194/egusphere-egu22-7153, 2022.

EGU22-7182 | Presentations | SM2.1 | Highlight

Monitoring a submarine strike-slip fault, using a fiber optic strain cable 

Marc-Andre Gutscher, Jean-Yves Royer, David Graindorge, Shane Murphy, Frauke Klingelhoefer, Arnaud Gaillot, Chastity Aiken, Antonio Cattaneo, Giovanni Barreca, Lionel Quetel, Giorgio Riccobene, Salvatore Aurnia, Lucia Margheriti, Milena Moretti, Sebastian Krastel, Florian Petersen, Morelia Urlaub, Heidrun Kopp, Gilda Currenti, and Philippe Jousset

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 in real time 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 tectonic faults and deformation on the seafloor.

Here, we report that BOTDR measurements detected movement at the seafloor consistent with ≥1 cm dextral strike-slip on the North Alfeo fault, 25 km offshore Catania, Sicily over the past 10 months. In Oct. 2020 a dedicated 6-km long fiber-optic strain cable was connected to the INFN-LNS (Catania physics institute) cabled seafloor observatory at 2060 m depth and deployed across this submarine fault, thus providing continuous monitoring of seafloor deformation at a spatial resolution of 2 m. The laser observations indicate significant elongation (20 - 40 microstrain) at two fault crossings, with most of the movement occurring between 19 and 21 Nov. 2020. A network of 8 seafloor geodetic stations for direct path measurements was also deployed in Oct. 2020, on both sides of the fault to provide an independent measure of relative seafloor movements. These positioning data are being downloaded during ongoing oceanographic expeditions to the working area (Aug. 2021 R/V Tethys; Jan. 2022 R/V PourquoiPas) using an acoustic modem to communicate with the stations on the seafloor. An additional experiment was performed in Sept. 2021 using an ROV on the Fugro vessel Handin Tide, by weighing down unburied portions of the submarine cable with pellet bags and sandbags (~25kg each) spaced every 5m. The response was observed simultaneously by DAS (Distributed Acoustic Sensing) recordings using two DAS interrogators (a Febus and a Silixa). The strain caused by the bag deployments was observed using BOTDR and typically produced a 50 - 100 microstrain signal across the 120 meter-long segments which were weighed down. In Jan. 2022 during the FocusX2 marine expedition, 21 ocean bottom seismometers were deployed for 12-14 months, which together with 15 temporary land-stations as well as the existing network of permanent stations (both operated by INGV) will allow us to perform a regional land-sea passive seismological monitoring experiment.

How to cite: Gutscher, M.-A., Royer, J.-Y., Graindorge, D., Murphy, S., Klingelhoefer, F., Gaillot, A., Aiken, C., Cattaneo, A., Barreca, G., Quetel, L., Riccobene, G., Aurnia, S., Margheriti, L., Moretti, M., Krastel, S., Petersen, F., Urlaub, M., Kopp, H., Currenti, G., and Jousset, P.: Monitoring a submarine strike-slip fault, using a fiber optic strain cable, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7182, https://doi.org/10.5194/egusphere-egu22-7182, 2022.

EGU22-7203 | Presentations | SM2.1

Multiphase observations of a meteoroid in Iceland recorded over 40 km of telecommunications cables and a large-N network 

Ismael Vera Rodriguez, Torsten Dahm, Marius P. Isken, Toni Kraft, Oliver D. Lamb, Sin-Mei Wu, Sebastian Heimann, Pilar Sanchez-Pastor, Christopher Wollin, Alan F. Baird, Andreas Wüstefeld, Sigríður Kristjánsdóttir, Kristín Jónsdóttir, Eva P. S. Eibl, Bettina P. Goertz-Allmann, Philippe Jousset, Volker Oye, and Anne Obermann

On July 2, 2021, around 22:44 CET, a meteoroid was observed crossing the sky near Lake Thingvallavatn east of Reykjavik in Iceland. During this event, a large-N seismic network consisting of 500, 3-component geophones was monitoring local seismicity associated with the Hengill geothermal field southwest of the lake.  In addition to the large-N network, two fiber optic telecommunication cables, covering a total length of more than 40 km, were connected to distributed acoustic sensing (DAS) interrogation units. The systems were deployed under the frame of the DEEPEN collaboration project between the Eidgenössische Technische Hochschule Zürich (ETHZ), the German Research Centre for Geosciences (GFZ), NORSAR, and Iceland Geo-survey (ISOR). Both the large-N and the DAS recordings display multiple trains of infrasound arrivals from the meteoroid that coupled to the surface of the earth at the locations of the sensors. In particular, three strong phases and multiple other weaker arrivals can be identified in the DAS data.

Fitting each of the strong phases assuming point sources (i.e., fragmentations) generates travel time residuals on the order of several seconds, resulting in an unsatisfactory explanation of the observations. On the other hand, inverting the arrival times for three independent hypersonic-trajectories generating Mach cone waves reduces travel time residuals to well under 0.5 s for each arrival. However, whereas the 1st arrival is well constrained by more than 900 travel times from the large-N, DAS and additional seismic stations distributed over the Reykjanes peninsula, the 2nd and 3rd arrivals are mainly constrained by DAS observations near Lake Thingvallavatn. The less well-constrained, latter trajectories show a weak agreement with the trajectory of the first arrival. Currently, neither the multi-Mach-cone model nor the multi-fragmentation model explain all our observations satisfactorily. Thus, traditional models for interpreting meteoroid observations appear unsuitable to explain the combination of phase arrivals in the large-N network and DAS data consistently.

How to cite: Vera Rodriguez, I., Dahm, T., Isken, M. P., Kraft, T., Lamb, O. D., Wu, S.-M., Heimann, S., Sanchez-Pastor, P., Wollin, C., Baird, A. F., Wüstefeld, A., Kristjánsdóttir, S., Jónsdóttir, K., Eibl, E. P. S., Goertz-Allmann, B. P., Jousset, P., Oye, V., and Obermann, A.: Multiphase observations of a meteoroid in Iceland recorded over 40 km of telecommunications cables and a large-N network, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7203, https://doi.org/10.5194/egusphere-egu22-7203, 2022.

EGU22-7311 | Presentations | SM2.1

Calibration and repositioning of an optical fibre cable from acoustic noise obtained by DAS technology 

Lucas Papotto, Benoit DeCacqueray, and Diane Rivet

DAS (Distributed Acoustic Sensing) turns fibre optic cables used for telecommunications into multi-sensor antenna arrays. This technology makes it possible to detect an acoustic signal from a natural source such as cetacean or micro-earthquakes, or a man-made source by measuring the deformation of the cable. At sea, the coupling between the optical fibre and the ground on which it rests, as well as the calibration of the cable, is a critical point when the configuration of the cable is unknown. Is the fibre buried or suspended? What is the depth of the sensor being studied? What impact do these parameters have on the signal? The answers to these questions have an impact on the quality of the results obtained, the location of sources - seismic or acoustic - and the characterisation of the amplitude of signals are examples of this. Here, a first approach to study this calibration is proposed. Acoustic noise generated by passing ships in the vicinity of a 42km long optical fibre off Toulon, south-east France, is used to obtain signals for which the position and the signal of the source are known. Then, the synthetic and theoretical signal representing the ship's passage is modelled (3D model, AIS Long/Lat coordinates and depth, propagation speed in water c₀ = 1530m/s). This simulation allows us to compare the real and synthetic signals, in order to make assumptions about the actual cable configuration. We compare the signals through beamforming, f-k diagram and time-frequency diagram in particular. The grid search approach allowed us to determine the new position or orientation of a portion of the antenna. This new position is then evaluated from the signals of different vessels.

How to cite: Papotto, L., DeCacqueray, B., and Rivet, D.: Calibration and repositioning of an optical fibre cable from acoustic noise obtained by DAS technology, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7311, https://doi.org/10.5194/egusphere-egu22-7311, 2022.

EGU22-7742 | Presentations | SM2.1

Strain evolution on a submarine cable during the 2020-2021 Etna eruption 

Shane Murphy, Pierre Garreau, Mimmo Palano, Stephan Ker, Lionel Quetel, Philippe Jousset, Giorgio Riccobene, Salvatore Aurnia, Gilda Currenti, and Marc-Andre Gutscher

On the 13th December 2020, a Strombolian eruption occurred on Mount Etna. We present a study of the temporal and spatial variation of strain measured at the underwater base of volcano during this event. 

As part of the FOCUS project, a BOTDR (Brillouin Optical Time Domain Reflectometry) interrogator has been connected to the INFN-LNS ( Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud) fibre optic cable that extends from the port of Catania 25km offshore to TTS (Test Site South) in a water depth of 2km. This interrogator has been continuously recording the relative strain changes at 2m spacing along the length of the cable every 2 hrs since May 2020. 

On preliminary analysis, a change in strain is observed at the around the time of the eruption, however this variation occurs close to the shore where seasonal variations in water temperatures are in the order of 5°C. As Brillouin frequency shifts are caused by both temperature and strain variations, it is necessary to remove this effect. To do so, numerical simulations of seasonal sea temperature specific to offshore Catania have used to estimate the change in temperature along the cable. This temperature change is then converted to a Brillouin frequency shift and removed from the frequency shift recorded by the interrogator before being converted to relative strain measurements. This processing produces a strain signature that is consistent with deformation observed by nearby geodetic stations on land.

How to cite: Murphy, S., Garreau, P., Palano, M., Ker, S., Quetel, L., Jousset, P., Riccobene, G., Aurnia, S., Currenti, G., and Gutscher, M.-A.: Strain evolution on a submarine cable during the 2020-2021 Etna eruption, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7742, https://doi.org/10.5194/egusphere-egu22-7742, 2022.

EGU22-8113 | Presentations | SM2.1

Exploration of Distributed Acoustic Sensing (DAS) data-space using a trans-dimensional algorithm, for locating geothermal induced microseismicity 

Nicola Piana Agostinetti, Emanuele Bozzi, Alberto Villa, and Gilberto Saccorotti

Distributed Acoustic sensing (DAS) data have been widely recognised as the next generation of  seismic data for applied geophysics, given the ultra-high spatial resolution achieved. DAS data are recorded along a fiber optic cable at pre-defined distances (called “channels”, generally with 1-10 meters spacing). DAS data have been benchmarked to standard seismic data (e.g. geophones) for tasks related to both exploration and monitoring of georesources.

The analysis of DAS data has to face two key-issues: the amount of data available and their “directionality”. First, the huge amount of data recorded, e.g. in monitoring activities related to georesources exploitation, can not be easily handled with standard seismic workflow, given the spatial and temporal sampling (for example, manual picking of P-wave arrivals for 10 000 channels is not feasible). Moreover, standard seismic workflow have been generally developed for “sparse" network of sensors, i.e. for punctual measurements, without considering the possibility of recording the quasi-continuous seismic wavefield along a km-long cable. With the term “directionality" we mean the ability of the DAS data to record horizontal strain-rate only in the direction of the fiber optic cable. This can be seen as a measure of a single horizontal component in a standard seismometer. Obviously, standard seismic workflow have not been developed to work correctly for a network of seismometers with a unique horizontal component, oriented with variable azimuth from one seismometer to the other. More important, “directionality” can easily bias the recognition of the seismic phase arriving at the channel, which could be, based on the cable azimuth and the seismic noise level, a P-wave or an S-wave. 

We developed a novel application for exploring DAS data-space in a way that: (1) data are automatically down weighted with the distance from the event source; (2) recorded phases are associated to P- or S- waves with a probabilistic approach, without pre-defined phase identification; and (3) the presence of outliers is also statistically considered, each phase being potentially a converted/refracted wave to be discarded. Our methodology makes use of a trans-dimensional algorithm, for selecting relevant weights with distance. Thus, all inferences in the data-space are fully data-driven, without imposing additional constrains from the seismologist.

How to cite: Piana Agostinetti, N., Bozzi, E., Villa, A., and Saccorotti, G.: Exploration of Distributed Acoustic Sensing (DAS) data-space using a trans-dimensional algorithm, for locating geothermal induced microseismicity, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8113, https://doi.org/10.5194/egusphere-egu22-8113, 2022.

EGU22-8294 | Presentations | SM2.1 | Highlight

Real-Time Magnitude Determination and Ground Motion Prediction using Optical Fiber Distributed Acoustic Sensing for Earthquake Early Warning 

Itzhak Lior, Diane Rivet, Anthony Sladen, Diego Mercerat, and Jean-Paul Ampuero

Distributed Acoustic Sensing (DAS) is ideally suited for the challenges of Earthquake Early Warning (EEW). These distributed measurements allow for robust discrimination between earthquakes and noise, and remote recordings at hard to reach places, such as offshore, close to the hypocenters of most of the largest earthquakes on Earth. In this study, we propose the first application of DAS for EEW. We present a framework for real-time strain-rate to ground accelerations conversion, magnitude estimation and ground shaking prediction. The conversion is applied using the local slant-stack transform, adapted for real-time applications. Since currently, DAS earthquake datasets are limited to low-to-medium magnitudes, an empirical magnitude estimation approach is not feasible. To estimate the magnitude, we derive an Omega-squared-model based theoretical description for acceleration root-mean-squares (rms), a measure that can be calculated in the time-domain. Finally, peak ground motions are predicted via ground motion prediction equation that are derived using the same theoretical model, thus constituting a self-consistent EEW scheme. The method is validated using a composite dataset of earthquakes from different tectonic settings up to a magnitude of 5.7. Being theoretical, the presented approach is readily applicable to any DAS array in any seismic region and allows for continuous updating of magnitude and ground shaking predictions with time. Applying this method to optical fibers deployed near on-land and underwater faults could be decisive in the performance of EEW systems, significantly improving earthquake warning times and allowing for better preparedness for intense shaking.

How to cite: Lior, I., Rivet, D., Sladen, A., Mercerat, D., and Ampuero, J.-P.: Real-Time Magnitude Determination and Ground Motion Prediction using Optical Fiber Distributed Acoustic Sensing for Earthquake Early Warning, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8294, https://doi.org/10.5194/egusphere-egu22-8294, 2022.

EGU22-8414 | Presentations | SM2.1

Towards microseismic moment tensor inversion in boreholes with DAS 

Katinka Tuinstra, Federica Lanza, Andreas Fichtner, Andrea Zunino, Francesco Grigoli, Antonio Pio Rinaldi, and Stefan Wiemer

We present preliminary results on a moment tensor inversion workflow for Distributed Acoustic Sensing (DAS). It makes use of a fast-marching Eikonal solver and synthetically modeled data. The study specifically focuses on borehole settings for geothermal sites. Distributed Acoustic Sensing measures the wavefield with high spatial and temporal resolution. In borehole settings, individual DAS traces generally prove to be noisier than co-located geophones, whereas the densely spaced DAS shot-gathers show features that would have otherwise been missed by the commonly more sparsely distributed geophone chains. For example, the coherency in the DAS records shows the polarity reversals of the arriving wavefield in great detail, which can help constrain the moment tensor of the seismic source. The synthetic tests encompass different source types and source positions relative to the deployed fiber to assess moment tensor resolvability. Further tests include the addition of a three-component seismometer at different positions to investigate an optimal network configuration, as well as various noise conditions to mimic real data. The synthetic tests are tailored to prepare for the data from future microseismicity monitoring with DAS in the conditions of the Utah FORGE geothermal test site, Utah, USA. The proposed method aims at improving amplitude-based moment tensor inversion for DAS deployed in downhole or underground lab contexts.

How to cite: Tuinstra, K., Lanza, F., Fichtner, A., Zunino, A., Grigoli, F., Rinaldi, A. P., and Wiemer, S.: Towards microseismic moment tensor inversion in boreholes with DAS, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8414, https://doi.org/10.5194/egusphere-egu22-8414, 2022.

EGU22-8664 | Presentations | SM2.1

Seismic Exploration and monitoring of geothermal reservoirs usiNg distributed fibre optic Sensing - the joint project SENSE 

CharLotte Krawczyk, Leila Ehsaniezhad, Christopher Wollin, Johannes Hart, and Martin Lipus

For a successful operation of energy or resources use in the subsurface, exploration for potential reservoir or storage horizons, monitoring of structural health and control of induced seismic unrest are essential both from a technical and a socio-economic perspective.  Furthermore, large-scale seismic surveys in densely populated areas are difficult to carry out due to the effort required to install sources and receivers and are associated with high financial and logistical costs.  Within the joint project SENSE*, a seismic exploration and monitoring approach is tested, which is based on fibre-optic sensing in urban areas.

Besides the further development of sensing devices, the monitoring of borehole operations as well as the development of processing workflows form central parts of the joint activities. In addition, the seismic wave field was recorded and the localisation of the cables was tested along existing telecommunication cables in Berlin. Further testing of measuring conditions in an urban environment was also conducted along an optic fibre separately laid out in an accessible heating tunnel.

We suggest a workflow for virtual shot gather extraction (e.g., band pass filtering, tapering, whitening, removal of poor traces before and after cross-correlation, stacking), that is finally including a coherence-based approach.  The picking of dispersion curves in the 1-7 Hz frequency range and inversion yield a shear wave velocity model for the subsurface down to a. 300 m depth.  Several velocity interfaces are evident, and a densely staggered zone appears between 220-270 m depth.  From lab measurements a distributed backscatter measurement in OTDR mode shows that high reflections and moderate loss at connectors can be achieved in a several hundred m distance.  Depending on drilling campaign progress, we will also present first results gained during the borehole experiment running until February 2022.

* The SENSE Research Group includes in addition to the authors of this abstract Andre Kloth and Sascha Liehr (DiGOS), Katerina Krebber and Masoud Zabihi (BAM), Bernd Weber (gempa), and Thomas Reinsch (IEG).

How to cite: Krawczyk, C., Ehsaniezhad, L., Wollin, C., Hart, J., and Lipus, M.: Seismic Exploration and monitoring of geothermal reservoirs usiNg distributed fibre optic Sensing - the joint project SENSE, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8664, https://doi.org/10.5194/egusphere-egu22-8664, 2022.

EGU22-8787 | Presentations | SM2.1

PSD analysis and seismic event detectability of Distributed Acoustic Sensing (DAS) mesurements from several monitoring sites 

Nasim Karamzadeh Toularoud, Jérôme Azzola, Emmanuel Gaucher, Thomas Forbriger, Rudolf Widmer-Schnidrig, Felix Bögelspacher, Michael Frietsch, and Andreas Rietbrock

High spatial and temporal resolution of distributed acoustic sensing (DAS) measurements makes them very attractive in different applications in seismology, such as seismic noise analysis (e.g. Bahavar et al 2020, Spica et al 2020) and seismic event detection (e.g. Ajo-Franklin et al 2019, Fernandez Ruiz 2020, Jousset 2020). The quantity measured by a DAS is strain or strain rate of an optic fiber cable, which is related to the spatial gradient of displacement and velocity that is usually measured by single point seismometers. The amplitude (and signal to noise ratio, SNR) and frequency resolutions of DAS recordings depend on spatial and temporal acquisition parameters, such as i.e. gauge-length (GL) and derivative time (DT), the latter being of importance only if the device records the strain rate.

In this study, our aims have been to investigate, experimentally, how to adapt the averaging parameters such as GL and DT to gain sensitivity in frequency bands of interests, and to investigate the seismic event detection capability of DAS data under specific set up. We recorded samples of DAS raw data, over a few hours at the German Black Forest Observatory (BFO) and in Sardinia, Italy.  We studied the spectral characteristics of strain and strain rate converted from DAS raw data, to analyze the sensitivity of DAS measurements to GL and DT. The power spectral densities are compared with the strain meter recordings at BFO site as a benchmark, which is recorded using the strain-meter arrays measuring horizontal strain in three different directions independently from the DAS (For details about the DAS measurement station at BFO see Azzola et al.  EGU 2022). We concluded about the lower limit of the DAS noise level that is achievable with employing different acquisition parameters. Accordingly, we applied suitable parameters for continuous strain-rate data acquisition at another experimental site in Georgia, which is related to the DAMAST (Dams and Seismicity) project.  

During the acquisition time periods at BFO and in Georgia, the visibility of local, regional and teleseismic events on the DAS data has been investigated. At both sites, a broadband seismometer is continuously operating, and can be considered as a reference to evaluate the event detection capability of the DAS recordings taking into account the monitoring set-up, i.e. cable types,  cable coupling to the ground, directional sensitivity and acquisition parameters. In addition, at BFO the DAS seismic event detection capability is evaluated comparing with the strain-meter array. Examples of detected seismic events by DAS are discussed, in terms of achievable SNR for each frequency content and comparison with the seismometers and strain-meter array.

How to cite: Karamzadeh Toularoud, N., Azzola, J., Gaucher, E., Forbriger, T., Widmer-Schnidrig, R., Bögelspacher, F., Frietsch, M., and Rietbrock, A.: PSD analysis and seismic event detectability of Distributed Acoustic Sensing (DAS) mesurements from several monitoring sites, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8787, https://doi.org/10.5194/egusphere-egu22-8787, 2022.

EGU22-10322 | Presentations | SM2.1

Strain accumulation along a 21km long optic fibre during a seismic crisis in Iceland, 2020 

Christopher Wollin, Philippe Jousset, Thomas Reinsch, Martin Lipus, and Charlotte Krawczyk

Slow slip plays an important role in accommodating plate motion along plate boundaries throughout the world. Further understanding of the interplay between aseismic and seismic slip has gained particular attention as it is crucial for the assessment of seismic risk. A wide range of instruments and acquisition techniques exist to quantify tectonic deformation which spans multiple orders of magnitude in duration as well as spatial extend. For example, seismometers acquire dense temporal data, however are sparsely deployed, leading to spatial aliasing. As opposite, remote sensing techniques have wide aperture but rather crude temporal resolution and accuracy (mm-range). In selected areas, strain is continuously measured with laser or borehole strainmeters.
In this contribution, we investigate the distribution of permanent strain along a telecommunication optic fibre on the Reykjanes Peninsula, South West Iceland. Continuous strain-rate was recorded via DAS (Distributed Acoustic Sensing) over a period of six months during the recent unrest of the Svartsengi volcano which began in January 2020. The interrogated fibre connects the town of Gridavik with the Svartsengi geothermal power plant and was patched to a second fibre leading to the western most tip of the Reykjanes Peninsula. It is approximately between 10 and 20km west of the active volcanic area which produced abundant local seismicity as well as surface uplift and subsidence in areas crossed with the optical fiber. The fibre was installed in a trench at less than one meter depth and consists of two roughly straight segments of 7 and 14km length. Whereas the longer segment trends WSW parallel to the strike of the Mid-Atlantic Ridge at this geographic height, the shorter segment trends NEN and thus almost coincides with the maximum compressive stress axis of the region.
Inspection of the spatio-temporal strain-rate records after the occurrence of local earthquakes indicates the accumulation of compressive as well as extensive strain in short fibre sections of a few dozen meters which could correlate with local geologic features like faults or dykes. This holds for events of M~2.5 and fibre segments in epicentral distances of more than 20km. Preliminary results regarding the total deformation of the fibre as response to an individual seismic event show a distinct behaviour for differently oriented fibre segments correlating with the overall stress regime, i.e. shortening in the order of some dozen nanometers in the direction of SHmax. Unfortunately, recordings of the two largest intermediate M>=4.8 events indicate saturation of the recording system or loss of ground coupling thus preventing a meaningful interpretation of their effect on permanent surface motion. 
Perspectively, our efforts aim at investigating the feasibility of distributed optical strain-rate measurements along telecommunication infrastructure to track locally accumulated strain.

How to cite: Wollin, C., Jousset, P., Reinsch, T., Lipus, M., and Krawczyk, C.: Strain accumulation along a 21km long optic fibre during a seismic crisis in Iceland, 2020, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10322, https://doi.org/10.5194/egusphere-egu22-10322, 2022.

EGU22-10574 | Presentations | SM2.1

Innovative high resolution optical geophysical instruments at the termination of long fibers: first results from the Les Saintes optical ocean bottom seismometer, and from the Stromboli optical strainmeter 

Pascal Bernard, Guy Plantier, Philippe Ménard, Yann Hello, Guillaume Savaton, Jean-Philippe Metaxian, Maurizio Ripepe, Marie-Paule Bouin, Frederick Boudin, Romain Feron, Sébastien Deroussi, and Roberto Moretti and the optic-OBS-strain-2022 team

In June 2022, in the frame of the PREST interreg Caraïbe project, we installed an optical OBS offshore the Les Saintes archipelago (Guadeloupe, Lesser Antilles), at the termination of a 5.5 km long optic cable buried in the sea floor and landing in Terre-de-Bas island (FIBROSAINTES campaign: Antea vessel from the FOF, plow from GEOAZUR). This innovative seismometer, developped in the last decade by ESEO, is based on Fabry-Perot (FP) interferometry, tracking at high resolution (rms 30 pm) the displacement of the mobile mass of a 10 Hz, 3 component, purely mechanical geophone (no electronics nor feed-back). This optically cabled OBS is the marine version of the optical seismometer installed at the top of La Soufrière volcano of Guadeloupe, in 2019, at the termination of a 1.5 km long fiber (HIPERSIS ANR project). Both seismometers are telemetered in real-time to the Guadeloupe Observatory (IPGP/OVSG). The optical seismometer, located at a water depth of 43 m near the edge of the immersed reef, is aimed at improving the location of the swarm-like seismicity which still persists after the Les Saintes 2004, M6.3 normal fault earthquake. The considerable advantage of such a purely optical submarine sensor over commercial, electric ones is that its robustness, due to the absence of electrical component, guarantees a very low probability of failure, and thus significantly reduces the costs of maintenance. In May 2022, an optical pressiometer and an optical hydrostatic tiltmeter designed and constructed by ENS shoud be installed offshore and connected to the long fiber, next to the optical OBS.

Based on the same FP interrogator, ESEO and IPGP recently developped a high resolution fiber strainmeter, the sensing part being a 5 m long fiber, to be buried or cemented to the ground. A prototype has been installed mid-September 2021 on the Stromboli volcano, in the frame of the MONIDAS (ANR) and LOFIGH (Labex Univearth, Univ. Paris) projects. The interrogator was located in the old volcanological observatory, downslope, and the optical sensors, at 500 m altitude, were plugged at the end of a 3 km optic cable. They consist of three fibers, 5 m long each, buried 50 cm into the ground. Their different orientation allowed to retrieve the complete local strain field. The four weeks of continuous operation clearly recorded the dynamic strain from the frequent ordinary summital explosion ( several per hour), and, most importantly, the major explosion of the 6th of October (only a few per year). The records show a clear precursory signal, starting 120s before this explosion, corresponding to a transient compression, oriented in the crater azimuth, peaking at 0.9 microstrain  10 s before the explosion.

These two successfull installations of optical instruments open promising perspectives for the seismic and strain real-time monitoring in many sites, offshore, on volcanoes, and more generally in any site, natural or industrial, presenting harsh environmental conditions, where commercial, electrical sensors are difficult and/or costly to install and to maintain, or simply cannot be operated.

How to cite: Bernard, P., Plantier, G., Ménard, P., Hello, Y., Savaton, G., Metaxian, J.-P., Ripepe, M., Bouin, M.-P., Boudin, F., Feron, R., Deroussi, S., and Moretti, R. and the optic-OBS-strain-2022 team: Innovative high resolution optical geophysical instruments at the termination of long fibers: first results from the Les Saintes optical ocean bottom seismometer, and from the Stromboli optical strainmeter, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10574, https://doi.org/10.5194/egusphere-egu22-10574, 2022.

EGU22-11311 | Presentations | SM2.1

Overcoming limitations of seismic monitoring using fibre-optic distributed acoustic sensing 

Regina Maaß, Sven Schippkus, Céline Hadziioannou, Benjamin Schwarz, Charlotte Krawczyk, and Philippe Jousset

Seismic monitoring refers to the measurement of time-lapse changes of seismic wave velocities and is a frequently used technique to detect dynamic changes in the Earth‘s crust. Its applications include a broad range of topics, such as natural hazard assessment and structural health monitoring. To obtain reliable measurements, results are usually stacked over time. Thereby, temporal resolution is lost, which makes the measurement less sensitive to short-term environmental processes. Another problem is that conventional datasets often lack spatial density and velocity changes can only be attributed to large areas. Recently, distributed acoustic sensing (DAS) has gained a lot of attention as a way to achieve high spatial resolution at low cost. DAS is based on Rayleigh-scattering of photons within an optical fibre. Because measurements can be taken every few meters along the cable, the fibre is turned into a large seismic array that provides information about the Earth’s crust at unprecedented resolution.

In our study, we explore the potential of DAS for monitoring studies. Specifically, we investigate how spatial stacking of DAS traces affects the measurements of velocity variations. We use data recorded by a 21-km-long dark fibre located on Reykjanes Pensinsula, Iceland. The cable is sampled with a channel spacing of 4 meters. We analyze the energy of the oceans microseism continuously recorded between March and September 2020. At first, we stack adjacent traces on the fibre in space. We then cross correlate the stacks to obtain approximations of the Green’s functions between different DAS-channels. By measuring changes in the coda waveform of the extracted seismograms, velocity variations can be inferred. Our analysis shows that spatial stacking improves the reliability of our measurements considerably. Because of that, less temporal stacking is required and the time resolution of our measurements can be increased. In addition, the enhancement of the data quality helps resolve velocity variations in space, allowing us to observe variations propagating along the cable over time. These velocity changes are likely linked to magmatic intrusions associated with a series of repeated uplifts on the Peninsula. Our results highlight the potential of DAS for improving the localization capabilities and accuracy of seismic monitoring studies.

How to cite: Maaß, R., Schippkus, S., Hadziioannou, C., Schwarz, B., Krawczyk, C., and Jousset, P.: Overcoming limitations of seismic monitoring using fibre-optic distributed acoustic sensing, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11311, https://doi.org/10.5194/egusphere-egu22-11311, 2022.

EGU22-11508 | Presentations | SM2.1 | Highlight

Building a new type of seafloor observatory on submarine telecom fiber optic cables in Chile 

Diane Rivet, Sergio Barrientos, Rodrigo Sánchez-Olavarría, Jean-Paul Ampuero, Itzhak Lior, Jose-Antonio Bustamente Prado, and German-Alberto Villarroel Opazo

In most subduction zones, a great portion of seismicity is located offshore, away from permanent onland seismic networks. Chile is not the exception; since the upgraded seismic observation system began operating in 2013, 35% of the ~7000 earthquakes with M≥3 recorded yearly were located offshore. Most importantly, the epicenters of the largest earthquakes (M>7.5) from 2014 to 2016 were located offshore as well.

The Chilean national seismic network is mainly composed of coastal and inland stations, except for two stations located on oceanic islands, Rapa Nui (Easter Island) and Juan Fernandez archipelago. This station configuration makes it difficult to observe in sufficient detail the lower-magnitude seismicity at the nucleation points of large events. Moreover, the lack of seafloor stations limits the efficiency of earthquake early warning systems during offshore events. These challenges could be overcome by permanently instrumenting existing submarine telecom cables with Distributed Acoustic Sensing (DAS).

Thanks to GTD, a private telecommunications company that owns a 3500-km-long network of marine fiber optic cables with twelve landing points in Chile (Prat project), from Arica (~ 18⁰S) to Puerto Montt (~ 41⁰S), we conducted the POST (Submarine Earthquake Observation Project in Spanish) DAS experiment on the northern leg of the Concón landing site of the Prat cable. This experiment, one of the first to be conducted on a commercial undersea infrastructure in a very seismically active region, was carried out from October 28 to December 3, 2021. Based on the longitudinal strain-rate data measured along 150 km of cable with a spatial resolution of 4 meters and a temporal sampling of 125 Hz, we present preliminary results of analyses to assess the possibility of building a new type of permanent, real-time and distributed seafloor observatory for continuous monitoring of active faults and earthquake early warning systems.

How to cite: Rivet, D., Barrientos, S., Sánchez-Olavarría, R., Ampuero, J.-P., Lior, I., Bustamente Prado, J.-A., and Villarroel Opazo, G.-A.: Building a new type of seafloor observatory on submarine telecom fiber optic cables in Chile, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11508, https://doi.org/10.5194/egusphere-egu22-11508, 2022.

EGU22-11599 | Presentations | SM2.1

Comparing two fiber-optic sensing systems: Distributed Acoustic Sensing and Direct Transmission 

Daniel Bowden, Andreas Fichtner, Thomas Nikas, Adonis Bogris, Konstantinos Lentas, Christos Simos, Krystyna Smolinski, Iraklis Simos, and Nikolaos Melis

Distributed Acoustic Sensing (DAS) systems have gained popularity in recent years due to the dense spatial coverage of strain observations; with one fiber and one interrogator researchers can have access to thousands of strain or strain-rate observations over a region. DAS systems have a limited range, however, with usual experiments being on the order of 10’s of kilometers, owing to their reliance on weakly backscattered light. In contrast, systems that transmit light through a fiber and measure signals on the other end (or looped back) can traverse significantly longer distances (e.g., Marra et. al 2018, Zhan et. al 2021, Bogris et. al 2021), and have the added advantages of being potentially cheaper and potentially operating in parallel with active telecommunications purposes. The disadvantage of such transmission systems is that only a single measurement of strain along the entire distance is given.

During September - October 2021, we operated examples of both systems side-by-side using telecommunications fibers underneath North Athens, Greece, in collaboration with the OTE telecommunications provider. Several earthquakes were detected by both systems, and we compare observations from both. The DAS system is a Silixa iDAS Interrogator measuring strain-rate. The newly designed transmission system relies on interferometric use of microwave frequency dissemination; signals sent along the fiber and back in a closed loop are compared to what was sent to measure phase differences (Bogris et. al 2021). We find that both systems are successful in sensing earthquakes and agree remarkably well when DAS signals are integrated over the length of the cable to properly mimic the transmission observations.

The direct transmission system, however, may not be as intuitive to interpret as an integral of displacement ground motions along the fiber. We discuss both theoretical and data-driven examples of how the observed phases depend on the curvature of a given length of fiber, and describe how asymmetries in the fiber’s index of refraction play a role in producing observed signals. Such an understanding is crucial if one is to properly interpret the signals from such a system (e.g., especially very long trans-oceanic cables). Given a full theoretical framework, we also discuss a strategy for seismic tomography given such a system: with a very long fiber, the spatial sensitivity should evolve over time as seismic signals reach different sections.

How to cite: Bowden, D., Fichtner, A., Nikas, T., Bogris, A., Lentas, K., Simos, C., Smolinski, K., Simos, I., and Melis, N.: Comparing two fiber-optic sensing systems: Distributed Acoustic Sensing and Direct Transmission, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11599, https://doi.org/10.5194/egusphere-egu22-11599, 2022.

EGU22-11864 | Presentations | SM2.1

Distributed Acoustic Sensing in the Athens Metropolitan Area: Preliminary Results 

Krystyna T. Smolinski, Daniel C. Bowden, Konstantinos Lentas, Nikolaos S. Melis, Christos Simos, Adonis Bogris, Iraklis Simos, Thomas Nikas, and Andreas Fichtner

Once a niche technology, Distributed Acoustic Sensing (DAS) has gained increasing popularity over the last decade, due to its versatility and ability to capture extremely dense seismic datasets in a wide range of challenging environments. While DAS has been utilised in some particularly remote locations, such as on glaciers and volcanoes, it also holds a great deal of potential closer to home; beneath our cities. As DAS is able to be used with existing telecommunication fibres, urban areas contain huge potential networks of strain or strain-rate sensors, right beneath our feet. This data enables us to monitor the local environment, recording events such as earthquakes, as well as characterising and monitoring the shallow subsurface. DAS experiments using dark fibres are unintrusive and highly repeatable, meaning that this method is ideal for long-term site monitoring.

In collaboration with the OTE Group (the largest telecommunications company in Greece), we have collected urban DAS data beneath North-East Athens, utilising existing, in-situ telecommunication fibres. This large dataset contains a wide range of anthropogenic signals, as well as many seismic events, ranging from small, local events, to an internationally reported Magnitude 6.4 earthquake in Crete.

We conduct a preliminary analysis of the dataset, identifying and assessing the earthquake signals recorded. This will be compared with the event catalogue of the local, regional network in Athens, to determine our sensitivity to events of different magnitudes, and in a range of locations. We hope to gain an understanding of how DAS could be combined with the existing network for seismic monitoring and earthquake detection.

Moving forward, we aim to also apply ambient noise methods to this dataset in order to extract dispersion measurements, and ultimately invert for a shallow velocity model of the suburbs of Athens.

How to cite: Smolinski, K. T., Bowden, D. C., Lentas, K., Melis, N. S., Simos, C., Bogris, A., Simos, I., Nikas, T., and Fichtner, A.: Distributed Acoustic Sensing in the Athens Metropolitan Area: Preliminary Results, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11864, https://doi.org/10.5194/egusphere-egu22-11864, 2022.

EGU22-11869 | Presentations | SM2.1

Long range distributed acoustic sensing technology for subsea geophysical applications 

Erlend Rønnekleiv, Ole Henrik Waagaard, Jan Petter Morten, and Jan Kristoffer Brenne

Recent advances in range and performance of distributed acoustic sensing (DAS) enable new geophysical applications by measuring fiber strain in existing telecom cables and subsea power cables that incorporate optical fibers. We will  present new field data showing the usability of DAS for environmental and geophysical applications, focusing especially on seabed surface waves and the sub-Hz domain. These examples show that highly sensitive DAS technology can be a valuable tool within seismology and oceanography.

The sensitive range along the fiber for DAS was previously limited to about 50 km. We will demonstrate a newly developed system (named OptoDAS) that allows for launching several orders of more optical power into the fiber, and thereby significantly improving the range beyond 150 km.

This new interrogation approach allows for high degree of flexibility optimizing the interrogation parameters to optimize the noise floor, spatial and temporal resolution according to the application. The gauge length (spatial resolution) can be set from 2 to 40 m. For interrogation of 10 km fiber, we achieve a record low noise floor of 1.4 pε/√Hz with 10 m spatial resolution. For interrogation of fibers beyond 150 km, we achieve a noise floor below 50 pε/√Hz up to 100 km. Above 100 km, the noise is limited by the level of reflected optical power, and the noise increases by ~0.3-0.4 dB/km, corresponding to the dual path optical loss in the fiber.

A modern instrument control interface allows for automatic optimalization of interrogation parameters based on application parameters in a few minutes. The instrument computer provides a flexible platform for different applications. The high-capacity storage system can store recorded time-series of several weeks to support e.g., geophysical investigations where extensive post-processing is required. The computational capacity can also be used for real-time visualization and advanced signal processing, for example for event detection and direct reporting of estimated parameters.

The OptoDAS system can convert a submarine cable into a 100 km+ densely sampled array.  From the recordings on a telecom cable in the North Sea, we will show examples of propagating Rayleigh and Love acoustical modes bounded to the seafloor surface. These modes can be excited by acoustic sources on or above the seafloor, such as trawls and anchors. The dense spatial sampling allows for accurate estimates of the location of these sources. The system also allows for applications in seismology and earthquake monitoring. When attached to a cable with non-straight geometry, the measurements have substantial information to determine the location of seismic events. This will be demonstrated using field data from the North Sea telecom cable.

From recordings on a submarine cable between Norway and Denmark, we present the DAS response in the frequency range 0.1 mHz-10Hz across a cable span of 120 km. The response in this frequency range will be a combination of temperature changes, ocean swells and tides. We show that increasing the gauge length in post-processing allows for improving the sensitivity for detecting ultra-low frequency signals.

How to cite: Rønnekleiv, E., Waagaard, O. H., Morten, J. P., and Brenne, J. K.: Long range distributed acoustic sensing technology for subsea geophysical applications, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11869, https://doi.org/10.5194/egusphere-egu22-11869, 2022.

The Dayi seismic gap of the Longmenshan thrust belt is located between the ruptures of the 2008 Wenchuan Earthquake and the 2013 Lushan Earthquake, with a length of about 40 ~ 60 km. So far, it has been still a heated debate on whether the Dayi seismic gap has the hazard of strong earthquakes in the near future. The occurrence of a strong earthquake in the seismic gap is closely related to the existence of high stress accumulation and the most direct method is to measure the borehole stress in the field. In order to find out the present stress state, in-situ stress measurements were carried out at the hanging wall and footwall of Dachuan-Shuangshi fault zone in Dachuan Town. The results showed that the hanging wall and footwall of Dachuan-Shuangshi fault zone in Dayi seismic gap are in a high-stress state. Based on seismicity parameter b-value, crustal velocity structure, GPS deformation monitoring data and temperature data, etc., it can be learned that there is a positive correlation coupling relationship between near surface shallow stress and deep stress. In this paper, a response model of shallow stress to deep locking was established. It was speculated that Dayi seismic gap has the potential hazard of strong earthquakes. This research result not only deepens the understanding of the relationship between stress and earthquake preparation, but also provides an effective scientific method for identifying seismic hazards in other active fault seismic gaps.

How to cite: li, B., Huang, J., and Xie, F.: In situ stress state and earthquake hazard assessment in Dayi seismic gap of the Longmenshan thrust belt, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-648, https://doi.org/10.5194/egusphere-egu22-648, 2022.

EGU22-799 | Presentations | TS1.4

Machine Learning and Underground Geomechanics – data needs, algorithm development, uncertainty, and engineering verification 

Josephine Morgenroth, Usman T. Khan, and Matthew A. Perras

Machine learning algorithms (MLAs) are emerging as a powerful tool for forecasting complex and nuanced rock mass behaviour, particularly when large, multivariate datasets are available. In engineering practice, it is often difficult for geomechanical professionals to investigate all available data in detail, and simplifications are necessary to streamline the engineering design process. An MLA is capable of processing large volumes of data quickly and may uncover relationships that are not immediately evident when manually processing data. This research compares two algorithms developed for two mines representing end member behaviours of rock failure mechanisms: squeezing ground with high radial convergence, and spalling ground with high in situ stresses and seismicity. For the squeezing ground case study, a Convolutional Neural Network is used to forecast the yield of the tunnel liner elements using tunnel mapping images as the input. For the high stress case study, a Long Short Term Memory network is used to forecast the in-situ stresses that takes time series microseismic events and geomechanical properties as inputs. The two case studies are used to compare input data requirements and pre-processing techniques. Ensemble modelling techniques used to quantify MLA uncertainty for both case studies are presented. The development of the two MLAs is discussed in terms of their complexity, generalizability, performance evaluation, verification, and practical applications to underground rock engineering. Finally, best practices for MLA development are proposed based on the two case studies to ensure model interpretability and use in engineering applications.

How to cite: Morgenroth, J., Khan, U. T., and Perras, M. A.: Machine Learning and Underground Geomechanics – data needs, algorithm development, uncertainty, and engineering verification, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-799, https://doi.org/10.5194/egusphere-egu22-799, 2022.

EGU22-2742 | Presentations | TS1.4 | Highlight

Assessing the effect of mass withdrawal from a surface quarry on the Mw4.9 Le Teil (France) earthquake triggering 

Julie Maury, Théophile Guillon, Hideo Aochi, Behrooz Bazargan, and André Burnol

On November 11th 2019, the Le Teil, France earthquake occurred in the vicinity of a quarry. Immediately, the question was raised about the potential triggering of this earthquake by the quarry. However, another potential triggering source is a hydraulic effect related to heavy rainfall (Burnol et al, 2021). That’s why it is important to quantify precisely the mechanical effect of mass withdrawal. Results from different studies (Ampuero et al, technical report CNRS, 2019; De Novellis et al, Comm. Earth Env., 2021) agrees to a Coulomb stress variation of 0.15 to 0.2 MPa. However, these studies are based on Boussinesq solution supposing a homogeneous half-space that maximize the effect of the quarry. Here we used the distinct element method code 3DEC @Itasca in 3D to take advantage of an improved geological model and assess the impact of discontinuities as well as lithology. Our results show the maximum Coulomb stress change of 0.27 MPa at 1.4 km depth, a value of the same order as what is obtained with Boussinesq solution. A comparison between the location of the earthquake (Delouis et al, 2021) and the maximum Coulomb stress is realized. The maximum value is located at the intersection of the Rouviere fault with another local fault highlighting the interaction between these structures. However, the in situ stress field is not well-known, fault parameters are difficult to assess and there is some uncertainty on the volume of extracted material in the 19th century estimated by the quarry owner. Additionally, the presence of marl in the Hauterivian layer suggests it could have an elasto-plastic behavior. A parametric study has been realized to assess the effect on Coulomb stress change of these uncertainties taking plausible values for each parameter. We show that the uncertainty associated with our calculations affect the results within a range of less than 10%.

How to cite: Maury, J., Guillon, T., Aochi, H., Bazargan, B., and Burnol, A.: Assessing the effect of mass withdrawal from a surface quarry on the Mw4.9 Le Teil (France) earthquake triggering, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2742, https://doi.org/10.5194/egusphere-egu22-2742, 2022.

EGU22-3272 | Presentations | TS1.4

The stress memory in rocks: insight from the deformation rate analysis (DRA) and acoustic emission (AE) 

Zulfiqar Ali, Murat Karakus, Giang D. Nguyen, and Khalid Amrouch

Deformation rate analysis (DRA) and Acoustic Emission (AE) are popular methods of in-situ stress measurements from oriented cored rocks which take advantage of the rock stress memory also known as the Kaiser effect. These methods rely on the accurate measurement of a point of inflection in the characteristic DRA and AE curves, however, due to the complex geological stress history in rocks, locating point of inflection can be problematic. In order to better understand the stress memory experiments were performed on a combination of six different types of soft, and hard crystalline rocks including concrete with no stress history. The effect of loading modes, strain rates, and time delay were studied on preloaded rock specimens to investigate their influence on the stress memory. A fading effect was observed when the number of the cycles in the test were increased which led to the development of a new method of quantifying the preloads. Results show that the type of loading and the loading rate has little to no influence on the Kaiser effect, however, under faster loading rates the Kaiser effect is more distinct. Likewise, no time dependency was observed for time delays up to seven months.

How to cite: Ali, Z., Karakus, M., Nguyen, G. D., and Amrouch, K.: The stress memory in rocks: insight from the deformation rate analysis (DRA) and acoustic emission (AE), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3272, https://doi.org/10.5194/egusphere-egu22-3272, 2022.

A review of works is presented in which new models of continuum mechanics generalizing the classical theories of elasticity are being intensively developed. These models are used to describe composite and statistically inhomogeneous media, new structural materials, as well as complexly constructed massifs in mine and ground conditions; and in the study of phenomena occurring in permafrost under the influence of heating processes. A characteristic feature of the theory of media with a hierarchical structure is the presence of explicit or implicit scale parameters, i.e. explicit or implicit non-locality of the theory. This work focuses on the study of the non-locality effects and internal degrees of freedom reflected in internal stresses that are not described by the classical theory of elasticity, but can be potential precursors of the development of a catastrophic process in a rock mass.

How to cite: Hachay, O. and Khachay, A.: Geophysical research and monitorind within a block-layered model with inclusions of hierrchical structure, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4574, https://doi.org/10.5194/egusphere-egu22-4574, 2022.

EGU22-4738 | Presentations | TS1.4

Modeling principal stress orientations in the Arabian plate using plate velocities 

Santiago Pena Clavijo, Thomas Finkbeiner, and Abdulkader M. Afifi

The Arabian Peninsula is part of a small tectonic plate that is characterized by active and appreciable deformations along its boundaries. Knowledge of the present-day in situ stress field in the Arabian plate and its variability is critical for earth science disciplines that require an understanding of geodynamic processes. In addition, it is essential for a range of practical applications that include the production of hydrocarbons and geothermal energy, mine safety, seismic hazard assessment, underground storage of CO2, and more.

This project aims at modeling the stress orientation field in the Arabian Plate using advanced computational tools together with a plate velocity model. We built a three-layer 3D model of the Arabian crust using digital elevation, basement depth, and Moho depth maps. Based on these data, we built a 3D unstructured finite element mesh for the whole Arabian plate, including the offshore area, with finer resolution at critical locations. The latter is a novel approach to this work.  To capture the deformation caused by the water bodies in the Red Sea, Gulf of Aden, and the Arabian Sea areas, we set a hydrostatic boundary condition as a function of bathymetry. Along the Zagros fold and thrust belt, we pinned the plate boundary to capture continental collision. Finally, the partial differential equation of force equilibrium (a linear static analysis) is solved using plate displacements (inferred from plate velocities) as boundary conditions for several displacement conditions.

The modeling results suggest NE-SW SHmax azimuths in northeastern Saudi Arabia and Kuwait while the Dead Sea transform areas show NW-SE to NNW-SSE azimuths, and the rest of the plate is characterized by predominant N-S SHmax azimuth. Due to pinned boundary conditions at the Zagros Mountains, SHmax azimuth changes from N-S at the Red Sea basin to NE-SW at the Zagros fold and thrust belt. We also notice significant stress concentrations in the transition from the Arabian shield to the sedimentary basins in the Eastern parts of the plate. This is in response to associated changes in rock properties. Hence, the simulated stress orientations corroborate the ongoing tectonic process and deepen our understanding of regional and local in situ stress variation drivers as well as the current elastic deformation in the Arabian plate.

How to cite: Pena Clavijo, S., Finkbeiner, T., and Afifi, A. M.: Modeling principal stress orientations in the Arabian plate using plate velocities, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4738, https://doi.org/10.5194/egusphere-egu22-4738, 2022.

EGU22-5494 | Presentations | TS1.4 | Highlight

Stress characterization in the Canadian Shield: Complexity in stress rotation 

Wenjing Wang and Douglas Schmitt

NE-SW stress compression in the Western Canadian Sedimentary Basin was discovered in the pioneering borehole breakout observations of Bell and Gough (1979). However, all of these and subsequent stress direction indicators are from the Phanerozoic sediment veneer, while the state of stress in the underlying craton remains unexplored. With the emergent demands on geothermal energy and wastewater and CO2 disposal, however, the state of stress in the cratons can no longer be safely ignored. To address this problem, we analyze various vintages of geophysical logs obtained from a serendipitous wellbore-of-opportunity drilled to 2.4 km in NE Alberta.  The profile of breakout orientations inferred from image and caliper logs exhibits a distinct rotation in breakout orientations changing from N100°E at 1650-2000m to N173°E at 2000-2210m and, finally, to N145°E at the bottom from 2210-2315m. The deepest measurement is consistent with the many observations in the overlying sediments. The heterogeneous breakout orientations at different depth intervals possibly indicate a heterogeneous in-situ stress field in the Precambrian craton. In addition, however, there is a strong correlation between the metamorphic textures and the breakout orientations suggesting that anisotropic strength may play an important role.  Using a recently developed algorithm we show that these observations can indeed be explained by foliation-controlled failure patterns in such anisotropic metamorphic rocks (Wang & Schmitt, accepted).  Models demonstrate that the observed breakout rotations can be produced under uniform stress orientations with failure slip planes controlled by the textured metamorphic rocks with anisotropic strength. This modeled stress field indicates that the stress field in the Canadian Shield where the far-field SH azimuth is at N50°E and the region is under normal/strike-slip faulting regime, is coupled with that in the overlying sedimentary basin.

How to cite: Wang, W. and Schmitt, D.: Stress characterization in the Canadian Shield: Complexity in stress rotation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5494, https://doi.org/10.5194/egusphere-egu22-5494, 2022.

EGU22-6453 | Presentations | TS1.4

Can we afford fracture pressure uncertainty? Limit tests as a key calibration for geomechanical models 

Michał Kępiński, David Wiprut, and Pramit Basu

The Leak-Off Test (LOT) is one of the most common fracture pressure/Shmin calibration measurements conducted in wellbores. Well engineers rely on readings from LOTs to design safe drilling plans. The LOT results indicate the maximum mud weight or equivalent circulating density that can be used to drill the next hole section without causing fluid losses to the formation. Losses are one of the most expensive issues to mitigate in drilling operations. In more severe cases, losses may lead to subsequent drilling challenges such as hole collapse or kicks. Oftentimes, drillers choose not to pressurize the well up to the leak-off pressure due to the risk of weakening the rock beneath the casing shoe by creating a fracture. In these cases, a formation integrity test (FIT) is conducted. However, the FIT is inadequate for properly constraining the fracture gradient or for input to geomechanical models because it is possible for the FIT to terminate at pressures that are either above or below the far-field minimum stress.

Geomechanical modelling from several projects in Poland shows that insufficient LOT measurements introduce a wide range of fracture gradient uncertainty, complicating the analysis of optimal ECD values in narrow margin drilling sections. This leads to difficulty in determining the proper mud weight when a loss event occurs. Additionally, without reliable calibration of the minimum horizontal stress, the geomechanical model used to determine the lower bound of the mud window becomes more uncertain. An inadequately constrained mud window can result in further drilling complications such as tight hole, stuck pipe, poor hole condition, and compromised log quality.

How to cite: Kępiński, M., Wiprut, D., and Basu, P.: Can we afford fracture pressure uncertainty? Limit tests as a key calibration for geomechanical models, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6453, https://doi.org/10.5194/egusphere-egu22-6453, 2022.

EGU22-8802 | Presentations | TS1.4

Stress state and patterns at the upper plate of Hikurangi Subduction Margin 

Effat Behboudi, David McNamara, and Ivan Lokmer

Quantifying the contemporary stress state of the Earth’s crust is critical for developing a geomechanical understanding of the behavior of brittle deformation (fractures and faults).In this study we characterize the shallow contemporary stress state of the active Hikurangi Subduction Margin (HSM), New Zealand, to better understand how it affects and responds to variable deformation and slip behavior documented along this plate boundary. The HSM is characterized by along-strike variations in megathrust slip behavior, ranging from shallow slow slip events (SSEs) and creep at the northern and central HSM to interseismic locking and stress accumulation in the southern HSM. We estimate the state of stress across the HSM utilizing rock strength estimates from empirical relationships, leak-off test data, wireline logs and borehole geology, and measurement of borehole wall failures such as borehole breakouts and drilling‐induced tensile fractures from eight boreholes. Stress magnitude constraints at depth intervals where BOs are observed indicate that the maximum principal stress (σ1) is horizontal along the shallow (<3 km) HSM and the stress state is predominantly strike-slip or contractional (barring localized areas where an extensional stress state is determined). Our results reveal a NE-SW (margin-parallel) SHmax orientation in the shallow central HSM, which rotates to a WNW- ESE/NW-SE (margin-perpendicular) SHmax orientation in the shallow southern HSM. The central NE-SW SHmax orientation is inconsistent with active, km-scale, NE-SW striking contractional faults observed across the central HSM. Considering both stress magnitude and orientation patterns at the central HSM, we suggest that long-term clockwise rotation of the Hikurangi forearc, over time, may transform motion on these km-scale central HSM faults from contractional dip-slip to a more contemporary strike/oblique-slip. The southern shallow WNW- ESE/NW-SE SHmax orientation is nearly perpendicular to focal-mechanisms derived NE-SW SHmax orientations within the subducting slab. This, combined with observed strike-slip and contractional faulting in the region and the NW-SE convergence direction, implies the overriding plate in the southern HSM is in a contractional stress state, potentially as deep as the plate interface, which is decoupled from that experienced in the subducting slab. Observed localized extensional stress states across the HSM may occur as a result of local extensions or reflect uncertainties in our estimations of SHmax magnitude which are sensitive to the UCS values used (unconstrained by laboratory testing). This UCS uncertainty and the potential errors it can introduce into a stress model highlights the importance of developing robust empirical relationships for UCS in regions where stress is a critical geological consideration for hazard and resource management.

How to cite: Behboudi, E., McNamara, D., and Lokmer, I.: Stress state and patterns at the upper plate of Hikurangi Subduction Margin, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8802, https://doi.org/10.5194/egusphere-egu22-8802, 2022.

A series of numerical simulations of mantle convection in 3D spherical-shell geometry were performed to evaluate the intraplate stress regime from numerically obtained velocity and stress fields. The intraplate stress regime was quantitatively classified into nine types by analyzing the principal deviatoric stress axes and the “stress ratio,” which is a continuous parameter accounting for the stress regimes. From the viewpoint of global geodynamics, this study analyzed the depth profile of the stress ratio across the entire depth of the mantle. The results demonstrated that the radial viscosity structure of the mantle interior strongly affected intraplate stress regimes, and the combination of increased viscosity in the lower mantle and the low-viscosity asthenosphere enhanced the pure strike-slip faulting regime within moving plates as indicated using visco-plastic rheology. The temporally averaged toroidal-poloidal ratio (T/P ratio) at the top surface of mantle convection with surface plate-like motion and the mantle’s viscosity stratification may be comparable to the observed T/P ratio of present-day and past Earth. The normal faulting (or strike-slip) regime with a strike-slip (or normal faulting) component, as well as the pure strike-slip faulting regime, were broadly found in the stable parts of the plate interiors. However, the significant dominance of these stress regimes was not observed in the depth profile of the toroidal-poloidal ratio as a remarkable peak magnitude near the top surface of the lithosphere. This result implies that the strike-slip component analyzed in this study does not directly relate to the formation of strike-slip faults that are infinitely narrow plate boundaries compared with the finite low-viscosity boundary obtained from a mantle convection model with visco-plastic rheology. Nonetheless, this first analysis of the stress ratio may contribute to an improved understanding of the intraplate stress reproduced by future numerical studies of mantle convection with further realistic conditions.

How to cite: Yoshida, M.: New analyses of the stress ratio and stress regime in the Earth’s lithosphere from numerical simulation models of global mantle convection, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9132, https://doi.org/10.5194/egusphere-egu22-9132, 2022.

EGU22-11827 | Presentations | TS1.4

A kinematic model for observed surface subsidence above a salt cavern gas storage site in Northern Germany 

Henriette Sudhaus, Alison Larissa Seidel, and Noemi Schulze-Glanert

In nation-wide radar satellite time series data of Germany, a linear subsidence motion of several kilometer spatial wavelength shows up south-east of Kiel, northern Germany. The center region of this signal, showing line-of-sight displacement velocities of about 2 mm/a, coincides with the facilities of a gas storage site managing two in-service and one out-of-service caverns in the salt dome beneath. The three caverns have been water-drilled only a few hundred meters apart in 1971, 1996 and 2014 into a large halite salt dome, which has risen up there to depths of around 1000 m. Their sizes range within a couple of 100.000 m³. Above the salt body thick deposits of mainly chalk, silk and claystone below layers of clays, silts, sands and glacial marls in the upper 200 m form a relatively strong roof layer.

We hypothesize that despite a thick and competent cover layer, the long-term ductile behavior of halite, which evidently causes shrinking of the cavern volumes through time, results in the observed continuous surface subsidence across several square kilometers. We present an attempt to test the hypothesis by optimizing a simple kinematic model to fit the surface subsidence signal. Using equivalent body forces to represent an isotropic volume point source embedded in a viscoelastic host medium below a horizontally layered elastic roof medium, we estimate the horizontal position of a single cavern, its depth and the corresponding volume change at the cavern. The medium properties at the cavern sites are well known from borehole geophysical analyses, but likely vary strongly laterally. We use InSAR time series data from two ascending look directions and two descending.

Our results show that a cavern at about 1200 m depth and in very close proximity to above-ground facilities of the storage site can indeed be associated with the observed ground motion. The best-fit models pin the location to the known positions, also in depth. The estimated volume loss is slightly larger than 20.000 m³ per year and is in the same order of volume loss estimated from volume measurements inside the actual caverns.

The model approach we present, a single kinematic point source for three caverns and a one-dimensional medium model, is simple, the signal-to-noise ratio of the satellite data is rather small and furthermore there are considerable spatial gaps in the InSAR time series data in areas of agriculture and forests. However, with a computationally fast forward calculation of surface displacements we can afford to propagate data error statistics that account for spatially correlated errors to model parameter uncertainty estimates in a Bayesian way through model ensembles. We plan to add modeling errors of the medium to better grasp their potential influence on the volume loss estimations. The optimization code we use, Grond, is part of the seismological open-source software toolbox Pyrocko (pyrocko.org). The data is openly available at bodenbewegungsdienst.bgr.de.

How to cite: Sudhaus, H., Seidel, A. L., and Schulze-Glanert, N.: A kinematic model for observed surface subsidence above a salt cavern gas storage site in Northern Germany, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11827, https://doi.org/10.5194/egusphere-egu22-11827, 2022.

EGU22-11830 | Presentations | TS1.4

Geomechanical explanation of the Enguri power tunnel leakage 

Thomas Niederhuber, Birgit Müller, Thomas Röckel, Mirian Kalabegishvili, Frank Schilling, and Bernd Aberle

The Enguri Dam (Georgia) is one of the highest arch dams in the world, located at Enguri river in the Greater Caucasus. A 15 km long pressure tunnel with a slope of 1.1 % connects the reservoir to the power station. The tunnel was initially flooded in 1978 and takes a flow rate of up to 450 m³/s. Annual water level changes in the reservoir reach 100 m and generate variable internal water pressure, which places a considerable and dynamic strain on the structure. Water losses of more than 10 m³/s required extensive rehabilitation work in 2021.

The pressure tunnel is lined by upper and lower concrete parts separated by longitudinal construction joints. During the rehabilitation in spring 2021, an approximately 40 m long section of a construction joint with a gaping fissure and several smaller cracks were located.

To explain why only one of the construction joints was leaking, we combined field observations with numerical modelling of the stress state around the pressure tunnel. To infer the regional tectonic stress field various stress indicators have been used like borehole observations (borehole televiewer data) in the field, hydraulic fracturing and earthquake focal mechanisms. These different methods provide mean values with standard deviations. This enabled the estimation of uncertainties in the model input data (field data).

Our approach is based on a static linear-elastic 2D model of the tunnel at km 13.7 within a limestone of homogeneous material properties. The orientation of the profile section is parallel to the regional maximum horizontal stress (SH), which corresponds to maximum principal stress in a thrust faulting regime. SV is the vertical stress. To account for uncertainties, the model was calculated for different stress state scenarios e.g. variation of SH/SV-ratio from 2 to 6 and internal pressure from 0 to 1.6 MPa.

The results show a symmetrical distribution of tensile and compressive stresses around the tunnel, with the axis of symmetry tilted by ca. 30° clockwise (in flow direction) for all scenarios. This is due to the high topography. Therefore, in some calculations, tangential tensile stresses are observed on the downslope side in the region of the construction joint, while compressive stresses are expected for the upslope construction joint.

Therefore, it can be concluded:

(A) the initial stress state is an important parameter for the positioning of underground installation like pressure tunnels especially in areas of high topography.

(B) geomechanical numerical modelling can help to design and dimension safe constructions.

These kinds of investigations can help to omit leakage which can lead to a reduction of the capacity of the power plant and to prolongate the integrity of the tunnel statics. Further investigations could consider the hydraulic situation of the karst rock in the surrounding of the tunnel.

How to cite: Niederhuber, T., Müller, B., Röckel, T., Kalabegishvili, M., Schilling, F., and Aberle, B.: Geomechanical explanation of the Enguri power tunnel leakage, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11830, https://doi.org/10.5194/egusphere-egu22-11830, 2022.

EGU22-11879 | Presentations | TS1.4

Optimizing the use of InSAR observations in data assimilation problems to estimate reservoir compaction 

Samantha S.R. Kim, Femke C. Vossepoel, Marius C. Wouters, Rob Govers, Wietske S. Brouwer, and Ramon F. Hanssen

Hydrocarbon production may cause subsidence as a result of the pressure reduction in the gas-producing layer and reservoir compaction. To analyze the process of subsidence and estimate reservoir parameters, we use a particle method to assimilate Interferometric synthetic-aperture radar (InSAR) observations of surface deformation with a conceptual model of reservoir. As example, we use an analytical model of the Groningen gas reservoir based on a geometry representing the compartmentalized structure of the subsurface at the reservoir depth.

The efficacy of the particle method becomes less when the degree of freedom is large compared to the ensemble size. This degree of freedom, in turn, varies because of spatial correlation in the observed field. The resolution of the InSAR data and the number of observations affect the performance of the particle method.

In this study, we quantify the information in a Sentinel-1 SAR dataset using the concept of Shannon entropy from information theory. We investigate how to best capture the level of detail in model resolved by the InSAR data while maximizing their information content for a data assimilation use. We show that incorrect representation of the existing correlations leads to weight collapse when the number of observation increases, unless the ensemble size growths. However, simulations of mutual information show that we could optimize data reduction by choosing an adequate mesh given the spatial correlation in the observed subsidence. Our approach provides a means to achieve a better information use from available InSAR data reducing weight collapse without additional computational cost.

How to cite: Kim, S. S. R., Vossepoel, F. C., Wouters, M. C., Govers, R., Brouwer, W. S., and Hanssen, R. F.: Optimizing the use of InSAR observations in data assimilation problems to estimate reservoir compaction, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11879, https://doi.org/10.5194/egusphere-egu22-11879, 2022.

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