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GM – Geomorphology

EGU24-19206 | Orals | MAL21-GM | Ralph Alger Bagnold Medal Lecture

The Neogene record of Himalayan erosion in the Bengal Fan 

Christian France-Lanord, Albert Galy, Valier Galy, Pascale Huyghe, Jérôme Lavé, Sébastien Lenard, Mara Limonta, Thomas Rigaudier, Volkhard Spiess, and Aswin Tachambalath

Over the Tertiary, the uplift of the Himalaya combined to the development of the monsoon generated the largest erosion basins of the planet. More than 80% of the erosion is exported to the Bay of Bengal by the Ganga-Brahmaputra river system and generates turbidity currents which convey detrital sediment building the Bengal Fan. In the modern Himalaya, the monsoon rainfall and tectonic processes shape the erosion pattern. The monsoon seasonal precipitation ensures efficient transport of sand-rich sediments in the basin despite long distances through a very flat floodplain and delta. Rapid transport also acts as a limiting factor for weathering as it reduces residence time in the floodplain but favors efficient carbon burial.

The IODP Expedition 354 drilled the Bengal Fan with seven sites over a 320 km E-W transect at 8°N. This construcs a composite sedimentary record of Himalayan erosion over the Neogene and Quaternary. Sediments are predominantly composed of turbidites generated from the Ganga-Brahmaputra delta. Turbiditic sediments show mineralogical, geochemical and isotopic characteristics which reveal a close analogy with those of the modern Ganga-Brahmaputra river. Sand deposition is dominant and is present in several meters thick sand lobe as well as in levee turbidite (Bergmann et al. 2020). Sand was used to determine average erosion rates of the Himalaya using quartz in situ concentrations of cosmogenic 10Be. Those show stable rate in spite of the onset of a more unstable climate from the Pliocene to the Pleistocene (Lenard et al. 2020).

Major element concentrations and Sr-Nd isotopic compositions of turbidite samples reflect combined effects of geological sources exposed to erosion, weathering and mineral sorting during transport. Deciphering these controls, based on the comparison between turbidite samples and modern river sediments of the Ganga and Brahmaputra basin reveals evolution from Miocene to present. Changes appear in the abundance of detrital carbonates likely reflecting decreasing exposition of the Tethys Himalaya to erosion since Miocene. Clear increase in the silicate Na and Ca concentrations from Miocene to Pleistocene indicates major change in the weathering conditions in the basin which can be related to longer residence time of the sediment in the floodplain and lower erosion ratesin the Miocene.

Bergmann et al. 2020, G. cube 10.1029/2019gc008702
Lenard et al. Nat Geosc. 2020, doi:10.1038/s41561-020-0585-2

How to cite: France-Lanord, C., Galy, A., Galy, V., Huyghe, P., Lavé, J., Lenard, S., Limonta, M., Rigaudier, T., Spiess, V., and Tachambalath, A.: The Neogene record of Himalayan erosion in the Bengal Fan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19206, https://doi.org/10.5194/egusphere-egu24-19206, 2024.

EGU24-6103 | ECS | Orals | GM1.1 | Highlight | GM Division Outstanding ECS Award Lecture

Going beyond the river long profile 

Fiona Clubb

Quantifying landscape form can provide crucial insight into the interactions between tectonics and climate. River long profile morphology, quantified by metrics such as channel steepness, is the most commonly used tool to investigate topographic form, with many studies relating long profile morphology to uplift rate, precipitation, sediment properties, or lithology, for example. River long profiles record the signal of external forcing over large spatial scales (i.e. tens of kilometres). This has many advantages: for example, it is a convenient scale for analysing variations in large-scale processes, such gradients in tectonic uplift. It also means that high resolution digital elevation models (DEMs) are not required and therefore river long profiles can be extracted globally. However, analysis of river long profiles over tens of kilometres can also result in signal smoothing and subsequent loss of finer scale tectonic or climatic signatures encoded into the landscape.

Tectonic and climatic processes do not only leave their fingerprint in the long profiles of rivers. Hilltops, hillslopes, and valleys make up the majority of Earth’s landscapes by area, yet their morphology has received much less attention than that of rivers. This is in part due to the difficulty in accurately extracting hilltops and valley morphology from DEMs, especially on a global scale. Here, I show that we can now extract hilltop and valley metrics from high-resolution (< 15 m) DEMs over orogenic to continental scales using new topographic analysis techniques and high-performance computing facilities. I argue that by combining hilltop, hillslope, and valley metrics, we can obtain more information about tectonic and climatic processes than from river profiles alone.

How to cite: Clubb, F.: Going beyond the river long profile, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6103, https://doi.org/10.5194/egusphere-egu24-6103, 2024.

GM1 – General Geomorphology

EGU24-849 | ECS | Orals | GM1.1

Characterization of channel-fill deposits in coastal wetlands 

Davide Tognin, Alice Puppin, Massimiliano Ghinassi, Andrea D'Alpaos, and Alvise Finotello

Tidal channels are key players in ecogeomorphological dynamics of coastal wetlands, controlling the exchange of water, sediment and nutrient fluxes between low-lying coastal areas and the open sea. Traditionally seen as stable features, the importance of migrating and abandoned channels has been often overlooked. Yet, the constant evolution of tidal channels significantly influences sediment reworking in coastal wetlands and reduced flow velocities within abandoned channels promote particle settling thus rapidly storing large volumes of sediment. Moreover, reach abandonment may lead to the reorganization of the channel network, thus leading to sudden changes in flux dynamics at the basin scale. Hence, the characterization of channel-fill deposits is a critical step for a better understanding of the mechanisms that lead to channel abandonment and consequent network reorganization.

To this aim, we conducted a detailed analysis of the sedimentary features and the related depositional processes in abandoned tidal channels in the microtidal Venice Lagoon, Italy. We collected undisturbed sedimentary cores within abandoned channels identified from aerial images taken in the last 70 years. Cores were longitudinally cut and photographed for classical sedimentary facies analysis and identification of the main depositional environments. Cores were then subsampled at 5 cm intervals and prepared for different laboratory analyses, including organic matter estimation through Loss-On-Ignition and particle size distribution using laser diffractometry.

By combining facies and laboratory analyses, different depositional environments can be readily identified and characterized. The deposits accumulated during the channel abandonment phase are usually floored by a layer rich in shell and shell fragments related to the channel lag, which in most cases overlies sandy-laminated tidal flat deposits. Instead, channel-fill deposits consist of dark grey, organic-rich mud without any visible sedimentary structures. Massive mud can be locally mixed with very fine sand, and close to the lag they tend to become richer in coarser fractions. Moreover, channel-fill deposits are characterized by abundant submillimetric vegetation debris and by an almost constant organic matter content all along the deposit thickness. Our analysis provides a distinctive characterization of the features of channel-fill deposits and is foundational to the comprehension of the processes that lead to channel abandonment and infill.

How to cite: Tognin, D., Puppin, A., Ghinassi, M., D'Alpaos, A., and Finotello, A.: Characterization of channel-fill deposits in coastal wetlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-849, https://doi.org/10.5194/egusphere-egu24-849, 2024.

EGU24-6103 | ECS | Orals | GM1.1 | Highlight | GM Division Outstanding ECS Award Lecture

Going beyond the river long profile 

Fiona Clubb

Quantifying landscape form can provide crucial insight into the interactions between tectonics and climate. River long profile morphology, quantified by metrics such as channel steepness, is the most commonly used tool to investigate topographic form, with many studies relating long profile morphology to uplift rate, precipitation, sediment properties, or lithology, for example. River long profiles record the signal of external forcing over large spatial scales (i.e. tens of kilometres). This has many advantages: for example, it is a convenient scale for analysing variations in large-scale processes, such gradients in tectonic uplift. It also means that high resolution digital elevation models (DEMs) are not required and therefore river long profiles can be extracted globally. However, analysis of river long profiles over tens of kilometres can also result in signal smoothing and subsequent loss of finer scale tectonic or climatic signatures encoded into the landscape.

Tectonic and climatic processes do not only leave their fingerprint in the long profiles of rivers. Hilltops, hillslopes, and valleys make up the majority of Earth’s landscapes by area, yet their morphology has received much less attention than that of rivers. This is in part due to the difficulty in accurately extracting hilltops and valley morphology from DEMs, especially on a global scale. Here, I show that we can now extract hilltop and valley metrics from high-resolution (< 15 m) DEMs over orogenic to continental scales using new topographic analysis techniques and high-performance computing facilities. I argue that by combining hilltop, hillslope, and valley metrics, we can obtain more information about tectonic and climatic processes than from river profiles alone.

How to cite: Clubb, F.: Going beyond the river long profile, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6103, https://doi.org/10.5194/egusphere-egu24-6103, 2024.

EGU24-6586 | ECS | Orals | GM1.1

Observations from a constantly changing nearshore zone in a mixed sediment bay  

Dominique Townsend, Julian Leyland, Hachem Kassem, Charlie Thompson, and Ian Townend

There has been limited exploration of the nearshore zone of mixed sediment beaches despite being widespread globally.  Our work aims to build a more complete picture of coastal change by looking at seabed evolution from the very upper reaches of the swash zone, down to the edge of the nearshore zone, at a variety of timescales. Bathymetry surveys, completed using both traditional and automated surface vessels collected single and multibeam sonar data over a 19-year period, were complimented by a shorter period of weekly radar sea surface roughness images which are indicative of nearshore bed morphology. Additionally, grab samples were collected from across the nearshore to show the bed sediments composition variation over a year, providing valuable insight on bed response to varying hydrodynamic conditions. Process based analysis gave long and cross shore drift rates to help understand the observed changes. 

We found that the nearshore zone experiences significantly larger volumetric bed changes in comparison to the upper beach but were limited to approximately +/-0.3 m, which is equivalent to the upper error limits of the surveyed data. The depth of closure, a term used to mark the offshore point of no change over a defined time scale, varied across the mixed sediment bay at both seasonal  (ranging between –4.7 and –8.4 metres Ordnance Datum(mOD)) and decadal (ranging between –7.3 and –8.2 mOD) timescales, yet was consistently shallower than all predictive equations of this depth. Moreover, our results indicate a loss of volume in the nearshore zone over time which is coupled with a simultaneous steepening of the upper beach for two thirds of the frontage.  The observed steepening poses questions for the current ‘hold the line’ management strategy, which is achieved through active beach management works, and accommodation space.  

Overall, our observations highlight the substantial sediment transport occurring within the predominantly sandy nearshore zone and demonstrate evidence of impacts to the upper shingle beach. Consequently, to ensure the sustainability of management practices in the upper beach, a comprehensive understanding of the nearshore dynamics becomes imperative. The presented findings emphasize the necessity of integrating nearshore considerations into coastal management strategies, providing a more holistic and effective approach to making sustainable management decisions. 

How to cite: Townsend, D., Leyland, J., Kassem, H., Thompson, C., and Townend, I.: Observations from a constantly changing nearshore zone in a mixed sediment bay , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6586, https://doi.org/10.5194/egusphere-egu24-6586, 2024.

EGU24-15791 | ECS | Orals | GM1.1

Using single-grain feldspar luminescence signal and modelling to study landscapes erosion rates and sediment transport 

Anne Guyez, Stephane Bonnet, Sebastien Carretier, Clare Wilkinson, Tony Reimann, Kevin Norton, and Jakob Wallinga

Luminescence is a powerful dating technique that is increasingly being used as a new tool to investigate surface processes. In the past decade, it has been used successfully for instance to estimate virtual sediment velocity in rivers, sediment storage time in floodplains, and to trace sediment sources (McGuire & Rhodes, 2015; Gray et al., 2018; Sawakuchi et al., 2018; Guyez et al., 2022; Guyez et al., 2023). As part of ongoing development, here we quantify sediment transport and catchment-wide erosion rates in natural systems using luminescence. For this purpose, single-grain post infrared-infrared (pIRIR) equivalent doses of felspars from modern floodplain deposits were measured in several catchments in the Southern Alps of New Zealand and compared to catchment-wide erosion rates derived from 10Be cosmogenic nuclide concentrations measured in fluvial quartz grains.

The fraction of grains that were well-bleached before their burial in the modern floodplain was calculated, as well as the fraction of grains with a saturated luminescence signal. Signal distribution was characterised using the central age model.

Our findings indicate that the luminescence signal is characterized by few well-bleached grains and lots of grains with a high luminescence signal where erosion rates are high. On the other hand, in catchments with lower erosion rates, bleaching appears to be more pervasive, resulting in an overall lower luminescence signal. Therefore, we hypothesize that bleaching efficiency is related to erosion rates.

To test the relationship between luminescence, bleaching, erosion, and transport processes, we include the luminescence signal of individual grains in a landscape evolution model that already takes into account the concentration of cosmogenic nuclides (Carretier et al., 2023). By tracking both signals in an evolving stream basin, the model helps better understanding the relationship between erosion and luminescence signal, on longer time scales. Single-grain pIRIR equivalent holds promise as a new method for measuring erosion and sediment transport.

How to cite: Guyez, A., Bonnet, S., Carretier, S., Wilkinson, C., Reimann, T., Norton, K., and Wallinga, J.: Using single-grain feldspar luminescence signal and modelling to study landscapes erosion rates and sediment transport, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15791, https://doi.org/10.5194/egusphere-egu24-15791, 2024.

EGU24-15955 | ECS | Orals | GM1.1

Identifying sediment-discharge event types with a data-based clustering approach 

Amalie Skålevåg, Oliver Korup, and Axel Bronstert

Suspended sediment poses a risk to human and natural systems in terms of compromising water quality, flood hazard, hydropower production, and aquatic habitats. In many rivers the bulk of annual suspended sediment yield is mobilised and transported during (extreme) episodic runoff. Understanding such sediment-discharge events, including their drivers, may inform management strategies aimed at mitigating potential detrimental effects. Event-based analysis of local time series of suspended sediment transport has become a common approach to infer the dominant drivers and processes of sediment dynamics at the catchment scale. The increasing availability of detailed and continuous monitoring time series data enables us to use machine-learning techniques to identify groups of similar events, i.e. event types, and test whether and how these groups reflect similar catchment conditions and hydro-meteorological drivers. 

We present an approach which automatically detects, characterises and clusters sediment-discharge events. Hydrograph separation is used to automatically detect events, which are then filtered based on suspended sediment magnitude. The detected events are subsequently characterised with a selection of metrics, which are transformed into uncorrelated event characteristics with principal component analysis. Based on these characteristics events are clustered using a Gaussian mixture model. Finally, the identified event types are interpreted using catchment metrics describing antecedent conditions, hydrometeorological forcing, and catchment freezethaw state and snowcover.

Applying our approach to a high alpine, glaciated catchment we find that the event regime in the catchment is mainly defined by event magnitude, hysteresis and event shape complexity. However, for the clustering suspended sediment and streamflow magnitude, and event shape complexity are the most important factors, whereas sediment discharge hysteresis is less relevant. The four identified event types are attributed to (1) compound rainfall-melt extremes, (2) glacier and seasonal snow melt, (3) freezethaw-modulated snow-melt and precipitation events, and (4) late season glacier melt. 

Our approach enables event-based analysis of riverine sediment fluxes, by detecting and grouping similar events together, which can in turn be interpreted to understand under which conditions episodic sediment fluxes occur in the target catchment.

How to cite: Skålevåg, A., Korup, O., and Bronstert, A.: Identifying sediment-discharge event types with a data-based clustering approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15955, https://doi.org/10.5194/egusphere-egu24-15955, 2024.

EGU24-20657 | ECS | Orals | GM1.1

UAV-based tracking of floating wood during a flood  

Janbert Aarnink, Florent Rouge, Aldo Fornari, and Virginia Ruiz-Villanueva

Floods in mountain rivers cause significant geomorphic changes and may entrain and transport large quantities of sediment and wood (uprooted trees). Although large wood contributes to healthy river ecosystems by providing and forming habitats for various species, it can also pose additional risks. In particular, the wood can block critical infrastructure. Governed by its density, the buoyancy of wood allows it to float and generally move at a velocity similar to the river flow. However, wood movement is complex due to interactions with the flow and the influence of turbulence and drag forces. Moreover, contact with other wood pieces can alter the forces on the floating wood. Observations of wood transport during floods are very rare, and this study aims to address this by monitoring the motion of wood during large-scale experimental floods in the Spöl River. 

The Spöl River, partially situated in the Swiss National Park, is controlled by two upstream dams, the Punt dal Gal and Ova Spin. As part of a restoration project, the company responsible for the dams releases environmental floods annually. This study monitored the movement of floating wood pieces entrained during these releases using a combination of methods. 

During the flood in June 2023, three drones were flown simultaneously. Each drone flew a maximum of 15 minutes, which was done five times between 09:30 and 11:45 in the morning. Each drone captured 24 frames per second with a resolution of 3840x2160 pixels. At an average height of 60 meters, this resulted in an average pixel size of 2.3 centimetres. Also, 6 topographical cross-sections, distributed over the observed river section were taken before and after the flood. 

The flood caused important geomorphic changes along the riverbed. In some of the surveyed sections, erosion was significant, whereas in others, aggradation was the dominant process. The video footage included approximately 90 pieces of floating large instream wood with and average length of 3 meters. When comparing the wood movement with the cross-sections, we observed that the wood pieces did not necessarily follow the river thalweg or deepest part of the channel. Local morphology, flow velocity and turbulence played a large role in the wood trajectory. In addition, the size, trajectory and rotation of wood are being analysed and compared with the flow field and local topography. 

 

This study provides unique insights into the behaviour of individual floating wood pieces transported during a flood. The findings will be valuable for comparison with numerical models and will help improving our understanding of large wood dynamics in rivers. 

 

This work is funded by the Swiss National Science Foundation project PCEFP2_186963, and supported by the University of Lausanne, the Swiss Academy of Sciences, the Swiss National Park, and the Engadiner Kraftwerke.

How to cite: Aarnink, J., Rouge, F., Fornari, A., and Ruiz-Villanueva, V.: UAV-based tracking of floating wood during a flood , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20657, https://doi.org/10.5194/egusphere-egu24-20657, 2024.

EGU24-4165 | ECS | Posters on site | GM1.2

The highest gas hydrate volume estimate found in the sediments of the Chilean margin 

Lucia Villar-Munoz, Ivan Vargas-Cordero, Umberta Tinivella, Michela Giustiniani, Joaquim P. Bento, Nathan Bangs, and Eduardo Contreras-Reyes

Along the Chilean continental margin, where the active Nazca plate subducts under the South American plate, large deposits of gas hydrates trapped in marine sediments can be observed in seismic profiles (from Valparaíso to Patagonia), which may be affected by the increase in deep-water temperature due to climate change. This could trigger a massive release of methane gas into the marine environment and the atmosphere with negative effects on the environment, mainly through dissociation of the hydrates and/or direct migration to the seafloor through faults.

In this study, new multichannel seismic data located off Chiloé Island (∼42°S) are presented, and for the first time a BSR parallel to the continental margin (north-south) is analysed. Here, an efficient sediment subduction occurs where the young oceanic Nazca plate (5-25 Ma) subducts beneath the continental plate along Chiloé Island. In addition, an integrated analysis to better understand the hydrological and hydrothermal system in this area included previous geophysical and geological datasets, such as a) bathymetry, b) geothermal gradient calculated from gas hydrate distribution boundaries, and c) thermal conductivities. 

The results show a continuous and strong BSR along the entire seismic profile MGL1701-27 (approximately 27 km long), where large deformations, fractures and faults occur, favouring the flow of carbon-rich fluids from the depths, which subsequently form the gas hydrate layer. The large amount of gas hydrate present in the marine sediments off the coast of Chiloé Island is impressive. Velocity analysis of seismic profile MGL1701-27 indicates gas hydrate concentration values of up to 25% of the total rock volume, the highest estimates obtained at the Chilean margin. In addition, a peak in the geothermal gradient is related to deep faults that allow the passage of hot fluids from deeper strata to the seafloor.  Finally, a large amount of free gas is estimated beneath the BSR, which enhances its intensity and continuity in the seismic profile.

Our results provide valuable information for current and future studies related to climate change (methane storage), hydrothermal circulation, seismicity, gas hydrate stability and fluid venting in this natural laboratory, since Chiloé Island is located at the southern boundary of the rupture zone of the largest earthquake in recorded history (the Mw 9.5 Valdivia earthquake), the implications of which have yet to be fully elucidated.

How to cite: Villar-Munoz, L., Vargas-Cordero, I., Tinivella, U., Giustiniani, M., P. Bento, J., Bangs, N., and Contreras-Reyes, E.: The highest gas hydrate volume estimate found in the sediments of the Chilean margin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4165, https://doi.org/10.5194/egusphere-egu24-4165, 2024.

EGU24-4166 | Posters on site | GM1.2 | Highlight

Paleoenvironmental and geomorphological changes in an ancient baldcypress swamp preserved on the Northern continental shelf in the Gulf of Mexico 

Andy Reese, Kristine DeLong, Grant Harley, Katie Garretson, Andrea Garcia, Kevin Xu, Kelli Moran, Kendall Broome, and Ellen Bergan

Wave action and seafloor scouring, likely from Hurricane Ivan, exposed an area of baldcypress (Taxoidum distichum) stumps, still in growth position and rooted in terrestrial soil, on the northern continental shelf of the Gulf of Mexico.  This site, known as the Underwater Forest, is located roughly 10 km off the coast of Gulf Shores, Alabama, USA, in approximately 18m of water.  Radiocarbon and optically stimulated luminescence dates from the mud/peat sections of the cores suggest a baldcypress swamp existed between approximately 70-40 ka BP (MIS 3-4) during the Würm glaciation.  Multiproxy analysis of sediments suggests significant geomorphological changes occurred to this backswamp environment overtime, which significantly impacted vegetation assemblage of the area.  Pollen evidence shows a clear transition from a baldcypress/tupelo gum (Nyssa aquatica) community to an alder (Alnus) dominated bar community.  This change suggests a transition to a braided river system, though it remains unclear whether these geomorphological changes resulted from terrestrial sources, marine transgression, or a combination of both.  The final vegetation change is to a more open, marsh environment resulting from sea-level rise.  Tree-ring analysis of the stumps suggest a synchronous death event, likely by burial, which may have also preserved the site.

How to cite: Reese, A., DeLong, K., Harley, G., Garretson, K., Garcia, A., Xu, K., Moran, K., Broome, K., and Bergan, E.: Paleoenvironmental and geomorphological changes in an ancient baldcypress swamp preserved on the Northern continental shelf in the Gulf of Mexico, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4166, https://doi.org/10.5194/egusphere-egu24-4166, 2024.

EGU24-6076 | ECS | Posters on site | GM1.2

Ribbed Moraines and Generalised Linear Modelling: Can modelled ice conditions be used to predict the presence of specific landforms?   

Thomas James Barnes, Karianne Staalesen Lilleøren, Thomas Vikhamar Schuler, and Louise Steffensen Schmidt

In this study, we investigate the relationship between subglacial conditions and the presence of ribbed moraines in Norway. Ribbed moraines are low-lying subglacially formed ridges, transverse to glacial flow and numerous processes have been proposed to explain their formation. So far there is no agreement about the formation process but most of them are linked to the presence of subglacial water. We therefore hypothesise that there is a relationship between hydrological conditions at the bed of the Fennoscandian Ice Sheet, and the presence of ribbed moraines. To test this, we extract subglacial conditions from a numerical model of the Fennoscandian Ice Sheet and derive further modelled hydrological conditions using a MATLAB-based hydrological toolbox. Our conditions include: (i) subglacial hydrological sinks, (ii) subglacial hydraulic head, (iii) flow accumulation, (iv) ice thickness, (v) ice-flow velocity, and (vi) basal temperature. We use these data in a presence-absence generalised linear modelling approach, to evaluate the coexistence of ribbed moraines and specific conditions. From this we can infer whether they have a consistent series of conditions which determine their presence. We focus on two areas, a training dataset in Vinstre, South-Central Norway, and a validation dataset in Femunden, Central-Eastern Norway. These sites cover known and well mapped areas of ribbed moraines, which are used as ground truth data. Comparison is possible through superimposing presence-absence predictions on the ground truth data in GIS as a pair of gridded, spatially referenced datasets. In comparing the model output to ground truth data, we aim to provide new assessments of the validity of the many ribbed moraine formation theories. For example, if hydrological conditions prove a poor predictor, then we can consider the presence of water as less likely a prerequisite for the formation of ribbed moraines. 

How to cite: Barnes, T. J., Lilleøren, K. S., Schuler, T. V., and Schmidt, L. S.: Ribbed Moraines and Generalised Linear Modelling: Can modelled ice conditions be used to predict the presence of specific landforms?  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6076, https://doi.org/10.5194/egusphere-egu24-6076, 2024.

EGU24-12134 | ECS | Posters on site | GM1.2

High-resolution fluvial geomorphology of dynamic volcanic environments of Costa Rica, Central America 

Jing Cui, Sebastián Granados, and Nicola Surian

Costa Rica is a small humid tropical country with an extension of 51,179 km2, it has an extensive network of diverse streams and rivers controlled by diverse environmental and geological conditions. Rugged terrain, active volcanism, and tectonic activity, along with intense and frequent precipitation, result in a dynamic drainage system characterized by a wide array of erosive and depositional fluvial landforms. Over 33% of Costa Rica’s territory is composed of Quaternary-Pleistocene volcanic landforms. These dynamic and high sediment source environments play a crucial role in the economy and society of the country. From the energy supply point of view, over 70% of the country’s electricity generation comes from hydropower plants located within volcanic formations. Mountain and highland volcanic areas are also the main source of drinking water for most of the population that live in the central part of Costa Rica.

Using remote sensing techniques (UAV photogrammetry and satellite imagery), bidimensional hydraulic modelling and raster analysis we analyzed with high-resolution (<1m/pixel) five fluvial-volcanic environments with different environmental conditions: (i) the effects of explosive phreatic eruptions on the channel morphology of the Pénjamo River located on the Rincón de la Vieja Volcano; (ii) severe bank erosion caused by an extreme precipitation event that damaged multiple structures along the Turrialba River, Turrialba Volcano; (iii) alluvial fan geomorphology of the Reventado River and it’s hazard implications to Cartago City, Irazú Volcano; (iv) confined urban streams and vegetation connectivity analysis of San José City, Irazú Volcano; (v) river dynamics and channel morphology  in extinct Pleistocene volcanic formations, San Lorencito River.

The use of the high-resolution assets allowed us to get novel insights on how channel morphology is composed in these extremely dynamic environments. Also, analyze how channels adjust to high sediment yield due to climatic or eruptive events. Some main outcomes of our research show that: (i) rivers in these steep environments flow confined mostly with single-thread morphologies and coarse sediments (boulders); (ii) volcanic phreatic eruptions generated hyperconcentrated flows (lahars) that caused severe bank erosion; (iii) vegetation in confined urban rivers play a key role in ecosystem management and environmental development; (iv) rivers that flow from active volcanoes transport extreme amounts of sediments and represent a major hazard for populated areas of Costa Rica.

Our results contribute to a better understanding of how river dynamics function under diverse volcanic environments of the country. Since over 40% of the country’s population lives within volcanic formations the data we provide contributes for a better environmental and risk assessment.

 

How to cite: Cui, J., Granados, S., and Surian, N.: High-resolution fluvial geomorphology of dynamic volcanic environments of Costa Rica, Central America, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12134, https://doi.org/10.5194/egusphere-egu24-12134, 2024.

EGU24-12871 | ECS | Posters on site | GM1.2

Global Distribution of Mountainous Headwater Catchments Morphology 

Pengfei Wu, Jintao Liu, and Vincenzo D'Agostino

Mountainous regions are important headwater regions to sustain environmental and human water demands. The morphologies of these headwater catchments control their hydrological response and affect the water supply to downstream. In this study, more than 3.3×107 headwater catchments are extracted. These cover most of the mountainous regions between 60°S and 60°N and their areas range from 0.5 km2 to 2 km2. Several morphological features closely related to hydrological response and sediment dynamics, such as width function and Melton number, are estimated for the catchments. Particularly, in order to ensure the accuracy of the estimated parameters, two new algorithms are developed, including an improved triangular form-based multiple flow direction algorithm as well as a width function algorithm based on a two-segmented-distance strategy and the multiple equidistant belt technique. Subsequently, a dataset of mountainous headwater catchment morphology is generated by adding the climatic and tectonic features corresponding to each catchment. This dataset can help to identify the hydrological similarities between different headwater catchments, which is important for determining the parameters of hydrological models in ungauged catchments. We analyze the relationship between the catchment morphology features and tectonics (e.g., shortening rate) as well as climate variables (e.g., precipitation and temperature). The results show that great differences exist in catchment morphology between tectonically active areas and inactive areas. Furthermore, the relationship between morphology and climatic variables varies depending on the lithology of the region, with the strongest correlation observed in sedimentary regions.

How to cite: Wu, P., Liu, J., and D'Agostino, V.: Global Distribution of Mountainous Headwater Catchments Morphology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12871, https://doi.org/10.5194/egusphere-egu24-12871, 2024.

EGU24-13101 | ECS | Posters on site | GM1.2

Quantifying the response of rivers to Holocene sea level rise in Southern England 

Anya Towers, Mikael Attal, Simon Mudd, and Fiona Clubb

Southern England has been undergoing subsidence since the end of the Last Glacial Maximum due to the Glacial Isostatic Adjustment of the British Isles. Rivers typically respond to subsidence by aggrading, however many rivers along the coast of Southern England incise at their outlet and exhibit river profile convexities typical of systems experiencing a drop in base level. Studies have suggested that coastal erosion could result in such river morphology. Specifically, numerical modelling studies (Leyland and Darby, 2009; Hackney et al., 2014) have shown that it was only in the Late Holocene when small basins experienced significant channel incision at their outlets.  They demonstrated that this was due to the reduction in the rates of sea level rise which enabled knickpoint recession rates to exceed cliff retreat rates.  

Observations and understanding of the geomorphic controls, including both climatic and topographic drivers, on coastal river outlets remain limited, however. For the first time, we examine the spatial distributions of river outlets in Southern England through digital topographic analysis. In regions with similar lithologies and coastal exposure, we find that channels with the smallest basins incise at their mouth while rivers with the largest basins experience aggradation. This signal aligns to model predictions, assuming that the slope of rivers at the coast decreases with increasing basin size. We further explore the role of lithology on knickpoint magnitude and retreat by testing whether more resistant lithologies slow knickpoint retreat rates. Moreover, we investigate the influence of spatial variations in coastal erosion rates on knickpoint morphology, with greater wave heights and subsidence rates documented in the South West. Finally, we examine whether realistic estimates of coastal erosion can be made by reconstructing river profiles before the initiation of subsidence.  This contribution will enhance our understanding of how rivers respond to rising base levels, which is particularly important given the projected sea level rise in Southern England.

How to cite: Towers, A., Attal, M., Mudd, S., and Clubb, F.: Quantifying the response of rivers to Holocene sea level rise in Southern England, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13101, https://doi.org/10.5194/egusphere-egu24-13101, 2024.

EGU24-14468 | Posters on site | GM1.2

Extreme values of central Japan snowfall attributable to global climate change 

Yasuhisa Kuzuha, Yoshihiro Tachibana, and Chiharu Mizuki

1. Objectives and data

To investigate trends of heavy snowfall attributable to climate change, we use maximum snow depth data calculated during 1951–2010 with a climate model (experimentation by present climate). The Japanese hydrological–meteorological community used a climate simulation model to construct a huge database of hydro-meteorological values (https://www.miroc-gcm.jp/d4PDF/index_en.html), designated as d4PDF. It has data calculated under the present climate and data calculated under a future climate, which are affected by global warming. The "T-year value" is a stochastically and statistically estimated hydrological value for which the return period is T years.

2. Extreme values of snowfall

We used hourly snow depth data of d4PDF around Japan. First, we calculated the annual maximum snow depth at each calculation grid. Because this database consists of ensemble calculations of 50 members, data for 3,000 years (60 years × 50 members) are included. We investigated trends of 50-year values for which the return period is 50 years. Specifically, 50-year snowfall and snow depth were estimated. The annual maximum of snow depth at each calculation grid was calculated. Our research theme evaluates the “T-year value” for which the return period is the T-year is itself, but we calculated it using a non-parametric method at this stage as described below.

  • We assume that the population of this database is not stationary. Therefore, for example, for 1951, we use 500 data which consist of data of 10 years (1951–1960) of 50 members.
  • A 50-year value is the tenth largest value among 500 descending data.
  • For 1952–2010, 50-year values are estimated using the same procedure.

3. Result

Figure 1 presents the time variational 50-year-snow-depth at five grid points in central Japan. Figure 2 shows 50-year values of 24 h snowfall as the same grid points. These show no long clear increasing or decreasing trend. However, after 1985, it is apparent that the 50-year-annual maximum snowfall during 24 h decreases slightly.

4. Future work

Although we describe trends of 1951–2010 herein, we can describe some other results we are investigating now, as presented below.

  • Optimal methods for estimating a T-year value require checking for optimal methods among non-parametric methods, methods using annual maxima, and methods using a partial duration series.
  • Although we use only a database for present climate conditions, we will present trends of the near future which are affected by global changes.

 

Figure 1: Time variational 50-year snow depth at five grid points.

 

Figure 2: Time variational 50-year snowfall at five grid points.

How to cite: Kuzuha, Y., Tachibana, Y., and Mizuki, C.: Extreme values of central Japan snowfall attributable to global climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14468, https://doi.org/10.5194/egusphere-egu24-14468, 2024.

EGU24-15831 | ECS | Posters on site | GM1.2

Right for the wrong reasons? On hillslope sediment and the streampower model 

David Litwin, Leonard Sklar, and Luca Malatesta

The streampower law is widely used to model the detachment-limited endmember of bedrock channel evolution, in which rivers set their slope mainly to abrade or pluck material from the channel bed. The model suggests a strong sensitivity of river long profiles to tectonic forcing, local bedrock strength, and climate. This has made it a tool of choice for interpreting these signatures in landscapes, regardless of the applicability of detachment limited erosion. For instance, sediment flux can be a major control on channel slope, as channels steepen to evacuate sediment and maintain their bed elevation, which is neglected by the streampower law.

While this is a well understood limitation, the implications become slightly murkier when the streampower law is used in 2D landscape evolution models that add a diffusion law to capture hillslope processes. We find that channel steepness increases with hillslope length, as channels have to steepen in order to erode the hillslope material added to the valley floor by diffusion processes. We show that this approximates some aspects of a transport-limited fluvial erosion model, but neglects others. Importantly, here channel steepening scales exactly with local hillslope properties, rather than those of the entire upstream watershed that would theoretically supply sediment. This has implications for interpretations of river profiles using chi-analysis and model inversion that rely on a version of the streampower law, especially when working between one-dimensional and two-dimensional approaches. We conclude with some extension of the physical significance of our findings, specifically related to constraints on the relationships between streampower erosivity, hillslope diffusivity, and grainsize.

How to cite: Litwin, D., Sklar, L., and Malatesta, L.: Right for the wrong reasons? On hillslope sediment and the streampower model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15831, https://doi.org/10.5194/egusphere-egu24-15831, 2024.

EGU24-16976 | ECS | Posters on site | GM1.2

Bedrock erosion by hyperconcentrated flows: A quantitative analysis and implications for effective gorge formation 

Verena Stammberger, Benjamin Jacobs, and Michael Krautblatter

Deeply incised bedrock channels can be found in mountain landscapes across the whole globe. The processes controlling this incision and subsequently gorge formation in bedrock have been discussed in the scientific community but have not been directly observed in an actualistic way. Here, we show the results of an unprecedented LiDAR dataset deciphering the erosive power of a 60,000 m3 hyperconcentrated flow (transition of flood and debris flow). We were able to quantify the lateral bedrock erosion in a narrow limestone gorge with channel widths between 1 and 15 m and a total length of 900 m. The flow laterally eroded up to 1 m massive limestone and widened sections by up to 15 %. The influence of sinuosity, convergence and gradient were tested but found not to influence the local erosivity pattern of the rock walls. We show that single hyperconcentrated flows similar to this one could have a major influence on the effectiveness of bedrock incision in comparison to turbulent flows. Here, we provide a new explanation of the processes of rock gorge formation due to mechanically excited breakout of rock fragments in a massive limestone gorge.

How to cite: Stammberger, V., Jacobs, B., and Krautblatter, M.: Bedrock erosion by hyperconcentrated flows: A quantitative analysis and implications for effective gorge formation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16976, https://doi.org/10.5194/egusphere-egu24-16976, 2024.

EGU24-1492 | ECS | Posters on site | ITS4.5/GM1.3

Structural shifts in plant functional diversity during biogeomorphic succession: Moving beyond taxonomic investigations in an alpine glacier foreland 

Stefan Haselberger, Robert R. Junker, Lisa-Maria Ohler, Jan-Christoph Otto, and Sabine Kraushaar

The complex interrelation between plants and geomorphic processes is described in the concept of biogeomorphic succession. While ecological research on succession and community assembly has transitioned towards functional approaches, studies on functional diversity in biogeomorphic settings, particularly in glacier forelands, remain limited.

In this study, we investigated abundance of vascular plant species and functional traits in an alpine glacier foreland using data from 199 plots. Our objective was to unravel the development of functional diversity during biogeomorphic succession. Specifically, the study determined whether structural shifts in functional diversity are associated with stability thresholds related to plant cover, geomorphic activity, and examined trait spectra for stages of biogeomorphic succession.

Our findings revealed a non-linear trajectory of functional diversity along the plant cover gradient, marked by two distinct structural shifts at 30% and 74% cover, corresponding to established stability thresholds. Along the gradient of geomorphic influence, we observed an increase in functional diversity until 54% of the plot area was affected, beyond which functional diversity declined below the initial level. The analysis of community-weighted means of traits across four stages of biogeomorphic succession determined by plant cover and absence and presence of geomorphic influence revealed significant differences in trait values.

In the transition to the biogeomorphic stage, associated with the identified initial structural shift, there is a shift from a prevalence of above-ground adaptation and reproductive traits, such as leaf longevity, structure, growth form, and mixed reproductive strategies, to an increased dominance of competitor species and traits related to below-ground structures, including root type and structures, as well as vegetative reproduction.

Our results contribute to understanding the relationship between vegetation succession and geomorphic influence by linking them to plant functional traits. This study advances beyond traditional taxonomic investigations by emphasizing functional approaches to biogeomorphic succession. Moreover, the functional trait data used in this study, easily downloadable from a public repository, can serve as a valuable template for future research in (bio)geomorphology, along with the employed methodologies.

How to cite: Haselberger, S., Junker, R. R., Ohler, L.-M., Otto, J.-C., and Kraushaar, S.: Structural shifts in plant functional diversity during biogeomorphic succession: Moving beyond taxonomic investigations in an alpine glacier foreland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1492, https://doi.org/10.5194/egusphere-egu24-1492, 2024.

Ecohydrology describes the effects of hydrological processes on ecosystem structure and functioning and the effects of biotic processes on hydrological processes. Recently, there is an increasing emphasis on the role of megafauna, large mammals and birds, on earth system processes, such as nutrient cycling, energy flows and vegetation patterns. Ecohydrology as a field, however, has not yet considered megafauna as central drivers of hydrological processes but focused strongly on the interactions between hydrological processes and plants and soils. Here, we introduce zoohydrology to emphasize the importance of considering the interactions between wild animals and hydrological processes. This includes both the effects of hydrological processes on the occurrence, behavior and life history of animals as well as the effects animals have on hydrology. In this introductory talk, we will outline different pathways through which hydrology affects megafauna and through which megafauna affect hydrological processes using a systems approach. We will illustrate these pathways with concrete examples from different parts of the world and on different species. For example, the importance of hydrological processes and hydromorpho-dynamics for shaping habitats of endangered species, such as the Ganges freshwater dolphin and Bengal tigers in northern India and Nepal, but also for structuring megafauna community dynamics, such as the example of Gorongosa National Park in Mozambique. We will also exemplify how wild animals can affect central hydrological processes in diverse ways; directly (e.g., species such as beaver and hippo as ecosystem engineers of aquatic systems) and indirectly (e.g., elephants that reduce woody cover at large scales, affecting evapotranspiration). Many effects of animals on hydrological processes remain understudied and are often lacking from hydrological models. By introducing the concept of zoohydrology, we stress the potentially pivotal interactions between central hydrological processes, wild animals and their habitats. To unravel the full complexity of these interactions and assess their true importance, zoohydrology must be advocated among scientists, policy makers and practitioners in order to better address biodiversity conservation and restoration, make the concept of environmental flow needs more concrete, and investigate the consequences of biodiversity restoration on hydrological systems.

How to cite: Cromsigt, J., Larsen, A., and Griffioen, J.: An introduction to the concept of Zoohydrology – the interactions between hydrological processes and wild animals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2096, https://doi.org/10.5194/egusphere-egu24-2096, 2024.

EGU24-2302 | ECS | Posters on site | ITS4.5/GM1.3

A holistic analysis of Chinese sponge city cases by region: Using PLS-SEM models to understand key factors impacting LID performance 

Zhou Guo, Xiang Zhang, Ryan Winston, Joseph Smith, Yifan Yang, Shiyong Tao, and Haoyuan Liu

Sponge city is an engineering solution proposed by the Chinese government which aims to deal with urban water issues (e.g., flooding, poor water quality) brought on by climate change and urbanization. Various strategies for sponge city construction are required since environmental constraints differ regionally across the country. To identify regional variations, reveal the inner links between externalities and design elements in sponge city construction, and offer practical suggestions, efforts in two directions are made based on the data of 65 sponge city cases around China, 1) discussing design parameters of four Low Impact Development (LID) facilities, including bioretention cell, permeable pavement, grass swale, and sunken green space, under four regionalization maps of hydrologic, climatic, landform and soil texture factors, and 2) building a holistic Partial Least Squares-Structural Equation Modelling (PLS-SEM) model illustrating the relationship between local characteristics, LID system design, and LID system performance in sponge city construction. The results show that: 1) rainfall and landform factor have great impact on LID facilities design, as the depths tend to be higher in water rich areas and coastal areas. 2) LID types and areas are positively influenced (+0.764) by the total area and permeable portion of a project, and the LID system performance (water quantity and quality control) is negatively impacted (-0.417) by the rainfall amount and clay fraction. 3) In the holistic model, there are no significant links between the LID system design and natural characteristics or LID system performance. It is recommended that different design standards and assessment indexing systems be tailored to local environment when constructing sponge city projects.

How to cite: Guo, Z., Zhang, X., Winston, R., Smith, J., Yang, Y., Tao, S., and Liu, H.: A holistic analysis of Chinese sponge city cases by region: Using PLS-SEM models to understand key factors impacting LID performance, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2302, https://doi.org/10.5194/egusphere-egu24-2302, 2024.

EGU24-3300 | ECS | Posters virtual | ITS4.5/GM1.3

Integration of health indicators and quantification of benefits from BGS urban interventions 

Wenfei Huo, Tasos Temenos, Stanislava Boskovic, and Cedo Maksimovic

    With the growing interest in utilizing Blue-green solutions to mitigate the negative impact of urbanization and climate change, and further enhance human health, it becomes essential to comprehensively understand the extent to which BGS influence human well-being through integrating various indicators. Building upon concepts within the existing framework of the Nature-Based solutions to health theory, this study aims to investigate the changes in heart rate among park users and establish connections between these changes and the benefits brought about by urban green spaces, as well as the potential of integrating wearables to quantify the impact of BGS on human health. The research was conducted at the demo site of the HEART project, the Pedion of Areos Park in Athens. The heart rate data of two participants engaged in walking activities within the park were recorded through wearable devices. By analyzing the associations between factors like the Normalized Difference Vegetation Index (NDVI), air pollutants, temperature with heart rate, as well as the complex interplay of various environmental indicators, this study reveals the positive impact of BGS on human health. The outcomes of quantitative statistical analysis indicate that temperature significantly influences heart rate, while the impact of air pollutants on heart rate is not clearly revealed. The result from spatial analysis further confirms a significant correlation between the increase in NDVI and the reduction in Land Surface Temperature (LST), particularly during the spring season. These research findings demonstrate that heart rate can serve as an effective health indicator to quantify the benefits of BGS. While the generalizability of study results might have limitations, it offers insights into the influence of urban green spaces on human health. In the future, with larger sample sizes, diversified datasets such as GeoHealth data with health status, age, and gender, and long-term observations, we can gain a more comprehensive understanding of these positive impacts, thus providing stronger scientific foundations for urban planning and design. 

How to cite: Huo, W., Temenos, T., Boskovic, S., and Maksimovic, C.: Integration of health indicators and quantification of benefits from BGS urban interventions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3300, https://doi.org/10.5194/egusphere-egu24-3300, 2024.

EGU24-3463 | ECS | Posters on site | ITS4.5/GM1.3

Beavers and flood alleviation: Human perspectives from downstream communities 

Roger Auster, Stewart Barr, and Richard Brazier

The activities of an animal – beavers - are increasingly recognised as a nature-based solution to hydrological extremes; dams and wetlands that beavers create attenuate flows downstream whilst delivering multiple benefits for the environment and for people. There can however also be challenges for people living alongside beavers. Q-Methodology is a technique for eliciting an understanding of human perspectives that exist within a context, enabling a rich understanding of human subjectivity within a context. We used Q-Methodology to elicit an understanding of perspectives that exist about beavers and their role in natural flood management among communities living downstream of three beaver sites in England, where Eurasian beavers (Castor fiber) are currently being reintroduced. Diverse perspectives that exhibited a range of value judgements were identified, including favourable viewpoints which valued multiple benefits beaver activities can provide, as well as less favourable viewpoints with some perceiving a reliance on beaver-led natural flood management to be less predictable and of higher risk than relying upon human-led interventions. In response to our findings, we support a catchment-based approach to beaver management so as to incorporate contextual perspectives in decision-making, and to enable dissemination of knowledge about beaver behaviours within communities. Further, we encourage future research into whether Beaver-Dam Analogues (in-stream structures that mimic beaver dams or their function) could be used as ‘starter dams’ to encourage beaver activities in optimal locations, as this may inspire confidence in beaver-led flood defence by working with the animal to develop a 'right dam in the right place' strategy.

How to cite: Auster, R., Barr, S., and Brazier, R.: Beavers and flood alleviation: Human perspectives from downstream communities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3463, https://doi.org/10.5194/egusphere-egu24-3463, 2024.

EGU24-3786 | Orals | ITS4.5/GM1.3

Nature-based solutions for improving food security: A systematic globalreview 

Loc Ho, Minh Nguyen, Mukand Singh Babel, and Edward Park

Nature-based solutions (NBSs) have been promoted as a holistic way to solve a variety of societal issues while benefiting biodiversity at the same time. To date, applications of NBS approaches that help ensure food security have yet been systematically reviewed. In this paper, we critically review the specific NBSs for food security, highlighting their limitations, to provide recommendations that promote their applications for improving global food security. Our systematic review of nearly 700 peer-reviewed articles indicated that many NBS approaches can be applied to enhance food security dimensions individually or together. However, there is a strong bias towards food availability and not enough research has been done to link NBSs with
improvements in food access and utilization. Over 80% of the reviewed papers were of short-term studies or without specific timeframes, and 25% offered no information on economic effectiveness of NBSs. Environmental benefits of NBSs were explicitly described in about 60% of these papers, and biodiversity enhancement was measured in only about 10%. We, therefore, recommend future applications of NBSs to safeguard food security be shifted to food access and utilization with careful consultation with local communities to address their specific context, using indicators that are easily measured and managed. Systematic monitoring regime and robust and diversified financial support system are also equally important in efforts to successfully implement NBSs. Moreover, environmental and societal benefits, especially water productivity and biodiversity, must be incorporated into the planning and design of NBSs.

How to cite: Ho, L., Nguyen, M., Babel, M. S., and Park, E.: Nature-based solutions for improving food security: A systematic globalreview, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3786, https://doi.org/10.5194/egusphere-egu24-3786, 2024.

EGU24-4650 | Orals | ITS4.5/GM1.3

Making Space for Water: Investing in Nature-based Solutions with Beavers 

Alan Puttock, Holly Barclay, Matt Holden, Peter Burgess, and Richard Brazier

Our landscapes and watercourses face intense pressures from climate extremes, land use change, declining biodiversity and increased demand for water resources. It is increasingly proposed that by working with natural processes, Nature-based Solutions (NbS) can increase resilience to these pressures, providing multiple environmental and societal benefits.

Beavers are the archetypal ecosystem engineers and keystone species, which can profoundly alter ecosystem structure and function, creating complex wetland environments (Brazier et al., 2021). Research has shown the return of the Eurasian beaver (Castor fiber) to European landscapes can provide multiple benefits including for biodiversity and water resource management (Puttock et al., 2021). However, beaver activity such as damming and tree-felling within our intensively managed and populated landscapes can also conflict with existing land use (Auster et al., 2019). Therefore, management and policy frameworks are required which mitigate conflicts and maximise the NbS benefits beavers can bring.

The Making Space for Water Programme (Barclay et al., 2023) will be introduced, which aims to support land managers to build a network of nature rich wetlands across South West England. This project led by Devon Wildlife Trust, in partnership with the University of Exeter and local landowners is the first of its kind in the UK, aiming to work with wild beavers to deliver natural solutions to address societal challenges.  Case studies will be presented discussing how geospatial mapping and modelling, stakeholder engagement and green finance approaches are being implemented to make catchments ‘beaver ready’, target financial support and enable NbS to deliver significant and lasting benefits. It is hoped that the approach adopted in this project alongside discussion of challenges and benefits can contribute towards progress in the mainstreaming of nature-led NbS approaches.

References

Auster, R. E., Puttock, A., & Brazier, R. (2019). Unravelling perceptions of Eurasian beaver reintroduction in Great Britain. Area, area.12576. https://doi.org/10.1111/area.12576

Barclay, H., Holden, M., Puttock, A., & Burgess, P. (2023) Making Space for Water: Investing in nature-based solutions with beavers. https://www.flipsnack.com/devonwildlifetrust/dwt-beaver-green-finance-programme/full-view.html

Brazier, R. E., Puttock, A., Graham, H. A., Auster, R. E., Davies, K. H. & Brown, C. M. . (2021). Beaver: Nature’s ecosystem engineers. WIREs Water. DOI:10.1002/wat2.1494

Puttock, A., Graham, H. A., Ashe, J., Luscombe, D. J. & Brazier, R. E. (2021). Beaver dams attenuate flow: A multi‐site study. Hydrological Processes, 35(2), e14017. DOI:10.1002/hyp.14017

How to cite: Puttock, A., Barclay, H., Holden, M., Burgess, P., and Brazier, R.: Making Space for Water: Investing in Nature-based Solutions with Beavers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4650, https://doi.org/10.5194/egusphere-egu24-4650, 2024.

EGU24-4763 | ECS | Orals | ITS4.5/GM1.3

The potential of Volcanic Pozzolan from Iceland (VPI) in concrete production to reduce the carbon footprint 

Diego Costa, Jukka Heinonen, David Finger, Sigríður Bjarnadóttir, Ólafur Ögmundarson, Börge Wigum, Björn Þorsteinsson, and Helga Adolfsdóttir

The concentration of atmospheric carbon has overpassed 420ppm calling for urgent action to mitigate climate change and remain below the 1.5-degree warming agreed in the Paris climate agreement. The construction industry, with energy consumption included, is with about 40% a significant contributor to the global carbon emissions. Within concrete production, cement accounts for 90% of the emissions. Notably, cement production alone accounts for 8% of global carbon emissions.

Fly ash is amongst the most used of all Supplementary Cementitious Material (SCM). However, its availability is becoming an issue since many coal power plants are shutting down in Europe. Moreover, its environmental profile is questionable. Fly ash is a side product of a carbon intensive industry. Nonetheless, no environmental load has been allocated to it until now.

This study investigates how Volcanic Pozzolan from Iceland (VPI) in concrete compares to traditional concrete and VPI to fly ash, as well as the potential of reducing carbon emissions in concrete production by using VPI as SCM and substitute for cement.

To assess the environmental impacts of VPI and fly ash in cement production, we conducted a Life Cycle Assessment (LCA). For this purpose, we used the GaBi software and relied on primary data from the developers, Heidelberg Materials, and secondary data from the Ecoinvent database.

Our preliminary results reveal that the utilization of VPI as SCM yields an important reduction in carbon emissions compared to Ordinary Portland Cement (OPC) concrete. This notable decrease in carbon footprint positions VPI as a compelling alternative for sustainable concrete production. Two primary factors support this assertion: i) preliminary tests affirm the comparable properties of VPI concrete to OPC, and ii) the diminishing availability of fly ash in Europe necessitates alternative sources, often located at considerable distances, thereby escalating transportation-related emissions.

In conclusion, the integration of VPI emerges as a viable strategy to combat climate change and curtail the carbon footprint of the concrete and construction industry. This initiative aligns with global environmental objectives outlined in the Paris Agreement, United Nations Climate Change Conference, and the Nordic commitment to carbon neutrality by 2040. Embracing VPI as a sustainable alternative in concrete production reflects a positive stride towards achieving these critical environmental milestones.

How to cite: Costa, D., Heinonen, J., Finger, D., Bjarnadóttir, S., Ögmundarson, Ó., Wigum, B., Þorsteinsson, B., and Adolfsdóttir, H.: The potential of Volcanic Pozzolan from Iceland (VPI) in concrete production to reduce the carbon footprint, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4763, https://doi.org/10.5194/egusphere-egu24-4763, 2024.

The rapid population growth rate is associated with an increased number of residential buildings worldwide; thereby, the massive consumption of building materials causes negative environmental consequences such as the depletion of natural resources and rising non-renewable energy use. To address the environmental, societal, and economic challenges, using Nature-based Solutions (NbS) in residential building materials became essential and considered a catalyst tool for realizing sustainable development goals (SDGs) of the UN 2030 agenda. Consequently, using green building materials (GBM) based on NbS as a long-term strategy should be considered during the whole building life cycle for applying sustainability. This research aims to investigate the potential role of using NbS in residential building materials to achieve SDG and develop a framework for assessing and identifying the direct and indirect inner relationships that affect resource efficiency, cost-effectiveness, and building occupants' comfort level. The research attempts to answer how using NbS in residential building materials can contribute to achieving SDG. The eco-friendly approach was used based on a comprehensive literature review to identify the sustainability indicators for using the GBM. The system dynamics (SD) is also used for estimating and quantifying the selected materials through the building life span, starting from the early design stage until demolition and disposal to landfill. The causal loop diagram (CLD) was created based on the data collected from the residential building case study in New Capital Administrative in Egypt after applying the sustainability indicators, followed by critical analysis to identify the realization of the SDGs. The results showed the framework promotes the potential benefits of using NbS in residential building materials. GBM has significantly contributed to achieving several SDG goals and their targets. The study recommended that the selection of alternative materials and the occupant's comfort level deserve more attention from the early design stage and need more consideration.

Keywords, Green Building Materials, Nature-based Solutions, System Dynamic, Sustainable Development Goals, Egypt

How to cite: Marey, H., Kozma, G., and Szabó, G.: The Role of Using Natural-Based Solutions in Residential Building Materials for Achieving Sustainable Development Goals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6592, https://doi.org/10.5194/egusphere-egu24-6592, 2024.

EGU24-6788 | ECS | Orals | ITS4.5/GM1.3

The role of biochar in a circular economy: from agriculture to water and wastewater treatment applications 

Panagiotis Regkouzas, Ioannis Asimakoulas, Eirini Athanasiadou, Elisavet Koukouraki, and Alexandros Stefanakis

Biochar is a sustainable carbonaceous solid material derived from biomass pyrolysis, which abides to circular economy principles in several ways that concern both its production and its several application fields. Biochar is produced by valorizing different organic waste biomass, such as agricultural waste, municipal solid waste, sewage sludge and industrial biowaste, to create a beneficial and valuable product that can then be used in many fields. Thus, biochar production serves perfectly the circularity paradigm as it renders a previously considered waste material to a valuable input material for a new production process. The grounds for the increasing use of and interest in biochars is their favourable physicochemical characteristics, such as the high carbon, macro- and micro- nutrient content, the high porosity and specific surface area, and the abundance of surface functional groups.

Biochar can be effectively used as soil amendment providing fertilizing properties to the applied soil that leads to higher crop production and increased crop nutrient content and quality. At the same time, it provides a stable source of carbon to the soil for several years after its application, contributing this way to CO2 mitigation. Biochar can also be used as an adsorbent due to its carbonaceous porous structure to remediate polluted soil, water and wastewater from either organic or/and inorganic pollutants, even in low pollutant concentrations.

Τhis abstract will present a comprehensive range of studies on biochar production from different sources and its use in different sectors. One of the latest applications is its use as a substrate in Constructed Wetlands for sustainable wastewater treatment, in order to enhance the various pollutant removal/transformation processes. Three different research studies will be presented where biochar was produced from green waste (e.g., olive tree branches) and used as substrate in various Constructed Wetland pilot units that treat domestic wastewater, landfill leachate and olive mill wastewater as an ecological treatment technology.

Furthermore, an agronomic application of biochar as soil amendment in a pot experiment for the cultivation of lettuce will be shown. Finally, the environmental application of biochar produced from sewage sludge as adsorbent will be presented towards the decontamination of water and wastewater from organic emerging micro-contaminants.

How to cite: Regkouzas, P., Asimakoulas, I., Athanasiadou, E., Koukouraki, E., and Stefanakis, A.: The role of biochar in a circular economy: from agriculture to water and wastewater treatment applications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6788, https://doi.org/10.5194/egusphere-egu24-6788, 2024.

EGU24-7509 | Orals | ITS4.5/GM1.3

BirdWatch - a Copernicus-based service for the improvement of habitat suitability of farmland birds in the EU 

Annett Frick, Nastasja Scholz, Sascha Gey, Damaris Zurell, Levin Wiedenroth, Nika Oman Kadunc, Nejc Vesel, Ine Rosier, Rik Hendrix, Annelies de Meyer, Ruth Sonnenschein, Basil Tufail, Bartolomeo Ventura, Tomas Orlickas, and Martynas Rimgaila

BirdWatch, funded by the Horizon Europe Program, focuses on improving the state of biodiversity of the EU's agricultural landscape, in line with major policy targets of the EU Green Deal, the EU Biodiversity Strategy for 2030, and the Farm to Fork Strategy. A healthy agricutural ecosystem forms the necessary basis for the provision of nature-based solutions and, eventually, for the resilience of our society.

Leveraging Copernicus satellite data, the project assesses agricultural areas to identify their suitability for farmland birds and strategises ways to enhance ecological conditions. As indicator species, birds offer insights into overall biodiversity health, contributing to a broader understanding of ecosystem well-being.

The project employs species distribution modeling to link bird occurrence data with habitat requirements, establishing models that gauge habitat suitability and the likelihood of an area being suitable for specific bird species. Utilising remote sensing data, BirdWatch quantifies essential environmental descriptors such as structural variability, land cover type, crop type, mowing intensity and soil moisture. These parameters are then fed into the habitat models to assess landscape suitability.

Knowing the state of habitat suitability and the habitat requirements, BirdWatch identifies which of the agroecological schemes under the EU’s Common Agricultural Policy (CAP), have to be applied to improve the farmland conditions. The agri-environmental schemes are selected in such a way to ensure that they are not in conflict with any spatial or ecological requirements.

Here, BirdWatch uses spatial optimisation, taking into account both the ecological requirements and the economic and operational constraints of the farmers who need to implement the agri-environmental measures as part of their obligations under the CAP.

Benefiting from Copernicus program's high temporal resolution, BirdWatch evaluates the success of agri-environmental measures and makes adjustments as needed.

Upon project completion, the service will be accessible through a web-based GIS application in the project regions of Flanders, Germany, Lithuania, and South Tyrol.

How to cite: Frick, A., Scholz, N., Gey, S., Zurell, D., Wiedenroth, L., Kadunc, N. O., Vesel, N., Rosier, I., Hendrix, R., de Meyer, A., Sonnenschein, R., Tufail, B., Ventura, B., Orlickas, T., and Rimgaila, M.: BirdWatch - a Copernicus-based service for the improvement of habitat suitability of farmland birds in the EU, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7509, https://doi.org/10.5194/egusphere-egu24-7509, 2024.

EGU24-7697 | ECS | Orals | ITS4.5/GM1.3

Circular management of sewage sludge for the sustainable dewatering and reuse of biosolids: an experimental study 

Ioannis Asimakoulas, Panagiotis Regouzas, Elisavet Koukouraki, and Alexandros Stefanakis

Wastewater treatment generates a by-product material known as sewage sludge. In many countries, most of the produced sludge is disposed in landfills, following a linear management strategy that is based on mechanical and chemical methods for limited dewatering and daily transportation to landfills. This strategy is rather expensive and unsustainable and possesses several environmental risks such as groundwater pollution, insufficient sludge drying and stabilization, high carbon footprint etc. Ecological engineering concepts and technologies can provide a circular sludge management strategy that focuses on the utilization of this valuable by-product with the smallest possible environmental impact.

This work will present an ongoing large research study that investigates different technologies and methods towards transforming this organic by-product to a beneficial material with the minimum environmental impact. Specific tasks of the project are:

  • A setup of 16 pilot-scale units of the sustainable technology of Sludge Treatment Wetlands for sewage sludge treatment. The pilot units have different operation and construction properties, such as planted/unplanted, presence of earthworms, different substrate thickness, different loading rates, in order to eventually result in a highly efficient and optimized design configuration.
  • Composting of sewage sludge along with the reed biomass from the constructed wetlands
  • Production of biochar using sewage sludge and reed biomass as raw materials

 

The experimental results of the first operational year of this project will be presented.

The studied circular model for sludge management will be evaluated regarding the reduction of greenhouse gas emissions due to the non-use of mechanical dewatering methods, avoidance of high energy and chemicals consumption, and cessation of daily transport and disposal in landfills. The various organic materials that are produced will be assessed based on their quality properties and will further be tested by application to tomato crops for the estimation of yield improvement. Ultimately, an assessment of the economic, technical, environmental and social parameters of all methods and material cycles and studied management scenarios, will be carried out in order to determine the optimal circular management strategy.

How to cite: Asimakoulas, I., Regouzas, P., Koukouraki, E., and Stefanakis, A.: Circular management of sewage sludge for the sustainable dewatering and reuse of biosolids: an experimental study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7697, https://doi.org/10.5194/egusphere-egu24-7697, 2024.

EGU24-7812 | ECS | Orals | ITS4.5/GM1.3

Algal-bacteria raceway ponds for circular wastewater treatment 

Styliani Biliani and Ioannis Manariotis

Raceway open systems are a highly promising, eco-friendly methodology for wastewater treatment. To assess how effectively nutrients and organic matter were removed from primary and secondary treated wastewater, two laboratory-scale open-raceway algal-bacteria ponds were used. The reactors were operated at organic loading rates (OLR) ranging from 29 to 95 and 9 to 38 g sCOD m3/d, for primary and secondary effluent, respectively. The hydraulic retention time (HRT) of both reactors dropped progressively from 5.5 to 2.2 d, and they thereafter ran at a HRT of 1.1 d. After 130 days, a high biomass concentration of around 2.2 g/ L was maintained with both substrates. Reactors were shown to be functional even at lower HRT levels by the quick removal of organic matter and nutrients. In less than 12 hours, the highly active biomass that was produced with both substrates resulted in the almost complete removal of organic matter and nutrients.
With its exceptional settling capabilities, the algal-bacteria biomass may settle in less than ten minutes. The algal-bacteria content of biomass was 18.3 to 16.5% for lipids, 72.5 to 72.6% for proteins, and 2.6 to 3.2% for carbohydrates. The findings of the present work show that syntrophic algal-bacteria biomass is effective for the high-rate treatment of municipal wastewater. The low operational cost as well as the potential nutrient recovery and biomass valorization make the algal-bacteria process a circular-green model for wastewater management .

How to cite: Biliani, S. and Manariotis, I.: Algal-bacteria raceway ponds for circular wastewater treatment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7812, https://doi.org/10.5194/egusphere-egu24-7812, 2024.

Over the past century, the nitrogen pollution problem has grown concomitantly with population growth, intensified agricultural practices, and a warming climate. In Europe, the presence of excess nitrogen in the environment has already exceeded safe planetary boundaries, posing a threat to Earth’s water supply and biodiversity.

While considerable efforts are now focused toward mitigating this problem through increased regulatory measures on wastewater treatment plants and implementation of better agricultural management practices, there is a growing interest in the use of wetlands as nature-based solutions (NBS) to improve water quality and, in particular, to reduce nitrogen loading to downstream water.

Despite these benefits, wetlands are among the most degraded ecosystem in Europe, having experienced significant shrinkage over the past centuries, now constituting only one-third of their 1700 extent. This decline is largely attributed to agricultural expansion on drained productive wetland soils, while also contributing to increased nitrogen pollution from excess use of fertilizers.

To address these issues, starting from nitrogen surplus data and current wetland extent at European scale we estimate with a physically-based model that current removal potential of wetlands is about 1113 ± 101 kt of N per year (~6.5% of total N surplus in European soil). The significance of wetlands in water quality remediation is underscored by the fact that this nitrogen would otherwise enter the river network and, subsequently, the sea. Given that the current riverine loads in EU watersheds amount to about 2730 kt N per year, the loss of current wetlands would increase this figure by over 40%, with detrimental consequences for the status of surface waters and the eutrophication of coastal areas.

We propose a set of restoration scenarios, along with the associated costs, for the restoration of wetlands that have been drained for agricultural purposes. Our analysis aligns with the objective of the Nature Restoration Law, requiring EU member states to implement effective restoration measures to cover at least 20% of the EU’s land and sea areas by 2030. We show that by restoring 2.6% of EU land (equivalent to 20% of historical wetlands), we could nearly double the current nitrogen uptake (2108 ± 187 kt of N per year), and significantly improve riverine water quality by reducing more than 30% of their loads to the sea. In addition, wetland restoration will offer a wide array of ecosystem co-benefits from flood prevention and carbon sequestration to provision of critical habitat for specialized flora and fauna.

How to cite: Bertassello, L., Basu, N., and Feyen, L.: Enhancing Nitrogen Removal in European River Basins: The Crucial Role of Wetland Conservation and Restoration as Nature-Based Solutions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11118, https://doi.org/10.5194/egusphere-egu24-11118, 2024.

EGU24-11619 | Orals | ITS4.5/GM1.3

Fostering forest and landscape restoration under the UN Decade on Ecosystem Restoration 

Christophe Besacier, Carolina Gallo Granizo, and Andrea Romero Montoya

The UN Decade on Ecosystem Restoration (2021-2030) was declared by the UN General Assembly driven by the global need to support and scale up efforts to prevent, halt and reverse the degradation of ecosystems worldwide. The Food and Agriculture Organization of the UN (FAO) and the UN Environment Programme (UNEP), as leaders of the Decade, are working together with other relevant stakeholders to achieve the Decade’s mission. To do so, focus is given to the development of capacities to empower professionals and institutions involved in the field of restoration to design, implement, monitor and sustain effective restoration initiatives. In the framework of the Best Practices Task Force (TF) of the Decade, partners have jointly developed a Capacity, Knowledge and Learning Action Plan, based on the findings of a global capacity needs assessment, a stocktake of knowledge products and capacity-development activities, and multiple targeted consultations. The plan identifies the gaps where knowledge products or capacity-development initiatives are required across different stakeholder groups, and provides terms of reference for capacity and knowledge development initiatives tailored for those different stakeholder groups. The TF has published the Standards of Practice to guide ecosystem restoration, providing key recommendations in an effort to facilitate the application of the principles for ecosystem restoration. In addition, the TF has created the Framework for the Dissemination of Good Restoration Practices to help practitioners share and consult information about restoration. This framework is in turn part of the UN Decade’s Framework for Ecosystem Restoration Monitoring (FERM), and allows for the collection and documentation of good practices. It also features a common search engine to connect and facilitate retrieving best practices from different relevant platforms, besides the FERM. These resources provide any restoration actor with an essential base for an effective planning, implementation and monitoring of global and local restoration efforts.

How to cite: Besacier, C., Gallo Granizo, C., and Romero Montoya, A.: Fostering forest and landscape restoration under the UN Decade on Ecosystem Restoration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11619, https://doi.org/10.5194/egusphere-egu24-11619, 2024.

EGU24-11821 | Orals | ITS4.5/GM1.3 | Highlight

Forest-landscape dynamics across a climate gradient 

Stuart Grieve, Harry Owen, Paloma Ruiz-Benito, and Emily Lines

Forests and landscapes are fundamentally interconnected, with geomorphic process being modulated by vegetation dynamics, which in turn is influenced by landscape form. Trees play a critical role in shaping landscapes by redistributing sediment across the Earth's surface via gradual processes including tree throw and root growth, and catastrophic processes such as landsliding and debris flows, where spatially variable root cohesion contributes to slope failure likelihood. Conversely, landscape morphology controls the availability of light, water and nutrients for trees and has been observed to dive significant variability in the structure and composition of forests at both local and regional scales. Until recently, our ability to disentangle these processes at broad spatial scales has been limited due to a lack of high resolution data on tree morphology. Advances in Terrestrial Laser Scanning and UAV-LiDAR systems now allow forest plots to be scanned rapidly, capturing the morphology of hundreds of trees alongside the terrain they grow on.

Working across a range of European forest ecosystems, representing a range of climates, we have constructed an unprecedented 3D dataset of European forest-landscape dynamics. From plot-level scans, individual trees are segmented from the digital forest and classified by species. State of the art structural metrics are then computed at an individual, species, and regional level across each distinct climate zone. This pan-European dataset is then coupled with high resolution topographic data, to explore the fundamental linkages between landscapes and vegetation.

How to cite: Grieve, S., Owen, H., Ruiz-Benito, P., and Lines, E.: Forest-landscape dynamics across a climate gradient, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11821, https://doi.org/10.5194/egusphere-egu24-11821, 2024.

EGU24-12659 | Posters on site | ITS4.5/GM1.3

Valuing Natural Capital in Communities for Health 

Jimmy O'Keeffe, Jolanta Burke, Branislav Kaleta, Stephen Campbell, and Cathal O'Connell

The natural capital and ecosystem services that we rely on have been severely impacted by changes to our ecological, biogeochemical and climate systems. This has been driven by our lifestyle choices, impacting our water, air and soil quality. Left unchecked, environmental degradation threatens to reverse the benefits created, exacerbating the decline of our critical natural capital resources. Among the many benefits we obtain from the natural environment, human health and wellbeing are among the most important, yet least understood. In Ireland, mental health conditions, including depression and anxiety impact up to 42% of the population. The costs of poor mental health to the economy are estimated to be €11 billion each year. Furthermore, the second leading cause of death in Ireland is circulatory disease, such as heart attack, or stroke. This Science Foundation Ireland funded project VNiC-Health (Valuing Natural Capital in Communities for Health) will focus on providing evidence from both a human health and wellbeing, and a quality natural environment point of view, helping to address two of the most critical challenges affecting society - the climate and environmental emergency, and our health crisis.

How to cite: O'Keeffe, J., Burke, J., Kaleta, B., Campbell, S., and O'Connell, C.: Valuing Natural Capital in Communities for Health, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12659, https://doi.org/10.5194/egusphere-egu24-12659, 2024.

EGU24-13080 | ECS | Posters on site | ITS4.5/GM1.3

Long-term monitoring of eco-hydrological effects of Live Pole Drains in large open-air test facility at TUDelft campus 

Linnaea Cahill, Job Augustijn van der Werf, Alejandro Gonzalez-Ollauri, and Thomas Adrianus Bogaard

Live Pole Drains (LPDs) are a plant-based drainage system used to drain natural slopes and prevent shallow gully erosion. LPDs are a Nature-based Solution built by placing a live fascine in a shallow ditch or gully along the slope direction, allowing moderate fluxes of surface runoff or seepage to infiltrate and high water fluxes to be conveyed along the fascine without further eroding the slope. Despite their practical implementation, the transient and long-term eco-hydrological behaviour of LPDs is not well understood. We aim to better understand the LPD’s water balance, the seasonal and life-span changes in hydrological behaviour, as well as the impact of an LPD on surface runoff water quality. To this end, we built and instrumented an artificial slope with full-scale LPDs in an open-air lab (OAL) at TUD. The design of the setup and the monitoring plan of the LPDs were developed in collaboration with Glasgow Caledonia University with insights from the construction and monitoring of three LPDs at different growth stages in their OAL on the east coast of Scotland. Herein, we present the design and possible research experiments that can be performed over the next 5 years, generating a data set to further develop and validate conceptual hydrological modelling of LPDs. We expect this long-term demonstrative setup to generate interest and facilitate a more comprehensive understanding of LPD functions, ultimately leading to the incorporation of LPD design and maintenance standards in engineering toolboxes for slope and gully stabilization.

How to cite: Cahill, L., van der Werf, J. A., Gonzalez-Ollauri, A., and Bogaard, T. A.: Long-term monitoring of eco-hydrological effects of Live Pole Drains in large open-air test facility at TUDelft campus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13080, https://doi.org/10.5194/egusphere-egu24-13080, 2024.

Zebra mussels (Dreissena bugensis) and quagga mussels (Dreissena polymorpha) are invasive throughout much of the northern hemisphere. Whilst much attention has been paid to their role in altering aquatic systems via their filter feeding, little attention has been given to their role as geomorphic agents, or the relationships between geomorphology and their ecosystem engineering. We aimed to understand the controls and feedbacks between fluvial geomorphology and Dreissenid mussel invasion, utilising field, laboratory, and numerical modelling approaches. We found important consequences for both geomorphology and ecosystems, with mussel invasion significantly impacting annual sediment transport rates, and positively facilitating the invasion of further priority invasive species.

Quagga mussels attach to benthic sediments using byssal threads, which affects sediment stability and thereby broader river geomorphology. At an invaded gravel bed river, quagga mussels attached >500 g m-2 of mineral sediments together. In ex situ flume experiments, this process increased critical shear stress by 40%. Numerical modelling of flow at the study river was used to upscale these stresses to estimate changes to sediment transport over a recorded five-year flow period, which indicated that typical densities of quagga mussels may reduce the occurrence of a geomorphically active flood event from Q30 to Q2, and reduce sediment transport by 74%. Thus, substantial alterations to bedload sediment transport may occur following quagga mussel invasion.

Dreissenid mussels are also ecosystem engineers, where their shells provide a unique stable habitat in fine-grained rivers. Field surveys found that mussel shells positively facilitate macroinvertebrate communities, but preferentially facilitate co-evolved, high-priority invasive amphipods. The construction of a spatial model of riverbed grainsize across England and Wales, combined with an analysis of Environment Agency nationwide presence/absence records, identified that ecosystem engineering by zebra mussels was particularly powerful in fine-grained river systems to other invasive taxa. Supporting mechanistic aquarium experiments indicated that the ecosystem engineering of zebra mussels may support the invasions of high-profile amphipod species into otherwise unfavourable habitats, which could not be invaded without mussel engineering. Channelisation and dredging, which simplify river channels, may benefit Dreissenid mussel ecosystem engineering and the facilitation of other invasive species. Instead, Nature-based Solutions could be employed to restore the geomorphic functioning of systems, which may improve resilience against high-priority invasive species.

How to cite: Sanders, C.: Geomorphic invaders: Geomorphic potential and landscape controls on the biogeomorphology and ecosystem engineering of Dreissenid mussels, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15884, https://doi.org/10.5194/egusphere-egu24-15884, 2024.

EGU24-16062 | Orals | ITS4.5/GM1.3

Nature-based-Solutions for restoring and developing new mangrove habitats through eco-engineering 

Vicky Stratigaki, Jelle Evenepoel, Mathieu Wille, Emile Lemey, Ignace Stols, Dominic De Prins, Andrea Sofia Reyes Chejin, Julia Peláez Ávila, Marlies Kimpe, Julie Nieto Wigby, Bernd Herremans, Maria Ibanez, Renaat De Sutter, Boris Bohorquez, Stijn Temmerman, and Farid Dahdouh-Guebas

Jan De Nul Group has a long-standing presence in Ecuador, particularly since 2018, when a 25-year concession contract began for performing maintenance dredging for the Access Channel to the port of Guayaquil. This area is part of the Guayas river delta and is covered by mangrove forests that provide important ecosystem services. However, in the last few decades there has been significant loss of mangroves in the area, which intensifies coastal safety problems, as the land around the Guayas river delta becomes more exposed to floods and coastal erosion.

In response to this, the AquaForest innovation project was introduced in 2023. Dredged material from the Access Channel of Guayaquil will be reused for the first time in a circular and sustainable way to create a new mangrove habitat on a new intertidal flat created in the Guayas river delta, located 15km NE of Posorja. AquaForest will become a ‘Nature-based-Solutions’ (NbS) Living lab where important mangrove ecosystem services will be demonstrated and monitored such as protection against floods, biodiversity gain, carbon sequestration and socio-economic benefits for the local communities.

The AquaForest project concept is based on the development of “green-grey infrastructure”. This approach combines conventional engineering techniques for land reclamation with the circular reuse of dredged material to create mangroves through assisted afforestation. At the same time, the initial conditions will be created (e.g. sediment characteristics, hydraulic and hydrodynamic conditions) that are ideal for the growth of mangrove propagules, the proliferation of new accompanying tree seeds and the colonization process of associated biodiversity (micro and macro fauna), though suitable eco-engineering of the project site. Part of the project also focuses on the study of upscaling of this type of Nature-based-Solutions. As such, knowledge obtained from this pilot project regarding the implementation and monitoring of mangrove NbS will be employed in the upscaling of the AquaForest concept in future projects across the region and around the world, particularly in areas where mangrove forests serve as vital components of local ecosystems.

AquaForest demonstrates co-creation between private companies, public institutions, international organisations, local communities and citizens, NGOs, universities and researchers. The project is a collaboration between Jan De Nul Group, Mantis Consulting, HAEDES, Escuela Superior Politécnica del Litoral, Free University of Brussels, University of Antwerp, South Pole, and the Calisur Foundation. The project furthermore has the full support of the Ecuadorian Ministry of Environment, Water and Ecological Transition (MAATE) and all other important local stakeholders.

Acknowledgements: AquaForest is supported by the Government of Flanders (NL: “Departement Omgeving”) through the G-STIC Climate Action Programme 2022, and The International Union for Conservation of Nature (IUCN) through the ‘Blue Natural Capital Financing Facility’.

How to cite: Stratigaki, V., Evenepoel, J., Wille, M., Lemey, E., Stols, I., De Prins, D., Reyes Chejin, A. S., Peláez Ávila, J., Kimpe, M., Nieto Wigby, J., Herremans, B., Ibanez, M., De Sutter, R., Bohorquez, B., Temmerman, S., and Dahdouh-Guebas, F.: Nature-based-Solutions for restoring and developing new mangrove habitats through eco-engineering, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16062, https://doi.org/10.5194/egusphere-egu24-16062, 2024.

EGU24-16355 | Posters on site | ITS4.5/GM1.3

The effectiveness of oyster reefs as a nature-based erosion control measure under storm events 

Wietse van de Lageweg, Thijs van Steen, Brenda Walles, and Jaco de Smit

Coastal ecosystems such as oyster reefs, salt marshes and mangroves are widely recognised as nature-based solutions reducing coastal erosion. Oyster reefs maintain their own habitat and have the ability to grow at the rate of sea level rise, making them self-sustainable, flexible and cost-effective coastal erosion measures in the face of climate change. By attenuating waves and stabilising sediment as well as facilitating and protecting neighbouring ecosystems, they stimulate coastal resilience. However, effective employment of oyster reefs as a nature-based erosion control measure is not trivial and requires the integration of ecological and engineering parameters. Given the satisfaction of these eco-engineering parameters, recent work demonstrates that oyster reefs lead to a four-fold reduction in erosion in the protected area compared to a non-protected area across a decadal period. Despite this apparent effectiveness across a longer time period, it is still poorly understood how effective oyster reefs are in reducing erosion during individual storm events and how large their morphological footprint during these events is.

We present the findings of a series of detailed morphological field surveys of the Viane oyster reef in the Eastern Scheldt, the Netherlands, during which three storm events (Ciaran, Gerrit and Henk) were captured. These storms led locally to significant wave heights of 1.3-1.5 m, corresponding to the highest percentile of wave events recorded locally. Results show that storm Ciaran resulted in an transect-average erosion of 0.02-0.05 m for the unprotected areas, corresponding to the typical annual erosion for the intertidal flats of this area. In contrast, the reef-protected areas showed a greatly reduced erosion of maximum 0.02 m but typically 0.01 m. It is important to note that the erosion pattern as a result of this storm event is far from homogeneous: erosion is greatest immediately behind the reef (~first 50 m), then reduces up to 150 m behind the reef, followed by a zone of deposition (150-250 m behind the reef) and then transitions into another zone of erosion (250-450 m behind the reef). Complementary numerical modelling with XBeach will be used to obtain additional insights into the role of wave angle, wave period and tidal timing on the flow, sediment transport and morphological changes caused by the Viane reef structure during storm events.

How to cite: van de Lageweg, W., van Steen, T., Walles, B., and de Smit, J.: The effectiveness of oyster reefs as a nature-based erosion control measure under storm events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16355, https://doi.org/10.5194/egusphere-egu24-16355, 2024.

Vertical greenery (VG) provides mutliple ecosystem services and diverse forms of implementation. Benefits are linked to maintenance, irrigation, and appropriate planning. The focus of the Fabikli project was to apply these aspects to educational purposes in three highschools in Berlin. This case study delineates the planning, implementation, maintenance, and educational operation of the project.

Complications arose due to planning errors and the still pending building permit of the systems, demonstrating the cumbersome administrative barriers regarding VG. Three energy-efficient rainwater irrigation systems and and a supporting structure that can be harvested from the ground were developed and implemented. Maintenance of these systems is designed to be infrequent and accessible, with low-tech solutions ensuring easy repairs.

At the center of the educational offer were the multidimensional issues addressed by the implemented VG systems. Examples include urban heat stress, land and water use, and CO2 sequestration. The school personal was directly involved in the participation process. Consequently, teachers incorporated the VG-topic creatively into their classes. Here we present the harvest of the VG as an exemplary illustrative showcase.

In addition, the project aimed at a multiplication and propagation of similar systems, which did occur, but with serious design flaws. This demonstrates the importance of appropriate planning, implementation, and continuous attendance, even for low-tech solutions.

In conclusion, schools offer an influential societal overlap between generations and functions such as teachers, parents, or administration. VG can convey several key aspects of environmental education about the ecology with cities.

How to cite: Kluge, B. and Dahm, Y.: Climate adaptation through educational vertical greenery in high schools: key lessons from the city of Berlin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16707, https://doi.org/10.5194/egusphere-egu24-16707, 2024.

EGU24-17900 | ECS | Posters on site | ITS4.5/GM1.3

Exploratory analysis of the long(er) term dynamics of Nature-based Solutions: the case of agricultural soil properties 

Neeraj Sah, James Blake, Vicky Bell, Jonathan Evans, Ross Morrison, and Alejandro Dussaillant

Conventional agricultural practices often lead to increased soil compaction, a decline in soil organic matter (SOM) and an associated decrease in structural porosity, compromising the water holding capacity and resilience of agricultural soils to hydrological extremes. Regenerative agriculture practices, with their focus on building healthy soil ecosystems, hold promises for enhancing agricultural resilience to extreme weather events like floods and droughts. These practices, such as reduced tillage, reduced trafficking and stocking density, cover cropping, and afforestation, can improve soil organic matter content, reduce compaction, enhance soil structure, and promote microbial activity, leading to increased soil porosity, water infiltration, and retention. However, due to the slow response of soils to changes in agricultural management, a critical research gap exists in the timely quantification of the potential effectiveness of these practices in mitigating flood and drought risks. Although undoubtedly robust and informative, long-term monitoring of soil properties before and after a management intervention may take decadal timescales to reveal any significant impacts.
We have therefore adopted an exploratory approach to investigate the merits of back-analysing existing long-term soil moisture datasets to reveal any changes in inferred soil porosity due to changes in land use and/or management. The following UKCEH long-term datasets, which include soil moisture information, have been considered: Neutron Probe Soil Moisture Database (~50 years range), UK Greenhouse Gases Flux Network (last 15+ years), and COSMOS-UK TDT probe data (last 10 years). In addition, we have land cover information from UKCEH Land Cover Maps from 1990 onwards. For UK conditions, it is anticipated that an annual maximum soil moisture content, representing saturated conditions, is likely to be attained during most winter seasons (excluding any ‘dry’ winters, excluded based on rainfall data). It is then possible to estimate soil porosity in any particular year by equating it to the maximum soil moisture content, in effect using this as a proxy measurement with due regard for potential air entrapment effects. Any identified long-term changes in soil porosity obtained through trend, wavelet, and before-after-control-impact analysis might then be linked to changes in land use and/or management. Land cover changes may be identified using Land Cover Map data and local site knowledge, the latter of which will also provide insights into changes in land management. COSMOS-UK TDT data is particularly interesting in terms of land management impacts as, when installed, the instrumentation at each site was enclosed by a newly erected fence. The resultant compound therefore excluded stock and vehicle trafficking and initiated a change in land use from generally arable or improved grassland to rough grassland. It will therefore be valuable to understand if the proposed exploratory analysis approach can reveal any significant changes in soil porosity over time due to this intervention. Likely challenges to be discussed include disentangling any long-term changes in maximum soil moisture due to changes in soil porosity from background changes in climate. We will also share lessons learned and provide recommendations for future work on the back-analysis of long-term soil moisture datasets.

 

 

How to cite: Sah, N., Blake, J., Bell, V., Evans, J., Morrison, R., and Dussaillant, A.: Exploratory analysis of the long(er) term dynamics of Nature-based Solutions: the case of agricultural soil properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17900, https://doi.org/10.5194/egusphere-egu24-17900, 2024.

EGU24-18207 | Posters virtual | ITS4.5/GM1.3

Freshwater mussels’ valve movement response as early-warning system of river’s ecosystem conditions 

Donatella Termini, Nina Benistati, Ashkan Pilbala Ashkan Pilbala, Vanessa Modesto, Nicoletta Riccardi, Luigi Fraccarollo, Sebastiano Piccolroaz, Dario Manca, and Tommaso Moramarco

Global warming has lead concerns about more frequent high intensity rainfall events and increasing river floods. Changes in the river hydrodynamics affect the biological communities which are controlled by the interplay between physical-chemical and hydraulic processes. Thus, there is increasing interest in identifying the impact of the hydrodynamic stresses, also determined by climate change, on the aquatic environment and, consequently, on the interactions between flow and organisms (Lopez and Vaughn, 2021). To this aim, it is fundamental to use remote sensors to constantly monitor the responses of animals to environmental changes. Among these sensors, bio-indicators have been increasingly used to monitor water quality conditions. Some species, called as “ecosystem engineers”, are especially important in studying the effects of climate changes in rivers (Butler and Sawyer, 2012). The present study considers freshwater mussels which meet the criteria to be considered as typical “ecosystem engineers” and can be considered as sensitive biosensors of environmental disturbance (among others Gerhardt et al. 2006). Monitoring freshwater mussels’ opening and closing valves activities (i.e., valvometric technique) over time has been used to evaluate the behavior of the bivalves in reaction to their environmental exposure. The application of the valvometric technique is not recent and has been mainly applied to analyze the impact of chemical stressors on freshwater mussels. Recent experimental results obtained by the research group of the present work (Modesto et al., 2023; Termini et al., 2023), in sand-bed laboratory flumes with different FMs’ populations, have suggested that the mussels’ behavioural response could be also used as a tool for an early warning system of flow variations in rivers, also in the presence of sediment transport. The present work reports the results both of an experimental investigation conducted in a laboratory flume to analyze the influence of the substrate composition on the freshwater mussels’ response and of an in-situ test conducted in a selected reach of the Paglia river (Italy) to verify the FMs’ response in non-controlled environment. In both cases the FMs’ valvometry data were collected in real-time by using Hall sensors technology. The FMs’ behavioural response was examined in terms of valves’ opening/closure frequency and amplitude. The obtained results have confirmed that FMs’ behavioural response can be used as BEWS for identifying the impacts of hydrodynamic changes in rivers.

References

Butler DR, Sawyer CF, 2012. Introduction to the special issue: zoogeomorphology and ecosystem engineering. Geomorphology 157–158.

Gerhardt A, Ingram MK, Kang IJ, Ulitzur S 2006. In situ on-line toxicity biomonitoring in water: recent developments. Environmental Toxicology and Chemistry 25: 2263–2271.

Lopez J. W., Vaughn C.C., 2021. A review and evaluation of the effects of hydrodynamic variables on freshwater mussel communities. Freshwater Biology 66 (9): 1665-1679.

Modesto, V. et al. 2023. Mussel behaviour as a tool to measure the impact of hydrodynamic stressors, Hydrobiologia, 850, 807–820.

Termini, D. et al. 2023. Identification of hydrodynamic changes in rivers by means of freshwater mussels’ behavioural response: an experimental investigation, Ecohydrology, e2544.

How to cite: Termini, D., Benistati, N., Ashkan Pilbala, A. P., Modesto, V., Riccardi, N., Fraccarollo, L., Piccolroaz, S., Manca, D., and Moramarco, T.: Freshwater mussels’ valve movement response as early-warning system of river’s ecosystem conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18207, https://doi.org/10.5194/egusphere-egu24-18207, 2024.

EGU24-19044 | Orals | ITS4.5/GM1.3

Connectivity as a driver of biodiversity and functioning in riverine landscapes: A dynamic, graph theoretic approach. 

Andrea Funk, Damiano Baldan, Paul Meulenbroek, Didier Pont, Sonia Recinos Brizuela, Elisabeth Bondar-Kunze, and Thomas Hein

Connectivity is a crucial property of the riverine landscape. Reduction of connectivity, i.e. habitat fragmentation and isolation effects, impacting ecological functions and biotic communities, is one of the most critical threats to river-floodplain systems. Using a graph theoretical approach for analyzing possible transport pathways in the system (directed, undirected, overland, seepage), we could show that essential ecological functions related to sediment composition and quality, hydrochemical conditions, and macrophyte coverage can be predicted and importance of waterbodies in the network and their main connectivity deficits can be identified. In a second step we are now integrating biotic communities in the predictive framework. Dependent on dispersal model and habitat preferences the different taxonomic groups show clear pattern i.e. drifting invertebrate organisms are highly driven on directed transport whereas fish as active swimmers are more dependent on connectivity in the waterbody network or organism with terrestrial or flying dispersal (amphibia or flying insects) are dependent on overland connectivity. Further they interact with the ecological functions in the system. Using a temporal dataset based on eDNA (environmental DNA) we can further show that ecosystem conditions and distributions of biotic communities are dependent on different transport/movement pathways changing with hydrological conditions (flood to low flow conditions). The dynamic graph theoretic approach can, therefore, be used as an essential tool for prioritizing water bodies for nature-based solutions.

How to cite: Funk, A., Baldan, D., Meulenbroek, P., Pont, D., Recinos Brizuela, S., Bondar-Kunze, E., and Hein, T.: Connectivity as a driver of biodiversity and functioning in riverine landscapes: A dynamic, graph theoretic approach., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19044, https://doi.org/10.5194/egusphere-egu24-19044, 2024.

EGU24-19170 | Posters on site | ITS4.5/GM1.3

Influence of Island Morphology on Micro-Endemic Biodiversity Distribution 

Anaé Lemaire, Jean Braun, and Esteban Acevedo-Trejos

Most islands host an endemic biota, i.e., present nowhere else on Earth like it is the case, for instance, of Madagascar. It has been shown that different populations of lemurs, endemic to the island, are mostly distributed along the watersheds surrounding the central plateau of Madagascar, creating a so-called micro-endemism, while the populations living on the central high-elevated watersheds are not showing this micro-endemism. Here we wish to address the question whether there exists a correlation between the evolution of the landforms (i.e., the morphology of the island) of Madagascar and the hybrid distribution of lemur populations? More broadly, how does the tectono-geomorphic evolution of an island influence the flourishing of micro-biodiversity?

To answer these questions in a quantitative manner, we combined a Landscape Evolution Model based on the Stream Power Law and taking into account Flexural Isostasy, with a Speciation Model. We first developed a morphometric index to differentiate between Π-islands with a central plateau surrounded by smaller basins, like Madagascar, from conical Λ-islands, like Sri Lanka. We then predicted patterns of biodiversity as a function of the index value and its time evolution. We show that the tectono-geomorphic evolution influences patterns of biodiversity and evaluate the influence of varying the values for model parameters, in particular the ones characterising dispersal and mutation. We finally used phylogenetic observations to constrain some of these parameters.

How to cite: Lemaire, A., Braun, J., and Acevedo-Trejos, E.: Influence of Island Morphology on Micro-Endemic Biodiversity Distribution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19170, https://doi.org/10.5194/egusphere-egu24-19170, 2024.

EGU24-19856 | ECS | Posters on site | ITS4.5/GM1.3

Quantification of burrowing animals’ impact on landscapes: a review of numerical methods. 

Marta Loreggian, Jantiene Baartman, and Annegret Larsen

The presence of burrowing animals is a recognizable characteristic in almost all types of landscapes and climates. Independent of their size, their activity of mounding and digging plays a significant role in landscape evolution, to the point of being addressed as ecosystem engineers. For example, while tunnels facilitate water infiltration, mounds slow down surface runoff and make soil available for erosion. Several models have included animal activity as a bioturbation process, and many studies have quantified the impact of animals’ presence on soil properties. However, how to best include burrowing animals’ role in other soil hydro-physical processes in hydrological, landscape evolution, or soil erosion models is still unclear. Indeed, the significant heterogeneity of animals’ distribution and their impact at different spatio-temporal scales complicates their inclusion into models. Therefore, this study aims to explore numerical methods (equations, coefficients, ratios) used to quantify the impact of burrowing animals on soil hydro-physical processes. Furthermore, it explores how these methods can be integrated with the most common equations implemented in hydrological, landscape evolution, or soil erosion models to calculate those processes. We focused on surface runoff, soil lateral transport, soil excavation, soil mixing, water infiltration and subsurface preferential flow. Peer-reviewed studies about burrowing animals’ impact on soil hydro-physical processes were collected. Of those articles, we reviewed studies where numerical methods were used to quantify or discriminate the role of the animals. The articles were classified according to the processes measured, the spatio-temporal scale, whether the animal was vertebrate or invertebrate and smaller or bigger than 2.5 cm.

As a first result, the main processes quantified are soil lateral transport, water infiltration and soil mixing. Most of the studies were conducted with field or laboratory experiments on a yearly scale. Because of this, most equations collected were empirical and used to quantify single processes for a specific environment. Rates were the primary means of quantification for runoff or soil lateral transport, and coefficients for soil mixing. Infiltration was quantified as change in soil moisture or as rate. Overall, hydraulic properties were mainly calculated in relation to the presence/absence of earthworms or insects, while mammals and vertebrates were primarily linked to soil physical properties and soil transport. We can argue that, to better incorporate animals’ influence on soil hydro-physical processes, a more comprehensive investigation of their role in soil hydraulic properties is fundamental. However, this might not be sufficient when considering large spatio-temporal scales (centuries, catchments). For this, the development of an ad hoc faunal-hydro-physical module can be used to explore the impact of animal bioturbation on processes at different scales.

How to cite: Loreggian, M., Baartman, J., and Larsen, A.: Quantification of burrowing animals’ impact on landscapes: a review of numerical methods., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19856, https://doi.org/10.5194/egusphere-egu24-19856, 2024.

EGU24-20606 | ECS | Orals | ITS4.5/GM1.3

Bioeconomy gaps and opportunities in restored Atlantic forests 

Pedro Krainovic, João Paulo Romanelli, Laura Helena Porcari Simões, Lukas Rodrigues Souza, Rens Brower, Ana Flávia Boeni, Klécia G. Massi, Cássio A. P. Toledo, Ricardo R. Rodrigues, Vinicius C. Souza, Rafael B. Chaves, Sergio de-Miguel8, and Pedro H. S. Brancalion

Forest restoration faces persistent challenges for its financial viability due to high land opportunity costs and insufficient financial returns from restored areas, such as through payments for ecosystem services and timber production. A potential financial pathway is to develop non-timber forest products with bioeconomic potential. Here, we explore the bioeconomic potential of native tree species growing in different types of new wooded lands in Atlantic forests. First, we established 25 30 𝚡 30 m plots in natural regeneration, degraded forest remnants, and actively managed areas (eucalyptus monoculture and active restoration) in the Paraíba Valley, southeastern Brazil, where we sampled all woody individuals with dbh ≥ 5 cm, totaling 284 native tree species. Then, we conducted a literature review and patent survey on the biotechnological potential of the species sampled. Based on this review and survey, we calculated the proportion of sampled species with patents and assessed the species used and general characteristics of patents registered among prominent companies in the market. We found 168 (70%) species with a biotechnological potential based on the presence/absence of articles reporting uses for medicine, cosmetics, food, and other market segments, such as bioinsecticides, bio fertilization, construction, and manufacturing. In the sampled areas, species offer varied potential for use, with higher potential in spontaneous environments. Araucaria angustifolia was the most extensively studied species, with 246 research papers, followed by Euterpe edulis (205), Baccharis dracunculifolia (188), Dodonaea viscosa (170), Cedrela odorata (158), Copaifera langsdorffii (139) and Hymenaea courbaril (132). We found patents worldwide, distributed across more than 20 countries, for the sampled species. The medicinal use of leaf chemicals accounts for the largest use in our survey. Despite these numbers, we found that less than 5% of the investigated articles reported evaluations of final products, while most provided results from in vitro, in vivo, or chemical analytics descriptions. Most patents registered by companies are related to exotic and non-tree species, many associated with existing commodity chains, reinforcing the need to integrate bioeconomy and forest restoration agendas better.

How to cite: Krainovic, P., Paulo Romanelli, J., Helena Porcari Simões, L., Rodrigues Souza, L., Brower, R., Flávia Boeni, A., G. Massi, K., A. P. Toledo, C., R. Rodrigues, R., C. Souza, V., B. Chaves, R., de-Miguel8, S., and H. S. Brancalion, P.: Bioeconomy gaps and opportunities in restored Atlantic forests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20606, https://doi.org/10.5194/egusphere-egu24-20606, 2024.

This study presents the preliminary results of the ongoing research project “Re.Nature Cities”, in which  the ability of street trees to act as an effective measure against increased urban air temperatures is evaluated via experimental and simulation means. In the existing literature, numerous studies highlight that the addition of street trees inside the canyons of urban areas may result in a significant reduction of the peak ambient summer Tair, having also a prominent effect on outdoor thermal comfort regulation. Yet, street trees also impact urban ventilation as they act as barriers, disturbing the wind flow and affecting buildings’ energy needs and thermal comfort; the positive effect of wind sheltering during the cold winter period, can be thus significantly counterbalanced during the warmer periods of the year. The existing evidence reveals that the green elements’ implementation in the built environment without holistically accounting for all the vegetation-air-buildings interactions, can even exacerbate human discomfort and deteriorate indoor natural ventilation.

Based on the above, this study evaluates the mitigation potential of a tree type that is commonly encountered in Greek cities – the citrus- since it has low irrigation needs and high drought tolerance. An integrated experimental campaign, employing wind tunnel measurements, albedo and Leaf Area Index/Leaf Area Density (LAI/LAD) measurements is conducted so as to define of the aerodynamic, thermal and foliage characteristics of real trees.  Wind tunnel measurements of total drag are carried out in a wind tunnel section of 3.5m width and 2.5m height, while LAI measurements are conducted using a plant canopy analyzer, with the LAD of each layer (1 m/layer) then calculated from LAI by empirical equations. The obtained values are then used as input parameters in the vegetation model of the ENVI-met microclimate model, which is employed for the evaluation of the thermal environment of typical building blocks in Greece, considering different planting patterns and vegetation coverage scenarios.

The experimental database of foliage, thermal and aerodynamic characteristics of common urban tree species, along with the detailed microclimatic simulations of typical urban districts provide a valuable tool for decision-making regarding the optimal vegetation coverage and the planting pattern for urban areas.

 

How to cite: Tsoka, S., Pappa, V., Markos, N., and Bouris, D.: Assessing the effect of citrus plant on the improvement of the outdoor thermal environment using wind tunnel and ground-based Leaf Area Index measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20879, https://doi.org/10.5194/egusphere-egu24-20879, 2024.

Cyanobacterial bloom induced by water eutrophication is one of the most serious ecological problems in freshwater lakes. Water diversion, transferring external freshwater into lakes, is proved to be the eco-hydraulic engineering measure rapidly relieving cyanobacterial blooms in eutrophic lakes. To explore the response of phytoplankton community to the changed aquatic habitat influenced by water diversion, we constructed the microcosm experiment modeling water diversion from Yangtze River to Lake Taihu in the laboratory, with one control group and three flow discharges groups of external freshwater from Wangyu River diversion channel during the summer water diversion period. Each modeling microcosm ecosystem had a volume of 5 L and was studied for a period of 20 days (10 days for the water diversion period and 10 days for the stop period). The results showed that the responses of physicochemical parameters in lake microcosms were sensitive, reflecting by the variations in contents of aquatic dissolved oxygen, total nitrogen, total phosphorus and dissolved silicate positively correlated with the flow discharges. During the period of water diversion, the cell abundances of Cyanophyta in all treat groups decreased significantly, while the abundances of Bacillariophyta increased, especially in the group with the highest flow discharge. The diversity and dominant species in phyla of Cyanophyta and Bacillariophyta were changed by water diversion and evidently in the highest flow discharge group. On the 20th day of the stop period, the relative proportion of Microcystis spp. recovered, and Pseudanabaena spp. became one of dominant cyanobacterial species in treat groups, which was related to the dominance of Pseudanabaena spp. in the external river water. The redundancy analysis between aquatic physicochemical parameters and phytoplankton communities revealed that variations in contents of aquatic dissolved oxygen, total nitrogen and dissolved silicate were the dominant environmental factors influencing lacustrine phytoplankton community in addition to the allochthonous inputs from external freshwater. However, the recovery of Microcystis spp. during the stop period of water diversion demonstrated that water diversion from Yangtze River to Lake Taihu has no sustainable effect on changing the dominance of Microcystis spp. in lakes in short time, although the diversity and phytoplankton community composition shifted during water diversion.

How to cite: Dai, J., Wu, X., and Wu, S.: Resilience of lacustrine phytoplankton community to the short-term river-to-lake water diversion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21127, https://doi.org/10.5194/egusphere-egu24-21127, 2024.

GM2 – Geomorphologists' Tools and Methods

EGU24-480 | ECS | Posters on site | GM2.1

Probabilistic optimal transport-driven inversion of the 2012 Palisades rockfall seismic source 

Rebeca Ursu, Mark Naylor, Hui Tang, and Jens M. Turowski

During rockfall events, the seismic waves are generated in response to the time-varying normal and tangential forces between the Earth and colliding and sliding mass. These forces carry information about the nature of the generative seismic source; hence, the source dynamics can be estimated. Several studies have used forward modeling to determine the amplitude and duration of these forces and, implicitly, the source process that could generate the observed seismic waves. Through running multiple forward models, the force history inversion involves adjusting the force amplitude and duration to minimize the misfit between the proposed source model, convoluted with the force-impulse Green’s functions, and the observations. In the Bayesian framework, the normal likelihood function is traditionally used to measure the misfit between the observed and predicted waveforms with respect to amplitude. However, the normal likelihood function is insensitive to the potential misalignment of the waveforms in time. Moreover, the relevant parameter space often exhibits multiple local minima, which may lead to a convergence to a minimum that does not present the global optimum. Optimal transport distances-driven exponential likelihoods were recently proposed as alternatives thanks to their ability to capture the time structure of the signals. We employed a Metropolis-Hastings sampling strategy in the probabilistic framework to reconstruct the 2012 Palisades rockfall seismic source using two implementations of the Wasserstein distance-based exponential likelihood function. The first implementation transforms between density functions, which are always positive and integrate to one. Therefore, it requires the transformation of the signals into probability density functions, which is done here via a modified graph-space transform scheme. The second method is applied directly to the signals. We evaluated the robustness of the two implementations of the Wasserstein distance-based exponential likelihood function in simulating the source characteristics with respect to the normal likelihood. Preliminary results show that contrary to the expectations, using optimal transport distances-driven exponential likelihoods leads to negligible improvement in the fit to the observed waveform.

How to cite: Ursu, R., Naylor, M., Tang, H., and Turowski, J. M.: Probabilistic optimal transport-driven inversion of the 2012 Palisades rockfall seismic source, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-480, https://doi.org/10.5194/egusphere-egu24-480, 2024.

EGU24-1972 | ECS | Orals | GM2.1 | Highlight

Do earthquakes cause more damage in the summer? 

Eldert Fokker, Elmer Ruigrok, and Jeannot Trampert

Shallow soft sedimentary layers overlaying harder bedrock are known to amplify ground motion generated by earthquakes. Such an amplification occurs when seismic waves travel from high impedance (density times wave speed) to low impedance layers. Large impedance contrasts can lead to substantially larger earthquake damages. As the impedance contrast determines the amplification factor, variations in shallow shear-wave speed contribute directly to changes in site amplification.

Seasonal temperature fluctuations have been shown to induce shear-wave speed variations and, hence, affect site amplification factors. This naturally leads to the question: is the strength of earthquake damage season dependent? In this study we model by how much seasonal temperature variations affect site amplification. The site-specific physical properties determine whether site amplification is more pronounced during summer or winter. For parameters from the Groningen region of the Netherlands, affected by the gas extraction induced seismicity, we expect in the summer a relative increase in amplification of 8% with respect to the amplification factor in the winter.

How to cite: Fokker, E., Ruigrok, E., and Trampert, J.: Do earthquakes cause more damage in the summer?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1972, https://doi.org/10.5194/egusphere-egu24-1972, 2024.

EGU24-3399 | ECS | Orals | GM2.1

Enhancing debris flow warning through seismic feature selection and machine learning model comparison 

Qi Zhou, Jens turowski, Hui Tang, Clément Hibert, Małgorzata Chmiel, Fabian Walter, and Michael Dietze

Machine learning can improve the accuracy of detecting mass movements in seismic signals and extend early warning times. However, we lack a profound understanding of the limitations of different machine learning methods and the most effective seismic features especially for the identifcation of debris flows. This contribution explores the importance of seismic features with Random Forest and XGBoost models. We find that a widely used approach based on more than seventy seismic features, including waveform, spectrum, spectrogram, and network metrics features, suffers from redundant input information. Our results show that six seismic features are sufficient to perform binary debris flow classification with equivalent or even better results., e.g., the Random Forest and XGBoost models achieve improvements over the benchmark of 0.09% and 1.10%, respectively, when validated on the ILL12 station. Considering models that aim to capture patterns in sequential data rather than information in the current time window, using the Long Short-Term Memory algorithm does not improve the binary classification performance over Random Forest and XGBoost models. However, in the early warning context, the Long Short-Term Memory model performs better and more consistently detects the initiation of debris flows. Our proposed framework simplifies seismic signal-driven early warning for debris flows and provides a proper workflow that can be used for detecting also other mass movements.

How to cite: Zhou, Q., turowski, J., Tang, H., Hibert, C., Chmiel, M., Walter, F., and Dietze, M.: Enhancing debris flow warning through seismic feature selection and machine learning model comparison, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3399, https://doi.org/10.5194/egusphere-egu24-3399, 2024.

EGU24-3861 | ECS | Posters on site | GM2.1

Capturing the short-term dynamics of outlet glaciers:  insights from seismic monitoring on Sermeq Kujalleq in Kangia, Greenland 

Janneke van Ginkel, Ana Nap, Adrien Wehrlé, Fabian Walter, and Martin Lüthi

Sermeq Kujalleq in Kangia, also known as Jakobshavn Isbræ, a major outlet glacier of the Greenland Ice Sheet, exhibits a flow speed higher than 30 m/day near the terminus. Basal sliding, iceberg calving, and subglacial hydraulics play pivotal roles in ice flow dynamics of this outlet glacier, and understanding these processes is crucial for predicting the impact of outlet glaciers on the Earth system in a changing climate.

 Seismic and geophysical field campaigns were conducted in 2021, 2022 and 2023 in the region of Sermeq Kujalleq in Kangia. The project has the aim to monitor the dynamic behavior of such a fast-flowing outlet glacier and its interaction with the surrounding shear margins. Shallow borehole seismic sensors and self-sufficient seismic boxes were deployed in multiple arrays on the fast-moving ice stream and its margin. The sensors capture seismic sources and monitor subglacial conditions and spatiotemporal variabilities throughout the ice mass. An on-rock broadband seismometer near the terminus records iceberg calving activity ideally complementing observations of a Terrestrial Radar Interferometer operating simultaneously.

 Here we report on first results of a seismic analysis that provides insights into details of ice dynamic variations of Sermeq Kujalleq. Power spectrograms of the 2023 upstream arrays feature a 4-day tremor-like signal between 2.5 and 6 Hz. This phenomenon was not observed for other calving events and was missing in the 2022 record. Beamforming techniques are employed to constrain the source location of this tremor as well as other seismic events. Potentially this multi-day tremor signal corresponds to the ice stream response to a major calving event. Additionally, beamforming and spectral analysis provide insights into hydraulic cycles of the glacier, such as widespread diurnal water drainage and the activity of moulins. By comparing these seismic observations with ice flow speed and satellite images we aim at understanding the details of short-term perturbations to ice flow, which may influence larger-scale ice stream dynamics.

How to cite: van Ginkel, J., Nap, A., Wehrlé, A., Walter, F., and Lüthi, M.: Capturing the short-term dynamics of outlet glaciers:  insights from seismic monitoring on Sermeq Kujalleq in Kangia, Greenland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3861, https://doi.org/10.5194/egusphere-egu24-3861, 2024.

EGU24-5306 | ECS | Posters on site | GM2.1

Quantifying snout marginal bedload export from alpine glaciers 

Eva Wolf, Michael Dietze, and Stuart Lane

Bedload export from Alpine glaciers by rivers is a geomorphological process of increasing interest given the high retreat rates of temperate ice masses in the context of global warming. Access and measurement difficulties make it very poorly known and contradictory hypotheses exist about how it might respond to receding glaciers. In subglacial channels, bedload transport is a key mechanism for evacuating one of the products of glacial erosion. It likely constrains glacial erosion rates as removal of the products of erosion is needed so as to yield fresh bedrock for further erosion. Environmental seismology may be a valuable tool in understanding rates of subglacial bedload export.
Previous studies have considered subglacial bedload export in glacial forefields using seismic sensors and tracked particles moving underneath the ice sheet. We are taking former studies forward and extend the monitoring of bedload export detecting coarse grain impacts using seismometers right at the glacial terminus. The project aims to determine diurnal as well as seasonal sediment export quantities and compare results among different field sites.
We studied subglacial bedload export for the Otemma and Arolla glacier in Valais, Switzerland in the summer of 2023 by installing two seismic stations (PE-6/B geophones) close to each glacier terminus throughout the melt season. These four-month records of seismic signals were processed using fluvial inversion algorithms of the eseis package implemented in R. The algorithm is refined with wave propagation- and ground properties determined through active seismic experiments as well as measured grain size distributions from field sampling. We are able to separate turbulent water noise and bedload noise in the seismic signal and estimate water stage as well as bedload transport rates. Results are validated by comparing the water stage estimates to measurements from a discharge gauging station. Over a full season, we compare the behaviour of the two different glaciers regarding sediment export taking into account their size, orientation, elevation and other factors. We relate the detected bedload export events to meteorological conditions and shifts in seasonal melt processes from snow melt to ice melt.
The results of this study help to get a clearer picture of diurnal as well as seasonal patterns of bedload export from glaciers, impacting downstream riverbed erosion and deposition in the light of increasingly rapid glacier melt. These geomorphological processes are of interest for different infrastructural facilities such as hydropower plants.

How to cite: Wolf, E., Dietze, M., and Lane, S.: Quantifying snout marginal bedload export from alpine glaciers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5306, https://doi.org/10.5194/egusphere-egu24-5306, 2024.

EGU24-5821 | Orals | GM2.1

Global observations of an up to 9 day long, recurring, monochromatic seismic source near 10.9 mHz associated with tsunamigenic landslides in a Northeast Greenland fjord 

Paula Koelemeijer, Rudolf Widmer-Schnidrig, Kristian Svennevig, Stephen Hicks, Thomas Forbriger, Thomas Lecocq, Anne Mangeney, Clément Hibert, Niels Korsgaard, Antoine Lucas, Claudio Satriano, Robert Anthony, Aurélien Mordret, Sven Schippkus, Søren Rysgaard, Wieter Boone, Steven Gibbons, Kristen Cook, Sylfest Glimsdal, and Finn Løvholt and the VLPGreenland team

We report the discovery of an unprecedented, monochromatic low-frequency seismic source arising from the fjords of North-East Greenland. Following a landslide and tsunami event in Dickson fjord on 16 September 2023, the seismic waves were detected by broad-band seismometers worldwide. Here we focus on a detailed analysis of the long-period seismic signal, while a reconstruction of the dynamics of the landslide is presented by Svennevig et al. in session NH3.5. 

Both frequency and phase velocity of the waves are consistent with fundamental mode Rayleigh- and Love-waves. However, the decay rate of these waves is much slower than predicted for freely propagating surface waves so that we infer a long-lasting and slowly decaying source process. Although the 16 September 2023 event was by far the largest, analysis of historical seismic data has revealed five other previously undetected events, all with a fundamental frequency between 10.85 and 11.02 mHz. The signal of the largest two events initially decayed with a quality factor, Q close to Q=500, which increased to Q=3000 within the first 10 hours and could thus be detected for up to nine days. The smaller four events had a slow decay-rate (Q>1000) for their entire duration. In comparison, the global average attenuation of Rayleigh waves at these frequencies is Q=117 for PREM, thus precluding a single, impulsive source for these signals.

Gleaning archives of optical and SAR satellite images reveals that at least four out of six events could be associated with landslides in Dickson fjord, the two others remain unresolved. However, such rapid transient events cannot explain the long duration of the radiated seismic waves. Our modelling of the largest event shows that a transversal seiche in Dickson fjord, excited by a landslide induced tsunami, can account for both the monochromatic low frequency signal as well as its seismic signal amplitude and radiation pattern. However, the seiche modelling results in Q values lower than 250 and hence the seiche needs to be continuously driven for the entire duration of the observed seismic signal. Thus, a full understanding of the source process that produces the monochromatic signal remains enigmatic.

How to cite: Koelemeijer, P., Widmer-Schnidrig, R., Svennevig, K., Hicks, S., Forbriger, T., Lecocq, T., Mangeney, A., Hibert, C., Korsgaard, N., Lucas, A., Satriano, C., Anthony, R., Mordret, A., Schippkus, S., Rysgaard, S., Boone, W., Gibbons, S., Cook, K., Glimsdal, S., and Løvholt, F. and the VLPGreenland team: Global observations of an up to 9 day long, recurring, monochromatic seismic source near 10.9 mHz associated with tsunamigenic landslides in a Northeast Greenland fjord, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5821, https://doi.org/10.5194/egusphere-egu24-5821, 2024.

EGU24-5947 | ECS | Posters on site | GM2.1

Low-cost raindrop sizing with piezoelectric sensor: A mechanical approach 

Chi-Ling Wei and Li-Pen Wang

Raindrop size distribution (DSD) is a key factor to derive reliable rainfall estimates. It is highly related to a number of integral rainfall variables, such as rain intensity (R), rain water content (W) and radar echo (Z) and thus can contribute to a range of hydrological and meteorological applications, such as rainfall-induced landslide warnings and radar rainfall calibration. Disdrometers are commonly used to measure DSDc. Well-known disdrometer sensors include JWD, Parsivel and 2DVD . These sensors may have their own strengths and weaknesses, but their costs are all much higher than that of widely-deployed catching gauges (e.g. tipping bucket and weighing gauges). This makes it infeasible to have a widespread, or dense, DSD monitoring network. To address this issue, our ultimate goal is to develop a lightweight and low-cost disdrometer with descent accuracy.

In this work, we have prototyped a disdrometer with a piezoelectric cantilever. It is not new to use piezoelectric materials as rain sensors because of its low cost and low maintenance. It is however not trivial to ‘calibrate’ this type of sensors, and various calibration methods have been proposed in the literature. However, whereas most of these sensors associate received signal with rainfall properties directly (via statistical or machine learning approaches), we propose to formulate the drop sensing process as a ‘mechanical’ problem. More specifically, we first form a physical model that can well simulate the signal response of continuous excitation force on a piezoelectric cantilever based on an existing theoretical model. We then analytically derive the inverse function of the model which can obtain the excitation force directly from the measured signals. The derived force-time signal is found to linearly associate with DSD and can also be used for other purposes including kinetic energy analysis.

In spite of the sound underlying theory, the real-world signal is far from perfect, containing a considerable amount of noise. Additionally, as our physical model requires conducting differentiation and second-order differentiation, to which the impact of noise is even destructive. Although we have made efforts to improve the quality of signal from the source, it does not fully solve the problem because the physical model is highly sensitive to signal gradients. To effectively deduce the impact of noise, we then introduced various signal ‘noise’ models, which were reported to well resemble the behavior of real-world signal noises, to train a machine learning (ML) model, such that the actual excitation force function can be derived from various weather conditions.

To verify the proposed sensor and signal processing model, we have set up lab experiments using an in-house device with micropumps and high-voltage raindrop detachment devices to control the required size, drop location, and timing of the drops. Preliminary results from a given range of drop sizes have shown the potential of the proposed sensor and ML-based signal processing model to well derive drop sizes from our experimental device. We plan on further testing our sensor outdoor and compare the measurements with those collected from a co-located Parseval2 disdrometer.

How to cite: Wei, C.-L. and Wang, L.-P.: Low-cost raindrop sizing with piezoelectric sensor: A mechanical approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5947, https://doi.org/10.5194/egusphere-egu24-5947, 2024.

EGU24-6218 | ECS | Orals | GM2.1

High resolution observations of tide induced icequake activity at the Astrolabe glacier grounding zone 

Tifenn Le Bris, Guilhem Barruol, Florent Gimbert, Emmanuel Le Meur, and Dimitri Zigone

Cryoseismology, which records ice-induced seismic activity, is emerging as a powerful tool for studying the grounding zone - a critical spatio-temporal area where outlet glaciers grounded on the continent starts floating and interacting with the ocean underneath. The SEIS-ADELICE project supported by the French Polar Institute (IPEV) aims to characterise the dynamics of the Astrolabe glacier in Terre Adélie (East Antarctica), from its grounded part to its terminus in the ocean. Over the past 3 years, we deployed broad-band seismometers both at the grounding zone and on stable ice around the glacier, along with ocean bottom seismometers (OBS) close to the glacier terminus. In January 2023, the recording system was complemented by a dense array of 50 seismic nodes over the grounding zone. This allowed us to cover spatial scales from metres to several kilometres, providing a high-resolution observation of tidal forcing on the floating tongue and its repercussions on the glacier behaviour. The seismic records contain a wide range of signals, including icequakes, accepted to result from the brittle deformation of the ice. Although the seismic patterns at the different stations show clear modulation of icequakes by tidal cycles, their phasing with the tide depends on the location of the sensors, whether they are grounded or floating and on their distance from the active part of the glacier. This highlights the importance of the network typology and its proximity to the grounding line when characterising icequake occurrence patterns. Local icequakes detected at the grounding line exhibit a consistent occurrence during both rising and falling tides, with the peak activity observed during high tide. Source location analysis reveals that events are distributed across both the grounding line and the lateral shear zones of the glacier which are under strong stress from the ice-ocean interactions during tides.

How to cite: Le Bris, T., Barruol, G., Gimbert, F., Le Meur, E., and Zigone, D.: High resolution observations of tide induced icequake activity at the Astrolabe glacier grounding zone, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6218, https://doi.org/10.5194/egusphere-egu24-6218, 2024.

EGU24-6613 | Orals | GM2.1

Tracking baleen whale calls in the Lower St. Lawrence Seaway, Canada, using land seismometers   

Yajing Liu, Eva Goblot, and Alexandre Plourde

The Lower St. Lawrence Seaway (LSLS) is part of a major marine shipping corridor in eastern Canada, and also an essential feeding ground for fin whales and blue whales. Understanding the whale migration and habitat usage in the LSLS is critical for informing conservation policies that minimize noise pollution and risk of collision to the whale populations. In this study we utilize continuous recordings of six broadband seismometers located on the north and south shores of the St. Lawrence River to characterize the frequency range, recurrence interval and duration of fin and blue whale calls. We further use the whale call detections to quantify their spatial and temporal variations along the LSLS between February 2020 and January 2022, with the caveat that the detection range at these land stations is probably limited to a few kilometers due to energy loss along the seismic wave travel paths through multiple interfaces. We identified higher whale call detection rates at stations near the northwest of St. Lawrence Gulf than the upstream Estuary, suggesting possible influences of ocean currents and ice conditions. Whale calls are detected year around, with majority in the fall/winter months (September to February), implying seasonal and annual variations that may be influenced by climate change. We are currently analyzing recordings from a temporary deployment of 48 nodal seismometers, at 10-km average spacing, along the shorelines of the LSLS between September-October 2023, to further quantify the spatial patterns of whale calls and identify possible linkages to coastal bathymetry, ocean currents and preferential diets for the baleen whales.

How to cite: Liu, Y., Goblot, E., and Plourde, A.: Tracking baleen whale calls in the Lower St. Lawrence Seaway, Canada, using land seismometers  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6613, https://doi.org/10.5194/egusphere-egu24-6613, 2024.

The EarthScope Transportable Array (TA) in Alaska has been a unique seismic network since about 2014 because most stations are equipped with environmental sensors to record pressure, temperature, and wind (speed and direction). We will summarize some physical insights of near-surface properties in Alaska that can be gained from the combined analysis of seismic and environmental sensors. We also point out a possible effect of the thick sea ice on the climate in the North Slope region that faces the polar ocean.

First, the combined analysis of seismic data and pressure data allows us to separate two distinct types of seismic noise; one is the ordinary seismic noise, consisting of propagating body and surface waves, and the other is the deformation caused by the local pressure loading. This loading effect is observed at many stations when surface pressure becomes high. It can be confirmed based on two pieces of evidence; one from high coherence between seismic and pressure data and the other from the phase difference between pressure and vertical seismic displacement. By selecting data from a high-pressure range, we can apply the compliance method, similar to the compliance method applied to ocean bottom observations (e.g., Webb and Crawford, 1998). We will show a map of shallow rigidity variations for the depth range of 50-100m.

Second, the combined analysis of temperature and seismic noise allows us to identify the major effects caused by near-surface melting, primarily in the permafrost area. Some stations show a thousand-fold increase of horizontal noise in summer at 0.01-0.03 Hz in comparison to the frozen state. This anomalous horizontal noise can be seen at low frequency (< 0.1 Hz) and is undoubtedly related to tilt effects as its amplitude increases towards lower frequency.

Third, seasonal variation in horizontal noise shows a rapid increase in summer due to melting but the way the noise level returns to the frozen (low-noise) state varies from station to station. For most stations, this return occurs well after the surface temperature becomes negative in September or October. But some stations require time until March of next year to return to the low noise level. These data suggest that the melt layer remains at depth for a long time even after temperature drops below freezing, perhaps developing a sandwiched molten layer between the developing ice from the surface and the underlying permafrost ice.

How to cite: Tanimoto, T.: New Perspectives on the Shallow Environment in Alaska from co-located seismic, pressure, temperature, and wind sensors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6637, https://doi.org/10.5194/egusphere-egu24-6637, 2024.

EGU24-7490 | Posters on site | GM2.1 | Highlight

August 2023 Slovenian flood anatomy from national seismometer network data analysis 

Michael Dietze, Mateja Jemec Auflič, Sašo Petan, and Nejc Bezak

Excessive and sustained rainfall can trigger regional floods with a large propagation range. Their non-linear onset, rapid evolution and massive impact make prediction, mitigation and posteriour anatomy efforts difficult.

The atmospheric low “Petar” that struck Europe in early August 2023 was one drastic example of such flood triggering rain events. It was able to gain abundant moisture and heat over an exceptionally warm Mediterranean Sea, before it moved to continental Europe, crossing Slovenia, Austria, and Germany. It caused severe flooding as a result of locally more than 350 mm rain within less than two days. We focus on Slovenian examples, where the event was perceived the most devastating natural hazard in the last decades.

Here, we follow a seismic approach to study the spatially contrasting effects of the rain signal from available FDSN data (SL network). We study the time variant spectral signatures of reaches in steep mountain, graded upland and wide basin landscapes across northern Slovenia and exemplarily invert the seismic data for key flood parameters: water level and debris flux, and propagation velocity. We discuss the detection range of existing earthquake seismometer networks and the potential to improve those with respect to flood quantification. Our analysis highlights the compound effects of channel geometry, event magnitude and network density for flood detection and signature consistency.

How to cite: Dietze, M., Jemec Auflič, M., Petan, S., and Bezak, N.: August 2023 Slovenian flood anatomy from national seismometer network data analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7490, https://doi.org/10.5194/egusphere-egu24-7490, 2024.

EGU24-7576 | ECS | Orals | GM2.1

Constructing a New Catalogue of Greenland's Iceberg Calving Events through Seismic Data Analysis and Machine Learning 

Selina Wetter, Clément Hibert, Anne Mangeney, and Eléonore Stutzmann

The Greenland ice sheet, a critical component of the global climate system, has played a substantial role in rising sea level, marked by a fourfold increase in mass loss due to iceberg calving between 1992-2000 and 2000-2011. Through the quantification of the spatio-temporal changes in Greenland’s ice mass loss resulting from iceberg calving, we gain a deeper understanding of the impacts of climate change.

The mass loss related to calving icebergs can be estimated by combining mechanical simulation of iceberg calving and inversion of seismic data. Seismic signals are generated by the time-varying force produced during iceberg calving on marine-terminating glacier termini. These events, known as glacial earthquakes, are recorded by the Greenland Ice Sheet Monitoring Network at tens of kilometres from the source.

However, differentiating these signals from tectonic events, anthropogenic noise, and other natural noise is challenging due to their complex frequency content (1-100s), multi-phase waveforms and low amplitude. To overcome this difficulty, we use a detection algorithm based on the Short-Time Average over Long-Time Average (STA/LTA) method and combine it with machine learning (Random Forests). By training the machine learning algorithm on seismic event catalogues containing more than 400 earthquakes and glacial earthquakes each, our approach is apt for identifying glacial earthquakes. Applying this methodology to continuous data offers the possibility to uncover smaller and previously undetected events. As a result, we present a comprehensive catalogue spanning several years and discuss its relevance and reliability. The generated catalogue allows us to develop new methods to better understand the spatio-temporal evolution of the ice-calving activity in the region. Among these, we will initially focus on locating and inverting the force of the largest events, providing a basis for testing new machine learning approaches for the characterisation of the source. This includes extracting properties like the iceberg volume and shape from both large and smaller events, ultimately advancing our understanding of Greenland's ice mass loss dynamics.

How to cite: Wetter, S., Hibert, C., Mangeney, A., and Stutzmann, E.: Constructing a New Catalogue of Greenland's Iceberg Calving Events through Seismic Data Analysis and Machine Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7576, https://doi.org/10.5194/egusphere-egu24-7576, 2024.

EGU24-8208 | ECS | Orals | GM2.1

Icequake source location using seismic data in Dålk Glacier, East Antarctica 

Shun Zhao, Zheyi Cao, Yuanyuan Gu, Chen Lv, Zhitu Ma, Tong Hao, Gang Qiao, Benfeng Wang, and Rongxing Li

Icequakes are closely associated with glacier movement and rupture, and their temporal and spatial distribution patterns can portray the dynamics of glaciers. In this study, we used the seismic data recorded by 34 short-period Smartsolo seismometers deployed in Dålk Glacier, East Antarctica for about 60 days to detect and locate icequakes. The array was deployed at the edge of the Dålk Glacier and across the grounding line previously generated by satellite observations. The recorded data were strongly affected by Antarctica storms and we selected two days with little wind noise for preliminary analysis. Using time-frequency analysis and particle motion, we found that the seismic events are either dominated by body waves or surface waves, which likely correspond to deep icequakes or near-surface crevasse icequakes. Since the propagation of surface waves is easier to analyze and possible detections of crevasse icequakes are more likely to be verified from satellite images, we chose to focus on surface wave signals in this preliminary analysis. We first filtered records to 5-20 Hz and manually examined records with clear surface wave arrivals. We then produced templates using these events to scan through our records. We successfully identified 89 events within the two-day period. Lastly, these signals were located using a grid-search approach for their latitudes and longitudes, together with an average group velocity for each event. Nearly half of the incidents were concentrated on the edges of rock outcrops, which suggests they were generated by the relative movement between the glacier and outcrops. The other half of the events was found in the eastern region, where a large number of surface crevasses were observed on satellite imagery. In addition, the optimal velocity from the grid search is ~2.8 km/s for events from the North and West, while the optimal velocity for events from the East is ~1.8 km/s. The difference in wave velocity suggests the existence of a boundary between rock and ice at a depth of about 100-150m within or near our seismometer array. By analyzing the amplitude variations of incidents in different directions recorded at various stations, we observed that this boundary is within our array and its location and geometry can be estimated. Compared to the grounding line predicted from satellite observations, our result shows that the boundary is offset to the East by ~100 m. The reason for this discrepancy will be further discussed in the meeting.

How to cite: Zhao, S., Cao, Z., Gu, Y., Lv, C., Ma, Z., Hao, T., Qiao, G., Wang, B., and Li, R.: Icequake source location using seismic data in Dålk Glacier, East Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8208, https://doi.org/10.5194/egusphere-egu24-8208, 2024.

EGU24-8304 | Posters on site | GM2.1

Water table height maps prediction from passive surface-wave dispersion using deep learning 

José Cunha Teixeira, Ludovic Bodet, Agnès Rivière, Marine Dangeard, Amélie Hallier, Alexandrine Gesret, Amine Dhemaied, and Joséphine Boisson Gaboriau

Monitoring underground water reservoirs is challenging due to limited spatial and temporal observations. This study presents an innovative approach utilizing supervised deep learning (DL), specifically a multilayer perceptron (MLP), and continuous passive-Multichannel Analysis of Surface Waves (passive-MASW) for constructing 2D water table height maps. The study site, geologically well-constrained, features two 20-meter-deep piezometers and a permanent 2D geophone array capturing train-induced surface waves. For each point of the 2D array, dispersion curves (DCs), displaying Rayleigh-wave phase velocities (VR) across a frequency range of 5 to 50 Hz, have been computed each day between December 2022 and September 2023. In the present study, these DCs are sampled in wavelengths ranging from 4.5 to 10.5 m in order to focus the monitoring on the expected water table depths. All VR data around one of the two piezometers is used to train the MLP model. Water table heights are then predicted across the entire geophone array, generating daily 2D piezometric maps. Model's performance is tested through cross-validation and comparisons with water table data at the second piezometer. Model’s efficiency is quantified with the root-mean-square error (RMSE) and the coefficient of determination (R²). A R² is estimated above 80 % for data surrounding the training piezometer and above 55 % for data surrounding the test piezometer. Additionally, the RMSE is impressively low at 0.03 m at both piezometers. Results showcase the effectiveness of DL in generating predictions of water table heights from passive-MASW data. This research contributes to advancing our understanding of subsurface hydrological dynamics, providing a valuable tool for water resource management and environmental monitoring. The ability to predict 2D piezometric maps from a single piezometer is particularly noteworthy, offering a practical and efficient solution for monitoring water table variations across broader spatial extents.

How to cite: Cunha Teixeira, J., Bodet, L., Rivière, A., Dangeard, M., Hallier, A., Gesret, A., Dhemaied, A., and Boisson Gaboriau, J.: Water table height maps prediction from passive surface-wave dispersion using deep learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8304, https://doi.org/10.5194/egusphere-egu24-8304, 2024.

EGU24-9067 | ECS | Posters on site | GM2.1

Seasonal variations in sediment transport from ice sheet terminus through a proglacial forefield. A case study from Leverett glacier, Western Kalaallit Nunaat (Greenland).  

Marjolein Gevers, Stuart N. Lane, Floreana Miesen, Davide Mancini, Matthew Jenkin, Chloé Bouscary, Faye Perchanok, and Ian Delaney

Current climatic warming is causing accelerated melt of the Greenland Ice Sheet. Whilst the changing hydrological response is well known, the sediment export as well as the geomorphic changes in the proglacial area remain uncertain.  

Here we present records of sediment transport from melt seasons 2022 and 2023 in the proglacial area of Leverett glacier, a land terminating glacier outlet on the Western part of the Greenland Ice Sheet. The proglacial area here is very well denifed by a waterfall cutting through bedrock functioning as terminal gauge, which allows for the installation of hydrological stations. These hydrological gauging stations, containing turbidity and pressure sensors, allow for estimation of discharge and suspended sediment concentrations over the melt season. Variations in bedload transport can be analysed using the sesimic data obtained from the geophones placed on the river bank close to the hydrological gauging stations. To convert the recorded seismic data into bedload flux, a Fluvial Inversion Model is used, which is calibrated using active seismics surveys and the water stage data from the hydrological gauging stations.

The dataset allows us to investigate the relationships between bedload, suspended sediment, and water discharge from the Leverett glacier as well as sediment transport and deposition in the proglacial area. We observe several spring events in the first half of July, where suspended sediment concentration and water discharge increase simultaneously at the start of the melt season. During the first half of August, we observe a clear dilution signal, where increase in water discharge coincides with a decrease in suspended sediment concentration From insights about the relationship between water and sediment discharge from the ice sheet, we can speculate about the sediment export response to increased water discharge from the Ice Sheet.

How to cite: Gevers, M., Lane, S. N., Miesen, F., Mancini, D., Jenkin, M., Bouscary, C., Perchanok, F., and Delaney, I.: Seasonal variations in sediment transport from ice sheet terminus through a proglacial forefield. A case study from Leverett glacier, Western Kalaallit Nunaat (Greenland). , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9067, https://doi.org/10.5194/egusphere-egu24-9067, 2024.

Groundwater storage monitoring is now one of the most promising application of seismic interferometry techniques. In steep mountain environments, where drilling wells is particularly challenging, the use of seismic stations to retrieve relative seismic velocity changes could fundamentally advance our understanding of groundwater dynamics. However, very few studies have looked at seismic velocity variations at the scale of a single steep topography unit. Here, we estimate velocity variations from six stations covering a distance of 3.5 km on a single mountain ridge in the county of Hualien, Taiwan. One station was placed at the top of a ridge (900m elevation), two at the mid-slope of the topography and two others at the bottom (200m elevation), near the river banks. The aim is twofold: Determining how homogenous these velocity changes are and understanding the possible impact of topography on groundwater variations in a mountainous setting. Results from auto-correlations and cross-correlations are compared with meteorological data and other geophysical analysis. We identify the average hydrological dynamics of the ridge unit and connect the residual velocity changes to local site characteristics and upstream weather conditions.

How to cite: Illien, L., Kuehn, J., Andermann, C., and Hovius, N.: Monitoring groundwater dynamics in a mountain ridge using seismic interferometry: Influence of topography, local subsurface structure and meteorological conditions., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9608, https://doi.org/10.5194/egusphere-egu24-9608, 2024.

EGU24-9822 | ECS | Posters on site | GM2.1

Intermediate-depth icequakes at Greenland’s fastest outlet glacier: evidence for englacial thrust faulting? 

Ana Nap, Fabian Walter, Martin P. Lüthi, Adrien Wehrlé, Janneke van Ginkel, Andrea Kneib-Walter, and Hugo Rousseau

In traditional glacier flow laws and consequently glacier models, a widely used assumption is that the ice behaves as a non-Newtonian viscous fluid that slides either across hard bedrock or via deforming subglacial till. Elastic effects and brittle deformation within the ice are often neglected for simplicity, as even ubiquitous surface crevasses are difficult to capture in numerical schemes. While there is ample seismological evidence that stick-slip motion plays a significant role in basal sliding of both alpine and polar glaciers, similar evidence is lacking for brittle deformation within the ice mass itself. Instead, it is commonly assumed that the ice moves and deforms in a purely viscous or ductile manner, which may not be an accurate representation of reality.

Here, we present observations of high-frequency (>50Hz) signals of intermediate-depth seismic sources occurring along the fast ice-stream of Sermeq Kujalleq in Kangia (Jakobshavn Isbræ), Greenland’s fastest flowing outlet glacier. The waveform characteristics of these events closely resemble the known characteristics of waveforms associated with basal stick-slip events, making them easily distinguishable from the more prevalent icequake signals generated by surface crevasse opening and propagation. However, differences in P and S wave arrival times as well as probabilistic source locations show that these events occur at ~170-400 m depth, whereas at those locations the glacier has a total depth of approximately 2000 m. Hence, these events cannot be caused by stick-slip motion at the base of the glacier, but must originate from englacial dislocations such as e.g., thrust faulting. Hundreds of these englacial icequakes are observed at several seismic arrays that were temporarily deployed in 2022 and 2023 along the fast ice-stream of Sermeq Kujalleq. Using waveform clustering and source mechanism analysis, we discuss the role of these events in ice dynamics and in particular englacial deformation.

 

How to cite: Nap, A., Walter, F., Lüthi, M. P., Wehrlé, A., van Ginkel, J., Kneib-Walter, A., and Rousseau, H.: Intermediate-depth icequakes at Greenland’s fastest outlet glacier: evidence for englacial thrust faulting?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9822, https://doi.org/10.5194/egusphere-egu24-9822, 2024.

EGU24-10147 | ECS | Posters on site | GM2.1

Uncovering Stick-Slip Events: Denoising Cryoseismological Distributed Acoustic Sensing Data with an Autoencoder 

Johanna Zitt, Patrick Paitz, Fabian Walter, and Josefine Umlauft

One major challenge in cryoseismology is that signals of interest are often buried within the high noise level emitted by a multitude of environmental processes. Specifically, basal sources such as stick-slip events often stay unnoticed due to long travel paths to surface sensors and accompanied wave attenuation. Yet, stick-slip events play a crucial role in understanding glacier sliding and therefore, it is of great interest to investigate their spatio-temporal evolution, across the entire glacier from its ablation to its accumulation zone.
Distributed Acoustic Sensing (DAS) is a technology for measuring strain rate by using common fiber-optic cables in combination with an interrogation unit. This technology enables us to acquire seismic data over an entire glacier with great spatial and temporal resolution. To unmask stick-slip events, new techniques are required that effectively and efficiently denoise large cryoseismological DAS data sets. 
Here, we propose an autoencoder, a type of deep neural network, which is able to separate the incoherent environmental noise from the temporally and spatially coherent signals of interest (e.g., stick-slip events or crevasse formations). We trained the autoencoder in order to denoise a DAS data set acquired on Rhonegletscher, Switzerland, in July 2020. Due to the highly active and dynamic cryospheric environment as well as non-ideal cable-ground coupling the collected DAS data are characterized by a low signal to noise ratio compared to classical point sensors.
Several models were trained on a variety of data subsets, differing in recording positions (ablation or accumulation zone), event types (stick-slip event or surface event) and the quantity of training events. We compare and discuss the denoising capabilities of these models with several metrics, such as inter-channel coherence, similarity between seismometer and DAS recordings, and visual assessment. This evaluation is conducted while considering different data types in a qualitative and quantitative manner. All models show an increase in inter-channel coherence of the seismic records after denoising. Further, all models uncover previously undetected stick-slip events, whereby models trained on manually picked training data perform better than models trained on randomly picked training data. We believe that the application of our models can improve the understanding of basal stick-slip information in cryoseismological DAS datasets, potentially uncovering previously hidden information.

How to cite: Zitt, J., Paitz, P., Walter, F., and Umlauft, J.: Uncovering Stick-Slip Events: Denoising Cryoseismological Distributed Acoustic Sensing Data with an Autoencoder, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10147, https://doi.org/10.5194/egusphere-egu24-10147, 2024.

EGU24-10347 | Orals | GM2.1 | Highlight

The seismic signature of skiing 

Heiner Igel, Sophie Brass, Fabian Lindner, Koen Van Noten, Raphael de Plaen, Joachim Wassermann, Felix Bernauer, and Thomas Lecocq

In March 2023 the annual winter school SKIENCE (www.skience.de) was held in the Bavaria alps, south-east of Munich. The topic was environmental seismology with a focus on seismic monitoring using ambient seismic noise. The winter school had strong practical training aspects. Prior to the meeting 12 5Hz nodes (SmartSolo) were deployed in the valley near Bayrischzell with the goal to explore local structure and site effects using interferometric methods. During the midweek free afternoon the 12 SmartSolo nodes were installed on both sides of a slalom run with several gates through which participants of the winterschool skied one after each other. First inspection of the data showed that clear signals of the skiers could be identified. Here, we report on attempts to use the seismic data records to recover the tracks of the skiers as moving seismic sources. Questions associated with this experiment are at which points in the tracks seismic energy is generated, where exactly the incoming signals propagate and with what velocities, and how well the source locations can be backprojected. A simple theoretical model is used to develop the inversion tools to recover the moving sources.   

How to cite: Igel, H., Brass, S., Lindner, F., Van Noten, K., de Plaen, R., Wassermann, J., Bernauer, F., and Lecocq, T.: The seismic signature of skiing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10347, https://doi.org/10.5194/egusphere-egu24-10347, 2024.

EGU24-10380 | Orals | GM2.1

Observing ice-bed weakening on a fast flowing glacier with seismic noise interferometry and unsupevised clustering. 

Léonard Seydoux, Ugo Nanni, Lucien Goulet, Thomas Pauze, and Andreas Köhler
Glacier flow instability often results from changes at the ice-bed interface. However, understanding these processes is challenging due to limited access to the glacier bed. Our study focuses on Kongsvegen glacier in Svalbard, which shows signs of an upcoming rapid flow event. To investigate the potential causes of such acceleration, we installed 20 seismometers along the glacier flowline, from the surface down to 350 m near the ice-bed interface. We combined our seismic monitoring with measurements of surface velocity, basal water pressure, and basal sediment deformation.
First, we performed seismic noise interferometry between stations located along the glacier flowline with inter-station distances ranging from 1 to 12 km. We observed a multi-year decrease in seismic velocity, with a seasonal signal superimposed, showing a melt-season decrease in seismic velocity of 2 to 4%. We compared our observations with 1D models and concluded on the presence of damaged basal ice and/or a weakening of the subglacial sediments. This indicates a mechanical weakening of the ice-bed interface, promoting further glacier acceleration.
Second, we conducted unsupervised clustering of seismic waveforms using a novel approach based on a deep scattering network. Doing so, we observed a yearly increase in surface crevasses concomitant with an increase in basal events, likely indicating stick-slip and/or basal crevasses. This increase is particularly visible during winter, where the number of events steadily increases from year to year. We suggest that, in response to an initial glacier acceleration, new crevasses have opened, providing access pathways for surface meltwater to the base of the glacier, affecting the ice-bed coupling. This mechanism represents a positive hydro-mechanical feedback that fuels further acceleration and crevassing, potentially having wider implications for triggering glacier-wide instabilities, increasing short-term sea-level rise, and local hazards.

 

How to cite: Seydoux, L., Nanni, U., Goulet, L., Pauze, T., and Köhler, A.: Observing ice-bed weakening on a fast flowing glacier with seismic noise interferometry and unsupevised clustering., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10380, https://doi.org/10.5194/egusphere-egu24-10380, 2024.

EGU24-10525 | ECS | Posters on site | GM2.1

Deep Embedded Clustering of a Cryo-Data-Cube 

Julia Peters, Felix Roth, and Josefine Umaluft

Cryoseismological records consist of numerous signals generated by various sources within or surrounding glacial ice, including icequakes, water flow, avalanches, rockfalls, wind, or precipitation. This results in a notably high noise level within the data, posing a significant challenge in detecting and distinguishing individual seismic events and sources.

Our research employs Deep Embedded Clustering (DEC) to address this challenge, focusing on the analysis of a Distributed Acoustic Sensing (DAS) dataset acquired on Rhonegletscher (Switzerland) in 2020.

To visualize and efficiently streamline the DEC processing of this substantial volume of data, we reorganize the numerous continuous DAS channels as a 3D data cube featuring the three dimensions: time, space, and frequency. The DEC approach involves first transforming high-dimensional seismic data into a more manageable lower-dimensional latent space using an autoencoder. This transformation is vital in emphasizing the essential characteristics of the data, thereby enabling more effective clustering. Subsequently, the DEC algorithm autonomously categorizes these seismic signals into distinct clusters based on their unique spatio-temporal characteristics, without the prerequisite of manual annotation.

The primary aim of this approach is to utilize DEC for the effective mapping of clearly defined spatio-temporal clusters within cryoseismological records. This approach is geared towards achieving a more nuanced understanding of the various sources contributing to these records and their complex dynamics. By successfully segregating these clusters, the aim is to reveal new insights into the complex processes and interactions in glacial environments.

Both the DAS data and the clustering results can be explored interactively using the data cube viewer Lexcube. Come find us at the poster stand!

How to cite: Peters, J., Roth, F., and Umaluft, J.: Deep Embedded Clustering of a Cryo-Data-Cube, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10525, https://doi.org/10.5194/egusphere-egu24-10525, 2024.

EGU24-11086 | ECS | Posters on site | GM2.1

Support vector regression-based model for the prediction of surface displacement and vibration using meteorological data 

Chi En Hi, Kate Huihsuan Chen, Wei Peng, Wan-Ru Huang, Hsiang Han Chen, Ko Chih Wang, and Kuo En Ching

Can we use environmental data to predict changes in surface displacement fields? Do severe weather events alter the near-surface geomechanical properties? The seasonal variations in GPS time series and crustal seismic velocities have been frequently observed at different study areas. Such variation has been tied closely to the cyclic hydrological loads [e.g., Costain et al., 1987; Heki, 2003; Roth et al., 1992], which its association with tectonic deformation remains debated. Using the 15 years meteorological, geodetic, and seismic data recorded in southern Taiwan (near Chaozhou fault where the background seismicity level is low), we aim to explore the possibility of predicting surface displacement and vibration using climatic variables (time series of temperature, precipitation, and wind velocity) and groundwater levels. Here the Support Vector Regression (SVR) model is developed for the prediction of the GNSS and seismic signals, while 15-yr datasets are divided into groups of 75%  and 25% datasets for model calibration and testing. When the predicted surface displacement is compared with the real data, the R-square values reach 95%, indicating the applicability of SVR model on long-term surface deformation prediction. In the future, long-term prediction model will be conducted to target several extreme weather events in Taiwan.

How to cite: Hi, C. E., Chen, K. H., Peng, W., Huang, W.-R., Chen, H. H., Wang, K. C., and Ching, K. E.: Support vector regression-based model for the prediction of surface displacement and vibration using meteorological data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11086, https://doi.org/10.5194/egusphere-egu24-11086, 2024.

EGU24-11562 | ECS | Posters on site | GM2.1 | Highlight

How trees sway and what it tells us about their overall vitality 

Jana Roth, Karin Mora, Djamil Al-Halbouni, Ronny Richter, Teja Kattenborn, Sebastian Johannes Wieneke, Ana Bastos, Alexandra Weigelt, Christian Wirth, and Josefine Umlauft

Changing climate, especially the increase in frequency and intensity of extreme events such as heat waves and droughts, poses a significant challenge to the biosphere, threatening biodiversity overall and specifically exacerbating tree mortality. Countermeasures and management actions often prove insufficient due to delayed visual indicators of tree stress. 

Real-time monitoring of physiological and structural changes in tree characteristics and related abiotic parameters, such as sap flow, leaf angle, or soil moisture, plays a crucial role in tracking the trees’ overall vitality. However, conventional monitoring approaches are often expensive, require high maintenance and are therefore not feasible on a larger spatio-temporal scale.     

In a groundbreaking approach, we propose to measure the seismic oscillation generated by tree sway under specific weather conditions, potentially reflecting tree vitality. Specifically, oscillations are related to material properties of leaves, branches, and trunks, which change when they become dry. Seismic measurements offer scalability and low maintenance, making them viable for extensive spatio-temporal coverage. Through integrated observations from dense seismic arrays, direct tree trait measurements, and meteorological parameters collected at the research arboretum (ARBOfun) during autumn 2023, we successfully isolated the seismic fingerprint of tree sway.

However, the unique nature of this novel data introduces challenges, for example noise from human and animal activities, allowing for only time series snapshots. To overcome these challenges, we explored various time series and frequency related analysis methods to separate the tree signal from other influences.

How to cite: Roth, J., Mora, K., Al-Halbouni, D., Richter, R., Kattenborn, T., Wieneke, S. J., Bastos, A., Weigelt, A., Wirth, C., and Umlauft, J.: How trees sway and what it tells us about their overall vitality, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11562, https://doi.org/10.5194/egusphere-egu24-11562, 2024.

EGU24-13007 | Orals | GM2.1 | Highlight

Assessing the seismic signature of turbulent flow and intense bedload transport from designed laboratory experiments 

Florent Gimbert, Maarten Bakker, Marco Piantini, Alain Recking, and Michael Lamb

The field of fluvial seismology has undergone significant advances over the past decade. The development of dedicated physical theories and their applications in various contexts have allowed separating the respective contributions of turbulent flow and bedload transport, such that physical parameters like flow depth and sediment flux may be inferred from seismic observations. However, the quantitative link between signal characteristics (amplitude, frequency) and the underlying physics yet involves simplified considerations that do not necessarily apply to more complex situations, such as for example under rough flow conditions or during extreme floods.

In this talk I will present results from laboratory experiments that we designed specifically in order to quantify the seismic signature of flow turbulence and intense bedload transport under a range of conditions using force sensors coupled to the river bed. On one hand, I will show that existing theory regarding turbulent flow properly captures the main characteristics of the seismic source, but that additional dependencies on flow conditions and particle-wake development need to be included for more accurate predictions. On the other hand, I will show that existing theory regarding bedload transport fails at capturing the main characteristics of the seismic source under intense bedload transport conditions associated with complex changes in internal flow dynamics. In this case the seismic source appears to be a decreased function of solid concentration, as opposed to an increased function such as considered in current theories, which we suggest is due to grain impacts being agitation-controlled rather than bed-roughness controlled. Finally, I will discuss possible ways towards building more generic theories of ground motion induced by sediment transport.  

How to cite: Gimbert, F., Bakker, M., Piantini, M., Recking, A., and Lamb, M.: Assessing the seismic signature of turbulent flow and intense bedload transport from designed laboratory experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13007, https://doi.org/10.5194/egusphere-egu24-13007, 2024.

EGU24-13208 | Posters on site | GM2.1 | Highlight

Analysis of Precursors and Collapse of June 15, 2023, Brienz/Brinzauls Rockslide in Switzerland: Integrating Seismic and Remote Sensing Observations 

Sibashish Dash, Michael Dietze, Fabian Walter, Marcel Fulde, Wandi Wang, Mahdi Motagh, and Niels Hovius

The early detection of slope instability and the monitoring of frequent hazard processes in mountainous regions is of paramount importance due to their sudden occurrence, and the risk of causing numerous fatalities and significant economic damage. The recent collapse of the Brienz/Brinzauls rockslide on June 15, 2023, in an active, deep-seated mountain slope deformation complex in Switzerland, provides a unique opportunity to investigate the evolution of precursors leading up to the collapse. Early identification of accelerating rockmass enabled us to set up a network of five broadband seismometers, strategically deployed to systematically record seismic signals in close proximity, reducing information loss due to attenuation of seismic waves. 

The internal rock damage dynamics in the displacing rock mass were interacting with external seasonal forcings, such as snow melt and rainfall, for years preceding the collapse at approximately 21:38:00 UTC on June 15, 2023. Seismic events of various types have been detected in the entire landslide complex, characterised by the recurrence of identical seismic events that aggregate prominently within the most rapid compartment, referred to as the "Insel," positioned directly above the village of Brienz. This study aims to investigate the influence of seasonal forcings on accelerating the rate of displacements and to understand how the nature of detected precursors changes over time. We systematically examine the feedback loop between seasonal triggers and gravity-driven internal rock damage under changing stress conditions during fluctuations in compartment velocity. Initially, events exhibit accelerations following periods of precipitation, but subsequently, a runaway acceleration in seismic events was noted even during dry periods. The locations detected reveal communication between the upper and lower parts of the “Insel” mass in the build-up to the main collapse. From June 1 onward, there is a consistent and gradual increase in the mean spectral power of the recurring seismic events, with a rapid escalation observed in the three days leading up to the collapse. Interestingly, on the final day preceding the main collapse, a significant decrease in the mean spectral power was identified. To complement seismic observations, the spatial and temporal changes in pre-failure slope instability for the period 05.2014-06.2023 were also analyzed using Sentinel-1 synthetic aperture radar (SAR) data using a multi-temporal interferometric (MTI) approach. MTI analysis indicates several patches of instability and surface deformation on the slope, along with signs of significant surface displacement of a few centimetres per year, also manifesting in the village of Brienz. To facilitate automatic detection and classification, we apply data science methods to various statistical seismic attributes of the identified precursors. This study contributes to advancing our understanding of the mechanisms leading to rockslide collapses, with the potential to significantly enhance warning system effectiveness.

How to cite: Dash, S., Dietze, M., Walter, F., Fulde, M., Wang, W., Motagh, M., and Hovius, N.: Analysis of Precursors and Collapse of June 15, 2023, Brienz/Brinzauls Rockslide in Switzerland: Integrating Seismic and Remote Sensing Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13208, https://doi.org/10.5194/egusphere-egu24-13208, 2024.

EGU24-13569 | Orals | GM2.1

Validation of seismic bedload saltation model: From laboratory flume to field-scale experiments 

Wei-An Chao, Chi-Yao Hung, and Yu-Shiu Chen

Reliable bedload flux estimations are necessary for a variety of applications such as sedimentation engineering, flood risk mitigation and river restoration. Several seismic physical models with considering different bedload transport mechanisms have been proposed, which provided an opportunity to have quantitative observation in practical. However, a lack of direct measurements of bedload fluxes in field application cause a challenge for the validation of seismic models. In the practical application, the bedload impact kinematics (elasticity and velocity) and particle dynamics assumed in models are crucial for achieving high accuracy in bedload inversion. In-situ seismic parameters such as shear-wave velocity and seismic quality factor are also required to reduce the uncertainty in model prediction. Thus, this study first conducts bedload transport experiments in a flume laboratory to understand the kinematics and mechanics of particle transport by using the smart rock embedded with accelerometer and gyroscope, geophone and hydrophone. For the field-scale experiments, we further studied distributed acoustic sensing (DAS) measurement during the experiments, which can record the dynamic strain in fiber optic cable under riverbed. Both case of laboratory flume and field-scale experiments, we will evaluate the performance of the different physical models by comparing in-situ measurements of bedload mass and impact forces recorded by the smart rock. In the case of field experiment, we adopted the active and passive seismic surface wave exploration to investigate the properties of wave propagation and attenuation. The effect of the process of rolling and/or sliding particles, as opposed to saltating particles, contributing in seismic signal generation, was also explored.   

How to cite: Chao, W.-A., Hung, C.-Y., and Chen, Y.-S.: Validation of seismic bedload saltation model: From laboratory flume to field-scale experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13569, https://doi.org/10.5194/egusphere-egu24-13569, 2024.

EGU24-13722 | ECS | Posters on site | GM2.1

Investigating bedload transport in mountain rivers through seismic methods: the new monitoring station in the Solda River (South Tyrol, Italy) 

Marco Piantini, Matthias Bonfrisco, Rudi Nadalet, Roberto Dinale, Gianluca Vignoli, Gianluca Antonacci, Silvia Simoni, Fabrizio Zanotti, Stefano Crema, Marco Cavalli, Alessandro Sarretta, Velio Coviello, and Francesco Comiti

Bedload transport plays a key role in the morphodynamics of mountain rivers by regulating erosion and aggradation processes. However, it is still challenging to estimate and predict bedload transport rates with reliability because of a complex interplay between different types of sediment supply, hydrological forcing, and fluvial morphologies. In the last two decades, passive sensors recording the seismic signals generated by coarse particles impacting the riverbed have been proposed to provide a continuous indirect measure of bedload transport. Among them, geophone plates and seismometers have been demonstrated to be valid tools.

Here, we present the preliminary results from the new monitoring station of Stilfserbrücke/Ponte Stelvio designed and built to monitor both water and sediment fluxes in the Solda River (Italian Alps). The station, mainly financed through two ERDF 2014-2020 projects of the Autonomous Province of Bolzano South-Tyrol, is part of the operational gauging network of the Civil Protection Agency of Bolzano (Italy). Bedload transport is indirectly monitored by sixteen geophone plates covering the downstream side of a consolidation check dam. The signal associated with the vibrations generated by particle impacts on the steel plates is recorded continuously with a sampling frequency of 5 kHz. In order to calibrate the instruments, direct bedload measurements have been carried out through an innovative bridge-like structure (BLS) consisting of an electronically controlled mobile trap. The collected samples have been sieved by hand to characterize their grain size distribution. At the end of summer 2023 we have also explored the possibility to additionally monitor the river with seismometers installed on the left bank at the monitoring station. We have analyzed the signal from the geophone plates by counting the number of times its amplitude exceeds a preselected threshold expressed in volts (i.e. the impulses, Rickenmann et al., 2014), and by computing its power (Coviello et al., 2022). The best correlation is found between impulses (threshold of 0.04 V) and the bedload transport rates of particles larger than 22 mm, with a power law regression characterized by a coefficient of determination (R2) of 0.85 and a low root mean square error (RMSE) of 3.3 kg/min against peak bedload transport rates reaching 41 kg/min.

These findings pave the way towards ensuring the continuous quantification of coarse sediment transport in the Solda River, allowing for the evaluation of the impact of glacier retreat and slope instabilities associated with global warming on river dynamics. Finally, the simultaneous use of seismometers may provide a unique opportunity to test existing theoretical models on bedload-induced ground vibrations through the indirect measurements provided by the geophone plates.

References

Coviello, V., Vignoli, G., Simoni, S., Bertoldi, W., Engel, M., Buter, A., et al. (2022). Bedload fluxes in a glacier-fed river at multiple temporal scales. Water Resources Research, 58, e2021WR031873.

Rickenmann, D., Turowski, J.M., Fritschi, B., Wyss, C., Laronne, J., Barzilai, R., Reid, I., Kreisler, A., Aigner, J., Seitz, H. and Habersack, H. (2014), Bedload transport measurements with impact plate geophones: comparison of sensor calibration in different gravel-bed streams. Earth Surf. Process. Landforms, 39: 928-942.

How to cite: Piantini, M., Bonfrisco, M., Nadalet, R., Dinale, R., Vignoli, G., Antonacci, G., Simoni, S., Zanotti, F., Crema, S., Cavalli, M., Sarretta, A., Coviello, V., and Comiti, F.: Investigating bedload transport in mountain rivers through seismic methods: the new monitoring station in the Solda River (South Tyrol, Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13722, https://doi.org/10.5194/egusphere-egu24-13722, 2024.

Solid Earth Sciences:SE07 Faults and Earthquakes: Networks, Precursors, Monitoring Systems and Numerical Modelling Techniques

Research on new methods and equipment for seismological monitoring of glaciers on the Qinghai-Tibet Plateau

Lei Zou1, Richard Games2, ……

1 SmartSolo Inc., China

2 SmartSolo Inc., Huston, USA

Abstract: Glacier seismology combines the advantages of glaciology and seismology to form a young interdisciplinary subject. Icequakes are vibrations produced during the movement and breakup of glaciers, ranging from small squeaks to sudden ruptures or slides equivalent to earthquakes (MW7). According to the location and mechanism of icequake occurrence, icequakes can be divided into five types: surface fissures, stick-slip movement, iceberg calving, subglacial flow, and hydraulic fracturing. In addition to traditional seismological methods, icequake research can also be conducted using multidisciplinary methods such as GPS, numerical simulation, and glacier physical properties. Icequake research can further explore the occurrence process and risk assessment of ice avalanches. We review advances in glacier seismology.

Our users use SmartSolo scientific instruments to successfully analyze ice avalanche events through vibration signals by observing multi-parameter glacier environment and climate changes, combined with seismological observation instruments. Provide a new and effective monitoring method for glacier seismic monitoring. It enriches the process observation and risk assessment methods of ice avalanche occurrence, and the combination of multiple parameters further improves the accuracy and effectiveness of ice avalanche event monitoring.

How to cite: Gamez, R. and Zou, L.: Research on new methods and equipment for seismological monitoring of glaciers on the Qinghai-Tibet Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13798, https://doi.org/10.5194/egusphere-egu24-13798, 2024.

EGU24-13859 | ECS | Orals | GM2.1 | Highlight

An overview of environmental seismology used to study the internal structure of the North East Greenland Ice Stream  

Emma Pearce, Dimitri Zigone, Andreas Fitchner, Coen Hofstede, Joachim Rimpot, Johanna Brehmer-Moltmann, and Olaf Eisen

In 2022 a network of 23 seismometers and Distributed Acoustic Sensing (DAS) fibre optic cable were deployed on the North East Greenland Ice Stream (NEGIS). Using a combination of environmental seismology methods, we were able to gain a comprehensive understanding of the ice streams internal structure, giving insight into its past and present dynamics.  

From ambient noise recording, we utilise the 9-component correlation tensors associated with all station pairs.  We derived dispersion curves for Rayleigh and Love wave group velocities with usable data in the frequencies from 1 to 25 Hz. These data are then inverted to obtain shear wave velocity measurements for the top 150 m of the ice stream using an MCMC approach. We reveal variations in the radial anisotropy for both the along and across-flow components.

Alternative methods of passive seismology were explored, such as using the seismic signal from an airplane landing. The recorded signals by the surface DAS cable displayed exceptional clarity, revealing at least 15 visible wave propagation modes, including various Rayleigh and pseudo-acoustic waves within the frequency range of 8 to 55 Hz.

Seismic While Drilling (SWD) methods utilising the noise from ice core drilling and cutting at NEGIS were investigated as an unconventional signal at the borehole camp. While not successful in this instance, recommendations for future deployments were provided to optimize the utilisation of these techniques.

These methods collectively offer insight into the layering of snow, firn, and ice within the ice stream, indicating the presence of seismic anisotropy. Demonstrating the effectiveness of short-duration (2-3 weeks) seismic deployments in glaciology.  

How to cite: Pearce, E., Zigone, D., Fitchner, A., Hofstede, C., Rimpot, J., Brehmer-Moltmann, J., and Eisen, O.: An overview of environmental seismology used to study the internal structure of the North East Greenland Ice Stream , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13859, https://doi.org/10.5194/egusphere-egu24-13859, 2024.

EGU24-14117 | ECS | Posters on site | GM2.1

Probing relation between rainfall pattern and seismic detected water-and-sediment events 

Guan-Syun Huang and Wei-An Chao

Southern Taiwan often experienced abundant monsoon seasons during seasonal transitions, and monsoons and typhoons controlled the rainfall patterns to be complex and varied, resulting the high intensity, prolonged duration, and high concentration. The aforementioned rainfall characteristics can increase the risk of water-and-sediment-related disasters.  To explore the correlation between rainfall patterns and water-and-sediment events, this study employs micro-seismic monitoring network, and the selected Putanpunuas River in southern Taiwan as a case study site. Frequent landslides in the middle and upper watershed supply the river with stable source of sediment materials. Consequently, during the periods with strong precipitation, our study site the shows high susceptibility of water-and-sediment events.  The seismic network comprises one station (BNAR) on the right bank and two stations (BNAL, BNAS) on the left bank downstream of the Putanpunuas River, and an additional station (BNAF) at the confluence of the Putanpunuas River and the Laonong River.  By conducting a series of spectrogram analysis, the average power spectral density (PSD) time series of each station can be computed. Then, we further quantified the seismic signal characteristic parameters for each water-and-sediment events.  This study initially employs various machine learning algorithms (Decision Tree, KNN, K-means, Auto-sklearn) to develop an optimized model for identifying water-and-sediment events, classifying different types of events, such as flooding (FD), debris flooding (DFD) and debris flow (DF), then providing a 4-year-length (2019~2023) catalog of water-and-sediment events.  Rainfall data including hourly precipitation and LiDAR estimated rainfall are collected from the rain gauge stations nearby study area. Using a certain definition (e.g., 4 mm/hr threshold for picking start time) of rain episodes, we calculated total number of episodes and established a rain episodes catalog.  The aforementioned datasets allow us to probe the relationship between rainfall patterns and water-and-sediment events, aiding in inferring the main rain episodes characteristics associated with water-and-sediment events . The  results of this study can be applied to predict potential water-and-sediment event types in Putanpunuas River using rainfall information as input. This can facilitate relevant early warning operations, reducing the societal impact of water-and-sediment disasters.

Key words : Rainfall Patterns, Rain Episode, Micro-seismic monitoring network, Putanpunuas River, Water-and-Sediment Events, Machine Learning

How to cite: Huang, G.-S. and Chao, W.-A.: Probing relation between rainfall pattern and seismic detected water-and-sediment events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14117, https://doi.org/10.5194/egusphere-egu24-14117, 2024.

EGU24-14125 | ECS | Posters on site | GM2.1

Studying field-scale dam breach due to overtopping by using seismic signals 

You-Lin Hou, Wei-An Chao, Chi-Yao Hung, Su-Chin Chen, and Tzu-Yao Chang

A dam is the natural damming of a river by the geohazards, such as landslides and debris flows. When the dam materials are eroded or washed away due to scour, erosion, and/or an increasing in water level of dam lake, leading dam breach and catastrophic outburst of flooding, which affect the downstream area. Therefore, real-time monitoring of dam failure would facilitate relevant early warning message for the impending floods. The conventional approach using image-based analysis and hydrological measurements is for providing timely warnings of breach; however, landslide dams often occur in mountainous areas, where the methods may face limitations of in-situ measurement. Additionally, the observations of landslide dam breach process are rare and cause the large uncertainties in scientific research. Hence, this study utilizes seismic signals to study the overtopping breach process of field-scale dams. Seismic signals serve as a monitoring tool while simultaneously monitoring the seismic characteristics of overtopping failure in the field-scale dams. In fact, there is a scarcity of observed seismic signal records related to dam breach process in field. Even if some observational data is available, there is a lack of corresponding image analysis or hydrological information for comprehensive discussions. Thus, this study aims to observe and understand overtopping failure through a series of field-scale dam breach experiments. In this study, we first investigate the time-frequency characteristics of seismic power spectral density (PSD) corresponding to the dam breaches primarily involves retrogression erosion, longitudinal and lateral erosion, and the stabilization period. Then, the results of photographic analysis (surface flow velocity, breach geometry), discharge measurements and the time-frequency characteristics of PSD are integrated to discuss the phenomena associated with dam breach. Finally, a series of comparison between compacted and non-compacted dams for PSD spectrogram patterns. The time-series of mean PSD and flow discharge data for the compacted dam exhibit a single-peak and short-term signal duration. Notably, the mean PSD time-series recorded by the seismic station located at the left bank showed a similar trend with flow discharge. Furthermore, during the retrogression erosion period, significant high-frequency PSD energy can be observed only in a case of the compacted dam. In contrast, the PSD energy for the non-compacted dam is concentrated in a relatively lower frequency range (between 10 to 30 Hz). The PSD and flow time series data for the non-compacted dam present a bimodal shape with longer time duration. Based on the flow velocity of breach notch, both in the compacted and non-compacted dams, the maximum velocity occurred during the transition from longitudinal to lateral erosion. In practical application, the results of seismic characteristics for the non-compacted dam case can be applied to the monitoring of dams formed by natural landslides in the field. Our results not only advance in understanding of the field-scale dam breach process but also can be directly applied to breach flooding warnings.
Key words : field-scale dam breach experiments, overtopping breach, power spectral density, time-frequency characteristic

How to cite: Hou, Y.-L., Chao, W.-A., Hung, C.-Y., Chen, S.-C., and Chang, T.-Y.: Studying field-scale dam breach due to overtopping by using seismic signals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14125, https://doi.org/10.5194/egusphere-egu24-14125, 2024.

EGU24-15165 | Orals | GM2.1

Investigating Rainfall-Driven Resonance Frequency Changes in a Natural Rock Formation 

Juliane Starke, Laurent Baillet, Eric Larose, Antoine Guillemot, and Laurence Audin

Rainfall, temperature variations, and chemical processes are well-known drivers of rock erosion. The impact of rainfall on rocks is not well-understood yet but may impact the mechanical properties (including damage, rigidity, deformation) of the rock. In this study, we exhibit the effect of rainfall events on the resonance frequency of a rock column.

Resonance frequencies of structures have been utilized to monitor rock columns due to their sensitivity to changes in the rock apparent rigidity (1). For instance, daily temperature changes induce stress variations in the rock column, resulting in a daily cycle of resonance frequency changes (thermal-acousto-elasticity, 2).

This research involves long-term monitoring of the first resonance frequency of a 50 m high limestone cliff covering the Chauvet cave in the Ardèche plateau, SW France, exposed to climatic solicitations including daily solar radiation, air temperature fluctuations, and rain events. The rock column was equipped with seismic and meteorologic stations and monitored continuously during three years.

To demonstrate the effect of rainfall events on the mechanical properties of the rock, we calculated the resonance frequency depending only on air temperature and solar radiation, using a simple bivariate linear regression. The regression provides well-fitting results for dry periods but shows larger deviations during most rainy periods. This indicates that rain has an effect on the changes in rock resonance frequency. Identifying and quantifying these changes would be a key factor in understanding the evolution of damage.

 

1) Bottelin, P., Baillet, L., Larose, E., Jongmans, D., Hantz, D., Brenguier, O., ... & Helmstetter, A. (2017). Monitoring rock reinforcement works with ambient vibrations: La Bourne case study (Vercors, France). Engineering Geology, 226, 136-145.

2) Guillemot, A., Baillet, L., Larose, E., & Bottelin, P. (2022). Changes in resonance frequency of rock columns due to thermoelastic effects on a daily scale: observations, modelling and insights to improve monitoring systems. Geophysical Journal International, 231(2), 894-906.

How to cite: Starke, J., Baillet, L., Larose, E., Guillemot, A., and Audin, L.: Investigating Rainfall-Driven Resonance Frequency Changes in a Natural Rock Formation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15165, https://doi.org/10.5194/egusphere-egu24-15165, 2024.

EGU24-15365 | Posters on site | GM2.1

Automatic Monitoring of Seismogenic Slope Failure Activity at Brienz (Switzerland) Using Distributed Acoustic Sensing and Semi-Supervised Learning 

Jiahui Kang, Fabian Walter, Patrick Paitz, Johannes Aichele, Pascal Edme, Andreas Fichtner, and Lorenz Meier

Distributed Acoustic Sensing (DAS) represents a leap in seismic monitoring capabilities. Compared to traditional single-seismometer stations, DAS measures seismic strain at meter to sub-meter intervals along fiber-optic cables thus offering unprecedented temporal and spatial resolution. Leveraging the resolution of DAS enables us to monitor and detect seismogenic processes in the domain of hazardous mass-movements, including catastrophic rock avalanches.

Here, we present a semi-supervised neural network algorithm for screening DAS data related to mass movements at the Brienz landslide in Eastern Switzerland, which partially failed on 15 June 2023. A DAS interrogator connected to a 10 km-long dark fiber provided by Swisscom Broadcast AG near the landslide recorded seismic data from 16 May to 30 June 2023, with a sampling frequency of 200 Hz and a channel spacing of 4m. During a test period from June 1 to June 19, 2023, a total of 634 characteristic waveforms potentially related to slope failures, including the 15 June 2023 event, were detected, along with vehicle and other anthropogenic noise sources with characteristic diurnal and weekday/weekend variations.

For information extraction, we selected a subset of adjacent DAS channels, which include cable sections that were parallel to the failure event trajectory and thus particularly sensitive to mass movement activity. To facilitate efficient processing, we downsampled the data to 20 Hz, considering that slope failure events predominantly excite seismicity at below 10 Hz. We conceptualize the DAS data as a series of images representing consecutive strain rate data in the two dimensions of time and space. To bring out signal coherence between DAS channels, we transform the waveforms into cross-spectral density matrices (CSDM’s) which serve as the input image for unsupervised feature learning using an autoencoder (AE). Leveraging the features learned from the AE, we focus on activity classification using approximately 1500 samples. As ground truth for the slope failure class, we utilize concurrent Doppler radar data. The radar provides an event magnitude, which scales with failure volume and the number of individual rockfalls. Furthermore, the radar provides a measure of the moving mass’s trajectory length and front speed. The radar detected 516 slope failures during the test period.

Our algorithm captures 41.09 % of the slope failures recorded by the Doppler radar. The undetected events mainly have low radar magnitudes suggesting that they are associated with mass movements generating reduced seismic activity. Among the slope failure-type signals detected by DAS, 87.85% are also present in the radar catalogue. Interference from vehicle or human-triggered seismic waves, deteriorating the signal-to-noise ratio significantly, poses a challenge for our algorithm to differentiate between slope failures and those activities. Our study thus provides a benchmark for future natural hazard monitoring and suggests that using existing fiber optic infrastructure has a high potential for early warning purposes.

How to cite: Kang, J., Walter, F., Paitz, P., Aichele, J., Edme, P., Fichtner, A., and Meier, L.: Automatic Monitoring of Seismogenic Slope Failure Activity at Brienz (Switzerland) Using Distributed Acoustic Sensing and Semi-Supervised Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15365, https://doi.org/10.5194/egusphere-egu24-15365, 2024.

EGU24-15794 | ECS | Orals | GM2.1 | Highlight

Monitoring subsurface changes in a quick clay area during extreme weather 

Charlotte Bruland, Andreas Köhler, Anna Maria Dichiarante, Volker Oye, and Ivan Van Bever

Some of the more densely populated areas in Norway are in potential quick clay zones. When disturbed, the structure of quick clay can suddenly collapse, and behave and flow as a liquid, potentially having disastrous impact over large areas One of the triggering factors for quick clay slides is heavy rainfall. Here, we focus on passive seismic data from two Raspberry shake sensors located in an urban area in Oslo, Norway with quick clay in the subsurface. Using coda wave interferometry, near-surface velocity variations are estimated during the extreme weather ”Hans” (August 2023).

We compute auto-correlations and single station cross-correlations of anthropogenic seismic noise (> 1 Hz) over a two-year period leading up to ”Hans”. We observe environmental velocity fluctuations well correlated with air temperature, precipitation and the water level in a nearby river. In particular, freezing and thawing produces strong changes in seismic velocity (up to 4 %). Disregarding freezing, we see the largest change in seismic velocity following the heavy rainfall associated with ”Hans”. This extreme event is associated with a sharp velocity drop anti-correlated with pore pressure. The surface wave-coda is sensitive to changes in shear wave velocity, which in turn can be used to detect changes of the subsurface properties. Therefore, observed velocity variations at the site could have potential for monitoring and early warning of quick clay instabilities.

How to cite: Bruland, C., Köhler, A., Dichiarante, A. M., Oye, V., and Van Bever, I.: Monitoring subsurface changes in a quick clay area during extreme weather, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15794, https://doi.org/10.5194/egusphere-egu24-15794, 2024.

EGU24-16742 | ECS | Posters on site | GM2.1

Detection and localisation of wadi flow events utilizing seismic sensors 

Robert Krüger, Michael Dietze, Xabier Blanch, Jens Grundmann, Issa El-Hussain, Ghazi Al-Rawas, and Anette Eltner

In Oman, the frequency of flash floods has significantly increased in recent years. This phenomenon is correlated with climate change, resulting in an intensification of the atmospheric water cycle. Consequently, a further escalation of flash floods can be anticipated in the future. In Oman, the issue of flash floods is exacerbated by the frequent occurrence of tropical cyclones. Furthermore, the rapid expansion of urban areas, in some cases extending directly into wadis, coupled with the advancing sealing of the ground and insufficient drainage systems, leads to an increased risk of flooding. This is accompanied by substantial property damage and recurring loss of life.

Despite the growing danger posed by flash floods, there is currently no early warning system for precise prediction of these events in Oman. To establish such a system, densely distributed networks for rainfall and water level measurements would be required. However, due to the challenging topography and vastness of the country, implementing such networks is currently not feasible.

Recent studies have shown that seismic sensors could be used for measuring flow conditions. Further, seismic networks could be utilized to detect and track extreme flow events. The increasing availability of low-cost seismic sensors opens up the possibility of instrumenting previously ungauged wadi systems. However, the question remains if seismic networks can pick up smaller flow events and flow events happening in multiple smaller catchments at the same time.

In this study we used flow data from wadi gauge stations in the Al-Batinah Region (NW Oman) and data from broadband seismometers of the Earthquake Monitoring Center to research how flow events of various sizes can be detected by seismic networks. Initial results suggest that flow regimes in wadi systems offer favourable conditions for detection, as they mainly change between flow and no flow conditions. As the amplitude of seismic signals decreases with distance from the source, detection range is limited by background noise. To overcome this, low-cost seismic sensors have recently been installed in a wadi system together with camera based river gauges. Further work utilizing this data is currently ongoing.

How to cite: Krüger, R., Dietze, M., Blanch, X., Grundmann, J., El-Hussain, I., Al-Rawas, G., and Eltner, A.: Detection and localisation of wadi flow events utilizing seismic sensors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16742, https://doi.org/10.5194/egusphere-egu24-16742, 2024.

EGU24-17219 | ECS | Posters on site | GM2.1

Towards seismic monitoring of terrestial ecosystems: an exploratory data analysis of the SeisSavanna dataset 

Rene Steinmann, Tarje Nissen-Meyer, Fabrice Cotton, Frederik Tilmann, and Beth Mortimer

Our planet experiences ongoing unrest across various scales, from human footsteps to the powerful forces of volcanic eruptions and megathrust earthquakes. Seismic sensors, typically employed for geophysical studies, record diverse phenomena, including ground vibrations caused by the movement of terrestrial animals, known as footfall signals. The recently released SeisSavanna dataset comprises approximately 70,637 footfall signals from 11 different species in the African savanna. Consequently, ground-based vibrations might represent an underexplored sensory mode for continuously monitoring habitat usage and undisturbed animal behavior. To gain a deeper understanding of footfall signals, we conduct exploratory data analysis on the SeisSavanna dataset. Utilizing a scattering transform, we capture the distinctive features of footfall signals, creating a high-level and interpretable data representation for subsequent analyses. Seismogram atlases and clustering enable us to group similar types of footfall signals and investigate the signal-altering path and site effects, providing a comprehensive overview of the entire dataset. Moreover, this data-driven approach serves as a quality check for the species labels retrieved from co-located camera traps with a limited angle of view.

How to cite: Steinmann, R., Nissen-Meyer, T., Cotton, F., Tilmann, F., and Mortimer, B.: Towards seismic monitoring of terrestial ecosystems: an exploratory data analysis of the SeisSavanna dataset, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17219, https://doi.org/10.5194/egusphere-egu24-17219, 2024.

EGU24-17786 | Orals | GM2.1

Monitoring the mechanics of mountain permafrost using ambient noise seismology 

Antoine Guillemot, Eric Larose, Laurent Baillet, Agnès Helmstetter, Xavier Bodin, and Reynald Delaloye

Since last decades, coda wave interferometry (CWI) from ambient seismic noise has become an efficient method to probe continuous temporal changes of mechanical properties of the subsurface and crust. This method has successfully been used for environmental seismology issues, in a view of investigating the response of subsurface to environmental changes, in particular hydrological and thermal forcings (2). More, it has contributed to monitoring instabilities such rock slopes or landslides (3). Applying these methods to permafrost is then relevant to assess and monitor its mechanical response to environmental forcings.

As lobate or tongue-shaped superficial landforms composed of frozen rock debris, active rock glaciers are widespread features of mountain permafrost (4), potentially causing emerging hazards linked to permafrost thawing and debris flows.

Passive seismic instrumentation has been deployed for several years at Gugla, Tsarmine (Valais, Switzerland) and Laurichard (Hautes-Alpes, France) rock glaciers.

CWI has been applied to compute daily averaged dV/V (or relative change in velocity of the surface waves). For the three sites studied, seasonal variations of shear stiffness have been measured, associated with freeze-thawing cycles (5) (6). We located these daily fluctuations in depth by using a 1D coda wave inversion scheme. We also tracked water-induced power spectral density (PSD) and we detected microseismic events, highlighting the role of water inputs in changing the mechanical state, thus accelerating the whole rock glacier body. Also, we developed a viscoelastic model to explain the seasonal variability of the kinematics of rock glaciers. Combined with other geophysical methods, environmental seismology paves hence the way to deeply understand the mechanical response of mountain permafrost landforms to thermo-hydrological forcings.

 References

  • Richter, T., Sens‐Schönfelder, C., Kind, R., & Asch, G. (2014). Comprehensive observation and modeling of earthquake and temperature‐related seismic velocity changes in northern Chile with passive image interferometry. Journal of Geophysical Research: Solid Earth, 119(6), 4747-4765
  • Le Breton, M., Bontemps, N., Guillemot, A., Baillet, L., & Larose, É. (2021). Landslide monitoring using seismic ambient noise correlation: challenges and applications. Earth-Science Reviews, 216, 103518.
  • Haeberli, W., Hallet, B., Arenson, L., Elconin, R., Humlum, O., Kääb, A., ... & Mühll, D. V. (2006). Permafrost creep and rock glacier dynamics.Permafrost and periglacial processes, 17(3), 189-214.
  • Guillemot, A., Helmstetter, A., Larose, É., Baillet, L., Garambois, S., Mayoraz, R., & Delaloye, R. (2020). Seismic monitoring in the Gugla rock glacier (Switzerland): ambient noise correlation, microseismicity and modelling.Geophysical Journal International, 221(3), 1719-1735. https://doi.org/10.1093/gji/ggaa097
  • Guillemot, A., Baillet, L., Garambois, S., Bodin, X., Helmstetter, A., Mayoraz, R., and Larose, E.: Modal sensitivity of rock glaciers to elastic changes from spectral seismic noise monitoring and modeling, The Cryosphere, 15, 501–529, https://doi.org/10.5194/tc-15-501-2021, 2021.

How to cite: Guillemot, A., Larose, E., Baillet, L., Helmstetter, A., Bodin, X., and Delaloye, R.: Monitoring the mechanics of mountain permafrost using ambient noise seismology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17786, https://doi.org/10.5194/egusphere-egu24-17786, 2024.

EGU24-17787 | Posters on site | GM2.1

(Multi)annual variations in the microseism of the Northern Atlantic 

Lars Wiesenberg, Sunke Schmidtko, and Thomas Meier

Microseism is one of the biggest parts of ambient seismic noise and has a huge effect on seismic measurements on almost every regular broad band seismometer, but especially in coastal areas. Generally, microseism describes the interaction of water waves and the seafloor. Its variation over time is from huge interest. It is often used on short-period scales to investigate local weather effects, like storm events or seasonal variations. In this work, we are investigating variations in the microseism of the Northern Atlantic on multiannual scales. For that reason, we utilize up to 50 years of seismic data from several onshore stations across Central and Northern Europe. The focus is on secondary microseism of the Northern Atlantic which is normally sensitive at periods of ≈10 to 5 s. It is estimated over two-hour segments of seismic data, separately. Secondary microseism is post processed to eliminate effects of data gaps or outliers before lowpass filtering for the periods of interest. Besides of a dominant peak at one year period, secondary microseism shows also distinct variations at several year of periods. These variations clearly correlate with the North-Atlantic-Oscillation Index (NAO), not only visually, but also quantitatively and might therefore be relatable to climate variations affecting the North Atlantic.

How to cite: Wiesenberg, L., Schmidtko, S., and Meier, T.: (Multi)annual variations in the microseism of the Northern Atlantic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17787, https://doi.org/10.5194/egusphere-egu24-17787, 2024.

Predicting bedload transport is a key element of water-related hazard assessment and hydraulic engineering applications. However, knowledge of bedload transport processes remains limited, particularly in steep mountain streams. Previous studies have revealed that bedload transport rates in mountain streams exhibits a large spatio-temporal variability for given flow conditions. This results from the direct influence of streambed structure on bedload transport, where sediment movement, in turn, interacts with streambed evolution. Furthermore, variations in sediment availability contribute to the spatio-temporal bedload variability. The complex interactions between water flow, bedload transport, and bed structure are not yet fully understood. In this work, systematic flume experiments were conducted to investigate the acoustic signal responses of impact plate geophone systems generated by bedload particles impacting on the flume bed during experimental flows in the transitional regime. The experiments varied in the grain size distribution of the transported particles and the bed material, and the compactness and the water content of the flume bed. Geophones were installed on the underside of steel plates flush with the flume bed both upstream and downstream to effectively capture the changes in vibration signals generated by the moving bedload mass impacting on the bed. Triaxial force sensors were utilized to measure the impact forces of the bedload particles on the bed material layer. Pore-water pressure sensors were embedded at different depths in the bed material to measure the change in pore-water pressure in the bed under the influence of the bedload mass. Flow velocities and depths of the moving bedload mass were recorded using a binocular high-speed camera and were analyzed with an image processing method. The observed vibration signals and fluctuating forces were used to calculate the characteristic parameters of bedload transport using calibrated relationships and seismic theory. In addition, a high-precision Digital Elevation Model (DEM) of the bed was constructed using the photography and 3D modeling techniques. The results of this work show that geotechnical material parameters of the bed such as compactness, compression modulus, and grain size distribution may affect the changes of bed structure caused by bedload transport This in turn influences the spatio-temporal variability of the transport rate. The findings of this work may help to explain the variability of the bedload transport process in mountain streams.

How to cite: Chen, Z., Badoux, A., and Rickenmann, D.: Quantitative measurement of bedload transport variability with acoustic monitoring systems: Insight from controlled laboratory flume experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18262, https://doi.org/10.5194/egusphere-egu24-18262, 2024.

EGU24-18668 | Posters on site | GM2.1

Bedload sediment dynamics in two contrasting alpine glacier headwater catchments 

Simon Cook, Darrel Swift, Kristen Cook, Christoff Andermann, Michael Dietze, William Wenban, and Rory White

Glaciated landscapes are showing an amplified reaction to global climate change. Glacial streams are the primary conveyor belts of the incipient sediment cascade, implementing the export of glacially scoured sediment to lower reaches, where the exported sediment controls fluvial geometry, valley floor evolution and ecosystem functioning, water reservoir lifetime and energy production in several alpine countries. Despite that importance, especially of the coarse bedload fraction, there is a striking lack of knowledge about the timing, magnitude and control factors of bedload flux in glacial streams. This is predominantly due to the difficulties to obtain such flux data by classic empirical approaches that require direct in-stream sampling. Here, we pursue a seismic approach to bedload transport quantification, where geophysical sensors are installed along the banks of glacial streams that continuously record ground motion caused by both the turbulent flow of the stream and coarse particle impact on the river bed. We installed small geophone networks along straight reaches of streams draining the glacierised catchments of Oberaargletscher and Steingletscher in Switzerland and recorded the target signals for several days in August 2022, when the melt driven, diurnal river stage fluctuated significantly. River level, turbidity and stream geometry were also observed. Ground parameters for the inverse seismic-model approach were determined using an active seismic survey. We present results of the instrumentation concepts, parameter estimation and data inversion. This allows a discussion of the temporal variability, non-linearity and site-specific nature of hydraulic and sediment transport patterns in catchments where sediment export is dominated by glacial processes.

How to cite: Cook, S., Swift, D., Cook, K., Andermann, C., Dietze, M., Wenban, W., and White, R.: Bedload sediment dynamics in two contrasting alpine glacier headwater catchments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18668, https://doi.org/10.5194/egusphere-egu24-18668, 2024.

EGU24-20192 | ECS | Orals | GM2.1

Boulder-induced Turbulence Drives Shift in Seismic Frequency 

Ron Nativ, Jonathan Laronne, Jens Turowski, Jui-Ming Chang, Ci-Jian Yang, Niels Hovius, Wen-Sheng Chen, and Wen-Yen Chang

Turbulent flows capable of mobilizing sediments, despite being studied over the past 100 years, continue to constitute an elusive process. In environmental seismology, seismic waves generated by the interplay of surface processes and the Earth offer a key to unraveling the dynamics of river processes. We studied the seismic signals emitted during floods in two tributaries with large boulders. Early findings indicated an unusually high dominant seismic frequency, reaching 2-4 times the frequency observed in nearby channels with smoother beds. Consistent anomalous high-frequency content during times without sediment transport prompts our hypothesis that turbulence is the key process driving the frequency shift. We hypothesized that the most energetic turbulent eddies, dominating the signal, decrease in size in response to the boulder-influenced constrained flow geometry, and we argue that this effect possesses a first-order control on the frequency shift. A frequency scaling law with boulder spacing, approximating boulder-induced eddy size, shows good agreement with our field data. The dynamics of the eddies under changing flow velocity are well predicted by a power law function of seismic frequency with water depth. The trend breaks at the onset of bedload transport, indicating that energy is dissipated through the partitioning between turbulence and sediment transport. Our study emphasizes that seismic frequency effectively records the dominant morphology and fluvial processes, revealing the intricate interaction between roughness and seismic energy.

How to cite: Nativ, R., Laronne, J., Turowski, J., Chang, J.-M., Yang, C.-J., Hovius, N., Chen, W.-S., and Chang, W.-Y.: Boulder-induced Turbulence Drives Shift in Seismic Frequency, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20192, https://doi.org/10.5194/egusphere-egu24-20192, 2024.

EGU24-394 | ECS | PICO | GM2.2 | Highlight

Smart boulders for real-time detection of hazardous movement on landslides 

Kate Newby, Georgina Bennett, Kyle Roskilly, Alessandro Sgarabotto, Chunbo Luo, and Irene Manzella

Landslides present a substantial hazard across coastal and mountainous regions in Europe and worldwide, and are becoming increasingly prevalent due to extreme rainfall linked to climate change. There is a need to develop new technologies for landslide monitoring and early warning systems, as traditional approaches alone are insufficient due to low temporal resolution and high costs. The SENSUM project (smart SENSing of landscapes Undergoing hazardous hydrogeologic Movement) has deployed manmade boulders, called SlideCubes, that monitor landslide movement in real-time across two coastal slow-moving landslide sites in southern England (Lyme Regis and Isle of Wight).

SlideCubes are embedded with low-power low-cost sensors that comprise an inertial measurement unit (IMU with accelerometers and gyroscopes) and magnetometers. The SlideCubes are part of a wireless sensor network (WSN) that communicates via Long Range Wide Area Network (LoRaWAN) and Internet of Things (IoT) technologies. Rain gauges and other third-party sensors can be easily integrated into the network to provide additional data sources. Our novel WSN allows for near real-time wireless monitoring of the landslides, only requiring field visits to replace sensor batteries every 9-12 months. The sensors are motion-triggered, significantly saving battery power, meaning the WSN requires little and less frequent maintenance than other sensor-based monitoring approaches. This allows long-term remote measurement of landslide kinematics (inferred from SlideCubes) and initiation of movement, which is key for early warning.

In the present work, initial findings from the SlideCubes installed at two UK-based sites are discussed. The movement events detected and recorded over 2 years are validated by periodic GNSS and drone imagery surveys. We present an overview of temporal and spatial motion across both landslide sites and evaluate sensor performance. Using gyroscope and accelerometer readings from field and laboratory data, we demonstrate how types of motion (e.g. rolling, sliding) can begin to be categorised, which is not possible with the accelerometer alone. This research will be developed in future with machine learning to detect hazardous movement including large magnitude catastrophic events. These findings will be integrated into a SENSUM early warning online portal, in development, for use by stakeholders.

How to cite: Newby, K., Bennett, G., Roskilly, K., Sgarabotto, A., Luo, C., and Manzella, I.: Smart boulders for real-time detection of hazardous movement on landslides, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-394, https://doi.org/10.5194/egusphere-egu24-394, 2024.

EGU24-558 | ECS | PICO | GM2.2

Estimating bed material transport in Himalayan streams using the virtual velocity approach 

Anshul Yadav, Sumit Sen, Luca Mao, and Marwan A. Hassan

This study investigates sediment mobility and transport dynamics in two Himalayan rivers, the Aglar and Paligad Rivers, during both monsoon and non-monsoon flows. Employing the virtual velocity approach, key parameters such as bed proportional mobility (Y), active layer depth (ds), and displacement length were measured to estimate the virtual velocity of mobilized grains. Local parameters (0.5 m sub-sections) and wetted cross-sectional averages were utilized. Using local parameters, the total annual bed material transport was determined as 67,100 t (±20,400 t) and 18,400 t (±6,000 t) for the Aglar and Paligad Rivers, respectively, with nearly 60% occurring during the monsoon. The significant contribution of non-monsoonal flows (~ 40 %) could be ascertained to higher enough flows in specific sub-sections inducing partial or full mobility. Still, the contribution of partial transport (PT) remained lower (< 6%). In contrast, based on cross-section average parameters, total transport was estimated at 42,300 t (±15,800 t) and 12,200 t (±4,700 t) for the Aglar and Paligad Rivers, respectively, with approximately 79% and 68% occurring during the monsoon. The contribution of PT increased to nearly 18% and 29% for the Aglar and Paligad Rivers, respectively, attributed to the averaging effects of shallower sections. Furthermore, the interdependence of partial transport on Y and full transport on ds leads to discontinuities in transport curves, prompting the proposal of a unified function to represent transport extent for both partial and full transport conditions. The unified function ensured the generation of continuous transport curves, yielding similar transport patterns concerning the contribution of PT, FT, monsoonal, and non-monsoonal flows. The findings are particularly relevant for efficient river management as the region houses several hydropower plants and is highly susceptible to climate change.

Keywords:

Painted tracers, partial transport, full transport, active layer, monsoonal flows

How to cite: Yadav, A., Sen, S., Mao, L., and A. Hassan, M.: Estimating bed material transport in Himalayan streams using the virtual velocity approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-558, https://doi.org/10.5194/egusphere-egu24-558, 2024.

EGU24-1825 | ECS | PICO | GM2.2

The Transition from Granular Debris Flow to Bedload: a force balance perspective 

Islam Koa, Alain Recking, and Florent Gimbert

Sediment transport can occur in a so-called “debris flow” form, where concentrations are high and movement is driven by gravity. Previous studies have predominantly used simple rheological fluids or uniform granular materials to study the characteristics of debris flows. However, a fundamental question remains regarding the characteristics of the complex granular debris flow, and the transition from granular debris flow to bedload remains poorly understood. In this contribution, we present an experiment in the laboratory where this phenomenon could be studied. Our experiment setup, a 6-meter-long wooden flume, involved a 1 m-long low-slope trapezoidal storage area and a 5 m-long and 0.1 m-wide wooden flume channel inclined at 33%, equipped with a force plate and hydrometer sensors. Our observations show that self-formed, highly concentrated sediment accumulation in the storage area, influenced by flow rate, generates pulses that exhibit three phases: the tail phase containing sand particles, the body phase containing a mixture of particles, and the front phase containing coarse particles. As discharge was dynamically increased, two distinct domains controlled by the forefront coarse particles were observed. Firstly, at low flow (0.14-0.16 l/sec), a static-dynamic domain is identified, characterized by a high sediment concentration and very low velocity. This generates a high resultant force magnitude that affects the forefront coarse particles, resulting in debris-flow-like pulses controlled by the sediment density. Secondly, at higher flows (0.17–0.24 l/sec), a full-dynamic domain is identified, characterized by a lower sediment concentration and very high velocities. This behavior generates hyperconcenrated flow-like pulses controlled by momentum transfer between the pulse phases. We demonstrated that the transition from debris and hyperconcentrated flow to bedload is controlled by the coarse particle’s mobility, whose threshold discharge in clear water was 0.22 l/sec. The important role played by the sand fraction is also demonstrated, which permits the static dynamics behavior by ensuring momentum transfer either directly, by mass transfer, or indirectly by reducing the medium porosity.

How to cite: Koa, I., Recking, A., and Gimbert, F.: The Transition from Granular Debris Flow to Bedload: a force balance perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1825, https://doi.org/10.5194/egusphere-egu24-1825, 2024.

EGU24-9717 | ECS | PICO | GM2.2 | Highlight

Vertical Mixing of Suspended Sediment in Big Rivers using ADCP data and Machine Learning 

Chris Tomsett, Julian Leyland, Steve Darby, Tom Gernon, Dan Parsons, Thea Hincks, and Josh Wolstenholme

Sediment is an intrinsic component of the fluvial network, supplying material for floodplains and coastal landforms which provide resilience during flooding and storms. As a result, an understanding of the fluvial processes that control how much sediment moves through our river systems, and how this varies across the globe, is of fundamental importance.

For the purpose of estimating sediment delivery through the fluvial network, it is often assumed that rivers are well mixed through their vertical extent. However, empirical data reveals that there is frequently large variability in the concentration of sediment through the water column. Better understanding this variability is of interest to the geomorphological community to help explain variations in sediment transport and improve estimates of sediment flux.

In this research, we utilise a collection of Acoustic Doppler Current Profiler (ADCP) data from large rivers across the globe to investigate variations in the vertical distribution of suspended sediment. Calibrations of ADCP backscatter to Suspended Sediment Concentration (SSC) from the wider literature are used, alongside median grainsize and acoustic frequency, to create a Machine Learning (ML) model from which SSC from uncalibrated ADCPs can be estimated. This new ML model is subsequently implemented to explore the variations in the vertical mixing of suspended sediment both temporally and spatially. This variability is explored to identify the importance of catchment characteristics in determining variations in suspended sediment concentration within the water column. Comparison of multiple river systems and their catchment characteristics, both between sites and through time, enables the identification of key attributes which exert a greater control on this variation through the water column. Subsequently, this leads to an improved understanding of sediment flux through the river system, whereby knowing the variation in sediment concentration within the water column can help to better calibrate current methods of estimating flux.

How to cite: Tomsett, C., Leyland, J., Darby, S., Gernon, T., Parsons, D., Hincks, T., and Wolstenholme, J.: Vertical Mixing of Suspended Sediment in Big Rivers using ADCP data and Machine Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9717, https://doi.org/10.5194/egusphere-egu24-9717, 2024.

EGU24-11132 | PICO | GM2.2

Comparing methods to quantify grain-scale sediment structure in gravel-bed rivers 

Rebecca Hodge, Hal Voepel, Elowyn Yager, Julian Leyland, Joel Johnson, David Sear, and Sharif Ahmed

Understanding when gravel moves in river beds is essential for a range of different applications, but is still surprisingly hard to predict. The critical shear stress at which a grain will move depends on its relative size and structure within the bed, and spatial and temporal changes in grain-scale structure are likely to be a major driver of changes in critical shear stress. Consequently grain-structure metrics such as protrusion, pivot angle and contact with any surrounding fine grained matrix are used as parameters in models to predict critical shear stress, and so there is an increasing demand for measurements of these parameters in order to improve our predictive ability. However, we do not have established methods for measuring these parameters, nor do we know whether different methods provide consistent results. Here we present and compare new datasets of sediment structure metrics collected from eight locations in a small gravel-bed stream using three different methods: direct field-based measurements, terrestrial laser scanning (TLS), and computed tomography (CT) scanning. Using each method, we measure metrics including grain size distribution, grain protrusion and fine matrix content. We find that distributions of grain size are consistent between field-based and TLS data, but smaller in CT data. All three methods produce similar distributions of protrusion relative to grain size. There is also some consistency between field and CT measures of fine-grained matrix. However, the identification of similarity also depends on the type of analysis, and an alternative analysis shows less similarity in protrusion and fine-grained matrix between the different methods. Of the three methods, TLS-based approaches have potential to be most easily applied, and our analysis suggests that for grain-size and protrusion they perform as well as the alternative methods. However, they cannot currently be used for measuring fine-grained matrix content.

How to cite: Hodge, R., Voepel, H., Yager, E., Leyland, J., Johnson, J., Sear, D., and Ahmed, S.: Comparing methods to quantify grain-scale sediment structure in gravel-bed rivers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11132, https://doi.org/10.5194/egusphere-egu24-11132, 2024.

EGU24-11623 | ECS | PICO | GM2.2

Application of Entropy theory to estimate the sediment transport 

Farhad Bahmanpouri, Silvia Barbetta, Christian Massari, Domenico De Santis, Ashutosh Sharma, Ankit Agarwal, and Sumit Sen

Abstract: Sediment transport is a natural process where sediment particles can be deposited downstream and exacerbate flooding. The movement of sediments can be observed in flows through rivers, canals, and coastal areas which include suspended load transport and bed-load transport. Bed-load transport occurs in the area close to the riverbed, which is of particular importance in shaping the riverbed. The present research aims to investigate the sediment transport process by applying the Entropy concept as a theoretical approach to the activities of the project ‘Probabilistic floods and sediment transport forecasting in the Himalayas during extreme events’, funded in the context of the Italy-India joint science and technology cooperation program.

Specifically, based on collected field data through the Alaknanda River at Srinagar in India by current meter, first, the Entropy theory was applied to obtain the cross-sectional distribution of the velocity (based on recent developments of Entropy theory in Bahmanpouri et al., 2022a, b). The calculated mean velocity and discharge were compared with the observed data collected by the Central Water Commission (CWC). Next, shear velocity was calculated for different cross-sections based on different flow conditions. Further, shear stress was calculated based on two terms induced by skin friction and bedforms, respectively. Finally, the shield parameter was obtained based on shear velocity distribution to find out if sediment particles have the potential to be transported or not. Overall, the findings of the current research highlighted the potential of the theoretical method of Entropy to calculate sediment transport in developing countries.

 

Bahmanpouri, F., Barbetta, S., Gualtieri, C., Ianniruberto, M., Filizola, N., Termini, D., & Moramarco, T. (2022a). Prediction of river discharges at confluences based on entropy theory and surface-velocity measurements. Journal of Hydrology606, 127404.

Bahmanpouri, F., Eltner, A., Barbetta, S., Bertalan, L., & Moramarco, T. (2022b). Estimating the Average River Cross‐Section Velocity by Observing Only One Surface Velocity Value and Calibrating the Entropic Parameter. Water Resources Research58(10), e2021WR031821.

How to cite: Bahmanpouri, F., Barbetta, S., Massari, C., De Santis, D., Sharma, A., Agarwal, A., and Sen, S.: Application of Entropy theory to estimate the sediment transport, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11623, https://doi.org/10.5194/egusphere-egu24-11623, 2024.

EGU24-11689 | PICO | GM2.2 | Highlight

Using seismic and timelapse camera observations to study flood-induced morphological changes on an alpine gravel-bed reach 

Adele Johannot, Florent Gimbert, Alain Recking, and Marco Piantini

Morphological changes in alluvial rivers are very active and remain very complex to predict because of the high spatio-temporal variability of bedload. This strongly limits the ability of river managers to assess risk or conduct ecological restoration. With the recent development of non-intrusive methods to monitor bedload, such as seismic or acoustic tools, acquisition of data has been highly facilitated compared to direct measurement methods involving in-situ sampling. The challenging task remains in the interpretation of the signals during phases of intense bedload transport which are responsible for major morphological changes. The analysis of such signals requires a good understanding of the underlying physics as well as in-situ field observations to confort interpretation. In this work, we combine seismic with timelapse camera observations with the objective to have a better understanding of bedload behavior and its consequences on the morphology during floods on an alluvial reach of the Severaisse river in the French Alps. Data consists in 3 seismic sensors continuously recording at 200Hz from upstream to downstream along the reach, as well as data from 2 cameras taking timelapse photos of the reach at a 10 min interval during flood. We We find that high frequency seismic power, attributed to bedload, exhibits a characteristic scaling relationship against discharge, materialized by two different phases: a scaling of about 5 from above the threshold of motion (around 12m3/s water discharge) up to a critical discharge of 25 m3/s, and a scaling of about 1.4 above 25 m3/s. We interpret the first scaling to be due to bedload occurring in a diluted regime as described in previous models, and the second scaling to be due to bedload in an intense transport phase. This shift only occur during floods where we observe channel shifting or important re-working of the bed and we suppose that it represents a phase of intense transport responsible for morphological changes. Interestingly, for the most extreme flood with a return period of 50-years, the seismic power versus discharge relationship shows a distinct behavior form the other floods, materialized by a particularly larger and singular hysteresis. Next steps include understanding why this distinct signature occurs, quantify the morphological changes by calculating indexes from image analysis and investigate how bedload and hence the morphological changes depends on the season, characterized by a snow-melting spring and summer and rainy autumn and winter through a multi-year scale.

How to cite: Johannot, A., Gimbert, F., Recking, A., and Piantini, M.: Using seismic and timelapse camera observations to study flood-induced morphological changes on an alpine gravel-bed reach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11689, https://doi.org/10.5194/egusphere-egu24-11689, 2024.

Bedload transport plays a crucial role in shaping landscapes, yet monitoring it is challenging. Seismic sensors have emerged as valuable tools for continuous and non-invasive bedload transport monitoring. However, isolating the seismic signal of bedload transport from other environmental signals such as flow turbulence remains a challenge. While seismic waves propagate both vertically and horizontally, previous seismic bedload transport studies focused solely on the vertical component. This was based on the assumption that the bedload transport signal was mainly contained in Rayleigh waves which propagate with both vertical and horizontal motion, as opposed to Love waves which propagate with only horizontal motion. We hypothesise that there may be a significant signal from horizontally-propagating waves that characterises the interactions of coarse bedload impacts, and that this signal will be strongest in a flow-parallel orientation.  

This study employs the Horizontal-to-Vertical Spectral Ratio (HVSR) which is a passive method, commonly used in engineering seismology, that determines the ratio between horizontal and vertical seismic signal components. In this study, we explore the potential of the HVSR method to isolate the dominant component in seismic bedload transport signals and its applicability for monitoring fluvial processes within rivers. Using seismic, hydroacoustic, and hydrological measurements from the River Feshie in Scotland, our findings challenge prior belief that the seismic signal of bedload transport predominantly resides in the vertical component; instead, the horizontal component contains significant fluvial and bedload transport information. Due to differences in seismic wave characteristics, the HVSR method acts as a tool to isolate signals of bedload transport and water turbulence.

Additionally, the HVSR method demonstrates promise in effectively filtering out meteorological signals that may contaminate raw river-induced seismic signals, enabling more accurate monitoring of bedload transport occurrences. However, we acknowledge that the contributions of horizontal and vertical signals greatly depend on sensor location and site characteristics. This study emphasises the significance of utilising horizontal seismic signals for comprehensive bedload transport monitoring, presenting an opportunity for this method to enhance our understanding of complex fluvial processes within river systems.

How to cite: Matthews, B., Naylor, M., Sinclair, H., and Gervais, M.: Exploring vertical component dominance in seismic bedload transport signals: Horizontal-to-Vertical Spectral Ratio (HVSR) analysis in the River Feshie, Scotland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12924, https://doi.org/10.5194/egusphere-egu24-12924, 2024.

We present results from a particle-scale numerical model inspired by the idea that a majority of the time during transport capable floods, bedload transport in rivers is rarefied, and a stochastic process. Physical experiments conducted by others to explore this idea suggest that the time varying particle activity N measured within a control area A above the bed surface is described by a Poisson probability mass function (pmf), assuming an absence of collective entrainment. This implies that particles are sporadically entrained from the bed surface at rate λ with no “memory” of prior entrainment events, when and where local flow conditions favor particle lift or dislodgement. In this context we developed a new open source kinematic particle-scale model written in Python (Zwiep and Chartrand, 2022). Notably, the model includes no information related to the bed surface shear stress or Shields conditions, and no sediment transport functions are used to drive the model.

The model domain measures a use specified length nD of the particle diameter D, with a width of 1D. At present we have tested the model with 30 simulations using a uniform particle diameter. Each simulation was run for 1 million iterations to explore the governing model parameters: SRe is the number of subregions within the domain length nD; En is the particle entrainment rate per iteration, which we randomly sample from a Poisson pmf for a specified value of λ; lt is the particle travel distance which we randomly sample from either a lognormal distribution or a truncated normal distribution for specified values of the distribution expected value and standard deviation; and Sh is the vertical particle stacking height ranging from 1-3D.

The model produces a time varying signal of particle flux counted at downstream points of internal subregion domains, and at the downstream end of the model domain. The simplified particle bed changes “relative” elevation distributions through particle stacking and downstream motions of travel distance. An implication of particle stacking within the context of a stochastic model framework is a time varying signal of the average “particle age” defined as the number of iterations since last entrainment, as well as the average “particle age range” defined as the difference of the maximum and minimum particle ages, both metrics calculated at each iteration and across all subregions. The age dynamics correlate with the magnitude of N following an initial period of particle bed organization. Our initial tests suggest that the relatively simple model logic captures the essence of rarefied particle transport. We believe the model can be used to ask basic science questions, and as a classroom tool to introduce students to bedload transport in a straightforward and illustrative manner.

References:

Zwiep, S., & Chartrand, S. M. (2022). pySBeLT: A Python software package for stochastic sediment transport under rarefied conditions. Journal of Open Source Software, 7(74), 4282. https://doi.org/10.21105/joss.04282.

How to cite: Chartrand, S.: A simplified Python-based kinematic model of particle transport in rivers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13064, https://doi.org/10.5194/egusphere-egu24-13064, 2024.

EGU24-16886 | PICO | GM2.2

Resolving bedload flux variability 

Thomas Pähtz, Yulan Chen, Jiafeng Xie, Rémi Monthiller, Raphaël Maurin, Katharina Tholen, Hao-Che Ho, Peng Hu, Zhiguo He, and Orencio Durán

Bedload transport plays a vital role in shaping Earth’s environment by promoting the formation and growth of geological features of various scales, including ripples and dunes, deltas and fans, and laminations and cross-bedding. A key problem hampering our understanding of bedload-induced landscape evolution is the notoriously large variability commonly associated with measurements of bedload flux, even under controlled and highly idealized conditions in the laboratory, such as fully-developed, unidirectional open-channel flows over flat beds composed of grains of nearly uniform sizes. For example, two recent experimental studies report a nearly sixfold different nondimensionalized bedload flux at a comparable Shields number for spherical grains [1, 2]. The likely culprit is the immense difficulty experimentalists face in estimating the transport-driving bed shear stress. There is currently no universally accepted method of even determining the bed surface elevation in the presence of bedload transport, which is particularly problematic for shallow flows where small changes have a large effect. Neither is there agreement on how to account for the effects of sidewall friction, which become the stronger the smaller the width-to-depth ratio b/h of the open-channel flow. Standardly employed empirical sidewall corrections have arguably a greater resemblance to cooking recipes than to formal physically-derived methods. In addition to such experimental difficulties, there is the physical question of how grain shape, which usually is not controlled for in laboratory experiments, affects bedload flux. A recent prominently published study argued that grain shape is the predominant reason for bedload flux variability and put forward a semi-empirical, analytical bedload transport model to account for it [1].

Here, we compile data from existing experiments and existing and new DNS-DEM, LES-DEM, and RANS-DEM numerical simulations of turbulent bedload transport of shape-controlled grains, in which b/h varies between 0.1 and infinity (periodic boundary conditions in simulations). After employing a non-empirical sidewall correction, which we derived from the phenomenological theory of turbulence, and a granular-physics-based method to determine the bed surface elevation, all data for spherical grains of sufficient size collapse onto a single curve, resolving the experimental problem of bed shear stress determination. Furthermore, the combined data for spherical and non-spherical grains are in strong disagreement with the model of Ref. [1] but support our alternative analytical bedload model across grain shapes, bed slopes, flow strengths, and channel widths.

[1] Deal et al., Nature 613, 298 (2023). https://doi.org/10.1038/s41586-022-05564-6

[2] Ni & Capart, Geophysical Research Letters 45, 7000 (2018). https://doi.org/10.1029/2018GL077571

How to cite: Pähtz, T., Chen, Y., Xie, J., Monthiller, R., Maurin, R., Tholen, K., Ho, H.-C., Hu, P., He, Z., and Durán, O.: Resolving bedload flux variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16886, https://doi.org/10.5194/egusphere-egu24-16886, 2024.

EGU24-18899 | ECS | PICO | GM2.2

Hydro-acoustic multi-frequency measurements of suspended sediment flux in rivers 

Jakob Höllrigl, Koen Blanckaert, David Hurther, Guillaume Fromant, and Florian R. Storck

Currently, the estimation of suspended sediment concentration (SSC) fluxes in rivers relies on river discharge and an average SSC, the latter is commonly determined through optical turbidity measurements at a single point in the river cross-section. This approach has limitations, such as the SSC data being extrapolated from a one-point measurement and indirectly determined depending on regular sampling and laboratory analysis, which is cost-intensive.


Hydro-acoustic echosounders are an alternative to derive SSC across an entire profile, for accurate conversion from backscatter intensity to SSC knowledge of particle size is a requirement. In this approach, we present a method utilizing multi-frequency hydro-acoustic echosounding in addition to velocity measurements via an ADCP. Operating on various acoustic frequencies allows for the direct estimation of mean particle size from backscatter data at different frequencies over a water profile. River in-situ measurements as well as laboratory experiments have been conducted in different concentration as well as particle size distribution regimes.

How to cite: Höllrigl, J., Blanckaert, K., Hurther, D., Fromant, G., and Storck, F. R.: Hydro-acoustic multi-frequency measurements of suspended sediment flux in rivers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18899, https://doi.org/10.5194/egusphere-egu24-18899, 2024.

EGU24-18979 | ECS | PICO | GM2.2

Exploring moisture-constrained aeolian sediment transport through a discrete particle modelling framework 

Xiuqi Wang, Geert Campmans, Thomas Weinhart, Anthony Thornton, Stefan Luding, and Kathelijne Wijnberg

Moisture is a crucial environmental factor that shapes the dynamics of aeolian sediment transport along coastal beaches. Despite the existence of empirical formulations, little is known about the mechanism through which moisture influences this dynamic process. To address this knowledge gap, we present a numerical modelling framework implemented in the open-source software package MercuryDPM [1].
This framework combines a discrete particle model, a one-dimensional airflow model and a liquid migration model. The two-way coupling between the discrete particle model and the airflow model can accurately represent the momentum exchange between these phases, yeilding reasonable sediment transport rates [2]. The inter-particle moisture distribution is modelled by a liquid migration law, which governs the presence of liquid films covering the particle surfaces and liquid bridges spanning the particle contacts [3]. The liquid bridge model introduces a static capillary force as well as a dynamic lubrication force, which is necessary to model the dynamic effects of moisture. This comprehensive model effectively captures particle behaviour under moist conditions and demonstrates the dependence of bed erodibility on particle impact and wind entrainment for varying moisture levels.
Our approach provides valuable insights on the moisture effect in aeolian sediment transport. It advances our understanding of this complex phenomenon, and gives insights on the development of geomorphological patterns at coastal sandy areas. With its flexilibity and versatility, it can be extended to study many more specific processes related to sediment transport.


[1] Weinhart, T., Orefice, L., Post, M., et al (2020). Fast, flexible particle simulations—an introduction to MercuryDPM. Computer physics communications, 249, 107129.
[2] Campmans, G., & Wijnberg, K. (2022). Modelling the vertical grain size sorting process in aeolian sediment transport using the discrete element method. AeolianResearch, 57, 100817.
[3] Mani, R., Kadau, D., Or, D., & Herrmann, H. J. (2012). Fluid depletion in shear bands. Physical review letters, 109 (24), 248001.

How to cite: Wang, X., Campmans, G., Weinhart, T., Thornton, A., Luding, S., and Wijnberg, K.: Exploring moisture-constrained aeolian sediment transport through a discrete particle modelling framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18979, https://doi.org/10.5194/egusphere-egu24-18979, 2024.

EGU24-20740 | ECS | PICO | GM2.2

Multi-Model Comparison of Suspended Sediment Flux in the Sagavanirktok River, Alaska.  

Theodore Langhorst, Konstantinos Andreadis, and Tamlin Pavelsky

Fluvial sediment transport is an important component of the global sediment budget, yet in-situ monitoring is limited. Researchers and practitioners employ various methods to fill in these gaps, each with their own advantages and drawbacks. In this study, we compare four different models for estimating the total annual suspended solids and daily suspended sediment flux for the Sagavanirktok River in Alaska. These four models include: 1) in-situ turbidity calibration; 2) WBMsed global sediment flux estimates 3) optical remote sensing random forest model; and 4) Long-short term memory (LSTM) model trained on remote sensing and modeled inputs. We focus particularly on the summers of 2022 and 2023, when we have continuous validation data via a USGS discharge gage and turbidity sensors that we installed. We evaluate the accuracy, practicality, and shortcomings of each approach to reconstructing the total suspended sediment flux of the Sagavanirktok River. We highlight the necessity of high temporal resolution (approximately daily) for estimating suspended sediment flux in the Sag. River due to the frequency of high discharge events and variable hysteresis between discharge and sediment load. We find that, for the Sag. River, optical imagery alone does not have sufficient temporal resolution to estimate suspended sediment flux (due to orbit repeat and clouds), despite the accuracy of individual estimates. The geomorphic model, WBMsed, is not accurate enough for the unusual hydrology, but does produce daily estimates. Finally, the LSTM model shows promise in being able to bridge the temporal mismatch between satellite, in-situ, and modeled dataset. The LSTM can take advantage of daily discharge models, while incorporating the accuracy of optical satellite sediment models

How to cite: Langhorst, T., Andreadis, K., and Pavelsky, T.: Multi-Model Comparison of Suspended Sediment Flux in the Sagavanirktok River, Alaska. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20740, https://doi.org/10.5194/egusphere-egu24-20740, 2024.

EGU24-433 | ECS | Orals | GM2.3

The morphotectonic evolution of the Albanian Dinarides: new insights from the application of in situ and meteoric Be cosmogenic nuclides 

Chiara Bazzucchi, Silvia Crosetto, Hella Wittmann, Paolo Ballato, Claudio Faccenna, Bardhyl Muceku, and Francesca Rossetti

The Albanian Dinarides represent the central segment of the Dinarides–Hellenides orogenic belt. The Albanian sector is strategically located at the boundary between continental subduction to the north and oceanic subduction to the south, making it an ideal setting to explore the interplay between surface and deep geological processes. Furthermore, modern seismicity (e.g. 1979, Mw 7.1 Montenegro, and 2019, Mw 6.4 Durres earthquakes) and geomorphic features indicate ongoing tectonic activity at least since the late Quaternary. In this study, we explore the landscape response to tectonics and climate by 1) conducting an extensive geomorphic analysis including knickpoint extraction, ksn and chi analysis, longitudinal river profile projection, and mapping of geomorphic features such as windgaps, river terraces, pediment surfaces and uplifted relict landscapes, and 2) estimating basin-wide denudation rates using cosmogenic nuclides.

Specifically, we collected river sediment samples from more than 20 rivers draining all tectonic units and we determined denudation rates using the classic in situ 10Be technique for catchments draining quartz-bearing lithologies, and the new meteoric 10Be/9Be technique in carbonate and ophiolite settings where quartz-poor lithologies predominate. In a few cases, we used both techniques on the same catchments for inter-method comparison. 

The geomorphic analysis highlights the presence of river terraces, non-lithological knickpoints, uplifted relict landscapes and wind gaps suggesting recent tectonic activity at both regional and local scales. This led to a reshaping of the river network with changes in the hydraulic connectivity with the regional sea level that altered the sediment transport directions. Furthermore, Quaternary climatic variations appear to play a crucial role in the erosive power of rivers and in controlling cycles of aggradation and incision.

Denudation rates show spatial variability, ranging from less than 0.3 mm/yr to 0.9 mm/yr in the south, where carbonate and siliciclastic predominate, to over 1 mm/yr in the central part of Albania, where siliciclastic rocks and ophiolites are widely exposed. Although the rates present a good correlation with geomorphic metrics (e.g., ksn and hillslope), the observed variability appears to be influenced by local tectonic processes associated with active normal faults and salt diapirism. Overall, the denudation rates obtained with the two Be techniques are consistent and align with published incision rates derived from river terrace dating, suggesting coupling between fluvial incision and hillslope processes over the last few thousands of years. The consistency between the two cosmogenic Be methods validates the high future potential of the meteoric 10Be technique in quantifying denudation rates in settings dominated by non-quartz lithologies.

How to cite: Bazzucchi, C., Crosetto, S., Wittmann, H., Ballato, P., Faccenna, C., Muceku, B., and Rossetti, F.: The morphotectonic evolution of the Albanian Dinarides: new insights from the application of in situ and meteoric Be cosmogenic nuclides, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-433, https://doi.org/10.5194/egusphere-egu24-433, 2024.

EGU24-545 | ECS | Posters on site | GM2.3

Cosmogenic signal of the stream boulder cover effect  

Emma Lodes and Dirk Scherler

Boulders are ubiquitous in bedrock river channels, moving only when the discharge and slope are large enough to transport them; as a result, large boulders in river channels may retard stream incision by blocking the erodible surface of the channel bed. This cover effect of boulders in stream channels has been demonstrated in models, but we lack field data to test it and understand how it varies with rock type and climate. We collected amalgamated stream boulder samples for in situ 10Be and 14C cosmogenic radionuclide analysis from catchments in humid-temperate, mediterranean, and semi-arid zones in the Chilean Coastal Cordillera. We present preliminary results, including new cosmogenic nuclide data from small (1-5 km2) main catchments in each climate zone and three very small (~0.05 km2) catchments in the semi-arid zone along with grain size analysis (Wolman pebble counts; >100 measurements per locality) for the catchments and adjacent hillslopes, and compare with published 10Be concentrations of stream sediment from van Dongen et al. (2019) and hillslope boulders from Lodes et al. (2023). The humid-temperate catchment has the lowest mean stream boulder 10Be concentrations (normalized to sea level high latitude production rates) at 0.52×105 a g-1, followed by the mediterranean (1.82×105 a g-1) and the semi-arid catchment (4.56×105 a g-1). We obtained a 14C concentration for one boulder sample in the humid-temperate zone so far, at 2.31×105 a g-1. In the main catchments of all three climate zones, stream sediment samples show a negative trend where larger sample grain sizes have lower 10Be concentrations, possibly due to increased erosion of the boulder surfaces or shielding due to overturning. Deposition by landslides can be ruled out in the humid and semi-arid catchments, but not in the mediterranean. In contrast, the three very small catchments in the semi-arid zone show a positive relationship between grain size and 10Be concentrations, suggesting that in these catchments, discharge and slope are too low to frequently overturn or erode the largest grains. In addition, in the semi-arid catchments boulders on hillslopes are larger and have higher 10Be concentrations than boulders in streams, whereas in the mediterranean catchment we observe the opposite pattern, suggesting that in the semi-arid catchments, the largest boulders may stay on the hillslopes until they have weathered to a size small enough to be transported to the stream channels. Next steps include analyzing 14C data for the remaining catchments and further analysis of boulder nuclide concentrations using a modelling approach.

How to cite: Lodes, E. and Scherler, D.: Cosmogenic signal of the stream boulder cover effect , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-545, https://doi.org/10.5194/egusphere-egu24-545, 2024.

EGU24-1456 | ECS | Orals | GM2.3 | Highlight

Landscape response to tectonic deformation and cyclic climate change since ca. 800 ka in the southern Central Andes 

Elizabeth Orr, Taylor Schildgen, Stefanie Tofelde, and Hella Wittmann-Oelze

Theory suggests that the response time of alluvial-channel systems to perturbations in climate can be related to the magnitude and direction of the forcing, and the length of the system; shorter systems may record a higher frequency of forcing compared to longer systems. The Toro Basin in the Eastern Cordillera of NW Argentina has preserved a suite of eight alluvial-fan deposits along the western flanks of the Sierra de Pascha. Farther downstream, a flight of cut-and-fill terraces have been linked to eccentricity-driven (100-kyr) climate cycles since ca. 500 ka. We applied cosmogenic radionuclide (10Be) exposure dating to the fan surfaces to explore (1) how channel responses to external perturbations may or may not propagate downstream, and (2) the differences in landscape response to forcing frequency as a function of channel length when comparing the upper basin alluvial fan deposits with the lower basin terrace sequence. Our new Toro 10Be dataset consisted of 30 boulder samples from the fan surfaces and five pebble samples from a fan depth profile. We identified two generations of fan surface; the first (G1) and second (G2) generations record surface activity and abandonment between ca. 800 and 500 ka, and within the last 100 kyr, respectively. G1 fans record a prolonged phase of net incision, which has been recognised throughout the Central Andes, and was likely triggered by prolonged and enhanced global glacial cycles following the Mid-Pleistocene Transition. Relative fan surface stability followed, while 100-kyr cut-and-fill cycles recorded by the fluvial terraces persisted downstream, suggesting a disconnect in behaviour between the two reaches. G2 fans record higher frequency climate forcing, possibly the result of precessional forcing of climate (ca. 21/40-kyr timescales). The lack of a high-frequency signal farther downstream provides field support for theoretical predictions of a filtering of high-frequency climate forcing with increasing channel length. We show that multiple climate periodicities can be preserved within the sedimentary record of a single basin. Differences in the timing of alluvial fan and fluvial terrace development in the Toro Basin appear to be associated with how channel length affects fluvial response times to climate forcing as well as local controls on net incision, such as tectonic deformation.

How to cite: Orr, E., Schildgen, T., Tofelde, S., and Wittmann-Oelze, H.: Landscape response to tectonic deformation and cyclic climate change since ca. 800 ka in the southern Central Andes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1456, https://doi.org/10.5194/egusphere-egu24-1456, 2024.

EGU24-1804 | Posters on site | GM2.3 | Highlight

Tracking dune blowouts to constrain prehistoric droughts in the Nebraska Sand Hills (Great Plains, USA) 

Sebastian Kreutzer, Christoph Schmidt, Annette Kadereit, and Paul Hanson

Droughts are amongst the most significant natural hazards in the central and southern Great Plains (USA). Chronologies of droughts and related dune activity phases in the Great Plains are paramount for understanding the frequency and magnitude of these potential risks. Beyond historical records, the timing and magnitude of droughts can be revealed only from sediment archives. Our joint DFG/SNF project, CONSTRAIN, aims to provide a new, accurate, and precise temporal placement of prehistoric droughts in the Great Plains, specifically the Nebraska Sand Hills, over the last 1,500 years. We combine methodological research (zircon luminescence dating, luminescence screening) with high-resolution quartz OSL dating to better understand the regional landscape dynamics. Our collaboration is currently in a pilot phase, performing the first methodological tests and identifying suitable archives for dating.

In our first field season, we sampled sand blowouts in the Nebraska Sand Hills identified from LiDAR data. These widespread crater-like depressions (Stubbendieck et al., 1989) are similar to modern blowouts but are grass-covered, suggesting they are likely prehistoric. Still, they remain poorly studied. The blowouts are deflation hollows that seem unrelated to anthropogenic activity or disturbance through wild animals. Instead, they likely formed from drought events that resulted in aeolian deflation on dune crests, but they were either of lower magnitude or shorter-lived than droughts that reactivated the dunes that last moved between 1,000 to 600 years ago (Mason et al., 2004; Miao et al., 2007; McKean et al., 2015).

Our contribution presents field luminescence screening results from 141 samples and the first optically stimulated luminescence (OSL) quartz ages derived from standard measurements testing the hypothesis that the naturally occurring blowouts are related to partial dune reactivation phases between 800 to 200 years ago.

References

Mason, J. A., Swinehart, J. B., Goble, R. J., and Loope, D. B.: Late-Holocene dune activity linked to hydrological drought, Nebraska Sand Hills, USA, The Holocene, 14, 209–217, https://doi.org/10.1191/0959683604hl677rp, 2004.

McKean, R. L. S., Goble, R. J., Mason, J. B., Swinehart, J. B., and Loope, D. B.: Temporal and spatial variability in dune reactivation across the Nebraska Sand Hills, USA, The Holocene, 25, 523–535, https://doi.org/10.1177/0959683614561889, 2015.

Miao, X., Mason, J. A., Swinehart, J. B., Loope, D. B., Hanson, P. R., Goble, R. J., and Liu, X.: A 10,000-year record of dune activity, dust storms, and severe drought in the central Great Plains, Geology, 35, 119–4, https://doi.org/10.1130/g23133a.1, 2007.

Stubbendieck, J., Flessner, T. R., and Weedon, R.: Blowouts in the Nebraska Sandhills: The Habitat of Penstemon haydenii, Proceedings of the North American Prairie Conferences, 223–225, 1989.

How to cite: Kreutzer, S., Schmidt, C., Kadereit, A., and Hanson, P.: Tracking dune blowouts to constrain prehistoric droughts in the Nebraska Sand Hills (Great Plains, USA), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1804, https://doi.org/10.5194/egusphere-egu24-1804, 2024.

EGU24-1850 | Posters on site | GM2.3

Modelling detrital cosmogenic nuclide concentrations during landscape evolution in the LEM CIDRE 

Sebastien Carretier, Vincent Regard, Youssouf Abdelhafiz, Bastien Plazolles, and Shlomy Vainer

The measurement of cosmogenic nuclide (CN) concentrations in riverine sediment has provided breakthroughs in our understanding of landscape evolution. Yet, linking this detrital CN signal and relief evolution is based on hypotheses that are not easy to verify in the field. Models can be used to explore the statistics of CN concentrations in sediment grains. In this work, we present a coupling between the landscape evolution model Cidre and a model of the CN concentration in distinct grains. These grains are exhumed and detached from the bedrock and then transported in the sediment to the catchment outlet with temporary burials and travel according to the erosion-deposition rates calculated spatially in Cidre. The concentrations of various CNs can be tracked in these grains. Because the CN concentrations are calculated in a limited number of grains, they provide an approximation of the whole CN flux. Therefore, this approach is limited by the number of grains that can be handled in a reasonable computing time. Conversely, it becomes possible to record part of the variability in the erosion-deposition processes by tracking the CN concentrations in distinct grains using a Lagrangian approach.  We illustrate the robustness and limitations of this approach by deriving the catchment-average erosion rates from the mean 10Be concentration of grains leaving a synthetic catchment, and comparing them to the erosion rates calculated from sediment flux, for different uplift scenarios. We show that the catchment-average erosion  rates are approximated to within 5% uncertainty in most of the cases with a limited number of grains. This model opens up new possibilities for studying sediment residence times in landscapes, assessing the effect of recycling in calculating paleo-erosion rates, and proposing new methods based on the combination of several isotopes.

How to cite: Carretier, S., Regard, V., Abdelhafiz, Y., Plazolles, B., and Vainer, S.: Modelling detrital cosmogenic nuclide concentrations during landscape evolution in the LEM CIDRE, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1850, https://doi.org/10.5194/egusphere-egu24-1850, 2024.

EGU24-4168 | Orals | GM2.3 | Highlight

Redrawing early human dispersal patterns with cosmogenic nuclides  

John D. Jansen, Mads F. Knudsen, Roman Garba, Jane L. Andersen, Jan-Pieter Buylaert, Jan Kameník, Roger N. Kurbanov, Johannes Lachner, Mariya Lukyanycheva, Martin Margold, Andrew S. Murray, Jesper Nørgaard, Jesper Olsen, Georg Rugel, Konstanze Stübner, Vitaly Usik, and Lotta Ylä-Mella

Burial dating with two cosmogenic nuclides (e.g. 26Al and 10Be) is unveiling the last 5 million years of the sedimentary record. There is no dating method of comparable reliability for the fragmentary records typical of terrestrial settings. For the first time, we can explore events on the same timescale as mountain-building, we can reconstruct landscapes that predate the initiation of the northern hemisphere glaciations, and we can explore milestones in the evolution of our species. Here we focus on illustrating the latter: two field sites in which 10Be-26Al burial dating has reshaped our understanding of early human dispersal in Eurasia. Both are well known Palaeolithic sites hosting Mode-1-type stone tools that despite being intensively studied have not been dated conclusively by other methods.

At Korolevo on the Tysa River in western Ukraine, alluvium containing stone tools is dated to 1.42 ± 0.10 Ma using the burial dating model, P-PINI (Particle-Pathway Inversion of Nuclide Inventories). Korolevo stands as the earliest securely dated hominin presence in Europe and bridges the spatial and temporal gap between the Caucasus (~1.85–1.78 Ma)and southwestern Europe (~1.2–1.1 Ma). Our findings advance the hypothesis of colonisation of Europe from the east well before the Middle Pleistocene Transition.

At Diring Yuriakh on the Lena River in eastern Siberia, stone tools are buried by aeolian sand sheets. We combine optically stimulated luminescence dating with the P-PINI burial dating model to yield an age of 417 ± 82 ka, which is at least 300 kyr earlier than the previously documented earliest human presence north of 60 degrees. This timing overlaps with exceptional warmth across the High North during the ‘super-interglacial’ MIS 11c (426–396 ka), suggesting that warm climate intervals permitted human migration well beyond widely accepted territorial bounds.

Reflecting on these advances, we evaluate the pros and cons of burial dating relative to other widely used dating approaches in archaeology and palaeoanthropology.

How to cite: Jansen, J. D., Knudsen, M. F., Garba, R., Andersen, J. L., Buylaert, J.-P., Kameník, J., Kurbanov, R. N., Lachner, J., Lukyanycheva, M., Margold, M., Murray, A. S., Nørgaard, J., Olsen, J., Rugel, G., Stübner, K., Usik, V., and Ylä-Mella, L.: Redrawing early human dispersal patterns with cosmogenic nuclides , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4168, https://doi.org/10.5194/egusphere-egu24-4168, 2024.

EGU24-4994 | Posters on site | GM2.3

How deep is deep enough: disambiguating the acceptable depth for cosmogenic isochron burial dating 

Yan Ma, Jianzhang Pang, and Dewen Zheng

Cosmogenic 10Be/26Al isochron burial dating is an effective way to accurately determine the depositional time of fluvial sediments that were shallowly buried without requiring any information on post-burial nuclide production and time-dependent burial history. The apparent differences in measured 10Be and 26Al concentrations among a sample assemblage, which derives from the differential erosion in provenance, plays a crucial role in building the isochron. While, when the burial depth is too shallow and/or the amounts of post-burial produced nuclides constitute a main part of total nuclide inventories in samples, the concentration differences among samples would be overwhelmed by the analytical uncertainties of measured 10Be and 26Al concentrations in samples, especially for the old sediments, and it thus leads to a large uncertainty in obtained burial age or destroys totally the isochron. As a result, in the situation of shallow outcrops, a compromise needs to be done between time consumption to dig few meters for sampling and the attainable dating precision. Furthermore, in the cases of shallowly deposited river terraces, especially in the southeastern margin of Tibetan Plateau where the surface erosion is fast and sediments preserved are commonly thin, there is no alternative deeper-buried sediments, and the dilemma between dating but without acceptable uncertainty and not dating has to face. Therefore, the question of how deep is deep enough has to be weighed when sampling. Here, we proposed that the sampling depth of sediments in isochron burial dating should be a flexible standard depending on the isochronicity of the sample assemblage, the predicted burial duration, local geomorphic conditions, and the probably analyzed uncertainties. We try to plot the correlation of predicted age uncertainties with sampling depth, burial ages, as well as the geomorphic parameters, to disambiguate the acceptable depth in the isochron dating for the required dating precision. 

How to cite: Ma, Y., Pang, J., and Zheng, D.: How deep is deep enough: disambiguating the acceptable depth for cosmogenic isochron burial dating, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4994, https://doi.org/10.5194/egusphere-egu24-4994, 2024.

EGU24-6385 | ECS | Posters on site | GM2.3 | Highlight

Relationships between temperature, elevation, and surface exposure age in the McMurdo Dry Valleys, Antarctica 

Taylor Bourikas, Marissa Tremblay, Jennifer Lamp, Greg Balco, and Darryl Granger

The McMurdo Dry Valleys are an ice-free region along the coast of the Transantarctic Mountains that display well-preserved polar desert morphologic features, particularly at high elevations. The extent of these well-preserved features suggests that cold-desert conditions have been present for millions of years. This is thought to be because average summer air temperatures in much of the McMurdo Dry Valleys remain below -3ºC, preventing significant amounts of liquid water from forming and in turn keeping erosion rates low. Recent climate simulations suggest that these freezing temperatures persist during summer months at high elevations in the McMurdo Dry Valleys, even during past warm periods characterized by significant ice sheet recession. Surfaces at lower elevations in the McMurdo Dry Valleys, subject to warmer temperatures during warm periods and interglacials, are thought to experience overall faster erosion rates compared to high elevation outcrops.

 

Here, we examine the relationships between elevation, temperature, and apparent surface exposure age for outcrops of the Beacon Sandstone in the McMurdo Dry Valleys. We use a compilation of cosmogenic nuclide measurements available in the ICE-D database to evaluate the correlation between apparent surface exposure age and elevation for outcrops of the Beacon Sandstone across the McMurdo Dry Valleys. At or near a number of the cosmogenic nuclide sites, local summertime ground and air surface temperature data are available from weather stations. We use these weather station data to document how ground temperatures, which ultimately control the availability of liquid water and therefore rates of surface processes, correspond with the apparent exposure ages and site elevations of Beacon Sandstone outcrops. In addition, we investigate whether field observations indicating a relationship between the coloration and surface appearance of Beacon Sandstone outcrops and the surface weathering/erosion rate can be quantified using satellite remote sensing data and the spectral properties of the outcrops. Tying all of these results together, we assess the role of temperature and other physical parameters on the rates of surface processes in the McMurdo Dry Valleys during the last few million ice-free years.

How to cite: Bourikas, T., Tremblay, M., Lamp, J., Balco, G., and Granger, D.: Relationships between temperature, elevation, and surface exposure age in the McMurdo Dry Valleys, Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6385, https://doi.org/10.5194/egusphere-egu24-6385, 2024.

EGU24-7506 | ECS | Posters on site | GM2.3

Combined application of single grain and cobble luminescence dating to Alpine glaciofluvial deposits 

Elena Serra, Daniela Mueller, Lukas Gegg, and Frank Preusser

Dating glaciofluvial deposits is fundamental to reconstruct paleoglacial and paleoclimatic dynamics. However, partial bleaching and lack of suitable sediments make the application of luminescence dating to such deposits challenging. Single grain and cobble luminescence dating have been successfully used to tackle these problematics [e.g. 1, 2] and are combined in this study on glaciofluvial deposits from the northern Alpine foreland (Finsterhennen, Switzerland).

Previous chronological investigations at the study site [3, 4, 5] suggest that the deposition of the glaciofluvial gravel lying directly underneath the till from the regional Last Glacial Maximum (LGM) occurred ca. 29 kyr ago, in response to the LGM glacial advance. By comparison with the existing age constraints, the present study aims (1) to test the combined application of single grain and cobble luminescence dating to Alpine glaciofluvial deposits and (2) to refine the two methodologies.

Samples were collected from well sorted sand lenses and moderately sorted gravel at approximately the same depth within the pre-LGM glaciofluvial gravel. Single grain (SG) feldspar luminescence measurements were conducted on sand lens and gravel sandy matrix samples, while luminescence depth profiles were measured in individual crystalline cobbles. Preliminary results show good agreement between SG ages from the sand lens and previous chronological constraints. SG results from the sandy matrix of the gravel horizon are instead underestimated, potentially because of challenges in dosimetry estimation, due to the heterogeneous lithology and grain size of the gravel layer. Heterogeneous dosimetry appears less problematic for burial age estimation of cobbles, since the variation of dose rate with depth into the cobble is dominated by the dosimetry of the cobble itself. Preliminary cobble luminescence depth profiles show shallow bleaching fronts, with large variability between cores and surfaces of the same cobble. The limited luminescence signal resetting can be explained by the proximity of the glaciofluvial deposits to the advancing LGM ice front and by sediment transportation in turbid water. The intra cobble variability is instead potentially related to the cobbles’ heterogeneous lithology, implying differences in dosimetry and light attenuation within the clasts.

References

[1] Duller, 2006, Quaternary Geochronology 1.

[2] Jenkins et al., 2018, Quaternary Science Review 192.

[3] Schlüchter, 2004, Quaternary Sciences 2.

[4] Preusser et al., 2007, Boreas 36.

[5] Pfander et al., 2022, Swiss Journal of Geosciences 115.

How to cite: Serra, E., Mueller, D., Gegg, L., and Preusser, F.: Combined application of single grain and cobble luminescence dating to Alpine glaciofluvial deposits, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7506, https://doi.org/10.5194/egusphere-egu24-7506, 2024.

EGU24-7571 | ECS | Posters on site | GM2.3

Controls on flank erosion rates during valley widening: an application of cosmogenic nuclides in Andean and French valleys 

Chloé Valenti, Sébastien Carretier, Vincent Regard, Sandrine Choy, Vincent Godard, Frédéric Christophoul, Willem Viveen, Valeria Zavala, and Aster Team

Any keen observer has noticed that valleys show a large variability in their shapes: mountain rivers flow in valleys ranging from dramatic narrow gorges to valley floors that are several times river width. This geometry implies that the river has not only carved vertically but has also laterally eroded the valley flanks, depending on the action of lateral and vertical erosion on the flanks and valley floor respectively. Valley widening occurs when a river channel comes into contact with the valley edges and erode them, therefore, it depends on processes acting at the scale of a river bank but also at the scale of the river.

However, valley widening processes and rate are still poorly documented while valley evolution has a key role in landscape evolution. Lateral erosion during catastrophic floods can drive valley flank erosion. Valleys are also wetlands with a voluminous aquifer and where ecosystems evolve as valleys widen or narrow over millennia. Moreover, the storage of carbon increases in wide valleys which, therefore, play a role in the carbon cycle and in the evolution of the global climate. Valley width strongly affects sediment residence times on continents, with large valleys potentially buffering sediment fluxes exported to the oceans. Finally, valleys widening is responsible for the formation of abrasion terraces and contribute to the development of pediments. The dynamics of valley widening is therefore a fundamental component of the evolution of relief and sediment flux.

Given these challenges, it is becoming necessary to better understand valley widening rate and its controls. We have used and further developed the approach presented and tested in northern Chile by Zavala et al. (2021 doi:e2020GL0899).  For that, we focused on 13 river valleys (in the Arequipa Province, Peru, in the Atacama Desert in Chile and in the plateau of Valensole, France) where geomorphic, geological and climatological parameters offer a wide range of conditions to compare with erosion rates. In total, we analysed 79 samples of sands from valley flanks to measure the millennial erosion rates, by using in-situ produced Beryllium-10 (10-Be) and Aluminium-26 (26-Al). We used the detrital mean 10-Be concentration to calculate a mean local valley flank erosion rate, in a similar way that cosmogenic nuclide concentrations have been used to quantify catchment wide denudation rates.

We also extracted factors that may control widening rate (valley width, slope of flanks and valley floors, incision and drainage area) for comparison with 10-Be and 26-Al concentrations. Our preliminary results in 31 samples show comparable 10-Be concentrations along a single stretch of valley, except for several outliers, for different valleys in the Andes and France, indicating some robustness in the sampling method. These results are promising and should provide new constraints on factors that control the widening rate of valleys. 

How to cite: Valenti, C., Carretier, S., Regard, V., Choy, S., Godard, V., Christophoul, F., Viveen, W., Zavala, V., and Team, A.: Controls on flank erosion rates during valley widening: an application of cosmogenic nuclides in Andean and French valleys, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7571, https://doi.org/10.5194/egusphere-egu24-7571, 2024.

EGU24-7686 | ECS | Posters on site | GM2.3

Combining meteoric and in situ 10Be for depositional flux estimations along a climate gradient 

Laura Krone, Hella Wittmann, and Friedhelm von Blanckenburg

Along an extreme climate gradient from arid to humid in the Chilean Coastal Cordillera, we investigated soil profiles using the meteoric cosmogenic radionuclide 10Be and its ratio to stable 9Be. The isotope ratio 10Be(meteoric)/9Be combines an atmospheric flux tracer to Earth’s surface with stable 9Be that is released by weathering. In contrast to the well-established in situ 10Be method, the meteoric variety of 10Be is not limited to quartz-bearing lithologies and requires less sample material. However, to calculate denudation rates from 10Be(meteoric)/9Be knowing the depositional flux to Earth’s surface, F10Bemet, is an essential prerequisite.

We applied the in situ 10Be technique for denudation rate estimations on soil profiles (Dinsitu) and compared the results with 10Be(meteoric)/9Be-derived denudation rates (Dmet). Our results show that Dmet in conjunction with F10Bemet derived from a general circulation (GCM) model (ECHAM5-HAM; Heikkilä, 2007) are consistent with Dinsitu at the mediterranean (10Beinsitu: 126 ± 32 t km-2 yr-1, 10Be(meteoric)/9Be: 170 ± 40 t km-2 yr-1) and humid (10Beinsitu: 38 ± 10 t km-2 yr-1, 10Be(meteoric)/9Be: 31 ± 8 t km-2 yr-1) study sites, both with mean annual precipitation (MAP) > 400 mm (mediterranean: 440 mm yr-1, humid: 1080 mm yr-1). However, at the arid (MAP: 10 mm yr-1) and semi-arid (MAP: 90 mm yr-1) study sites, when using a GCM-based F10Bemet, Dmet exceed Dinsitu by a factor of up to 170. The cause for this offset may lie in an overestimation of F10Bemet at low precipitation. Indeed, when using Dinsitu as benchmark and solving for F10Bemet instead, a much lower flux results.

These results suggest a lower precipitation limit (~400 mm yr-1) for the use of GCM-derived F10Bemet especially in dry regions. In such arid and semi-arid regions with high spatial climate variability the depositional flux derived from coarse-resolution GCM-models overestimates the input of meteoric 10Be to Earth’s surface either by wet or dry deposition. In settings with sufficient precipitation above this limit the GCM-derived flux is suited to determine denudation rates using 10Be(meteoric)/9Be.

Heikkilä, U., 2007, Modeling of the atmospheric transport of the cosmogenic radionuclides 10Be and 7Be using the ECHAM5-HAM general circulation model: ETH Zurich, doi:10.3929/ETHZ-A-005560259.

How to cite: Krone, L., Wittmann, H., and von Blanckenburg, F.: Combining meteoric and in situ 10Be for depositional flux estimations along a climate gradient, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7686, https://doi.org/10.5194/egusphere-egu24-7686, 2024.

EGU24-9499 | ECS | Orals | GM2.3

What can DEMs tell us about the ages of fluvial terraces? 

Lennart Grimm, Fergus McNab, Victoria M. Fernandes, and Taylor Schildgen

Changes in climate coupled with long-term uplift cause alluvial rivers to aggrade or incise, resulting in the formation of fluvial terrace sequences. Such terrace records provide an opportunity to investigate past interactions between climatic forcings, tectonics, and fluvial systems. Further, they allow us to infer potential channel responses to future climatic change. To accurately decipher such interactions, precise age constraints on fluvial terraces are vital. However, established dating methods such as cosmogenic exposure dating are costly, time intensive, and require direct access to terrace surfaces. Thus, their application is not always possible.

An alternative approach to dating fluvial terraces is based on the temporal evolution of the step (riser) between successive terraces. Downslope sediment transport and elevation change, commonly modelled by hillslope diffusion equations, cause a decrease in gradient with time. If the profile of a riser is obtained in high resolution via GPS or LiDAR elevation measurements, its shape can be related back to the terrace age using inverse modelling schemes.

Here, we apply this theory to a set of fluvial terraces situated along the Río Santa Cruz and Río Shehuen in Patagonia, Argentina. A set of existing 10Be terrace exposure ages of up to ca. 1 Ma from both rivers is used for age verification and model calibration. GPS elevation transects of terrace risers measured during a field campaign in 2023 are used to establish an age chronology with negligible elevation uncertainties. To explore the feasibility of this method without access to field-quality elevation data, we also test the viability of using riser profiles derived from ca. 12 m resolution TanDEM-X data for dating. Preliminary results from synthetic riser profiles with elevation uncertainties similar to those of TanDEM-X data indicate that such DEM-derived age estimates are theoretically accurate. However, application to the Patagonian river systems and comparison against independent 10Be ages shows a wide spread in absolute age estimates for single terrace generations. Therefore, in this case, the method appears to be viable only for relative age classification. Post-abandonment riser disturbances and spatially variable sediment transport rates may be key factors hindering our ability to integrate large numbers of DEM-derived profiles into a unified interpretation. Obtaining more robust absolute age estimates may require the use of landscape evolution models that incorporate more complex, non-diffusive processes. Further, the viability of this method may be reduced for very old (i.e., ca. 1 Ma) terraces. Application to younger terrace systems may yield more accurate results.

This technique provides a low-cost, spatially extendable way of dating fluvial terraces and analysing landscape dynamics in fluvial systems. We are currently preparing to release an open-source Python library containing the tools needed to perform these analyses.

How to cite: Grimm, L., McNab, F., Fernandes, V. M., and Schildgen, T.: What can DEMs tell us about the ages of fluvial terraces?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9499, https://doi.org/10.5194/egusphere-egu24-9499, 2024.

EGU24-9605 | ECS | Orals | GM2.3

Early development of Argon-39 as a new geochronometer for geologic processes on short time scales 

Franka Neumann, Yannis Arck, W. Payton Gardner, Joerg Schaefer, Modou L. Singhateh, Markus Oberthaler, and Werner Aeschbach

Up until now, the cosmogenic radioisotope 39Ar has not been used for surface exposure or burial dating of minerals due to its low concentration in rocks and the large sample size requirements for its detection by low-level counting. The novel analytical method Atom Trap Trace Analysis (ATTA) – already well established for gas samples from groundwater, ocean water or ice cores – can measure the isotopic ratio of 39Ar to stable Ar in the range of 10-16 on just a few ml STP of argon and therefore opens up new possibilities for applying 39Ar.

This talk will report on the initial steps taken towards using 39Ar as a geochronometer. Calculations of production rates of 39Ar in typical continental rocks, exposed to cosmic radiation at the Earth surface, show that sample sizes of the order of 100 g of rock should yield a sufficient number of 39Ar atoms (order 103 to 104) for detection by ATTA. However, the amount of 40Ar in such samples – and therefore the total extractable Ar amount - is much lower than what is typically extracted from ice and water samples, which contain atmosphere-derived Ar. The 40Ar content in rock stems from 40K-decay and depends on the rock formation age and the potassium content. Dilution with 39Ar-free Ar results in sufficient total argon volumes for the standard ATTA analysis.

Gas extractions from heated rock samples indeed show 39Ar isotope abundances 2-3 orders of magnitude above the atmospheric ratio, well within the measurement range of ATTA after dilution. In order to check the feasibility of exposure dating of rocks, several samples were taken for comparison from boulders of glacier moraines, previously dated with 10Be, in the Jamtal valley in Austria. Additionally, 10Be-dated samples from other moraine sites are to be analysed for 39Ar for further validation of 39Ar as a tool for exposure dating. As of now it remains to be seen whether reliable agreement between the dating methods can be achieved. Due to its relatively short half-life of 268 years, 39Ar would be a useful addition in multi-tracer studies on geologic processes within the last two millennia.  

How to cite: Neumann, F., Arck, Y., Gardner, W. P., Schaefer, J., Singhateh, M. L., Oberthaler, M., and Aeschbach, W.: Early development of Argon-39 as a new geochronometer for geologic processes on short time scales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9605, https://doi.org/10.5194/egusphere-egu24-9605, 2024.

EGU24-10522 | ECS | Posters on site | GM2.3

Long-term denudation and topographic relief evolution of Central and Northern Madagascar 

Romano Clementucci, Sean Willett, Yanyan Wang, Wu Datian, Negar Haghipour, Hervé Randriamananjara, and Nirina Tedy Ranaivoson

The landscape of Central and Northern Madagascar is characterized by residual landforms, steep slopes, and low-relief areas, resulting mainly from the processes of dissection of the central high plateau and retreat of two main topographic scarps on the western and eastern margins of the island. On the western side, the topography is characterized by relict relief and a highly sinuous plateau edge. Conversely, the landscape on the eastern side is dominated by the great topographic escarpment with a linear plateau edge. Locally, this general morphology is perturbed by the formation of the active Alaotra-Ankay rift system, which displaces the plateau-escarpment system. Here, we explore the long-term relief evolution of these three morpho-structural domains (west and east sides and rift sector) by combining denudation rates derived from cosmogenic nuclides and geomorphic stream profile analysis. Our results show that, although the erosional dynamics are dominated by the same processes of plateau dissection and scarp retreat, the topographic features, drainage networks, and distributions of species richness differ within these three domains. We provide insight into the processes that lead to transient landscape and relief evolution of rifted margins.

How to cite: Clementucci, R., Willett, S., Wang, Y., Datian, W., Haghipour, N., Randriamananjara, H., and Ranaivoson, N. T.: Long-term denudation and topographic relief evolution of Central and Northern Madagascar, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10522, https://doi.org/10.5194/egusphere-egu24-10522, 2024.

EGU24-10959 | ECS | Orals | GM2.3

Variation of authigenic 10Be/9Be in spatial and temporal scale and its implications for applicability of dating method for river dominated deltas 

Kishan Aherwar, Michal Šujan, Régis Braucher, Andrej Chyba, Arjan De Leeuw, Anton Matoshko, Alessandro Amorosi, Bruno Campo, Barbara Rózsová, Bronislava Lalinská-Voleková, and Aster Team

The authigenic 10Be/9Be dating method has emerged as a novel chronometer in the last few decades. Initially introduced by Bourles et al. (1989: Geochim. Cosmochim. Acta) for dating of oceanic sediments the method has been successfully applied to date continental sediments in some recent studies. The method utilizes decay of cosmogenic radionuclide 10Be to date the deposition of sediment in the range of 0.2 to ~14 Ma. Different source of the two isotopes 9Be and 10Be results in changes in the authigenic 10Be/9Be ratio (R) as the sediment gets transported from deltaic to offshore settings through shelfal environment. Accurate determination of initial 10Be/9Be ratio (R0) is of paramount importance in this dating method to calculate the correct age of the deposited sediment. It is therefore necessary to quantify the variability of authigenic initial ratio for the effective application of the method.

This study aims to describe the variability of authigenic 10Be/9Be ratio in temporal as well as spatial scale. We analyzed the samples for authigenic 10Be/9Be ratio from two different study sites, the Late Miocene to Quaternary Slanicul de Buzau section in Romania and the Holocene Po River delta plain in Italy. 109 samples were sampled from Slanicul de Buzau section with a sampling step resolution of ~20–30 ka aiming to interpret ratio variability in temporal scale. Po coastal plain yielded 50 samples from 4 different parasequnces (5,6,7 and 8) (Amorosi et al., 2017: Mar. Pet. Geol.) to cover the variability in spatial scale. The analysis of samples from these study sites allowed us to understand the variability of the ratio in terms of sediment source proximity and change in sediment provenance.

Back calculation of initial ratio R0 in 109 samples from Slanicul de Buzau section with the help of measured authigenic R and interpolated magnetostratigraphic age of samples reveals low variability in R0 in deltaic and shallow water sediments, while the offshore facies exhibit significantly higher variability.

Results from measured ratio R in 50 samples of Po Plain does not show a drastic variability, slightly higher R in the samples from parasequence 6 can be attributed to the different provenance of this parasequence in contrast to the sediment source of the latter parasequences (Amorosi et al., 2020: Basin res.).

This observed low variability of authigenic 10Be/9Be reveals the good suitability of the dating method for river dominated deltas. We have also attempted to propose a minimum number of sample count necessary to be analyzed when using this dating method. The approach aims to estimate the sample size dependency of the ratio by running 1000 simulations and bootstrapping to estimate the 95% CI for variability of ratio, taking into consideration the three statistics namely, range, IQR, and SD. Bootstrapping performed in our data, in a particular group of n samples (e.g., samples from a specific facies type), suggests that at least nearly half the sample size of n is necessary to represent the initial ratio variability and to avoid the potential bias caused by the initial ratio variability.

How to cite: Aherwar, K., Šujan, M., Braucher, R., Chyba, A., De Leeuw, A., Matoshko, A., Amorosi, A., Campo, B., Rózsová, B., Lalinská-Voleková, B., and Team, A.: Variation of authigenic 10Be/9Be in spatial and temporal scale and its implications for applicability of dating method for river dominated deltas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10959, https://doi.org/10.5194/egusphere-egu24-10959, 2024.

Multiple elevated temperature infra-red stimulated luminescence (MET-IRSL) has great potential to provide detailed information on the movement of sediment grains through time and space. MET-IRSL stimulates grains using infra-red light at a series of elevated temperatures to access multiple charge populations with different bleaching behaviours. Length of past light exposure and duration of storage events can be determined by the relative difference between multiple signals, or ages, for a single grain. With more signals, we can see deeper into the history of an individual grain.

Single-grain measurements paint a fine-resolution picture of how a system operates, often masked by multiple grain average measurements. The power of single-grain measurement is underpinned by three basic principles: 1) A single grain has a single transport-storage history (Rhodes and Leathard, 2022), 2) Populations of >200 grains per sample allows for quantitative estimation of the most likely, or ‘dominant’ history for a given sample, 3) It is possible to isolate different grain populations, with different histories or provenance within a single sample.

Using samples collected from the active channel of the Allt Dubhaig in Scotland, we present results from a bleach recovery experiment to illustrate an optimal method for quantifying most likely length of past light exposure using single grains, and a gaussian mixture model approach to isolating different grain populations within a single sample. Combined with a numerical model of single-grain bleaching and burial, we apply these approaches to elucidate past and present fluvial sediment transport information for the Allt Dubhaig, Scotland, and the Santa Clara River, southern California.

How to cite: Spano, T., Rhodes, E., and Hodge, R.: Using single-grain multiple elevated temperature luminescence to understand fluvial sediment transport at the system scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11032, https://doi.org/10.5194/egusphere-egu24-11032, 2024.

EGU24-11084 | Orals | GM2.3

Denudation and weathering rates from meteoric 10Be/9Be: A versatile tool in mafic, carbonate or slate-dominated lithologies from the critical zone to very large catchments  

Hella Wittmann, Julien Bouchez, Kai Deng, Nestor Gaviria-Lugo, Anne Bernhardt, and Friedhelm von Blanckenburg

Meteoric 10Be is a cosmogenic nuclide produced in the atmosphere and delivered to Earth’s surface by precipitation, whereas stable 9Be is a trace metal released from bedrock during weathering. The ratio (10Be(meteoric)/9Be) is set in the critical zone, where beryllium is either adsorbed to fine-grained sediment or is dissolved in water if the pH-dependent retentivity of Be is low. A prerequisite for calculating denudation and weathering rates over millennial timescales is knowledge of the flux of 10Be deposition to Earth surface and the concentration of 9Be in the unweathered parent bedrock. We provide a review of applications of the 10Be/9Be system to Earth surface studies that covers a variety of quartz-bearing rocks, lithologies largely void of quartz like mafic rocks, mixed lithologies, and, most recently, carbonate and marble lithologies.

We show the versatility of this new approach in several case studies. These range from small creek-scale mafic basins in the European midlands, medium-sized (102-103 km2) catchments covered by slate and marble in the rapidly eroding Taiwan Island, pure carbonate rocks from the French Jura Mountains, to large catchments draining mixed lithologies in the Chilean Andean Cordillera and the Amazon and Ganga river basins. We find that i) across all spatial scales, the dissolved and sediment-bound 10Be/9Be ratios agree well, indicating equilibrium of phases. Approximately at medium-sized catchment scales, ii) the 9Be concentration from published databases from typical parent rocks (http://earthref.org/GERM) represents the local bedrock 9Be concentration, but for much smaller and carbonate catchments, a locally representative bedrock concentration has to be determined on a case-by-case basis; and iii) local measurements of the depositional 10Be flux from the 10Be inventory of independently-dated deposits like e.g. terrace profiles appear to yield the most reliable estimates. Under these constraints, derived denudation and weathering rates agree in all settings to within less than a factor of 2 with either decadal-scale denudation rates from combined suspended and dissolved river fluxes or with in situ-10Be-derived denudation rates where quartz is present. This close agreement shows that 10Be/9Be ratios from such rock types yield meaningful denudation rates obtained from sub gram-sized amounts of sediment, independent of the spatial scale of sampling ranging from a single soil profile to the scale of the Amazon river basin. Small sample amounts and the independence of the presence of quartz provide a benefit over the “sister” nuclide in situ 10Be that has been widely used in landscapes of felsic rocks. Now, with 10Be/9Be, the determination of rates of Earth surface change in quartz-poor lithologies opens up entirely new opportunities.

How to cite: Wittmann, H., Bouchez, J., Deng, K., Gaviria-Lugo, N., Bernhardt, A., and von Blanckenburg, F.: Denudation and weathering rates from meteoric 10Be/9Be: A versatile tool in mafic, carbonate or slate-dominated lithologies from the critical zone to very large catchments , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11084, https://doi.org/10.5194/egusphere-egu24-11084, 2024.

EGU24-11574 | ECS | Orals | GM2.3

Unveiling the early Eurasian glaciations with new advances of 10Be-26Al burial dating 

Lotta Ylä-Mella, Kaleb Wagner, Martin Margold, Mads Faurschou Knudsen, Freek Busschers, Marcel Bakker, Lucyna Wachecka-Kotkowska, Dariusz Krzyszkowski, Dariusz Wieczorek, Izabela Szuman-Kalita, Birte Lindahl Eriksen, Jane Lund Andersen, Jesper Olsen, Zoran Perić, Helena Alexanderson, and John D. Jansen

Cosmogenic nuclide burial dating exploits the differential decay rate of a nuclide pair, typically 26Al and 10Be. There are three basic approaches; simple burial dating, the isochron method and P-PINI (Particle Pathway Inversion of Nuclide Inventories). The simple burial age is based on deviation from the surface production ratio assuming quick and deep burial. The isochron method incorporates multiple samples from a single stratigraphic layer and assumes steady erosion in the sediment source area. P-PINI accommodates more complicated situations, such as landscapes undergoing non-steady erosion and an eroding or accumulating sink zone. This source-to-sink model uses a Monte Carlo simulator to create a library of plausible erosional and depositional histories and then compares those histories against measured nuclide data to derive a burial age estimate. In cases involving multiple dated layers in a section or when an independent age estimate is available, a Bayesian tool further constrains the burial age.

With the aim of constraining the timing of the Eurasian Ice Sheet at its largest known extent, we applied P-PINI at Wapenveld in the Netherlands and at Szczerców in central Poland. From a drill-core at Wapenveld we collected three sand samples from the Early Pleistocene ‘Hattem’ beds, and derived the P-PINI burial age bracketed by simple burial ages calculated from the units above and below. Szczerców is an open-cast mine exposing multiple Middle Pleistocene till units rich in cobble-sized clasts. Here, P-PINI burial ages show sensitivity to the thickness of the dated layer, a problem we resolve by including feldspar infrared-simulated luminescence dates higher up the sequence.

We discuss the pros and cons of our approach at Wapenveld and Szczerców. Burial dating multiple units in section requires considerably more lab effort but also offers important advantages that can be boosted by carefully considering which grain-size to sample, and by incorporating independent age constraints.

How to cite: Ylä-Mella, L., Wagner, K., Margold, M., Knudsen, M. F., Busschers, F., Bakker, M., Wachecka-Kotkowska, L., Krzyszkowski, D., Wieczorek, D., Szuman-Kalita, I., Eriksen, B. L., Andersen, J. L., Olsen, J., Perić, Z., Alexanderson, H., and Jansen, J. D.: Unveiling the early Eurasian glaciations with new advances of 10Be-26Al burial dating, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11574, https://doi.org/10.5194/egusphere-egu24-11574, 2024.

EGU24-12081 | ECS | Posters on site | GM2.3

Constraining erosion rates and patterns for glaciated basins in the European Alps using thermoluminescence thermochronology  

William J. Wenban, Nathan D. Brown, Edward J. Rhodes, and Darrel A. Swift

Rates and patterns of erosion by glaciers and their contribution to the evolution of tectonically active mountain topographies remain poorly understood. Insights from apatite fission track and (U-Th)/He thermochronometry have been restricted by minimum detectable cooling ages measured in millions of years that are relevant to the exhumation of bedrock from depths of upwards of c. 2 km, whilst cosmogenic nuclide concentration methods reveal the timing of removal of only the uppermost 2 m of bedrock, which is relatively superficial in glacial erosion terms. We have therefore applied the relatively new technique of K-feldspar thermoluminescence thermochronometry (Brown & Rhodes, 2022) that is capable of resolving near-surface cooling histories of bedrock over timescales spanning the most recent glacial-interglacial cycle. This very low-temperature thermochronometer permits analysis of exhumation from depths of several hundred metres upwards and is therefore sensitive to the erosion processes of specific components of the glacier system as well as the dynamism and significance of major erosional landforms. Results are presented from two currently glaciated valleys in the central European Alps that possess contrasting features and longitudinal valley profiles, and these suggest the ability to better understand glacial process contributions to mountain geomorphic development and to improve glacial erosion laws commonly used in numerical landscape evolution models. 

How to cite: Wenban, W. J., Brown, N. D., Rhodes, E. J., and Swift, D. A.: Constraining erosion rates and patterns for glaciated basins in the European Alps using thermoluminescence thermochronology , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12081, https://doi.org/10.5194/egusphere-egu24-12081, 2024.

EGU24-12491 | Orals | GM2.3

Sediment Dating of Fluvial, Lacustrine and Aeolian Systems in the Basin of the great Lakes, Western Mongolia 

Manfred Frechen, Neda Rahimzadeh, Dennis Wolf, and Frank Lehmkuhl

Luminescence and radiocarbon dating methods are mandatory to set up reliable chronological frameworks for sedimentary systems to reconstruct climate and environmental changes quantitatively through time. Our study area, the Basin of the Great Lakes in Western Mongolia is a key area to investigate sediment archives and sediment pathways under variable climates in this region including extreme continental climatic conditions.  Alluvial fans, beach bars and dune fields, partly interacting with each other, were sampled for luminescence dating in detail. In this study, a total of thirty-four samples were taken from a beach ridge sequence of Khyargas Nuur and tested using K-feldspar single aliquot (2.5 mm) pIRIR dating to overcome the problem of the dim signal of quartz. Furthermore, single grain dating was also conducted to address the problem of insufficient bleaching of the pIRIR signals. The preliminary established chronological framework indicates that the studied samples were mostly deposited during the Holocene and the results yielded a continuous decline of the lake level for most of the Holocene period.

 

How to cite: Frechen, M., Rahimzadeh, N., Wolf, D., and Lehmkuhl, F.: Sediment Dating of Fluvial, Lacustrine and Aeolian Systems in the Basin of the great Lakes, Western Mongolia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12491, https://doi.org/10.5194/egusphere-egu24-12491, 2024.

EGU24-13590 | ECS | Orals | GM2.3

Advances in Cosmogenic Nuclides measured in Ferrar Pyroxene 

Marie Bergelin and Greg Balco

Measurement of multiple cosmogenic nuclides in single samples is valuable for various applications. For exposure dating, multiple-nuclide systematics are important for correcting exposure ages for surface weathering and erosion, as well as quantifying when and how often a surface has experienced burial. Currently, such constraints from paired 26Al/10Be/21Ne measurements in quartz are common practice and well established. However, 36Cl/10Be/3He nuclide measurements in pyroxene would provide more precise constraints because the range in decay constants is greater. In Antarctica, the pyroxene-bearing Ferrar Dolerite is one of the dominant lithologies of clast exposed at the surface of many surficial deposits throughout the Transantarctic Mountains. While cosmogenic 3He measurements in Ferrar pyroxene are routine, 10Be and 36Cl measurements are less common and not well established. Here we present recent advances in multiple cosmogenic nuclides measured in the Ferrar pyroxene, which includes (i) improvements in the extraction of 10Be and 3He from pyroxene grains, (i) production rate estimates of 10Be in pyroxene and 36Cl from Ca spallation, and (iii) understanding and quantifying the non-cosmogenic inventories of 3He and 36Cl in pyroxene for accurate exposure dating.

How to cite: Bergelin, M. and Balco, G.: Advances in Cosmogenic Nuclides measured in Ferrar Pyroxene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13590, https://doi.org/10.5194/egusphere-egu24-13590, 2024.

EGU24-14778 | Posters on site | GM2.3

Refining exposure-age estimates of 40- to 800-ka surfaces with 10Be, 21Ne, and additional geologic constraints 

Taylor Schildgen, Elizabeth Orr, and Samuel Niedermann

Dating alluvial-fan or river-terrace surfaces that are more than several tens of kyr old is challenging in many environments. Depth profiles of samples can be difficult to extract in the field, time consuming to process in the lab, and expensive to analyze. Even under idealized sampling conditions, the difficulty of constraining possible surface erosion or inflation can lead to large uncertainties in the surface exposure age. Alternatively, sampling individual boulder surfaces or cobbles may be logistically simpler, but large scatter in ages can be difficult to explain, given the possibility that the boulders/cobbles have rotated from their original position, surfaces experienced erosion, or the clasts may have some inherited concentration of cosmogenic nuclides. All of these problems are exacerbated in surfaces that have been exposed for hundreds of kyr.

In the Toro Basin of NW Argentina, a set of alluvial-fan surfaces has recently been interpreted to comprise two generations, one likely spanning from ca. 500 to 800 ka, and another less than 100 ka, based on 10Be exposure ages of individual boulder surfaces and one depth profile. Here, we report 21Ne data from a subset of the boulder surfaces with the aim of better constraining the ages.

Despite the apparently simple geomorphic setting of the fans, dual-nuclide (“banana”) plots of 21Ne and 10Be data reveal that most of the boulders have a complex burial history, with inferred burial times up to ca. 750 kyr. This finding implies that the boulders were not simply transported from nearby bedrock hillslopes and exposed on the fan surfaces. Instead, the boulders must represent exhumed rocks from an earlier generation of basin filling, which is constrained to between 4.5 and 0.85 Ma in the vicinity of the fans from U-Pb zircon dating of intercalated ashes (Pingel et al., 2020). We use a Monte Carlo approach to explore what possible range of initial exposure times, burial times, and final exposure times are consistent with the 10Be and 21Ne data on any given surface. For several surfaces, parameters trade off such that a wide range of exposure ages is possible. However, if we also take into account the stratigraphic relationships among the surfaces (higher surfaces must be older), and we consider that boulders exposed in the highest surface must have burial times that are shorter than boulders exhumed from lower elevations, relatively tight constraints on exposure ages, inherited nuclide concentrations, and boulder-surface erosion rates are possible on some of the surfaces.

How to cite: Schildgen, T., Orr, E., and Niedermann, S.: Refining exposure-age estimates of 40- to 800-ka surfaces with 10Be, 21Ne, and additional geologic constraints, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14778, https://doi.org/10.5194/egusphere-egu24-14778, 2024.

EGU24-15601 | ECS | Orals | GM2.3

Hillslopes in action? Combining in situ 14C- and 10Be-derived insights into the spatio-temporal variability of soil dynamics on Swiss alpine hillslopes 

Stephan Heinz Wartenweiler, Maarten Lupker, Negar Haghipour, Marcus Christl, and Timothy Ian Eglinton

Rapidly eroding mountain ranges act as major sources for the export of clastic sediments, solutes and organic matter from the continents to the oceans, and thereby affect the global climate via the sequestration of atmospheric CO2 into geological reservoirs. At the same time, mountainous landscapes experienced Quaternary variations in climate and vegetation – including the waxing and waning of glacial ice masses – and were therefore exposed to temporally varying erosional regimes. In the specific case of soil-mantled hillslopes, changing environmental conditions (e.g., temperature, precipitation) along with spatially variable topographic parameters (e.g., slope, aspect) are expected to modify the geomorphic processes responsible for the mobilization and downslope movement of soil material, such that soil erosion might represent a function of both space and time. Furthermore, transient soil erosion is likely coupled to alterations of the soil thickness and hence to changes in the production of soil material from the underlying bedrock. In this study, we investigate the spatio-temporal variability of soil production and erosion on different soil-covered alpine landforms within the Goms area (Switzerland), based on paired measurements of the in situ 14C and 10Be concentrations within quartz separates of saprolite (n=12) and till-derived (n=2) samples. The short half-life of 14C compared to 10Be provides this approach with a unique sensitivity for short-term changes of soil production and/or soil thickness on Lateglacial to Holocene time scales. For multiple sites, the apparent soil production rates and exposure ages calculated from the cosmogenic nuclide concentrations reveal a constant exposure of the saprolite-soil interface, without any (detectable) signs of soil production or changes to the thickness of the overlying soil column since the Early to Mid-Holocene. The absence of soil production in combination with a constant vertical extent of the soils further implies that the erosional downslope transport of soil material is inactive at these locations, despite their generally steep slope angles (10 to 38°). Remarkably, the estimated exposure ages also differentiate between relatively young samples (10Be: 5.5 to 7.8 ka; 14C: 5.4 to 7.9 ka) from tributary hillslopes and older samples (10Be: 10.2 to 12.0 ka; 14C: 9.6 to 12.7 ka) from the hillslopes of the main valley and erosional ridges, which represent important landforms within the investigated landscape. Additional results from Markov chain Monte Carlo inversion modelling indicate the potential occurrence of instantaneous losses of the soil cover (9.3 to 14.7 m at 7.6 to 8.7 ka) or the step-like decline of soil production rates (11- to 12-fold at 12.4 to 13.1 ka) for most of the remaining samples. Overall, these observations demonstrate the co-occurrence of ‘static’ sites without active soil production and erosion and more ‘dynamic’ sites characterized by transient, non-zero soil production and erosion rates, attesting to the spatial variability of hillslope soil dynamics between an active and an inactive state.

How to cite: Wartenweiler, S. H., Lupker, M., Haghipour, N., Christl, M., and Eglinton, T. I.: Hillslopes in action? Combining in situ 14C- and 10Be-derived insights into the spatio-temporal variability of soil dynamics on Swiss alpine hillslopes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15601, https://doi.org/10.5194/egusphere-egu24-15601, 2024.

EGU24-16703 | ECS | Orals | GM2.3

Reconciling late Cenozoic spatio-temporal patterns of Alpine topographic changes from low-temperature thermochronology and glacial morphometric signatures  

Isabel Wapenhans, Peter van der Beek, Maxime Bernard, Cody Colleps, and Julien Amalberti

Improving our understanding of the timing, rates and distribution of erosion across mountains and valleys plays a key part in resolving longstanding debates on how landscape dynamics are influenced by the interactions between climate, tectonics and erosion. In particular, the onset of glaciations and more variable climate in the Pliocene-Quaternary have been invoked to explain the observed global increase in erosion rates, arguing that glaciers are more efficient at eroding bedrock than rivers. But questions about the temporal and spatial impact of glacial erosion and potential feedback remain. To contribute to resolving this debate, we conducted a local-scale thermochronological study in the Tauern Window, Eastern European Alps, with the aim to compare our findings to patterns in the wider region and the Western Alps. The Tauern Window presents an ideal natural laboratory to isolate these interdependent effects due to its well constrained tectonic history of rapid uplift until ∼8 Ma. Comparatively, the western Alps have experienced similar glaciation but a different tectonic history, and show significantly higher geodetic uplift rates and millennial-timescale erosion rates. Thus, an East-West comparison could help shed light on the dominant controls on the laterally variable Alpine morphology.

Here, we present new apatite (U-Th)/He (AHe) data distributed along elevation profiles through several glacial valleys: the Italian Ahrntal and the Austrian Floitental, Krimmler Achental and Windbachtal. The low closure temperature of the AHe system is sufficiently sensitive to enable correlating recorded exhumation/denudation to surface processes and landscape-shaping dynamics, and allows us to examine the late-Cenozoic thermal history of the area. AHe dates range from ~3.4 to 12.5 Ma; the youngest dates are thus time congruent with the onset of glaciation.

Our data indicate variations in erosion rates with elevation down these valleys, which we suggest can be attributed to altitude-dependent glacial erosion intensity. These patterns are compared to a hypsometric analysis of the Eastern Alps, to determine possible links between observed denudation over the last few million years and present-day markers of glacially reshaped topography. This study also provides initial insight into the best suited locations for a future higher-resolution investigation using 4He/3He thermochronometry, which promises to be able to resolve the area’s denudation history into the Quaternary and allow for a more direct comparison to modern hypsometry. These findings will also inform a future focused investigation into landscape-shaping couplings discernible from thermochronological data used alongside landscape analysis via thermal-kinematic modelling in PecubeGUI.

How to cite: Wapenhans, I., van der Beek, P., Bernard, M., Colleps, C., and Amalberti, J.: Reconciling late Cenozoic spatio-temporal patterns of Alpine topographic changes from low-temperature thermochronology and glacial morphometric signatures , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16703, https://doi.org/10.5194/egusphere-egu24-16703, 2024.

EGU24-17371 | ECS | Orals | GM2.3

­­­­­ESR-thermochronometry in the western European Alps (Switzerland)  

Xiaoxia Wen, Melanie Bartz, Christoph Schmidt, and Georgina King

The western European Alps are characterised by deeply incised valleys, however the timing of their formation and the impact of Quaternary glaciation on rates of erosion remains disputed. This is mainly due to a lack of geochronological methods that cover the timespan of 103-106 years. Electron spin resonance (ESR) thermochronometry has a high potential to fill this temporal gap because of its low closure temperature (<100 °C), potentially allowing changes in erosion rates to be related to glacial advance and retreat. The Rhône Valley (Switzerland) was intensively glaciated during the Quaternary [1] while it is unclear how tributary valleys incised throughout the glaciation period. In this study, we focus on two study sites along the main valley, close to Sion and Visp and the Matter and Vispa river tributary valleys, towards Zermatt and Saas-Fee to compare their Quaternary exhumation histories.  Whilst bedrock samples from Sion yielded cooling ages between 209 and 674 ka, samples from Visp showed saturation around 2500 ka. Thermal stability varied between samples and signals, and sample measurement is ongoing. Preliminary inversion of the data shows that the low closure temperatures of the ESR signals in quartz allow the Late Quaternary exhumation of the Alpine valleys to be resolved, providing new insights into the glacial incision history during the Quaternary and especially how erosion rates varied temporally under a changing climate.

Reference:

[1] Valla, P.G., D.L. Shuster, and P.A. van der Beek. 2011. Significant increase in relief of the European Alps during mid-Pleistocene glaciations, Nature Geoscience. 4(10): p. 688-692.

How to cite: Wen, X., Bartz, M., Schmidt, C., and King, G.: ­­­­­ESR-thermochronometry in the western European Alps (Switzerland) , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17371, https://doi.org/10.5194/egusphere-egu24-17371, 2024.

The Rhenish/Ardenne Massif (RAM) spreads across parts of Belgium, France, Germany and Luxemburg; it is one of the largest (>40,000 km²) and most “emblematic” Variscan structures located north of the Alps (think of the “Romantic Rhine”). Intraplate uplift affected the RAM during the Plio-Quaternary along with other Palaeozoic massifs located in the alpine foreland. However, its cause(s), shape and rates are still poorly understood and therefore remain debated (e.g., Demoulin & Hallot, 2009). This was, until recently, mainly due to a lack of reliable ages for uplift markers, such as the Quaternary terrace staircases along deeply incised valleys of the Rhine, Moselle and Meuse as well as their main intra-massif tributaries. Several studies based on numerical dating methods (i.e., in situ cosmogenic nuclides, electron spin resonance, luminescence…) have shed new light on these questions by assigning numerical age estimates on key levels of fluvial terraces (e.g., the so-called main terraces; Rixhon et al., 2011; Cordier et al., 2012) or cave levels related to phases of regional base-level stability (Rixhon et al., 2020).

This contribution first compiles all chronological data produced over the last twenty years and critically assesses their reliability to infer massif-scale spatio-temporal patterns of river incision. Plio-Quaternary incision rates are accordingly reconstructed. A similar trend of increase is reported throughout the RAM with a peak of incision occurring during the Early or Middle Pleistocene and matching the massif-wide geomorphological marker materialised by the main terraces (and associated cave levels if any). However – and importantly – age control reveals a significant time lag (>250 ka) between the south-eastern and north-western RAM margins. The high incision rates onset is consistently older along the Rhine/Moselle and tributaries (e.g., the Sarre) than along the Meuse and tributaries (e.g., Ourthe). This key finding is well in line with Demoulin and Hallot’s (2009) hypothesis arguing for a wave of uplift migrating northward throughout the RAM. It also supports regional tectonic causes for uplift (i.e., late, upper-crustal stress transfer from the Alps to their foreland) rather than more local ones (i.e., mantle plume below the Eifel Massif). Age constraints along the river valleys draining the easternmost part of the RAM – so far absent – along with a global geodynamic modelling will represent further steps to better understand the evolution of the uplift history.

 

References:

Cordier S. et al., 2012. Geomorphology, 165-166, 91-106.

Demoulin, A., Hallot, E. 2009. Tectonophysics, 474, 696-708.

Rixhon, G., et al. 2011. Quaternary Geochronology, 6, 273-284.

Rixhon, G. et al. 2020. Geomorphology, 371, 107424.

How to cite: Rixhon, G.: From spatio-temporal patterns of river incision rates to Quaternary uplift history of the Variscan Rhenish/Ardenne Massif (N Europe), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17402, https://doi.org/10.5194/egusphere-egu24-17402, 2024.

EGU24-20370 | ECS | Orals | GM2.3

Age of deposition versus age of remobilized sediments in turbidites and implication for the duration of transport 

Etienne Large, Sophie Hage, Bernard Dennielou, Julien Charreau, and Pierre-Henri Blard

Turbidites are underwater land sliding events that correspond to the most distal part of the source-to-sink system. They can be triggered by a number of processes including flood events, storms, earthquakes or simply destabilization of a continental slope and are a vector of terrestrial sediments to deep depocenters. Marine sedimentary cores recording turbidites represent key sedimentary archives and can be used to track back the occurrence of such land and sea processes giving information on terrestrial paleo conditions.

Unfortunately, it is often difficult to assess which process initiated turbidites in particular because these are usually poorly dated. In most studies, turbidites are considered as instantaneous events and dated using foraminifera of the over and underlying hemipelagic layers. In this study, we bring new light on the age of the material remobilized by turbidites. To do so, we use 14C to date 20 samples of foraminifera and 38 samples of vegetal debris contained in two turbidites from two different cores of the Ogooué turbiditic system in western Africa. We have also dated foraminifera in the hemipelagic layers above and under these turbidites. The radiocarbon ages measured in the turbidites, when compared to the depositional ages of under- and overlying hemipelagic layers constrain the total transportation time from the source to the turbidite deposition, including both the duration of transport on land, and the potential storage of the sediments onshore and offshore (on the continental margin).

Our results shed new light on the transport and residence time of sediments in the Ogooué drainage system which is under 15 ka, on the residence time of sediments on the continental slopes or margins which is of about 3 ka, and on the depositional sequences and mechanisms of turbidites in said system. In a broader sense, it allows a better understanding of the mechanisms controlling turbidite deposition and its intrinsic timings. 

How to cite: Large, E., Hage, S., Dennielou, B., Charreau, J., and Blard, P.-H.: Age of deposition versus age of remobilized sediments in turbidites and implication for the duration of transport, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20370, https://doi.org/10.5194/egusphere-egu24-20370, 2024.

EGU24-1085 | ECS | Posters on site | GM2.6

Quantifying the Importance of Wind Erosion of Bare Peat: Initial Insights from Field Measurements and Wind Tunnel Modelling 

Yuzhe Zang, Jeff Warburton, Lian Gan, and Richard Hardy

Peat erosion and degradation contribute to 2-6% of total global emissions of carbon each year. Wind erosion of bare peat surfaces, is a significant component of erosion. However, how rapidly-changing bare peat surface aerodynamic properties affect erosion processes have not been fully quantified. This study investigates how the spatial and temporal characteristics of peatland wind erosion are controlled by the aerodynamic properties of the bare peat surface. Field measurements of local meteorology, peat surface properties and peat flux from a 3-ha bare area of upland blanket peat (North Pennines, UK), have been analysed during a sustained period of strong winds and rainfall (November to April 2023). Results demonstrate that the eroded peat flux is correlated with the southwest prevailing wind direction and as velocity increases, the flux becomes more focussed to the southwest (225°). Windward-facing peat fluxes are 4-9 times higher than those in the leeward direction. The vertical wind velocity profile over the bare peat shows a logarithmic pattern with height which is mirrored in the peat flux profile. Average friction velocity is only partially correlated to the peat flux during the strongest wind events suggesting that peat surface aerodynamic characteristics (roughness) also affect the pattern and magnitude of eroded peat flux. To investigate this hypothesis in greater detail wind tunnel experiments with a 3-D printed 1:1 rough peat surface model (0.5 x 0.7 m, average geometric roughness height 0.0345 m) in a large recirculating wind tunnel (2 x 0.6 x 0.6 m) are conducted to acquire the wind velocity profile over the peat boundary surface at 12 carefully selected characteristic locations. Experiments are conducted under free stream wind velocities at 2, 4, 6, 8, 10 m s-1 which are representative to the wind velocities observed in the field. Velocity measurements are taken by traversing a 5-hole probe in a normal direction with a spatial resolution of 2 mm within the boundary layer. Velocity signals are sampled at 500 Hz over 12 seconds at each sampling location. Flow properties including time-mean velocity, turbulence kinetic energy and wall shear stresses over the rough peat surface are analysed. These provide details of the wind flow field over the peat microtopography and allow us to investigate spatially and temporally resolved airflow dynamics. Further work using numerical modelling is planned to test the field observations and wind tunnel experiments and define in detail how surface roughness influences erosion of bare peat.

How to cite: Zang, Y., Warburton, J., Gan, L., and Hardy, R.: Quantifying the Importance of Wind Erosion of Bare Peat: Initial Insights from Field Measurements and Wind Tunnel Modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1085, https://doi.org/10.5194/egusphere-egu24-1085, 2024.

EGU24-3160 | ECS | Orals | GM2.6

Instability of Antidune Incipience under Low Submergence Conditions  

Sofi Farazande, Ivan Pascal, and Christophe Ancey

Investigating the stability of river bedforms is essential for understanding their occurrence and evolution over time. Whereas the formation of ripples and dunes has been extensively studied [1, 2], little is known about antidune stability in the early stages. Our research aims to fill this gap by focusing on antidune incipience in gravel-bed streams under low submergence conditions. Based on Vesipa et al. (2014), who distinguished between convective and absolute instabilities of bedforms [3], we investigated the behavior of the antidunes in the early stages of their formation. We conducted experiments in a narrow flume and studied how key flow factors (e.g., the Froude number, relative submergence, and initial perturbation) affect antidune dynamics. By filming the bed evolution from the sidewall, we determined the antidune wavelength and amplitude as a function of space and time in order to provide empirical insights that complement the theoretical framework.

 

[1] Colombini, M., and Stocchino, A. (2011). Ripple and dune formation in rivers. Journal of Fluid Mechanics, 673, pp. 121-131.

[2] Fourrière, A., Claudin, P., and Andreotti, B. (2010). Bedforms in a turbulent stream: formation of ripples by primary linear instability and of dunes by nonlinear pattern coarsening. Journal of Fluid Mechanics, 649, pp. 287-328.

[3] Vesipa, R., Camporeale, C., Ridolfi, L., and Chomaz, J. M. (2014). On the convective-absolute nature of river bedform instabilities. Physics of Fluids, 26, 124104

How to cite: Farazande, S., Pascal, I., and Ancey, C.: Instability of Antidune Incipience under Low Submergence Conditions , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3160, https://doi.org/10.5194/egusphere-egu24-3160, 2024.

Debris flows are classical two-phase flows that can be enhanced by entraining multi-grain sizes of sediments from the bed as they rush down steep slopes, in which particle segregation is related to assessing the potential hazards. However, understanding the characteristics and fluid-particle interaction mechanisms remains challenging. Here an existing depth-averaged two-phase continuum flow model is further improved by incorporating the effects of pore-fluid pressure and bed sediment conditions on erosion. To demonstrate its reliability, we compare numerical solutions with measurements of thickness, front location, and bed deformation in two sets of USGS large-scale experimental debris flows over erodible beds. The following physical understandings are obtained. First, the positive effects of pore-fluid pressure and coarse bed materials on erosion rates are numerically reproduced. Moreover, an additional mechanism for this phenomenon has been revealed. Specifically, debris flows on steep slopes are likely to fall into a high shear stress regime, under which conditions the sediment transport capacity always takes a maximum value and is independent of the sediment size. Therefore, the sediment settling velocity that is proportional to the sediment size affects the erosion rate directly. Second, we probe into the non-dimension number and energetics of the debris flows to find it necessary to incorporate water-sediment and particle-particle interactions into reproducing the debris flow processes. Third, two kinds of mechanisms for particle size coarsening in the head region of the debris flow are resolved: on the one hand, they can be incorporated and retained there if the debris flow acquires sediment from the bed in transit due to considering the hiding/exposure mechanisms and on the other hand, they can migrate to the head by preferential transport. Furthermore, a series of idealized tests were conducted to explore the factors contributing to the segregation of particles within a debris flow. The longitudinal particle segregation was reproduced by incorporating the shear-induced non-uniform vertical distributions of velocity and sediment concentrations, the visco-inertial rheology, as well as the grain-size heterogeneity into the modelling. Sensitive analysis shows that the transport of fine particles is more inhibited by the interaction of the flow, contributing to the larger transportation velocity of the coarse particle. We further observed that the water content, the slope, and the particle size would have positive effects on the longitudinal size segregation in the head region, contrasting with the negative effects of the flow viscosity. These factors affecting the segregation ratio are attributed to the changes in the ratio of the Reynolds Number of the flow between fine and coarse particle.

How to cite: Hu, P., Lyu, B., Li, J., Li, W., and Cao, Z.: Numerical investigation about propagation characteristics and hydro-sediment-morphodynamic interactions of multi-sized debris flow with a two-phase continuum model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4798, https://doi.org/10.5194/egusphere-egu24-4798, 2024.

EGU24-6100 | Posters on site | GM2.6

Measured distributions of velocity and concentration for intense transport of bimodal lightweight sediment in tilting flume 

Vaclav Matousek, Jan Krupicka, Tomas Picek, and Lukas Svoboda

The laboratory experiments on the intense transport of bimodal sediment were conducted in a tilted, glass-sided flume with a variable longitudinal slope. Two fractions of lightweight solids were used, primarily differing in particle size, and each had a distinct color. The observed solid-liquid flow exhibited characteristics of being steady, uniform, turbulent, and supercritical. The bimodal sediment was transported as a combined load, with the finer fraction primarily supported by carrier turbulence, and the coarser fraction supported by interparticle contacts in the transport layer above a plane surface of the bimodal stationary bed. Distributions of solids velocity and concentration were measured for each of the two fractions across the transport layer above the bed using optical methods employing high-speed cameras. Additionally, the distribution of carrier velocity was measured across the flow depth. The measurements revealed a non-uniform distribution of solids for both fractions, with the maximum concentrations at the top of the bed for the coarser fraction and within the transport layer for the finer fraction at the highest bed shear. The results of the measurements allowed for the identification of the degree of stratification in the high-concentration sediment-laden flow and facilitated the evaluation of the interaction between particles of different fractions in the transport layer at various elevations above the bed. Furthermore, they enabled the quantification of the proportion of particles of the two fractions in the total discharge of solids through the channel.

How to cite: Matousek, V., Krupicka, J., Picek, T., and Svoboda, L.: Measured distributions of velocity and concentration for intense transport of bimodal lightweight sediment in tilting flume, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6100, https://doi.org/10.5194/egusphere-egu24-6100, 2024.

Consecutive floods combined with hyperconcentrated floods and moderate/low sediment-laden floods have always been observed in the Lower Yellow River (LYR) characterized by complex channel-floodplain systems of alternated meandering and straight segments. Interactions between those floods and sophisticated morphological segments are much more complicated than normal low-sediment laden rivers of relatively simple geometry. In this regard, we numerically investigate the 92.8 consecutive floods in the natural channel-floodplain reach of Xiaolangdi-Jiahetan in the LYR by deploying a 2-D depth-averaged fully coupled morphological model. The major focus includes (1) the unusual phenomenon of downstream peak discharge increase and (2) the different hydro-morphodynamic behaviors between meandering and straight channel-floodplain systems. For the former, the peak discharge increase of hyperconcentrated floods could be satisfactorily reproduced when the effects of bed roughness reduction and bed deformation are considered simultaneously. For the latter, the water-sediment exchange between channels and floodplains is relatively strong in hyperconcentrated floods and exhibits distinct features in meandering and straight segments. The straight one is featured by lateral channel-floodplain diffusion while the meandering one is characterized by the transition from lateral diffusion at the meander apex to streamwise advection. Consequently, the deposition at the meanders (especially on the floodplains) is much larger than that at the straight reach floodplains resulting in a remarkable uneven deposition pattern along the streamwise direction.

 

Key words: Lower Yellow River; Hyperconcentrated floods; Channel-floodplain interactions; Morphological modelling; Sediment transport

 

Acknowledgements: National Natural Science Foundation of China (No. 12272349, 52339005).

How to cite: Li, W., Zhu, L., and Hu, P.: Modelling interactions between consecutive floods and channel-floodplain systems in the Lower Yellow River, China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7028, https://doi.org/10.5194/egusphere-egu24-7028, 2024.

EGU24-9106 | ECS | Orals | GM2.6

Formation and Kinematics of Basal Layer in Granular Flows Down Smooth and Rough Inclines 

Teng Wang, Lu Jing, and Fiona Kwok

Granular flow down a rough incline is a typical model case for geophysical mass flows. For insufficiently rough inclines, a strongly sheared basal layer can form below the less agitated bulk layer due to basal slip and particle collisions. However, the thickness and kinematic characteristics of the basal layer has not been well understood. Here, discrete element method (DEM) simulations are carried out to investigate the effects of base roughness on various kinematics profiles (i.e., velocity, shear rate and granular temperature) of the basal layer. The base roughness is varied systematically from geometrically smooth (i.e., a flat frictional plane) to moderately and sufficiently rough (formed by a layer of stationary particles). The base roughness is quantified by a dimensionless parameter, Ra, varying from 0 to 1, which has previously been found to control the transition from slip to non-slip regimes at around Ra=0.6. The present results show that, when basal slip occurs, the velocity profile deviates from the standard Bagnold’s profile, with an apparent basal slip and a basal layer where particles are highly agitated. The thickness of the basal layer, the slip velocity, and the level of velocity fluctuations (granular temperature) in the basal layer are all controlled by Ra. Intriguingly, the thickness of the basal layer, which is about several particle diameters, is insignificantly affected by other simulation conditions including the flow thickness and slope angle. Finally, the velocity profile is accurately described by a semi-empirical function based on the strong association between granular temperature and shear rate. Future work will focus on the rheology of the basal layer, which will potentially lead to more accurate predictions of geophysical granular flows.

How to cite: Wang, T., Jing, L., and Kwok, F.: Formation and Kinematics of Basal Layer in Granular Flows Down Smooth and Rough Inclines, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9106, https://doi.org/10.5194/egusphere-egu24-9106, 2024.

EGU24-9390 | ECS | Orals | GM2.6

Assessment and evaluation of the utility of hydrokinetic technologies in low head streams 

Mohamad Anas El Mir and Manousos Valyrakis

Large dams exploiting hydropower have been marvels of engineering practice, but over the decades their accrued environmental effects, such as sediment budget balances (due to upstream aggregation and downstream erosion) and water quality and fish biota degradation, were visible. Moreover, large centralised hydropower systems present the challenge of grid connectivity, as it can be challenging to connect large electricity grids to remote and inaccessible rural areas, not only due to costs but also due to the loss of energy due to high distances. Scotland having many small rural communities and thousands of small low-head streams, is a prime example for efficiently demonstrating tackling the above crucial challenges of small scale decentralised power generation, with alternative schemes such as micro-hydropower and hydro-kinetic systems. These flexible to install and operate systems, can help prevent grid connectivity problems and electricity loss. They can be installed in several locations due to their small assembly and easy construction process compared to large hydropower plants. They can also be installed at wastewater plants to exploit outlet flows. In this study several criteria were analysed to assess the new technologies based on data collected from various suppliers. The criteria covered several aspects of the technologies: health and safety, design, environmental constraints, employability, and financial viability. The selection process started to classify the viability of the technologies according to the score they achieved. The technologies are assessed, and optimal use sometimes based on the location and real world application, are offered.

How to cite: El Mir, M. A. and Valyrakis, M.: Assessment and evaluation of the utility of hydrokinetic technologies in low head streams, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9390, https://doi.org/10.5194/egusphere-egu24-9390, 2024.

EGU24-9559 | ECS | Orals | GM2.6

Vegetation Submergence Effects on Bedload Transport Rate 

Yesheng Lu, Nian-Sheng Cheng, Maoxing Wei, and Christophe Ancey

We conducted a series of laboratory experiments to investigate the impact of vegetation on bedload transport rates depending on submergence. In the experiments, we used aluminum rods to simulate rigid vegetation, with vegetation submergence ratios (i.e., the ratio of water depth to vegetation height) ranging from 1 to 2. The bedload transport rates were measured by collecting sediment at the end of the vegetated area. The findings indicate that, with a constant bulk-averaged flow velocity, bedload transport rates decrease as the submergence ratio increases. This decrease is attributed to changes in the flow velocity distribution resulting from the flow resistance exerted by submerged vegetation. Indeed, water flows more easily through the top of the vegetation, and concurrently water velocity decreases significantly in the bottom region occupied by the vegetation. Building upon the phenomenological theory of turbulence, we propose a hydraulic radius-based method for estimating bed shear stress by incorporating the submergence ratio effect. This model enables the application of Cheng’s (2002) bedload formula, originally developed for bare beds, to predict bedload transport rates in both emergent and submerged vegetated flows. The present model, calibrated with a single parameter from experimental data, exhibited an average relative error of about 400% when validated with using experimental data (275 data in all) from our study and the relevant literature.

How to cite: Lu, Y., Cheng, N.-S., Wei, M., and Ancey, C.: Vegetation Submergence Effects on Bedload Transport Rate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9559, https://doi.org/10.5194/egusphere-egu24-9559, 2024.

EGU24-9650 | ECS | Orals | GM2.6

Segregation of granular mixtures in an annular shear cell under shear, gravity, and convection 

Yanan Chen, Christophe Ancey, and Nico Gray

Particle-size segregation is a widespread process that affects granular materials. Under the influence of gravity and shear, particles segregate into distinct regions according to their size. To date, most experimental investigations have studied granular flows induced by gravity and shear. Less studied is the special case where the granular material is segregated under convection. We are concerned with this particular case. We conducted experiments by shearing bi-dispersed granular mixtures in an annular shear cell. Refractive-index matching (RIM) was achieved between particles and the surrounding fluid, which made it possible to visualize the granular flow when illuminated by a laser sheet. We reconstructed the particle spatial arrangement by applying the Hough Transformation to a continuous series of scans. Both axial and radial segregation was observed in experiments, i.e., small particles tended to percolate downwards and accumulated radially to the center region, while large particles were squeezed upwards and gathered in the exterior region. We found that axial segregation was related to gravity and shear, while the radial convection was related to the shear and convection. Solids volume fractions were computed as a function of time from three-dimensional scans of granular mixtures, from which segregation velocity was then derived. The experimental data provides interesting insights into segregation produced simultaneously in two directions.

How to cite: Chen, Y., Ancey, C., and Gray, N.: Segregation of granular mixtures in an annular shear cell under shear, gravity, and convection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9650, https://doi.org/10.5194/egusphere-egu24-9650, 2024.

EGU24-9765 | ECS | Orals | GM2.6

Impact of sediment transport on newly constructed embankments and flooding in the Nakkhu River, Kathmandu, Nepal 

Saraswati Thapa, Hugh D. Sinclair, Maggie J. Creed, Simon M. Mudd, Mikael Attal, Alistair G. L. Borthwick, and Bhola N. Ghimire

In Nepal, urbanization has significantly accelerated since 2017 due to the conversion of numerous rural administrative units into urban ones by the government. This trend is particularly pronounced in the Kathmandu Valley where development is taking place on a large scale, including the building of four smart satellite cities, an outer ring road and river corridor roads flanked by green belts. The result is increased urban sprawl, river channelization, and floodplain encroachment, accompanied by sand and gravel mining activities. Many embankments have been constructed for flood protection along the rivers in the Kathmandu valley, including the Nakkhu River. However, the increasing number of settlements in low-lying floodplain areas and associated infrastructure damage caused by overtopping, breaching, or seepage of embankments, raise questions about the long-term sustainability of embankments as a solution to prevent future floods.

Using numerical simulations in a coupled hydrodynamic and landscape evolution model, CAESAR-Lisflood, we investigate how such embankments affect sediment transport, channel geometry, conveyance capacity, and flood inundation along the Nakkhu River. Each simulation is based on a high-resolution digital elevation model (2 m pixels, acquired in 2019-2020). Input sediment grain sizes are derived from field measurements, and we drive the model for different flood scenarios using maximum daily discharge data provided from the Department of Hydrology and Meteorology, Nepal.

The results suggest that changes in channel geometry caused by sedimentation increase flood risk downstream, particularly where embankments have been built to replicate sinuous channel courses. Inundation area is significantly higher in a scenario that includes sediment transport compared to a flood event modelled without sediment. It is recommended that sediment transport analysis be undertaken in the routine design of embankments and planned developments for river floodplains to minimize flood risk. Our study indicates that the construction of embankments alone may not provide sustainable long-term protection against future floods in rivers carrying high sediment loads.

Keywords: River embankment; Sediment transport; River morphology; Flood modelling; Nepal

How to cite: Thapa, S., Sinclair, H. D., Creed, M. J., Mudd, S. M., Attal, M., Borthwick, A. G. L., and Ghimire, B. N.: Impact of sediment transport on newly constructed embankments and flooding in the Nakkhu River, Kathmandu, Nepal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9765, https://doi.org/10.5194/egusphere-egu24-9765, 2024.

EGU24-9774 | ECS | Posters virtual | GM2.6

Subaqueous bedform morphology and migration in a mountainous macrotidal estuary 

Ruiqing Liu, Heqin Cheng, Lizhi Teng, Zhongda Ren, Jinfeng Chen, Qian Yang, and Heshan Fan

Abstract: The subaqueous bedforms in mountainous macrotidal estuaries, distinguished by their large tidal range and strong tidal and river flow dynamics, exhibit complex interactions among hydrodynamics, sediment transport, and bedform morphology, setting them apart from river and marine bedforms. However, there is currently a lack of research on the development characteristics and mechanisms of bedforms in such estuaries. To address this gap, field observations were conducted in the Minjiang Estuary of the East China Sea in December 2021 and August 2023, utilizing multibeam echosounders, shallow seismic profilers, and Acoustic Doppler Current Profilers (ADCP). Field measurements, including bedform morphology, surface sediment grain size, and hydrodynamics, were collected during both flood and ebb seasons. The study aims to explore the development characteristics and evolutionary patterns of bedforms in mountainous macrotidal estuaries, using the Minjiang Estuary as a representative case. The results indicate that the surface sediments in the subaqueous delta plain to the delta front channel of the Minjiang Estuary are predominantly composed of gravelly sand, with a median grain size ranging from 12.77 to 724.51 µm. Large compound bedforms are prevalent, with wavelengths ranging from 7.23 to 233 m and heights from 0.1 to 11.42 m. Bedform size is positively correlated with sediment grain size in the respective regions, and bedform morphology is related to sediment composition and water depth. Bedforms in different regions of the Minjiang Estuary exhibit varying degrees of symmetry, with asymmetry being more common, occasionally interspersed with cosinusoidal bedforms exhibiting better symmetry, which correlates with the strength of regional tidal dynamics. This study is of significant importance for understanding and simulating estuarine hydrodynamics and sediment transport.

Keywords: Mountainous Macrotidal Estuary, Minjiang Estuary, Bedform Morphology, Subaqueous Bedforms, Tidal Currents

How to cite: Liu, R., Cheng, H., Teng, L., Ren, Z., Chen, J., Yang, Q., and Fan, H.: Subaqueous bedform morphology and migration in a mountainous macrotidal estuary, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9774, https://doi.org/10.5194/egusphere-egu24-9774, 2024.

The mechanics of geophysical granular flow has been widely studied using spherical particles. However, natural granular materials are nearly always non-spherical, and a fundamental understanding of how particle shape affects the dynamics of granular flow remains elusive. Here, we use the discrete element method to simulate dense granular flows down a rough incline with systematically varied particle elongation (indicated by the length-to-diameter aspect ratio, AR). For each value of AR, we first determine the well-known hstop curve delimiting no-flow and steady flow regimes and then carry out steady flow simulations above the hstop curve to extract Pouliquen’s flow rule relations between the Froude number (Fr=u/(gh)0.5) and the normalized flow thickness h/hstop, where u is the mean flow velocity, h is the flow thickness and g is the gravitational acceleration. Our results show that the Fr-h/hstop relations have a nonlinear dependence on AR (data collapse is not immediately achieved). Next, we analyze the statistics of particle orientation during the flow using a microscopic order parameter and find that more elongated particles tend to align better along a certain orientation, thus hindering the particle rotation. The dependence of the measured order parameter on AR seems to explain the trend in the Fr-h/hstop relations, but further investigations are needed to quantitatively connect this micromechanical understanding with the macroscopic flow behaviors. Finally, the effects of other shape parameters, such as particle flatness and angularity, will be studied to draw a fuller picture of how the particle shape affects the mobility of geophysical granular flows.

How to cite: Jing, L. and Liu, J.: Effects of particle elongation on dense granular flows down a rough inclined plane, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9977, https://doi.org/10.5194/egusphere-egu24-9977, 2024.

EGU24-10063 | ECS | Posters virtual | GM2.6

Incipient particle entraiment prediction with the use of machine learning methods 

Manousos Valyrakis and Taiwo Ojo

In natural water bodies, sheared turbulent flows are the forcing agent responsible for particle mobilization near the river bed surface. Several analytical approaches have been used to describe this phenomenon, with ambiguities in the analytical methods employed, resulting in methodological biases. The application of a machine learning technique, namely, Adaptive Neuro-Fuzzy Inference System (ANFIS), is proposed here to model sediment transport dynamics. It is hypothesized that turbulent flow of different magnitudes and sufficient duration or near bed instantaneous flow power is responsible for particle displacement. The entrainment of sediment is modeled using the dynamic incipient motion criteria of impulse and energetic turbulent flow events. Several ANFIS architectures have been developed to relate the hydrodynamic vectorial quantities to particle displacement. ANFIS combines artificial neural networks' adaptation and learning power with the advantage of fuzzy inference (IF-THEN) rules for knowledge representation. To demonstrate ANFIS applicability for near bed threshold conditions, streamwise velocity [1], and particle dislodgement [2], flume-based experimental data sets are obtained as input and output signals to train the ANFIS model of various architecture complexities. The energy-based criterion and impulse criterion are obtained as cubic and quadratic expressions of streamwise velocity, respectively, and they are also used as inputs to train the ANFIS model [3]. Following a trial and error approach, the models developed with these criteria are analyzed and compared in terms of their efficiency and predictability using several performance indices. The optimum performing model is found capable of replicating the complex dynamics of sediment transport.

References
[1] Liu, D., AlObaidi, K., Valyrakis, M.* (2022). The assessment of an Acoustic Doppler Velocimetry profiler from a user’s perspective, Acta Geophysica, 70, pp. 2297-2310. DOI: 10.1007/s11600-022-00896-3.
[2] AlObaidi, K., Valyrakis, M. (2021). Linking the explicit probability of entrainment of instrumented particles to flow hydrodynamics, Earth Surface Processes and Landforms, 46(12), pp. 2448-2465 DOI: 10.1002/esp.5188.
[3] Valyrakis, M., Diplas, P., Dancey, C.L. (2011). Prediction of coarse particle movement with adaptive neuro-fuzzy inference systems, Hydrological Processes, 25(22). pp.3513-3524, DOI:10.1002/hyp.8228.

How to cite: Valyrakis, M. and Ojo, T.: Incipient particle entraiment prediction with the use of machine learning methods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10063, https://doi.org/10.5194/egusphere-egu24-10063, 2024.

EGU24-10349 | ECS | Posters on site | GM2.6

Temporal development of the scour hole next to the riprap sloping structure 

Antonija Harasti, Gordon Gilja, Josip Vuco, Jelena Boban, and Manousos Valyrakis

Riprap sloping structure is effective as bridge pier scour protection in the immediate vicinity of piers. In turn, riprap disrupts the flow conditions in a larger area than is the case with piers without scour protection in place. While these structures effectively dissipate the turbulent energy around piers, scouring occurs at the toe of the riprap and threatens the stability of the riprap and adjacent riverbed or hydraulic structures in proximity. This research presents the temporal evolution of the scour hole forming next to the riprap sloping structure. The research combines flume experiments with a physical model and numerical simulations using FLOW-3D software calibrated with experimental data measured with an optical surface scanner. Investigating the change in the scour hole dimensions over time provides valuable insights into the understanding of scour development and the associated undermining of the riprap toe during flood events that can jeopardize the bridge stability. The results show that, while scour generally increases with the duration of the flood, there are also evident backfilling events that need to be recognized and accounted for during the bridge design.

References:
[1] Harasti, A.; Gilja, G.; Potočki, K.; Lacko, M. Scour at Bridge Piers Protected by the Riprap Sloping Structure: A Review. Water 2021, 13, 3606. https://doi.org/10.3390/w13243606
[2] Harasti, A.; Gilja, G.; Adžaga, N.; Žic, M. Analysis of Variables Influencing Scour on Large Sand-Bed Rivers Conducted Using Field Data. Appl. Sci. 2023, 13, 5365. https://doi.org/10.3390/app13095365

Acknowledgments
This work has been supported in part by Croatian Science Foundation under the project R3PEAT (UIP-2019-04-4046).

How to cite: Harasti, A., Gilja, G., Vuco, J., Boban, J., and Valyrakis, M.: Temporal development of the scour hole next to the riprap sloping structure, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10349, https://doi.org/10.5194/egusphere-egu24-10349, 2024.

EGU24-10417 | Posters on site | GM2.6

Change in flow field next to riprap sloping structure caused by variability of scoured bathymetry 

Gordon Gilja, Antonija Harasti, Dea Delija, Iva Mejašić, and Manousos Valyrakis

One approach to scour protection for bridge piers is constructing riprap sloping structure around the pier. To maintain its designated function, riprap must remain stable throughout the service life of the bridge, often exceeding 100 years and thus being vulnerable to more extreme hydrological events driven by climate change. The riprap sloping structure increases the size of the recirculation zone and turbulence downstream compared to a single pier. This paper presents the results of a detailed investigation of flow field dynamics over the scoured riverbed downstream of the riprap sloping structure. The research combines flume experiments with a physical model and numerical simulations using FLOW-3D software calibrated with experimental data measured with an acoustic Doppler velocimetry profiler, Vectrino ADVP. Investigating the complexities of the flow field resulting from the presence of riprap and interactions between the flow and scour development is essential for enhancing the design and performance of riprap structures in various hydraulic conditions. The results show that the change in scour geometry over time influences the flow direction in the zone downstream of the pier.

 

References

[1]    Gilja, G.; Fliszar, R.; Harasti, A.; Valyrakis, M. Calibration and Verification of Operation Parameters for an Array of Vectrino Profilers Configured for Turbulent Flow Field Measurement around Bridge Piers—Part I. Fluids 2022, 7, 315. https://doi.org/10.3390/fluids7100315

[2]    Gilja, G.; Fliszar, R.; Harasti, A.; Valyrakis, M. Calibration and Verification of Operation Parameters for an Array of Vectrino Profilers Configured for Turbulent Flow Field Measurement around Bridge Piers—Part II. Fluids 2023, 8, 199. https://doi.org/10.3390/fluids8070199

 

Acknowledgments

This work has been supported in part by the Croatian Science Foundation under the project R3PEAT (UIP-2019-04-4046)

How to cite: Gilja, G., Harasti, A., Delija, D., Mejašić, I., and Valyrakis, M.: Change in flow field next to riprap sloping structure caused by variability of scoured bathymetry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10417, https://doi.org/10.5194/egusphere-egu24-10417, 2024.

EGU24-11224 | ECS | Posters on site | GM2.6

Measuring flow resistance in rough-bed rivers using flume and CFD approaches 

Taís Yamasaki, Robert Houseago, Rebecca Hodge, Richard Hardy, Stephen Rice, Robert Ferguson, Christopher Hackney, Elowyn Yager, Joel Johnson, and Trevor Hoey

Accurate predictions of river channel flow resistance are necessary for estimating flow depth and/or velocity, and so are needed for predicting sediment transport and flood risk, river restoration and in-channel engineering. Standard approaches typically predict resistance as a function of the channel bed grain size distribution (GSD). However, in rough-bed rivers that comprise much of the river network (i.e. rivers where flow depth is not much greater than channel roughness elements), the sediment GSD is not the main factor that controls the channel shape, and so GSD does not provide a good predictor of flow resistance. In these channels, predictions need to instead account for the influence of multiple scales and shapes of roughness, including boulders, sediment patches, exposed bedrock and irregular banks, but we do not yet have suitable methods for making these predictions.  

We present initial results from flume and CFD modelling experiments that have been designed to identify how irregular river-beds affects the spatial pattern of form drag and determine overall flow resistance. Both experiments take advantage of high-resolution topographic data that has been collected from field locations using new survey techniques (terrestrial laser scanning and structure from motion photogrammetry). In the flume experiments, we used the data to create 1:10 scale 3D reproductions of three different river beds. For each bed we incrementally add sediment cover, boulders, and rough walls, and measured changes in channel topography. For each configuration we then measure how water depth varied across a range of discharges to evaluate bulk flow resistance. In the CFD experiments, we simulate a range of flows over the field topography to evaluate the spatial pattern of form drag across the bed. In subsequent experiments the topography will be manipulated to retain specific topographic scales, in order to assess how form drag changes. From both sets of experiments, we will identify which topographic (surface roughness) metrics best represent the effect of the differing river bed properties on bulk flow resistance, and hence offer most promise for improved predictive equations. 

How to cite: Yamasaki, T., Houseago, R., Hodge, R., Hardy, R., Rice, S., Ferguson, R., Hackney, C., Yager, E., Johnson, J., and Hoey, T.: Measuring flow resistance in rough-bed rivers using flume and CFD approaches, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11224, https://doi.org/10.5194/egusphere-egu24-11224, 2024.

EGU24-11293 | ECS | Orals | GM2.6

How do supercritical turbidity-current bedforms transition? Insights from seismic data interpretation in the South China Sea 

Biwen Wang, Guangfa Zhong, Liaoliang Wang, and Zenggui Kuang

The transition of supercritical turbidity-current bedforms has been studied in the flume experiments and outcrops, whereas similar bedform transitions in deep-sea cases are rare. To better understand the mechanism behind bedform transitions in natural environments, we investigated the tempo-spatial transition of supercritical turbidity-current bedforms in the lower continental slope to abyssal plain in the northeastern South China Sea, by high-quality single-channel seismic data analysis coupled with simple numerical modeling. Quaternary bedforms were delineated at >3400 m water depth, covering an area of ~20000 km2. These bedforms are characterized by long wavelength (0.4-5 km), low wave height (1-15 m), and large aspect ratio (80-730), which are identified as supercritical-flow bedforms. Four types of bedforms were further identified based on the morphology and internal structure, which are (I) upslope-migrating cyclic steps characterized by asymmetrical morphology with thick backsets and long wavelength; (II) upslope-migrating antidunes (UMAs) featured by nearly symmetrical morphology and relatively short wavelength; (III) downslope-migrating antidunes (DMAs) typified by gentle and sigmoid foresets and large aspect ratios; (IV) upper-stage plane beds (UPBs) consisting of low-relief wavy to subhorizontal reflections. Slope variations are highlighted to induce flow energy changes and facilitate bedform transitions. A slight slope decrease from 0.5 to 0.1° and 0.3 to 0.1-0.2° would respectively lead to the transition from UMAs to UPBs and from cyclic steps to UMAs, due to the hydraulic jump and flow acceleration. In contrast, an increased slope from 0.1 to 0.2° can contribute to the transition from UMAs to cyclic steps or DMAs by re-accelerating flows. Over time, the bedforms evolve from DMAs to UMAs and cyclic steps with growing wavelengths and wave heights, possibly caused by the inherited development of bedforms and increasing aggradation rates linked with progressively rising Taiwan uplifting rates. These bedforms consist of three contiguous fields fed by inter-seamount pathways and Manila Trench, comprising a supercritical-flow submarine fan apron that is far from the shelf edge and lacks submarine channels. This research was supported by the National Key Research and Development Program of China (Grant Number 2022YFF0800503).

How to cite: Wang, B., Zhong, G., Wang, L., and Kuang, Z.: How do supercritical turbidity-current bedforms transition? Insights from seismic data interpretation in the South China Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11293, https://doi.org/10.5194/egusphere-egu24-11293, 2024.

EGU24-12742 | Orals | GM2.6

Background Topography Affects the Degree of Three-Dimensionality of Tidal Sand Waves 

Abdel Nnafie, Janneke Krabbendam, Bas Borsje, and Huib de Swart

Offshore tidal sand waves on the sandy bed of shallow continental shelf seas are more three-dimensional (3D) in some places than others, where 3D refers to a pattern that shows variations in three spatial directions. These sand waves often display meandering, splitting, or merging crestlines. The degree of three-dimensionality seems to vary especially when large-scale bedforms, such as tidal sand banks, are present underneath the sand waves. Understanding this behavior is important for offshore activities, such as offshore wind farm construction or the maintenance of navigation channels. In this study, the degree of three-dimensionality of sand waves at five sites in the North Sea is quantified with a new measure. Results show that tidal sand waves on top of tidal sand banks are more two-dimensional (2D) than those on bank slopes or in open areas. Numerical simulations performed with a new long-term sand wave model support these differences in sand wave patterns. The primary cause of these differences is attributed to the deflection of tidal flow over a sand bank, which causes sand wave crests to be more aligned with the bank at its top than at its slopes. It is subsequently made plausible that the different patterns result from the competition between two known mechanisms. These mechanisms are nonlinear interactions between sand waves themselves (SW-SW interactions) and nonlinear interactions between sand banks and sand waves (SB-SW interactions). On bank tops, SB-SW interactions favor a 2D pattern, while SW-SW interactions, which produce a 3D pattern elsewhere, are less effective.

How to cite: Nnafie, A., Krabbendam, J., Borsje, B., and de Swart, H.: Background Topography Affects the Degree of Three-Dimensionality of Tidal Sand Waves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12742, https://doi.org/10.5194/egusphere-egu24-12742, 2024.

EGU24-13532 | ECS | Posters virtual | GM2.6

Research on nearshore subaqueous geomorphology stability detection based on few-shot learning 

Zhongda Ren, Peng Zhang, Heqin Cheng, Lizhi Teng, Jinfeng Chen, Yang Jin, Ruiqing Liu, Zhengyang Jia, and Hong Zhang

Detecting the stability of nearshore subaqueous geomorphology is a crucial challenge for ensuring early warning and controlling the stability of riverbank slopes. Acquiring nearshore subaqueous geomorphology data using unmanned ship-mounted acoustic multibeam systems is difficult, costly, and time-consuming. Moreover, it is often influenced by weather conditions. The limited availability of nearshore subaqueous geomorphology samples suitable for model training, combined with the high similarity between targets of nearshore unstable geomorphology and the background, poses significant challenges for traditional detection methods. In response to issues such as high similarity in subaqueous geomorphology images, large-scale variations in target size, and a scarcity of samples, this study proposes a nearshore subaqueous geomorphology instability detection framework based on Few-shot learning. Firstly, a feature extraction network is designed, replacing the backbone network with a Swin Transformer network. This network employs a feature pyramid network to extract multi-scale geomorphology features containing global information from the query set, facilitating the fusion of features across deep and shallow layers. Secondly, a weight adjustment module is devised to transform the support set into weight coefficients with class attributes. This adjustment helps in adapting the distribution of geomorphology features for detecting new class objects. Experimental results demonstrate that the proposed detection framework achieves desirable performance in terms of average precision and average recall indicators.
Keywords: Subaqueous Geomorphology; Stability Detection; Few-shot learning

How to cite: Ren, Z., Zhang, P., Cheng, H., Teng, L., Chen, J., Jin, Y., Liu, R., Jia, Z., and Zhang, H.: Research on nearshore subaqueous geomorphology stability detection based on few-shot learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13532, https://doi.org/10.5194/egusphere-egu24-13532, 2024.

EGU24-15069 | Orals | GM2.6

Modeling particle impacts on granular media for the analysis of aeolian saltation 

Provence Mahjoub-Bonnaire, Franck Bourrier, Luc Oger, and Guillaume Chambon

Grain transport by saltation is involved in numerous geophysical phenomena such as wind-blown sand, snow drift, aeolian soil erosion, dust emission, etc. Particle impacts on a granular bed trigger rebound and ejections processes, which can lead in certain conditions to a steady state of solid transport. The present work is dedicated to the analysis of the impact processes at the grain scale, with the objectives of inferring robust statistical laws and better understanding granular transport, accounting for the possible role played by adhesion between the grains.

The study is based on numerical simulations with the DEM (Discrete Element Method). The numerical experiments consist in throwing a spherical particle on a granular packing with controlled velocity (Froude number between 0 and 200) and impact angle (between 10° and 90°). The contact model (friction, cohesion) between the grains is varied to represent different types of granular materials (e.g., dry sand, wet sand, snow).
We investigated the influence of incident parameters on the impact process, focusing on the incident particle rebound and on the number and velocities of ejected particles. For non-cohesive granular beds, the simulations were compared to laboratory experiments of impacts of spherical particles on granular packings in order to validate the model . In particular, the restitution coefficient of the incident particles and the number of ejected particles were found in good agreement with experimental results. The simulations also give access to quantities that cannot be easily measured in the experiments. Hence, we could observe an anisotropy of ejected particles velocities for grazing impact angles, which is more pronounced when the incident velocity decreases.
Preliminary results concerning cohesive granular beds will also be presented, considering contact laws representative of liquid (capillary) and solid cohesion processes. Effect of cohesion on the number of ejected particles, and energy dissipation processes within the cohesive granular beds, will be discussed.

How to cite: Mahjoub-Bonnaire, P., Bourrier, F., Oger, L., and Chambon, G.: Modeling particle impacts on granular media for the analysis of aeolian saltation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15069, https://doi.org/10.5194/egusphere-egu24-15069, 2024.

EGU24-15693 | Orals | GM2.6

Classification of underwater flow-transverse sedimentary bedforms 

Alice Lefebvre, Robert W Dalrymple, Julia Cisneros, Leon Scheiber, Suzanne Hulscher, Arnoud Slootman, Maarten G. Kleinhans, and Elda Miramontes

Despite the recommendations given in Ashley (1990), a plethora of terms continues to be used to describe flow-scale flow-transverse sedimentary bedforms, often without clear definition or distinction between the different nomenclatures. For example, (marine) dunes and sand waves are used interchangeably in many contexts. Smaller bedforms superimposed on larger ones may be referred to as megaripples or secondary dunes. It is currently unclear if different terms are used due to intrinsic morphological or genetic differences or due to the traditions of different scientific communities. Ashley (1990) already noted that the “poor communication among scientists and engineers has perpetuated the multiplicity of terms”. Researchers from fluvial, coastal or deep-marine environments, from industry or academia, from various disciplines, such as sedimentology, oceanography, coastal and offshore engineering or geomorphology may use a specific vocabulary. Furthermore, terminology may differ depending on the country or research group in which they work. All this makes communication difficult and may cause misinterpretations, hindering progress in understanding and cross-disciplinary collaborative pursuits.

The aim of the present contribution is to provide an updated classification of the different types of underwater flow-transverse sedimentary bedforms. The intent is to homogenise the nomenclature for researchers coming from different disciplines and working in varied environments, to enable the use of a common classification and terminology to improve knowledge exchange, comparison and dialogue.

We propose a description table, which can be used by scientists and practitioners to describe the sedimentary bedforms with which they are working. Importantly, each bedform characteristic is described and the way to calculate the quantitative descriptive parameters is detailed. The description table aims at providing a standard and consistent way to describe the bedforms and their environmental setting prior to classifying them. The description table can be used independently of bedform type and further classification, which should overcome communication issues.

Two classification schemes are then proposed. The first is based on an understanding of the genetic processes. This should be used whenever possible because it informs about the underlying processes which formed the bedform. In order to complement the process-based classification, or in situations where the genetic processes are unknown, a second, geomorphological classification is introduced. Thus, we urge the bedform community to consider deploying these descriptor and classification tools and hope our contribution leads to a much more transparent and cohesive future in bedform research.

How to cite: Lefebvre, A., Dalrymple, R. W., Cisneros, J., Scheiber, L., Hulscher, S., Slootman, A., Kleinhans, M. G., and Miramontes, E.: Classification of underwater flow-transverse sedimentary bedforms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15693, https://doi.org/10.5194/egusphere-egu24-15693, 2024.

The study of the geomorphic dynamics of consecutive bends in Yangtze River under controlled conditions, i.e., the regulated water and sediment process, and the bank protection project, contributes to the further understanding of the meandering river theory. In this study, by combining the topographic data and remote sensing data, the morphological adjustment of typical consecutive bends in Yangtze River in response to upstream damming are analyzed. The results show that during 2006-2021, the riverbed is scoured generally. The consecutive bends are generally characterized by inner-bank scouring and outer-bank sedimentation. Besides, the evolution of the front and back bends shows good correlation, and the longer the length of the transition section, the weaker the correlation between the evolution of the front and back bends. The results of the study may serve as a rational reference for managing natural meandering rivers with multiple hydrological, geomorphological, and ecological goals.

How to cite: He, X. and Yu, M.: The morphological adjustment of typical consecutive bends in Yangtze River in response to upstream damming, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15932, https://doi.org/10.5194/egusphere-egu24-15932, 2024.

EGU24-16292 | ECS | Orals | GM2.6

Flow rule for unsteady flows of spherical and non-spherical grains down rough inclined planes 

Yanbin Wu, Zixiao Guo, Thomas Pähtz, and Zhiguo He

Based on laboratory experiments, Pouliquen (1999) uncovered a universal scaling law for the average velocity v of homogeneous flows of spherical grains down rough inclines [1]: , where g is the gravitational acceleration, h the flow thickness, and hs(θ) the thickness below which the flow stops depending on the inclination angle θ. Today, this so-called “flow rule” is well established in the field and has served as a critical test for continuum granular flow models [2]. However, based on more accurate measurements for granular materials composed of either spherical or non-spherical grains, Börzsönyi and Ecke (2007) found and pointed out that this revised flow rule was predicted by a two-dimensional granular kinetic theory [3, 4]. In addition, for non-spherical grains, they noticed deviations from this rule at large h/hs. Both Pouliquen and Börzsönyi and Ecke assumed that the granular flows in their experiments were steady.

Here, we report on new systematic experiments for granular materials composed of spherical glass beads, different kinds of non-spherical sands, and grain-size-equivalent mixtures of these. Their careful analysis reveals a new grain-shape-dependent flow rule that resolves the above contradictions in the current literature and provides quantitative evidence for the statement that the deviations observed by Börzsönyi and Ecke can be attributed to the flows not having reached the steady state.

[1] Pouliquen O. Scaling laws in granular flows down rough inclined planes[J]. Physics of fluids, 1999, 11(3): 542-548.

[2] Kamrin K, Henann D L. Nonlocal modeling of granular flows down inclines[J]. Soft matter, 2015, 11(1): 179-185.

[3] Börzsönyi T, Ecke R E. Flow rule of dense granular flows down a rough incline[J]. Physical Review E, 2007, 76(3): 031301.

[4] Jenkins J T. Dense shearing flows of inelastic disks[J]. Physics of Fluids, 2006, 18(10).

How to cite: Wu, Y., Guo, Z., Pähtz, T., and He, Z.: Flow rule for unsteady flows of spherical and non-spherical grains down rough inclined planes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16292, https://doi.org/10.5194/egusphere-egu24-16292, 2024.

EGU24-17522 | ECS | Orals | GM2.6

Experimental modelling of local scour phenomenon at a series of repelling emergent spur dikes  

Sandeep Kumar and Prashanth Reddy Hanmaiahgari

A spur dike is an elongated artificial structure with one end on the bank of a stream and the other end projecting into the current, and it is the most cost-effective river training structure that can be built at the channel’s banks. A series of spur dikes are usually more efficient in stabilizing the alluvial shores, whereas single spur dikes alter the local field. Thus, analyzing the local scour phenomena surrounding hydraulic structures in rivers is crucial to minimize the hazard of foundation collapse.

Therefore, experiments have been conducted to study the phenomenon of local scouring around the series of repelling spur dikes under clear water conditions, analysis of flow behavior & alterations in the morphology of sediment bed, and turbulent fluctuation. The inclination angle of the non-submerged spur dike with the vertical wall was kept 600 during the study in the straight rectangular flume of length, width, and depth are 15 m, 0.91 m, and 0.70 m. While the projected length of spur dikes was 1/5 of the width of the channel, and the spacing between spur dikes was 2.5 * the projected length of spur dike. In laboratory experiments, the flow velocities and bed deformation around the series of repelling spur dikes were measured using an Acoustic Doppler velocimeter, a high-resolution laser displacement meter, and a point gauge.

The test section consists of uniform sediment particles, the experiment was initiated with a leveled sediment bed, and a scouring phenomenon was observed throughout the experiment at the head, middle, and end of each spur dike in the u/s and d/s. The 3D velocity measurement is done at the head of the spur dike from u/s of the first spur dike till downstream of the third spur dike. Velocity measurements provide information on dominant agents responsible for the local scour.

It was concluded that the maximum depth of the scour hole 14.47 cm at 1st spur dike head. Digging and siltation was a cyclic process till equilibrium was achieved during the experiment, and the flow was classified as subcritical and turbulent. The approaching flow has less strength between the 1st and 2nd spur dike as it moves upward mostly in the top section.  The negative values of  over some length was observed in the scoring zone near the bed. While comparing the value of non-dimensional Reynolds Shear Stress -uv/u*2,  -uw/u*2,  -vw/u*2, it was observed that -uw/u*2, had a much greater both positive and negative value compared to the other. The Turbulent Kinetic Energy distribution shows that there is relatively more turbulence surrounding the 1st spur dike.

How to cite: Kumar, S. and Hanmaiahgari, P. R.: Experimental modelling of local scour phenomenon at a series of repelling emergent spur dikes , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17522, https://doi.org/10.5194/egusphere-egu24-17522, 2024.

EGU24-17681 | ECS | Orals | GM2.6

Typical design hydrograph method based on a joint distribution approach combining flood peak discharge, volume and duration 

Martina Lacko, Kristina Potočki, Kristina Ana Škreb, Nejc Bezak, and Gordon Gilja

Determination of flood magnitude and shape characteristics are necessary to provide a more complete assessment of flood severity and its impact in scour development analysis. Our recent research has focused on a joint distribution approach to account for the multivariate nature of flood characteristics, resulting in probability of occurrence of different pairs of flood variables: flood peak (Q), volume (V) and duration (D). To extend the results of this research, a method for deriving a design hydrograph is applied to the study area by using the typical hydrograph method. As it is recommended to test multiple scenarios in a scour analysis, different typical flood hydrographs were selected at several gauging stations on the Sava and Drava rivers in Croatia and multiplied by the design discharge values. The aim of this study is to complement the ongoing research of the relationship between climate change indicators, flood wave characteristics and scour development next to the bridges crossing large rivers in Croatia with installed scour countermeasures by preparing hydrological input data for a hydraulic scour analysis.

How to cite: Lacko, M., Potočki, K., Škreb, K. A., Bezak, N., and Gilja, G.: Typical design hydrograph method based on a joint distribution approach combining flood peak discharge, volume and duration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17681, https://doi.org/10.5194/egusphere-egu24-17681, 2024.

Granular media has near omnipresence in nature and is the second most processed substance in industry, after water. It is well accepted that it exhibits a wide spectrum of macro-scale behaviour which is ultimately determined by the grain-scale interactions of its constituent particles [1][2][3]; but there is still much to be discovered about those grain-scale interactions themselves. Away from the free surface of an agitated granular bed, the dominant grain-scale interactions are relative sliding and rolling between neighbouring particles [4], and it is this sliding and rolling which is the subject of this research.

In these experimental lab-based tests, ‘dry’ and ‘wet’ ideal granular beds are harmonically compressed via a moving side-wall and their responses captured via high-speed imaging. The granular media itself is a quasi-2D bed of polydisperse discs consisting of an even mixture of five different disc diameters ranging from 11mm to 36mm. The cyclic compressions are specifically designed to impose a jamming effect within the granular beds, before subsequent relaxation and deformation.

Use of the photo-elastic technique provides a window through which the grain-scale behaviour of the beds can be examined, as networks of inter-particle contact forces, known as force chains, become visible. Disc rotation is measured by tracking lines drawn onto each disc, providing useful insight into the sliding and rolling inter-particle interactions at the grain-scale. First, the behaviour of a ‘dry’ granular bed is examined, and then a thin layer of glycerol is spread onto the edges of each individual disc in order for the behaviour of an equivalent ‘wet’ granular bed – or at least, a bed with reduced inter-particle friction – to be examined. The behaviour of these beds are then compared to one another, and the results used to discuss how changes to friction at the grain scale affects the behaviour of granular bodies.

 

 

[1] Singh, S., Murthy, T.G.: Evolution of structure of cohesive granular ensembles in compression. International Journal of Solids and Structures 238(1), 111359 (2022)

[2] Jiang, M., Yu, H., Harris, D.: A novel discrete model for granular material incorporating rolling resistance. Computers and Geotechnics 32(5), 340–357 (2005)

[3] Oda, M., Konishi, J., Nemat-Nasser, S.: Experimental micromechanical evaluation of strength of granular materials: effects of particle rolling. Mechanics of Materials 1(4), 269–283 (1982)

[4] Moss, J., Glovnea, R.: Behavioural responses to horizontal vibrations of quasi-2D ideal granular beds: an experimental approach. Granular Matter 25(4), 63 (2023).

How to cite: Moss, J. and Glovnea, R.: Friction at the grain-scale: the role of inter-particle friction in granular media and its influence on grain-scale bed behaviour, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18798, https://doi.org/10.5194/egusphere-egu24-18798, 2024.

EGU24-19002 | ECS | Orals | GM2.6

A three-species model of aeolian saltation incorporating cooperative splash 

Yulan Chen, Thomas Pähtz, Katharina Tholen, and Klaus Kroy

Most aeolian sand transport models incorporate a so-called splash function that describes the number and velocity of particles ejected by the splash of an impacting particle. It is usually obtained from experiments or simulations in which an incident grain is shot onto a static granular packing. However, it has recently been discovered that, during aeolian sand transport, the bed cannot be considered as static, since it cannot completely recover between successive impacts. This led to a correction of the splash function accounting for cooperative effects [1], which were shown to be responsible for an anomalous third-root scaling of the sand flux with the particle-fluid density ratio s, observed in discrete-element-method-based simulations of aeolian sand transport across six orders of magnitude of s [2]. The model by [1] represents the aeolian transport layer by two species: high-energy saltons that eject low-energy reptons upon impact. While it quantitatively captures measurements and the simulated sand flux scaling, it does not recover the scaling laws of the simulated transport threshold and vertical flux at the bed. Here, we improve the model by [1] by means of a three-species saltation model. The additional species, called leapers, represent the fastest reptons, ejected by saltons in rare extreme ejection events. Together, saltons and leapers quantitatively reproduce the threshold and sand flux scaling behaviors, whereas reptons are predominantly responsible for the vertical bed surface fluxes seen in the simulations.

[1] Tholen, Pähtz, Kamath, Parteli, Kroy, Anomalous scaling of aeolian sand transport reveals coupling to bed rheology, Physical Review Letters 130 (5), 058204 (2023). https://doi.org/10.1103/PhysRevLett.130.058204

[2] Pähtz, Durán, Scaling laws for planetary sediment transport from DEM-RANS numerical simulations, Journal of Fluid Mechanics 963, A20 (2023). https://doi.org/10.1017/jfm.2023.343

How to cite: Chen, Y., Pähtz, T., Tholen, K., and Kroy, K.: A three-species model of aeolian saltation incorporating cooperative splash, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19002, https://doi.org/10.5194/egusphere-egu24-19002, 2024.

EGU24-20911 | Posters on site | GM2.6

Kinematics of the jamming front resulting from the clogging of the flow of monodisperse inelastic particles in a partially obstructed chute 

Rui M L Ferreira, Solange Mendes, Rui Aleixo, Amaral Amaral, and Michele Larcher

We characterize experimentally the upstream-progressing jamming wave triggered by the clogging of a granular flow down a partially obstructed chute. We generated dry granular flows in a sloping chute whose outlet was obstructed by a wall with two vertical gaps, twice the diameter of the granular material. We conducted 31 repetitions of the same test to obtain stable statistics. We employed Particle Tracking Velocimetry (PTV) to determine particle velocities at the sidewall and estimated fields of mean velocity and granular temperature by ensemble-averaging. Each ensemble is a set of valid grain velocities collected in space-time bins, that map the entire domain, over all test repetitions. The system is highly dissipative due to collisions and enduring contacts among inelastic particles, resulting in generalised cooling. Clogging occurs as a consequence of the formation of stable arch-like structures at the outlet, while the flow cools down. We observe that the jamming wave propagates against the flow at different values of granular temperature and mean velocity. There is no triple point in the system in the sense that jamming is always preceded by gas-liquid transition. For the tested conditions, jamming can be described as an accretion problem, leading to a granular solid state from liquid state and never from the gaseous state. The jamming wavefront progresses faster as the values of the granular temperature decrease. Flow cooling, including gas-fluid transitions, seem independent of jamming, which is compatible with the range of observed granular Froude and Mach numbers. The jamming wavefront becomes faster than the adiabatic speed of sound of the granular material moving towards the jammed region.

 

Acknowledgements: This work was partially funded by the Portuguese Foundation for Science and Technology (FCT) through Project DikesFPro PTDC/ECI-EGC/7739/2020 and through CERIS funding UIDB/04625/2020

How to cite: L Ferreira, R. M., Mendes, S., Aleixo, R., Amaral, A., and Larcher, M.: Kinematics of the jamming front resulting from the clogging of the flow of monodisperse inelastic particles in a partially obstructed chute, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20911, https://doi.org/10.5194/egusphere-egu24-20911, 2024.

EGU24-22239 | ECS | Posters on site | GM2.6

Numerical simulation of dike breaching by overtopping. Influence of the bank erosion operator.  

Ricardo Jonatas, Rui M L Ferreira, Ana M Ricardo, and Sílvia Amaral

We employ a physically-based in-house 2D multi-layered depth and time averaged shallow water model with the capacity to simulate morphology and sediment transport (HiSTAV) to model the erosion of dikes subjected to overtopping. Its conceptual model is based on conservation laws for shallow flows and requires closures for flow resistance, and sources and sinks of transported substances. The conservation laws are discretized within a Godunov-type Finite Volume scheme. HiSTAV design is entirely cross-compatible between CPUs and GPUs, through an intuitive object-oriented approach. HiSTAV requires the parametrization of the processes expressing hydraulic erosion, slope failure and mass detachment. The latter are modelled as sudden collapses of cells of dam body, dry but adjacent to the flow, a process akin to river bank collapse. A secondary mesh is defined to group the cells that form the detached mass. We investigate the effects of the dimension of the group and the values of the parameters (velocity and shear stress) that trigger the collapse. As expected, the bulk erosion rate increases with the size of the detached group. The results of the model were compared with data from laboratory models. Three laboratory tests were carried out in a medium-scale facility located at the Fluvial Facilities of the Hydraulics and Environment Department (DHA) of LNEC. The facility operates in closed circuit and is composed by a 1.40 m wide and 19 m long channel where the river stream is simulated. It allows testing dikes up to 0.50 m height and 2.0 m long. The water level upstream the dike is controlled by a sluice gate placed at the downstream end of the channel. The dike site and the main channel where constructed in an elevated platform, after which there a settling basin (2.10W x 4.5L (m)) where the eroded soil from the failure tests is deposited. A Bazin spillway exists at the end of this structure to measure the dike outflow discharge. We performed 3-D reconstructions of the evolving dike geometry, monitored the water levels in the main channel, the flow discharges in the main channel and across the breach and calculated the surface velocity fields in the vicinity and breach (LSPIV). The rate of breach erosion and the velocities near the breach were compared with the results of the model. It was observed that the size of the detachment group should scale with the breach crest and is influenced by the type of soil.

Acknowledgements: This work was partially funded by the Portuguese Foundation for Science and Technology (FCT) through Project DikesFPro PTDC/ECI-EGC/7739/2020 and through CERIS funding UIDB/04625/2020

How to cite: Jonatas, R., L Ferreira, R. M., Ricardo, A. M., and Amaral, S.: Numerical simulation of dike breaching by overtopping. Influence of the bank erosion operator. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22239, https://doi.org/10.5194/egusphere-egu24-22239, 2024.

EGU24-6080 | Posters on site | CL5.3

U-Th dating of gypsum: methodology and reference materials 

Xuefeng Wang, Lisheng Wang, Zhibang Ma, Wuhui Duan, and Jule Xiao

Gypsum is a common evaporate mineral in a wide variety of geological settings, especially in arid and semi-arid areas. It often precipitated from the natural brine systems with trace amounts of U and almost no Th, rendering it a potentially valuable U-Th geochronometer. However, U-Th dating of gypsum is often challenging, such as how to quickly and completely digest gypsum into solution, and avoid the re-crystallization of gypsum particles during the digestion and chromatography process. Here we present a rapid and practical method for high-precision U-Th dating of gypsum using the (NH4)2CO3 exchange reaction and double-spike method by MC-ICPMS. Our developed protocol addresses these conventional challenges by using the chemical reaction between calcium sulfate and carbonate, resulting in the (NH4)2SO4 solution and CaCO3 precipitate. Then the CaCO3 could be easily digested by diluted acid. With the solid-liquid separation, Ca2+ and SO42- ions are also effectively separated, minimizing the recrystallization of gypsum. The (NH4)2CO3 median, the gypsum/carbonate molar ratio of 1: 4, and the exchange reaction duration of 1.5 ~ 2 hours are suggested in this protocol. Since there is no gypsum U-Th dating reference materials to validate the accuracy of different approaches and ensure methods are repeatable across laboratories. We also prepared and characterized two natural gypsum U-Th dating reference materials (PXCG-1, PXCG-2) from PiXiao Cave, southwest China. Data from three different laboratories exhibit good agreement with both 238U content, δ234U, 230Th/238U activity ratio, and the 230Th ages. The 230Th ages of PXCG-1, PXCG-2 RMs proposed are 66.97 ± 0.31 ka, 260.82 ± 3.39 ka, respectively.

How to cite: Wang, X., Wang, L., Ma, Z., Duan, W., and Xiao, J.: U-Th dating of gypsum: methodology and reference materials, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6080, https://doi.org/10.5194/egusphere-egu24-6080, 2024.

EGU24-10443 | Posters on site | CL5.3

14C bomb peak and the onset of the Anthropocene 

Irka Hajdas, Carley Crann, Kristine DeLong, Barbara Fiałkiewicz-Kozieł, Juliana Ivar Do Sul, Jerome Kaiser, Francine M.G. McCarthy, Simon Turner, Allison Stenger, Colin Waters, and Jens Zinke

The unprecedented environmental changes resulting from anthropogenic activities initiated during the Great Acceleration of the mid-20th century can be traced using radiocarbon analysis. The cosmogenic isotope 14C, which is produced in the atmosphere, is well-known as the geochronological tool applied to archives of the last 55 thousand years. However, during the last 200 years, the natural signal of 14C in the atmosphere and connected reservoirs (biosphere, ocean, soils, etc.,) has been perturbed by human activities. Two anthropogenic effects are observed: a decreasing trend observed in 14C concentration of the atmosphere (Suess effect) which has been temporarily reversed by aboveground thermonuclear tests of the 1950/60s.

The excess of the artificially produced 14C (bomb pulse) is a useful time marker for the mid-20th century and the detection of the bomb peak in natural archives has thus been proposed as a tool to locate and date the onset of a proposed new epoch, the Anthropocene [1].

Here we present the results of radiocarbon analysis conducted as a part of the research dedicated to establishing the Global boundary Stratotype Section and Point (GSSP) for the proposed Anthropocene series. The studied sites include corals (Flinders Reef, AU and Flower Garden Banks, USA)[2, 3], peat (Śnieżka peatland, PL)[4], lake sediment (Crawford Lake, CA and Searsville Lake, USA)[5, 6] and marine sediment (East Gotland Basin, Baltic Sea)[7]. The variety of records (different carbon reservoirs) required site and sample-specific treatment prior to analysis and site-specific interpretation of the measured 14C. Nevertheless, the mid-20th century bomb peak was detected at all but one of these sites (Searsville Lake)[6]. In all records, the observed onset of the 14C bomb peak always postdates 1954, the year of the first atmospheric 14C bomb increase. The specific reservoir effects and corrections will be discussed.

References

The Anthropocene Review, 2023. 10(1):

1.    Waters, C.N., et al. (Eds.), Candidate sites and other reference sections for the Global boundary Stratotype Section and Point of the Anthropocene series.  p. 3-24.

2.    Zinke, J., et al., North Flinders Reef (Coral Sea, Australia) Porites sp. corals as a candidate Global boundary Stratotype Section and Point  for the Anthropocene series.  p. 201-224.

3.    DeLong, K.L., et al., The Flower Garden Banks Siderastrea siderea coral as a candidate Global boundary Stratotype Section and Point  for the Anthropocene series. p. 225-250.

4.    Fiałkiewicz-Kozieł, B., et al., The Śnieżka peatland as a candidate for the Global boundary Stratotype Section and Point  for the Anthropocene series.  p. 288-315.

5.    McCarthy, F.M.G., et al., The varved succession of Crawford Lake, Milton, Ontario, Canada as a candidate Global boundary Stratotype Section and Point for the Anthropocene series.  p. 146-176.

6.    Stegner, M.A., et al., The Searsville Lake Site (California, USA) as a candidate Global boundary Stratotype Section and Point for the Anthropocene Series. p. 116-145.

7.    Kaiser, J., et al., The East Gotland Basin (Baltic Sea) as a candidate Global boundary Stratotype Section and Point for the Anthropocene series. p. 25-48.

How to cite: Hajdas, I., Crann, C., DeLong, K., Fiałkiewicz-Kozieł, B., Ivar Do Sul, J., Kaiser, J., McCarthy, F. M. G., Turner, S., Stenger, A., Waters, C., and Zinke, J.: 14C bomb peak and the onset of the Anthropocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10443, https://doi.org/10.5194/egusphere-egu24-10443, 2024.

EGU24-13250 | Posters on site | CL5.3

Assessing Gol-e-Zard Cave (GZS) and Bergen Speleothem Standards (BSS) for U/Th Geochronometry Using MC-ICP-MS 

Altug Hasözbek, Fernando Jiménez-Barredo, Arash Sharifi, Ali Pourmand, Regina Mertz-Kraus, Michael Weber, Denis Scholz, Stein-Erik Lauritzen, Josep M. Parés, and Silviu Constantin

Recent advancements in MC-ICPMS technology have significantly enhanced the application of U/Th geochronometry in both biogenic and chemically precipitated carbonate rocks of almost middle Pleistocene to upper Holocene. This burgeoning use, particularly in the study of late Pleistocene earth surface processes, underscores the need for standardized reference materials with a broad age spectrum with different uranium and thorium concentrations. Addressing this need, our study evaluates speleothem specimens, Gol-e-Zard Cave Standard (GZS) and Bergen Speleothem Standard (BSS), as potential reference materials.

BSS-2 was processed as a homogenized powder and dissolved aliquot for U-Th dating using MC-ICP-MS analysis. We employed various digestion and ion-resin chromatography separation methods, followed by U-Th dating using MC-ICP-MS at CENIEH, University of Miami, and University of Mainz. The ion chromatography protocols yielded recovery rates ranging from 85% to over 95%. U-series analyses of powdered BSS-2 indicated uncertainties between 0.2-1.5%, attributed to variations in the Beta-factor and the specific U and Th standard bracketing procedures used across laboratories. The dissolved BSS-2 aliquots yield between 1.5-2% of uncertainty. Obtained U-Th ages were 122.8 ± 3.3 ka (University of Miami), 124.5 ± 0.3 ka (University of Mainz), and 123.9 ± 3.2 ka (CENIEH) in the powdered samples. Furthermore, in dissolved samples, the Th-ages vary between 126.9 ± 2.9 to 127.9 ± 3.1 (CENIEH & University of Miami). GZS was prepared as a dissolved standard and the Th-date results obtained from this stalagmite are 3967 ± 0.1 to 3988 ± 0.1 (University of Miami), and 3967 ± 0.1 to 4060 ± 0.4 (CENIEH).

All Th-dates required no correction as activity ratios [230Th/232Th] exceeded 500 and 150 for BSS-2 and GZS, respectively. The consistency of these preliminary results across different laboratories suggest that GZS and BSS-2 are promising reference materials for U-Series analysis of calcium carbonate.

How to cite: Hasözbek, A., Jiménez-Barredo, F., Sharifi, A., Pourmand, A., Mertz-Kraus, R., Weber, M., Scholz, D., Lauritzen, S.-E., M. Parés, J., and Constantin, S.: Assessing Gol-e-Zard Cave (GZS) and Bergen Speleothem Standards (BSS) for U/Th Geochronometry Using MC-ICP-MS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13250, https://doi.org/10.5194/egusphere-egu24-13250, 2024.

EGU24-17301 | ECS | Posters on site | CL5.3

Refining the age-depth model of a marine sediment record in the Laptev Sea using Beryllium-10 

Arnaud Nicolas, Gesine Mollenhauer, Maylin Malter, Jutta Wollenburg, and Florian Adolphi

In order to correctly determine leads and lags in the climate system and compare different proxy records over long time periods, it is important to build robust chronologies that can provide the temporal foundation for paleoclimate correlations between marine, terrestrial and ice-core records. One of the main challenges for building reliable radiocarbon-based chronologies in the marine realm is to estimate the regional marine radiocarbon reservoir age correction. Estimates of the local marine reservoir effect, ΔR, during the deglaciation can be obtained by 14C-independent dating methods such as synchronization to other well-dated archives. The cosmogenic radionuclide 10Be provides such a synchronization tool. Its atmospheric production rate is globally modulated by changes in the cosmic ray flux caused by changes in solar activity and geomagnetic field strength. The resulting variations in the meteoric fallout of10Be are recorded in sediments and ice cores and can thus be used for their synchronization.

In this study we use for the first time the authigenic 10Be/9Be record of a Laptev Sea sediment core and synchronize it to the 10Be records from absolutely dated ice cores. Based on the resulting absolute chronology, the ΔR  was then estimated for the Laptev Sea during the deglaciation. The deglacial estimate for the benthic ΔR value for the Laptev Sea is 345±60 14C years, corresponding to a marine reservoir age of 864±90 14C years. We discuss the obtained ΔR in comparison to modern ΔR estimates from the literature and its consequences for the age-depth model. Our refined age-depth model can be used as a reference for the Laptev Sea and the wider Siberian regions of the Arctic Ocean.    

How to cite: Nicolas, A., Mollenhauer, G., Malter, M., Wollenburg, J., and Adolphi, F.: Refining the age-depth model of a marine sediment record in the Laptev Sea using Beryllium-10, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17301, https://doi.org/10.5194/egusphere-egu24-17301, 2024.

EGU24-18258 | Posters on site | CL5.3

Advancing Quaternary Geochronology: Impact of Sample Preparation and Analytical Techniques on Natural Radioactive Dose Assessment in Stream Sediments 

Fernando Jimenez, Altug Hasozbek, Mathieu Duval, Josep M. Pares, M. Isabel Sarró-Moreno, Ana I. Barrado-Olmedo, Estefania Conde-Vila, Marta Fernández-Díaz, Jose Manuel Cobo, Martin Perez-Estebanez, and Javier Alonso-Garcia

Keywords: Geochronology, Sediment, Uranium, Thorium, Microwave Digestion, HR-ICP-MS

In Quaternary geochronology, accurately estimating natural radiation exposure is crucial for dating materials using Electron Spin Resonance (ESR) and Optically Stimulated Luminescence (OSL). Traditional methods like gamma and alpha spectrometry, despite their utility, are limited by sample size requirements and time inefficiency, especially in low-radiation contexts. This study explores the efficacy of Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and Plasma Mass Spectrometry (ICP-MS), including both Quadrupole (ICP-QMS) and High-Resolution (HR-ICP-MS), for analyzing uranium, thorium, and potassium concentrations in sediments.

We compared various acid digestion methods using standard hot-blocks, microwave digestion, and single cell microwave technology on Sediment Reference Materials (NIST BRS 8704, OREAS 24d). Potassium detection was more accurate with ICP-OES (96% precision) than ICP-QMS (80%). In contrast, HR-ICP-MS significantly outperformed ICP-QMS in measuring uranium and thorium (U and Th recoveries of 99% and 94% vs. 83% and 81%, respectively). Moreover, microwave-assisted digestion methods showed slight advantages in uranium and thorium recovery.

Our findings suggest that a four-acid microwave-assisted digestion, combined with potassium measurement via ICP-OES in radial mode and uranium and thorium quantification using HR-ICP-MS, offers the most accurate and time-efficient approach for natural dose determination in sediment dating. This methodology is particularly relevant for cave, river, and stream sediments even with expected low uranium levels.

How to cite: Jimenez, F., Hasozbek, A., Duval, M., Pares, J. M., Sarró-Moreno, M. I., Barrado-Olmedo, A. I., Conde-Vila, E., Fernández-Díaz, M., Cobo, J. M., Perez-Estebanez, M., and Alonso-Garcia, J.: Advancing Quaternary Geochronology: Impact of Sample Preparation and Analytical Techniques on Natural Radioactive Dose Assessment in Stream Sediments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18258, https://doi.org/10.5194/egusphere-egu24-18258, 2024.

EGU24-18925 | Posters on site | CL5.3

μGraphiline: a high-throughput, low-maintenance, fully automated 14C graphitization system 

Konrad Tudyka, Kacper Kłosok, Maksymilian Jedrzejowski, Andrzej Rakowski, Sławomira Pawełczyk, Alicja Ustrzycka, Sebastian Miłosz, and Aleksander Kolarczyk

μGraphiline is an innovative, fully automated graphitization system designed for radiocarbon dating using accelerator mass spectrometry. This system streamlines the conversion of samples into CO2 and subsequently into graphite. The standard configuration of μGraphiline is capable of preparing 24 targets daily, demonstrating its high throughput. It achieves a graphitization efficiency of over 95% for 1 mg graphite targets. μGraphiline also offers additional modules for stepped combustion, ramped pyrolysis, and oxidation, all of which can be operated at user-defined temperatures. Furthermore, its design ensures a low background and reproducibility, significantly enhancing the accuracy and reliability of radiocarbon measurements.

 

One of the notable advantages of the system is its low maintenance requirements. It operates efficiently without the need for working gasses such as helium (He), argon (Ar), oxygen (O2), explosive hydrogen (H2) or liquid nitrogen, which simplifies its operation and enhances safety. This feature, coupled with its modular design and high efficiency, virtually no cross-contamination between modules and samples makes μGraphiline an advanced solution for radiocarbon dating. Lastly, the system's repeatability and reliability are backed by reference materials measurements from the International Atomic Energy Agency, demonstrating good repeatability. 

 

This demonstrates μGraphiline's capability to deliver fast, consistent and accurate results, making it a valuable tool for various scientific and research applications.

How to cite: Tudyka, K., Kłosok, K., Jedrzejowski, M., Rakowski, A., Pawełczyk, S., Ustrzycka, A., Miłosz, S., and Kolarczyk, A.: μGraphiline: a high-throughput, low-maintenance, fully automated 14C graphitization system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18925, https://doi.org/10.5194/egusphere-egu24-18925, 2024.

EGU24-19089 | Posters on site | CL5.3

230Th/U and 234U/238U dating of cold-water corals: Approaching the disequilibrium theory 

Norbert Frank and the DCWC

U-series disequilibrium dating or more specifically 230Th/U - dating of cold-water corals is a major absolute chronological toolbox to study the evolution of coral reefs through time and to determine absolute time scales for climate proxies. Advances in multi-collector inductively coupled ion source mass spectrometry (MC-ICPMS) have continuously improved precision of Th and U isotopic measurements over the past decades thanks the development of new high ohmic resistors for Faraday cups. Consequently, isotopic measurements and absolute precision levels are in epsilon ranges for 234U/238U ratios and in the case of materials older than a few tens of thousands of years also for 230Th/238U ratios. To obtain accurate ages the corals isotope ratios need to evolve as a U series closed system and must be free of initial 230Th and non-carbonate materials. The latter being often traced using the natural most abundant 232Th isotope. Coral diagenesis, bio-erosion, residual ferromanganese coatings, recrystallization, and recoil displacement of U isotopes are known sources of age disturbances and U series open system behavior. Here, I want to advocate, however, that such cold-water corals can be ideal dating objects opening far reaching perspectives of marine climate science and for past ecosystem studies. Based on approx. 1200 coral ages and isotope ratios of reef-forming cold-water corals, which correspond to strict quality criteria, a perfect agreement with theoretical predictions of a closed U series system can be found. The resulting oceanic initial (234U/238U) activity ratio for the past 510 ka varies by at most 6.7 ‰ (2s) surrounding the mean of modern seawater and of all reconstructed values of 146.5 ‰ (HU1 reference material is assumed here to be in secular radioactive equilibrium). Consequently, the 234U/238U ratios may be used for dating of old cold-water corals to expand the dating range to more than 1.2 million years. Moreover, any significant deviation between closed system 234U/238U ages and 230Th/238U ages may be used to detect U series open - system behavior. Based on the combined age determination, more consistent chronologies can be derived for cold-water coral reefs beyond 350 ka and theoretically the quality of this archive has opened a path for absolutely dated marine climate proxy records since the Mid Pleistocene Transition.

How to cite: Frank, N. and the DCWC: 230Th/U and 234U/238U dating of cold-water corals: Approaching the disequilibrium theory, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19089, https://doi.org/10.5194/egusphere-egu24-19089, 2024.

EGU24-21472 | ECS | Posters on site | CL5.3

Lyoluminescence: a potential tool for dating evaporites up to the Middle-Pleistocene? 

Magdalena Biernacka and Sebastian Kreutzer

Lyoluminescence (LL) is light emission during the solvation of previously irradiated crystals in the liquid-solid interface (Atari, 1980). Our aim is the breakthrough development of lyoluminescence as a dating tool on halite (here: sodium chloride and potassium chloride) for application in Earth Sciences. The positive correlation between radiation dose and LL light emission makes crystal lattice defects viable natural ionizing radiation dosimeters. With a saturation dose of ~10 kGy (e.g. Atari et al., 1973) for sodium chloride dissolved in pure water and for realistic dose rates of ~4 Gy/ka (e.g., Han et al., 2014), the LL signal from salt minerals potentially may determine an age up to 2.5 Ma.
We hypothesize that LL, naturally observable in salt minerals, will allow dating the last recrystallization event significantly beyond the age limits of conventional luminescence-dating methods. In the past, the potential of halite as a material for optical luminescence dating had been suggested, e.g. Bailey et al., (2000); Zhang et al., (2005). However, LL may offer an additional luminescence-dating tool for routine use in geochronology but targeting the crystallization instead of heat or light exposure event. Moreover, it may enable tapping into different archives and subsurface processes where only the event of the last hydration is of interest.
In our contribution, we present the first basic design of a measurement prototype using 3D printing and preliminary experimental results of salts easily soluble in water.

References
Atari, N.A., 1980. Lyoluminescence mechanism of gamma and additively coloured alkali halides in pure water. Journal of Luminescence 21, 305–316. https://doi.org/10.1016/0022-2313(80)90009-5
Atari, N.A., Ettinger, K.V., Fremlin, J.H., 1973. Lyoluminescence as a possible basis of radiation dosimetry. Radiation Effects 17, 45–48. https://doi.org/10.1080/00337577308232596
Bailey, R.M., Adamiec, G., Rhodes, E.J., 2000. OSL properties of NaCl relative to dating and dosimetry. Radiation Measurements 32, 717–723. https://doi.org/10.1016/S1350-4487(00)00087-1
Han, W., Ma, Z., Lai, Z., Appel, E., Fang, X., Yu, L., 2014. Wind erosion on the north‐eastern Tibetan Plateau: constraints from OSL and U‐Th dating of playa salt crust in the Qaidam Basin. Earth Surf Processes Landf 39, 779–789. https://doi.org/10.1002/esp.3483
Zhang, J.F., Yan, C., Zhou, L.P., 2005. Feasibility of optical dating using halite. Journal of Luminescence 114, 234–240. https://doi.org/10.1016/j.jlumin.2005.01.009
 

How to cite: Biernacka, M. and Kreutzer, S.: Lyoluminescence: a potential tool for dating evaporites up to the Middle-Pleistocene?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21472, https://doi.org/10.5194/egusphere-egu24-21472, 2024.

GM3 – Spatial Methods and Analysis in Geomorphology

EGU24-1261 | Orals | GM3.1

Machine-learning based 3D point cloud classification and multitemporal change analysis with simulated laser scanning data using open source scientific software 

Bernhard Höfle, Ronald Tabernig, Vivien Zahs, Alberto M. Esmorís Pena, Lukas Winiwarter, and Hannah Weiser

AIM: We will present how virtual laser scanning (VLS), i.e., simulation of realistic LiDAR campaigns, can be key for applying machine/deep learning (ML/DL) approaches to geographic point clouds. Recent results will be shown for semantic classification and change analysis in multitemporal point clouds using exclusively open source scientific software.

MOTIVATION: Laser scanning is able to deliver precise 3D point clouds which have made huge progress in research in geosciences over the last decade. Capturing multitemporal (4D: 3D + time) point clouds enables to observe and quantify Earth surface process activities, their complex interactions and triggers. Due to the large size of 3D/4D datasets that can be captured by modern systems, automatic methods are required for point cloud analysis. Machine learning approaches applied to geographic point clouds, in particular DL, have shown very promising results for many different geoscientific applications [1,2].

METHODS & RESULTS: While new approaches for deep neural networks are rapidly developing [1], the bottleneck of sufficient and appropriate training data (typically annotated point clouds) remains the major obstacle for many applications in geosciences. Those data hungry learning methods depend on proper domain representation by training data, which is challenging for natural surfaces and dynamics, where there is high intra-class variability. Synthetic LiDAR point clouds generated by means of VLS, e.g., with the open-source simulator HELIOS++ [3], can be a possible solution to overcome the lack of training data for a given task. In a virtual 3D/4D scene representing the target surface classes, different LiDAR campaigns can be simulated, with all generated point clouds being automatically annotated. VLS software like HELIOS++ allows to simulate any LiDAR platform and settings for a given scene, which offers high potential for data augmentation and the creation of training samples tailored to specific applications. In recent experiments [1], purely synthetic training data could achieve similar performances to costly labeled training data from real-world acquisitions for semantic scene classification.

Furthermore, surface changes can be introduced to create dynamic VLS scenes (e.g., erosion, accumulation, movement/transport). Combining LiDAR simulation with automatic change analysis, such as offered by the open-source scientific software py4dgeo [5], enables to perform ML for change analysis in multitemporal point clouds [6]. Recent results show that rockfall activity mapping and classification for permanent laser scanning data can be successfully implemented by combining HELIOS++, py4dgeo and the open-source framework VL3D, which can be used for investigating various ML/DL approaches in parallel.

CONCLUSION: Expert domain knowledge (i.e., definition of proper 3D/4D scenes) and the power of AI can be closely coupled in VLS-driven ML/DL approaches to analyze 3D/4D point clouds in the geosciences. Open-source scientific software already offers all required components (HELIOS++, VL3D, py4dgeo). 

REFERENCES:

[1] Esmorís Pena, A. M., et al. (2024): Deep learning with simulated laser scanning data for 3D point cloud classification. ISPRS Journal of Photogrammetry and Remote Sensing. under revision.

[2] Winiwarter, L., et al. (2022): DOI: https://doi.org/10.1016/j.rse.2021.112772 

[3] HELIOS++: https://github.com/3dgeo-heidelberg/helios

[4] VL3D framework: https://github.com/3dgeo-heidelberg/virtualearn3d

[5] py4dgeo: https://github.com/3dgeo-heidelberg/py4dgeo

[6] Zahs, V. et al. (2023): DOI: https://doi.org/10.1016/j.jag.2023.103406

How to cite: Höfle, B., Tabernig, R., Zahs, V., Esmorís Pena, A. M., Winiwarter, L., and Weiser, H.: Machine-learning based 3D point cloud classification and multitemporal change analysis with simulated laser scanning data using open source scientific software, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1261, https://doi.org/10.5194/egusphere-egu24-1261, 2024.

EGU24-1640 | ECS | Posters on site | GM3.1

Automatic Classification of Surface Activity Types from Geographic 4D Monitoring Combining Virtual Laser Scanning, Change Analysis and Machine Learning 

Vivien Zahs, Bernhard Höfle, Maria Federer, Hannah Weiser, Ronald Tabernig, and Katharina Anders

We advance the characterization of landscape dynamics through analysis of point cloud time series by integrating virtual laser scanning, machine learning and innovative open source methods for 4D change analysis. We present a novel approach for automatic identification of different surface activity types in real-world 4D geospatial data using a machine learning model trained exclusively on simulated data.

Our method focuses on classifying surface activity types based on spatiotemporal features. We generate training data using virtual laser scanning of a dynamic coastal scene with artificially induced surface changes. Scenes with surface change are generated using geographic knowledge and the concept of 4D objects-by-change (4D-OBCs) [1, 2], which represent spatiotemporal subsets of the scene that exhibit change with similar properties. A realistic 3D scene modelling is essential for accurately replicating the dynamic nature of coastal landscapes, where morphological changes are driven by both natural processes and anthropogenic activities.

The Earth's landscapes exhibit complex dynamics, spanning large spatiotemporal scales, from high-mountain glaciers to sandy coastlines. The challenge lies in effectively detecting and classifying diverse surface activities with varying magnitudes, spatial extents, velocities, and return frequencies. Effective characterization of these dynamics is crucial for understanding the underlying environmental processes and their interplay with human activities. Supervised machine learning classification of surface activities from point cloud time series is challenging due to the limited availability of comprehensive and diverse real-world datasets for training and validation. Our approach combines virtual laser scanning with machine learning-based classification, enabling the generation of comprehensive training datasets covering the full spectrum of expected change patterns [3].

In our approach, the simulation of LiDAR point clouds is performed in the open-source framework HELIOS++ [4, 5]. HELIOS++ allows the flexible simulation of custom LiDAR campaigns with diverse acquisition modes and settings together with automatic annotations of artificially induced surface changes. We train a supervised machine learning model to classify synthetic 4D-OBCs into typical surface activity types of a sandy beach (e.g. dune erosion/accretion, sediment transport, etc.). Moreover, we investigate descriptors for 4D-OBCs, assessing their suitability for representing general types of surface activity (transferable between use cases) and types specific to particular surface processes.

We evaluate our model for 4D-OBC classification in terms of its capacity to discriminate surface activity types in a real-world dataset of a sandy beach in the Netherlands [6]. 4D-OBCs are extracted, classified into our target classes and validated with manually labelled reference data based on expert evaluation.

Our study showcases the efficacy of coupling virtual laser scanning, innovative open-source 4D change analysis methods, and machine learning for classifying natural surface changes [7]. Our findings not only contribute to advancing the understanding of landscape dynamics but also provide a promising approach to mitigating environmental challenges.

REFERENCES

[1] Anders et al. (2022): DOI: https://doi.org/10.5194/egusphere-egu22-4225

[2] py4dgeo: https://github.com/3dgeo-heidelberg/py4dgeo 

[3] Zahs et al. (2022): DOI: https://doi.org/10.1016/j.jag.2023.103406

[4] HELIOS++: https://github.com/3dgeo-heidelberg/helios

[5] Winiwarter et al. (2022): DOI: https://doi.org/10.1016/j.rse.2021.112772 

[6] Vos et al. (2022): DOI: https://doi.org/10.1038/s41597-022-01291-9

[7] CharAct4D: www.uni-heidelberg.de/charact4d

How to cite: Zahs, V., Höfle, B., Federer, M., Weiser, H., Tabernig, R., and Anders, K.: Automatic Classification of Surface Activity Types from Geographic 4D Monitoring Combining Virtual Laser Scanning, Change Analysis and Machine Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1640, https://doi.org/10.5194/egusphere-egu24-1640, 2024.

The acquisition of aerial photographs for cartographic applications started in the 1930s, and more intensively after World War II. Such old, often panchromatic, imagery offers metre to sub-metre scale spatial resolution over landscapes that have significantly evolved over the decades. Before the appearance of the first digital aerial camera systems at the end of the 20th Century, surveys were performed with analogue metric cameras, with images acquired on films or glass plates and, next, developed on photo papers. In Europe and North America, several institutions hold unique collections of historical aerial photographs having local, national and, in some cases, colonial coverages. They represent invaluable opportunities for environmental studies, allowing the comparison with today’s land use land cover, and the analysis of long-term surface displacements.

Initially, the photogrammetric processing of analogue aerial photographs would require expensive equipment, specialised operators, and significant processing time. Thanks to the digital revolution of the past two decades and the development of modern digital photogrammetric approaches, the processing of this type of image datasets has become less cumbersome, time consuming and expensive, at least in theory. In practice, this is more complex, with digitising and processing issues related to the ageing and quality of conservation of the aerial photographs, the potential distortions created during the digitising process, and the lack of ancillary data, such as, flight plans, and camera calibration reports. The limited overlap between photographs, typically 60 % and 10-20 %, along-track and across-track, respectively, make their processing with Structure-from-Motion Multi-View Stereo (SfM-MVS) photogrammetry poorly reliable to accurately reconstruct the topography and orthorectify the images. Given the fact that some collections reach up to millions of historical aerial photographs, the digitising, pre-processing, and photogrammetric processing of these images remain a challenge that must be properly tackle if we would like to ensure their preservation and large-scale valorisation.

In the present work, we describe the mass-digitising, digital image pre-processing and photogrammetric processing approaches implemented at the Royal Museum for Central Africa (RMCA, Belgium) to preserve and valorise the collection of >320,000 historical aerial photographs conserved in this federal institution. This imagery was acquired between the 1940’s and the 1980’s, over Central Africa, and mostly D.R. Congo, Rwanda and Burundi. For the digitising, a system of parallelized flatbed scanners controlled by a Linux computer and a self-developed software allows speeding-up the scanning of the entire collection in only few years. A series of Python scripts were developed and combined to allow a swift pre-processing that prepare and optimise the digitised images for photogrammetric processing. Finally, a SfM-MVS photogrammetric approach adapted to historical aerial photos is used. Examples of application for geo-hydrological hazards studies in the western branch of the East African Rift are shown.

How to cite: Smets, B., Dille, A., Dewitte, O., and Kervyn, F.: Digitising, pre-processing and photogrammetric processing of historical aerial photographs for the production of high resolution orthomosaics and the study of geohazards, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2356, https://doi.org/10.5194/egusphere-egu24-2356, 2024.

EGU24-4399 | ECS | Posters on site | GM3.1

Evaluating the efficacy of multitemporal TLS and UAS surveys for quantifying wind erosion magnitudes of sand dune topography 

László Bertalan, Gábor Négyesi, Gergely Szabó, Zoltán Túri, and Szilárd Szabó

Wind erosion constitutes a prominent land degradation process in regions of Hungary characterized by low annual precipitation. In these areas, it poses significant challenges to agricultural productivity and adversely impacts soil and environmental quality. Presently, human activities exert a more pronounced influence on the endangered areas of Hungary in comparison to climate-related factors. It is noteworthy that the wind erodibility of Hungarian soils not only poses a soil conservation challenge but also gives rise to economic ramifications, such as nutrient loss, as well as environmental and human health concerns. Within agricultural landscapes, wind erosion contributes to the removal and transportation of the finest and biologically active soil fractions, rich in organic matter and nutrients.

High-resolution topographic surveys have become integral for assessing volumetric changes in sand dune mobility and mapping wind erosion. While Unmanned Aerial Systems (UAS) surveys have been extensively employed for erosion rates exceeding the decimeter scale, Terrestrial Laser Scanning (TLS) surveys have demonstrated efficiency in capturing more extensive negative erosional forms, even in a vertical orientation. To enhance the field of view, a mounting framework can be implemented to elevate the TLS. However, determining centimeter-scale material displacement in flat terrain conditions remains challenging and requires an increased number of scanning positions.

To identify optimal settings for surveying centimeter-scale wind erosion magnitudes, we conducted combined multi-temporal TLS and UAS surveys at the Westsik experimental site near Nyíregyháza during the spring of 2023. This site features dune topography with a height of 6 meters. Our investigations encompassed various UAS image acquisition modes, involving different flight altitudes and camera settings, utilizing a DJI Matrice M210 RTK v2 drone and a Zenmuse X7 24 mm lens. Additionally, we generated diverse point clouds through various scanning scenarios using a Trimble X7 TLS device. In the data processing phase, we explored multiple co-registration algorithms to address the challenge of larger Root Mean Square Error (RMSE) in Digital Terrain Models (DTMs) from UAS Structure from Motion (SfM) compared to the actual wind erosion rates.

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The research is supported by the NKFI K138079 project.

How to cite: Bertalan, L., Négyesi, G., Szabó, G., Túri, Z., and Szabó, S.: Evaluating the efficacy of multitemporal TLS and UAS surveys for quantifying wind erosion magnitudes of sand dune topography, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4399, https://doi.org/10.5194/egusphere-egu24-4399, 2024.

EGU24-5142 | Posters on site | GM3.1 | Highlight

Four nationwide Digital Surface Models from airborne historical stereo-images 

Christian Ginzler, Livia Piermattei, Mauro Marty, and Lars T. Waser

Historical aerial images, captured by film cameras in the previous century, have emerged as valuable resources for quantifying Earth's surface and landscape changes over time. In the post-war period, historical aerial images were often acquired to create topographic maps, resulting in the acquisition of large-scale aerial photographs with stereo coverage. Using photogrammetric techniques on stereo-images enables extracting 3D information to reconstruct Digital Surface Models (DSMs), and orthoimages.

This study presents a highly automated photogrammetric approach for generating nationwide DSMs for Switzerland at 1 m resolution using aerial stereo-images acquired between 1979 and 2006. The 8-bit scanned images, with known exterior and interior orientation, were processed using BAE Systems' SocetSet (v5.6.0) with the "Next-Generation Automatic Terrain Extraction" (NGATE) package for DSM generation. The primary objective of the study is to derive four nationwide DSMs for the epochs 1979-1985, 1985-1991, 1991-1998, and 1998-2006. The study assesses DSM quality in terms of vertical accuracy and completeness of image matching across different land cover types, with a focus on forest dynamics and management research.

The elevation accuracy of the generated DSMs was assessed using two reference datasets. Firstly, the elevation differences between a nationwide reference Digital Terrain Model (DTM - swissAlti3d 2017 by Swisstopo) and the generated DSMs were calculated on points classified as "sealed surface". Secondly, elevation values of the DSMs were compared to approximately 500 independent geodetic points distributed across the country. Six study areas were chosen to assess completeness, and it was calculated as the percentage of successfully matched points to the potential total number of matched points within a predefined area. This assessment was conducted for six land cover classes based on the land cover/land-use statistics dataset from the Federal Office of Statistics.

Across the entire country, the median elevation accuracy of the DSMs on sealed points ranges between 0.28 to 0.53 m, with a Normalized Median Absolute Deviation (NMAD) of around 1 m (maximum 1.41 m) and an RMSE of a maximum of 3.90 m. The elevation differences between geodetic points and DSMs show higher accuracy, with a median value of a maximum of 0.05 m and an NMAD smaller than 1 m. Completeness results reveal mean completeness between 64 % to 98 % for the classes "glacial and perpetual snow" and "sealed surfaces," respectively and 93 % specifically for the “closed forest” class.

This work demonstrates the feasibility of generating accurate DSM time series (spanning four epochs) from historical scanned images for the entire Switzerland in a highly automated manner. The resulting DSMs will be available upon publication, providing an excellent opportunity to detect major surface changes, such as forest dynamics.

How to cite: Ginzler, C., Piermattei, L., Marty, M., and Waser, L. T.: Four nationwide Digital Surface Models from airborne historical stereo-images, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5142, https://doi.org/10.5194/egusphere-egu24-5142, 2024.

EGU24-5670 | ECS | Posters on site | GM3.1

Enhancing 3D Feature-based Landslide Monitoring Efficiency by Integrating Contour Lines in Laser Scanner Point Clouds 

Kourosh Hosseini, Jakob Hummelsberger, Daniel Czerwonka-Schröder, and Christoph Holst

Landslides are a pervasive natural hazard with significant societal and environmental impacts. In addressing the critical need for accurate landslide detection and monitoring, our previous research introduced a feature-based monitoring method enhanced by histogram analyses, straddling a middle ground between point-based and point cloud-based methods. This paper expands upon that foundation, introducing an innovative contour line extraction technique from various epochs to precisely identify areas prone to deformation. This refined focus diverges from conventional methodologies that analyze entire point clouds. By applying on regions where contour lines do not match, indicating potential ground movement, we significantly elevate the efficiency and precision of our feature-based monitoring system.

 

One of the principal challenges of feature-based monitoring is managing a substantial number of outliers. Our prior research tackled this issue effectively by integrating feature tracking with histogram analysis, thereby filtering these outliers from the final results. However, the process of extracting features from each patch and matching them with corresponding patches from different epochs was time-intensive.

 

The incorporation of contour line extraction into our workflow, using high-resolution laser scanner data, allows for a more focused and efficient analysis. We can now identify and analyze areas of landscape alteration with greater accuracy. This approach limits the application of feature tracking and histogram analysis to these critical areas, thus streamlining the process and significantly reducing computational demands. This focused methodology not only accelerates data processing but also enhances the accuracy of landslide predictions.

 

Our findings indicate a substantial improvement in the efficiency of landslide monitoring methods. This methodology represents a promising advancement in geospatial analysis, particularly for environmental monitoring and risk management in regions susceptible to landslides. This research contributes to the ongoing efforts to develop more effective, efficient, and accurate approaches to landslide monitoring, ultimately aiding in better informed and timely decision-making processes for hazard mitigation and risk management.

How to cite: Hosseini, K., Hummelsberger, J., Czerwonka-Schröder, D., and Holst, C.: Enhancing 3D Feature-based Landslide Monitoring Efficiency by Integrating Contour Lines in Laser Scanner Point Clouds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5670, https://doi.org/10.5194/egusphere-egu24-5670, 2024.

EGU24-5674 | ECS | Orals | GM3.1

Piecewise-ICP: Efficient Registration of 4D Point Clouds for Geodetic Monitoring 

Yihui Yang, Daniel Czerwonka-Schröder, and Christoph Holst

The permanent terrestrial laser scanning (PLS) system has opened the possibilities for efficient data acquisition with high-temporal and spatial resolution, thus allowing for improved capture and analyses of complex geomorphological changes on the Earth's surface. Accurate georeferencing of generated four-dimensional point clouds (4DPC) from PLS is the prerequisite of the following change analysis. Due to the massive data volume and potential changes between scans, however, efficient, robust, and automatic georeferencing of 4DPC remains challenging, especially in scenarios lacking signalized and reliable targets. This georeferencing procedure can be typically realized by designating a reference epoch and registering all other scans to this epoch. Addressing the challenges in targetless registration of topographic 4DPC, we propose a simple and efficient registration method called Piecewise-ICP, which first segments point clouds into piecewise patches and aligns them in a piecewise manner.

Assuming the stable areas on monitored surfaces are locally planar, supervoxel-based segmentation is employed to generate small planes from adjacent point clouds. These planes are then refined and classified by comparing defined correspondence distances to a monotonically decreasing distance threshold, thus progressively eliminating unstable planes in an efficient iterative process as well as preventing local minimization in the ICP process. Finally, point-to-plane ICP is performed on the centroids of the remaining stable planes. We introduce the level of detection in change analysis to determine the minimum distance threshold, which mitigates the influence of outliers and deformed areas on registration accuracy. Besides, the spatial distribution of empirical registration uncertainties on registered point clouds is derived based on the variance-covariance propagation law.

Our registration method is demonstrated on two datasets: (1) Synthetic point cloud time series with defined changes and transformation parameters, and (2) a 4DPC dataset from a PLS system installed in the Vals Valley (Tyrol, Austria) for monitoring a rockfall. The experimental results show that the proposed algorithm exhibits higher registration accuracy compared to the existing robust ICP variants. The real-time capability of Piecewise-ICP is significantly improved owing to the centroid-based point-to-plane ICP and the efficient iteration process.

How to cite: Yang, Y., Czerwonka-Schröder, D., and Holst, C.: Piecewise-ICP: Efficient Registration of 4D Point Clouds for Geodetic Monitoring, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5674, https://doi.org/10.5194/egusphere-egu24-5674, 2024.

EGU24-5757 | Posters on site | GM3.1

Arctic puzzle: pioneering a shrimp habitat model in topographically complex Disko Bay (West Greenland) 

Diana Krawczyk, Tobias Vonnahme, Ann-Dorte Burmeister, Sandra Maier, Martin Blicher, Lorenz Meire, and Rasmus Nygaard

Our study focuses on the geologically, topographically, and oceanographically complex region of Disko Bay in West Greenland. Disko Bay is also considered a marine biodiversity hotspot in Greenland. Given the impact of commercial fishing on seafloor integrity in the area, seafloor habitats studies are crucial for sustainable use of marine resources. One of the key fishery resources in Greenland, as well as in the North Atlantic Ocean, is northern shrimp.

In this study we analyzed multiple (1) monitoring datasets from 2010 to 2019, including data from shrimp and fish surveys, commercial shrimp fishery catches, satellite chlorophyll data, and (2) seafloor models, encompassing high-resolution (25 x 25 m) multibeam data with a low-resolution (200 x 200 m) IBCAO grid. Using multivariate regression analysis and spatial linear mixed-effect model we assessed the impact of physical (water depth, bottom water temperature, sediment type), biological (chlorophyll a, Greenland halibut predation), and anthropogenic factors (shrimp fishery catch and effort) on shrimp density in the area. The resulting high-resolution predictive model of northern shrimp distribution in Disko Bay is the first model of this kind developed for an Arctic area.

Our findings reveal that shrimp density is significantly associated with static habitat factors, namely sediment type and water depth, explaining 34% of the variation. The optimal shrimp habitat is characterized by medium-deep water (approximately 150-350 m) and mixed sediments, primarily in the north-eastern, south-eastern, and north-western Disko Bay. This pioneering study highlights the importance of seafloor habitat mapping and modeling, providing fundamental geophysical knowledge necessary for long-term sustainable use of marine resources in Greenland.

The developed high-resolution model contributes to a better understanding of detailed patterns in northern shrimp distribution in the Arctic, offering valuable insights for stock assessments and sustainable fishery management. This novel approach to seafloor habitat mapping supports the broader goal of ensuring the responsible utilization of marine resources, aligning with principles of environmental conservation and fisheries management. Our work serves as a foundation for ongoing efforts to balance economic interests with the preservation of marine ecosystems, fostering a harmonious coexistence between human activities and the fragile Arctic environment.

How to cite: Krawczyk, D., Vonnahme, T., Burmeister, A.-D., Maier, S., Blicher, M., Meire, L., and Nygaard, R.: Arctic puzzle: pioneering a shrimp habitat model in topographically complex Disko Bay (West Greenland), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5757, https://doi.org/10.5194/egusphere-egu24-5757, 2024.

EGU24-10361 | ECS | Orals | GM3.1

A Time-Series Analysis of Rockfall Evolution in a Coastal Region Using Remote Sensing Data 

Aliki Konsolaki, Emmanuel Vassilakis, Evelina Kotsi, Michalis Diakakis, Spyridon Mavroulis, Stelios Petrakis, Christos Filis, and Efthymios Lekkas

The evolution of technology, particularly the integration of Unmanned Aerial Systems (UAS), earth observation datasets, and historical data such as aerial photographs, stand as fundamental tools for comprehending and reconstructing surface evolution and potential environmental changes. In addition, the active geodynamic phenomena in conjunction with climate crisis and the increasing frequency of extreme weather phenomena can cause abrupt events such as rockfalls and landslides, altering completely the morphology on both small and large scales.

This study deals generally with the temporal evolution of landscapes and specifically focuses on the detection and quantification of a significant rockfall event that occurred at Kalamaki Beach on Zakynthos Island, Greece – a very popular summer destination. Utilizing UAS surveys conducted in July 2020 and July 2023, this research revealed a rockfall that has significantly altered the coastal morphology. During this period, two severe natural phenomena occurred, one of which could potentially be the cause of this rockfall event. Initially, the Mediterranean hurricane (‘medicane’) ‘Ianos’ made landfall in September 2020, affecting a large part of the country including the Ionian Islands. The result was severe damage to property and infrastructures, along with human casualties, induced by intense precipitation, flash flooding, strong winds, and wave action. Second, in September of 2022, an ML=5.4 earthquake struck between Cephalonia and Zakynthos Islands in the Ionian Sea, triggering considerable impact in both islands. The study employs satellite images postdating these natural disasters, to detect the source of the rockfall in Kalamaki Beach. Additionally, historical analog aerial images from 1996 and 2010 were used as assets for understanding the surface’s evolution. For the quantitative analysis, we applied 3D semi-automated change detection techniques such as the M3C2 algorithm, to estimate the volume of the rockfall.

The results provide insights into the complex interplay between natural disasters and geological processes, shedding light on the dynamic nature of landscapes and the potential implications for visitor-preferred areas.

This research not only contributes to our understanding of landscape evolution but also underscores the importance of integrating modern and historical datasets to decipher the dynamic processes shaping the Earth's surface. The methodology proposed, serves as a valuable approach for assessing and managing geological hazards in coastal regions affected by both climatic events and geodynamic activities.

How to cite: Konsolaki, A., Vassilakis, E., Kotsi, E., Diakakis, M., Mavroulis, S., Petrakis, S., Filis, C., and Lekkas, E.: A Time-Series Analysis of Rockfall Evolution in a Coastal Region Using Remote Sensing Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10361, https://doi.org/10.5194/egusphere-egu24-10361, 2024.

EGU24-10373 | Orals | GM3.1

A database for ancillary information of three-dimensional soil surface microtopography measurements. 

Kossi Nouwakpo, Anette Eltner, Bernardo Candido, Yingkui Li, Kenneth Wacha, Mary Nichols, and Robert Washington-Allen

Understanding the complex processes occurring at the soil surface is challenging due to the intricate spatial variability and dynamic nature of these processes. An effective tool for elucidating these phenomena is three-dimensional (3D) reconstruction, which employs advanced imaging technologies to create a comprehensive representation of the soil surface at high spatial resolution, often at the mm-scale. Three-dimensional reconstruction techniques are increasingly available to scientists in the fields of soil science, geomorphology, hydrology, and ecology and many studies have employed these novel tools to advance understanding of surface processes. Much of the data being collected in these studies are however not interoperable, i.e., 3D data from one study may not be directly combined with 3D data from other studies thus limiting the ability of researchers to advance process understanding at a broader scope. The limited interoperability of existing data is due in part to the fact that 3D surface reconstruction data are influenced by many factors including experimental conditions, intrinsic soil properties and accuracy and precision limits of the 3D reconstruction technique used. These ancillary data are crucial to any broad-scope efforts that leverage the increasing number of 3D datasets collected by scientists across disciplines, geographic regions, and experimental conditions. We have developed a relational database that archives and serves ancillary data associated with published high-resolution 3D data representing soil surface processes. This presentation introduces the structure of the database with its required and optional variables. We also provide analytics on the currently available records in the database and discuss potential applications of the database and future developments.

How to cite: Nouwakpo, K., Eltner, A., Candido, B., Li, Y., Wacha, K., Nichols, M., and Washington-Allen, R.: A database for ancillary information of three-dimensional soil surface microtopography measurements., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10373, https://doi.org/10.5194/egusphere-egu24-10373, 2024.

EGU24-11949 | ECS | Posters on site | GM3.1

Employng satellite immagery interpretation tools to detect land-use land-change dynamics in Italian historical rural landscapes 

Virginia Chiara Cuccaro, Claudio Di Giovannantonio, Giovanni Pica, Luca Malatesta, and Fabio Attorre

Rural landscapes inherited from the past are marked by a strong interaction between man and nature, a relationship rooted in a long history that testifies to the importance of the landscape as one of the most historically representative expressions of a country's cultural identity.

In this broad context, olive groves markedly characterize the agricultural landscape of many European rural areas, particularly in the Mediterranean region. Along with other rural landscapes, they form a semi-natural environment that can contribute to biodiversity conservation, soil protection and ecosystem resilience.

In addition to the global increase in temperatures, the main threats affecting these agrarian landscapes include the abandonment of traditional practices and the intensification of cultivation through the installation of irregular, intensive and overly dense planting beds.

The Land Cover classification and change-detection can provide useful indications for the restoration, conservation, and enhancement of olive groves

The objective of this work was to identify , rural landscapes in the Lazio region with characteristics of historical interest and determine their level of conservation. In particular, it was investigated the olive landscape of Cures (historic province of Sabina) trough a multi-temporal analysis of literature and cartographic information (e.g. orthophotos from the Italian Aeronautical Group flight of 1954)

The technique concerns the VASA (Historical Environmental Assessment) methodology, which allows the temporal evaluation of a given landscape and can inform on how agricultural practices and land use have changed over time.

Softwares  Collect Earth and Google Earth were employed to manipulate the historical series of high-resolution satellite images and implement photointerpretation. The coverage of identitied land units  was then estimated to address the configuration of the target landscape.

Landscape evolution over time was achieved by overlaying the 1954 and 2022 land use polygons, resulting in a merging database, in which an evolutionary dynamic was associated with each land use change.

The approach generated in-depth insights on the significant elements of the CURES olive landscape and informed on the dynamics of the area in relation to the risk of their disappearance, making it possible to identify what are the "landscape emergencies," i.e., the land uses that have seen the most̀ reduction in their area.

The methodologies employed have proven reliability in improving the knowledge ng target landscapes.  It might be useful to promote  sustainable agricultural practices for better preservation and management of rural environments so that cultural traditions can be preserved as well, and the environmental balance of the agrarian land can be maintained.

How to cite: Cuccaro, V. C., Di Giovannantonio, C., Pica, G., Malatesta, L., and Attorre, F.: Employng satellite immagery interpretation tools to detect land-use land-change dynamics in Italian historical rural landscapes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11949, https://doi.org/10.5194/egusphere-egu24-11949, 2024.

EGU24-12105 | ECS | Orals | GM3.1 | Highlight

Unleashing the archive of aerial photographs of Iceland, 1945-2000. Applications in geosciences  

Joaquín M. C. Belart, Sydney Gunnarson, Etienne Berthier, Amaury Dehecq, Tómas Jóhannesson, Hrafnhildur Hannesdóttir, and Kieran Baxter

The archive of historical aerial photographs of Iceland consists of ~140,000 vertical aerial photographs acquired between the years 1945 and 2000. It contains an invaluable amount of information about human and natural changes in the landscape of Iceland. We have developed a series of automated processing workflows for producing accurate orthomosaics and Digital Elevation Models (DEMs) from these aerial photographs, which we’re making openly available in a data repository and a web map visualization service. The workflow requires two primary inputs: a modern orthomosaic to automatically extract Ground Control Points (GCPs) and an accurate DEM for a fine-scale (sub-meter) alignment of the historical datasets. We evaluated the accuracy of the DEMs by comparing them in unchanged terrain against accurate recent lidar and Pléiades-based DEMs, and we evaluated the accuracy of the orthomosaics by comparing them against Pléiades-based orthomosaics. The data are becoming available at https://loftmyndasja.lmi.is/. To show the potential applications of this repository, we present the following showcases where these data reveal significant changes the landscape in Iceland in the past 80 years: (1) volcanic eruptions (Askja 1961, Heimaey 1973 and the Krafla eruptions, 1975-1984), (2) decadal changes of Múlajökull glacier from 1960-2023, (3) Landslides (Steinsholtsjökull 1967, Tungnakvíslarjökull 1945-present) and (4) coastal erosion (Surtsey island).

How to cite: Belart, J. M. C., Gunnarson, S., Berthier, E., Dehecq, A., Jóhannesson, T., Hannesdóttir, H., and Baxter, K.: Unleashing the archive of aerial photographs of Iceland, 1945-2000. Applications in geosciences , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12105, https://doi.org/10.5194/egusphere-egu24-12105, 2024.

EGU24-14087 | ECS | Posters on site | GM3.1

A point-cloud deep learning model based on RGB-D images: Application of riverbed grain size survey 

Bo Rui Chen and Wei An Chao

The water level and discharge of river are crucial parameters to understand the variance in riverbed scour. The detail behavior of scouring can be studied by the hydraulic simulation. The grain-size distribution of riverbed is also one of crucial parameter for modeling. Thus, how to investigate the grain-size of riverbed efficiently and swiftly is the urgent issue. However, the conventional measurement methods including Wolman counts (particles sampled at a fixed interval) which are a long and laborious task cannot survey the grain-size efficiently in the large area. In recent years, with an advantage of image segmentation and recognition has been applied to the investigation of grain-size, for example, capturing images through UAV and generating orthoimage is one of commonly used image technique. Although above the method can investigate the grain-size in the large area, it does not provide the information in the field immediately. Hence, a recent study developed the low-cost portable scanner to obtain the information of grain-size distribution in the field. However, the calibrating parameters of camera (e.g., height camera capture) are necessary before survey, and the uncertainties in calculation of image resolution will significantly affect the accuracy of grain-size analysis. Therefore, this study provides the additional algorithm to analyze the grain-size by using RGB-D image as inputs. The application of RGB-D can be categorized into two-dimensional (2D) and three-dimensional (3D) spaces. In a case of 2D, it integrates depth information with traditional RGB image processing to separate the grain-size of riverbed from the background (e.g., bottomland). Furthermore, depth information is also applied for grain-size edge detection. In a case of 3D, the collected RGB-D image information is transformed into point cloud data, then extract 3D features of grain particle by Deep learning, specifically PointNet. Our study demonstrates that clustering of 3D features can achieve the automatic identification of particle. The grain-size of particle can also be estimated by fitting 3D ellipsoid geometry. In the end, results show the grain-size distribution curves with the RGB、RGB-D、PointNet recognition, and compare with the true observations. 3D image information provides the cloud points of grain object, leading the possibility of estimating the 3D geometric morphology of the object. Our study successfully overcomes the limitations of conventional RGB-based process, which could only capture size and shape information in 2D planar. RGB-D-based image recognition, is an innovative technique for the hydraulic problem, not only advances survey efficiency but also addresses the intricate steps required for field investigations.

 

Key words: Riverbed grain size, RGB-D image, Point cloud, Deep Learning

How to cite: Chen, B. R. and Chao, W. A.: A point-cloud deep learning model based on RGB-D images: Application of riverbed grain size survey, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14087, https://doi.org/10.5194/egusphere-egu24-14087, 2024.

EGU24-14680 | Orals | GM3.1

Using current 3D point clouds as a tool to infer on past geomorphological processes 

Reuma Arav, Sagi Filin, and Yoav Avni

Examining deposition and erosion dynamics during the late Pleistocene and Holocene is crucial for gaining insights into soil development, erosion, and climate fluctuations. This urgency intensifies as arable lands face escalating degradation rates, particularly in arid and semi-arid environments. Nevertheless, as the destructive nature of erosional processes allows only for short-term studies, long-term processes in these regions are insufficiently investigated. In that respect, the ancient agricultural installations in the arid Southern Levant offer distinctive and undisturbed evidence of long-term land dynamics. Constructed on a late Pleistocene fluvial-loess section during the 3rd-4th CE and abandoned after 600-700 years, these installations record sediment deposition, soil formation, and erosion processes. The challenge is to trace and quantify these processes based on their current state. In this presentation, we demonstrate how the use of 3D point cloud data enables us to follow past geomorphological processes and reconstruct trends and rates. Utilizing data gathered in the immediate vicinity of the UNESCO World Heritage Site of Avdat (Israel), we illustrate how these point clouds comprehensively document the history of soil dynamics in the region. This encompasses the initial erosion phase, subsequent soil aggradation processes resulting from anthropogenic interruption, and the ongoing reinstated erosion. The unique setting, which uncovers the different fluvial sections, together with the detailed 3D documentation of the site, allows us to develop means for the reconstruction of the natural environment in each of the erosion/siltation stages. Therefore, by utilizing the obtained data, we can recreate the site during its developmental stages till the present day. Furthermore, we utilize terrestrial laser scan data sequence acquired in the past decade (2012-2022) to compute current erosion rates. These are then used to determine past rates, enabling inferences about the climatic conditions prevalent in the region over the last millennium. The in-depth examination of these installations provides valuable insights into approaches for soil conservation, sustainable desert living, and strategies to safeguard world-heritage sites subjected to soil erosion. As the global imperative to address soil erosion intensifies, this case study gains heightened relevance.

How to cite: Arav, R., Filin, S., and Avni, Y.: Using current 3D point clouds as a tool to infer on past geomorphological processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14680, https://doi.org/10.5194/egusphere-egu24-14680, 2024.

EGU24-15439 | ECS | Orals | GM3.1 | Highlight

Utilizing historical aerial imagery for change detection in Antarctica 

Felix Dahle, Roderik Lindenbergh, and Bert Wouters

Our research explores the potential of historical images of Antarctica for change detection in 2D and 3D. We
make use of the TMA Archive, a vast collection of over 330,000 black and white photographs of Antarctica taken
between 1940 to 1990. These photographs, available in both nadir and oblique, are systematically captured
from airplanes along flight paths and offer an unprecedented historical snapshot of the Antarctic landscape.
Detecting changes between past and present observations provides a unique insight into the long-term impact
of changing climate conditions on Antarctica’s glaciers, and their dynamical response to ice shelf weakening and
disintegration. Furthermore, it provides essential validation data for ice modelling efforts, thereby contributing
to reducing the uncertainties in future sea level rise scenarios.

In previous work, we applied semantic segmentation to these images [1]. By employing classes derived from this
segmentation, we can focus on features of interest and exclude images with extensive cloud coverage, enhancing
the accuracy of change analyses. In the next step, we geo-referenced the images: We assigned the images to
their actual position, scaled them to their true size, and aligned them with their genuine orientation. This
presents novel opportunities for detecting environmental changes in Antarctica, particularly in the retreat of
glaciers and sea ice.

Furthermore, the combination of these two steps allows for the first time a large scale reconstruction of these
images in 3D through Structure from Motion (SfM) techniques, which enables further multidimensional change
detection by comparing historical 3D models with contemporary ones. Due to the high number of images,
manual processing is impractical. Therefore, we are investigating the possibility of automatizing this process.
We utilize MicMac, an open-source software developed by the French National Geographic Institute for the
creation of the 3D models. Its high modularity allows for necessary customizations to automate the SfM
process effectively. Further adaptions are required due to the poor image quality and monotonous scenery. By
comparing historical 3D models with contemporary ones, we can assess alterations in elevation due to factors
such as glacial isostatic adjustments and glacier retreat.

We have already employed geo-referenced images for detecting changes on the Antarctic peninsula and are in the
process of creating initial 3D models. Our presentation will outline the workflow we developed for this process
and showcase the initial results of the change detection, both in 2D and 3D formats. This approach marks a
significant step in understanding and visualizing the impacts of climate change on the Antarctic landscape.

Acknowledgements
This work was funded by NWO-grant ALWGO.2019.044.

References
[1] F. Dahle, R. Lindenbergh, and B. Wouters. Revisiting the past: A comparative study for semantic segmen-
tation of historical images of Adelaide Island using U-nets. ISPRS Open Journal of Photogrammetry and
Remote Sensing, 11:100056, 2024.

How to cite: Dahle, F., Lindenbergh, R., and Wouters, B.: Utilizing historical aerial imagery for change detection in Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15439, https://doi.org/10.5194/egusphere-egu24-15439, 2024.

EGU24-15896 | Orals | GM3.1

Classification and segmentation of 3D point clouds to survey river dynamics and evolution  

Laure Guerit, Philippe Steer, Paul Leroy, Dimitri Lague, Dobromir Filipov, Jiri Jakubinsky, Ana Petrovic, and Valentina Nikolova

3D data for natural environments are now widely available via open data at large scales (e.g., OpenTopography) and can be easily acquired on the field by terrestrial LiDAR scan (TLS) or by structure-from-motion (SFM) from camera or drone imagery. The 3D description of landscapes gives access to an unprecedented level of details that can significantly change the way we look at, understand, and study natural systems. Point clouds with millimetric resolution even allow to go further and to investigate the properties of riverbed sediments: dedicated algorithms are now able to extract the sediment size distribution or their spatial orientation directly from the point cloud. 

Such data can be real game changers to study for example torrential streams prone to flash floods or debris flows. Such events are usually associated with heavy rainfall events, while conditioned by the geomorphological state of a stream (e.g., channel geometry, vegetation cover). The size and the shape of the grains available in the river also strongly influence river erosion and sediment transport during a flood. 3D data can thus help to design prevention and mitigation measures in streams prone to torrential events. 

However, it is not straightforward to go from data acquisition to river erosion or to grain-size distributions. Indeed, isolating and classifying the areas of interest can be complex and time-consuming. This can be done manually, at the cost of time and absence of reproducibility. We rather take advantage of state-of-the-art classification method (3DMASC) to develop a general classifier for point clouds in fluvial environments designed to identify five classes usually found in such settings: coarse sediments, sand, bedrock, vegetation and human-made structures. We also improved the G3Point sediment segmentation algorithm, developed by our team, to make it more efficient and straightforward to use in the CloudCompare software, which is dedicated to point cloud visualization and analysis. We apply it to the coarse sediments class identified by 3DMASC to provide a more accurate description of grain size and orientation. We also make a profit of the sand class to estimate its relative areal distribution that can then be compared to the coarse sediment class. This provides valuable information about the type of flows which are also important for planning torrential events mitigation measures.

We illustrate this combined approach with two field examples. The first one is based on SFM data acquired along streams prone to torrential events in Bulgaria and in Serbia where we documented sediment size and orientation. The second one is based on TLS data acquired along a bedrock river in France that experienced a major flood which induced dramatic changes in the river morphology. 

This work has been partially funded by PHC Danube n° 49921ZG/ n° KP-06-Danube/5, 14.08.2023 (National Science Fund, Bulgaria) and the H2020 European Research Council (grant no. 803721). 

How to cite: Guerit, L., Steer, P., Leroy, P., Lague, D., Filipov, D., Jakubinsky, J., Petrovic, A., and Nikolova, V.: Classification and segmentation of 3D point clouds to survey river dynamics and evolution , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15896, https://doi.org/10.5194/egusphere-egu24-15896, 2024.

EGU24-16939 | ECS | Posters on site | GM3.1 | Highlight

Integrating structure-from-motion photogrammetry with 3D webGIS for risk assessment, mapping and monitoring of coastal area changes in the Maltese archipelago 

Emanuele Colica, Daniel Fenech, Christopher Gauci, and George Buhagiar

The Maltese coasts extend for approximately 273km, representing a notable resource for the country and of one of its pillar economies, the tourism sector. Natural processes and anthropic interventions continue to threaten Malta's coastal morphology, shaping its landscape and triggering soil erosion phenomena. Therefore, many research projects (Colica et al., 2021, 2022 and 2023) have concentrated their work on the investigation and monitoring of the instability of cliffs and the erosion of pocket beaches. The results of such activities can be widely disseminated and shared with expert and non-expert users through web mapping, which has only been used in a very limited way in collaborative coastal management and monitoring by different entities in Malta. This study describes the performance of a WebGIS designed to disseminate the results of innovative geomatic investigations for monitoring and analyzing erosion risk, performed by the Research and Planning Unit within the Public Works Department of Malta. While aiming to include the entire national coastline, three study areas along the NE and NW regional coasts of the island of Malta have already been implemented as pilot cases. This WebGIS was generated using ArcGIS pro software by ESRI and a user-friendly interactive interface has been programmed to help users view in 2D and 3D, satisfying both multi-temporal and multi-scale perspectives. It is envisaged that through further development and wider dissemination there will be a stronger uptake across different agencies involved in coastal risk assessment, monitoring and management.

References

Colica, E., D’Amico, S., Iannucci, R., Martino, S., Gauci, A., Galone, L., ... & Paciello, A. (2021). Using unmanned aerial vehicle photogrammetry for digital geological surveys: Case study of Selmun promontory, northern of Malta. Environmental Earth Sciences, 80, 1-14.

Colica, E. (2022). Geophysics and geomatics methods for coastal monitoring and hazard evaluation.

Colica, E., Galone, L., D’Amico, S., Gauci, A., Iannucci, R., Martino, S., ... & Valentino, G. (2023). Evaluating Characteristics of an Active Coastal Spreading Area Combining Geophysical Data with Satellite, Aerial, and Unmanned Aerial Vehicles Images. Remote Sensing, 15(5), 1465.

How to cite: Colica, E., Fenech, D., Gauci, C., and Buhagiar, G.: Integrating structure-from-motion photogrammetry with 3D webGIS for risk assessment, mapping and monitoring of coastal area changes in the Maltese archipelago, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16939, https://doi.org/10.5194/egusphere-egu24-16939, 2024.

EGU24-17822 | ECS | Posters on site | GM3.1

Evaluating Ordnance Survey sheets (1890s – 1957) for shoreline change analysis in the Maltese Islands  

Daniel Fenech, Jeremie Tranchant, Christopher Gauci, Daniela Ghirxi, Ines Felix-Martins, Emanuele Colica, and George Buhagiar

 

Jeremie' Tranchant1, Daniel Fenech1, Christopher Gauci1, Daniela Ghirxi1, Ines Felix Martins1, Emanuele Colica1, George Buhagiar1

1  Research and Planning Unit, Ministry for Transport, Infrastructure and Public Works, Project House, Triq Francesco    Buonamici, Floriana, FRN1700, Malta

The assessment of coastal erosion through shoreline change analysis, is an exercise of national utility undertaken in many countries. The Maltese Islands are particularly vulnerable to coastal erosion given the economic value of coastal activities and their high ratio of coast-to-land surface. The integration of historical cartographic material is often used to hindcast shoreline change across long periods of time, as well as to model future erosion rates. The Public Works Department have produced detailed 1:2500 maps of Malta in collaboration with the British Ordnance Survey from the end of the 19th century to 1957, however these maps have never been scientifically assessed. The initial research carried out evaluated the usefulness of the two oldest 25-inches Maltese maps series (early 20th century and 1957) for shoreline change analysis.  The two series were digitised, georeferenced, and compared in a GIS environment to assess their differences. The inaccuracies of the original drawings, absent shoreline indicators, and the absence of a geographic coordinate system (datum and projection) were identified as limitations for their use in evaluating small gradual changes, but were ideal for the identification of stochastic, large-scale historic erosion events using difference maps. This assessment showed that the two series are highly congruous and any changes between the two series are largely attributed to changes in infrastructure. There were, however, minor exceptions and these need to be explored on a case-by-case basis. These methods and the insights garnered from their production will function as scientific steppingstones towards developing a holistic coastal erosion national monitoring program.  

How to cite: Fenech, D., Tranchant, J., Gauci, C., Ghirxi, D., Felix-Martins, I., Colica, E., and Buhagiar, G.: Evaluating Ordnance Survey sheets (1890s – 1957) for shoreline change analysis in the Maltese Islands , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17822, https://doi.org/10.5194/egusphere-egu24-17822, 2024.

EGU24-21396 | ECS | Orals | GM3.1

Automatic detection of river bankfull parameters from high density lidar data 

Alexandre Rétat, Nathalie Thommeret, Frédéric Gob, Thomas Depret, Jean-Stéphane Bailly, Laurent Lespez, and Karl Kreutzenberger

The European Water Framework Directive (WFD), adopted in 2000, set out requirements for a
better understanding of aquatic environments and ecosystems. In 2006, following the transposition of
the WFD into French law (LEMA), France began work on a field protocol for the geomorphological
characterization of watercourses, as part of a partnership between the Centre National de la Recherche
Scientifique (CNRS) and the Office Français de la Biodiversité (OFB). This protocol, known as "Carhyce"
(For « River Hydromorphological Caracterisation »), has been tested, strengthened and approved over
the last 15 years at more than 2500 reaches. It consists of collecting standardised qualitative and
quantitative data in the field, essential for the caracterisation of a watercourse: channel geometry,
substrate, riparian vegetation... However, certain rivers that are difficult to survey (too deep or too
wide) pose problems for data collection.
To address these issues, and to extend the analysis to a wider scale (full river section), using
remote sensing, and in particular LiDAR data, was considered. The major advantages of LiDAR over
passive optical sensors are better geometric accuracy and especially under vegetation. For a long time,
LiDAR data rarely exists at national scale with data density similar to passive imagery. Today, the French
LiDAR HD dataset (10 pulses per meter square) program run by the French mapping agency offers an
unprecedented amount of data at this scale. Thanks to them, a national 3D coverage of the ground can
be used, and numerous geomorphological measurements can be carried out on a more or less large
scale. This is the case for hydromorphological parameters such as water level and width.
The aim of this study is therefore to use this high-density lidar to automatically determine the
hydromorphological parameters sought in the Carhyce protocol. In particular, we have developed a
lidar-based algorithm to reconstruct the topography from point cloud and automatically identify the
bankfull level at reach scale. Designed to be applicable to every French river, the method must be
robust to all river features such as longitudinal slope, width, sinuosity, multi-channel etc... For
validation purposes, the bankfull geometry calculated by the algorithm has been compared with field
measurements at some twenty Carhyce stations across France. To determine the test stations, we
looked for the diversity of situations in terms of river characteristics describe above to observed the
influence of this features on the results.

How to cite: Rétat, A., Thommeret, N., Gob, F., Depret, T., Bailly, J.-S., Lespez, L., and Kreutzenberger, K.: Automatic detection of river bankfull parameters from high density lidar data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21396, https://doi.org/10.5194/egusphere-egu24-21396, 2024.

EGU24-22358 | ECS | Orals | GM3.1 | Highlight

UAV’s to monitor the mass balance of glaciers 

Lander Van Tricht, Harry Zekollari, Matthias Huss, Philippe Huybrechts, and Daniel Farinotti

Uncrewed Aerial Vehicles (UAVs) are increasingly employed for glacier monitoring, particularly for small to medium-sized glaciers. The UAVs are mainly used to generate high-resolution Digital Elevation Models (DEMs), delineate glacier areas, determine surface velocities, and map supraglacial features. In this study, we utilise UAVs across various sites in the Alps and the Tien Shan (Central Asia) to monitor the mass balance of glaciers. We present a workflow for calculating the annual geodetic mass balance and obtaining the surface mass balance using the continuity-equation method. Our results demonstrate generally a close alignment between the determined mass balances and those obtained through traditional glaciological methods involving intensive fieldwork. We show that utilising UAV data reveals significantly more spatial details, such as the influence of debris and collapsing ice caves, which are challenging to capture using conventional methods that strongly rely on interpolation and extrapolation. This underscores the UAV's significance as a valuable add-on tool for quantifying annual glacier mass balance and validating glaciological assessments. Drawing on our experience in on-site UAV glacier surveys, we discuss the methodology's advantages, disadvantages, and potential pitfalls. 

How to cite: Van Tricht, L., Zekollari, H., Huss, M., Huybrechts, P., and Farinotti, D.: UAV’s to monitor the mass balance of glaciers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22358, https://doi.org/10.5194/egusphere-egu24-22358, 2024.

EGU24-196 | ECS | Posters on site | GM3.2

Remote sensing and geomorphometry application in riverscapes evolution in the south-eastern Arabian Peninsula (Sultanate of Oman) 

Andrea Pezzotta, Alessia Marinoni, Mohammed Al Kindi, Michele Zucali, and Andrea Zerboni

Riverscapes in arid and semi-arid environments serve as crucial archives, enabling us to understand the landscape evolution and the active and fossil geomorphological processes that shape the Earth's surface. Such environmental contexts are generally wide, and these settings are routinely investigated with remote sensing tools. We selected two distinct study areas from the south-eastern margin of the Arabian Peninsula (Sultanate of Oman) to detect climate and tectonic imprints over landform development: 1) Jebel Akhdar (JAK), and its surrounding areas, located in the Al-Hajar Mountains (to the North), is a wide anticline formed by the Late Cretaceous obduction of the Semail Ophiolite and the associated time-equivalent tectonics, followed by the Cenozoic tectonic events; and 2) Jebel Qara (JQA), situated in the Dhofar Mountains (to the South), is placed along the Gulf of Aden transform margin, featuring transtensional faults giving rise to stepped escarpments and grabens. The extant landscapes of both regions are characterized by a network of narrow and deep canyons that incised limestone massifs, while the surrounding plain areas show the development of important alluvial fan systems.

The application of remote sensing is essential for investigating the development of fluvial systems at a regional scale, combined with field survey to validate specific sites of interest, thereby understanding the geomorphological evolution at various scales. Specifically, remote sensing techniques include the processing of satellite imagery and the comparison with the available historical imagery and maps to detect changes in geomorphic processes. Remote sensing and field survey allow the recognizing of different geomorphological features; the dominant ones are represented by elements and landforms related to structural setting, fluvial activity, and karst processes. The associations of the abovementioned landforms make it possible to assess the structural influence on drainage and karstic network development. Data collected from remote sensing implements the geomorphometric quantification of geomorphological processes, mostly considering changes in topography and river network analyses. The most meaningful morphometric indices applied (such as drainage divide stability, normalized steepness index, knickpoint detection, and swath profiles…) suggest their values strongly vary along faults in JAK, highlighted even with the alignment of knickpoints; while, in JQA, values show little changes in correspondence of faults and knickpoints are controlled both by karst and structural settings. In this way, the combination of remote sensing and morphometrical analyses permits to quantify the central role of litho-structural influence on the development of riverscapes in the south-eastern Arabian Peninsula. This approach facilitates the identification of the primary geomorphological processes that have shaped the landscape in arid and semi-arid contexts of the Sultanate of Oman, making it a versatile method that can be applied to understand the riverscapes evolution processes in analogous regions.

How to cite: Pezzotta, A., Marinoni, A., Al Kindi, M., Zucali, M., and Zerboni, A.: Remote sensing and geomorphometry application in riverscapes evolution in the south-eastern Arabian Peninsula (Sultanate of Oman), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-196, https://doi.org/10.5194/egusphere-egu24-196, 2024.

EGU24-1613 | ECS | Posters on site | GM3.2

Simulating 4D scenes of rockfall and landslide activity for improved 3D point cloud-based change detection using machine learning 

Ronald Tabernig, Vivien Zahs, Hannah Weiser, and Bernhard Höfle

Terrestrial Laser Scanning (TLS) systems have been refined to automatically and continuously scan defined areas with high temporal resolution (sub-hourly), leading to the development of Permanent Laser Scanning (PLS). This temporal resolution requires the development of new methods for efficient extraction of change information. The creation of labeled 4D point clouds (3D+time), classified by surface change type, remains time-consuming. This hinders the evaluation of change detection methods and the training of machine learning (ML) and deep learning (DL) models.

This study explores how synthetic 4D point clouds can be effectively utilized for detecting and classifying spatiotemporal changes. We combine simplified process path simulations, simulated PLS, and change detection methods (e.g. M3C2) [1]. This combination is used to automatically evaluate calculated distances compared to a pre-defined reference. It also generates labeled 4D training datasets for ML/DL approaches.

We adapted the Gravitational Process Path model (GPP) [2] to create gravity-influenced process paths for our PLS simulations. Utilizing these paths, we simulate two different scenarios, 1) including a forest situated on top of a large landslide and 2) an outcrop with rockfall activity. For the forest scenario, a constant velocity is applied to each tree to simulate slope movement. The velocity of the objects in the rockfall scene is determined by the GPP model. Dynamic 3D scenes are generated from these scenarios and used as input for Virtual Laser Scanning (VLS). Realistic simulation of LiDAR surveys (of these virtual scenes) is achieved by using the open-source simulator HELIOS++ [3]. This workflow allows for the determination of the accurate position of each object at any given time. It provides reference data that is usually unavailable in real data acquisitions. In the rockfall scenario, M3C2 distances are calculated, and areas of similar change are clustered. For the forest located on the landslide, 2D and 3D displacement vectors are derived from the displacement of the tree trunks. These changes are then compared to the actual change occurring between epochs. Furthermore, the time steps between each epoch can be chosen arbitrarily, enabling the exploration of various scenarios and processes using labeled point clouds at any temporal resolution.

Preliminary results suggest that this workflow can assist in determining the scan resolution required to detect changes of a specific size and magnitude. We establish a simulation-based error margin for each method used by comparing the results to the reference data. This enables direct evaluation of method performance during implementation.

We demonstrate the potential of combining process simulation and laser scanning simulation for resource efficient planning of TLS and PLS campaigns, geographically sound generation of dynamic point clouds, the evaluation of change detection and quantification methods, and generating labeled point clouds as training data for 4D ML/DL methods. 

References:
[1] py4dgeo: https://github.com/3dgeo-heidelberg/py4dgeo
[2] Wichmann, V. (2017): https://doi.org/10.5194/gmd-10-3309-2017.
[3] Winiwarter, L. et al. (2022): https://doi.org/10.1016/j.rse.2021.112772. 

How to cite: Tabernig, R., Zahs, V., Weiser, H., and Höfle, B.: Simulating 4D scenes of rockfall and landslide activity for improved 3D point cloud-based change detection using machine learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1613, https://doi.org/10.5194/egusphere-egu24-1613, 2024.

EGU24-4207 | Orals | GM3.2

Incorporating ontological characteristics for global landform classification based on 30 meters DEM 

Xin Yang, Chenghu Zhou, Sijin Li, Junfei Ma, Yang Chen, Xingyu Zhou, Fayuan Li, Liyang Xiong, Guoan Tang, and Michael Meadows

Landform classification and mapping provide fundamental data for Earth science research, natural resource management, environmental monitoring, urban planning, and various other domains. Despite the availability of DEMs with 1-arc second resolution, global-scale studies on landform classification and mapping are inconsistent in terms of general classification systems and methods.

Landforms represent not only assemblages of morphological characteristics but also encompass the human understanding of the Earth, which is constrained by the nature and scale of quantitative analysis. Here, we propose a novel framework for global landform mapping to significantly improve the quantitative evaluation of geomorphological features.

The proposed framework incorporates geomorphological ontology that takes account of their conceptualization to construct classified objects. We propose the accumulated slope (AS) and mountain uplift index (MUI) to emphasize the integrity and continuity of geomorphological units, providing more precise results compared to traditional methods. Aggregating local terrain features into global metrics, AS effectively overcomes the potential negative influence of increased resolution on landform integrity. MUI aligns better with human perception of mountainous morphology and surpasses the limitations of window-based computing.

In presenting the new framework, we have developed and made available a public dataset, Global Basic Landform Unit (GBLU), which incorporates a comprehensive set of objects that constitute the range of landforms on Earth. In emphasizing the integration of classification with quantitative analysis, GBLU highlights the connection between natural objects and human understanding in geomorphology and the Earth sciences. The GBLU outperforms previous datasets (the basic landform classification and global mountain assessment) in expressing landform details. GBLU can be downloaded at https://geomorph.deep-time.org. It serves as a valuable resource in facilitating a deeper understanding of landform spatial distribution and evolution, and supporting research in a diverse range of fields.

How to cite: Yang, X., Zhou, C., Li, S., Ma, J., Chen, Y., Zhou, X., Li, F., Xiong, L., Tang, G., and Meadows, M.: Incorporating ontological characteristics for global landform classification based on 30 meters DEM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4207, https://doi.org/10.5194/egusphere-egu24-4207, 2024.

The influence of temperature as a key factor in slope stability, particularly in temperate regions, remains insufficiently explored. This study investigates the thermo-hydro-mechanical (THM) response of expansive soils, focusing on the thermally-induced activity in clay landslides.

Establishing a representative thermal variable for broad-scale assessments poses challenges due to material heterogeneities and the intricate nature of THM processes. Our research employs landslide spatial modelling in Italy, concentrating on clay-rich areas with shallow landslides on gentle slopes. Utilizing geo-lithological and geological maps and the Italian National Inventory (IFFI), we apply a Generalized Additive Model (GAM) based on slope units to capture nonlinearities in the temperature-shear strength relationship. A decade-long dataset of Land Surface Temperature (LST) from MODIS, accessible in Google Earth Engine, serves as a key input.

The study produces spatial probability maps for clay deposits across Italy, revealing a positive correlation between landslide occurrence and LST on warmer, gentle slopes, especially in Southern Italy. This aligns with the observation that higher temperatures reduce soil and water viscosity, amplifying shear creep rates in clay-rich materials. By elucidating the temperature-slope stability relationship, this study contributes to understanding landslide dynamics in temperate climates, facilitating the development of effective risk recognition strategies.

How to cite: Loche, M. and Scaringi, G.: Exploring Temperature-Shear Strength Dynamics: A Spatial Modelling Approach for Clay Landslide Susceptibility in Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5190, https://doi.org/10.5194/egusphere-egu24-5190, 2024.

EGU24-6250 | ECS | Orals | GM3.2

Three-Dimensional Stress Analysis of Mountain Ranges: A Novel Approach Using Marching Volume Polytopes Algorithm and Finite Cell Method  

Viktor Haunsperger, Jörg Robl, Andreas Schröder, and Stefan Hergarten

The negative feedback between relief formation due to valley incision, increasing topographic stress towards a critical stress state dependent on rock strength, and consequently relief-destroying (and stress-reducing) landslides determines the geometry of alpine landscapes. Hence, the computation of topographic stresses for entire mountain massifs is crucial to identify potential landslide hotspots at steep landforms close to rock failure, determining the maximum strength of rocks and rock sequences at the mountain scale, and explaining contrasting geometries of alpine landscapes in dependence on the prevailing rock types. Traditional 2D stress and displacement calculations on valley cross-sections tend to oversimplify the complicated stress pattern, particularly where valleys converge or around ridges and peaks. 3D stress calculations based on standard finite element methods are computationally expensive and not feasible for entire mountain massifs at a reasonable expense.

Our study addresses this limitation by employing a novel three-dimensional approach, utilizing the Marching Volume Polytopes Algorithm for mesh generation and the Finite Cell Method as an alternative to the widely used finite element method. Incorporating an octree-like structure and advancing-front meshing techniques, the Marching Volume Polytopes Algorithm accurately represents given surface data through a tetrahedral mesh. In the Finite Cell Method representing a fictitious domain approach, the difficulty of generating adequate grids for physical domains with complicated geometry is transformed into the problem of specifying an adequate integration scheme for the finite cells and thus saving degrees of freedom. The computational efficiency of our approach is particularly advantageous when dealing with equidistant grids such as digital elevation models for mesh generation.

In a first study, we use our model to compute the 3D topographic stress distribution for the three Austrian UNESCO Global Geoparks known for over-steepened valley flanks and high landslide activity. Initial results show high shear stress maxima occurring predominantly at over-deepened glacial valleys bordered by rock faces, with stress maxima at valley flanks but also at or slightly below the valley floors. Unexpected stress patterns occur in areas with a complicated landscape geometry, where valleys converge, or intersecting ridge lines form pyramid peaks. Lithological contrasts of the investigated mountain massifs are reflected in very different stress patterns, with shear stress maxima showing the highest values in carbonate-dominated units.

In addition to local topographic metrics, the spatial distribution of observed landslides and the rock types that occur, modelled topographic stresses provide a new data set for assessing landslide potential. Beyond that, modeling topographic stresses of entire mountain massifs offers new insights into the evolution of alpine landscapes in the competition between relief-forming and relief-destroying processes.

How to cite: Haunsperger, V., Robl, J., Schröder, A., and Hergarten, S.: Three-Dimensional Stress Analysis of Mountain Ranges: A Novel Approach Using Marching Volume Polytopes Algorithm and Finite Cell Method , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6250, https://doi.org/10.5194/egusphere-egu24-6250, 2024.

Mapping benthic reefs at high resolution and accuracy is vital for the management and conservation of coral habitats. Optical remote sensing data has emerged as a valuable tool for large-scale reef mapping in the past decades, with numerous data sets and methods being utilised and developed. In this study, we present a comprehensive comparison of optical remote sensing based bathymetry and benthic mapping methods. We use different optical data including WorldView-2 stereo and Sentinel-2 imagery to map the water depths of coral reef areas in the Xisha region of the South China Sea. Bathymetry data derived from photogrammetric and linear regression methods are compared to the reprocessed Ice, Cloud and land Elevation Satellite-2 (ICESat-2) data. We find that the linear regression method (root-mean-square-error, RMSE=0.60 m) outperforms photogrammetry (RMSE=1.02 m), and the higher resolution WorldView-2 data yields less systematic biases than Sentinel-2 data. Considering that water depths reflect changes in temperature and light, which are critical factors influencing coral reef distribution, we propose to use satellite-derived bathymetry as a feature for coral reef classification. We demonstrate that combining topography and spectral information can improve the overall mapping accuracy, particularly for compositions characterised by sharp boundaries.

How to cite: Liu, Y., Zhou, Y., and Yang, X.: Bathymetry derivation and slope-assisted benthic mapping using optical satellite imagery in combination with ICESat-2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7114, https://doi.org/10.5194/egusphere-egu24-7114, 2024.

EGU24-7859 | Posters on site | GM3.2

The Performance of the Man-Kendall Test in the Analysis of Coastal Changes along Cliff Sections on the Baltic Sea 

Michael Fuchs, Lars Tiepolt, Karsten Schütze, and Jewgenij Torizin

Airborne Light Detecting and Ranging (LiDAR) surveys became essential in tracking the evolving coastal landscapes of Mecklenburg-Vorpommern on the Baltic Sea for more than one decade, producing a data series of Digital Terrain Models (DTMs) crucial for estimating coastal erosion along the exposed cliffs. Although change detection based on differences between these DTMs is supposed to represent erosion and deposition accurately, a detailed analysis indicates that the initial and final DTMs in the data series sometimes fail to capture the full extent of changes due to various factors. So, natural phenomena, such as the movement of cliff materials (rolling, sliding, creeping), human activities aimed at coastal protection, and errors in DTM processing may disturb clear trends, introducing uncertainties and, in particular, making the data series appear alternating.

To address these issues, we proposed to apply the robust Mann-Kendall test, a non-parametric statistical method used to identify trends in a data series without assuming any particular data distribution. It focuses on determining the direction and consistency of trends (ascending or descending), rather than the change’s magnitude. By implementing this approach, we can pinpoint areas that exhibit clear trends, thereby significantly improving the accuracy of coastal retreat estimations. In regions where trends are not readily apparent, it becomes crucial to investigate potential contributing factors thoroughly by exploring natural environmental dynamics, assessing the impact of human activities, and scrutinizing any errors in data processing. Such a comprehensive analysis ensures a more holistic understanding of the factors influencing these zones.

We employed the proposed approach across four distinguished shore areas characterized by the distinct geological composition of the cliffs, delving into the trends of coastal retreat over the past ten years. As expected for areas with clear trends, the estimation of the dimensions of the recent coastal retreat was in good agreement with historically recorded data. Additionally, in areas exhibiting no discernible trends, we were able to identify the underlying reasons, shedding light on the intricacies of coastal dynamics.

How to cite: Fuchs, M., Tiepolt, L., Schütze, K., and Torizin, J.: The Performance of the Man-Kendall Test in the Analysis of Coastal Changes along Cliff Sections on the Baltic Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7859, https://doi.org/10.5194/egusphere-egu24-7859, 2024.

EGU24-8222 | ECS | Posters on site | GM3.2

Automated and flexible measuring of grain size and shape in images of sediment with deep learning 

David Mair, Guillaume Witz, Ariel Henrique Do Prado, Philippos Garefalakis, and Fritz Schlunegger

The size and shape of sediment particles record crucial information on erosion, transport, and deposition mechanisms during sedimentary processes. Therefore, data on grain morphometry is a critical component in understanding sediment production and transport dynamics in various environments, such as fluvial or hillslope settings. However, traditional field methods are labor-intensive, and results may suffer from a limited number of observations. At the same time, remote measurements in images or point clouds still need improvements to counter low accuracy or the need for time-consuming manual corrections (e.g., Steer et al., 2022). These persisting challenges impede the capability of routinely obtaining size and shape information.

Here, we present a new and automated approach (Mair et al., 2023) for obtaining morphometric information on coarse sediment particles from segmented images. To do so, we tap into the capability for transfer learning of deep neural networks. In particular, we use state-of-the-art deep learning, developed to find cells in biomedical images, to segment individual grains in pictures of various sediments and image types. Our method validation includes assessing segmentation performance against ground truth from annotated images and evaluating the measurement quality by comparing results to independent measurements in the field and in images. This approach facilitates precise and rapid grain segmentation and outperforms existing methods. In addition, we observe that higher segmentation quality directly leads to improved precision and accuracy for grain size and shape data. Furthermore, any model of the used architecture can easily be re-trained for new image conditions, which we successfully did for several different settings. This highlights the potential for easy adapting to different environments and scales with comparatively small datasets.

References

Mair, D., Witz, G., Do Prado, A. H., Garefalakis, P., and Schlunegger, F.: Automated detecting, segmenting and measuring of grains in images of fluvial sediments: The potential for large and precise data from specialist deep learning models and transfer learning, Earth Surf. Process. Landforms, 1–18, https://doi.org/10.1002/esp.5755, 2023.

Steer, P., Guerit, L., Lague, D., Crave, A., and Gourdon, A.: Size, shape and orientation matter: fast and semi-automatic measurement of grain geometries from 3D point clouds, Earth Surf. Dyn., 10, 1211–1232, https://doi.org/10.5194/esurf-10-1211-2022, 2022.

How to cite: Mair, D., Witz, G., Do Prado, A. H., Garefalakis, P., and Schlunegger, F.: Automated and flexible measuring of grain size and shape in images of sediment with deep learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8222, https://doi.org/10.5194/egusphere-egu24-8222, 2024.

EGU24-10314 | ECS | Posters on site | GM3.2

A deep learning-based super-resolution DEM model for pluvial flood simulation 

Yue Zhu, Paolo Burlando, Pauy Yok Tan, Christian Geiß, and Simone Fatichi

High-resolution Digital Elevation Model (DEM) data provides essential information for pluvial flood simulation. Although the increased accessibility and quality of publicly available DEM datasets can facilitate geospatial analysis at various scales, existing DEM datasets with global coverage mostly lack sufficient spatial resolution for pluvial flood simulations, which require detailed topographic information to be included in the simulation. Simulating flood scenarios with low-resolution DEMs (>30m) can result in substantial deviations from real cases. This issue becomes even more severe for flood-prone areas in data-scarce developing countries.

Image super-resolution is a technique for reconstructing low-resolution information into high-resolution data. Various deep-learning models have been employed for this task, primarily focusing on generating high-resolution natural-colour images. However, the effects of these deep learning models on enhancing the resolution of DEM data have not been extensively investigated. One of the state-of-the-art super-resolution models, the Residual Channel Attention Network (RCAN), has gained popularity due to its accuracy and efficiency. Leveraging publicly available low-resolution global DEM data and high-resolution regional DEM data, this study assesses the performance of RCAN models in a DEM super-resolution task. The experimental results suggest that, compared to conventional interpolation methods, the tested RCAN model exhibits superior performance in constructing high-resolution DEM data. The generated super-resolution DEM data were then tested in pluvial flood simulations and achieved substantially higher realism in modelling floodwater distribution. The proposed method for constructing super-resolution DEMs opens up the possibility of simulating flooding at hyper-resolution globally.

How to cite: Zhu, Y., Burlando, P., Tan, P. Y., Geiß, C., and Fatichi, S.: A deep learning-based super-resolution DEM model for pluvial flood simulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10314, https://doi.org/10.5194/egusphere-egu24-10314, 2024.

EGU24-11527 | ECS | Orals | GM3.2

Identification of river channel bankfull geometry from topographic indicators extracted from high-resolution digital elevation datasets  

Valeria Ruscitto, Michele Delchiaro, Wolfgang Schwanghart, Eleonora Brignone, Daniela Piacentini, and Francesco Troiani

River channel bankfull geometry and discharge are important features providing valuable insights into fluvial monitoring and flood recurrency. The bankfull stage represents the riverbank position that approximates the level at which water overflows onto the floodplain. Bankfull discharge is considered the channel-forming discharge, with a recurrence interval of approximately 1.5 years. Bankfull floods are significant, as they are highly effective in changing channel shape and characteristics. Their recurrence intervals can be used for stream assessment and have implications for infrastructure design and flood mapping. Additionally, gaining insights into the factors influencing floodplain inundation across various time periods is crucial, as the frequency of flood events is predicted to rise with the increase in global temperatures.

In this contribution, we present a novel approach to identify the bankfull geometry through a set of dedicated MATLAB functions. A Digital Elevation Model (DEM) with ground resolution of 1 m/pixel is used as input elevation dataset, obtained with airborne LiDAR (Light Detection and Ranging) survey. The selected river channels are divided in regularly spaced sampling sections, where the bankfull geometry is extracted. Then, the hydraulic depth function that plots the elevation above the river thalweg vs. the ratio between the area and the width is computed for every section. Then, the elevation above river associated to the lowest and the most prominent peaks of the function, corresponding respectively to the bankfull stage or bankfull/floodplain inflection point and to the floodplain, are automatically extracted for each section. Manning’s equation is then applied to the hydraulic geometry corresponding to the lowest peaks elevation to compute the bankfull discharge at every river channel section. The validation process includes the comparison between the results obtained through the automatic bankfull geometry and discharge estimation and discharge data available from river hydrological gauges. Results demonstrate that the developed approach is effective to delineate the bankfull geometry from high-resolution DEMs and complements traditional qualitative field observations. Thus, our approach represents a cost-effective alternative for mapping detailed spatial variations over large spatial extents that are difficult to cover with traditional fieldwork.

How to cite: Ruscitto, V., Delchiaro, M., Schwanghart, W., Brignone, E., Piacentini, D., and Troiani, F.: Identification of river channel bankfull geometry from topographic indicators extracted from high-resolution digital elevation datasets , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11527, https://doi.org/10.5194/egusphere-egu24-11527, 2024.

EGU24-12288 | Posters on site | GM3.2

TopoToolbox 3 – avenues for the future development of a software for terrain analysis 

Wolfgang Schwanghart, William Kearney, Anna-Lena Lamprecht, and Dirk Scherler

The Earth’s surface results from the interplay of tectonic and erosive forces, and the action of organisms and humans. To gain a deeper understanding of these interactions, accurate monitoring and analysis of topography is essential. Digital elevation models (DEMs) are powerful tools for achieving this goal and are available at ever increasing spatial resolution. TopoToolbox is a research software that provides a “laboratory” for the analysis of DEMs, enabling customized, automated analysis, prototyping and creative method development. Its high computational efficiency, ease-of-use and extensive documentation have attracted a worldwide user base across multiple research disciplines.

Over the last ten years, TopoToolbox, now in version 2, has undergone numerous changes and additions. The development of version 3 of TopoToolbox seeks to build on those past successes and take the software to the next level. Specifically, our goals are (1) to improve usability and accessibility, (2) to enhance quality assurance in the software’s development process, and (3) to increase community involvement in the ongoing development of TopoToolbox. We strive to achieve these goals in a recently funded 2-year project, in which community involvement is a key aspect. In this presentation, we aim to interact with other researchers interested in terrain analysis to discuss avenues for future developments and activities that improve TopoToolbox's usability, expand its usage, and increase its impact in a new version 3.

How to cite: Schwanghart, W., Kearney, W., Lamprecht, A.-L., and Scherler, D.: TopoToolbox 3 – avenues for the future development of a software for terrain analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12288, https://doi.org/10.5194/egusphere-egu24-12288, 2024.

After successfully applying segmentation and machine learning for landform identification and delineation for concave, convex, and generic landforms (landslides, floodplains), the used approach is generalized as a framework. The approach can be implemented in any GIS software that allows scripting and is based on four steps: (i) object-based segmentation based on a specific geomorphometric variable, (ii) contextual merging if the landform is composed of multiple shapes, (iii) selection of the training data segments, (iv) statistical classification by machine learning. The framework refers to creating a set of rules for various scenarios of landform types to allow the implementation of the approach for various landforms and areas around the globe. One of the main requirements regarding the DEM is that its feature resolution be high enough to allow at least a segment to cover the target landform spatially. This requires either LiDAR or RADAR DEMs, with medium or high resolution. We tested COPDEM in areas where there is no vegetation cover and the results show that landslides, floodplains, gullies, sinkholes, and closed depressions can be depicted by the approach.

How to cite: Niculita, M.: A generic framework for the identification and delineation of landforms from high-for DEMs using segmentation, contextual merging, and machine learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13034, https://doi.org/10.5194/egusphere-egu24-13034, 2024.

EGU24-13135 | Posters on site | GM3.2

Spectral analysis as proxy for lineament spatial distribution: validation and case study 

Anna Maria Dichiarante, Tim Redfield, Espen Torgersen, Anne Kathrine Svendby, and Volker Oye

Spectral analysis (SA) is a technique commonly used in signal and image processing that makes use of the Fast Fourier Transform to compute the 2D power spectrum, which is a representation of the magnitude of each frequency component of the signal or image. SA can be similarly performed on a topographic map, and the orientation, frequency and magnitude (or power) of general topographic trends can be automatically retrieved and displayed in the 2D power spectrum. Recent studies have shown that spectral analysis can be successfully used to characterize repetitive and spatially homogeneous features or landforms, such as ridge and valley or glacial lineations. However, although these repetitive features dominate the 2D power spectrum, all the topographic information of the map is still present. Therefore, SA can be used on heterogenous and complex topographic map as a proxy for lineament analysis.

Lineament analysis is broadly used in a wide number of applications which include tectonic studies, exploration for groundwater, hazard evaluation for tunnel excavation, rockfalls or waste repository etc. Here, we propose a new methodology for lineament analysis based on spectral analysis and we demonstrate that this is a fast and effective way to derive lineament spatial distribution from images that can be visualized as rose diagrams. To validate our methodology, we stochastically generated 1000 synthetic lineament networks and numerically compared the rose diagrams derived from the power spectra to known lineament distribution. The comparison held a similarity of 94%.

The methodology was also applied to the Oslo region and compared to automatically extracted lineaments from OttoDetect software (developed by the Geological Survey of Norway). Results on three pre-selected areas characterized by different topographic patterns showed similarity of 97%, 95%, and 90%, respectively.

One of the pitfalls of spectral analysis is the lack of positioning on the original map of the signatures in the power spectrum. To locate the main signature on the map, we used the orientation of the main signatures from the power spectrum and used cross-correlation and clustering methods on topographic profiles.

How to cite: Dichiarante, A. M., Redfield, T., Torgersen, E., Svendby, A. K., and Oye, V.: Spectral analysis as proxy for lineament spatial distribution: validation and case study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13135, https://doi.org/10.5194/egusphere-egu24-13135, 2024.

EGU24-13867 | ECS | Orals | GM3.2

The effect of correcting the projection error in Digital Terrain Models on Earth surface processes 

Anne Voigtländer, Aljoscha Rheinwalt, and Stefanie Tofelde

Hiking up a steep mountain, in comparison to walking on a flat beach, is unarguably different. But the horizontal distance made, estimated using a Digital Terrain Model (DTM), might be the same. The projection of 3D landscapes onto 2D grids in DTMs leads to a slope-dependent, inhomogeneous sampling of the surfaces, and a first-order error in topographic metrics. Using the slope dependency of this error, we can quantify and revert it. Foremost, correcting the projection error allows for more accurate estimates of area and volume, e.g., to quantify natural hazards; and enables the use of the full slope distribution to define the physical space of surface processes at any scale.

We quantify the projection error using synthetic landscapes for which analytical solutions of slope angles and surface area are known. In applying the correction to DTM data of a real landscapes, we can address geomorphological processes in physically more meaningful ways. The corrected extracted topographic proxies, here exemplary, the erosional response to uplift in the Mendocino Triple Junction (MTJ) area, California, USA, provide two aspects for interpretation of geomorphic processes. First, as all slope angles are now represented equally, the variations in slope distribution by region of uplift rate is more pronounced. Second, the erosional response causes not only a steepening but narrow slope distribution in the regions of high uplift. The transient response is visible in a broadening of the distribution towards the lower slope angles, as deposition becomes more prevalent. In this example, we also find that the surface area ratio, enables determining the effectiveness of Earth surface processes, by increasing or decreasing the differential between the standard-planform and the surface area. Earth surface processes, that involve transport and volume along the surfaces, if not referenced in time, the ratio between the planform and surface area can provide a spatial reference and could be explored further. Correcting topographic metrics also allows addressing additional questions, like, which slope angles characterize which process domains, which processes create steepening, which lowering of slopes, where, and to what extent? Or, which parts of landscapes, maybe not the steepest, correlate to the highest potential to erode?

 

How to cite: Voigtländer, A., Rheinwalt, A., and Tofelde, S.: The effect of correcting the projection error in Digital Terrain Models on Earth surface processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13867, https://doi.org/10.5194/egusphere-egu24-13867, 2024.

The integration of point-cloud data in geo- and environmental sciences has become increasingly pivotal, with applications ranging from UAVs, spaceborne and airborne lidars to ground-based lidars and stereo-photogrammetric techniques. This session seeks contributions that delve into challenges related to classification, segmentation, and noise removal in the context of point-cloud data, crucial for facilitating change detection studies. Our study focuses on the Navigational Branch of the ERDC Coastal Hydraulics Laboratory tasked with developing a Digital Twin model for a Dam, exemplifying the complexities involved in creating CAD models of terrain and structures.

To address the intricacies of point-cloud data processing, we employed both open-source and proprietary software solutions—Cloud Compare and Autodesk ReCAP— for noise reduction, ensuring the prepared data is seamlessly integrated into CAD modeling software, specifically Inventor. Surface modeling involved the strategic application of planes on cloud points to generate a foundation for sketching and subsequent solid surface extrusion.

Classification of data points was initiated through the implementation of regions in the noise removal software, facilitating the depiction of various areas on the model. Further, color and material assignment in the CAD software enhanced the identification of distinct part areas. Microstation TopoDOT played a pivotal role in creating a detailed terrain model, complete with physical landmarks and water bodies specific to the Dalles dam site.

The resulting models were exported in the desired file format, ensuring compatibility with sponsor requirements. This case study not only showcases the practical challenges encountered in working with point-cloud data but also highlights effective strategies for noise reduction, classification, and model exportation. The presented methodologies contribute to the broader spectrum of geo- and environmental sciences, emphasizing the significance of accurate point-cloud processing for comprehensive modeling endeavors.

How to cite: Krapac, M.: Advancements in Point-Cloud Processing for Geo-Environmental Modeling: A Case Study of The Dalles Dam Digital Twin Creation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14080, https://doi.org/10.5194/egusphere-egu24-14080, 2024.

EGU24-14955 | Posters on site | GM3.2

Multi-Technique Analysis and Landscape Evolution: Implications for Landslide-Fluvial Cascading Hazards Assessment 

Marta Guinau, Celeste Fernández-Jiménez, Anna Barra, Marc Viaplana-Muzas, Ariadna Flores, Maria Ortuño, Marta González, Jordi Pinyol, and Clàudia Abancó

The interaction between slope instability processes and river dynamics often triggers a cascade effect. Sediment influx from slopes can obstruct rivers, leading to upstream flooding and potential catastrophic flash floods downstream upon dam breakage. In addition, the incision of the drainage network steepens the valley hillslopes, further exacerbating slope instability processes, modifying the geomorphology and the sedimentary fluxes and increasing the occurrence of landslide-derived hazards.

In this regard, a comprehensive and updated landslide inventory, especially focusing on the interconnection between landslides and drainage networks, is crucial for effective hazard assessment considering these cascading effects induced by slope and fluvial processes.

This study presents advancements in landslide mapping by integrating data from Multi-Temporal Synthetic Aperture Radar (MT-InSAR) and landscape evolution analysis through geomorphological indices such as Chi, Normalized Channel Steepness Index (Ksn) and Stream Length-Gradient Index (SL). Identification of anomalies along rivers using Ksn and SL (knickpoints or knickzones) aided in pinpointing abnormal slopes due to sediment influx from landslides. Additionally, active areas were delineated using the ADAfinder tool, extracting data from MT-InSAR provided by the European Ground Motion Service (EGMS). This multi-technique analysis highlighted the slopes of interest. Landslides identified with these techniques were delimited and characterized in terms of type assignment, using 2x2 m DTM hillshades derived from airborne LiDAR data and field observations.

The upper catchments of the Garona and Noguera Pallaresa rivers (central Pyrenees-NE Spain) were selected as study cases. The study highlights the disequilibrium in the watershed divide between Noguera Pallaresa and Garona basins, suggesting a transition toward equilibrium favouring a main divide migration towards the Noguera Pallaresa due to hillslope processes. The assessment of the equilibrium profile geometry of the Noguera Pallaresa river at a regional scale suggests at least two main knickpoints. The river sections downstream of the knickpoints are associated with landslides triggered by post-glacial dynamics and incision wave effects. Combining SL and Ksn curves with Active Deformation Areas (ADA) underscores areas with potentially reactivating deep-seated landslides, signifying potential high damages in case of low-probability but catastrophic reactivations.

In conclusion, the integration of diverse methodologies shed light on the spatial relationship between transient features in the landscape (knickpoints) and landslide occurrence, emphasizing the need for a comprehensive approach to mitigate landslide and fluvial risks in the Noguera Pallaresa and Garona river basins.

How to cite: Guinau, M., Fernández-Jiménez, C., Barra, A., Viaplana-Muzas, M., Flores, A., Ortuño, M., González, M., Pinyol, J., and Abancó, C.: Multi-Technique Analysis and Landscape Evolution: Implications for Landslide-Fluvial Cascading Hazards Assessment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14955, https://doi.org/10.5194/egusphere-egu24-14955, 2024.

EGU24-15001 | Orals | GM3.2 | Highlight

Applying photogrammetry to time-lapse imagery for geomorphological change detection 

Anette Eltner, Xabier Blanch, Oliver Grothum, Lea Epple, Eliisa Lotsari, Katharina Anders, and Melanie Elias

Cameras that capture images in time-lapse mode of the earth surface enable great opportunities for change detection and thus potential process identification and understanding. The camera systems can range from simple and robust game cameras to complex and synchronised full frame cameras. The main workflow of calculating digital elevation models from overlapping images is similar for the different types of systems; automatically matching the images, performing bundle adjustment considering either calibrated or non-calibrated cameras, geo-referencing the data by automatic ground control point (GCP) measurement, densifying the point cloud and eventually calculating point cloud differences. However, adapted pre-and post-processing steps are needed due to the varying observation conditions considering the camera qualities and the objects of interest. The time-series of point cloud-based change information can be further processed, for example, with time-series clustering approaches to disentangle overlapping processes.

We will introduce three different case studies in the field of fluvial geomorphology, soil erosion research and rockfall assessment. Thereby, different camera systems are utilized. Four low-cost time-lapse cameras are applied in arctic environments to study changes of a river bank at a distance of about 60 m. The high robustness of the cameras encompasses the trade-off of low quality images. In addition, challenging lighting conditions and enduring snow cover complicate the photogrammetric processing. The images are captured with a frequency of two hours, and six permanent GCPs are used to geo-reference the measurements.

Digital SLR cameras are used in moderate climate to measure soil surface changes either due to rainfall simulations or due to natural rainfall events. During the rainfall simulation we use images that are captured by up to ten cameras with a frequency of 10 to 20 seconds and at an object distance between 3 to 4 m. And at the field plot we installed three special camera rigs that encompass five cameras each that are event-controlled by a micro-controller and single board computer solution, which trigger the cameras each time a rain collector bucket is tipping in addition to daily captured images. Challenges for change detection arise from vegetation present at the plots and from runoff water covering the soil surface. Eventually, the derived models of change are used to validate physical based soil erosion models.

The last case study utilizes five full-frame system cameras in the Mediterranean to detect single rockfall events. Images are captured three times a day by an ad-hoc system at a distance of about 100 m. The data is transferred via a locally installed network module. Many areas within the field of view remain stable throughout the measurement period allowing for a time-SIFT approach that matches the images from different points in time. Machine learning algorithms are applied to automatically identify rockfalls in the final 4D dataset. Thereby, we showcase the great potential of time-lapse photogrammetry for different applications of geomorphological change detection.

How to cite: Eltner, A., Blanch, X., Grothum, O., Epple, L., Lotsari, E., Anders, K., and Elias, M.: Applying photogrammetry to time-lapse imagery for geomorphological change detection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15001, https://doi.org/10.5194/egusphere-egu24-15001, 2024.

EGU24-15418 | ECS | Posters on site | GM3.2 | Highlight

A definition of land surface geomorphodiversity across different scales 

Martina Burnelli, Laura Melelli, Francesco Bucci, Michele Santangelo, Federica Fiorucci, and Massimiliano Alvioli

Geodiversity is “the variety of abiotic features and processes of the land surface and subsurface” [1,2]. Consensus is growing that geodiversity is the geosphere counterpart of what biodiversity represents within the biosphere, atmosphere, and hydrosphere [2]. Thus, it is potentially relevant to ecosystem functions and services [2]. Since the introduction of geodiversity, several scholars studied it from the theoretical and practical points of view, with different approaches, assumptions and purposes. Methods to define diversity of the geosphere are quantitative, qualitative, or a combination of the twos, with the occasional addition of heuristics [3].

Here, we describe a quantitative derivation of a subset of geodiversity, namely, geomorphodiversity. The effort stems from the need of an objective method, apt to providing easy to understand results, readily available for subsequent applications. To that end, requirements are in order about the data included in the analysis: they should be widely available, to allow reproduction of the analysis in most geographical locations, and they should contain enough information to approximate real-world geodiversity.

Geomorphodiversity is one implementation fulfilling the requirements, obtained in the literature by different groups, for different locations [4,5], using simple geomorphometry. Data for the method implemented in Italy [6] are a digital elevation model (EUDEM, 25 m resolution), and a lithological map at 1:100,000 scale [7]. DEM provides derived quantities such as slope, drainage network, landforms [8] and slope units [9], all of which contribute in different ways to produce partial diversity maps. We eventually combine partials into an overall geomorphodiversity raster index, GmI, distinguishing five classes of land surface diversity.

The inherent parameter dependence in the existing implementations of GmI, partially resolved in [6], is one issue to overcome. Free parameters are embedded in the size of neighborhoods (moving windows, or focal statistics) used to calculate the variety, the arbitrary output resolution, and procedures to polish the final raster diversity map from artifacts. We suggest a multiple assessment of the variety of partial abiotic parameters with a full range of different neighborhood sizes, and a-posteriori statistical selection of local values of diversity. This results in a parameter-free approach to GmI, also allowing a custom resolution of the output, with the lower bound of DEM resolution.

We consider a parameter-free geomorphodiversity as a measure of the potential of morphological evolution of the landscape, useful to investigate natural and human-induced diversity in urban areas [10], in combination with accurate, local mapping of geomorphological landforms [11].

 

References

[1] Gray, (2004) Geodiversity: valuing and conserving abiotic nature. ISBN 978–0–470-74215-0

[2] Schrodt et al., PNAS (2019) https://doi.org/10.1073/pnas.1911799116

[3] Zwoliński et al., Geoheritage (2018) https://doi.org/10.1016/B978-0-12-809531-7.00002-2

[4] Benito-Calvo et al, Earth Surf Proc Land (2009) https://doi.org/10.1002/esp.1840

[5] Melelli et al., Sci Tot Env (2017) https://doi.org/10.1016/j.scitotenv.2017.01.101

[6] Burnelli et al., Earth Surf Proc Land (2023) https://doi.org/10.1002/esp.5679

[7] Bucci et al., Earth System Science Data (2022) https://doi.org/10.5194/essd-14-4129-2022

[8] Jasiewicz et al., Geomorphology (2013) https://doi.org/10.1016/j.geomorph.2012.11.005

[9] Alvioli et al., Geomorphology (2020) https://doi.org/10.1016/j.geomorph.2020.107124

[10] Alvioli, Landscape and Urban Planning (2020) https://doi.org/10.1016/j.landurbplan.2020.103906

[11] Del Monte et al., Journal of Maps (2016) https://doi.org/10.1080/17445647.2016.1187977

How to cite: Burnelli, M., Melelli, L., Bucci, F., Santangelo, M., Fiorucci, F., and Alvioli, M.: A definition of land surface geomorphodiversity across different scales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15418, https://doi.org/10.5194/egusphere-egu24-15418, 2024.

EGU24-15904 | Orals | GM3.2

Mapping gold mines under the French Guiana rainforest: return of experience with different mobile lidar systems 

Thomas Dewez, Sébastien Linares, Silvain Yart, Florian Masson, Marie Collignon, Lucas Rivera, Caroline Bedeau, and Matthieu Chevillard

Gold is abundant in the greenstone belts of the Guiana shield, in South America, leading to alluvial mining in river sediments and in in-situ rocks. In French Guiana, legal mining takes place under strict environmental regulations and controls, but illegal operations also occur uncontrolled in the vast expanses of the rainforest. Here we describe a successful range of mobile lidar systems, acquisition schemes and processes to map the ground and underground mining operations in a rainforest context. We seek to detect illegal operations, supply and transportation pathways and base camps, using crewed planes and helicopters, uncrewed fixed-wing and multi-copter vehicles (UAV) and handheld lidar systems.

To sense ground elevation below the canopy, airborne lidar systems face three challenges: tree heights (some trees exceed 70 m in height), incised topography (requires performant terrain following capabilities), dark and wet ground surface largely absorbs lidar pulses requiring powerful sources. Tested uncrewed airborne vehicles (UAV) did not yet meet all of the flying autonomy, terrain-following capability, lidar range and on-board decision systems. At present, crewed systems adapt better to conditions and achieve mission objectives.

Over forested areas, observed canopy penetration rates is of the order of 1 ground point for 250 lidar pulses (0.4%). To generate a 1-m/pixel Digital Terrain Model (DTM) with a minimum of occluded pixels, acquisition density should exceed 250 pts/m² at canopy level everywhere. In Dorlin (central French Guiana), a helicopter flew 85-m-above ground-level, 70 % side-lap and 90° cross-lines, using a Riegl VUX-1LR lidar. Targeting 400 pts/m² at canopy-top for 95 % of the 220 ha territory, it reached a canopy-top density of 1400 +/- 750 pts/m² and 43 pts/m² ground density overall. On fully forested areas, ground density dropped to 22.4+/-22.6 pts/m² with 5% of the surface never receiving points at 1 m² level. This enabled interpolation of a 25cm/pixel DTM, which revealed narrow paths, quad tracks, and shaft platforms and head frames under the forest. 2-m kernel high-pass filtering enhanced features better than a standard hill shading. Base camp hut structures, invisible in DTM, are retrievable from native point clouds in a 4 to 5 m-above-ground elevation range. Huts covered in black tarpaulins stand out as rectangular hollow patches due to lidar photon absorption. But even without tarpaulin, hut wooden frames stand out particularly well when point cloud subsets are lit up with the PCV filter of Cloud Compare. Ore-bearing quartz stockpiles however are too small and occluded for a reliable detection and volume computation.

Instead, SLAM-based handheld lidar systems (GeoSLAM Zeb-Revo and Zeb-Horizon) complement the detailed mapping of quartz stockpiles volume, shaft conduit geometry and gallery entrances. Then real-time, SLAM-based quadcopter UAV lidar (Flyability Elios 3) safely penetrates shafts from the surface to explore the undergound gallery network. These new millimetre-scale density point clouds critically reveal spacing, orientation and dimensions of ore-bearing veins, which improves the metallogical understanding of the site and uniquely documents the way artisanal illegal miners operate.

Lidar acquisitions and processing are now being streamlined for systematic use in law enforcement operations and environmental protection actions.

How to cite: Dewez, T., Linares, S., Yart, S., Masson, F., Collignon, M., Rivera, L., Bedeau, C., and Chevillard, M.: Mapping gold mines under the French Guiana rainforest: return of experience with different mobile lidar systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15904, https://doi.org/10.5194/egusphere-egu24-15904, 2024.

EGU24-16317 | Orals | GM3.2

Debris flow catchments and landscape evolution in the northern Colombian Andes 

Edier Vicente Aristizábal Giraldo and Oliver Korup

Fans are cone-shaped depositional landforms composed of a mixture of sediments, mainly derived from debris flow processes at the catchment scale. In mountainous terrains located in humid climates, debris flows are fundamental agents of landscape evolution and a highly destructive natural hazard. In the northern Colombian Andes, fans have been traditionally occupied by human settlements, which has also produced a long history of disasters in many settlements located on fans. For example, a debris flow on November 13, 1985, devastated the city of Armero, killing approximately 22,000 people and causing economic losses totaling over $US 339 million. In 2017, the city of Mocoa was affected by a debris flow where 333 people died, 130 houses were destroyed, and 1461 were partially affected.

Debris-flow risk is likely to increase as a consequence of the increasing magnitude and frequency of extreme weather and rapid population growth over the past few decades. Hence, identifying fan spatial distribution and debris flow occurrences is important for land use planning. In this study, we implemented geomorphometric analyses in the northern Colombian Andes to understand debris flow occurrence in terms of landscape evolution. Using digital elevation models, fan inventory, morphometric parameters, and geomorphic indices associated with the drainage network at the catchment scale, the close interconnection between debris-flow hazards and landscape evolution is explained.

The results show a clear spatial pattern of fans location and debris-flow-prone basins with knickpoint upstream migration and transient-state catchments, those characterized by high values of Ksn, hypsometric index and constraint values of 𝛘. Those findings suggest that landscape evolution indexes could improve debris flow susceptibility assessment at regional scale.

How to cite: Aristizábal Giraldo, E. V. and Korup, O.: Debris flow catchments and landscape evolution in the northern Colombian Andes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16317, https://doi.org/10.5194/egusphere-egu24-16317, 2024.

EGU24-16412 | ECS | Orals | GM3.2

Deep-Image-Matching: an open-source toolbox for multi-view image matching of complex geomorphological scenarios 

Francesco Ioli, Luca Morelli, Livio Pinto, and Fabio Remondino

Geomorphometry and geomorphological mapping are essential tools for understanding landscape changes. The recent availability of 3D imaging sensors and processing techniques, including Artificial Intelligence, is offering interesting solutions for gemorphometric analyses and processes understanding. Photogrammetry stands as a pivotal image-based tool in geomorphology, enabling accurate 3D reconstruction of complex natural environments and effective tackling of multi-temporal monitoring challenges. A key step in photogrammetry is the identification of corresponding points between different images, traditionally achieved through the extraction and matching of local features such as SIFT and ORB. However, these methods face difficulties when using images of complex environments scenarios. Deep Learning (DL) methods have recently emerged as powerful tools to address challenges such as strong radiometric variations and viewpoint changes (Morelli et al., 2022; Ioli et al., 2023). However, their practical application in photogrammetry is hindered by the lack of libraries integrating DL matching into standard SfM pipelines.

The presentation will introduce the recently developed Deep-Image-Matching, an open-source toolbox designed for multi-view image matching using DL approaches, specifically tailored for 3D reconstruction in complex scenarios (https://github.com/3DOM-FBK/deep-image-matching). This tool can be used to achieve a 3D reconstruction with wide camera baselines and strongly varying viewpoints (e.g., with ground-based monitoring cameras), with datasets involving varying illumination or weather conditions typical of multi-temporal monitoring, with historical images, or in low-texture situations (e.g., snow or bare ice).

Deep-Image-Matching provides the flexibility to choose from a variety of local feature extractors and matchers. Supported methods include traditional local feature extractors, such as ORB or SIFT, as well as learning-based methods, such as SuperPoint, ALIKE, ALIKED, DISK, KeyNet + OriNet + HardNet, and DeDoDe. Matcher choices range from traditional nearest neighbor algorithms to state-of-the-art options like SuperGlue and LightGlue. Available semi-dense matching solutions include the detector-free matchers LoFTR and RoMa.

To handle high-resolution images, the tool offers a tiling process. In case of strong image rotations, such as aerial stripes, images are automatically rotated before matching. Image pairs for matching can be selected by exhaustive brute-force matching, sequential matching, low-resolution guided pairs selection, or global descriptor-based image retrieval. Geometric verification is used to discard outliers among matched features. The extracted image correspondences are stored in a COLMAP database for further processing (i.e. bundle adjustment and dense reconstruction) or can be exported in other formats useful for other open-source and commercial software.

The presentation will highlight how image-based geomorphometry and geomorphological mapping could benefit of the realized tool and how complex environmental scenarios (landslides, glaciers, etc.) could be analysed and monitored with the support of deep learning.

References:

Ioli, F., Bruno, E., Calzolari, D., Galbiati, M., Mannocchi, A., Manzoni, P., Martini, M., Bianchi, A., Cina, A., De Michele, C. & Pinto, L. (2023). A Replicable Open-Source Multi-Camera System for Low-Cost 4D Glacier Monitoring. Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci., 48, 137-144

Morelli, L., Bellavia, F., Menna, F., & Remondino, F. (2022). Photogrammetry Now and Then - From Hand-Crafted to Deep Learning Tie Points. Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci., XLVIII-2/W1-2022, 163–170

How to cite: Ioli, F., Morelli, L., Pinto, L., and Remondino, F.: Deep-Image-Matching: an open-source toolbox for multi-view image matching of complex geomorphological scenarios, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16412, https://doi.org/10.5194/egusphere-egu24-16412, 2024.

EGU24-18657 | ECS | Posters on site | GM3.2

Tailoring slope units delineation according to different natural phenomena for institutional land use planning at the regional scale 

Rossana Napolitano, Michele Delchiaro, Leonardo Maria Giannini, Claudia Masciulli, Giandomenico Mastrantoni, Marta Zocchi, Massimiliano Alvioli, Paolo Mazzanti, and Carlo Esposito

The Latium region (Central Italy) is currently updating the institutional hydro-geological plan, one of the main planning tools to prevent geo-hydrological hazard at regional scale. The plan focuses on landslides, erosion and hydraulic hazard assessment using both conventional and innovative approaches. This analysis required different scales of study, according to the different processes acting on slopes, and their broader physiographic context. In this multiscale approach, slope units represent the most suitable territorial units of analysis and mapping, considering their morpho-hydrological representativeness and scalability.

Slope units are a particular type of terrain units, characterized by internal homogeneity and external heterogeneity, delineated from a digital elevation model considering the natural setting of the territory. A widely used tool for slope unit delineation is the software ‘’r.slopeunits’’ [1,2]. The parameters controlling the delineation are both morphological and hydrological, derived from a digital elevation model. The software implements an iterative and adaptive process, depending on the aforementioned parameters, resulting in slope unit sets optimized for the local morphology. The accurate selection of input parameters requires careful consideration, but it also allows extra flexibility in defining the proper scale of the output slope unit map.

Here, we aim at obtaining a new way to select the values of the software’s input parameters, considering their relations with the different processes, to single out the proper scale of analysis. Specifically, we provide additional terrain analysis methods to find “good” parameter ranges, implemented in simple computer scripts that make use of r.slopeunits. The workflow is organized as follow. First, the geomorphological domains (i.e. hillslope, unchanneled, and fluvial domain) are discriminated by the implementation of the slope – area function, with the area weighed by the runoff values available from the GIS-based model BIGBANG [3]. Next, the flow paths related to the hillslope and unchanneled domains and related basins are hierarchized using Strahler ordering. Then, delineation of basins and half-basins for every path order is computed. Finally, implementation of zonal statistics functions on the half-basins of every path order and calculation of the parameters ranges that for slope unit delineation is performed.

Implementation of a multi – scale derivation of slope units with a range of input parameters, customized according to the type of natural phenomena (landslide, flooding, erosion etc.), allows an adaptive multi – scale approach, specific for each process, for a comprehensive multi-hazard evaluation. One of the future applications of the research is the application of this approach for the definition of ‘’buffer zones’’ covered by natural or semi-natural vegetation, capable of counteracting slope instabilities. In the context of the hazard and risk mitigation management, these outcomes could represent an efficient aid for regulating urban development in a proper and secure manner.

 

References

[1] Alvioli et al. (2016). Geosci Mod Dev, https://doi.org/10.5194/gmd-9-3975-2016

[2] Alvioli et al. (2020). Geomorphology, https://doi.org/10.1016/j.geomorph.2020.107124

[3] BIGBANG model, https://www.isprambiente.gov.it/pre_meteo/idro/BIGBANG_ISPRA.html

 

How to cite: Napolitano, R., Delchiaro, M., Giannini, L. M., Masciulli, C., Mastrantoni, G., Zocchi, M., Alvioli, M., Mazzanti, P., and Esposito, C.: Tailoring slope units delineation according to different natural phenomena for institutional land use planning at the regional scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18657, https://doi.org/10.5194/egusphere-egu24-18657, 2024.

EGU24-18943 | ECS | Posters on site | GM3.2

Reconstructing ancient coastal landscapes and sea-level stands in Southern Italy (Cilento coast): a geostatistical approach 

Alessia Sorrentino, Gaia Mattei, and Pietro Patrizio Ciro Aucelli

This research aims to obtain coastal paleo-environmental reconstructions through the analysis of direct and indirect paleo sea-level markers (SLMs, i.e., SLIPs, TLPs, MLPs) by GIS-aided geostatistics.  

In this work, we used classical SLMs combined with a caves inventory in the Cilento area in the Campania Region (Southern Italy). In this area, mainly characterized by carbonatic rocks, numerous emerged and submerged caves are present along active and fossil cliffs as evidenced in the papers of Antonioli et al., 1994 and Esposito et al., 2002.  

As reported in Ferranti, 1998 and Florea et al., 2007, coastal caves can be considered positively correlated to the glacial-hydro-eustatic sea-level oscillations, especially on the carbonatic substratum.  

Therefore, caves cannot be classified as sea-level markers (SLMs) strictu sensu, anyway, they can be considered as a mark of ancient sea-level position, especially when the occurrence of floor elevation is well-distributed all along the coast (in the case of areas characterised by homogeneous tectonic behaviour). In detail, in this work, the floor elevation of the cave entrances was correlated with tidal notches, wave-cut platforms, Lithophaga burrows, and marine deposits deriving both from previous knowledge and new direct and indirect surveys carried out through classic geomorphological investigations and using robotic technologies and remote sensing.  

All collected data were used to produce a specific geodatabase “PALEOScape (PALEO SeasCAPE)” (Sorrentino et al., 2023) structured based on international standards for sea-level studies. Caves information was obtained from an existing caves’ Inventory (Federazione Speleologica Campana; Russo et al., 2005) integrated by field surveys. Thanks to the well-documented tectonic stability of the area, it was possible to ascribe at the same age SLMs having the equal altimetric position.

These records were analysed by a geostatistical approach by correlating the cave entrances to known sea-level stands increasing the information available on paleo sea-level stands along the examined coast.

By integrating this approach with a new method for semi-automatic landform recognition and classification, it was possible to reconstruct ancient coastal landscapes related to known sea level stands, but also to some new altimetric positions not previously reported in the area.

REFERENCES

Antonioli, F., Cinque, A., Ferranti, L., & Romano, P. 1994. Emerged and Submerged Quaternary Marine Terraces of Palinuro Cape (Southern Italy). Memorie Descrittive Carta Geologica d’Italia, 52, 237–260.

Federazione Speleologica Campana https://www.fscampania.it/catasto-2/catasto/  

Ferranti, L. 1998. Underwater cave systems in carbonate rocks as semi-proxy indicators of paleo-sea levels. Il Quaternario-Italian Journal of Quaternary Sciences, 11(1), 41-52.

Florea, L. J., Vacher, H. L., Donahue, B., Naar, D. 2007. Quaternary cave levels in peninsular Florida. Quaternary Science Reviews, 26(9-10), 1344-1361.

Russo, N., Del Prete, S., Giulivo, I., Santo, A. 2005. Grotte e speleologia della Campania : atlante delle cavità naturali. Elio Sellino Editore.

Sorrentino, A., Maratea, A., Mattei, G., Pappone, G., Tursi, M. F., Aucelli, P. P. 2023. A GIS-based geostatistical approach for palaeo-environmental reconstructions of coastal areas: the case of the Cilento promontory (southern Italy). In 2023 IEEE International Workshop on Metrology for the Sea; Learning to Measure Sea Health Parameters (MetroSea) (pp. 488-493). IEEE.

 

How to cite: Sorrentino, A., Mattei, G., and Aucelli, P. P. C.: Reconstructing ancient coastal landscapes and sea-level stands in Southern Italy (Cilento coast): a geostatistical approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18943, https://doi.org/10.5194/egusphere-egu24-18943, 2024.

EGU24-20335 | ECS | Posters on site | GM3.2

 Bivariate mountain definition: a case study for the turkish mountain system  

Neslihan Dal and Tolga Görüm

Türkiye, 61% of which consists of mountains, has an extremely rugged topography. Anatolia, which is located in the collision zone of plates with different characteristics, exhibits a morphological character with different stages of mountain formation due to the Paleotectonic and Neotectonic movements it has been exposed to during geological times. In Anatolia, where the main physiographic character is mountains, the proportion and boundaries of mountains and mountainous areas have not been quantitatively defined and there has not been a geomorphometric approach to this until now. In this study, the mountain definition obtained from the pixel-based and multi-scale basic data matrix was subjected to various analyzes with the modeling created in geographic information systems. In addition, how the mountain definition and classification change at varying scales and thresholds is revealed.

The characterization has two main purposes: To determine the framework of the methodology in the definition of macro landforms and to determine the most optimum model that quantitatively defines mountain and mountainous area. According to the model, mountains cover 61% of Türkiye. In this context, in addition to developing a model to geomorphometrically define mountain and mountainous area characterization, the thesis approaches mountains, which are a macro morphological landform, from an ontological perspective and approaches the questions we asked at the beginning in terms of geographical epistomology. In this respect, the thesis is a contribution to traditional geomorphology.  A bivariate map of 16 classes to visualize the relationships between morphological variables and a combination of mean elevation and topographic relief classifies mountains. The classification shows a transition from low rugged and low mountains, to moderate rugged and moderate height mountains, to high rugged and high mountains, to very high rugged and very high mountains. Within the framework of the classification, according to four different ruggedness ratios in Türkiye, low rugged mountains occupy 37%, moderate rugged mountains 33%, high rugged mountains 20% and very high rugged mountains 9%.

How to cite: Dal, N. and Görüm, T.:  Bivariate mountain definition: a case study for the turkish mountain system , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20335, https://doi.org/10.5194/egusphere-egu24-20335, 2024.

EGU24-20923 | Orals | GM3.2

Do Mature, Fluvial Landscapes Obey Hamilton's Principle? 

Scott D. Peckham

Students of physics typically take a theory course on classical mechanics in which they learn about Hamilton's Principle and how it can be used to derive many well-known physical laws that describe the motion of objects from particles, to light rays, to celestial bodies, including Newton's laws and Snell's Law from geometrical optics.  This powerful principle has also been shown to apply to fields (i.e., continuous systems) such as the electromagnetic and gravitational fields, and it is a foundational concept in quantum physics.  Hamilton's principle states that the dynamics of a physical system will optimize a functional (in our case, an integral over a spatial domain) of the system's Lagrangian, which is typically the difference between its kinetic and potential energies.  Many previous authors have postulated that fluvial landscapes may evolve in such a way that local and/or global kinetic energy dissipation or stream power is minimized, and this is the basis of the optimal channel network (OCN) simulation models that have been widely studied.  However, Hamilton's Principle suggests that these formulations are lacking an important piece, namely the global introduction of potential energy into the fluvial system by rainfall.  The author will show that by introducing this missing piece, Hamilton's Principle and the Euler-Lagrange theorem lead to a partial differential equation (PDE) for idealized, steady-state landforms.  This same PDE can also be derived from conservation of mass and an empirical slope-discharge formula.  These connections therefore point to a new theoretical framework for understanding the interplay between function and form in mature, fluvial landforms;  that is, an explanation for why these landforms take the forms we observe.  The author will also present ideas and algorithms for analyzing digital elevation models (DEMs), in an effort to test for agreement with Hamilton's principle.

How to cite: Peckham, S. D.: Do Mature, Fluvial Landscapes Obey Hamilton's Principle?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20923, https://doi.org/10.5194/egusphere-egu24-20923, 2024.

EGU24-22282 | ECS | Orals | GM3.2

A data-driven approach to understanding esker morphogenesis 

Meaghan Dinney and Tracy Brennand

Eskers are ubiquitous features on previously glaciated landscapes, recording the configuration and dynamics of the channelized meltwater system. Studies of esker composition and form have resulted in a variety of genetic interpretations surrounding the ice, water, and sediment characteristics under which they may develop. However, issues of apparent equifinality currently limit the usefulness of eskers for reconstructing broad-scale glacial hydrology. Although some authors have attempted to asses esker morphogenesis, previous studies are limited by their small sample size and/or use of qualitative morphometric indices.

This project aims to explore whether eskers have a distinct morphogenetic signature using data science techniques. Published research has been mined for empirical studies of esker composition and structure. These data were compiled into a database summarizing the genetic interpretations commonly invoked for eskers (e.g., depositional environment, meltwater flow regime) as well as the supporting evidence for such inferences (e.g., sedimentary logs). Semi-automated methods will be tested to map eskers from high resolution (1-2 metres) LiDAR digital terrain models and to extract their morphometry. A range of planform- and profile-scale morphometric indices will be employed and new indices that can more precisely quantify esker morphometry will be developed.

The resulting highly-dimensional dataset can be analyzed using machine learning techniques in order to assess the relationships between sedimentologic, morphometric, and genetic variables. Preliminary results from database development and analysis will be presented and methodological concerns will be discussed.

How to cite: Dinney, M. and Brennand, T.: A data-driven approach to understanding esker morphogenesis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22282, https://doi.org/10.5194/egusphere-egu24-22282, 2024.

EGU24-720 | ECS | Posters on site | BG3.18

An adaptive mapping framework for the management of peat soils: a new Irish Peat Soils Map. 

Louis Gilet, Terry Morley, Raymond Flynn, and John Connolly

Accurate mapping is necessary for effective management of peat soils to help reduce GHG emissions and improve environmental quality. However, mapping peat soils remains a major challenge: definitions of peat soils vary substantially, field data are sparse and difficult to produce, and remote sensing of limited use for converted peatlands. Using an Adaptive Mapping Framework developed for the Derived Irish Peat Map, this study describes our work to update the map with refined and new datasets. These include incorporation of areas considered to be underlain by shallow peat soils (≥ 10 cm and ≥ 8.6 % Organic Matter content), and augmentation of the overall test dataset with an additional ~ 20,000 points.

The workflow for map generation employed 20 Decision Tree Output Maps (DTOMs), aggregated into 33 Map Combinations (MCs). The MC selected for the update had the highest accuracy metrics (≥ 80 %), consisting of DTOMs with a user accuracy ≥ 60 % and assessed over a minimum number of test points ≥ 50. The resulting map reveals peat to underlie 1.66 M ha of Ireland (~ 23.3 % of the country), with an overall accuracy of 84 % and a F1 score for peat areas of 85 %. This extent is 13.2 % larger than that delineated in previous versions and at least 18.8 % larger than areas presented in other previous maps. The methodology also allows transparency from which data sources the different peat layers of the new map are coming from and to distinguish different peat thickness ranges (≥ 10 cm, ≥ 30-40 cm).

We demonstrate the utility of the mapping framework to facilitate the production of a more reliable peat map than previous mapping attempts. This approach has potential relevance for peat mapping elsewhere, in areas containing disparate datasets (e.g., land cover, soil map, etc.), covering different time periods, or employing different production methods. The accuracy metrics generated also suggest that the approach can be used as a basis for implementing or updating European and national regulations concerning carbon-rich soils in comparable settings to those encountered in Ireland.

How to cite: Gilet, L., Morley, T., Flynn, R., and Connolly, J.: An adaptive mapping framework for the management of peat soils: a new Irish Peat Soils Map., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-720, https://doi.org/10.5194/egusphere-egu24-720, 2024.

EGU24-1164 | Posters on site | BG3.18 | Highlight

Long-term interventions by conservation and development projects support successful recovery of tropical peatlands in Amazonia 

Euridice Honorio Coronado and the Research team

Sustainable management of non-timber forest products, as a means to increase the value of standing forest, has long been a goal of conservation in the tropics. However, there are few studies of the long-term ecological, social, and economic impacts of sustainable management initiatives. This study addresses this issue in the context of fruit harvesting of the arborescent palm, Mauritia flexuosa. In Amazonia, M. flexuosa grows naturally at high densities in carbon-rich peatland ecosystems and its fruit is an important resource for local communities. Typically, the fruit has been harvested by felling the trees. However, over recent decades, some communities have adopted climbing techniques to harvest the fruits. We analyse for the first time the potential of M. flexuosa populations and fruit production to recover in two rural communities in Peruvian Amazonia where climbing palms was adopted between 1999 and 2002. Since then, these communities have been supported by conservation and development projects.

In both communities, we conducted interviews to assess the perceptions of change after the introduction of climbing and carried out forest inventories to estimate changes in two socio-economic indicators (volume of harvested M. flexuosa fruits and income) and three ecological indicators (pole stem density of M. flexuosa, seedling and sapling density, and the sex ratio of adult palms). Our results highlight the positive impacts of the use of climbing to harvest fruits on a range of both ecological and socio-economic indicators in these communities. These results demonstrate that sustainable fruit production is a viable way to conserve the forests, the high carbon stocks beneath the ground and the livelihood of people living in these ecosystems. These findings therefore will be of interest to a wide range of researchers, policymakers, and practitioners seeking to promote sustainable practices in these, and similar, ecosystems across the world and provide support for community-led conservation across the tropics.

How to cite: Honorio Coronado, E. and the Research team: Long-term interventions by conservation and development projects support successful recovery of tropical peatlands in Amazonia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1164, https://doi.org/10.5194/egusphere-egu24-1164, 2024.

EGU24-2171 | Orals | BG3.18

Flark area monitoring in boreal aapa mires using multi-resolution optical remote sensing 

Kaapro Keränen, Aleksi Isoaho, Aleksi Räsänen, Jan Hjort, Timo Kumpula, Pasi Korpelainen, and Parvez Rana

Peatlands have globally suffered significant degradation due to human activities which has necessitated monitoring of the condition of and changes in peatland ecosystems. With remote sensing, point-based in-situ observations can be upscaled to larger areas but there is a need to develop scalable monitoring methods. We hypothesize that the upscaling can be conducted by combining multispectral uncrewed aerial vehicle (UAV) and optical satellite imagery observations. We tested the hypothesis in predicting wet flark area extent, a key ecological indicator for patterned aapa mires with flarks, in five sites in central Finland. We asked: 1) How does the spatial and spectral resolution of widely used optical satellite image sensors (Landsat 8-9, Sentinel-2, and PlanetScope) influence flark area coverage prediction? 2) Are there seasonal and site-specific differences in prediction accuracy? 3) Is it feasible to upscale flark area coverage to larger mire areas? We employed UAV-derived flark area classification as a ground reference to compare predictive accuracy of satellite imagery data. We predicted flark area coverage using spectral bands and indices as explanatory variables in random forests regressions. Our findings revealed that all sensors provide accurate results, but there were differences in explanatory capacities between Landsat (pseudo-R² 32−84%, root-mean squared error (RMSE) 10−18%), Sentinel-2 (R² 61−92%, RMSE 6−14%), and PlanetScope (R² 46−92%, RMSE 6−17%) data. The shortwave infrared bands of Landsat and Sentinel-2 did not increase the prediction accuracy. There were notable site-specific variations in prediction accuracy despite all the sites having typical aapa mire wet flark–dry string patterns. With single-site models the prediction accuracies were similar for early and late summer conditions, but when transferring the models to the other sites, performance decreased considerably, especially with the models constructed with the late-summer imagery. Finally, we successfully upscaled the single-site models to detect flark area coverage across entire mire areas. Our results demonstrated that UAV-satellite image combination can be used to track key indicators of peatland conditions and monitoring changes in them.

How to cite: Keränen, K., Isoaho, A., Räsänen, A., Hjort, J., Kumpula, T., Korpelainen, P., and Rana, P.: Flark area monitoring in boreal aapa mires using multi-resolution optical remote sensing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2171, https://doi.org/10.5194/egusphere-egu24-2171, 2024.

EGU24-2944 | ECS | Orals | BG3.18

Investigating the Kuan Kreng Peat Swamp Forest using Electrical Resistivity and Ground Penetrating Radar for Carbon Stock Estimation 

Theethach Phiranram, Piyaphong Chenrai, Akkaneewut Jirapinyakul, and Narongsak Rachukan

Peatlands, also known as bogs, fens, and especially peat swamp forests in tropical regions, are wetland ecosystems where peat layers are present due to anoxic conditions. Immense amounts of carbon are stored in peat layers, making it an important carbon sink for atmospheric carbon and playing a major role in carbon cycle. These peat layers are vulnerable to becoming a carbon emission source due to the disturbance of the peat layer by natural and anthropogenic processes. Southern Thailand comprises several peatlands that have encountered degradation due to cultivation and forest fires, especially the Kuan Kreng peat swamp forest, which is the second largest peatland in Thailand and serves for carbon storage. To evaluate the impact of peatland degradation, carbon stock estimation is necessary; thus, the thickness and distribution of the peat layers are necessary. This study utilizes ground penetrating radar and electrical resistivity imaging, along with conventional core studies, to investigate physical and chemical characteristics and also delineate peat layer.

Significant relationships between chemical and physical properties of the peat layer are represented, which is useful for geophysical interpretation. The resistivity profiles show a high resistivity response, in the range of 21.9 to 145.0 ohm-m, which is interpreted as peat layers in the shallow subsurface. The high amplitude, contorted to sub-parallel reflection from GPR profiles, represents a peat layer that has a relatively lowest velocity with the highest dielectric constant. In order to evaluate carbon stock, average values of bulk density (0.19 g/cm­3) and TOC (31.18 wt. %) from the drilling core samples are advocated, resulting in 59.24 Kg C/m3 of carbon density. Then the peat layer average thickness of 18.00 cm from the geophysical survey and core samples are used to estimate the carbon stock per unit area. Therefore, considering the entire area of the Kuan Kreng peat swamp forest, the carbon stock is estimated at a minimum of 7.53 Mt.

How to cite: Phiranram, T., Chenrai, P., Jirapinyakul, A., and Rachukan, N.: Investigating the Kuan Kreng Peat Swamp Forest using Electrical Resistivity and Ground Penetrating Radar for Carbon Stock Estimation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2944, https://doi.org/10.5194/egusphere-egu24-2944, 2024.

EGU24-3219 | ECS | Posters on site | BG3.18

Peat soil thickness and carbon storage in the Belgian High Fens: insights from multi-sensor UAV remote sensing 

Yanfei Li, François Jonard, Maud Henrion, Angus Moore, Sébastien Lambot, Sophie Opfergelt, Veerle Vanacker, and Kristof Van Oost

Peatlands are known to store a large amount of carbon, but global warming and associated changes in hydrology have the potential to accelerate peatland carbon emissions. An in-depth understanding of carbon dynamics within these peatlands is therefore important. However, peatlands are complex ecosystems, and acquiring accurate and reliable estimates of how much carbon is stored underneath the Earth’s surface is inherently challenging even at small scales. Here, Unmanned Aerial Vehicles (UAVs) equipped with RGB, multispectral, thermal infrared, and LiDAR sensors were combined with Ground Penetrating Radar (GPR) technology and traditional field surveys, to provide a comprehensive 4D monitoring of a peatland landscape in the Belgian High Fens. Data was collected along a hillslope-floodplain transition. We aimed to establish links between the above- and below-ground factors that control soil carbon status, identify the key drivers of carbon storage as well as explore the potential of UAV remote sensing for spatial mapping of peat depth and carbon stock. Our results indicated that peat thickness widely varied (0.2 to 2.1 m) at small scales and is negatively correlated with elevation (r= -0.39, p<0.001). We found that soil organic carbon (SOC) stock is spatially organized, as abundant carbon was observed at the summit and shoulder of the hill, with an average storage of 670.93 ± 108.86 t/ha and 601.47 ± 133.40 t/ha, respectively. Moreover, the carbon storage exhibited heterogeneity under different vegetation types, with trees having the highest mean SOC stocks at 722.21 ± 37.92 t/ha. Through multiple linear regression, we identified 6 environmental variables that can explain 71.44% of SOC stock variance. Clay content is the most critical factor, accounting for nearly 40% of the variance, followed by topography. Contributions from land surface temperature and vegetation remain below 10%. In addition, UAV data provided accurate estimations of both peat depth and SOC stock, with RMSE and R2 values of 0.13 m and 0.88 for the peat depth test dataset, and 114.42 t/ha and 0.84 for the SOC stock. Our study bridged the gap between surface observations and the hidden carbon reservoir below, this not only allows us to improve our ability to assess the spatial distribution of C stocks but also contributes to our understanding of the drivers of C turnover in these highly heterogeneous landscapes, providing insights for environmental science and climate projections.

How to cite: Li, Y., Jonard, F., Henrion, M., Moore, A., Lambot, S., Opfergelt, S., Vanacker, V., and Van Oost, K.: Peat soil thickness and carbon storage in the Belgian High Fens: insights from multi-sensor UAV remote sensing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3219, https://doi.org/10.5194/egusphere-egu24-3219, 2024.

EGU24-4700 | Posters on site | BG3.18

Large CO2 and CH4 emissions from drainage ditches in oil palm plantations on peat soil 

Kuno Kasak, Kaido Soosaar, Iryna Dronova, Lulie Melling, Gx Wong, Faustina Sangok, Reti Ranniku, Jorge Villa, and Ülo Mander

Tropical peatlands contain approximately 17% of the total global peat carbon and are under pressure for deforestation and the formation of oil palm plantations. The conversion of large peatland forests in Malaysia and Indonesia has resulted in these plantations becoming substantial sources of greenhouse gases. While previous research has focused on estimating the C loss from the soil, the impact of drainage ditches on the overall C budget remains largely unexplored. However, on average, drainage ditches with free surface water cover roughly one-third of the total drained land. Hence, these ditches could be significant CO2 and CH4 sources and while not considered for C budget calculation it could lead to significant underestimation of total C loss from these ecosystems. Here we represent the CO2 and CH4 emissions from drainage ditches in an oil palm plantation located in Sarawak, Malaysia. CO2 and CH4 samples (n=107) were collected from a recently created plantation (~5 y.o.) and from the plantation, which is under second rotation using a floating chamber and LI7810 analyzer (LICOR Biosciences). Additional parameters such as water pH, electrical conductivity, dissolved oxygen concentration, temperature, turbidity, salinity, water level, and dissolved gas concentration (dCO2 and dCH4; analyzed in the lab with GC-2014, Shimadzu) were measured from each sampling spot. After measurements, we collected sediment samples for soil TN, TOC, TIC, DOC, DIC, and DN analyses. The results revealed that the average net CH4 flux (combining both diffusive and ebullitive emissions) from drainage ditches in the first and second rotations was 0.31 ± 0.65 g m-2 d-1 and 0.29 ± 0.54 g CH4-C m-2 d-1, respectively. The average CO2 flux from the first and second rotations was 4.27 ± 2.1 g CO2-C m-2 d-1 and 4.4 ± 2.5 g CO2-C m-2 d-1, respectively. To estimate surface water coverage at the whole site, green vegetation, open water, and bare soil were mapped from the site drone imagery collected in Spring 2023 using object-based supervised classification and spectral indicators computed from red, green, and blue image bands. The total surface water coverage will give us an understanding of the total CO2 and CH4 flux in the entire region that originates from drainage ditches. Our results strongly underscore the significant role of drainage ditches in contributing to the overall carbon loss from oil palm plantations on organic soils. Proper consideration of these emissions is essential for accurate carbon budget calculations and for devising effective strategies to mitigate greenhouse gas emissions in these ecosystems.

How to cite: Kasak, K., Soosaar, K., Dronova, I., Melling, L., Wong, G., Sangok, F., Ranniku, R., Villa, J., and Mander, Ü.: Large CO2 and CH4 emissions from drainage ditches in oil palm plantations on peat soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4700, https://doi.org/10.5194/egusphere-egu24-4700, 2024.

Northern peatlands provide key climate regulating services by sequestering and storing atmospheric carbon as peat, but they also harbour highly specialized plant and animal species. Yet, 50% of peatlands in the European Union are currently degraded. To understand the effect of recent restoration efforts on habitat suitability and peat accumulation rate, there is a need to develop and refine efficient and standardised methods that can effectively target the multiple ecosystem services that peatlands provide. Given the spatial characteristics of peatlands, as well as the direct link between vegetation structure and peatland functioning, vegetation mapping with unmanned aerial vehicles or drones is ideal for such tasks.

For this study, we collected very-high-resolution drone imagery (2.8cm) of five Irish peatlands (ranging between 35–124 ha) in September 2022. We then used Random Forest classifiers to map fine-scale vegetation patterns (microform and plant functional type) in all peatlands using the resulting remote sensing products. Hereafter we subdivided and labelled each peatland into 20x20m grid cells using polygon-shaped field-based ground truth maps of peatland, and classified large-scale peatland habitats (ecotopes, and status or Active versus Degraded Raised Bog) with Support Vector Classifiers while using the proportions of microforms and plant functional types and topography as input datasets. Lastly, we assessed model performance and mapping accuracy between models trained on a singular peatland to those trained using a pooled ground truth dataset from the four other peatlands to evaluate the spatial transferability of habitat mapping over multiple peatlands.

Our results highlight that model performance for fine-scale vegetation patterns were consistently high (>90%) for all peatlands. Subsequent classifications of peatland habitats were also relatively consistent for singular peatlands with overall model performances of 73.0% and 89.3% for ecotopes and status respectively. Nevertheless, we observed notable reductions in overall model performances of 11.0% and 6.2% using pooled ground truth datasets. Inconsistencies in classification models resulted largely from artificial landscape features created by restoration, sun and shading, variation in plant phenology, suboptimal elevation models, and development of a gridded ground truth dataset from an original polygon-shaped and field-based map.

Our findings highlight that fine-scale vegetation patterns and peatland habitats can be classified accurately and consistently on the scale of whole peatlands using drone-derived imagery products and machine learning classifications. Our study provides comprehensive and novel insights into the multiple requirements for accurate vegetation mapping on which future drone studies can build to further optimize and standardise monitoring of vegetation dynamics in a wide variety of peatlands and peatland types of contrasting eco-hydrological integrity.

How to cite: Steenvoorden, J. and Limpens, J.: Towards efficient and standardised large-scale monitoring of peatland habitats through fine-scale drone-derived vegetation mapping, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5078, https://doi.org/10.5194/egusphere-egu24-5078, 2024.

EGU24-6027 | Orals | BG3.18

Sphagnum peatlands of Reunion Island: potential and limitations as environmental archives for the Quaternary of the Indian Ocean. 

Gaël Le Roux, Claudine Ah-Peng, Rongqin Liu, Oskar Hagelskjaer, Henar Margenart, Jeroen Sonke, Sophia V. Hansson, Natalia Piotrowska, Corinne Pautot, Pieter Van Beek, Thomas Zambardi, Marc Souhault, François De Vleeschouwer, Laurent Bremond, Fabien Arnaud, Laure Gandois, Dominique Strasberg, and David Beilman

Contrary to temperate and boreal peatlands built after the glacial retreat, tropical peatlands are potentially recording environmental information pre-dating the Holocene. However on tropical volcanic islands, Sphagnum moss are scarce and/or rarely build peat.

Within the framework of the several projects on the territory of Reunion Island, we sampled peat bogs and Sphagnum mats of Reunion Island in 2021 (Margenat and Le Roux, 2023). The objectives were originally to use them as microplastic traps and thus reveal the history of atmospheric contamination by microplastics in the Indian Ocean over the last fifty years. It turns out some peat cores are older than expected and can provide amazing archives for the Holocene and Last Glacial environmental history of the Indian Ocean and La Réunion Island itself including the last period of strong volcanic activities. For example, one site located in the heart of the National Park is 25 ky old.

In this talk, we will present the diversity of the Sphagnum peatlands of La Réunion, the first results of peat characterization, and the first results of radiometric age dating covering the last glacial maximum, the Holocene, and the most recent periods. We will then discuss potential and limitations of La Réunion peat records in paleo-landscape, paleo-atmosphere and carbon cycle aspects.

 

References:

Margenat, H., Le Roux, G., 2023. POST EXPEDITION REPORT Field Expedition La Réunion Island, France ATMO-PLASTIC Project. Zenodo. https://doi.org/10.5281/zenodo.7643599

 

How to cite: Le Roux, G., Ah-Peng, C., Liu, R., Hagelskjaer, O., Margenart, H., Sonke, J., Hansson, S. V., Piotrowska, N., Pautot, C., Van Beek, P., Zambardi, T., Souhault, M., De Vleeschouwer, F., Bremond, L., Arnaud, F., Gandois, L., Strasberg, D., and Beilman, D.: Sphagnum peatlands of Reunion Island: potential and limitations as environmental archives for the Quaternary of the Indian Ocean., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6027, https://doi.org/10.5194/egusphere-egu24-6027, 2024.

EGU24-6028 | Orals | BG3.18

Using JULES to Model the Congo Peatlands 

Peter Anthony Cook, Richard Betts, Sarah Chadburn, and Eleanor Burke

The Cuvette Centrale swamp forest around the Congo has the most extensive peatland complex in the tropics, but due to its remoteness the extent and depth of the peat was only recently determined.  The international project CongoPeat has researchers from the UK, the Republic of the Congo and the Democratic Republic of the Congo, working alongside the local people in studying the peatlands to determine how they formed and the possible threats since it is vital that the peat is preserved.  While the peatlands are at least 20,000 years old the peat is thin compared to other tropical peatlands of similar age.  The JULES land surface model has been driven by a reconstruction of the past annual rainfall and meteorological data from a HadCM3 paleo global model to simulate the development of the peatlands.  The model results closely match measurements from the CongoPeat fieldwork and support the hypothesis that a long period of reduced rainfall a few thousand years ago lead to a large loss of peat.  This confirms that a consistently high water table is needed to keep decomposition of the peat to a minimum and hence preserve the peatlands.  Though JULES was unable to recreate the measured Carbon age profile, whereas simpler peat models did, this is only due to its low vertical resolution.  The JULES run was then continued with future climate projections from four global climate models to simulate how the peatlands are likely to change up to 2100.  In each projection there are lower water tables and increased decomposition of peat, but large losses only occur when rainfall is reduced or when drainage is introduced to represent disruption of the peatlands, both of which further lower the water tables.  This is in-spite of increased CO2 concentration affecting the vegetation by increasing the productivity and litterfall while reducing the amount of transpiration.

How to cite: Cook, P. A., Betts, R., Chadburn, S., and Burke, E.: Using JULES to Model the Congo Peatlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6028, https://doi.org/10.5194/egusphere-egu24-6028, 2024.

EGU24-7452 | Posters on site | BG3.18

How does land use change impact tropical peatland surface elevation changes?  

Daniel Murdiyarso, Meli F Saragi-Sasmito, Sigit D Sasmito, Nyahu Rumbang, and Adi Jaya

Tropical peat swamp deforestation followed by extensive drainage and recurrence of fires leads to peat subsidence and subsequently carbon release to the atmosphere. While many previous studies have assessed the positive relationship between greenhouse gas (GHG) emissions and peat subsidence, an accurate field-based measurement of peat subsidence remains methodologically challenging. Between 2015 and 2020, we monitored peat subsidence (surface elevation change) in tropical peatlands of Central Kalimantan by using Rod Surface Elevation Table (RSET) installed across 22 locations representing range of land use types, including natural forest as reference. We observed that the largest net surface elevation loss was found in burned areas of -35.1 ± 87.2 mm yr-1, followed by the drained peatland sites with -11.1 ± 16.9 mm yr-1 and the agricultural impacted sites with -6.3 ± 13.1 mm yr-1. Further, we observed substantial net surface elevation loss in secondary protected forests by -12.1 ± 77.2 mm yr-1. By contrast, natural forest reference experienced net surface elevation loss as much as -8.8 ± 24.4 mm yr-1. Our findings suggest that all the study sites in the tropical peatlands of Central Kalimantan have experienced net surface elevation loss with their degree of losses vary depending on past land use and current land management.

Keywords: peat subsidence, peat compaction, peat drainage, peat conversion, GHG emission

How to cite: Murdiyarso, D., Saragi-Sasmito, M. F., Sasmito, S. D., Rumbang, N., and Jaya, A.: How does land use change impact tropical peatland surface elevation changes? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7452, https://doi.org/10.5194/egusphere-egu24-7452, 2024.

EGU24-7914 | Orals | BG3.18 | Highlight

The climate impact of tropical peatland degradation 

René Dommain, Steve Frolking, Aurich Jeltsch-Thömmes, Fortunat Joos, John Couwenberg, Paul Glaser, Alexander Cobb, and Charles Harvey

Southeast Asia is a global hotspot of peatland degradation and related greenhouse gas emissions. Anthropogenic impacts, mainly associated with agricultural conversion, shift Southeast Asian peatlands from carbon sinks to significant carbon sources. Here we first describe the impacts of anthropogenic drainage on landscape-scale carbon dynamics of individual peatlands and then use an impulse‐response model of radiative forcing to quantify the climate impacts of peat-carbon losses. Whereas water-table elevation (i.e. drainage depth) determines the magnitude of CO2 emissions at the site-scale, the geometric arrangement of artificial drainage networks determines carbon losses on the landscape-scale. Among all peatland greenhouse gas fluxes, the rapid release of large quantities of CO2 with lowered water tables has the greatest impact on atmospheric radiative forcing. While peat accumulation in undisturbed peatlands produces a slowly increasing net radiative cooling, drainage, within decades, causes a shift in radiative forcing to a positive atmospheric perturbation (i.e. net warming), which can persist for centuries to millennia. The pace of this shift in radiative forcing and the magnitude and duration of the warming effect depend on the age and carbon pools of peatlands.

How to cite: Dommain, R., Frolking, S., Jeltsch-Thömmes, A., Joos, F., Couwenberg, J., Glaser, P., Cobb, A., and Harvey, C.: The climate impact of tropical peatland degradation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7914, https://doi.org/10.5194/egusphere-egu24-7914, 2024.

EGU24-8359 | Orals | BG3.18

Leveraging hydrological constraints on bog morphology to better map raised peatlands 

Alex Cobb, René Dommain, Kimberly Yeap, Cao Hannan, Nathan C. Dadap, Bodo Bookhagen, Paul H. Glaser, and Charles F. Harvey

Raised peatlands, or bogs, are recognized as exceptionally carbon-dense terrestrial ecosystems in which peat accumulates into convex shapes that rise above their boundaries. Because of this convexity, bogs are vulnerable to artificial drainage, and mapping them is important to evaluate whether and how to protect or restore their carbon stocks. Recently, we showed that hydrological constraints create a pattern in the morphology of bogs that holds under a broad range of conditions, as illustrated by eight examples of bogs from northern, through tropical and further to southern latitudes. Specifically, we found that if bog surface elevation, mean water table elevation and transmissivity are related to one another in similar ways across a bog, the relationships among these variables define a bog-specific monotonic function that generates the bog morphology from a solution to Poisson’s equation. This pattern is like a signature for raised bog morphology, and could be used to help identify the boundaries of raised bogs. In addition, the pattern can be used to infer the full morphology of bogs from limited data, which in turn enables estimation of a bog’s stock of vulnerable carbon. We discuss how these findings can be combined with field and remote sensing data to better map the extent and vulnerable carbon stocks of raised peatlands around the world.

How to cite: Cobb, A., Dommain, R., Yeap, K., Hannan, C., Dadap, N. C., Bookhagen, B., Glaser, P. H., and Harvey, C. F.: Leveraging hydrological constraints on bog morphology to better map raised peatlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8359, https://doi.org/10.5194/egusphere-egu24-8359, 2024.

EGU24-9398 | Posters on site | BG3.18

Integrating UAS-based lidar data in eddy covariance flux footprint modelling 

Jan Rudolf Karl Lehmann, Visweshwar Arulmozhi Nambi, Laura Giese, Hanna Meyer, and Mana Gharun

Peatlands, covering 3% of the global land area, store twice the carbon of all the world's forests combined, acting as crucial carbon sinks. However, under varying environmental conditions induced by global warming and land cover changes, they can transition into carbon sources. Monitoring gas exchanges in peatland ecosystems involves employing the eddy covariance method, often interpreted using flux footprint models. This study focuses on the application of the FFP model, specifically addressing the influence of spatially varying roughness parameters.

Utilizing Unoccupied Aerial Vehicle (UAS)-based high-resolution LIDAR data, we incorporated spatially varying roughness values into the FFP model, comparing the results with traditional scalar roughness length values. Our findings reveal that spatially varying roughness introduces spatial heterogeneity, resulting in more irregular and smaller footprints. The inclusion of spatially varying roughness based on the surface reduced the area contribution to fluxes by 40%, emphasizing the significance of accounting for this spatial variability.

Moreover, we investigated the impact of surface and terrain conditions on footprint modeling in a peatland previously subjected to extraction. Our analysis indicates that variations in terrain (both natural and extraction-induced) reduced the footprint contours by 18% compared to the original FFP model footprints. This underscores the importance of considering terrain changes in footprint modeling, especially in peatlands with a history of extraction activities.

In conclusion, this research enhances our understanding of (1) the impacts of spatially varying roughness on modeled footprints and (2) the influences of surface and terrain on footprint size in peatland ecosystems. These insights contribute to improved modeling accuracy and aid in effective carbon management strategies for peatland conservation.

How to cite: Lehmann, J. R. K., Arulmozhi Nambi, V., Giese, L., Meyer, H., and Gharun, M.: Integrating UAS-based lidar data in eddy covariance flux footprint modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9398, https://doi.org/10.5194/egusphere-egu24-9398, 2024.

EGU24-10580 | Orals | BG3.18

Mapping and characterizing peatland using ground-penetrating-radar and nuclear-magnetic-resonance 

Mike Müller-Petke, Bárbara Blanco Arrué, Jan Igel, Tobias Splith, and Stephan Costabel

Peatlands are of importance for a number of environmental services and ecological processes. They are a crucial component of the global carbon cycle and, therefore, of special interest in times of climate change. On the one hand, drained peatlands irreversibly degenerate when used for agriculture and lose their physicochemical functionality. On the other hand, activities on renaturation or joint use are in discussion or already in practice. Consequently, there is a demand for knowledge of the state of the peat layers and for the ability to monitor their changes, most preferably in high detail and on a large scale. Airborne geophysics and remote sensing (e.g. optical images, radar or electromagnetics) are  approaches to gain large-scale information on the lateral extend of peatlands, however, covering the large scale comes along with limitations and uncertainties on knowledge about thickness, internal structure, or degradation states.

We conducted a ground-penetrating-radar (GPR) and nuclear-magnetic-resonance (NMR) survey at a peatland site in northern Germany, which has been in agricultural use for decades. The site is characterized by a peat layer of varying thicknesses between 0--4 m covering mineral sediments. While GPR provides a fast 3D insight into the internal structure, extent, and thickness, NMR enables the characterization of the internal layers detected by GPR in more detail and may provide information on their degradation states. The results are compared to visually inspected vertical soil sampling data. Our study demonstrates that ground-based geophysics can provide the demanded detailed information and may easily be upscaled to effectively cover areas at the kilometre scale.

How to cite: Müller-Petke, M., Blanco Arrué, B., Igel, J., Splith, T., and Costabel, S.: Mapping and characterizing peatland using ground-penetrating-radar and nuclear-magnetic-resonance, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10580, https://doi.org/10.5194/egusphere-egu24-10580, 2024.

EGU24-12027 | ECS | Posters on site | BG3.18

Resistant high tree cover mode with increasing fire in Indonesian natural peatland ecosystems 

Eufrasia B. A. Diatmiko, Max Rietkerk, and Arie Staal

The vulnerability of tropical ecosystems to global changes is a growing concern, with tree cover distribution patterns playing a pivotal role in their responses to changing environmental conditions. It is important to understand how natural ecosystems respond to these changes to assess the resilience of the ecosystems. While extensive research has investigated tree cover distributions in the tropics, a notable gap exists in understanding the effects of environmental variables to tree cover and the underlying mechanisms in Indonesian natural ecosystems, with its vast peatland areas. In response to this gap, we analyze the relative importance of environmental variables, specifically precipitation and fire, on shaping tree cover distributions in peatland and non-peatland ecosystems in Indonesia. We use the Global Forest Change dataset on tree cover with the spatial resolution of 30 meters. To focus on natural ecosystems, we filter out areas with human intervention. We find a consistent unimodal distribution of tree cover in the gradients of fire frequency and precipitation, marked by a distinct peak in each value range of the variables. In non-peatland, we observe a switch from high to low tree cover mode with increasing fire, which occurs at intermediate fire frequency. In contrast, peatland ecosystems show a remarkable resistance of the high tree cover mode despite increasing fire incidents. This implies that peatland could be more resistant to the same intermediate fire frequency than non-peatland. Our findings are relevant for ecosystem resistance in Indonesian peatlands and non-peatlands and their potential vulnerability to disturbances, particularly in the face of ongoing global environmental changes.

How to cite: Diatmiko, E. B. A., Rietkerk, M., and Staal, A.: Resistant high tree cover mode with increasing fire in Indonesian natural peatland ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12027, https://doi.org/10.5194/egusphere-egu24-12027, 2024.

EGU24-13540 | ECS | Posters on site | BG3.18

Mapping Italian Alpine Peatlands Using Multisource Satellite Imagery and Machine Learning Approach 

Qiqi Li, Manudeo Singh, and Sonia Silvestri

While we are aware that the Italian Alps host thousands of small peatlands, the precise estimate remains uncertain due to the absence of a comprehensive map. These ecosystems are extremely valuable because, in addition to storing large amounts of organic carbon, they provide many other ecosystem services. They regulate water flow, retaining it during wet seasons and releasing it during dry periods. Furthermore, they purify water by retaining nutrients such as nitrogen and phosphorus and provide water to wildlife even during droughts. Moreover, they are characterized by high biodiversity, serving as habitats for several endangered species.

Conventional approaches to mapping peatlands typically involve surveys characterized by long update cycles and considerable costs. Some remote sensing approaches, such as UAV and aerial photography, have the disadvantages of being weather dependent, and have high costs and limited coverage. In contrast, satellite remote sensing imagery presents several advantages, including broad coverage, cost-effectiveness, and frequent temporal resolution. Hence, our research emphasizes the mapping of Alpine peatlands by integrating multiple remote sensing datasets and employing machine learning algorithms. The spatial distribution of Alpine peatlands shows a correlation with topographic and hydrological conditions. These peatlands, averaging around 1 hectare in size, exhibit distinctive vegetation, topographic, and hydrological characteristics compared to non-peatland regions. Therefore, the differentiation in these features extracted from remote sensing imagery stands as a critical factor for identifying peatlands.

We present the results of integrating Sentinel-2 optical data, Sentinel-1 radar imagery, and the CLO-30 from the Copernicus digital elevation model (DEM) through the Google Earth Engine (GEE) platform. This integration aims to map Alpine peatlands employing a pixel-based Random Forest algorithm. We focus on a section of the Adige River basin, located within the Trentino Alto-Adige Region in Italy. Within this area, we collected and updated an inventory of 157 peatland sites, divided into two groups. One subset was used to calibrate the algorithm, while the other served to validate the results. Several sets of features were extracted from the multi-source remote sensing dataset. The findings suggest that both the DEM itself and the topographic features derived from it contributed most significantly to the classification results. Hydrological connectivity was also found to be a significant feature, probably due to the crucial role that water flow and retention play in the establishment and sustainability of peatlands. A key finding is the impact of these features surpassed that of optical and radar data in enhancing the accuracy of the classification. Since our peatland mapping methodology is implemented on the GEE platform and uses freely available datasets, it can be applied across the entire Alpine region and in other mountainous areas worldwide.

How to cite: Li, Q., Singh, M., and Silvestri, S.: Mapping Italian Alpine Peatlands Using Multisource Satellite Imagery and Machine Learning Approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13540, https://doi.org/10.5194/egusphere-egu24-13540, 2024.

EGU24-14157 | Posters on site | BG3.18

Methane and Nitrous Oxide Fluxes in Soil and Stems of Malaysian Tropical Peat Swamp Forest 

Kaido Soosaar, Lulie Melling, Reti Ranniku, Faustina E. Sangok, Jaan Pärn, Guan Xhuan Wong, Sebestian Kalang William, Kuno Kasak, Mikk Espenberg, Maarja Öpik, and Ülo Mander

Tropical peat swamp forests are crucial global carbon (C) reserves. Prevailing waterlogged conditions in peat soils prevent the complete decomposition of dead plant material. As a result, more organic matter is produced than decomposed, leading to the gradual accumulation of peat. However, the destabilisation of tropical peatlands through climate warming, droughts, and changes in land use threaten this C sink capacity. Anaerobic conditions in peat soils lead to methane (CH4) production through decomposition and nitrous oxide (N2O) production under moderate levels of soil oxygen content. Earlier evidence suggests that tree stems in tropical peat swamp forests are significant sources of CH4; however, little information is available on their exchange of N2O.
This study investigated CH4 and N2O exchange of soil and stems of Combretocarpus rotunditus and Shorea albida trees in a peat swamp forest in Sarawak, Malaysia, from September 2022 to September 2023. To describe the temporal dynamics of greenhouse gas (GHG) exchange, we measured gas fluxes from the soil and stems at different heights (10, 80 and 170 cm from the tree's base) using the manual static chamber method and spectroscopic gas analysis. The chemical composition of the soil was analysed and several environmental parameters, including groundwater level, soil moisture content, soil and air temperature, were simultaneously measured with the GHG fluxes to determine the relationships between the fluxes and environmental factors.
Soil CH4 emissions varied between 52.3 and 807 μg C m−2 h−1, with higher values observed during the wet season in conjunction with higher groundwater levels. On the other hand, the soil N2O fluxes were relatively low and did not show a distinct seasonal pattern, ranging from -1.33 to 3.54 μg N m−2 h−1. Annual average soil CH4 and N2O emissions were 392 μg C m−2 h−1 and 0.65 μg N m−2 h−1, respectively. The highest average stem CH4 emissions (1.48 μg C m−2 h−1) were recorded at the lowest parts of trees, with a vertical decrease in emissions and an overall uptake observed at the highest measurement point. In contrast, stem N2O emissions were small, with no clear trend with measurement height.

In summary, we observed moderate and variable soil CH4 emissions with limited generalisable relation to measured environmental parameters. Soil and stem N2O emissions were relatively small. These results indicate the need for further comprehensive soil and stem GHG analyses in tropical peat swamp systems to better understand the GHG dynamics of this critical ecosystem.

How to cite: Soosaar, K., Melling, L., Ranniku, R., Sangok, F. E., Pärn, J., Wong, G. X., William, S. K., Kasak, K., Espenberg, M., Öpik, M., and Mander, Ü.: Methane and Nitrous Oxide Fluxes in Soil and Stems of Malaysian Tropical Peat Swamp Forest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14157, https://doi.org/10.5194/egusphere-egu24-14157, 2024.

EGU24-14254 | ECS | Posters virtual | BG3.18 | Highlight

Saltwater intrusion may aggravate carbon loss from tropical peatlands 

Hasan Akhtar, Salwana M. Jaafar, Rahayu S. Sukri, and Massimo Lupascu

Tropical peatlands, covering approximately 23 million hectares, constitute 6% of the global peatlands, predominantly situated in low-lying coastal regions of Indonesia, Malaysia, Borneo, and Papua. Unfortunately, due to land-use change and accompanying subsidence, these low-lying coastal peatlands may be inundated with seawater due to sea level rise in response to climate warming in the coming decades. This would not only result in carbon losses in fluvial form but may also alter the biogeochemistry of peat, thereby affecting the peat decomposition process. Therefore, in this peat incubation study, we attempted to simulate the effect of saltwater intrusion on CO2 emissions under a factorial setup of two salinity levels (15 ppt, 30 ppt), tidal cycle (high tide as flooded peat vs low tide as mesic peat), and labile carbon mimicking plant root exudates (in the form of glucose addition @ 0.1 mgC/g of peat/day) with peat incubated at 28 °C (the long-term average temperature at site).

            We found that salinity and carbon addition significantly (p < 0.01) affected the rate of CO2 emissions with the highest mean values for treatment with 30 ppt salinity (251.7 ± 61.3 mgCO2/g of peat/hr), which was approximately three times higher than the control (72.3 ± 9.3 mgCO2/g of peat/hr). Similarly, we found that the mesic peat (reflecting low tide) showed almost twice the mean CO2 values (150 ± 36 mgCO2/g of peat/hr) compared to flooded peat (79.9 ± 15.1 mgCO2/g of peat/hr). These results underscore the vulnerability of these ecosystems to future sea level rise, potentially transforming them into a significant carbon source. The urgency to conserve these vital terrestrial carbon reserves is further emphasized by the implications of our study, emphasizing the need for proactive measures to mitigate the impact of land use and climate change on tropical peatlands.

How to cite: Akhtar, H., Jaafar, S. M., Sukri, R. S., and Lupascu, M.: Saltwater intrusion may aggravate carbon loss from tropical peatlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14254, https://doi.org/10.5194/egusphere-egu24-14254, 2024.

EGU24-17791 | ECS | Posters on site | BG3.18

Identifying the Transition Zone between Peat and Mineral Soils Using Airborne Radiometric Data: a national scale case study from Ireland 

David O Leary, John Connolly, Louis Gilet, Patrick Tuohy, Jim Hodgson, and Eve Daly

National and international climate change mitigation plans require a knowledge of peat soil extent across large geographic areas. Peat soils, which play a vital role in carbon storage and climate regulation, have a physical margin where soils change from high to low organic content. Accurate delineation of both national extent of peat soils and peat to mineral soil transition is required for assessing land use and planning effective conservation and carbon loss mitigation strategies. This abstract presents a novel approach for defining both peat soil extent nationally and transition zones between peat and mineral soils at field scale.

At a national scale, peat soil maps are created using optical satellite remote sensing or legacy soil/quaternary maps or a combination of both. However, optical remote sensing cannot detect peatlands under landcover such as forest or grassland and legacy maps are often created from sparse in-situ auger data making the accurate delineation of the boundary between peat and mineral soils difficult and cost prohibitive.

Airborne radiometric data, which measures natural environmental radiation, has been shown to differentiate between peat and mineral soils due to high attenuation of gamma rays in organic soils. Radiometric data is considered a direct measurement of the subsurface and so is minimally affected by landcover. Additionally, as airborne radiometric data can be acquired in a spatially consistent manner, it has the potential to identify areas of peat soil across the landscape and highlight areas of transition between high and low organic soils.

In Ireland, the Tellus survey, acquired by Geological Survey Ireland (GSI) aims to acquire airborne data (including radiometric data), consistently across the country (flight line spacing of 200m) at a resolution of 50 x 50 m. Utilising this national radiometric dataset, a machine learning classification methodology is presented. Data are classified as peat (> 30 % organic material) or non-peat, with 85 % accuracy, is validated using a national soils sampling survey. A confidence value is extracted, once data are classified, which results in the identification peat soils. Several field sites across the midlands of Ireland, which are located at verified transition zones, are then used to show the effectiveness of the classification at identifying transition zones at the field scale.

The methodology is robust and can be applied in all areas where these data exist. The results highlight that inclusion of an airborne radiometric dataset in a national climate plan can be used to update national and international carbon inventories of peatlands areas and inform European policy. Understanding the location of these peat to mineral soil transitions is paramount when considering the impact on climate change mitigation strategies such as potential impact of rewetting of peat soils.

How to cite: O Leary, D., Connolly, J., Gilet, L., Tuohy, P., Hodgson, J., and Daly, E.: Identifying the Transition Zone between Peat and Mineral Soils Using Airborne Radiometric Data: a national scale case study from Ireland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17791, https://doi.org/10.5194/egusphere-egu24-17791, 2024.

EGU24-17838 | Orals | BG3.18

Quantifying spatial peat depth with seismic micronodes and the implications for carbon stock estimates 

Tarje Nissen-Meyer, Jack Muir, Simon Jeffery, Joe Collins, Alice Marks, and Nathan Brake

Peatlands are a major store of soil carbon, due to their high concentration of carbon-rich decayed plant material. Consequently, accurate assessment of peat volumes are important for determining land-use carbon budgets. Determination of carbon stocks at the scale of individual peat sites has principally relied on either mechanical probing or electromagnetic geophysical methods. In this study, we investigated the use of seismic nodal instrumentation for quantifying peat depth. We used Stryde nodes for a deployment at the Whixall Moss in Shropshire, England. We measured seismic arrival times from peat-bottom reflections, as well as dispersive surface waves to invert for a model of variable peat depth along a linear cross-section using level-set based interface inversion for peat depth. We found that the results from seismic surveying corresponded well with manual probe depths, and delivered high spatial resolution. The use of very small seismic nodes (micronodes) allows for particularly rapid deployment on challenging terrain.

How to cite: Nissen-Meyer, T., Muir, J., Jeffery, S., Collins, J., Marks, A., and Brake, N.: Quantifying spatial peat depth with seismic micronodes and the implications for carbon stock estimates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17838, https://doi.org/10.5194/egusphere-egu24-17838, 2024.

EGU24-18342 | Posters on site | BG3.18

A simple approach to upscale methane emissions from peatlands using Planetscope satellite data and machine learning algorithm 

Ruchita Ingle, Matthew Saunders, Wahaj Habib, John Connolly, Laurent Bataille, Ronald Hutjes, Jan Biermann, Wilma Jans, Wietse Franssen, Laura vander Poel, and Bart Kruijt

Peatland plays a significant role in methane (CH4) emissions, and methane dynamics are governed by ecohydrological variables and site heterogeneity. Emission quantification from different stages of peatland is vital to understanding the impacts of peatland on climatic feedbacks for effective rehabilitation of these sensitive ecosystems. Chamber measurement and eddy covariance techniques are widely used to understand methane dynamics. These measurements are either at a point or footprint scale, making it challenging to upscale these emissions to the site scale considering the heterogeneity of peatlands. Here, we present a simple approach to upscale methane emissions from closed chambers using PlanetScope high-resolution satellite data along with the random forest algorithm and weighted-area approach. This methodology was tested at three peatlands covering near-natural, under-rehabilitation, and degraded sites in Ireland for a span of two years. The annual vegetation maps were mapped with an accuracy of 83% at the near-natural site and around 98-99% at the under-rehabilitation and degraded sites. The highest site-scale fluxes were observed at the near-natural site (2.25 and 3.80 gC m−2 y−1), and the site-scale fluxes were close to net zero for the under-rehabilitation (0.17 and 0.31 gC m−2 y−1) and the degraded site (0.15 and 0.27 gC m−2 y−1). As a step forward, this approach will be applied to upscale eddy covariance fluxes from three fen sites in the Netherlands. Overall, the easy-to-implement methodology proposed in this study shows potential to apply it across various heterogeneous land-use types to assess the impact of peatland rehabilitation on methane emissions.

How to cite: Ingle, R., Saunders, M., Habib, W., Connolly, J., Bataille, L., Hutjes, R., Biermann, J., Jans, W., Franssen, W., vander Poel, L., and Kruijt, B.: A simple approach to upscale methane emissions from peatlands using Planetscope satellite data and machine learning algorithm, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18342, https://doi.org/10.5194/egusphere-egu24-18342, 2024.

EGU24-18587 | ECS | Posters on site | BG3.18

Deciphering Congo Peat Chemistry; Using Plants to Understand the Peat. 

Kirby Robinson, Sue Page, Nick Girkin, Lydia Duffy, and Arnoud Boom

The chemistry of tropical peat has been shown to vary significantly according to differences in plant litter chemistry and hence the composition of the peat-forming vegetation. In the Central Congo peatlands, peat forms under two forest types; hardwood and palm swamp forests.

The complex chemistry of the organic matter (OM) in peat involves multiple compounds including; carbohydrates, cellulose, lipids, lignin and various secondary metabolites, each with different decay rates. Thus, the chemical nature of the OM determines its recalcitrance. Likewise, due to both chemical and structural differences between plant material from different species and between different litter components, not all plant fractions are conducive to or make a similar contribution to peat production. Previous studies suggest there is a relatively greater accumulation of root material in tropical peats compared to other fractions due to its high lignin content, which renders it more resistant to decay, but linking the physiochemical properties of tropical peats and their decomposability to the botanical origins of the plant litter remains understudied. As a result, there are significant gaps in our knowledge regarding the links between plant litter inputs, peat organic geochemistry and our understanding of their role in both peat formation and GHG emissions.

Important recalcitrant moieties such as lignin can be analysed via geochemical analytical methods such as pyrolysis GC-MS, to provide insights into peat composition and vegetative origin. Lignin is an abundant and complex class of organic polymer, that forms key structural plant tissues. Categorised into three monolignols: coniferyl alcohol (Guaiacyl type; G), sinapyl alcohol (syringyl type; S) and p-coumaryl alcohol (p-hydroxyphenyl type; P). The amalgamation of these monolignols results in the creation of complex and diverse lignin structures, related to plant physiology for example between monocot and dicot angiosperms and to tissue type e.g. woody and non-woody. Consequently, key vegetation types exhibit varying concentrations of these monolignols, resulting in variations in relative proportions of G, S & P – which have identifiable pyrolysis signatures, and thus can be used to differentiate between types of lignin in the Congo peat. By examining their relative concentrations, this method allows the discrimination of plant inputs and their subsequent influence on peat organic geochemistry.

This study aims to characterise the organic geochemistry of peat from various locations across the Congo Basin; investigating the vegetative origin of the peat and OM transformations in both palm and hardwood dominated swamp forests. Initial results demonstrate distinct chemical (pyrolysis) signatures reflective of plant inputs and type, leading to discernible variations in peat chemistry over short distances and significant differences in the lignin composition corresponding to hardwood and palm dominated peat. The relevance of these findings for improved understanding of peat formation in this location is discussed.

How to cite: Robinson, K., Page, S., Girkin, N., Duffy, L., and Boom, A.: Deciphering Congo Peat Chemistry; Using Plants to Understand the Peat., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18587, https://doi.org/10.5194/egusphere-egu24-18587, 2024.

EGU24-18973 | ECS | Posters on site | BG3.18

The Use of Ground-Penetrating Radar for Mapping Peatland Subsurface in Afforested Peatland Restoration 

Laura Hughes-Dowdle, Bernd Kulessa, Tavi Murray, Jonathan Walker, Rob Low, Robin Cox, and Joey Pickard

Peatland afforestation and drainage are major causes of upland peatland degradation and have resulted in ongoing issues including increased flood risk, biodiversity loss, and carbon emissions. The last decades have witnessed increasing global investments in peatland restoration, as exemplified in South Wales. Here, the peatlands of Pen y Cymoedd coexist as the UK’s highest altitude windfarm and are being restored post tree-felling through a process known as ‘forest-to-bog’ restoration. Yet, there is a definite need to improve understanding of the impacts and effectiveness of these interventions, which can be gained through the mapping and representation of peatland structure and in particular, its ecohydrological properties.

Traditional peatland investigations involving manual probing and coring are environmentally intrusive and time and labour intensive. However, recent studies have demonstrated that geophysical approaches such as ground penetrating radar offer an alternative approach, enabling peat depth to be rapidly surveyed over large areas. Afforested peatlands, however, present new challenges for both radar and probe-based approaches, for example, the presence of tree roots can obstruct the probe from reaching the true depth of the peat body and create complex reflectors on the radargram. There remains little guidance on appropriate use of ground-penetrating radar methodologies in afforested peatland settings, particularly on peatlands that have different hydrogeophysical properties resulting from various land use interventions.

In this study, ground-penetrating radar surveys were conducted on peatland sites representing four different condition states: intact, afforested, felled, and restored. The surveys aim to map peat depth and explore the structure of the shallow subsurface. We adjust the parameterisation and processing flows involved in ground-penetrating radar surveys to determine the most appropriate approach dependant on peatland condition and the purpose of survey. Furthermore, by comparing reflection properties from different peatland sites which were selected to replicate the successive stages of forest-to-bog restoration, the structural changes caused by forestry and subsequent restoration attempts are revealed. This research will therefore help to inform operational best-practice and policy of peatland restoration, both within and beyond Wales.

How to cite: Hughes-Dowdle, L., Kulessa, B., Murray, T., Walker, J., Low, R., Cox, R., and Pickard, J.: The Use of Ground-Penetrating Radar for Mapping Peatland Subsurface in Afforested Peatland Restoration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18973, https://doi.org/10.5194/egusphere-egu24-18973, 2024.

EGU24-19643 | Posters on site | BG3.18

A Satellite-derived Peatland Ecotype Classification Method Using Artificial Neural Network Hierarchical Ensembles 

Corrado Grappiolo, Veeresh Gurusiddappa, Shane Regan, Oisín Boydell, and Eoghan Holohan

Being able to identify, map and monitor areas of different ecological quality of peatland habitats, or ecotypes, provides important information on spatial peatland condition, the potential for restoration of degraded areas and ecotype carbon (C) emission and/or sequestration capacity when coupled with known C-flux factors. Regular and accurate mapping of such ecotypes is also a requirement under the European Union (EU) Habitats Directive, and will be required in some form to help guide the framework and implementation of the upcoming EU Nature Restoration Law.

Although the most precise way to identify the presence of certain ecotypes is via in-situ surveying, this approach clearly suffers from scaling issues, as it is only feasible in small selected peatlands (or even portions of them) and requires a lot of resources, e.g. skilled domain experts and time. A solution might come from remote sensing and Earth Observation technologies, which have been increasingly utilised to map the occurrence and extent of peatland environments in recent years. With this respect, the European Space Agency's Copernicus Program's Sentinel-2 satellite constellation could be a viable data source, as it allows for a multi-spectral, systematic and regular coverage of land surfaces with a spatial resolution up to 10 square metres and 5 days of revisit frequency. Nevertheless, the remote detection and mapping of ecotypes within the peatland complex itself is relatively under-studied and there is no currently accepted method that can be deployed at landscape scale. 

In this work we present a rather simple machine learning pipeline for ecotype detection at scale. The focus of this study are lowland peatlands, or raised bogs, in the Republic of Ireland. The pipeline assumes the existence of ground truth ecotype data (for machine learning training purposes), raised bogs map boundaries (shapefiles) and Sentinel-2 imagery. Both training, testing and validation datasets undergo the same pre-processing procedure. In the training step we train an ensemble of binary classifiers - specifically one multilayer perceptron network per ecotype - organised in a hierarchical fashion, to reduce the complexity of the problem. The ecotype classification would be done in a cascade - in accordance with the hierarchy - via canonical ensemble learning classification. 

The preliminary results gathered not only seems to indicate that our approach could provide reliable estimations about raised bog ecotype composition at scale, they also highlight the potential need for seasonal ensembles. Furthermore, we will present the results of a crowdsourcing experiment, in which domain experts were: (1) presented with ecotype map images, resulting from the inference of a plethora of ensemble classifiers of different settings and hyperparameters, and (2) asked to cast a vote on which image most closely resembled the related ground truth image.

How to cite: Grappiolo, C., Gurusiddappa, V., Regan, S., Boydell, O., and Holohan, E.: A Satellite-derived Peatland Ecotype Classification Method Using Artificial Neural Network Hierarchical Ensembles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19643, https://doi.org/10.5194/egusphere-egu24-19643, 2024.

Peatlands, which cover a significant proportion of the wetland ecosystems globally, play a vital role in maintaining biodiversity and regulating water and climate. However, these ecosystems are currently undergoing degradation as a result of human activities, particularly the draining of peatlands for agricultural purposes, peat extraction, and forestry. Irish raised bogs, which constitute over half of the EU's oceanic raised bogs, have been extensively drained for various land-use activities. Efforts are being made to conserve these ecosystems by implementing measures such as rewetting, restoration, and rehabilitation. However, this requires the identification and accurate mapping of artificial drainage ditches. This study uses a U-net-based convolutional neural network to develop a very high-resolution map of the artificial drainage network in Irish raised bogs, covering an area of 523,000 hectares. The map also quantifies drainage in different land-use categories, such as industrial and domestic peat extraction. The results of this study will aid in implementing conservation activities, such as drain blocking to promote rewetting and improve carbon and greenhouse gas emission accounting at the national scale.

How to cite: Habib, W. and Connolly, J.: Automated Mapping of Artificial Drainage in Peatlands Using Deep Learning and Very High-Resolution Aerial Imagery, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21619, https://doi.org/10.5194/egusphere-egu24-21619, 2024.

EGU24-21989 | ECS | Posters virtual | BG3.18

Mapping global peatlands thickness and carbon stock 

Marliana Tri Widyastuti, José Padarian, Federico Maggi, and Budiman Minasny

Peatlands, occupying just 3–4% of the Earth's surface area, are remarkable for holding nearly 30% of the world's terrestrial carbon (C), securely stored in their soil. These ecosystems are incredibly diverse, found from the Arctic to the Tropics and at various elevations. They perform numerous critical functions and ecosystem services, crucial for achieving the Sustainable Development Goals.

The 2022 Global Peatland Assessment reported over 500 million hectares of peatlands worldwide, emphasising the importance of evaluating their baseline status and routinely assessing their conditions. This is vital for the conservation of these significant ecosystems. While global and national extent maps of peatlands exist, there's a notable gap in information regarding global peatland thickness and carbon stock.

This study aims to perform a preliminary evaluation of global peatland thickness and carbon stock by employing digital mapping techniques. We gathered over 5,000 data points on peatland characteristics (including thickness, carbon content, and bulk density) from existing observations and maps worldwide.  We combined these observations with spatial data from earth observations representing climate, topography, and vegetation as covariates for use in machine learning methods to explicitly estimate peatland thickness and carbon stock globally at a 1 km resolution. The outcome of this work provides a first comprehensive global quantification of peat thickness, carbon content, and stock, aiding in the global modelling of peatland status and conditions.

How to cite: Widyastuti, M. T., Padarian, J., Maggi, F., and Minasny, B.: Mapping global peatlands thickness and carbon stock, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21989, https://doi.org/10.5194/egusphere-egu24-21989, 2024.

EGU24-22001 | ECS | Posters virtual | BG3.18

Remote sensing of peatland degradation – a review on gaps and hotspots of research across the northern hemisphere 

Farina de Waard, Alexandra Barthelmes, Hans Joosten, John Connolly, and Sebastian van der Linden

While mapping peatlands worldwide remains an important task, capturing their status using earth observation technologies has received less attention. Approximately 500,000 km² of degraded peatland worldwide contribute an excessive 5% of global greenhouse gas emissions. Most human use of peatlands remains unsustainable and can disrupt the balance of peat, water, and vegetation that maintain a stable or even growing peatland. With growing threats like the climate crisis and a need for safe water supplies and other ecosystem services, the restoration of degraded areas becomes ever more eminent. Standardized degradation classifications and land cover mapping techniques that address the severe outcomes of degraded peatlands are important tools but lacking.

The temperate and boreal zones of Northern America, Europe and Asia host a large proportion of the worlds’ peatland area. While temperate regions are often densely populated, causing high pressures on peatlands, the far north is facing increasing challenges such as permafrost melt, intensification of fire, mining, and wood harvesting. Based on a Web of Science literature search, this review identified and analyzed articles with a focus on peatland degradation research using remote sensing. 115 articles with study areas across the northern hemisphere were identified. Using a new approach to cluster this research based on a three-dimensional cube, each study’s degradation foci were evaluated along three directions of peatland degradation that build the three directions of the cube: peat, hydrology, and vegetation.

Five clusters of different weights emerge from this concept, including two-dimensional and three-dimensional research. Vegetation-focused research dominates, while there are only few holistic approaches (12 of 115) that address peatland degradation along all three dimensions. Almost 80% of all research papers between 1981 and 2023 were published on eight hotspot regions across the northern hemisphere. While there is a general increase in article numbers over the last years, publications from other countries decrease. Restoring peatland ecosystem functions after degradation presents a significant challenge. With this review, we aim to highlight cold- and hotspots of research with regard to geography, research topics and used remote sensing tools to help improving peatland degradation research using remote sensing.

How to cite: de Waard, F., Barthelmes, A., Joosten, H., Connolly, J., and van der Linden, S.: Remote sensing of peatland degradation – a review on gaps and hotspots of research across the northern hemisphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22001, https://doi.org/10.5194/egusphere-egu24-22001, 2024.

EGU24-22008 | ECS | Orals | BG3.18 | Highlight

Carbon dynamics of high-elevation tropical cushion peatlands in the Andes 

Mary Carolina Garcia Lino, Simon Pfanzelt, Alejandra Domic, Isabell Hensen, Karsten Schittek, Rosa Isele Meneses, and Maaike Bader

High-Andean tropical peatlands occur up to 5000 m a.s.l., where conditions vary from cool to freezing cold on a daily basis. In the tropical and subtropical Andes, these high-elevation peatlands are mainly composed of vascular cushion plants and occur in topographically wet locations in climates ranging from very humid paramos in the north to arid puna in the south. Like other peatlands, Andean cushion peatlands store large amounts of carbon, but with high amount of sediments and higher recent carbon accumulation rates. Often, these amounts have not been quantified, nor are the controls on carbon gains and losses sufficiently known to predict changes in carbon storage due to land-use and climate change. We reviewed the literature on carbon stocks and dynamics in (sub-)tropical Andean cushion peatlands, aiming to understand the topographic, hydrologic, climatic and biotic drivers and geographic patterns. We identified important roles for catchment size and sediment inputs, temperature in combination with water availability, and vegetation, but none of these roles can be quantified yet based on currently available data. However, it is clear that predicted regional differences in climatic changes (seasonality, permafrost behavior, temperature, precipitation regimes) imply that carbon-balance trends of cushion peatlands will differ regionally, with those in paramo most likely to continue as C sinks, while those in dry puna are more likely turning to C sources under increasing aridification.

How to cite: Garcia Lino, M. C., Pfanzelt, S., Domic, A., Hensen, I., Schittek, K., Meneses, R. I., and Bader, M.: Carbon dynamics of high-elevation tropical cushion peatlands in the Andes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22008, https://doi.org/10.5194/egusphere-egu24-22008, 2024.

GM4 – Geomorphology, Climate, and Hazards

EGU24-224 | Posters on site | GM4.2

Assessment of sediments dynamics through the identification of main deposition shapes in large reservoirs  

Jose Luis Molina, Fernando Espejo, Jorge Mongil-Manso, Teresa Diez-Castro, Santiago Zazo, and Carmen Patino-Alonso

Sediment deposition at the bottom of artificial reservoirs have become a worldwide problem that represent a dual problem. First, it is related to the reduction of storage capacity and lifetime. In this sense, associated impacts may comprise a capability reduction to provide water for irrigation, hydropower production and other uses, as well as to intercept floods and regulate the flow. Second, problems come from the threat that the sediment represents for the dam structure. In case the sediment deposits get too close from the structure, they may block the outlets affecting the dam safety. Also, if high-charged water pass through the turbines, it causes abrasion of mechanical equipment. This may generate inefficiencies such as decrease power generating efficiency and ultimately production loss. This primarily stems from the absence of a holistic and integrated strategy for creating a durable and sustainable strategy for managing sedimentation in dams and reservoirs.  In this sense, a whole plan should incorporate a sequential nature that incorporate three chronological phases: preventive, mitigative and corrective measurements. It is clear the lack of preventive actions that have taken during the initial decades of dam/reservoirs functioning. The main objective of this work is to identify the main sediment deposition shapes in large reservoirs that allows inferring the driven processes. Based on the pervious analysis, 6 categories of shapes have been identified based on 4 parameters listed as follows: slope continuity, slope break, absolute and relative slope, and arc configuration. In this sense, categories are:  Flat Areas (FA), SubFlat Areas (SFA), Breaking Lines (BL), Vertical Jumps (VJ), Non-Vertical Jumps (NVJ) and Arc-Shapes. This will allow inferring the main deposition and transport processes that may help to prevent, palliate and/or correct this phenomenon. This research was applied in Rules reservoir (Granada) which is key hydraulic infrastructure with huge sediments issues. Future policies will have to implement a plan route incorporating scientific analysis taking to consideration sediments dynamics.

Keywords: dynamics, bathymetric measurement, dam sedimentation, hydraulic infrastructure, storage capacity

How to cite: Molina, J. L., Espejo, F., Mongil-Manso, J., Diez-Castro, T., Zazo, S., and Patino-Alonso, C.: Assessment of sediments dynamics through the identification of main deposition shapes in large reservoirs , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-224, https://doi.org/10.5194/egusphere-egu24-224, 2024.

EGU24-1049 | ECS | Orals | GM4.2

Exploring Uncertainties Within a Framework for Assessing Extreme Precipitation-Induced Cascading Hazards in the Himalayas  

Sudhanshu Dixit, Srikrishnan Siva Subramanian, and Sumit Sen

The Himalayas are increasingly vulnerable to the impacts of climate change, with recent years experiencing a surge in the frequency of natural hazards. The risk escalates when events unfold in a cascading manner, where a primary hazard triggers a secondary one. Therefore, it is crucial to develop an integrated framework to assess the ramifications of these cascading hazards. This framework plays a pivotal role in providing early warnings, considering the uncertainty introduced by rainfall input. The presented framework simulates the dynamic interplay between intense precipitation events and hill slopes, potentially triggering landslides. It subsequently models the debris flow resulting from the runoff formed by precipitation mixing with landslide deposits, culminating in debris runout. To address data uncertainties, the framework integrates four diverse precipitation data sources: gridded observation datasets, reanalysis data, satellite data, and numerical weather prediction models. The methodology assesses sediment volume originating from hillslopes and anticipates the sediment volume reaching river junctions during extreme events. Additionally, it involves the numerical simulation of the initial stages of the cascading nature of geohazards, specifically the transformation of landslides into debris flows. The framework's validation is conducted using the 2013 North India Floods, an extreme precipitation event that triggered over 6000 landslides and debris flows.

How to cite: Dixit, S., Subramanian, S. S., and Sen, S.: Exploring Uncertainties Within a Framework for Assessing Extreme Precipitation-Induced Cascading Hazards in the Himalayas , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1049, https://doi.org/10.5194/egusphere-egu24-1049, 2024.

EGU24-1577 | Posters on site | GM4.2

Exploring connections between liquid/solid runoff fractions and water quality in large reservoirs´ catchments through Multivariate statistics  

Jorge Mongil-Manso, Carmen Patino-Alonso, José Nespereira-Jato, José-Luis Molina, Fernando Espejo, María-Teresa Díez-Castro, and Santiago Zazo

In river environments, the interaction between liquid and solid runoff fractions plays a crucial for understanding water flow. The magnitude of liquid runoff is directly influenced by of sediments levels, impacting water resource management and quality. Sediment mobilization by total runoff fundamentally shapes river morphology. The imperative need to comprehensively understand hydrological behavior leads us to examine the relationship between these variables and water chemical aspects. Understanding the intricate dynamics between liquid and solid runoff, influenced by sediment levels and chemical variables, is crucial for the effective sediment management of reservoirs. Multivariate statistics are commonly used to identify factors influencing sediment production during hydrological processes. The objective of this study is to apply Partial Least Squares Regression (PLSR) to identify and understand the relationship between chemical variables as predictors and hydrological processes (liquid and solid runoff), allowing a comprehensive assessment of their influence in river environments.  The case study was conducted in the Rules (Granada), Casasola, and La Viñuela reservoirs (Málaga). The results indicated a positive correlation between sediments (solid runoff) and variables such as pH, Clay (CY), Silt (ST), and Carbonates (CA). This means that as sediment levels increase, these variables also show an increasing tendency. Nevertheless, this study also revealed a negative association between sediments and Dissolved Oxygen (EG) and sand (SD) implying that as sediment levels rise, Dissolved Oxygen and sand content tend to decrease. In terms of liquid runoff, a direct relationship was primarily observed with electrical conductivity (CE), Organic Matter (MO), and Sand Content (SD). This suggests a positive connection between these variables, where higher liquid runoff is associated with higher values of electrical conductivity, organic matter, and sand content. Chemical parameters manifest in two distinct groups: one shows a strong positive relationship with sediments (pH, CY, ST, and CA), while the other (CE, MO, SD, and EG) is associated with liquid runoff. In conclusion, the study underscores the intricate dynamics between liquid runoff, sediments (solid runoff), and chemical variables in river systems, using PLSR to unveil relationships. In summary, this study underscores the crucial connection between total runoff (water and sediments), and chemical variables in river environments. These findings highlight the complexity of interactions in river systems, providing valuable insights for water management and understanding hydrological processes. Furthermore, the interaction between liquid and solid runoff fractions in river environments has direct applications for sediment management in reservoirs, enhancing decision-making knowledge for authorities.

How to cite: Mongil-Manso, J., Patino-Alonso, C., Nespereira-Jato, J., Molina, J.-L., Espejo, F., Díez-Castro, M.-T., and Zazo, S.: Exploring connections between liquid/solid runoff fractions and water quality in large reservoirs´ catchments through Multivariate statistics , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1577, https://doi.org/10.5194/egusphere-egu24-1577, 2024.

Sediment connectivity is a pivotal concept in geomorphological studies aimed at assessing watershed sediment dynamics. It is expressed through the spatial arrangement and physical linkages of system components (Structural Connectivity, SC) and the actual transfer of water and sediments facilitated by dynamic processes (Functional Connectivity, FC). However, a limited number of studies have simultaneously assessed SC and FC. Moreover, traditionally sediment connectivity studies primarily rely on comparing independent results from GIS modelling, field-based assessments, and mapping. Thus, it remains a common practice to treat geomorphic processes and connectivity as separate variables, often without joining them into an integrated modelling approach.

Accordingly, this research aims to introduce a novel methodology that integrates geomorphological data derived from a detailed mapping approach with SC and FC. In particular, we developed a new GIS-based integrated model named HOTSED, designed to assess potential hotspots of sediment sources and related sediment dynamics at the watershed scale.

We tested our approach in a geomorphologically highly active Mediterranean watershed in the Northern Apennines (Italy), starting with the elaboration of an Inventory Map (IM) of sediment sources through fieldwork, photointerpretation, terrain analysis, and digital mapping. Furthermore, we used IM-derived data to estimate the geomorphic Potential of Sediment Sources (PSS) adopting a relative scoring system. Moreover, we computed Structural Sediment Connectivity (STC) and the Potential for Sediment Transport (PST) by combining terrain and hydrological parameters, land use data, and rainfall erosivity. Subsequently, the integration of PSS, STC, and PST was achieved through a raster-based calculation method, yielding the HOTSED model.

The application of the model in the study area provided a single and intuitive output depicting the location of hotspots of sediment sources. It allowed the derivation of “relative hazard” classes for sediment production and delivery using the fluvial system as target feature. The results show that HOTSED successfully highlighted hotspots associated with active complex and polygenetic geomorphic systems located in areas close to the main channels, as well as linear hotspots corresponding to tributary drainages acting as stream corridor sources. Furthermore, it successfully identified areas prone to store sediments in depositional landforms with low hazard, considering both low geomorphic potential and sediment connectivity. Thus, this study proves that our conceptual model is particularly effective in geomorphologically complex areas such as the Northern Apennines.

How to cite: La Licata, M., Bosino, A., Sadeghi, S. H., and Maerker, M.: Assessing hotspots of sediment sources and related sediment dynamics through the integration of geomorphological data, sediment connectivity and sediment transport modelling – The HOTSED model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4101, https://doi.org/10.5194/egusphere-egu24-4101, 2024.

EGU24-4411 | ECS | Posters virtual | GM4.2

Reconstruction of spatial and temporal variability of debris flow in northern Apennines (Italy): Case study of the Alpe di Succiso area 

Muhammad Ahsan Rashid, Giovanni Leonelli, Roberto Tinterri, Roberto Valentino, and Alessandro Chelli

Debris flows are within the most common and extensive natural hazards in mountain areas, where they may impact humans and their assets. On the surroundings of Alpe di Succiso (2000 m a.s.l., Reggio Emilia Province, Italy) multiple debris flows can be found but there is no information about the spatial and temporal variability. To fill the gap, various methods such as geomorphological mapping, geo-mechanical classification of source areas, grain size analysis, dendro-geomorphic method and climate data have been used to assess the spatial extent and the past occurrence of debris-flow events. Here the preliminary results of the analysis performed in the Fossa Lattara Site, NW of Alpe di Succiso, are shown.

The landforms and deposits present in the surroundings of Alpe di Succiso are the product of different morphogenesis (glacial, gravitational, and torrential) which revealed the evolution of the morpho-climatic conditions that have affected the study area over time. Field work has been carried out to identify the morphological features of debris flows revealing distinctive features such as detachment scarps, debris flow cones, lobes, levees, and channels.

To understand the slope stability mechanism of the source area, a discontinuous survey was conducted and it is found that wedge failure is common. Additionally, in both source and depositional areas, grain size analysis was performed by using various methods: direct field measurement was used for particles greater than 16 mm, a sieve analysis covered the range from 2 to 16 mm, and the laser granulometer technique was applied to particles smaller than 2 mm. Notably, the coarser particles were abundant in depositional area than source area.

On forested areas, dendro-geomorphic analysis contributes to detection of trends of debris flow. Dendro-geomorphic technique is based on the identification of growth anomalies recorded by the annual rings of trees disturbed by debris flows. For debris flow dating, identification of reaction wood, abrupt growth changes and eccentric growth are essential.  Trees samples from debris flow area and reference sites (undisturbed areas) have been collected on site to cross date climate influences and debris flow events. According to the dendro-chronological preliminary results, the debris flow was identified in 1989, 2013 and 2017. Further, debris flow events are linked with precipitation events of the study area.

Moreover, daily rainfall depths in the period 1961-2022 have been collected from ARPAE Emilia Romagna database to understand the impact of climate change on debris flow and it is observed that daily precipitation intensity (dpi) has increased from 1961 to 2022. Seasonal variations are also observed. Noticeably, in the months of December, January, and February the sum of dpi has increased by 162 to 220 mm. Future studies will be performed to analyze the effects of climate change on debris flow.

How to cite: Rashid, M. A., Leonelli, G., Tinterri, R., Valentino, R., and Chelli, A.: Reconstruction of spatial and temporal variability of debris flow in northern Apennines (Italy): Case study of the Alpe di Succiso area, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4411, https://doi.org/10.5194/egusphere-egu24-4411, 2024.

EGU24-5386 | ECS | Orals | GM4.2

How is climate change affecting hydro-meteorological triggering for debris flows? An assessment based on convection-permitting models and a bias-neutral procedure 

Andrea Menapace, Eleonora Dallan, Francesco Marra, Lorenzo Marchi, Michele Larcher, and Marco Borga

Debris-flow activity is expected to change in the future following the expected changes in sub-daily rainfall rates. In this study, we connect high-resolution climate simulations from an ensemble of recently developed convection-permitting models (CPM) and a threshold-based precipitation model for debris-flows triggering. We are considering CPM runs over historical (1996-2005), near future (2041-2050) and far future (2090-2099) decade-long periods. Given the biases affecting the CPM simulations and the desire to avoid bias-correction procedures, which may introduce distortions into the precipitation simulations, we propose a methodology to map the debris-flow threshold into the simulated climates. This is obtained by evaluating the return levels of the threshold precipitation rates at different durations, and mapping these in the climate simulations using the same return levels. The Simplified Metastatistical Extreme Value (SMEV) methodology is exploited for the precipitation statistical analysis. The suitability of the proposed framework is tested on the Moscardo catchment, a small study basin located in the eastern Italian Alps, where the debris flow activity is mainly transport-limited. This case study is particularly remarkable due to the high frequency of debris flows and a monitoring system working since 1990, which has permitted establishing reliable rainfall . The debris-flow triggering precipitation events are assessed by considering changes in their frequency, depth and seasonality. The promising preliminary results support the use of this approach to assess debris flow hazards in a changing climate.

How to cite: Menapace, A., Dallan, E., Marra, F., Marchi, L., Larcher, M., and Borga, M.: How is climate change affecting hydro-meteorological triggering for debris flows? An assessment based on convection-permitting models and a bias-neutral procedure, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5386, https://doi.org/10.5194/egusphere-egu24-5386, 2024.

EGU24-5581 | ECS | Orals | GM4.2

Quantifying the effects of rainfall temporal variability on landscape evolution processes 

Taiqi Lian, Nadav Peleg, and Sara Bonetti

Rainfall characteristics such as intensity, duration, and frequency are key determinants of the hydro-geomorphological response of a catchment. The presence of non-linear and threshold effects makes the relationship between rainfall variability and geomorphological dynamics difficult to quantify. This is particularly relevant under predicted exacerbated erosion induced by an intensification of hydroclimatic extremes. In this study, we quantify the effects of changes in rainfall temporal variability on catchment morphology and sediment erosion, transport, and deposition across a broad spectrum of grain size distributions and climatic conditions. To this purpose, multiple rainfall realizations are simulated using a numerical rainfall generator, while geomorphic response and soil erosion dynamics are assessed through a landscape evolution model (CAESAR-Lisflood). Virtual catchments are used for the numerical experiments and simulations are conducted over centennial time scales. Simulation results show that higher rainfall temporal variability increases net sediment discharge, domain erosion and deposition volumes, and secondary channel development. Particularly, dry regions respond more actively to rainfall variations and finer grain size configurations amplify the hydro-geomorphological response. We find that changes in erosion rates due to rainfall variations can be expressed as a power-law function of the ratio of rainfall temporal variabilities (quantified here through the Gini index). Results are further supported by long-term observational data and simulations over real catchments. Such quantification of the effects of predicted changes in rainfall patterns on catchment hydro-geomorphic response, as mediated by local soil properties, is crucial to forecasting modifications in sediment dynamics due to climate change.

How to cite: Lian, T., Peleg, N., and Bonetti, S.: Quantifying the effects of rainfall temporal variability on landscape evolution processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5581, https://doi.org/10.5194/egusphere-egu24-5581, 2024.

EGU24-8030 | ECS | Posters on site | GM4.2

The use of normalized difference vegetation index (NDVI) in sediment connectivity analysis: insights for considering land cover changes in Sediment flow Connectivity Index (SfCI) 

Marina Zingaro, Giovanni Scicchitano, Alberto Refice, Alok Kushabaha, Antonella Marsico, Deodato Tapete, Alessandro Ursi, and Domenico Capolongo

Land cover plays a fundamental role in surface dynamics that involve sediment connectivity. The processes of sediment erosion, transport and deposition are strongly conditioned by land coverage types (classes) that physically can mitigate, prevent or increase sediment production and mobility on the surface. In fact, land cover and land use data are required for the computation of some indices and models of sediment connectivity. However, it should be considered that land cover changes can impact these processes, especially if they occur over a short period of time.

This work presents an assessment of land cover changes in three different hydrographic basins (river Severn basin in UK, river Vernazza basin in northwestern Italy and Lama Camaggi basin in southern Italy) in relation to their respective sediment connectivity patterns, described by Sediment flow Connectivity Index (SfCI) in previous works (Zingaro et al., 2019; Zingaro et al., 2020; Zingaro et al., 2023). The main aim is to evaluate the use of normalized difference vegetation index (NDVI) to consider land cover changes in sediment connectivity analysis. The NDVI is computed from satellite multi-spectral images (Sentinel-2) in time period between the reference year of the land cover used in previous SfCI calculation and the last year (2023) in each of study area. The results show that (1) NDVI highlights the occurrence of land cover changes over short time periods in many areas of the basins, (2) the introduction of NDVI in SfCI modifies sediment mobility values also affecting the definition of sediment connectivity pattern.

The use of NDVI can improve the analysis of sediment connectivity by providing more dynamism in the description of sediment pathways on both spatial and temporal scales. The present experimentation gives new insights to consider surface cover changes in SfCI contributing to update the algorithm and to investigate the possibility of its enhancement.

Acknowledgments

Research performed in the framework of the project “GEORES - Applicativo GEOspaziale a supporto del miglioramento della sostenibilità ambientale e RESilienza ai cambiamenti climatici nelle aree urbane”, funded by the Italian Space Agency (ASI), Agreement n. 2023-42-HH.0, as part of ASI’s program “Innovation for Downstream Preparation for Science” (I4DP_SCIENCE).

References

  • Zingaro, M.; Refice, A.; Giachetta, E.; D’Addabbo, A.; Lovergine, F.; De Pasquale, V.; Pepe, G.; Brandolini, P.; Cevasco, A.; Capolongo, D. Sediment Mobility and Connectivity in a Catchment: A New Mapping Approach. Science of The Total Environment 2019, 672, 763–775, doi:10.1016/j.scitotenv.2019.03.461.
  • Zingaro, M.; Refice, A.; D’Addabbo, A.; Hostache, R.; Chini, M.; Capolongo, D. Experimental Application of Sediment Flow Connectivity Index (SCI) in Flood Monitoring. Water 2020, 12, 1857, doi:10.3390/w12071857.
  • Zingaro, M.; Scicchitano, G.; Palmentola, P.; Piscitelli, A.; Refice, A.; Roseto, R.; Scardino, G.; Capolongo, D. Contribution of the Sediment Flow Connectivity Index (SfCI) in Landscape Archaeology Investigations: Test Case of a New Interdisciplinary Approach. Sustainability 2023, 15, 15042, doi:10.3390/su152015042.

How to cite: Zingaro, M., Scicchitano, G., Refice, A., Kushabaha, A., Marsico, A., Tapete, D., Ursi, A., and Capolongo, D.: The use of normalized difference vegetation index (NDVI) in sediment connectivity analysis: insights for considering land cover changes in Sediment flow Connectivity Index (SfCI), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8030, https://doi.org/10.5194/egusphere-egu24-8030, 2024.

EGU24-10204 | Orals | GM4.2

A stochastic landscape evolution model framework for debris flow and fluvial processes 

Dingzhu Liu, Hui Tang, Jean Braun, and Jens Turowski

Debris flow is an important process that shapes steep landscapes, connecting the hillslopes and fluvial domains. Yet, it is unclear how debris flows quantitatively influence the topography. Here, we propose and develop a new framework considering debris flows as stochastic processes in long-term landscape evolution. We assume that debris flows occur randomly in time with different initial debris flow volumes, which we model using five different distribution functions. Debris flows propagate along the channel and increase their volume by eroding additional material using deterministic equations. The model predicts the slope-area relationship that is generally assumed to be indicative of debris-flow-dominated landscapes. We suggest a new equation to fit the slope-area relationship, including both debris flow and fluvial domains. This equation features a total of five metrics, two of which are power law exponents, two are representative areas, and one representative slope. The topography in the debris flow-dominated domain is sensitive to the properties of the debris flow, e.g., the initial volume of debris flow, frequency, erosion coefficient, Manning coefficient, uplift rate, and channel width and length. The representative slope and area are primarily sensitive to the total initial volumes of the debris flow, and secondarily to the frequency of occurrence of debris flows. The type and shape parameters of distributions and the debris flows’ volume and frequency have limited effects on the slope-area relationship.

How to cite: Liu, D., Tang, H., Braun, J., and Turowski, J.: A stochastic landscape evolution model framework for debris flow and fluvial processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10204, https://doi.org/10.5194/egusphere-egu24-10204, 2024.

Devoting more efforts to understand how arid landscapes respond to extreme rainfall events, given the expected increase in storm frequency in the future due to global warming projections, is of great relevance and therefore needs to be addressed. While local studies of recent storm impacts in drylands have proven to be useful, our understanding of global impacts at local-and-regional-scales over longer time-scales is now more qualitative than quantitative.

Deciphering the effects of erosion runoff processes operating during extreme rainstorm events requires developing practical measuring approaches that assist understanding the temporal and spatial extent of erosion and sediment pathways in the ephemeral drainage networks of bare lands. The advent of Synthetic Aperture Radar (SAR) satellite missions with, for example, the Sentinel 1 constellation from the ESA, has provided a great number of images that can be used to map the areal and temporal extent of erosion during rainstorm events. As a result, we are now able to unravel surface runoff erosion operating in arid areas using InSAR coherence change detection following, for example, the work of Cabré et al. (2020, 2023). Interferometric SAR (InSAR) coherence can be used to decipher the sediment entrainment areas and identify channels and drainages disturbed by the passage of floods. However, the coherence remains a dimensionless parameter with no physical meaning of surface change. Thus, it cannot be used yet to estimate surface change processes in an automatic basis. For this reason, we have explored the areas with surface change identified in InSAR coherence images using SAR amplitude and field calibration data. In the identified surface change areas we have performed grain-size measurements to prove that sediment grain-size diameter (e.g., D84, D50) in ephemeral channels is well correlated (R=0.93 and 0.72, respectively) with SAR amplitude values and therefore can be used to (i) unravel the downstream variations in grain-size by providing valley-floor grain-size maps and, (ii) identify fluvial features (e.g., longitudinal bars) preserved within the ephemeral channels after the passage of a flood. The latter can be of wide application to monitor ungauged ephemeral channels in arid areas worldwide and provide insights about the dryland sedimentary system dynamics during extreme storm events.

How to cite: Cabré, A., Marc, O., Remy, D., and Carretier, S.: Integrating InSAR coherence and SAR amplitude to unravel the surface change processes operating during extreme rainstorm events in the Atacama Desert., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10362, https://doi.org/10.5194/egusphere-egu24-10362, 2024.

EGU24-10429 | ECS | Orals | GM4.2

Interaction Between Large Wood and Sediment Transport in an Alpine Torrent in the Dolomites 

Marco Martini, Francesco Bettella, and Vincenzo D'Agostino

Large wood (LW), defined as woody pieces exceeding 1 m in length and 10 cm in diameter, significantly shapes channel morphology and ecological habitats within Alpine torrents. Lower-order alpine torrents, with their smaller drainage areas and steeper gradients, are particularly sensitive to LW dynamics. The movement of LW greatly affects channel processes, altering flow patterns and sediment dynamics. LW can retain sediments and form log steps that may reduce bed erosion. Moreover, the accumulation of LW at bridge piers and filters or openings of retention check dams can exacerbate flood hazards, emphasizing the crucial need for its accurate quantification for more effective hazard assessments and protection measure design. Our investigation aims to assess changes in the LW budget in the Ru de Vallaccia catchment (covering 1.72 km2, Melton number 0.97, mean channel slope 45%) in the province of Belluno, Veneto, Italy. Specifically, we explore variations in LW volume before and after a heavy rainstorm event with a return period between 2 and 5 years that occurred between the 30th of October and the 2nd of November 2023. Furthermore, this study examines the correlation between segments of the channel affected by sediment erosion and deposition and changes in both the spatial distribution and volume of LW within the channel. Field surveys coupled with high-resolution topography (HRT) assessments conducted before and after the rainstorm event (July and November 2023) allow for a comprehensive evaluation of sediment and LW budgets. Our methodology involves direct field measurements of LW and photointerpretation using GIS software on orthophotomosaics resulting from HRT surveys. Additionally, we utilize the Digital Elevation Model (DEM) obtained from HRT surveys to analyze channel geomorphological changes through the DEM of Differences (DoD) technique, enabling precise quantification and visualization of sediment alterations related to erosion and deposition phenomena. Preliminary findings reveal pronounced sediment mobility, significant alterations in channel morphology, and notable changes in both the spatial distribution and volume of LW. The results of the study highlight the close link between patterns of erosional or depositional sediment dynamics and alterations in the LW budget, elucidating the intricate interaction between geomorphic processes and the presence and evolution of LW during subsequent flood events in steep mountain basins. In addition, these insights have substantial implications for addressing or guiding periodic monitoring of LW and thereby improving our hazard mitigation strategies against those sediment transport events (bedload, debris flood, and debris flow) capable of encompassing significant amounts of LW.

How to cite: Martini, M., Bettella, F., and D'Agostino, V.: Interaction Between Large Wood and Sediment Transport in an Alpine Torrent in the Dolomites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10429, https://doi.org/10.5194/egusphere-egu24-10429, 2024.

EGU24-10776 | Orals | GM4.2

Amplified Risk: How Climate Change is Modifying the Risks from Geological Hazards 

Mary Antonette Beroya-Eitner, Heidi Stenner, Luke Bowman, and Kate Nelson

The global climate is changing, and the effects of these changes on natural hazards are increasingly being felt, particularly by the populations in low- and middle-income countries. Consequently, in the last decades, there has been much research examining the extent of these effects, but the focus has largely been on hydrometeorological hazards. The potential effects of climate change on geological hazards, like earthquakes and volcanic activity, is less studied and deserves greater attention.

Amplified Risk is a four-year program currently being led by the GeoHazards International (GHI), a non-profit committed to saving lives by empowering at-risk communities worldwide to build resilience ahead of disasters and climate impacts. Funded by the United States Agency for International Development (USAID), the overarching goal of the program is to increase collective understanding of how volcanic and earthquake hazards and their societal impacts may be affected by climate change in at-risk low- and middle-income countries.

In line with this, we have thus far explored through literature review and subject matter expert consultations how climate change may alter earthquake and volcanic processes and associated hazards, considering eight climate change signals as the starting point: increased precipitation, decreased precipitation, increased temperature, increased rain-drought cycles, increased free-thaw cycles, increased typhoons, increased wind and sea level rise. Our results show the potential amplifying, cascading, and compounding effects of climate change on geological hazards.   

In general, climate change can affect earthquake and volcanic hazards in two ways: Firstly, it can directly trigger or contribute to directly triggering the hazards as a result of stress regime change following climate-induced variations of loads on the earth surface, mainly due to changes in the volume of ice and water, e.g., glacier melting. Secondly, climate change prepares the ground so that the occurrence of secondary hazards becomes more likely should an earthquake or volcanic eruption occur. For instance, increased precipitation increases soil saturation, making liquefaction more likely in the event of an earthquake.     

In this presentation, we discuss the findings to date in more detail. We also present the flowchart that summarizes our result, which we intend to publish online as an interactive informational tool that may be useful to risk managers, authorities, community leaders, and researchers in appraising the range of effects from climate change on local hazards, and therefore in determining and prioritizing intervention measures.

How to cite: Beroya-Eitner, M. A., Stenner, H., Bowman, L., and Nelson, K.: Amplified Risk: How Climate Change is Modifying the Risks from Geological Hazards, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10776, https://doi.org/10.5194/egusphere-egu24-10776, 2024.

EGU24-13482 | ECS | Orals | GM4.2

Secondary Lahars Impacting on Building Structures at Chimborazo Volcano: A Retrospective and Scenario-Based Modeling Approach 

Simon Mühlbauer, Theresa Frimberger, and Michael Krautblatter

The intense melting of glacial ice and permafrost can increase the presence of temporarily stored liquid water in dynamic high-alpine environments. A sudden release of this water, especially in volcanic settings, might trigger a process chain of severe consequences. During a period of increased periglacial degradation between 2015 and 2017, several large-volume (> 6.0 × 105 m³), outburst-related secondary lahars damaged local infrastructure on the populated southeastern slopes of Chimborazo volcano in Ecuador. The insufficient understanding of secondary lahars associated with the sudden outburst of water complicates the identification of initiating processes and hinders the ability to decipher the governing mechanisms involved during propagation.

In this study, we present how we (1) identified initiation mechanisms of past secondary lahars at Chimborazo, (2) numerically back-calculated these events, (3) developed future lahar scenarios, and (4) quantified their impact on the local population. We performed a retrospective calibration approach to simulate a secondary lahar using the physics-based model RAMMS::Debris Flow. By introducing a novel two-stage outburst scenario development concept, we were able to predict potential future lahars. Finally, applying a standards-based verification of the structural components of residential development allowed us to evaluate the physical impact of potential lahars on infrastructure. We also assessed how increasing the wall thickness affects high- and low-risk areas.

Our results show that the observed secondary lahars can be numerically reproduced with a set of frictional parameters of µ = 0.028 (Coulomb-type friction) and ξ = 600 ms-2 (turbulent friction). The model shows high agreement with locally obtained data (Vasconez et al., 2021) on total lahar volume, flow distance, discharge, and flooded area (deviation from target value = 20 %). By comparing the climatic and topographical situation of similar events at other study sites with the conditions at Chimborazo, we assume that glacial/periglacial destabilization processes may have accompanied the initiation of past lahars. Through deciphering the past initiation processes, our scenarios resulted in volumes between 2.7 × 105 m³ (high probability) and 10.8 × 105 m³ (very low probability) for a climatically derived reference period of 180 years. The structural validation of the component resistance identified high risk for approximately 24 % of the entire runout area. The adjustment to 11 cm wider bricks reduces this area by 5 %.

Only a precise quantification of the ice content and dynamic behavior within the source region enable to estimate the influence of destabilization processes on lahar initiation. However, this work makes an important contribution to supporting informed decision-making in land use planning by implementing an interdisciplinary methodology for analyzing the impacts of mass movements.

In this study, we showed that a retrospectively calibrated numerical model enables the simulation of future outburst-triggered lahars, and we further provided a quantification of their impact on downstream communities.

Vasconez, F.J., Maisincho, L., Andrade, S.D., Cáceres Correa, B.E., Bernard, B., Argoti, C., Telenchana, E., Almeida, M., Almeida, S. & Lema, V. (2021): Secondary Lahars Triggered by Periglacial Melting at Chimborazo Volcano, Ecuador. – Revista Politécnica, 48: 19–30.https://doi.org/10.33333/rp.vol48n1.02

How to cite: Mühlbauer, S., Frimberger, T., and Krautblatter, M.: Secondary Lahars Impacting on Building Structures at Chimborazo Volcano: A Retrospective and Scenario-Based Modeling Approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13482, https://doi.org/10.5194/egusphere-egu24-13482, 2024.

EGU24-14250 | ECS | Orals | GM4.2 | Highlight

Widespread cascading torrential hazards in tropical regions  

Maria Isabel Arango, Marcel Hürlimann, Edier Aristizábal, and Oliver Korup

Over the past decades, cascading hazards that include landslides, debris flows, and floods have caused several major disasters in tropical mountain regions. Even though such cascading hazards also occur in steep terrain elsewhere, some natural drivers such as very high humidity with associated heavy rainfalls, and deeply weathered soil profiles, may amplify the reach and impacts of these cascades in tropical mountains. There, torrential fans sustaining dense settlements are especially prone to rainfall-triggered hazard cascades but remain largely understudied compared to temperate mountain regions. Challenges in their hazard assessment include a lack of consensus regarding the scientific terminology to describe, analyse, and record these events; and their complexity, given that, combining traditional single hazard assessment fails to capture the amplification of the damages. On the other hand, their occurrence in remote, undeveloped regions where they are poorly or not documented, and their low temporal recurrence, decreases hazard awareness and increases the growth of urban settlements in exposed areas.

The goal of this study is to review widespread cascading torrential hazards in the tropics as a common and destructive interaction of mass-wasting and flow processes. The study has two different steps: the first is a review of existing terminology concerning regional hydrometeorological cascading hazards in different latitudes and environments, as an attempt to clarify the existing gaps and differences in information between tropical and higher latitude areas. The second step is the description of the main morphological and triggering characteristics of such events. For this, we compiled a dozen regional cascading torrential events that occurred between 2017 and 2023 in different tropical regions of the American, Asian, and African continents, caused by different triggering mechanisms, including extreme rainfall and earthquakes, or both. Using high-resolution satellite images, the events were mapped differentiating the extent of landslide initiation, debris flows runout, and floodings. Additionally, we used freely available remote sensing sources to extract information concerning the geomorphology, soil texture, and triggering rainfall of each study area. Using different statistical tools, we analysed the relationship between different morphological features, triggering rainfall and soil texture, to distinguish the main characteristics of such events in both the basin and the sub-process scale.

As preliminary results of this ongoing research, we have found an important gap in information concerning widespread cascading torrential hazards in tropical regions. Furthermore, the analysis of our inventory allowed us to identify key factors that contribute to the triggering, propagation, and connection of hazards, including the very high availability of coarse-textured soils and higher sediment connectivity within affected catchments. Furthermore, we found that the spatial connection of the sub-processes involved in these events (landslides, debris flows, and floods), is given by their overlap within the different process domains of basins.

This initial approach provides a preliminary understanding of the conditions that promote cascading torrential hazards in tropical regions, which can aid in developing more accurate hazard assessment tools and implementing effective strategies to mitigate risks in the tropics, considering its unique multi-hazard and complex setting.

How to cite: Arango, M. I., Hürlimann, M., Aristizábal, E., and Korup, O.: Widespread cascading torrential hazards in tropical regions , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14250, https://doi.org/10.5194/egusphere-egu24-14250, 2024.

EGU24-14699 | ECS | Posters on site | GM4.2

How will bedload transport respond to climate change in Alpine regions? The "ALTROCLIMA" project 

Felix Pitscheider, Anne-Laure Argentin, Mattia Gianini, Leona Repnik, Simone Bizzi, Stuart Lane, and Francesco Comiti

Alpine regions are among the areas that are the most intensely impacted by climate change. Predictions of how such changes affect meteorological conditions, as well as snow and ice cover and water discharge in mountain regions, are well established. However, how climate change has affected and will affect sediment transport in general and bedload transport in particular in such environments has yet to be studied.

Bedload transport within Alpine rivers is of ecological importance for river systems, impacts the economic efficiency of hydropower and is a critical parameter in assessing hydrogeological risks. This transport is determined by the sediment supplied to the river and the river's capacity to transport these sediments. These complex processes are closely intertwined with climatological conditions within a catchment, particularly in catchments with substantial glacial coverage. However, predicting how bedload transport behaves due to a changing climate is challenging.

This project fills this knowledge gap and investigates the link between bedload transport and rapid climate change in Alpine environments and aims to predict future trends for the current century. To reach this goal, a wide range of objectives has been set. We work towards providing the first reliable, multi-site quantification of past bedload transport changes under warming conditions, as well as to determine the role of geomorphic processes on bedload export in the analysed river networks. Furthermore, we are working on establishing modelling frameworks to predict subglacial and hillslope sediment supply as well as hydrological discharge to create a bedload transport modelling chain. The modelling chain is based upon the D-CASCADE model, which allows quantifying the spatio-temporal bedload (dis)-connectivity in river networks. Supplying the model with climatological and hydrological predictions enables the estimation of future bedload flux and erosion/deposition patterns under different scenarios. The approach for estimating the evolution of bedload transport will be developed and tested in the Solda (Italy) and Navisence (Switzerland) catchments, due to the data availability of the recent bedload transport history. Once validated and calibrated, the approach will be applied to further selected catchments.

In summary, the project aims to provide a decadal-scale quantification of changes in Alpine bedload transport due to climate warming and predict its evolution in the 21st century. We anticipate an initial increase in sediment transport with increasing glacial melt, driven by climate warming. However, this surge may be temporary as diminishing glaciers reduce their contribution to river discharge after a phase of maximum discharge rates. Beyond the academic value of this research, it will offer critical insights for water resource managers in Alpine regions.

How to cite: Pitscheider, F., Argentin, A.-L., Gianini, M., Repnik, L., Bizzi, S., Lane, S., and Comiti, F.: How will bedload transport respond to climate change in Alpine regions? The "ALTROCLIMA" project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14699, https://doi.org/10.5194/egusphere-egu24-14699, 2024.

EGU24-15047 | Orals | GM4.2

Assessing slope-river connectivity for evaluating cascading landslide hazards: A case study of Tordera river basin, NE Spain. 

Clàudia Abancó, Marta Guinau, Marta González, Jordi Pinyol, and Rosa M Palau

Landslides and torrential flows are among the most dangerous processes that occur on hillslopes, and they are mostly triggered by intense rainfall events. These phenomena are not only hazardous in themselves, but they can also have a more significant impact downstream when they interact with channels or the river network. When multiple landslides are simultaneously triggered by a rainfall event that affects an extensive area, they can initiate chains of further hazards due to the sudden and massive influx of sediment they bring onto channels and rivers. Therefore, it is crucial to study the connectivity between slopes and the river network to evaluate areas with a potentially higher sediment contribution to the river network. Ultimately, this information will help to assess flood hazards and mitigate risks, as well as assist in the planning of protective structures, drainage works, and other relevant measures.

We conducted a study on the slopes of the Tordera River basin (NE Spain). This river flows from the Montseny (Catalan Coastal range)  into the Mediterranean Sea. The study area was affected by a regional landslide event that occurred in January 2020 during the Gloria Storm (more than 480 mm of rainfall was measured in 96 hours in the region). We employed the index of connectivity, which is based on Borselli et al. (2008), to examine the connectivity between the slopes and the river network. The outcomes of this analysis were subsequently compared to a landslide inventory (more than 1000 mass movements) to determine whether the high amount of sediment present in the lowlands could have originated from landslides in the upper part of the basin.

According to the results of this study, slopes with high connectivity experienced a high density of landslides. The sediment that flowed down the slopes and reached the rivers added to the flood that occurred downstream. This flood carried a considerable amount of sediment which caused the widening of the active channel and the growth of the Tordera delta. The impacts of the Gloria storm on the infrastructure caused significant economic losses.

 

Borselli, L.;  Cassi, P.;  Torri, D. Prolegomena to sediment and flow connectivity in the landscape: A GIS and field numerical assessment, CATENA, Volume 75, Issue 3, 2008, Pages 268-277, ISSN 0341-8162, https://doi.org/10.1016/j.catena.2008.07.006.

How to cite: Abancó, C., Guinau, M., González, M., Pinyol, J., and Palau, R. M.: Assessing slope-river connectivity for evaluating cascading landslide hazards: A case study of Tordera river basin, NE Spain., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15047, https://doi.org/10.5194/egusphere-egu24-15047, 2024.

Under the background of global warming, the risk of geo-hazard in the cryosphere has increased with the retreat of glaciers. Several similar large-scale glacial debris flows with high mobility occurred in the southeast Tibet Plateau during the summer season which has drawn the attention of scientists. One typical event occurred on 10 September 2020 near Namcha Barwa Peak. The initial landslide finally changed into a glacial debris flow with high water content and high mobility under the condition of little precipitation. To solve the questions: 1) why is the glacial debris flow in southwest Tibet more prone in the warm season? 2) How is the initiation mechanism of this glacial debris flow with little rainfall? 3) What is the major source of water for this large debris flow? and 4) Which factors dominate the high mobility characteristic of this debris flow event? By conducting field investigation and comparing the satellite images before and after the event, we have revealed a rock-ice avalanche on the ridge above the landslide area to be contemporary with the event. This finding produced the hypothesis on the initiation process: rock-ice avalanche – moraine deposit failure – glacial debris flow, which has been inferred for many other similar events but not quantitatively proved. To test the hypothesis, we conducted thermal-hydraulic-mechanical coupled numerical modeling with the impact of freeze-thaw cycles and rock-ice avalanche on the stability of the moraine deposit. The results demonstrate that the avalanche event triggered the moraine landslide, with freeze-thaw cycles as the control factor. Generally, long-term freeze-thaw cycles alone are insufficient to set off the hazard chain. At the same time, seasonal temperature variation that controls ice-water phase change dominates the stability of moraine deposits under rock-ice avalanche in different seasons. In warm seasons, rock-ice avalanches would trigger moraine deposit failure more easily due to abundant water content that facilitates pore pressure increase, and liquefaction of moraine. By conducting multi-phase modeling of glacial debris flow, we have proven that the initial water content and entrainment of water during the development of the debris flow are the main water sources of this debris flow event. Moreover, the high water content in the initial landslide together with the entrainment process should also account for the high mobility characteristic of glacial debris flow. This work answered the long-lasting scientific questions about the initiation mechanism and dynamics of hyper-mobility glacial debris flow disaster chain under the background of climate change.

How to cite: Wang, T., Huang, T., and Shen, P.: Unravaling the cascading mechanisms of rock-ice avalanche triggering hyper-mobility glacial debris flow in southeast Tibet, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15190, https://doi.org/10.5194/egusphere-egu24-15190, 2024.

EGU24-16937 | Orals | GM4.2 | Highlight

Cascading Hazards – the challenges to understand interactions 

Margreth Keiler

Cascading hazards come into focus of hazard and risk research in the last 15 years and is strongly connected to studies on multi-hazards and compound hazards. Unexpected cascading events and related casualties and losses of properties draw the attention to consider the possible amplified risks induced by cascading hazards.

The contribution will focus in the first part on key concepts in relation to cascading hazards and will address briefly the challenges which may occur due to the general terminological ambiguity because the term cascading hazards tends to be used interchangeably with multi-hazards, cascading events, cascading disasters, or compound hazards or events. The main focus is on the analyses of different types of interactions which may occur during a cascading hazard events and their dependency on time and space. In the second part, the main question addresses the influence of climate and environmental change on cascading hazards including the occurrence of cascading hazards, changes of types of cascading hazards or interactions within the cascading hazard event. Current challenges regarding the approaches used to analyse and better understand cascading hazards are presented as well as first ideas to answer the questions what is missing, what is needed and how it can be used for hazard and risk analysis/management. 

How to cite: Keiler, M.: Cascading Hazards – the challenges to understand interactions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16937, https://doi.org/10.5194/egusphere-egu24-16937, 2024.

EGU24-17658 | ECS | Posters on site | GM4.2

Addressing the 'Black Hole' amidst Sediment Connectivity and Multi-Hazards 

Ishmam Kabir, Bernhard Gems, Martin Rutzinger, and Margreth Keiler

‘Sediment Connectivity’ and ‘Multi-Hazard’ – two booming topics over the last decade; have experienced intensive methodological and conceptual developments. Research so far has acknowledged their interrelationships and established sediment connectivity as a crucial component in the framework of hazard and risk research, but mostly through the so called ‘single-hazard’ approaches. Sediment connectivity referring to the entire assemblage of connectivity network would by definition occupy a significant amount of space, which may often accommodate multiple interactive and interrelated hazards, making a single-hazard approach fairly inadequate and thus leaving a crucial research gap.

The primary aim of this study is to draw the attention of future research on this gap while attempting to address it through developing a new perspective to look into multi-hazard events. In line of that we propose a semi-quantitative index based on the classification of hazard events and their interactions through an inverse event tree approach – assuming a cascading process flow. The event classification is based on the type of interactions (e.g. process-process, triggering, impeding, structure-process, etc.) to facilitate the understanding and inclusion of the connectivity concept. The index would assess each step and the interlinkages of such cascading events and assign weights to them based on their significance from a sediment connectivity viewpoint. Furthermore, it would also address how these weights may alter the probabilities across the event tree. Overall, this study proposes a novel perspective into the inter-connectedness of geomorphic/sediment connectivity and multi-hazard events, in line with the ‘Gaia’ and ‘Systems’ theories. 

How to cite: Kabir, I., Gems, B., Rutzinger, M., and Keiler, M.: Addressing the 'Black Hole' amidst Sediment Connectivity and Multi-Hazards, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17658, https://doi.org/10.5194/egusphere-egu24-17658, 2024.

EGU24-18379 | Orals | GM4.2

Quantifying surface process dynamics during extreme events from storm characteristics and landslide inventories 

Marin Clark, Ries Plescher, Madeline Hille, Christoff Anderman, Chan-Mao Chen, Deepak Chamlagain, Dimitrios Zekkos, and A. Joshua West

Extreme precipitation events drive landsliding in many regions across the globe and are an important part of the erosional cycle and related hazards. The intensity and frequency of extreme events are likely increasing due to rising global temperatures, causing greater future threat to society and an urgent need to quantify the relationships between surface process dynamics and extreme events. In steep mountain belts, orography also plays a role in focusing precipitation and intensifying erosion. Yet, the influence of orography on the intensity-duration characteristics of extreme precipitation remains a subject of debate because we lack spatially distributed and high time-resolution gauge datasets needed to resolve convective-scale, short-duration storm events and satellite-derived precipitation products struggle to accurately resolve precipitation gradients over areas of high relief and altitude. Annual periods of monsoon-related landsliding in the Himalaya offer a natural laboratory in which to explore relationships between extreme precipitation, orography and landsliding processes. Here we scale the NASA’s Global Precipitation Measurement (GPM) IMERG 30-minute, 0.1x0.1 degree product with local rain gauge data to produce high-temporal resolution records used to characterize extreme rainfall events (EREs) in central Nepal where hundreds of shallow landslides occur each summer. Individual storms from the time series are defined using the average inter-accumulation time as a measure for the minimum dry period between storms and extreme storms are extracted from the series using a 90th percentile threshold for each gauge station. Variability in storm characteristics is defined using paired K-means agglomerative cluster and principal component analyses to evaluate spatial patterns in storm characteristics over a 10 year period compared to annual landslide inventories. Spatial patterns emerge that suggest orography increases the intensity and frequency of storms, which in turn focuses landsliding in specific, and potentially predictable, regions along the steep windward flank of the mountain belt.

How to cite: Clark, M., Plescher, R., Hille, M., Anderman, C., Chen, C.-M., Chamlagain, D., Zekkos, D., and West, A. J.: Quantifying surface process dynamics during extreme events from storm characteristics and landslide inventories, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18379, https://doi.org/10.5194/egusphere-egu24-18379, 2024.

EGU24-18653 | ECS | Posters on site | GM4.2

Seven decades of debris flow activity. Spatio-temporal observations at connected and disconnected debris flow fans to the Lake Plansee (AT). 

Natalie Barbosa, Carolin Kiefer, Juilson Jubanski, and Michael Krautblatter

Debris flow activity at Lake Plansee, Austria, is evident through numerous debris cones continuously transferring sediment to the lake. Lacustrine sediment records of fan deltas were used to analyze the debris flow activity since 2120 BCE with Kiefer et al. (2021) identifying a drastic increase in debris flow activity since 1920. Furthermore, the photointerpretation of historical aerial imagery combined with modeling of debris flow volumes at the northern slope of Lake Plansee since 1947 suggests an increased trend since the 1980s (Dietrich et al., 2016). Despite the lithological and climatic similarities between the slopes that surround Lake Plansee, debris cones at the northern slope are primarily connected to the lake, while those on the southern slope remain highly active but disconnected.

This contribution aims to advance our understanding of spatio-temporal dynamics on debris flow fans and factors influencing sediment connectivity to the lake. We revise the historical aerial imagery since 1952 to automatically detect ‚active‘ debris channels using image processing and derive time series of photogrammetric Digital Surface Models (DSMs) for change detection.We identified 34 debris catchments with debris flow activity since 1952. Our objectives include (i) analysis of the spatio-temporal patterns of erosion and deposition at each fan to trace their evolution, (ii) quantifying sediment transfer rates from connected fans to lake Plansee in the last 70 years, (iii) identifying the role of vegetation changes in debris fan evolution and (iii) refining our understanding of precipitation and temperature as controlling factors influencing debris flow activity and connectivity or dis-connectivity of active debris channels to lake Plansee. The presented results intend to comprehend the intricate patterns that lead to debris flow exhaustion and increased or decreased activity.

 

Dietrich, A., & Krautblatter, M. (2017). Evidence for enhanced debris-flow activity in the Northern Calcareous Alps since the 1980s (Plansee, Austria). Geomorphology, 287, 144-158.

Kiefer, C., Oswald, P., Moernaut, J., Fabbri, S. C., Mayr, C., Strasser, M., & Krautblatter, M. (2021). A 4000-year debris flow record based on amphibious investigations of fan delta activity in Plansee (Austria, Eastern Alps). Earth Surface Dynamics, 9(6), 1481-1503.

How to cite: Barbosa, N., Kiefer, C., Jubanski, J., and Krautblatter, M.: Seven decades of debris flow activity. Spatio-temporal observations at connected and disconnected debris flow fans to the Lake Plansee (AT)., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18653, https://doi.org/10.5194/egusphere-egu24-18653, 2024.

EGU24-19175 | Orals | GM4.2

Non-uniqueness in sediment transport in river network hydrology-sediment modelling 

Peter Molnar, Sascha Meierhans, Giulia Battista, Jacob Hirschberg, Jessica Droujko, and Scott Sinclair

Sediment cascades are a convenient way of conceptualizing the transfer of sediment from hillslope production areas, through the river network, to the river basin outlet. Distributed hydrology-sediment models play an important role in the prediction of these source-to-sink links, because they can explicitly connect water and sediment fluxes along topographically-driven pathways. Here, we provide some examples of such cascade-based hydrology-sediment model applications in alpine environments and some problems related to their use.

In particular, we highlight two critical problems with hydrology-sediment modelling that go beyond trivial model calibration difficulties. These address fundamental issues of (a) non-uniqueness in sediment source mixing, and (b) sediment supply limitations. The first problem of non-uniqueness is known in hydrological modelling as the curse when models perform well at basin outlets for the wrong reasons, misrepresenting hydrological processes within the basin. In geomorphology, this concept has not received the same level of attention. Here we show that even a calibrated physically-distributed hydrology-sediment model can be subject to non-uniqueness, and provide the same suspended sediment yields at the basin outlet with completely different combinations of sediment sources. Including sediment tracers in model validation helps to identify this problem, and it is also helpful to check simulations at sub-basin scales where we are closer to distinct sediment sources. The second problem of sediment supply limitations is a challenge for all models that rely on transport capacity formulas for sediment transport. In our experience, both supply and transport capacity limit sediment transport at the basin scale, and we need to include this in our models. For example, we show that supply limitations can completely change the seasonality of sediment yields and render many climate change impact studies worthless.

Finally, we argue that both problems above, at least for suspended load, can be partially addressed by novel monitoring. For example by low cost smart sensors that allow a distributed sensing of sediment fluxes above and below potential sediment sources at high resolutions, or by high resolution remote sensing to capture space-time variability in river turbidity. This kind of data can dramatically improve our ability to calibrate models, reduce non-uniqueness, and over the long term identify the key signatures of sediment supply in river systems. It is our opinion that improving the predictions of climate and environmental change effects on sediment yields requires both better model validation as well as new data.

How to cite: Molnar, P., Meierhans, S., Battista, G., Hirschberg, J., Droujko, J., and Sinclair, S.: Non-uniqueness in sediment transport in river network hydrology-sediment modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19175, https://doi.org/10.5194/egusphere-egu24-19175, 2024.

EGU24-19438 | ECS | Posters on site | GM4.2

Post-event forensic survey after a recent catastrophic flash flood in Central Spain: morphosedimentary and hydrodynamic reconstruction 

K. Patricia Sandoval-Rincón, Julio Garrote, Daniel Vázquez-Tarrío, Ana Lucía, Mario Hernández-Ruiz, María Ángeles Perucha, Amalia Romero, José Ortega, and Andrés Díez-Herrero

Catastrophic flash floods are among the deadliest and most damaging natural processes worldwide. Despite this, they are rarely well recorded in instrumental (e.g. rain gauges, gauging stations) and documentary records (archives and newspaper archives). For their analysis and future prevention, it is therefore essential to carry out post-event forensic studies to collect as much information as possible in the field, from which the morphodynamic, hydrological and hydraulic characteristics of these events can be reconstructed.

In early September 2023, an exceptional ‘cut-off low’ weather situation (DANA) crossed the centre of the Iberian Peninsula, causing heavy rainfall and flash floods in several river basins (Alberche, Perales, Grande, Guadarrama). There were seven deaths and hundreds of millions of euros of damage to property and infrastructure.

This work summarises all the post-event forensic analyses and field observations collected after this episode along the Grande-Perales-Alberche river system, consisting of: (i) documentation of the historical morphological changes of these rivers, obtained from old cartographies, geomorphological maps, aerial photographs and recent orthoimages; (ii) compilation of all meteorological (rainfall) and hydrological (flow) information available for the event; (iii) acquisition of aerial images and video recordings using drones; iv) field georeferencing with differential GPS of high water marks (HWM) and paleo-stage indicators (PSI); v) field topographic measurements; vi) detailed measurement of bedform parameters such as wavelength and amplitude of current ripples; vii) grain size and composition sampling of flood deposits.

With all this information and other still being collected (such as orthophotographs and post-event DEMs generated by digital photogrammetry techniques based on images taken by drones), detailed digital elevation models are obtained. All this information will be used as calibration and validation information for 2D hydrodynamic and landscape evolution numerical models that attempt to reproduce and predict this type of event in the study rivers.

How to cite: Sandoval-Rincón, K. P., Garrote, J., Vázquez-Tarrío, D., Lucía, A., Hernández-Ruiz, M., Perucha, M. Á., Romero, A., Ortega, J., and Díez-Herrero, A.: Post-event forensic survey after a recent catastrophic flash flood in Central Spain: morphosedimentary and hydrodynamic reconstruction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19438, https://doi.org/10.5194/egusphere-egu24-19438, 2024.

EGU24-20877 | ECS | Posters on site | GM4.2

Snow preparation in landslide scenarios under multi-hazard perspective: experiences from Lake Campotosto (Italy) 

Matteo Ferrarotti, Maria Elena Di Renzo, Gian Marco Marmoni, Carlo Esposito, and Salvatore Martino

Landslides are a natural land-forming process and their interaction with urbanized areas and infrastructures makes them one of the most common geo-hazards. Landslides are controlled by three macro-categories of factors, namely the “predisposing”, “preparatory”, and “triggering” ones. In particular, preparatory factors are time-changing and gradually reduce the slope stability without initiating the movement. Snow melting and accumulation are generally discussed in the literature as triggering factors of landslides, particularly shallow ones, although, the here presented approach focuses on their contribution as preparatory factors. In mountainous areas, snow loading and, especially, snow melting can increase the soil pore water pressure, causing a reduction of available strength. Their influence on soil stability is time-dependent and, in particular, changes cyclically throughout the year. Snow usually begins to fall in the late autumn and accumulates especially in winter, whereas in spring it melts, resulting in water infiltration into the soil and resistance reduction. In seismic areas, where earthquakes can act as triggers for shallow landslides, seismic action might discover different levels of soil weakness throughout the year depending on the season, resulting in distinct landslide scenarios.

This research illustrates some multi-hazard scenarios that consider earthquakes as triggering factor of landslides, varying the degree of saturation of soil covers. The case study is the area around Lake Campotosto (Italy), located in one of the Apennines areas with the highest amount of snowfall per year, is in the near fault sector of one of the most important seismogenic source of the Apennines (Mt. Gorzano Fault System) and is characterized by different sizes and mechanisms landslides.

The approach applied for generating landslide scenarios is the PARSIFAL (Probabilistic Approach for Rating Seismically Induced slope FAiLures), a probabilistic multi-hazard tool that includes a three steps procedure: 1) susceptibility analysis including differentiated approach for rock and earth failure mechanisms; 2) slope stability analysis; 3) synthetic mapping of generated scenarios, based on grid or slope units.

Preliminary research on the stability of soil covers under seismic conditions emphasizes importance of hydraulic conditions during earthquake, which also suggests the relevance of snow loading and, in particular, snow melting in regulating slope stability.

Further research is being done utilizing satellite and meteorological data, and geomorphological features, and then elaborating them using statistical and geostatistical tools, up to advanced computing.

The goal is to generate time-dependent landslide hazard scenarios by weighting the effects of snow precipitation throughout the year as a preparatory factor and adding a related tool to PARSIFAL.

The majority of these concepts are being studied at Sapienza's Department of Earth Sciences in the CN1 (National Centre for HPC, Big Data, and Quantum Computing) – Spoke5 PNRR Linea Tematica 1 (Reconstruction of multi-hazard scenarios from seismic source models to the simulation of seismic-induced instabilities), which aims at generating ground effects scenarios in terms of instabilities induced by nonlinear effects produced by the propagation of seismic waves from the seismogenic source to the surface, also considering geomorphological and geotechnical characteristics of the near subsurface.

How to cite: Ferrarotti, M., Di Renzo, M. E., Marmoni, G. M., Esposito, C., and Martino, S.: Snow preparation in landslide scenarios under multi-hazard perspective: experiences from Lake Campotosto (Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20877, https://doi.org/10.5194/egusphere-egu24-20877, 2024.

Torrential risk protection works have a long tradition in the Alps, where these measures have allowed more intensive use of the landscape since the twentieth century and form the basis for rational management of the risk of torrential floods. While the maintenance and management of protective works makes it possible to control their inevitable deterioration and to extend their life, the collapse of these systems should be always considered in the frame of the residual risk management. This work aims to i) analyse the catastrophic debris flow occurred on October 2018 in the Rotian river basin (Eastern Italian Alps) during which a series of check dams collapsed magnifying the event and causing a casualty and severe damages, and ii) to identify implications for hazard monitoring and management. The work is based on post-event investigations, witness accounts, remote sensing information and local station data, hydrogeomorphic data and models, and systematically analyses the geo-environment, climate conditions and check dam structural conditions which characterized the geohazard cascade of events. In particular, results from the application of a couple hydrological and hydraulic model for the triggering and propagation of the debris flows event are used to inform the analysis. The results from this work are exploited to inform a discussion about the future of these works, which concerns not only the structural and maintenance aspects of the single work, but also involves the risk management requests of the systems of works which in recent decades have evolved significantly.

How to cite: Marchi, L., Borga, M., Zugliani, D., and Rosatti, G.: Geohazard cascade and mechanism of large debris flows in the Rotian river basin (NE Italy): implications to hazard monitoring and management, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21166, https://doi.org/10.5194/egusphere-egu24-21166, 2024.

EGU24-4885 | ECS | Posters on site | GM4.4

The Sea Level during MIS5a, MIS5c in the Southwestern Coast of South Korea 

Huigyeong Ryu, Jun-Ho Lee, Hoi Soo Jung, and Jaeryul Shin

The study of marine terraces, which include a paleo-shoreline record, provides information on global sea level fluctuations and crustal uplift rates during the Late Quaternary period. This data is helpful in preparing for sea level rise in the upcoming 'Global boiling'. Currently, widely recognized sea level fluctuation curves are derived from oxygen isotope stages in ice cores and deep-sea cores. The data shows a 30-50m sea level fall during Marine Isotope Stage (MIS) 5d-5a. However, some studies conducted in various parts of the world have reported smaller declines in sea level than is commonly known. For instance, studies on the marine terraces of the east coast of the Korean Peninsula suggest that sea level may have been as low as -5 to -10 m during MIS5a and MIS5c. In this study, we investigated the marine deposits in Haenam, located on the southwestern coast of the Korean Peninsula. We found deposits in the sedimentary layers that correspond to MIS5c, which were located beneath layers formed during MIS5e. The age of the sediments was determined using optically stimulated luminescence (OSL) dating. Based on the altitude, formation process, and absolute age of the sediments, it is inferred that sea level was similar to the present during MIS5c in Haenam. Recent research on the southwestern coast of the Korean Peninsula has accumulated data on marine deposits formed during MIS5a and MIS5c. This paper presents the results of studies on sea level during MIS5a and MIS5c on the west and south coasts of the Korean Peninsula. This study suggests one perspective for MIS5a and MIS5c sea level across East Asia and to raise new questions. Specifically, the paper questions why sea levels are similar to present during what is known to be a glacial period. This study offers a fresh perspective on sea level fluctuations in East Asia and can improve our comprehension of the intricate correlation between sea level and climate change.

How to cite: Ryu, H., Lee, J.-H., Jung, H. S., and Shin, J.: The Sea Level during MIS5a, MIS5c in the Southwestern Coast of South Korea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4885, https://doi.org/10.5194/egusphere-egu24-4885, 2024.

EGU24-5716 | Posters on site | GM4.4 | Highlight

TerraceM 3.0: Advancing marine terrace mapping through integrated machine learning methods 

Julius Jara Muñoz, Jurgen Mey, Roland Freisleben, Kevin Pedoja, and Daniel Melnick

TerraceM is an open-source software written in MATLAB for mapping and analyzing marine terraces. In this latest release, TerraceM-3 has undergone significant evolution, which leverages the capabilities of machine learning to introduce an automated marine terrace mapping feature. This new version includes a neural network that has been meticulously trained with over 1000 mapped marine terraces. This allows TerraceM-3 users to effortlessly map marine terraces and precisely determine their elevation through the automated mapping of their shoreline angles. In addition, TerraceM-3 incorporates two new functionalities: 1) Photon profile mapping, which includes mapping of satellite LiDAR profiles from the IceSat-2 mission, which broadens the applicability of TerraceM-3 beyond the availability of topographic data. 2) Indicative meaning calculator that accounts for the factors that can alter the initial sea-level position using global datasets (wave conditions and tidal ranges). This method facilitates the direct assessment of uncertainties in the reconstructions of the paleo-sea-level based on marine terraces. TerraceM-3 is a complete toolkit for researchers and students engaged in marine terrace analysis by offering a unique blend of numerical methods, statistical analyses techniques and additional enhanced functionalities to precisely map marine terraces and using them as markers of tectonic deformation.

How to cite: Jara Muñoz, J., Mey, J., Freisleben, R., Pedoja, K., and Melnick, D.: TerraceM 3.0: Advancing marine terrace mapping through integrated machine learning methods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5716, https://doi.org/10.5194/egusphere-egu24-5716, 2024.

EGU24-8118 | ECS | Posters on site | GM4.4

Sea level oscillations within the Last Interglacial: insights from coral reef stratigraphic forward modelling 

Denovan Chauveau, Nikos Georgiou, Ciro Cerrone, Silas Dean, Anne-Morwenn Pastier, and Alessio Rovere

Understanding past sea-level variations is essential to constrain future patterns of sea-level rise in response to warmer climate conditions. Due to good preservation and the possibility to use various geochemical methods to date fossil sea-level index points, the Last Interglacial (Marine Isotope Stage (MIS) 5e; 130-116 ka ago) is often regarded as one of the best climate analogs for a future slightly warmer climate. Some MIS 5e coastal stratigraphic sequences, especially fossil coral reefs in tectonically stable areas, are characterized by abrupt shifts in their geological facies or steps within the reef topography, which have been often interpreted as proxies for abrupt sea-level fluctuations within the interglacial. However, the observational evidence and magnitude of such abrupt changes are controversial. Here, we run nearly 50 thousand simulations of a 2D kinematic reef model that can reproduce reef growth and demise through time. Our aim is to investigate the parameter space, the sea-level scenarios, and the processes by which double-stepped MIS 5e fossil reefs can form. Our results show that the only sea-level history that could explain the generation of an emerged MIS 5e backstepped reef is an abrupt rise in sea level, followed by a short-term peak. Any other multiple-stepped stratigraphy can be explained by the interplay between accommodation space, marine erosion, and bedrock slope, rather than by abrupt changes in sea level. 

How to cite: Chauveau, D., Georgiou, N., Cerrone, C., Dean, S., Pastier, A.-M., and Rovere, A.: Sea level oscillations within the Last Interglacial: insights from coral reef stratigraphic forward modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8118, https://doi.org/10.5194/egusphere-egu24-8118, 2024.

EGU24-8724 | Posters virtual | GM4.4

Two highstands during the last interglacial: insights from palaeoshorelines and marine terraced deposits of ionian coast of Apulia 

Vincenzo De Santis, Paolo Montagna, Giovanni Scicchitano, Giuseppe Mastronuzzi, Edwige Pons Brancu, Giovanni Scardino, Josè Eugenio Ortiz, Yolanda Sanchez Palencia, Trinidad Torres, and Massimo Caldara

Geomorphological studies in the Ionian Sea margin of Apulia region (southern Italy) enabled the identification of

1) three terraced deposits: TD1, TD2, and TD3, divided in several sub-units;

2) three related palaeoshorelines: PS1, PS2, PS3.

The higher PS2 (30±2 m a.p.s.l.) dates to the first highstand of MIS 5.5. The ages of 127.851±1.47 and 128.4±26.2 ky BP from the sub-units of TD2 marking the transgression, suggest that at ca. 128 ky BP the transgression toward the first highstand of MIS 5.5 was still occurring.

The lower PS3 (19±2 m a.p.s.l.) dates to a second highstand of MIS 5.5. The age of 122.49 ±1.25 ky BP from TD3 is the most reliable chronological constraint for this second highstand.

Also considering the above mentioned contraints, and since it was not possible to attribute an absolute age for the TD2 sub-units which mark the first MIS 5.5 highstand, we adopt, in this paper, for the first highstand of MIS 5.5, the age given by Kopp et al. (2013), namely between 125 and 123 ky BP.

In particular we considered two possible scenarios:

1) scenario 1, assuming the first highstand of MIS 5.5 at 125 ky BP

2) scenario 2, assuming the first highstand of MIS 5.5 at 123 ky BP

In both scenarios, we considered a mean sea level value during the first highstand of MIS 5.5 at + 7.5±1.5 m. We then calculated the uplift rate of PS2 for both scenarios, assuming a constant rate up to present.

With these assumptions, we tentatively calculate the position of PS3 at ⁓ 122 ky and of the dated layer of the lowest transgressive sub-unit of TD2 (today at +3.80 m, dated at ⁓ 128 ky BP), this latter assumed as deposited from 5 to 10 metres of water depth.

A mean uplift rate of ca. 0.18 mm/yr was quantified, with a minimum possible of 0.15 mm/yr and a maximum possible of 0.21 mm/yr, for both scenarios. This range of uplift rates fits well within the regional setting.

Accordingly, the mean elevation of PS3 at time of its formation (i.e., the sea level at ⁓122 ky BP, namely the second highstand of MIS 5.5) was -2.96 and -3.32 m for scenario 1 and 2, respectively. Taking into account all the uncertainties in PS2 and PS3 elevations, and in sea level at the first highstand of MIS 5.5, the whole range of the RSL values during the second highstand of MIS 5.5 is -8.38 to +2.45 m for scenario 1, and -8.79 to +2.15 m for scenario 2.

On the other hand, using the three possible values of uplift rate, we calculated also the position and then the sea level indicated by the dated layer at ⁓ 128 ky BP at Torre Castelluccia, which ranged from -5.5 to -18.08 m, with a mean value of -11.79 m.

Finally, we hypotesise that the observed alternating abundance of marine gastropods Bolma rugosa (Linneo) and Thetystrombus latus (Gmelin) across the recognised deposits can be interpreded as a palaeoclimatic indicator, although in a merely qualitative way and, for now, only in the study area.

 

 

 

How to cite: De Santis, V., Montagna, P., Scicchitano, G., Mastronuzzi, G., Pons Brancu, E., Scardino, G., Ortiz, J. E., Sanchez Palencia, Y., Torres, T., and Caldara, M.: Two highstands during the last interglacial: insights from palaeoshorelines and marine terraced deposits of ionian coast of Apulia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8724, https://doi.org/10.5194/egusphere-egu24-8724, 2024.

EGU24-15894 | ECS | Posters on site | GM4.4

OSL Dated Sea-Level for MIS 5e Interglacial in South Carolina, United States 

Silas Dean, Nikos Georgiou, Robert K. Poirier, William R. Doar III, Dominik Brill, Denovan Chauveau, Ciro Cerrone, and Alessio Rovere

The degree to which the Last Interglacial (Marine Isotope Stage 5e; ~125,000 Before Present) can serve as an analog for future sea-level rise caused by anthropogenic climate change is a matter of great importance. Refining knowledge of factors such as glacio-hydro-isostatic conditions and ice-sheet histories leading up to and since the Last Interglacial will help resolve this question, and well-constrained, well-dated indicators of relative sea level will provide crucial data towards this end. We conducted stratigraphic surveys on several well-exposed outcrops along the Intercoastal Waterway canal near Myrtle Beach, South Carolina, on the East Coast of the United States. In addition to photogrammetry records of the outcrop, optically stimulated luminescence analysis has produced new dates that provide information about sea level history during the Last Interglacial and subsequent interstadials, while also helping to clarify the complex local stratigraphic context, which consists of a series of coastal beach ridges and paleoshorelines left by highstands. The dates are linked to precisely constrained DGPS elevations referenced to the local hydrographic datum, a technique which has not been widely used in the study area. The new data will be preserved as sea-level index points in the format specified by the World Atlas of Last Interglacial Shorelines as part of the WARMCOASTS project and are an especially important contribution since they add additional points in a passive margin area considered to be tectonically stable since the investigated time period.

How to cite: Dean, S., Georgiou, N., Poirier, R. K., Doar III, W. R., Brill, D., Chauveau, D., Cerrone, C., and Rovere, A.: OSL Dated Sea-Level for MIS 5e Interglacial in South Carolina, United States, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15894, https://doi.org/10.5194/egusphere-egu24-15894, 2024.

EGU24-16272 | Posters on site | GM4.4 | Highlight

Geomorphological signatures of known climatic extreme events and validation of theoritical emplacement approach: Boulders on Cuban low-lying Marine Terraces  

Christine Authemayou, Pedro Luis Dunán Avila, Marion Jaud, Kevin Pedoja, Julius Jara Muñoz, Leandro Peñalver Hernández, France Floc'h, Stéphane Bertin, Arelis Nuñez Labañino, Pedro de Jesus Benítez Frometa, Hassan Ross Cabrera, pauline Letortu, Angel Raúl Rodríguez Valdés, Noel Coutín Lobaina, and Denovan Chauveau

To assess coastal hazard where Coastal boulder deposits (CBDs) are found, it is crucial to constrain the forces governing their emplacement: from either storms/tropical cyclones or tsunamis. Here we focus on the CBDs on the island of Cuba and the extreme climatic events responsible for their formation. Four sites are being studied to identify the CBDs produced during known hurricanes over the last fifty years.The selected CBDs are located on a low-lying coral reef terrace on the Cuban shore, emplaced by the Cuban hurricane of 1935, Lili hurricane of 1996 and Matthew hurricane of 2016. These meteorological events associated with reported geomorphological objects are analyzed to quantify the hydrodynamic parameters of such extreme events (maximum orbital velocity). Furthermore, the quantification of CBDs volume by stereophotogrammetry (using Agisoft Metashape Professional version 1.7.2) and CBDs density by water immersion method on samples allow us to use deterministic and theoretical approaches ( hydrodynamics equations of Nandasena et al., 2013, 2022 ) to assess the assumed associated hydrodynamic parameters (minimum flow velocity) responsible for the dislocation of the coral reef terraces and transport of the resulted boulders. Finally, we compare these velocities with ones  calculated from the meteorological  events to discuss the reliability of these approaches to determine the climatic or tsunamigenic origin of the past extreme waves from geomorphological analyses of CBDs.

How to cite: Authemayou, C., Dunán Avila, P. L., Jaud, M., Pedoja, K., Jara Muñoz, J., Peñalver Hernández, L., Floc'h, F., Bertin, S., Nuñez Labañino, A., Benítez Frometa, P. D. J., Ross Cabrera, H., Letortu, P., Rodríguez Valdés, A. R., Coutín Lobaina, N., and Chauveau, D.: Geomorphological signatures of known climatic extreme events and validation of theoritical emplacement approach: Boulders on Cuban low-lying Marine Terraces , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16272, https://doi.org/10.5194/egusphere-egu24-16272, 2024.

EGU24-16538 | ECS | Posters on site | GM4.4

Last Interglacial sea-level proxies along the Brazilian western Atlantic coasts 

Ciro Cerrone, Luca Lämmle, Giovanni Scicchitano, Archimedes Perez Filho, Denovan Chauveau, Nikos Georgiou, Silas Dean, and Alessio Rovere

Geological sea-level proxies, such as fossil intertidal or foreshore deposits, store fundamental information that allow reconstructing past changes in sea level, which may be used to evaluate the volume of ice sheets during past warm periods. Studies on Last Interglacial (LIG; Marine Isotope Stage 5e, ~ 125 ka) sea-level proxies are particularly important, as this highstand is a process analogue for the current interglacial, including warming caused by human greenhouse gas emissions. In fact, the LIG was characterized by slightly higher temperatures than the pre-industrial, that caused higher global sea level and, in turn, smaller ice-sheets.

This work was done in the framework of the WARMCOAST Project funded by the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovative Program (Grant Agreement No. 802414). This part of the project aims at surveying new geological sea-level proxies along the western Atlantic Brazilian coast, from Rio Grande do Sul to São Paulo and in southern Bahia State. Classical geological and geomorphological surveys were carried out in the field. We collected several samples for OSL dating and micropaleontological analysis. Samples consist mostly of shallow-water marine sands of supposed LIG age. The elevation of each proxy has been measured by a GNSS RTK station with centimetric precision and referred to a local geoid model (MAPGEO2015).

In this work, we report the results of the field campaign along the Brazil coast and, the new data are interpreted in terms of Glacio-Isostatic Adjustment processes affecting the coasts since the Last Interglacial. 

How to cite: Cerrone, C., Lämmle, L., Scicchitano, G., Perez Filho, A., Chauveau, D., Georgiou, N., Dean, S., and Rovere, A.: Last Interglacial sea-level proxies along the Brazilian western Atlantic coasts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16538, https://doi.org/10.5194/egusphere-egu24-16538, 2024.

EGU24-17200 | Posters on site | GM4.4

Quaternary and Pliocene sea-level changes at Camarones, central Patagonia, Argentina 

Alessio Rovere, Karla Rubio Sandoval, Deirdre D. Ryan, Sebastian Richiano, Luciana M. Giachetti, Andrew Hollyday, Jordon Bright, Evan J. Gowan, Marta Pappalardo, Jacqueline Austermann, and Darrell S. Kaufman

Geological indicators of past relative sea level changes are fundamental to reconstruct the extent of former ice sheet during past interglacials, which are considered analogs for future climate conditions. Four interglacials, dating from Holocene to Pliocene, have left sea-level imprints in the proximity of the coastal town of Camarones in Central Patagonia, Argentina. Sea-level index points were preserved as beach ridges deposited by storm waves above modern sea level. We used highly accurate survey techniques to measure the elevation of these deposits. Satellite-derived wave measurements and wave runup models were then employed to calculate their indicative meaning (i.e., their elevation with respect to sea level at the time of deposition). The paleo relative sea levels (i.e., uncorrected for post-depositional vertical land motions) associated with the four interglacials (with 1σ uncertainties) are 6±1.5 m (Holocene); 8.7±2.1 m (MIS 5e); 14.5±1.5 m (MIS 9 or 11); and 36.2±2.7 m (Early Pliocene). Ages have been obtained using both published (U-series, Electron Spin Resonance, and Radiocarbon) and new (Amino Acid Racemization and Radiocarbon) dating constraints. We compare our results with published glacial isostatic adjustment and mantle dynamic topography predictions, and we highlight that refining these models before calculating the global mean sea level for the interglacials mentioned above is necessary. Our high-resolution data provide a significant benchmark for paleo relative sea-level studies in the Southwestern Atlantic.

This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 re- search and innovation programme (grant agreement no. 802414)

How to cite: Rovere, A., Rubio Sandoval, K., Ryan, D. D., Richiano, S., Giachetti, L. M., Hollyday, A., Bright, J., Gowan, E. J., Pappalardo, M., Austermann, J., and Kaufman, D. S.: Quaternary and Pliocene sea-level changes at Camarones, central Patagonia, Argentina, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17200, https://doi.org/10.5194/egusphere-egu24-17200, 2024.

EGU24-17311 | ECS | Posters on site | GM4.4

Early-to-Late Holocene Emerged Fossil Corals along the Negros Trench Forearc, Philippines 

Lyndon Nawanao, Noelynna Ramos, Robelyn Mangahas, Hsun-Ming Hu, and Chuan-Chou Shen

Corals have been used as proxies of relative sea-level (RSL) change and key inputs in refining glacial isostatic adjustment (GIA) models globally. Along subduction zones, interseismic, coseismic, and postseismic processes act as local drivers of relative sea-level changes, which can also be used to elucidate past tectonic deformation. In this study, we present new radiometric (Th-230) ages of marine-limiting sea-level proxies (i.e., emerged fossil coral reefs) along the coasts of Southwest Panay Peninsula and Nogas Island facing the Negros Trench forearc. Real-time kinematic (RTK) GNSS and drone surveys were conducted to determine the elevations relative to the tide datum and the extent of the emerged fossil coral reefs. In the Southwest Panay Peninsula, emerged fossil coral reefs were observed at 4.20 m and 3.967–4.647 m above mean low low water (amllw), with Th-230 ages of 12.44 kya and 8.65–8.82 kya BP, respectively. About 15 km from the trench forearc, Mid-Holocene emerged fossil coral reefs dated 6.37–7.55 kya BP with elevations 1.596–2.810 m amllw. Late Holocene emerged fossil coral reefs were dated 4.33–1.48 kya BP with elevations 1.256–2.280 m amllw. On the western side of Nogas Island facing the trench forearc, emerged fossil coral reef platforms dated 1.08–1.66 kya BP with elevations 1.446–1.960 m amllw. The calculated RSL of these marine-limiting sea-level indicators is generally higher compared to the ICE-6G C and ICE-7G NA sea-level curve models and other coral proxies in Southeast Asia and Palawan that have relatively low tectonic deformation activities. In this study, we highlight the spatiotemporal variability of RSL coral proxies in local scales along the trench forearc. These initial results further imply active tectonic deformation induced along the Negros Trench since the Holocene. 

 

Keywords: fossil coral reefs, relative sea level, Holocene, Negros Trench forearc, Southwest Panay Peninsula, Nogas Island, Philippines

How to cite: Nawanao, L., Ramos, N., Mangahas, R., Hu, H.-M., and Shen, C.-C.: Early-to-Late Holocene Emerged Fossil Corals along the Negros Trench Forearc, Philippines, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17311, https://doi.org/10.5194/egusphere-egu24-17311, 2024.

EGU24-20690 | ECS | Posters on site | GM4.4

Interglacial beach ridge plains across the northern Gulf of Mexico 

Nikos Georgiou, Silas Dean, Alexander R. Simms, Denovan Chauveau, Ciro Cerrone, and Alessio Rovere

During past Interglacial periods, global ocean volume increased as a result of the higher temperatures and the melting of ice sheets, consequently leading to a rise in global sea levels. However, on timescales ranging from years to a few decades, regional sea level variability deviates from the global pattern, due to a combination of vertical land movements (earth’s crust viscoelastic response to glacial and ice sheet melting, tectonics), thermohaline circulation, wind forcing and land water storage. Therefore, decoding the regional sea-level variability during Interglacial periods is crucial for advancing climate models’ precision, especially for vulnerable coastlines.

Beach ridge plains are valuable fossil geological archives, offering significant potential for the analysis of sea-level fluctuations, climatic shifts and catastrophic events. The extraction of these information can be achieved through the measured elevation of the dune-beach contact and the beach berm, the analysis of the fossil beach ridge orientation, the geometry of the internal stratigraphy and by dating of the beach deposits using optically stimulated luminescence (OSL) signals from quartz.

In this study, we present results from our fieldwork campaign in the northern Gulf of Mexico, where we utilized a GNSS RTK station to obtain centimeter-level precision in measuring the elevation of the beach ridge sets, originally detected through freely available LIDAR datasets. Concurrently, a Ground Penetrating Radar (GPR) was employed to determine the stratigraphy of the beach ridge plains. Both surveyed areas, Apalachicola and Pensacola, contain fossil beach ridge sets varying in elevation from +2.5m up to a maximum of +7.5-8m above mean sea level, detected in more inland locations. Recent studies suggest that during the Last Interglacial period sea level in the area reached up to ~5m. The exact timing of the formation of the more elevated inland beach ridges remains uncertain, as does the question of whether their present elevation is attributable to post-Last Interglacial vertical land movements. Through in-depth analysis of the data collected during the WARMCOASTS ERC project, we aim to unravel the formation processes of these beach ridges and trace their development and evolution over time.

How to cite: Georgiou, N., Dean, S., Simms, A. R., Chauveau, D., Cerrone, C., and Rovere, A.: Interglacial beach ridge plains across the northern Gulf of Mexico, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20690, https://doi.org/10.5194/egusphere-egu24-20690, 2024.

EGU24-82 | ECS | Orals | HS7.5

Proposal for a new meteotsunami intensity index. 

Clare Lewis

Atmospherically generated coastal waves labelled as meteotsunami are known to cause destruction, injury and fatality due to their rapid onset and unexpected nature. These progressive shallow water waves with a period of 2 to 120 minutes tend to be initiated by sudden pressure changes (±1 mb over a few tens of minutes) and wind stress from moving atmospheric systems out on the open water. As these waves arrive at the shoreline they are amplified by localised resonances. Unlike other related coastal hazards such as tsunami, there exists no standardised means of quantifying this phenomenon which is crucial for understanding its impacts and to establish a shared language and framework for meteotsunami analysis and comparison.

In this study, we present a new 5-level Lewis Meteotsunami Intensity Index (LMTI) primarily trialled in the United Kingdom (UK) but designed for global applicability. A comprehensive dataset of meteotsunami events recorded in the UK were verified and applied to the index which yielded results that identified a predominant occurrence of Level 2 or moderate intensity meteotsunamis (69%), with distinct hotspots identified in Southwest England and Scotland. Further trial implementation and calibration of the LMTI in a global capacity revealed its adaptability to other meteotsunami prone regions facilitating the potential for further research into preparedness and hazard mitigation strategies.

How to cite: Lewis, C.: Proposal for a new meteotsunami intensity index., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-82, https://doi.org/10.5194/egusphere-egu24-82, 2024.

EGU24-611 | ECS | Posters virtual | HS7.5

Hydrological Analysis of Monsoon Rain Spells in the Indian Ganga Basin over the Last Century 

Amit Kumar Maurya, Somil Swarnkar, and Shivendra Prakash

The Indian Ganga Basin (IGB) is a highly prominent socioeconomic region in the Indian subcontinent. The IGB supports about 500 million individuals by providing sufficient freshwater for agro-industrial activities, mainly through the contribution of Indian Summer Monsoon (ISM) rainfall, which accounts for around 85% of the total rainfall received throughout the IGB. Any modifications in ISM patterns would substantially impact the availability of freshwater, and consequently, the socio-economic activities of the IGB region will be affected. This study aims to evaluate the historical changes in the monsoon rainfall characteristics from 1901 to 2019. Here, we conducted a detailed rainfall analysis in different sub-basins of the IGB where changes in monsoon rain spells are most noticeable and examined the hydrological extremes. We found that monsoon rain spell peaks have significantly increased across the major sub-basins of the IGB after 1960, implying the increased probability of flash flood hazards. At the same time, the monsoon rain spell has been depleted across the IGB after 1960, especially in the lower Indo-Gangetic plains. These results imply a rise in the occurrence of droughts. In addition, our interpretations also indicate a growing potential for combined hydrological extremes in the IGB. Further, the continuous rise in temperature and human-induced perturbations might exacerbate the existing extreme hydrological conditions. Thus, the findings of this study will be beneficial in implementing river basin management methods to assess the complex patterns of major hydrological catastrophes in the IGB.

How to cite: Maurya, A. K., Swarnkar, S., and Prakash, S.: Hydrological Analysis of Monsoon Rain Spells in the Indian Ganga Basin over the Last Century, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-611, https://doi.org/10.5194/egusphere-egu24-611, 2024.

EGU24-669 | ECS | Orals | HS7.5

Assessing Local Community Vulnerability to Landslides and Floods: A Household Survey Approach in North-Western Rwanda  

Clemence Idukunda, Caroline Michellier, Emmanuel Twarabamenye, Florence De Longueville, and Sabine Henry

North-Western Rwanda's hilly and mountainous topography, high elevation, frequent torrential rainfall, and high population density render it highly susceptible to landslides and floods. A comprehensive understanding of community vulnerability to these hazards is crucial for effective risk assessment and mitigation strategies. To address data scarcity in the region, this study is based on a household survey approach that incorporates hazard-specific variables to compare vulnerability across three hazard categories: landslides, floods, and a combination of both. The survey encompasses 904 households across 50 cells (local administrative units), purposively selected according to hazard susceptibility distribution. Principal Component Analysis (PCA) was applied to derive a contextualized Social Vulnerability Index (SoVI). Five principal components accounting for 73.2% of the variance were identified. The first component, contributing 23.4%, highlights the vulnerability associated with unplanned settlements and low income. The second component, representing 19.5% of the variance, emphasizes demographic and social factors. The third component (12.6% of the variance) points to the vulnerability of households solely reliant on agriculture for their income. The fourth component (9% variance) is associated with land ownership, with households lacking land assets experiencing lower vulnerability. The fifth component (8.7% variance) underlines the relevance of household structure variables, indicating the high vulnerability of single-person households. SoVI scores classified 19 cells in the very high or high vulnerability category, predominantly those prone to landslides. These highly vulnerable cells are concentrated in the Northern Province, emphasizing the need to prioritize interventions in this region, such as effective land use planning and livelihood improvement strategies. This study provides a comprehensive vulnerability assessment and valuable insights for prioritizing interventions. The inclusion of hazard-specific variables and a comparative vulnerability approach across areas susceptible to landslides, floods, and both hazard types enhances the specificity and applicability of the findings. These insights are invaluable for local policymakers and disaster prevention and management authorities, enabling them to develop context-specific strategies to improve community resilience and reduce vulnerability to natural hazards.

Keywords: Community Vulnerability, Landslides, Floods, Noth-Western Rwanda, Social Vulnerability Index

How to cite: Idukunda, C., Michellier, C., Twarabamenye, E., De Longueville, F., and Henry, S.: Assessing Local Community Vulnerability to Landslides and Floods: A Household Survey Approach in North-Western Rwanda , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-669, https://doi.org/10.5194/egusphere-egu24-669, 2024.

EGU24-677 | ECS | Orals | HS7.5 | Highlight

A new climate impact database using generative AI 

Ni Li, Wim Thiery, Jakob Zscheischler, Gabriele Messori, Liane Guillou, Joakim Nivre, Olof Görnerup, Seppe Lampe, Clare Flynn, Mariana Madruga de Brito, and Aglae Jezequel

Storms, heat waves, wildfires, floods, and other extreme weather climate-related disasters pose a significant threat to society and ecosystems, which in many cases is being aggravated by climate change. Understanding and quantifying the impacts of extreme weather climate events is thus a crucial scientific and societal challenge. Disaster databases are extremely useful for establishing the link between climate events and socio-economic impacts. However, publicly available data on impacts is generally scarce. Apart from existing open disaster databases such as EM-DAT, robust data on the impacts of climate extremes can also be found in textual documents, such as newspapers, reports and Wikipedia articles. Here we present a new climate impact database that has been built based on multiple public textual entries using a pipeline of data cleaning, key information extraction and validation. In particular, we constructed the database by using the state-of-the-art generative artificial intelligence language models GPT4, Llama2 and other advanced natural language processing techniques. We note that our dataset contains more records in the early time period of 1900-1960 and in specific areas such as than the benchmark database EM-DAT. Our research highlights the opportunities of natural language processing to collect data on climate impacts, which can complement existing open impact datasets to provide a more robust information on the impacts of weather and climate events.

How to cite: Li, N., Thiery, W., Zscheischler, J., Messori, G., Guillou, L., Nivre, J., Görnerup, O., Lampe, S., Flynn, C., Madruga de Brito, M., and Jezequel, A.: A new climate impact database using generative AI, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-677, https://doi.org/10.5194/egusphere-egu24-677, 2024.

Climate change, an increasing urban population, and poor urban planning have increased flood-risk and the accompanying solid waste challenge in many coastal urban areas in developing countries. These challenges are more pronounced in informal settlements because: (a) they are often built on environmentally fragile locations such as river banks and coastal shores with high exposure to floods, (b) high poverty levels among residents resulting in low adaptive capacity, and (c) marginalisation of these localities emanating from their non-recognition in the larger city framework. Against this background, flood-risk assessments and response initiatives in these areas have primarily been informed by scientific approaches such as geographical information systems, without adequate incorporation of other forms of knowledge. Using the case of the coastal city of Durban, South Africa, our project explores the benefits of combining perspectives from different knowledge systems in understanding flood-risk and the accompanying solid waste challenge in urban informal settlements, towards developing solutions that are based on contextual and experiential aspects. Methodological techniques used include interviews and workshops with key experts and with informal settlement residents, and extensive reviews of literature.  Emerging findings show that holders of scientific, practitioner, and local knowledge vis-à-vis flood risk and waste management are active in the selected case study informal settlement. They have, in isolated cases, collaborated particularly around a) generation and distribution of flood early warnings, b) river clean-up initiatives, and c) catchment rehabilitation projects, with clear benefits for flood resilience and solid waste management. We find that there is need for a clear framework for integrating knowledge systems towards flood resilience and solid waste management in these contexts and the project has developed a draft framework. Integrating knowledge systems will: i) ensure the participation of different actors in mapping flood risk thereby creating a sense of ownership and ensuring uptake of and support for solutions crafted to deal with flood risk and the solid waste challenge; and ii) open up opportunities for coordinated support from various actors for a range of decisions around flood risk response preparation, flood and waste infrastructural design and mitigation of waste-induced flood destruction of infrastructure.

How to cite: Johnson, K. and Nyamwanza, A.: Integrated knowledge systems towards flood resilience and sustainable solid waste management in South African urban informal settlements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-867, https://doi.org/10.5194/egusphere-egu24-867, 2024.

EGU24-2163 | ECS | Posters on site | HS7.5

Climate risk-reduction potential of gridded precipitation data for agricultural index-based insurance development 

Sarvarbek Eltazarov, Ihtiyor Bobojonov, and Lena Kuhn

Index insurance has been introduced as an innovative and potential solution to mitigate several challenges caused by climate change in the agricultural sector. Despite the promising potential of index insurance, dissemination in developing countries is slow due to a lack of reliable weather data, which is essential for the design and operation of index insurance products. The increasing availability of model- and satellite-based data could ease the constraints of data access. However, their accuracy and suitability have to undergo a thorough assessment. Therefore, this study statistically and financially analyzes and compares the risk reduction potential of index insurance products designed employing various in-situ-, model- and satellite-based precipitation products (e.g., CMOPH, CPC, IMERG, GSMaP, MERRA, GLDAS, ERA5, PERSIANN, MSWEP, and MERRA2). This study employed county-level spring wheat yield data between 1982 and 2018 from 56 counties overall in Kazakhstan and Mongolia. The results showed that in the majority of cases in both countries, the hedging effectiveness of index insurance products designed based on IMERG is the highest. Moreover, among other data sources, the index insurance products designed using the PERSIANN, GLDAS and FLDAS showed higher risk reduction potential. Overall, this study highlights that satellite- and model-based precipitation products have higher accuracy and potential for index insurance design and operation than in-situ-based precipitation data.

How to cite: Eltazarov, S., Bobojonov, I., and Kuhn, L.: Climate risk-reduction potential of gridded precipitation data for agricultural index-based insurance development, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2163, https://doi.org/10.5194/egusphere-egu24-2163, 2024.

A severe and complex, polygenetic flood event occurred in Muktinath area of Mustang, Nepal on the evening of August 13, 2023 causing significant damage to property and infra-structures worth approximately of USD 7.4 million at Kagbeni Village, which is nestled along both banks of Kagkhola, a major left bank tributary of the Kali Gandaki River. About 29 houses, 1 motorable bridge, 1 steel truss bridge and 3 temporary bridges were destroyed, while more than 25 cows and other livestock were killed. Fortunately, human lives were spared because the community was warned to move to safety before the mud and sludge hit the village. A study was conducted in order to know what had caused this unusual flash-flood in Mustang. Kagbeni (2810 m) lies in the north Himalayan, rain-shadow area and normally receives few rainfall (<300 mm/yr). However, for several years, the trend (confirmed by local residents) has been towards increased rainfall, leading to more landslides and floods. Although rainfall data from the nearest monitoring station, Jomsom (2720 m), shows that rainfall was high, there is not detailed information about the rainfall amount at Jhong (3600 m), and Muktinath  (3760 m), source area of Kagbeni flood. From the video taken there (Jhong, Muktinath) during this flash-flood event (hyper-concentrated flow), it can be concluded that it was a landslide lake outburst flood. However due to the difficult terrain and inaccessible path, it has not yet been possible to visit the source area of the landslide in detail. Heavy rainfall over a short period and flash-flood-like disasters are becoming a trend in the mountain regions in Nepal. Furthermore, this part of Mustang is fragile (Spiti shales), and heavy rainfalls have an immediate impact, since there is little soil to absorb the excess water. Former studies have also shown that temperature in Mustang is rising which is causing the monsoon air to move northward and upward. As a result, more rainfall is taking place in Trans-Himalayan areas like Mustang and Manang (North of Annapurna Himal, 8091 m). Therefore, it is believed that climate change and the rise in temperature could be the significant reasons for heavy rainfall that caused such a flash-flood in Kagbeni, Mustang. On the other hand, people are inviting disaster in Kagbeni by settling on the very low terraces or in flood-plains and encroaching on the bed of the local Kagkhola. Given the fragile geology of upstream area of Kagkhola, ongoing anthropogenic activities (agriculture and tourism) and the effect of climate change, the possibility of flash floods reoccurring in the future at Kagbeni remains high. Sadly, locals at Kagbeni have already started rebuilding houses damaged by the recent Kagbeni flood and continue to live in potentially threatened flood plains.   

How to cite: Fort, M., Gurung, N., Arnaud-Fassetta, G., and Bell, R.: Retrospect of the polygenetic Kagbeni flood event (August 13, 2023) in Mustang, Nepal. Are rapid hydromorphological processes relays and sediment cascades in the catchment well taken into account in the risk equation?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2563, https://doi.org/10.5194/egusphere-egu24-2563, 2024.

EGU24-3076 | ECS | Orals | HS7.5

Assessing Surface Drainage Efficiency in Urban Pluvial Flood Hazard and Risk Mitigation: A Case Study of Braunschweig City 

Shahin Khosh Bin Ghomash, Heiko Apel, Kai Schroeter, and Max Steinhausen

Due to rapid urbanization and the increase of extreme precipitation events driven by climate change, urban areas have experienced more frequent and severe pluvial floods in recent years. This trend is anticipated to continue in the future. One of the causes of flooding in these urban zones is the limited effectiveness or temporary reduction in surface drainage capacity, even when storm sewers adhere to technical standards. A notable instance was the June 2023 flooding in Braunschweig, situated in Lower Saxony, Germany, where the city received 60 liters per square meter of rainfall within a short time span, largely excessing sewer system capacity and leading to widespread inundation.

This research investigates the impact of implementing diverse strategies aimed at expanding urban drainage capacity to mitigate pluvial flood risk in Braunschweig. To accomplish this, a moderately detailed hydrodynamic model for the city was set up using the RIM2D hydrodynamic model, allowing for quick computational processing times which enabled the exploration of various measures through sensitivity analysis. The setup involved employing a high-resolution digital elevation model and various remote sensing data for land classification. The model incorporated high-resolution precipitation radar data from the 2023 event and additional precipitation scenarios of varying occurrence probabilities. Validation of the model against available event data and existing flood hazard maps specific to Braunschweig was conducted.

The validated model was then utilized to assess the effectiveness of different surface de-sealing scenarios within the city. These scenarios aim to enhance drainage capacity by means of increased infiltration to complement the existing sewer drainage system. The evaluation of these de-sealing scenarios focused on reducing surface inundation and anticipated damage, serving as a foundational aspect for conducting a cost-benefit analysis and detailed planning. This analysis can contribute to future-oriented urban pluvial flood risk management plans for the city.

How to cite: Khosh Bin Ghomash, S., Apel, H., Schroeter, K., and Steinhausen, M.: Assessing Surface Drainage Efficiency in Urban Pluvial Flood Hazard and Risk Mitigation: A Case Study of Braunschweig City, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3076, https://doi.org/10.5194/egusphere-egu24-3076, 2024.

EGU24-3170 | ECS | Orals | HS7.5

Influences of moisture transport on changes in extreme precipitation in Central Plains Urban Agglomeration, China  

Yufan Chen, Shuyu Zhang, Deliang Chen, and Junguo Liu

In recent decades, the Central Plains Urban Agglomeration of China (CPUA) has faced recurring extreme precipitation events (EPEs), causing severe flood disasters, endangering residents, and inducing significant property losses. This study examines the spatiotemporal patterns of summer EPEs in the CPUA from 1961 to 2022. The Hybrid Single-Particle Lagrangian Integrated Trajectory model was used to trace the water vapor trajectories associated with these events and the atmospheric circulations linked to diverse moisture transports were identified. The findings reveal an overall increase in both the intensity and frequency of summer EPEs, particularly intensifying over urban areas while displaying more frequent yet weaker precipitation in mountainous regions. Moisture contributing to these events originates from sources including Eurasia, the northern and southern Western North Pacific, as well as the Bay of Bengal and South China Sea. Notably, contributions from Eurasia and the Northern Western North Pacific have increased, whereas those from the Bay of Bengal and the South China Sea have decreased. Events fueled by Western North Pacific moisture show intensified impacts on urban areas, driven by anomalous anticyclonic patterns and the formation of the Huang-Huai cyclone, inducing vigorous convective activity over the CPUA. The proliferation of the Western North Pacific Subtropical High facilitates warm air transport, converging with colder air from inland areas, resulting in extreme precipitation.

How to cite: Chen, Y., Zhang, S., Chen, D., and Liu, J.: Influences of moisture transport on changes in extreme precipitation in Central Plains Urban Agglomeration, China , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3170, https://doi.org/10.5194/egusphere-egu24-3170, 2024.

EGU24-3602 | ECS | Posters on site | HS7.5

FLOODGAMA: the new INUNGAMA. Beyond a flood events database for Catalonia 

Montserrat Llasat-Botija, Maria Carmen Llasat, Dimitri Marinelli, Raül Marcos, Carlo Guzzon, and Albert Díaz

Floods represent a complex natural hazard, influenced not only by meteorological factors but also by geophysical aspects such as terrain topography, social factors such as the value of exposed assets, and cultural factors like risk awareness. For this reason, the study of these phenomena requires a holistic approach. This requires the correct organization of the information. In addition, given that the information comes from different sources, the traceability of the data must also be contrasted and preserved in order to guarantee its quality and robustness. Databases make it possible to conserve and document historical information, to analyze it and to support smart flood risk management.

With this objective in mind, in 2000 the GAMA team developed the INUNGAMA flood database, following the example of other natural hazards databases. This communication will present the new version of this database, FLOODGAMA, and the main results of its analysis. FLOODGAMA contains information on 456 flood events that affected Catalonia (NE of Spain), between 1900 and 2020, which have caused 1,253 casualties. The events are classified according to the impacts. It includes linked tables with information on event dates, descriptions, fatalities, economic damages, affected municipalities, recorded rainfall and recorded flow. Other tables contain historical marks, codifications and the geographical information of municipalities, counties, basins and rivers, as well as meteorological stations. Its structure has been simplified and standardized with Python and migrated to PostgreSQL (PostGIS) from an ACCESS format. The new database allows for more general and straightforward analysis, introduces GIS tool compatibility, and simplifies the addition of new data and new data sources. This last point has been one of the key points in this transformation as it will provide the database with the flexibility to respond to the challenges posed by the digital transformation that is currently taking place and as a tool for the improvement of adaptation.

The contribution shows the structure of this flood database and the results obtained after its analysis that allows the characterization of flood events in Catalonia.

This research has been done in the framework of the C3Riskmed project, Grant PID2020-113638RB-C22 funded by MCIN/AEI/10.13039/501100011033 and Flood2Now project, Grant PLEC2022-009403 funded by MCIN/AEI/10.13039/501100011033 and by the European Union Next Generation EU/PRTR.

How to cite: Llasat-Botija, M., Llasat, M. C., Marinelli, D., Marcos, R., Guzzon, C., and Díaz, A.: FLOODGAMA: the new INUNGAMA. Beyond a flood events database for Catalonia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3602, https://doi.org/10.5194/egusphere-egu24-3602, 2024.

EGU24-3951 | ECS | Orals | HS7.5

Multi-day precipitation extremes ranking and their association with atmospheric moisture fluxes over India 

Tomás Gaspar, Ricardo M. Trigo, Alexandre M. Ramos, Akash Singh Raghuvanshi, Ana Russo, Pedro M.M. Soares, Tiago Ferreira, and Ankit Agarwal

The Indian subcontinent is characterized by a pronounced summer monsoon season with substantial rainfall from June to September and a less intense autumn monsoon, albeit both posing major challenges to the densely populated regions through flash floods and landslides. During monsoons, different regions of India are affected by extreme precipitation events with distinct durations and triggered by several mechanisms. Here, considering 10 different regions of India characterized by different climatic regimes, we apply an objective ranking of extreme precipitation events, across various time scales, ranging from 1 to 10 days, making use of a high-resolution daily precipitation dataset covering the entire Indian territory from 1951 to 2022. The results confirm that the method accurately detects and ranks the most extreme precipitation events in each region, providing information on the daily evolution of the magnitude (and spatial extent affected) of high precipitation values in each region. Moreover, results show that top rank events can be associated with different types of storms affecting the four main coastal regions of India. In particular, some top rank events can be critically linked to long duration events (e.g., 10 days), which can be missed in ranks for shorter duration (e.g., 1-3 days) periods, thus stressing the need to employ multi-day precipitation extremes ranking. Finally, an in-depth analysis of the large-scale atmospheric circulation and moisture transport is presented for the top 10-day events affecting four coastal regions of India. Overall, we are confident that our findings are valuable in advancing disaster risk reduction strategies, optimizing water resource management practices, and formulating climate change adaptation strategies specifically tailored for the Indian subcontinent.

 

R.M.T., A.R., S.P. and A.T.M. thank Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) – UIDB/50019/2020 (https://doi.org/10.54499/UIDP/50019/2020) and LA/P/0068/2020 (https://doi.org/10.54499/LA/P/0068/2020). A.R. and R.M.T. thank also FCT (https://doi.org/10.54499/2022.09185.PTDC, http://doi.org/10.54499/JPIOCEANS/0001/2019, https://doi.org/10.54499/DRI/India/0098/2020). A.R. was supported by FCT through https://doi.org/10.54499/2022.01167.CEECIND/CP1722/CT0006.

 

How to cite: Gaspar, T., M. Trigo, R., M. Ramos, A., Singh Raghuvanshi, A., Russo, A., M.M. Soares, P., Ferreira, T., and Agarwal, A.: Multi-day precipitation extremes ranking and their association with atmospheric moisture fluxes over India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3951, https://doi.org/10.5194/egusphere-egu24-3951, 2024.

EGU24-5587 | ECS | Orals | HS7.5

Socio-Economic Vulnerability assessment and validation in Seoul, South Korea  

Chi Vuong Tai, Dongkyun Kim, Soohyun Kim, Yongchan Kim, Hyojeong Choi, and Jeonghun Lee

Vulnerability is regarded as a crucial element in disaster risk reduction, garnering increasing attention from researchers. However, these assessments typically conclude with the spatial representation and analysis of vulnerability index values, with very few attempts made on vulnerability validation. This study has employed Principal Component Analysis (PCA) algorithm for the entire 38 selected socio-economic features, resulting in 9 principal components (or factors) to estimate Socio-Economic Vulnerability Index (SEVI). The results reveal consistent vulnerability levels in over half of the dongs (administrative units), compared with SEVI estimated from a subjective weighting scheme based on expert experience. Meanwhile, the remaining dongs exhibit a change in only one level of vulnerability. SEVI values and ranks from PCA were subsequently internally validated through global uncertainty and sensitivity analyses using Monte Carlo method. The vulnerability scores of all input features were randomly generated based on their fitted probability distribution functions, serving as input parameters for 39,936 Monte Carlo simulations. The median statistic was employed to evaluate the vulnerability uncertainty based on both bias of estimated SEVI values and ranks in comparison with simulated data. The findings from this analysis revealed that medium-low and medium vulnerability levels tend to be underestimated, while medium-high and high levels primarily witness an overestimation tendency. The bias in SEVI ranks was further employed to assess the vulnerability uncertainty. In the sensitivity test, a tornado diagram was created to illustrate the explanation of each feature to the overall SEVI variability. The results indicate that the feature with highest explanation of SEVI variability is the number of families with only children and a mother, accounting for more than 5%. The methodology employed in this study is applicable to areas with limited social and economic data sources. Based on our findings, we suggest that the areas with low bias on SEVI values or ranks are reliable for developing disaster risk mitigation strategies, while other areas require further consideration. Additionally, the results from the sensitivity test provide valuable support for future research when selecting input features for socio-economic vulnerability assessment.

Acknowledgement:

This study was supported by: (1) The National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. NRF-2022R1A4A3032838) (50 % grant); (2) Korea Environment Industry & Technology Institute (KEITI) through R&D Program for Innovative Flood Protection Technologies against Climate Crisis Project, funded by Korea Ministry of Environment (MOE) (RS-2023-00218873) (50 % grant).

How to cite: Vuong Tai, C., Kim, D., Kim, S., Kim, Y., Choi, H., and Lee, J.: Socio-Economic Vulnerability assessment and validation in Seoul, South Korea , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5587, https://doi.org/10.5194/egusphere-egu24-5587, 2024.

EGU24-5774 | Orals | HS7.5

myDewetra-VOLTALARM: a transboundary impact-based early warning system increasing resilience of Volta basin communities against hydrometeorological hazards 

Anna Mapelli, Andrea Libertino, Giulia Ercolani, Mirko D'Andrea, Nicola Testa, Matteo Darienzo, Simone Gabellani, Marco Massabò, Rafatou Fofana, Salifou Dene, Boukary Niampa, Maxime Teblekou, and Ramesh Tripathi and the Voltalarm member states national agencies

The Volta Basin, spanning six countries in West Africa, faces significant challenges from both floods and extreme precipitation. To address these challenges, the myDewetra-VOLTALARM system was developed as a collaborative transboundary early warning system (EWS) through the joint efforts of an international Consortium, composed by the Volta Basin Authority (VBA), the Global Water Partnership for West Africa (GWP-WA) and the World Meteorological Organization (WMO), and national institutions of the six riparian countries.  

myDewetra-VOLTALARM embraces an impact-based forecasting approach, focusing on the potential consequences of severe hydrological events on vulnerable communities. This is achieved through state-of-the-art hydro-meteorological modelling chain generating precipitation and discharge forecast with lead times of up to five days, coupled with impact assessment tools that translate these forecasts into actionable warnings based on real-time risk information for sectors like civil protection, agriculture and livelihoods, protected areas. By focusing on potential impacts,  myDewetra-VOLTALARM empowers stakeholders to make risk-informed decisions and implement timely mitigation actions, thereby reducing vulnerabilities and enhancing community resilience. The strength of myDewetra-VOLTALARM hinges on the collaboration, built-up through the implementation process, among the riparian countries, fostering data exchange and enabling a comprehensive understanding of hydrological dynamics across the entire basin. Harmonized risk assessments lead to consistent warning products and mitigation strategies, while the publication of the results on the open-source  myDewetra-VOLTALARM platform ensures transparency and accessibility for all stakeholders. 

A cornerstone of myDewetra-VOLTALARM's impact is the co-produced flood and heavy rainfall impact bulletin, issued jointly by national and regional authorities twice per week. This bulletin provides critical information, enriching and validating the model results with the expertise and local information/measurements of the national institutions, on which the Volta Basin Authority bases its advisories, tailored to specific locations and sectors. The Flood and Heavy Rainfall Impact Bulletin ensures a consistent flow of information at the basin scale and it integrates in the existing national procedures for early warning and civil protection, allowing all the stakeholders to stay informed and adapt their preparedness measures as the hydrometeorological situation evolves. 

myDewetra-VOLTALARM serves as a model for effective early warning systems in shared river basins. Its impact-based forecasting, transboundary cooperation, and co-produced Flood and Heavy Rainfall Impact Bulletin hold the potential to significantly reduce the impacts of floods and extreme precipitation, contributing to a more resilient and sustainable future for the Volta Basin communities.

How to cite: Mapelli, A., Libertino, A., Ercolani, G., D'Andrea, M., Testa, N., Darienzo, M., Gabellani, S., Massabò, M., Fofana, R., Dene, S., Niampa, B., Teblekou, M., and Tripathi, R. and the Voltalarm member states national agencies: myDewetra-VOLTALARM: a transboundary impact-based early warning system increasing resilience of Volta basin communities against hydrometeorological hazards, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5774, https://doi.org/10.5194/egusphere-egu24-5774, 2024.

EGU24-6088 | ECS | Posters on site | HS7.5

Modelling and Prediction of Unprecedented Heavy Rainfall Event Over North India  

Rohtash Saini and Raju Attada

Widespread and multi-day heavy rainfall events, recorded during 08-09 July 2023 in northwest India, significantly impacted Himachal Pradesh, Punjab, and the Chandigarh region. These events resulted in devastating floods and extensive landslides, causing a substantial loss of lives and properties. Understanding such extreme weather phenomena is imperative for enhancing predictive capabilities and mitigating associated impacts. However, due to the complex topography of the Himalayas and limited observational data, poses challenges for investigating precipitation extremes. Against the background, in this study, we employ the Weather Research and Forecasting (WRF) model to investigate the atmospheric processes that led to unprecedented extreme precipitation. The innermost domain is configured with a horizontal grid spacing of 3 km, successfully reproduces the observed extreme rainfall. To assess the performance of different microphysics schemes in capturing key characteristics associated with heavy rainfall events, sensitivity experiments were conducted with five distinct schemes. Preliminary findings reveal that the Goddard microphysics scheme demonstrates good agreement with observations, closely followed by the Thompson scheme. Statistical analyses, including skill scores, further suggest that the Goddard microphysics scheme skillfully simulates the observed rainfall, displaying robust reflectivity values exceeding 35 dBZ in the core regions. The strong reflectivity indicates substantial hydrometeor concentrations, suggesting potential locations of deep convective activity associated with heavy rainfall. Detailed results of simulating the rainfall extremes over northwest India, along with feasible mechanisms influencing atmospheric conditions during extreme will be comprehensively discussed.

How to cite: Saini, R. and Attada, R.: Modelling and Prediction of Unprecedented Heavy Rainfall Event Over North India , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6088, https://doi.org/10.5194/egusphere-egu24-6088, 2024.

EGU24-6148 | ECS | Posters on site | HS7.5

Functionality assessment of road network combining flood roadworthiness and graph topology 

Ke He, Maria Pregnolato, Neil Carhart, Jeffrey Neal, and Raffaele De Risi

In the realm of critical infrastructure, the road network plays an indispensable role in facilitating daily activities, communication, and economic interactions. However, it remains susceptible to the persistent challenge of flood hazards, leading to both structural and non-structural damages (e.g., physical collapse and service interruption). In normal flood disasters, physical collapse may not occur, but service interruptions often occur. Such disruptions manifest in the form of increased travel distances, prolong the travel times, and, in severe cases, complete travel impossibility. This has resulted in a reduction in transportation efficiency, leading to an increase in the social cost of transportation.

This study presents a novel approach that integrated flood hazard, transportation network topology, and vehicle vulnerability to evaluate the functionality of road network. A severity factor is defined to assess the accessibility of expected links (roads and bridges), considering different vehicle types such as cars and SUVs. Then, this study analyses the overall road network functionality loss under varying flood return periods by evaluating the severity of each network link based on the different types of vehicles. Identification of links with the lowest functionality allows for the assessment of the entire network’s performance using topology-based measures, including the average node degree, average clustering, average shortest path, and reachable areas (isochrones). This research employs the transportation network of Bristol, UK, as a case study to investigate the dynamic relationship between the network status and vehicle typology in the context of flooding events. Findings reveal a discernible correlation, wherein the resilience of the network in influenced by the specific characteristics of different vehicle types. Notably, SUVs emerge as inherently more resistant to flood-related disruptions compared to conventional cars.

The insights presented in this paper hold significant implications for the development of robust mitigation strategies geared towards bolstering the resilience of road networks and optimizing the rerouting of emergency response vehicles in flood-prone areas. By elucidating the interplay between vehicle characteristics, network functionality, and flood impacts, the research provides a foundation for informed decision-making in the formulation and implementation of effective preparedness measures. The outcomes of this study offer a strategic roadmap for authorities and policymakers, enabling them to proactively address the challenges posed by future flood events and enhance the overall adaptability and responsiveness of road networks in emergency situations.

How to cite: He, K., Pregnolato, M., Carhart, N., Neal, J., and De Risi, R.: Functionality assessment of road network combining flood roadworthiness and graph topology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6148, https://doi.org/10.5194/egusphere-egu24-6148, 2024.

EGU24-7026 | ECS | Orals | HS7.5

Characteristics of Disaster-causing Heavy Rainfall in Taipei City and Its Application 

Chi-June Jung, Radiant Rong-Guang Hsiu, Yu-Cheng Kao, Mon-Liang Chiang, Wen-Bin Hung, Jing-Ting Wang, and Ben Jong-Dao Jou

The most challenging weather phenomenon for disaster response in Taipei City is localized short-duration heavy rainfall. The capacity of each administrative district to withstand rainfall intensity varies, leading to incidents of flooding even when the rainfall falls short of the designed protection standard of 78.8 mm/h for drainage systems. To enhance disaster response, the Taipei City Fire Department conducts investigations and reports based on rainfall conditions. By integrating the intelligence and reporting system and raising the dispatching standard from 20 to 40 mm/h, the "Heavy Rainfall Response Process Improvement" project has successfully reduced response operation time and alleviated service burdens, advocating for adopting higher standards.

This study explores the correlation between intense rainfall and disaster occurrences, examining thunderstorm events that caused significant flooding in over three administrative districts. The study compares the earliest reported flooding time in each district with the corresponding rainfall, revealing that several districts experienced flooding with less than 60 mm/h of rainfall at the onset, indicating heightened vulnerability. Additionally, the study delves into the relationship between rainfall patterns and disaster potentials. When it accumulates 40 mm of rainfall within 30 minutes, there is a 63% chance of reaching 60 mm accumulation in the following 10 to 20 minutes. This analysis underscores the potential application of cumulative rainfall within the first 30 minutes for predicting subsequent rainfall trends and issuing disaster warnings.

How to cite: Jung, C.-J., Hsiu, R. R.-G., Kao, Y.-C., Chiang, M.-L., Hung, W.-B., Wang, J.-T., and Jou, B. J.-D.: Characteristics of Disaster-causing Heavy Rainfall in Taipei City and Its Application, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7026, https://doi.org/10.5194/egusphere-egu24-7026, 2024.

EGU24-7347 | Posters on site | HS7.5

Impacts comparison by using different hydraulic models on the 2011 flood in Thailand 

Morgane Terrier and Mathis Joffrain

The 2011 flood event in Thailand was devastating both in terms of lives and economic losses. Following this event, the (re)insurance industry have deeply transformed its underwriting practices and used new modeling tools, both external and internal.

A loss is linked both to hazard and sites characteristics. As an insurer's exposure changes, losses for the same event can differ greatly from past observations. Therefore, hazard maps representing a past event can be used to estimate losses as of today.

Building an internal flood risk model requires to create a large set of spatial grids of flood depth. The water depth spatialisation, based on the water level of identified rivers, is a crucial part of the modeling and called the hydraulic modeling.

This poster will :

(i) the use of two hydraulic models to obtain a flood footprint: The software Super-Fast Inundation of CoastS (SFINCS) (Leijnse et al., 2021), a 2D open-source fast numerical model, and LISFLOOD-FP (Bates, 2004).

(ii) calculate insured losses on a fictive portfolio in Thailand using these two models with the same inputs.

(iii) describe and explain the discrepancies steming from (ii).

How to cite: Terrier, M. and Joffrain, M.: Impacts comparison by using different hydraulic models on the 2011 flood in Thailand, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7347, https://doi.org/10.5194/egusphere-egu24-7347, 2024.

EGU24-7770 | Posters on site | HS7.5

Historical database for multi-hazard zonation and damage trend analysis in a Mediterranean study area (southern Italy) 

Olga Petrucci, Massimo Conforti, Giovanni Cosentini, and Graziella Emanuela Scarcella

The occurrence of extreme hydro-meteorological events is globally on the rise, due to the combined effects of climate change and increasing urban development in vulnerable areas. Each year, landslides, floods, urban flooding, storm surges, snow and thunderstorm events cause casualties, huge damage to urban areas, farmland, and communication infrastructures. This work presents the preliminary results of an historical research aiming to identify the series of geo-hydrological events which affected the municipality of Catanzaro (Calabria, South Italy), having an area of 112.7 km2 and a population density of 746.84 ab./km², throughout the latest two Centuries. The purpose is to implement a GIS-platform using the historical series of past events to realize density maps resulting is a zonation of municipal area which depict the vulnerability of municipal sectors per type of damaging phenomena and type of damaged elements, and their trends throughout the decades. We firstly extracted those events contained in the database named ASICal (Italian acronym of historically flooded areas), a catalogue collecting damaging geo-hydrological events occurred in Calabria in the latest centuries and maintained by CNR-IRPI researchers. Then, to improve and enrich our series, we performed an historical research throughout the documents of the State Archive of Catanzaro. As a total, we gathered data about around 270 events which occurred in the study area between 1830 to 2023, highlighting the strong territorial vulnerability of the selected area. Considering the average number of events per year as a proxy of events impact, we can observe as this value increases during the study period, moving from one event per year (in the period 1900 – 1950) to 3 events per year (in the period 1950 – 2023). To be uploaded in the GIS platform and mapped, the 270 events were split in around 1500 records, according to the kind of damaging phenomena (flood, landslide, urban flooding, storm surges, snow, thunderstorm) and the affected place. 44% of cases were widespread events, while the remaining 56% affected single sites. Urban flooding seems the most frequent damaging phenomena (68% of records), followed by landslides (21%), while the other phenomena show lower frequencies. As far as damaged elements, the most frequently affected were public and private buildings (64%) and road and railway network (26%), while people were affected in a few cases (5%). Data elaboration as multi-hazard maps, also crosschecked to either physical or anthropogenic data can be used to identify hazard-prone areas and to support the multi risk management in terms of monitoring, planning of remedial works, and realization/updating of civil protection plans, as far as in the realization of educational campaigns aiming to raise people awareness.

This work was funded by the Next Generation EU—Italian NRRP, Mission 4, Component 2, Investment 1.5, call for the creation and strengthening of ‘Innovation Ecosystems’, building ‘Territorial R&D Leaders’ (Directorial Decree n. 2021/3277)—project Tech4You—Technologies for climate change adaptation and quality of life improvement, n. ECS0000009. This work reflects only the authors' views and opinions, neither the Ministry for University and Research nor the European Commission can be considered responsible for them.

How to cite: Petrucci, O., Conforti, M., Cosentini, G., and Scarcella, G. E.: Historical database for multi-hazard zonation and damage trend analysis in a Mediterranean study area (southern Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7770, https://doi.org/10.5194/egusphere-egu24-7770, 2024.

EGU24-8205 | ECS | Posters on site | HS7.5

A Multi-Criteria Analysis procedure for the evaluation and classification of flood risk mitigation strategies 

Alice Gallazzi, Daniela Molinari, Francesco Ballio, Marina Credali, Immacolata Tolone, Simona Muratori, and Panagiotis Asaridis

The study aims to provide the Lombardy Region, the primary stakeholder in the project, with a procedure for evaluating and classifying structural flood risk mitigation measures. The primary objective is to assist the regional authority in identifying priority interventions for public funding. A step-by-step procedure has been developed to assess and rank all projects submitted to the Region, selecting priority projects based on technical considerations—evaluating feasibility, effectiveness, and sustainability of the proposed measures—and the preferences of policymakers. The assessment procedure's conceptual structure was tested using case studies, including both feasibility studies and executive projects, to determine the level of technical insights required at each planning phase of public works. The methodology relies on Multiple Criteria Analysis (MCA) techniques, enabling the simultaneous consideration of various, non-directly comparable criteria in a complex decision-making context. These criteria encompass technical features of proposed works, potential territorial constraints, and interferences in the intervention area (feasibility); the effectiveness of measures in reducing flood risk and associated costs; and the environmental and social co-benefits and disbenefits of each intervention (sustainability). Specific indicators, either ad hoc defined for the study or referenced from current regulations and guidelines at national and regional levels, are employed to evaluate the criteria. Stakeholder participation, particularly from the Region, River District Authorities, and Municipalities, is crucial throughout the process, especially in the final phase of aggregating (weighting) all criteria. This aggregation produces an overall performance score for each option, enabling the derivation of a regional ranking of flood risk mitigation strategies. The collaboration between academia and public institutions is highlighted as essential for enhancing the efficiency of disaster risk reduction policies.

How to cite: Gallazzi, A., Molinari, D., Ballio, F., Credali, M., Tolone, I., Muratori, S., and Asaridis, P.: A Multi-Criteria Analysis procedure for the evaluation and classification of flood risk mitigation strategies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8205, https://doi.org/10.5194/egusphere-egu24-8205, 2024.

Since the 1950s, global irrigated area has expanded dramatically, with complex effects on regional climate worldwide. The North China Plain (NCP) is among the most intensively irrigated regions in the world, but the effects of historical irrigation expansion on climate extremes over multi-decadal timescale are largely uncertain. Combining statistical methods with model simulations, we found that NCP experienced a decreasing trend of 0.2–0.25 ℃ decade−1 (p < 0.1) in daily maximum temperature (Tmax) during May-June of 1961–2000 along with irrigation expansion, which is distinct from other regions experiencing strong warming such as most of western China. The cooling effect on Tmax is 0.092 ℃ decade−1 (p < 0.01), relatively lower than that in California’s Central Valley but comparable to the trend in Northwest China and larger than the trend in Tibetan Plateau. The correlation coefficients between irrigation expansion and temperature change from 1960 to 2000 for Tmax and mean air temperature (Tmean) are –0.58 and –0.33 (p < 0.01), respectively, suggesting the ability of irrigation to alleviate regional warming and temperature extremes. Such effect varies over time, continuously strengthening from 1961 to 1980 because of intensive irrigation expansion, but then remaining relatively unchanged or weakening during 1980–2005 with moderate expansion. After 2005, the cooling effect is not detectable, which implies that it is completely canceled out by other forcings such as greenhouse gas warming, compensation of urban area expansion, small irrigation expansion rate and decline in irrigation water use. Despite that, irrigation is still able to reduce the number of extreme heat days after 1980. Compared with other factors, we found that irrigation expansion is the second most important contributor (27%) to the decrease in Tmax during the study period, after aerosol pollution (54%). This work emphasizes the ability of irrigation expansion to adapt agriculture to climate change over the past decades, and highlights the need for sustainable irrigation expansion in the future.

How to cite: Yuan, T., Tai, A. P. K., and Wu, J.: Irrigation expansion in North China Plain has historically decelerated regional warming and mitigated temperature extremes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8291, https://doi.org/10.5194/egusphere-egu24-8291, 2024.

The occurrence probability of rare floods is linked to the right-tail behavior of flood frequency distributions. Specifically, heavy-tailed behavior of flood distributions often signals significant hazards due to the unexpected extremeness of event magnitudes. However, conducting reliable analyses of flood tail heaviness across regions remains challenging due to the varying record lengths of available data.

In this study, instead of relying solely on statistical methods to evaluate flood tail behavior, we adopt a physical-based approach—hydrograph recession analysis—to quantify the nonlinearity of catchment hydrological responses. This method has shown its efficacy in identifying heavy-tailed flood behavior across analyses with different data lengths. Our analysis covers 575 river gauges, spanning drainage areas from 4 to 40,504 km2, across Atlantic-influenced European areas, Northwestern European areas, and the Continental United States. We categorize these regions based on the Köppen climate classification to explore the relationship between physiographic/climatic conditions and heavy-tailed flood behavior, and distinguish regional characteristics using the aridity index and potential evapotranspiration.

Our findings reveal a prevalence of heavy-tailed flood propensity in Atlantic-influenced European areas, prevalent nonheavy-tailed flood propensity in Northwestern European areas, and a mixed distribution with a balanced propensity in the Continental United States. Generally, drier catchments exhibit higher nonlinearity in hydrological responses, facilitating heavy-tailed floods, while catchments in which snow dynamics dominate the flood generation process tend to present linear responses. Excessively dry catchments, however, are less likely to exhibit heavy-tail floods due to insufficient moisture. Moreover, around one-third of catchments display varying tail behavior across seasons, underscoring the potential underestimation of flood tail heaviness in annual analyses. The seasonality of flood tail behavior—where instances of heavy-tailed flood behavior increase from spring to autumn but decrease in winter—is influenced by the seasonal variation of potential evapotranspiration.

Our study contributes to advancing the understanding of the impact of inherent physiographic and climatic features on regional and seasonal patterns of heavy-tailed flood behavior, providing valuable insights into the emergence of a considerable occurrence probability associated with very large magnitudes of rare floods.

How to cite: Wang, H.-J., Merz, R., and Basso, S.: Physiographic and Climatic Controls on Heavy-Tailed Flood Behavior: Insights from Catchment Nonlinear Responses, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8389, https://doi.org/10.5194/egusphere-egu24-8389, 2024.

EGU24-8531 | Orals | HS7.5

Appraising and reducing riverine flood risk: a case study from Central Italy 

Francesco Dottori, Matteo Darienzo, Giacomo Fagugli, Simone Gabellani, Tatiana Ghizzoni, Daria Ottonelli, Flavio Pignone, and Eva Trasforini

On 15 September 2022 a catastrophic flood event hit the Misa river basin in Central Italy. The magnitude of the event (intensity of precipitation, water discharge, debris and sediment transport) and the subsequent impacts were far more severe and extended than previous flood events in the same area, thus calling for a radical change in current practices of flood risk management. In this framework, the present study aims at 1) providing a comprehensive assessment of flood risk for the Misa river basin, and 2) designing appropriate risk reduction measures at river basin scale. We reconstructed the September 2022 event by integrating in-field surveys, hydrological data, hydraulic models, observations of the event (e.g. flood extent maps) and historical data of past flood events, taking into account the incompleteness and uncertainty of both models and observations. Moreover, we modelled exposure and vulnerability of population and economic activities in the area, using detailed surveys of observed impacts to inform the model set-up. The outcomes of these activities allowed to review the risk analysis tools currently available in the Misa river basin, and to design updated risk scenarios for present and future climate conditions. Finally, the risk scenarios have been used to explore different alternatives for flood risk reduction, in agreement with local authorities and stakeholders. We evaluated a range of structural measures (strengthening of dike systems, detention areas, river diversions) and non-structural measures (land-use planning, relocation, flood-proofing measures), considering existing risk management plans and new analyses carried out in this study (e.g. cost effectiveness of measures).

How to cite: Dottori, F., Darienzo, M., Fagugli, G., Gabellani, S., Ghizzoni, T., Ottonelli, D., Pignone, F., and Trasforini, E.: Appraising and reducing riverine flood risk: a case study from Central Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8531, https://doi.org/10.5194/egusphere-egu24-8531, 2024.

EGU24-8564 | Orals | HS7.5

High-Resolution Dynamic Flood Susceptibility Mapping Across the Mediterranean Region 

Hamidreza Mosaffa and Luca Brocca

Effective disaster prevention necessitates the production of high-resolution flood susceptibility maps (FSM) that accurately identify potential flood-prone areas. Conventional FSMs, however, provide static representations that overlook the inherent dynamicity of flood susceptibility, which is influenced by temporal variations, precipitation intensities, and other factors. Additionally, traditional FSMs often lack the high-resolution climate data required for precise risk assessment. To address these limitations, we propose a novel dynamic FSM approach that incorporates temporal variations and high-resolution climate data.

Our approach employs the Random Forest machine learning algorithm, trained on a comprehensive dataset of flooded and non-flooded areas (Global Flood Database v1). The algorithm considers seven critical factors influencing flooding events: elevation, slope, land cover, proximity to rivers, drainage density, soil moisture, and precipitation. This approach enables the generation of high-resolution (1 km) dynamic FSMs for the Mediterranean region, under varying seasonal conditions, precipitation intensities, and post-drought scenarios.

To assess and compare the model's performance, we employed both training and testing datasets, conducting evaluations using various metrics. The study results demonstrate the superior performance of the Random Forest model, establishing its efficacy as a robust tool for mapping dynamic flood susceptibility. The accuracy and reliability of the results obtained through this approach offer crucial insights for mitigating flood-related risks and enhancing disaster management strategies. This study is an integral part of the Open-Earth-Monitor Cyberinfrastructure (OEMC) project. As our next step, we aim to expand the application of our dynamic flood susceptibility mapping methodology to cover the European region.

How to cite: Mosaffa, H. and Brocca, L.: High-Resolution Dynamic Flood Susceptibility Mapping Across the Mediterranean Region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8564, https://doi.org/10.5194/egusphere-egu24-8564, 2024.

Floods impact natural and human systems from multiple dimensions. The vulnerability to flood consequences is intricately linked to the hydrogeomorphic and socio-economic properties of the region. In a long run flood control infrastructure such as embankments evolve with the hydrogeomorphic and socio-economic properties and co produce the new set of vulnerabilities. Assessment of maladaptive contribution of flood control infrastructure is crucial in adaptive decision making and building resilience.The study analyzed flood vulnerability of the population residing inside the embankment area of the Kosi River basin from multidisciplinary parameters. The Kosi River embankment area covers around 890 Sq Km area and is home to nearly 0.8 million people who are facing a trifecta of issues, including regular flooding, scarcity of basic amenities, and loss of livelihood. The basin went through numerous flood-related research based on geomorphology, hydrology, and other physical factors; however, the flood impact assessment of embankments and its role within the socioeconomic dimension still needs to be explored. The present study unpacks flood vulnerability in 283 villages located within the Kosi embankment. Drawing upon thirteen attributes—comprising eight socio-economic and five hydro-geomorphic parameters—the analysis incorporates data from Sentinel-2, IMD, FMIS, the 2011 census report, and other pertinent survey reports. The study utilized analytical hierarchical process (AHP) to obtain relative priority order of parameters. Through the application of GIS analysis, we systematically formulated exhaustive vulnerability maps encapsulating socio-economic, hydrogeomorphic, and composite dimensions based on the weightage assigned to the selected parameters. The analysis highlights that nearly the entire population in the embankment region is susceptible to the effects of flooding, with ∼66% of the region having high and very high flood risk and ∼26% in areas with moderate risk. Furthermore, the outcomes reveal the maladaptive consequences of infrastructure solutions, manifesting as socio-economic disparities and exclusionary effects. The population living inside the embankment region exhibit notably impoverished socio-economic characteristics,including 32 % female literacy, approximately 90 houses constructed by  around 90 percent of houses are Kachha ( mud house), and highly rely on farm labor activities, which is highly lower than the region outside the embankment. Additionally, the outcomes bring to light the maladaptive consequences of infrastructure solutions, manifesting as socio-economic disparities and exclusionary effects. Residents within the embankment area exhibit notably impoverished socio-economic indicators, including a 32% female literacy rate, approximately 90% of houses are Katchha ( made from mud and straw), and economic dependency on agriculture labor activities, which is significantly lower than outside of the embankment. Moreover, the annual flood and longer periods of waterlogging cut off the population from other parts of the state. Lastly, the study discussed the source of vulnerability and adaptation options, which could be useful in developing comprehensive flood adaptation programs, including socioeconomic considerations.

How to cite: Devda, A. and Verma, V.: Assessing Flood Vulnerability and Maladaptive Effects Associated with Embankment-Based Flood Control Infrastructure : Hydrogeomorphic and Socioeconomic Analysis Kosi River Embankment Region, Bihar, India., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8741, https://doi.org/10.5194/egusphere-egu24-8741, 2024.

EGU24-9209 | ECS | Posters on site | HS7.5

Spatial analysis of catastrophic flooding in the metropolitan area of Murcia over the last 100 years 

Ester García Fernández, Juan Francisco Albaladejo-Gómez, Andrina Gincheva, Salvador Gil-Guirado, and Alfredo Pérez-Morales

Floods represent the most diverse, destructive and frequent natural hazard worldwide and are one of the most significant causes of loss of economic and social assets. In recent years, an increase in the quantity and intensity of this phenomenon can be observed. The factors are manifold, but two stand out: increased hazards as a consequence of anthropogenic climate change and increased exposure and vulnerability of the population and its economic assets. One of the most conflictive areas of the planet are the Mediterranean regions, due to the combination of both factors. Among the hot spots, the Southeast of Spain stands out, with a situation aggravated by a semi-arid climate, but with a highly irregular and torrential rainfall distribution.

These factors are particularly problematic in urban areas, making it necessary to precisely locate the areas at risk in order to establish effective adaptation measures. For this reason, this paper compiles historical information on the main flood events from 1900 to the present in the metropolitan area of Murcia, the main urban area in southeast Spain. The information collected comes from newspaper sources. Subsequently, this information has been geolocated and analyzed with Geographic Information Systems. The results reveal that, in general terms, the damage is concentrated mainly in the areas near the Segura River. Additionally, and to a lesser extent, there is a significant concentration in its main tributary, the Guadalentín River. However, it should be noted that during recent flooding episodes, the areas affected are being modified, involving new urbanized areas, far from the main riverbeds and located in flood zones due to the passage of secondary watercourses such as wadis. Finally, it is worth noting that there has been an increase in the number of low-intensity damage points. However, on a positive note, it has been observed that higher intensity damage is decreasing.

How to cite: García Fernández, E., Albaladejo-Gómez, J. F., Gincheva, A., Gil-Guirado, S., and Pérez-Morales, A.: Spatial analysis of catastrophic flooding in the metropolitan area of Murcia over the last 100 years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9209, https://doi.org/10.5194/egusphere-egu24-9209, 2024.

EGU24-9257 | ECS | Orals | HS7.5

Multi-hazard assessment of long- and short-term extreme hydrometeorological events in southeastern South America 

M. Josefina Pierrestegui, Miguel A. Lovino, Gabriela V. Müller, and Omar V. Müller

Extreme hydrometeorological events (EHE) negatively affect ecosystems, human settlements, food production, water resources, and public health worldwide. In southeastern South America (SESA), the frequency and intensity of temperature and precipitation extremes have increased over recent decades. SESA is particularly vulnerable to EHE due to its high population rates and an economy heavily reliant on agricultural activities; therefore, advancing towards a climate-resilient development is a key goal for the region. This study presents a multi-hazard analysis of EHE and their changes over SESA.

Our study assesses the frequency, duration, and intensity of short- and long-term EHE for the 1961-1990 and 1991-2020 periods. ERA5 precipitation, soil moisture, and temperature data at multiple time scales (from daily to monthly) are used, with a spatial resolution of 0.25°×0.25° latitude-longitude grid. Long-term EHE are studied using nonparametric standardized indices—specifically, the Standardized Precipitation Index (SPI) and Standardized Soil Moisture Index (SSI)—at 3- and 18-month timescales to analyze agricultural and hydrological impacts. Short-term EHE are characterized by heavy precipitation, flash droughts, and heat waves events to analyze immediate impacts in urban areas and in agriculture. Individual hazard components are derived by multiplying the frequency, duration, and intensity of the identified events, followed by a rescaling to a 0-1 range using range normalization (with minimum and maximum values). The long-term and short-term EHE hazard indices are formulated by aggregating the rescaled individual hazard components and dividing by the total number of components. Changes in observed EHE hazard components are determined by comparing the EHE hazard indices for the 1991-2020 and 1961-1990 periods.

Our findings underscore significant precipitation excess hazard, mainly concentrated in agriculture-prone areas spanning central-eastern Argentina, Uruguay, and southern Brazil across both 3- and 18-month timescales. In contrast, precipitation deficit hazard predominantly manifests in the western regions of SESA. Regarding short-term EHE, the highest hazard magnitudes are observed in northeastern Argentina, southern Brazil, and southeastern Paraguay. Heat waves occur frequently in the region, with hazardous intensities over the northern part of SESA. Additionally, heavy precipitation events constitute a significant hazard component for urban and rural infrastructure primarily in northeastern Argentina. Flash droughts also affect agriculture-prone areas, particularly with high intensity in southern Brazil, northeastern Argentina, and Uruguay.

Our results reveal that the most significant changes are observed in short-term hazard indices in northeastern SESA. This region, which includes eastern Paraguay, northeastern Argentina, southern Brazil, and Uruguay, has experienced an increase in heat wave hazard, primarily due to a significant rise in the frequency of heat waves. Hazards associated with heavy precipitation and flash drought events have also increased, with a rise in their frequency and duration observed mainly over northeastern Argentina and southern Brazil. In contrast, long-term hazard indices exhibit non-uniform patterns of change. Our findings suggest that weather-related hazards have undergone changes over the last decades. We expect that these findings provide valuable insights to enhance SESA's hydroclimatic risk management systems by identifying areas susceptible to both short- and long-term hazards.

How to cite: Pierrestegui, M. J., Lovino, M. A., Müller, G. V., and Müller, O. V.: Multi-hazard assessment of long- and short-term extreme hydrometeorological events in southeastern South America, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9257, https://doi.org/10.5194/egusphere-egu24-9257, 2024.

EGU24-9313 | ECS | Orals | HS7.5

The Effects of Geographic Risk Complementarity on Reducing Flood Insurance Costs 

Shibo Cui and Jianshi Zhao

Flood insurance is an important non-structural measure for flood risk management. However, a significant protection gap in flood insurance exists in many countries and the high cost of flood insurance is a primary reason. Reducing the flood insurance costs for both policyholders and insurance companies is crucial for the effective implementation of flood insurance. Here, we use portfolio theory to derive fundamental principles of reducing overall insurance cost including premiums and risk reserves through geographic risk complementarity. Furthermore, we propose a reasonable premiums distribution approach among different risk agents to analyze the effect of geographic risk complementarity on individual cost, based on the cooperative game theory. We applied our method in China, which has a large territory but lacks a national flood insurance program. We show there is a low correlation of flood losses across most provinces in China. Compared to the separate insurance in each province, national flood insurance can reduce total premiums by 14.5% and total risk reserves by 61.0%. The regions with highest proportion of premium reduction are the middle and lower Yellow River reaches, which have a lower flood risk correlation with the portfolios of other regions. In conclusion, the geographic complementarity in flood risk has a significant effect on reducing flood insurance cost and the degree of cost reduction depends on the flood risk correlation among different entities. We recommend that China should utilize the geographic risk complementarity to implement a national-level flood insurance program. The method proposed can also provide references for catastrophe insurances around the world.

How to cite: Cui, S. and Zhao, J.: The Effects of Geographic Risk Complementarity on Reducing Flood Insurance Costs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9313, https://doi.org/10.5194/egusphere-egu24-9313, 2024.

EGU24-10245 | ECS | Orals | HS7.5

A time-dependent non-asymptotic statistical analysis of extreme precipitation events 

Matteo Pesce, Eleonora Dallan, Francesco Marra, and Marco Borga

Time-dependent precipitation frequency analyses were often hampered by the availability of relatively short data records, which result in large uncertainty in the estimation of extremes. The recently developed non-asymptotic statistical methods, based on fitting ordinary events rather than extreme events only, represent a potential solution to the problem of data scarcity and are finding wide application in literature under assumptions of stationarity. Recent studies investigated the use of non-asymptotic methods under non-stationary conditions (e.g., Vidrio-Sahagún and He, 2022) and advocated their use over other methods for non-stationary frequency analysis of extreme precipitation. In this study we formalize a non-stationary time-dependent approach for the statistical analysis of multi-duration precipitation extremes using simplified metastatistical extreme value (SMEV) approach. The study focuses on a catchment in the Eastern Italian Alps, where trends in extreme precipitation where reported (Dallan et al., 2022) and which was impacted by the exceptional Vaia event in 2018. We provide an estimation of extreme return levels of precipitation in six stations in the neighborhood of the catchment and compare them with precipitation maxima observed during Vaia storm. The results show that using a non-stationary left-censored Weibull distribution, with both scale and shape parameters linearly dependent on time, allows to properly describe the observed trends of intense precipitation for different durations. Our results suggest that the probability of observing events like Vaia increased over the past decades, leading to the need for updating local adaptation measures.

 

References:

Dallan, E., Borga, M., Zaramella, M., & Marra, F. (2022). Enhanced summer convection explains observed trends in extreme subdaily precipitation in the eastern Italian Alps. Geophysical Research Letters49(5), e2021GL096727.

Vidrio-Sahagún, C. T., & He, J. (2022). Hydrological frequency analysis under nonstationarity using the Metastatistical approach and its simplified version. Advances in Water Resources166, 104244.

How to cite: Pesce, M., Dallan, E., Marra, F., and Borga, M.: A time-dependent non-asymptotic statistical analysis of extreme precipitation events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10245, https://doi.org/10.5194/egusphere-egu24-10245, 2024.

EGU24-10297 | ECS | Orals | HS7.5

Projected amplification of rainfall extremes due to warming-induced reduction of snow fraction: an assessment based on convection-permitting simulations 

Petr Vohnicky, Eleonora Dallan, Francesco Marra, Giorgia Fosser, Matteo Pesce, and Marco Borga

In mountainous regions, temperature determines the state of precipitation (liquid or solid) and in turn significantly affects runoff formation and flood generation. Projected temperature increase due to global warming may therefore affect the rainfall/precipitation ratio during heavy storms, hence intensifying the flood regime. This study aims to assess the projected variations in liquid/solid fraction of precipitation during heavy precipitation events in the upper Adige River, Italy (Eastern Italian Alps). The study utilizes simulations from an ensemble of convection-permitting climate models (CPM), which are suitable to the task given their ability to explicitly represent deep convection and to resolve the mountainous topography. The CPM data provided by the CORDEX-FPS Convection project at 1-hour temporal and remapped to 3 km spatial resolution, cover historical and far-future (2090-2099) time periods under the extreme climate change scenario (RCP8.5). Observational data from the densely instrumented river system are utilized for bias evaluation. Lastly, the Simplified Metastatistical Extreme Value (SMEV) approach, known for the reduced uncertainty compared to conventional approaches, is incorporated for frequency analysis. This method proves particularly useful for analyzing extremes from short time periods, such as those in CPM simulations. The projected changes in both sub-daily mean areal precipitation and liquid rainfall return levels are examined at various spatial scales based on the sub-basins total area. Our preliminary results underscore the significance of leveraging advanced statistical techniques and high-resolution climate models to address emerging challenges in hydrology and climate science. The climate-induced shifts in return period of liquid precipitation identified in this study are expected to have implications for both water resources management and adaptation measures.

How to cite: Vohnicky, P., Dallan, E., Marra, F., Fosser, G., Pesce, M., and Borga, M.: Projected amplification of rainfall extremes due to warming-induced reduction of snow fraction: an assessment based on convection-permitting simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10297, https://doi.org/10.5194/egusphere-egu24-10297, 2024.

EGU24-10877 | ECS | Posters on site | HS7.5

Exploring Diverse Perceptions of Multiple Risks among the Public in Rome 

Mara Lucantonio, Elena Ridolfi, Patrizia Cicini, Fabio Russo, and Francesco Napolitano

Risk is given by the combination of exposure, hazard, and vulnerability, and it is perceived by individuals in different ways. Some people may be unaware of the potential occurrence of a given hazard, while others may misjudge their level of exposure, vulnerability, or both. The knowledge of the population’s risk perception is a fundamental aspect for the analysis of potentially catastrophic phenomena and for the development of prevention policies to intervene and mitigate the expected damage. Questionnaires are widely used in social science research to acquire information about the attitudes, social characteristics, beliefs, and behaviors of participants. This information when combined through a mixed method can provide robust, comprehensive, and quantifiable results, adding a valuable perspective for the development of appropriate hazard mitigation and adaptation strategies. Here we present a case study that involves the analysis of a data set based on a questionnaire submitted to around 300 citizens of the city of Rome (Italy) in spring 2023. The proposed questionnaire investigates specific areas, which are: experience and knowledge of the phenomena, probability of occurrence perceived by the respondent, potential impact, and preparedness to deal with the phenomena.The use of questionnaires to study citizens’ perception of both natural and man-made hazards enables the acquisition of valuable information for authorities dealing with emergency management. The resulting dataset has the potential to improve the communication efficiency between authorities and citizens in risk situations, and provide relevant information for future studies relying on the knowledge of citizens’ risk perception.

How to cite: Lucantonio, M., Ridolfi, E., Cicini, P., Russo, F., and Napolitano, F.: Exploring Diverse Perceptions of Multiple Risks among the Public in Rome, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10877, https://doi.org/10.5194/egusphere-egu24-10877, 2024.

EGU24-10950 | ECS | Posters on site | HS7.5

Temporal and spatial analysis of mortality associated with landslides on São Miguel Island (Portugal) from 1900 to 2020 

Rui Fagundes Silva, Rui Marques, and José Luís Zêzere

The São Miguel Island covers an area of 744.6 km² and has a total population of 133,390, distributed across six municipalities: Ponta Delgada, Ribeira Grande, Vila Franca do Campo, Povoação, Lagoa, and Nordeste. The island features two extinct volcanic systems and three active central volcanoes with calderas connected by two fissure volcanic systems. Two distinct seasons can be identified based on rainfall patterns: from October to March (wet season) and from April to September (dry season). Since the settlement of the island in the mid-15th century, there have been records of landslides, some with significant socio-economic impact. The analysis of the spatial distribution and temporal patterns of mortality associated to landslides was carried out using the NATHA (Natural Hazards in Azores) database for the period 1900–2020. Data collection involved the analysis of more than 55,500 newspaper specimens. A total of 236 landslides events were catalogued on São Miguel Island, which caused 82 fatalities. The municipality of Povoação accounted for 48 fatalities, approximately 59% of the total. Ponta Delgada reported 14 fatalities, Ribeira Grande eight, Vila Franca do Campo seven, Nordeste three, and Lagoa two. On São Miguel Island, an average of 0.7 fatalities per year were recorded, resulting in a landslide mortality rate of 0.35 (calculated as the ratio between deaths and total events). The events with the highest number of fatalities occurred on October 31, 1997 (29 fatalities) and on October 14, 1942 (7 fatalities). The annual mortality rate per decade reveals two distinct periods with higher values: 1930-1949 and 1990-1999. No fatalities were recorded from 1900 to 1929. The landslide mortality rate has a first increase in the 1930s and 1940s (≈0.1 fatalities/10,000 inhabitants). From 1950 to 1989, there was a decrease (≈0.02 fatalities/10,000 inhabitants), with a slight increase in the 1960s. The period from 1990 to 1999 has the highest mortality rate (≈0.26 fatalities/10,000 inhabitants). However, excluding the extreme event of October 31, 1997 from the analysis reveals that the 1990s had a mortality rate in line with the previous four decades (0.02 fatalities/10,000 inhabitants). Along the two first decades of the 21st century, the mortality rate increased again, maintaining a stable trend (≈0.05 fatalities/10,000 inhabitants). The data also indicates that males had a higher frequency of fatalities. The circumstances surrounding the incidents varied, with most fatalities occurring outdoors when individuals were on foot in rural areas. However, it is noteworthy that there were also fatalities inside houses in urban areas, emphasizing the diverse contexts in which these tragic events took place. This information provides valuable insights to temporal patterns and spatial distribution of landslide-induced fatalities on São Miguel Island.

How to cite: Silva, R. F., Marques, R., and Zêzere, J. L.: Temporal and spatial analysis of mortality associated with landslides on São Miguel Island (Portugal) from 1900 to 2020, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10950, https://doi.org/10.5194/egusphere-egu24-10950, 2024.

EGU24-11090 | ECS | Orals | HS7.5

From indices to impacts: Understanding the dynamics of drought impacts through socio-economic clustering 

Rhoda Odongo, Hans De Moel, Marthe Wens, Natalia Limones, Dim Coumou, and Anne Van Loon

Over the past decade, the Horn of Africa (HoA) has been plagued by recurrent drought events that have had devastating impacts on the population. The frequency, duration and severity of these droughts are expected to increase in the wake of global warming, leading to higher losses and damages if the vulnerability of the population is not reduced. Monitoring and early warning systems for droughts are based on various drought hazard indicators. However, assessments of how these indicators are linked to impacts are rare. For adequate drought management, it is essential to understand and characterise the drivers of drought impacts, especially in the HoA, where most studies focus either on meteorological droughts, agricultural droughts or the propagation of droughts through the hydrological cycle, without considering the relationship between hazard and impact. Drought hazard indices alone cannot capture the vulnerability of the system. In this study, we identify meaningful indices for the occurrence of region- and sector-specific impacts. We assess the effectiveness of socio-economic clustering in categorising counties based on common characteristics and their correlation with historical drought impacts (malnutrition, milk production and trekking distances to water sources). Using Random Forest (RF) and Spearman correlation analyses, we examine the link between drought indices (Standardised Precipitation Index, Standardised Precipitation Evapotranspiration Index, Standardised Soil Moisture Index, Standardised Streamflow Index and Vegetation Condition Index) with different accumulation periods and the impact data. We find that clustering regions based on vulnerability proxies significantly improves the hazard-impact relationship, emphasising the importance of considering vulnerability factors in drought risk assessment. Our results indicate an impact-specific relationship that is strongly influenced by the vulnerability of the region. In particular, household and livestock distance to water is most strongly associated with medium- to long-term precipitation-based indices (2-10 months), while milk production can be associated with a variety of indices with different accumulation periods (5-24 months), and malnutrition is correlated with precipitation- and streamflow-based indices (5-24 months). Household and livestock distance to water is well modelled by clusters reflecting low access to improved sanitation and safe water sources, high poverty, aridity and gender disparities. Malnutrition was well modelled by clusters related to aridity, average precipitation, food consumption score, access to water sources, improved sanitation and poverty levels. The type of clustering used in modelling the impact of drought on milk production does not have a major impact on the performance of the models. We then apply this relationship to hindcast drought indices to obtain impact data on individual counties for periods when no impact monitoring was done yet. With that information we estimate the associated risk under specific climatic conditions. By recognising the drivers and vulnerability factors that influence the sensitivity of counties to drought, communities can better prepare and mitigate the impacts of drought.

How to cite: Odongo, R., De Moel, H., Wens, M., Limones, N., Coumou, D., and Van Loon, A.: From indices to impacts: Understanding the dynamics of drought impacts through socio-economic clustering, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11090, https://doi.org/10.5194/egusphere-egu24-11090, 2024.

EGU24-11493 | ECS | Posters on site | HS7.5

Dry spell frequency and duration analysis using different spell definitions 

Pedro Henrique Lima Alencar and Eva Nora Paton

Dry spells, characterized by consecutive days with little to no precipitation, pose significant challenges, particularly in agriculture, and can impact various sectors including health when compounded by high temperatures, increased evaporation rates, or pollution. However, defining the thresholds for what constitutes a significant lack of precipitation or the number of consecutive days to define a notable dry spell remains ambiguous. In this study, we investigate the occurrence of different types of dry spells across Germany using twelve diverse definitions. These definitions encompass not only the conventional criteria of low/no precipitation but also consider associations with other extreme weather conditions occurring simultaneously (such as high temperatures, and potential evapotranspiration) or following the dry spell (like intense precipitation events). Leveraging continuous weather station data spanning the last 50 years, we employ the Mann-Kendall test to analyse seasonal and regional trends in the duration and frequency of these various dry spell events across Germany. Our findings reveal positive trends in both the frequency and duration of dry spells in Germany, notably prominent in the southern regions. These trends are observed in conventional low-precipitation dry spells and compound heat-dry events. Additionally, to facilitate event identification, we have consolidated these diverse dry spell definitions into an R-package called DryER (Dry spell Events in R).

 

How to cite: Lima Alencar, P. H. and Paton, E. N.: Dry spell frequency and duration analysis using different spell definitions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11493, https://doi.org/10.5194/egusphere-egu24-11493, 2024.

EGU24-11733 | ECS | Orals | HS7.5

Exploring vulnerability to flash floods in a water-scarce MENA city: Challenges and possible solutions  

Clara Hohmann, Christina Maus, Ahmad Awad, Dörte Ziegler, Hanna Leberke, Maram Al Naimat, Wafaa Abuhammour, and Katja Brinkmann

Jordan is one of the water scarcest regions worldwide, but regularly hit by severe flash floods caused by heavy rainfall events. Such events will likely intensify in future and increase flash flood damages, especially in rapidly developing urban areas. Therefore, flood vulnerability analysis and assessment are urgently needed to improve urban risk management and to protect the local population. To date, however, such analyses in Jordan, as in many other MENA regions, have been hampered by the lack of spatial and temporal high-resolution climate, economic and social data. Furthermore, conducted hydrological analyses have only considered physical parameters in assessing flash flood risk.

Our aim is to investigate the vulnerability in a data scarce urban region and find solutions to overcome the challenges by combining different disciplinary perspectives with local knowledge. Jordan’s capital, Amman was selected as study region, which is a prime example of a rapidly growing city in the MENA region.

To analyze and assess the vulnerability of people, infrastructure and ecosystem to flash flood events in a watershed of Amman, a mixed-method approach was applied within a transdisciplinary research project called CapTain Rain (Capture and retain heavy rainfall in Jordan). To gain insights into flash flood risks, we explore the vulnerability dimensions exposure and sensitivity from the hydrological, hydraulic and social perspectives, and the adaptive capacity of the local population. For the assessment of each vulnerability dimension, different physical, social and ecological indicators were used. Several indicators, such as damage potential, were adapted to local conditions based on focus group discussions with Jordanian stakeholders.

The vulnerability dimensions exposure, sensitivity and adaptive capacity were assessed for the current situation and several possible scenarios with changing future conditions in climate (intensity of rainfall) and land cover (urbanization trends). As one sensitivity indicator the damage potential was analyzed. The resulting damage potential map shows e.g. the locations of critical infrastructure, and also includes the word heritage sites, which were identified as vulnerable infrastructure of high importance by the Jordanian stakeholders. Regarding future scenarios our first hydrological and hydraulic modelling results show that a moderate climate change of 20% more intense rainfall has a stronger influence compared to land cover changes. Land cover changes with more sealed surfaces have little influence on the runoff caused by the low infiltration capacity of soils in the area according to the available data.

Through interdisciplinary collaboration and local stakeholder engagement, this work demonstrates a noteworthy strategy to addressing flash flood risks in situations where data is limited. The results of the integrated scenario analysis and vulnerability assessment serve as a decision-support tool for urban planning.

How to cite: Hohmann, C., Maus, C., Awad, A., Ziegler, D., Leberke, H., Al Naimat, M., Abuhammour, W., and Brinkmann, K.: Exploring vulnerability to flash floods in a water-scarce MENA city: Challenges and possible solutions , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11733, https://doi.org/10.5194/egusphere-egu24-11733, 2024.

EGU24-14198 | ECS | Orals | HS7.5

Assessing the Influenced Zone of Debris Flow Using Numerical Simulation 

Kai-Lun Wei, Kuo-Wei Liao, Guan-Yu Lin, Poshuan Lin, and Tsungyu Hsieh

Taiwan is located at the boundary between the Philippine Sea Plate and the Eurasian Plate, characterized by steep terrain and high river gradients. Combined with frequent events such as typhoons leading to substantial rainfall, this has resulted in disasters like debris flows. Several available tools such as HEC-RAS two-dimensional hydraulic, SRH-2D, FLO-2D and FLOW-3D are used to analyze the area of flooding and the impact of debris flow in the watershed. The simulation results are compared with historical disaster data to validate the feasibility of model. Furthermore, the results are used to evaluate the suitability of current government-designated evacuation locations and routes.

Among several analysis tools, the debris flow modeling in HEC-RAS two-dimensional hydraulic is considered as the best platform to analyze debris risk. The results show the sections of evacuation routes on the left bank of the downstream area near the estuary pass through the debris flow impact area. However, there is no suitable evacuation facility in the vicinity. Therefore, during warning issuance, residents need to be cautious and evacuate promptly. On the other hand, collaboration with government authorities can be pursued to establish new shelters or activity centers nearby, serving as alternative evacuation sites.

How to cite: Wei, K.-L., Liao, K.-W., Lin, G.-Y., Lin, P., and Hsieh, T.: Assessing the Influenced Zone of Debris Flow Using Numerical Simulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14198, https://doi.org/10.5194/egusphere-egu24-14198, 2024.

EGU24-14698 | Posters on site | HS7.5

Monthly flood frequency regionalization for comprehensive flood damage assessment to crops 

Anna Rita Scorzini, Charlie Dayane Paz Idarraga, and Daniela Molinari

Quantitative flood risk assessments rely on damage models, which relate information on flood hazard and vulnerability of exposed assets to estimate expected losses. Differently from other sectors, crop damage depends not only on typical hazards variables (including water depth, flow velocity, inundation duration, water salinity, yield of sediments and/or contaminants) but also on the month of flood occurrence. Indeed, plant vulnerability changes over the different phenological phases that are strictly related to the seasonality of crop production. Considering the time of occurrence of the flood would imply a shift from the traditional representation of inundation scenarios based on annual probability to monthly-based hazard estimations. When risk assessment is carried out at large spatial scale, a detailed understanding of seasonal flood patterns is then required for the different sub-catchments of the basins, including un-gauged ones. In this study we present a clustering approach to flood frequency regionalization applied to the Po River District in Northern Italy, within the risk assessment process required by the European Floods Directive. The  area is characterized by complex climatic and topographic conditions, highlighting the representativeness of the case study for the implementation of the proposed approach in other geographical contexts. Utilizing observed monthly flow data from over 100 gauging stations, the approach combines both physical and statistical criteria to identify homogeneous regions in terms of flood generation mechanisms and seasonality. The process enables the assignment of distinct monthly flood probabilities to all catchments within the district, thereby supporting a comprehensive flood risk assessment for the agricultural sector.

How to cite: Scorzini, A. R., Paz Idarraga, C. D., and Molinari, D.: Monthly flood frequency regionalization for comprehensive flood damage assessment to crops, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14698, https://doi.org/10.5194/egusphere-egu24-14698, 2024.

The insurance sector plays a critical role in promoting disaster resilience and recovery by providing financial protection, speeding up rebuilding and recovery, and managing the financial impact of natural disasters. To fulfill this role, insurance companies must meet the capital requirements imposed by regulators. For example, the European Solvency II regulatory framework requires insurers to hold enough capital to withstand a natural catastrophe loss with a return period of 1 in 200 years. As the historical loss data are scarce and incomplete, the insurance sector uses stochastic catastrophe models (cat models) to assess the potential cost of rare but devastating events like floods.

A stochastic event set is a crucial element of cat models. It is a collection of possible disasters with their likelihood and severity. One method to generate stochastic flood events is to use numerical models of the atmosphere to generate realistic precipitation fields, and then apply rainfall-runoff models to estimate how much water will flow into rivers and streams from precipitation and snowmelt. By running many simulations with different inputs and parameters, stochastic flood models can provide a range of possible outcomes, including floods with spatial patterns and magnitude missing in historical data.

Output of such simulations are spatio-temporal hazard grids: precipitation grids for pluvial risk and river discharge grids for fluvial risk. These grids are large as the models typically run over large geographies (countries or continents) and simulate 10,000 years or more. This contribution will (i) provide overview of existing methods how to identify flood events in such huge discharge and precipitation datasets (i.e. peak-over threshold method), (ii) show their limitations for identifying flood events, and finally (iii) propose a new methodology designed to address specific needs of reinsurance industry such as the hours-clause condition, which specifies the time period within which losses from a single event must occur in order to be covered.

As many severe floods are composed from several sub-waves (for example 2002 floods in Czech Republic), proper event identification and separation is highly relevant topic as it influences the amount of reinsurance payouts after some types of flood events and thus capital available for rebuilding and recovery. 

How to cite: Kadlec, M.: Identification of flood events in large discharge datasets - reinsurance industry perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14743, https://doi.org/10.5194/egusphere-egu24-14743, 2024.

EGU24-14898 | Posters on site | HS7.5

The diverse impacts of extreme storms in the European South. The case of Storm Daniel (2023) in Greece. 

Michalis Diakakis, Spyridon Mavroulis, Christos Filis, Yiannis Bantekas, Marilia Gogou, Katerina-Nafsika Katsetsiadou, Maria Mavrouli, Vasilis Giannopoulos, Andromachi Sarantopoulou, Panagiotis Nastos, Emmanuel Vassilakis, Aliki Konsolaki, Evelina Kotsi, Sotiris Moraitis, Eleftheria Stamati, Athanasia Bakopoulou, Emmanuel Skourtsos, Panayotis Carydis, and Efthymios Lekkas

On September 4, 2023, Storm Daniel moved inland from the Ionian Sea, intensifying due to the warmth of the post-summer Mediterranean Sea, resulting in intense rainfall and thunderstorms over the Balkans. Central Greece was particularly affected, experiencing the highest daily rainfall totals recorded in the region.

The storm caused widespread devastation, especially in the Thessaly region, with significant impacts including intense erosion, mass movement phenomena triggered by rainfall, damages from strong winds, inundation, agricultural land damage, loss of life and injuries, impacts on residences and businesses, as well as a substantial toll on the environment and cultural sites.

This study focuses on Storm Daniel and its effects in Thessaly, Greece, by creating a database of distinct impact elements based on field surveys and public records. Through this archive, the study explores the range of its impacts, developing a systematic categorization to provide an in-depth understanding of the types and mechanisms of these impacts.

Examining extreme storms through post-flood surveys and emphasizing their impacts can enhance our comprehension of associated risks. This knowledge will facilitate more accurate predictions and strategic planning for such events, contributing to improved emergency management and recovery efforts. Anticipating the impacts becomes crucial, particularly in the context of the projected increase in the frequency of such events due to climate change, thereby strengthening our preparedness.

How to cite: Diakakis, M., Mavroulis, S., Filis, C., Bantekas, Y., Gogou, M., Katsetsiadou, K.-N., Mavrouli, M., Giannopoulos, V., Sarantopoulou, A., Nastos, P., Vassilakis, E., Konsolaki, A., Kotsi, E., Moraitis, S., Stamati, E., Bakopoulou, A., Skourtsos, E., Carydis, P., and Lekkas, E.: The diverse impacts of extreme storms in the European South. The case of Storm Daniel (2023) in Greece., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14898, https://doi.org/10.5194/egusphere-egu24-14898, 2024.

EGU24-15286 | ECS | Posters on site | HS7.5

A 10-Year climatology of hail in France: towards an estimate of the hail hazard 

Maxime Trevisani

According to France Assureur (French insurance unions), 2022 hail damage in France is estimated at more than €6.5 billion, i.e. more than half of all climate-related damage in 2022, or 60% of all hail damage accumulated between 2013 and 2021. This record-breaking year is in line with the growing concern about hail in France among public and private stakeholders. Despite its increasing impact on society the hail hazard in France remains largely unknown or under investigated at the national level, with a single 20x20 km hail risk map produced up in 1998 by F. Vinet using economic data (insurance) and measurements (hailpad). Hail hazard is poorly studied in France due to the great difficulty of observing or modelling hailfall, which are highly localised in time and space. The emergence of social networks since the late 2000s has led to a proliferation of potential hail observers across France. These new data, combined with insurance data, make it possible to study hail at a level of resolution never seen before in France.

The main objectives of our study are therefore to update the geographical assessment of the hail hazard in France, while improving the granularity of the existing geographical hail assessment. To this end we studied the hail hazard in terms of frequency and maximum diameter at the municipal level (average 16 km²), using hail reports (Keraunos, European Sever Weather Database) and insurance data (Generali France, around 5% market share) over the period 2013-2022.

Our study thus provides a resolution 25 times finer than that of Vinet and reveals a southwest - northeast axis dividing France into two parts: the southern part is heavily affected by hail while the northern part is less affected. It also highlights 3 main geographical areas with the highest hail hazard. The Massif Central stands out as the main hail-prone area in France, with a notable maximum in its northern part. The Bordeaux-Paris axis comes second, with a local maximum in the southwest Atlantic coast. In third place comes the Provence-Alpes-Côte d'Azur region, particularly in the Pre-Alps and Pre-Atlantic massifs. There also seems to be a correlation between orography and areas of high hail hazard, particularly noticeable in the Massif Central and Pre-Alps regions, but this assumption needs to be further investigated.

How to cite: Trevisani, M.: A 10-Year climatology of hail in France: towards an estimate of the hail hazard, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15286, https://doi.org/10.5194/egusphere-egu24-15286, 2024.

EGU24-15556 | Orals | HS7.5

Climate Stress Testing for Enhanced Understanding of the Flood Hazard and its Socioeconomic Impacts in Italy 

Francesca Perosa, Alastair Clarke, Punit Bhola, Caroline McMullan, Emma Lewington, and Bernhard Reinhardt

To contribute to a more resilient flood risk management in Italy, we employ the recently published Verisk Inland Flood Model for Italy to conduct climate stress testing. We focus on the sensitivity of modeled losses to precipitation and leverage the meteorological dataset obtained from the Climate Model Intercomparison Project Phase 6 (CMIP6) for identifying projected precipitation trends and analyzing the potential effects of climate change on inland flood losses in the future, exploring different Shared Socioeconomic Pathways (SSPs) and Representative Concentration Pathways (RCPs). The methodology involves analyzing correlations between annual or seasonal precipitation and the corresponding annual loss cost, which is defined as annual loss divided by the total insured value. By exploring these relationships, we seek to enhance our understanding of how precipitation patterns influence the financial implications of flood events in various Italian regions. Additionally, we use the 10,000-year stochastic catalog embedded in the Verisk Inland Flood Model to explore the impact of expected climate change-related changes in annual precipitation for each Italian region, addressing the climate change-based precipitation targets. This enables us to run the fully probabilistic Verisk Inland Flood model and to assess whether anticipated alterations in precipitation levels correspond to expected changes in Annual Average Loss (AAL). This approach allows us to dynamically adapt our flood risk model to varying climate scenarios, providing valuable insights for the (re)insurance industry, as well as academia and government agencies that are seeking to navigate the evolving landscape of flood-related risks.

How to cite: Perosa, F., Clarke, A., Bhola, P., McMullan, C., Lewington, E., and Reinhardt, B.: Climate Stress Testing for Enhanced Understanding of the Flood Hazard and its Socioeconomic Impacts in Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15556, https://doi.org/10.5194/egusphere-egu24-15556, 2024.

EGU24-15848 | Posters on site | HS7.5

The use of radar information for improving the knowledge about landslides and floods events: an application to Calabria region (Italy) 

Vincenzo Totaro, Simona de Sario, Francesco Chiaravalloti, and Olga Petrucci

Floods and landslides are common natural phenomena that threaten society and ecosystems causing significant losses in term of human lives and financial damages. An in-depth investigation about the past occurrences of these events is of paramount importance for providing advances in the knowledge of natural and anthropogenic factors responsible for their generation. Considering rainfall as one of the key drivers for triggering physical mechanisms responsible for the occurrences of floods and landslides, a proper description of its characteristics needs to contemplate the intrinsic spatial and temporal variability. Despite the importance of such elements, rainfall monitoring often relies on sparse rain gauges, which lead to uncertainty in the identification of real rainfall patterns, making difficult to link precipitation records with observed damages. Meteorological radar represents a relevant tool for detecting rainfall spatiotemporal variability and providing ancillary information about the evolution of the events.

Goal of the work is to develop a methodology that aims in reconcile records of landslides and floods events with the rainfall structures obtained by the joint use of data recorded by rain gauge network and radar data. The research has been carried out by moving from a consolidated catalogue of damaging events occurred in correspondence of floods and landslides in Calabria region (Italy) in 2019 and 2020. Rainfall was investigated integrating rain gauge data and maps of Surface Rainfall Intensity with resolution of 1x1 km2.

Exploiting the availability of an accurate spatiotemporal reconstruction of precipitation structures, our investigation allowed to improve the specific knowledge about dynamics responsible of selected floods and landslides events. Preliminary results are supportive of the use of the proposed approach for integrating different sources of information in the assessment of the real dynamics of damaging events and for enhancing the use of their joint scientific content in the framework of risk assessment and mitigation.

How to cite: Totaro, V., de Sario, S., Chiaravalloti, F., and Petrucci, O.: The use of radar information for improving the knowledge about landslides and floods events: an application to Calabria region (Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15848, https://doi.org/10.5194/egusphere-egu24-15848, 2024.

EGU24-17412 | Orals | HS7.5 | Highlight

It could have come worse –  an analysis of spatial counterfactual scenarios for the July 2021 flood in the Ahr Valley, Germany 

Sergiy Vorogushyn, Li Han, Heiko Apel, Viet Dung Nguyen, Björn Guse, Xiaoxiang Guan, Oldrich Rakovec, Husain Najafi, Luis Samaniego, and Bruno Merz

After a flood disaster, the question often arises: “What if the event had gone differently?” For example, what would be the effects of a flood if the path of a pressure system and thus the precipitation field had occurred taken a different trajectory? The analysis of such alternative scenarios of precipitation footprints (“counterfactuals”) is a valuable approach for flood risk management in addition to classical extreme value statistical analyses. It helps to think about and prepare for extremes that have not occurred in this way, but which appear quite plausible.

Here, we analyze the spatial alternative scenarios of the deadly July 2021 flood in the Ahr Valley, Germany. The hydrological model mHM is driven with precipitation fields systematically shifted in space. The resulting runoff is transformed into inundation and flood impact indicators using the high-resolution hydrodynamic model RIM2D.

The results show that even a slight shift of the precipitation field by 15-20 km, which does not seem implausible due to orographic conditions, causes an increase in peak flows at the Altenahr gauge of over 30% and at individual tributaries of up to 160%. Also, significantly larger flood volumes can be expected due to precipitation shifts. This results in markable differences in inundation depths in a number of areas along the Ahr river valley. The presented results should encourage critical thinking about precautionary measures and risk management plans for extreme and unprecedented events.

How to cite: Vorogushyn, S., Han, L., Apel, H., Nguyen, V. D., Guse, B., Guan, X., Rakovec, O., Najafi, H., Samaniego, L., and Merz, B.: It could have come worse –  an analysis of spatial counterfactual scenarios for the July 2021 flood in the Ahr Valley, Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17412, https://doi.org/10.5194/egusphere-egu24-17412, 2024.

EGU24-17516 | Posters on site | HS7.5

Spatial patterns and determinants of severe geomorphological changes due to the extreme flood event in the Ahr valley, western Germany in July 2021 

Fabian Weidt, Rainer Bell, Lothar Schrott, Alexander Brenning, Michael Dietze, Lisa Burghardt, and Joshua Groeßer

The extreme flood event of July 14/15, 2021 caused massive geomorphological changes along the Ahr river in western Germany. The processes include mass movement and bank erosion, channel displacement and widening and deposition of material at the floodplains, all of which contributed to extreme damage. With the aim of gaining a more comprehensive understanding of the factors controlling these processes, spatial patterns of geomorphological changes on a regional scale are analyzed. A differential terrain model (DoD), calculated from digital terrain models (DTM) collected before and after the event using airborne laser scanning (ALS), serves as the data basis. The course of the river is divided into 120 m wide and 100 m long segments. Analyzing the cumulated volumetric loss per segment, which represents the explained variable proxying spatial variability in flood power, is conducted by using a multiple linear regression model. The independent variables considered in this investigation include peak discharge, valley floor width and river curvature. Additionally, a time series model, incorporating ARIMA and GARCH components, is applied to unravel patterns and anomalies along the course of the river while accounting for the autocorrelative and heteroscedastic structure of data. Both the native data and the residuals of all model types are used to examine effects of bridge failure and subsequent outburst waves on volumetric loss. The analysis shows that the strongest geomorphological changes are associated with high peak discharge and a small valley floor width. River segments containing destroyed arch bridges show significantly higher volumetric loss values than segments with destroyed slab bridges, intact bridges or no bridge at all. Spatially limited amplification of volumetric loss to 200 m downstream of destroyed slab bridges suggests a more rapid decrease in outburst wave power for those type of bridges in contrast to arch bridges. These findings provide evidence that there are construction types more appropriate than traditional arch bridges to prevent local augmentation of flood power caused by outburst waves resulting from bridge clogging and failure.

How to cite: Weidt, F., Bell, R., Schrott, L., Brenning, A., Dietze, M., Burghardt, L., and Groeßer, J.: Spatial patterns and determinants of severe geomorphological changes due to the extreme flood event in the Ahr valley, western Germany in July 2021, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17516, https://doi.org/10.5194/egusphere-egu24-17516, 2024.

EGU24-18244 | ECS | Orals | HS7.5

The effects of extreme rainfall trends on compound flood risk: A case study over Greater Boston 

Stergios Emmanouil, Andreas Langousis, Elizabeth Perry, Luke Madaus, Joshua Hacker, and Emmanouil N. Anagnostou

Climate adaptation strategies and vulnerability assessments over coastal areas require proper modeling of the interplay and nonstationary nature of the physical processes involved in compound flooding. As a result of the reported upward trajectories of rainfall intensity over the Contiguous United States, flood risk estimates are also expected to vary. However, given the systematic and random inconsistencies of traditional extreme rainfall estimation approaches and the increased uncertainty surrounding climate model projections, the effects of climate change on the estimation of flood risk from compound hazards remains an open question. In this effort we aim to: (a) combine the observed rainfall intensity trends from the past 40 years (i.e., from 1979 to 2020; see also Emmanouil et al., 2022) across various scales of temporal averaging, with storm surge and antecedent streamflow conditions, to estimate how flood inundation levels evolve, and (b) assess the effects of those trends on flood risk estimation within areas affected by compound hydrological events. In doing so, we use hydrodynamic simulations of reported flood occurrences over the Greater Boston area (MA, United States) for a period of 20 years (i.e., from 2000 to 2019), along with the parametric modeling scheme proposed by Emmanouil et al. (2023). The latter has been shown to properly weight and link the exceedance probabilities of the main flood-driving mechanisms to the return periods of the maximum inundation levels, thus providing a sufficient depiction of the conditions over the studied domain and allowing for estimation beyond the range covered by the available simulations. Assuming that the dependence structure of the driving mechanisms remains time-invariant, our findings aim to enhance the understanding of how flood risk from compound hazards has been affected by extreme rainfall trends induced by the changing climatic conditions and, therefore, support decision-making on the design and protection of critical infrastructure.

References

Emmanouil, S., Langousis, A., Nikolopoulos, E. I., & Anagnostou, E. N. (2022). The Spatiotemporal Evolution of Rainfall Extremes in a Changing Climate: A CONUS‐Wide Assessment Based on Multifractal Scaling Arguments. Earth’s Future, 10(3). https://doi.org/10.1029/2021ef002539

Emmanouil, S., Langousis, A., Perry, E., Madaus, L., Hacker, J., and Emmanouil, E.N. (2023) Decomposing the effects of compound mechanisms on flood risk estimation for urban environments: A case study over Greater Boston, UrbanRain23, 12th International Workshop on Precipitation in Urban Areas, Pontresina, Switzerland, 29 November – 2 December 2023.

How to cite: Emmanouil, S., Langousis, A., Perry, E., Madaus, L., Hacker, J., and Anagnostou, E. N.: The effects of extreme rainfall trends on compound flood risk: A case study over Greater Boston, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18244, https://doi.org/10.5194/egusphere-egu24-18244, 2024.

EGU24-18357 | ECS | Posters on site | HS7.5

Unveiling the complexity of social vulnerability: An analysis of the Social Vulnerability Index in Sweden (SVIS) 

Konstantinos Karagiorgos, Lars Nyberg, Nikos Kavallaris, Jenni Koivisto, Tonje Grahn, Ruth Björkholm, Johanna Gustavsson, and Sven Fuchs

In recent decades, social vulnerability assessments have become a valuable tool for gaining a deeper understanding of the effects of natural hazards on societies. These assessments aim to quantify and map human characteristics that contribute to potential loss, enabling the development of capacities and capabilities to respond to the emerging threats. Assessment methods range from qualitative approaches to semi-quantitative, often spatially explicit, place-based approaches, many of them with empirical background in respective case studies around the world. Despite these efforts, it is still important to carefully examine the potential benefits and limitations of these assessments, particularly those that focus on mapping and place-based approaches, in order to fully understand their value.

The purpose of this study (Karagiorgos et al., 2023) was to systematically evaluate the Social Vulnerability Index in Sweden (SVIS) developed by Haas et al. (2022) using a sensitivity analysis approach. This evaluation focuses on the sensitivity around the impact of changing aggregation scale levels, the influence of different options in constructing the index, the weight/contribution of each factor to social vulnerability and the indicators set. The aim was to determine the influence of input factor variation on model response.

Concerning the influence of scale variations on assessment outcomes, the SVIS algorithm demonstrated robustness when employed across various scales. In contrast, the factor retention method utilized yielded considerable differences in the results. Likewise, the weights' effect exerted a noteworthy influence on the index formation. The consideration of different subsets of variables revealed a high impact in certain scenarios.

The sensitivity analysis conducted in the index construction outlined in this study, recommends that the development of indexes proceed cautiously, accompanied by expert guidance. This approach ensures that the portrayal of social vulnerability remains both reasonable and consistent. Furthermore, the existence of other dimensions of vulnerability, such as physical, economic, and institutional, suggests that the SVIS be integrated with these dimensions. This integration can offer a comprehensive perspective on vulnerability, helping to identify and comprehend the primary pillars for use in Disaster Risk Reduction (DRR). It also contributes to a deeper understanding of the connections between social vulnerability models and the outcomes of disasters.

Haas, J.; Karagiorgos, K.; Pettersson, A.; de Goër de Herve, M.; Gustavsson, J.; Koivisto, J.; Turesson, K. & L. Nyberg (2022): Social sårbarhet för klimatrelaterade hot. Delstudie 2: Generella och hotspecifika index för social sårbarhet i Sverige. Myndigheten för samhällsskydd och beredskap, (MSB) rapport nr 1978, Karlstad.

Karagiorgos, K.; Kavallaris, N.; Björnholm, R.; Koivisto, J. & S. Fuchs (2023): Evaluation of the Social Vulnerability Index (SVIS) in Sweden. Swedish Civil Contingencies Agency (MSB), MSB report nr 2185, Karlstad. 

How to cite: Karagiorgos, K., Nyberg, L., Kavallaris, N., Koivisto, J., Grahn, T., Björkholm, R., Gustavsson, J., and Fuchs, S.: Unveiling the complexity of social vulnerability: An analysis of the Social Vulnerability Index in Sweden (SVIS), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18357, https://doi.org/10.5194/egusphere-egu24-18357, 2024.

EGU24-19140 | ECS | Posters virtual | HS7.5

Sensitivity analysis of agricultural and hydrological droughts to rainfall deficits across India 

Syed Bakhtawar Bilal and Vivek Gupta

Drought is a natural phenomenon characterized by an extended period of insufficient rainfall for a particular area. These deficit in rainfall leads to shortage of water reserves across surface and sub-surface storages. Variations in these shortages arise from diverse factors such as regional climatic variations, geographical features, and land-use patterns. The primary objective of this study is to assess the sensitivity of agricultural and hydrological systems to rainfall deficits across different climatic zones. We aim to quantify the degree of responsiveness of agricultural and hydrological droughts to varying precipitation deficiencies using various statistical and modeling techniques. By examining the diverse responses in different regions, this research seeks to enhance our understanding of precipitation shortages on drought dynamics.

How to cite: Bilal, S. B. and Gupta, V.: Sensitivity analysis of agricultural and hydrological droughts to rainfall deficits across India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19140, https://doi.org/10.5194/egusphere-egu24-19140, 2024.

EGU24-19393 | ECS | Orals | HS7.5

Impact of long-lasting flood water on agricultural productivity: a case study of the May 2023 Emilia Romagna floods 

Margherita Sarcinella, Jeremy S. Pal, and Jaroslav Mysiak

Heavy rainfall events occurred in the Emilia-Romagna region in Northern Italy as a result of two major storms on May 2nd and 17th that led to the overflow of 22 rivers and triggered over 250 landslides. This event claimed 15 lives, forced 10 thousand people to evacuate and caused over 400 road closures. Due to a prior long-lasting winter drought and poor land use management that hampered effective water drainage, floodwaters stagnated for over a month in some areas, exacerbating the crisis. Over 40% of regional agricultural land was flooded leading to irreversible crop damage, in some instances, entire harvest loss. The objective of this study is to build a consistent and replicable methodology to quantify the agricultural damages and economic loss resulting from stagnated floodwater over cropland using the Emilia Romagna floods as a case study. The study emphasises the use of remote sensing data as a tool to achieve accurate impact estimates. Sentinel-1 SAR imagery is used to derive 10-meter resolution flood extent and duration maps at a revisit time of 3 to 6 days. The maps are matched with crop data available for the region from the iColt database and damages are computed as a function of ponded water duration and crop type as well as resistance to oxygen deprivation. The data, comprised of crop type, growing season and sowing date, allow for the characterization of the growth state of each crop at the time of flooding, implicitly providing insights on the probability of plant survival. The use of satellite-derived vegetation indices as markers for post-disaster crop recovery, with a focus on identifying crop-specific recovery rates and patterns is highlighted. This study highlights the need for collaborative efforts with key regional entities and can provide factual-hazard-based agricultural loss estimates to local institutions. These findings can guide targeted adaptation strategies, improve the spatial accuracy of loss assessment, and improve our comprehension of the aftermath of prolonged floods on agricultural output.

How to cite: Sarcinella, M., Pal, J. S., and Mysiak, J.: Impact of long-lasting flood water on agricultural productivity: a case study of the May 2023 Emilia Romagna floods, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19393, https://doi.org/10.5194/egusphere-egu24-19393, 2024.

EGU24-19552 | Posters on site | HS7.5 | Highlight

Unveiling global sub-daily precipitation extremes: Insights and development of the INTENSE Project  

Hayley Fowler, Amy Green, Elizabeth Lewis, David Pritchard, Stephen Blenkinsop, Luis Patino Velasquez, and Anna Whitford

Precipitation extremes result in flooding and droughts, causing substantial damages and loss of life. Understanding the variability of precipitation extremes with climate change is challenging, as we do no fully understand processes causing extreme precipitation under current climate variability. The INTENSE project focuses on understanding of the nature and drivers of global sub-daily precipitation extremes and change on societally relevant timescales. As part of this a Global sub-daily precipitation dataset has been collected, containing hourly rainfall data from approximately 25,000 rain gauges across over 200 territories, from a wide range of sources. This has been quality controlled using a rule-based open-source methodology, combining a number of checks against neighbouring gauges, known biases and errors, and thresholds based on the Expert Team on Climate Change Detection and Indices (ETCCDI) Climate Change Indices.  

A set of global hydroclimatic indices have been produced, characterising key aspects of shorter duration precipitation variability, including intensity, duration and frequency properties. An analysis of the indices, trends and corresponding climatology is carried out, providing information on various sub-daily precipitation characteristics (including extremes) across large parts of the world. These indices are publicly available for as many gauges as possible, alongside a gridded dataset that also incorporates indices calculated for additional restricted-access gauge records. To progress further with this work, updates to the dataset are required, with work ongoing to update resources for 2016 onwards, and attempts to automate the process where open-source datasets are available. Any collaborations, information, suggested contacts and relevant resources for developing the dataset are welcomed. 

How to cite: Fowler, H., Green, A., Lewis, E., Pritchard, D., Blenkinsop, S., Patino Velasquez, L., and Whitford, A.: Unveiling global sub-daily precipitation extremes: Insights and development of the INTENSE Project , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19552, https://doi.org/10.5194/egusphere-egu24-19552, 2024.

Draught is one of the major climate related disaster that Italy has been fighting in the recent years .It is a complex multidimensional phenomenon that is dependent upon on a wide variety of parameters ranging from climatic to socioeconomic ones. In this study we are considering watershed area of lake Bolsena, which is one of the most important water resources in central Italy, to asses in drought vulnerability using Geographical Information System (GIS)  in combination with the Analytic Hierarchy Process (AHP). GIS is used for the spatial analysis of drought for Lake Bolsena watershed area for the year 2022 which was one of the worst draught affected year in the history for the country. Parameters such as Monthly rainfall, Land use/Landcover (LULC), elevation , soil type, Normalized difference vegetation index (NDVI), Normalized Difference turbidity Index (NDTI),Normalized differentiate chlorophyl index(NDCI), Normalized Difference Water Index (NDWI),Storm power index (SPI)  were chosen and considered for the study. AHP is used to calculate weightage factors of each criterion based on the pairwise comparison matrices. The thematic maps of all the parameters were analyzed and Drought Vulnerability Assessment (DVA) map was generated using GIS. The output DVA map will provide valuable information on drought severity in the area and vulnerability related to water availability.

How to cite: Mazumdar, T., Di Francesco, S., Giannone, F., and Santini, M.: Drought vulnerability assessment and mapping using Multi-Criteria decision making (MCDM) and application of Analytic Hierarchy process (AHP) for watershed area of Lake Bolsena of Central Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19949, https://doi.org/10.5194/egusphere-egu24-19949, 2024.

Rich in biodiversity, Tumaco is a focal point for REDD+ projects that aim to combat deforestation and promote sustainable land use. Cacao farming, vital to the local economy, offers an opportunity to reconcile livelihoods and conservation. However, challenges remain in reconciling cacao and forest conservation. This study explores the benefits of sustainable cacao practices, such as agroforestry, for economic development and environmental conservation. It also looks at the challenges farmers face and the implications for the success of REDD+. Perceptions of climate change profoundly influence farmers' perspectives and behaviours in the context of REDD+ initiatives, shaping the sustainability and effectiveness of such efforts. Therefore, fostering a robust understanding of climate change among local farmers is critical to improving the integration of sustainable cacao production into REDD+ frameworks. This research aims to provide insights for policy makers and project implementers to advance both conservation and development goals in the Tumaco region, by addressing potential synergies and trade-offs between cacao production and REDD+ initiatives. The farmers' lack of knowledge is particularly worrying, not only for the fight against climate change, but also because if the cacao farmers of Tumaco do not see the incentives of carbon credits as a sustainable source of income, they will be forced to return to illegal crops, and the socio-environmental development of these communities will be compromised.

How to cite: Quiroga, S., Hernanz, V., Suarez, C., and Aguiño, J. E.: Evaluating the merit of Carbon Credits: Is there a lack of effectiveness in transitioning from direct Payments for Ecosystem Services to REDD+ community-based incentives?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20767, https://doi.org/10.5194/egusphere-egu24-20767, 2024.

EGU24-20944 | ECS | Posters on site | HS7.5

Towards optimizing the operation of controlled flood detention basins 

Mara Ruf and Daniel Straub

Floods are one of the most hazardous natural phenomena worldwide and they are predicted to increase both in intensity and frequency due to climate change. This necessitates comprehensive flood risk mitigation measures that are planned and controlled from a regional as well as a strategic trans-regional perspective.

Controlled flood detention basins can be effective measures for dealing with extreme flood events [1]. By temporally storing water in the detention basin, the discharge in a river is reduced. If the water is removed from the river at the optimal time, this should reduce the peak water level at downstream locations and hence the flood risk.

However, the identification of the optimal operation of flood detention basins is a non-trivial as well as non-deterministic problem. Flood forecast uncertainty, dilatation of the wave along the river channel and the uncertainty in the breaching process turns the polder operation into a stochastic optimization problem with multiple possible optimization targets. Hence, this optimization belongs to the class of sequential decision problems under uncertainty. In this contribution, we utilize a developed dynamic-probabilistic flood risk model [2] to analyze and optimize different control strategies as well as the effect of uncertainties on the optimality of the detention basin operation. We consider the case of a single detention basin as well as that of multiple detention basins that are arranged in series.

 

[1] De Kork, J.-L.; Grossmann, M. (2009): Large-scale assessment of flood risk and the effects of mitigation measures along the Elbe River. Natural Hazards (2010) 52:143-166.

[2] Ruf, M., Hoffmann, A., Straub, D. (2023): Application of a decision sensitivity measure for the cost-benefit analysis of a flood polder at the Bavarian Danube. 14th International Conference on Applications of Statistics and Probability in Civil Engineering (ICASP 14). Dublin, Ireland.

How to cite: Ruf, M. and Straub, D.: Towards optimizing the operation of controlled flood detention basins, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20944, https://doi.org/10.5194/egusphere-egu24-20944, 2024.

EGU24-20988 | ECS | Posters on site | HS7.5

Assessment of future climate risk and vulnerability of local communities in High Mountain Asia 

Anju Vijayan Nair, Rahim Dobariya, Deo Raj Gurung, and Efthymios Nikolopoulos

Higher altitude regions like High Mountain Asia (HMA) are particularly affected by future climate change where the increasing temperature coupled with inconsistent precipitation results in rapid glacier melting during summers and less regeneration of glaciers in winters affecting the livelihoods of billions of people. Access to information on future climate change and related hazards is essential to significantly reduce the impacts on socio-economic systems in HMA. In this study, we focus on identifying the areas in northwest HMA where climate extremes are projected to increase in magnitude and/or frequency. For this, statistically downscaled climate projections (at 5km resolution) derived from a 30-member ensemble of GFDL SPEAR CMIP6 are used to evaluate the projected trends in precipitation and temperature (for years 2015 to 2100) over Afghanistan, Tajikistan, and northern Pakistan under SSP2-4.5 and SSP5-8.5 scenarios. Analysis of changes in precipitation and temperature with respect to the historic climate (1990 to 2014) is done to evaluate the vulnerability to climate hazards including droughts and heatwaves. Analysis of the changes in future climate revealed a rapid increase in the occurrence of droughts and heatwaves towards the end of the century, affecting several communities in the region. Following the methodology developed by the Implementation Platform of the EU Mission on Adaptation to Climate Change (MIP4Adapt), the climate risk and vulnerability of local communities in the region is quantified. The results of this study provide critical information to stakeholders and the local communities to proactively prepare for the anticipated climate risks in the future and to adopt appropriate mitigation measures.

How to cite: Vijayan Nair, A., Dobariya, R., Gurung, D. R., and Nikolopoulos, E.: Assessment of future climate risk and vulnerability of local communities in High Mountain Asia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20988, https://doi.org/10.5194/egusphere-egu24-20988, 2024.

EGU24-21687 | Orals | HS7.5 | Highlight

Understanding the dynamics of multi-sector impacts of hydro-meteorological extremes: a methods overview 

Mariana Madruga de Brito, Jan Sodoge, Alexander Fekete, Michael Hagenlocher, Elco Koks, Christian Kuhlicke, Gabriele Messori, Marleen de Ruiter, Pia-Johanna Schweizer, and Philip J. Ward

Hydro-meteorological extremes, such as droughts and floods, often trigger a series of compound and cascading impacts due to interdependencies between coupled natural and social systems. However, studies typically only consider one impact and disaster event at a time, ignoring causal chains, feedback loops, and conditional dependencies between impacts. Analyses capturing these complex patterns across space and time are thus needed to inform effective adaptation planning. Here, we present a collection of methods that can be used for assessing the dynamics of the multi-sector compound and cascading impacts (CCI) of hydro-meteorological extremes. We discuss existing challenges, good practices, and potential ways forward. Rather than pursuing a single methodological approach, we advocate for methodological pluralism. We see complementary or even convergent roles for analyses based on quantitative (e.g. data-mining, systems modeling) and qualitative methods (e.g. mental models, qualitative storylines). The data-driven and knowledge-driven methods provided here can serve as a useful starting point for understanding the dynamics of both high-frequency CCI and low-likelihood but high-impact CCI.

How to cite: Madruga de Brito, M., Sodoge, J., Fekete, A., Hagenlocher, M., Koks, E., Kuhlicke, C., Messori, G., de Ruiter, M., Schweizer, P.-J., and Ward, P. J.: Understanding the dynamics of multi-sector impacts of hydro-meteorological extremes: a methods overview, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21687, https://doi.org/10.5194/egusphere-egu24-21687, 2024.

EGU24-1624 | ECS | Posters on site | NH3.2

Reconstructing the history of landslides in northern Japan through dendrogeomorphology 

Reona Kawakami, Ching-Ying Tsou, Yukio Ishikawa, Ami Matsumoto, Shigeru Ogita, Kazunori Hayashi, and Daisuke Kuriyama

Dendrogeomorphology serves as a method to determine the timing of historical landslide events. This approach entails scrutinizing the spatial and temporal aspects of landslide occurrences by investigating their impact on tree growth by analyzing variations in tree-ring width, recovery timeline of injured tree stem, as well as the age of tree invasion and establishment in areas affected by landsliding. The method's advantage lies in its capacity to yield a large number of samples where trees are growing. This study encompasses research conducted in both the Sansukezawa landslide in Aomori Prefecture and the Kamitokitozawa landslide in Akita Prefecture, Japan. The examination includes an analysis of the reactions of a combined total of 187 tilted deciduous broadleaved trees and coniferous trees aged between 100 and 102 years in response to landslide events. The findings, revealed by variations in tree-ring width, suggested multiple landslide occurrences at the Sansukezawa landslide between 1901 and 2000. The magnitude of these events varied, encompassing localized activities such as the enlargement of landslide scarps to more extensive landslide movements. In the Kamitokitozawa landslide area, the development of impending landslide events, inferred from the recovery timeline of injured tree stems, included scarp expansion. There were five instances of landslide activities recorded during the period from 1999 to 2019.

How to cite: Kawakami, R., Tsou, C.-Y., Ishikawa, Y., Matsumoto, A., Ogita, S., Hayashi, K., and Kuriyama, D.: Reconstructing the history of landslides in northern Japan through dendrogeomorphology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1624, https://doi.org/10.5194/egusphere-egu24-1624, 2024.

EGU24-2036 | ECS | Orals | NH3.2

Spatio-temporal distribution of extreme rock-ice avalanches in the Cordillera Blanca (Peru) 

Benjamin Lehmann, Swann Zerathe, Ronald Concha, Julien Carcaillet, Pierre G. Valla, Juan C. Torres-Lázaro, W. Harrinso Jara, and Manuel Cosi

The Cordillera Blanca, located in Peru between latitudes 8-10°S, is the most glacierized intertropical mountain range in the world, with peaks over 6,000 meters still carrying numerous glaciers today. Ongoing climate change has resulted in a 41.50% reduction in glacier extent from 1962 to 2020, increasing natural hazards such as icefall, glacial lake overflow flooding, and rock avalanches. These events mainly affect the highest reliefs, but can reach the low elevation valleys, where around 300,000 inhabitants are exposed. Since the 1950s, these hazards have caused tens of thousands of casualties, including two major disasters: rock-ice avalanches from the northern summit of Huascaran (6,757m) traveling over considerable distances and destroying populated areas such as Ranrahirca (1962) and Yungay (1970), resulting in approximately 7,000 casualties in total.

In this context, our objective is to construct a comprehensive "spatio-temporal" inventory of substantial rock-ice avalanches (volume > 106 m3) within the Cordillera Blanca. Our aim is to enhance our understanding of their spatial distribution, temporal frequency, and magnitude while pinpointing potential triggering factors. Our specific focus involves investigating potential correlations between avalanche records and climatic oscillations spanning the past hundred thousand years. The primary area of interest is the Yungay site, situated directly downstream from Huascaran North, where successive debris avalanche (historical and paleo) have accumulated, forming debris cones that extend across several square kilometers. Preliminary field observations have identified numerous large boulders indicative of events surpassing the reported magnitude for historical avalanches and their associated deposits.

Employing a multi-method approach that integrates fieldwork, remote sensing, geochronology, and numerical modeling, we intend to assess rock-avalanche deposits and volumes. A preliminary field mission conducted in August 2023 in Yungay facilitated the mapping and sampling of approximately 30 boulders of pluri-decametric size for surface-exposure dating (in situ 10Be on quartz). Anticipating dating results by early 2024, one of the primary expected outcomes of this study is to achieve a comprehensive reconstruction of the geomorphic response of the high Cordillera Blanca during past climate oscillations. This understanding will contribute to better anticipating the future evolution of natural hazards within the context of ongoing global climate warming, glacial retreat, and accelerated permafrost degradation. Additionally, our objective is to characterize the triggering mechanisms for low-frequency (recurrence time >100 yr) high-magnitude (volume >106 m3) events.

How to cite: Lehmann, B., Zerathe, S., Concha, R., Carcaillet, J., Valla, P. G., Torres-Lázaro, J. C., Jara, W. H., and Cosi, M.: Spatio-temporal distribution of extreme rock-ice avalanches in the Cordillera Blanca (Peru), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2036, https://doi.org/10.5194/egusphere-egu24-2036, 2024.

Accurate characterization of riverbed sediment is crucial for monitoring cross-sectional changes in rivers and modeling water dynamics, especially during large water discharge events. The UAV LiDAR technique, with recent advancements, offers enhanced capabilities for detailed riverbed topography mapping by eliminating surface vegetation. Despite its potential, the adoption of UAV LiDAR for riverbed cross-sectional profiling has faced delays and skepticism in regular practices. In this study, we applied the UAV LiDAR technique to measure the riverbed topography of a relatively wide river in the Ilan plain, northeast Taiwan. Our findings reveal that UAV LiDAR provides significantly more detailed results compared to Airborne LiDAR and surpasses topography measurements obtained through photogrammetry. The accuracy of UAV LiDAR-derived point clouds outperforms photogrammetry, especially when ground control points for the work of photogrammetry are insufficient or poorly distributed. Despite challenges posed by water bodies absorbing LiDAR signals, UAV LiDAR allows the production of complete riverbed topography, offering reliable estimates during dry seasons. Utilizing UAV LiDAR data, we conducted a comprehensive analysis of both cross-sectional and longitudinal riverbed profiles. The longitudinal profiles exhibit wavy frequencies associated with sediment transport processes, opening avenues for further investigation. Additionally, we evaluated Digital Elevation Models (DEMs) of Differencing (DoD) using previously acquired Airborne LiDAR point clouds. The DoD analysis unveiled the substantial magnitude of sediment movement and redistribution following an extreme rainfall event and dam failure, with a height difference exceeding 9m. This analysis, extending along the river's longitudinal profile, serves as a ground-truth field dataset illustrating how extreme rainfall events can trigger large sediment movements, posing potential hazards to the residents near rivers. Our study demonstrates the utility of UAV LiDAR in high-resolution mapping of riverbed sediment topography and provides valuable insights into sediment dynamics under extreme events, contributing to improved monitoring and hazard assessment practices.

How to cite: Chan, Y.-C. and Sun, C.-W.: Riverbed Sediment Topography Mapping Using UAV LiDAR and Insights into Sediment Redistribution Following an Extreme Rainfall Event and Dam Failure, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2327, https://doi.org/10.5194/egusphere-egu24-2327, 2024.

EGU24-2547 | ECS | Posters on site | NH3.2

SAR Monitoring and Finite Element based Stability Modeling for the Zero Landslide in the Darjeeling Himalayas, India 

Suvam Das, Koushik Pandit, Debi Prasanna Kanungo, and Shantanu Sarkar

Landslides are one of the recurring geological hazards in the Indian Himalayas, often leading to loss of life and economy. For the present study, the Zero landslide located in the Darjeeling Himalayas, India has been investigated. This landslide was first activated on July 16, 2014 and its subsequent occurrences have affected a total area of 1×105 sq.m. Field investigations revealed that a local school building, its nearby roads and a few residential buildings are at risk from this landslide. Therefore, monitoring and stability modeling becomes imperative to assess the associated hazard level. For the studied case, the Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) technique was applied to monitor the surface level deformation. For this purpose, Sentinel-1 SLC images captured from January 2022 to November 2023 were collected, and processed using the HyP3 and OpenSARLab platforms. The SBAS-InSAR results revealed maximum subsidence i.e., Line-of-Sight (LOS) velocity (cm/y) of –8.2 and –11.5 for ascending and descending orbit directions, respectively. The presence of transverse tension cracks in the crown and flanks of this landslide supports the SBAS-InSAR results and indicate an active sliding. Furthermore, to assess the slope stability, continuum based two-dimensional finite element modeling (FEM) was carried out. For this, the Shear Strength Reduction (SSR) method was employed in the FE analysis to compute the safety factors for different scenarios. To incorporate material properties within the configured FEM, the Mohr-Coulomb strength criterion was used for soil overburden, and the Generalized Hoek-Brown strength criterion was used for bed-rock profile. The FE analysis revealed a critical Factor of Safety (FoS) value of 1.07 for dry condition and 0.78 for wet condition (Ru). The obtained FoS values suggest that the studied slope section is marginally stable in dry condition; however, instability may be induced during a rainfall event in future. Based on these findings, the design and implementation of landslide risk mitigation measures have been encouraged prior to any major landslide event at the study location.

How to cite: Das, S., Pandit, K., Kanungo, D. P., and Sarkar, S.: SAR Monitoring and Finite Element based Stability Modeling for the Zero Landslide in the Darjeeling Himalayas, India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2547, https://doi.org/10.5194/egusphere-egu24-2547, 2024.

EGU24-2625 | Orals | NH3.2

Rheological behavior of Crushed Rock Flows 

wei hu and Mauri McSaveney

The enduring mystery surrounding the unexpectedly high mobility of expansive geophysical flows has persistently tantalized researchers since Albert Heim's investigation following the catastrophic landslide at Elm, Switzerland. Despite numerous claims of resolution, the mechanism underpinning this remarkable mobility has remained elusive. To delve into the flow dynamics of crushable dense granular material exhibiting high mobility, a series of high-speed rotary shear experiments was conducted using various mineral particles. Our findings revealed a more explicable flow behavior when interpreting shear resistance as viscous rather than purely frictional. Notably, we observed a dramatic decrease in viscosity for crushable materials, stabilizing at a consistently low level, crucial in dictating the remarkable fluidity observed in large-scale geophysical flows like rock avalanches. The flow exhibited two distinct phases, demarcated by a critical point of weakening within accumulated strain for crushable material. The initial phase reflected a simple Newtonian or non-Newtonian-like flow, while the subsequent phase was more intricate, displaying a profound viscosity drop stabilizing at a constant level under substantial strain. This discovery holds significant implications for understanding hypermobile geophysical phenomena, including rock avalanche dynamics, natural faulting, and crater collapse. In particular, we demonstrate that the behavior of rock avalanches is similar to that of complicated fluids with extensive weakening and that the viscosity of this special “liquid” is as low as 500 Pa·s. This finding can also help improve the accuracy and reliability of the numerical simulation of rock avalanches by using the viscous model obtained from the experiments.

How to cite: hu, W. and McSaveney, M.: Rheological behavior of Crushed Rock Flows, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2625, https://doi.org/10.5194/egusphere-egu24-2625, 2024.

EGU24-3883 | Posters on site | NH3.2

Evolution of large-scale landslide at Tuchang creek, Taiwan 

Chia-Ming Lo and Yu-Chen Wu

The D077 study area is located on the right bank of Tuchang Creek in Wufeng Township, Hsinchu County, Taiwan. Two large-scale landslide events occurred in the D077 study area in 2004 and 2013, causing 14 casualties and disrupting traffic, seriously threatening downstream settlements. Until now, the rock slopes in the D077 study area are still in a state of toppling deformation and instability. In view of this, this study used multi-stage remote sensing, terrain analysis, geological survey, geophysical prospecting, drilling, and other data in the analysis of the evolution of large-scale landslides at D077 study area. The results show that the evolution of large-scale landslides (the D077 study area contains three sliding masses: S1, S2, and S3) can be divided into six periods: (1) the period of severe erosion of Tuchang creek and Chingchuan anticline, (2) rock mass decompression and toppling deformation period, (3) development of wedge failure trend of rock slopes at S1 sliding mass, (4) movement of S1 sliding mass and violent erosion of the S2 sliding mass slope toe, (5) toppling deformation develops rapidly at S2 sliding mass, (6) movement of S2 sliding mass and S3 sliding mass toppling deformation continues to develop. In the future, we predict that S2 and S3 will again cause debris sliding and large-scale rock mass sliding. This activity is also expected to threaten the safety of inhabitants and property in downstream of Tuchang creek.

Key words: large-scale landslide, toppling deformation, remote sensing, geological survey, geophysical prospecting, drilling

How to cite: Lo, C.-M. and Wu, Y.-C.: Evolution of large-scale landslide at Tuchang creek, Taiwan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3883, https://doi.org/10.5194/egusphere-egu24-3883, 2024.

Slope monitoring is a commonly way to mitigate the hazard of landslide. The displacement is one of the main parameters being used in slope monitoring, however it is not significant until landslide occurs. According to the literature, energy will accumulate, transfer and dissipate during the development of landslide. So, it is possible to take energy as one of parameters used in slope monitoring if it’s property was understood sufficiently. This study is aimed to find the relationship between energy evolution, displacement of sliding mass and mechanical behavior of rock materials during the development of landslide. In addition, the energy data and displacement data were compared to find the difference between them. Science the mechanical properties of rock mass is affected by scale, four kind of numerical models were created using different scales. Then the energy data and displacement data of specific particles inside each models were recorded during the simulation. The small-scale models include direct shear test model and uniaxial compression test model. The large-scale models include simplified toppling failure model and full-scale landslide model. The results show that in the large-scale models, the variation of energy data is more significant than displacement data. However, in the small-scale models, the variation of displacement data is more significant.

How to cite: Wu, Y. C. and Lo, C. M.: Study on energy and displacement evolution of rock slope during the development of landslide by multi-scale modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4336, https://doi.org/10.5194/egusphere-egu24-4336, 2024.

EGU24-5778 | ECS | Orals | NH3.2

Monitoring 4D landslide displacement using very high resolution Pléiades satellite remote sensing.Case study of the La Valette landslide, French Alps 

Sheng Fu, Steven M. de Jong, Wiebe Nijland, Mathieu Gravey, Philip Kraaijenbrink, and Tjalling de Haas

Slow-moving landslides may pose a substantial threat to communities and infrastructure, with annual creeping distances ranging from a few mm to 100 m. To protect local communities from the landslide motion, landslide displacement monitoring is necessary. However, traditional field investigations are time- and labor-consuming, which may limit the understanding of the landslide evolution and thereby mitigation. Here we propose a 4D landslide displacement framework using optical very high resolution (0.5m) Pléiades satellite constellation imagery. We use our method to monitor the annual movement of the ‘La Valette’ landslide, southern French Alps, between 2012 and 2022. During this period, the landslide moved most actively during the years 2012 and 2013, with average 3D displacement rates of 1.22 and 0.89 cm / day, respectively. Furthermore, we found a decelerating trend in movement rate from 2012 to 2022, which we attribute to warmer weather, decreasing precipitation rates, drier air conditions, and the implementation of a drainage installation. Our study demonstrates the great potential of very-high resolution satellite imagery for near-real time monitoring of 4D landslide displacement, which may benefit research and may contribute to the mitigation of damage and fatalities of slow-moving landslides.

How to cite: Fu, S., de Jong, S. M., Nijland, W., Gravey, M., Kraaijenbrink, P., and de Haas, T.: Monitoring 4D landslide displacement using very high resolution Pléiades satellite remote sensing.Case study of the La Valette landslide, French Alps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5778, https://doi.org/10.5194/egusphere-egu24-5778, 2024.

EGU24-6050 | Posters on site | NH3.2

A case study integrating in-situ monitoring data and numerical simulation method to slope stability assessment of a remote village in southwest Taiwan 

Huai-Houh Hsu, Ting-Wei Chen, Chen-Hsun Hsieh, Chia-Chi Chang, and Tsung-Yi He

The Baoshan Village, a remote village deep in southwest Taiwan, is located near the Tengjhih National Forest Recreation Area. The strata at the site of this study belong to the Miocene Changshan Formation. Its lithology is mainly slate, occasionally intercalated with thin sandstone layers, and the Chaochou Fault passes through it on the east side. Headward erosion and weathering effects made landfall while heavy rainfall and typhoons hit Taiwan. Typhoon Morakot (2009) impacted Taiwan and brought catastrophic damage. Landslides and significant damage happened in the Baoshan Village neighborhood. This study compiles the long-term in-situ monitoring data of the Baoshan Village from 2018 to the present. Monitoring results show that the east side of the Baoshan Elementary School has an apparent slide surface at a depth of 46m. The limit equilibrium method is adopted for the numerical simulation of slope stability by the digital elevation model (DEM), site investigations, and monitoring data. Results show that Baoshan Village contains many potential slide surfaces distributed in different areas, three of which have high potential sliding surfaces. The assessment of slope stability analysis can provide a tremendously meaningful reference for disaster mitigation of Baoshan Village.

How to cite: Hsu, H.-H., Chen, T.-W., Hsieh, C.-H., Chang, C.-C., and He, T.-Y.: A case study integrating in-situ monitoring data and numerical simulation method to slope stability assessment of a remote village in southwest Taiwan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6050, https://doi.org/10.5194/egusphere-egu24-6050, 2024.

Rock slope failures are the catastrophic expression of long-term geomorphological processes occurring in alpine regions. Their impact is often limited to single slopes; however, rock and debris material can occasionally travel very long distances and affect landscape, infrastructures, as well as endanger human life several kilometers away from the source area. Monitoring the evolution of surface activity is recognized as a suitable method to timely identify changes potentially leading to such failure events. Satellite based remote sensing, and in particular Synthetic Aperture Radar (SAR), has shown to be an efficient alternative to in-situ sensors to monitor displacements, especially in situations where the area of interest is large and/or barely accessible. Despite the advent of satellite missions like the ESA Copernicus Sentinel-1, operational monitoring and early warning on single slopes exhibiting surface displacement acceleration potentially leading to failure is still not viable from satellite radars. This is mainly because of the current limitations in spatial and temporal resolution, which prevent obtaining the accuracy and the timeliness often needed for such scenarios.

Here we demonstrate how high spatial and temporal resolution SAR imagery can improve monitoring and characterization of the evolution of a rock slope instability prior and after catastrophic failure. We benefit from ICEYE imagery (X-Band, SPOT mode, 5x5 km scene size, ~50cm resolution) acquired over the Brienz/Brinzauls slope instability in the Swiss Alps between March and August 2023. Among 100 SAR images, we have identified a subset of 30 datasets (ascending orbit, left looking) providing an optimal viewing of the moving slope and imaging the area of interest with revisit times ranging from 3 days to a few hours. We use digital image correlation to measure surface displacements and change detection analyses to map rockfall activity and the slope failure event on June 15th, 2023. We also applied SAR interferometry on data pairs exhibiting suitable perpendicular baselines and computed topographic models at different times and determine failed volumes. The latter have been validated with local terrain models based on photogrammetric drone flights. We discuss the results obtained with ICEYE imagery versus the possibilities with Sentinel-1 data and focus on advantages and specific problems. Our results provide an important step forward towards the use of satellite SAR imagery for operational landslide monitoring scenarios and in the identification and forecasting of catastrophic slope failure events in alpine areas. 

How to cite: Manconi, A., Bühler, Y., Tolpekyn, V., Rankl, M., and Wollersheim, M.: Monitoring impending rock slope failure in alpine scenarios: impact of high spatial and temporal resolution satellite SAR imagery in the investigation of the June 15, 2023, failure event in Brienz/Brinzauls, Swiss Alps  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6091, https://doi.org/10.5194/egusphere-egu24-6091, 2024.

Deep-seated landslide monitoring can require extensive insitu monitoring tools, typically involving equipping boreholes with extensometers, thermometers, and piezometers – proving to be an expensive and labor-intensive task. This work focuses on assessing deep-seated landslide stability by using the physics-based modeling, in partnership with Interferometric Synthetic Aperture Radar (InSAR), as a diagnostic tool for assessing stability in remote regions. We use the case of the insitu monitored El Forn landslide in Canillo, Andorra. We used available Sentinel-1 data to create a velocity map from deformation time series in 2019 and inputted it into a calibrated physics-based predictive model. Using the correlation between the model’s velocity, the insitu observed velocity and the velocity derived from InSAR, we create a normalized real-time risk map of the landslide.

How to cite: Lau, R.: Physics-based uncertainty modeling of deep-seated landslides using InSAR: A case of El Forn (Andorra), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6304, https://doi.org/10.5194/egusphere-egu24-6304, 2024.

EGU24-8090 | ECS | Posters on site | NH3.2

The discovery of a large-scale gravitational collapse in the Gulf of Squillace, Calabria region (central Mediterranean) 

Giacomo Mangano, Silvia Ceramicola, Tiago M. Alves, Massimo Zecchin, Dario Civile, Anna Del Ben, and Salvatore Critelli

The discovery of a large-scale gravitational complex, named in this work Squillace Complex, has been reported in the Gulf of Squillace, Southern Italy, spanning from the continental shelf (c. 1.5 km from the coastline) to the distal sector, covering an area of roughly 600 km2.  The integration between seismic reflection data, borehole and bathymetric information has revealed that this complex exhibits a NE-trending headwall domain made up of sinuous and continuous seafloor scarps linked to a E-W morphological high, via a basal detachment layer between the Messinian evaporites and Tortonian shaleys.

The initiation of the Squillace Complex dates back to the Zanclean (~ 4 Ma) and persisted in movement through the Gelasian (~ 2.1 Ma) at an average rate of 1.9 mm/year. Later in the Calabrian (Middle Pleistocene), the movement underwent a braking and continued sliding to the present day at a reduced rate of 0.1 mm/year. The gravitational collapse of the Squillace Complex aligns temporally with distinct contractional/transpressional events impacting the Calabrian region. These events resulted from basin shortening under a setting of Calabrian Arc stop migration, as well as tectonic uplift affecting the study area since 0.45 million years ago.

In contrast, the diminished movement observed in the Squillace Complex since the Calabrian (Middle Pleistocene) has been inferred as a consequence of conditions of basin stretching in the framework of Ionian plate rollback beneath the Calabrian Arc.

How to cite: Mangano, G., Ceramicola, S., Alves, T. M., Zecchin, M., Civile, D., Del Ben, A., and Critelli, S.: The discovery of a large-scale gravitational collapse in the Gulf of Squillace, Calabria region (central Mediterranean), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8090, https://doi.org/10.5194/egusphere-egu24-8090, 2024.

EGU24-11027 | ECS | Posters on site | NH3.2

Deep-seated gravitational slope deformations of Friuli Venezia Giulia Region (NE Italy) 

Christian Leone, Stefano Devoto, and Luca Zini

Deep-seated Gravitational Slope Deformations (DGSDs) are common phenomena and are observed across various mountain belts worldwide. These phenomena are characterized by the presence of multiple landforms which are important for the recognition of the occurrence of DGSDs. The latter pose significant geological hazard due to their impact on society, economy and environment. They can affect vast areas, potentially endangering large sections of infrastructure, transportation routes, settlements and natural habitats. Furthermore, they cause collateral landslides that can evolve in catastrophic events.

In the past, a comprehensive inventory detailing DGSDs at the scale of the entire European Alps was compiled. This work shows a relatively limited DGSD population in Friuli Venezia Giulia, if compared to other mountain areas such as Central or Western Alps. The final objective of this study is to produce a detailed inventory of DGSDs that affect Alps of Friuli Venezia Giulia Region. Preliminary activities were aimed to desk activities such as analysis of historical documents, reports, aerial images and geomorphological interpretation of LiDAR-derived DTMs. We identified during preliminary activities several DGSDs and tens of possible gravity-induced landforms such as double ridges, ridge top depressions, uphill and downhill-facing scarps, trenches, toe bulges and persistent discontinuities. These gravity-induced features were validated by extensive field surveys carried out in 2023 and the beginning of 2024, also using HR images provided by low-altitude UAV surveys. DGSDs and their landforms were mapped and stored in a GIS.

DGSDs of Friuli Venezia Giulia Alps are favored by: (i) exceptionally high mean annual precipitation (ranging from 1400 to 3400 mm/y), (ii) the presence of several regional faults, (iii) the high-energy relief, (iv) the presence of different rock units (rigid materials and plastic terrains).

How to cite: Leone, C., Devoto, S., and Zini, L.: Deep-seated gravitational slope deformations of Friuli Venezia Giulia Region (NE Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11027, https://doi.org/10.5194/egusphere-egu24-11027, 2024.

EGU24-11468 | Orals | NH3.2

Dynamic simulation of rock-avalanche fragmentation 

Shiva P. Pudasaini, Martin Mergili, Qiwen Lin, and Yufeng Wang

Fragmentation is a common phenomenon in rock avalanches with complex features. The fragmentation intensity and process determines exceptional spreading and mobility of rock-avalanches in the run-out zone. However, studies focusing on the simulation of these phenomena are still limited and no operational dynamic simulation model including the effects of fragmentation has been proposed yet. By enhancing the mechanically controlled landslide deformation model, we propose a novel, unified dynamic simulation method for rock-avalanche fragmentation during propagation. Our formally derived method relies on the continuum mechanics that is applicable to rock masses of any size. The model includes three important aspects: mechanically controlled rock mass deformation, the momentum loss while the rock-mass fiercely impacts the ground, and the energy transfer during fragmentation resulting in the generation of dispersive lateral pressure. We reveal that the dynamic fragmentation, resulting from the overcoming of the tensile strength of the rock mass by the impact on the ground, leads to spreading, thinning, and run-out of the rock avalanche, and to its hypermobility. The elastic strain energy release caused by fragmentation is an important process. Energy conversion between the front and rear parts of the mass caused by the fragmentation process results in the forward movement of the frontal material and the hindered motion of the rear portion of the rock avalanche. Our new model describes this by amplifying the lateral pressure gradient in the opposite direction: enhanced for the frontal particles and reduced for the rear particles after the fragmentation process. The main principle is the switching between the compressional stress and the tensile stress, and therefore from the controlled deformation to substantial spreading of the frontal part of the mass in the flow direction while backward stretching of the rear part of the rock mass. In principle, observations in the laboratory and field events support our simulation results.

How to cite: Pudasaini, S. P., Mergili, M., Lin, Q., and Wang, Y.: Dynamic simulation of rock-avalanche fragmentation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11468, https://doi.org/10.5194/egusphere-egu24-11468, 2024.

Far-traveled landslides greatly increase hazard and risk. Although pervasive liquefaction in debris flows and flow slides can dramatically boost their mobility, the effects of liquefaction on the mobility of coherent landslides is more difficult to forecast. In 2014, the Oso landslide in Washington State, USA failed rapidly and swept across more than 1 km of the adjacent flat alluvial valley, killing 43 people. We mapped over 350 sand boils that emanated from the alluvium under the debris-avalanche hummock deposit. Although transient, these sand boils represent definitive evidence of sub-bottom (basal) liquefaction of the alluvium beneath the overriding slide. The hummocks in the slide mass were not liquefied and they commonly rafted upright vegetation, including coniferous trees, and intact layered glacial sediments across the valley floor. A liquefied base provides little shear resistance, greatly enhancing slide mobility. Our extensive laboratory testing and numerical modeling revealed that several mechanisms may have enhanced basal liquefaction at Oso: rapid undrained loading, shearing of contractive alluvial sediments, and cyclical loading from ground shaking associated with rapid emplacement. 

Here we further investigate the potential for a rapidly moving slide mass to dynamically liquefy underlying alluvial sediments through undrained loading. We use a fully coupled poro-elastic numerical model with parameters determined by laboratory tests of the valley alluvium at the Oso landslide site. Given a landslide speed of 10 m/s, estimated from seismic records of the event, our modeling demonstrates that rapid loading induces transiently elevated pore-fluid pressures nearly equal to the overriding landslide load. These pore-fluid pressures are capable of liquefying the saturated alluvium, reducing its shear strength, and enhancing mobility. Both landslide speed and the hydraulic conductivity of the underlying alluvium strongly modulate the potential for liquefaction. Slower landslide speeds and/or greater alluvial hydraulic conductivity allow simulated pore pressures from loading to dissipate before reaching liquefaction levels. Only specific combinations of these parameters promote basal liquefaction. Such basal liquefaction effects may enhance the mobility of other slides traveling rapidly across saturated alluvium in adjacent valley floors.

How to cite: Reid, M. and Collins, B.: Landslide mobility enhanced by dynamic basal liquefaction of underlying sediments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11528, https://doi.org/10.5194/egusphere-egu24-11528, 2024.

EGU24-12171 | ECS | Orals | NH3.2

Detecting Mass Movements using Fractal-based algorithm 

Quratulain Jaffar, Qi Zhou, and Hui Tang

Rapid climate change is triggering an increase in the frequency and magnitude of catastrophic mass movements on the Earth's surface. Real-time detection of these hazards can improve existing early warning systems and mitigate risks to both humans and society. However, effectively isolating seismic signals from mass movements within continuous seismic recordings remains a significant challenge due to persistent background noise interference. Therefore, It is essential to develop robust detection algorithms for automatic detection. To address this issue, this study proposes the utilization of fractal geometry, which offers a quantitative description of the intricate structures and patterns within a signal across different scales. By using fractal dimensions, this approach aims to differentiate the seismic signal from background noise, because noise typically has a higher fractal dimension than the seismic signal. Two methods, namely, i) variogram estimator and ii) detrended fluctuation analysis, are investigated and applied to the continuous seismic data recorded in the Illgraben catchment in Switzerland to compute the fractal dimension. The findings demonstrate that both methods exhibit power law behaviors in spatio-temporal data, unveiling consistent patterns across scales. The observed variation in fractal dimensions along the seismic traces suggests the reliability of this approach, showcasing reduced susceptibility to false positive detection errors even in the presence of high noise levels. Furthermore, this study also aims to categorize various types of mass movements. This involves defining distinct ranges of fractal dimensions derived from measured data, facilitating the differentiation of various types of mass movements.

How to cite: Jaffar, Q., Zhou, Q., and Tang, H.: Detecting Mass Movements using Fractal-based algorithm, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12171, https://doi.org/10.5194/egusphere-egu24-12171, 2024.

EGU24-13255 | Orals | NH3.2

Unifying endo-exo classification of episodic landslide movements 

Qinghua Lei and Didier Sornette

Landslides, a widespread form of mass wasting, involve complex gravity-driven downslope movements developing over days to years before the final major collapse, which are commonly boosted by external events like precipitations and earthquakes. The reasons behind these episodic movements, characterised by alternating cycles of accelerating and decelerating creeps (marked by intermittent bursts of displacement followed by sustained periods of relaxation dynamics), and how these relate to the final instability, remain poorly understood. Here, we propose the new “endo-exo” classification of landslide bursts, based on the dynamical signatures of pre- and post-burst displacement rates. The underlying concept is based on the existence of cascades of triggered frictional slip and damage responses around a burst. The general theory of multiple cascades of triggered events predicts the existence of four classes of bursts: (i) exogenous non-critical, (ii) exogenous critical, (iii) endogenous non-critical, and (iv) endogenous critical, with respective displacement rates relaxing as power laws around the time tc of the burst respectively as (i) 1/(ttc)1+ϑ for t > tc, (ii) 1/(ttc)1–ϑ for t > tc, (iii) 1/ttc0, and (iv) 1/ttc1–2ϑ, thus depending on a single parameter ϑ. We test these predictions on the precursory and recovery signatures associated with bursts recorded in the long-term monitoring dataset of a rainfall-induced landslide at Preonzo, Switzerland, which exhibited significant episodic movements over many years prior to a catastrophic failure in 2012. Exogenous critical bursts (ii), provoked by external rainfall events, occur abruptly and relax gradually with a power-law exponent around 0.5. In contrast, for endogenous critical bursts (iv) that occur spontaneously under no external triggering, the landslide progressively accelerates prior to the burst and then slowly decelerates afterwards, showing a semi-symmetrical acceleration-deceleration behaviour governed by a small power-law exponent around 0.1. The longer-lived influence of an endogenous critical burst (as reflected by its small relaxation exponent) results from the precursory process that impregnates the system much more than its exogenous counterpart. Additionally, we document a unique exogeneous subcritical burst (i) triggered by the sudden collapse of a downslope sector; it is characterised by an immediate peak followed by a rapid recovery with a power-law exponent around 1.4, consistent with the absence of cascading failures. Endogenous non-critical bursts (iii) are largely driven by fluctuations and thus show no time-dependent recovery. The obtained power laws for these different burst classes are compatible with the existence of a single exponent ϑ ≈ 0.4±0.1, providing strong support for our theory. Our novel conceptual framework points at the existence of a deep quantitative relationship between episodic landslide movements, external triggering events (e.g. rainfall, snowmelt, and seismicity), and internal frictional slip, damage, and healing processes within the landmass.

How to cite: Lei, Q. and Sornette, D.: Unifying endo-exo classification of episodic landslide movements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13255, https://doi.org/10.5194/egusphere-egu24-13255, 2024.

EGU24-14609 | Posters on site | NH3.2

The Parraguirre ice-rock avalanche 1987, semi-arid Andes, Chile -  A holistic revision 

Johannes J. Fürst, David Farías-Barahona, Lucía Scaff, Thomas Bruckner, and Martin Mergili

On November 29 in 1987, a massive ice-rock avalanche detached near Cerro Rubicano in the Dry Andes east of Santiago de Chile. The avalanche developed into a highly destructive debris flow, which reached a run-out distance of more than 50 km resulting in important damage of infrastructure and causing numerous fatalities. In the wake of the event, several studies have shed light on the event history as well as on the geological, volcano-seismic, meteorological and glacio-hydrological pre-conditioning. Although the El-Niño event, that prevailed in 1987, and the presence of glaciers are considered important factors for the development of such a massive debris flow, a holistic analysis of observational evidence, meteorological conditions and debris-flow simulations remains, to this day, absent.

Here, we present new insights obtained from historic aerial photographs and satellite imagery, climate reanalysis, weather stations, hydrographic monitoring and physically-based debris-flow modelling. First, we are able to better constrain the trigger volume and to delineate a first map of the impact area. Second, time records and modelling results affirm the assumed multi-stage character of the event. Third, we postulate that the Parraguirre event can be considered a compound weather event, pre-conditioned by anomalously high temperatures and exceptionally deep snow cover in the days and weeks before the devastating debris flow.

How to cite: Fürst, J. J., Farías-Barahona, D., Scaff, L., Bruckner, T., and Mergili, M.: The Parraguirre ice-rock avalanche 1987, semi-arid Andes, Chile -  A holistic revision, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14609, https://doi.org/10.5194/egusphere-egu24-14609, 2024.

EGU24-15258 | ECS | Orals | NH3.2

Effects of rainfall Intensity-Duration on landslides’ velocity variations: insights from long-term monitoring of case studies in Emilia-Romagna and South Tyrol (Italy) 

Melissa Tondo, Vincenzo Critelli, Marco Mulas, Francesco Lelli, Giuseppe Ciccarese, Giovanni Truffelli, Volkmar Mair, and Alessandro Corsini

What is known, nowadays, is that shallow landslides are mostly influenced by intense short-duration rainfall events while deep-seated ones are mainly affected by long-duration cumulated rainfall. However, the correlation between precipitation and displacement rates, especially for deep-seated landslides, is still poorly investigated on a quantitative basis. In order to understand the mechanisms of acceleration and deceleration of landslides and how they are related to rainfall regimes, long-term, possibly continuous, monitoring of displacement is essential. This contribute aims to present and discuss this issue based on results from about 15 long-term monitored landslides, ranging from earthslides-earthflows to deep-seated rockslides, located in Emilia-Romagna region and South Tyrol. Displacement time series in these case studies have been collected with different in-situ techniques such as principally periodic and continuous GNSS and Robotic Total Stations (RTS), covering periods up to more than ten years. After analysing displacement plots, each identified acceleration event was correlated to rainfall by considering the last significant precipitation event antecedent to the first date of velocity variation, recorded by local meteo stations. Then, Duration (h) and Intensity (mm/h) were retrieved for each event and an Intensity-Duration (ID) plot was built with all data together. It could be observed that the ID-points were distributed along a line with extremely slow deep-seated landslides on one side and rapid earthslides-earthflows on the other, representing the two opposites of the spectrum. Secondly, another aspect that was considered in this framework is the difference between velocity variations of monitored points (such as GNSS benchmarks or RTS prisms) and the velocity of movement propagation along the landslide body. Examples on this topic are presented from Ca’ Lita and Corvara landslides, located in Emilia-Romagna and South Tyrol, respectively. Landslides response to precipitation events is the result of a complex combination of geological, geomorphological, geotechnical, and meteo-climatic factors. In accordance with ID-points distribution, the lower the surface of movement the lower duration and intensity are needed to enhance instability and displacement rates. On the other hand, the interaction with rainfall is not as immediate for deep-seated landslides, making their interpretation more complex. This study presents (i) a summary of all the recorded velocity variations affecting the proposed case studies, and (ii) an interpretation of their behavior in terms of acceleration and precipitation conditions.

How to cite: Tondo, M., Critelli, V., Mulas, M., Lelli, F., Ciccarese, G., Truffelli, G., Mair, V., and Corsini, A.: Effects of rainfall Intensity-Duration on landslides’ velocity variations: insights from long-term monitoring of case studies in Emilia-Romagna and South Tyrol (Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15258, https://doi.org/10.5194/egusphere-egu24-15258, 2024.

EGU24-15459 | ECS | Orals | NH3.2

Multiscale Numerical Modeling of Ultrasound-Induced Granular Avalanches 

Hugo A. Martin, Anne Mangeney, Xiaoping Jia, Bertrand Maury, Aline Lefebvre-Lepot, Yvon Maday, and Paul Dérand

Understanding the mechanisms of seismic-wave-induced triggering of landslides and earthquakes at micro-strain amplitudes is crucial for quantifying seismic hazards. Granular materials, as an out-of-equilibrium and metastable model system, offer insights into landslides and fault dynamics within the unjamming transition framework from solid to liquid states. Recent experiments suggest that ultrasound-induced granular avalanches result from reduced interparticle friction via shear acoustic lubrication. However, investigating crack growth or slip at the grain contact scale in optically opaque granular media remains challenging.

We present a new multiscale numerical modeling of 2D dense granular flows triggered by basal acoustic vibrations of an inclined plane. We introduce a time-scale separation method, addressing the characteristic scales of grain motion on one hand and the propagation of acoustic vibrations on the other. Our approach results from the coupling between the Convex Optimization Contact Dynamics model (COCD) and the computation of vibration modes.

Numerical simulations of ultrasonic vibrations in the millisecond range and flow onset in the second range reveal a correlation between local rearrangements at the grain scale and continuous flows at the macroscopic scale. Ultrasounds primarily propagate through strong-force chains, while a decrease in interparticle friction occurs in weak contact forces perpendicular to these chains. This friction reduction initiates local rearrangements leading to continuous flows through a percolation process with a delay dependent on proximity to failure. Ultrasound-induced flow, compared to gravity-driven flow, appears more spatially uniform, suggesting the role of effective temperature induced by ultrasonic vibration. The simulations align well with experimental observations of granular flows triggered by ultrasound below avalanche angles, supporting the validity of our numerical method.

How to cite: Martin, H. A., Mangeney, A., Jia, X., Maury, B., Lefebvre-Lepot, A., Maday, Y., and Dérand, P.: Multiscale Numerical Modeling of Ultrasound-Induced Granular Avalanches, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15459, https://doi.org/10.5194/egusphere-egu24-15459, 2024.

The Chamoli disaster of 2021 in the Rishiganga valley, triggered by a massive ice-rock avalanche, displayed a characteristic example of the complex dynamic in the glacier and fluvial systems under a warming climate. Here, we present cutting-edge UAV-LiDAR technology to examine the post-disaster morphological changes in the headwater river systems of Rishiganga, specifically focusing on river incision and channel morphological changes. Employing multi-period digital elevation models, we present the region's substantial increases in river incision and channel widening. A considerable increase in river width was also recorded following the event. Our research concludes that landslides act as a significant control of channel morphology in the Himalayan terrain. By unravelling the complex dynamics of river morphology caused by extreme events, this study contributes significantly to the literature in the context of bedrock river incision and landscape evolution.

How to cite: Kaushal, S. and Pulpadan, Y. A.: Assessing river morphological changes induced by large ice-rock avalanches: The 2021 Chamoli disaster region using UAV-LIDAR data., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16450, https://doi.org/10.5194/egusphere-egu24-16450, 2024.

EGU24-18109 | ECS | Posters on site | NH3.2

Paleo-landslides in the southern France (Larzac plateau) 

Kévin Elkharrat, Catherine Homberg, Sara Lafuerza, Nicolas Loget, Muriel Gasc-Barbier, and Stephanie Gautier

The Larzac carbonate plateau (France) is subject to numerous slope instabilities on its edges, ranging from toppling to landslides. Due to their extremely slow slip rates (3mm/year), these last large rotational instabilities remain poorly understood, particularly in terms of characterisation and dynamics. Our study focuses on several deep paleo-landslides of this type, located in two valleys: the Lergue and the Laurounet. These landslides evolved in sedimentary rocks including the highly fractured Jurassic carbonates overlying the Triassic sandstones and the thick Triassic clays. This work aims to study the initial phase mechanisms. In a climate change context, with extreme precipitations as in southern France (“cevenol events”), understanding paleo-landslide mechanisms has an added value in the comprehension of the future slope stability in similar geological contexts.

We used a multi-method approach to characterize the investigated landslides. Remote sensing and field surveys allowed mapping of the landslides, identification of geomorphological features, main and secondary scarps, and their associated slide blocks. Rock mass fracturing was characterized at localities in and away from the landslides. Mechanical characterization was obtained through the Rock Mass Rating (RMR)/Geological Strength Index (GSI) and laboratory tests. Finally, terrestrial cosmogenic nuclides (36Cl for carbonate surfaces) were used to determine the exposure age of the landslide scarps.

The investigated million-cubic-meter landslides show upslope and secondary circular scarps with counter-slope slide blocks, signifying rotation. However, at deeper levels, the failure surface flattens within the evaporite-rich clays. Dating two paleo-landslides places their occurrence between 10 and 18 kyrs, suggesting the Late Pleistocene/Holocene transition. A directional correlation is evidenced between the dense NNW-SSE joint network that cut the carbonates and N-S faults with the landslide scarps. The study suggests that landslides exhibit a rotational-translational mechanism, influenced by lithological differences between fractured carbonate units and weak underlying clays. This reaffirms the significance of clays in landslide failure, with evaporite levels playing a role in deep rupture surface branching in certain cases. Furthermore, a major structural control is evidenced, with the faults serving for initiation or as lateral ramps of the landslides depending on their orientation relative to the slope. Dating results suggest that increasing precipitation could have led to slope failures.

These geological constraints were employed to test scenarios for the initiation of the rotational-translational landslides of the Larzac carbonate plateau using the distinct elements method 3DEC. Field data supplied geometry, while the mechanical parameters of the multi-layer rock mass were estimated based on the RMR and GSI data. The three families of discontinuities, layering planes, and the sub-vertical NNW-SSE and WSW-ENE joints were also included, as well as the in-situ pore pressure. The stability analysis revealed the significant impact of joints/faults and lithology contrast on the stability and geometry of the failure surface. This study illustrates how landslides can be related to a combination of predisposing parameters such as structural inheritance and variation of properties in the heterogeneous rock mass that control their modes of failure and geometries.

How to cite: Elkharrat, K., Homberg, C., Lafuerza, S., Loget, N., Gasc-Barbier, M., and Gautier, S.: Paleo-landslides in the southern France (Larzac plateau), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18109, https://doi.org/10.5194/egusphere-egu24-18109, 2024.

EGU24-18344 | ECS | Posters virtual | NH3.2

Locating Sediment Evacuation Zones – A Prefatory Action for Early Warning System Development in Mountainous landscapes 

Arkaprabha Sarkar, Vimal Singh, and Sukumar Parida

The past decade has seen an alarming rise in the number of extreme events, most of which are high magnitude hydrological events triggered by focused precipitation, glacial lake outburst or both. During such event large amount of debris is mobilized and get deposited in downstream reaches. Studies have quantified the volumes of debris exported by the events and have shown them to possess potential for future hazard (e.g., Hooke, 2019; Sarkar and Singh, 2022; Westoby et al., 2023). However, a pressing question that remains unaddressed is regarding the identification of storage sites of these sediments prior to the event.

We have employed the concept of index of connectivity (IC) to locate sediment stored in the landscape. We have altered the relationships of the upslope and downslope components of the basic framework of index of connectivity (Borselli et al., 2008), and normalized the values to obtain a dimensionless storage potential index (SPI) that indicates the proneness of a point to arrest sediment flux and disrupt the routing process. Using the SPI and normalized IC, we have formulated a Sediment Evacuation Susceptibility Index (ESIS), the values of which ranges between -1 to 1; lower ESIS values indicate stable zones with higher thresholds of evacuation, and vice versa.

The model has been tested in a small catchment (~93 km2) known as Pranmati catchment in NW Himalayas, India. Our results show that significant volume of sediment gets arrested along the margins of land cover units that have contrasting impedance to sediment transportation. Sediment flux also gets arrested in isolated pockets (e.g., grassland patches) within forested land. Croplands tend arrest and store sediment due to intense anthropogenic modification of hillslopes. Landslide talus deposits are a potential sediment storage unit. Mid-slope regions of hillslope transects tend to have high storage potential. These sites get connected during extreme hydrological conditions and release the stored sediments. Landslides debris deposits are found to be highly stable. However, parts of the hillslope in the vicinity of the stream network have a very high susceptibility to evacuation. The results have been validated in field with reference to two major local high magnitude flash flood events. The evacuation susceptibility assessment can be the first step for risk identification, development of an early warning system for flood hazards and disaster mitigation.

References

Borselli, L., Cassi, P., & Torri, D. (2008). Prolegomena to sediment and flow connectivity in the landscape: A GIS and field numerical assessment. Catena, 75(3), 268-277.

Hooke, J. M. (2019). Extreme sediment fluxes in a dryland flash flood. Scientific Reports, 9(1), 1686.

Sarkar, A., & Singh, V. (2022). Characterisation and Assessment of a Flash Flood in the Himalaya: Understanding the Significance of High Magnitude Events in Sediment Mobilisation. Journal of the Geological Society of India, 98(5), 678-686.

Westoby, M. J., Dunning, S. A., Carrivick, J. L., Coulthard, T. J., Sain, K., Kumar, A., ... & Shugar, D. H. (2023). Rapid fluvial remobilization of sediments deposited by the 2021 Chamoli disaster, Indian Himalaya. Geology, 51(10), 924-928.ter, Indian Himalaya. Geology, 51(10), 924-928.

How to cite: Sarkar, A., Singh, V., and Parida, S.: Locating Sediment Evacuation Zones – A Prefatory Action for Early Warning System Development in Mountainous landscapes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18344, https://doi.org/10.5194/egusphere-egu24-18344, 2024.

EGU24-20856 | ECS | Posters virtual | NH3.2

“Identification and Characterization of Paleoalluvial Events in the  Ranrahírca Hydrographic Unit, Cordillera Blanca, Perú” 

W. Harrinson Jara Infantes, Manuel Cosi Cosi, Juan C. Torres, Benjamin Lehmann, Swann Zerathe, Hilbert Villafane, Enver Melgarejo, Adriana Caballero, Sara Cachay, and Leila Mamani

Abstracts

The Cordillera Blanca, located in Peru, is a mountain range with peaks exceeding 6000 meters, preserving tropical glaciers on its surface. Currently, due to global climate change resulting from both natural and anthropogenic causes, glaciers are rapidly losing surface area and volume. Over a period of 58 years, between 1962 and 2020, the Cordillera Blanca (CB) has lost 301.4 km2 of glacier surface, equivalent to 41.50% of the total area. This has led to an increased occurrence of ice and rock avalanches, triggering violent overflow events of glacial lakes and alluvial processes. In this context, the Hydrographic Unit (HU) Ranrahírca has recorded the occurrence of two extreme avalanche events originating from the North Peak of Nevado Huascarán, corresponding to the 1962 event in Ranrahírca and the 1970 event in Yungay.

The objective is to identify, differentiate, categorize, and correlate unconsolidated deposits with different historical alluvial events (Paleoalluvions) of significant magnitude that occurred on the north peak of Nevado Huascarán, Cordillera Blanca. This involves a detailed grain size analysis of soils, with emphasis on lithology, dimensions, shape, and degree of weathering of the clasts in their composition, as well as their fine material content, aiding in temporally situating the origin event. The primary study area is the Yungay district, located at the lower part of Nevado Huascarán, where Quaternary material from various paleoalluvions has accumulated in a fan-shaped pattern in the lower part of the Ranrahírca HU. This area extends for several kilometers, currently encompassing the urban areas of Yungay and Ranrahírca.

To achieve this, fieldwork was conducted in August 2023 in the Yungay and Ranrahírca areas. Seven (07) chronostratigraphic columns were surveyed, and thirteen (13) soil samples were collected from different cut sections of slopes. These efforts have allowed the differentiation of various paleoalluvionic events and, in some cases, evidence the transition between them.

Keywords: Cordillera Blanca, rock-ice paleoavalanche, grain size analysis, chronostratigraphic column.

How to cite: Jara Infantes, W. H., Cosi, M. C., Torres, J. C., Lehmann, B., Zerathe, S., Villafane, H., Melgarejo, E., Caballero, A., Cachay, S., and Mamani, L.: “Identification and Characterization of Paleoalluvial Events in the  Ranrahírca Hydrographic Unit, Cordillera Blanca, Perú”, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20856, https://doi.org/10.5194/egusphere-egu24-20856, 2024.

EGU24-703 | ECS | Orals | NH3.5 | Highlight

Integrated Monitoring and Multi-Hazard Early Warning System for Himalayan Region: Insights from the Chamoli Disaster of 2021 

Anil Tiwari, Kalachand Sain, and Amit Kumar

The material/rock failure is not a sudden progression but is preceded by multiple progressive nucleation phases during which relaxation or rearrangement of material leads to creep and accelerates with time before any major rupture. The monitoring of Himalayan surficial dynamics is challenging and expensive to access for scientific research purposes. The unfelt destructions produced by the surficial mass movement activities can only be recognized by satellite images if other monitoring is not possible. We focused on the Chamoli region, which is the most vulnerable or hazard-prone region in the NW Himalaya. Recently, on 7th February 2021, a huge rock-ice mass detached from the Raunthi peak at a height of 5600 m in the Chamoli district of Uttarakhand Himalaya. We found several pre-collapse and unfelt activities,in a post-mortem study, which were recorded at nearby highly sensitive broad-band seismic stations and radon detector instruments. The integrated study of the recorded signatures allows us to reconstruct the complete dynamic time-dependent nucleation phases, which intensify as time gets closer to the main detachment. Continuous monitoring of vulnerable regions, coupled with the identification and characterization of precursory signals, holds the fundamental clue for hazard mitigation. After the Chamoli disaster, we are more focused on monitoring unfelt activities and anomalies linked to hazards in the proximity of potentially endangered zones and also planning to deploy multi-parametric instruments such as automatic weather stations (AWS), broad-band seismometers (BBS), automatic water level recorders (AWLR) and infrasound array for real-time monitoring and integrated analysis with a view to forewarn against the hazards in the Himalayan terrain. The dense network of sensors will allow us to collect high-quality data and crucial information as a way forward for disaster mitigation and societal benefit.

How to cite: Tiwari, A., Sain, K., and Kumar, A.: Integrated Monitoring and Multi-Hazard Early Warning System for Himalayan Region: Insights from the Chamoli Disaster of 2021, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-703, https://doi.org/10.5194/egusphere-egu24-703, 2024.

EGU24-3808 | ECS | Orals | NH3.5

The mountains are falling and I must go: paraglacial landslide response to glacier debuttressing in southern Alaska 

Jane Walden, Mylène Jacquemart, Bretwood Higman, Romain Hugonnet, Andrea Manconi, and Daniel Farinotti

Glacier mass loss due to anthropogenic climate change has far-reaching implications, one of which is the destabilization of paraglacial slopes. The buttressing force, or the support provided by the glacier to adjacent valley walls, changes and eventually decreases to zero as glaciers dwindle. However, the processes governing this (de-)buttressing, the amount of support glaciers can provide, and to what extent glacier retreat is responsible for landslide (re-)mobilization are still poorly understood. Paraglacial landslides can be hazardous, especially in the proximity of deep water, where a catastrophic failure has the potential to produce a tsunami.

We investigated eight large (roughly 20 to 500 million m3) paraglacial landslides in southern Alaska, a region which is experiencing some of the fastest glacier retreat worldwide. The selected landslides have varying degrees of ice contact: some are still experiencing active glacier retreat and thinning, others have already lost contact with the glacier. One of the selected landslides has undergone catastrophic failure, the others have not. We reconstructed the deformation history of the eight sites using Landsat images from the 1980s to present and automated and manual feature tracking. The slope evolution was then compared to ice thinning rates, ice velocity changes, the proximity of the landslide to the glacier terminus, environmental conditions, and seismic energy. 

We found that both thinning and retreat are sufficient conditions for landslide (re-)activation. In two cases we documented periods of acceleration for slopes where ice is still present at the landslide toe but thinning rapidly. In two further cases, substantial thinning did not correspond to any detectable motion. In four cases we observed a rapid retreat of the glacier terminus as the glacier retreated progressively up-fjord which led to the sudden onset of slope motion. This acceleration suggests decreased stability, which may be important in close proximity to water-filled basins, where rapid retreat due to calving is common and catastrophic landslides can cause tsunamis if they impact the water. The association of reduced glacier-slope contact, especially at rapidly retreating termini, with accelerated slope deformation suggests that buttressing is indeed an important stabilizer for paraglacial slopes. Furthermore, the off-and-on nature of deformation suggests there are critical thresholds for buttressing that, when crossed, leave slopes prone to rapid change.

How to cite: Walden, J., Jacquemart, M., Higman, B., Hugonnet, R., Manconi, A., and Farinotti, D.: The mountains are falling and I must go: paraglacial landslide response to glacier debuttressing in southern Alaska, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3808, https://doi.org/10.5194/egusphere-egu24-3808, 2024.

EGU24-3812 | Orals | NH3.5

Millions of years of landslides in the Patagonian tableland 

Tomáš Pánek, Jakub Kilnar, Michal Břežný, and Diego Winocur

Dating the lifespan of slow-moving landslides poses a major challenge, typically limited to the most recent slope evolution within maximally 103 to 104 years. The Patagonian tableland, characterized by plateau basalts overlying weak sedimentary and volcaniclastic rocks, ranks among Earth's largest landslide provinces. Certain contiguous landslide areas, shaped mainly by rotational slides and spreads, exceed 1000 km2, affecting hundreds of kilometers of mesa escarpments. Our new landslide mapping in eastern Patagonia has allowed us to establish an unprecedentedly long history of landslide evolution, utilizing cross-cutting relationships with dated chronological markers such as glacial moraines and trimlines, lacustrine and marine paleoshorelines, and lava flows. Our findings indicate that the escarpments of the Patagonian plateaus primarily evolved in a retrogressive mode. Both mesas within (or nearby) and outside Pleistocene ice limits involve landslides with topographic footprints that have persisted for over 1 Ma; the oldest documented landslide rim is overlain by a lava flow with a 40Ar/39Ar age exceeding 5 Ma. Even in the most arid parts of the Patagonian tableland, repeated landslide reactivations occurred in the Quaternary, including the Late Holocene. In the western glaciated area, this is likely due to glaciation/deglaciation pulses, while in the eastern extraglacial part, it is probably associated with wetter periods linked to the strengthening of the eastern Atlantic circulation. We conclude that the Patagonian tableland boasts the longest documented landslide topographic footprints on Earth. Future research should prioritize high-resolution (direct radiometric) dating of landslide (re)activations and their correlation with paleoenvironmental changes.

How to cite: Pánek, T., Kilnar, J., Břežný, M., and Winocur, D.: Millions of years of landslides in the Patagonian tableland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3812, https://doi.org/10.5194/egusphere-egu24-3812, 2024.

EGU24-3817 | Posters on site | NH3.5

Failed Patagonian tableland: landslides distribution and controls 

Jakub Kilnar, Tomáš Pánek, Michal Břežný, and Diego Winocur

Argentinian Patagonia is formed mostly by tableland relief created by Cenozoic basaltic efusions, general uplift and relief inversion. The tableland is vastly effected by landslides. Using TanDEM-X we manually maped 30 000 km2 of landslides in the Patagonian tableland and conducted spatial analysis of their distribution and controls. Based on relative dating to lava efusions, glaciation and paleoshorlines we propose, that the landslide activity in the region spans across several millions of years. In contrary to general knowledge of landslide distribution, most of the landslides in the Patagonian tableland are located in low-seismicity, tectonicaly stable, semiarid to arid conditions. We propose, that the leading landslide distribution control is the tableland stratigraphy: basaltic caprock overlaying weak sedimentary and volcanoclastic rocks. The caprock protects the underlying weak rocks and thus it becomes elevated above the surroundings over time, forming plateaus and mesas. As long as the topography of the formed tableland becomes high enough to laterally expose underlaying weak rocks, the tableland margins becomes unstable and collapse. It starts as lateral spreading a rotational landslides and later often evolve to flow-like mass movements. Many of the plateaus and mesas in the Patagonian tableland are fringed by almost continuous landslides. Some mesas are already completly consumed by landslides. This study helps to understand distribution and evolvement of landslides in volcanic tablelands.

How to cite: Kilnar, J., Pánek, T., Břežný, M., and Winocur, D.: Failed Patagonian tableland: landslides distribution and controls, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3817, https://doi.org/10.5194/egusphere-egu24-3817, 2024.

EGU24-4203 | Orals | NH3.5

Development of counterscarps by flexural toppling of schist in the Bedretto valley, Swiss Alps 

Masahiro Chigira, Satoru Kojima, Andrea Pedrazzini, Fei Li, and Michel Jaboyedoff

We investigated the geological structure and the development of DGSD in the south side of the Bedretto Valley, Swiss Alps by field survey, topographic analysis, trenching, and 14C dating.

The Bedretto valley has major slope breaks approximately 300 m above the current valley bottom, which separate the area into two domains. Above the slope breaks, and in the catchments of the tributaries of the Bedretto valley, large flexural toppling occurs with counterscarps and troughs on two ridges between tributaries. Their hinges expose on the side of each ridge to suggest that the flexural toppling reaches to the depth of 200 m. The two large flexural toppling accompanied settling down of a wedge-shaped ridge top, which is bounded by two face-to-face normal faults. Below the slope breaks and on the side slopes of Bedretto valley, smaller but sharper counterscarps and terraces, which are of the incipient stage of counterscarps, develop. These counterscarps and troughs appeared by the preferential shearing along tectonic faults, which are pervasive in the area with a ~30 m average spacing. They are nearly parallel to the steeply-dipping schistosity; the faults may originate as lateral faults but reactivated as normal gravitational faults.

Deformation of the trenched sediments suggests that the flexural toppling occurred intermittently along a fault during three events, in which the first event had the largest dip slip of 30 m, much larger than the displacements of the subsequent events.

The third event at least was probably induced by an earthquake shaking, which is strongly suggested by the injection of fault gouge into the overlying sediments in the trough. Such injection should have been caused by pore pressure build up during earthquake shaking.

How to cite: Chigira, M., Kojima, S., Pedrazzini, A., Li, F., and Jaboyedoff, M.: Development of counterscarps by flexural toppling of schist in the Bedretto valley, Swiss Alps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4203, https://doi.org/10.5194/egusphere-egu24-4203, 2024.

EGU24-5228 | ECS | Orals | NH3.5

Influence of structural geology on rock slope failure in a paraglacial environment: insights from the Southern Swiss Alps 

Alessandro De Pedrini, Andrea Manconi, Christian Ambrosi, Federico Agliardi, and Christian Zangerl

The onset and development of large rock slope failures in alpine environments are influenced by a combination of multiple factors, including lithology, inherited structural features on different scales, and the morpho-climatic history of the region. In the Southern Swiss Alps, seven large rock slope failure accumulations can be recognized along the five valleys north of Bellinzona, (Riviera, Leventina and Blenio in Canton Ticino, Calanca and Mesolcina in Canton Graubünden).  
The region exposes a predominance of crystalline rocks as orthogneiss and paragneiss with similar mechanical characteristics, an aspect that limits the lithological control on the rock slope failures. In addition, the availability of detailed geochronological documentation of both glacial retreat following the Last Glacial Maximum LGM and the major slope collapses motivated the search for a potential correlation, which, however, has not been found (De Pedrini et al. 2023). 
For this reason, slope failures in this region are potentially controlled by the peculiar structural setting. 
In this work, we aim at investigating the impact of structural geology on style of activity and timing of the rock avalanches and deep rockslides of the region. We rely on a catalog of the instabilities (Ambrosi and Czerski, 2016 and De Pedrini et al. 2023) and lineament mapping based on the visual interpretation on 0.5 to 2 m resolution hillshade (swissALTI3D multidirectional Hillshade, Federal Office of Topography swisstopo) and stereo-photogrammetry of aerial strips (Image strips swisstopo, Federal Office of Topography swisstopo). The manual tracing of lineaments is compared with an automatic lineaments tracing performed on surface models of Switzerland in the form of a classified point cloud (swissSURFACE3D, Federal Office of Topography swisstopo). Knowledge on structural lineaments and site-specific field surveys allow us to identify the proper structural setting for each large rock slope failure (already collapsed, active or dormant), and to study structural patterns that may promote slope response after deglaciation at regional scale.
The results of this analysis, aimed at the definition of the influence of glacial retreat plus the influence of structural geology, could provide an additional instrument to the comprehension of the paraglacial slope response in crystalline rocks and could thus represent an added value for long-term hazard assessment.

How to cite: De Pedrini, A., Manconi, A., Ambrosi, C., Agliardi, F., and Zangerl, C.: Influence of structural geology on rock slope failure in a paraglacial environment: insights from the Southern Swiss Alps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5228, https://doi.org/10.5194/egusphere-egu24-5228, 2024.

EGU24-5417 | ECS | Posters on site | NH3.5

Numerical modeling of collapsed deep-seated gravitational slope deformations: insights from Velka Fatra Mts., Slovakia 

Andrius Toločka and Veronika Kapustová

Large-scale deep-seated gravitational slope deformations (DSGSDs) are common but not highly investigated phenomena around the world. In the Carpathian Mountains, they played an important role during the Quaternary evolution of typical core mountain ridges formed by crystalline basement and surrounded by Mesozoic deposits. There is evidence that most of the biggest catastrophic rock slope failures (collapses) in the Carpathian Mountains appeared exactly in areas that are affected by DSGSDs. Two DSGSD-affected slopes (Brdo and Žlebiny) on the northeast side of the Velka Fatra Mountains (Western Carpathians, Slovakia) have been subjected to a detailed investigation involving geomorphic mapping, remote sensing analysis, structural data collection, and numerical modeling. To improve our understanding of these gravity-induced processes, we performed a back-analysis of collapsed DSGSDs through a 4-stage continuum-based finite-element model set up using the RS2 code (Rocscience). We used geomechanical rock data from fieldwork and previous laboratory tests, as well as interpretation in RSData software (Rocscience), to obtain the major rock mass parameters for the models. Results show that these DSGSDs are strongly predisposed by regional geological structures given by the intersection of bedding planes, joint sets, and thrust faults. The numerical modeling approach and performed back-analysis have enabled a better view of the development of these deep-seated slope failures in the Velka Fatra Mountains. It suggests a high diversity of mechanisms leading to the origin of these DSGSD cases. The main causal factors influencing their development have been bedrock structure, the lithological composition of dolomite and limestone layers, thrust faulting, and, finally, deep weathering of the rock mass. Both cases have deep basal shear zones and a few series of gravitational faults associated with complex joint sets. According to the numerical modeling results, Brdo DSGSD shows a typical scenario of a symmetrical sackung surrounded by shallow landslide areas, while Žlebiny DSGSD developed into a one-sided deep-seated slide with a few large-scale tilted rock blocks.

How to cite: Toločka, A. and Kapustová, V.: Numerical modeling of collapsed deep-seated gravitational slope deformations: insights from Velka Fatra Mts., Slovakia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5417, https://doi.org/10.5194/egusphere-egu24-5417, 2024.

A fixed point in geodesy is a stable survey point that fulfils the following two conditions: The point is known in coordinates from a previous survey (by position and/or height) and the point is permanently marketed (stabilised) in nature. Fixed points serve as reference points for surveys of all kinds. To determine the coordinates of the fixed points in the modern European reference system ETRS89, not only all previously measured GNSS vectors are used, but also all terrestrial observations measured since 1906, i.e. direction, elevation angle and distance measurements (Otter et al., 2017). More than 20.000 individual RTK measurements on these fixed points by using APOS (Austrian Positioning Service) complete the measurement dataset. Approximately 60.000 triangulation points (TPs) form a three-dimensional point network throughout Austria, whereas about 70 % of all TPs have multiple measurements. Fixed points should be stable, but this is not always the case, as fixed points are often influenced in their spatial position by gravitational mass movements, among other factors.

We have interpreted the entire elevation model/hill shade of Austria (1-metre resolution, based on ALS-data) and mapped all DSGSDs that manifest themselves geomorphologically in the terrain. This data set was intersected with the fixed points in order to identify those points that lie within a DSGSD. By analysing the results of the individual fixed point survey epochs, conclusions can be drawn about deformation rates of mass movements after excluding possible sources of error and statements can be made retrospectively up to the year in which the particular point was created (Otter et al., 2017).

Overall the fixed point measurements of the Federal Office of Metrology and Surveying Austria (BEV) represent a high quality and long term dataset that stands for its own and can support other slope monitoring methods. The interpretation of the dataset concerning slope deformations is not trivial but can deliver information of the range of movements over decades with uncertainties of 0 to 1.5 cm.

By combining different data sources (InSAR, ALS, in-situ measurements, fixed points, ...) we can present a preliminary, comprehensive data set on the activity status and often associated deformation rates of DSGSDs in Austria.

References:

Otter, J.; Imrek, E.; Melzner, S. (2017) Geodätische Grundlagenvermessung als Werkzeug in der Naturgefahrenanalyse in: Wimmer-Frey, I.; Römer, A.; Janda, C. [Hrsg.] Angewandte Geowissenschaften an der GBA. Wien, S. 147–152.

 

 

How to cite: Ostermann, M. and Blauensteiner, F.: Analysing geodetic fixed point survey time series to evaluate the long-term activity of DSGSDs in Austria, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5578, https://doi.org/10.5194/egusphere-egu24-5578, 2024.

EGU24-6268 | Posters on site | NH3.5

Enhancing rockfall modelling through an integrated workflow, from source area definition to susceptibility zoning 

Roberto Sarro, Mauro Rossi, Paola Reichenbach, Pablo Vitali Miranda-Garcia, and Rosa María Mateos

The main complexity of rockfall modelling lies in the need for a series of dedicated methodological choices and assumptions. Despite specific aspects of modelling have been largely discussed in the literature, a comprehensive methodology to assess susceptibility posed by rockfalls is still missing. To fill this gap, we have proposed a novel workflow in this study, including methods for identifying source areas, deterministic runout modelling, classifying runout modelling output to establish an objective rockfall probabilistic susceptibility zonation, and comparing and validating the results. This methodology is applied to the island of El Hierro (Canary Islands, Spain), where rockfalls pose a significant threat to structures, infrastructure, and the population.

In the first stage, three different approaches were proposed to identify rockfall source areas, ranging from scenarios with limited data availability to those with extensive topographic, geological, and geomorphological information. The first approach employed a morphometric criterion, establishing a slope angle threshold to identify source areas. The second approach used a statistical method employing Empirical Cumulative Distribution Functions (ECDF) of slope angle values. The third method employed a probabilistic modelling framework that combined multiple multivariate statistical classification models, using mapped source areas as dependent variables and thematic information as independent variables.

Subsequently, a rockfall simulation was carried out using a physically based model using the maps of the three source areas as input. A key result of the rockfall modelling simulations was the rockfall trajectory count maps. These maps, highlighting areas prone to rockfall on El Hierro, indicated the probability that a given pixel would be affected by these processes.

Then, this study also explores the strategies to validate the rockfall susceptibility model outputs, using different types of inventories. Therefore, to get susceptibility maps with a probabilistic approach, two classification methods were applied: unsupervised and supervised statistical techniques using distribution functions. The unsupervised classification used only the raster map of rockfall trajectory counts, while the supervised classification considered additional data on areas already affected by rockfalls.

Diffused metrics comparing modelled and observed values (i.e., ROC plots and correspondent AUCROC) can be used to show the performances of susceptibility models, regardless the adopted classification approach. Finally, the six susceptibility maps were compared to emphasize the impact of source area definition on the distribution of rockfall trajectories.

In summary, the methodology proposed provides guidance for an objective and reliable rockfall modelling, supporting civil protection, emergency authorities, and decision-makers in evaluating and assessing potential rockfall impacts. This contributes to enhanced rockfall hazard assessments and improved mitigation strategies on the island of El Hierro and potentially in similar geological settings globally.

How to cite: Sarro, R., Rossi, M., Reichenbach, P., Miranda-Garcia, P. V., and Mateos, R. M.: Enhancing rockfall modelling through an integrated workflow, from source area definition to susceptibility zoning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6268, https://doi.org/10.5194/egusphere-egu24-6268, 2024.

EGU24-6335 | Orals | NH3.5 | Highlight

Infrasound analysis of break-off events  from Planpincieux glacier, Mount Blanc, Italy 

Emanuele Marchetti, Fabrizio Troilo, Paolo Perret, Giacomo Belli, Duccio Gheri, and Claudia Sanchez

Glacier break-off events constitute a severe hazard in Alpine regions and their effects are expected to increase soon because of climate changes. Within this rapidly changing scenario, the development and implementation of new monitoring solutions and warning systems, able to detect collapses and possibly estimate the volumes, is of critical importance.

In this paper we present the analysis of avalanching activity from Planpincieux glacier (Aosta valley) through infrasound data collected by a small aperture (~ 150 m) array deployed at short distance (~ 2000 m) from the hanging front. The analysis is performed over five time periods between August 2020 and December 2022 summing up into 360 days. From a data set of confirmed events, infrasound wave parameters (intensity, peak amplitude, frequency and duration) are compared with collapse volumes estimated from photogrammetry and experimental relations are defined.

Morerover, characteristics of infrasound signals of confirmed events are used to extract signals that are likely produced by collapses from the whole dataset of infrasound detections and a volumetric flux of collapses from the front of the Planpincieux glacier is derived through time.

 

How to cite: Marchetti, E., Troilo, F., Perret, P., Belli, G., Gheri, D., and Sanchez, C.: Infrasound analysis of break-off events  from Planpincieux glacier, Mount Blanc, Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6335, https://doi.org/10.5194/egusphere-egu24-6335, 2024.

EGU24-6627 | ECS | Posters on site | NH3.5

Landslides on the growing folds of the Kura fold-and-thrust belt (Azerbaijan, Georgia) 

Michal Břežný, Tomáš Pánek, Hans-Balder Havenith, and Alessandro Tibaldi

Rising hillslopes in the active fold-and-thrust regions present new landslide-prone slopes. However, studies investigating landslides in newly formed fold-and-thrust belts are limited. In this research, we analyse landslide occurrences in the Kura fold-and-thrust belt, a geologically active region at the southern edge of the Greater Caucasus. This area has experienced significant tectonic shaping over the last 2-3 million years, affecting Miocene to Quaternary sediments. Using satellite imagery, we identified about 1600 landslides, a quarter of which are active. These landslides, although occupying less than 1% of the land, are predominantly found at higher elevations and areas with greater relief. They mainly occur in regions elevated by tectonic forces, especially on steep anticlines and valley slopes cut by active faults. Our findings lead to a conceptual model for the temporal evolution of landslide patterns in weak sediment-based fold-and-thrust belts: 1) Initially, slow deformations at thrust fronts lead to landslides in deep valleys intersecting the uplifting hanging walls. 2) As anticlines rise and steepen, they become more prone to planar sliding when dip slopes exceed friction angle, and valley development creates additional dip slopes resulting in widespread landslides. 3) Finally, erosion lowers relief, forming badlands and reducing landslide occurence.

How to cite: Břežný, M., Pánek, T., Havenith, H.-B., and Tibaldi, A.: Landslides on the growing folds of the Kura fold-and-thrust belt (Azerbaijan, Georgia), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6627, https://doi.org/10.5194/egusphere-egu24-6627, 2024.

EGU24-6726 | Orals | NH3.5

A modified Voellmy rheology for modeling rock avalanches 

Stefan Hergarten

Voellmy's rheology was originally developed for snow avalanches in the 1950s. However, it has also been widely applied to rock avalanches and to debris flows. In its original form, Voellmy's rheology assumes that the effective friction is the sum of Coulomb friction and a velocity-dependent term. While the Coulomb friction term is necessary for letting avalanches stop after a finite time, it causes problems with regard to the long runout of huge rock avalanches. This long runout requires Coulomb friction coefficients much lower than typically assumed for granular media, which finally result in unrealistically smooth morphologies of the deposits. In this presentation, numerical simulations with a recently published modified version of Voellmy's rheology are shown and compared to the conventional version. The modified version assumes two distinct regimes of Coulomb friction and velocity-dependent friction with a transition at a critical velocity derived from the concept of random kinetic energy. The modified rheology explains the long runout of huge rock avalanches without assuming an artificially low Coulomb friction coefficient. Furthermore, it produces hummocky deposit morphologies even with isolated hills similar to toma hills.

How to cite: Hergarten, S.: A modified Voellmy rheology for modeling rock avalanches, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6726, https://doi.org/10.5194/egusphere-egu24-6726, 2024.

Landslides, as a ubiquitous type of mass wasting phenomena, occur under various geological and environmental conditions and exhibit diverse failure patterns. Among various factors, weathering has been widely recognised as one of the primary drivers on landslide evolution over geological timescales. However, how weathering induces slope instabilities, including how pre-failure rock mass degradation contributes to the landslide failure development and post-failure deposition of mobilised geomaterials, has not been fully understood. In this study, we develop a novel, physics-based unified computational framework to capture weathering-induced landslide evolution over multiple time scales, from the long-term pre-failure rock mass deformation to the short-term slope rupture and post-failure runout dynamics. Weathering laws and failure criteria are coupled to capture the combined effects of time-dependent strength degradation and strain-driven damage processes, while a frictional velocity-weakening law is adopted to characterise the rapid movement of yielded masses. The non-linear governing equations of landslide dynamics are solved using an implicit particle finite element framework that can model all the landslide stages from the long-term material degradation to short-term failure and runout. We further investigate the effects of weathering conditions (type and rate), geological properties (fracture sets and rock matrix) and slope geometry (angle and shape) on the failure patterns. Our high-fidelity numerical simulations capture the emergence of diverse landslide failure patterns resulting from the complex interplay among rock lithology, fracture distribution, weathering process, and gravitational forcing. Our numerical results show that matrix-dominated weathering tends to produce shallow landslides, while fracture-dominated weathering promotes the occurrence of deep landslides. For fracture-dominated weathering, the orientation of pre-existing fractures and the slope ratio significantly control the failure mode (e.g. falling, toppling, sliding, etc.), which further affects post-failure runout behaviour. Our computational framework opens the door to investigating and understanding weathering-induced rock slope failure evolution across spatial and temporal scales.

How to cite: Wang, L., Loew, S., Gu, X., and Lei, Q.: Emergence of diverse failure patterns in weathering-induced landslides: Insights from high-fidelity particle finite element simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6969, https://doi.org/10.5194/egusphere-egu24-6969, 2024.

In the realm of natural Earth-surface processes, such as mass movements exemplified by rock avalanches, a substantial entrainment of bed material along their trajectory is a common occurrence, amplifying both volume and run-out distance. The heightened mobility of these rapid gravity flows has been frequently ascribed by numerous researchers to the complete or partial fluidization of path material induced by swift undrained loading. An intriguing question arises: are there additional entrainment mechanisms at play in this process? To address this query, we executed a series of flume experiments designed to replicate rock avalanches overriding a saturated bed material. Our experimental findings revealed that the overriding flow induced a state of fluidization in the bed material, rendering it viscous. Furthermore, we observed that the rapid loading by the overriding debris increased pore pressure at the base, although it did not reach the threshold of complete fluidization. Rheological analysis of the bed material unveiled significant shear-thinning behavior, with viscosity diminishing rapidly as shear strain rate increased. Consequently, we posit that the concurrent effects of excess pore pressure at the basal layer and shear-thinning rheology in the flowing mass contributed to the fluidization of bed material and the ensuing extended run-out distance. This discovery offers a plausible natural elucidation for the extraordinary mobility of rock avalanches and holds promise for refining the precision and reliability of numerical simulations through the integration of the viscous model derived from our experimental endeavors.

How to cite: Zheng, Y. and Hu, W.: Flume tests and rheological experiments provide insights into the fluidization of bed material induced by shear thinning during the entrainment of rock avalanches., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7405, https://doi.org/10.5194/egusphere-egu24-7405, 2024.

EGU24-7631 | ECS | Posters on site | NH3.5 | Highlight

Causes, consequences and implications of the 2023 Lake Rasac GLOF, Cordillera Huayhuash, Peru 

Adam Emmer, Oscar Vilca, Cesar Salazar Checa, Sihan Li, Simon Cook, Elena Pummer, Jan Hrebrina, and Wilfried Haeberli

Glacierized Peruvian mountain ranges are experiencing accelerated glacier ice loss, including the second highest mountain range – Cordillera Huayhuash – which has lost about 40% of its glacier area (deglaciated area of approximately 34 km2) since the 1970s. The exposure of a new land is associated with various processes including the formation and evolution of glacial lakes, changing stability conditions of mountain slopes, and rapid mass movements. In this study, we integrate the analysis of meteorological data, remotely sensed images and field observations in order to document the most recent large mass movement-induced glacial lake outburst flood (GLOF) from moraine-dammed Lake Rasac (February 2023). We found that the triggering mass movement (the failure of Rasac arête ridge with an estimated volume of 1.1 to 1.5 ∙ 106 m3) occurred from the frozen rock zone with cold, deep-reaching permafrost and was preceded by several small magnitude precursory events. The stability reduction of the frozen rocks in the detachment zone most likely relates to deep warming, but not to critical conditions of warm permafrost with unfrozen water. Further, we describe the surprisingly short-distanced process chain (attenuated by the Lake Gochacotan located 3.5 km downstream from the detachment zone) and analyze the transport of large boulders with the use of hydrodynamic modelling, revealing that flow velocities > 5 m/s must have been reached in case of translational motion and > 10 m/s in case of rotational motion of the largest transported boulders (diameter > 3.5 m). This study helps us to understand (i) mechanisms, amplification and attenuation elements in GLOF process chains; and (ii) altering frequency-magnitude relationships of extreme processes in rapidly changing high mountain environments on regional scale (both large magnitude rockfalls and GLOFs). Considering the recent Peru-wide GLOF inventory published in 2022, this event corroborates the assumption of increasing frequency of large mass movement-induced GLOFs originating from warming permafrost in recent decades. 

How to cite: Emmer, A., Vilca, O., Salazar Checa, C., Li, S., Cook, S., Pummer, E., Hrebrina, J., and Haeberli, W.: Causes, consequences and implications of the 2023 Lake Rasac GLOF, Cordillera Huayhuash, Peru, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7631, https://doi.org/10.5194/egusphere-egu24-7631, 2024.

EGU24-8202 | ECS | Posters on site | NH3.5

Mapping release and propagation areas of permafrost-related rock slope failures in the French Alps: A new methodological approach at regional scale 

Maeva Cathala, Florence Magnin, Ludovic Ravanel, Luuk Dorren, Nicolas Zuanon, Frederic Berger, Franck Bourrier, and Philip Deline

Permafrost-affected rockwalls are increasingly impacted by the effects of climate change and rising air temperature leading to rock slope failures, threatening human lives and infrastructure. Populations and policy makers need new methods to anticipate these potential hazards and their consequences.  The aim of this study was to propose a mapping approach of susceptible release areas of rock slope failures and resulting runout distances at a regional scale to identify hotspots for hazard assessment.

To do so, we used an inventory of 1389 rock slope failures (volume > 102 m3)recorded in the Mont-Blanc massif from 2007 to 2019 and determined the topographical and permafrost conditions that are most prone to their triggering using a digital terrain model and a permafrost map. These conditions are used in a multi-criteria GIS approach to identify potential unstable slopes at the French Alps scale. Then, the potential release area map is used as input to map the runout of potential events, using a propagation model based on a normalised area dependant energy line principle. The resulting maps of release and propagation areas could be used to point out human assets and lakes which could be impacted by rock slope failure hazards. In this communication we will show how theses maps can be used to identify potential hotspots for a regional hazard assessment.

This work is a first step to identify hot spots for a regional hazard assessment where more detailed analyses will be required to evaluate potential risks at a local scale.

How to cite: Cathala, M., Magnin, F., Ravanel, L., Dorren, L., Zuanon, N., Berger, F., Bourrier, F., and Deline, P.: Mapping release and propagation areas of permafrost-related rock slope failures in the French Alps: A new methodological approach at regional scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8202, https://doi.org/10.5194/egusphere-egu24-8202, 2024.

EGU24-8891 | ECS | Orals | NH3.5

Climate change impact on rock avalanches in metamorphic rock masses in Tyrol, Austria 

Lukas Prandstätter, Christian Zangerl, Christine Fey, Tatiana Klisho, and Herbert Formayer

Rockfalls and rockslides are a common hazard in alpine terrain and are major factor of alpine landscape evolution. They are characterized by a complex combination of geological, hydrological, geomechanical and meteorolocical processes and occur in a wide variety of geological and structural settings and in response to various loading and triggering processes. In the Alps in particular, extremely rapid rock avalanches reaching a volume of several 10000 m3 or more have the potential to cause serious damage to both humans and infrastructure. As global warming progresses, the meteorological and climatological factors that influence rock avalanche formation will change. Especially, in the high mountain environment rock avalanches are strongly influenced by climate change due to thawing of permafrost and the retreat of glaciers. Less obvious is the influence of climate change on the formation of rock avalanches at lower altitudes, and thus there is a need for additional research.

In this study, we investigate the impact of global warming on selected rock avalanche case studies with volumes above several tens of thousands of cubic meters. The study area covers approx. 3400 km2 in the metamorphic rock mass of the Ötztal Stubai Crystalline, the Silvretta and the Glockner Nappes as well as the units of the Engadin Window of the Tyrolian Alps, Austria.

The aim of this work is to identify the processes that led to our case studies and if these processes are influenced by climate change factors, such as changes in temperature, precipitation, freeze-thaw cycles, snow coverage, etc. The climatic factors will be investigated in terms of both their short-term and long-term influence on the trigger mechanisms.

Advanced remote sensing techniques were used on site to carry out small to large-scale investigations. Terrestrial laser scanning (TLS) and Airborne laser scanning (ALS) enables us to create high-resolution recordings of inaccessible rock faces, supported by 3D point cloud analyzing tools. In addition, where TLS campaigns are not possible, we use an unmanned aerial vehicle (UAV) photogrammetry system that provides 3D point clouds and delivers a 3D model of the site. Geological field investigations were performed to record lithological, hydrogeological and structural features. This results in a comprehensive geological model of the failure area. A 3D discontinuity network was developed based on the combined analyses of remote sensing and discontinuity mapping data, providing the basis for structural geological analyses and distinct element modelling studies.

With regard to the above criteria, we have selected several case studies. Most of the case studies are located well above 2500 m above sea level in glaciated or recently glaciated areas. For all case studies, we were able to document at least one rock avalanche event with a volume exceeding several 10000 m3. A high-resolution climate model was created for the documented events. We then began to collect and evaluate the existing literature on the individual case studies.

How to cite: Prandstätter, L., Zangerl, C., Fey, C., Klisho, T., and Formayer, H.: Climate change impact on rock avalanches in metamorphic rock masses in Tyrol, Austria, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8891, https://doi.org/10.5194/egusphere-egu24-8891, 2024.

EGU24-9085 | Orals | NH3.5 | Highlight

Probabilistic rockfall hazard and risk analysis along the El Portal Road in Yosemite National Park (California, USA) 

Federico Agliardi, Paolo Frattini, Greg M. Stock, Teseo Tosi, Camilla Lanfranconi, and Brian D. Collins

Yosemite National Park attracts millions of visitors each year with its stunning landscape, characterized by 1000 m high granite cliffs that are highly susceptible to rockfalls. Between 2010 and 2020, more than 300 rockfalls affected the 12 km long El Portal Road, used by 30% of visitors to enter the park, causing road closures and fatalities. Since National Park policies limit engineering mitigation on natural slopes, risks along roads are managed through traffic practices based on local hazard evaluation.

In this perspective we developed a probabilistic risk analysis workflow, aimed at estimating the annual probability of loss of life for people driving a vehicle along the road. The analysis was carried out for every 10-m-long segment of each travel lane, to and from Yosemite Valley. We based our analyses on 3D rockfall runout simulations performed with the Hy-STONE simulator, and on rockfall event (1857-2022) and vehicle traffic data collected by the U.S. National Park Service. Runout simulations were performed over 18 km2 with a spatial accuracy of 1 m. Simulation parameters were calibrated by back-analysis of past events and validated with field evidence. Fifteen million trajectories were simulated for five volume scenarios (0.01-100 m3), providing local information of transit frequency and kinetic energy.

A probabilistic hazard analysis was developed using the probabilistic rockfall hazard analysis (PRHA) method (Lari et al, 2014), which calculates the kinetic energy that can be exceeded in N years for each road segment. The method integrates different rockfall volume scenarios, with specific return times, in a probabilistic framework accounting for modelling uncertainties. For each considered scenario, the annual rockfall onset frequency was derived by a magnitude-frequency (MF) curve, based on the Yosemite event data from 2010-2020 and combined with a field-based talus MF curve, to redistribute frequency among blocks disaggregated during runout. The annual rockfall frequency at each slope segment was then calculated by combining the onset frequency with the transit frequency provided by runout simulations. The exposure analysis, dependent on block size, vehicle size and speed, considered the probability of a vehicle being in the path of a falling block when it reaches each road segment. Since blocks coming from different sources may converge to a common location based on the 3D topography, we reconstructed the distribution of kinetic energy at each target road segment.

The probability of exceeding specific energy values, combined with the annual frequency of rockfall occurrence, allowed deriving probabilistic hazard curves for each scenario and for the ensemble. Based on expected kinetic energy and considering the number of visitors passing along the road every day as well as assumptions on the vulnerability of vehicles, we calculated the possible annual number of casualties for each road segment and the entire road, to identify the road sectors with the highest risk. Computed risk varies in time with clear weekly and seasonal patterns depending on the number of daily visitors and the weather conditions. Our study will provide park managers with tools to make adaptive decisions for managing risk in dynamically changing conditions.

How to cite: Agliardi, F., Frattini, P., Stock, G. M., Tosi, T., Lanfranconi, C., and Collins, B. D.: Probabilistic rockfall hazard and risk analysis along the El Portal Road in Yosemite National Park (California, USA), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9085, https://doi.org/10.5194/egusphere-egu24-9085, 2024.

EGU24-10312 | Orals | NH3.5

Deep-seated gravitational slope deformations in Sierra Nevada, Spain: insights from InSAR, geomorphic and stability analyses 

Jorge Pedro Galve, Cristina Reyes-Carmona, Federico Agliardi, Mara Cannarozzi, José Vicente Pérez-Peña, Marcos Moreno-Sánchez, David Alfonso-Jorde, Daniel Ballesteros, Davide Torre, José Miguel Azañón, and Rosa María Mateos

Sierra Nevada (Spain) is a mountain range thoroughly studied from a geological-geomorphological perspective due to its anomalously high local relief and the ongoing debate about its origin and geological structure. From the standpoint of slope dynamics, several studies have carried out, but it was not until last year that deep-seated gravitational slope deformations (DSGSDs) were described in this mountain range. Their recognition was facilitated by synergizing geomorphological assessments with data from two well-established techniques: Differential Synthetic Aperture Radar Interferometry (DInSAR) and Landscape Analysis using the normalized channel steepness index (ksn), a geomorphic index commonly used to outline landscape perturbations in tectonically-active mountain ranges. Systematic evaluation of ksn anomalies along rivers illuminated key DSGSD sectors that were studied in detail. This approach resulted in a novel inventory of 17 DSGSDs in the southwestern sector of the range, providing an initial figure of the widespread occurrence of large DSGSDs in Sierra Nevada.

In a second phase, we conducted a detailed study of two slopes affected by DSGSDs in the Poqueira catchment, which provided new insights into Sierra Nevada’s DSGSDs. There, we characterized slope deformations by detailed morpho-structural mapping supported by fieldwork and interpretation of optical and LiDAR-derived imagery, resulting in morpho-structural maps and interpretative cross-sections. Collected data allowed setting up a series of 2DFEM multistage elasto-plastic models, parametrized by laboratory data and field rock mass assessment and validated with field evidence and DInSAR data. The studied cases are characterized by multiple nested landslides that become increasingly shallow, deformed, and active towards the valley. The geometry and kinematics of DSGSDs seem to be partially influenced by the orientation of foliation, indicating rock mass anisotropy, with dip slopes mainly exhibiting translational movements and anti-dip slopes demonstrating prevalence of rotational motions. We tested our initial hypothesis that these slope instabilities in the region were initiated because the development of fluvial incision, favored by the active tectonics and uplifting of the range. Preliminary findings of our analyses suggest that fluvial incision was a key trigger of DSGSDs in Sierra Nevada, but not the only one. Model simulations emphasize that, in addition to fluvial incision, rock mass anisotropy and long-term seismic activity played a crucial role in the onset and accumulation of large deformations of high slopes across the region, favoring the occurrence of significant mass movements. Considering this, rough estimates regarding the timing of incision and seismic activity suggest that initial DSGSD onset took place over a timescale of 104-105 years.

How to cite: Galve, J. P., Reyes-Carmona, C., Agliardi, F., Cannarozzi, M., Pérez-Peña, J. V., Moreno-Sánchez, M., Alfonso-Jorde, D., Ballesteros, D., Torre, D., Azañón, J. M., and Mateos, R. M.: Deep-seated gravitational slope deformations in Sierra Nevada, Spain: insights from InSAR, geomorphic and stability analyses, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10312, https://doi.org/10.5194/egusphere-egu24-10312, 2024.

EGU24-10488 | Posters on site | NH3.5

Advanced Discontinuity Detection Algorithm for Geological Formations Using High-Density Point Cloud Data 

Antonin Chale, Michel Jaboyedoff, and Marc-Henri Derron

Advanced Discontinuity Detection Algorithm for Geological Formations Using High-Density Point Cloud Data

Antonin Chale, Michel Jaboyedoff, Marc-Henri Derron

Geological hazard analysis relies on precise identification and characterization of discontinuities in rock formations, crucial for evaluating rock stability. While techniques such as Structure-from-Motion (SFM) and Light Detection and Ranging (LiDAR) have significantly advanced high-density 3D point cloud (PC) data acquisition, detecting structural irregularities in complex geological formations remains a challenge. We have developed a new discontinuity detection algorithm that emulates human visual perception. The algorithm employs multi-angle scanning, point cloud optimization techniques, and efficient multiprocessing to comprehensively survey the point cloud. Density maps are generated to identify and determine the orientation of discontinuities, proving effective in both synthetic models and real LiDAR data. The algorithm comprises three primary steps: an initial point cloud scan, density map generation, and visualization of discontinuities with their initial orientation. A secondary scan focuses on the density map, projecting data into a 2D representation to detect a second vector orientation, crucial for identifying discontinuity sets. Thanks to the previous steps we can deduce the orientation of the discontinuity sets. While the algorithm’s capability to handle both synthetic and real-world data sets highlight its potential significance in structural analysis, ongoing work aims to enhance its applicability for larger and more complex datasets. But also, the possibility of extracting the points involved in the different discontinuity sets.

 

References:

Adrián J. Riquelme, A. Abellán, R. Tomás, M. Jaboyedoff, (2014)  " A new approach for semi-automatic rock mass joints recognition from 3D point clouds," Computers & Geosciences, Volume 68, 2014, Pages 38-52.

Matthew J. Lato, Malte Vöge, (2012) "Automated mapping of rock discontinuities in 3D lidar and photogrammetry models," International Journal of Rock Mechanics and Mining Sciences, Volume 54, 2012, Pages 150-158.

How to cite: Chale, A., Jaboyedoff, M., and Derron, M.-H.: Advanced Discontinuity Detection Algorithm for Geological Formations Using High-Density Point Cloud Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10488, https://doi.org/10.5194/egusphere-egu24-10488, 2024.

The steep terrain in mountainous areas poses a significant threat to people's safety due to frequent geological hazards(e.g., rockfall and slope collapse), making effective management, monitoring, and timely issuance of alerts and warnings are crucial for highway authorities. Previous studies focus on studying the rainfall thresholds for possible rockfall occurrence. Recently, machine learning using seismic signals has been applied to detect rockfall events and monitor rockfall activity. However, supervised machine learning algorithms have relied on predefined labels, and the limited accumulation of data makes predicting model reliability challenging. The time-consuming model training can limit the practical application of the above models. In response to both aforementioned challenges, we first selected the roadside slope with relatively high activity of rockfalls and earthquakes as the study site and installed a seismic station on the crest of the slope. Then, we use an unsupervised machine learning framework to reveal patterns from unlabeled data and cluster seismic signals in continuous seismic records in the single three-component seismic station. Using continuous seismic data over one year, our approach combines a deep scattering network, features extraction, and features cluster to detect structures of signal segments. To illustrate the framework, a deep scattering network performs convolution and pooling on the three-component seismic signal data to extract multiscale information and construct scattering coefficients. For feature extraction, four different algorithms were employed: principal components analysis (PCA), independent components analysis (ICA), singular value decomposition (SVD), and Uniform Manifold Approximation and Projection (UMAP). Subsequently, we cluster the primary features using unsupervised learning algorithms such as K-means and Gaussian Mixture Model(GMM). We demonstrate the group categories belonging to rockfall events with in-situ data time-lapse images and videos. An approach proposed in this study could achieve rapid model training for building on-site rockfall warning systems using only single-station seismic records. Our high capability recognition model of rockfall events is ready to be implemented globally with high rockfall activity.

 

Keywords: unsupervised machine learning, deep scattering network, rockfall, seismic records, on-site early warning 

How to cite: Li, Y.-R. and Chao, W.-A.: A fast unsupervised deep learning algorithm using seismic records of a single station for roadside rockfall recognition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14088, https://doi.org/10.5194/egusphere-egu24-14088, 2024.

EGU24-15526 | ECS | Posters on site | NH3.5

Investigation into rockslides by the adaptive rock discrete fracture analysis (RDFA) method 

Bin Gong and Tao Zhao

The rock discrete fracture analysis (RDFA) method was proposed as a combination of the rock failure process analysis method and the discrete element method. Leveraging the statistical strength theory and contact mechanics, it can effectively capture the intricate continuum-discontinuum behaviors inherent in rock mechanics, encompassing fracture and fragmentation phenomena. Enabled by a sophisticated nodal updating scheme, RDFA can dynamically adjust nodes at critical crack tips in accordance with strength criteria, facilitating accurate modeling of zero-thickness crack initiation and propagation. Noteworthy is its capacity to accommodate the inherent heterogeneity of rock masses, enabling holistic consideration of localized damage and fine crack development. Rigorously validated through the Brazilian disc and uniaxial compression tests, RDFA consistently aligns with the analytical solutions and experimental data. After that, it was applied to analyze the rockslide characteristics at the Anshan Road station in the Qingdao metro, China, and illuminated crucial insights. The results show that in the presence of 60° oriented joints with 5m spacing, the high stress concentration primarily emerged at the slope toe, leading to the localized tensile damage and the formation of a sliding surface. Subsequent rock sliding induced compression and collision among blocks, precipitating continuous failure within the sliding body. Additionally, the presence of intermittent joints notably contributed to progressive rockslide, particularly triggering the localized failures in the lower part of the slope.

How to cite: Gong, B. and Zhao, T.: Investigation into rockslides by the adaptive rock discrete fracture analysis (RDFA) method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15526, https://doi.org/10.5194/egusphere-egu24-15526, 2024.

EGU24-15711 | ECS | Orals | NH3.5

Rockfalls risk assessment along a E45 motorway section in South Tyrol (Italy) 

Francesco Lelli, Leonardo De Rosa, Lucia Simeoni, Francesco Ronchetti, Vincenzo Critelli, and Alessandro Corsini

The E45 motorway in South Tyrol (Italy) is exposed to rockfalls in many locations. For this reason, a significant number of rockfall risk reduction measures (nets, barriers, etc) has been progressively installed since its construction. Planning of further mitigation and monitoring measures can benefit from the assessment over a large-area and at adequate scale, of the exposure to rockfalls and of the associated risk, a piece of knowledge that this study has provided for a 13.5 km motorway section.

First, susceptibility mapping has been carried out using bivariate statistical methods with supporting evidences from an inventory of rockfalls occurrences covering the period 1993 to 2020. This has allowed to define potential rockfall detachment zones located upslope the E45. For each zone, rockfall runout modelling with RocPro3D software by considering 0.5 m and 2.0 m blocks diameter and high-resolution Lidar DTM has allowed to assess potential interactions between rockfall and different motorway structures (i.e. viaduct piers, tunnel entrances and road embankments). Spatial-temporal frequency of 2 m diameter rockfall (i.e. n° of rockfalls per year and unit area) has been assessed on the basis of the inventory of rockfalls occurrences and of the overall extent of slopes resulting highly susceptible to rockfalls. On such basis, the expected rockfall triggering frequency (n° events/year) in each source area has been assessed by considering its extension.  Hazard has been assessed by using an heuristic matrix-based approach that combines frequency and geomechanics (expressed by the GSI) of the rock masses. Rockfall spatial impact frequency, energy and bounce height determined by runout models have been used to establish exposure and vulnerability (i.e. expected damage level) of the motorway infrastructures. Finally, risk has been evaluated in function of hazard and vulnerability (by using combination matrices tailored to each type of interaction of rockfall – on infrastructures taken into consideration.

Results allowed us to determine and map that, out of the total 13.5 km motorway section considered, about 1.5 km for 0.5 m diameter blocks, and about 3.2 km considering 2.0 m diameter blocks, should be considered at high to very high rockfall risk. This result is also relevant with respect to the identification of priorities for more in-depth slope-scale surveys and monitoring of rockfalls in the perspective of further structural and non-structural mitigation measures implementation.

How to cite: Lelli, F., De Rosa, L., Simeoni, L., Ronchetti, F., Critelli, V., and Corsini, A.: Rockfalls risk assessment along a E45 motorway section in South Tyrol (Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15711, https://doi.org/10.5194/egusphere-egu24-15711, 2024.

EGU24-16064 | ECS | Posters on site | NH3.5

Back analysis of the 2023 rockfall event of Martigny (Switzerland): trajectography prediction to future potential hazard along road 

Tiggi Choanji, Antonin Chale, Wei Liu, Li Fei, François Noël, Marc-Henri Derron, and Michel Jaboyedoff

In this study, we back analysed a rockfall that occurred on a road in Martigny, Switzerland, on 15 March 2023 to determine the trajectory involving block fragments of approximately 43 m3 in total with block maximum 15 m3 and to identify factors that could contribute to future rockfalls in the area. A combination of remote sensing techniques such as LiDAR, photomosaic, and SfM (Structure for Motion) from drone have been performed to reconstruct the rockfall event and to predict the future potential for rockfalls. Our results suggest that the rockfall was caused by a combination of factors, including the  sliding failure mechanism occurred along a surface deeping to the valley with an angle of 54.5o, the presence of jointed and cracks in the rock with high aperture. A series of 10,000 of block propagations using the scarring model algorithm from stnParabel to produce an area of deposition in agreement with observation made in the field, with corresponding energy line from simulation average has an angle of 35.5 o. The trajectories of blocks are attributed to the high damping effects of the ground conditions and the vineyard rock fences which reduced the distance travelled by the falling rock, and the vineyard terraces slope angle lower than the average slope. While rock protections fences have been installed for protection on the falling block area, however there is a need to consider additional measures, as the rock structure in this area is larger than the width of the cliff face, which makes it more susceptible to rockfalls. Such study points out that the calibration of rockfall simulation based on only few blocks is very challenging.

How to cite: Choanji, T., Chale, A., Liu, W., Fei, L., Noël, F., Derron, M.-H., and Jaboyedoff, M.: Back analysis of the 2023 rockfall event of Martigny (Switzerland): trajectography prediction to future potential hazard along road, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16064, https://doi.org/10.5194/egusphere-egu24-16064, 2024.

Rock avalanches are one of the most destructive geological phenomena in mountainous regions. Understanding the dynamics and characteristics of rock avalanche movement plays a crucial role in assessing the potential hazards. However, the prediction for rock avalanche propagation is still challenging. Our study used an inventory of rock avalanches from Central Asia containing 412 historical cases from 6 countries provided by A. Strom. Considering several input parameters, the machine learning-based approach of extreme gradient boosting with grid search optimization was proposed. Input parameters including confinement type, headscarp height, mean slope angle of headscrap, length and width of the headscarp base, source volume, and maximal height drop (Hmax) are analyzed and discussed. Our proposed model can multi-output the distance of propagation L and the total impacted area, which outperformed by comparison with other machine learning models. Eleven rock avalanche events in Uzbekistan were introduced to demonstrate that the proposed model can be applied to prediction for limited parameters. For future work, we intend to propose a Convolutional Neural Network (CNN) architecture that combines spatial inputs and metadata as input in machine learning. Spatial inputs including elevation, slope, aspect, curvature, and lithology were used for our proposed model. Additionally, the CNN-based deep learning approach might be possible to predict rock avalanches which are characterized by complex terrain with multiple source areas and diverging paths. 

How to cite: Lin, R.: Travel distance prediction for rock avalanche based on machine learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16109, https://doi.org/10.5194/egusphere-egu24-16109, 2024.

EGU24-16313 | ECS | Orals | NH3.5

Quantitative vulnerability assessment of buildings susceptible to slow-kinematic landslides 

Francesco Poggi, Francesco Caleca, Davide Festa, Olga Nardini, Francesco Barbadori, Matteo Del Soldato, Claudio De Luca, Francesco Casu, Riccardo Lanari, Nicola Casagli, and Federico Raspini

An approach for assessing the quantitative vulnerability, through empirical fragility and vulnerability curves, of masonry buildings exposed to slow-kinematic landslides is described. More in detail, the fragility curves express the probability of exceeding a given level of damage for a range of landslide intensity values. Starting from these ones, the vulnerability curve provides the mean level of damage severity to a given building (or aggregate of buildings) in relation to the landslide intensity value. The application of the vulnerability curve is exploited in the quantitative risk analysis (QRA), that quantifies the probability of a given level of loss.

The Department of Earth Sciences of the University of Florence has catalogued the severity damage landslide-induced to over four thousand masonry buildings gathered from in situ surveys in the northern Apennines. Moreover, to retrieve the fragility and, consequently, the vulnerability curves for buildings, the proposed method exploits the results of spaceborne Advanced Differential Interferometry SAR (A-DInSAR) analysis. In particular, such a method considers the landslide intensity value equal to the module of the vertical (up-down) and horizontal (east-west) deformation velocity obtained by properly combining ascending and descending Sentinel-1 DInSAR products, retrieved through the P-SBAS (Parallel-Small Baseline Subset) method developed at IREA-CNR.

This approach to assess the vulnerability has been integrated within the well-known QRA procedure, which is based on the application of the risk equation (R=H*V*E), where:

R is the landslide risk in terms of economic loss;

H is the hazard retrieved from the susceptibility map available for the entire Italian territory;

V is the vulnerability obtained directly from the equation of the vulnerability curve;

E is the exposure of buildings assessed from average real estate market parameters reported in the OMI (Osservatorio Mercato Immobliare).

The effectiveness of the proposed procedure has been tested over the municipality of Zeri (Massa-Carrara, Italy), where a large-scale landslide risk map has been produced. In particular, for each building of the study area, the hazard, the vulnerability, the exposure and the risk associated with it, are presented. The analysis estimates a total risk of 33.2 million euro for the Zeri municipality and the identification of specific buildings at highest risk. The provided result can be useful for the civil protection activities of the local administrator identifying areas with higher potentiality of damage on structures.

How to cite: Poggi, F., Caleca, F., Festa, D., Nardini, O., Barbadori, F., Del Soldato, M., De Luca, C., Casu, F., Lanari, R., Casagli, N., and Raspini, F.: Quantitative vulnerability assessment of buildings susceptible to slow-kinematic landslides, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16313, https://doi.org/10.5194/egusphere-egu24-16313, 2024.

EGU24-17618 | ECS | Posters on site | NH3.5

Monitoring techniques for rockfall hazard across Malta, Mediterranean Sea. 

Christopher Gauci, Emanuele Colica, Daniel Fenech, and George Buhagiar

The Maltese Islands are exposed to a variety of environmental impacts because of their geographic position, one such impact being coastal hazards arising from erosion, exacerbated by climate change. The prevailing mitigation approach has traditionally been based on visual assessment of risk in specific sites rather than scientifically gathered information as an evidence basis for action to mitigate such risks. Constant monitoring is required to identify the probability and patterns of these events, which would assist in prediction. This was done using in situ measurements which include tiltmeter readings and topographic nail distances.  Certain sites were chosen across the Maltese islands for both installations, selected through historical research and other datasets including dangerous signage installations. Several nails were designated between primary and secondary signifying more stable to unstable cliff edge respectively. Distances using a total station were then taken from primary nails to the secondary nails for consecutive datasets. Tilt plates were installed in three areas with the nails and data recorded by positioning the tiltmeter at different directional axis. 

How to cite: Gauci, C., Colica, E., Fenech, D., and Buhagiar, G.: Monitoring techniques for rockfall hazard across Malta, Mediterranean Sea., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17618, https://doi.org/10.5194/egusphere-egu24-17618, 2024.

EGU24-17946 | ECS | Orals | NH3.5

Rock avalanche runout prediction for suggested failure scenarios. Case study of Cima del Simano rockslide (Switzerland) 

Charlotte Wolff, Michel Jaboyedoff, Andrea Pedrazzini, and Marc-Henri Derron

Rock avalanches events pose significant concerns in mountainous regions characterised by deep and narrow valleys. This has not deterred the ongoing development in these areas, where population settlements and infrastructure continue to expand, becoming increasingly susceptible to these risks. Cima del Simano instability in the Swiss Alps, located in the narrow Blenio Valley, is a deep-seated rockslide which could trigger such events in the future. A previous work outlined several scenarios for the rockslide failure defined by a specific area, volume (ranging from 2.30x105 m3 to 4.30x106 m3), and susceptibility to happen.

Given the proximity of a major road and several villages on both sides of the Valley, there is a real need to evaluate the potential runout distance in the event of rupture and propagation of the different failure scenarios. 

Literature often presents two distinct approaches for estimating the runout distance and the impacted area, both based on the retrospective analysis of historical landslide occurrence. The first approach is through empirical equations linking volumes of failure V and Fahrböschung angles f (tanf=aV^(-b), with a and b two empirical parameters to determine). The second approach consists in numerically simulating the flow propagation by means of dedicated software and by applying specific rheological models. 

This present work suggests applying both those techniques to evaluate the area that would be affected in the case of a rock avalanche at Cima del Simano, triggered by one of the suggested scenarios. We evaluated the runout distance for different angles f estimated based on the empirical relationship, and Dan3D for simulating the propagation applying the Voellmy rheology. Four simulations were conducted by varying the friction coefficient μ [-] and the parameter of turbulence ξ [m.s-2] in order to assess the minimal and maximal possible propagation in terms of runout distance L and lateral spreading based on domain of validity of those parameters according to literature. 

The distances L obtained empirically are longer than the ones from the simulations. This can be explained by the frontal confinement of the flow slowing down the propagation. The study is completed by an evaluation for each scenario of the probability of exceeding a certain distance L using existing statistical models for f variations. 

Additionally, the numerical simulations highlight the areas in gullies where debris are deposited during the flow propagation. Those areas can be sources for subsequent debris flow events. In a second step, we conducted an analysis of areas susceptible to debris flow with Flow-R and compared them with former debris flow events for validation. 

This study aligns with risk management to assist in making informed decisions regarding the evacuation plan in the event of a rupture and propagation of an important volume at Cima del Simano. 

How to cite: Wolff, C., Jaboyedoff, M., Pedrazzini, A., and Derron, M.-H.: Rock avalanche runout prediction for suggested failure scenarios. Case study of Cima del Simano rockslide (Switzerland), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17946, https://doi.org/10.5194/egusphere-egu24-17946, 2024.

EGU24-18131 | Orals | NH3.5 | Highlight

Introducing uncertainty in hazard analysis in a simple way: example of rockfalls 

Michel Jaboyedoff

One of the main problems of risk assessment is to evaluate the uncertainty of the results. One relevant solution is to provide exceedance curves based on simulations of the risk calculation (Macciotta et al., 2016; Jaboyedoff et al. 2021), as can be done with CAT models. Instead of performing a single calculation, up to 106 are performed with imputed viability based on different approaches such as observed distributions, standard probabilistic laws such as Poisson or uniform distribution, expert knowledge based on triangular distributions, etc. This can be done on the basis of a "deterministic calculation" of the risk, which allows a better assessment of the uncertainty of the risk.

Drawing upon a precedent risk calculation study within a road corridor, a novel risk calculation methodology is suggested, employing stochastic simulations to introduce variability across the parameters in the risk equation. The outcome manifests as an exceedance curve akin to those generated by catastrophe models. This approach systematically introduces uncertainty into the risk calculation, providing a simplistic means to address inadequately documented cases with limited data. This approach tends to minimise risk or call risk calculations into question.

 

References:

Jaboyedoff, M., Choanji, T., Derron, M.-H., Fei, L., Gutierrez, A., Loiotine, L., Noel, F., Sun, C., Wyser, E. & Wolff, C. 2021. Introducing Uncertainty in Risk Calculation along Roads Using a Simple Stochastic Approach. Geosciences, 11, doi: 10.3390/geosciences11030143.

Macciotta, R., Martin, C.D., Morgenstern, N.R. & Cruden, D.M. 2016. Quantitative risk assessment of slope hazards along a section of railway in the Canadian Cordillera—a methodology considering the uncertainty in the results. Landslides, 13, 115-127, doi: 10.1007/s10346-014-0551-4.

How to cite: Jaboyedoff, M.: Introducing uncertainty in hazard analysis in a simple way: example of rockfalls, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18131, https://doi.org/10.5194/egusphere-egu24-18131, 2024.

EGU24-20066 | ECS | Orals | NH3.5 | Highlight

Interdisciplinary insights into an exceptional giant tsunamigenic rockslide on September 16th 2023 in Northeast Greenland 

Kristian Svennevig, Stephen Hicks, Thomas Lecocq, Anne Mangeney, Clément Hibert, Niels Korsgaard, Antoine Lucas, Marie Keiding, Alexis Marboeuf, Sven Schippkus, Søren Rysgaard, Wieter Boone, Steven Gibbons, Kristen Cook, Sylfest Glimsdal, Finn Løvholt, Matteo Spagnolo, Jelle Assink, William Harcourt, and Jean-Philippe Malet and the VLPGreenland

On September 16th, 2023 at 12:35 UTC, a 25.5 M m3 rockslide occurred on the slope of Dickson Fjord in Northeast Greenland. The rockslide impacted a gully glacier, leading to a rock and ice avalanche that entered the fjord causing an up to 200 m high tsunami with observable runup up to 100 km away. The event produced an unprecedented very long period (VLP) seismic event observable on seismic stations worldwide for up to nine days. Here we focus on reconstructing the dynamics of the landslide, while detailed analysis of the VLP seismic signal is presented by Widmer-Schnidrig et al. in Session GM2.1.

Detailed analysis of the landslide reveals that a large body of metamorphic rock, with dimensions up to 150 m thick, 480 m wide, and 600 m long, dropped westwards along a foliation-parallel failure plane. The impact shattered a 200 m-wide outlet glacier, entraining 2.3 M m3 of glacier ice. The event was dynamically preconditioned by the progressive thinning of the glacier that supported the toe of the unstable slope. Subsequent investigations of satellite images and seismic records indicate that up to five minor landslides occurred in the years prior to the largest event in Sept. 2023, and one subsequent landslide has also been recorded.

Seismic signals generated by the landslide-tsunami were observed at nearby seismic stations, providing insights into its dynamics. The seismic signatures, including emergent high-frequency arrivals and low-frequency signals, match with characteristics of landslides involving glacial ice. Infrasound signals were also detected up to 3310 km away.

To reconstruct the landslide run-out, seismic waveforms from the closest stations were analyzed, resulting in a maximum force of 192×109 N, corresponding to a mass estimate of 78-103×109 kg, equating to a volume of ca. 29-38 M m3, consistent with results from photogrammetric reconstruction. The inverted run-out path indicates the initial rockslide impact with the gully wall, followed by entry into the water. The whole slide lasted c. 90 seconds. An independent numerical model to simulate the landslide force-history is in overall agreement with the seismic inversion results. Simulations of the landslide induced tsunami compare well with observations of the tsunami run-up, and also show evidence of longer lasting seiche action.

The landslide is the first glacial debuttressing landslide known from Greenland, and the first tsunamigenic landslide of this magnitude recorded in Northeast Greenland. 

How to cite: Svennevig, K., Hicks, S., Lecocq, T., Mangeney, A., Hibert, C., Korsgaard, N., Lucas, A., Keiding, M., Marboeuf, A., Schippkus, S., Rysgaard, S., Boone, W., Gibbons, S., Cook, K., Glimsdal, S., Løvholt, F., Spagnolo, M., Assink, J., Harcourt, W., and Malet, J.-P. and the VLPGreenland: Interdisciplinary insights into an exceptional giant tsunamigenic rockslide on September 16th 2023 in Northeast Greenland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20066, https://doi.org/10.5194/egusphere-egu24-20066, 2024.

EGU24-20256 | ECS | Posters virtual | NH3.5

Deciphering the force history of 2021 Chamoli rockslide 

Athul Palliath, Himangshu Paul, N Purnachandra Rao, and Venkatesh Vempati

Landslides are a significant hazard, particularly for those living in mountainous regions where the terrain is steep and unstable. Unfortunately, continuous monitoring of landslides is challenging due to their unpredictable nature. However, recent advancements in high-quality, dense broadband seismic networks have made it possible to study the spatial and temporal evolution of mass wasting processes through the analysis of seismic signals. The 2021 Chamoli rockslide which originated from a glaciated ridge of the Ronti Mountain in the western Himalaya caused severe damage to a hydropower project in downslope region and a casualty of about 80 people. CSIR-National Geophysical Research Institute established a regional seismic network in the Uttarakhand Himalaya which provides a great scope to understand this event in greater detail. We have performed dynamic inversion of the long period seismic waves generated by the rockslide to derive its force history. We used multistation data from Uttarakhand regional seismic network. We used IRIS syngine to generate Green’s function based on ak135 velocity model. Long period seismic waveforms from 6 stations within a distance of 80 km were chosen to perform inversion based on the signal to noise ratio and azimuthal coverage. The inversion is done using python package called lsforce. We reconstruct the force time history of the landslide, from the initial detachment of the rock mass to its impact on the ground. The peak upward vertical force corresponds to the detachment and peak downward vertical force corresponds its  the imapct  onto the ground. The result agrees with the centroid single force inversion done for the phases of detachment and impact of the landslide. The result obtained from force time history can be used to constrain parameters for the numerical simulation of the landslide to understand its dynamics in detail.  

How to cite: Palliath, A., Paul, H., Rao, N. P., and Vempati, V.: Deciphering the force history of 2021 Chamoli rockslide, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20256, https://doi.org/10.5194/egusphere-egu24-20256, 2024.

EGU24-22276 | Posters on site | NH3.5

Topographic changes in the high-altitude walls of the Mont Blanc massif: quantification at different spatial and temporal scales  

Daniel Uhlmann, Michel Jaboyedoff, Ludovic Ravanel, Joëlle Hélène Vicari, and Marc-Henri Derron

Long-term topographic changes at high altitude in the Alps, at different spatial and temporal scales, are challenging to quantify, often due to lack of direct evidence. Historic rockfalls are not always visually evident and their debris is frequently consumed by surrounding glaciers, and hanging glaciers leave no moraines to mark their evolution. Remote sensing techniques such as Light Detection and Ranging (LiDAR) have become powerful tools for precisely quantifying geomorphometric changes in the 21st century. However, rates of change based on the short time intervals of data produced since the advent of these modern techniques might not reflect longer-term trends. Especially considering the acceleration of Alpine zone erosion rates driven by cryospheric warming trends, extending the record towards the beginning of the 20th century can help resolve if the current rates are anomalous or consistent with the past. To extend the record of topographic changes of rock and glacier surfaces, Structure-from-Motion (SfM) photogrammetry techniques exploiting archival imagery can be used to create 3D models of past Alpine zone topography with which modern LiDAR can be combined to quantify longer-term rates of change. Combining archival SfM and recent LiDAR 3D models allows the estimation of historical erosion rates and glacier surface height change in the Mont-Blanc massif from the southeast face of Grand Pilier d’Angle (GPA; 4,243 m a.s.l.) from 1929-2021, the Brouillard Pillars (BP; 4150 m a.s.l.) from 1950-2021, the Aiguille du Midi (AdM; 3,842 m a.s.l.) from 1909-2022, and the Aiguille Verte (4,122 m a.s.l.) from 1932-2021. 1-year-interval LiDAR surveys of the GPA and AdM from 2020-2021 and 2021-2022, respectively, provide high-resolution erosion rates for a reference against the rates calculated with the SfM method. The GPA had erosion rates of 5.9±2.3mm year-1 and 8.5±0.1 mm year-1 for the 1929-2021 and 2020-2021 time-intervals, respectively. The BP had a rate of 1.0±0.39 mm year-1 for the period 1950-2022, and the AdM had a 16.4± 0.9 mm year-1 rate from 2021-2022. The 6 hanging glaciers of the AdM north face had an average surface height change of -9.39 m from 1909-2022. SfM models from archival photographs show an increase in the annual erosion rate of the GPA.

How to cite: Uhlmann, D., Jaboyedoff, M., Ravanel, L., Vicari, J. H., and Derron, M.-H.: Topographic changes in the high-altitude walls of the Mont Blanc massif: quantification at different spatial and temporal scales , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22276, https://doi.org/10.5194/egusphere-egu24-22276, 2024.

EGU24-22438 | Posters on site | NH3.5

The Steinsholtsjökull rockslide and GLOF in January 1967, South Iceland – a geophysical hazard likely to reoccur elsewhere in Iceland? 

Thorsteinn Saemundsson, Daniel Ben-Yehoshua, Greta Wells, Sinah Toscka, and Andrew J. Dugmore

This paper presents new estimates of the dimensions and impact of the 1967 Steinsholtshlaup in Iceland in order to understand better the event, the hazards it generated, its long-term legacy and the implications for both landscape interpretation and hazard planning in areas of contemporary valley glaciation. On 15th of January 1967 a major rockslide occurred on the northern face of the Innstihaus mountain in southern Iceland, which overlooked the valley glacier called Steinsholtsjökull. The slide occurred during intensive snowmelt, that followed heavy snow accumulation in December 1966. The landslide was a complex paraglacial response to decades of down wasting of Steinholtsjökull. Since the 19th century high stands of the Little Ice age in Iceland, Icelandic glaciers have probably lost about 16% of their mass. Warm conditions in the 1920s and 1930s drove rapid glacier retreat in southern Iceland and resulted in the formation of many pro-glacial lakes, one of which formed in front of Steinsholtsjökull as the terminus of the glacier retreated up valley and the surface down wasted.  The Innstihaus rockslide displaced the southern margin of the glacier and broke up a large amount of the glacier surface. The resulting down valley avalanche of rock incorporated glacier ice, swept into a proglacial lake and the confined pro-glacial valley of Steinsholtsdalur, creating a GLOF that left a trail of ice, rock debris and landscape transformation that entirely overprinted the pre-existing pro-glacial landscape. The Steinsholtsá river was displaced from the centre line of the valley to its southern margin. About 5km from the site of the cliff collapse, boulders up to 80m3 in size were scattered immediately beyond the confluence of the proglacial valley with a wider valley sandur. A paper published by Kjartansson in 1967 recorded the immediate aftermath of the GLOF, but left many questions unanswered, and there have been no subsequent publications. A better understanding of this event is important because, circumstances similar to those found in the Steinsholtsdalur valley prior to 1967 have developed in numerous glacial environments around Iceland’s ice caps.  As in many other montane areas, increased temperatures over the last thirty years have driven renewed and rapid retreat of valley glaciers. Across Iceland, existing proglacial lakes have expanded and many new ones have formed. These glacier fluctuations have affected the stability of neighbouring mountain slopes, which are resulting in slope deformation and mass movements. The potential for a major geomorphological incident in areas that both attract tourists year-round and have seen a recent related infrastructure development raises serious concerns and stresses an urgent need to study and monitor these environments.

How to cite: Saemundsson, T., Ben-Yehoshua, D., Wells, G., Toscka, S., and Dugmore, A. J.: The Steinsholtsjökull rockslide and GLOF in January 1967, South Iceland – a geophysical hazard likely to reoccur elsewhere in Iceland?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22438, https://doi.org/10.5194/egusphere-egu24-22438, 2024.

EGU24-1696 | Orals | NH3.6

The influence of rainfall patterns on shallow landslides in New Zealand 

Hugh Smith, Andrew Neverman, Harley Betts, and Raphael Spiekermann

Understanding how rainfall events influence the pattern and magnitude of landslide response is an important research focus from geomorphological and hazard planning perspectives. Few studies quantitatively relate spatial patterns in rainfall and landslides, largely due to difficulties in acquiring landslide inventories and data on rainfall patterns for individual storm events. Here, we aim to a) identify which factors most influence susceptibility to rapid shallow landslides at the event scale and b) assess how the spatial density of landslides varies in relation to rainfall. While we do not know precisely when individual landslides were triggered during an event, we can examine how the overall pattern of landslides varies spatially in relation to rainfall and geo-environmental factors.

Rapid landslides triggered by intense rainfall occur extensively in New Zealand’s hill country (land <1000 m in elevation with slopes generally between 20-30°). These landslides are typically shallow (approximately 1 m deep) and small (median source areas 50-100 m2). Past deforestation for pastoral farming accelerated landslide erosion. As a result, large rainfall events, such as Cyclone Gabrielle in February 2023, may trigger tens to hundreds of thousands of landslides, causing significant damage to land, infrastructure, and sites of cultural significance to Māori, as well as agricultural production losses and degradation of receiving environments from excess sediment.

In the present study, we focus on four large storm events that generated over 26,000 landslides across mostly hill country terrain on the North Island of New Zealand in 2017-18. High-resolution (0.5 m), before/after satellite imagery was used to map landslides within each study area. Ground-based weather radar data was processed to generate high-spatiotemporal-resolution gauge-calibrated rainfall grids and compute a) maximum intra-event intensities (30 min – 24-h), b) total event rainfall, and c) pre-event accumulations (10 – 90 days) that influence antecedent soil moisture. Rainfall variables were included alongside geo-environmental factors in a binary logistic regression model applied with automated variable selection using the least absolute shrinkage selection operator (LASSO) to assess the influence of different explanatory variables.

Land cover and slope most influenced landslide susceptibility ahead of intra-event rainfall intensities and pre-event rainfall accumulations. Of the rainfall variables, maximum 12-h rainfall normalised by the 10-y recurrence interval intensity and the 10-d pre-event accumulation normalised by mean annual rainfall had the most influence. Forest cover reduced the sensitivity of landslide spatial density to variations in slope, rainfall, and rock type, in contrast to pasture. Mean landslide density increased 3.5-fold once the maximum 12-h intensity exceeded the 10-y recurrence interval intensity by ≥25% for pastoral land on weak sedimentary rocks. This threshold is consistent with the increase in 12-h rainfall by late century under the highest levels of projected warming in New Zealand, which suggests the landslide response to storm rainfall could be significantly amplified by climate change.

How to cite: Smith, H., Neverman, A., Betts, H., and Spiekermann, R.: The influence of rainfall patterns on shallow landslides in New Zealand, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1696, https://doi.org/10.5194/egusphere-egu24-1696, 2024.

EGU24-2416 | Posters on site | NH3.6

Combined Effect of Wind and Rain on Typhoon-Induced Landslide 

Jui-Yun Hsieh and Yuan-Chien Lin

Landslides which cause numerous casualties and property losses are the crucial natural disaster in Taiwan. Traditionally, typhoon-induced landslides studies mainly focused on the triggering factors, such as geological condition, topographic condition and heavy rainfall. However, typhoons often bring sudden maximum wind which sways trees severely, leading to the soil disturbance which decreasing the slope stability. Moreover, some landslide events occurred on borad-leaved forest along the slopes where were only affected by strong winds of the typhoon and were not particularly affecte by heavy rainfall of the typhoon. In this study, data-driven approach is used to prove that strong winds is one of the important trigger factor, especially strong winds lasting for hours. We examed the significance of the combined rain-wind influence on landslides by Three-dimensional (3D) Histogram and Mann-Whitney U test. The results demonstrated that the wind and rain conditions when a typhoon landslide event occurs are both significantly greater than when no landslide event occurs. And a binary machine learning Random Forest model is constructed to predict the occurrences of landslides based on factors, such as heavy rain, strong winds, traditional geological conditions, and topographical factors. The findings of this study infer that  in addition to heavy rainfall, strong winds is also one of the important factor that may increase or trigger the risk of landslides. Therefore, strong winds can not be ignored when investigating the typhoon-induced landslides.

How to cite: Hsieh, J.-Y. and Lin, Y.-C.: Combined Effect of Wind and Rain on Typhoon-Induced Landslide, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2416, https://doi.org/10.5194/egusphere-egu24-2416, 2024.

EGU24-2680 | ECS | Orals | NH3.6

Understanding Delayed Landslides: A Study of 1,118 Fatal Incidents in China Influenced by Post-Precipitation Runoff 

Kanglin Wu, Alessandro Simoni, and Ningsheng Chen

The common understanding of landslides points to intense precipitation as a primary trigger. However, this explanation falters when considering landslides occurring with minimal or no rainfall, challenging the basis of empirical and numerical analyses. Taking advantage of a dataset documenting 1,118 landslide disasters with casualties in China since 1984, this study incorporates field investigations, laboratory experiments, and numerical simulations to unravel the mechanisms behind the delayed initiation of landslides influenced by post-precipitation runoff and infiltration. A noteworthy finding emerges: over 75% of catastrophic landslides in China exhibit a temporal delay compared to triggering rainfalls, typically manifesting within one week following peak precipitation. The temporal dynamics of precipitation-induced landslide delays show a range from months to hours, with the delay positively correlated to both landslide scale and the severity of regional drought. Spatially, delayed landslides are frequently related to runoff recharge by upstream catchment, playing a pivotal role in the initiation process. Consideration of topography, climate, and human activities leads to the identification of four typical runoff recharge patterns. We use such patterns to investigate the relationships with the upstream catchment area and delay time, influenced by surface runoff migration and supplied runoff infiltration. Hydrological and slope stability calculations underscore the significance of the catchment area to landslide area ratio while delay time is predominantly governed by surface runoff migration and supplied runoff infiltration into the sliding soil. Results unveil a consistent sequence: robust runoff recharge facilitates water infiltration into weak rock fractures or soil mass, resulting in a gradual increase of pore water pressure. This sequence culminates in the delay of landslide initiation compared to the peak precipitation. These findings may contribute to a scientific foundation for early warning and prediction related to such landslides, thereby mitigating associated risks.

How to cite: Wu, K., Simoni, A., and Chen, N.: Understanding Delayed Landslides: A Study of 1,118 Fatal Incidents in China Influenced by Post-Precipitation Runoff, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2680, https://doi.org/10.5194/egusphere-egu24-2680, 2024.

EGU24-4772 | ECS | Orals | NH3.6

A Comparison of SimCLR and SwAV Contrastive Self-Supervised Learning Models For Landslide Detection 

Hejar Shahabi, Omid Ghorbanzadeh, Saeid Homayouni, and Pedram Ghamisi

Deep Learning (DL) algorithms have demonstrated superior efficacy compared to traditional Machine Learning (ML) methods in the realm of landslide detection through the analysis of Remote Sensing (RS) imagery. However, their performance is notably contingent upon the quantity of manual annotations utilized during the training process. This investigation delves into the utilization of two distinct Self-Supervised Learning (SSL) models, specifically the Simple Framework for Contrastive Learning of Visual Representations (SimCLR) and Swapping Assignments between multiple Views (SwAV). These models were adapted and enhanced for downstream tasks, particularly in the domain of landslide detection. To train the SSL models, the Landslide4Sense competition dataset was employed, consisting of 3799 training patches, 245 validation patches, and 800 testing patches generated from Sentinel-2 images acquired from diverse regions worldwide. During the training of SimCLR and SwAV models, only the training patches were utilized, with a series of data augmentations applied to the input dataset based on each model's architecture. Both models employed ResNet-50 as the encoder.

For the downstream task of landslide detection, a custom U-Net model was developed. The trained ResNet-50 served as the encoder, and during fine-tuning, only the decoder part was permitted to be trained while the encoder remained frozen. During the fine-tuning process, subsets comprising 1% and 10% of labeled data from the training dataset were randomly selected to train the model, and predictions were exclusively conducted on the testing data. While a conventional supervised ResU-Net model, which was trained on all labeled training datasets, attained an F1 score of 72%, the SSL models achieved F1 scores of 64% and 71% with 1% labeled data, and 68% and 76% with 10% labeled data for SimCLR and SwAV, respectively. In addition, comparisons were conducted with all supervised reference models in the Landslide4Sense competition, revealing that SwAV, with 10% labeled data, outperformed all models, surpassing their top model by 4%. This study underscores the potential of SSL techniques in the segmentation and classification of RS images for natural hazard mapping, particularly in scenarios where labeled data is not available or is limited.

How to cite: Shahabi, H., Ghorbanzadeh, O., Homayouni, S., and Ghamisi, P.: A Comparison of SimCLR and SwAV Contrastive Self-Supervised Learning Models For Landslide Detection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4772, https://doi.org/10.5194/egusphere-egu24-4772, 2024.

EGU24-5116 | ECS | Posters on site | NH3.6

Estimating near-surface reduction in shear-strength on hillslopes caused by strong ground shaking 

Hakan Tanyas, Chuanjie Xi, Luigi Lombardo, Kun He, Xiewen Hu, and Randall Jibson

The weakening of hillslopes during strong earthquakes increases landsliding rates in post-seismic periods. However, very few studies have addressed the amount of coseismic reduction in shear strength of hillslope materials. This makes estimation of post-seismic landslide susceptibility challenging. Here we propose a method to quantify the maximum shear-strength reduction expected on seismically disturbed hillslopes. We focus on a subset of the area affected by the 2008 Mw 7.9 Wenchuan, China earthquake. We combine physical and data-driven modeling approaches. First, we back-analyze shear-strength reduction at locations where post-seismic landslides occurred. Second, we regress the estimated shear-strength reduction against peak ground acceleration, local relief, and topographic position index to extrapolate the shear-strength reduction over the entire study area. Our results show a maximum of 60%-75% reduction in near-surface shear strength over a peak ground acceleration range of 0.5-0.9 g. Reduction percentages can be generalized using a data-driven model.

How to cite: Tanyas, H., Xi, C., Lombardo, L., He, K., Hu, X., and Jibson, R.: Estimating near-surface reduction in shear-strength on hillslopes caused by strong ground shaking, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5116, https://doi.org/10.5194/egusphere-egu24-5116, 2024.

EGU24-5565 | ECS | Orals | NH3.6

A probabilistic model for slope stability analysis including the root reinforcement effects 

Sara Galeazzi, Luca Ciabatta, Luca Brocca, and Diana Salciarini

The presence of vegetation plays an important role in slope stability, especially in triggering of shallow landslides. It influences the mechanical and hydrological behaviour of soils, generating both stabilizing and destabilizing actions [1,2]. Variation in vegetation related to land use change can affect slope stability and can be evidenced in terms of variation of probability of failure.
In this study we implement a module for the calculation of root reinforcement in the slope stability physically-based probabilistic model PG_TRIGRS (Probabilistic, Geostatistic-based, TranSient Rainfall Infiltration and Grid-based Slope stability, [3]). Such model allows the wide-area assessment of the probability of rainfall-induced failure, considering the spatial variability of the soil properties treated as random variables. In this work, we apply the model to an area prone to landslides in Central Italy assuming the spatial variability of vegetation.
To investigate the influence of the spatial layout of plant roots on slope stability, the root reinforcement is implemented in the PG_TRIGRS probabilistic model. The considered root cohesion values  were derived from literature and were determined according to vegetation maps available for the study area. In addition, root cohesion variation is also considered along the vertical profile as a function of rooting depth. Finally, the resulting probability of failure distribution is compared to the results obtained for the bare soil with the absence of roots.


[1] Pollen-Bankhead, N., & Simon, A. (2010). Hydrologic and hydraulic effects of riparian root networks on streambank stability: Is mechanical root-reinforcement the whole story?. Geomorphology, 116(3-4), 353-362.
[2] Masi, E. B., Segoni, S., & Tofani, V. (2021). Root reinforcement in slope stability models: a review. Geosciences, 11(5), 212.
[3] Salciarini, D., Fanelli, G., & Tamagnini, C. (2017). A probabilistic model for rainfall—induced shallow landslide prediction at the regional scale. Landslides, 14, 1731-1746.

How to cite: Galeazzi, S., Ciabatta, L., Brocca, L., and Salciarini, D.: A probabilistic model for slope stability analysis including the root reinforcement effects, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5565, https://doi.org/10.5194/egusphere-egu24-5565, 2024.

EGU24-6201 | Orals | NH3.6

Deep learning forecast of rainfall-induced shallow landslides in Italy 

Fausto Guzzetti, Alessandro C. Mondini, and Massimo Melillo

Rainfall induced landslides occur in all mountain ranges posing severe threats to people, property, and the environment. Given the projected climate changes, in many areas the risk posed by rainfall induced landslides is expected to increase. For this reason, the ability to anticipate their occurrence is key for effective landslide risk reduction. Empirical rainfall thresholds and coupled slope-stability and rainfall infiltration models are commonly adopted to anticipate the short-term (from hours to days) occurrence of rainfall induced shallow landslides. However, empirical evidence suggests that they may not be effective for operational forecasting over large and very large areas. We proposed a deep learning based modelling strategy to link hourly rainfall measurements to landslide occurrence. We constructed a large ensemble of 2400 neural network models which we informed using hourly rainfall measurements taken by more than 2000 rain gauges and information on more than 2400 landslides in the period from February 2002 to December 2020 in Italy. Our results have indicated that (a) it is possible to effectively anticipate the occurrence of the rainfall induced shallow landslides in Italy, and (b) the location and timing of the rainfall-induced shallow landslides are controlled primarily by the precipitation. Our results open to the possibility of operational landslide forecasting in Italy, and possibly elsewhere, based on rainfall measurements and quantitative meteorological forecasts aided by deep learning based modelling.

How to cite: Guzzetti, F., Mondini, A. C., and Melillo, M.: Deep learning forecast of rainfall-induced shallow landslides in Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6201, https://doi.org/10.5194/egusphere-egu24-6201, 2024.

EGU24-6480 | ECS | Posters on site | NH3.6

A full probabilistic approach to landslide forecast 

Flavia Ferriero, Warner Marzocchi, Gianfranco Urciuoli, and Simone Mancini

Landslides are among the most destructive natural disasters that occur frequently worldwide, claiming lives and causing severe economic losses. The most common approaches for managing the short-term landslide risk is based on the definition of deterministic thresholds of a triggering event (a seismic quantity, or an amount of rain) above which the landslide is expected to occur. However, landslides, as well as most of natural events, is hardly predictable deterministically, owing to the unavoidable and ubiquitous presence of uncertainties of different kind. In this study, we present the first steps towards the development of a full probabilistic landslide forecasting model that accounts for the probabilistic forecasts of triggering events (such as earthquakes and/or rainfalls), and it includes a full appraisal of different kinds of uncertainty. Within a Bayesian mathematical framework, the model combines the probabilistic distribution of the mechanical parameters of the soil with the probability of observing a certain natural triggering event; the output is a space-time dependent probability of occurrence of landslides as a function of the probability of occurrence of their triggering event. In addition, we describe the landslide forecasts as a distribution of probability instead of one single value, to give a complete description of what we know and what we do not know. This approach provides a suitable scientific output that can be used by land use managers and decision-makers. Indeed, a formal probabilistic assessment fits more adequately the intrinsic non-deterministic nature of landslide occurrence. Moreover, it provides a more suitable framework that help defining  roles and responsibilities of all actors involved in the full risk reduction process.

How to cite: Ferriero, F., Marzocchi, W., Urciuoli, G., and Mancini, S.: A full probabilistic approach to landslide forecast, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6480, https://doi.org/10.5194/egusphere-egu24-6480, 2024.

EGU24-7275 | Orals | NH3.6

A fully operational IoT-based slope stability analysis for an unsaturated slope in Norway 

Luca Piciullo, Minu Treesa Abraham, Ida Norderhaug Drøsdal, Erling Singstad Paulsen, Vittoria Capobianco, and Håkon Heyerdahl

The framework proposed by Piciullo et al., 2022 for a Internet of Things (IoT)-based local landslide early warning system (Lo-LEWS) consists of four main components: monitoring, modelling, forecasting, and warning. It was applied to a steep natural slope in Norway, equipped with various hydrological and meteorological sensors since 2016. Volumetric water content (VWC) and pore-water pressure (PWP) sensors were installed in 2016 (Heyerdahl et al., 2018). A weather station was added in 2022 to measure climate variables: rainfall, relative humidity, wind speed, air temperature among others. The sensors and weather station regularly send data to NGIs IoT data platform (NGI Live), which stores and makes the data available real-time through online dashboards and Application Programming Interface (API). GeoStudio software was used to create a reliable digital twin of the slope with the aim of back-calculating the in-situ hydrological conditions. Calibration, climate variables, and vegetation proved crucial for accurately modelling the slope's response . Sensitivity analysis on hydraulic conductivity and permeability anisotropy improved input data and model fitting. The hydrological model adequately represented monitored conditions up to a 1-year period (Piciullo et al., 2022). 

A fully operational IoT-based slope stability analysis has been recently established. The digital twin model has been used to evaluate the slope stability (i.e., factor of safety, FS) coupling SEEP and Slope analyses for 5 different 1-year datasets. Both past and future scenarios have been considered:  2019-2020, 2021-2022, 2022-2023, 2064-2065, 2095-2096. The inputs (i.e., hydrological and weather variables) and the FS results have been used to train different machine learning and statistical models. The feature considered are VWC, PWP, rainfall, temperature, LAI; the target was the FS. The best models able to predict the FS, given the features, are polynomial regression and random forest.

In order to predict the FS for the upcoming three days, PASTAS model (Collenteur et al., 2019) and the Norwegian Meteorological Institute webpage have been used to respectively forecast the hydrological variables (i.e., VWC and PWP) and rainfall, air temperature and relative humidity data. We created a web service that once a day automatically (1) fetches measured data from NGI Live using the NGI Live API, (2) runs predictions for the next three days based on the measured data, (3) sends the predicted values back to NGI Live, making them available for real-time visualization in online dashboards. This case study can be seen as a fully operational example of the use of IoT and digital twinning to provide a real-time stability assessment for a slope as well as a collaborative effort among different expertise: geotechnical, hydrological, instrumental and informatics.  

REFERENCES

Heyerdahl H., et al. (2018). Slope instrumentation and unsaturated stability evaluation for steep natural slope close to railway line. In UNSAT 2018: The 7th International Conference on Unsaturated Soils.

Collenteur R. A., et al. (2019). Pastas: Open Source Software for the Analysis of Groundwater Time Series. Groundwater, 57(6):877–885. URL: https://doi.org/10.1111/gwat.12925, doi:10.1111/gwat.12925.

Piciullo, L., et al. (2022) A first step towards a IoT-based local early warning system for an unsaturated slope in Norway. Nat Hazards 114, 3377–3407 (2022). https://doi.org/10.1007/s11069-022-05524-3 

How to cite: Piciullo, L., Abraham, M. T., Drøsdal, I. N., Paulsen, E. S., Capobianco, V., and Heyerdahl, H.: A fully operational IoT-based slope stability analysis for an unsaturated slope in Norway, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7275, https://doi.org/10.5194/egusphere-egu24-7275, 2024.

EGU24-7330 | Orals | NH3.6

Determination and analysis of the rainfall triggering landslides in the ITALICA catalogue  

Silvia Peruccacci, Stefano Luigi Gariano, Massimo Melillo, Fausto Guzzetti, and Maria Teresa Brunetti

The wide physiographic variability and the abundance of rainfall and landslide data make Italy an appropriate site to study variations in the rainfall conditions responsible for triggering landslides.

For more than two decades, the Research Institute for Geo-Hydrological Protection of the Italian National Research Council (CNR-IRPI) has been carrying out a specific research activity aimed at collecting information on rainfall-induced landslides in Italy. The information comes mainly from chronicle sources (newspapers in print or electronic format, websites, etc.) and institutional sources (reports on interventions carried out by the Fire Brigade and other institutional entities following reports of weather-induced landslides). The information collected has been used to compile the ITAlian rainfall-induced LandslIdes CAtalogue (ITALICA), freely accessible at https://zenodo.org/records/8009366. A description of the main features of the catalogue and the procedures adopted to fill it out can be found at https://essd.copernicus.org/articles/15/2863/2023/.

ITALICA, which is being continuously updated, to date contains data on more than 6300 rainfall-induced landslides that occurred in Italy during the period 1996-2021. The peculiarity and specificity of the catalogue lies in the mastery and control of the landslide records, which have very high levels of spatial and temporal accuracy. In particular, for more than one third of the catalogue, landslides are spatially and temporally localized with an uncertainty of less than one km2 and one hour, respectively. The availability of accurate and up-to-date information on the geographic location and time of onset of landslides is essential for improving the predictive ability of landslides. Different subsets of the catalogue have been already used to calculate national and regional rainfall thresholds implemented in early warning systems in Italy.

The first published version of ITALICA did not contain information on the rainfall conditions associated with the landslides. In the new release, presented here, we add the cumulate rainfall, rainfall duration and mean rainfall intensity values of the rainfall conditions responsible for the failures listed in the catalogue. The rainfall conditions are reconstructed by means of the CTRL-T automatic tool (https://zenodo.org/records/4533719) and using hourly rainfall measurements from more than 3000 rain gauges distributed over the Italian territory. Rainfall records are provided by the Italian National Department for Civil Protection. The spatial and temporal features of the reconstructed landslide-triggering rainfall conditions are analysed in depth.

Given the rising demand for high-quality data to be used in comprehensive analyses and data-driven models, this dataset might be very useful for assessing the rainfall triggering conditions of landslides in Italy, either by empirical or physically based models. In particular, we expect our results to have an impact on the definition of new rainfall thresholds to be implemented in landslide early warning systems at regional and national scales.

 

Work financially supported by the Italian National Department for Civil Protection (Accordo di Collaborazione 2022-2024) and the PRIN-ITALERT project (PRIN2022 call, grant number: 202248MN7N, funded by NextGenerationEU).

How to cite: Peruccacci, S., Gariano, S. L., Melillo, M., Guzzetti, F., and Brunetti, M. T.: Determination and analysis of the rainfall triggering landslides in the ITALICA catalogue , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7330, https://doi.org/10.5194/egusphere-egu24-7330, 2024.

EGU24-7357 | ECS | Orals | NH3.6

Machine learning-based landslide susceptibility mapping for short-term risk assessment in South Korea 

Sujong Lee, Minwoo Roh, Uichan Kim, and Woo-Kyun Lee

Climate change impacts the frequency and intensity of extreme weather events, leading to an increase in natural disasters globally. Heavy rainfall is a notable extreme weather event, acting as an external factor for landslides. In South Korea, where approximately 70% of the terrain is mountainous, the susceptibility to landslides is high. Despite the development and implementation of landslide early warning systems by the Korea Forest Service for local governments, the extent of landslide damage has been significant, reaching approximately 2,345 hectares in the last five years. Especially, last year, landslides occurred more than 800 times with severe human costs. The current early warning system, which focuses on administrative boundaries, has limitations in accurately identifying high-vulnerability landslide areas. To address this issue, this study introduces a landslide diagnostic model designed to assess the daily susceptibility of South Korea with fine spatial resolution. The model employs a semi-automated process that encompasses the acquisition of short-term climate forecast data and the generation of daily landslide susceptibility maps. The core algorithm of the model is based on the random forest method, predicting susceptibility at a spatial resolution of 100 meters. The model integrates various feature datasets, including meteorological, topographic, and land surface data, which are closely linked to landslide occurrences. The training model utilized landslide inventory data from 2016 to 2022, with various performance indicators employed for calibration and validation. Additionally, the landslide inventory data from 2023 was utilized for final model verification. Notably, the model incorporates a 3-day climate forecast data process provided by the Korea Meteorological Administration, enabling the prediction of short-term daily landslide susceptibility. This landslide diagnostic model holds the potential to enhance landslide prevention and preparedness at both local and regional scales.

How to cite: Lee, S., Roh, M., Kim, U., and Lee, W.-K.: Machine learning-based landslide susceptibility mapping for short-term risk assessment in South Korea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7357, https://doi.org/10.5194/egusphere-egu24-7357, 2024.

EGU24-8845 | ECS | Posters on site | NH3.6

Combining meteorological and soil wetness information in machine learning modelling for landslide early warning 

Tobias Halter, Peter Lehmann, Alexander Bast, Jordan Aaron, and Manfred Stähli

Shallow landslides triggered by intense rainfall events pose a serious threat to people and infrastructure in mountainous areas. Regional landslide early warning systems (LEWS) have proven to be a cost-efficient tool for informing the public about the imminent landslide danger. These LEWS are often based on the statistical relationship between rainfall characteristics and landslide inventory information. Previous studies in Switzerland have demonstrated that periods of increased landslide danger are correlated with relative changes in volumetric water content measured at soil moisture stations across the country. In this study, we combine such soil moisture information (including soil water potential) with meteorological data to establish dynamic thresholds for the prediction of landslide probability in both time and space. We train a random forest classifier to separate between critical and non-critical rainfall events. The models are trained and tested on data measured at 136 locations across the entire country during the period from 2008 to 2023. Our trained algorithm allows us to quantify (1) the importance of different climate and soil wetness variables and (2) the benefits of integrating soil wetness and meteorological information within LEWS. We are confident that this study will improve the accuracy and reliability of landslide forecasting at a national scale and contribute to improved landslide risk management in areas with steep slopes.

How to cite: Halter, T., Lehmann, P., Bast, A., Aaron, J., and Stähli, M.: Combining meteorological and soil wetness information in machine learning modelling for landslide early warning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8845, https://doi.org/10.5194/egusphere-egu24-8845, 2024.

EGU24-9311 | ECS | Posters on site | NH3.6

Temporal and spatial analysis of landslide-triggering rainfall conditions in Qinghai-Tibet Plateau, China 

Kezhen Yao, Stefano Luigi Gariano, and Saini Yang

Landslide on the Qinghai-Tibet Plateau (QTP) is expected to be more affected by climate change due to the sensitivity of this unique climatic and geomorphological area to variations in temperature and precipitation. As an important response signal to climate change, a systematic framework for the assessment of landslide hazard and risk in QTP is necessary to investigate the potential impacts of climate change on landslides and related exposures.

The study aims to establish an integrated model that synthesizes spatial and temporal landslide prediction, using statistical analysis, machine learning, and quantitative methods. The temporal landslide prediction is made by means of empirical rainfall thresholds, based on satellite rainfall estimates, whose feasibility for defining landslide-triggering rainfall thresholds was proved by several studies.

A well-documented hazard database of the QTP provided by the China Geological Survey (4519 records from 2001 to 2022) indicates that landslides occurred here are mostly induced by rainfall from April to October, with an obvious seasonal characteristic, resulting in fatalities, damage, and affected population. According to the database, 3542 landslides are associated to a rainfall trigger. Based on the satellite-based rainfall product of CHIRPS (Climate Hazards Group InfraRed Precipitation with Station data, version 2.0 final) daily data, we find that the rainfall of the occurrence day and the antecedent rainfall over the seven days before the landslides are significant indicators for the rainfall induced hazard. Using the frequentist method, the event duration-cumulated event rainfall (ED) thresholds at different non-exceedance probabilities for landslide triggering are calculated for the whole QTP area and for different environmental subdivisions within it. The thresholds show a robust definition with low parameter uncertainty. This is the first attempt to define empirical rainfall thresholds for landslide occurrence specifically for the QTP.

Given the long-term of the used database, temporal and spatial analyses are conducted, to search for variations in the rainfall triggering conditions according to landslide locations and time of occurrence. Variations in the seasonal distribution and in the annual trends (using 5-year moving windows from 2007 to 2002) are evaluated. The impact of variations in rainfall patterns due to climate change making the landscape of the QTP more prone to landslides during the recent-most ten years is demonstrated by the gradual change of thresholds with lower intercepts and slopes. That means, for a certain rainfall duration, there is a tendency of lower rainfall threshold to trigger a landslide.

The thresholds here defined are further combined with landslide susceptibility map based on Random Forest to derive a landslide hazard map for the interested area.

How to cite: Yao, K., Gariano, S. L., and Yang, S.: Temporal and spatial analysis of landslide-triggering rainfall conditions in Qinghai-Tibet Plateau, China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9311, https://doi.org/10.5194/egusphere-egu24-9311, 2024.

Landslides are complex and dynamic natural hazards that require a comprehensive understanding of their temporal changes for effective assessment and management. Traditional landslide inventories often focus on static analysis, providing a snapshot of landslide occurrences at a specific point in time. However, to capture the dynamic nature of landslides and assess their evolution over time, multi-temporal inventories are essential. This study aims to go beyond static analysis by proposing the use of multi-temporal inventories for dynamic landslide assessment. The approach involves the integration of remote sensing data, advanced modeling techniques, and deep learning algorithms to analyze and map landslides over multiple time periods. By considering the temporal dimension, the proposed method enables the identification of changes in landslide patterns, movements, and susceptibility over time. We used orthophotos retrieved from WMS and WMTS services provided by the Italian national portal, covering the period from 1989 to 2021, for a study conducted in the Cordevole and Alpago areas (Belluno province, NE Italian Alps). These areas were impacted by two extreme meteorological events (return period > 100 years) in 2018 (October 27th–30th) and 2020 (December 4th–6th). The first, known as windstorm VAIA, has induced severe damage to the forest cover. The generated multi-temporal inventories provide valuable information for understanding the temporal dynamics of landslides, which is crucial for accurate landslide hazard assessment and risk management. The findings of this study highlight the importance of incorporating multi-temporal inventories into landslide assessment methodologies to enhance our understanding of landslide behavior and improve decision-making processes.

Acknowledgement:

This study was carried out within the PNRR research activities of the consortium iNEST (Interconnected North-Est Innovation Ecosystem) funded by the European Union Next-Generation EU (Piano Nazionale diRipresa e Resilienza (PNRR) – Missione 4 Componente 2, Investimento 1.5 – D.D. 1058 23/06/2022, ECS_00000043). This manuscript reflects only the Authors’ views and opinions; neither the European Union nor the European Commission can be considered responsible for them.

How to cite: Bhookya, R. and Floris, M.: Beyond Static Analysis: Importance of Multi-Temporal Inventories in Alpine Environments for Dynamic Landslide Assessment in Belluno Province (Veneto Region, NE, Italy). , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9898, https://doi.org/10.5194/egusphere-egu24-9898, 2024.

EGU24-10552 | Posters on site | NH3.6

Development of a data-driven space-time model to predict precipitation-induced geomorphic impact events at the Alpine Scale 

Raphael Spiekermann, Sebastian Lehner, Stefan Steger, Mateo Moreno, Katharina Enigl, Dominik Imgrüth, Matthias Schlögl, and Georg Pistotnik

Extreme hydro-meteorological impact events are difficult to predict in space and time as they frequently result from localised, high-intensity convective precipitation events. Societal impacts can occur when extreme precipitation events interact with multiple other geomorpholocial, hydrological and societal predisposing and preparatory factors. Due to limitations in spatial and temporal resolution, it is assumed that climate models likely underestimate the magnitude and frequency of future extreme precipitation events (Slingo et al., 2022).

In the context of disaster risk reduction, it is important to understand the relationships between the multiple driving factors of geomorphic high impact events. Knowing when and where potential adverse consequences are likely to occur and under which conditions can support the design and provision of risk reduction measures (e.g., impact-based forecasts and warnings). Moreover, impact models can inform on likely changes in the frequency of extreme events under future climate regimes.

We address this problem by developing a data-driven machine-learning model aimed at predicting the likelihood of past and future weather extremes that cause societal impacts. Using a risk framework as a conceptual underpinning, a stratified space-time modelling approach is implemented, sampling from combined landslide, debris-flow and rock-fall damage inventories across Austria and South Tyrol (Italy) spanning the period 2005-2022. Building on previous method developments (Steger et al., 2023), multiple meteorological indicators available at different spatial scales, including a sub-model used to predict the likelihood of deep convective events, are combined with morphometric, geological, hydrological, land cover data as well as data on potentially exposed assets to train a hierarchical generalised additive mixed model (GAMM) on the basis of slope units. The modelling results are evaluated through multiple perspectives using variable importance assessment, spatial and temporal cross-validation procedures as well as qualitative plausibility checks.

We present first model results, showing the importance of simultaneously considering spatio-temporal variations in hazard components as well as exposure data to predict localised impact events. Further strengths, opportunities and limitations of the approach are discussed. The research leading to these results has received funding from Interreg Alpine Space Program 2021-27 under the project number ASP0100101, “How to adapt to changing weather eXtremes and associated compound and cascading RISKs in the context of Climate Change” (X-RISK-CC).

References

  • Slingo, J., Bates, P., Bauer, P. et al. Ambitious partnership needed for reliable climate prediction. Nat. Clim. Chang. 12, 499–503 (2022). https://doi.org/10.1038/s41558-022-01384-8.
  • Steger, S., Moreno, M., Crespi, A., Zellner, P., Gariano, S.L., Brunetti, M., Melillo, M., Peruccacci, S., Marra, F., Kohrs, R., Goetz, J., Mair, V. & Pittore, M. Deciphering seasonal effects of triggering and preparatory precipitation for improved shallow landslide prediction using generalized additive mixed models. Natural Hazards and Earth System Sciences. 23, 1483–1506 (2023). https://doi.org/10.5194/nhess-23-1483-2023.

How to cite: Spiekermann, R., Lehner, S., Steger, S., Moreno, M., Enigl, K., Imgrüth, D., Schlögl, M., and Pistotnik, G.: Development of a data-driven space-time model to predict precipitation-induced geomorphic impact events at the Alpine Scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10552, https://doi.org/10.5194/egusphere-egu24-10552, 2024.

EGU24-10593 | ECS | Orals | NH3.6

Analyses of slow-moving landslides interacting with the road network: case studies in Basilicata region (southern Italy) 

Gaetano Pecoraro, Gianfranco Nicodemo, Rosa Menichini, Davide Luongo, Dario Peduto, and Michele Calvello

Road infrastructure plays a key role in the economic development of a society. Thus, ensuring its functionality and safety conditions over time is a crucial and, at the same time, a demanding task that central and local authorities are asked to address. In Italy, road networks often develop within complex geological contexts, where active slow-moving landslides may generate risks to traveling persons and to the roads themselves, the latter being associated with socio-economic impacts. The identification of the road sections most exposed to landslide risk is critical for reducing the population potentially exposed to risk and for minimizing the repair/replacement costs. However, studies specifically oriented to roads affected by existing slow-moving landslides are quite rare in the scientific literature. This is possibly due to different reasons: landslide inventories with reliable information on the past and current state of activity of the phenomena are often not available; assessing the temporal probability of landslides characterized by a given intensity over large areas is not straightforward; the development of large datasets of road displacements and damage through traditional techniques can be time-consuming and sometimes not affordable.

This study proposes a conceptual model aimed at classifying the level of exposure to slow-moving landslide risk of stretches of roads at municipal scale. The activities have been developed in the context of the “Mitigation of natural risks to ensure safety and mobility in mountain areas of Southern Italy” (MitiGO) project.  Adopting a matrix-based approach, the following data are combined: landslide inventories, thematic information, displacement measurements derived from the interferometric processing of synthetic aperture radar images (DInSAR) and damage records obtained from Google Street View. First, a statistical model based on the bivariate correlations between the independent variables (i.e., each significant spatial variable derived from the thematic maps) and the dependent variable (i.e., the slow-moving landslides inventoried in the official map) is applied for zoning the susceptibility to slow-moving landslides at the municipal scale. Then, the information is combined with the level of damage and a monitored rate of movement based on DInSAR-derived ground-displacement measurements along the road network. The output is a correlation matrix combining all the information and classifying each stretch of the road network.

The proposed procedure has been applied to different access routes from a major regional road, the SS407 Basentana highway, to some urban centers of municipalities located in the Basento river basin (Basilicata region, southern Italy).

The analyses carried out at a municipal scale allow the classification of the road stretches potentially exposed to slow-moving landslide risk adopting a fairly simple qualitative ranking procedure, reliable in relation to the scale of analysis, which is based on a few data that are relatively easy to retrieve and to manage. The obtained results can be used to support studies of road networks over large areas aimed at the prioritization of risk-mitigation measures, as well as at the identification of road sections requiring further geomorphological surveys and geotechnical analyses, to be conducted in more detail at a larger scale.

How to cite: Pecoraro, G., Nicodemo, G., Menichini, R., Luongo, D., Peduto, D., and Calvello, M.: Analyses of slow-moving landslides interacting with the road network: case studies in Basilicata region (southern Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10593, https://doi.org/10.5194/egusphere-egu24-10593, 2024.

EGU24-10837 | ECS | Orals | NH3.6

Comparative analysis of conventional and machine learning techniques for rainfall threshold evaluation under complex geological conditions 

Nicola Dal Seno, Davide Evangelista, Elena Piccolomini, and Matteo Berti

The Emilia-Romagna Region in Italy faces significant challenges due to landslide hazards. With over 80,000 landslides identified in its mountainous regions, some areas see more than a quarter of their land impacted. Despite the generally slow nature of these landslides, they pose a considerable economic burden. For instance, in 2019, the region allocated 1 million euros for immediate safety measures, and it's estimated that an additional 80 million euros are needed to complete safety plans. This makes Emilia-Romagna one of the most landslide-prone areas globally. Factors like the region's geological makeup, increased land use, and climate change are exacerbating the issue. It's becoming evident that emergency measures alone are insufficient, and proactive prevention strategies are essential. Key efforts include better forecasting of rain-induced slope instabilities and predicting reactivations of dormant landslides and new failures. However, the unpredictable nature of landslides makes these goals challenging.

The primary aim of this study is to create AI models to predict landslides in Emilia-Romagna, leveraging 75 years of data collected by the University of Bologna in partnership with the Regional Agency for Civil Protection and the Geological Survey of Emilia-Romagna. Various methods like Bayesian analysis, Neural Networks, XGBoost, TPOT, Random Forest, LDA, QDA, and Linear Regression have been employed. The findings suggest that landslides in this region are primarily driven by rainfall during the event and its location, while prior rainfall seems less critical. The research also found that after a dry summer, a rainfall event of 90-100 mm is typically needed to trigger a landslide, a threshold that decreases later in the year. The best algorithm had an F2 score test result of 0.6, meaning it could correctly predict a true positive (rainfall causing landslide) every 3 positive instances and correctly predict a true negative (rainfall not causing landslide) 95.5% of the time.

How to cite: Dal Seno, N., Evangelista, D., Piccolomini, E., and Berti, M.: Comparative analysis of conventional and machine learning techniques for rainfall threshold evaluation under complex geological conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10837, https://doi.org/10.5194/egusphere-egu24-10837, 2024.

EGU24-11180 | ECS | Posters on site | NH3.6

Identifying Heterogeneous Landslides using Multi-modal Deep Learning 

Xiaochuan Tang, Xuanmei Fan, and Filippo Catani

Automated detection of landslides is an important part of geohazard prevention. In dense vegetation covered area, identifying landslides is a challenging problem. Various types of landslide monitoring technologies have generated heterogeneous data, such as optical imagery, SAR imagery, and LiDAR point clouds. Different types of landslide monitoring methods have their advantages and drawbacks. An ideal landslide detection model should utilize their advantages. However, the complementary information of multi-source landslide monitoring data has not been fully understood. To deal with this problem, we study how to use multi-source data for developing better landslide detection models. First, a multi-modal deep learning model is introduced for landslide detection using multi-source landslide monitoring data. Second, representation learning networks are proposed for extracting landslide detection features from optical imagery and LiDAR-derived data. In addition, an attention-based data fusion network is proposed for merging the feature maps of different data sources. Finally, to improve the explainability of the proposed neural network, a new loss function with domain knowledge constrains is proposed. The proposed multi-modal deep learning method is compared with the existing machine learning-based landslide detection methods. Experimental results demonstrated that the proposed method outperformed the state-of-the-art landslide detection methods, and is able to simultaneously identify earthquake-triggered new landslides and forest-covered ancient landslides. The reason is that optical imagery is appropriate for identifying new landslides, while LiDAR-derived data is able to remove forest cover and suitable for identifying ancient landslides. It can be seen that the complementary information of multi-source data is helpful for improving the performance of landslide detection.

How to cite: Tang, X., Fan, X., and Catani, F.: Identifying Heterogeneous Landslides using Multi-modal Deep Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11180, https://doi.org/10.5194/egusphere-egu24-11180, 2024.

EGU24-12097 | Orals | NH3.6

A deep Learning-based approach for landslide dating from time-series of SAR data 

Wandi Wang, Mahdi Motagh, Zhuge Xia, Simon Plank, Zhe Li, Aiym Orynbaikyzy, Chao Zhou, and Sigrid Roessner

Landslides are a serious geologic hazard common to many countries around the world.  They can result in fatalities and the destruction of infrastructure, buildings, roads, and electrical equipment. Especially rapid-moving landslides, which occur suddenly and travel at high speeds for miles, can pose a serious threat to life and property. Landslide inventories are essential to understand the evolution of landscapes, and to ascertain landslide susceptibility and hazard, and it can be of help for any further hazard and risk analysis. Although  many landslides inventories have already been created worldwide, often these archives of historical landslide events  lack precise information on the date of landslide occurrence. Many of these inventories also lack completeness especially in case of smaller landslides which is also caused by  landslides erosion processes, human impact, and vegetation  regrowth. Precise determination of landslide occurrence time is a big challenge in  landslide research. Optical and Synthetic Aperture Radar (SAR) images with multi-spectral and textural features, multi-temporal revisit rates, and large area coverage provide opportunities for landslide detection and mapping. Landslide-prone regions are frequently obscured by cloud cover, limiting the utility of optical imagery. The capacity of SAR sensors to penetrate clouds allows the use of SAR satellite data to provide a more precise temporal characterization of the occurrence of landslides on a regional scale. The archived Copernicus Sentinel-1 satellite, which has a 6 to 12-day revisit period and covers the majority of the world's landmass, allows for more precise identification of landslide failure timings. The time-series of SAR amplitude, interferometric coherence, and polarimetric features (alpha and entropy) have strong responses to landslide failures in vegetated regions. This is characterized by a sudden increase or decrease in their values. Consequently, the abrupt shifts in the time-series of SAR-derived parameters, triggered by the failure, can be recognized and regarded as the failure occurrence time. The aim of this study is to determine the time period of failure occurrences by automatically detecting abrupt changes in the time series of SAR-derived parameters. We present a strategy for anomaly detection in time-series based on deep-learning to identify the failure time using four parameters derived from SAR time series. In this strategy, we introduce a gated relative position bias to an unsupervised Transformer model to detect anomalies in a multivariate time-series composed of four SAR-derived parameters. We conduct an experiment involving multiple landslides and compare the performance of our proposed strategy for detection of the failure time period with that of the LSTM model. Our strategy successfully identifies the time of landslide failure, which closely approximates the actual time of occurrence when compared to the LSTM model employed in this study.

How to cite: Wang, W., Motagh, M., Xia, Z., Plank, S., Li, Z., Orynbaikyzy, A., Zhou, C., and Roessner, S.: A deep Learning-based approach for landslide dating from time-series of SAR data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12097, https://doi.org/10.5194/egusphere-egu24-12097, 2024.

EGU24-13892 | ECS | Posters on site | NH3.6

Forecasting of rainfall-induced landslides in pyroclastic soil deposits through hydrometeorological information. 

Abdullah Abdullah, Pasquale Marino, Daniel Camilo Roman Quintero, and Roberto Greco

Shallow landslides pose a major geohazard impacting mountainous regions all around the world, and wide slope areas in Campania (southern Italy) covered by loose granular deposits overlapping a karstic bedrock are known for hosting the most destructive landslides of the region in the last decades. The landslide triggering factor in this case is clearly the rainfall. Nonetheless, there are concurring causes linked to the hydrological conditions predisposing slopes to failure (Bogaard and Greco, 2016). In the present study, the landslide-inducing factors are divided in static and dynamic (Moreno et al., 2023). The static factors (e.g., topography, slope, forest ratio) are well investigated in numerous studies on landslide susceptibility assessment. However, the modelling of dynamics factors (e.g., rainfall, soil moisture) is a relatively new issue and has been addressed only in few studies. In this study, Generalized Additive Models (GAMs) were applied for spaciotemporal data-based modelling of landslide prediction for eleven years (2010-2020). The study area is located on the Sarno and Partenio mountains in Campania where pyroclastic soil deposits cover about 370 km2 of carbonate massifs. In a first step, the modelling of static components, controlling landslide susceptibility in the area, was carried out by utilizing the historical data of landslide events along with other factors (slope, forest ratio etc.,) significantly affecting the static probability of landslide occurrence. Afterwards, the dynamic component was modelled by considering the triggering rainfall and the antecedent soil moisture for landslide events. The soil moisture data was taken from ERA5-Land soil moisture product. Lastly, the static and dynamic components were integrated to model the dynamic probability of landslide occurrence. A cross-validation technique was used for model training. The novel integrated model approach showed trustworthy improvements in the assessment of the probability of landslide. The model was also successfully tested for different rainfall events reproducing the landslide triggering conditions in the study area.

How to cite: Abdullah, A., Marino, P., Roman Quintero, D. C., and Greco, R.: Forecasting of rainfall-induced landslides in pyroclastic soil deposits through hydrometeorological information., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13892, https://doi.org/10.5194/egusphere-egu24-13892, 2024.

EGU24-14020 | ECS | Orals | NH3.6

Evaluating Landslide Susceptibility on the Big Sur Coast, California, USA using Complex Network Theory 

Vrinda D. Desai, Alexander L. Handwerger, and Karen E. Daniels

As a result of extreme weather conditions such as heavy precipitation, natural slopes can fail dramatically. While the pre-failure deformation is sometimes apparent in retrospect, it remains challenging to predict the sudden transition from gradual deformation to runaway acceleration. Recent advancements in remote sensing techniques, like satellite radar interferometry (InSAR), enable high spatial and temporal resolution measurements of deformation and topographic information, providing valuable insights into landslide detection and activity. 

Landslides are common on the Big Sur coast, Central California, USA due to active tectonics, mechanically weak rocks, and high seasonal precipitation. We use satellite InSAR data from Copernicus Sentinel-1A/B to identify 23 active landslides within our 175 km2 study site; one is Mud Creek, a slow-moving, deep-seated landslide that catastrophically failed in May 2017 and another is Paul’s Slide, which has experienced nearly constant motion for decades. 

We use multilayer networks to investigate the spatiotemporal patterns of slow deformation on the 23 active landslides. In our analysis, we transform observations of the study site — ground surface displacement (InSAR) and topographic slope (digital elevation model) — into a spatially-embedded multilayer network in which each layer represents a sequential data acquisition period. We use community detection, which identifies strongly-correlated clusters of nodes, to identify patterns of instability. We have previously shown [Desai et al., Physical Review E, 2023] that using high-quality data containing information about the fluidity (via velocity as a proxy) and susceptibility (slope) of the area successfully forecasts the transition of the Mud Creek landslide — the only formally slow-moving landslide in this collection to have catastrophically collapsed — from stable to unstable. 

Using multivariate analysis, we compare the traits of the active landslides, such as precipitation, vegetation, deformation, topography, NDVI, and radar coherence, against the results of the community detection. A strong indicator of instability is a combination of poor InSAR coherence and high displacement. Combined with community detection, we are able to differentiate between creeping landslides that are stable and landslides that display concerning trends that may warn of catastrophic failure.

How to cite: Desai, V. D., Handwerger, A. L., and Daniels, K. E.: Evaluating Landslide Susceptibility on the Big Sur Coast, California, USA using Complex Network Theory, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14020, https://doi.org/10.5194/egusphere-egu24-14020, 2024.

EGU24-14188 | ECS | Posters virtual | NH3.6

A Non-Stationary Approach for Temporal Probability of Landslide using Hydrometeorological Thresholds 

Shamla Dilama Shamsudeen and Adarsh Sankaran

Landslides are one of the natural hazards that endanger life and property. Landslide research emphasises prediction based on the probability of triggering factors such as rainfall for use in early warning systems, and has implications for effective risk mitigation. Recent studies have focused on the probability of a landslide occurrence depending on hydrological factors such as soil moisture. The objective of the current study is to determine the temporal probability of landslide occurrence in a non-stationary framework using hydrometeorological parameters such as soil moisture and rainfall. The study was conducted in the Wayanad district of Kerala, India and area was divided into different zones inorder to account the spatial variation of rainfall and the topographical influence on the soil moisture. The non-stationary temporal probability estimation was performed using the generalised extreme value analysis. The hydrometeorological parameters, gridded rainfall and soil moisture data collected over a 42-year period (1981–2021), were analysed for the non-stationarity characteristics using the statistical tests for trend detection and Pettit test for the change point analysis. A monotonical trend in non-stationarity of the parameters were observed in the different regions of Wayanad. The temporal probability estimation for the future time periods was performed using the bias corrected GCM data and the landslide inventory data. The results showed that the exceedance probability of soil moisture based on the covariates improves the temporal probability of landslides when compared to the rainfall-based approach. The study is a novel and effective method for improving landslide prediction based on hydrological and meteorological factors under changing climate conditions, and for incorporating the same in early warning systems.

How to cite: Dilama Shamsudeen, S. and Sankaran, A.: A Non-Stationary Approach for Temporal Probability of Landslide using Hydrometeorological Thresholds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14188, https://doi.org/10.5194/egusphere-egu24-14188, 2024.

EGU24-14949 | Posters on site | NH3.6

Modeling the impact of Hurricane Maria on Puerto Rico with an eco-hydrological landslide model 

Elisa Arnone, Evren M. Soylu, Furuya Takahiro, and Rafael L. Bras

This study proposes an advanced hydrologic/landslide modeling application to assess the spatial distribution of rainfall-induced landslides for a sub-basin in central Puerto Rico. The framework implements a stability component into a spatially distributed physically-based hydrological model coupled to a model of plant physiology. Puerto Rico is an ideal study site to assess the performance of landslide modeling efforts due to the availability of thousands of catalogued landslides triggered by Hurricane Maria (HMA) during September 19-22, 2017. The main objective of the study is to simulate the observed landslide events forcing a coupled eco-hydrological-stability model, the tRIBS-VEGGIE-Landslide, with weather data of HMA. The tRIBS-VEGGIE-Landslide model has the advantage of accounting for the vegetation dynamics that affect the soil moisture patterns at an hourly scale and for the soil-water characteristic curve and the saturated shear strength parameters (cohesion and friction angle) to assess the factor of safety (FS) in space and time, using an infinite slope model.

The modeling application focuses on two small sub-basins of the Rio Saliente watershed, each smaller than 1 km2. The small study area allows for the use of a 5m DEM resolution topography, which has been derived from a 1m resolution LiDAR measurements. Since many radar and ground stations were destroyed during the hurricane, the hourly time series of the HMA event has been reconstructed by using the NCEP (National Centers for Environmental Prediction) – Environmental Modeling Center (EMC) gridded Stage IV data, produced by NOAA National Weather Service. The precipitation data resulted in a maximum hourly intensity of 64.52 mm/hr, maximum daily intensity of 294.56 mm/day, and rainfall total of 332.15 mm, consistent with other daily reconstructions. Preliminary results demonstrate the importance of the spatial computational mesh and accurate characterization of soil parameters, which play an essential role in simulating landslides with mechanistic models.

How to cite: Arnone, E., Soylu, E. M., Takahiro, F., and Bras, R. L.: Modeling the impact of Hurricane Maria on Puerto Rico with an eco-hydrological landslide model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14949, https://doi.org/10.5194/egusphere-egu24-14949, 2024.

EGU24-15351 | ECS | Posters on site | NH3.6

Mapping landslide susceptibility through physically-based modeling 

Federica Angela Mevoli, Lorenzo Borselli, Michele Santangelo, Angelo Ugenti, Daniela de Lucia, Nunzio Luciano Fazio, and Mauro Rossi

Landslide susceptibility is the likelihood of a landslide occurring in a specific area based on the local terrain conditions. Susceptibility does not take into account the size, duration, or frequency of occurrence of landslides. Different approaches and methods have been proposed to determine the likelihood of occurrence of landslides: geomorphological mapping, analysis of landslide inventories, heuristic terrain zoning, statistically-based classifications and physically based numerical modelling (Aleotti and Chowdhury, 1999; Guzzetti et al., 1999). The last two approaches are preferred for assessing susceptibility in quantitative terms. Today, statistically based methods are preferred for small-scale landslide susceptibility zonations. Performing this task by using physically-based approaches is more challenging, as the performance of numerical analyses usually requires detailed geomechanical and hydrological data, whose collection demands significant time and costly efforts.

However, this work is primarily motivated by the following question: Can landslide susceptibility maps at smaller scales than detail-scale truly not be attained through the application of physically-based approaches?

The authors show their first attempt in answering the question through the combined application of Geographic Information Systems (GIS) and a 2.5D Limit Equilibrium Method (LEM) implemented using the SSAP software (Borselli, 2023). The results obtained in a study area in Southern Italy and the physically-based landslide susceptibility map derived at basin-scale are presented and discussed. This preliminary but yet reproducible analysis allows to drive future efforts in physically-based susceptibility zonation.

 

References

Aleotti, P., & Chowdhury, R. (1999). Landslide hazard assessment: summary review and new perspectives. Bulletin of Engineering Geology and the environment58, 21-44. DOI: https://doi.org/10.1007/s100640050066

Borselli L. (2023). "SSAP 5.2 - slope stability analysis program". Manuale di riferimento. Del codice ssap versione 5.2. Researchgate.   DOI: https://dx.doi.org/10.13140/RG.2.2.19931.03361

Guzzetti, F., Carrara, A., Cardinali, M., & Reichenbach, P. (1999). Landslide hazard evaluation: a review of current techniques and their application in a multi-scale study, Central Italy. Geomorphology31(1-4), 181-216. DOI: https://doi.org/10.1016/S0169-555X(99)00078-1

How to cite: Mevoli, F. A., Borselli, L., Santangelo, M., Ugenti, A., de Lucia, D., Fazio, N. L., and Rossi, M.: Mapping landslide susceptibility through physically-based modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15351, https://doi.org/10.5194/egusphere-egu24-15351, 2024.

EGU24-15580 | ECS | Orals | NH3.6

Landsifier 2.0: Towards automating landslide trigger and failure movement identification 

Lorenzo Nava, Kushanav Bhuyan, Manan Kapoor, Kamal Rana, Ascanio Rosi, Joaquin Vicente Ferrer, Ugur Ozturk, Mario Floris, Cees van Westen, and Filippo Catani

Understanding landslide failure processes is pertinent to predict and minimize the effects of landslides. A variety of elements, such as geology, topography, and soil conditions, can lead to slope failures triggered via natural causes e.g., rainfall and earthquakes, setting off the failure movements. Proper geotechnical analysis requires knowledge of both the triggering event and the subsequent movement patterns of the landslide. This information is vital for accurately predicting when and where landslides might occur. To integrate this information into existing landslide inventories, we introduce Landsifier 2.0, a tool designed to meet the needs of the landslide research community. This Python-based library allows seamless usage of machine learning models to extract information regarding landslide triggers and failure movements solely based on inventories of landslides. Powered by topology, a high-dimensional feature extraction module encapsulated within our library, information accessed via a landslide's shapes and configurations allows the identification of triggers (e.g., earthquake-and rainfall-triggered landslides) and failure movements (e.g., rotational slides, translational slides, debris flows, rock falls) of undocumented landslide inventories through continuous remote sensing missions. We showcase the library’s application in diverse geomorphological and climatic settings e.g., South-western China, Denmark, Turkey, Japan, Italy and more. We anticipate that Landsifier 2.0 will be particularly useful in the predictive modelling domain (including susceptibility and hazard modelling) of landslide studies, where precise information about triggers and failure dynamics is essential for developing reliable predictive models.


References:
Rana, Kamal, Uğur Öztürk, and Nishant Malik. 2021. “Landslide Geometry Reveals Its Trigger.” Geophysical Research Letters 48(4). doi: 10.1029/2020gl090848.
Rana, Kamal, Nishant Malik, and Uğur Öztürk. 2022. “Landsifier v1.0: A Python Library to Estimate Likely Triggers of Mapped Landslides.” Natural Hazards and Earth System Sciences 22(11):3751–64. doi: 10.5194/nhess-22-3751-2022.
Rana, Kamal, Kushanav Bhuyan, Joaquin Vicente Ferrer, Fabrice Cotton, Uğur Öztürk, Filippo Catani, and Nishant Malik. 2023. “Landslide Topology Uncovers Failure Movements.” arXiv (Cornell University). doi: 10.48550/arxiv.2310.09631.

How to cite: Nava, L., Bhuyan, K., Kapoor, M., Rana, K., Rosi, A., Vicente Ferrer, J., Ozturk, U., Floris, M., van Westen, C., and Catani, F.: Landsifier 2.0: Towards automating landslide trigger and failure movement identification, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15580, https://doi.org/10.5194/egusphere-egu24-15580, 2024.

Lvliang, located in Shanxi Province, was built on the loess plateau where the loess is characterized by high potential of collapsibility. Monsoonal precipitation, steep slopes, and anthropogenic activities such as coal mining make this terrain even more fragile. To better inform the farmland allocation, village relocation, and resettlement for the local residents, we have to assess the hazard exposure to fractures and landslides across the entire region. Here we use a double differencing method, i.e., computing the differential interferograms after applying distinct filtering windows, to pinpoint high-frequency signals suggesting drastic ground displacement. We further apply small baseline subset (SBAS) time-series analysis using Copernicus Sentinel-1 images collected from July 16th 2015 to May 16th 2023 to generate displacement time series. Our results show seasonal variations in displacement rates distributed on hillslopes. Our study demonstrates the efficacy of InSAR time series analysis in monitoring deformation with various natural and anthropogenic origins for the ultimate goal of disaster prediction, prevention, and reduction.

How to cite: Wu, P. and Hu, X.: Characterization of Ground Displacement over Mining Sites and Landslides in Lvliang, Shanxi Province, China, Using InSAR Time Series Analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16453, https://doi.org/10.5194/egusphere-egu24-16453, 2024.

Strong earthquakes on mountain slopes can trigger numerous landslides, a significant secondary hazard responsible for a substantial proportion of fatalities in the affected area. In this study, we present a model framework for rapidly creating coseismic landslide probability distribution maps using machine learning models and optimal conditioning factors. To illustrate our approach, we focus on the case of the Mw 7.2 Haiti earthquake in 2021 and predict the distribution of coseismic landslides based on historical landslide data collected following the Mw 7.0 Haiti earthquake in 2010. To validate our findings, we mapped all the landslides triggered during the 2021 event. Furthermore, we conduct a comparative analysis of various landslide-conditioning factors (seismic, topographic, lithologic, and hydrological variables) in relation to the coseismic landslides occurring during both earthquake events in 2010 and 2021, to reassess the factors feed into the machine learning model. We observed noticeable differences in patterns of several conditioning factors between the two events EQIL distributions (e.g., tectonic and releif factors), but consistent similarities in other terrain factors (e.g., slope, curvature, topographic wetness index, etc.). Our Random Forest (RF) model, initially trained using the 2010 landslide inventory and 15 selected factors, effectively predicts 2021 landslides with an area under curve (AUC) score of 0.83. Improved performance is achieved when we use a reevaluated set of six factors for training, resulting in an AUC score of 0.90, with  93% of landslides falling into the high to medium probability class. These findings demonstrate the feasibility of rapidly generating highly accurate coseismic landslide distribution maps, even when there are considerable differences in key conditioning factors, highlighting the applicability of ML models to complex problems.

How to cite: Thanveer, J. and Pulpadan, Y. A.: Rapid Estimation of Earthquake Induced Landslides using Machine Learning Models: Insights from Haiti Earthquakes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16454, https://doi.org/10.5194/egusphere-egu24-16454, 2024.

Recent works on landslide displacement forecasting using machine learning or deep learning models show relevant performance. However, they are mostly based on the use of historical displacement information and do not provide information on the most predictive features in terms of meteorological and hydrogeological variables for the forecast, and thus the identification of possible precursory factors. In this context, providing approaches based on EXplainable Machine Learning (XML) is essential for landslide forecasting as it concerns making decisions about risk mitigation actions, it supports the identification of possible precursory factors and it increases confidence in the predictions.
The proposed XML-based landslide forecasting approach is developed and tested using ensemble learning methods such as Random Forest and XGBoost. It relies on the use of multi-year and multi-parameter data chronicles to analyse the relationships between surface displacements (target data) and hydro-meteorological conditions (predictor data). Displacement and meteorological data are acquired through the landslide monitoring network. Hydrological data, when not available, are simulated discharge calculated with reservoir based-model; the simulations allow to construct water level time series for each water reservoirs identified in the unstable slope.
The predictive time series are decomposed into a set of 340 descriptive features (mean, variance, difference, number of rainy days, number of consecutive rainy periods of X days, …). The displacement time series are detrended using the multiplicative decomposition method.
This method has been applied to several use cases, such as the Séchilienne landslide located southwest of the Belledonne massif (French Alps). The Random forest and XGBoost models are trained and tested over periods of 12 and 5 years respectively, and applied to three automatic extensometers located in the most active part of the landslide. The results indicate that the main features used include variations in water levels over past 10 to 30 days, as well as the number of consecutive rainy period during the month. These results are associated with accurate predictions for the three extensometers, with coefficients of determination ranging between 0.37 and 0.46.
We show that these models have high predictive power while informing about the most important hydro-meteorological features. The application of the models to trendless displacement time series significantly improves prediction accuracy.

How to cite: Maillard, O., Bertrand, C., and Malet, J.-P.: Forecasting landslide motion with EXplainable Machine Learning models: the use case of Séchilienne landslide (French Alps) to identify the relevant predicting variables, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16825, https://doi.org/10.5194/egusphere-egu24-16825, 2024.

Hybrid, physically constrained machine learning models combine the predictive power of machine learning approaches with the plausibility and interpretability of established physical models. The architecture of artificial neural networks (ANNs) allows to incorporate process-based constraints and physical laws to ensure a physically plausible and therefore generalizable model output.
Hybrid models have proven their utility in a variety of scientific domains and, most recently, in the Earth system sciences. They have been successfully applied to model the global hydrological cycle or ocean currents and sea surface temperatures.
However, up to now, the applicability of hybrid models has not yet been explored for landslide susceptibility and hazard modeling.
It is therefore our objective to shed light on the potential of hybrid, physically constrained slope stability models by assessing the predictive performance and plausibility of results as a prerequisite for a wider adoption of such approaches in landslide studies. We have embedded an established slope stability model in an ANN framework to overcome parameterization issues: The ANNs estimate the spatial distribution of soil properties and local soil cohesion as spatially variable latent inputs to the physically based model structure without requiring field or laboratory data of these parameters. As a case study, in cooperation with the Geological Survey of Slovenia (GeoZS) we have developed a landslide susceptibility map for the municipalities most affected by the disastrous rainfall event in August 2023.
Preliminary results show a good agreement with existing susceptibility maps produced with traditional slope stability models. Model parameters which would require extensive laboratory measurements for calibration could be plausibly estimated by machine learning. The hybrid approach furthermore allowed us to explicitly map these latent variables as a side product that supports model interpretation and can be evaluated with ancillary data that may become available in the future.
Building upon these results, we plan to expand the model's spatial and temporal domains. In doing so, we can assess this novel approach in terms of its transferability and generalization capabilities.

How to cite: Strohmaier, F. and Brenning, A.: Hybrid Physically Constrained Machine Learning Models of Landslide Susceptibility: a Case Study from Slovenia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17248, https://doi.org/10.5194/egusphere-egu24-17248, 2024.

EGU24-17785 | ECS | Posters on site | NH3.6

Application of beta regression for the prediction of landslide areal density in South Tyrol, Italy  

Mateo Moreno, Thomas Opitz, Stefan Steger, Cees van Westen, and Luigi Lombardo

The concept of landslide hazard entails evaluating landslide occurrence in space (i.e., where landslides may occur), in time (i.e., when or how often landslides may occur), and their intensity (i.e., how destructive landslides may be). At regional scales, data-driven methods are implemented to separately analyze the spatial component (i.e., landslide susceptibility) and the temporal conditions leading to landslide occurrence, such as rainfall thresholds. However, assessing how large a landslide may develop once triggered is seldom conducted and poses a persistent challenge to satisfying the complete definition of landslide hazard.

So far, only a few publications have addressed this issue by predicting the total areal extent of landslides based on certain mapping units, such as slope units. Limitations arise since the total areal extent of landslides within a mapping unit is strongly influenced by the size of the mapping unit, leading to larger mapping units being more likely to encompass larger total landslide areas. To tackle these challenges, this study aims to predict the landslide area proportion per slope unit in South Tyrol, Italy (7,400 km²). Our approach built upon past landslide occurrences from 2000 to 2020, systematically related to damage-causing and infrastructure-threatening landslide events. The method involved delineating slope units, filtering the landslide inventory, designing the sampling strategy, removing trivial areas, and aggregating the environmental variables (e.g., topography, lithology, land cover, and precipitation) to the slope unit partition. We tested a generalized additive beta regression model to estimate statistical relationships between the various static predictors and the target landslide areal density. The resulting spatially explicit predictions are evaluated through cross-validation from multiple perspectives. Applications and shortcomings of the approach are discussed.

The proposed method is anticipated to provide valuable insights and alternatives to assessing landslide intensity and moving toward landslide hazard in a data-driven context. The outcomes associated with this research are framed within the PROSLIDE project, which has received funding from the research program Research Südtirol/Alto Adige 2019 of the Autonomous Province of Bozen/Bolzano – Südtirol/Alto Adige.

How to cite: Moreno, M., Opitz, T., Steger, S., van Westen, C., and Lombardo, L.: Application of beta regression for the prediction of landslide areal density in South Tyrol, Italy , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17785, https://doi.org/10.5194/egusphere-egu24-17785, 2024.

EGU24-18279 | ECS | Posters on site | NH3.6

Representative Profile Model (RPM): A new physically-based model for assessing the hazards of colluvial landslides at local scale 

Xiao Feng, Juan Du, Bo Chai, Yang Wang, Fasheng Miao, and Thom Bogaard

The physically-based models for regional landslide hazard assessment typically use straight and homogeneous slope geometry and an infinite slope assumption. They assume that the sliding surface and saturation line are parallel to the surface, neglecting the variations in topography and soil thickness across different sections of the slope. This simplification can result in substantial inaccuracies in the regional landslide hazard assessment. To address these limitations, this study proposes a novel, spatially-distributed and physically-based model known as the Representative Profile Model (RPM). RPM distinguishes itself by using slope units rather than grid units, as the primary units of assessment. It efficiently integrates soil thickness and groundwater level information to automatically generate a detailed representative profile for each slope unit. These profiles include a ground surface line, a sliding surface, and a saturation line. This means that RPM can well take into account the effects of topographic relief and spatially uneven distribution of soil thickness for quantifying regional slope stability. Moreover, RPM combines the residual thrust method with the Monte Carlo method. This integration allows for the calculation of failure probabilities for each slope unit, thereby enabling comprehensive and complex susceptibility and hazard assessments at a local scale. A local scale assessment of landslide susceptibility and hazard in Tiefeng Township, Wanzhou District, Chongqing was carried out, with the RPM model. Subsequently, a comparative analysis was conducted with the TRIGRS model, which is based on grid units. The superior performance of RPM was clearly demonstrated by our findings.

How to cite: Feng, X., Du, J., Chai, B., Wang, Y., Miao, F., and Bogaard, T.: Representative Profile Model (RPM): A new physically-based model for assessing the hazards of colluvial landslides at local scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18279, https://doi.org/10.5194/egusphere-egu24-18279, 2024.

EGU24-18624 | Posters on site | NH3.6

Regional scale landslide susceptibility maps: strengths and weaknesses 

Paola Molin, Andrea Sembroni, and Gioia Vetere

Landslides are among the most dangerous natural hazards impacting on human life claiming lives and affecting economy and society. For this reason, the cost of the repeated occurrence of landslides could become unsustainable for a country. In this respect, the assessment of the susceptibility to landslide of a region becomes crucial to mitigate the economic and societal implications and to save lives. A typical approach starts from the inventory of landslides by field survey coupled with database consulting. This activity could assess the discriminating and predisposing factors, defining the weight of each of them on the slope stability. Overlaying resulting maps in GIS environment, a susceptibility map of each type of landslide could be produced. At local scale, the field survey allows to identify properly the past events and the factors that contributed to the instability. Unfortunately, sometimes managers and policy makers ask for landslide prediction regarding areas that are too large for a detailed field survey. As a consequence it is necessary to work out methods that start from available database. The main problem is to check the quality of the data and to eliminate possible errors. Starting from a classical susceptibility analysis based on landslide inventory derived from filed survey, we propose a modified method applicable to database on regional scale area. In detail, we check the quality of the database with respect to landslide locations eliminating unproper sites according to hillslope interval or rock-type, i.e. the two main discriminating factors. Our results show how this kind of approach allows to produce maps that are useful for general landscape management indicating the areas susceptible to each type of landslide. These preliminary maps are the basis for identifying the areas where more detailed studies are needed.

How to cite: Molin, P., Sembroni, A., and Vetere, G.: Regional scale landslide susceptibility maps: strengths and weaknesses, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18624, https://doi.org/10.5194/egusphere-egu24-18624, 2024.

EGU24-18847 | ECS | Orals | NH3.6

A unified Bayesian model selection workflow for geophysical free-surface flow 

V Mithlesh Kumar and Julia Kowalski

The broad family of shallow flow models arises from depth-averaging the underlying governing balance laws. Depth-averaging yields an analytical model complexity reduction, increasing computational efficiency and reducing the number of model parameters. Consequently, shallow flow models become a desirable choice for various scientific and engineering applications, such as landslide prediction and coastal engineering. In the realm of landslide modelling, different variants of shallow flow models are often tailored - sometimes in an ad hoc manner - to specific physical phenomena, such as basal shear, non-hydrostatic effects, kinetics, or phase change processes. Therefore, selecting the most appropriate shallow flow model for a particular scenario based on quantitative reasoning poses a formidable challenge. Quantifying the uncertainty associated with this model selection is essential to assess the reliability of the predictions of these shallow flow models.

Here, we present a unified Bayesian model selection workflow leveraging Gaussian Process emulation — a machine learning technique used for non-intrusive physics-based machine learning. It starts with model calibration, where we generate posterior samples. These are then used to calculate the marginal likelihood, the basis for our model selection. This process faces two computational bottlenecks: significant computational costs involved in numerous model evaluations during calibration and high-dimensional, intractable integrals in the computation of Marginal Likelihood. To address the former, we integrated Gaussian process emulators into the workflow using PSimPy, our in-house Python package, for predictive and probabilistic simulations. For the latter bottleneck, we conducted a comprehensive literature review, with particular emphasis on marginal likelihood computation techniques based on Importance Sampling and implemented single proposal density schemes and integrated them into the workflow.

We demonstrate our approach using elementary landslide runout models across varying fidelity levels, investigating the impact of data representation—specifically, comparing point data to time series data—while considering data characteristics such as velocity and distance. Additionally, we calibrated the discrepancy parameter for robust handling of uncertainties associated with the data. Our future work will focus on implementing advanced importance sampling schemes to enhance the computation of the Marginal Likelihood, especially in high-dimensional scenarios. Furthermore, emphasis will be placed on adopting a hierarchical approach to address data uncertainty in conjunction with model inadequacy, which is not accounted for in the existing workflow.

How to cite: Kumar, V. M. and Kowalski, J.: A unified Bayesian model selection workflow for geophysical free-surface flow, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18847, https://doi.org/10.5194/egusphere-egu24-18847, 2024.

EGU24-20698 | Posters on site | NH3.6

Utilizing deep neural networks for landslide detection and segmentation in remote sensing imagery 

Jasmin Lampert, Lam Pham, Cam Le, Matthias Schlögl, and Alexander Schindler

Understanding the occurrences of historic landslide events is crucial for supporting strategies aimed at reducing disaster risks. Drawing from insights obtained in the 2022 Landslide4Sense competition, we present a methodological framework reliant on a deep neural network design for the detection and segmentation of landslides using input from various remote sensing sources. Our approach involves using a U-Net architecture, initially trained with cross entropy loss, as a baseline. We then enhance this architecture by employing diverse deep learning techniques. Specifically, we engage in feature engineering by creating new band data derived from the original bands, thereby improving the quality of the remote sensing image input. Concerning the network architecture, we substitute the conventional convolutional layers in the U-Net baseline with a residual-convolutional layer. Additionally, we introduce an attention layer that capitalizes on a multi-head attention scheme. Furthermore, we generate multiple output masks at three distinct resolutions, forming an ensemble of three outputs during the inference process to augment performance. Lastly, we propose a composite loss function that integrates focal loss and IoU loss to train the network effectively. Our experiments on the Landslide4Sense challenge's development set yield an F1-score of 84.07 and an mIoU score of 76.07. Our optimized model surpasses both the challenge baseline and the proposed U-Net baseline, improving the F1-score by 6.8/7.4 and the mIoU score by 10.5/8.8, respectively.

How to cite: Lampert, J., Pham, L., Le, C., Schlögl, M., and Schindler, A.: Utilizing deep neural networks for landslide detection and segmentation in remote sensing imagery, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20698, https://doi.org/10.5194/egusphere-egu24-20698, 2024.

Dams, powerlines, and power plants represent strategic energetic infrastructures and their future operativity maintenance is a challenge. Stakeholders are strongly interested in evaluating the potential risks that may affect their functionality, especially regarding natural hazards. In Italy, geo-hydrological hazards triggered by rainfall such as floods and landslides represent a serious threat to electrical infrastructure, since their magnitude is generally difficult to modelling and quantify properly.

Here, we present an application of the model proposed by Borga et. Al. for rainfall-induced shallow landslide hazard assessment. The model merges an infinite slope stability equation with a simplified hydrogeological model evaluating, for a defined rainfall duration, the critical rainfall ratio able to trigger the landslide failure. The model has been adapted to work automatically using Python scripts and has been extended proposing a new strategy for evaluating the Dynamic Contributing Area and for including soil moisture information. Rainfall return time was considered as a proxy of the magnitude of the geo-hydrological events, identifying the most hazardous area with respect to the position of powerlines for the case study basin of Trebbia River, Emilia, Italy. Model results were validated against the currently available local rainfall threshold curves, showing good skill in failure detection.

The instrument could be useful for planning purposes, addressing, and quantifying the location under which the critical infrastructure may encounter risk with respect to geo-hydrological threats, and giving useful insights about possible mitigation strategies to increase the overall electro-energetic system resilience.

How to cite: Abbate, A. and Mancusi, L.: A fast geo-hazard assessment for electro-energetic network systems using a simplified geo-hydrological model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22521, https://doi.org/10.5194/egusphere-egu24-22521, 2024.

EGU24-12 | ECS | Posters on site | NH9.1 | Highlight

Understanding fatal landslides on a global scale: insights from topographic, climatic, and anthropogenic perspectives 

Seckin Fidan, Hakan Tanyas, Abdullah Akbas, Luigi Lombardo, David N. Petley, and Tolga Gorum

Landslides are a common global geohazard that lead to substantial loss of life and socio-economic damage annually. Landslides are becoming more common due to climate change and anthropogenic disturbance, threatening sustainable development in vulnerable areas. Previous studies on fatal landslides have focussed on inventory development; spatial and temporal distributions; the role of precipitation and/or seismic forcing; and human impacts. However, their climatological, topographic, and anthropogenic characterization on a global scale has been neglected. Here, we present the association of natural and anthropogenically induced landslides in the Global Fatal Landslide Database (GFLD) with topographic, climatic, and anthropogenic factors, focusing on their persistent spatial patterns. The majority of natural (69.3%) and anthropogenic (44.1%) landslides occur in mountainous areas in tropical and temperate regions, which are also characterized by the highest casualty rates per group (66.7% and 43.0%, respectively). However, they significantly differ in terms of their morphometric footprint. Fatal landslides triggered by natural variables occur mostly in the highest portions of the topographic profile, where human disturbance is minimal. As for their anthropogenic counterpart, these failures cluster at much lower altitudes, where slopes are gentler, but human intervention is greater due to a higher population density. Our results demonstrate that fatal landslides have a heterogeneous distribution on different macro landforms characterized by different topographic, climatic, and population conditions. Our observations also point towards land cover changes being a critical factor in landscape dynamics, stressing human pressure as a discriminant cause/effect term for natural vs. human-induced landslide fatalities.

How to cite: Fidan, S., Tanyas, H., Akbas, A., Lombardo, L., Petley, D. N., and Gorum, T.: Understanding fatal landslides on a global scale: insights from topographic, climatic, and anthropogenic perspectives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12, https://doi.org/10.5194/egusphere-egu24-12, 2024.

EGU24-1451 | ECS | Posters on site | NH9.1

A vulnerability framework for a global flood catastrophe model 

Conor Lamb, Izzy Probyn, Oliver Wing, James Daniel, Florian Elmer, and Malcolm Haylock

In recent years the precision and skill of global flood hazard models has increased dramatically. This, alongside developments allowing for hazard model conversion to stochastic event sets and the open-sourcing of catastrophe modeling software, have opened up the possibilities of developing detailed and skillful global flood catastrophe models; assessing not just average risk but also the possible impacts of major flood events and the probability distribution of annual losses. In order to realize these possibilities, it is necessary to develop a global vulnerability framework that appropriately represents the state of the art in vulnerability modeling whilst being flexible to user inputs and faithfully representing uncertainties. 

Here, we present a framework for implementing a flexible vulnerability module within a global flood catastrophe model. Vulnerability curves are derived for a variety of occupancies (residential, commercial, industrial), for both building and contents losses. The mean loss ratio curves are derived from literature and commercial datasets before being normalized and fit to a family of logarithmic functions of depth, which can be adjusted for varying property characteristics. Uncertainty distributions are parameterised using a 4 parameter beta model and derived from a large insurance claims dataset (~2 million claims). 

Finally, using the same large claims dataset, we explore the event-level correlation of the quantiles sampled within our uncertainty distribution. Specifically, we evaluate the extent to which the quantiles sampled of the uncertainty distribution, in a Monte Carlo approach, should be clustered for each event. This is vital for correctly estimating the losses from rare, high-impact events and allows for a realistic representation of vulnerability uncertainty in aggregate loss estimates. 

How to cite: Lamb, C., Probyn, I., Wing, O., Daniel, J., Elmer, F., and Haylock, M.: A vulnerability framework for a global flood catastrophe model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1451, https://doi.org/10.5194/egusphere-egu24-1451, 2024.

EGU24-1669 | ECS | Posters on site | NH9.1

A Comprehensive Review of Coastal Compound Flooding Literature 

Joshua Green, Ivan Haigh, Niall Quinn, Jeff Neal, Thomas Wahl, Melissa Wood, Dirk Eilander, Marleen de Ruiter, Philip Ward, and Paula Camus

Compound flooding, where the combination or successive occurrence of two or more flood drivers leads to an extreme impact, can greatly exacerbate the adverse consequences associated with flooding in coastal regions. This paper reviews the practices and trends in coastal compound flood research methodologies and applications, as well as synthesizes key findings at regional and global scales. Systematic review is employed to construct a literature database of 271 studies relevant to compound flood hazards in a coastal context. This review explores the types of compound flood events, their mechanistic processes, and synthesizes the definitions and terms exhibited throughout the literature. Considered in the review are six flood drivers (fluvial, pluvial, coastal, groundwater, damming/dam failure, and tsunami) and five precursor events and environmental conditions (soil moisture, snow, temp/heat, fire, and drought). Furthermore, this review summarizes the trends in research methodology, examines the wide range of study applications, and considers the influences of climate change and urban environments. Finally, this review highlights the knowledge gaps in compound flood research and discusses the implications of review findings on future practices. Our five recommendations for future compound flood research are to: 1) adopt consistent definitions, terminology, and approaches; 2) expand the geographic coverage of research; 3) pursue more inter-comparison projects; 4) develop modelling frameworks that better couple dynamic earth systems; and 5) design urban and coastal infrastructure with compound flooding in mind. We hope this review will help to enhance understanding of compound flooding, guide areas for future research focus, and close knowledge gaps.

How to cite: Green, J., Haigh, I., Quinn, N., Neal, J., Wahl, T., Wood, M., Eilander, D., de Ruiter, M., Ward, P., and Camus, P.: A Comprehensive Review of Coastal Compound Flooding Literature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1669, https://doi.org/10.5194/egusphere-egu24-1669, 2024.

Translation of geoscience research into tangible changes, such as modified decisions, processes or policy in the wider world is an important yet notably difficult process. Co-RISK is an accessible (i.e. open access, paper-based, zero cost) ‘toolkit’ for use by stakeholder groups within workshops, which is intended to aid this translation process. It is given a robust basis by incorporating paradox theory from organisation studies, which deals with navigating the genuine tensions between industry and research organizations that stem from their differing roles. Specifically designed to ameliorate the organizational paradox, a Co-RISK workshop draws up ‘Maps’ including key stakeholders (e.g. regulator, insurer, university) and their positionality (e.g. barriers, concerns, motivations), and identifies exactly the points where science might modify actions. Ultimately a Co-RISK workshop drafts simple and tailored project-specific frameworks that span from climate to hazard, to risk, to implications of that risk (e.g. solvency). The action research approach used to design Co-RISK (with Bank of England, Aon, Verisk), its implementation in a trial session for the insurance sector and its intellectual contribution are described and evaluated. The initial Co-RISK workshop was well received, so application is envisaged to other sectors (i.e. transport infrastructure, utilities, government).  Joint endeavours enabled by Co-RISK could fulfil the genuine need to quickly convert the latest insights from environmental research into real-world climate change adaptation strategies. 

 

https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1251/

How to cite: Hillier, J. K. and van Meeteren, M.: Co-RISK: A tool to co-create impactful university-industry projects for natural hazard risk mitigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1684, https://doi.org/10.5194/egusphere-egu24-1684, 2024.

EGU24-2009 | ECS | Orals | NH9.1

Considering aftershock-induced damage accumulation in seismic loss assessments 

Corentin Gouache and Adélaïde Allemand

This work outlines a methodology developed for considering aftershock-induced damage accumulation in seismic loss assessments. In particular, it adapts this methodology to the case of reinforced concrete (RC) frames in mainland France and incorporates it to an already-developed seismic loss assessment model.

The methodology consists in dividing the RC buildings into sub-categories of buildings, depending on parameters influencing the vulnerability of the structures. For each category, a set of discrete damage states is defined. For each state Di, fragility functions are derived, enabling to compute the probability of transitioning to another damage state Di+1, knowing the intensity of the ground motion. Therefore, this methodology allows to estimate the final damage state reached by a structure submitted to a series of ground motions.

In order to do so, the pool of French RC buildings is analysed so as to create realistic and general models of RC frames. Ground motions are selected from an open database, following some criteria. Fragility functions are then derived (for each type of building) by applying numerous ground motions to the models and assessing the probabilities of reaching each damage state. The methods for constructing those fragility functions are evaluated from the literature. The choice of relevant parameters measuring damage and measuring ground motion intensity is also scrutinized.

How to cite: Gouache, C. and Allemand, A.: Considering aftershock-induced damage accumulation in seismic loss assessments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2009, https://doi.org/10.5194/egusphere-egu24-2009, 2024.

EGU24-5951 | ECS | Posters on site | NH9.1

Three-dimensional analysis of air temperature of the Hualien M6.9 earthquake based on the tidal forces 

Xian Lu, Weiyu Ma, and Zhengyi Yuan

The Hualien M6.9 earthquake on September 18, 2022 was calculated based on the additional tectonic stress caused by celestial tidal-generating forces (ATSCTF) model. The period of celestial tidal-generating forces was the time background of the air temperature calculation, and the air temperature variation of three-dimensional layered before and after the Hualien earthquake was studied combined with the air temperature data from the National Center for Environmental Prediction (NCEP) of United States. According to the changes of ATSCTF, the Hualien earthquake occurred within the Period B among the three periods: Period A, Period B, and Period C. The air temperature stratification changes during these three periods were calculated separately, and the results showed that on September 12 in Period B, a temperature increase phenomenon began to occur near the epicenter of the Hualien earthquake. On September 13, the air temperature increase anomaly was significant, and the amplitude and area of the temperature enhancement anomaly increased. On September 14th and 15th, the anomaly gradually weakened and disappeared, and the change of the air temperature anomaly followed the seismic thermal anomaly law caused by tectonic movement: the air temperature closer to the land’s surface had a greater anomaly amplitude and a wider anomaly range; as the altitude increases, the air temperature gradually decreases, and the range of anomalies gradually reduces until it disappears. Meanwhile, there were also high temperature anomalies on September 4 and 5 in the Period A, as well as October 1 to October 4 in the Period C. However, the amplitude and area of the warming anomalies in the upper atmosphere were larger than those near the land surface, which did not conform to the seismic thermal anomaly law caused by tectonic movements and did not belong to the seismic thermal anomalies. In addition, the solar geomagnetic KP index in the study area was relatively low during Period B, indicating that it was in a calm period of solar geomagnetic.

How to cite: Lu, X., Ma, W., and Yuan, Z.: Three-dimensional analysis of air temperature of the Hualien M6.9 earthquake based on the tidal forces, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5951, https://doi.org/10.5194/egusphere-egu24-5951, 2024.

EGU24-7652 | ECS | Posters on site | NH9.1

A semi-automatic natural language tool to minimize systematic biases in geo-hydrological disaster datasets in tropical Africa 

Bram Valkenborg, Olivier Dewitte, and Benoît Smets

The high susceptibility to geo-hydrological hazards in tropical Africa and their impacts remain poorly documented in existing disaster databases. Only impactful events with high attention are manually reported, creating systematic biases. Natural Language Processing has the potential to automate the documentation of geo-hydrological disasters. This research focuses on developing a semi-automated tool to extract information from online press and social media posts. Fine-tuned Large Language Models perform a series of tasks, such as question-answering, zero-shot classification, and near-entity recognition, to extract information from these online sources. A three-step approach is proposed for the detection of events: (1) filtering posts or articles on their relevancy, (2) extracting information on the location, timing, and impact and (3) merging and sorting information to document identified events into a structured disaster database. Shortcomings compared to a manual approach remain. These mainly relate to the complexity of the text or toponymic ambiguity when geocoding events. The tool is therefore complementary to other information-gathering approaches. These new sources of information will improve our understanding of the distribution of disasters related to geo-hydrological hazards, especially in data scarce context. Future work will combine this semi-automated tool with remote sensing and citizen science data, to further reduce systematic biases in disaster datasets.

How to cite: Valkenborg, B., Dewitte, O., and Smets, B.: A semi-automatic natural language tool to minimize systematic biases in geo-hydrological disaster datasets in tropical Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7652, https://doi.org/10.5194/egusphere-egu24-7652, 2024.

EGU24-7875 | ECS | Orals | NH9.1

Advancing drought detection and management using ML enhanced impact-based drought indexes 

Martina Merlo, Matteo Giuliani, Yiheng Du, Ilias Pechlivanidis, and Andrea Castelletti

Drought is a slowly developing natural phenomenon that can occur in all climatic zones and propagates through the entire hydrological cycle with long-term socio-economic and environmental impacts. Intensified by anthropogenic climate change, drought has become one of the most significant natural hazards in Europe. Different definitions of drought exist, i.e. meteorological, hydrological, and agricultural droughts, which vary according to the time horizon and the variables considered. Just as there is no single definition of drought, there is no single index that accounts for all types of droughts. Consequently, capturing the evolution of drought dynamics and associated impacts across different temporal and spatial scales remains a critical challenge.

In this work, we first analyze different state-of-the-art standardized drought indexes in terms of their ability in detecting drought events at the pan-European scale, using hydro-meteorological variables from the E-HYPE hydrological model and forced with the HydroGFD v2.0 reanalysis dataset over the period 1993-2018. The findings suggest the need of adjusting the formulation of traditional drought indexes to better capture and represent drought-related impacts. Specifically, here we use the FRamework for Index-based Drought Analysis (FRIDA), a Machine Learning approach that allows the design of site-specific indexes to reproduce a surrogate of the drought impacts in the considered area, here represented by the Fraction of Absorbed Photosynthetically Active Radiation Anomaly (FAPAN). FRIDA builds a novel impact-based drought index combining all the relevant available information about the water circulating in the system identified by means of a feature extraction algorithm.

Our results reveal a general pattern among different indexes, that Southern England, Northern France, and Northern Italy are the regions with the highest number of drought events, whereas the areas experiencing longest drought durations are instead the Baltic Sea region and Normandy. Clustering the 35,408 European basins according to dominant hydrologic processes reveals that the variables mainly controlling the drought process vary across clusters. Similarly, we obtain diverse correlation between standardized drought indexes and the FAPAN in different clusters. Numerical results also show that, in one of the worst cases (cluster 10), the FRIDA index increases the correlation with FAPAN from 0.16 to 0.69. Lastly, the FRIDA indexes are computed for different climatic projections to investigate future trends in drought impacts.  Results show divergence with respect to the trends of the standardized drought indexes, with correlation values below 0.30. In conclusion, these findings can contribute in advancing drought-related climate services by enabling the analysis of projected drought impacts.

 

How to cite: Merlo, M., Giuliani, M., Du, Y., Pechlivanidis, I., and Castelletti, A.: Advancing drought detection and management using ML enhanced impact-based drought indexes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7875, https://doi.org/10.5194/egusphere-egu24-7875, 2024.

EGU24-8660 | ECS | Orals | NH9.1 | Highlight

Assessing landslide risk on a Pan-European scale 

Francesco Caleca, Luigi Lombardo, Stefan Steger, Ashok Dahal, Hakan Tanyas, Federico Raspini, and Veronica Tofani

Assessing landslide risk is a fundamental step in planning prevention and mitigation actions in mountainous landscapes. To date, most landslide risk analyses address this topic at the scale of a slope or catchment. Whenever the scale involves regions, nations, or continents, the landslide risk analysis is hardly implemented. To test this theoretical framework, we present a practical case study, represented by the European landscape. In this contribution, we take the main Pan-European mountain ranges and provide an example of risk assessment at a continental scale. We consider challenges like cross-national variations landslide mapping and digital data storage. A two-stepped protocol is developed to identify areas more prone to failure. With this initial information, we then model the possible economic consequences, particularly in terms of human settlements and agricultural areas, as well as the exposed population. The analytical protocol firstly results in an unbiased landslide susceptibility map, which is combined with economic and population data. The landslide risk is presented in both the spatial distribution of possible economic losses and the identification of risk hotspots. The latters are defined through a bivariate classification scheme by combining the landslide susceptibility and exposure of human settlements. Ultimately, the exposed population is represented during the two sub-daily cycles across the study area.

How to cite: Caleca, F., Lombardo, L., Steger, S., Dahal, A., Tanyas, H., Raspini, F., and Tofani, V.: Assessing landslide risk on a Pan-European scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8660, https://doi.org/10.5194/egusphere-egu24-8660, 2024.

EGU24-9197 | Orals | NH9.1 | Highlight

A global stochastic flood risk model for any climate scenario 

Oliver Wing, Niall Quinn, Malcolm Haylock, Conor Lamb, Rhianwen Davies, Nick Sampson, Izzy Probyn, James Daniell, Florian Elmer, Johannes Brand, and Paul Bates

Modelling flood hazards at large scales – both uniform frequency hazard maps and event simulations whose frequency varies in space – is a relatively new scientific endeavour. Data and computation constraints have historically necessitated either a more local focus to modelling efforts, or the building of proof-of-concept global-scale models whose fidelity inhibits most practical applications.

Here, we present a global climate-conditioned flood catastrophe model; the culmination of decades of research into scaling inundation modelling, the incorporation of climate change, and synthetic event generation. 30 m resolution global maps representing fluvial, pluvial, and coastal flooding for given return periods were simulated using a hydrodynamic model with sub-grid channels whose inputs were defined using regional flood frequency analyses. Change factors from climate model cascades were flexibly used to perturb the local flood frequency a given flood map represents. Separately, a 10,000-year-long set of synthetic events were simulated using a conditional multivariate statistical model fitted to global fluvial-pluvial-coastal reanalysis data. The empirical return period of a given event is used to sample the corresponding flood map return period in order to build a long synthetic series of floods.

With a global exposure model built using a top-down approach – downscaling capital stock models to high-resolution satellite-derived land-use and building height data – and a global vulnerability model derived from an extensive review of modelling and engineering literature, we demonstrate the calibration and validation of the global risk model. We also show the software challenges overcome to run this model, as well as to enable end-users to flexibly calculate the flood risk of their own exposures in the Oasis Loss Modelling Framework.

How to cite: Wing, O., Quinn, N., Haylock, M., Lamb, C., Davies, R., Sampson, N., Probyn, I., Daniell, J., Elmer, F., Brand, J., and Bates, P.: A global stochastic flood risk model for any climate scenario, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9197, https://doi.org/10.5194/egusphere-egu24-9197, 2024.

EGU24-9533 | Posters on site | NH9.1

Modeling inland flooding caused by tropical cyclones in the US using AI-based synthetic events 

Nans Addor, Natalie Lord, Balaji Mani, Thomas Loridan, Naoki Mizukami, Jannis Hoch, and Malcolm Haylock

Tropical cyclones (TCs) are a key driver of flooding in the US. Here we present a modeling approach to simulate their associated inundation footprint under present and future climate and generate the hazard data necessary to run a CAT model. 

We developed an AI-based model called RainCyc that learns from the TC rainfall fields dynamically generated by the WRF model as well as from observations. RainCyc is orders of magnitudes faster than WRF, meaning that orders of magnitude more events can be simulated for the same computational cost. This is essential to capture the tail of the distribution, i.e., to generate synthetic events over a period longer than the longest return period of interest. Future boundary conditions for RainCyc are provided by the CESM2-LENS ensemble, which covers the 21st century under SSP370 levels of warming using 50 model realizations started from slightly perturbed initial conditions.

The rainfall fields produced by RainCyc are used to simulate inland flooding, i.e., pluvial and fluvial. The inundation footprint for each event is generated by sampling from flood hazard maps simulated by the LISFLOOD hydraulic model. The sampling for pluvial is informed by RainCyc precipitation, while for fluvial, it relies on hydrological simulations driven by the FUSE and mizuRoute models. FUSE is a frugal rainfall-runoff model that is run at 10km over a domain encompassing each event to generate its associated runoff. This runoff is then provided to the vector-based routing model mizuRoute to generate flow time series from which peak flow is extracted and used to sample fluvial hazard maps.

We present this modeling framework and test it for thousands of years of synthetic events under present and future climate. We benchmark the hydrological simulations for historical events using runs from other models, including GloFAS. We also test the ability of the framework to generate synthetic events spanning the intensities covered by hazard maps for a wide range of return periods.

How to cite: Addor, N., Lord, N., Mani, B., Loridan, T., Mizukami, N., Hoch, J., and Haylock, M.: Modeling inland flooding caused by tropical cyclones in the US using AI-based synthetic events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9533, https://doi.org/10.5194/egusphere-egu24-9533, 2024.

Understanding the relationship between extreme temperature events and health outcomes necessitates integration of hazard and impact data. International databases of societal impacts from disasters serve as an important data source for empirical cross-country analyses. Yet, detailed and precise estimations of the hazard magnitude of these impact records are often lacking. Physical metrics play a pivotal role in, for instance, statistical analyses and exposure assessments.

In bridging this gap, our work leverages recent advancements in geocoding of disaster records alongside high-resolution meteorological datasets to construct an inventory of a diverse range of health-related climate metrics. Our global analysis spans over 200 records of extreme temperature disasters from the past fifty years. By doing so, we unveil insights into the properties of these disastrous heat- and cold-waves. We furthermore explore differences across space, time, metrics, and data sources. This work highlights the potential of utilizing this integrated approach to extract meaningful information from historical disaster records in global databases, aiding climate resilience and public health strategies.

How to cite: Lindersson, S. and Messori, G.: Quantifying health-related climate metrics of extreme temperature disasters: An international analysis over five decades, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9798, https://doi.org/10.5194/egusphere-egu24-9798, 2024.

EGU24-10060 | ECS | Posters on site | NH9.1

The Impact of El Niño-Southern Oscillation on Tropical Cyclone Risks 

Juner Liu, Simona Meiler, David N. Bresch, and Carmen B. Steinmann

The El Niño-Southern Oscillation (ENSO) is the most important inter-annual signal of climate variability on the planet. It affects many natural hazards including tropical cyclones (TCs), known for causing severe economic losses and many fatalities. Although research efforts have examined ENSO’s influence on TC characteristics including frequency and intensity in different basins, the transfer of these findings to global TC risk assessments has yet to be undertaken. This covers aspects such as damage to physical assets and the number of people affected. However, this is complicated by many uncertainties, such as landfall location (heterogeneous distribution of exposures) and vulnerability definitions. To bridge this gap, we assess TC risks on physical assets and affected people under ENSO’s influence and quantify related sources of uncertainty on a global scale.

We analyze TC risks during El Niño and La Niña years, using three types of TC datasets: the International Best Track Archive for Climate Stewardship (IBTrACS), probabilistic tracks generated by a random walk algorithm (IBTrACS_p), and synthetic TCs generated by a statistical-dynamical TC model (MIT). Furthermore, we quantify the sensitivity of input variables, such as the ENSO threshold, and assess uncertainties arising from TC landfall location using uniform exposure values. The outcomes regarding ENSO-conditioned TC risks can potentially improve seasonal TC risk prediction, thus benefiting policymakers and the insurance industry alike. Additionally, the results contribute to more balanced and diversified (multi-)hazard risk portfolios by accounting for ENSO as an important common modulator of spatially compounding hazards.

How to cite: Liu, J., Meiler, S., Bresch, D. N., and Steinmann, C. B.: The Impact of El Niño-Southern Oscillation on Tropical Cyclone Risks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10060, https://doi.org/10.5194/egusphere-egu24-10060, 2024.

EGU24-10905 | ECS | Posters on site | NH9.1

Flooding Under Climate Change in Small Island Developing States 

Leanne Archer, Jeffrey Neal, Paul Bates, Natalie Lord, and Laurence Hawker

Small Island Developing States are a group of 57 island nations and territories which are some of the most at-risk places to the impacts of climate change globally, particularly from changes in hydrometeorological hazards such as flooding. Despite this, little research has quantified present day flood hazard and population exposure in small islands, let alone how this may change as global temperatures continue to rise. Until now, this was due to the insufficient data to produce high-resolution flood hazard and population exposure estimates for a wide range of possible scenarios at such a large scale. Following the release of Fathom’s Global Flood Model 3.0, in this work we combine global flood hazard estimates for coastal, fluvial, and pluvial flood hazard at ~30m flood model resolution to estimate present day population exposure to flooding across all 57 small islands. We also investigate how flood hazard and population exposure changes under three climate scenarios: two plausible climate change scenarios (SSP1-2.6 and SSP2-4.5), and a plausible worst-case climate scenario (SSP5-8.5). We assess how present day flood hazard and exposure differs across the island typologies, and how these are projected to change under the different climate change scenarios. We also compare population exposure with vulnerability metrics to explore how population exposure to flooding and vulnerability interact. The results of this analysis aim to improve understanding regarding the range of plausible estimates of current and future population exposure to flooding in Small Island Developing States. These results will help inform adaptation to more extreme flood risk in Small Island Developing States under current and future climate change.

How to cite: Archer, L., Neal, J., Bates, P., Lord, N., and Hawker, L.: Flooding Under Climate Change in Small Island Developing States, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10905, https://doi.org/10.5194/egusphere-egu24-10905, 2024.

EGU24-13847 | Posters on site | NH9.1

Development of a Comprehensive Exposure-at-Risk Map for Europe: Integrating Coinciding Natural Hazards and Exposure Metrics 

James Daniell, Andreas Schaefer, Judith Claassen, Johannes Brand, Timothy Tiggeloven, Bijan Khazai, Trevor Girard, Annika Maier, Benjamin Blanz, Nikita Strelkovskii, Jaroslav Mysiak, Marleen de Ruiter, Wiebke Jaeger, and Philip Ward

The development of an Exposure-at-risk map for Europe that encompasses multiple coinciding natural hazards builds upon many previous attempts and existing portals such as TIGRA, TEMRAP, ESPON, JRC DRMKC, and GIRI to name a few, which have primarily focused on examining a few single hazards and limited exposure.
The novelty of this approach lies in its integration of a myriad of hazards into a single, cohesive framework. The European Hazard Map is constructed using data from various sources, covering geophysical hazards (earthquakes, volcanoes, landslides), meteorological hazards (winds, convective storms, storms), hydrological hazards (river/pluvial floods), climatic overlaps (bushfires, droughts), and biological hazards. These hazards are modelled using both stochastic and probabilistic methods as well as historical reanalysis, offering a robust and comprehensive view of potential risks.
The exposure component of this map is constructed around a handful of key Europe-wide metrics, encompassing aspects crucial to the European multi-sector context. These include tourism-based metrics such as domestic and international expenditure, hotel statistics, employment figures, as well as broader economic indicators like capital stock (particularly focusing on buildings), GDP, and critical infrastructure related to transport and energy. Additionally, agricultural production and seasonal population variations are factored in. These metrics are pivotal in assessing the potential impact of various hazards, including but not limited to earthquakes, tsunamis, winds, floods, landslides, tornadoes, hail, droughts, and bushfires.
This map has been developed as part of the MYRIAD-EU project, a multi-hazard initiative, and is built using open data sources and risk analytics within the project. A significant feature of this map is its ability to demonstrate temporal and spatial overlaps. This capability allows for the visualization of combined events or the combined impact of different exposure-hazard overlaps, depending on whether the output is stochastic or probabilistic. The interface of this map serves as a crucial gateway to the MYRIAD-EU multi-hazard software scorecard approach. It also plays a pivotal role in identifying overlapping hazards within the EU, enabling better preparedness and response strategies.
In summary, this Exposure-at-risk map for Europe is a significant advancement in the field of hazard assessment and risk management. It integrates a multitude of hazards and exposure metrics, offering a comprehensive and detailed view of potential risks across Europe. This map is not only a tool for current risk assessment but also a foundation for future research and development in this critical area of study.

How to cite: Daniell, J., Schaefer, A., Claassen, J., Brand, J., Tiggeloven, T., Khazai, B., Girard, T., Maier, A., Blanz, B., Strelkovskii, N., Mysiak, J., de Ruiter, M., Jaeger, W., and Ward, P.: Development of a Comprehensive Exposure-at-Risk Map for Europe: Integrating Coinciding Natural Hazards and Exposure Metrics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13847, https://doi.org/10.5194/egusphere-egu24-13847, 2024.

EGU24-13864 | Orals | NH9.1

Connecting the dots: teleconnection of global floods and their association with climate variability 

Yixin Yang, Long Yang, Qiang Wang, and Gabriele Villarini

A fundamental question in global hydrology is how global floods behaved in the past and are expected to behave in the future. Previous site-specific analyses might offer locally relevant insights, but little is known about how floods are connected in space and time as well as their synchronous responses to climate variability at the global scale. Here we carry out empirical analyses based on a comprehensive dataset of annual maximum flood peak series from 4407 stream gaging stations. We establish the link between any two stream gages if their annual maximum flood peak discharges are significantly correlated and the dates of their occurrences are sufficiently close (using event synchronization and complex network). Our results identify notable remote links of annual flood peak series over western Canada/US (e.g., upper Missouri River basin), northern Europe (e.g., Kemijoki River basin), southern China (e.g., middle Yangtze River basin), and northern South America (e.g., Amazon River basin). Annual flood peak series are linked to their local neighbors (within a distance of 4500 km) over eastern United States, central Europe, and eastern Australia. Remote links highlight the spatial dependence of riverine floods at the global scale. These links are dictated by the oscillation of dominant climate modes over the Pacific Ocean (e.g., El Niño Southern Oscillation, Pacific Decadal Oscillation) and their resultant anomalous atmospheric circulation patterns. Local flood clusters are more responsive to region-specific atmospheric forcings. The complex flood network plays an important role in regulating the dynamic behaviors of flood hazards. Our results offer new insights into global flood hydrology and their connections with large-scale climate forcings.

How to cite: Yang, Y., Yang, L., Wang, Q., and Villarini, G.: Connecting the dots: teleconnection of global floods and their association with climate variability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13864, https://doi.org/10.5194/egusphere-egu24-13864, 2024.

Floods constantly occur in San Miguel de Ibarra's urban setting each year. Situated on the slopes of the Imbabura volcano, an integral component of the UNESCO Global Geopark Imbabura, this Ecuadorian city boasts an invaluable cultural and natural heritage. However, it has experienced multiple adverse impacts due to the overflow of rivers and streams. In 2022, an inventory of floods was compiled for the Geopark, revealing the persistent recurrence of this phenomenon within the city. Consequently, it became imperative to gather historical and contemporary data from diverse sources such as public institutions (GAD Ibarra 2023), digital newspapers, social networks, and aerial imagery (IGM 2014) to discern patterns and establish correlations related to these occurrences (SNGRE 2023).

In this way, the acquired information spanning the period from 1965 to the present, insights were gained into the distribution of flood-prone zones and their correlation with paleochannels. Additionally, discernment was achieved regarding alterations in land-use planning attributable to urban expansion in the city, which, in turn, contributes to the heightened susceptibility to floods. This meticulous analysis unveiled specific areas within the city consistently affected by such hazards, elucidating these events' characteristics and the ensuing damage to both public and private properties. The current publication presents preliminary findings utilized in the estimation of flood risk.

Keywords: Paleochannels, floods, Ibarra, Imbabura, Imbabura UNESCO Geopark

References:

GAD Ibarra (2023) Cartography of Ibarra canton at several scales

IGM (2014) Cartography of Ibarra canton 1:5.000

IGM (2023) Historical imagery of flights in Ecuador at several scales

SNGRE (2023) Data Base Events SNGRE. Period 2010 to 2023

How to cite: Torres-Ramírez, R.: Paleochannels and their correspondence with floods in the 21st century. Case study of Ibarra city, Imbabura, Ecuador., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14423, https://doi.org/10.5194/egusphere-egu24-14423, 2024.

Abstract: The incidences of earthquakes in the north Indian state of Uttarkhand are broadly associated with the presence of active fault viz. Main Central Thrust and Alaknanda Fault in the north, Moradabad Fault and Himalayan Frontal Thrust in the southern margin, Martoli Thrust and Indus Suture in the eastern, Mahendragarh Dehrdun Fault in the west. Uttarakhand falls under Seismic Zone IV and V and has been struck by several devastating earthquakes viz. 1905 Kangra earthquake of MW 7.8, 1991 Uttarkashi earthquake of MW 6.8 and 1999 Chamoli earthquake of MW 6.5 with maximum MM Intensity of IX observed in near-source region causing widespread damage and destruction in the study region. Uttarakhand region has undergone unprecedented development and population growth, emphasizing the importance of analysis of Seismic Hazard to ensure safe and secure progress in this seismically vulnerable region. Consideration of seismicity patterns, fault networks and similarity in the style of focal mechanisms yielded 10 areal seismogenic sources with additional active tectonic features in 0-25km, 25-70km, and 70-180km hypocentral depth ranges, along with 15 Ground Motion Prediction Equations for the tectonic provinces of Uttarakhand region yielding Probabilistic Peak Ground Acceleration (PGA) at engineering bedrock  seen to vary from 0.36g to 0.63g for 475years of return period which places the region in the moderate to high hazard zone necessitating a case study for site-specific seismic characterization of the region. Seismic site classification has been done based on an enriched geophysical, in-situ downhole, geotechnical database and surface geoscience attributes comprising of Geology, Geomorphology, Landform and Topographic Gradient derived shear wave velocity categorizes the region into Site Classes E, D4, D3, D2, D1, C4, C3, C2, C1, B and A. Using the input ground motion at bedrock level obtained from stochastic simulation for the near-source earthquakes, nonlinear site response analyses have been performed using PLAXIS-2D software package wherein site amplification has been mapped which is seen to vary in the range of 1.02 to 2.86. Surface-consistent probabilistic seismic hazard in terms of Peak Ground Acceleration (PGA) for a return period of 475 years has been assessed for the study region by convolving site amplification with bedrock hazard thus predicting a variation of PGA in the range of 0.51-1.61g. Additionally, assessment of liquefaction potential of the terrain and seismic hazard microzonation have been done for Dehradun city to identify areas with varying level of ground shaking and its associated liquefaction phenomenon during earthquakes, enabling the development of site-specific building codes and land-use regulations. The results of this investigation are expected to play vital roles in the earthquake–related disaster mitigation and management of the region.

How to cite: Bind, A. P. and Nath, S. K.: Site-specific Seismic Hazard Assessment of Uttarakhand, India with special emphasis on Liquefaction Potential  modelling of the terrain and Seismic Hazard Microzonation of Dehradun City, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14677, https://doi.org/10.5194/egusphere-egu24-14677, 2024.

EGU24-16095 | ECS | Posters on site | NH9.1

Do catchment characteristics drive extreme discharge tail behavior in the Meuse catchment? Insights from 1,040 years of synthetic discharge data.  

Anais Couasnon, Laurène Bouaziz, Ruben Imhoff, Hessel Winsemius, Mark Hegnauer, Niek van der Sleen, Robert Slomp, Leon van Voorst, and Henk van den Brink

Understanding extreme discharge behavior is of importance for flood design and risk management. For example, estimates of large extreme discharge return periods such as the 100-year return period or higher are often needed as a basis for flood hazard maps or dike design. Yet, frequency analysis based on decade-long discharge records show a large uncertainty for these frequencies, among others due to the statistical uncertainty from the distribution parameters.  This is not the case for the shape parameter, a key parameter that describes the upward or downward curvature of the tail of the distribution and thus an indicator of extreme discharge behavior. 

This study provides robust estimates of the shape parameter by using the 1,040 years of synthetic daily discharge generated for the Meuse catchment as part of the EMfloodResilience project from the Interreg Euregio Meuse-Rhine program. The spatially-distributed hydrological model wflow_sbm, calibrated and validated for the Meuse catchment, is forced with 16 synthetic climate ensembles of 65 years representative for the current climate from the physically-based KNMI regional climate model RACMO climate model at a daily and hourly time step. The annual maxima (AM) from hydrological years (Oct-Sep) are retrieved from these continuous time series, and a GEV distribution is fit to the AM. We observe a clear spatial pattern of the shape parameter across the Meuse catchment. Using this large dataset of shape parameters, we also review the possible reasons for the different tail behavior obtained with respect to rainfall statistics, catchment characteristics and river systems following the In doing so, we aim to bridge the extreme value statistical modelling with our current understanding of the extreme hydrological signatures present in the catchment.

How to cite: Couasnon, A., Bouaziz, L., Imhoff, R., Winsemius, H., Hegnauer, M., van der Sleen, N., Slomp, R., van Voorst, L., and van den Brink, H.: Do catchment characteristics drive extreme discharge tail behavior in the Meuse catchment? Insights from 1,040 years of synthetic discharge data. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16095, https://doi.org/10.5194/egusphere-egu24-16095, 2024.

EGU24-16556 | ECS | Posters on site | NH9.1

Coastal flood risks in Europe in the context of sea-level rise: methods and preliminary results from the CoCliCo project 

Vincent Bascoul, Rémi Thiéblemont, Jeremy Rohmer, Elco Koks, Joël De Plaen, Daniel Lincke, Hedda Bonatz, and Goneri Le Cozannet

Present days and future coastal flooding is a key concern for Europe due to sea-level rise, storm surges and the importance of infrastructure at risk in low-lying areas. To support adaptation, information on future risks such as people exposed and economic damages are required. The CoCliCo project aims to contribute responding to this need by informing users about coastal risks via an open-source web platform. This platform aspires to improve decision-making on coastal risk management and adaptation in Europe.

Here, we present the methods used in CoCliCo to compute risks and provide early results of risk calculations at the European scale. The results take the form of costs calculated for different flooding scenarios on different infrastructures (residential buildings, roads...) as a function of flood water levels. Flood water levels are determined for each infrastructure based on flood modelling. Then, using vulnerability curves, a damage associated with the type of infrastructure as a function of the water level is assigned. The damage ratio then is used to calculate the cost of flooding. Coastal risk can also be presented in social terms, by assessing the number of people potentially affected by flooding. The results are illustrated for two case studies: Dieppe and Hyère in France using detailed flood modelling and complemented by preliminary results for Europe. Our results are compared results from with previous studies.

Finally, flood risk projections will be presented for several return periods at different scales and for different integrated scenarios considering climate change and associated socio-economic pathways as well as different adaptation options. These results will be made available on the CoCliCo platform.

How to cite: Bascoul, V., Thiéblemont, R., Rohmer, J., Koks, E., De Plaen, J., Lincke, D., Bonatz, H., and Le Cozannet, G.: Coastal flood risks in Europe in the context of sea-level rise: methods and preliminary results from the CoCliCo project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16556, https://doi.org/10.5194/egusphere-egu24-16556, 2024.

Tropical cyclones are events responsible for the costliest meteorological catastrophes. On average per year over the last decade, they have affected 20 million people, with estimated economic losses US$51.5 billion (Krichene et al., 2023). These consequences reduce the economic growth of the affected countries (Berlemann & Wenzel, 2018). Take Jamaica, for instance, where annual damages caused by tropical cyclones are estimated at 0.5%, reaching up to 10% of the Gross Domestic Product (Adam & Bevan, 2020).

The climatology of tropical cyclone, defined as characteristics averaged over years, controls parameters like tracks, intensification, number of storms, all crucial for induced hazards (winds, precipitation, storm surge and waves). In recent years, anomalous tropical cyclones have impacted the coasts worldwide. In 2023, hurricane Otis, without precedent, rapidly intensified off the coast of the coast of Acapulco (Mexico), resulting in at least 52 deaths and estimated damage exceeding 10 billion USD. The track of tropical cyclone Kenneth struck areas of Mozambique where no previous tropical cyclone had impacted before, resulting in 45 casualties and $100 million in damage (Mawren et al., 2020). The future of tropical cyclones is impregnated with uncertainty and is a matter of concern, which have motivated the recent advance in this topic. Several authors asseverate an increase in intensity, reduce in frequency (Bloemendaal, et al., 2022; T. Knutson et al., 2020; T. R. Knutson et al., 2010), and their poleward displacement (Studholme et al., 2022). However, the global study of the displacement of tropical cyclones and their characteristics due to the migration of storms has not been integrated into large-scale adaptation planning.

This study identifies regions affected by the displacement of storms in the North Atlantic at the municipal administration level. Analysing characteristics under two climatology periods—a baseline climate (1980-2017) and a future high-emission climate scenario, Shared Socioeconomic Pathway SSP8.5 (2015-2050)—we used synthetic tracks (Bloemendaal, et al., 2022) generated with a model based on STORM  (Bloemendaal et al., 2020). Four Global Climate Models (CMCC, CNRM, EC-Earth, and HadGEM3) were examined to evaluate uncertainty, focusing on frequency, intensity, and critical parameters such as size, translation speed, track complexity, residence time in front of the coast, and relative direction to the shoreline.

This study identifies hotspots where tropical cyclone characteristics are spatially displaced, increasing the exposure to tropical cyclones in these regions. For example, the Canary Islands in Spain show that hurricanes of category 1, in present conditions, have a return period of 215 years, reducing to 62 years in the SSP8.5 scenario. This is in line with the recent records, the Hermine storm in 2022 almost impacted their coasts. The results raise questions about our public policies for future adaptation. In areas historically unaffected and unprepared for tropical cyclones, the corresponding government may lack and require prevention systems for tropical cyclones, such as warning alarms, reducing subsidies for coastal development or implementing disaster relief policies. 

How to cite: Odériz, I. and Losada, I.: Implications of the displacement of tropical cyclones for public policies in the North Atlantic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17338, https://doi.org/10.5194/egusphere-egu24-17338, 2024.

EGU24-17738 | ECS | Orals | NH9.1

Complex emergencies: drivers of the humanitarian impacts of climate-related disasters 

Ellen Berntell, Nina von Uexkull, Tanushree Rao, Frida Bender, and Lisa Dellmuth

Climate-related disasters such as floods, droughts and storms often pose significant threats to human livelihoods, especially in developing countries. The extreme weather events often lead to destroying of shelter, harming of crops and livestock as well as fueling of conflicts, and the threat to human livelihoods are likely to increase due to climate change. While we know that climate change and conflict interact and reinforce each other, less is known in the context of natural disasters and disaster aid. In this paper we address this gap by studying how hazard severity, disaster exposure and drivers of vulnerability interact to produce humanitarian impacts, and if the delivery of emergency disaster aid alleviates these impacts. We do this by generating meteorological hazard severity measurements based on the reanalysis dataset ERA5, comparable across different climate-related disaster types, allowing us to study drivers of vulnerability to climate-related hazards. Secondarily, we study the role of aid allocation on limiting disaster mortality and displacement, with the results having broad implications for the understanding of disaster impacts and aid effectiveness.

How to cite: Berntell, E., von Uexkull, N., Rao, T., Bender, F., and Dellmuth, L.: Complex emergencies: drivers of the humanitarian impacts of climate-related disasters, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17738, https://doi.org/10.5194/egusphere-egu24-17738, 2024.

EGU24-17751 | ECS | Orals | NH9.1 | Highlight

A New Method to Compile Global Multi-Hazard Event Sets 

Judith Claassen, Elco E. Koks, Timothy Tiggeloven, and Marleen C. de Ruiter

This study presents a new method, the MYRIAD-Hazard Event Sets Algorithm (MYRIAD-HESA), that compiles historically-based multi-hazard event sets. MYRIAD-HESA is a fully open-access method that can create multi-hazard event sets from any hazard events that occur on varying time, space, and intensity scales. In the past, multi-hazards have predominately been studied on a local or continental scale, or have been limited to specific hazard combinations, such as the combination between droughts and heatwaves. Therefore, we exemplify our approach by compiling a global multi-hazard event set database, spanning from 2004 to 2017, which includes eleven hazards from varying hazard classes (e.g. meteorological, geophysical, hydrological and climatological). This global database provides new scientific insights on the frequency of different multi-hazard events and their hotspots. Additionally, we explicitly incorporate a temporal dimension in MYRIAD-HESA, the time-lag. The time-lag, or time between the occurrence of hazards, is used to determine potentially impactful events that occurred in close succession. Varying time-lags have been tested in MYRIAD-HESA, and are analysed using North America as a case study. Alongside the MYRIAD-HESA, the multi-hazard event sets, MYRIAD-HES, is openly available to further increase the understanding of multi-hazard events in the disaster risk community. The open-source nature of MYRIAD-HESA provides flexibility to conduct multi-risk assessments by, for example, incorporating higher resolution data for an area of interest.

How to cite: Claassen, J., Koks, E. E., Tiggeloven, T., and de Ruiter, M. C.: A New Method to Compile Global Multi-Hazard Event Sets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17751, https://doi.org/10.5194/egusphere-egu24-17751, 2024.

EGU24-17874 | ECS | Orals | NH9.1

An evaluation of the use of regional climate model data applied to extreme precipitation in the Meuse basin 

Leon van Voorst, Henk van den Brink, and Anais Couasnon

Understanding of hydrological and meteorological extremes is essential for flood risk management and flood protection. A primary focus in these professions is adequate estimation of extreme events that correspond to large return periods. Hydrological and meteorological observations only go back several decades, complicating frequency analysis of these large extremes. Capturing the tail behaviour of extremes is particularly challenging with such short records, resulting in high uncertainty of large precipitation and discharge extreme estimates.

This study proposes an alternative strategy for hydrological and meteorological frequency analysis. Long timeseries obtained from regional climate models are used to replace short observational datasets, leading to a substantial reduction of the statistical uncertainty of meteorological and hydrological extreme estimates. The approach was tested in the Meuse basin as part of the EMFloodresilience project, evaluating meteorological extremes from 16 synthetic ensembles of 65 years from the RACMO regional climate model (forced by the EC-EARTH global climate model). Hydrological extremes are analysed in a subsequent study from Rijkswaterstaat and Deltares, by forcing the wflow discharge model with the RACMO climate model dataset.

The study results reveal that bias-corrected model data is climatologically comparable to observational averages and extremes, exhibiting similar GEV location and scale parameters. Revealing a previously unexamined range of extremes, the model data offers a more plausible method to estimate the tails of annual extremes and likely provides a better estimate of the corresponding GEV shape parameter. Spatially, the model-derived parameter shows greater consistency across different sub-catchments of the Meuse basin compared to observations, suggesting a more robust insight in the tail behaviour of extremes. Additionally, a distinct separation between GEV distributions of summer and winter events is observed, indicating a transition in magnitude dominance from winter to summer maxima and possibly the presence of a double population. The existence of such a double population is difficult to obtain from observations, but can have an enormous impact on the return values of summer extremes. This emphasizes the need for further research on this area for adequate flood management.

How to cite: van Voorst, L., van den Brink, H., and Couasnon, A.: An evaluation of the use of regional climate model data applied to extreme precipitation in the Meuse basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17874, https://doi.org/10.5194/egusphere-egu24-17874, 2024.

EGU24-18718 | ECS | Orals | NH9.1

When one becomes many: Including complex channel systems in large scale flood models 

Laurence Hawker, Jeffrey Neal, Michel Wortmann, Louise Slater, Yinxue Liu, Solomon H. Gebrechorkos, Julian Leyland, Philip J. Ashworth, Ellie Vahidi, Andrew Nicholas, Georgina Bennett, Richard Boothroyd, Hannah Cloke, Helen Griffith, Pauline Delorme, Stuart McLelland, Andrew J. Tatem, Daniel Parsons, and Stephen E. Darby

Over 70% of flood events recorded in the past two decades in the Global Flood Database and WorldFloods dataset have occurred in locations where complex channel systems occur. Here we define complex channel systems as parts of the river network that diverge, such as bifurcations, multi-threaded channels, canals and deltas. Yet, large scale flood models have, until now, used only single-threaded networks due to the lack of a river network that reflects complex channel systems . Therefore, these large-scale models fundamentally misrepresent the physical processes in these often highly populated areas, leading to sub-optimal estimates of flood risk.

Using the new Global River Topology (GRIT) dataset, a global bifurcation and multi-directional river network (Wortmann et al. 2023), we extend the river channel bathymetry estimation routine of Neal et al. (2021) to model multi-channels with LISFLOOD-FP. We compare the multi-thread model results to observations and to previous versions of LISFLOOD-FP using a single-threaded river network in the Indus, Mekong and Niger rivers at 1 arc second (~30m). By using GRIT, we find marked improvements in model results, observing better connectivity to areas of the floodplain that are far from the main channel and more channel floodplain interactions in wetlands. This work paves the way to further our understanding of global flood risk and to finally consider the diverse, evolving nature of geomorphologically active river networks. As this work progresses, we will continue to model a typology of bifurcations and multi-directional rivers to help further our understanding of the significance of complex river systems.

Neal, J., Hawker, L., Savage, J., Durand, M., Bates, P., & Sampson, C. (2021). Estimating river channel bathymetry in large scale flood inundation models. Water Resources Research57(5), e2020WR028301.

Wortmann, M., Slater, L., Hawker, L., Liu, Y., & Neal, J. (2023). Global River Topology (GRIT) (0.4) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.7629908

How to cite: Hawker, L., Neal, J., Wortmann, M., Slater, L., Liu, Y., Gebrechorkos, S. H., Leyland, J., Ashworth, P. J., Vahidi, E., Nicholas, A., Bennett, G., Boothroyd, R., Cloke, H., Griffith, H., Delorme, P., McLelland, S., Tatem, A. J., Parsons, D., and Darby, S. E.: When one becomes many: Including complex channel systems in large scale flood models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18718, https://doi.org/10.5194/egusphere-egu24-18718, 2024.

EGU24-20386 | ECS | Orals | NH9.1

Slow-moving landslide exposure increases with population pressure 

Joaquin Vicente Ferrer and Oliver Korup

Slow-moving landslides can cause damage to structures and infrastructure and result in thousands of casualties, if they fail catastrophically. Landslide motion may accelerate after prolonged rainfall, and with alterations to their surface hydrology caused by urbanization. As populations grow in mountainous regions, there will be more direct interactions between communities expanding onto landslides. Yet, the lack of systematic data has precluded a global overview of exposure. We address this by compiling a global database of 7,764 large landslides (>0.1 km2 in area) reported to be slow-moving. Here, we assess the presence of human settlements in 2015 and estimate exposure across IPCC regions with projected landslide risk. We estimate that 9% of landslides in a given basin are occupied by human settlements. On 1195 km2 slow-moving landslides, settlement footprints total 55 km2 and cover an average of 12%, relative to the landslide area. We show regional influences of exposure to floods, average steepness, and urbanization on exposure across basins. Our estimates of exposure in East Asia (EAS) show the most credibility across regions facing growing landslide and flood risk by the IPCC. Apart from Central Asia, we find that urbanization in a basin increases the relative number of landslides inhabited. Furthermore, we find that regions with mountain risks projected to increase have highest uncertainty in our assessment.

How to cite: Ferrer, J. V. and Korup, O.: Slow-moving landslide exposure increases with population pressure, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20386, https://doi.org/10.5194/egusphere-egu24-20386, 2024.

EGU24-20522 | ECS | Orals | NH9.1

Global assessment of human exposure to sea-level rise to 2300 

Jack Heslop, Robert Nicholls, Caridad Ballesteros Martinez, Daniel Linke, and Jochen Hinkel

The PROTECT project [1] includes a probabilistic integrated assessment of global population exposure to coastal flood hazard under climate-induced sea-level rise (SLR) over the next three centuries (to 2300). The assessment synthesises present-day datasets on population distribution [2], low lying coastal elevations [3] and extreme tides [4] with probabilistic projection datasets of population [5] and sea level [6] to 2300. For the scenarios considered (SSP1-2.6 & SSP2-4.5) and at a global scale, the median human exposure to coastal flood hazards grows substantially but then peaks in the early 2200s and subsequently slowly declines by 2300, despite continued rise in sea level.

Previous assessments have primarily focussed on shorter timeframes [2], typically to 2100, while it is widely acknowledged that even if temperatures are stabilised, sea levels are almost certain to continue to rise for many centuries [7][8][9]. Stakeholder workshops carried out with practitioners under the umbrella of PROTECT [10] and literature reviews [11][12] highlight the importance of extending sea-level rise information beyond 2100, to support strategic coastal adaptation and management, land-use planning, and critical infrastructure design.

Recent advancements in long term socio-economic modelling [13][5] now provide projections of global population and GDP at country level to 2300. These have already been applied to long-term risk assessments for other climate sectors [13][5][14].

For this assessment, the global coastline was split into ~29,000 segments, each assigned an extreme tide curve (from the COAST-RP dataset [4]) and a hypsometric curve, generated from a global terrain model [3] and present-day population distribution [2]. The hypsometric curves aggregate the total land-area and population at each elevation, including consideration of hydraulic connectivity to the coastline. This gives the land area and population that would be exposed at a given coastal flood level (up to 20mAMSL) for each coastal segment.

When sea-level scenarios [6] (SSP1-2.6 & SSP2-4.5) and socio-economic data [5] are combined, the human exposure and land area exposure to coastal flood hazard under a chosen extreme tide return period (or the annual average based on the event-exposure curve) is calculated.

This approach facilitates efficient computations, sampling across probabilistic data, and providing robust statistics at a high spatial resolution compared to traditional methods. The outputs at each coastal segment can be aggregated to sub-national, national, or the global scale.

In this analysis, it is found that the median exposure of people to coastal flood hazards increases fivefold to a peak in the early 2200s and subsequently slowly declines to 2300 in both SSPs, despite the continued rise in sea level. For the 80th percentile population exposure grows even more (10- to 11-fold) but then stabilises rather than declines. These results reflect the interplay of sea level and demography with fall in global population in the latter half of the assessment period and are contrary to conventional wisdom. This analysis shows that in addition to sea-level rise, it is important to consider demographic trends when considering coastal futures.

Figure 1. Probabilistic annual average global population exposure to coastal flood hazard

References exceed the word limit so not included

How to cite: Heslop, J., Nicholls, R., Ballesteros Martinez, C., Linke, D., and Hinkel, J.: Global assessment of human exposure to sea-level rise to 2300, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20522, https://doi.org/10.5194/egusphere-egu24-20522, 2024.

EGU24-21315 | Orals | NH9.1

Wildfire Risk Assessment under present and future climate at national scale: a pan european approach 

Farzad Ghasemiazma, Giorgio Meschi, Andrea Trucchia, and Paolo Fiorucci

The authors present a framework designed to model wildfire risk and the future projection of wildfire risk patterns, also in view of climate change scenarios. The adopted modeling framework is inherently multi scale, giving results at national scale, after a data gathering process developed at regional / supranational scale. The risk assessment comprises the computation of susceptibility, hazard, exposures, and damage layers. Machine learning techniques are used to assess the wildfire susceptibility and hazard at regional level, analogously to [1, 2]. To this end, a two-models approach has been adopted. The first model, based on the Random Forest Classifier, is trained at pan-European level to capture the climate variability of the European continent and related fire regimes. Building upon the outcome of this model, a wildfire susceptibility map representative for the historical
conditions at pan-European level is produced and used in input of a second machine learning model, to provide results at national level. The strength of this model lies in using high-resolution downscaled climate data and annual temporal resolution, with the objective of computing a high resolution annual susceptibility map for the specific region. This approach facilitates the generation of annual outcomes for both historical and future conditions, using the climate projections available in the ISIMIP framework. The result of five different climate models and three climate change scenarios have been used to estimate the average annual losses due to wildfires. The wildfire hazard has been evaluated through empirical approaches, building a wildfire hazard classes map combining fuel type/severity maps with wildfire susceptibility. Then, a burning probability is estimated for each hazard class: a statistical analysis on historical wildfires at pan-European level has been performed in order to retrieve the annual relative burned area per hazard class. The method allows to estimate the average annual probability to be affected by a fire given a wildfire event. Several exposed elements were used to estimate the losses ranging from infrastructure to forest and roads: Global Earthquake Model [3] provides a dataset featuring economic values under both present and future conditions across five categories of infrastructures at European level. JRC, OpenStreeMap, and Copernicus provide information on the presence of roads and forests. Empirical vulnerability functions establish a link between severity maps, the presence of exposed elements, and their economic value, leading to the estimation of potential damage maps. The assessment of average annual losses involves coupling spatial information on average annual probability with potential damage maps. This approach allows for the evaluation of average values across various future timeframes associating a variance accounting for both the year to year and climate models’ variability. Results have been produced at national level for several countries characterized by different wildfire regimes, land cover and climate, such as Croatia, Romania and Bulgaria.

How to cite: Ghasemiazma, F., Meschi, G., Trucchia, A., and Fiorucci, P.: Wildfire Risk Assessment under present and future climate at national scale: a pan european approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21315, https://doi.org/10.5194/egusphere-egu24-21315, 2024.

GM5 – Humans, Life, and Landscapes

EGU24-1472 | Posters on site | GM5.2

Minimum duration of a Miocene lake phase in the hyperarid core of the Atacama Desert, Chile 

Stephanie Scheidt, Stefanie Koboth-Bahr, Volker Wennrich, Richard Albert, Julia L. Diederich-Leicher, Barbara N. Blanco-Arrué, Niklas Leicher, Lena Wallbrecht, Pritam Yogeshwar, and Martin Melles

In 2017, sediment cores were drilled in the PAG clay pan in the hyperarid core of the Atacama Desert as part of CRC1211 (Earth - Evolution at the Dry Limit). The aim of the endeavour was to deduce the climate history of this region from the sedimentary record. The core composite established from the individual core runs goes down to a depth of approx. 52 metres. The core is composed of three major lithological facies. Below 29.2 metre composite depth (mcd), the core consists of fine-grained silty-clayey sediments, which are cyclically interspersed with layers of gypsum. These sediments are interpreted as lacustrine strata. They are overlain by coarse sediments with clasts up to several centimetre in size, which are referred to as colluvial sediments. The upper around seven metre are formed by fine-grained clay pan sediments. The geochronological framework of the core was investigated using various dating methods, most of which were unable to provide reliable ages. For the lake sediments no absolute ages could be obtained. However, U-Pb ages of zircons of a tephra layers, at the transition between the lake and coarse-grained facies suggest a Miocene age for the lake deposits. To constrain the age framework of the lake phase, magnetic polarity stratigraphy was combined with an analysis of gypsum cyclicity that is interpreted as an orbital signal. Here, we present and discuss the results of the study, which provides a new age model for this lacustrine part of the core and thus, sheds new light on an extended pluvial phase in the Atacama Desert.

How to cite: Scheidt, S., Koboth-Bahr, S., Wennrich, V., Albert, R., Diederich-Leicher, J. L., Blanco-Arrué, B. N., Leicher, N., Wallbrecht, L., Yogeshwar, P., and Melles, M.: Minimum duration of a Miocene lake phase in the hyperarid core of the Atacama Desert, Chile, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1472, https://doi.org/10.5194/egusphere-egu24-1472, 2024.

EGU24-2118 | ECS | Orals | GM5.2

The entanglement of microorganisms and mineral matrices in a hyperarid environment – observations by SEM imaging and biomarker analysis from the Atacama Desert 

Isabel Prater, Helge Mißbach-Karmrodt, Kathrin König, Daniel Friedrich, and Christine Heim

In hyperarid deserts like the Atacama Desert, biota face additional aggravations beside the dryness, e.g. high UV radiation and often high surface temperatures. However, even under these extreme conditions, diverse microbial communities thrive on and within the sediment and interact strongly with their mineral substrate. Common habitats for microbial communities in this environment are fog-receiving surfaces and endolithic zones within evaporite crusts. Endolithic microorganisms are highly adapted to both the substrate and severe water limitations and colonize protected cracks, niches, and caverns within translucent rocks and crusts. They have the potential to alter mineral components and stimulate the formation of secondary minerals as they redistribute moisture and potentially extract crystal water. Processes like these are the starting point of pedogenesis and, even if proceeding extremely slowly, affect the shape of the surface.

To elucidate the relationship of microbial communities with the mineral matrix, we investigated the biogeochemical traces of microbial communities and their spatial distribution on and within gypsum and halite crusts from different regions within the Atacama Desert in Northern Chile. We combined imaging techniques (scanning electron microscopy, SEM) and biomolecular methods (gas chromatography-mass spectrometry, GC-MS/MS and nuclear magnetic resonance, NMR) to obtain a deeper insight into the entanglement of microorganisms and evaporitic crusts. Tight interactions of bacteria and fungi with the mineral matrix were revealed by SEM. Short-chain membrane fatty acids (C14-C18) indicated recent bacterial activity in all samples analyzed. Extracellular short-chain acids (C6-C12) and carbohydrates of the extracellular polymeric substances (EPS) make up to 75% of the total biomass within evaporites which point to efficient desiccation buffers and protection mechanisms against UV radiation. Furthermore, the sticky EPS leads to the biochemical stabilization of mineral aggregates by agglutination, which was also visible with SEM.

How to cite: Prater, I., Mißbach-Karmrodt, H., König, K., Friedrich, D., and Heim, C.: The entanglement of microorganisms and mineral matrices in a hyperarid environment – observations by SEM imaging and biomarker analysis from the Atacama Desert, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2118, https://doi.org/10.5194/egusphere-egu24-2118, 2024.

EGU24-2204 | Orals | GM5.2 | Highlight

On the tectonic and climatic controls to the evolutionary patterns of Andean plant groups 

Esteban Acevedo-Trejos, Jean Braun, Benedikt Ritter, Tim Böhnert, Adeniyi Mosaku, and Hannah Davies

Life, climate, and landforms interact to shape the biodiversity patterns we observe in Earth’s Mountain regions. Plausible tectonic and climatic explanations have emerged to explain, for example, the evolutionary patterns of Andean plant groups. However, it remains unclear how different tectonic and climatic histories affect the evolution of Andean flora on geological time scales. Here we present the results of numerical experiments using our coupled speciation and landscape evolution model to investigate how tectonics and climate interact to produce distinct evolutionary histories in the Andes. To address this, we first calibrated our model using a Bayesian inversion algorithm with observations of present-day topography and precipitation, paleo-elevation reconstructions, and thermochronological data to calibrate three scenarios with different uplift histories, which were designed based on the literature and named as propagating and compound. The propagating scenario considers the west-to-east propagation of a Gaussian-shaped wave of uplift, which has been shown to adequately approximate the evolution of plateaus. The compound scenario divides the landscape into 6 geomorphic regions, each with its uplift history. Additionally, we tested a third scenario as a control, in which we maintained the present-day topography for the course of the simulation (ca. 80 Myr), which we named static. We ran the eco-evolutionary component of our model in these three distinct uplift scenarios, covering the mountain building of the Andes for the past 80 Myrs, and designed a series of ensemble simulations in which we randomly assigned dispersal and mutation variability to recreate different assemblages with distinct evolutionary histories and evaluate if the different scenarios produce any consistent speciation patterns comparable to reported time-calibrated phylogenies of various plant groups. We found that the uplift scenario with a more complex uplift history, i.e. compound, better agrees with the different observations. This scenario also showed increased diversification during the Miocene (23-4.5 Ma), a feature observed in several Andean plant groups. This demonstrates how diversification constraints obtained from phylogenetic studies can be used to discriminate between conflicting uplift scenarios for the Andes/Altiplano that have been suggested by paleo-altimetry estimates and other geological observations.

How to cite: Acevedo-Trejos, E., Braun, J., Ritter, B., Böhnert, T., Mosaku, A., and Davies, H.: On the tectonic and climatic controls to the evolutionary patterns of Andean plant groups, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2204, https://doi.org/10.5194/egusphere-egu24-2204, 2024.

EGU24-3506 | Posters on site | GM5.2

Paleocene surface exposure ages imply an early development of hyperaridity in the Atacama Desert 

Benedikt Ritter, Steven A. Binnie, Finlay M. Stuart, Derek Fabel, Richard Albert, Volker Wennrich, and Tibor J. Dunai

The (hyper-) arid climate of the Atacama Desert preserves traces of ancient landforms. Clusters of cosmogenic 21Ne exposure ages of pebbles from Early Miocene sediment surfaces indicate the preservation and continuous exposure (low to no erosive surface activity) since the Late Eocene, with distinct phases of low fluvial activity and deposition during the Neogene. A reduction of significant fluvial activity since ~10 Ma, and the complete absence since ~1-2 Ma, indicate extreme hyperarid conditions.  Single exposure histories of Paleocene age, with age clusters during the Eocene and Oligocene, demonstrate remarkable landscape stability throughout the Cenozoic. Phases of fluvial activity, i.e. the end of a fluvial period and the beginning of continuous exposure to cosmic rays, coincide closely with trends and aberrations in regional and global Cenozoic climate variability.

How to cite: Ritter, B., Binnie, S. A., Stuart, F. M., Fabel, D., Albert, R., Wennrich, V., and Dunai, T. J.: Paleocene surface exposure ages imply an early development of hyperaridity in the Atacama Desert, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3506, https://doi.org/10.5194/egusphere-egu24-3506, 2024.

EGU24-3594 | Orals | GM5.2

Understanding a complex ecosystem: Tillandsiales in the hyperarid core of the Chilean Atacama Desert 

Marcus Koch, Eric Stein, and Dietmar Quandt

Tillandsia landbeckii is a “core species” in the hyper arid parts of the Atacama Desert colonized by few vascular plants only and this species is totally depending on fog occurrence as the most important source of water. Tillandsia landbeckii is a key element of the most prominent vegetation type of the hyperarid Chilean Atacama core. Epiarenic growth, growing on bare sand and lacking any root system, evolved five times independently in the genus Tillandsia during the past 5 my in the Peruvian-Chilean Desert system and lay the ground to build up unique ecosystems, with Tillandsia purpurea representing the Peruvian vicariant species. The onset of this parallel evolution may be considered as a temporal land-mark for the evolution of those fog-dependent ecosystems of the hyperarid core Atacama. Footprints of evolutionary diversification of present-day gene pools of T. landbeckii go back roughly 500,000 years, and present-day biogeographic distribution pattern is mostly shaped due to environmental changes since the last 22,000 years and the Last Glacial Maximum (LGM). The genetic set-up is surprisingly characterized by ancestral gene pools, “frozen” hybrid genotypes and clonal propagation and dispersal. This observation feeds into our hypothesis that phenotypic plasticity - contributing to plant fitness and survival in space and time - is limited on individual level, but a genetic mosaic on population- and landscape level is compensating this by a mixture of different “frozen” geno- and phenotypes, thereby allowing to cope rapidly with environmental change at the extreme limits of plants´ life. A multi-disciplinary approach combining evidence from different disciplines (plant biology, evolutionary biology, microbiology, climatology, geology, geomorphology and remote sensing technology) aims to unravel the complex interplay of biotic and abiotic factors to elaborate on our understanding of life occuring at the limits of growth due to the lack of water. We introduce the complex phylogeographic history of the species in Chile and introduce a mechanistic/biological growth model exploring environmental - biotic and abiotic - parameters. For comparative analysis on metapopulation level three regions have been selected in Chile (North near Arica, Centre near Iquique, South near Caldera) for detailed comparative in-situ and ex-sito analyses. 

How to cite: Koch, M., Stein, E., and Quandt, D.: Understanding a complex ecosystem: Tillandsiales in the hyperarid core of the Chilean Atacama Desert, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3594, https://doi.org/10.5194/egusphere-egu24-3594, 2024.

EGU24-6493 | ECS | Posters on site | GM5.2

Dating of upwelling archives in the eastern South Pacific: a multiproxy approach in the Late Neogene Bahía Inglesa Formation, North-Central Chile 

Tiago Freire, Fatima Zohra Bouhdayad, Gerald Auer, Rafael Carballeira, Fabrizio Lirer, Niklas Leicher, Volker Wennrich, Richard Albert, Axel Gerdes, Bárbara Blanco-Arrué, Pritam Yogeshwar, Stephanie Scheidt, Jassin Petersen, Sven Nielsen, Marcelo Rivadeneira, and Patrick Grunert

In modern oceans, upwelling processes are responsible for high biological productivity and low sea surface temperatures at coastal zones. Upwelling may have intensified during the late Neogene in the eastern South Pacific due to the strengthening of the Humboldt Current System. Records of Neogene coastal upwelling are preserved in outcrops along the coast of north-central Chile (~ 26°S to 28°S) as diatomaceous mudstone deposits of the Neogene Bahía Inglesa Formation. To place such records in a broader paleoceanographic context, however, their stratigraphic assessment still needs refinements. Our work presents a multiproxy dataset to provide a stratigraphic framework for the Bahía Inglesa Formation at Quebrada Tiburón (27°42' S, 70°59' W), one of the southernmost outcrops of diatomaceous mudstone. Our approach is based on tephrochronometry, strontium isotope chronology (mollusk shells 87Sr/86Sr), and calcareous nannoplankton, diatom, and planktonic foraminifera biostratigraphy. Zircon crystals separated from a volcanic ash layer at the base of the sequence were analyzed by laser ablation ICP-MS for U-Pb dating. The youngest cluster of five concordant zircon crystallization ages indicates a tephra deposition after 8.68 ± 0.15 Ma. The 87Sr/86Sr analyses were performed on an oyster and a pectinid from sandstones underlying the diatomaceous mudstone using high-precision MC-ICP-MS measurements. The corrected and adjusted 87Sr/86Sr ratios resulted in 8.12 ± 0.40 Ma and 6.10 ± 0.25 Ma ages. The microfossil biostratigraphy was based on First (FAD) and Last Appearance (LAD) datums of biostratigraphic markers from the diatomaceous mudstone. The presence of mainly Miocene diatoms (e.g., Actinocyclus ingens, Cavitatus joseanus, and Nitzschia fossilis) and the planktonic foraminifera Neogloboquadrina acostaensis (sinistral) indicate a Tortonian age for the base of the diatomaceous mudstone. The Messinian-Zanclean boundary was identified in the middle interval of the mudstone by the disappearance of the calcareous nannoplankton species Calcidiscus pataecus and the appearance of Helicosphaera sellii and Umbilicosphaera sibogae. This interpretation is supported by the continuity and limit of the diatoms Actinocyclus ellipticus, Azpeitia nodulifer, and Coscinodiscus plicatus overlapping with Hemidiscus cuneiformis. A Zanclean age was attributed to the upper part of the mudstone sequence due to the co-occurrence of the calcareous nannoplankton species Reticulofenestra pseudoumbilicus and Sphenolithus moriformis, the diatoms Actinocyclus ellipticus, the co-occurrence of the diatoms Nitzschia fossilis and Shionodiscus oestrupii, and the planktonic foraminifera Globoconella miotumida and Sphaeroidinellopsis seminulina. The following sandstones contain Pliocene mollusks. Although inconsistencies between biostratigraphic data of taxa from different microfossil groups were observed (likely due to the lack of a local biozonation appropriate for the upwelling context), our dataset suggests a late Tortonian to Zanclean (8.68 to 3.5 Ma) age constraint for the succession and late Messinian to Zanclean (6.09 to 3.5 Ma) age for the diatomaceous mudstone. Further studies will apply our stratigraphic constraints for paleoenvironmental reconstructions. This research is part of the CRC 1211 “Earth-Evolution at the dry limit” project, funded by the German Research Foundation (DFG).

How to cite: Freire, T., Bouhdayad, F. Z., Auer, G., Carballeira, R., Lirer, F., Leicher, N., Wennrich, V., Albert, R., Gerdes, A., Blanco-Arrué, B., Yogeshwar, P., Scheidt, S., Petersen, J., Nielsen, S., Rivadeneira, M., and Grunert, P.: Dating of upwelling archives in the eastern South Pacific: a multiproxy approach in the Late Neogene Bahía Inglesa Formation, North-Central Chile, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6493, https://doi.org/10.5194/egusphere-egu24-6493, 2024.

EGU24-6736 | Posters on site | GM5.2

Early Pliocene coastal upwelling off central Chile (Coquimbo Formation, Tongoy) 

Patrick Grunert, Rafael Carballeira, Stephanie Scheidt, Tiago Menezes Freire, Sven N. Nielsen, Marcelo M. Rivadeneira, Fatima Zhora Bouhdayad, and Jassin Petersen

Diatom-rich sediments exposed along the coastline of northern and central Chile are prominent archives of coastal upwelling properties in the Neogene. Unlocking these archives is fundamental to evaluate the potential significance of changing sea surface temperatures for landward moisture transport and palaeoclimatic fluctuations in the Atacama Desert. One of the southernmost occurrences of Neogene diatom-rich sediments is known from a series of quebradas, i.e. seaward ravines, on the Tongoy Pensinsula (30.3°S). The diatomaceous muds, previously correlated with the Middle to Upper Miocene, have been deposited in the Tongoy Paleobay. Here we present new bio- and magnetostratigraphic data from a 3.5 m-thick section of diatomaceous muds in the Quebrada Las Salinas together with a preliminary assessment of the depositional environment.

While calcareous microfossils are absent, the sample material is rich in silicious microfossils. Diatoms are the predominant group, while silicoflagellates, ebridians, radiolarians, and sponge spicules contribute to a lesser extent. Co-occurrences of the diatom species Nitzschia fossilis and Shionodiscus oestrupii constrain the diatomaceous muds to an age < 5.7-5.9 Ma. Together with normal magnetic polarity at the base of the section, the lowermost age limit is further refined to an Early Pliocene age < 5.23 Ma (base of the Thvera subchron). Occurrences of the diatom species Rouxia californica in the upper part of the diatomaceous muds suggest an upper age limit within the Zanclean. The results demonstrate for the first time that diatomaceous muds in the Tongoy Paleobay extend well into the Pliocene. Comparison with previous studies suggests that diatom-rich deposits in the study area may be highly diachronous within and between quebradas.

The microfossil assemblages suggest that coastal upwelling was prevalent in the Tongoy Paleobay during the Early Pliocene. Diatom assemblages are dominated by planktonic and meroplanktonic taxa that prefer cold, nutrient-rich surface waters of coastal upwelling such as Chaetoceros and its resting spores, Thalassionema nitzschoides, Coscinodiscus spp., and Actinoptychus senarius. Cold surface waters are also indicated by high abundances of Distephanus spp. in the silicoflagellate assemblages. Benthic taxa are very rare, suggesting water depths of 100-150 meters. The Early Pliocene diatom assemblages more closely resemble those of today’s upwelling in Eastern equatorial Pacific and off the northern Peruvian continental margin than off central Chile. This may suggest a range of surface temperatures at least comparable to or even warmer than off central Chile today, and significantly enhanced primary productivity. This preliminary assessment will be further evaluated through detailed statistical analysis.

This study is part of the CRC 1211 “Earth-Evolution at the dry limit” project, funded by the Deutsche Forschungsgemeinschaft (DFG).

How to cite: Grunert, P., Carballeira, R., Scheidt, S., Menezes Freire, T., Nielsen, S. N., Rivadeneira, M. M., Bouhdayad, F. Z., and Petersen, J.: Early Pliocene coastal upwelling off central Chile (Coquimbo Formation, Tongoy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6736, https://doi.org/10.5194/egusphere-egu24-6736, 2024.

EGU24-8271 | ECS | Posters on site | GM5.2

Quantifying processes in Earth’s Critical Zone in the Atacama Desert by combined luminescence and sedimentological approaches 

Linda Maßon, Svenja Riedesel, Simon Matthias May, Johanna Steiner, Stephan Opitz, and Tony Reimann

The central Atacama Desert is generally considered the driest non-polar desert on Earth. Given the fog-related moisture availability along the northern Chilean Coastal Cordillera and the increasing precipitation towards the Andean Cordillera, it is an ideal area to explore the transition of biotically to abiotically driven subsurface soil processes (e.g., soil turbation and weathering) in the Earth’s Critical Zone (ECZ). So far, no geochronological framework exists for these subsurface soil processes, and the factors controlling these processes are still unknown. Here we combine feldspar single grain luminescence dating with detailed sedimentological and geochemical analyses to improve our understanding of factors, processes, and time scales involved in subsurface soil processes in the Atacama Desert, ultimately contributing to decipher geomorphodynamics and landscape evolution under hyper arid conditions. While single-grain luminescence dating has successfully been applied to infer sediment transport and mixing processes in various geological settings [e.g., Reimann et al., 2017], luminescence dating of Atacama Desert sediments has proven to be challenging and time-consuming. It has been shown that establishing a standardised growth curve (SGC) for single-grain feldspar post-infrared infrared stimulated luminescence measurements reduces the measurement time considerably [Li et al., 2018]. In this regard, we previously showed that SGCs are only suitable for Atacama Desert feldspars if special modifications are made [Maßon et al., under review].

Based on a combination of the sedimentological and geochemical analyses of samples from nine sediment profiles of 35-180 cm depth, four dust traps and luminescence dating techniques using the modified SGC approach of Maßon et al. [under review] we explore biotic and abiotic subsurface soil processes in the ECZ along two W-E-oriented climatic transects in the north and south of the central Atacama Desert. The northern transect focusses on the transition from the Central Depression to the Precordillera, where biotic components in the ECZ increase with increasing humidity and elevation. The southern transect reflects the transition from the fog-influenced Coastal Cordillera to the Central Depression, where biotic components in the ECZ decrease with decreasing fog-frequency and increasing elevation. We present first results of the successful combination of the refined SGC method from Maßon et al. [under review] and detailed sedimentological and geochemical results to disentangle and infer the processes and rates of sediment deposition and surface evolution, as well as post-depositional subsurface soil processes in both transects. Furthermore, we test if different soil formation processes (e.g., incorporation of aeolian dust vs. in-situ weathering), identified using a combination of sedimentological and geochemical analysis of samples from both sediment profiles and dust traps, can be traced by specific luminescence vs. depth fingerprints. Our preliminary results indicate surface and soil activity during the Late Pleistocene and Holocene even in the abiotic sections of the transects. This suggests that Earth surface dynamics and soil processes such as vertical particle transport and the incorporation of aeolian dust in the most hyperarid parts of the Atacama Desert – virtually independent from flowing water and plant activity - are more active than previously expected, although acting on long time and subtle spatial scales.

How to cite: Maßon, L., Riedesel, S., May, S. M., Steiner, J., Opitz, S., and Reimann, T.: Quantifying processes in Earth’s Critical Zone in the Atacama Desert by combined luminescence and sedimentological approaches, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8271, https://doi.org/10.5194/egusphere-egu24-8271, 2024.

EGU24-8995 | ECS | Posters on site | GM5.2

Alluvial deposition at the Skeleton Coast, northern Namibia: chronology and spatial patterns 

Joel Mohren, Janek Walk, Dominik Brill, Julian Krieger, Wolfgang Römer, Alicia Medialdea, Anna Nguno, and Frank Lehmkuhl

Quaternary topography sculpting along the Skeleton Coast of northern Namibia has predominantly been governed by long-term (hyper-)aridity and a rather absence of tectonic activity. The long-term prevalence of such environmental conditions has been favoured by the overall geographical setting, as the Skeleton Coast is situated at the western passive continental margin of the African continent, close to the southern tropic. As a consequence, the main episode of denudation and relief building in this region is usually believed to have taken place during the Cretaceous. However, Quaternary sediment successions and modern records on flash floods hold proof for a highly active environment post-dating the Mesozoic. Given the important role climate and its variability are presumed to play for sediment redistribution during the Quaternary, alluvial deposits found along this coast-parallel stretch may be regarded as valuable paleoclimate archives, potentially reflecting indications for climate-controlled pulses of sediment aggradation. The present-day environmental conditions limit the decay of such landforms, while promoting the persistence of a long-stretched, coast-parallel dune belt obstructing fluvial sediment conveyance towards the Pacific. The dune belt, termed Skeleton Coast erg, represents aeolian, coast-parallel sediment transport, and covers older alluvial surfaces. Altogether, this special setting bears the potential to investigate linkages between pulses of wetter episodes, the different modes of erosion, and spatiotemporal patterns of alluvial deposition.

We seek to identify these patterns on a regional scale and hence apply a combined, spatially extensive approach including geochronological and (hydro-)morphometric analyses of mapped alluvial fans (n = 52) along the Skeleton Coast and catchments draining the hinterland (n = 67). The drainage is mostly confined by the Great Escarpment to the east, providing similar (modern) rainfall regimes of less than ~150 mm yr-1 on average. Preliminary results obtained from the morphometric analyses indicate that typical power-law correlations between catchment and fan metrics exist, providing evidence for intact source-sink communication pathways for climate signals from the feeding catchments towards the coast. However, significant spatial fan confinement, e.g. caused by the coastal erg, is very likely to affect the morphometric relationships and landscape reconstruction efforts based on these data. Hence, establishing a regional geochronological framework integrating over timescales relevant for major episodes of alluvial deposition is crucial for our study aims. First results obtained from optically stimulated luminescence (OSL) dating provide indications for significant Holocene and Late Pleistocene sediment conveyance, as previously reported for other study areas across Namibia. Additionally, preliminary 10Be exposure dating yields Middle Pleistocene ages for alluvial surfaces in the vicinity of the Skeleton Coast erg. Such old ages could reflect the impact of orbital forcing on fan activity and may imply that landscape formation processes temporally integrating over timescales relevant for our analyses are archived in both the fan and catchment morphology. Investigating polyphase fans will help to further increase the spatiotemporal resolution of alluvial deposition patterns to unravel Quaternary climatic conditions and climate variability along the Skeleton Coast of Namibia.

How to cite: Mohren, J., Walk, J., Brill, D., Krieger, J., Römer, W., Medialdea, A., Nguno, A., and Lehmkuhl, F.: Alluvial deposition at the Skeleton Coast, northern Namibia: chronology and spatial patterns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8995, https://doi.org/10.5194/egusphere-egu24-8995, 2024.

EGU24-9360 | Posters on site | GM5.2

Studies of Nitrate Deposits in the Atacama Desert, Chile: Insights from Triple Oxygen Isotopes and Strontium Isotopes 

Camila Riffo Contreras, Guillermo Chong, Swea Klipsch, Kathi Deußen, Carsten Münker, and Michael Staubwasser

The Atacama Desert in northern Chile is the oldest and driest place on Earth, characterized by continuous arid conditions since mid-Tertiary times and hyperarid since the Pliocene. These extreme aridity conditions make this region an ideal environment for the accumulation of highly soluble salts, including the Nitrate Deposits which are of economic importance and scientific research. Despite almost two centuries of exploitation and research, a comprehensive generic model fitting the extremely variable settings and types of Nitrate Deposits has not been universally accepted.

Geochemical and isotopic evidence suggests predominant atmospheric deposition of sea salt and ozone oxidation products with diagnostic Δ17O anomalies in the nitrates and sulfates deposition. Current models invoke two genesis scenarios: (1)episodic rains and salts washing-down from the soil surface followed by reprecipitation due to evaporation that is assumed to concentrate nitrates and associated salts in sedimentary continental sequences, and (2)salts dissolution in low-O2 groundwater with subsequent precipitation after capillary activity and evaporation. However, certain Nitrate Deposits, like pure nitrate veins and manto-type up to 1m thick cutting through sedimentary or volcanic rocks at depths of 25m, cannot be easily explained through these two mechanisms. They are too thick and deep to be easily related to capillarity evaporitic concentration from dilute groundwater because the capillary fringe in sediments rarely exceeds 2m. On the other hand, in some cases they are related to gypsum veins, suggesting the possibility of redissolution of primary nitrate deposits by hydrothermal, seismic activity, or precipitations, and brines emplaced into fracture systems, fault planes and stratigraphic boundaries.

This study investigates a possible origin of Nitrate Deposits by analyzing triple oxygen isotopes in nitrates and sulfates. The triple oxygen isotope values in nitrates offer constraints on the formation processes, such as bacterial denitrification and atmospheric photochemical reactions, thereby giving clues to interpret the possible origin and evolution of these deposits.

Sulfates are the dominating salt in soils of the Atacama Desert and are present in Nitrate Deposits. Thenardite and mirabilite appear in several stratigraphic sequences of saline soils between 5-65 cm below the surface. Gypsum is present in continental sequences mainly as gypsysols, but our main interest is when it occurs in groups of sulfate veins associated with nitrates cutting volcanic rocks. Triple oxygen isotope analysis of sulfate veins helps to distinguish between secondary atmospheric sulfate, deposition of sea spray, biological sulfate reduction, and reoxidation. For thenardites, appear to fall on a unique trend in the multi-isotope plots, tending towards zero in ∆17OSO4 and very low δ18OSO4 and δ34SSO4, extrapolating this trend to ∆17OSO4=0‰ yields a hypothetical hydrothermal end member.

Additionally, the strontium isotopes (87Sr/86Sr) in Nitrate Deposits offer further insights. The strontium isotope composition reflects interactions between nitrate-bearing fluids (high and low temperature) and host rocks. Comparing these isotopic ratios with known geological formations aids in detecting potential nitrate sources.

The combination of these isotopic systems offers a comprehensive approach to understanding and provides new ideas about the origin and evolution of these still enigmatic deposits in the Atacama Desert.

How to cite: Riffo Contreras, C., Chong, G., Klipsch, S., Deußen, K., Münker, C., and Staubwasser, M.: Studies of Nitrate Deposits in the Atacama Desert, Chile: Insights from Triple Oxygen Isotopes and Strontium Isotopes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9360, https://doi.org/10.5194/egusphere-egu24-9360, 2024.

EGU24-9660 | Posters on site | GM5.2 | Highlight

Terracettes in the hyperarid Atacama Desert – fog-driven landforms of Holocene age? 

Simon Matthias May, Dirk Hoffmeister, Dominik Brill, Stephan Opitz, and Olaf Bubenzer

Terracettes are quasi-contour parallel step-like microtopographic features consisting of repetitious platform-type benches and slope-type risers and are documented from hillslopes in a range of climates. While a number of studies emphasize their formation by trampling of livestock and grazing animals (cat steps or stock trails), it has been shown that terracette formation may be explained by a number of natural processes, including solifluction or freeze-thaw processes, slumping, soil creep, or vegetation control. Despite this variability and the controversy about their origin, these micro-terraces may alter hillslope soil moisture and vegetation patterns, infiltration and surface hydrology, as well as downslope sediment flux, potentially disconnecting downslope conveyance processes of surface runoff. Given the process mechanisms discussed in these previous studies, the extremely hyperarid climate of the central Atacama Desert in northern Chile may be regarded as unfavourable for terracette formation; here, livestock and grazing animals are absent, moisture availability is extremely limited, and frost processes in elevations below ~1000 m asl are rare. Nevertheless, here we report on terracette-covered slopes in the central Atacama Desert located close to the Rio Loa canyon in the Coastal Cordillera that represents an important inland pathway for coastal fog. Based on sedimentological, geochemical (e.g., micro-X-ray fluorescence) and geomorphological investigations, thin section analyses, UAV-derived aerial photos, soil moisture monitoring as well as post-infrared infrared stimulated luminescence (post-IR IRSL) dating, we present geomorphological, chronostratigraphical and soil hydrological characteristics of the terracettes and discuss potential drivers of terracette formation. Our observations suggest a combination of wind and fog-related moisture supply, particularly during several day-long periods of sustained high relative humidity and fog occurrence, as the key driver for terracette formation, adding to the various processes discussed in previous studies. Post-IR IRSL dating of terracette platform sediments suggests a late Pleistocene to Holocene formation of the terracettes, thereby illustrating the role of fog in driving hillslope dynamics and shaping the desert landscape in the Atacama under past and present hyperaridity.

How to cite: May, S. M., Hoffmeister, D., Brill, D., Opitz, S., and Bubenzer, O.: Terracettes in the hyperarid Atacama Desert – fog-driven landforms of Holocene age?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9660, https://doi.org/10.5194/egusphere-egu24-9660, 2024.

The Atacama Desert, known for its hyper-arid climate, occasionally experiences extreme rainfall events, significantly impacting desert hydrology and land-surface evolution. Climate records suggest past interruptions of hyper-aridity, notably during the mid-Pliocene. Understanding hydrological changes during the wet phases is hindered by data scarcity. To address this, we use dynamically downscaled precipitation data from a regional climate model (WRF) and offline Atmospheric and Hydrological-Sediment Modeling Systems (AHMS-SED) to analyze water and sediment discharge during extreme rainfall events under the present-day and mid-Pliocene conditions. Calibration and validation were performed for the Salado River Basin and Paranal clay pan, where relatively more data were recorded. Using AHMS-SED simulations, we explore the long-term land-surface responses to extreme precipitation events and examine the impacts of flash floods on sediment transport under different climate scenarios. This study also provides insights into the effects of extreme rainfall events on desert hydrology and land-surface evolution in a future warmer climate.

How to cite: Jiang, C. and Shao, Y.: Model Characterization of Hydrological and Fluvial Sediment Transport Processes in Present-day and Mid-Pliocene Climate Conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10039, https://doi.org/10.5194/egusphere-egu24-10039, 2024.

EGU24-10611 | ECS | Posters on site | GM5.2

Fog controls biological cycling of soil phosphorus in the Coastal Cordillera of the Atacama Desert 

Xiaolei Sun, Wulf Amelung, Erwin Klumpp, Janek Walk, Ramona Mörchen, Christoph Böhm, Simon Matthias May, Federica Tamburini, and Roland Bol

Soils in hyper-arid climates, such as the Chilean Atacama Desert, show indications of past and present forms of life despite extreme water limitations. We hypothesize that fog plays a key role in sustaining life. In particular, we assume that fog water is incorporated into soil nutrient cycles, with the inland limit of fog penetration corresponding to the threshold for biological cycling of soil phosphorus (P). We collected topsoil samples (0‒10 cm) from each of 54 subsites, including sites in direct adjacency (< 10 cm) and in 1 m distance to plants, along an aridity gradient across the Coastal Cordillera. Satellite-based fog detection revealed that Pacific fog penetrates up to 10 km inland, while inland sites at 10‒23 km from the coast rely solely on sporadic rainfall for water supply. To assess biological P cycling we performed sequential P fractionation and determined oxygen isotope of HCl-extractable inorganic P (δ18OHCl-Pi). Total P (Pt) concentration exponentially increased from 336 mg kg-1 to a maximum of 1021 mg kg-1 in inland areas ≥ 10 km. With increasing distance from the coast, soil δ18OHCl-Pi values declined exponentially from 16.6‰ to a constant 9.9‰ for locations ≥ 10 km inland. Biological cycling of HCl-Pi near the coast reached a maximum of 76‒100%, which could only be explained by the fact that fog water predominately drives biological P cycling. In inland regions, with minimal rainfall (< 5 mm) as single water source, only 24±14% of HCl-Pi was biologically cycled. We conclude that biological P cycling in the hyper-arid Atacama Desert is not exclusively but mainly mediated by fog, which thus controls apatite dissolution rates and related occurrence and spread of microbial life in this extreme environment.

How to cite: Sun, X., Amelung, W., Klumpp, E., Walk, J., Mörchen, R., Böhm, C., May, S. M., Tamburini, F., and Bol, R.: Fog controls biological cycling of soil phosphorus in the Coastal Cordillera of the Atacama Desert, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10611, https://doi.org/10.5194/egusphere-egu24-10611, 2024.

EGU24-10679 | ECS | Posters on site | GM5.2

Mechanisms and timing of haloturbation in the northern Atacama Desert derived from a subsurface network of calcium sulphate wedges  

Aline Zinelabedin, Svenja Riedesel, Benedikt Ritter, Joel Mohren, Steven A. Binnie, Maria Wierzbicka-Wieczorek, Simon M. May, Tibor J. Dunai, Stefan Heinze, and Tony Reimann

The presence of subsurface wedges and polygonal patterned grounds on the Earth’s surface is usually associated with cycles of cryogenic subsurface processes in periglacial environments. However, similar though calcium sulphate-dominated structures are found at numerous sites in the central Atacama Desert (N Chile), including particularly well-developed wedges in the subsurface of the Aroma alluvial fan in the Central Depression. Here, the subsurface wedges are covered by a ~20 cm thick, gypsum‑dominated surface crust, impeding the detection of the polygonal structures on the present-day Aroma fan surface. Due to high salt contents in the local alluvial fan deposits, the wedges are thought to be preliminary formed by haloturbation and may represent a hyperarid equivalent to periglacial wedge structures. The dominance of calcium sulphate phases in the vertical lamination of the wedges, accompanied by clastic minerals, is revealed by X-ray diffraction analysis. Hence, haloturbation is likely to be the key driver of wedge formation, caused by significant volumetric changes in the deposits and soil cracking induced by swelling and shrinking during calcium sulphate phase transitions.

Geochronological information on subsurface wedge growth under conditions of extreme water scarcity is crucial for using these laminated wedges as an additional terrestrial palaeoclimate archive for arid to hyperarid environments in the northern Atacama Desert. Information on the processes and timing of wedge-polygon formation may also be important for interpreting wedge-polygon formation in other water-limited environments such as on Mars. Therefore, in order to unravel the mechanisms and governing environmental conditions of calcium sulphate wedge and crust formation at the Aroma site, we here present mineralogical, geochemical, and sedimentological data of wedge and crust material. In addition, our chronological investigations aimed at constraining the age of wedge growth activity by using a combination of feldspar luminescence dating and meteoric 10Be dating techniques as well as 239Pu concentration measurements. Based on a minimum age model of our luminescence dating results, wedge growth was last active at the Pleistocene-Holocene boundary. The presence of the overlying gypsum-dominated surface crust could reflect an environmental change from slightly marginally ‘wetter’ conditions to present-day hyperaridity, which ultimately inhibited wedge-polygon formation during the Holocene. However, 239Pu concentrations measured in surface crust samples indicate recent downward migration of soil fines through the crust body. Therefore, it remains an open question whether surface sediments and/or moisture can penetrate the surface crust to promote processes of wedge-polygon formation even under present hyperarid conditions, leading to wedge growth over longer time scales.

How to cite: Zinelabedin, A., Riedesel, S., Ritter, B., Mohren, J., Binnie, S. A., Wierzbicka-Wieczorek, M., May, S. M., Dunai, T. J., Heinze, S., and Reimann, T.: Mechanisms and timing of haloturbation in the northern Atacama Desert derived from a subsurface network of calcium sulphate wedges , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10679, https://doi.org/10.5194/egusphere-egu24-10679, 2024.

EGU24-11939 | ECS | Posters on site | GM5.2

Assessing the last “large scale fluvial modification” across the hyperarid Atacama Desert, northern Chile 

Janek Walk, Joel Mohren, Ariane Binnie, Dominik Brill, Helmut Brückner, Viktor Schaubert, Andrés Quezada, and Frank Lehmkuhl

During the last decade, a consensus has been widely established about an Early Miocene onset of hyperaridity characterizing the Atacama Desert located in the Andean forearc region in northern Chile. Prevailing hyperarid conditions were interrupted by many pluvial episodes of varying duration and spatial extent. In contrast to the onset of hyperaridity, highly discrepant interpretations persist regarding the last “large scale fluvial modification” (Ritter et al., 2018) of the Atacama Desert. While terminal aggradation of the coastal alluvial fans is constrained at several sites to the Last Glacial Maximum (MIS 2), followed by Holocene progradation to the shore, chronological constraints for last major fluvial activity throughout the inland desert scatter between the Late Miocene and Middle Pleistocene. The types of investigated sedimentary archives differ and many studies have a local focus. Instead, a systematic assessment from the hyperarid coast (W) to the footslopes of the Precordillera (E) is yet lacking. We therefore mapped 84 alluvial fan systems with small (<25 km²) source areas along a latitudinal transect at ~21°S. The last-abandoned, widely distinguishable fan surface generations (S1) and subrecent incised channels of five alluvial fan systems was further systematically sampled for 10Be cosmogenic nuclide exposure dating of surface pebbles. Morphometric results indicate a significant positive dependence of both fan area and fan slope on the catchment area and can further be interpreted as the result of (palaeo)climatic effects on the fan systems. Initial 10Be exposure dating reveals Middle Pleistocene terminal aggradation of the S1 fan generation, confirming the younger interpretations of the last “large scale fluvial modification” of the Atacama Desert. Forthcoming additional 10Be results will provide further insights into the function of the alluvial fans as buffers in the sediment cascade under prevailing hyperaridity, spatial patterns in Pleistocene fan morphodynamics and implications for a potential spatio-temporal gradient in (palaeo‑)precipitation.

Reference
Ritter, B., Stuart, F.M., Binnie, S.A., Gerdes, A., Wennrich, V., Dunai, T.J. (2018). Neogene fluvial landscape evolution in the hyperarid core of the Atacama Desert. Scientific Reports 8, 13952. doi:10.1038/s41598-018-32339-9

How to cite: Walk, J., Mohren, J., Binnie, A., Brill, D., Brückner, H., Schaubert, V., Quezada, A., and Lehmkuhl, F.: Assessing the last “large scale fluvial modification” across the hyperarid Atacama Desert, northern Chile, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11939, https://doi.org/10.5194/egusphere-egu24-11939, 2024.

EGU24-12220 | ECS | Posters on site | GM5.2

Significance of millennial-scale coastal upwelling and Rio Loa variability forAtacama paleoclimate during MIS 2 

Jessica Fabritius, Andrea Jaeschke, Jassin Petersen, Volker Wennrich, and Patrick Grunert

The Atacama Desert located in northern Chile is one of the driest places on earth. The factors determining recent hyperarid climate conditions and their interplay and variability on interannual and decadal time scales are generally understood. Evidence for wetter (yet arid) conditions in the Atacama’s past is mostly provided by ephemeral lacustrine and fluvial deposits. The main watercourse of the Atacama Desert is the Rio Loa sourced by rainfall in the Andean mountains. Information on changes in the terrestrial supply to the ocean is recorded in marine sediments off the Rio Loa mouth.

Sediment core SO-104-52KL has been collected on the upper continental slope (∼340 m water depth, 21°S) off the Rio Loa during cruise 104, Leg 3 by RV Sonne in 1995. The preliminary chronology of the core based on 14C datings constrains the top and base of the core to 16 and 42 ka, respectively, with a mean sedimentation rate of 30-40 cm kyr-1. These very high average sedimentation rates allow reconstructions of the paleoceaonographic and paleoclimatic conditions during marine isotope stages (MIS) 3 and 2 on millennial to centennial time scales. The location of the core on the continental slope off the Rio Loa mouth allows for the parallel evaluation of the Humboldt Current System and Andean rainfall as moisture sources for the Atacama Desert.

Proxy data for upwelling properties are established from microfossil assemblages and lipid biomarkers. Preliminary results show that foraminifera are abundant and well-preserved in the upper 4 m of the core. While planktonic foraminifera are rare, benthic assemblages are rich. In total, 24 genera and 49 species of benthic foraminifera were distinguished. The three taxa Bolivina, Bulimina, and Suggrunda, which indicate hypoxic to dysoxic conditions at the seafloor, make up most of the individuals. The dominance of hypoxia tolerating taxa indicates strong upwelling conditions via the presence of a pronounced Oxygen Mimimum Zone impinging on the upper continental slope. These data are put into context with relatively warm sea surface temperatures of average 21 °C as derived from alkenone data. Together with XRF data and grain-size analyses, both applied to characterize the terrestrial input by the Rio Loa, the expected proxy data will provide new insights into the dynamics of land-ocean coupling between the Atacama Desert and the eastern Pacific Ocean.

This study is part of the CRC 1211 “Earth-Evolution at the dry limit” project, funded by the German Research Foundation (DFG).

How to cite: Fabritius, J., Jaeschke, A., Petersen, J., Wennrich, V., and Grunert, P.: Significance of millennial-scale coastal upwelling and Rio Loa variability forAtacama paleoclimate during MIS 2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12220, https://doi.org/10.5194/egusphere-egu24-12220, 2024.

EGU24-12681 | ECS | Orals | GM5.2

The coevolution of life and landscape in the Atacama Desert 

Ariane Binnie, Kathrin Lampert, Pia Victor, Klaus Reicherter, Ambrosio Vega Ruiz, Laura Evenstar, Gabriel González, and Steven Binnie

The evolution of landscapes has often been inferred from the phylogenetic records of species that inhabit them, but it is rare to have a sufficiently detailed record of landscape evolution to be able to test the validity of links between bio- and geochronometers. Here we derive the history of fluvial incision of the Tiliviche River in the Central Depression of the northern Atacama Desert, Chile, using cosmogenic nuclide exposure dating of fluvial terraces and nearby paleochannels. We compare this to the timing of speciation from molecular clock dating of Ephemeroptera (Mayflies), collected from both the Tiliviche and proximal Camerones Rivers. Both these drainages source their discharge in the Western Cordillera of the Andes Mountains and drain westwards to the Pacific Ocean. Where they pass through the low relief Central Depression between the Andes and Coastal Cordillera they have formed steeply incised canyons. Our exposure dating shows that notable incision of the Tiliviche River into the Central Depression began around 2 Myr ago. The timing of the divergence of Ephemeroptera species from the Tiliviche and Camerones Rivers is coeval with the onset of Tiliviche incision at 2 Myr. Furthermore, this history of river incision and speciation is consistent with the timing of abandonment of smaller streams that used to flow across the pampa between the Tiliviche and Camerones rivers (Binnie et al., 2020).  Our results imply that the downcutting of the Tiliviche as a deep canyon and the contemporaneous drying out of smaller drainages between Tiliviche and Camerones were sufficient to isolate the Ephemeroptera clades.  This provides a positive test of a coupled bio- geochronometer approach for unravelling relationships between life and landscape. Whether the controls of river incision and consequently speciation are predominantly climatic, tectonic, or autogenous in nature is still to be resolved.

Binnie S. A, Reicherter K. R., Victor P., González G., Binnie A., Niemann K., Stuart F.M., Lenting C., Heinze S., Freeman S.P.H.T. and Dunai T. J. (2020)
The origins and implications of paleochannels in hyperarid, tectonically active regions: The northern Atacama Desert, Chile. Global and Planetary Change, Volume 185. https://doi.org/10.1016/j.gloplacha.2019.103083

How to cite: Binnie, A., Lampert, K., Victor, P., Reicherter, K., Vega Ruiz, A., Evenstar, L., González, G., and Binnie, S.: The coevolution of life and landscape in the Atacama Desert, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12681, https://doi.org/10.5194/egusphere-egu24-12681, 2024.

The study of supergene minerals has been used as a proxy to unravel the palaeoclimatic conditions that prevailed when it occurred. The youngest age of supergene mineralisation is interpreted as the last time with sufficient moisture; therefore, it will reflect the transition from semi-arid towards hyperarid conditions.

The history of dating supergene minerals, mainly alunite and far less common copper-bearing minerals such as atacamite and pseudomalachite, in the Atacama Desert is mainly restricted to the Central Depression and Precordillera indicating that supergene processes were active from 44 to 6 Ma. In contrast, there are only four ages in the Coastal Cordillera, one reported by Sillitoe & McKee, 1996, and three obtained by Reich et al., 2009. This lack of information makes it impossible to constrain the onset of hyperaridity in the Coastal Cordillera and how it relates with the previously mentioned physiographic units.

The Coastal Cordillera in northern Chile correspond to a Jurassic-Early Cretaceous magmatic arc consisting mainly of andesites and basaltic andesites intruded by numerous plutonic bodies. It hosts the metallogenic belt with the largest number of mineral deposits in the Antofagasta Region, the majority of which are copper deposits.

We test for the first time, the potential of the LA-ICP-MS in situ U-Pb technique to date the deposition of the copper deposits in the Coastal Cordillera and use it as a new proxy to understand its palaeoclimatic evolution. For this purpose, we selected chrysocolla samples from manto- and vein-type deposits hosted in the west side of the Coastal Cordillera.

Chrysocolla is an amorphous hydrated copper silicate that precipitate from gel-like material. Furthermore, the chrysocolla may occurs as a replacement of other copper minerals such as malachite and atacamite. Macroscopically it is possible found it in crust, in veins filling cracks along the host rock or in amygdales of andesites. The second most common mineral is atacamite which presents a complex textural relationship with chrysocolla.

The amorphous structure of chrysocolla makes difficult that the U and Pb concentrations will be consistent along the same sample. Due to this, we apply a pre-scan with the laser to measure the U-Pb ratio in the sample. After that, the laser spots were defined in tree main areas: highest, intermediate and lowest U-Pb ratio to be secure that we will get a dispersion of the ratios that can help to obtain an isochron.

The preliminary results show that the chrysocolla is extremely young (<1 Ma). The oldest age obtained is 7 Ma. It is possible that these ages are the consequence of a reset of the system. We need to consider the possibility that the amorphous structure of chrysocolla allows U- and Pb-loss that can give a younger age than the real deposition age.

How to cite: Ríos-Contesse, J.: U-Pb LA-ICP-MS in situ dating of chrysocolla in copper deposits in Coastal Cordillera, northern Chile, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13141, https://doi.org/10.5194/egusphere-egu24-13141, 2024.

EGU24-13512 | ECS | Orals | GM5.2

Depositional environment of upper Miocene to lower Pliocene diatom-rich deposits of the Bahía Inglesa Formation inferred from benthic foraminiferal assemblages 

Fatima Zohra Bouhdayad, Tiago Menezes Freire, Laura Schneider, Daniel Herwartz, Stephanie Scheidt, Jassin Petersen, Sven Nielsen, Marcelo Rivadeneira, and Patrick Grunert

Neogene diatom-rich deposits of north-central Chile represent fundamental archives for studying the dynamic relationship between sea surface temperatures and paleoclimatic fluctuations in the Atacama Desert. To ensure a reliable correlation between the (often discontinuous) marine and terrestrial archives, a well-calibrated stratigraphic framework is needed. In this sense, this study presents microfossil and sedimentological data from a c. 9m-thick diatomaceous mudstone deposit cropping out at the Quebrada Tiburón (27°42' S, 70°59' W, Bahía Inglesa Formation) for paleoenvironment investigations. Biostratigraphy, chemostratigraphy, and tephrochronometry correlated the diatomaceous mudstones with the upper Messinian and Zanclean (c. 6.1-3.6 Ma). To further improve the paleoceanographic interpretations and stratigraphic framework of the sequence, we also measured stable oxygen isotopes (δ18O) from two shallow infaunal benthic foraminifera species (Bulimina falconensis and Uvigerina striata/peregrina). However, the diatom-rich succession shows distinctive horizons of bioturbation, often associated with overlaying sandstones of variable thicknesses which are intercalated with the diatomaceous mudstones. These repetitive bioturbation cycles warrant caution when interpreting δ18O data, as they may imply potential hiatuses in sedimentation. At the same time, the observed cycles may provide the opportunity to establish a sequence stratigraphic framework for the deposition of the diatomaceous mudstones.

Benthic foraminiferal assemblages from the mudstones indicate high export productivity and limited oxygen supply at the seafloor related to a coastal upwelling setting. The low-diversity fauna is mostly dominated by individuals < 150 μm of Bolivina granti/pacifica, Epistominella obesa, and Eubuliminella bassendorfensis. Across the Miocene/Pliocene boundary, the relative abundances of Bolivina granti/pacifica and Epistominella obesa respectively increase and decrease, and Bolivina aenariensis disappears. This faunal shift may be explained by changes in the amount and/or frequency of organic matter input. In the intercalated sandstones, Bolivina granti/pacifica, Eubuliminella bassendorfensis, and Epistominella obesa are still the most abundant species, with variable minor contributions of uvigerininds, Bolivina advena and shallow-water taxa such as Buccella peruviana. Notably, the faunal composition of these sandstones differs from neritic upper Tortonian to lower Messinian and upper Pliocene sandstones below and above the studied section, respectively, in which cibicids and Buccella spp. are dominant. In further steps, increased resolution of the assemblage data and statistical analysis combined with sedimentological data will provide more insights into the depositional processes to explain the observed sedimentary cycles. Understanding these processes will help to interpret the δ18O record and potentially establish a sequence stratigraphic framework for the section.

This study contributes to CRC 1211 “Earth-Evolution at the dry limit”, funded by the Deutsche Forschungsgemeinschaft (DFG).

 

How to cite: Bouhdayad, F. Z., Menezes Freire, T., Schneider, L., Herwartz, D., Scheidt, S., Petersen, J., Nielsen, S., Rivadeneira, M., and Grunert, P.: Depositional environment of upper Miocene to lower Pliocene diatom-rich deposits of the Bahía Inglesa Formation inferred from benthic foraminiferal assemblages, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13512, https://doi.org/10.5194/egusphere-egu24-13512, 2024.

EGU24-18984 | Posters on site | GM5.2

Enhancing AMS measurement precision with the incorporation of 𝛿13C data measured with IRMS 

Martina Gwozdz, Andrea Jaeschke, Stefan Heinze, Janet Rethemeyer, Dennis Mücher, and Markus Schiffer

Within the CRC1211 project-Evolution at the Dry Limit, there is a need for precise dating analysis on soil samples extracted from the Atacama Desert. These samples have a characteristically low carbon content. Consequently, ultra-small samples containing approximately 2-20 𝜇g of carbon, need to be measured reliably. For this reason an elemental analyser (EA) and an isotope ratio mass spectrometer (IRMS) have been coupled to the 6 MV AMS system of CologneAMS as well as an existing gas interface (GIS). This provides a fully automated, online-analysis of 14C/12C, and it delivers precise values for 𝛿13C. We investigated whether this set-up improves the fractionation correction which is used in the 14C data evaluation. 𝛿13C values from multiple standard materials are measured quasi-simultaneously at the AMS and at the IRMS. Within these measurements we determined that the 𝛿13C values form both AMS and IRMS agree with each other within their respective errors. While the 𝛿13C AMS values scatter multiple orders higher than the IRMS values we concluded that the 𝛿13C IRMS values can be used for a reliable and more precise AMS measurements.

How to cite: Gwozdz, M., Jaeschke, A., Heinze, S., Rethemeyer, J., Mücher, D., and Schiffer, M.: Enhancing AMS measurement precision with the incorporation of 𝛿13C data measured with IRMS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18984, https://doi.org/10.5194/egusphere-egu24-18984, 2024.

EGU24-20073 | Orals | GM5.2

Miocene to recent precipitation history of the central Atacama Desert as reconstructed from a clay pan record in the Coastal Cordillera, northern Chile.  

Volker Wennrich, Julia Diederich-Leicher, Stephanie Scheidt, Benedikt Ritter, Niklas Leicher, Richard Albert, Barbara Blanco-Arrue, Pritam Yogeshwar, Rafael Carballeira, Roberto Bao, Dominik Brill, Alicia Medialdea, Melanie Bartz, Eduardo Campos Sepúlveda, Tibor Dunai, and Martin Melles

Hyperaridity is the major limiting factor of Earth-surface processes and biological activity in the Atacama Desert of northern Chile, one of the oldest and driest deserts on Earth. On geological timescales, however, the general aridity, which is thought to have onset during the Oligocene to Miocene, has been punctuated by distinct pluvial periods. Also nowadays sporadic but severe rainfall events, like during the flood in 2015, occur within the hyperarid core of the Atacama Desert. During the Miocene and Pliocene, such wetter conditions caused lake formation in parts of the Central Depression and Coastal Cordillera, but also amplified surface processes as well as changes in vegetation dynamics. Unfortunately, due to the limited number and heterogeneity of suitable paleoclimate archives, the long-term precipitation history of the central Atacama Desert and its drivers are still a matter of controversy.

Here we present a first quasi-continuous (on time periods of 10-100 kyr) record of the Mid-Miocene to present paleoclimatic and environmental history of the central Atacama Desert obtained from an endorheic clay pan. Due to its location in the Coastal Cordillera, the investigated clay pan is assumed to have been decoupled from Andean ground and surface-water inflow, and thus to have recorded only local and regional precipitation variations on different timescales.

The investigated 52 m-long sediment sequence exhibits significant changes in the sedimentological, geochemical paleontological, and mineralogical properties. Preliminary data from the recovered Mid-Miocene sediments imply permanent lacustrine conditions with alternating evaporation cycles that point to significantly different hydrological and/or climatic conditions in Coastal Cordillera than today. A major lithological shift, accompanied by a well-preserved paleosol, documents a significant local groundwater lowering, probably due to fault activation during the mid-Miocene. Subsequent high sedimentation of coarse-grained alluvial deposits indicates alternating periods of wetter than present precipitation, though still arid, conditions with episodic shallow lake phases during the Miocene. A distinct drop in the sedimentation rate and a synchronous transition to fine-grained distal alluvial deposits highlights a significant change in the moisture availability in the Coastal Cordillera during the Pliocene and Pleistocene, probably marking the final onset of hyperarid conditions in the central Atacama Desert.

How to cite: Wennrich, V., Diederich-Leicher, J., Scheidt, S., Ritter, B., Leicher, N., Albert, R., Blanco-Arrue, B., Yogeshwar, P., Carballeira, R., Bao, R., Brill, D., Medialdea, A., Bartz, M., Campos Sepúlveda, E., Dunai, T., and Melles, M.: Miocene to recent precipitation history of the central Atacama Desert as reconstructed from a clay pan record in the Coastal Cordillera, northern Chile. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20073, https://doi.org/10.5194/egusphere-egu24-20073, 2024.

EGU24-20672 | Orals | GM5.2

Triple oxygen isotopes in Atacama Desert waters since the late Miocene 

Michael Staubwasser, Claudia Voigt, Daniel Herwartz, Carsten Münker, and Guillermo Chong

Utilizing H and triple O isotopes, the main hydrologic variables from the Craig-Gordon model (CGM) of isotope evaporation from a lake, i.e. inflow composition (Ri), the atmosphere’s vapor composition (Rv), and relative humidity (hr) can now be accurately constrained by measurements from differently evaporated subset lakes within the basin, if they fall on a single isotope evaporation trajectory in a diagram of 17O-excess or d-excess over δ18O. We demonstrate here, that this approach can be applied also to paleo-lakes by sampling subsets of lacustrine hydrous mineral deposits - e.g. gypsum (CaSO4 • 2H2O) – from the same geologic unit representing a narrowly constrained interval of time. This allows for the reconstruction of the above variables for the past. We conducted a proof-of-concept study in the Atacama Desert on modern and U-Pb dated paleo-gypsum lacustrine deposits. We tested the principles of the above approach on gypsum and lake water from the present-day Salar de Llamara. We verified signal preservation in a 1.8 Ma old – Ri constrained – marine lagoon gypsum outcrop situated on the tectonically uplifted Mejillones Peninsula that has been exposed to meteoric water for the last ~1 Ma. Finally, we applied the method to a 9 Ma old gypsum outcrop from the paleo-lake system of Tilliviche, which existed during the late Miocene / early Pliocene between ~ 11 Ma and 5 Ma. The CGM is applied to nine sub-samples with a ~ +13 to -10 per meg range in 17O-excess (~ +15 to -16 ‰ in d-excess). The model yields a paleo-Ri equal within model uncertainty to the present-day water flowing down Tilliviche ravine with a δ18O ~ -9 ‰ reflecting its high altitude source in the Andes. Paleo-Rv has a δ18O ~ -20 ‰, which is ~ 5 ‰ lower than the present-day atmosphere. Average modelled annual paleo-hr is 66 % (44 to 84 % range), which is considerably more humid than at present (30 to 40 %). The data suggests that rainfall in the late Miocene Atacama Desert had an annual distribution equal to the present time and was likely as scarce. The more depleted past vapor composition can plausibly be explained only by higher subtropical rain-out prior to moisture advection into the desert. The higher paleo-hr implies a much lower late Miocene evaporation rate, and must have been the prime cause of the lake’s existence. Thus, the late Miocene Atacama was likely already hyper-arid in terms of rainfall, but its atmosphere was more humid and less evaporative. The desert’s hyper aridity trend since the late Miocene fits with the global subtropical aridity trend beginning ~ 8 Ma ago and widely recorded by the expansion of drought-resistant C4 plants.

How to cite: Staubwasser, M., Voigt, C., Herwartz, D., Münker, C., and Chong, G.: Triple oxygen isotopes in Atacama Desert waters since the late Miocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20672, https://doi.org/10.5194/egusphere-egu24-20672, 2024.

EGU24-21353 | Orals | GM5.2

Late Neogene terrestrial climate reconstruction of the central Namib Desert derived by the combination of U–Pb silcrete and terrestrial cosmogenic nuclide exposure dating 

Richard Albert, Benedikt Ritter, Aleksandr Rakipov, Frederik M. van der Wateren, Tibor J. Dunai, and Axel Gerdes

The Cenozoic “Namib Group” of the Namib Desert relies on relative chronology and lacks direct radiometric dating. Therefore, the landscape evolution and paleoclimate of the central Namib Desert remains imprecise, hindering the detailed search for global and/or local forcing factors for the aridification of the Namib. The broad presence of silcretes and calcretes in the Namib Desert allows the application of the of the U–Pb laser ablation dating technique on silcretes and calcretes to date important phases of landscape stability and to retrieve crucial paleoclimatic and environmental information on desertification and its paleoclimatic variability. Microscale silcrete formation (maximum of 8 mm), as a result of pressure solution by expanding calcrete cementation, grants the opportunity to date multiple phases (multiple generations of silcrete as growing layers) of silcrete formation. Groundwater silcrete and calcrete formation took place at our study site during the Pliocene, an epoch of relatively stable climate and landscape evolution under semi-arid to arid conditions. Terrestrial cosmogenic nuclide (TCN) exposure dates from flat canyon rim surfaces show the remission of groundwater calcrete formation due to river incision during Late Pliocene–Early Pleistocene. This incision is a consequence of a large-scale landscape rejuvenation caused by a climate shift towards more arid conditions in the Pleistocene, which can be connected to global climate patterns. This study shows the feasibility of applying U–Pb laser ablation to groundwater calcretes and silcretes, discusses important issues associated with this technique, and opens up the possibility of dating numerous sedimentary sequences with silcretes and calcretes in arid environments. Our study redefines and improves the generally accepted Late Cenozoic chronostratigraphy of the Namib Desert (Miller, 2008).

How to cite: Albert, R., Ritter, B., Rakipov, A., van der Wateren, F. M., Dunai, T. J., and Gerdes, A.: Late Neogene terrestrial climate reconstruction of the central Namib Desert derived by the combination of U–Pb silcrete and terrestrial cosmogenic nuclide exposure dating, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21353, https://doi.org/10.5194/egusphere-egu24-21353, 2024.

EGU24-21791 | Orals | GM5.2

Water vapor transport into the Atacama desertsimulated with a high resolution atmospheric model 

Jan H. Schween, Vera Schemann, and Ullrich Loehnert

The Atacama at the west coast of South America is one of the driest regions on earth. Any atmospheric transport of water vapor into this desert which may form fog or dew is accordingly important for its supply with freshwater. Within the CRC 'Earth Evolution at the dry Limit' a network of climate stations has been installed in the core of the Atacama (Schween et al 2020). This network shows a very regular circulation with strong winds from the west during day time and weaker winds from the east during night. These winds are part of a circulation pattern between the coast and the slopes of the Andes known as Rutllant cell. The daytime westerly winds in the desert are moister than the night-time easterlies but this day-night difference in moisture vanishes at the slope of the Andes. Accordingly there is a net transport of water vapor into the desert. But from these surface measurements it remains unclear whether this moisture remains in the surface layer or leaves the region at higher levels,
To get better insight in the circulation we performed simulations with the ICON-LEM model in a 300x300km domain centered around 20.75degS and 69.75W with a resolution of 624m. It covers the ocean as well the high Andes including the coastal mountain range and the central depression. A simulation of a typical winter day showed that the circulation is rather a complex movement of airmasses than a closed circulation. The moist air from the ocean reaches only partly up the slopes of the Andes before it switches to the night time pattern and flows back into the central depression of the desert. There the moist air collects as shallow pools in the basins and valleys where it eventually forms fog. When the following morning the breeze propagates into the desert, convergence at its head leads to injection of moist air into the free troposphere.
We use the model data to identify corridors in which moist air from the ocean enters the desert. In the regions where fog forms we calculate the horizontal transport of liquid (fog) water which can be used to estimate fog water deposition to the surface. We calculate a moisture budget for different layers of the atmosphere to identify where and when water vapor enters and leaves the desert.

Reference:
Schween, J. H., D. Hoffmeister, and U. Löhnert, 2020: Filling the Observational Gap in the Atacama Desert with a new Network of Climate Stations, Global and Planetary Change, 184, https://doi.org/10.1016/j.gloplacha.2019.103034

How to cite: Schween, J. H., Schemann, V., and Loehnert, U.: Water vapor transport into the Atacama desertsimulated with a high resolution atmospheric model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21791, https://doi.org/10.5194/egusphere-egu24-21791, 2024.

Suspended sediment load in rivers has a crucial impact on the river water quality, soil erosion, irrigation activities, and dam or reservoir operations. Dam construction in a river reduces the runoff, which increases the deposition of suspended sediment on the river course and ultimately leads to a change in the river channel morphology. Thus, suspended sediment load prediction is significant for planning and sustainable management of the riverine ecosystem. Researchers have used various physical models, such as sediment rating curves (SRC), SWAT, HEC-RAS, HEC-HMS, etc., for predicting suspended sediment load. Recently, researchers have used machine learning models to predict suspended sediment load in different hydroclimatic regions worldwide. In this study, we used five different machine learning models, such as ElasticNetCV, Multi‑Layer Perceptron (MLP) Regressor, Extreme Gradient Boosting (XGB) Regressor, Light Gradient-Boosting Machine (LGBM) Regressor and Linear Regression (LR), for predicting suspended sediment load in a downstream station of Godavari River Basin (GRB). The GRB is the largest Indian peninsular river basin, covering more than 0.3 million square kilometers of area. We used the 'Lazy Predict' Python library to achieve better results for machine-learning modeling. The data was collected for the period of 1970–2018 and divided into two parts, viz. pre-1990 and post-1990, to consider the dam effects on the downstream regions of the GRB. Performance evaluation revealed that the Multi‑Layer Perceptron (MLP) Regressor performed very significantly, with an r-square value of 0.71 and 0.74, respectively, for pre-1990 and post-1990. The developed models offer a valuable resource for decision-makers, environmental scientists, and water resource managers seeking to proactively manage sediment-related issues in river systems, ultimately fostering sustainable water quality and ecosystem health.

How to cite: Kundu, S., Swarnkar, S., and Agarwal, A.: Application of Machine-Learning Based Models for Prediction of Suspended Sediment Load in the Indian Peninsular River Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1117, https://doi.org/10.5194/egusphere-egu24-1117, 2024.

EGU24-1900 | Orals | GM5.3 | Highlight

Large Scale Modification of the Salton Sea Shoreline to Reduce the Potential for Dust Emissions 

John Gillies, Eden Furtak-Cole, and George Nikolich

The Salton Sea in California’s Imperial and Riverside counties is a large endorheic lake with significant areas of exposed shoreline.  The exposed shoreline and surrounding desert are potential sources of wind-blown dust that can contribute to degraded air quality as the emissions create high concentrations of particulate matter ≤10 µm in aerodynamic diameter (i.e., PM10), which is a federally regulated pollutant in the USA.  The Salton Sea’s water surface height is lowering at an accelerating rate.  The decreasing volume of water leads to increased shoreline exposure with the potential for high wind speed events to cause dust emissions. This increases the potential for degradation of air quality with respect to PM10 mass concentrations within the basin potentially elevating the health risk to the surrounding population.  The State of California has implemented the Salton Sea Management Plan that has several phases of development to protect air quality and ecosystem values at the Salton Sea.  California Department of Water Resources (DWR) began a series of projects at the Salton Sea designed to limit dust emissions from shoreline areas deemed vulnerable to wind erosion and dust emissions based on evaluation of soil textural properties and in situ measurements of PM10 emissivity.  To protect sandy surfaces vulnerable to wind erosion, surface roughening based on the super-positioning of non-erodible roughness elements onto the exposed sediments of the shoreline has been implemented.  The non-erodible elements are bales of straw sourced from agricultural producers in the vicinity.  They are rectangular prisms of dimensions 0.41 m high, 1.12 m long, and 0.55 m wide. 

To evaluate the effectiveness of the roughness arrays, designed initially to offer 95% reduction in sand transport and dust emissions compared to the unprotected surface, computational fluid dynamics modeling was carried out to quantify the reduction in surface shear stress and dust emission potential due to the presence of the roughness.  In addition, in situ measurements of sand flux and PM10 concentrations were collected to corroborate the simulation results.  Air flow across the roughness array for three freestream wind speeds and three wind direction angles was simulated using CFD in OpenFOAM.  The mean shear stress reduction compared to the surface without roughness for the three freestream wind speeds and wind directions was 62% (±1%), 66% (±0.2%), and 79% (±1%), for 225°, 270°, and 315° wind directions, respectively.  The greatest probability for high wind speed events is expected from the wind direction range 225° to 315°. The mean reduction in total PM10 emission for these three conditions were: 73% (±4%), 85% (±2%), and 80% (±2%).  In situ measurements suggest control effectiveness is even greater as saltation has not been recorded within the roughness for the range of observed wind speed, and there is no indication that PM10 has been emitted from the protected surfaces.  This suggests that large size superposed roughness has effectively modified the dust emission potential of these susceptible surfaces and provides the protection needed to ensure that the exposed shoreline does not contribute to the regional PM10 burden.

How to cite: Gillies, J., Furtak-Cole, E., and Nikolich, G.: Large Scale Modification of the Salton Sea Shoreline to Reduce the Potential for Dust Emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1900, https://doi.org/10.5194/egusphere-egu24-1900, 2024.

Sand mining has accelerated in recent years primarily due to population increase and rapid urbanization. To meet demand, the rate of sand extraction often exceeds the rate of natural replenishment with serious environmental consequences. In this review paper, the Vietnamese Mekong Delta (VMD), a global hotspot for sand mining with a prolonged history of intensive riverbed extraction, is used as a representative case study to highlight the extent and compounded impacts of this activity. Sand mining budgets from literature present significant discrepancies, with estimates for the entire delta varying from around 8.5 to 42.2 Mm3/yr. These variances can be attributed to the challenges in the actual measurement of mining rates and the deployment of disparate methods across studies. Moreover, the widespread practice of illegal sand mining in the region further exacerbates the mismatch in budget calculations. Consequences of such mining activities manifest as deeply-incised riverbeds leading to riverbank and coastal erosion. Moreover, the massive sediment removal has resulted in river water level reductions, disrupted hydrological connectivity, and diminished floodplain inundation. The augmented backwater effect, a result of riverbed lowering, amplifies saltwater intrusion in dry seasons. While the physical and hydrological impacts have received attention, studies on the ecological and societal ramifications remain sparse. These impacts, further magnified by factors like upstream dams, irrigation infrastructures, excessive groundwater extraction, and sea-level rise (SLR), present a multifaceted challenge. This paper concludes by advocating for the adoption of remote sensing-based approaches for effective mapping of sand mining activities, and implementation of sustainable sand harvesting practices to balance developmental needs with environmental conservation.

How to cite: Park, E.: Sand mining in the Mekong Delta: Extent and compounded impacts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2678, https://doi.org/10.5194/egusphere-egu24-2678, 2024.

EGU24-4096 | ECS | Orals | GM5.3

Assessing river corridor changes after anthropogenic vegetation removal: an object-based mapping approach 

Katarina Pavlek, Mateo Gašparović, and Ronald E. Poeppl

The development of remote sensing technologies and image classification methods has facilitated research on changes in river channels and floodplains by automating mapping of land cover and geomorphic units. In often highly heterogeneous river environments, object-based approaches proved sensible, since they are based on objects produced by image segmentation rather than on individual pixels.

This study uses object-based image analysis to investigate land cover and river channel dynamics in the managed corridor of the Orljava River in the Pannonian basin (Croatia). In the last decade, the river has been affected by anthropogenic removal of riparian vegetation to increase channel capacity, which was followed by a big flood event. Five river corridor classes (water, bare soil, sparse vegetation, dense vegetation, and shadows) were classified based on RGB and near-infrared (NIR) aerial images in the period 2011-2021. A digital surface model generated from the images was used to separate bare river channel units (“river sediments”) from bare soil in the floodplain and to define high vegetation, while agricultural land was classified manually. The accuracy of the produced maps was between 85 and 93%, except for the year 2014 which lacked the NIR band. Based on classified river corridor units, changes in channel morphology were further analysed in GIS. The two main phases of river corridor changes were caused by the occurrence of a big flood in 2014. In 2011-2014, immediately after the flood, a significant increase in the area of water and river sediments was recorded, mostly at the expense of bare riverbanks and adjacent agricultural land. Large in-channel bars have formed due to sediment accumulation, as well as significant channel migration has been recorded. Contrarily, in 2014-2021 lower discharges allowed gradual channel narrowing and stabilisation, characterised by the spread and growth of vegetation in the river corridor.

Observed changes in channel morphology and vegetation succession are natural processes related to actively meandering rivers. However, it has been shown that extensive bank erosion during the flood and subsequent land cover dynamics were primarily triggered by anthropogenic removal of riparian vegetation exemplifying how inadequate and isolated river management decisions may increase bank erosion and lead to a loss of agricultural land in floodplain areas.

How to cite: Pavlek, K., Gašparović, M., and Poeppl, R. E.: Assessing river corridor changes after anthropogenic vegetation removal: an object-based mapping approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4096, https://doi.org/10.5194/egusphere-egu24-4096, 2024.

EGU24-4572 | ECS | Posters on site | GM5.3

Human impact on grain size variations of river gravel bars in the western Himalaya: Insights from a UAV survey 

Narendra K. Patel, Fritz Schlunegger, David Mair, Pitambar Pati, and Ariel Henrique Do Prado

Downstream variation in bed material size was investigated over a stretch of the Yamuna River in the western Himalayan region in India. Data on grain size distribution along rivers are critical for understanding river systems and material transport. Flow regulation caused by dam construction can alter sediment transport mechanisms, generating morphological changes. Using an uncrewed aerial vehicle (UAV), we investigated precise grain size variation along the Yamuna River and its tributaries in the Siwalik region, from Lakhwar Dam to Hathni Kund Barrage. All photos were collected via UAV survey.

On these datasets, grain size variation was observed across dams. The upper Yamuna River's bed-load sediments are becoming finer-grained downstream. Since the dam barrier and low flow energy force large particles to remain above the dam, smaller particles are found downstream of the dam. During the survey, evidence of mining in several locations along the river suggests the influence of anthropogenic activity in the regions. Accordingly, this study sheds light on the potential consequences of dam construction on material transportation. We observed that dams work as a barrier for coarse grain particles, which may have an impact on the dam in the near future. Field evidence and preliminary processed data indicate that the size of the gravel bar along the river course has been modified by many human interventions (hydroelectric dams, barrages, mining).

How to cite: Patel, N. K., Schlunegger, F., Mair, D., Pati, P., and Prado, A. H. D.: Human impact on grain size variations of river gravel bars in the western Himalaya: Insights from a UAV survey, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4572, https://doi.org/10.5194/egusphere-egu24-4572, 2024.

Already at the end of the 19th century, initial approaches were carried out to estimate the extent of anthropogenic mass transfer by humans on a global scale. In the course of the proposal of a new geological epoch, the Anthropocene, which is controversially discussed since the 2000s, anthropogenic geomorphological changes have received new attention. According to this concept, humans are moving more rocks and sediments worldwide than natural processes, with a supposed exponential increase in the mid 20th century. Along with agriculture, mining activities are among the most important anthropogenic transformations of the earth's surface. Mining landscapes have become at many locations an integral part of landform development and a crucial element of the technosphere. In the framework of the Anthropogenetic Geomorphology, humans are considered as geomorphological agents, creating a variety of landforms, for which at the same time new classifications are needed.

In the present project an interdisciplinary environmental-historical approach is used to examine the question of when, how and to which extent humans have modified the relief landscape. As study area, the Harz Mountains in Northern Germany were selected, which represents one of the most important historical mining areas in Central Europe, especially for silver, lead and copper. They are a key region for the interconnectedness of human-nature interactions, which are reflected in a genetically complex landscape development. Humans have influenced the landscape of the Harz Mountains already since prehistorical times to varying extents. Distinct phases of landscape transformation will be distinguished in this study. However, one of the most significant landscape changes took place in the Early Modern Period, when the Harz became one of the largest industrial areas in Central Europe with some of the deepest shafts worldwide at that time and large-scale underground excavations. The main driver for the exploitation of ores was the interlinkage with the global metal trade and the arise of new economic and political systems during the Renaissance, whereas the mining operations mainly relied on the local availability of certain resources such as wood and water. The energetic base for the underground mining, reaching up to almost 1000 m below the earth surface, was the Upper Harz Water Management System, the largest historical energy supply system for mining, designated as UNESCO-World-Heritage site in the year 2010.

In a case study in the St. Andreasberg Mining District (West-Harz) as one of the centers of silver mining, the physical landscape changes are systematically examined in the context of litho-geomorphological, ecological and cultural-political aspects and in their spatio-temporal patterns. The focus of the study presented here lies on the type and dimension of subterranean relief changes in the lithosphere in connection with the correlating transformation of the reliefsphere and the hydrological system in the catchment area of the Oder-Sieber River system. The mining landscape is composed of anthropogenic landform assemblages, consisting of heterogeneous compositions of lithogenic, geomorphological, biogenic and aquatic elements, which are representative for the Upper Harz mining landscape.

 

How to cite: Iturrizaga, L. and Ließmann, W.: Anthropogenic landscape transformations and geomorphological landform assemblages in the context of historical mining in the Harz Mountains (Germany): Case study Sankt Andreasberg Mining District , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6818, https://doi.org/10.5194/egusphere-egu24-6818, 2024.

EGU24-9614 | ECS | Posters on site | GM5.3 | Highlight

The influence of anthropogenic topographic changes on geomorphological processes in the city of Rome (Italy) 

Michele Delchiaro, Francesca Vergari, Carlo Esposito, and Maurizio Del Monte

The urban landscape of the city of Rome exhibits a discernible urban-rural gradient, characterized by a diminishing anthropic impact from the central historic city to the outskirts and peri-urban zones, marked by increased open spaces and green areas. In the Aeterna Urbs, the Anthropocene epoch has seen significant urbanization and infrastructure development, frequently leading to profound alterations or complete obliteration of natural landscapes. The distinctive anthropogenic changes observed in Rome, characterized by their unique features, are not confined to the city; they are also evident in other contexts, underscoring commonalities and interconnections in how human activity shapes the landscape. In this regard, the city of Rome stands as an exemplar, offering a unique opportunity to delve into the human-induced changes and their impact on the natural geomorphological processes. However, despite their critical importance in understanding human-landscape interactions and the associated geomorphological risks, the role of human activity as a morphogenetic agent along the urban-rural gradient remains inadequately understood. This study addresses the tricky understanding of human-induced geomorphic changes, particularly on erosion, transport, and sedimentation processes, which pose threats to ecosystem functioning and impede efficient land use. The Malagrotta extraction area in Rome, Italy, characterized by a mining landscape of ridge removal, hillslope terracing and valley filling, offers a unique opportunity to assess the impact of topographical alterations on the geomorphic system. The investigation employs the widely accepted functional relationship between drainage area (A in m2) and slope (S in m/m) to delineate local process domains and facilitate the interpretation of process interactions. The slope-area function is applied to the same watershed across different periods using digital elevation models, offering insights into the evolving geomorphic dynamics influenced by human activities.

How to cite: Delchiaro, M., Vergari, F., Esposito, C., and Del Monte, M.: The influence of anthropogenic topographic changes on geomorphological processes in the city of Rome (Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9614, https://doi.org/10.5194/egusphere-egu24-9614, 2024.

The Bonneville Salt Flats, a landscape characterized by a perennial halite crust and seasonal flooding in western Utah, USA, provides a natural laboratory for advancing understanding of the processes that create and change dynamic saline environments. A decade of interdisciplinary research on the Bonneville Salt Flats has resulted in a new understanding of the salt's history, the functioning of the salt crust ecosystem, and the role that humans play in shaping this landscape. Sedimentological analyses of cores collected across the salt has changed our understanding of the history of the landscape, including evidence of extensive erosion after Pleistocene Lake Bonneville, the surprisingly young age of the oldest salt (~5.4 cal ka BP), and historical and ongoing crust halite dissolution. 16S rRNA gene and metagenomic analysis of the salt crust reveals a complex and robust microbial and archaeal ecosystem within the salt, hosting a wide range of metabolic pathways that actively cycle C, N, and S through the landscape. A long-term environmental observation station established at the center of the salt crust provides a robust new record of landscape processes, weather data, and eddy covariance flux measurements that have helped to constrain the energy and water budgets and highlight the sensitivity of ecosystem-scale surface conductance in the absence of vegetation to atmospheric drying. Arial and spaceborne remote sensing data show the impacts of over a century of human activities on landscape composition and texture, including groundwater extraction for potash mining, intensive surface modification, and land use associated with high-speed vehicle racing on the salt. Brine extraction and attempted mitigation have resulted in salinity and salt crust extent decreases over the last several decades, potentially limiting future landscape uses. The intricate interconnection of the human-natural system has enabled the exploration of variations in mental models influencing decision-making, attribution of blame, and the feasibility of adaptive management in dynamic landscapes serving diverse and conflicting needs. Integration of science with art has expanded the nature of the inquiry and led to new ways of thinking about human connections to a seemingly barren, but truly alive, place. All of these new insights into saline landscapes and the role that human land use and climate change play in altering processes are significant to understand as water delivered to closed basin saline lakes globally is in decline, potentially leading to an expansion of exposed salt-encrusted landscapes.

How to cite: Bowen, B.: A decade of interdisciplinary research on the dynamics of surface processes and landscape change at the Bonneville Salt Flats, Utah, USA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9915, https://doi.org/10.5194/egusphere-egu24-9915, 2024.

EGU24-11466 | Posters on site | GM5.3

The impact of anthropogenic activities on the geomorphological evolution of the Taro River over the last 70 years 

Vittoria Scorpio, Alessandra Cervizzi, and Sharon Pittau

Human pressures, in response to economic development and population growth, have been one of the main drivers of river systems changes especially since the second half of the last century. In the European context, anthropogenic impacts mainly concern with catchment land use changes, in-stream gravel mining, and in-channel works construction. The reconstruction of the past evolutionary trajectories and the temporal analysis of driving factors is considered fundamental to understand present river conditions, to support channel network management and to anticipate future changes.

The aim of this study is to investigate the anthropogenic factors that have impacted the geomorphological evolution of the Taro River (Northern Apennines, Italy) over the last 70 years.

Traditional methods based on multi-temporal orthophoto (1954, 1976, 1988, 1994 and 2020) analysis in GIS environment were used for studying historical channel changes along a channel segment 90 km long. Analyses of anthropogenic factors that may have influenced changes in the active channel included: (i) analysis of land use changes at the catchment scale, (ii) quantification of gravel mining activities, and (iii) analysis of in-channel work constructions.

Results showed that between 1954 and 1976 the Taro River channel width decreased by 39% on average, mainly in response to gravel mining activities, and subsequently to the increase of works into the channel. To the contrary, as a result of mining activities abandonment in the early 1980s, and of the occurrence of an extreme flood event in 1982, an increase of 18% in the active channel width was observed in 1988. The decreases in active channel width in the last 30 years (since the end of the 1980s) were correlated with the increase in forested areas in the catchment and with the increasing degree of stabilization of channel banks.

These studies are fundamental to identify management solutions in degraded rivers and to anticipate impacts in such rivers still featuring poorly impacted channel morphologies.

How to cite: Scorpio, V., Cervizzi, A., and Pittau, S.: The impact of anthropogenic activities on the geomorphological evolution of the Taro River over the last 70 years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11466, https://doi.org/10.5194/egusphere-egu24-11466, 2024.

This study contributes to the topic of land surface degradation due to touristic activity by documenting examples of trail impacts related to initial trail development and high-intensity visitor usage. Our observations are based on a case study from the tropical Andes - Peru’s Rainbow Mountain (also named Vinicunca or Montaña de Siete Colores), which became a world-renowned tourist destination in recent years (after 2015/2016). The topic is important, as such high-mountain settings are very fragile, and degradation can occur rapidly – with long-term repercussions, as these landscapes tend not to recover quickly.

The main objectives of the study were to: (1) characterise and map different types of impacts related to direct visitor pressure, (2) document and evaluate activities aimed at limiting degradation while enhancing visitors’ experience, and (3) propose a conceptual model of trail functioning in the tropical high-mountain environment. Data were collected using ground-based surveys, unmanned aerial vehicle (UAV) and high-resolution satellite images.

Eight processes were responsible for transformation of the land surface: (1) trampling, (2) abrasion/shearing by visitors and service animals, (3) transformation of water and sediment circulation, (4) water erosion, (5) freeze-thaw cycles, (6) dry-wet cycles, (7) aeolian activities, and (8) mass movements. The five main trail impacts clearly visible in the landscape just after 1–2 seasons of intensive recreational use were: trail widening, trail incision, formation of braided trail networks, development of muddy sections, and development of informal (visitor-created) trails.

The hiking path was characterised by a width below 2 m and a low incision (<0.1 m incision on 80% of its length). The equestrian path was much wider (up to 17 m) and slightly more incised (<0.3 m incision on 69% of its length). The width of the multi-use path was up to 24 m. We suggest that the location of the trail in relation to the main geomorphological elements of the landscape (valley bottom vs slopes) and trail alignment to the terrain gradient have an essential impact on trail functioning and degradation. Specifically, trail sections routed through flat terrain and without lateral restrictions tend to widen and develop muddy sections, while sections routed parallel to steep slopes were prone to incision. Trails transverse to the terrain gradient were better drained but often developed into several parallel paths.

Undertaken trail management aimed to reduce negative visitor impacts and improve their safety and satisfaction. Successful measures included hardening the trail tread and marking the trail edges, which limited visitor dispersion and stabilised trail conditions. Partially successful actions involved installing artificial drainage (only partly preventing muddy section development) and providing separate paths for pedestrians and equestrians. After this change, the pedestrian trail was narrow and stable, but the equestrian path continued to degrade. Attempts to change visitor traffic patterns by relocating parking and abandoning a section of the trail were unsuccessful, as the new road and parking, and a new additional trail segment further degraded the landscape. Moreover, geomorphological processes continued to transform the abandoned trail section.

This study was funded by National Science Centre, Poland, project 2021/43/B/ST10/00950

How to cite: Tomczyk, A. and Ewertowski, M.: Land surface changes in response to touristic activity in the fragile, high-mountain environment: a case study of Vinicunca (Rainbow Mountain) in Andes, Peru, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12407, https://doi.org/10.5194/egusphere-egu24-12407, 2024.

Palaeochannels offer a glimpse into the history of a landscape. In the context of shifting perspectives from traditional hard engineering to soft nature-based measures, modern flood risk management could benefit from an understanding of the natural processes and features preserved within palaeochannels, which have otherwise been hidden by a legacy of engineering and land management on the river and floodplain. This study uses geophysical surveying techniques to bridge the gap between surface topography LiDAR data and sediment core data, in order to investigate the evolution of past rivers and tidal inlets in the Somerset Levels coastal plain and inland wetlands in southwest England. Case studies from a range of palaeochannels across the Somerset Levels are presented to identify the advantages and limitations of applying the methodology to a coastal plain and wetland dominated by Holocene alluvium and increasing human influence over the past several centuries. Four river systems represent both tidally dominated and inland freshwater conditions: a large tidal creek system within predominantly clay sediment; an inland river system traversing a peat wetland which was the former course of a major drainage network before intentional diversion; and two systems at the transition between tidal and freshwater influence.

Two-dimensional subsurface profiles derived from electrical resistivity tomography (ERT), shallow seismic refraction traverses, and ground penetrating radar (GPR) are used to laterally connect one-dimensional vertical sediment core data, and then integrated with the surface topography LiDAR data to construct channel and floodplain cross-sectional models. Past geomorphological processes – such as lateral migration, channel adjustment, and avulsion – are revealed in the preserved channel sediments, indicating responses to the contemporary climatic and anthropogenic conditions. Geophysical survey designs for identifying fluvial-geomorphological processes and features within palaeochannels are discussed, along with the need to adapt survey design for best resolution and depth in different, peat-dominated or clay-dominated, sedimentary settings. ERT is shown to consistently provide excellent depth penetration and estimations of channel extent. High resolution GPR data at the near-surface can be used in tandem with available core data to delineate the channel fill and bank geometry and calibrate depth estimations.

Flow conditions are reconstructed quantitatively using palaeohydrological drainage equations based on cross-sectional area values derived from the geophysical profiles. This avoids reliance on oversimplified cross-section estimates based upon surface parameters such as width and meander length, and one-dimensional depth estimates from core profiles. Existing hydraulic and drainage regime equations are tested against flow gauge data and channel measurements from active rivers to obtain optimal parameters for palaeohydrological calculations. These parameter estimates also benefit from on-the-ground channel parameter measurements in tandem with topographic remote-sensing. Hence, this study proposes a novel methodology that integrates geophysical surveying within palaeohydrological estimation techniques to improve models over long timescales of past fluvial environments that have been modified by humans.

How to cite: Anthony, J.: A geophysical study of palaeochannels on the Somerset Levels coastal plain and wetland to explore river landscape evolution., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12508, https://doi.org/10.5194/egusphere-egu24-12508, 2024.

EGU24-13659 | ECS | Orals | GM5.3

Testing a low-complexity model to decompose the multitemporal dynamics of soil erosion and sediment delivery in agricultural catchments 

Francis Matthews, Panos Panagos, Arthur Fendrich, and Gert Verstraeten

Testing and improving the capacity of soil erosion and sediment delivery models to simulate the response of soil erosion to the intra-annual dynamics of climatic drivers and disturbances (e.g., vegetation clearcutting, tillage events, wildfires) is critical to understand intolerable soil loss and catchment sediment yields. Here, we approach the trade-off between the need for model simplicity and temporally dynamic predictions by testing the ability of a low-complexity, spatially distributed model (WaTEM/SEDEM), to decompose the 15-day dynamics of soil erosion and sediment yield. A standardised RUSLE parameterisation and model implementation routine was applied to four arable-dominated catchments in North-West Europe with open-access validation data. We firstly show that when applied to simulate the multitemporal dynamics of sediment delivery, a standard assumption of a temporally static transport capacity within the model structure mostly cannot adequately replicate the multitemporal variability of sediment delivery. Instead, optimising a 5-parameter splines curve to determine the temporal profile of the transport capacity coefficient (ktc) based on the monthly average sediment yield improved the model performance and revealed clear seasonality in the sediment transport efficacy. Despite simulating similar temporally aggregated sediment yields, the introduction of seasonal dynamics into the transport capacity further caused a net reduction in the magnitudes of the spatially distributed sediment fluxes, compared to a temporally lumped approach. Published catchment observations infer this seasonality in sediment transport efficiency to attribute abundant vegetative boundaries in summer and increased soil crusting and runoff promotion in winter. Models operating at temporally aggregated timescales should account for the possibility of decoupling in time and space between gross erosion and sediment delivery related to these alternations between transport- and detachment-limited sediment transport capacity states. Despite the complexities and uncertainties involved in the temporal downscaling of WaTEM/SEDEM, we show the utility of this approach to: 1) link optimised multitemporal parameters to key missing model information components which may reduce error in gross erosion predictions (e.g. more consideration of antecedent soil conditions), 2) form a basis for strategically adding physical process-representation, with a focus on maintaining low model complexity while improving predictive skill, and 3) better understand the interdependencies between spatial fluxes and multitemporal dynamics when undertaking model predictions at large spatial and temporal scales.

How to cite: Matthews, F., Panagos, P., Fendrich, A., and Verstraeten, G.: Testing a low-complexity model to decompose the multitemporal dynamics of soil erosion and sediment delivery in agricultural catchments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13659, https://doi.org/10.5194/egusphere-egu24-13659, 2024.

Tailings are a by-product of the processing of minerals. Tailings can be highly erodible and transportable via fluvial processes and are commonly stored in ‘tailings dams’ which are a feature of many mine sites. These dams and their impounded material will become permanent geomorphic features in the post-mining landscape. The question examined here is - can tailings dams ever be walk-away structures? Tailings dams can fail by both catastrophic and gradual failure. Catastrophic failure occurs when there is a large scale rapid structural failure of the dam wall. Gradual failure occurs over time by slow infilling of the dam and the erosion of the dam wall. This can lead to overtopping of the dam wall and gully incision and failure of the wall and release of sediment to the environment. To understand failure modes and risk profile, computer based Landscape Evolution Models (LEMs) can be used. LEMs have become common tools to quantify risk for mine waste rock dumps and waste repositories.  LEMs provide detailed information on erosion rates, type of erosion and where erosion is likely to occur. They inform long-term behaviour which allows designs to be tested and improved. Here they are used to assess tailings dams where the strengths and weaknesses of different tailings dams designs are examined across a range of climates and material settings. The results show that if well-designed and assuming a well understood climate, a dam can be sufficiently robust to last centuries. However, failure can occur under different climate settings. Modelling also demonstrates that upon failure water quality will be affected for many centuries post-breach if no remedial work is conducted. Longer term, the tailings can be contained if there is maintenance and or an increase in the dam wall height over time or a more robust dam wall constructed to manage extreme events.

How to cite: Hancock, G. and Coulthard, T.: Assessing tailings dam long-term failure risk using computer based Landform Evolution Models , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14575, https://doi.org/10.5194/egusphere-egu24-14575, 2024.

EGU24-15250 | ECS | Posters on site | GM5.3

Legacy effects of post-storm silvicultural treatments on plot-scale soil erosion in a subalpine headwater catchment of the Italian Alps 

Kenta Koyanagi, Giovanna Nordio, Andrea Andreoli, Enrico Tomelleri, Ronald Pöppl, and Francesco Comiti

Wind-disturbed mountain forests are often subject to artificial deadwood extraction and tree planting to accelerate the recovery of timber resources. However, little is known about to what degree and extent those post-storm silvicultural treatments modify the surface processes of wind-affected hillslopes. This study aims to understand how post-storm silvicultural treatments affect soil erosion from wind-disturbed mountain forests by coupling monitoring and modeling approaches. We continuously collected and measured soil losses from four 4.5-m-wide and 6.0-m-long bounded field plots located on wind-disturbed hillslopes with a slope angle of 45 % in a subalpine headwater of the Italian Alps during the vegetation periods from 2021 to 2023. The dominant ground cover of four plots resulting from altered post-storm interventions is characterized by residual deadwood, native herbs, 20-year-old plantation, and 5-year-old plantation, respectively. During 75 analyzed storm events, average soil loss from the native herbs-covered plot (2.4 t ha-1; SD: ±3.5 t ha-1) was the smallest, followed by plots covered with residual deadwood (mean±SD: 3.1±2.9 t ha-1), 20-year-old plantation (mean±SD: 3.5±5.2 t ha-1), and the 5-year-old plantation (mean±SD: 4.5±4.2 t ha-1). Moreover, linear regression models (p-value < 0.001) indicated that two plantation plots potentially yield 2-fold sediment of naturally regenerating deadwood and herbs-covered plots as storm rainfall depth increases. Our three-year field observations highlight the persistent impact of post-storm forest management activities in accelerating soil erosion potentially even 20 years after their implementation. In the next step, the Water Erosion Prediction Project (WEPP) model will be used to further investigate the effect of human treatments on hydrology and sediment transport in storm-affected mountain areas.

How to cite: Koyanagi, K., Nordio, G., Andreoli, A., Tomelleri, E., Pöppl, R., and Comiti, F.: Legacy effects of post-storm silvicultural treatments on plot-scale soil erosion in a subalpine headwater catchment of the Italian Alps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15250, https://doi.org/10.5194/egusphere-egu24-15250, 2024.

As the number and quality of satellite data detecting the Earth increases, a significant number of research fields are using these images, providing increasingly interesting results that were previously unimaginable. In this study, we extract the coastline from satellite images captured over a long period of time and analyze how the location of the coastline has changed in time and space.

Recently, many studies have attempted similar analyzes. However, the resolution of the image is low, so the results tend to be unreliable, as they often produce trend results of less than cm per year. Therefore, in this study, we first analyzed how reliable the trend results are depending on the amount of data, even if the resolution is low.

We also present a method to obtain the location of the coastline from reference points fixed behind the coast by linearly fitting nearby coastline points to reduce the error of coastline points extracted from satellite images. This method obtains the coastline position as the distance to the intersection of the base line and the fitting line and obtains the coastline gradient as the angle of the fitting line.

This method was applied to Wonpyeong-Chogok Beach located in the East Sea of the Korean Peninsula to analyze how the coastline has evolved over the past five years from 2019 to 2023, when coastal structures were built. On this beach, which has a total length of 2.9 km, three submerged detached breakwaters, two emerged detached breakwaters, and three groynes were built to reduce beach erosion. Reference points are located about 100 m behind the circular line that best fits the coastline, and the direction of base line is fixed to face the center of the fitting circle. Behind the emerged detached breakwater, the rate of change is up to 6.2m per year, and even in areas where structures have not yet been installed, there is a slight forward trend (0.4m/yr) due to the influence of beach nourishment. The standard deviation of the coastline position data for each base line ranges from 4.0m to 10.6m. Recently, Lim et al. (2022) presented the relationship between the standard deviation of the coastline data and sand grain size, and compared to the sand grain size results collected in the field, the grain size value was shown to be larger. The reason is that if the annual mean coastline is not maintained and continues to advance, the standard deviation increases. Considering this effect, the results are compared with observed sand gain size data. Therefore, it will be interesting to see how feasible it is to estimate the sand grain size from the analysis of long-term shoreline data obtained from satellite data, as in the results of this study.

 

 

Reference

Lim, C., Kim, T.-K., Kim, J.-B., and Lee, J.-L. (2022). A study on the influence of sand median grain size on the short-term recovery process of shorelines. Front. Mar. Sci. 9. doi: 10.3389/fmars.2022.906209

How to cite: Kim, E. H. and Lee, J. L.: Shoreline Change Analysis After Construction of Coastal Structures in Wonpyeong-Chogok Beach by Satellite Image Process, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16648, https://doi.org/10.5194/egusphere-egu24-16648, 2024.

EGU24-18146 | ECS | Orals | GM5.3

Natural dynamic vs anthropogenic transformations of the AlUla oasis, NW Arabia, during the Holocene: a combination  of geoarchaeology and geomatic approaches 

Amaury Fernandes, Laurent Lespez, Gourguen Davtian, Hatem Djerbi, Claude Rouvier, Sophie Costa, Eric Andrieux, and Louise Purdue

Oases are man-made environment in response to hydro-climatic constraints of dryland. They form landscapes of natural origin that have been modified and exploited by the agro-pastoral practices of human societies. The oasis of AlUla, in Northwestern Saudi Arabia, is settled at least since the beginning of the Bronze Age. This oasis is located at the foot of the Harrat al-Uwayrid formation which separates the sandy deserts of northern Arabia from the Red Sea. AlUla has a long history of occupation, notably through the development of major archaeological sites such as the Late Bronze Age site of Dadan, the Nabataean site of Hegra, and the old towns of AlUla and Al Mabyat from the Islamic period. Recent research has also revealed the development of agro-pastoral activities since the Neolithic and hydroagricultural development from the Late Bronze Age onwards.

The aim of this research is to reconstruct the landscape of the AlUla oasis and thus to find out in what environmental framework these agro-pastoral societies developed. It also aims to study the role of climatic changes in the natural dynamics that have formed the geomorphology of the oasis (aeolian, fluvial, slopes processes and formations) and to determine the impact of human development. These objectives are to provide answers about the understanding of the current organization of geomorphological objects and their evolution/transformation through the Holocene and thus the interactions between societies and their environment that have produced them. This work has also enabled us to produce quantitative data on the volumes of earth moved/excavated since the rampant urbanization of the oasis, and to identify the practices (quarrying vs. levelling) and geomorphological environment most affected by these earthworks.

To achieve these objectives, we have produced a diachronic geomorphological map covering the AlUla oasis and its margins, with the aim of tracing the natural history of the oasis from its current state back to the Neolithic/Early Holocene. This realization of this map is based on a combination of geomatics methods, using a DEM produced by LiDAR data (2018, 40 cm accuracy), orthophotographs (2018, 10 cm accuracy), remote sensing with satellite images (1965-2024 Google, Bing, Corona), geological data (1:500,000) and fieldwork in order to inventory landforms and determined their organization and their chronology (C14, OSL).

Our results show a long-term trend towards aridification since the second half of the Holocene and an increase in human pressure since the Bronze Age. This last observation result from the initiation and expansion of agricultural practices supported by earthworks which have led to the development of levees along wadis, agricultural terraces and anthroposols. These anthropogenic forms associated with numerous excavations have greatly modified the initial topography and therefore the geomorphology of the oasis, from the Bronze age but with an astonishing and constant acceleration over the last thirty years. This demonstrates that the natural dynamics which have prevailed during the Holocene are progressively replaced by the impact of human societies, acting as an agent of erosion in the oasis environment in NW Arabia during the Anthropocene.

How to cite: Fernandes, A., Lespez, L., Davtian, G., Djerbi, H., Rouvier, C., Costa, S., Andrieux, E., and Purdue, L.: Natural dynamic vs anthropogenic transformations of the AlUla oasis, NW Arabia, during the Holocene: a combination  of geoarchaeology and geomatic approaches, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18146, https://doi.org/10.5194/egusphere-egu24-18146, 2024.

EGU24-18350 | Orals | GM5.3

Quantifying human impact during industrialisation on the evolutionary trajectory of Vosgian streams (NE France): the value of documentary archives  

Timothée Jautzy, Nicolas Jacob-Rousseau, Salomé Berthier--Laumond, Margaux Claudepierre, Gilles Rixhon, and Laurent Schmitt

The anthropogenic pressure on European rivers has greatly intensified since the Industrial Revolution through channelisation, rectification, and building of dams and weirs. Against this background, focusing on the Vosges Mountains (NE France) is particularly relevant since it is the most densely populated mountain range in France. The Vosgian hydrographic network was accordingly impacted by widespread human modifications. No less than ~5000 hydraulic structures (HS) mostly involving weirs were built across the main streams draining the massif. Contrary to large rivers (e.g. the Rhine), the edification periods of these HS in smaller catchments remains largely unknown yet, thereby impeding a precise chronological reconstruction of the main phases of human pressure and environmental trajectories.

 

In this study, we aim to gain insight into the spatio-temporal anthropisation of three main streams draining the southern part of the Vosges, i.e. the Fecht, Vologne and Moselotte, and to evaluate their historical morphodynamic adjustments from the end of the 18th century onwards. We took advantage of the abundant paper archives, i.e. written reports, plans…, from the “Ponts et Chaussées” administration, which collected at the local scale every official request to build HS along and across streams from the 18th to the 20th century. Firstly, we characterised and mapped every weir and levee along the three studied streams to produce an updated database of the present distribution of HS. Secondly, we analysed the archives to date the construction (and in some cases deconstruction) of the HS. Finally, we reconstructed the diachronic evolution of the channel pattern, from an ancient topographical map (1866) and two orthophotos (1951, 2018). Our results allow a first quantification of human impacts: the year of construction (terminus ante-quem) could be assigned to 7%, 38% and 59% of the weirs currently present in the Fecht, Vologne and Moselotte, respectively. Most of them were probably built in the middle of the 19th century. Importantly, we also evidence a spatio-temporal correlation between the construction of HS and the simplification of the channel pattern. Although the use of historical documents has several limitations (e.g. loss, destruction, unavailability), we demonstrate that they are valuable archives that usefully complement field observations and investigations.

How to cite: Jautzy, T., Jacob-Rousseau, N., Berthier--Laumond, S., Claudepierre, M., Rixhon, G., and Schmitt, L.: Quantifying human impact during industrialisation on the evolutionary trajectory of Vosgian streams (NE France): the value of documentary archives , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18350, https://doi.org/10.5194/egusphere-egu24-18350, 2024.

EGU24-19923 | Posters on site | GM5.3 | Highlight

Reading the sedimentary archives in the Danube floodplain downstream of Vienna (Austria) 

Michael Weissl, Diana Hatzenbühler, Christian Baumgartner, and Michael Wagreich

Many human interventions in river systems, e.g., river channelization, hydropower dams, or restoration measures, affect geomorphological and sedimentological settings. Anthropogenic impact can lead to alterations in stream dynamics and sedimentary imbalances, as recorded in the sediments of large riverplains.

In the project “From Romans to the Anthropocene, from Carnuntum to Vienna: An Urban Anthropocene Field Lab” (WWTF ESR20-027) we explore long-term urban and geomorphological transformations within the Danube floodplain between Vienna (Austria) and Bratislava (Slovakia). Combining historical and sedimentological methods, our research focuses on the development of a very old settlement area within the transition zone between eastern and Central Europe.

Extensive river engineering, starting in the 19th century, was a precondition for Vienna’s development as a residence and metropolis. This includes extensive river training and the construction of flood control structures. After a long period of river engineering and the construction of many hydro-power dams along the upper Danube, around 2000 the local removal of river bank fortifications started and also the restoration of fluvial dynamics primarily within our study area downstream of Vienna, in the free-flowing river section of the Donau-Auen National Park.

Fine overbank deposits record river dynamics through climatic and anthropogenic drivers. Reading the sequence of alluvial deposits allows us to understand the human impact on floodplain morphology. The great advantage of analyzing sedimentary archives is the temporal depth they offer: we can evaluate the conditions prior to river training (~200 years ago), the effects of engineering measures (e.g. river channelization, construction of hydropower stations), and recent restoration measures as well.

The characterization of sediment archives, including sediment dating (radioactive isotopes, OSL, dendrochronology), provides information on major flooding events, changes in the flow regime, and the dynamics of sedimentation. For investigations into sedimentary processes and river morphology downstream of Vienna, it is also necessary to have a look not only at the present state of a trained river but also at the former, near-natural situation of the riverscape. Therefore, comparisons of changing river morphologies before, during, and after the erection of dams and weirs are a requirement.

 

How to cite: Weissl, M., Hatzenbühler, D., Baumgartner, C., and Wagreich, M.: Reading the sedimentary archives in the Danube floodplain downstream of Vienna (Austria), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19923, https://doi.org/10.5194/egusphere-egu24-19923, 2024.

The interdisciplinary project, titled 'Living together or apart? Unravelling the development, internal organization, and social structure of a complex Bronze Age tell settlement at Toboliu, western Romania,' seeks to analyse Bronze Age settlement activity in Toboliu, located in the easternmost Carpathian Basin. Key aspects of the study include associated land-use and landscape evolution, making the reconstruction of the tell's surroundings a focal point. The study area is dominated by loess and significantly influenced by both modern and prehistoric agricultural practices. Thus, it is a major challenge to differentiate between landscape features caused by natural soil-landscape formation processes and human activity especially for the investigated period. Within this context we focussed our research on closed depressions surrounding the tell and investigated two hypotheses regarding their formation: i) closed depressions result from human activities (such as daub extraction pits) and ii) formed through natural soil-geomorphological processes (like loess dolines or periglacial relicts). Based on core drillings, we made use of Optically Stimulated Luminescence (OSL), radiocarbon-supported, and palynological chronostratigraphical analyses. In addition, we took advantage of spatial analysis involving a high-resolution LIDAR elevation model, multispectral WorldView-3 imagery, and magnetographic data to thoroughly testing both hypotheses. Our results suggest that the examined closed depressions exhibit characteristics reminiscent of specific periglacial relict forms, more commonly known from northern European landscapes. Details will be discussed within the presentation.

How to cite: Zickel, M., Nett, J. J., Röpke, A., and Reimann, T.: Unraveling Geomorphological Processes and Anthropogenic Activity at the Eastern Border of the Carpathian Basin: Insights from the Bronze Age Tell site Toboliu, Romania, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1638, https://doi.org/10.5194/egusphere-egu24-1638, 2024.

In antiquity, the development of techniques to collect and store water was fundamental to sustain life in arid regions. One way to overcome the problem of water supply in the desert was to construct water reservoirs and cisterns which collect surface runoff during rare rain events. Indeed, open reservoirs and rock-cut cisterns are widely spread over the arid zone of the Negev Highlands / Israel. They were an important component of human activity in the area. Today, they can serve as sedimentary archives for archaeological and paleoenvironmental reconstruction. Here we provide the final assessment of a large-scale optically stimulated luminescence (OSL) dating project of water installations in the arid Negev Highlands. By sampling spoil piles, feeding channels, and accumulation of sediments within reservoirs and cisterns, the construction, the phases of maintenance and abandonment were dated. The significance of these results for reconstructing the history of human activity in the region is discussed.

How to cite: Fuchs, M., Junge, A., and Lomax, J.: Chronology of ancient water installations and the history of human activity in the Negev Highlands, Israel , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2124, https://doi.org/10.5194/egusphere-egu24-2124, 2024.

EGU24-4080 | PICO | GM5.4

Holocene overbank sedimentation in Central Europe between natural and human drivers – the Weiße Elster River (Central Germany) 

Hans von Suchodoletz, Azra Khosravichenar, Pierre Fütterer, Christoph Zielhofer, Birgit Schneider, Tobias Sprafke, Christian Tinapp, Alexander Fülling, Lukas Werther, Harald Stäuble, Michael Hein, Ulrich Veit, Peter Ettel, Ulrike Werban, and Jan Miera

Up to several meters thick fine-grained Holocene overbank deposits are ubiquitously found in most Western and Central European lowland floodplains. However, the interplay of different possible causes for their formation are not well understood yet. Most authors suggest human-induced deforestation as the main precondition for sediment mobilisation and transport from the slopes to the floodplain, generally regarding overbank sediments as human-derived ‘legacy sediments’. In contrast, others suggest a stronger influence of climatic factors. This current research gap is caused by often missing well-resolved fluvial chronostratigraphies and spatio-temporal information about former human activity within the studied catchments. To fill this gap we exemplarily studied Holocene overbank sedimentation and possible human or natural drivers in the meso-scale Weiße Elster catchment in Central Germany by using a comprehensive geoarchaeological approach: On the one hand, we applied numerical dating as well as sedimentological and micromorphological analyses to Holocene overbank sediments along three floodplain transects. On the other hand, we built up an unprecedented systematic spatio-temporal database of former human activity within the catchment from the Neolithic until the Early Modern Ages. Together with published paleoclimatic data, this database allowed an unprecedented, systematic comparison of Holocene overbank sedimentation phases with possible human and natural external controls. Our data show that some overbank sedimentation phases were directly linked with human activities in the affected site sub-catchments, whereas others were not. Instead, all phases were clearly linked with natural factors, i.e. hydroclimatic fluctuations. This difference with most former studies could possibly be explained by previously often limited numerical dating of the fluvial sediments and by largely missing spatio-temporally well-resolved regional settlement records, hindering a precise temporal link of fluvial sedimentation with former human settlement. Furthermore, this difference could possibly also be explained by a relatively high natural sensitivity of the landscape dynamics in the Central German lowlands, showing a subcontinental climate, towards external controls.

 

How to cite: von Suchodoletz, H., Khosravichenar, A., Fütterer, P., Zielhofer, C., Schneider, B., Sprafke, T., Tinapp, C., Fülling, A., Werther, L., Stäuble, H., Hein, M., Veit, U., Ettel, P., Werban, U., and Miera, J.: Holocene overbank sedimentation in Central Europe between natural and human drivers – the Weiße Elster River (Central Germany), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4080, https://doi.org/10.5194/egusphere-egu24-4080, 2024.

The Austronesian population, which consists of approximately 0.4 billion people, is widely spread across the Pacific and Indian Ocean islands. Extensive research over several decades has led to an academic consensus that the Austronesian population originated from Taiwan and the southeastern coast of mainland China. However, the exact manner in which the Austronesian ancestors arrived in Taiwan and subsequently dispersed to other oceanic regions remains a mystery. By analyzing the last deglacial sea-level rise, neotectonic activities, and resulting ancient environmental changes, as well as comparing the characteristics of middle Neolithic remains (dating back approximately 7.4-4ka) between the Taiwan Strait, we have proposed the existence of a “proto-Austronesian culture” in the early Holocene (around 11.7ka~7.4ka). This culture was centered around the nearshore area of the Taiwan Strait and Taiwan Shoal region. As sea levels gradually rose, the Austronesian ancestors’ habitat became increasingly submerged, compelling them to retreat to the inshore highlands on both sides of the Taiwan Strait. The Austronesian relics discovered on both sides of the Taiwan Strait, such as Dabenken, Keqiutou, and Fuguodun, among others, are actually branches of the Austronesian ancestors, inheriting their marine ecological characteristics. The scarcity of Neolithic artifacts older than 7.4ka on both sides of the Taiwan Strait can be attributed to a “survivor bias” phenomenon. It is plausible that numerous early Holocene relics of the “proto-Austronesian culture” remain submerged in the nearshore area of the Taiwan Strait and Taiwan Shoal, eagerly awaiting discovery through submarine archaeological exploration.

How to cite: Zhang, K. and Zhang, S.: Unraveling the Origins and Dispersal of Austronesian Culture by the last deglacial sea-level rises and paleoenvironmental changes: Insights from the Taiwan Strait, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4518, https://doi.org/10.5194/egusphere-egu24-4518, 2024.

EGU24-8532 | ECS | PICO | GM5.4

Application of shallow geophysical methods and machine learning for detecting remains of early medieval settlements in south-eastern Poland. 

Szymon Oryński, Artur Marciniak, Piotr Berezowski, Paweł Banasiak, and Justyna Cader

Poland's landscape is a testament to its deep-rooted agricultural history, characterized by ancient field systems echoing the spatial layouts in Celtic fields throughout Europe. These intricate and expansive layouts pose a significant challenge for archaeologists and researchers dedicated to uncovering the secrets of the past. The focus of this study is to meticulously explore and analyze these extensive field systems, which often cover large areas and require a detailed and systematic approach. To navigate this complex task, researchers employed cutting-edge deep learning neural networks (DLNN), particularly the U-Net model. This approach involved semantic segmentation of data derived from Airborne Laser Scanning (ALS) to automate the identification of these significant archaeological sites. The team successfully identified hundreds of ancient sites across Poland by harnessing the power of ALS data combined with thorough desk-based analysis.

The research concentrated on specific sites in southern Poland, namely in the areas around Trzebinia and Jaworzno. Various geophysical methods were utilised here, including Magnetometry and the Slingram Electromagnetic Induction Method. These techniques aimed to confirm the existence of preliminary archaeological features in the region. The researchers conducted Magnetic Gradiometry and Electromagnetic Measurements across different terrains, including cultivated fields and forests. They specifically targeted relict embankments that once delineated old fields. The findings from these investigations were striking. The geophysical profiles of the two studied areas revealed significant differences. In the first area in a current crop field, researchers observed point-like, strong anomalies in both vertical magnetic gradient and electrical conductivity. In contrast, the wooded study area exhibited weaker but continuous anomalies, suggesting the presence of buried burnt clay formations. A key aspect of this research was integrating Ground Conductivity assessments with vertical magnetic gradient evaluations. This approach was crucial in correlating data from both methods. At the first site, variations in conductivity at different depths hinted at geological transitions or man-made structures beneath the surface. Meanwhile, at the second site, resistivity patterns suggested an anthropogenic alteration of water conditions, possibly resembling an artificial fault.

Integrating a machine learning system into this research process marked a significant advancement. It facilitated the automated segmentation of ALS data, greatly enhancing the efficiency of detecting and mapping cultural resources over large areas. Combined with traditional geophysical methodologies, this innovative approach provided a non-invasive means of identifying potential archaeological objects. This was crucial for the effective management and preservation of heritage sites. In summary, this comprehensive interdisciplinary study represents a fusion of advanced technological solutions with traditional geophysical methods. It offers valuable new insights into detecting and interpreting archaeological features, potentially revolutionizing the field of archaeological exploration and heritage conservation. The research highlights the importance of integrating diverse methodologies to uncover the intricacies of our past, ultimately contributing to a deeper understanding of human history and its impact on the landscape.

How to cite: Oryński, S., Marciniak, A., Berezowski, P., Banasiak, P., and Cader, J.: Application of shallow geophysical methods and machine learning for detecting remains of early medieval settlements in south-eastern Poland., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8532, https://doi.org/10.5194/egusphere-egu24-8532, 2024.

EGU24-10076 | PICO | GM5.4

Palaeoenvironmental changes and human-environment interactions in the surroundings of La Silla del Papa, SW Spain 

Dominik Brill, Simon Matthias May, Maike Norpoth, Anna Pint, Lyudmila Shumilovskikh, Kira Raith, Gilles Rixhon, Pierre Moret, Helena Jiménez-Vialás, Ignasi Grau-Mira, Iván García-Jiménez, Dirce Marzoli, César León-Martín, Klaus Reicherter, and Helmut Brückner

The surroundings of the Strait of Gibraltar in southern Iberia are well known as a crossroads for population movements, cultural exchange and trade from Late Prehistory to Modern Times. However, questions remain about how this historical development has impacted the environment. The settlement of La Silla del Papa, an important hillfort located in the Sierra de la Plata in southern Andalusia (Cádiz), and its territory represent an ideal location for long-term studies of human-environment interactions. It was occupied throughout the entire Iron Age, replaced by the coastal town of Baelo Claudia during Roman times, and reoccupied in the early Middle Ages. Therefore, the geoarchaeological investigations in the surroundings of La Silla del Papa within the framework of the interdisciplinary project “Archeostraits” aimed at constraining the ecological conditions and human-environment interactions during the Mid- and Late Holocene and during the most important human occupation phases. Our investigations included sedimentological, geochemical, chronological (OSL, 14C-AMS, diagnostic pottery), microfaunal and palynological analyses of nine sediment profiles as well as nine vibracores from the catchment of the Río del Cachón, a small river originating in the Sierra de la Plata, just below La Silla del Papa. Our results document an early Mid-Holocene open marine embayment in what is now the lower floodplain, which rapidly transformed into a coastal lagoon and later into freshwater-dominated wetlands. After ~2100 BP, fluvial and alluvial deposition considerably increased, suggesting high anthropogenic impact on the local landscape during the Roman or post-Roman times. Palynological results reveal fluctuating agricultural and pastoral activities and suggest two distinct periods of landscape opening between 7000-6000 BP and during the Phoenician and Iron Age period.

How to cite: Brill, D., May, S. M., Norpoth, M., Pint, A., Shumilovskikh, L., Raith, K., Rixhon, G., Moret, P., Jiménez-Vialás, H., Grau-Mira, I., García-Jiménez, I., Marzoli, D., León-Martín, C., Reicherter, K., and Brückner, H.: Palaeoenvironmental changes and human-environment interactions in the surroundings of La Silla del Papa, SW Spain, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10076, https://doi.org/10.5194/egusphere-egu24-10076, 2024.

EGU24-12670 | PICO | GM5.4

Prehispanic agricultural terrace-settlement systems: an integrative approach to study land use and settlement dynamics in the southern Peruvian Andes 

Julia Meister, Christoph Binder, Laura Dietrich, Philipp Godde, Fernando Leceta, Mike Lyons, Erik Marsh, Markus Reindel, and Christian Mader

An impressive relic of the scale of human-environment interaction and land modification in prehispanic South America are agricultural terraces, covering slopes across the Andes and of which only a fraction is still in use nowadays. Despite the ubiquity of agricultural terraces in the Andes, there is a lack of systematic studies that combine the investigation of farming terraces, land use history, and settlement patterns, preventing a comprehensive understanding of prehispanic socio-economic-ecological systems and human-environmental interactions. Our project develops and applies an integrative and interdisciplinary methodological approach to the study of prehispanic Andean terrace agricultural systems and associated settlements, providing reliable data on the dynamics of land use-settlement systems through time and space. Our methodological approach consists of the application of a variety of archaeological and geoscientific methods, including archaeological and geomorphological surveys, archaeological excavations, drone surveys, mapping using satellite imagery and high-resolution digital elevation models, geographic information system applications, soil testing, phytolith and starch analysis, numerical dating, and calculations of food supply capacity and labour requirements.

We apply these to the prehispanic site of Cutamalla (3,300 m asl) in the southern Peruvian Andes, which serves as an ideal and pioneering case study. Previous research has focused primarily on the settlement of Cutamalla, particularly through large-scale archaeological excavations, but less attention has been paid to the extensive farming terraces surrounding the settlement and the close relationship between agricultural and settlement activities. By analyzing both the terrace and settlement levels, we take a new perspective and introduce the term agricultural terrace-settlement system for such complexes. Our results show that the residential occupation of Cutamalla and the use of the surrounding farming terraces coincided: the agricultural terrace-settlement system was intensively used for a relatively short period of about 200 years (~250–40 BCE) during the Formative Late Paracas and transitional Initial Nasca periods. There is no evidence of reoccupation of the site and subsequent reuse of the agricultural system. Our data also document the large extent of agricultural terraces around Cutamalla (221 ha) and that maize was likely a major crop grown there. Finally, we place these findings in their broader socio-economic and ecological context. Cutamalla was an important regional center and economic hub during a very dynamic period characterized by significant population growth and increased violence. Not only a more humid climate, but probably also forced collective labor were cornerstones of substantial agricultural production in Cutamalla and the region.

How to cite: Meister, J., Binder, C., Dietrich, L., Godde, P., Leceta, F., Lyons, M., Marsh, E., Reindel, M., and Mader, C.: Prehispanic agricultural terrace-settlement systems: an integrative approach to study land use and settlement dynamics in the southern Peruvian Andes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12670, https://doi.org/10.5194/egusphere-egu24-12670, 2024.

EGU24-14063 | PICO | GM5.4

Deciphering Hidden Ancient Human Physical and Chemical Markers through pOSL and  pXRF Analysis: A Case Study at Tel Burna 

Oren Ackermann, Martin Janovský, Polina Nikolskaia, Jan Fišer, Yaakov Anker, Yamm Anker, Tziona Ben-Gedalya, Aharon Friedman, Michal Hejcman, and Itzhaq Shai

As archeological sites are not isolated islands, they exert horizontal and vertical influence on their surrounding area. Therefore understanding the impact of these sites on their periphery becomes crucial.  Soil and sediments, as reliable historical archives, provide a unique opportunity to investigate these processes. Recent research has demonstrated that not all markers of human activity are visible, and a combination of physical and chemical methods, including pOSL and pXRF analysis, can provide insights into hidden past human signatures.

Core drills conducted at the footslope of Tel Burna In Israel's archaeological site revealed an anthropogenic unit buried within the valley. This unit also contains a layer indicative of heightened anthropogenic activity, which could either signify the remnants of an ancient field's surface or the site's abandonment, followed by rapid site erosion. Given that these drills spanned from the slope of the Tell to the valley below, we were able to track the sediment's properties from the top of the site down to the valley. It was shown that the anthropogenic influence reduced with distance from the site, resulting in increasingly intricate patterns, suggesting multiple sources of sedimentation—both natural and anthropogenic. Furthermore, the study revealed a cycle of deposits that were transported to the site from the adjacent valley through human material transport activities to be subsequently eroded back into the valley due to natural processes. In summary, the ancient archeological site during its occupation and abandonment is still a physical feature that has been contributing to the landscape cycling processes.

How to cite: Ackermann, O., Janovský, M., Nikolskaia, P., Fišer, J., Anker, Y., Anker, Y., Ben-Gedalya, T., Friedman, A., Hejcman, M., and Shai, I.: Deciphering Hidden Ancient Human Physical and Chemical Markers through pOSL and  pXRF Analysis: A Case Study at Tel Burna, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14063, https://doi.org/10.5194/egusphere-egu24-14063, 2024.

EGU24-15442 | PICO | GM5.4

A submerged Late Pleistocene hunting structure in the Western Baltic Sea 

Jacob Geersen, Marcel Bradtmöller, Jens Schneider von Deimling, Peter Feldens, Jens Auer, Philipp Held, Arne Lohrberg, Ruth Supka, Jasper Hoffmann, Berit Valentin Eriksen, Wolfgang Rabbel, Hans-Jörg Karlsen, Sebastian Krastel, David Heuskin, David Brandt, and Harald Lübke

After the retreat of the Weichselian glaciers, Northern Europe was populated by highly mobile hunter-gatherer groups. Traces of these societies are difficult to find, hampering our understanding of their life. Some remote basins of the western Baltic Sea, however, only drowned in the Holocene, and it has recently been postulated, that they preserve architectures from the Stone Age, that did not survive on land. In 2021 we documented the Blinkerwall, a stonewall megastructure located in 21 m water depth in the Bay of Mecklenburg, Germany. Shipborne and autonomous underwater vehicle hydroacoustic data as well as optical images show that the wall is composed of about 1700 stones, predominantly less than 1 m in height, placed side by side over 971 m in a way that argues against a natural origin by glacial transport or ice push ridges. Combining this information with sedimentological samples, radiocarbon dates, and a geophysical reconstruction of the paleo-landscape, we suggest that the wall was likely used as a drive lane for hunting during the late Pleistocene or earliest Holocene. Ranging among the oldest hunting structures on Earth and the largest Stone Age structures in Europe, the Blinkerwall will become important for understanding subsistence strategies, mobility patterns, and inspire discussions concerning the territorial development in the Western Baltic Sea region.

How to cite: Geersen, J., Bradtmöller, M., Schneider von Deimling, J., Feldens, P., Auer, J., Held, P., Lohrberg, A., Supka, R., Hoffmann, J., Eriksen, B. V., Rabbel, W., Karlsen, H.-J., Krastel, S., Heuskin, D., Brandt, D., and Lübke, H.: A submerged Late Pleistocene hunting structure in the Western Baltic Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15442, https://doi.org/10.5194/egusphere-egu24-15442, 2024.

EGU24-16626 | PICO | GM5.4

Micromorphological insights within the Middle Pleistocene-Holocene cave sediment record of Grotta Romanelli, Italy. 

Guido Stefano Mariani, Pierluigi Pieruccini, Davide Susini, Luca Forti, Ilaria Mazzini, and Raffaele Sardella

Grotta Romanelli (Apulia, southern Italy) is a key-site in Mediterranean archaeology. In the long history of excavations since the early 20th century, its sedimentary archive has revealed important information about human frequentation, vertebrate faunas, and environmental changes, inside a time frame which includes the Middle Pleistocene (ca. 350 ka BP) and the Early Holocene (ca 11 ka BP). The peculiarity of the sedimentary succession, which consists of fine- to very fine-grained sediments with weakly-developed or massive sedimentary structures, determined a thorough micromorphological investigation. Indeed, these sedimentary structures are often associated with human-settled cave environments. Thus, the micromorphological analysis is of utmost importance for determining the sedimentary and geomorphological context of an archaeological site. In this respect, we present for the first time the results at a more detailed scale of the depositional environments of Grotta Romanelli, in order to understand the role of sedimentary, post-depositional and anthropogenic processes in the formation of the stratigraphy of the cave.

The micromorphological investigation highlights several microfacies associated with the finer-grained sediments. The sediments within the deposit is mainly allochthonous as evidenced by the abundance of aeolian quartz and remnants of leached soils, thus indicating erosion and transport into the cave. Moreover, the characterisation of the microfacies suggests runoff and standing water processes as main agents of the internal redistribution of material. This also includes, albeit to a lesser extent, phases of biological activity, as well as phases of relative surface stability and anthropogenic contributions. Anthropogenic inputs are mainly related to fire activity and food exploitation, such as charcoal, charred plant tissue, and burnt bones. Notwithstanding the extensive volume of sediments excavated during historical archaeological campaigns, especially in the mid-frontal sectors, results show that anthropogenic inputs are not restricted to specific areas within the cave, due to its dimensions, rather they are sporadically scattered across the microfacies.

How to cite: Mariani, G. S., Pieruccini, P., Susini, D., Forti, L., Mazzini, I., and Sardella, R.: Micromorphological insights within the Middle Pleistocene-Holocene cave sediment record of Grotta Romanelli, Italy., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16626, https://doi.org/10.5194/egusphere-egu24-16626, 2024.

EGU24-20000 | PICO | GM5.4

New stable isotope geochemical approach documents grain production and manuring in the High Middle Ages 

Martin Janovský, Laszlo Ferenczi, and Jakub Trubač

Isotope analysis, particularly for the determination of δ13C and δ15N in archaeobotanical remains, is a recognized method within the field of archaeology. Until now, the primary focus of these analyses has been on archaeobotanical remains directly related to dietary practices. The significant impact of the Cistercian Order on the European agricultural landscape, and its far-reaching ecological consequences, has been well documented. However, the use of isotopic analysis for determining land-use based on present-day soils remains unexplored. The study at hand focuses on a Cistercian court, utilized from the 13th to the 15th century. The lands of this court, along with its surrounding regions, have been extensively surveyed. The isotopic analysis of the anthropogenically influenced soils is compared to approximately 400 archaeobotanical, soil, and sediment samples collected globally. The comparative analysis reveals the potential to ascertain through the presence of the C3 cycle and evidence of medieval fertilization, that the area was used for cereal cultivation and fertilization. The results of our study indicate that the medieval Cistercians employed the landscape primarily for grain production rather than pastoralism.

How to cite: Janovský, M., Ferenczi, L., and Trubač, J.: New stable isotope geochemical approach documents grain production and manuring in the High Middle Ages, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20000, https://doi.org/10.5194/egusphere-egu24-20000, 2024.

EGU24-20312 | ECS | PICO | GM5.4

Plant-wax biomarkers and their isotopes reveal complex relationships between climate, vegetation and fire during collapse of Indus Valley Civilization 

Deepak Jha, James Blinkhorn, Valerie Schwab-Lavric, Verónica Zuccarelli Freire, Jana Ilgner, Hema Achyuthan, Nicole Boivin, Ravindra Devra, S. Yoshi Maezumi, Gerd Gleixner, Patrick Roberts, and Michael Petraglia

Climate variability, especially monsoonal rainfall, has significantly shaped habitable areas for human populations in South Asia in the past just as it does today. Instances of climate-driven social disruptions and population movements are evident worldwide, as evidenced for example in the Classic Maya and the Indus Valley Civilization (IVC). However, climate change can manifest in very different ways in terms of vegetation and fire regimes, with important implications for regional environmental histories as well as socio-political patterns. As such, it is essential to develop a comprehensive understanding of the intricate interplay between climate, vegetation, fire, and archaeological evidence relating to changes in settlement patterns and continuities. Insights derived from such studies offer a foundation to explore and comprehend present and future human-environment interactions.

Here we present multi-proxy time-series datasets derived from a 2.25-meter geological trench known as ‘Jankipura,’ located within the semi-arid Thar Desert. Jankipura, located near Didwana Lake, holds prehistoric importance, being surrounded by major archaeological sites in the Thar Desert. It is also a part of the Didwana Palaeolithic Complex, surrounded by the IVC, Jodhpura-Ganeshwar, and Ahar-Banas cultural regions. The chronology of the Jankipura trench is constructed based on four 14C AMS dates ranging from 183 to 4656 cal yr. BP, aligning with the Mature phase of the IVC – a period characterized by population migration and a severe reduction in settlement density. Our analysis encompasses measurements of sediment total organic and bulk carbon isotope (d13Cbulk) composition, alongside examinations of plant-wax molecular distributions (n-alkanes and fatty acids). Additionally, we analyzed the δ13C and δ2H values of long-chain n-alkanes (C27, C29, C31, and C33) and fatty acids (C26, C28, C30, and C32) extracted from the sediment samples.

Our study also involved the assessment of macro-charcoal concentrations (>125 µm, differentiating grass from wood) to reconstruct the climate-vegetation-fire relationships during and after a major period of disruption of the IVC. The findings highlight an dry phase between 4656 and 2932 cal yr. BP, characterized by a mixed C3-C4 vegetational landscape with limited fire episodes. A significant fire episode took place during the period from 2932 to 1960 cal yr. BP, suggesting dry conditions supported by abundant C4 vegetation. Between 1960 and 183 cal yr. BP, three minor fire events occurred amid fluctuating rainfall conditions and a landscape dominated by mixed C3-C4 vegetation. The identified macro-charcoal predominantly comprised woody fragments over grass fragments. Notably, an increasing trend in isotope values, reaching its peak in macro-charcoal, is observed between 183 cal yr. BP and the present, signifying increased aridity compared to the mature phase of the IVC.

Although the study is based on a single trench, our observation of a weak relationship between vegetation and fire suggests that the reconstructed fire events may have originated from anthropogenic activities. This sheds light on the significance of vegetation, especially the utilization of wood, during the Mature phase of the IVC. We recommend generating more records from this region to better comprehend the spatio-temporal interaction of the IVC population with the environment.

How to cite: Jha, D., Blinkhorn, J., Schwab-Lavric, V., Zuccarelli Freire, V., Ilgner, J., Achyuthan, H., Boivin, N., Devra, R., Maezumi, S. Y., Gleixner, G., Roberts, P., and Petraglia, M.: Plant-wax biomarkers and their isotopes reveal complex relationships between climate, vegetation and fire during collapse of Indus Valley Civilization, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20312, https://doi.org/10.5194/egusphere-egu24-20312, 2024.

EGU24-21345 | ECS | PICO | GM5.4

Holocene relative sea-level changes and coastal dynamics in Southern Latium, Italy: an interdisciplinary investigation  

Claudia Caporizzo, Giuseppe Aiello, Vincenzo Amato, Pietro P.C. Aucelli, Diana Barra, Andrea Gionta, Giuseppe Corrado, Gaia Mattei, Gerardo Pappone, Roberta Parisi, Paola Petrosino, Marcello Schiattarella, and Matteo Vacchi

Understanding the historical changes in Relative Sea Level (RSL) and coastal responses in stable regions is crucial for unraveling the intricate relationship between natural dynamics and human adaptation. This interdisciplinary study seeks to explore the Holocene sea-level fluctuations in the stable area of Southern Latium, shedding light on how past societies adapted to coastal changes.
The study area, located in the historical Sinus Formianus, between the Fondi and Garigliano coastal plains, played a key role in ancient times. Formia, a strategic monitoring point for the Tyrrhenian Sea, was a thriving commercial hub during Roman occupation. During this period, the coastal stretch 
from Formia to Gaeta witnessed substantial urbanization, leaving behind well-preserved remnants visible today in submerged or semi-submerged coastal structures along the present shoreline.

This study reconstructs the Holocene morpho-evolution and RSL changes in the study area by creating a geodatabase following international guidelines for sea-level markers (SLMs). A comprehensive dataset of 52 SLMs was compiled from direct geoarchaeological measurements, stratigraphic and palaeoecological interpretations of new borehole data, and reinterpreting bibliographic information. Archaeological site selection involved analyzing bibliographic, cartographic, and video materials for ruins' details and dating. Additionally, public institutions provided access to an unpublished stratigraphic dataset from five deep boreholes drilled between Fondi and Formia plains in 2023. 
Three samples were collected from the stratigraphic columns of the analyzed boreholes in Formia Plain and dated using the radiocarbon dating technique. One sample, derived from a lagoonal deposit, presented an age exceeding the dating technique's accuracy range and older than 54 ka BCE. Despite this, the dating provided valuable information on the initiation of backshore formation. The other two dated samples, derived from a second drilling and collected inside layers of peat deposits, were interpreted as Terrestrial Limiting Points (TLPs) defining an upper limit of -4.20 m MSL for the RSL position at about 7.5 ka BP.
Accordingly, based on the collected data, between 8.0 and 7.5 ka BP, the sea level in the study area rose from -23 to -5 m at a rate of 25 mm/yr. Subsequently, the rate slowed to less than 5 mm/yr, stabilizing at its current position. In particular, the results coming from the geoarchaeological surveys suggest that the local sea level during the Roman period (I century BCE) was no higher than - 0.55 ± 0.29 m MSL. 
Overall, the RSL data included in the geodatabase highlights the tectonic stability of this sector during the last 2.0 ka, testified by the position of the SLMs in accordance with the GIA models and supported by the determination of average vertical ground movements rates of -0.017 ± 0.23 mm/yr.

Finally, the interplay between new data from geoarchaeological surveys, bibliographic sources, and LiDAR-based geomorphological analysis allowed the creation of a paleogeographic scenario for the study area in the 1st century CE. This highlights the significant landscape modifications induced by anthropic activities during that period.

How to cite: Caporizzo, C., Aiello, G., Amato, V., Aucelli, P. P. C., Barra, D., Gionta, A., Corrado, G., Mattei, G., Pappone, G., Parisi, R., Petrosino, P., Schiattarella, M., and Vacchi, M.: Holocene relative sea-level changes and coastal dynamics in Southern Latium, Italy: an interdisciplinary investigation , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21345, https://doi.org/10.5194/egusphere-egu24-21345, 2024.

EGU24-192 | Orals | GM5.5

From Iran to Iberia: character and evolution of sunken groundwater-harvesting agroecosystems in aeolian sand since Early Islamic times until today 

Joel Roskin, Lotem Robins, Ruben Sanchez, Adam Ostrowski, Revital Bookman, and Itamar Taxel

By compiling and reviewing data on traditional sunken groundwater-harvesting agroecosystems in aeolian sand (SGHAS) in Iran, Egypt, Gaza Strip, Algeria and Iberia we analyze the motivation, function, crop-type and abandonment of recently excavated Early Islamic- to early Crusader-period (late 9th-mid-12th century) Plot-and-Berm (P&B) agroecosystems situated along the Mediterranean coast of Israel. The SGHAS and the Early Islamic P&B agroecosystems were affiliated with nearby towns. The SGHAS enrichened the sandy substrate with local organic material, while the Early Islamic sites used local urban refuse. The extensive long-term investment in earthworks to form SGHASs was proven profitable due to prime water security in the form of continuous shallow, ~0.6-2  m deep groundwater availability coupled with rainfall for agriculture and groundwater replenishment. The SGHAS crops are mainly a wide range of vegetable types, watermelons, date palms, and grapes.

The spotty appearance of SGHAS temporally lags after the abandonment of the Early Islamic P&B agroecosystems. They appear to have independently developed since the 15th-16th century until the 19th-early 20th century. These late/post-medieval to early modern times are characterized by an unprecedented growth in the variety of food and textile crop types due to the introduction of species from arid Muslim-controlled regions and from the newly discovered Americas. This convergence exemplifies the appearance of local ingenuities derived from growing agricultural and technological knowledge and experience, crop variety and pressing needs for capital and food security. Such engineering agriculture demonstrates entrepreneurship usually supported by local administrations.

Our finds do not support a successive spatial-temporal dissemination process since Early Islamic times as occurred for qanats in western Asia, Arabia, North Africa and Iberia. The Early Islamic agroecosystems were significantly ahead of their time, possibly explaining why they were never reestablished following their abandonment. This understanding implies that the Early Islamic crops were probably partly different from those of the later SGHAS counterparts and maybe also provided inedible, profitable crops like cotton. This study demonstrates the importance of traditional analogues for interpreting archaeological research gaps of past agricultural engineering landscapes and provides a focal point for reestablishing traditionally-based, community, and sustainable agricultures.

How to cite: Roskin, J., Robins, L., Sanchez, R., Ostrowski, A., Bookman, R., and Taxel, I.: From Iran to Iberia: character and evolution of sunken groundwater-harvesting agroecosystems in aeolian sand since Early Islamic times until today, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-192, https://doi.org/10.5194/egusphere-egu24-192, 2024.

One of the first steps for geopark establishment is the recognition of geoscientific locations of interest (geosites), their description and geoconservation design. Such works can scientifically recognize their uniqueness in both regional and global scales. However, the description often requires direct identification and observation of the main sites of geoscientific relevance, which is a time-consuming, resource intensive and expensive procedure. Hence, the utilization of Geographical Information Systems (GIS) is a practical first order tool for the calculation of geodiversity values for the recognition of geosites to minimize a search area for direct observation and description of the diversity and the geoheritage of a studied region.

Quantitative assessment in these days is one of the most popular methodologies developed to identify geodiversity hotspots of area of interests in various of spatial scales. This type of approach uses indices for defining the diversity of geoscientific variables (however the applied spatial variables can vary from method to method) over the unit-sized regions of the sample area. Hence, quantitative assessment depends on the availability, accuracy, and scale of data. In this research, we used geological, pedological, geomorphological, and hydrological data that were processed within QGIS. The geodiversity index is produced by summing the normalized variety of thematic features (thematic cell value divided by the maximum cell value of that thematic variable) over a spatial unit (geology, pedology, geomorphology) and with an additional expression of the hydrological variables. By using normalization, the overrepresentation of subindices is eliminated.

Rooting from this, qualitative-quantitative methodology was created to enhance the recognition of potential geosites (hotspots) utilizing less data, a case common in remote or understudied and/or large areas geological mapping is not performed beyond 1 to 50,000 scale. The qualitative part of methodology is an evaluation system specifically tailored for each element of geodiversity included into assessment, where their (elements) number demonstrate the quantitative part of equation. Currently, the methodology utilizes three elements of geodiversity: geology, geomorphology, and hydrology calculated in QGIS software, while only geological map required for assessment. Each element has been described to emphasize features required for geosite recognition, which are rock type rareness, slope angle, and Strahler stream order for mentioned elements respectively. The result demonstrates the hotspots areas of potential geosites located in the studied region.

Both methodologies have been used for the region of Novohrad-Nógrád UNESCO Global Geopark to recognize potential geosites. Methodologies have been represented with the same 2.5*2.5 km grid size evaluated to a 5-point system to recognize their differences. Additionally, both models have been compared with the main geosite locations within an active and operating Novohrad-Nógrád UNESCO Global Geopark. The result of the project demonstrates that the similarity between the two methodologies is only 30 %, and similar areas mostly located in the “low” value areas. Moreover, quantitative methodology catching 42 already known geosites, while qualitative-quantitative recognizing 31 (for areas with high and the highest value).

How to cite: Zakharovskyi, V., Pál, M., and Németh, K.: Comparison of quantitative and qualitative-quantitative geodiversity assessment-based geosite recognition in the Novohrad-Nógrád UNESCO Global Geopark, Hungary/Slovakia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-353, https://doi.org/10.5194/egusphere-egu24-353, 2024.

EGU24-472 | ECS | Posters on site | GM5.5

Comparative analysis of methods for assessing geoheritage degradation risk 

Vittoria Vandelli, Lidia Selmi, Francesco Faccini, Andrea Ferrando, and Paola Coratza

The last 25 years have been significant in the growth of geoconservation studies and a comprehensive interest in geoheritage. To date, investigations conducted on geosites have predominantly focused on their identification, classification, and assessment. Recently, there has been a newfound emphasis on geosites mapping as well. A considerably less-explored topic in this field has been the assessment of degradation risk associated with geosites. Nevertheless, this aspect is of paramount importance, providing crucial information for their management and conservation. In fact, geoheritage is consistently under pressure from natural or anthropogenic factors and processes. In many countries, geosites are at risk of degradation or even total loss due to the absence of a systematic inventory and the resulting inadequate management. Research for the evaluation, including quantitative measures, of the risk of degradation and for monitoring the state of conservation of geosites, therefore, represents a priority for the scientific community. It should be highlighted that the recognition and prevention of threats affecting geosites still lack common investigation schemes and approaches. In this context, this paper presents the framework of a research in progress aimed at providing the first systematic and comprehensive literature review on degradation risk and related terms. A total of 284 records were identified through an extensive search across widely used literature databases. Following this initial identification, a screening process was conducted, involving the review of titles and abstracts. Through this screening, a refined selection of 177 papers emerged for further consideration in the literature review. The review is expected to help outline shared investigation schemes and approaches, shedding light on current research gaps and identifying potential areas for improvement. Additionally, insights into the terminology and concepts related to degradation risk will contribute to establishing a solid foundation for future studies in this field.

How to cite: Vandelli, V., Selmi, L., Faccini, F., Ferrando, A., and Coratza, P.: Comparative analysis of methods for assessing geoheritage degradation risk, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-472, https://doi.org/10.5194/egusphere-egu24-472, 2024.

EGU24-909 | ECS | Orals | GM5.5

The influence of the spatial assessment unit on the final outcome of the geodiversity value 

Alicja Najwer, Piotr Jankowski, and Zbigniew Zwoliński

Recently, noteworthy advancements in geodiversity studies have emerged, due to the capabilities provided by Geographic Information Systems (GIS) and increasingly accurate digital data from diverse sources. New methods of geodiversity assessment have been proposed and research on validating aggregated geodiversity ratings has emerged. Thus far, scant consideration has been given to selecting the suitable shape and size for the spatial assessment unit. This conference paper presents the outcomes of a study investigating the impact of the shape and size of primary spatial assessment unit on the final map of geodiversity. Additionally, the reliability of the assessment was evaluated through spatially explicit uncertainty analysis (UA) for three national parks in Poland representing one of three morphogenetically different landscape types: mountains, uplands, and lowlands.

The geodiversity assessment was based on global and local spatial multicriteria analysis (Weighted Linear Combination and Local Weighted Linear Combination). As part of the approach, the assessment input data, comprising geodiversity factor ratings and weights, were obtained through crowdsourcing. A GIS-based web application called the geo-questionnaire was used to collect data from Earth science expert volunteers. The study was conducted for three national parks in Poland – Karkonosze National Park (KNP), Roztocze National Park (RNP), and Wolin National Park (WNP). For each of the parks, the averaged ratings from respondents were aggregated across four selected primary assessment units, namely watersheds, geomorphological features, and grids in two dimensions: 100 x 100 m and 1 x 1 km. For each map, uncertainty analysis was conducted to account for the influence of inputs on the variability (uncertainty) of the model output. As a result, four classes were calculated representing categorical outcomes for geodiversity and its uncertainty. The evaluation of the selected primary assessment units refers to the percentage of the study area characterised by the most desirable result - a relative high geodiversity and low uncertainty, in comparison to the class of relative low geodiversity and low uncertainty.

Shape and size of the spatial assessment unit can significantly impact the final result of the assessment and, consequently, limit the practical applicability of the resulting maps for managing protected and conserved areas (PCAs). In the case of KNP, the selection of watershed as a basic unit proved to be unfortunate. Due to the transboundary nature of the park and constraints related to obtaining consistent data for the entire Karkonosze massif, delineated watershed boundaries do not accurately reflect reality. The Polish part of the park covers the northern slopes of the Karkonosze Mts., which also influenced the elongated shape of many units. The use of grids as the basic assessment units in geodiversity analysis did not show significant differences in this regard for any type of the studied landscapes. 

How to cite: Najwer, A., Jankowski, P., and Zwoliński, Z.: The influence of the spatial assessment unit on the final outcome of the geodiversity value, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-909, https://doi.org/10.5194/egusphere-egu24-909, 2024.

EGU24-1370 | ECS | Posters on site | GM5.5

What do people think about 3D geosite models? 

Edina Hajdú and Márton Pál

Geoheritage and geotourism are dynamically evolving fields, and much scientific research tries to establish their scientific communication and economic potential at the international level. Geotourism aims to present geoscience to the public through inanimate natural formations of geoscientific importance. Virtual and GIS-based solutions have been applied for years in evaluation, identification, and presentation too. In our case, a web-based platform where visitors can explore geosites through 3D models was designed to expand the scientific toolbox. For this purpose, 12 geosites were selected from the Bakony–Balaton UNESCO Global Geopark. With the web environment, geotourists can get a virtual view of sites when planning their hikes. It also provides information to those who cannot visit the geosites because of physical limitations. It can also be used as a new, interactive element in education. But is it enough to create a platform without asking people what they need?

 After the creation of the basic interface, a questionnaire was created to assess user opinions. Before filling it, it is recommended to look at least at one model, as the questions are related to it. The questionnaire contains several answer possibilities: multiple choice, rating scale, and open-ended questions are included. The first inquiry is about the structure of the website and its accessibility. This is followed by the quality of the models and their texture. One of the most important parts is where we ask about the usability of the models. At the end of the questionnaire, there was an opportunity to give personal views and opinions.

We have received 128 answers in the 3-month time of investigation. It was important to get responses from non-expert tourists and professionals too. We also tried to work with a wide age range. Only half of the respondents were satisfied with the quality of the models, the other half thought that the quality could be improved in terms of detailedness. Most votes were for "interesting", followed by "education research" on the question of model use possibilities. At the end of the questionnaire, many people chose to give their opinions and suggestions in text form. People missed pictures and annotations. The negative side of the models was sometimes confusing. Among the constructive suggestions was the idea of an overview map, where the user can spatially locate where the geosites are. The basic geological background knowledge about the sites was also missed.

The models were shared in a Sketchfab platform, and we tried to implement the proposed changes in it. The annotation of the models was easily done, providing them with the names of the geological formations and images of the information boards on the field. The view angle was also restricted to hide the negative side of the models. The website was given an overview map with the models shown as red symbols. Furthermore, the website contains a short geological description of each location and a link to read more interesting information. 

How to cite: Hajdú, E. and Pál, M.: What do people think about 3D geosite models?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1370, https://doi.org/10.5194/egusphere-egu24-1370, 2024.

Geotourism is one of the fastest growing areas of thematic tourism worldwide. Geology interpretation centers and trails (so-called ‘geotrails’) are often used as a tool to implement geotourism activities, also contributing to the sustainable development of a region. Well-designed interpretation centers and geotrails play indeed a significant role in linking geoheritage with informal geoscience education and diversifying tourism. Furthermore, the use of “citizen science” in Earth Science experienced a substantial rise in the last decade, with the goals of making research more relevant to society and increasing public awareness of environmental issues.

As part of this effort, a study was conducted on geotourism opportunities in the French Alps. Specifically, this case study includes (i) the "Glaciorium” interpretation centers at Montenvers / Mer de Glace in Chamonix (Mont-Blanc massif), a historical tourist attraction (the first visits by tourists to the Mer de Glace date back to the year 1741) which focuses on the history and the functioning of the main French glacier in the Alps; and (ii) the "Sentier des Maîtres du Mont Déserté" and "Sentier des Tannes et Glacières" in the Bauges massif (within the Massif de Bauges UNESCO Global Geopark), which focus on geohazards and deal with the effects of climate change on iced caves respectively.

The study evaluates the synergy between popular and scientific knowledge along these interpretation center and geotrails. This integration is particularly noticeable at the geotrail stops and within the interpretation center, where the significance of the various geosites is explained to visitors. The consistent integration of vernacular wisdom and scientific knowledge offers visitors a richer experience and enhances their understanding of the take-home messages.

Simultaneously, this research investigates the use of participatory approaches throughout the development of the geotrails, covering design, monitoring, and the creation of interpretive panels. A comprehensive examination of participatory methods reveals their effectiveness in enhancing community engagement and communicating geological insights to local residents, ultimately improving the dissemination of the key message to tourists.

This dual analysis highlights the importance of public participation in sustainable geotourism initiatives and provides a model for the development of a new participatory Geotrail (“The path to sustainability”) situated at the base of Monte Rosa within the Sesia Val Grande UNESCO Global Geopark (Italy). The geotrail will connect alpine landscape viewpoints, scientific observatories, geosites and cultural sites to the Walser culture interpretation center. The initiative will integrate popular and scientific knowledge, as well as active community participation. Consequently, studying existing geotrails not only serves as a valuable point of reference, but also facilitates international cooperation and networking, thus preparing the ground for the development of new and effective research initiatives.

How to cite: Guerini, M., Hoblea, F., Giardino, M., and Ravanel, L.: Enhancing community engagement in geotourism: French Alpine interpreted landscapes as a model for an innovative participatory geotrail in the Sesia Val Grande Geopark (Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1648, https://doi.org/10.5194/egusphere-egu24-1648, 2024.

EGU24-3087 | Posters on site | GM5.5

Risk assessment on dynamic sites of Earth Sciences interest 

Lucie Kubalíková

Recently, numerous approaches to the assessment of sites of Earth Sciences interest have been introduced and the conservation of geoheritage is already seen as highly important.  Although there is still an emphasis on the protection of living nature, geoconservation continuously gets more attention and recognition and it is being incorporated into some local and regional policies. Despite all these efforts, some threats may occur resulting from the multiple uses, land-use changes or human society demands on such sites. Thus, the identification, assessment and management of these threats, risks and conflicts of interest should become an integral part of every geoconservation effort.

 

For these purposes, a two-level risk assessment has been introduced. The first level of threat assessment is based on the already used criteria within geosite/geomorphosite concept and corresponds to the degradation risk evaluation. The second level is represented by the Risk Assessment Matrix, which is commonly used in regional development or project planning and may be viewed as a useful tool for assessing the threats to geodiversity sites as well. Using both approaches provides a complex view of the threats and allows to propose particular measures that could contribute to the balance of the different demands and more effective geoconservation management.

 

This study is focused on dynamic sites of Earth Sciences interest, namely abandoned sand, clay or loess pits which possess a high intrinsic value and offer numerous geosystem services. Before the proper assessment of the risks and threats, geosystem services of the abandoned pits are identified and classified proving that these sites are of great geoconservation importance. Based on the geosystem services analysis and risk assessment, geoconservation measures are proposed and sustainable use (including geotourist and geoeducational activities) of these sites is designed.

 

Keywords: Geoconservation; Dynamic sites; Risk analysis; Degradation risk assessment; Risk assessment matrix

 

References:

Kubalíková L, Balková M (2023) Two-level assessment of threats to geodiversity and geoheritage: A case study from Hády quarries (Brno, Czech Republic). Environmental Impact Assessment Review 99, https://doi.org/10.1016/j.eiar.2022.107024

 

How to cite: Kubalíková, L.: Risk assessment on dynamic sites of Earth Sciences interest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3087, https://doi.org/10.5194/egusphere-egu24-3087, 2024.

EGU24-3130 | Orals | GM5.5

Managing geoparks -Practical and application  

Jiun-Chuan Lin

Managing geoparks ---Practical and application

 

Lin, Jiun-Chuan, Department of Geography, National Taiwan University

Su, Shew-Jiunn, Department of Geography, National Taiwan Normal University

Wang, Wen-Cheng, Department of Geography, National Taiwan Normal University

Liu, Ying-San, Department Natural Resource and Environment, Tong-Hua University

 

 

Abstract

This paper mainly focuses on managing geoparks in Taiwan.

There are 10 geoparks according to the Cultural Preservation Law in Taiwan and formed a Taiwan Geoparks Networks (TGN).

 

Geo-heritage is a combination of geology and physical processes as well as the cultural characters. The awareness of the value of geo-heritage is getting more and more important in Taiwan after designation of geoparks.

The methodology to conserve the geo-heritage is rather unclear before 1985 in Taiwan. However, through designation of geoparks, the conserving geo-heritage, in terms of landscape conservation, became clearer for local people to practice.

This study demonstrates some typical ways of conserving landscapes in Taiwan geoparks. First of all, through environmental education; second, through legislation; third, through local participation on geopark affairs; fourth, through guided tour by local interpreters.

According to Environmental Education Law, everyone including all departments of different level of government workers and schools have to take 4 hours’ environmental education course every year. It helps to enhance the awareness of environment conservation including conservation of geo-heritage. By Cultural Heritage Preservation Law, the designation of geoparks and natural monuments are the tools to conserve the landscapes. Local participation as local guard on geoparks are also the ways to prevent further damages. Through interpretation on the aesthetic/ scientific value by local licensed guides for visitors, it is a way to prevent further damage by human activities.

This study demonstrates the such progresses at Taiwan Geoparks.

 

Key words: geo-heritage, geo-conservation, environmental education, Taiwan geoparks

How to cite: Lin, J.-C.: Managing geoparks -Practical and application , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3130, https://doi.org/10.5194/egusphere-egu24-3130, 2024.

EGU24-4057 | Orals | GM5.5

Exploring the dynamics of geodiversity and land cover diversity in Northern Albania 

Gáspár Albert and Drisela Kraja

Geodiversity is expressed as a geographical index. It aims to quantify the diversity of the non-living environment. Like all diversity index it serves complex analyses and comparisons. For example, comparing geodiversity and biodiversity helps to understand the relationship between the living and non-living environment and to protect it in a coordinated way. In this study, we had a similar objective: the relationship between geodiversity and land cover diversity was explored to find out the dynamics between the two indicators.

The study area is in the northern part of Albania, near Shkodra, on an area of about 1800 km2, and covers a geographic environment that is diverse in almost all respects: coastal, agricultural, urban, riverside, mid- and high mountain. These make the area remarkable for both its geodiversity and biodiversity, and although the former is not emphasised, the Theth National Park in the area aims to preserve these values.

The study was conducted using open-source GIS tools (QGIS and SAGA) at a medium scale, which also determined the 2x2 km cell size of the grid over the area. For the geodiversity index we used geological, soil, morphometric categories, and paleontological and mineral sites from published sources. For surface coverage, the 100 m cell resolution Copernicus Global Land Cover 2019 data for vegetation were used. Land cover diversity was expressed by the Shannon’s diversity index averaged over each 2x2 km cell. In addition to diversity, we also examined the connectivity of land cover categories and the degree of spatial autocorrelation. The latter was assessed for the 4 km2 tiles by the global Moran index.

The results were evaluated separately for low- and medium-altitude (<850 m a.s.l.) tiles and for high-altitude areas. The analysis was performed using Pearson correlation test. Geodiversity and land cover diversity showed a positive correlation in the lower regions, but a negative correlation in the high regions. The relationship between geodiversity and connectivity is marked by a negative correlation in low areas and a positive correlation in mountain areas. Only in low areas was there a very weak negative correlation between Moran index and geodiversity.

Consistent with previous research, our results confirmed that there is a correlation between geodiversity and land cover diversity in certain areas (low and medium altitudes). However, the negative correlation we show in high altitudes is a new result. In other words, in low altitude areas, geo- and land cover diversity go together, while in the mountains, geodiverse areas are not characterized by land cover diversity.

Connectivity plays an important role in ecological studies. Low connectivity areas with high land cover diversity at low altitudes correspond to cultural landscapes (urban, and rural areas mixed with natural habitats), which deserves special attention because of the human factor. When coupled with high geodiversity, these areas also make ideal geotourism destinations.

How to cite: Albert, G. and Kraja, D.: Exploring the dynamics of geodiversity and land cover diversity in Northern Albania, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4057, https://doi.org/10.5194/egusphere-egu24-4057, 2024.

EGU24-5421 | ECS | Posters on site | GM5.5 | Highlight

The Heritage of Frost Giants. From the Geomythologies to the Cultural Geomorphologyof Erratic Boulders in the Young Glacial Area of Poland 

Robert Piotrowski, Dariusz Brykała, Piotr Czubla, and Karol Tylmann

The erratic boulders have had a significant impact on shaping perceptions of 'environmental reality' and forming beliefs about the relationship between humans and the supernatural world in traditional culture. Establishing the ontological-axiological status of erratic boulders allowed for the cultural inclusion of these objects and the boundaries between the cultural and the natural were blurring (Burström 1999, 34; Holm 1999, 218; Tilley 2004, 23). In folk narratives, dating from the 19th, about erratic boulders one finds multiplication of belief motifs relating to the dynamics of interaction and interrelationships between humans and natural objects at utilitarian and symbolic levels (O'Rourke 2005; Knight, Harrison 2013, 186). Narratives are known about breaking erratic boulders to make millstones, which often ended tragically as these rocks were considered sacred or cursed. Erratics were attributed supernatural origins – believed to have been abandoned or brought by a giant or the devil. Many features such as cracks and natural indentations were ascribed to the influence of supernatural forces. Numerous traces of anthropogenic origin, such as broken holes, oval depressions that are the remains of millstone production were interpreted as traces of pagan sacrificial altars. We can speak here of "proper co-optation" and "symbolic co-optation" (Ingold 2002, 175). The variety of utilitarian-symbolic relationships led to ''unconscious protection of geological objects" in vernacular cultures. These phenomena were the result of the liminal – geocultural status of erratic boulders. The proposed poster aims to elucidate the network of interactions  between humans and erratic boulders. The network of polysemantic relationships enables the reconstruction of a wide range of values associated with eratics and diverse forms of interaction between people and geomorphological objects, and demonstrate strong links between geodiversity and cultural values (Reynard, Giusti 2018, 159).

This reaserch was founded by The National Science Centre, Poland - scientific grants:

The Heritage of Frost Giants. From the Geomythologies to the Cultural Geomorphology of Erratic Boulders in the Young Glacial Area of Poland” (grant no. 2023/49/N/HS3/02181), Project leader: Dr Robert Piotrowski IGSO PAS.

Memory of the stones. The origin, use and sacralisation of millstones set into the walls of Gothic churches in the South Baltic Lowlands” (grant no. 2019/35/B/HS3/03933), Project leader: Dr Dariusz Brykała IGSO PAS.

References:

Burström M. 1999. Focusing on time: disciplining archaeology in Sweden. In: Archaeology and Folklore. Eds. A. Gazin-Schwartz and C. Holtorf. London-New York, pp. 33-45. 

Holm I. 1999. Clearance cairns: the farmers’ and the archaeologists’ views. In: Archaeology and Folklore. Eds. A. Gazin-Schwartz and C. Holtorf. London, pp. 207-221. 

Ingold, T. 2002. The Perception of the Environment Essays on livelihood, dwelling and skill. London-New York. 

Knight J. Harrison S. 2013. ‘A land history of men’: The intersection of geomorphology, culture and heritage in Cornwall, southwest England. In: Applied Geography 42, pp. 186-194.

O’Rourke E. 2005. Socio-natural interaction and landscape dynamics in the Burren, Ireland. In: Landscape and Urban Planing 70, pp. 69-83.

Reynard E. Giusti C. 2018. The Landscape and Cultural Value of Geoheritage. In: Geoheritage. Eds. Reynard E. Brilha J. Amsterdam, pp. 147-166.

Tilley, Ch. 2004. The Materiality of Stone. Explorations in Landscape Phenomenology. Oxford – New York: Routledge. 

 

How to cite: Piotrowski, R., Brykała, D., Czubla, P., and Tylmann, K.: The Heritage of Frost Giants. From the Geomythologies to the Cultural Geomorphologyof Erratic Boulders in the Young Glacial Area of Poland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5421, https://doi.org/10.5194/egusphere-egu24-5421, 2024.

EGU24-6207 | ECS | Orals | GM5.5

The spatial delineation of geosites: an approach for effective management and geoconservation 

Andrea Ferrando, Francesco Faccini, Paola Coratza, and Emmanuel Reynard

When doing geomorphosite inventories, one important issue concerns the spatial delineation of the sites themselves. Several authors have proposed classifications of geomorphosites depending on their size and degree of complexity of the processes involved. Depending on the geomorphological conditions of the studied area, the perimeter of a geomorphosite can include a single landform, a cluster of landforms that may be more or less interconnected, as well as large portions of landscape (geomorphological systems). However, these typologies, and the related spatial delineation, do not take into account the possible future evolution of landforms and more in general their management and their evolution.

Indeed, in many cases, threats to the integrity of sites, be they natural or anthropogenic in origin, come from outside the perimeter of the site itself. Morphogenetic processes acting in a more or less extensive area around the geomorphosite influence its evolution and eventually its degradation. Therefore, in assessing the risk of degradation of geomorphosites and their management, one should analyze a wider area than the single perimeter, that is, the whole geomorphological system in which the site is located. In this research, the identification of a second perimeter for each geomorphosite, i.e., a "management perimeter", is proposed to be considered for the assessment of the degradation risk and geoconservation. The extent of the “management perimeter” depends on the characteristics and specificities of the geomorphosite. In some cases it may correspond with its own perimeter, in other cases it may encompass a very large area where processes influence the geomorphosite itself. The proposed approach is tested in two different areas: a mountain context – Val d'Hérens (Valais, Switzerland) – and a coastal context – Liguria (Italy). In conclusion, a typology of geomorphosites into categories for which the identification of the “management perimeter” is more or less homogeneous is proposed. This research highlights how the management and conservation of geosites should be approached with a systemic view, so as to understand how the main features of a geomorphosite interact with the active processes, natural and anthropogenic, acting in the surrounding area.

How to cite: Ferrando, A., Faccini, F., Coratza, P., and Reynard, E.: The spatial delineation of geosites: an approach for effective management and geoconservation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6207, https://doi.org/10.5194/egusphere-egu24-6207, 2024.

EGU24-6638 | Orals | GM5.5

Social well-being and knowledge of geopark values in the settlements of Novohrad-Nógrád UNESCO Global Geopark 

Judit Pappné Vancsó, Nikoletta Németh, and Laura Bertalan

Areas of the Novohrad-Nógrád UNESCO Global Geopark are considered to be the most underdeveloped parts of Hungary and Slovakia from a socio-economic view. The paper provides an overview of the results of the regional development realized by the Geopark after more than ten years of operation, and whether it is reflected in the subjective well-being of the local society and its knowledge of geopark’s values. More than 260 completed questionnaires were collected among the inhabitants of the geopark settlements and 14 in-depth interviews were conducted with those who contributed to the establishment, organization, and operation of the geopark. The results based on the obtained database clearly show that local people are aware of the values of their environment, have a close relationship with the nature around them, and are proud of it, but they are typically unaware that these are also geopark values. Many people do not know that they live in a geopark area, and the proportion of those who directly benefit from the geopark's presence is minimal. The population seemed more "geopark-conscious" in the surroundings of the geopark or tourism-related investments. The information from the in-depth interviews gives reason for optimism, as geopark-related education or dissemination of knowledge is present in the area, so it can be assumed that the growing generation is more aware of their geopark environment than those interviewed in the study.

How to cite: Pappné Vancsó, J., Németh, N., and Bertalan, L.: Social well-being and knowledge of geopark values in the settlements of Novohrad-Nógrád UNESCO Global Geopark, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6638, https://doi.org/10.5194/egusphere-egu24-6638, 2024.

Caves, as subterranean geological formations, hold scientific, cultural, and environmental significance. Show caves stand out as carefully curated destinations, providing an opportunity to explore geological processes, appreciate their aesthetic beauty, and recognize their ecological importance. This study explores the significance of show caves as subterranean geoheritage sites and focuses on their potential for sustainable cave tourism. Our primary objective is to comprehensively assess caves, while developing practical growth strategies. We introduce a novel methodology and have tested it in evaluating nine show caves in Switzerland, involving literature review, field surveys, assessments and stakeholder consultations. Addressing potential challenges and negative impacts, we analyze current tourism development and propose mitigation strategies. The Extended Show Cave Assessment Model (E-SCAM) represents a new version of SCAM (Antić et al., 2022), consisting of four groups of indicators: speleological value (SV), monitoring value (MV), infrastructure value (IV) and touristic value (TV). All indicators have their own sub-indicators that are given values (grades) from 1 to 5. The assessment process comprises two distinct stages. In the initial phase, experts evaluate and provide importance factors for each sub-indicator within the assessment model. The importance factors are average scores given by experts (1-5) in surveys. Each sub-indicator has its own importance factor, representing the experts' collective assessment of its significance within our model. For SV, the importance factor has already been determined in a previous study (Antić et al., 2022). Thus, the assessment of SV in this paper excluded the first stage of the assessment process, since we used the importance factors of SV from the previous study. Subsequently, in the second stage, authors assess and assign scores to the show caves in Switzerland. To calculate the final ratings for the explored show caves in this paper, the authors' ratings are multiplied by the previously established importance factors determined by experts. Therefore, the final ratings incorporates both the authors' opinions and the input from experts in the fields of speleology, climate, show cave infrastructure and tourism. This approach was chosen to gain a more detailed and expert-driven understanding of the significance of show cave tourism values. The study culminates in three distinct matrices: the Speleological- Touristic Value (SV-TV) matrix, the Monitoring-Touristic Value (MV-TV) matrix, and the Infrastructure-Touristic Value (IV-TV) matrix. These matrices compare the speleological, monitoring, and infrastructure values of show caves with their corresponding tourist values. The findings underscore the need for immediate action in addressing the lack of sustainable lighting systems for preservation, while highlighting generally robust infrastructure. However, concerning monitoring values, there is a significant deficit, emphasizing the necessity for enhanced climatic monitoring. The study suggests improving tourist values by implementing clearer rules of conduct, strategic marketing, enhancing guide service quality, and educating tourists on the fragility of cave ecosystems.

 

Keywords: show caves; cave tourism; Switzerland; geoheritage; geointerpretation.

 

References

 

Antić, A., Tomić, N., & Marković, S. B. (2022). Applying the show cave assessment model (SCAM) on cave tourism destinations in Serbia. International Journal of Geoheritage and Parks, 10(4), 616-634.

How to cite: Antić, A. and Reynard, E.: Cave Tourism in Switzerland: Implications for Preservation and Interpretation of Subterranean Geoheritage, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6702, https://doi.org/10.5194/egusphere-egu24-6702, 2024.

EGU24-8050 | ECS | Orals | GM5.5

Near-Surface Geophysical Investigation of Historic Mines in Ore Mountains, Czechia 

Roman Beránek, Jan Mrlina, Radek Klanica, and Eliška Vošvrdová

Keywords: Historic mines, Near-surface geophysics, Montan-archaeology, Mining heritage

The Ore Mountains are known for a considerable number of mineral deposits that have played an important role in the development of human activities at least from the early Bronze Age to recent times. This long period of prospecting and mining led to the creation of a unique mining landscape, recognised today as a UNESCO World Heritage Site. The underground mining relics, which have often been disused for hundreds of years, are an interesting target for mining archaeology and can often be converted into a mining museum. Many historic mines have an uncertain or unknown location, which, combined with the complicated relief of the mining landscape, makes excavation and further investigation a challenge. In one of the tin mining districts in the village of Hřebečná, we have investigated several sites where shallow mines from the early modern period are suspected, using a range of near-surface geophysical methods, the evaluation of historical sources, and terrain analysis. We have used microgravity survey in combination with electrical resistivity tomography and ground penetrating radar. We describe the entire process from the planning phase, including the evaluation of prior historical and geological knowledge, through to processing of observed field data. Then we discuss general capabilities of each geophysical method for the detection of voids in different states of preservation. Special attention is paid to complex interpretation in the case of conflicting results from different methods and to the determination of the most likely locations of the structures. In addition, we examine the possibility of creating density models through different modelling strategies and the reliability of models in case of significant measurement errors. The modelling includes forward modelling of the response from different scenarios with added noise according to our measurement error to estimate the detection chances for the empty, partially filled and filled mining adit, as a feasibility study, and interpretation modelling based on observed data as well.

How to cite: Beránek, R., Mrlina, J., Klanica, R., and Vošvrdová, E.: Near-Surface Geophysical Investigation of Historic Mines in Ore Mountains, Czechia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8050, https://doi.org/10.5194/egusphere-egu24-8050, 2024.

EGU24-8148 | Posters on site | GM5.5

The Cimmerian Dobrogea Aspiring Geopark from Romania: raising awareness on the geological heritage 

Andrei Briceag, Antoneta Seghedi, Silviu Radan, and Vlad Apotrosoaei

The Cimmerian Dobrogea Aspiring Geopark territory, located in the eastern part of Romania, covers an area of approximately 2,500 km2, overlapping 28 localities. It is a region with unique natural and cultural heritage, that includes an early alpine folding (Cimmerian), starting in the Upper Triassic, which reworks Paleozoic formations with a Hercynian history. The Geopark territory includes two paleontological reserves and 94 geosites, one of the most important being Deșli Caira Hill, a candidate for the international stratotype (GSSP) of the base of Anisian. The cultural heritage includes tumuli (isolated or grouped), fortresses and castra along the fortified border of the Roman Empire in the province of Moesia inferior, inner fortresses, but also many other archaeological sites, which prove a continuous habitation in this region since the Paleolithic. To raise awareness on the geological heritage, the Geopark team started a dialogue with local administration officials and school representatives to emphasize the exceptional value of the territory, by the integration of the geological, natural, and cultural elements. Thus, to highlight the geoheritage, plans are in motion to create a museum that will exhibit the geopark's most representative geological assets. In order to support the growth of this awareness campaign, our newly created Citizen Science Platform will be used. Citizen Science encourages the participation of non-professional citizens in scientific research that helps generate knowledge and information. The concept encompasses scientific activities that use volunteer "citizen researchers" for data collection, analysis, and dissemination of science, thereby consolidating their knowledge about geological heritage values.

How to cite: Briceag, A., Seghedi, A., Radan, S., and Apotrosoaei, V.: The Cimmerian Dobrogea Aspiring Geopark from Romania: raising awareness on the geological heritage, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8148, https://doi.org/10.5194/egusphere-egu24-8148, 2024.

Awareness is increasing amongst decision makers that societal challenges such as climate change, water resource management, biodiversity loss, poor soil health and air quality are interlinked. In contrast the holistic approach to Nature by pioneering 18th century natural scientists where biotic and abiotic components were interdependent, modern western science has evolved into specialised scientific disciplines. Today, science influenced global accords such as the Paris Agreement on climate change, Kunming-Montreal Global Biodiversity Framework and numerous United Nations Sustainable Development Goals place great emphasis on the biotic components of the natural world. Strategies and legislation at national level generally follow this trend and influence natural heritage management approaches.

Case studies from the Chablais UNESCO Global Geopark in France illustrate the impact of a transdisciplinary approach to natural heritage management where both biotic and abiotic factors are considered. The explicit inclusion of geodiversity informed stakeholder decisions over matters such as the choice of legal conservation measures, the definition of protected area limits and content for public communication programs. Different decisions were taken as a result of this inclusive approach to Nature in the municipalities of Montriond and La Baume. The ongoing work in the Chablais region confirms the need for scientists, natural heritage managers and politicians to share a common understanding of nature and ecosystems that explicitly includes geodiversity.

How to cite: Justice, S.: Geodiversity in Nature: Improving Natural Heritage Management , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8489, https://doi.org/10.5194/egusphere-egu24-8489, 2024.

EGU24-8730 | Posters on site | GM5.5 | Highlight

The geomorphodiversity index map of Switzerland 

Laura Melelli, Martina Burnelli, Emmanuel Reynard, and Massimiliano Alvioli

Quantitative methods to define the geomorphodiversity, the variety of landforms and surface features in a given area, are a promising approach in order to obtain an objective and reproducible working method, adopted by several scholars in a few different variants (Benito-Calvo et al., 2009; Melelli et al., 2017; Burnelli et al., 2023). The geomorphodiversity index of Italy by Burnelli et al. (2023) considers four input parameters: lithology (geological factor), slope angle and geomorphons landforms (topographic and geomorphological factors, Jasiewicz & Stepinski, 2013), and drainage density (as a corrective parameter for flat areas).

Here we focus on Switzerland that, despite its limited area, has diverse and impressive geomorphological features (Reynard, 2021). The main physiographic units (60% of the country) are the Alps, interspersed with deep valleys, such as the Rhone, Rhine, Ticino and Engadine valleys. Past and present glaciers have played a significant role in shaping the landscape. The Swiss Plateau is between the Jura Mountains to the northwest and the Alps to the south; it comprises the relatively flat and hilly lowlands of the country. The Jura Mountains, located to the northwest of Switzerland, are a lower mountain range compared to the Alps characterized by rolling hills and limestone formations, with numerous karst landforms as caves, sinkholes, and underground rivers. Lakes are a meaningful geographic feature in Switzerland, where large and small lakes are the result of glacial activity and intense fluvial erosion during the Miocene, related to the “Messinian salinity crisis” in the southern Alpine valleys. Lakes do not contribute to geomorphodiversity, in the proposed approach.

We obtain a geomorphodiversity index for Switzerland using the same approach and inputs proposed by Burnelli et al., (2023). The basics of the method are calculating the variety of the four input raster maps in GIS, with a moving window approach, casting them into five classes of variety, and combining them into a final, geomorphodiversity raster map. In addition to previous work, we consider different weights for each partial variety map, when performing the combination into the final index. This allows extra flexibility in reproducing the diversity of landforms in the different geomorphological settings of Switzerland. The map by Annaheim (1975) classifies Swiss geomorphological landscapes according to four main genetic processes (glacial, fluvial, karst, and gravitational - denudativ, in German). The weight of each parameter is different for each geomorphological unit, improving the original method, in which all of the factors had the same importance for the final index map.

This is the first Swiss geomorphodiversity map, representing a potentially valuable document for land management. It contains relevant information for biodiversity conservation and natural resource management, as well as geoheritage selection and management, and geotourism.

References

Annaheim (1975) (ed.). Geomorphologie I. Übersicht. Wabern, Atlas der Schweiz Eidgenössische Landestopographie, Plate 8.

Benito-Calvo et al, Earth Surf Proc Land (2009) https://doi.org/10.1002/esp.1840

Burnelli et al., Earth Surf Proc Land (2023) https://doi.org/10.1002/esp.5679

Jasiewicz et al., Geomorphology (2013) https://doi.org/10.1016/j.geomorph.2012.11.005.

Melelli et al., Sci Tot Env (2017) https://doi.org/10.1016/j.scitotenv.2017.01.101

Reynard (2021) (ed.). Landscapes and Landforms of Switzerland. https://doi.org/10.1007/978-3-030-43203-4

How to cite: Melelli, L., Burnelli, M., Reynard, E., and Alvioli, M.: The geomorphodiversity index map of Switzerland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8730, https://doi.org/10.5194/egusphere-egu24-8730, 2024.

EGU24-9525 | ECS | Orals | GM5.5

Bridging the gap between intangible science and society through geoheritage 

Rasia Shajahan, Benjamin van Wyk de Vries, Elena Zanella, and Andrew Harris

The realm of science and its outcomes is frequently perceived as esoteric by individuals outside the scientific field. This perception largely stems from the presentation of results, as scientists often convey their findings in a refined manner using strong technical terminology. However, this approach can be challenging for individuals with diverse backgrounds, both within and outside the scientific field. The absence of comprehension isolates such scientific work from our everyday life experiences, resulting in limited applicability and utilization of its findings. Hence, it is crucial to discover means of conveying research and findings in a more accessible and engaging manner. Achieving this can foster greater societal involvement in research, promoting participatory science—an integral yet often undervalued scientific endeavour.

Geoheritage bridges geoscience and society, facilitating the accessible communication of geoscientific results. In our study, we create three levels of simple and clear explanations (doing, seeing and theory) to illustrate one of the most useful techniques in studying the rock-forming process, AMS (Anisotropy of magnetic susceptibility), to all based on their background. AMS is an extremely useful technique with diverse applications, including identifying strain and flow sense in rocks. We studied three distinct volcanic settings serving different visitor contexts—wild trekkers, beach visitors, and walkers and created an inventory that includes both tangible geological features of outcrops and intangible elements (AMS results). The M-GAM technique enabled us to create a comprehensive geoheritage inventory and to identify the most likely candidates for presenting these results effectively to the community, ensuring an optimal strategy for subsequent outreach and interaction with both tourists and locals. This method could be useful for studies involving a wider public, using their input in the simple explanations stage to con-construct a narrative that can then be consolidated with the inventory alongside the science.

How to cite: Shajahan, R., van Wyk de Vries, B., Zanella, E., and Harris, A.: Bridging the gap between intangible science and society through geoheritage, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9525, https://doi.org/10.5194/egusphere-egu24-9525, 2024.

EGU24-9863 | Posters on site | GM5.5

From erratic boulders to sacramental emblems - the geocultural significance of millstones embedded in the walls of Gothic churches in the Southern Baltic Lowlands 

Dariusz Brykała, Piotr Czubla, Maciej Dąbski, Piotr Gierszewski, Robert Piotrowski, Zachariasz Mosakowski, Wojciech Bartz, Olaf Juschus, Waldemar Witek, Joanna Piotrowska, Karol Tylmann, Maciej Prarat, and Paweł Pogodziński

Northern Poland and North-Eastern Germany are unique in the World regions with such a large number of Gothic churches, in which walls old querns and millstones were embedded and exposed. Already the very idea of sacralising such stones, which were commonly used in hand mills, water mills and wind mills, is fascinating. There are several concepts as to why they were inserted into the walls of churches. One of them refers to the idea of the so-called Eucharistic Mill, popular in German-speaking area during the Middle Ages. An object used to make bread could not simply be thrown away after being used up.  Thanks to the fact that these stones were set into the walls of churches as early as the Middle Ages, we have an exceptional opportunity to learn about the degree of advancement in the technique of their production, use and conservation in the 13th to 15th centuries. At the same time, we were able to identify several examples of erratic boulders (in situ) with traces of production for millstones.

We identified more than 70 querns and millstones. Almost all of the examples were made from local erratic boulders (transported to the Southern Baltic Lowlands during the Pleistocene glaciations from Fennoscandia), as there were no quarries in this area. Their size varies from several centimetres to over 1 metre in diameter. Based on the millstone-eye we are able to determine whether it was runner-stone or bedstone. There have also been surviving examples with furrows still visible. Many of the millstones are semi-finished pieces, unfinished for some reason at various stages of production.

This work was supported by the National Science Centre, Poland (Grant No. 2019/35/B/HS3/03933).

How to cite: Brykała, D., Czubla, P., Dąbski, M., Gierszewski, P., Piotrowski, R., Mosakowski, Z., Bartz, W., Juschus, O., Witek, W., Piotrowska, J., Tylmann, K., Prarat, M., and Pogodziński, P.: From erratic boulders to sacramental emblems - the geocultural significance of millstones embedded in the walls of Gothic churches in the Southern Baltic Lowlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9863, https://doi.org/10.5194/egusphere-egu24-9863, 2024.

With the establishment of the European Working Group on Earth Science Conservation in 1988 and the ‘First International Symposium on the Conservation of our Geological Heritage’ held at Digne-les-Bains (France) in 1991, geodiversity conservation emerged onto a global stage. By 1993 the working group had evolved into ProGEO, the International Association for the Conservation of Geological Heritage (www.progeo.ngo). Meanwhile, the concept and practice of geological heritage had begun to be recognised elsewhere with the establishment of UNESCO’s Earth Science division and the development of the concept of Geoparks and, in collaboration with IUGS, the development of the initial concept of Global Geosites, both in the 1990s. With a formal acceptance of Global Geoparks as a UNESCO programme in 2016, the potential contribution of geological heritage to sustainable development has now been fully realised in around 195 areas across 48 countries (https://www.unesco.org/en/iggp/geoparks/about).  Meanwhile, IUGS’s new International Commission for Geoheritage (ICG; https://iugs-geoheritage.org/) has launched its Geological Heritage Sites programme, celebrating the best of global geodiversity, with the first 100 sites being listed in 2022. ProGEO, however, continues its work of promoting the philosophy and practice of geodiversity conservation, at all levels from local the global, and as an independent NGO. Of particular importance in this context was the establishment of the journal Geoheritage in 2009 as a collaboration with Springer (www.springer.com/12371) with over 1000 published papers across 86 countries having now been published – with nearly 140,000 downloads in 2022 alone. Crucially, as a partnership, ProGEO receives an annual payment from Springer, which supports its continuing activities. In addition, ProGEO has been an ongoing collaborator with partner organisations to lay the foundations for the recognition and protection of sites of geoscientific importance at every level from national to global, by establishing formal motions and recommendations through IUCN (International Union for the Conservation of Nature), hence influencing conservation practice across more than 160 countries. Currently under development through the Geodiversity Specialist Group (https://www.iucn.org/our-union/commissions/group/iucn-wcpa-geoheritage-specialist-group) of IUCN’s World Commission for Protected Areas is a programme for the recognition of ‘Key Geodiversity Areas’ (KGAs) – effectively ‘Global Geosites’ within the original 1990s concept. This project aims to establish a comprehensive and systematically selected global network of geosites to safeguard the most important stages and processes – both physical and biological - of planet Earth’s long history and ongoing evolution. Despite the quite distinct aims for KGAs from World Heritage, UGG and GHS selection and management, there is still a lot of work to be done to bring UNESCO, Global Geopark, IUGS and IUCN initiatives together towards developing mutual support and goals. In the meantime, however, the benefits for geosciences are clear if a global recognition of the importance of geosites, and geodiversity in general, can be established through international conservation designations, not least the contribution of those sites to understanding how better to sustainably manage our only planet for the benefit of future generations. Aspects of all these activities will be discussed and a vision for the future of global Geoconservation endeavour synthesised...

How to cite: Page, K.: Geoconservation, Geoheritage, Geosites – and sustainable development - the role of ProGEO at a global level, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11754, https://doi.org/10.5194/egusphere-egu24-11754, 2024.

EGU24-15403 | ECS | Posters on site | GM5.5

Landform modifications within glaciotectonic landscape due to prolonged mining activity, Muskau Arch (W Poland) 

Pinar Eksert, Jan Blachowski, Jacek Koźma, and Natalia Walerysiak

Muskau Arch is a moraine structure formed as a result of the multistage impact of the Scandinavian ice sheet. Between 1920 and 1972 intensive lignite underground and open-cast mining operations took place there. In addition to brown coal, glass sand and ceramic clay deposits were exploited, causing extensive and varied anthropogenic transformations in the entire region. Although mining activities ended approximately 50 years ago, secondary ground deformations and other post-mining processes (e.g. waste dump erosion) continue to this day. Based on the rich geological, mining and cultural heritage a Muskau Arch Geopark that belongs to the UNESCO Global Geopark Network has been established there.

The primary purpose of the landscape transformation map is to document and illustrate the extent and types of anthropogenic  transformations within the “Pustków” field of the old "Babina" lignite mine located in the Muskau Arch. 

The map was developed using free and open-source GIS software QGIS that allows for the integration of various geospatial data thematic layers and provides tools for effective analysis and geo visualization. Open data and data acquired within the NCN financed research projects were used to prepare the landscape transformation map.The concept of the graphical presentation is based on the main map and three subsidiary, insert, maps. The content of the main map includes thematic layers representing: the extent of glaciotectonic transformations, location and types of open-cast and underground mining objects, e.g.: external and internal waste dumps, abandoned pits, anthropogenic lakes, remains of mining infrastructure on the surface such as: railway tracks, shafts, extent of continuous and discontinuous ground deformations from underground mining. In addition, present day land development (built-up area, road network, stream network) against the background of terrain elevation in the form of isolines. Finally, new tourist development of the reclaimed post-mining land is presented.

 The insert maps illustrate: the location of the area of interest in the geographical context, perspective view of the anthropogenically transformed post-mining area based on present-day digital elevation model derived from aerial laser scanning data, 3D visualization of underground workings.

The compiled material is a valuable contribution to the documentation and understanding of the evolution of the post-mining landscape in the Muskau Arch area. The map can be used for educational purposes and to effectively manage the area, as it contains information on the location of mining infrastructure. The map not only shows the mining history of the region, but can help in making decisions about further reclamation of the area and promoting the sustainable development of the Geopark.

The research has been financed from the OPUS National Science Centre projects grant no. 2019/33/B/ST10/02975 and grant no 2021/43/B/ST10/02157.

How to cite: Eksert, P., Blachowski, J., Koźma, J., and Walerysiak, N.: Landform modifications within glaciotectonic landscape due to prolonged mining activity, Muskau Arch (W Poland), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15403, https://doi.org/10.5194/egusphere-egu24-15403, 2024.

EGU24-15718 | ECS | Posters on site | GM5.5

Quantitative geodiversity inventory and evaluation on the example of Slovenia 

Aleksandra Trenchovska

Geodiversity is defined as the natural range of abiotic features and processes. In this work, a quantitative GIS-based geodiversity inventory and evaluation of Slovenia is presented. Slovenia lies on the intersection of the mountain (Alps and Dinaric Alps), continental (Pannonian Basin), and coastal/maritime (Mediterranean) landscape types therefore represents a natural laboratory for geodiversity studies. To determine the geodiversity distribution pattern, an inventory of geodiversity elements was carried out. Through documental research, remote sensing methods and field validation work were identified 544.088 geodiversity elements and classified in four main categories: geological (224), geomorphological (541.505), hydrological (2.358), and topographical (1). Based on the inventory data three geodiversity parameters, including richness, abundance, and geodiversity index were calculated in a GIS environment using a 5 × 5 km grid cell size. The geodiversity index was calculated by multiplying the layers of richness and the mean of the terrain ruggedness index. To enhance the applicability of the results to tourism, education, and nature conservation, we employed the Jenks classification method to categorize geodiversity parameters into five distinct classes. The results show that the highest richness class spans across 1.65% of Slovenia's land surface, featuring a maximum of 13 different geodiversity elements within a grid cell. The highest abundance class covers 5.33% of the area, exhibiting the highest count of 6,198 geodiversity elements within a grid cell. Notably, the highest geodiversity index class encompasses 1.55% of Slovenia's territory, primarily concentrated in two prominent areas within the mountainous landscape where glacial, fluvial, and karstic processes and landforms interweave. The results help to inform scientists and managers about abiotic conservation values, and decision-making processes, fostering effective strategies for the preservation and sustainable management of biodiversity and ecosystem integrity.

How to cite: Trenchovska, A.: Quantitative geodiversity inventory and evaluation on the example of Slovenia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15718, https://doi.org/10.5194/egusphere-egu24-15718, 2024.

Many glacial landscapes on all continents are inscribed on the World Heritage List. Due to climate change, most of the glaciers are retreating rapidly, thus questioning their Outstanding Universal Value (OUV). Ice loss could indeed reduce or modify the heritage values of the UNESCO World Heritage properties where glaciers are the core of the OUV and even question their inscription on the World Heritage List. In a future with fewer or without glaciers, at least two components of the OUV of World Heritage glacial landscapes could be affected: the aesthetic value (criterion vii), which could be reduced if glaciers disappear, and the geoheritage value (criterion viii), which is partly based on current glaciological processes that would no longer exist without ice.

This presentation aims to clarify what constitute the heritage values of glacial landscapes and outlines how they could evolve in a future with less (or without) ice. For two sites in the UNESCO Swiss Alps Jungfrau-Aletsch property (the Great Aletsch Glacier and the Upper Lauterbrunnen Valley), we describe the evolution of the glacial landscape using a Past-Present-Future framework. We then evaluate the present and post-glacial heritage values according to criteria used in the literature on geomorphosites.

We outline two main issues:

1. The two sites are characterized by a very high palaeogeographical interest: the inherited glacial landforms around the Great Aletsch Glacier and Lake Oberhorn have allowed the reconstruction of Holocene glacial stages. In the future, the inherited landforms of high palaeogeographical interest and the para- and periglacial processes that develop in post-glacier conditions are likely to gain interest, while the dynamics of the glacier itself, which is an important part of the current geoscientific value, will decline and even be lost when the glacier disappears. As glaciers retreat, the geoscientific value will therefore depend more and more on the inherited glacial landforms, which allow the understanding of the Earth and climate history, and less and less on the glacier itself and its dynamics. As the inherited landforms can be fragile, are non-renewable and will become more central to the heritage value, their protection is an issue.

2. The aesthetic value of glacial landscapes could decrease because of the disappearance of the glacier (landscape greying). One possible adaptation could be a shift from glacier tourism, which is mainly oriented towards the contemplation of an aesthetic landscape, to geotourism, where the understanding of landscape evolution is proposed to the public.

How to cite: Bussard, J. and Reynard, E.: Conservation of World Heritage glacial landscapes in a changing climate: The Swiss Alps Jungfrau-Aletsch case, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16650, https://doi.org/10.5194/egusphere-egu24-16650, 2024.

EGU24-19805 | ECS | Posters on site | GM5.5

Citizen science in geoheritage: who participates in community geosite assessments? 

Márton Pál, Benjamin van Wyk de Vries, Viktor Vereb, and Gáspár Albert

Citizen science has only recently started to develop in the field of geoheritage . It is a methodology that involves the public in the study, conservation, and evaluation of geoscientific phenomena. The involvement of non-geoscientists in geoheritage tasks and processes enables collaboration between professionals and the public, harnessing the collective power of the community to collect valuable data and observations.  

One of the citizen science opportunities in geoheritage is to include visitor opinions in geosite assessment. Since the introduction of the Modified Geosite Assessment Model (Tomić & Božić, 2014), some publications have included geotourists’ opinions about scientific and infrastructural criteria in the evaluation using online questionnaires (Pál & Albert, 2020; Vereb, 2020). These can be filled in with the help of QR codes placed in the field.  

A few years ago, we designated two areas – the Chaîne des Puys in France and the Balaton Uplands in Hungary – with several geosites to analyse the modifying effect of visitor involvement in geosite assessment. Apart from the assessment results, the demographic and professional composition of questionnaire fillers can also be examined.  

In our questionnaire, we collected data at each site on each participant’s age, gender, education, profession in geosciences or tourism, distance of residence, interest in geosciences and geoheritage, and hiking frequency. These data have been compared regarding the Hungarian (1123) and French (321) completions. 

According to the results, there are more male respondents in both countries. There is a difference between the most populated age groups (France: 46-60, Hungary: 36-45). Most respondents have a university degree, but only a few percent of them are geoscientists or tourism professionals. In France, the majority is interested in geoheritage and geosciences, while in Hungary, the interest is only mediocre. The majority of French respondents live close to the subject area (<25 km), while in Hungary the largest group of respondents live more than 100 km from the sites. There is also a difference in the frequency of hiking: while most French geotourists hike at least once a week, Hungarians only hike just once a month. 

These demographic data show clear differences between geotourists in the two areas. The reasons for these differences are not yet known.  It cannot be ruled out that different geotourism assessment methods may have played a role. 

Pál, M., & Albert, G. (2021). Examining the Spatial Variability of Geosite Assessment and Its Relevance in Geosite Management. Geoheritage, 13(1). https://doi.org/10.1007/S12371-020-00528-6 

Tomić, N., & Božić, S. (2014). A modified Geosite Assessment Model (M-GAM) and its Application on the Lazar Canyon area (Serbia). Int. J. Environ. Res, 8(4), 1041–1052. 

Vereb, V. (2020). Geoheritage and resilience. Selected studies of volcanic geoheritage area from different geographical environments and different levels of protection. https://doi.org/10.15476/ELTE.2020.154 

How to cite: Pál, M., van Wyk de Vries, B., Vereb, V., and Albert, G.: Citizen science in geoheritage: who participates in community geosite assessments?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19805, https://doi.org/10.5194/egusphere-egu24-19805, 2024.

EGU24-20385 | Orals | GM5.5

Geomorphodiversity indices and geomorphological mapping: complementary contributions to landscape classification in urban areas 

Alessia Pica, Laura Melelli, Martina Burnelli, Maurizio Del Monte, Francesca Vergari, and Massimiliano Alvioli

Urban geomorphology focuses on the changes to the natural landscape caused by human activities in cities. Cities have different geological-geomorphological substrates, and several human activities have been operating within them in different times. Humans as “geomorphic agents” have been generating anthropogenic erosion and accumulation, moving a “tremendous amounts of soil and rock” since the Paleolithic [1].

Study of urban geomorphology helps understanding the natural, historical and anthropogenic landscape evolution, the changes imposed by settlements in relation with natural morphologies, and the effects of the development of cities on natural geomorphological processes.

Quantitative geomorphodiversity [2,3] describes the variety of landforms and morphological processes characterizing the landscape, representing a valuable tool for landscape classification in urban areas [4,5].

Geomorphodiversity maps can be prepared using heterogeneous spatial data, at different geographical scales. The land surface diversity index (GmI) of Italy [6] is a quantitative geomorphodiversity index, considering multiple input quantities to describe geological constraints and geomorphological processes. It uses moving windows for focal statistics operations, to calculate local diversity of slope, lithology, drainage density and terrain forms, and eventually combines these ingredients in an individual, classified raster map.

The GmI approximates field-based geomorphological maps, containing accurate representations of landforms in the real world. One relevant example of the latter, in Italy, is the geomorphological survey recently carried out in Rome, with a method that integrated field surveys, historical maps, aerial photographs, archaeological and geomorphological literature [5].

In this work, we compare the land surface diversity index, obtained with a simple and objective approach [6], with real-world geomorphological maps of 3 locations describing the rural-urban gradient of Rome urban area to understand the representativeness of the GmI, in general, and its advantages and limitations, in urban areas. The methodological approach is a simple overlay of the GmI and geomorphological dataset, in a first approximation. For the comparison, we implemented different spatial analysis techniques to build suitable density functions from both datasets, to pin down to a common ground the five diversity classes, in the GmI, and the number of landforms mapped in the field, in the geomorphological map. Most notably, the latter distinguishes natural and anthropogenic landforms along the rural-urban gradient in Rome, allowing an assessment of GmI from these substantially different points of view.

The results of this work are relevant to understand the applicability of geomorphodiversity indices for landscape classification in a data-rich area. It has the potential of paving the way for larger scale analyses of the natural and human-made landforms in rural and urban areas in Italy [7], to gain insight on how to plan and maintain a resilient urban environment.

 

[1]Bathrellos G.D., Bulletin Geol Soc Greece (2007). https://www.pmf.unizg.hr/_download/repository/clanak_1%5B1%5D.pdf

[2] Benito-Calvo et al, Earth Surf Proc Land (2009). https://doi.org/10.1002/esp.1840

[3] Melelli et al., Sci Tot Env (2017). https://doi.org/10.1016/j.scitotenv.2017.01.101

[4] Vergari et al., Rendiconti Online Soc Geol Ital (2022). https://doi.org/10.3301/ROL.2022.09

[5] Del Monte et al., Journal of Maps (2016). https://doi.org/10.1080/17445647.2016.1187977

[6] Burnelli et al., Earth Surf Proc Land (2023). https://doi.org/10.1002/esp.5679

[7] Alvioli, Landscape and Urban Planning (2020). https://doi.org/10.1016/j.landurbplan.2020.103906

How to cite: Pica, A., Melelli, L., Burnelli, M., Del Monte, M., Vergari, F., and Alvioli, M.: Geomorphodiversity indices and geomorphological mapping: complementary contributions to landscape classification in urban areas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20385, https://doi.org/10.5194/egusphere-egu24-20385, 2024.

EGU24-20881 | Posters on site | GM5.5

Hitchikers’s Guide to Capri Island’s Geotourism, Italy 

Francesca Vergari, Martina Nicole Verga, Carlo Donadio, and Alessia Pica

Mass tourism affects Italian minor islands during summer, and the main attractions are seaside and boat tours, together nightlife. Nevertheless, the islands are hotspots of Mediterranean geodiversity, biodiversity, and culture. This study presents a geotourist itinerary on Capri Island based on a geomorphological survey and mapping, geoheritage inventory, and evaluation for geotourism purposes. This research highlights Capri’s geosites’ scientific, scenic and cultural values as an alternative to mass tourism focused on the coasts. The Island of Capri is the best-known Italian island worldwide, so it could be sampled for the valorization of other islands through geotourism. On the Island of Capri, 8 geosites have been inventoried and evaluated, and an itinerary is proposed mainly based on terrestrial geosites, summarizing naturalistic and cultural values. The itinerary is implemented in Google Earth Pro TM to be available remotely and on-site. Geo-interpretation of the patrimony makes it accessible to the lay public, promoting its popularization and the development of more sustainable recreational activities on the island.

How to cite: Vergari, F., Verga, M. N., Donadio, C., and Pica, A.: Hitchikers’s Guide to Capri Island’s Geotourism, Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20881, https://doi.org/10.5194/egusphere-egu24-20881, 2024.

EGU24-20888 | Orals | GM5.5

Virtual field sites at the UNESCO Geopark Serra da Estrela (Portugal) 

Gerald Raab and Gonçalo Vieira

Virtual field sites are increasing in popularity beyond classrooms. Also, field investigations greatly benefit from DGPS-referenced 3D models. We show a selection of field sites at the UNESCO Geopark Serra da Estrela (Portugal) and how they were implemented into field research. In detail, the advantages of high-definition virtual models of tors, i.e., large residual vertical rocks that are still enrooted in bedrock, were explored in the modeling of the recently conceived tor exhumation approach (TEA; Raab et al., 2018) that can trace surface degradation over a multimillennial period within the landscape of interest. The TEA uses in-situ terrestrial cosmogenic nuclides (TCNs) to surface exposure date (SED) along the surfaces of tors.

Animated tors of two endmember sites, formerly glaciated and non-glaciated, contributed to derived continuous surface denudation variations covering the last ~200 ka and revealed glacial retreat dynamics in good detail. Higher isotope contents, thus, surface exposure ages were found in the non-glaciated area. In the formerly glaciated site, the ice margin distance correlates with the isotope signature of the tors. Higher elevation tors have experienced mass wasting and water erosion during the transition from a cool, moist, oceanic-Mediterranean climate. There, the younger rock surfaces have a higher chemical weathering degree than older surfaces at the non-glaciated site.

In summary, we provide freely available 3D field sites coupled with an extensive geomorphological study of these landscape features.

How to cite: Raab, G. and Vieira, G.: Virtual field sites at the UNESCO Geopark Serra da Estrela (Portugal), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20888, https://doi.org/10.5194/egusphere-egu24-20888, 2024.

EGU24-21186 | Orals | GM5.5 | Highlight

Geosites that are out of this world: an example of  planned development of Morasko (Poland) impact crater educational activities 

Anna Losiak, Agnieszka Kryszczyńska, Andrzej Muszyński, Dagmara Oszkiewicz, Witold Szczuciński, Monika Szokaluk, and Anna Wierzbicka

Impact craters are rare and important geosites: 

Asteroids are constantly colliding with our planet. Some of them have enough energy to form impact structures that can vary in size from tens of meters (e.g., Kaali in Estonia: [1]) to hundreds of kilometers (Vredefort in RSA: [2]). Due to their rarity (~200 terrestrial impact sites are known: [3]) and a certain level of mystery and attractivity provided by their extraterrestrial genesis, impact craters are prime locations for teaching about Earth and planetary sciences. 

Museums and/or geoparks were built near many impact sites e.g.: Chicxulub museum [4], Kaali Meteoritics and Limestone Museum, Meteor Crater Barringer Space Museum, Odessa Meteor Crater Museum, Ries Crater Museum Nördlingen [5], Meteorite Museum, Rochechouart. Most impact sites, even if they are formally protected, are not associated with a museum. 

Morasko craters: 

Morasko impact site [6] consists of a group of seven craters located in central Poland. All of them formed at the same time ~5 ka, due to fragmentation of an IAB asteroid during passage through the atmosphere. The largest structure is 100 m in diameter. Multiple fragments of the impactor were found. It is one of only six known strewn fields on Earth, and the only one that is located within a large city limits (Poznan) and and next to an international airport. 

Morasko is currently utilized for educational and tourist purposes to a limited degree. The site is formally protected (Morasko Meteorite Nature Reserve), and there is a slightly deteriorated, but well designed educational path. Some pieces of Morasko meteorite (along with a collection of other meteorites) are curated in the nearby geological museum of Adam Mickiewicz University, however, access to this display is possible only for a couple of hours a week (upon previous appointment).

The goal: 

As a newly formed committee, within the next 10 years, we plan to establish a museum of natural sciences at the Morasko site. We want to make use of this amazing site to teach people about the: planetary geology, astronomy and natural hazards. 

During the conference we would like to present the case for Morasko, and receive advice and support in order to make this plan a reality. 

[1] Losiak et al. 2016. Dating Kaali Crater (Estonia) based on Charcoal emplaced within proximal ejecta blanket. MAPS 51:681–695.

[2] Huber et al. 2023. Can Archean Impact Structures Be Discovered? A Case Study From Earth's Largest, Most Deeply Eroded Impact Structure. JGR:Planets. 128 (8).

[3] Osinski et al. 2022. Impact Earth: A review of the terrestrial impact record, Earth-Science Rev. 232:104–112 

[4] Urrutia-Fucugauchi et al. 2020. Chicxulub museum, geosciences in Mexico, outreach and science communication – built from the crater up. Geosci. Commun. 4:267–280, 

[5] PöSges 2005. The Ries Crater Museum in Nördlingen, Bavaria, Germany. MAPS 40:1555-1557.

[6] Szokaluk et al. 2019. Geology of the Morasko craters, Poznań, Poland —Small impact craters in unconsolidated sediments. MAPS54:1478–1494.

 

How to cite: Losiak, A., Kryszczyńska, A., Muszyński, A., Oszkiewicz, D., Szczuciński, W., Szokaluk, M., and Wierzbicka, A.: Geosites that are out of this world: an example of  planned development of Morasko (Poland) impact crater educational activities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21186, https://doi.org/10.5194/egusphere-egu24-21186, 2024.

EGU24-21798 | Orals | GM5.5

Geoheritage Assessment of Geosites in NEOM, Saudi Arabia: in the perspective of Geotourism and Geoconservation 

Subhajit Sen, Mohamed O. Abouelresh, Ali Almusabeh, Fahad S. Al-Ismail, Bruno Pulido, and Thadickal V. Joydas

Geosites comprise geomorphological sites and geological sites with significant scientific value. Geotourism promotes such natural landscapes and opens opportunities for regional development with economic benefits. NEOM is a new regional development, part of the Vission 2030 of Saudi Arabia, born from sustainability, conservation of nature, development and tourism. In the absence of adequate data on geosites, this study aims to assess various geological, and geomorphological sites in NEOM. Fourteen geosites were identified from fieldwork, and a description card was prepared. The scientific, educational, tourism, and degradation risk value of geosites has been analysed. Based on qualitative study, inventory developed on key landforms like yardang, canyons, gully, evaporite hills and submarine landscapes according to the geological provinces with a detailed description card. The assessment indicates tectonic, weathering, coastal, and marine landform diversity in a region with moderate to high scientific, educational, and touristic value. Enumerable archaeological imprints are associated with the potential geosites, and ecological importance related to the geosite enhances the significance of the site. However, the chances of landform degradation are low to moderate. Considering the sustainable development approach of NEOM, geotourism will be an alternative opportunity for regional development.

How to cite: Sen, S., O. Abouelresh, M., Almusabeh, A., S. Al-Ismail, F., Pulido, B., and V. Joydas, T.: Geoheritage Assessment of Geosites in NEOM, Saudi Arabia: in the perspective of Geotourism and Geoconservation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21798, https://doi.org/10.5194/egusphere-egu24-21798, 2024.

EGU24-1796 | Orals | HS9.3

Assessing the impact of soil decontamination on radiocesium and sediment transfers in a catchment affected by Fukushima nuclear accident, Japan, using a reservoir sediment core. 

Thomas Chalaux-Clergue, Pierre-Alexis Chaboche, Sylvain Huon, Seiji Hayashi, Hideki Tsuji, Yoshifumi Wakiyama, Atsushi Nakao, and Olivier Evrard

Significant quantities of radionuclides including a majority of 137Cs have been deposited onto Fukushima landscapes following the accident of Fukushima Dai-ichi Power Plant in March 2011. Starting from late 2013, the Japanese government initiated a large-scale decontamination programme for cropland, residential areas, grassland and forest borders, which was conducted on 12% of the catchment area (8.2 km2) while forest, which is the dominant land use (88%), was not decontaminated. The surface layer of cropland and residential soils (~5 cm) concentrating radiocesium (134Cs, 137Cs) was removed and substituted with a fresh soil -composed of saprolite layer mined at local quarries- which represent 3% of the catchment area (1.8 km2). Thirteen years after the accident, questions remain regarding the fate of residual particle-bound 137Cs across terrestrial environments in response to extreme precipitation (e.g. tropical storm, typhoon, extra-tropical cyclone) and associated erosion events. In particular, there is a need to identify and quantify the sources delivering sediment and associated 137Cs to the water bodies, to reconstruct and evaluate the impact of decontamination on sediment and radiocesium transfers. To conduct this project, one sediment core was collected in undisturbed condition in June 2021 at a downstream location of the Mano Dam reservoir, which drains an early decontaminated catchment (67 km2) (2014–2016). Elemental geochemistry, organic matter, visible colorimetry, particle size, and radiocesium analyses were conducted on the sediment core, with depth increments of 1 cm. These analyses were used to provide multiple lines of evidence to define and interpret the major precipitation events recorded by the sedimentary sequence. Then, the sediment source fingerprinting technique allowed, with a multiple modelling approach (MixSIAR and BMM), to identify changes in sediment sources with variable contributions from forest, cropland, and subsoil (e.g. channel bank, fresh soil) throughout time. During abandonment (2011–2016), the contribution from cropland sharply decreased (from ~50% to 30-35%) while forest increased (from ~40% to 60-65%). Nevertheless, after the completion of decontamination, in late 2016, a significant increase of cropland contributions was observed, returning to the pre-accidental level in the most recently deposited sediment (~55%). It occurred concomitantly with that of sediment originating from the freshly-added soil (i.e. granite saprolite; from about 5% to 25%), reflecting the impact of decontamination. During abandonment, the 137Cs activity in sediment was reduced by 40%, such as the 137Cs flux per extreme event, which was reduced by 20%. After the completion of decontamination, although a strong decrease in 137Cs activity in sediment was observed (up to -60%), it was not associated with such a significant decrease as 137Cs flux per extreme event (0% to -20%). This suggests that the reduction in 137Cs activity in the sediment following decontamination may result from a dilution of contaminated sediments originating from forest with sediment originating from decontaminated cropland fresh soil rather than the removal of contaminated soil in designated areas. To understand the impact of natural soil protection against erosion through revegetation on 137Cs flux over a longer abandonment time, studying sediment cores from lately decontaminated catchment would be useful.

How to cite: Chalaux-Clergue, T., Chaboche, P.-A., Huon, S., Hayashi, S., Tsuji, H., Wakiyama, Y., Nakao, A., and Evrard, O.: Assessing the impact of soil decontamination on radiocesium and sediment transfers in a catchment affected by Fukushima nuclear accident, Japan, using a reservoir sediment core., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1796, https://doi.org/10.5194/egusphere-egu24-1796, 2024.

EGU24-1821 | ECS | Orals | HS9.3

Impact of soil erosion on chlordecone insecticide transfers in a tropical volcanic cultivated subcatchment 

Rémi Bizeul, Oriane Lajoie, Olivier Cerdan, Lai-Ting Pak, and Olivier Evrard

Between 1972 and 1993, in the French West Indies, chlordecone – a toxic organochlorine insecticide – was applied to control the banana weevil. In the late 1990s, the intensification of agricultural practices (i.e. intensive ploughing, herbicide application) under banana plantations is expected to have led to accelerated soil erosion and sediment transfers (Bizeul et al., 2023) to aquatic systems and, ultimately, to marine environments (Sabatier et al., 2021). Due to the high affinity of chlordecone for organic matter and its hydrophobicity, these sediment transfers are associated with chlordecone remobilization (Mottes et al., 2021) and pesticide transfers along the land-to-sea continuum. Nevertheless, the links between soil erosion, sediment and chlordecone transfers are not well understood. The investigation of these processes is therefore essential to manage chlordecone transfers along the land-to-sea continuum.

To this end, three sediment cores were collected in an agricultural reservoir (Saint-Esprit, Martinique) and five soil cores (one-meter depth) were sampled along a transect in a banana plantation draining to the reservoir.

Regarding sediment cores, age-depth models were drawn for each core using short-lived radionuclide activities (Bruel et Sabatier, 2020). Furthermore, dry bulk density was measured to calculate mass accumulation rates. Moreover, chlordecone and organic carbon contents were measured on three cores. Overall, results show a correspondence between the increase of sediment supply to the reservoir and that of chlordecone and organic carbon fluxes. In particular, chlordecone fluxes showed an increase since 1999 (± 4 years, depending on the cores) from 200 µg.kg-1 to 600-750 µg.kg-1.

Regarding soil cores, radiocesium activities were measured in 5-cm increments and chlordecone contents were measured in a selection of 2 cores (uplslope and downslope of the transect). On the upper hillslope part, chlordecone contents showed a strong increase at 20 cm, from 255 µg.kg-1 to 591 µg.kg-1, in line with radiocesium activity increase, from 0.5 Bq.kg-1 to 1.4 Bq.kg-1. On the lowest hillslope part, chlordecone contents showed a strong increase at 70 cm, from 520 µg.kg-1 to 1220 µg.kg-1. Based on these results, we assume that chlordecone distribution follows erosion pathways and can accumulate on the foot slope of this banana plantation. Furthermore, in contrast, constant chlordecone contents observed in the upper part of the profile in each core (i.e. 20 and 70 cm) suggest an homogenization of the soil profile, probably due to ploughing operations carried out every 6-8 years for cyclical banana re-plantation.

Overall, these results confirm the transfer of chlordecone with soil particles along a cultivated hillslope and, ultimately, in the sediment deposited in the reservoir. We assume that these processes also reflect land use changes and the occurrence of erosive tropical climatic events. Further work is needed to confirm the validity of these results to other cultivated catchments across the French West Indies.

How to cite: Bizeul, R., Lajoie, O., Cerdan, O., Pak, L.-T., and Evrard, O.: Impact of soil erosion on chlordecone insecticide transfers in a tropical volcanic cultivated subcatchment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1821, https://doi.org/10.5194/egusphere-egu24-1821, 2024.

EGU24-3464 | Posters on site | HS9.3

Reservoir sediments in central Europe as archives of human-environmental interaction during the past 115 years - the example of the Urft Reservoir 

Georg Stauch, Lukas Dörwald, Alexander Esch, Eberhard Andreas Kümmerle, Frank Lehmkuhl, Philipp Schulte, Christina Schwanen, and Janek Walk

The mid-European landscape has been influenced by humans since several millennia. In the Eifel Mountains in western Germany, mining and ore processing in combination with land-use changes considerably altered sediment composition and sediment fluxes. While there have been frequent studies to reconstruct changes in sediment fluxes on the long term, considerably less research focused on the past century. To decipher the recent human influence on the landscape, the sediments of the Urft Reservoir in the northern Eifel Mountains were analysed. The Reservoir started operation in 1905, and was the largest reservoir in Europe at this time. In November in 2020 the reservoir was drained for construction works, offering the unique possibility to analyse sediment volume and composition.

A high resolution sediment budget for the past century was calculated using topographical maps with a scale of 1:1000 created prior to the construction of the reservoir. For the most recent topography the entire lake area was photogrammetrically surveyed using an uncrewed aerial system (UAS). Mean accumulation in the whole reservoir was around 1.54 m and regionally above 6 m.

Additionally, 24 cores were retrieved from the bottom of the reservoir. A range of different sedimentological proxies including grain-size, heavy metals, geochemical ratios, sediment colour and microplastics were analysed. An absolute chronology was established based on 137Cs dating. Up to four different sedimentary units could be distinguished in the cores. The upper two units consist of reservoir sediments and were deposited between 1905 and 2020. The heavy metals content in these sediments show a strong connection to historical changes in the ore industry in the Urft valley. The decline of the metal processing industry as well as stricter environmental protection laws resulted in a reduced input of lead, copper and zinc from the 1960s to the 1980s. Since that time the content has remained relatively constant. Microplastic particles appear in the sediments since the mid-1960s. Furthermore, a distinct layer of high microplastic content was recorded in the cores. This event-layer could be traced back to a major fire in a glassworks and plastics factory in 1991 in the upper Urft catchment.

In summer 2021, the northern Eifel Mountains were impacted by a catastrophic flooding event, resulting in massive destructions in the catchment of the Urft and strong relocation of sediments in the floodplain. To assess these geomorphologic changes in the Urft reservoir, the water level was lowered again in December 2021 and an additional UAS survey was conducted. Furthermore, additional sediment samples were taken. However, we could neither observe any significant changes in the heavy metal content in the flood sediment nor asses the sediment input by the flooding event. The topographic changes due to the flood were generally to low and within the error margins of our method (0.5 m).

How to cite: Stauch, G., Dörwald, L., Esch, A., Kümmerle, E. A., Lehmkuhl, F., Schulte, P., Schwanen, C., and Walk, J.: Reservoir sediments in central Europe as archives of human-environmental interaction during the past 115 years - the example of the Urft Reservoir, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3464, https://doi.org/10.5194/egusphere-egu24-3464, 2024.

EGU24-3953 | Orals | HS9.3

Can beavers clean our streams? A study from three agricultural catchments in south-west England 

Gareth Bradbury, Alan Puttock, Gemma Coxon, Stewart Clarke, and Rich Brazier

In common with many European streams, most streams in south-west England have failed to reach Good Ecological Status under the Water Framework Directive. The landscape comprises mainly pastoral and arable fields, from which rainwater can run off, carrying huge quantities of sediment and surplus fertiliser. The receiving streams, often highly modified through channelisation, are degraded from the physical, chemical and biological effects of these pollutant loads, most notably high nutrient and fine sediment inputs leading to eutrophication. 


After an absence of 400 years, Eurasian beavers Castor fiber are now being re-introduced into some of these landscapes, or are colonising naturally from nearby introductions. Through the building of their dams and creation of diverse, ponded wetland environments, beavers have been shown to deliver multiple ecosystem services, including flow moderation, habitat provision and water quality improvements.

 
Encompassing highly productive, vegetation-rich shallow areas and deeper, oxygen-limited areas with different nutrient-cycling pathways, beaver wetlands have the potential to improve water quality through the settling out of solids and uptake and cycling of nutrients. By contrast there are periodic releases of solids and nutrients due to burrow and canal excavations, dam breaches and nutrient inputs from the beavers themselves and the diverse fauna and flora supported in their wetlands.

 
To examine the potentially dynamic effects of beavers on the transfer of sediments and contaminants (nutrients) in catchments, this study used fortnightly water sampling at the inflow, outflow and upstream and downstream of three beaver re-introduction enclosures over two years. In addition, automated samplers were deployed to investigate finer temporal resolution responses to rainfall events. 


For each site, suspended solids, nitrogen, carbon and phosphorus concentrations and loads were determined. Sediment storage dynamics were revealed through the novel use of sonar monitoring in ponds and continuous in-situ turbidity sensor measurements at the inflow and outflow.

 
Results demonstrate the dynamic nature of sediment and nutrient reduction in beaver-engineered wetlands, with switches between source and sink states depending on inflow conditions and pond-specific factors. Beaver wetlands were shown to remove nutrient pollution where inflow loads were high and the mixed temporal and spatial dimensions of this study help resolve differences in results between previously published studies.

How to cite: Bradbury, G., Puttock, A., Coxon, G., Clarke, S., and Brazier, R.: Can beavers clean our streams? A study from three agricultural catchments in south-west England, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3953, https://doi.org/10.5194/egusphere-egu24-3953, 2024.

EGU24-6153 | ECS | Posters on site | HS9.3

Robust River load estimation of micropollutants: Method validation on an extended micropollutants dataset 

Nikolaus Weber, Steffen Kittlaus, Radmila Milacic, Jörg Krampe, Ottavia Zoboli, and Matthias Zessner

Many anthropogenic sources discharge thousands of micropollutants into surface waters, which can pose a risk to human health and the environment. Monitoring provides a better understanding of the occurrence and transport dynamics of these pollutants and is the basis for mitigation measures as well as valuable validation loads for pollution transport models. As conventional monitoring methods do not provide the full picture in terms of transport dynamics (Weber, 2023), there is a need for more specific monitoring methods.

To prove this statement, a one-year monitoring program was established at two Austrian rivers, namely the Wulka and one of its tributaries. The locations are strategically located to capture different catchment properties. This monitoring program consists of monitoring stations at each river equipped with automatic samplers and online measurements of flow, turbidity, and conductivity. The monitoring is carried out by a one-year sampling program to cover the variability of micropollutants over a whole year by taking both volume-proportional composites and grab samples at a biweekly interval. The samples are then analyzed in labs and for total suspended solids (TSS) and various micropollutants from the group of heavy metal, pharmaceuticals, pesticides and PFAS.

Turbidity events are an important transport factor for many micropollutants and therefor need to be considered for annual load calculation (Weber, 2023). We therefor integrated online turbidity data with the pollutant measurements to enhance accuracy of current load calculation methods. Those calculated annual load were validated on the monitoring data from the monitoring campaign to ensure robust results. The biweekly resolution of the monitoring data allowed for detailed analysis to reveal patterns, trends and anomalies that could impacted the load estimation. This led to a comparison of the methods and suggestions to improve their robustness.

This research helps to understand river transport dynamics of TSS and micropollutants towards robust estimation of annual micropollutant loads in rivers to improve future monitoring campaigns and annual load calculation for pollution transport model validation.

How to cite: Weber, N., Kittlaus, S., Milacic, R., Krampe, J., Zoboli, O., and Zessner, M.: Robust River load estimation of micropollutants: Method validation on an extended micropollutants dataset, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6153, https://doi.org/10.5194/egusphere-egu24-6153, 2024.

EGU24-6366 | ECS | Posters on site | HS9.3

Environmental and physical factors controlling the distribution of 137Cs in lake sediments in the Southern Hemisphere: a meta-analysis 

Floriane Guillevic, Olivier Evrard, Pierre Sabatier, Anthony Foucher, Gerald Dicen, and Christine Alewell

For decades the artificial radionuclide 137Cs has been used as an independent time marker to ascertain the 210Pb chronology to date recent sediments from the Anthropocene period (<150 years). The distribution and depositional timing of man-made fallout radionuclides (FRN) are well constrained in the Northern Hemisphere, where most nuclear weapon test sites were located. The maximum deposition year of 1963 is usually marked by a 137Cs peak. Although the major nuclear powers stopped testing in 1963, France continued to test atmospheric nuclear bombs (1966-1974) in French Polynesia in the Pacific (Moruroa and Fangataufa atolls). This later and prolonged period of French bomb testing in the Southern Hemisphere may have resulted in a wider distribution with higher FRN levels in depth profiles of environmental archives, such as lake sediment cores.

To test this hypothesis, a literature review was conducted (n=124), in which 137Cs data were collected from lake sediments (including dam reservoirs and lagoons) across the Southern hemisphere. Decay-corrected 137Cs activities, 137Cs inventories (where available) and parameters of the 137Cs profile shape have been reported for many countries and latitudinal bands. In addition, environmental and physical parameters were reported for each lake site. Global parameters influence the atmospheric distribution and deposition of FRN such as the distance from the nuclear test site, the wind distribution (relative to the Intertropical Convergence Zone position), the wind direction (westerlies vs trade winds) and the annual precipitation. Conversely, local scale parameters such as sedimentation rate, catchment to lake area ratio, and maximum elevation difference will influence the depositional processes of FRN in lake sediments. A meta-analysis of these parameters will help to identify parameters that are crucial for understanding the 137Cs distribution across the Southern Hemisphere. Based on these results, we selected the new sampling sites, which are likely to reflect mainly FRN atmospheric input, for further reconstruction of fallout radionuclide chronologies in the Southern Hemisphere.

How to cite: Guillevic, F., Evrard, O., Sabatier, P., Foucher, A., Dicen, G., and Alewell, C.: Environmental and physical factors controlling the distribution of 137Cs in lake sediments in the Southern Hemisphere: a meta-analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6366, https://doi.org/10.5194/egusphere-egu24-6366, 2024.

Suspended sediment is closely linked to nutrients, pollutants, and heavy metals, profoundly affecting aquatic ecosystems and widely recognized as a vital indicator of inland water health. Consequently, Suspended sediment concentration (SSC) can affect the growth of aquatic organisms in fish ponds, posing a substantial threat to aquaculture production. However, research on the long-term spatial and temporal dynamics of SSC, along with its response to various natural and anthropogenic factors in small water bodies like fish ponds, remains relatively scarce. This study aims to recalibrate current unified models using measured data to derive a more applicable SSC retrieval model specifically for the Guangdong-Hong Kong-Macao Greater Bay Area (GBA). Using Landsat top-of-atmosphere reflectance data from Google Earth Engine (GEE), the recalibrated model was utilized to generate SSC data for fish ponds in GBA spanning from 1986 to 2019.The results indicate that SSC in GBA fish ponds is significantly elevated during spring and summer compared to autumn and winter, with spring SSC recording the highest levels in most years. In the last 34 years, there has been a substantial overall decline in SSC in fish ponds, with an almost 50% reduction in the annual average SSC. Notably, this reduction was most pronounced in the northern, western, and eastern regions, resulting in a spatial pattern of higher SSC concentrations in the central and southern areas and lower concentrations in the surrounding regions. Correlation analysis unveiled substantial relationships (P < 0.01) between SSC interannual variations and factors like wind, speed, river sediment load, and NDVI, except for precipitation (P > 0.05). The surrounding land use of fish ponds and their proximity to rivers emerged as critical determinants influencing the spatial distribution of SSC. Furthermore, diverse aquaculture activities, such as the pond's farming cycle and production, play a significant role in regulating SSC, thereby influencing its temporal and spatial variations. GBA is one of China's highly developed aquaculture regions with dense populations, thus rendering the findings of this study valuable from both economic and ecological perspectives.

How to cite: Zhou, T. and Yang, X.: Response of suspended sediment to natural and anthropogenic factors in the Guangdong-Hong Kong-Macao Greater Bay Area’s fish ponds over the Past 40 Years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7807, https://doi.org/10.5194/egusphere-egu24-7807, 2024.

EGU24-9548 | Orals | HS9.3

Mobilisation and transport dynamics of potential toxic elements during high flow events in a small river catchment 

Steffen Kittlaus, Radmila Milačič, Katarina Marković, Nikolaus Weber, Matthias Zessner, and Ottavia Zoboli

Export of potential toxic elements and other particle bound pollutants from catchments is highly dependent on the flow regime. The main driver is the higher mobilisation and transport capacity for suspended particulate matter (SPM) during high flow events.  But are there further dynamics in the concentrations which are not purely driven by the SPM transport?

To answer this question, we investigated the dynamics of the concentrations of potential toxic elements, several other elements and total suspended solids during high flow events by automated sampling and subsequent analysis of dissolved and total concentrations by ICP-MS after microwave assisted acid digestion. At 3 river monitoring sites 3 high flow events were sampled with 3-6 samples per event and site, covering different parts of the flow and turbidity peaks, which were recorded by online-measurements. To complement the river monitoring with data about potential sediment sources, landuse-stratified soil sampling in the catchment and river bed sediment sampling were conducted.

Our case study was the Wulka river in eastern Austria with a catchment area of 384 km2 and two if its tributaries, one with a very high share of treated waste water and the other with no permanent input of waste water. With a mean annual precipitation of 695 mm and a mean elevation of 256 m a.s.l. the river can be classified as a low land river. The landuse is dominated by agriculture including significant share of viniculture.

A first explorative principal component analysis showed, that several elements are strongly related with each other and the suspended sediment concentration. As this was expected, we used the SPM concentration to normalize the elemental concentrations and therefore taking out the variability caused by the suspended solids dynamics for further analysis. The remaining variability will be investigated regarding temporal and spatial patterns and correlation with the sediment and soil concentrations which can give indications about the emission pathways and sources.

To characterize the sampled high flow events, a hysteresis index was calculated from the discharge and turbidity signal which revealed different types of hysteresis, some clockwise hysteresis, several complex hysteresis patterns with different directions of the hysteresis during different times of the event and one small event with anticlockwise hysteresis. Different types of hysteresis can give indications about the distance of the sediment source to the observation location, further contributing to the exploration of SPM sources.

How to cite: Kittlaus, S., Milačič, R., Marković, K., Weber, N., Zessner, M., and Zoboli, O.: Mobilisation and transport dynamics of potential toxic elements during high flow events in a small river catchment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9548, https://doi.org/10.5194/egusphere-egu24-9548, 2024.

EGU24-10712 | Posters on site | HS9.3

Retro-observations of terrestrial and aquatic ecosystem degradation associated with agricultural intensification in South America using sedimentary archives 

Anthony Foucher, Amaury Bardelle, Jean Paolo Gomes Minella, Marcos Tassano, Guillermo Chalar, Mirel Cabrera, and Olivier Evrard

Since the mid-1980s, agriculture in South America has intensified and expanded significantly. For example, Brazilian census data show that cultivated land increased by 80% between 1996 and 2006, mainly in ecologically fragile areas (e.g., the Amazon, Cerrado, and Pampa). While agriculture plays a critical role in the socio-economic life of South America's agricultural regions, it also has negative environmental impacts, including land-use change, biodiversity loss, soil erosion and agrochemical contamination. To mitigate the negative effects of accelerated sediment transport, conservation practices such as no-tillage were adopted in the 2000s. Despite the advantage of not tilling the soil, the no-till system has a significant potential for soil and water degradation, both because of the high amount of inputs (pesticides and nutrients) added to the soil surface and because of the susceptibility to surface runoff formation and related processes.

Agricultural expansion and intensification are expected to continue in South America in the coming decades to meet growing food demand. However, the long-term (>40 years) responses of terrestrial and aquatic ecosystems to these anthropogenic pressures and conservation practices remain poorly documented due to a lack of multi-decadal monitoring stations or field measurements. Sedimentary archives collected in rivers and lakes draining South American regions affected by this agricultural expansion/intensification provide a unique opportunity to reconstruct the magnitude of these environmental impacts. In this study, we propose a synthesis of sedimentary archives published in Brazil, Uruguay, and Argentina, with a focus on the post-1950 period. These studies, which report on sediment dynamics and sediment characteristics (such as organic matter, phosphorus, accumulation rate), will be used to reconstruct the regional trajectory of terrestrial and aquatic ecological degradation related to these increasing human pressures. These trajectories will be compared with existing data on land use change, agricultural inputs, etc. to understand the response of the system to these perturbations and to better anticipate potential future degradation in line with expected trends in the coming years.

How to cite: Foucher, A., Bardelle, A., Minella, J. P. G., Tassano, M., Chalar, G., Cabrera, M., and Evrard, O.: Retro-observations of terrestrial and aquatic ecosystem degradation associated with agricultural intensification in South America using sedimentary archives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10712, https://doi.org/10.5194/egusphere-egu24-10712, 2024.

EGU24-11245 | ECS | Orals | HS9.3

Spatio-temporal evolution and source tracking of arsenic in surface waters of an old mining district (Orbiel Valley, France) 

Marie Heydon, Eléonore Resongles, Corinne Casiot-Marouani, Eva Schreck, Philippe Behra, Rémi Freydier, Mylène Marie, Carole Causserand, Sophie Delpoux, Martin Roddaz, Alain Pages, and Jérôme Viers

Past mining activities in the Orbiel Valley pose a significant risk of As contamination to its ecosystems and inhabitants. Approximately 12 million tons of tailings from last century's As and Au mining operations remain on site. Rehabilitation works have been implemented to store mining wastes and treat leaching waters. However recent studies have revealed that contamination is still present in water and sediments (Khaska et al., 2015; Delplace et al., 2022). The complexity of the area and previous findings have shown the importance of a more in-depth study of As sources and fate in the watershed, including 1/ characterizing As contamination levels in the Orbiel River and its tributaries during different hydrological periods, 2/ identifying the main sources of As and 3/ distinguishing the natural geochemical baseline from anthropogenic inputs.

Water samples (<0.22 µm) were collected in the Orbiel River and its tributaries from 2018 to 2022, representing a total of 170 samples, to analyze major element and metal(loid) concentrations, alkalinity, dissolved organic carbon, Sr isotope ratio, and As redox speciation in the dissolved fraction. Rock samples representative of the different geological formations were collected to compare the natural and anthropogenic evolution of the Sr isotope along the Orbiel Valley.

Upstream the mining district, in Orbiel River, the dissolved As concentration was about 2 µg/L and increased downstream near the main waste storage area to 7 – 71 µg/L (min-max, depending on the period) with a high proportion of As(III) (> 52 %). The anthropogenic origin of this contamination was confirmed by the 87Sr/86Sr ratio, which is less radiogenic than in the upstream pristine area, in relation with lime treatment implemented in the mine waste area. However, some valley limestones exhibit a Ca-arsenate-like isotopic ratio, highlighting the need to use complementary tracers to distinguish between anthropogenic and lithological sources. Finally, the mining-impacted tributaries are identified as significant contributors of As to the Orbiel River.

The present study will serve as a reference to interpret the origin, transport, and fate of metal(loid)s during future extreme flood events characteristic of this Mediterranean river.

 

Delplace, G., Viers, J., Schreck, E., Oliva, P., Behra, P., 2022. Pedo-geochemical background and sediment contamination of metal(loid)s in the old mining-district of Salsigne (Orbiel valley, France). Chemosphere 287 (2).

Khaska, M., Le Gal La Salle, C., Verdoux, P., Boutin, R., 2015. Tracking natural and anthropogenic origins of dissolved arsenic during surface and groundwater interaction in a post-closure mining context: isotopic constraints. J. Contaminant Hydrol. 177–178, 122–135.

How to cite: Heydon, M., Resongles, E., Casiot-Marouani, C., Schreck, E., Behra, P., Freydier, R., Marie, M., Causserand, C., Delpoux, S., Roddaz, M., Pages, A., and Viers, J.: Spatio-temporal evolution and source tracking of arsenic in surface waters of an old mining district (Orbiel Valley, France), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11245, https://doi.org/10.5194/egusphere-egu24-11245, 2024.

EGU24-11268 | Orals | HS9.3

Integrating lacustrine and coastal sediment records of environmental change in Northern Spain during the Anthropocene 

Mario Morellón, Juan Remondo, Víctor Villasante-Marcos, César Morales-Molino, Jon Gardoki, José Ezequiel Gómez-Arozamena, Jaime Bonachea, Victoria Rivas, Manel Leira, Francisco Javier Ezquerra, Pablo Cruz-Hernández, Pablo Valenzuela, María Luisa Canales, Mario Puente-Sierra, Sandra Yamile Hernández, Artur Stachnik, Carlos Sierra-Fernández, Willy Tinner, and Javier Martín-Chivelet

Reconstructing past environmental changes and identifying their main drivers is essential to predict the future response of natural systems to climate change under ever increasing anthropogenic pressure. To achieve this goal and understand the natural variability (prior to human disturbance) of the main processes involved, it is necessary to extend our temporal records back in time to pre-industrial conditions through the analysis of natural archives. 
The Cantabrian region (Northern Spain) constitutes an excellent natural laboratory to analyze and evaluate the magnitude of recent environmental change because of: i) its particular location, near to the boundary between Eurosiberian and Mediterranean biogeographic regions; ii) its strong elevation (from sea level to >2600 m asl) and climate (oceanic to continental mediterranean) gradients; and iii) the strong human impact to which this region has been subjected during the past few centuries. This research aims at understanding how recent (19th to 21st centuries CE) warming and increasing human land use have affected the geomorphological and geochemical dynamics of Northern Spanish watersheds, in the context of the environmental changes occurred during the last millennia. We use a multi-site approach, integrating high-resolution lake sediment records (Valle, Ausente, Isoba, Pozo Curavacas, Pozo Tremeo and Antuzanos) located along a West to East transect with a strong altitudinal gradient (17—1800 m asl), covering a wide range of climatic conditions and land management. To quantify the contributions of human and climate drivers to the recorded environmental changes, we use a multidisciplinary approach , involving geomorphological and paleolimnological proxies. We particularly focus on three main components of watershed dynamics: i) sediment delivery and depositional dynamics, ii) heavy metal loads, and iii) carbon fluxes. 
The multiproxy analysis of lake sediment cores (sedimentology, geochemistry, environmental magnetism, pollen and diatoms) dated by radiometric techniques (210Pb, 137Cs and 14C) reveals a dominant climate forcing at millennial to centennial timescales on depositional processes, in agreement with speleothem records. This signal has been modulated locally by changing anthropogenic landscape transformations driven by arable and pastoral farming as revealed by biological and geochemical proxies. In contrast, human-driven, abrupt increases in watershed erosion, heavy metal concentrations and nutrient loads occurred since the early to mid-20th century CE, coinciding with the Great Acceleration, in agreement with estuarine records along the Central and Eastern Cantabrian Sea coast analyzed by our research team and collaborators. According to available erosion models, this increase in sediment production has been influenced by a warmer and drier climate, with increasing flood frequency. This environmental change has been particularly intense at low-elevation sites subject to higher anthropogenic pressure, but it has been attenuated during the last two decades in high-elevation areas as a consequence of changing land use and environmental management. 
This research demonstrates the importance of combining different natural archives and methodologies to achieve a comprehensive understanding of the nature, timing, spatial variability, and consequences of the synergistic effects of human activities and climate change on watershed and regional scales. This is a contribution to CALACLIMP project (PID2021-122854OB-I00).

How to cite: Morellón, M., Remondo, J., Villasante-Marcos, V., Morales-Molino, C., Gardoki, J., Gómez-Arozamena, J. E., Bonachea, J., Rivas, V., Leira, M., Ezquerra, F. J., Cruz-Hernández, P., Valenzuela, P., Canales, M. L., Puente-Sierra, M., Hernández, S. Y., Stachnik, A., Sierra-Fernández, C., Tinner, W., and Martín-Chivelet, J.: Integrating lacustrine and coastal sediment records of environmental change in Northern Spain during the Anthropocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11268, https://doi.org/10.5194/egusphere-egu24-11268, 2024.

Historic metal mining and smelting have greatly enhanced the levels and fluxes of heavy metals in and through the fluvial system of the Geul river, a nearly 60 km long transboundary meandering stream in the northeast of Belgium and southeast of the Netherlands. In this study, we examined the long-term (> 1 year) effects of the extreme June 2021 flood on the transfer of sediments and heavy metals through the Geul river system. For this, we quantified the volumetric sediment budget of the channel belt of Dutch part of the Geul river using 0.5 m resolution Lidar-derived DEMs (Algemeen Hoogtebestand Nederland - AHN) for the 2018-2022 period and compared that to the similarly derived sediment budget for the 2012-2018 period. Furthermore, samples of fine sediment from the river bed and the top of the point bars were collected at more or less regular downstream intervals in 2022 and 2023, respectively. These sediment samples were analysed for total zinc and lead concentrations.

During the 2012-2018 period, the sediment of the channel belt was generally negative with an average net erosion rate of about 130 m3 km-1 y-1. This implies that during this period, river cut-bank erosion was not fully compensated by pointbar accretion and that the surface level of the newly formed point bars of the meandering Geul river was in general lower than the former floodplain surface. During the 2018-2022 period, the sediment budget was close to zero in the first 22 km of the Dutch reach downstream from the Belgian-Dutch border. However, in the downstream portion of the channel belt, the net deposition rate increased strongly with an average of about 380 m3 km-1 y-1. This positive sediment budget indicates strong aggradation of the point bars, which can most likely be attributed to backwater effects during the 2021 flood event, which upstream from a culvert underneath a canal close to the confluence of the Geul river into the Meuse river.

The zinc and lead concentrations in the fine fractions of the bed sediments shows a gradually decreasing trend in downstream direction which can be attributed to dilution from less contaminated sediment inputs from soil erosion on the upstream hillslopes and bank erosion. This pattern cannot be directly linked to the June 2021 flood event. In the reach where the sediment budget was close to zero during the 2018-2022 period, the zinc and lead concentrations in the point bar sediments are comparable to those in the fine bed sediments and show similar decreasing downstream trend. However, in the downstream reach, where net aggradation occurred during the 2018-2022 period, the metal concentrations in the point bar sediments deviate from the generally decreasing trend and increase again by a factor of about four. This downstream pattern in metal concentrations denotes that during the 2021 flood event, sediments originating from the contaminated upstream reaches of the Geul river skipped a substantial reach the Geul channel belt and were mainly deposited in the downstream portion of the channel belt.

How to cite: van der Perk, M. and Walcott, D.: Downstream transfer of metal-contaminated sediments in the Geul river as a result of the extreme June 2021 flood event, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12652, https://doi.org/10.5194/egusphere-egu24-12652, 2024.

EGU24-13348 | Orals | HS9.3

The varved sediment succession of Crawford Lake, Ontario, Canada: GSSP for the proposed Anthropocene Epoch  

R Timothy Patterson, Francine MG McCarthy, Martin J Head, Carling R Walsh, Nicholas L Riddick, Brian F Cumming, Paul B Hamilton, Michael FJ Pisaric, A Cale Gushulak, Peter R Leavitt, Krysten M Lafond, Brendan Llew-Williams, Autumn Heyde, Paul M Pilkington, Joshua Moraal, Nawaf A Nasser, Monica Garvie, Sarah Roberts, Neil L Rose, and Helen M Roe

The Crawford Lake sedimentary sequence in Milton, Ontario, Canada, has been chosen as the Global Boundary Stratotype Section and Point (GSSP) for the proposed Anthropocene Series/Epoch, with its inception occurring at 1952 CE in the mid-20th century. This sequence consists of seasonally deposited layers of organic matter capped by summer-deposited calcite, forming in alkaline surface waters when pH and temperature rise above 7.76 and ~15°C, respectively. These sediments preserve a range of proxies that mirror environmental shifts spanning from local, to regional, global scale, indicative of the Anthropocene's onset. Notably, a significant uptick in industrial fossil fuel combustion in the early 1950s is recorded by increased spheroidal carbonaceous particles and a shift in the sediment's nitrogen isotope composition. During the 1960s, the ratios of 239Pu:240Pu and 14C:12C peak, aligning with heightened radioactive fallout from atmospheric nuclear weapons testing, counterbalancing the old carbon effect in Crawford Lake's dolomitic basin. Post-World War II industrial growth in the Great Lakes region, part of the so-called Great Acceleration, led to acid rain that diminished calcite deposition and impacted primary productivity in the lake. This change is reflected in thinner calcite layers concurrent with the proposed GSSP. These varve thickness variations correlate with climate patterns and lake productivity trends, influenced by cycles like the Quasi-biennial Oscillation, El Nino-Southern Oscillation, the 11-year Schwabe sunspot cycle, and the Pacific Decadal Oscillation. The absence of pigments from anaerobic purple sulfur bacteria suggested an oxygen-rich monimolimnion but with elevated bottom-water salinities that was subsequently confirmed by water property data collected through the modern lake water column in all seasons.  Such an aerobic depositional environment is highly atypical for a meromictic lake and it was the elevated alkalinity and higher salinity conditions that resulted in preservation of varves. The oxygenated bottom waters serendipitously prevented the mobilization of 239Pu in the lake sediments, a key primary stratigraphic marker for the Anthropocene.

How to cite: Patterson, R. T., McCarthy, F. M., Head, M. J., Walsh, C. R., Riddick, N. L., Cumming, B. F., Hamilton, P. B., Pisaric, M. F., Gushulak, A. C., Leavitt, P. R., Lafond, K. M., Llew-Williams, B., Heyde, A., Pilkington, P. M., Moraal, J., Nasser, N. A., Garvie, M., Roberts, S., Rose, N. L., and Roe, H. M.: The varved sediment succession of Crawford Lake, Ontario, Canada: GSSP for the proposed Anthropocene Epoch , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13348, https://doi.org/10.5194/egusphere-egu24-13348, 2024.

EGU24-14030 | ECS | Posters virtual | HS9.3

Secondary Flow and Turbulent Kinetic Energy in a Dredged Channel with Riverbank 

Sukhjeet Arora, Harish Kumar Patel, Abhijit Dilip Lade, and Bimlesh Kumar

Sand dredging from the rivers has become an uncontrolled practice that harms the river's ecology. It affects the flow structure of the river, leading to further deterioration of the river's morphology. Several field investigations and experimental studies have conformed to the erosive effects of sand mining pits upstream and downstream of mining locations. We conducted laboratory-scale flume experiments to study the impact of a mining pit on the secondary flow structure across a riverbank cross-section. Three bank slopes were tested, namely, 25°,31°, and 40°, and gravity flow experiments were conducted with and without a mining pit. Turbulent velocity data across the cross-section was analyzed to study the transverse and velocity distribution across the riverbank for both with-pit and without-mining-pit cases. Results show that dredging an upstream mining pit significantly affects the transverse and vertical velocities, especially on the bank slopes and near the bed in the main channel portion. The turbulent kinetic energy in the flow region on the bank slope and near the bed in the main channel portion significantly increases because of the pit excavation. These alterations in the secondary flow within the riverbank can lead to morphological changes and may affect the bank stability of rivers.

Keywords: Sand Mining, Turbulent kinetic energy, turbulence

How to cite: Arora, S., Kumar Patel, H., Dilip Lade, A., and Kumar, B.: Secondary Flow and Turbulent Kinetic Energy in a Dredged Channel with Riverbank, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14030, https://doi.org/10.5194/egusphere-egu24-14030, 2024.

EGU24-15753 | Posters on site | HS9.3

Seasonal Retrieval of Suspended Sediment in the Pearl River Estuary Based on Measured Data 

Shirong Cai and Xiankun Yang

Suspended sediment is an important water quality parameter that plays an important role in regulating water and sediment dynamics in estuaries and shaping landform patterns. As one of China's important shipping channels, the sediment transport laws in the Pearl River Estuary (PRE) are very complex, which affects the water quality monitoring, pollutant transport, and offshore environmental and ecological protection of the PRE. This study takes the Pearl River Estuary as the study area, combines Landsat 8 images and measured data to construct suspended sediment inversion models in four seasons, and explores the seasonal patterns of suspended sediment concentration (SSC), to gain a deeper understanding of the transport mechanisms of suspended sediment in the PRE. The results show that: (1) From 2013 to 2021, there were significant seasonal differences in SSC. SSC was generally low during autumn and winter, and was higher during the dry season compared to the wet season. (2) At the interannual scale, SSC in the PRE exhibited a stable decrease. The suspended sediment is mainly concentrated at the estuary, and the spatial distribution pattern shows a distribution trend of higher on the west coast and lower on the east coast. (3) The suspended sediment in this region is influenced by various factors, such as upstream dam construction, seasonal rainfall changes, and land use changes. The findings of this study provide scientific insights for the sustainable development and ecological environment protection of the Pearl River Estuary, as well as suggestions for navigation safety and the security of infrastructure on both coasts.

How to cite: Cai, S. and Yang, X.: Seasonal Retrieval of Suspended Sediment in the Pearl River Estuary Based on Measured Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15753, https://doi.org/10.5194/egusphere-egu24-15753, 2024.

EGU24-17267 | ECS | Orals | HS9.3

Tracing the eutrophication history of Lake Baldegg using diatom-bound nitrogen isotopes 

Jules Millet, Nathalie Dubois, Moritz F. Lehmann, and Anja S. Studer

Diatom frustules are well-preserved in marine and lacustrine sediments over hundreds or even thousands of years. In addition, although only in very small amounts, they also contain organic matter within their siliceous structure. Previous applications have shown that the 15N/14N ratio of the organic nitrogen contained in diatom frustules (diatom-bound δ15N, or δ15NDB) can be used as a proxy for nutrient cycling in the polar oceans, and that it is not affected by diagenetic effects. However, the applicability of this paleo-proxy to lacustrine sediments has never been tested. Here, we explore the use of δ15NDB to reconstruct the history of nitrogen dynamics in Lake Baldegg (Switzerland) over the past 300 years. This lake was heavily eutrophied due to anthropogenic activities during the 20th century, before the implementation of lake restoration measures (i.e., artificial aeration of the lake bottom since 1982). Using a multi-proxy approach (e.g., reflectance-inferred chlorophyll a and organic carbon accumulation rates, XRF sulfur counts, bulk isotopic composition, C:N ratio), we identified two distinct eutrophication phases (1880-1950 and 1950-1980) that were characterised by an increase in organic matter accumulation and primary productivity, the occurrence of bottom water anoxia, and a change in the origin of the bulk organic matter. The implementation of re-oligotrophication measures has led to the disappearance of anoxic conditions at the bottom of the lake after 1995, and a decrease in phosphorus concentrations in the lake (the latter observed in the monitoring data), which seems to have mitigated primary productivity and organic matter accumulation. δ15NDB increased during the first phase of eutrophication, which could be due to extended denitrification in the water column in an expanding anoxic water column zone, and/or limiting N concentrations for phytoplankton growth, leading to increased nitrate utilization. During the second phase, δ15NDB decreased, probably because fixed N in surface waters was no longer limiting for phytoplankton. After the implementation of re-oligotrophication measures, δ15NDB increased again, possibly the isotopic imprint of external N inputs with a high δ15N signature, such as organic fertilizers (e.g. animal manure, compost). Additionally, the δ15N of hand-picked Daphnia ephippia are lower than, and show no consistent offset to, δ15NDB, suggesting that the N isotope signal of δ15NDB is not transferred to the upper trophic level in that lake. Finally, we measured the offset between δ15NDB and δ15NBULK providing insight into the effects of early diagenesis on the N isotopic composition of bulk sediments. In Lake Baldegg, the offset reversed after the lake was artificially oxygenated, indicating a role of sediment oxygenation in the diagenetic alteration on δ15NBULK.

How to cite: Millet, J., Dubois, N., Lehmann, M. F., and Studer, A. S.: Tracing the eutrophication history of Lake Baldegg using diatom-bound nitrogen isotopes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17267, https://doi.org/10.5194/egusphere-egu24-17267, 2024.

EGU24-17656 | ECS | Orals | HS9.3

Unravelling the mechanisms behind the spatial and temporal trends of suspended sediment in the Rhine basin  

Jana Cox, Tatjana Edler, Marcel van der Perk, and Hans Middelkoop

River deltas are reliant on upstream fluvial sediment delivery for their survival. The ultimate sediment delivery to deltas and the changing bed dynamics of river channels are strongly dependent on climate and anthropogenic changes within the entire river basin that control the increase (due to e.g. increased erosion, climate change) or decrease (due to e.g. sand mining, dam construction) of sediment supply. In the case of the Rhine-Meuse basin, suspended sediment delivery to the delta apex at Lobith has decreased since the 1950s. Therefore, we investigated changes in suspended sediment concentrations (SSC) and suspended sediment loads (SSL) over time along the main Rhine branch and its major tributaries (the Aare, Main, Mosel and Neckar) to determine the cause of the decline. We hypothesis and mathematically demonstrate that the spatial pattern in the temporal change can explain and determine specific mechanisms that are causing the decline.

Using collated SSC data of varying frequency from 1997-2014, we explored the suspended sediment transport within and along branches using the rating curve method & discharge-suspended sediment relations for a total of 26 measurements stations in the basin. These were compared with bed level data from Ylla-Arbós et al. (2021), to examine the interaction of SSC with bed dynamics.

A clear spatial trend emerged: the decrease in SSC strongly increases in an upstream direction. In the Alpine Rhine SSC has increased. There is negligible change in the upper basin/impounded section of the Rhine. However, SSC decreases emerge after the confluences with the Main and Mosel branches and this decrease becomes stronger moving towards the delta.

We find that contrary to many other river basins which are showing declining fluvial sediment delivery to deltas due to upstream dams or sediment management activities, in the Rhine-Meuse basin  the cause is actually the changing retention of channels and differing erosion rates from the river bed. Since the 19th century there have been activities to straighten and narrow the Rhine river to embank and fix the river course for navigation. This created high amounts of incision in the river bed in the early 20th century, but as proven by Ylla-Arbós et al. (2021) and others, this incision is now decreasing. These changes in suspended sediment supply from the river bed can be correlated to the changing supply at the delta apex. Since the 1980s efforts have been made to stabilize bed erosion and this ‘fixing’ of the river beds has led ultimately to a declining suspended sediment supply to the delta apex. This suggests that response to human interventions is not only relevant at a centurial timescale but is likely to be a defining feature of sediment supply for the coming century.  

 

References

Ylla Arbós, C., Blom, A., Viparelli, E., Reneerkens, M., Frings, R. M., & Schielen, R. M. J. (2021). River response to anthropogenic modification: Channel steepening and gravel front fading in an incising river. Geophysical Research Letters, 48(4), e2020GL091338.

How to cite: Cox, J., Edler, T., van der Perk, M., and Middelkoop, H.: Unravelling the mechanisms behind the spatial and temporal trends of suspended sediment in the Rhine basin , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17656, https://doi.org/10.5194/egusphere-egu24-17656, 2024.

EGU24-18246 | ECS | Posters on site | HS9.3

Suspended sediment and pollutant transport during heavy rain events: A case study of the Moselle river 

Liza-Marie Beckers, Magdalena Uber, Simon Terweh, Thomas Hoffmann, Arne Wick, and Gudrun Hillebrand

Extreme weather events pose major challenges for water managers and will likely increase in the future due to climate change. Heavy rain events potentially lead to short-term, but extraordinary changes in the composition of organic micropollutants (OMPs) e.g., via increased surface runoff and the input of untreated wastewater, as well as high inputs of suspended sediment into water bodies.

This study aims to unravel precipitation-related pollution patterns (including OMPs and suspended sediment) in the Moselle River and identify relevant sources and pathways relevant for rain-related emission. We used monitoring data of suspended sediment, which are derived using 15 min turbidity measurements or work-daily water sampling at seven stations starting in 1974. Furthermore, daily composite samples were collected by automatic samplers at two stations located along the German part of the Moselle River since April 2021. The chemical analyses included nontarget screening as well as target screening for selected fungicides.

From April 2021 to November 2021, 35 daily composite samples were selected for chemical analysis. Only one extreme rain event from July 12th- 14th, 2021 affected the water quality concerning suspended sediment concentrations and OMP mixture composition dramatically. During the event, 75 mm rainfall within 3 days lead to a flood with a return period of approximately five years. The estimated suspended sediment load of 141,000 tons during this event corresponds to approximately 13 times the long-term mean for the entire month of July and 23 % of the average annual load. A clockwise hysteresis pattern was observed, indicating instream remobilization of sediment and soil erosion in close proximity of the river. Concerning OMPs, three pollution patterns were identified. These patterns represented a) wastewater-related compounds diluted with increasing water level (e.g., pharmaceutical valsartan) as well as direct surface runoff from immediate surroundings of the river (e.g., fungicide fluopicolide), b) compounds introduced via increased groundwater discharge (e.g., pesticide metabolite metolachlor ESA) and c) compounds likely related to surface runoff in the catchment (e.g., herbicide terbuthylazine). While for the latter, the maximum intensity correlated with the maximum discharge and turbidity, the pattern related to groundwater input was characterized by a delay in maximum feature intensity relative to the maximum water level (i.e., kinematic wave effect).

Other, less extreme rain events that occurred since April 2021, did not show such pronounced OMP dynamics and such a strong hydro-sedimentary response in the Moselle river. This study supports our understanding of heavy rain induced OMP and suspended sediment emissions to a large river. With expected higher frequency and intensities of heavy rain events due to climate change, these emissions might gain in relevance in the future.

How to cite: Beckers, L.-M., Uber, M., Terweh, S., Hoffmann, T., Wick, A., and Hillebrand, G.: Suspended sediment and pollutant transport during heavy rain events: A case study of the Moselle river, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18246, https://doi.org/10.5194/egusphere-egu24-18246, 2024.

EGU24-19408 | ECS | Posters on site | HS9.3

A Lagrangian Stochastic Approach with Embedded Ornstein-Uhlenbeck Processes for Suspended Sediment Transport 

Yin-Yen Peng and Christina W. Tsai

This study aims to develop a Lagrangian stochastic (LS) model for simulating suspended sediment transport in open channels. The model incorporates three physical levels, namely, position, velocity, and acceleration, to describe sediment movement precisely. Without using any approximations, this approach is intrinsically stochastic and differentiable. It can reproduce different scale motions in turbulent flow for any Reynolds number. We will introduce the Lagrangian turbulent velocity theory into the random term of the sediment transport force balance equation. The random term, describing random particle movements, is usually represented by the Weiner process (i.e., Brownian motion), which is nowhere differentiable. Building upon prior research on stochastic turbulence models, we adopt an 'embedded' Ornstein-Uhlenbeck process to replace the Weiner process in this study. This embedded structure is defined through a set of coupled stochastic ordinary differential equations (ODEs), resulting in a multi-layered equation system. These different levels are interconnected through differentials and integrals. We introduce specific time scales and parameters tailored to different flow conditions to enhance their applicability to sediment transport scenarios. After we build these LS models, we have to validate with data or even calibrate the parameters in the model. We usually use two types of data: DNS data and experimental data. We will extract the details of isotropic turbulent flow in DNS data (such as the Kolmogorov time scale and Lagrangian velocity). The mean flow velocity profile will be determined from the experimental data. One-way coupling might be a reasonable assumption for the suspended sediment transport. However, when the gravitational force acts on the particles, the inter-particle interactions dominate the bed region due to the high particle concentration. A more appropriate resuspension mechanism must be identified so the particle concentrations can be more accurately quantified.

How to cite: Peng, Y.-Y. and Tsai, C. W.: A Lagrangian Stochastic Approach with Embedded Ornstein-Uhlenbeck Processes for Suspended Sediment Transport, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19408, https://doi.org/10.5194/egusphere-egu24-19408, 2024.

EGU24-20737 | Posters on site | HS9.3

Lake organic and inorganic carbon cycle decoupling in response to historical watershed activities in Yunnan, China 

Aubrey Hillman, Daniel Bain, and Mark Abbott

As anthropogenic impacts to both the climate system and freshwater resources continue unabated and are expected to intensify in coming decades, an increasing number of lakes will experience carbon cycle perturbations. Lakes that have been experiencing such perturbations for millennia can clarify the nature and severity of carbon cycle disturbances as well as recoveries. In lakes with authigenic carbonate material, the use of both inorganic and organic carbon isotopes to detect the decoupling of the inorganic and organic carbon cycles has been underutilized. We summarize here the application of these methods to three lakes in Yunnan, China, which have been impacted by human activities for the last 1,500 years.  Further we compare the results from this time period to the middle and late Holocene, both periods characterized by minimal anthropogenic influence. Decreased precipitation, increased evaporation, and changes in landscape vegetation drive changes observed in sediment carbon isotope compositions from 5,500 to 3,500 years BP. Stabilization of these factors from 3,500 to 1,500 years BP resulted in fairly consistent within-lake nutrient cycling. Following anthropogenic manipulation of lake levels after 1,500 years BP and despite differences in the magnitude of such activities, a pervasive feature in all of these lakes is the decoupling of the inorganic and organic carbon cycles, primarily driven by an influx of oxidized organic carbon from the watershed and/or the respiration of lake sediment organic matter. Carbon cycle decoupling persists into present-day for some lakes, illustrating the importance of considering historical, legacy activities.

How to cite: Hillman, A., Bain, D., and Abbott, M.: Lake organic and inorganic carbon cycle decoupling in response to historical watershed activities in Yunnan, China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20737, https://doi.org/10.5194/egusphere-egu24-20737, 2024.

EGU24-419 | ECS | Posters on site | HS2.1.12

Exploring the landscape heterogeneity and the hydrological diversity in three contrasted observatories of the French critical zone research infrastructure OZCAR 

Julien Ackerer, Sylvain Kuppel, Isabelle Braud, Sylvain Pasquet, Ophélie Fovet, Anne Probst, Marie Claire Pierret, Laurent Ruiz, Tiphaine Tallec, Nolwen Lesparre, Sylvain Weill, Christophe Flechard, Jean Luc Probst, Jean Marçais, Agnes Riviere, Florence Habets, Sandrine Anquetin, and Jerome Gaillardet

The French OZCAR critical zone network offers the opportunity to conduct multi-site studies and to explore the critical zone functioning under contrasted climate, geology, vegetation and land use. In this study, an integrated modeling of the water cycle is performed with the ecohydrological model EcH2O-iso in three long-term observatories: (1) the Naizin watershed characterized by an oceanic climate, a metamorphic bedrock and an intensive agriculture (north-west of France, AgrHyS observatory); (2) the Aurade watershed, a watershed with a warmer semi-continental oceanic climate, a sedimentary geological substratum and a crop cover with a wheat-sunflower rotation (south-west of France, Aurade observatory) and; (3) the Strengbach watershed characterized by a mountain climate, a granitic bedrock, and a beech-spruce forest cover (north-east of France, OHGE observatory).

Modeling robustness is evaluated by taking advantage of the large database for critical zone sciences including stream flow, water level in piezometers, and evapotranspiration fluxes measured from climatological stations and flux-towers located in the watersheds. Our comparative study brings these general outcomes: (1) the long term CZ evolution controlling the regolith thickness strongly impacts the total water storage in watersheds; (2) the Quaternary geomorphological evolution influences the current hydrological partitioning and the separation of hydrologically active and inactive water storage; (3) Both internal watershed characteristics and external forcings, such as current atmospheric forcing and recent land use need to be considered to infer stream persistence and to understand hydrological diversity; and (4) the observed hydrological diversity cannot be fully understood without considering a continuum of time scales in CZ evolution.

 

Overall, this work illustrates the strength of critical zone networks, allowing a new level of multi-site and comparative studies that are crossing several observatories and encompassing a wide diversity of geology and climate.

 

How to cite: Ackerer, J., Kuppel, S., Braud, I., Pasquet, S., Fovet, O., Probst, A., Pierret, M. C., Ruiz, L., Tallec, T., Lesparre, N., Weill, S., Flechard, C., Probst, J. L., Marçais, J., Riviere, A., Habets, F., Anquetin, S., and Gaillardet, J.: Exploring the landscape heterogeneity and the hydrological diversity in three contrasted observatories of the French critical zone research infrastructure OZCAR, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-419, https://doi.org/10.5194/egusphere-egu24-419, 2024.

EGU24-2143 | Posters on site | HS2.1.12

Time matters: photosynthetic vs. weathering-induced C drawdown and the role of dust inputs along a one-million-year soil weathering gradient on the Galápagos Islands 

Franz Zehetner, Martin H. Gerzabek, J. Gregory Shellnutt, Pei-Hao Chen, I Nyoman Candra, Kuo-Fang Huang, and Der-Chuen Lee

The Galápagos archipelago, a chain of islands formed by hotspot volcanism on the Nazca tectonic plate, exhibits a pronounced rock age gradient with distance from the volcanic hotspot from west to east. Here, we investigate chemical weathering along a soil chronosequence (1.5 to 1070 ka) under humid conditions. Our results show considerable loss of base cations already in the early to intermediate phases of weathering (e.g. 95% of Na and 78% of Mg lost from the topsoil after 26 ka) and almost complete loss from the entire profile in soils older than 800 ka. Depletion of Si was less pronounced, with topsoil losses of 24% and 63-68% after 26 ka and >800 ka, respectively. Total weathering flux and associated CO2 consumption rates estimated from profile-scale element losses in this study exceeded catchment-scale estimates reported for other volcanic islands or global averages during the early weathering phase, but were much lower in the intermediate and late phases. Nevertheless, total C drawdown was dominated by soil organic C sequestration (70-90% share) rather than inorganic, weathering-induced CO2 consumption during early pedogenesis (≤4.3 ka), and the relative importance switched in the intermediate and late phases (90-95% share of weathering-induced C drawdown at ≥166 ka). Dust deposition derived from a nearby ocean sediment core was <20% of total basalt mass loss at the young and intermediate-aged sites, but reached 40-60% at the older sites (>800 ka). Our results suggest that (1) young volcanic surfaces are very efficient (inorganic and organic) C sinks, (2) the development of thick soil covers at advanced pedogenic stages effectively shields the underlying rocks from further weathering, and (3) dust inputs become an increasingly important biogeochemical factor in such highly weathered environments.

How to cite: Zehetner, F., Gerzabek, M. H., Shellnutt, J. G., Chen, P.-H., Candra, I. N., Huang, K.-F., and Lee, D.-C.: Time matters: photosynthetic vs. weathering-induced C drawdown and the role of dust inputs along a one-million-year soil weathering gradient on the Galápagos Islands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2143, https://doi.org/10.5194/egusphere-egu24-2143, 2024.

EGU24-4999 | Posters on site | HS2.1.12 | Highlight

Lessons learned from 15 years of TERENO: the integrated TERrestrial ENvironmental Observatories in Germany 

Steffen Zacharias, Theresa Blume, Heye Bogena, Ralf Kiese, Erik Borg, Peter Dietrich, Susanne Liebner, Hans Peter Schmid, Martin Schrön, and Harry Vereecken

The need to develop and provide integrated observation systems to better understand and manage global and regional environmental change is one of the major challenges facing Earth system science today. In 2008, the German Helmholtz Association took up this challenge and launched the German research infrastructure TERrestrial ENvironmental Observatories (TERENO). The aim of TERENO is to establish and to maintain a network of observatories as a basis for an interdisciplinary and long-term research programme to investigate the effects of global environmental change on terrestrial ecosystems and their socio-economic consequences. State-of-the-art methods from the field of environmental monitoring, geophysics, and remote sensing are used to record and analyze states and fluxes in different environmental compartments from groundwater through the vadose zone, surface water, and biosphere, up to the lower atmosphere. To date, four observatories are part of the network, and over the past 15 years we have gained collective experience in running a long-term observing network, thereby overcoming unexpected operational and institutional challenges, exceeding expectations and facilitating new research. Today, the TERENO network is a key pillar for environmental modelling and prediction in Germany, an information hub for regional stakeholders, a nucleus for international collaboration, an important anchor for large-scale experiments, and a trigger for methodological innovation and technological progress. We will present the main lessons learned from this 15-year endeavour, and illustrate the need to continue long-term integrated environmental monitoring programmes in the future.

How to cite: Zacharias, S., Blume, T., Bogena, H., Kiese, R., Borg, E., Dietrich, P., Liebner, S., Schmid, H. P., Schrön, M., and Vereecken, H.: Lessons learned from 15 years of TERENO: the integrated TERrestrial ENvironmental Observatories in Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4999, https://doi.org/10.5194/egusphere-egu24-4999, 2024.

EGU24-7396 | Posters on site | HS2.1.12

Developing a coupled hydrological model for UK chalk catchments 

Mostaquimur Rahman, Ross Woods, Francesca Pianosi, Fai Fung, and Rafael Rosolem

Chalk forms one of the most important aquifers in the UK. Extending over large parts in the south-west, chalk aquifers account for more than half of the groundwater used for drinking in England and Wales. Groundwater held in these aquifers supports flows in chalk rivers. Hence, chalk aquifers play an important role in sustaining the riverine ecosystem. It is, therefore, important to assess and manage freshwater resources in these catchments. Here we develop and evaluate a distributed numerical model for simulating coupled subsurface and land surface hydrological processes including soil moisture variability, flow, and groundwater dynamics in chalk catchments. The parsimony and computational efficiency of this model make it possible to perform numerous simulations within a reasonable time. This allows for sensitivity analysis, calibration, and multiple scenario analysis that are useful in management decision making.

How to cite: Rahman, M., Woods, R., Pianosi, F., Fung, F., and Rosolem, R.: Developing a coupled hydrological model for UK chalk catchments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7396, https://doi.org/10.5194/egusphere-egu24-7396, 2024.

EGU24-9338 | ECS | Posters on site | HS2.1.12

The importance of in-situ soil moisture observations to evaluate the main drivers of event runoff characteristics in a small-scale catchment 

Adriane Hövel, Christine Stumpp, Heye Bogena, Andreas Lücke, and Michael Stockinger

A catchment’s runoff response to precipitation largely depends on the antecedent soil moisture in the catchment, but also on hydro-meteorological conditions in terms of, e.g., evapotranspiration. Studies investigating the effects of hydro-meteorological conditions on runoff event characteristics at the small catchment scale with daily temporal resolution mostly used surrogate measures for soil moisture, e.g., derived from hydrological models or using the antecedent precipitation index (API). Here, we applied a time-series based pattern search to 11 years of daily in-situ measured soil moisture in three depths (5, 20, 50 cm) at 33 locations in the Rollesbroich catchment (40 ha) in Germany to identify key variables influencing runoff event characteristics under similar wetness patterns. After identifying wetness patterns, we split the corresponding runoff responses into similar and dissimilar ones by means of goodness-of-fit criteria and analyzed their respective hydro-meteorological variables and event runoff coefficients (ERC), i.e., the proportion of rainfall that transforms into runoff during an event. Results showed that for similar soil moisture patterns, mean potential evapotranspiration, and antecedent soil moisture in all three depths had a smaller standard deviation for similar runoff responses than for dissimilar. This indicates a larger influence on the runoff response compared to rainfall-derived variables such as total event rainfall, maximum event rainfall intensity, or API. Furthermore, during runoff events under similar wetness conditions, the Spearman rank correlation coefficient (ρ) indicated a low average correlation between ERC and API (ρ=0.17). In terms of antecedent soil moisture conditions, the highest correlation between ERC and antecedent soil moisture was observed in the topsoil at 5 cm depth (ρ=0.43), while at 20 cm (ρ=0.16) and 50 cm (ρ=0.30) depths, the correlations were comparatively lower. Our study indicates that using the API as a substitute for antecedent wetness conditions may not be able to comprehensively reflect the relation between the runoff response and antecedent soil moisture conditions in the topsoil in the given catchment. Consequently, the results show that topsoil moisture measurements are more suitable than the surrogate API for assessing the impact of hydro-meteorological variables on daily runoff characteristics.

How to cite: Hövel, A., Stumpp, C., Bogena, H., Lücke, A., and Stockinger, M.: The importance of in-situ soil moisture observations to evaluate the main drivers of event runoff characteristics in a small-scale catchment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9338, https://doi.org/10.5194/egusphere-egu24-9338, 2024.

EGU24-9375 | ECS | Posters on site | HS2.1.12

Link between groundwater storage and landscape changes in mountainous areas: the Kahule Khola watershed (Nepal) 

Kapiolani Teagai, John Armitage, Léo Agélas, Christoff Andermann, and Niels Hovius

In many watersheds of various sizes, the role played by groundwater to sustain river flow is still misunderstood. This is the case in mountainous areas where geological features as fractures, altered or unaltered bedrocks and steep slopes notably play an important role for storing groundwater into the subsurface. The groundwater support to low flows was considered for a long time as a minor contribution, due to the steep slopes in those areas. But in Nepal, it is estimated that 2/3 of the volume of rivers comes from the exfiltration of groundwater through resurgences. Though several attempts were made with numerical modelling based on data monitoring and field surveys to quantify river-groundwater exchanged fluxes, some ambiguities remain. Especially regarding the impact of landscape change in a mountainous topography. The aim of this work is to characterize the subsurface infiltration, recharge, and storage mechanisms of a mountainous hydrogeological system in the Himalayas using field investigations and numerical modelling. In the Kahule Khola watershed (Nepal), a steep catchment of 33 km² whose altitudes range between 1000 and 3500 masl, various field experiments were made to identify groundwater pathways into the altered subsurface and to catch the river/groundwater interactions: seismic and electric surveys (ERT), infiltration tests, physical and isotopic measurements of springs/streams and the water tracking on the surface with loggers installed along gullies in the overall watershed. The region is submitted to intense rainfall as monsoon, intercalated by dry periods in which the river flow is still sustained. Moreover, by closing ancient fractures and opening new ones, earthquakes can deviate springs and change the surface water/groundwater pathways. This contributes to reshaping the landscape. However, the spatial and temporal contribution of groundwater to maintain a baseflow in the river is not quantified yet, in space and time. The ERT data from a time-lapse realized before and after monsoon show a deep alteration zone with a shallow humid layer of 10 m thick at least all year long under the slopes. Areas of low resistivity reveal infiltration zones and preferential flow paths. These areas are recharged in the wet season and drained in the dry season. At the surface, we estimate an average hydraulic conductivity at saturation of 3,5.10-5 m.s-1 in 150 cm depth which suggest an infiltration rate higher than the average rainfall rate (~3000 mm.year-1). In order to quantify the groundwater storage into the subsurface, a numerical groundwater model in 2D has been developed (Python) and is able to simulate and quantify the water storage dynamics of a spatial and temporal pre-defined domain. The data measured on the field will be used to define the initial conditions of future scenarios.

How to cite: Teagai, K., Armitage, J., Agélas, L., Andermann, C., and Hovius, N.: Link between groundwater storage and landscape changes in mountainous areas: the Kahule Khola watershed (Nepal), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9375, https://doi.org/10.5194/egusphere-egu24-9375, 2024.

EGU24-13095 | Posters on site | HS2.1.12

Hydrological, biogeochemical, and ecological linkages at the land-sea margin: Insights from a coastal critical zone network 

Holly Michael, Dannielle Pratt, Yu-Ping Chin, Sergio Fagherazzi, Keryn Gedan, Matthew Kirwan, Angelia Seyfferth, Lee Slater, Stephanie Stotts, and Katherine Tully

Ghost forests and abandoned farms are stark indicators of ecological change along world coastlines, caused by sea level rise (SLR). These changes adversely affect terrestrial ecosystems and economies, but expanding coastal marshes resulting from SLR also provide crucial ecosystem services such as carbon sequestration and mediate material fluxes to the ocean. A US-NSF Critical Zone Network project was designed to understand the hydrological, ecological, geomorphological, and biogeochemical processes that are altering the functioning of the marsh-upland transition in the coastal critical zone. We have instrumented six sites in the mid-Atlantic region of the US, along the coastlines of the Atlantic Ocean, Delaware Bay, and Chesapeake Bay where marshes are rapidly encroaching into forests and farmland. Field observations, laboratory experiments, and modeling are revealing the drivers and impacts of coastal change, as well as feedbacks among competing processes that accelerate or reduce rates and magnitude of change. We discuss examples of processes and feedbacks and highlight the importance of interdisciplinary exploration and synthesis in advancing process understanding at the land-sea transition.

How to cite: Michael, H., Pratt, D., Chin, Y.-P., Fagherazzi, S., Gedan, K., Kirwan, M., Seyfferth, A., Slater, L., Stotts, S., and Tully, K.: Hydrological, biogeochemical, and ecological linkages at the land-sea margin: Insights from a coastal critical zone network, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13095, https://doi.org/10.5194/egusphere-egu24-13095, 2024.

EGU24-13395 | Posters on site | HS2.1.12

Exploring Earth's Critical Zone Through the U.S. Critical Zone Collaborative Network 

Elizabeth W. Boyer, Bhavna Arora, Emma Aronson, Holly Barnard, Steven Holbrook, Jeffery S. Horsburgh, Lixin Jin, Praveen Kumar, Holly Michael, Jeff Munroe, Julia Perdrial, Claire Welty, and Jordan Read

The Critical Zone Collaborative Network (CZ Net) is a national research initiative in the United States supporting investigations of the Earth's critical zone (CZ) -- the vital near-surface environment extending from the top of the vegetation canopy to the weathered bedrock beneath. CZ Net fosters collaboration, data sharing, and interdisciplinary research to understand complex landscapes. The network comprises nine thematic clusters covering diverse geological, climatic, and land use settings. The thematic clusters explore many areas, including bedrock geology's effects on landscapes and ecosystems, ecosystem responses to climate and land-use disturbances, processes occurring between land and sea affected by sea-level rise, land-water interactions in agricultural regions, water and carbon cycles in arid regions, the impact of mineral dust transported in the atmosphere on ecosystems, water storage's influence on landscape and ecosystem processes, relationships between landscapes and microbial communities, and ecosystem processes in cities. A coordinating hub provides cross-cluster support. In the presentation, we introduce CZ Net and the focal research areas of each thematic cluster. We consider synthesis work addressing environmental challenges faced by the CZ, which is under increasing pressure to meet societal needs while safeguarding the environment for future generations. Further, we discuss opportunities for engagement with the network, reflecting CZ Net's dedication to advancing knowledge and addressing critical environmental issues through collaborative efforts. International coordination through developing a network of networks can foster collaborative research that transcends national boundaries, allowing scientists to combine expertise, data, and resources for a deeper understanding of CZ processes. Such collaboration is imperative for addressing pressing global environmental challenges.

How to cite: Boyer, E. W., Arora, B., Aronson, E., Barnard, H., Holbrook, S., Horsburgh, J. S., Jin, L., Kumar, P., Michael, H., Munroe, J., Perdrial, J., Welty, C., and Read, J.: Exploring Earth's Critical Zone Through the U.S. Critical Zone Collaborative Network, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13395, https://doi.org/10.5194/egusphere-egu24-13395, 2024.

EGU24-15452 | ECS | Posters on site | HS2.1.12

Exploring fluvial morphodynamics through scales  

Boris Gailleton, Philippe Steer, Philippe Davy, and Wolfgang Schwanghart

Surface processes control mass transfer efficiency on Earth, responding to tectonic and climatic forcings. These forcings impact landscape dynamics across a wide range of temporal scales, from individual events (e.g., storms) to geological time spans (e.g., Cenozoic climate cooling). Bridging these temporal scales poses a significant challenge for Landscape Evolution Models (LEMs). While LEMs are conventionally employed to study the effects of climate or tectonics on landscape dynamics over geological time, numerical methods simulating short-term processes such as landslides, floods, erosion, and sediment transport struggle to be projected beyond a few hundred years. 

In this contribution, we address this challenge by leveraging a recent model development—graphflood—that enables the computation of hydro-stationary water surfaces and discharge using a simplified shallow water approximation. This new model shows an order-of-magnitude improvement in speed over its predecessors, achieved through the efficiency of algorithms applied to directed acyclic graphs. Through testing induced subgraph dynamic traversals for initial calculations of a stationary state and employing GPU techniques to maintain the state to slower erosion and deposition processes, we demonstrate the potential for an additional order-of-magnitude reduction in computation time for fluvial dynamics. We also investigate how the computation of landslide runout using a shallow water approximation with a friction coefficient modified to account for velocity-weakening can be introduced within the same numerical framework. 

First, we explore various sets of fluvial erosion and deposition laws (e.g., stream power, Meyer Peter Muller) to determine the minimal representation needed for fluvial morphodynamics and projecting them across scales at the lowest computational cost. We then perturb the system with landslides processes and observe the controls on its resilience to external forcings. Lateral dynamics (e.g., lateral erosion, deposition, interaction with valley walls) and the model's ability to capture different river states (e.g., high flow vs low flow, flood) emerge as crucial elements in understanding the complexity of river responses to climato-tectonic perturbations. 

How to cite: Gailleton, B., Steer, P., Davy, P., and Schwanghart, W.: Exploring fluvial morphodynamics through scales , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15452, https://doi.org/10.5194/egusphere-egu24-15452, 2024.

EGU24-15453 | Posters on site | HS2.1.12

High Mountain Plateau Margin Critical Zone Observatory, Kaligandaki River Nepal 

Christoff Andermann, Kristen Cook, Basanta Raj Adhikari, Niels Hovius, and Rajaram Prajapati

Mountains are hotspots for earth surface processes, with very fast erosion rates, mass movements, catastrophic flooding and enhanced geochemical weathering rates. These landscapes respond quickly to external forcing by tectonics and/or climate. As a consequence, the hazard potential in mountains is very high, and mountains produce a wide range of large catastrophes which often have wide-reaching impacts on infrastructure and human lives. Furthermore, mountains can be considered as the water towers of the world, as they are very effective at harvesting water from the atmosphere, storing it, and redistributing it to the adjacent lowlands. The key role of mountain regions can be extended endlessly to other disciplines such as ecology, climatology, social sciences and so forth. Yet, despite their importance, high mountains remain inaccessible and notoriously understudied. High elevation terrains are only lightly covered by monitoring systems, with elevations >2500 m asl. widely underrepresented in global monitoring networks (Shahgedanova et al., 2021). The Himalayan mountains are particularly poorly covered by coordinated monitoring observatories.

In this contribution we present the set up and overview results of the ~last 10 years of integrated critical zone monitoring in the Kaligandaki Catchment in the central Himalayas in Nepal.

Motivated by fundamental research questions on coupled surface process and the high mountain water cycle in the Himalayan mountain range, we began observation in the Kaligandaki Catchment with two major stations for climatological and hydrological monitoring that have operated continuously over the past 10 years. At each location trained personal conducted manual river water sampling for river water geochemistry and suspended sediment monitoring as well as water discharge and bulk meteorological parameters. These observations were complemented by targeted short-term deployments and field sampling campaigns to cover the full spatial extent as well as the seasonal variability. Research question range from organic carbon export, climate and erosion feedback as well as water pathways in high mountains to large mass-movements and intramountain sediment storage and feedbacks with landscape evolution.

Our findings from the past 10 years of monitoring motivate the development of a more substantial observatory in the Kaligandaki catchment, which is particularly suited as a critical zone observatory in the Himalayas. The Kaligandaki is a trans-Himalayan river that connects the Tibetan Plateau through the Himalaya to the low elevation foreland. The river crosses distinct climatological, ecological, tectonic, and geomorphic zones, including the arid high elevation plateau, the rapidly uplifting high Himalaya and monsoon precipitation maxima, and the middle hills. The river corridor is highly prone to flood and landslide hazards, and is experience increasing development and human impact, particularly road construction and hydropower. In addition, the river basin is highly sensitive to changing precipitation patterns, which have brought anomalous rainfall and flooding in recent years, and to changing melting patterns, which affect water resources. Together with local partners and the international research community we are proposing this unique catchment as potential integrated mountain critical zone observatory in order to close the monitoring gap in the highest mountain range on Earth.

Literature:

Shahgedanova, M., et al. 2021, https://doi.org/10.1659/MRD-JOURNAL-D-20-00054.1

How to cite: Andermann, C., Cook, K., Adhikari, B. R., Hovius, N., and Prajapati, R.: High Mountain Plateau Margin Critical Zone Observatory, Kaligandaki River Nepal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15453, https://doi.org/10.5194/egusphere-egu24-15453, 2024.

EGU24-15523 | Posters on site | HS2.1.12

The impact of groundwater dynamics on landsliding and hillslope morphology: insights from typhoon Morakot and landscape evolution modelling 

Philippe Steer, Lucas Pelascini, Laurent Longuevergne, and Min-Hui Lo

Landslides represent a pervasive natural hazard, exerting a significant influence on hillslope morphology in steep regions. Intense rainfall events are well-established as primary triggers for landslides, particularly those characterized by high rainfall intensity, intermediate to long durations, and substantial cumulative precipitation during and before the event. While the evolving roles of soil saturation and mechanical properties are well-identified in shallow landslide occurrences, the influence of groundwater dynamics on the triggering of deep-seated or bedrock landslides remains less understood. Despite this knowledge gap, deep-seated landslides play a dominant role in the volume budget of landslide catalogs and serve as the primary geomorphological process shaping hillslope evolution in steep regions. In this study, we explore the impact of groundwater dynamics on landslide triggering. Our investigation focuses initially on landslides triggered during Typhoon Morakot, examining their relationship with water table fluctuations derived from the HydroModPy 3D hydrogeological model, forced by water recharge data obtained from the Community Land Model CLM 4.0. Analyzing several contrasting catchments, we demonstrate a strong correlation between the locations and depth of deep-seated landslides and the instability predicted by a simple landslide model that integrates pore pressure and water table depth. Notably, these predictions are valid within specific ranges of hydrogeological (i.e., aquifer thickness, porosity, and conductivity) and mechanical (i.e., cohesion and friction angle) parameters, providing valuable insights into the hydrogeological and mechanical properties of the studied catchments. In an exploratory study, we then shift our focus to the longer-term geomorphological impact of rainfall-triggered landslides on hillslope evolution and morphology. Using a coupled 2D model of water table evolution and landsliding, we investigate topographic changes at the hillslope scale, under different scenarios. Our investigation considers the influence of seasonal recharge, intense rainfall events, and hillslope hydrological convergence or divergence perpendicular to the hillslope orientation on resulting hillslope morphology and dynamics. Overall, our results particularly highlight the role of groundwater dynamics on hillslope finite shape.

How to cite: Steer, P., Pelascini, L., Longuevergne, L., and Lo, M.-H.: The impact of groundwater dynamics on landsliding and hillslope morphology: insights from typhoon Morakot and landscape evolution modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15523, https://doi.org/10.5194/egusphere-egu24-15523, 2024.

EGU24-17282 | ECS | Posters on site | HS2.1.12

Assessing the impact of stress–dependent hydraulic properties on hillslope-scale groundwater flow and transport 

Ronny Figueroa, Clément Roques, Ronan Abherve, Landon Halloran, and Benoit Valley

The occurrence of springs and their connectivity within stream networks is typically associated with three key controlling factors: climate, topography and the distribution of hydraulic properties. In crystalline media, this distribution is often related to lithology and the presence of fractures. In addition, tectonic and topographic stresses can modify properties through compressive and extensional forces acting on the rock mass and fractures. However, these controls are rarely considered for hillslope scale applications. The aim of this research is to investigate the effects of stress on bedrock hydraulic properties and their implications for groundwater flow and transport at the hillslope scale. A numerical experiment has been designed that combines linear poroelasticity to simulate the distribution of permeability and porosity, together with groundwater flow and transport simulations. Different slope and stress conditions are examined, providing a comprehensive sensitivity analysis framework.

Our results show that vertical stress leads to a decrease in permeability and porosity at depth, following an exponential-like trend. Increasing the proportion of lateral stresses relative to the total vertical stresses reduces the mean permeability and porosity and increases the variance in the distribution along the hillslope. For high values of lateral stress, a low permeability domain develops downslope at the valley bottom due to the accumulation of compressive stresses, while the extensive regime at the crest provides higher permeabilities. As expected, groundwater flow simulations revealed that the partitioning of flow paths is strongly influenced by such heterogeneous stress-induced permeability and porosity fields. As stress increases, groundwater flow becomes more channelized in the near subsurface, strongly deviating from the classical Dupuit model. We also found that the distribution of normalized groundwater discharge rates shows higher values in the upper part of the seepage zone than in the lower part. By analyzing the results of particle tracking simulations, we found that mean residence times increase with higher external stress due to a decrease in mean permeability. In addition, the shape of the residence time distribution is strongly modified by the channeling of groundwater flow with increasing lateral stress, with the probability of shorter residence times increasing as stress increases. We discuss the implications of these fundamental results for our understanding of the role of stress in groundwater-dependent systems, with important insights into the recharge, storage and discharge mechanisms that may control the resilience of landscapes to the effects of climate change.

How to cite: Figueroa, R., Roques, C., Abherve, R., Halloran, L., and Valley, B.: Assessing the impact of stress–dependent hydraulic properties on hillslope-scale groundwater flow and transport, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17282, https://doi.org/10.5194/egusphere-egu24-17282, 2024.

EGU24-17490 | Posters on site | HS2.1.12 | Highlight

Hydroclimatic versus geochemical controls on silicate weathering rates 

Sylvain Kuppel, Yves Goddéris, Jean Riotte, and Laurent Ruiz

Water is the first order controlling factor of the weathering reactions. In the recent years, efforts have been made towards the building of model cascades able to simulate the water fluxes and the residence time of the water in the various compartments of the critical zone. Those hydrological constrains are then injected into numerical models simulating the water-rock interactions from the surface down to the impervious bedrock. In this contribution, we describe such a model cascade, where the water-rock interaction model WITCH is fed by the process-based ecohydrological model EcH2O-iso. This model cascade, WITCH2O, is designed for the modeling of water fluxes & stores, as well as the weathering reactions and transport of weathering products (including atmospheric CO2 consumption), from the vertical profile to the catchment scale, and from the submonthly to decadal time scales. We deployed WITCH2O along a gneiss-saprolite-ferralsol profile in a small tropical forested catchment in peninsular India. Long-term observations of water and geochemical fluxes are available, allowing for a 2-step model calibration and evaluation (hydrological and geochemical) across the different processes simulated. Using various temporal averages of simulated water fluxes and stores, preliminary results highlight that seasonal hydrological variability (driven by monsoon dynamics and deep root water uptake) is key for capturing groundwater nutrient concentrations, despite highly-buffered water table variations. We also explore how this non-linear dependence of weathering fluxes upon hydrological states is modulated by the propagation of uncertainties regarding i) modeled hydrology and ii) uncertainties in geohydrochemical properties (e.g. reactive surface and mineral abundance).

How to cite: Kuppel, S., Goddéris, Y., Riotte, J., and Ruiz, L.: Hydroclimatic versus geochemical controls on silicate weathering rates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17490, https://doi.org/10.5194/egusphere-egu24-17490, 2024.

EGU24-20178 | Posters on site | HS2.1.12

Coevolution in the critical zone: the key role of fast hydrologic processes 

Patricia Saco, Juan Quijano Baron, Jose Rodriguez, Mariano Moreno de las Heras, and Samira Azadi

Feedback effects between hydrology, vegetation and erosion processes are pervasive across landscapes. These tight interactions lead to the coevolution of landscape patterns that modulate landform shape and regulate many other critical zone processes. We study these feedbacks and interactions using simulations from landform evolution models that account for the effect (and feedbacks) of spatially and temporally varying hydrologic pathways and vegetation over landscapes displaying a variety of vegetation patterns. 

We first present results from a landscape evolution modelling framework, that accounts for a comprehensive representation of hydrology and vegetation, including the effect of various vegetation pools on erosion processes. The model includes interacting modules for hydrology, dynamic vegetation, biomass pools partition, and landform evolution. Our simulations indicate that each of the biomass pools provides a specific erosion protection mechanism at a different time of the year. As rainfall events and the resulting vegetation growth and protection are asynchronous, the maximum values of erosion are associated with runoff at the beginning of the rainy season when vegetation protection is not as its maximum. These results show how rapid hydrological processes affecting vegetation have long term implications for landform development. Results for a Eucalyptus savanna landscape study site in the Northern Territory (Australia) showed that models that do not account for the vegetation dynamics can result in prediction errors of up to 80%.  

We also present simulations of the coevolution of landforms and vegetation patterns in selected sites with patchy Acacia Aneura (Mulga) vegetation.  These sites display a sparse vegetation cover and strong patterns of surface water redistribution, with runoff sources located in the bare areas and sinks in the vegetation patches. This effect triggers high spatial variability of erosion/deposition rates that affects the evolving topography and induces feedbacks that shape the dynamic vegetation patterns. We run simulations using rainfall, vegetation and erosion data, and vegetation parameters previously calibrated for Mulga sites in the Northern territory. We further investigate the effect of alterations in hydrologic connectivity induced by climate change and/or anthropogenic activities, which affect water and sediment redistribution and can be linked to loss of resources leading to degradation. We find that an increase in hydrologic connectivity can trigger changes in vegetation patterns inducing feedbacks with landforms leading to degraded states. These transitions display non-linear behaviour and, in some cases, can lead to thresholds with an abrupt reduction in productivity. Critical implications for management and restoration are discussed.  

How to cite: Saco, P., Quijano Baron, J., Rodriguez, J., Moreno de las Heras, M., and Azadi, S.: Coevolution in the critical zone: the key role of fast hydrologic processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20178, https://doi.org/10.5194/egusphere-egu24-20178, 2024.

EGU24-219 | ECS | Posters on site | BG3.13

Rhizodeposition in the Plant Economic Space for 15 grassland species and its links to biogeochemical cycles (C,N) 

Chloé Folacher, Estelle Forey, Angèle Branger, Matthieu Chauvat, and Ludovic Henneron

Understanding how photosynthetic carbon is delivered into the soil system through rhizodeposition is of utmost importance in a changing world, as it represents an essential part of carbon cycling in soils. The plant economic space (PES) is a theoretical model representing plant strategies resource acquisition strategies based on two independent trade-offs: (i) resource acquisition vs conservation and (ii) exploration outsourcing (cooperation with mycorrhizal fungi) vs do-it-yourself. The PES is known to be related to a set of chemical and morphological traits, but some physiological traits such as rhizodeposition lack attention because they are harder to measure, while they are crucial for our understanding of resource allocation strategies and their linkages to ecosystem processes. For example, gross rhizodeposition can represent more than 40% of belowground carbon allocation.

We aimed to provide more insights on the relationship between rhizodeposition and the two dimensions of the PES, with a focus on the second axis, as arbuscular mycorrhizal fungi (AMF) are supposed to play an essential role of sink in the sink/source model of rhizodeposition. To do so, we grew 15 grassland plant species with contrasting resource acquisition strategies in a 3-month long pot experiment, with or without litter inputs. By means of 13C pulse-labelling, we traced carbon fluxes from recent photosynthates in major pools, including above-and belowground parts of the plant, but also in microbial biomass and microbial functional groups using PLFAs, soil organic matter, and soil respiration. We also measured net and gross nitrogen mineralisation.

We hypothesise that (i) rhizodeposition will be strongly link to the fast-slow gradient, fast-growing species being associated with higher rhizodeposition rates, but (ii) rhizodeposition will also show significant relationships with the exploration gradient, as tighter plant-soil biota association – including more AMF colonisation – could promote higher rhizodeposition rate, because of sink mechanisms. Higher rhizodeposition should also be associated (iii) with a shift in microbial community toward functional groups more dependant to plant carbon such as AMF and Gram negative bacteria, as well as (iv) higher soil respiration and nitrogen mineralisation.

How to cite: Folacher, C., Forey, E., Branger, A., Chauvat, M., and Henneron, L.: Rhizodeposition in the Plant Economic Space for 15 grassland species and its links to biogeochemical cycles (C,N), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-219, https://doi.org/10.5194/egusphere-egu24-219, 2024.

EGU24-743 | ECS | Posters on site | BG3.13

Assessing Fine Root Production in Terrestrial Forests: A Comparative Analysis of AI and Human Annotation Using Minirhizotron Images 

Imogen Carter, Grace Handy, Marie Arnaud, Rob Mackenzie, Gael Denny, Abraham Smith, and Adriane Esquivel-Muelbert

Fine roots are a major source of the stabilised carbon in soils. However, the response of fine root production to an increase in atmospheric CO2 and its impact on carbon dynamics in terrestrial forests remain poorly understood. Minirhizotrons can help to quantify fine root production and associated carbon dynamics in long-term, in-situ experiments such as Free Air CO2 Enrichment experiments. Yet, using minirhizotrons requires the manual annotation of thousands of images. Artificial Intelligence (AI) technology for image processing is fast developing and has proven to be successful in simple systems, such as agronomous crops. Here, we quantified how AI (RootPainter) annotation compares with humans, and determined the implications in terms of root production and carbon dynamics in a mature deciduous forest (BIFOR-FACE). Firstly, we quantified the variation in outputs of 30 annotated minirhizotron images using AI and human analysts of varying levels of expertise, comparing them to a gold standard established through expert consensus. We find that root annotation varied substantially among humans, with novices and AI over-annotating root length by 244% and 206% respectively, compared to our gold standard. Secondly, we quantified root length for five minirhizotron tubes in March and June (n = 1060 images) using AI and then a trained human analyst. AI over-estimated root length by more than an order of magnitude compared to a trained human user, and there was a poor linear relationship between annotated images with  AI and humans (r² < 0.22 for both months). This over-annotation by AI resulted in inaccurate quantification of root production and mortality, and thus erroneous carbon budget.

How to cite: Carter, I., Handy, G., Arnaud, M., Mackenzie, R., Denny, G., Smith, A., and Esquivel-Muelbert, A.: Assessing Fine Root Production in Terrestrial Forests: A Comparative Analysis of AI and Human Annotation Using Minirhizotron Images, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-743, https://doi.org/10.5194/egusphere-egu24-743, 2024.

The enhancement of biodiversity's positive impact on ecosystem functioning (BEF) over time is commonly observed and attributed to the accumulation of mutualists and dilution of antagonists in more diverse communities. If antagonists play a role in the BEF relationship, the reduction of plant antagonists in more diverse communities, could allow plants to reduce allocation to defence. This study aimed to assess the influence of plant diversity on the expression of defence traits in 16 plant species. Our hypotheses were: (1) increased plant diversity reduces allocation to defence, (2) this reduction is more pronounced in roots than in leaves, and (3) this effect varies among species.

We measured both physical and chemical defence traits in leaves and fine roots across communities with varying plant species richness in a 19-year-old biodiversity experiment. Using established methods and an innovative metabolome approach, we explored the interactive effects of plant diversity and species identity on defence traits through linear mixed models.

Our findings were mixed concerning the first hypothesis, with only some leaf defence traits (leaf mass per area, leaf dry matter content, and hair length) showing reduction along the diversity gradient. Unexpectedly, the values of some root traits, root tissue density and nitrogen content, suggested increased allocation to defence along the same gradient. This might be attributed to these traits serving other functions, e.g. in resource acquisition and competition, which potentially overruled the impact of declining antagonists on plant defences. Our results did not support the third hypothesis, suggesting an overall convergence responses to biotic and abiotic factors related to plant diversity after two decades.

While evidence for a consistent reduction in defence trait expression along the diversity gradient was limited, our findings underscore the complex nature of BEF relationships. Further experiments, possibly controlling confounding factors on trait expression or manipulating antagonist pressures along diversity gradients, are needed to elucidate the underlying mechanisms.

How to cite: Bassi, L.: Intra- and inter-specific changes in leaf and root defence traits along an experimental plant diversity gradient., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3368, https://doi.org/10.5194/egusphere-egu24-3368, 2024.

EGU24-3397 | ECS | Orals |