Articles de revistahttp://hdl.handle.net/2117/797872024-03-29T15:47:03Z2024-03-29T15:47:03ZFSLAM: A QGIS plugin for fast regional susceptibility assessment of rainfall-induced landslidesGuo, ZizhengTorra i Truncal, OnaHurlimann Ziegler, MarcelAbanco Martínez de Arenzana, ClaudiaMedina Iglesias, Vicente César dehttp://hdl.handle.net/2117/3676042024-02-12T01:28:21Z2022-05-23T09:47:27ZFSLAM: A QGIS plugin for fast regional susceptibility assessment of rainfall-induced landslides
Guo, Zizheng; Torra i Truncal, Ona; Hurlimann Ziegler, Marcel; Abanco Martínez de Arenzana, Claudia; Medina Iglesias, Vicente César de
Shallow slope failures triggered by rainfall commonly pose considerable risks in mountainous areas. In order to delineate areas where landslides are more prone to occur within a region, we have designed and developed a Python QGIS plugin named Fast Shallow Landslide Assessment Model (FSLAM). The plugin integrates a simplified hydrological model and a geotechnical model based on the infinite slope theory and contains two principal modules: runoff and slope stability modelling. It can output up to 15 raster maps describing the hydrological and stability conditions in a short computational time. Firstly, we explain the design of graphical user interface and the elements of the plugin. Then, the Berguedà area in NE Spain is used as case study to present the procedure of the plugin application. The results show that the accuracy of landslide susceptibility assessment performed by FSLAM-plugin is high and the computing time is only a few minutes.
2022-05-23T09:47:27ZGuo, ZizhengTorra i Truncal, OnaHurlimann Ziegler, MarcelAbanco Martínez de Arenzana, ClaudiaMedina Iglesias, Vicente César deShallow slope failures triggered by rainfall commonly pose considerable risks in mountainous areas. In order to delineate areas where landslides are more prone to occur within a region, we have designed and developed a Python QGIS plugin named Fast Shallow Landslide Assessment Model (FSLAM). The plugin integrates a simplified hydrological model and a geotechnical model based on the infinite slope theory and contains two principal modules: runoff and slope stability modelling. It can output up to 15 raster maps describing the hydrological and stability conditions in a short computational time. Firstly, we explain the design of graphical user interface and the elements of the plugin. Then, the Berguedà area in NE Spain is used as case study to present the procedure of the plugin application. The results show that the accuracy of landslide susceptibility assessment performed by FSLAM-plugin is high and the computing time is only a few minutes.Rockfalls: analysis of the block fragmentation through field experimentsGili Ripoll, José AntonioRuiz Carulla, RogerMatas Casado, GerardMoya Sánchez, JoséPrades Valls, AlbertCorominas Dulcet, JordiLantada, NievesNúñez Andrés, María AmparoBuill Pozuelo, FelipePuig i Polo, CàrolMartínez Bofill, JoanSalo Salgado, LluisMavrouli, Olga Christinahttp://hdl.handle.net/2117/3674072022-10-09T04:15:57Z2022-05-16T19:45:37ZRockfalls: analysis of the block fragmentation through field experiments
Gili Ripoll, José Antonio; Ruiz Carulla, Roger; Matas Casado, Gerard; Moya Sánchez, José; Prades Valls, Albert; Corominas Dulcet, Jordi; Lantada, Nieves; Núñez Andrés, María Amparo; Buill Pozuelo, Felipe; Puig i Polo, Càrol; Martínez Bofill, Joan; Salo Salgado, Lluis; Mavrouli, Olga Christina
Fragmentation is a common feature of rockfall that exerts a strong control on the trajectories of the generated blocks, the impact energies, and the runout. In this paper, we present a set of four real-scale rockfall tests aimed at studying the fragmentation of the rocky blocks, from the global design of the field procedure to the data analysis and the main results. A total of 124 limestone, dacite, or granite blocks ranging between 0.2 and 5 m3 were dropped from different heights (8.5 to 23.6 m) onto four slopes with different shapes (single or double bench) and slope angles (42º to 71º). The characteristics of the blocks, in particular the size, surface texture and joint condition, were measured before the drops. The trajectories of the blocks and both the initial and the impact velocities were tracked and recorded by means of three high-speed video cameras. A total of 200 block-to-ground impacts have been studied. On average, 40% of the blocks broke upon impact on the slope or on the ground, making it necessary to measure the fragments. The initial and final sizes of the blocks/fragments were measured by hand with tape, though photogrammetric techniques (UAV and terrestrial) were also used for comparison purposes. The information gathered during the field tests provides a deep insight into the fragmentation processes. On the one hand, the high-resolution slow-motion videos help to describe when and how the block breakage takes place and the spatial distribution of the pieces. On the other hand, it is possible to compute the block trajectories, the velocities, and the energy losses using videogrammetry. The results include, for instance, a block average fragmentation of 54% and 14% for the limestone and granitoids, respectively; the systematic inventory of the size fragments, which may be used for fitting the power law distributions; and after each breakage, the total angle of aperture occupied by the fragments has been measured, with values in the range 25º–145º. To figure out the different behavior of the blocks in terms of breakage/no breakage, each block-to-ground impact has been characterized with a set of parameters describing the energy level, the robustness of the substrate, and the configuration of the block contact at the impact point, among others. All these terms are combined in a function F, which is used to adjust the field data. The adjustment has been carried out, first, for the whole 200 events and later for a subset of them. The procedure and the results are described in the paper. Although the discrimination capability of F is moderately satisfactory, it is very sensitive to the test site and setup. It must be highlighted that these field tests are a unique source of data to adjust the parameters of the numerical simulation models in use for rockfall studies and risk mitigation, especially when fragmentation during the propagation is considered.
2022-05-16T19:45:37ZGili Ripoll, José AntonioRuiz Carulla, RogerMatas Casado, GerardMoya Sánchez, JoséPrades Valls, AlbertCorominas Dulcet, JordiLantada, NievesNúñez Andrés, María AmparoBuill Pozuelo, FelipePuig i Polo, CàrolMartínez Bofill, JoanSalo Salgado, LluisMavrouli, Olga ChristinaFragmentation is a common feature of rockfall that exerts a strong control on the trajectories of the generated blocks, the impact energies, and the runout. In this paper, we present a set of four real-scale rockfall tests aimed at studying the fragmentation of the rocky blocks, from the global design of the field procedure to the data analysis and the main results. A total of 124 limestone, dacite, or granite blocks ranging between 0.2 and 5 m3 were dropped from different heights (8.5 to 23.6 m) onto four slopes with different shapes (single or double bench) and slope angles (42º to 71º). The characteristics of the blocks, in particular the size, surface texture and joint condition, were measured before the drops. The trajectories of the blocks and both the initial and the impact velocities were tracked and recorded by means of three high-speed video cameras. A total of 200 block-to-ground impacts have been studied. On average, 40% of the blocks broke upon impact on the slope or on the ground, making it necessary to measure the fragments. The initial and final sizes of the blocks/fragments were measured by hand with tape, though photogrammetric techniques (UAV and terrestrial) were also used for comparison purposes. The information gathered during the field tests provides a deep insight into the fragmentation processes. On the one hand, the high-resolution slow-motion videos help to describe when and how the block breakage takes place and the spatial distribution of the pieces. On the other hand, it is possible to compute the block trajectories, the velocities, and the energy losses using videogrammetry. The results include, for instance, a block average fragmentation of 54% and 14% for the limestone and granitoids, respectively; the systematic inventory of the size fragments, which may be used for fitting the power law distributions; and after each breakage, the total angle of aperture occupied by the fragments has been measured, with values in the range 25º–145º. To figure out the different behavior of the blocks in terms of breakage/no breakage, each block-to-ground impact has been characterized with a set of parameters describing the energy level, the robustness of the substrate, and the configuration of the block contact at the impact point, among others. All these terms are combined in a function F, which is used to adjust the field data. The adjustment has been carried out, first, for the whole 200 events and later for a subset of them. The procedure and the results are described in the paper. Although the discrimination capability of F is moderately satisfactory, it is very sensitive to the test site and setup. It must be highlighted that these field tests are a unique source of data to adjust the parameters of the numerical simulation models in use for rockfall studies and risk mitigation, especially when fragmentation during the propagation is considered.Capturing rockfall kinematic and fragmentation parameters using high-speed camera systemPrades Valls, AlbertCorominas Dulcet, JordiLantada, NievesMatas Casado, GerardNúñez Andrés, María Amparohttp://hdl.handle.net/2117/3672512023-03-13T10:59:11Z2022-05-11T12:05:38ZCapturing rockfall kinematic and fragmentation parameters using high-speed camera system
Prades Valls, Albert; Corominas Dulcet, Jordi; Lantada, Nieves; Matas Casado, Gerard; Núñez Andrés, María Amparo
This paper presents a procedure for tracking rockfall trajectories and extracting kinematic parameters from both the impacts and the resultant fragments. A set of full scale rockfall experiments was performed in a quarry located in Vallirana, Barcelona (Spain). The study site was chosen due to the presence of a rigid discontinuity surface, inclined at 42° in the middle of the slope, whose configuration was expected to favor the breakage of the blocks. The trajectories of the blocks released and of the resultant fragments were recorded with three video cameras. A C++ program was specifically developed to track the 3D trajectory of blocks and fragments, and measure velocities before and after the impact. Two different modules were implemented, one for the blocks that break and one for those that do not. The trajectory of a non-fragmented block is obtained by comparing it to its 3D model. In this way, both the center of mass position and the orientation of the block are tracked. For fragmented blocks, the local coordinates of the fragments determined from the images are converted to terrain coordinates using the program we developed. A total of 16 blocks and 36 rock fragments after impact were tracked. The parameters obtained were georeferenced and linked to a common system of 3D terrestrial coordinates. The captured parameters allow obtaining the velocity distribution of fragments, the coefficient of restitution, and energy balance for the blocks that break. To our knowledge, this is the first attempt to capture kinematic parameters of rock fragments that result from the impact and breakage of rock blocks in full-scale tests. Although the analysis of the rockfall fragmentation phenomenon is beyond of this work, we have compared the performance of the fragmented and unbroken blocks. To this purpose, we have built 3D models of the rock fragments generated using images captured with a drone. The results indicate that blocks that fragment show higher rebound velocities and coefficients of restitution than the blocks that do not although there exists a certain overlap between the two groups. Despite the experiment is carried out on the same discontinuity surface and with small variations in the impact velocities, impact kinetic energies and impact angles, the coefficients of restitution obtained present a wide range of values, both for the blocks that break and for those who do not. The number of tested blocks is too small to draw generalizable conclusions, but they highlight the stochastic nature of the rebound process and the necessity to consider additional parameters for its understanding. Finally, the results confirm the relation between the dissipated energy and, especially the impact energy and the new area created by fragmentation. Furthermore, the blocks that hit the ground with the face are those that generate the most new area while those that hit the vertex generate less.
2022-05-11T12:05:38ZPrades Valls, AlbertCorominas Dulcet, JordiLantada, NievesMatas Casado, GerardNúñez Andrés, María AmparoThis paper presents a procedure for tracking rockfall trajectories and extracting kinematic parameters from both the impacts and the resultant fragments. A set of full scale rockfall experiments was performed in a quarry located in Vallirana, Barcelona (Spain). The study site was chosen due to the presence of a rigid discontinuity surface, inclined at 42° in the middle of the slope, whose configuration was expected to favor the breakage of the blocks. The trajectories of the blocks released and of the resultant fragments were recorded with three video cameras. A C++ program was specifically developed to track the 3D trajectory of blocks and fragments, and measure velocities before and after the impact. Two different modules were implemented, one for the blocks that break and one for those that do not. The trajectory of a non-fragmented block is obtained by comparing it to its 3D model. In this way, both the center of mass position and the orientation of the block are tracked. For fragmented blocks, the local coordinates of the fragments determined from the images are converted to terrain coordinates using the program we developed. A total of 16 blocks and 36 rock fragments after impact were tracked. The parameters obtained were georeferenced and linked to a common system of 3D terrestrial coordinates. The captured parameters allow obtaining the velocity distribution of fragments, the coefficient of restitution, and energy balance for the blocks that break. To our knowledge, this is the first attempt to capture kinematic parameters of rock fragments that result from the impact and breakage of rock blocks in full-scale tests. Although the analysis of the rockfall fragmentation phenomenon is beyond of this work, we have compared the performance of the fragmented and unbroken blocks. To this purpose, we have built 3D models of the rock fragments generated using images captured with a drone. The results indicate that blocks that fragment show higher rebound velocities and coefficients of restitution than the blocks that do not although there exists a certain overlap between the two groups. Despite the experiment is carried out on the same discontinuity surface and with small variations in the impact velocities, impact kinetic energies and impact angles, the coefficients of restitution obtained present a wide range of values, both for the blocks that break and for those who do not. The number of tested blocks is too small to draw generalizable conclusions, but they highlight the stochastic nature of the rebound process and the necessity to consider additional parameters for its understanding. Finally, the results confirm the relation between the dissipated energy and, especially the impact energy and the new area created by fragmentation. Furthermore, the blocks that hit the ground with the face are those that generate the most new area while those that hit the vertex generate less.Application of a fuzzy verification framework for the evaluation of a regional-scale landslide early warning system during the January 2020 Gloria storm in Catalonia (NE Spain)Palau Berastegui, Rosa MariaBerenguer Ferrer, MarcHurlimann Ziegler, MarcelSempere Torres, Danielhttp://hdl.handle.net/2117/3666742022-07-27T16:31:02Z2022-05-02T17:02:21ZApplication of a fuzzy verification framework for the evaluation of a regional-scale landslide early warning system during the January 2020 Gloria storm in Catalonia (NE Spain)
Palau Berastegui, Rosa Maria; Berenguer Ferrer, Marc; Hurlimann Ziegler, Marcel; Sempere Torres, Daniel
The Gloria storm rainfalls affected Catalonia from 20 to 23 January 2020 and triggered multiple landslides, some of which affected buildings and infrastructures (such as roads and railways). This paper presents the rainfall and landslide datasets collected during the event, and evaluates the performance of a regional landslide early warning system (LEWS) during the Gloria storm applying a fuzzy verification method. The majority of the inventoried landslides can be classified as slides, involving a limited volume of sediment (up to 10 m3), and were triggered in cut slopes along linear infrastructures. Rainfall accumulations were significant in the whole region, especially in the Montseny area, where over 450 mm were registered in 96 h. Generally, the LEWS computed moderate and high warnings in the areas where large rainfall amounts were recorded, and showed good correspondence with the locations where landslides were reported. The fuzzy verification method has been applied using neighbouring windows of different sizes to obtain scale-dependant information on the LEWS performance. The skill of the LEWS considerably improves when enlarging the neighbouring window size from 500 m to 1 km.
2022-05-02T17:02:21ZPalau Berastegui, Rosa MariaBerenguer Ferrer, MarcHurlimann Ziegler, MarcelSempere Torres, DanielThe Gloria storm rainfalls affected Catalonia from 20 to 23 January 2020 and triggered multiple landslides, some of which affected buildings and infrastructures (such as roads and railways). This paper presents the rainfall and landslide datasets collected during the event, and evaluates the performance of a regional landslide early warning system (LEWS) during the Gloria storm applying a fuzzy verification method. The majority of the inventoried landslides can be classified as slides, involving a limited volume of sediment (up to 10 m3), and were triggered in cut slopes along linear infrastructures. Rainfall accumulations were significant in the whole region, especially in the Montseny area, where over 450 mm were registered in 96 h. Generally, the LEWS computed moderate and high warnings in the areas where large rainfall amounts were recorded, and showed good correspondence with the locations where landslides were reported. The fuzzy verification method has been applied using neighbouring windows of different sizes to obtain scale-dependant information on the LEWS performance. The skill of the LEWS considerably improves when enlarging the neighbouring window size from 500 m to 1 km.A Framework to Project Future Rainfall Scenarios: An Application to Shallow Landslide-Triggering Summer Rainfall in Wanzhou County ChinaFerrer Roman, JoaquinGuo, ZizhengMedina Iglesias, Vicente César dePuig i Polo, CàrolHurlimann Ziegler, Marcelhttp://hdl.handle.net/2117/3654562022-04-10T14:14:55Z2022-04-06T15:13:06ZA Framework to Project Future Rainfall Scenarios: An Application to Shallow Landslide-Triggering Summer Rainfall in Wanzhou County China
Ferrer Roman, Joaquin; Guo, Zizheng; Medina Iglesias, Vicente César de; Puig i Polo, Càrol; Hurlimann Ziegler, Marcel
Fatal landslides are a widespread geohazard that have affected millions of people and have claimed the lives of thousands around the globe. A change in climate has significantly increased the frequency and magnitude of rainfall, which affect the susceptibility of slopes to shallow landslides. This paper presents a methodological framework to assess the future changes in extreme and seasonal rainfall magnitudes with climate model projections. This framework was applied to project summer rainfall over Wanzhou County, China, using an ensemble of four regional climate models (RCMs) from the East Asian domain of the Coordinated Downscaling Experiment (CORDEX) under the Phase 5 Coupled Intercomparison Modeling Project (CMIP5). The results find that extreme daily rainfall was projected to decrease in the mid-21st century, with an uncertainty measured by a coefficient of variation between 5% and 25%. The mean seasonal rainfall is projected to increase in the mid-21st century up to a factor of 1.4, and up to a factor of 1.8 in the late-21st century. The variation in the mid21st century ranged from 10% to 35%, and from 30% to 50% in the late-21st century. This case study delivered a proof-of-concept for a methodological framework to derive shallow landslide-triggering rainfall scenarios under climate change conditions. The resulting spatially distributed climate change factors (CCFs) can be used to incorporate future rainfall scenarios in slope susceptibility models and climate impact assessments.
2022-04-06T15:13:06ZFerrer Roman, JoaquinGuo, ZizhengMedina Iglesias, Vicente César dePuig i Polo, CàrolHurlimann Ziegler, MarcelFatal landslides are a widespread geohazard that have affected millions of people and have claimed the lives of thousands around the globe. A change in climate has significantly increased the frequency and magnitude of rainfall, which affect the susceptibility of slopes to shallow landslides. This paper presents a methodological framework to assess the future changes in extreme and seasonal rainfall magnitudes with climate model projections. This framework was applied to project summer rainfall over Wanzhou County, China, using an ensemble of four regional climate models (RCMs) from the East Asian domain of the Coordinated Downscaling Experiment (CORDEX) under the Phase 5 Coupled Intercomparison Modeling Project (CMIP5). The results find that extreme daily rainfall was projected to decrease in the mid-21st century, with an uncertainty measured by a coefficient of variation between 5% and 25%. The mean seasonal rainfall is projected to increase in the mid-21st century up to a factor of 1.4, and up to a factor of 1.8 in the late-21st century. The variation in the mid21st century ranged from 10% to 35%, and from 30% to 50% in the late-21st century. This case study delivered a proof-of-concept for a methodological framework to derive shallow landslide-triggering rainfall scenarios under climate change conditions. The resulting spatially distributed climate change factors (CCFs) can be used to incorporate future rainfall scenarios in slope susceptibility models and climate impact assessments.Drone-based identification of erosive processes in open-pit mining restored areasPadró Garcia, Joan-CristianCardozo, JohnssonMontero, PauRuiz Carulla, RogerAlcañiz Baldellou, Josep MariaSerra Sangüesa, DèliaCarabassa, Vicençhttp://hdl.handle.net/2117/3649342022-04-03T13:58:13Z2022-03-28T18:52:06ZDrone-based identification of erosive processes in open-pit mining restored areas
Padró Garcia, Joan-Cristian; Cardozo, Johnsson; Montero, Pau; Ruiz Carulla, Roger; Alcañiz Baldellou, Josep Maria; Serra Sangüesa, Dèlia; Carabassa, Vicenç
Unmanned Aerial Systems, or drones, are very helpful tools for managing open-pit mining operations and developing ecological restoration activities. This article presents a method for identifying water erosion processes in active quarries by means of drone imagery remote sensing, in the absence of pre-existing imagery or mapping for comparison. A Digital Elevation Model (DEM) with a spatial resolution (SR) >10 cm and an orthophoto with an SR >2.5 cm were generated from images captured with a drone and their subsequent photogrammetric processing. By using Geographical Information Systems tools to process the DEM, a detailed drainage network was obtained, the areas of detected water erosion were separated, and the watersheds in the gullies identified. Subsequently, an estimated DEM before the erosive processes was reconstructed by interpolating the gully ridges; this DEM serves as a reference for the relief before the erosion. To calculate the volume of eroded material, the DEM of Differences was calculated, which estimates the volume difference between the previously estimated DEM and the current DEM. Additionally, we calculated the material necessary for the geomorphological adaptation of the quarry and the slope map, which are two valuable factors closely related to the monitoring of erosive processes. The results obtained allowed us to identify the erosion factors quickly and accurately in this type of mining. In the case of water-filled quarries, it would be important to characterize the subsurface relief. Essentially, the presented method can be applied with affordable and non-invasive materials to create digital grid maps at 10 cm resolution, obtaining data ready for 3D metrics, being a very practical landscape modelling tool for characterizing the restoration evolution of open-pit mining spaces
2022-03-28T18:52:06ZPadró Garcia, Joan-CristianCardozo, JohnssonMontero, PauRuiz Carulla, RogerAlcañiz Baldellou, Josep MariaSerra Sangüesa, DèliaCarabassa, VicençUnmanned Aerial Systems, or drones, are very helpful tools for managing open-pit mining operations and developing ecological restoration activities. This article presents a method for identifying water erosion processes in active quarries by means of drone imagery remote sensing, in the absence of pre-existing imagery or mapping for comparison. A Digital Elevation Model (DEM) with a spatial resolution (SR) >10 cm and an orthophoto with an SR >2.5 cm were generated from images captured with a drone and their subsequent photogrammetric processing. By using Geographical Information Systems tools to process the DEM, a detailed drainage network was obtained, the areas of detected water erosion were separated, and the watersheds in the gullies identified. Subsequently, an estimated DEM before the erosive processes was reconstructed by interpolating the gully ridges; this DEM serves as a reference for the relief before the erosion. To calculate the volume of eroded material, the DEM of Differences was calculated, which estimates the volume difference between the previously estimated DEM and the current DEM. Additionally, we calculated the material necessary for the geomorphological adaptation of the quarry and the slope map, which are two valuable factors closely related to the monitoring of erosive processes. The results obtained allowed us to identify the erosion factors quickly and accurately in this type of mining. In the case of water-filled quarries, it would be important to characterize the subsurface relief. Essentially, the presented method can be applied with affordable and non-invasive materials to create digital grid maps at 10 cm resolution, obtaining data ready for 3D metrics, being a very practical landscape modelling tool for characterizing the restoration evolution of open-pit mining spacesImpacts of future climate and land cover changes on landslide susceptibility: regional scale modelling in the Val d’Aran region (Pyrenees, Spain)Hurlimann Ziegler, MarcelGuo, ZizhengPuig i Polo, CàrolMedina Iglesias, Vicente César dehttp://hdl.handle.net/2117/3648342022-10-27T00:27:07Z2022-03-24T16:49:18ZImpacts of future climate and land cover changes on landslide susceptibility: regional scale modelling in the Val d’Aran region (Pyrenees, Spain)
Hurlimann Ziegler, Marcel; Guo, Zizheng; Puig i Polo, Càrol; Medina Iglesias, Vicente César de
It is widely accepted that future environmental changes will affect rainfall-induced shallow slides in high-mountain areas. In this study, the Val d’Aran region located in the Central Pyrenees was selected to analyze and quantify the impacts of land use and land cover (LULC) and climate changes on regional landslides susceptibility. We analyzed 26 climate models of the EURO-CORDEX database focussing on the future rainfall conditions. The IDRISI TerrSet software suite was used to create the future LULC maps. These two inputs were analyzed individually and in a combined way defining 20 different scenarios. All these scenarios were incorporated in a physically based stability model to compute landslides susceptibility maps. The results showed that both environmental conditions will considerably change in the future. The daily rainfall will increase between 14 and 26% assuming a return period of 100 years. This intensification of precipitation will produce an overall decrease of the stability condition in the study area. Regarding the LULC prediction, the forest area will significantly increase, while in particular grassland, but also shrubs decrease. As a consequence, the overall stability condition improves, because the root strength is higher in forest than in grassland and shrubs. When we analyzed the combined impacts, the results showed that the positive effect of LULC changes is larger than the negative influence of rainfall changes. Hence, when combining the two aspects in the future scenarios, the stability condition in the study area will improve.
The final publication is available at Springer via http://dx.doi.org/10.1007/s10346-021-01775-6
2022-03-24T16:49:18ZHurlimann Ziegler, MarcelGuo, ZizhengPuig i Polo, CàrolMedina Iglesias, Vicente César deIt is widely accepted that future environmental changes will affect rainfall-induced shallow slides in high-mountain areas. In this study, the Val d’Aran region located in the Central Pyrenees was selected to analyze and quantify the impacts of land use and land cover (LULC) and climate changes on regional landslides susceptibility. We analyzed 26 climate models of the EURO-CORDEX database focussing on the future rainfall conditions. The IDRISI TerrSet software suite was used to create the future LULC maps. These two inputs were analyzed individually and in a combined way defining 20 different scenarios. All these scenarios were incorporated in a physically based stability model to compute landslides susceptibility maps. The results showed that both environmental conditions will considerably change in the future. The daily rainfall will increase between 14 and 26% assuming a return period of 100 years. This intensification of precipitation will produce an overall decrease of the stability condition in the study area. Regarding the LULC prediction, the forest area will significantly increase, while in particular grassland, but also shrubs decrease. As a consequence, the overall stability condition improves, because the root strength is higher in forest than in grassland and shrubs. When we analyzed the combined impacts, the results showed that the positive effect of LULC changes is larger than the negative influence of rainfall changes. Hence, when combining the two aspects in the future scenarios, the stability condition in the study area will improve.Monitoring of rainfall and soil moisture at the Rebaixader catchment (Central Pyrenees)Oorthuis Gómez, RaülHurlimann Ziegler, MarcelAbanco Martínez de Arenzana, ClaudiaMoya Sánchez, JoséCarleo, Luigihttp://hdl.handle.net/2117/3631712024-03-10T10:21:50Z2022-02-28T19:07:09ZMonitoring of rainfall and soil moisture at the Rebaixader catchment (Central Pyrenees)
Oorthuis Gómez, Raül; Hurlimann Ziegler, Marcel; Abanco Martínez de Arenzana, Claudia; Moya Sánchez, José; Carleo, Luigi
The instrumental monitoring of torrential catchments is a fundamental research task that provides necessary information to improve our understanding of the mechanisms of debris flows. While most monitoring sites include meteorological sensors and analyze the critical rainfall conditions, very few contain soil moisture measurements. In our monitoring site, the Rebaixader catchment, 11 debris flows and 24 debris floods were detected during the last 9 years. Herein, the initiation mechanisms of these torrential flows were analyzed, focusing on the critical rainfall conditions and the soil water dynamics. Comparing the temporal distribution of both rainfall episodes and torrential flows, the Kernel density plots showed maximum values for rainfalls at the beginning of June, while the peak for torrential flows is on July 20. Thus, the antecedent rainfall, and especially the soil moisture conditions, may influence the triggering of torrential flows. In a second step, a new updated rainfall threshold was proposed that included total rainfall duration and mean intensity. The analysis of soil moisture data was more complicated, and no clear trends were observed in the data set. Therefore, additional data have to be recorded in order to quantitatively analyze the role of soil moisture on the triggering of torrential flows and for the definition of thresholds. Some preliminary results show that the soil moisture at the beginning of a rainfall event affects the maximum increase of soil moisture, while a slight trend was visible comparing the initial soil moisture with the necessary rainfall amount to trigger a torrential flow.
2022-02-28T19:07:09ZOorthuis Gómez, RaülHurlimann Ziegler, MarcelAbanco Martínez de Arenzana, ClaudiaMoya Sánchez, JoséCarleo, LuigiThe instrumental monitoring of torrential catchments is a fundamental research task that provides necessary information to improve our understanding of the mechanisms of debris flows. While most monitoring sites include meteorological sensors and analyze the critical rainfall conditions, very few contain soil moisture measurements. In our monitoring site, the Rebaixader catchment, 11 debris flows and 24 debris floods were detected during the last 9 years. Herein, the initiation mechanisms of these torrential flows were analyzed, focusing on the critical rainfall conditions and the soil water dynamics. Comparing the temporal distribution of both rainfall episodes and torrential flows, the Kernel density plots showed maximum values for rainfalls at the beginning of June, while the peak for torrential flows is on July 20. Thus, the antecedent rainfall, and especially the soil moisture conditions, may influence the triggering of torrential flows. In a second step, a new updated rainfall threshold was proposed that included total rainfall duration and mean intensity. The analysis of soil moisture data was more complicated, and no clear trends were observed in the data set. Therefore, additional data have to be recorded in order to quantitatively analyze the role of soil moisture on the triggering of torrential flows and for the definition of thresholds. Some preliminary results show that the soil moisture at the beginning of a rainfall event affects the maximum increase of soil moisture, while a slight trend was visible comparing the initial soil moisture with the necessary rainfall amount to trigger a torrential flow.Fast physically-based model for rainfall-induced landslide susceptibility assessment at regional scaleMedina Iglesias, Vicente César deHurlimann Ziegler, MarcelGuo, ZizhengLloret Morancho, AntonioVaunat, Jeanhttp://hdl.handle.net/2117/3620412023-06-20T00:30:31Z2022-02-09T13:56:24ZFast physically-based model for rainfall-induced landslide susceptibility assessment at regional scale
Medina Iglesias, Vicente César de; Hurlimann Ziegler, Marcel; Guo, Zizheng; Lloret Morancho, Antonio; Vaunat, Jean
Rainfall-induced landslides represent an important threat in mountainous areas. Therefore, a physically-based model called “Fast Shallow Landslide Assessment Model” (FSLAM) was developed to calculate large areas (>100 km2 ) with a high-resolution topography in a very short computational time. FSLAM applies a simplified hydrological model and the infinite slope theory, while the two most sensitive soil properties regarding slope stability (cohesion and friction angle) can be stochastically included. The model has five necessary input raster files including information of soil properties, vegetation, elevation and rainfall. The principal output is the probability of failure (PoF) map. The Principality of Andorra was selected as case study, where FSLAM was successfully applied and validated using the existing landslide inventory. The PoF raster file of Andorra (including 19 million cells) was calculated in only 2 min. Therefore, an accurate calibration of the input parameters was easy, which strongly improved the final outcomes.
2022-02-09T13:56:24ZMedina Iglesias, Vicente César deHurlimann Ziegler, MarcelGuo, ZizhengLloret Morancho, AntonioVaunat, JeanRainfall-induced landslides represent an important threat in mountainous areas. Therefore, a physically-based model called “Fast Shallow Landslide Assessment Model” (FSLAM) was developed to calculate large areas (>100 km2 ) with a high-resolution topography in a very short computational time. FSLAM applies a simplified hydrological model and the infinite slope theory, while the two most sensitive soil properties regarding slope stability (cohesion and friction angle) can be stochastically included. The model has five necessary input raster files including information of soil properties, vegetation, elevation and rainfall. The principal output is the probability of failure (PoF) map. The Principality of Andorra was selected as case study, where FSLAM was successfully applied and validated using the existing landslide inventory. The PoF raster file of Andorra (including 19 million cells) was calculated in only 2 min. Therefore, an accurate calibration of the input parameters was easy, which strongly improved the final outcomes.Definitions and concepts for quantitative rockfall hazard and risk analysisHantz, DidierCorominas Dulcet, JordiCrosta, Giovanni BattistaJaboyedoff, Michelhttp://hdl.handle.net/2117/3460622022-10-09T03:14:33Z2021-05-25T16:20:49ZDefinitions and concepts for quantitative rockfall hazard and risk analysis
Hantz, Didier; Corominas Dulcet, Jordi; Crosta, Giovanni Battista; Jaboyedoff, Michel
There is an increasing need for quantitative rockfall hazard and risk assessment that requires a precise definition of the terms and concepts used for this particular type of landslide. This paper suggests using terms that appear to be the most logic and explicit as possible and describes methods to derive some of the main hazards and risk descriptors. The terms and concepts presented concern the rockfall process (failure, propagation, fragmentation, modelling) and the hazard and risk descriptors, distinguishing the cases of localized and diffuse hazards. For a localized hazard, the failure probability of the considered rock compartment in a given period of time has to be assessed, and the probability for a given element at risk to be impacted with a given energy must be derived combining the failure probability, the reach probability, and the exposure of the element. For a diffuse hazard that is characterized by a failure frequency, the number of rockfalls reaching the element at risk per unit of time and with a given energy (passage frequency) can be derived. This frequency is relevant for risk assessment when the element at risk can be damaged several times. If it is not replaced, the probability that it is impacted by at least one rockfall is more relevant.
2021-05-25T16:20:49ZHantz, DidierCorominas Dulcet, JordiCrosta, Giovanni BattistaJaboyedoff, MichelThere is an increasing need for quantitative rockfall hazard and risk assessment that requires a precise definition of the terms and concepts used for this particular type of landslide. This paper suggests using terms that appear to be the most logic and explicit as possible and describes methods to derive some of the main hazards and risk descriptors. The terms and concepts presented concern the rockfall process (failure, propagation, fragmentation, modelling) and the hazard and risk descriptors, distinguishing the cases of localized and diffuse hazards. For a localized hazard, the failure probability of the considered rock compartment in a given period of time has to be assessed, and the probability for a given element at risk to be impacted with a given energy must be derived combining the failure probability, the reach probability, and the exposure of the element. For a diffuse hazard that is characterized by a failure frequency, the number of rockfalls reaching the element at risk per unit of time and with a given energy (passage frequency) can be derived. This frequency is relevant for risk assessment when the element at risk can be damaged several times. If it is not replaced, the probability that it is impacted by at least one rockfall is more relevant.