Articles de revista
http://hdl.handle.net/2117/594
2024-03-28T19:19:27ZGb-SAR interferometry displacement measurements during dewatering in construction works : case of La Sagrera railway station in Barcelona, Spain
http://hdl.handle.net/2117/104222
Gb-SAR interferometry displacement measurements during dewatering in construction works : case of La Sagrera railway station in Barcelona, Spain
Serrano Juan, Alejandro; Vázquez Suñé, Enric; Montserrat, Oriol; Crosetto, Michele; Hoffmann Jauge, Christian; Ledesma Villalba, Alberto; Criollo, Rotman; Pujades, E; Velasco Mansilla, Domitila Violeta; García Gil, Alejandro; García Alcaraz, María del Mar
Construction processes require monitoring to ensure safety and to control the new and existing structures. Traditional monitoring is based on land surveys and geotechnical instruments and only allows for point-like measurements. Ground-based synthetic aperture radar (GB-SAR) is a remote sensing radar installed in the ground that offers the possibility of acquiring measurements in 2D covering areas of up to a few square kilometers in a single acquisition. Because the GB-SAR technology measures phase shifts along the Line-of-Sight, it only allows for measurements in the longitudinal direction. Moreover, this technology requires coherence between subsequent acquisitions. These restrictions can be a limitation to the usage of GB-SAR for monitoring a construction process because in this context, the movements of soil and existing structures occur in any direction and at a very fast pace. This paper aims to test the GB-SAR suitability to measure movements during construction. To do so, an experiment was performed in the future railway station of La Sagrera, Barcelona (Spain), in which GB-SAR was used to accurately quantify wall displacements induced by dewatering and proved to be helpful to understand structural deformations and to identify vulnerable areas. The results were compared to traditional monitoring data and numerical models to confirm the reliability of the GB-SAR measurements.
The final publication is available at Springer via http://dx.doi.org/10.1016/j.enggeo.2016.02.014
2017-05-09T08:32:47ZSerrano Juan, AlejandroVázquez Suñé, EnricMontserrat, OriolCrosetto, MicheleHoffmann Jauge, ChristianLedesma Villalba, AlbertoCriollo, RotmanPujades, EVelasco Mansilla, Domitila VioletaGarcía Gil, AlejandroGarcía Alcaraz, María del MarConstruction processes require monitoring to ensure safety and to control the new and existing structures. Traditional monitoring is based on land surveys and geotechnical instruments and only allows for point-like measurements. Ground-based synthetic aperture radar (GB-SAR) is a remote sensing radar installed in the ground that offers the possibility of acquiring measurements in 2D covering areas of up to a few square kilometers in a single acquisition. Because the GB-SAR technology measures phase shifts along the Line-of-Sight, it only allows for measurements in the longitudinal direction. Moreover, this technology requires coherence between subsequent acquisitions. These restrictions can be a limitation to the usage of GB-SAR for monitoring a construction process because in this context, the movements of soil and existing structures occur in any direction and at a very fast pace. This paper aims to test the GB-SAR suitability to measure movements during construction. To do so, an experiment was performed in the future railway station of La Sagrera, Barcelona (Spain), in which GB-SAR was used to accurately quantify wall displacements induced by dewatering and proved to be helpful to understand structural deformations and to identify vulnerable areas. The results were compared to traditional monitoring data and numerical models to confirm the reliability of the GB-SAR measurements.Carbon dioxide and helium dissolved gases in groundwater at central Tenerife Island, Canary Islands: chemical and isotopic characterization
http://hdl.handle.net/2117/78571
Carbon dioxide and helium dissolved gases in groundwater at central Tenerife Island, Canary Islands: chemical and isotopic characterization
Marrero Díaz, Rayco; Lopez, Dina; Pérez Rodriguez, Nemesio M.; Custodio Gimena, Emilio; Sumino, Hirochika; Melian, Gladys V.; Padron, Eleazar; Calvo, David; Barrancos, Jose; Padilla, German; Sortino, Francesco
Seismic-volcanic unrest was detected between 2004 and 2005 in the central and northwest zones of Tenerife Island (Canary Islands, Spain). With the aim of strengthening the program of geochemical and seismic-volcanic surveillance, a study of the origin, characteristics, and spatial distribution of dissolved carbon dioxide (CO2) and helium (He) gases in the volcanic aquifer of central Tenerife Island and around Teide volcano was carried out. This work also improves the hydrogeological and hydrogeochemical conceptual model of groundwater flow. Dissolved CO2 concentrations in sampled groundwater are several orders of magnitude higher than that of air-saturated water (ASW) suggesting a significant contribution of non-atmospheric CO2, mainly magmatic, confirmed through measurement of isotopic compositions (delta C-13(TDIC)) and total dissolved inorganic carbon (TDIC) concentrations. A vertical stratification of dissolved CO2 and delta C-13(TDIC) values was observed in the volcanic aquifer at the eastern region of Las Canadas Caldera. Stratification seems to be controlled by both degree of magmatic CO2-water interaction and CO2 degassing and the original delta C-13(co2(g)) isotopic composition. The highest dissolved helium (He-4) concentrations in groundwater seem to be related to radiogenic contributions resulting from water-rock interactions, and increase with residence time, instead of with endogenous magmatic inputs. Isotopic systematics show that the dissolved gases in groundwater of central Tenerife are variable mixtures of CO2-He-3-rich fluids of volcanic-hydrothermal origin with both organic and atmospheric components. The results suggest that the eastern area of Las Canadas Caldera, the South Volcanic Ridge, and the Teide summit cone are the areas most affected by degassing of the volcanic-hydrothermal system, and they are therefore the most suitable zones for future geochemical monitoring.
2015-10-30T13:39:34ZMarrero Díaz, RaycoLopez, DinaPérez Rodriguez, Nemesio M.Custodio Gimena, EmilioSumino, HirochikaMelian, Gladys V.Padron, EleazarCalvo, DavidBarrancos, JosePadilla, GermanSortino, FrancescoSeismic-volcanic unrest was detected between 2004 and 2005 in the central and northwest zones of Tenerife Island (Canary Islands, Spain). With the aim of strengthening the program of geochemical and seismic-volcanic surveillance, a study of the origin, characteristics, and spatial distribution of dissolved carbon dioxide (CO2) and helium (He) gases in the volcanic aquifer of central Tenerife Island and around Teide volcano was carried out. This work also improves the hydrogeological and hydrogeochemical conceptual model of groundwater flow. Dissolved CO2 concentrations in sampled groundwater are several orders of magnitude higher than that of air-saturated water (ASW) suggesting a significant contribution of non-atmospheric CO2, mainly magmatic, confirmed through measurement of isotopic compositions (delta C-13(TDIC)) and total dissolved inorganic carbon (TDIC) concentrations. A vertical stratification of dissolved CO2 and delta C-13(TDIC) values was observed in the volcanic aquifer at the eastern region of Las Canadas Caldera. Stratification seems to be controlled by both degree of magmatic CO2-water interaction and CO2 degassing and the original delta C-13(co2(g)) isotopic composition. The highest dissolved helium (He-4) concentrations in groundwater seem to be related to radiogenic contributions resulting from water-rock interactions, and increase with residence time, instead of with endogenous magmatic inputs. Isotopic systematics show that the dissolved gases in groundwater of central Tenerife are variable mixtures of CO2-He-3-rich fluids of volcanic-hydrothermal origin with both organic and atmospheric components. The results suggest that the eastern area of Las Canadas Caldera, the South Volcanic Ridge, and the Teide summit cone are the areas most affected by degassing of the volcanic-hydrothermal system, and they are therefore the most suitable zones for future geochemical monitoring.Evaluation of two carbon sources for inducing denitrification: batch and column experiments
http://hdl.handle.net/2117/78565
Evaluation of two carbon sources for inducing denitrification: batch and column experiments
Grau_Martínez, Alba; Carrey, Raul; Torrentó, Clara; Folch Sancho, Albert; Soler, Albert; Otero, Neus
Artificial recharge improves several water quality parameters. Denitrification is a good example of water treatment process that could be achieved through artificial recharge. To improve the removal of nitrate and other emerging organic contaminants (EOCs) a reactive barrier at the bottom of aninfiltration pond can be added. In the present study, the efficiency in removing nitrate of an artificial recharge system with a compost layer located in the Mediterranean area (Sant Vicenç dels Horts, Catalonia)is evaluated, as well as the feasibility of another carbon source to be used as reactive layer in the artificial recharge system planned in theMaghreb Region. We examined the effectiveness of two different materials, commercial compost and crushed palm tree leaves, in batch and column experiments. The results of batch experiments confirmed that both materials induced denitrification andthe flow-through experiments showed complete nitrate removal. The isotopic fractionation of nitrogen and oxygen of dissolved nitrate was calculated for both experiments in order to provide a tool to evaluate the efficacy of the treatments in future field scale studies.
2015-10-30T12:40:45ZGrau_Martínez, AlbaCarrey, RaulTorrentó, ClaraFolch Sancho, AlbertSoler, AlbertOtero, NeusArtificial recharge improves several water quality parameters. Denitrification is a good example of water treatment process that could be achieved through artificial recharge. To improve the removal of nitrate and other emerging organic contaminants (EOCs) a reactive barrier at the bottom of aninfiltration pond can be added. In the present study, the efficiency in removing nitrate of an artificial recharge system with a compost layer located in the Mediterranean area (Sant Vicenç dels Horts, Catalonia)is evaluated, as well as the feasibility of another carbon source to be used as reactive layer in the artificial recharge system planned in theMaghreb Region. We examined the effectiveness of two different materials, commercial compost and crushed palm tree leaves, in batch and column experiments. The results of batch experiments confirmed that both materials induced denitrification andthe flow-through experiments showed complete nitrate removal. The isotopic fractionation of nitrogen and oxygen of dissolved nitrate was calculated for both experiments in order to provide a tool to evaluate the efficacy of the treatments in future field scale studies.The great Colorado flood of September 2013
http://hdl.handle.net/2117/78527
The great Colorado flood of September 2013
Gochis, David; Rutledge, Steven A.; Sempere Torres, Daniel; Steiner, Matthias; Chandrasekar, V.
During the second week of September 2013, a seasonally uncharacteristic weather pattern stalled over the Rocky Mountain Front Range region of northern Colorado bringing with it copious amounts of moisture from the Gulf of Mexico, Caribbean Sea, and the tropical eastern Pacific Ocean. This feed of moisture was funneled toward the east-facing mountain slopes through a series of mesoscale circulation features, resulting in several days of unusually widespread heavy rainfall over steep mountainous terrain. Catastrophic flooding ensued within several Front Range river systems that washed away highways, destroyed towns, isolated communities, necessitated days of airborne evacuations, and resulted in eight fatalities. The impacts from heavy rainfall and flooding were felt over a broad region of northern Colorado leading to 18 counties being designated as federal disaster areas and resulting in damages exceeding $2 billion (U.S. dollars). This study explores the meteorological and hydrological ingredients that led to this extreme event. After providing a basic timeline of events, synoptic and mesoscale circulation features of the event are discussed. Particular focus is placed on documenting how circulation features, embedded within the larger synoptic flow, served to funnel moist inflow into the mountain front driving several days of sustained orographic precipitation. Operational and research networks of polarimetric radar and surface instrumentation were used to evaluate the cloud structures and dominant hydrometeor characteristics. The performance of several quantitative precipitation estimates, quantitative precipitation forecasts, and hydrological forecast products are also analyzed with the intention of identifying what monitoring and prediction tools worked and where further improvements are needed.
2015-10-29T16:54:37ZGochis, DavidRutledge, Steven A.Sempere Torres, DanielSteiner, MatthiasChandrasekar, V.During the second week of September 2013, a seasonally uncharacteristic weather pattern stalled over the Rocky Mountain Front Range region of northern Colorado bringing with it copious amounts of moisture from the Gulf of Mexico, Caribbean Sea, and the tropical eastern Pacific Ocean. This feed of moisture was funneled toward the east-facing mountain slopes through a series of mesoscale circulation features, resulting in several days of unusually widespread heavy rainfall over steep mountainous terrain. Catastrophic flooding ensued within several Front Range river systems that washed away highways, destroyed towns, isolated communities, necessitated days of airborne evacuations, and resulted in eight fatalities. The impacts from heavy rainfall and flooding were felt over a broad region of northern Colorado leading to 18 counties being designated as federal disaster areas and resulting in damages exceeding $2 billion (U.S. dollars). This study explores the meteorological and hydrological ingredients that led to this extreme event. After providing a basic timeline of events, synoptic and mesoscale circulation features of the event are discussed. Particular focus is placed on documenting how circulation features, embedded within the larger synoptic flow, served to funnel moist inflow into the mountain front driving several days of sustained orographic precipitation. Operational and research networks of polarimetric radar and surface instrumentation were used to evaluate the cloud structures and dominant hydrometeor characteristics. The performance of several quantitative precipitation estimates, quantitative precipitation forecasts, and hydrological forecast products are also analyzed with the intention of identifying what monitoring and prediction tools worked and where further improvements are needed.Estimating natural recharge by means of chloride mass balance in a volcanic aquifer: northeastern Gran Canaria (Canary Islands, Spain)
http://hdl.handle.net/2117/78085
Estimating natural recharge by means of chloride mass balance in a volcanic aquifer: northeastern Gran Canaria (Canary Islands, Spain)
Naranjo, Gema; Cruz Fuentes, Tatiana; Cabrera Santana, Maria del Carmen; Custodio Gimena, Emilio
The chloride mass balance method was used to estimate the average diffuse groundwater recharge on northeastern Gran Canaria (Canary Islands), where the largest recharge to the volcanic island aquifer occurs. Rainwater was sampled monthly in ten rainwater collectors to determine the bulk deposition rate of chloride for the 2008-2014 period. Average chloride deposition decreases inwardly from more than 10 g center dot m(-2)center dot year(-1) to about 4 g center dot m(-2)center dot year(-1). The application of the chloride mass balance method resulted in an estimated average recharge of about 28 hm(3)/year or 92 mm/year (24% of precipitation) in the study area after subtracting chloride loss with surface runoff. The average storm runoff was estimated to be 12 hm(3)/year (9% of precipitation) for the 1980-2014 period. Runoff was sampled during scarce rainy periods, which produce surface water flow. Average recharge varies from less than a few mm/year near the coast up to 270 mm/year in the highlands (about 33% of average rainfall), with a close-to-linear increase inwardly of about 18 mm center dot year(-1)center dot km(-1). Recharge rate uncertainty corresponds to an estimated CV of 0.3-0.4 because of the short data series available.
2015-10-21T17:46:00ZNaranjo, GemaCruz Fuentes, TatianaCabrera Santana, Maria del CarmenCustodio Gimena, EmilioThe chloride mass balance method was used to estimate the average diffuse groundwater recharge on northeastern Gran Canaria (Canary Islands), where the largest recharge to the volcanic island aquifer occurs. Rainwater was sampled monthly in ten rainwater collectors to determine the bulk deposition rate of chloride for the 2008-2014 period. Average chloride deposition decreases inwardly from more than 10 g center dot m(-2)center dot year(-1) to about 4 g center dot m(-2)center dot year(-1). The application of the chloride mass balance method resulted in an estimated average recharge of about 28 hm(3)/year or 92 mm/year (24% of precipitation) in the study area after subtracting chloride loss with surface runoff. The average storm runoff was estimated to be 12 hm(3)/year (9% of precipitation) for the 1980-2014 period. Runoff was sampled during scarce rainy periods, which produce surface water flow. Average recharge varies from less than a few mm/year near the coast up to 270 mm/year in the highlands (about 33% of average rainfall), with a close-to-linear increase inwardly of about 18 mm center dot year(-1)center dot km(-1). Recharge rate uncertainty corresponds to an estimated CV of 0.3-0.4 because of the short data series available.Comments on uncertainty in groundwater governance in the volcanic Canary islands, Spain
http://hdl.handle.net/2117/78084
Comments on uncertainty in groundwater governance in the volcanic Canary islands, Spain
Custodio Gimena, Emilio; Cabrera Santana, Maria del Carmen; Cruz Fuentes, Tatiana; Naranjo, Gema; Puga de Miguel, Luis Olavo
The uncertainty associated with natural magnitudes and processes is conspicuous in water resources and groundwater evaluation. This uncertainty has an essential component and a part that can be reduced to some extent by increasing knowledge, improving monitoring coverage, continuous elaboration of data and accuracy and addressing the related economic and social aspects involved. Reducing uncertainty has a cost that may not be justified by the improvement that is obtainable, but that has to be known to make the right decisions. With this idea, this paper contributes general comments on the evaluation of groundwater resources in the semiarid Canary Islands and on some of the main sources of uncertainty, but a full treatment is not attempted, nor how to reduce it. Although the point of view is local, these comments may help to address similar situations on other islands where similar problems appear. A consequence of physical and hydrological uncertainty is that different hydrogeological and water resource studies and evaluations may yield different results. Understanding and coarsely evaluating uncertainty helps in reducing administrative instability, poor decisions that may harm groundwater property rights, the rise of complaints and the sub-optimal use of the scarce water resources available in semiarid areas. Transparency and honesty are needed, but especially a clear understanding of what numbers mean and the uncertainty around them, to act soundly and avoid conflicting and damaging rigid attitudes. However, the different situations could condition that what may be good in a place, may not always be the case in other places.
2015-10-21T17:37:16ZCustodio Gimena, EmilioCabrera Santana, Maria del CarmenCruz Fuentes, TatianaNaranjo, GemaPuga de Miguel, Luis OlavoThe uncertainty associated with natural magnitudes and processes is conspicuous in water resources and groundwater evaluation. This uncertainty has an essential component and a part that can be reduced to some extent by increasing knowledge, improving monitoring coverage, continuous elaboration of data and accuracy and addressing the related economic and social aspects involved. Reducing uncertainty has a cost that may not be justified by the improvement that is obtainable, but that has to be known to make the right decisions. With this idea, this paper contributes general comments on the evaluation of groundwater resources in the semiarid Canary Islands and on some of the main sources of uncertainty, but a full treatment is not attempted, nor how to reduce it. Although the point of view is local, these comments may help to address similar situations on other islands where similar problems appear. A consequence of physical and hydrological uncertainty is that different hydrogeological and water resource studies and evaluations may yield different results. Understanding and coarsely evaluating uncertainty helps in reducing administrative instability, poor decisions that may harm groundwater property rights, the rise of complaints and the sub-optimal use of the scarce water resources available in semiarid areas. Transparency and honesty are needed, but especially a clear understanding of what numbers mean and the uncertainty around them, to act soundly and avoid conflicting and damaging rigid attitudes. However, the different situations could condition that what may be good in a place, may not always be the case in other places.Field and laboratory analysis of the runout characteristics of hillslope debris flows in Switzerland
http://hdl.handle.net/2117/77265
Field and laboratory analysis of the runout characteristics of hillslope debris flows in Switzerland
Hurlimann Ziegler, Marcel; McArdell, Brian, W.; Rickli, Christian
Hillslope debris flows are unconfined flows that originate by shallow failures in unconsolidated material at steep slopes. In spite of their significant hazard for persons and infrastructure in mountainous regions, research on hillslope debris flows is rather scarce in comparison to other landslide types. This study focusses on the runout characteristics of hillslope debris flows applying two different approaches. First, detailed landslide inventories, which include field measurements of 548 slope failures that occurred during the last two decades in seven parts of Switzerland, were analysed. Second, laboratory tests were carried out to study the effect of the soil water content, grain-size distribution and mobilized volume on the runout behaviour of hillslope debris flows. Most of the failures in the field started as shallow translational slides at terrain slopes between 25° and 45° and involved volumes of some tens to a few hundred cubic meters. An analysis of the runout distance of 117 hillslope debris flows showed that they normally travelled some tens of meters, but sometimes the runout exceeded 300 m. A positive relation between volume and runout distance and between volume and affected area was observed, although there is considerable scatter in the data. The affected area of 63 hillslope debris flows ranged from ~ 100 to ~ 1500 m2. Based on the field data, a 7.5 m long laboratory hillslope was designed with a geometrical scale factor of 20. A total of 75 runs with volumes from 4 to 20 dm3, water contents from 18% to 38%, and four grain-size distributions were carried out. The laboratory tests revealed that water content is the dominant control, but also the clay content strongly influences the runout distance and the affected area. Even a small increase in water or clay content produces a considerably larger or smaller runout distance, respectively. In contrast, the influence of the volume on the runout was smaller, and a positive relation was observed between these two parameters. The field and laboratory results are in general agreement and consistent with the results of other studies. The results of this work improve the understanding of hillslope debris flows and may aid in the hazard assessments of these processes.
2015-10-01T14:38:03ZHurlimann Ziegler, MarcelMcArdell, Brian, W.Rickli, ChristianHillslope debris flows are unconfined flows that originate by shallow failures in unconsolidated material at steep slopes. In spite of their significant hazard for persons and infrastructure in mountainous regions, research on hillslope debris flows is rather scarce in comparison to other landslide types. This study focusses on the runout characteristics of hillslope debris flows applying two different approaches. First, detailed landslide inventories, which include field measurements of 548 slope failures that occurred during the last two decades in seven parts of Switzerland, were analysed. Second, laboratory tests were carried out to study the effect of the soil water content, grain-size distribution and mobilized volume on the runout behaviour of hillslope debris flows. Most of the failures in the field started as shallow translational slides at terrain slopes between 25° and 45° and involved volumes of some tens to a few hundred cubic meters. An analysis of the runout distance of 117 hillslope debris flows showed that they normally travelled some tens of meters, but sometimes the runout exceeded 300 m. A positive relation between volume and runout distance and between volume and affected area was observed, although there is considerable scatter in the data. The affected area of 63 hillslope debris flows ranged from ~ 100 to ~ 1500 m2. Based on the field data, a 7.5 m long laboratory hillslope was designed with a geometrical scale factor of 20. A total of 75 runs with volumes from 4 to 20 dm3, water contents from 18% to 38%, and four grain-size distributions were carried out. The laboratory tests revealed that water content is the dominant control, but also the clay content strongly influences the runout distance and the affected area. Even a small increase in water or clay content produces a considerably larger or smaller runout distance, respectively. In contrast, the influence of the volume on the runout was smaller, and a positive relation was observed between these two parameters. The field and laboratory results are in general agreement and consistent with the results of other studies. The results of this work improve the understanding of hillslope debris flows and may aid in the hazard assessments of these processes.Environmental and economic assessment of a pilot stormwater infiltration system for flood prevention in Brazil
http://hdl.handle.net/2117/77210
Environmental and economic assessment of a pilot stormwater infiltration system for flood prevention in Brazil
Petit Boix, Anna; Sevigné-Itoiz, Eva; Rojas-Gutierrez, L. A.; Paceli Barbassa, Ademir; Josa Garcia-Tornel, Alejandro; Rieradevall, J.; Gabarrell, Xavier
Green and grey stormwater management infrastructures, such as the filter, swale and infiltration trench (FST), can be used to prevent flooding events. The aim of this paper was to determine the environmental and economic impacts of a pilot FST that was built in São Carlos (Brazil) using Life Cycle Assessment (LCA) and Life Cycle Costing (LCC). As a result, the components with the greatest contributions to the total impacts of the FST were the infiltration trench and the grass cover. The system has a carbon footprint of 0.13 kg CO2 eq./m3 of infiltrated stormwater and an eco-efficiency ratio of 0.35 kg CO2 eq./USD. Moreover, the FST prevented up to 95% of the runoff in the area. Compared to a grey infrastructure, this system is a good solution with respect to PVC stormwater pipes, which require a long pipe length (1070 m) and have a shorter lifespan. In contrast, concrete pipes are a better solution, and their impacts are similar to those of the FST. Finally, a sensitivity analysis was conducted to assess the changes in the impacts with the varying lifespan of the system components. Thus, the proper management of the FST can reduce the economic and environmental impacts of the system by increasing its durability.
2015-09-30T16:54:55ZPetit Boix, AnnaSevigné-Itoiz, EvaRojas-Gutierrez, L. A.Paceli Barbassa, AdemirJosa Garcia-Tornel, AlejandroRieradevall, J.Gabarrell, XavierGreen and grey stormwater management infrastructures, such as the filter, swale and infiltration trench (FST), can be used to prevent flooding events. The aim of this paper was to determine the environmental and economic impacts of a pilot FST that was built in São Carlos (Brazil) using Life Cycle Assessment (LCA) and Life Cycle Costing (LCC). As a result, the components with the greatest contributions to the total impacts of the FST were the infiltration trench and the grass cover. The system has a carbon footprint of 0.13 kg CO2 eq./m3 of infiltrated stormwater and an eco-efficiency ratio of 0.35 kg CO2 eq./USD. Moreover, the FST prevented up to 95% of the runoff in the area. Compared to a grey infrastructure, this system is a good solution with respect to PVC stormwater pipes, which require a long pipe length (1070 m) and have a shorter lifespan. In contrast, concrete pipes are a better solution, and their impacts are similar to those of the FST. Finally, a sensitivity analysis was conducted to assess the changes in the impacts with the varying lifespan of the system components. Thus, the proper management of the FST can reduce the economic and environmental impacts of the system by increasing its durability.Size distribution for potentially unstable rock masses and in situ rock blocks using LIDAR-generated digital elevation models
http://hdl.handle.net/2117/76613
Size distribution for potentially unstable rock masses and in situ rock blocks using LIDAR-generated digital elevation models
Mavrouli, Olga Christina; Corominas Dulcet, Jordi; Jaboyedoff, M.
In this paper, two analytical procedures which are independent from the existence of empirical data are presented for the calculation of (1) the size distribution of potentially unstable rock masses that expresses the potential rockfall size distribution, including big volumes corresponding to potential rare events with low susceptibility of failure and (2) the in situ block distribution on the slope face. Two approaches are, respectively, used. The first one involves the detection of kinematically unstable surfaces on a digital elevation model (DEM) and on orthophotos and the calculation of the volumes resting on them. For the second one the in situ block volumes formed by the intersection of the existing discontinuity sets are calculated using a high-resolution DEM. The procedures are presented through an application example at the country of Andorra and in particular at the chute of Forat Negre. The results from the first procedure indicate that it is kinematically possible to have mobilized volumes of some thousands of cubic meters; however, these are considered rare events with low susceptibility of failure. The size distribution of potentially unstable rock masses for big volume events was well fitted by a power law with an exponent of -0.5. The in situ block distribution on the slope face from the second procedure, assuming three types of intersection between the joints of the existing discontinuity sets and two extreme cases of discontinuity persistence, was also found to follow a power law, but with an exponent of -1.3. The comparison with the observed in the field block volume distribution on the slope face indicates that in reality discontinuities have a very high persistence and that considering only their visible trace length overestimates volumes, which is conservative.
2015-09-04T09:14:32ZMavrouli, Olga ChristinaCorominas Dulcet, JordiJaboyedoff, M.In this paper, two analytical procedures which are independent from the existence of empirical data are presented for the calculation of (1) the size distribution of potentially unstable rock masses that expresses the potential rockfall size distribution, including big volumes corresponding to potential rare events with low susceptibility of failure and (2) the in situ block distribution on the slope face. Two approaches are, respectively, used. The first one involves the detection of kinematically unstable surfaces on a digital elevation model (DEM) and on orthophotos and the calculation of the volumes resting on them. For the second one the in situ block volumes formed by the intersection of the existing discontinuity sets are calculated using a high-resolution DEM. The procedures are presented through an application example at the country of Andorra and in particular at the chute of Forat Negre. The results from the first procedure indicate that it is kinematically possible to have mobilized volumes of some thousands of cubic meters; however, these are considered rare events with low susceptibility of failure. The size distribution of potentially unstable rock masses for big volume events was well fitted by a power law with an exponent of -0.5. The in situ block distribution on the slope face from the second procedure, assuming three types of intersection between the joints of the existing discontinuity sets and two extreme cases of discontinuity persistence, was also found to follow a power law, but with an exponent of -1.3. The comparison with the observed in the field block volume distribution on the slope face indicates that in reality discontinuities have a very high persistence and that considering only their visible trace length overestimates volumes, which is conservative.Large-scale rock slope failures in the eastern Pyrenees: identifying a sparse but significant population in paraglacial and parafluvial contexts
http://hdl.handle.net/2117/76607
Large-scale rock slope failures in the eastern Pyrenees: identifying a sparse but significant population in paraglacial and parafluvial contexts
Jarman, David; Calvet, Marc; Corominas Dulcet, Jordi; Delmas, Magali; Gunnell, Yanni
This first overview of large-scale rock slope failure (RSF) in the Pyrenees addresses the eastern third of the range. Around 30 principal RSFs >0.25 km2 and 20 lesser or uncertain cases have been identified from remote imagery and groundtruthing. Compared with other European mountain ranges, RSF incidence is relatively sparse, displays no obvious regional trend or spatial clustering, and occurs across diverse landscape types, if mainly on metamorphic rocks. A transition is observed from paraglacial RSFs in formerly-glaciated valleys to what are here termed ‘parafluvial’ RSFs, within wholly or mainly fluvial valleys but where slope failure is not directly provoked by or linked to river erosion. RSFs are particularly found in three topographic settings: (i) at cirque and trough-head thresholds (transition zones of elevated instability between cirque and main glaciated trough walls); (ii) near the upper or outer periphery of the ice field, where glacial adaptation of fluvial valleys is incomplete; and (iii) in fluvial valleys beyond glacial limits where incision is locally intense. RSF is absent from the range divide, from within cirques, and from most main valleys. In the montane areas, RSF is strongly associated with vestiges of preglacial summit surfaces, confirming that plateau ridges are less stable than sharpened crests and horns. RSF is contributing significantly to the progressive destruction of this paleic relief. The overall sparsity of RSF indicates insufficient rock mass stresses, including rebound after concentrated bedrock erosion. This may reflect a relatively weak imprint of glacial erosion, including breaching, in a context of relatively low mean rates of neotectonic uplift, possibly signalling overall that eastern Pyrenees landscapes are close to dynamic equilibrium.
This is the accepted version of the following article: [Jarman, D., Calvet, M., Corominas, J., Delmas, M. and Gunnell, Y. (2014), Large-Scale Rock Slope Failures in the Eastern Pyrenees: Identifying a Sparse But Significant Population in Paraglacial and Parafluvial Contexts. Geografiska Annaler: Series A, Physical Geography, 96: 357–391. doi: 10.1111/geoa.12060], which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1111/geoa.12060/full
2015-09-03T16:25:57ZJarman, DavidCalvet, MarcCorominas Dulcet, JordiDelmas, MagaliGunnell, YanniThis first overview of large-scale rock slope failure (RSF) in the Pyrenees addresses the eastern third of the range. Around 30 principal RSFs >0.25 km2 and 20 lesser or uncertain cases have been identified from remote imagery and groundtruthing. Compared with other European mountain ranges, RSF incidence is relatively sparse, displays no obvious regional trend or spatial clustering, and occurs across diverse landscape types, if mainly on metamorphic rocks. A transition is observed from paraglacial RSFs in formerly-glaciated valleys to what are here termed ‘parafluvial’ RSFs, within wholly or mainly fluvial valleys but where slope failure is not directly provoked by or linked to river erosion. RSFs are particularly found in three topographic settings: (i) at cirque and trough-head thresholds (transition zones of elevated instability between cirque and main glaciated trough walls); (ii) near the upper or outer periphery of the ice field, where glacial adaptation of fluvial valleys is incomplete; and (iii) in fluvial valleys beyond glacial limits where incision is locally intense. RSF is absent from the range divide, from within cirques, and from most main valleys. In the montane areas, RSF is strongly associated with vestiges of preglacial summit surfaces, confirming that plateau ridges are less stable than sharpened crests and horns. RSF is contributing significantly to the progressive destruction of this paleic relief. The overall sparsity of RSF indicates insufficient rock mass stresses, including rebound after concentrated bedrock erosion. This may reflect a relatively weak imprint of glacial erosion, including breaching, in a context of relatively low mean rates of neotectonic uplift, possibly signalling overall that eastern Pyrenees landscapes are close to dynamic equilibrium.