Rockfall simulations constitute the first step toward hazard assessments and can guide future roc... more Rockfall simulations constitute the first step toward hazard assessments and can guide future rockfall prevention efforts. In this work, we assess the impact of digital elevation model (DEM) resolution on the accuracy of numerical rockfall simulation outputs. For this purpose, we compared the simulation output obtained using 1 m, 2 m and 3 m resolution UAV-derived DEMs, to two other models based on coarser topographic data (a 5 m resolution DEM obtained through interpolating elevation contours and the Shuttle Radar Topographic Mission 30m DEM). To generate the validation data, we conducted field surveys in order to map the real trajectories of three boulders that were detached during a rockfall event that occurred on 1 December 2018. Our findings suggest that the use of low to medium-resolution DEMs translated into large errors in the shape of the simulated trajectories as well as the computed runout distances, which appeared to be exaggerated by such models. The geometry of the run...
This research tests the application of GNSS and RPAS techniques to the spatiotemporal analysis of... more This research tests the application of GNSS and RPAS techniques to the spatiotemporal analysis of landslide dynamics. Our method began by establishing non-permanent GNSS networks on the slope surfaces to perform periodic measurements by differential GNSS. Similarly, RPAS flights were made to acquire high-resolution images, which were oriented and georeferenced using ground control points and structure-from-motion algorithms to ultimately obtain digital surface models and orthophotos. Based on GNSS measurements, the direction and velocity of displacements were accurately calculated, and orthophotos and DSMs were used to calculate horizontal and vertical displacements in a set of significant points throughout the study area, reaching accuracies higher than 0.035 m in the GNSS data and 0.10 m in the RPAS data. These values were within the accuracy required for such studies. Based on the field observations and the results from the photogrammetric studies, the two studied landslides were...
The Eastern coast of the Granada Province, modelled on Alpujarrides metapelitic rocks, has been v... more The Eastern coast of the Granada Province, modelled on Alpujarrides metapelitic rocks, has been very frequently affected by landslides, usually triggered by a combination of rainfall and anthropic actions. Its relief includes instable zones and old landslides of variable size and unknown age. In the seventies, great residential resorts were damaged in Punta de la Mona and Velilla (Almuñécar), and then roadworks for widening the National Road 340, induced slope failures affecting new residential areas along the road in the municipalities of Salobreña and Almuñécar. More recently, from the late nineties, a great residential complex built up on Cerro Gordo (La Herradura, Almuñécar), is heavily affected since 2005 by widespread damages; its construction involved excavations and fillings, frequently performed too quickly, and lacking of adequate drainage and stabilization treatments. Rainfall and the leaks by breakage of water supply and sanitation networks are the main triggering factor...
Landslide susceptibility maps (LSMs) rely on statistical association for weighting the impact of ... more Landslide susceptibility maps (LSMs) rely on statistical association for weighting the impact of each predictive factor class. However, the effects of using different training datasets and causative factors combinations on the accuracy of the results are rarely discussed. Accordingly, we investigated the effects of training data and computation technique selection on the accuracy and performance of LSMs. Results show that including relict landslides in the training data diminishes the accuracy of the LSMs compared to models that exclude such processes from the input. As for the effect of choosing different combinations of predictive variables, it was shown to be less significant. After investigating association and causality between predictive variables, the best performing models produced using frequency ratio and logistic regression tend to be more accurate than those including all variables. As for the artificial neural networks, it seems to outperform other models. Indeed, such investigations are beneficial for improving LSMs.
espanolLa costa oriental de la provincia de Granada, modelada sobre rocas metapeliticas Alpujarri... more espanolLa costa oriental de la provincia de Granada, modelada sobre rocas metapeliticas Alpujarrides ha sido afectada frecuentemente por movimientos de ladera, activados por una combinacion de lluvias y accion antropica. Su relieve incorpora zonas inestables y deslizamientos antiguos de tamano variable y edad indeterminada. En los anos setenta, quedaron danados grandes complejos residenciales en Punta de la Mona y Velilla (Almunecar) y despues las obras de ampliacion de la carretera C.N. 340, indujeron roturas de laderas que afectaron a las nuevas urbanizaciones construidas a lo largo de la carretera en los terminos de Salobrena y Almunecar. Mas recientemente, a partir de finales de los noventa, se construyo en Cerro Gordo (La Herradura, Almunecar), un gran complejo residencial, que desde 2005, se ve afectado por danos generalizados; su construccion implico excavaciones y rellenos, practicados frecuentemente con demasiada rapidez, y por lo tanto carecieron de tratamientos de drenaje...
Abstract. This research tests the application of GNSS and RPAS techniques to the spatiotemporal a... more Abstract. This research tests the application of GNSS and RPAS techniques to the spatiotemporal analysis of landslide dynamics. Our method began by establishing non-permanent GNSS networks on the slope surfaces to perform periodic measurements by differential GNSS. Similarly, RPAS flights were made to acquire high-resolution images, which were oriented and georeferenced using ground control points and structure-from-motion algorithms to obtain digital surface models and orthophotos ultimately. Based on GNSS measurements, the direction and velocity of displacements were accurately calculated, and orthophotos and DSMs were used to calculate horizontal and vertical displacements in a set of significant points throughout the study area, reaching accuracies higher than 0.035 m in the GNSS data and 0.10 m in the RPAS data. These values were within the accuracy required for such studies. Based on the field observations and the results from the photogrammetric studies, the two studied lands...
Abstract Coastal landslides cause great economic damage to human installations along the Mediterr... more Abstract Coastal landslides cause great economic damage to human installations along the Mediterranean shoreline . In the Alboran Sea, this phenomenon is very common and causes many problems for residential resorts and road infrastructures in coastal areas. In the last two decades, such slope instability processes were the subject of many studies, which employed multidisciplinary approaches to understand their underlying mechanisms and surficial kinematics in Southern Spain and elsewhere in the Mediterranean. However, advanced and new investigation methods and techniques used in these studies have never been performed in Northern Morocco despite the geomorphological, geological and climatic resemblance between the two regions. In this paper we analyze the mechanisms and processes controlling the Tamegaret slow-moving deep-seated landslide (Northern Morocco) in order to bridge this knowledge gap and to understand landslide slope dynamics on their regional context. To do so, Electrical resistivity Tomography , field investigations and multi-temporal Synthetic Aperture Radar Interferometry (InSAR) were performed to characterize slope instability processes at the study area. The interpretation of Historic aerial photographs and UAV surveys was also conducted to study the major redistribution of mass caused by recent road widening work at the landslide headscarp. Results show that the Tamegaret landslide owes its existence to deep creep processes controlled by a rock flow type gravitational deformation. Extensional tectonic structures and marine erosion processes that eliminate landslide deposits from the foot area constitute the most relevant control factors of this dynamic. InSAR results show that this deep-seated landslide is currently (2017–2019) characterized by very slow displacement rates (2–3 cm/year maximum). Yet, the substantial deformation observed both in the field and on aerial/satellite photographs suggests that the acceleration occurred during the road-widening work which caused major changes to the natural topography in the period (2009–2012). This deformation phase was manifested by local shoreline advancement at the landslide foot area. Such results show that studying historic shoreline variations can be an effective low-cost time-saving tool allowing the reconstruction of active landslide kinematics in coastal areas. On a regional scale, findings of this study highlight the resemblance between the coasts of Southern Spain and Northern Morocco in terms of (i) the geomorphological processes controlling the coastal slope dynamics at the region; (ii) the displacement rates measured in Tamegaret compared to other unstable slopes in the Northern shore of the Alboran Sea and (iii) the bad-engineering on old dormant landslides which compromises their stability. Therefore, we suggest limiting construction work on coastal hillslopes of Northern Morocco in order to prevent bad construction practices from causing economic losses in the Southern shoreline of the Alboran Sea as well.
Landslide susceptibility indices were calculated and landslide susceptibility maps were generated... more Landslide susceptibility indices were calculated and landslide susceptibility maps were generated for the Oudka, Morocco, study area using a geographic information system. The spatial database included current landslide location, topography, soil, hydrology, and lithology, and the eight factors related to landslides (elevation, slope, aspect, distance to streams, distance to roads, distance to faults, lithology, and Normalized Difference Vegetation Index [NDVI]) were calculated or extracted. Logistic regression (LR), multivariate adaptive regression spline (MARSpline), and Artificial Neural Networks (ANN) were the methods used in this study to generate landslide susceptibility indices. Before the calculation, the study area was randomly divided into two parts, the first for the establishment of the model and the second for its validation. The results of the landslide susceptibility analysis were verified using success and prediction rates. The MARSpline model gave a higher success r...
El objetivo del proyecto es la mejora del aprendizaje de la asignatura Mecánica del Suelo y Rocas... more El objetivo del proyecto es la mejora del aprendizaje de la asignatura Mecánica del Suelo y Rocas. Geotecnia de 2º curso del Grado en Ingeniería Civil mediante la resolución de problemas y el uso de las NTIC. Se han realizado las siguientes tareas: 1. Revisión de información y formación, 2. Selección de un conjunto representativo de problemas demostrativos y de evaluación sobre fundamentos de Mecánica del Suelo y Rocas. Geotecnia. 3. Adaptación del material docente al espacio web. El resultado es una página web con material didáctico que facilite el aprendizaje autónomo y la autoevaluación mediante la resolución de problemas.
ABSTRACT estabilidad. Los datos del análisis reflejan que el 15% de la zona estudiada muestra una... more ABSTRACT estabilidad. Los datos del análisis reflejan que el 15% de la zona estudiada muestra una susceptibilidad a los movimientos de moderada a muy alta que, a su vez, coincide con lugares donde se encuentran la mayoría de las infraestructuras públicas de la región. Además, los valores registrados en la validación mediante el grado de ajuste están por encima del 83% para las zonas de susceptibilidad alta y muy alta.
ABSTRACT This paper presents a new, fast and economical method for digitizing a rock surface prof... more ABSTRACT This paper presents a new, fast and economical method for digitizing a rock surface profile to determine its joint roughness coefficient (JRC) value (Barton and Choubey, Rock Mech Rock Eng 10:1–54, 1977) using a set of existing parameters, the appropriateness of which has been tested. The new procedure was applied to four rock road cuts in the Alpujarra area of Granada province (Andalusia, Spain), supported by 117 digitized profiles. The method avoids any personal subjectivity bias. The usual subjectivity in the visualization and assessment of the JRC value is estimated here by a survey test answered by 90 trained users. The survey test consisted of a set of JRC visual comparisons of 12 roughness profiles, selected from the 117 profiles surveyed during the field research in the Alpujarra region, with the Barton typical profiles. The results of the survey clearly show systematic inaccuracies in the traditional procedure that are reduced if the advice presented in the conclusions of this paper is taken in account when performing the visual estimation.
In order to characterise the influence of the heavyrains on the observed landslides during the 19... more In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations,
Rockfall simulations constitute the first step toward hazard assessments and can guide future roc... more Rockfall simulations constitute the first step toward hazard assessments and can guide future rockfall prevention efforts. In this work, we assess the impact of digital elevation model (DEM) resolution on the accuracy of numerical rockfall simulation outputs. For this purpose, we compared the simulation output obtained using 1 m, 2 m and 3 m resolution UAV-derived DEMs, to two other models based on coarser topographic data (a 5 m resolution DEM obtained through interpolating elevation contours and the Shuttle Radar Topographic Mission 30m DEM). To generate the validation data, we conducted field surveys in order to map the real trajectories of three boulders that were detached during a rockfall event that occurred on 1 December 2018. Our findings suggest that the use of low to medium-resolution DEMs translated into large errors in the shape of the simulated trajectories as well as the computed runout distances, which appeared to be exaggerated by such models. The geometry of the run...
This research tests the application of GNSS and RPAS techniques to the spatiotemporal analysis of... more This research tests the application of GNSS and RPAS techniques to the spatiotemporal analysis of landslide dynamics. Our method began by establishing non-permanent GNSS networks on the slope surfaces to perform periodic measurements by differential GNSS. Similarly, RPAS flights were made to acquire high-resolution images, which were oriented and georeferenced using ground control points and structure-from-motion algorithms to ultimately obtain digital surface models and orthophotos. Based on GNSS measurements, the direction and velocity of displacements were accurately calculated, and orthophotos and DSMs were used to calculate horizontal and vertical displacements in a set of significant points throughout the study area, reaching accuracies higher than 0.035 m in the GNSS data and 0.10 m in the RPAS data. These values were within the accuracy required for such studies. Based on the field observations and the results from the photogrammetric studies, the two studied landslides were...
The Eastern coast of the Granada Province, modelled on Alpujarrides metapelitic rocks, has been v... more The Eastern coast of the Granada Province, modelled on Alpujarrides metapelitic rocks, has been very frequently affected by landslides, usually triggered by a combination of rainfall and anthropic actions. Its relief includes instable zones and old landslides of variable size and unknown age. In the seventies, great residential resorts were damaged in Punta de la Mona and Velilla (Almuñécar), and then roadworks for widening the National Road 340, induced slope failures affecting new residential areas along the road in the municipalities of Salobreña and Almuñécar. More recently, from the late nineties, a great residential complex built up on Cerro Gordo (La Herradura, Almuñécar), is heavily affected since 2005 by widespread damages; its construction involved excavations and fillings, frequently performed too quickly, and lacking of adequate drainage and stabilization treatments. Rainfall and the leaks by breakage of water supply and sanitation networks are the main triggering factor...
Landslide susceptibility maps (LSMs) rely on statistical association for weighting the impact of ... more Landslide susceptibility maps (LSMs) rely on statistical association for weighting the impact of each predictive factor class. However, the effects of using different training datasets and causative factors combinations on the accuracy of the results are rarely discussed. Accordingly, we investigated the effects of training data and computation technique selection on the accuracy and performance of LSMs. Results show that including relict landslides in the training data diminishes the accuracy of the LSMs compared to models that exclude such processes from the input. As for the effect of choosing different combinations of predictive variables, it was shown to be less significant. After investigating association and causality between predictive variables, the best performing models produced using frequency ratio and logistic regression tend to be more accurate than those including all variables. As for the artificial neural networks, it seems to outperform other models. Indeed, such investigations are beneficial for improving LSMs.
espanolLa costa oriental de la provincia de Granada, modelada sobre rocas metapeliticas Alpujarri... more espanolLa costa oriental de la provincia de Granada, modelada sobre rocas metapeliticas Alpujarrides ha sido afectada frecuentemente por movimientos de ladera, activados por una combinacion de lluvias y accion antropica. Su relieve incorpora zonas inestables y deslizamientos antiguos de tamano variable y edad indeterminada. En los anos setenta, quedaron danados grandes complejos residenciales en Punta de la Mona y Velilla (Almunecar) y despues las obras de ampliacion de la carretera C.N. 340, indujeron roturas de laderas que afectaron a las nuevas urbanizaciones construidas a lo largo de la carretera en los terminos de Salobrena y Almunecar. Mas recientemente, a partir de finales de los noventa, se construyo en Cerro Gordo (La Herradura, Almunecar), un gran complejo residencial, que desde 2005, se ve afectado por danos generalizados; su construccion implico excavaciones y rellenos, practicados frecuentemente con demasiada rapidez, y por lo tanto carecieron de tratamientos de drenaje...
Abstract. This research tests the application of GNSS and RPAS techniques to the spatiotemporal a... more Abstract. This research tests the application of GNSS and RPAS techniques to the spatiotemporal analysis of landslide dynamics. Our method began by establishing non-permanent GNSS networks on the slope surfaces to perform periodic measurements by differential GNSS. Similarly, RPAS flights were made to acquire high-resolution images, which were oriented and georeferenced using ground control points and structure-from-motion algorithms to obtain digital surface models and orthophotos ultimately. Based on GNSS measurements, the direction and velocity of displacements were accurately calculated, and orthophotos and DSMs were used to calculate horizontal and vertical displacements in a set of significant points throughout the study area, reaching accuracies higher than 0.035 m in the GNSS data and 0.10 m in the RPAS data. These values were within the accuracy required for such studies. Based on the field observations and the results from the photogrammetric studies, the two studied lands...
Abstract Coastal landslides cause great economic damage to human installations along the Mediterr... more Abstract Coastal landslides cause great economic damage to human installations along the Mediterranean shoreline . In the Alboran Sea, this phenomenon is very common and causes many problems for residential resorts and road infrastructures in coastal areas. In the last two decades, such slope instability processes were the subject of many studies, which employed multidisciplinary approaches to understand their underlying mechanisms and surficial kinematics in Southern Spain and elsewhere in the Mediterranean. However, advanced and new investigation methods and techniques used in these studies have never been performed in Northern Morocco despite the geomorphological, geological and climatic resemblance between the two regions. In this paper we analyze the mechanisms and processes controlling the Tamegaret slow-moving deep-seated landslide (Northern Morocco) in order to bridge this knowledge gap and to understand landslide slope dynamics on their regional context. To do so, Electrical resistivity Tomography , field investigations and multi-temporal Synthetic Aperture Radar Interferometry (InSAR) were performed to characterize slope instability processes at the study area. The interpretation of Historic aerial photographs and UAV surveys was also conducted to study the major redistribution of mass caused by recent road widening work at the landslide headscarp. Results show that the Tamegaret landslide owes its existence to deep creep processes controlled by a rock flow type gravitational deformation. Extensional tectonic structures and marine erosion processes that eliminate landslide deposits from the foot area constitute the most relevant control factors of this dynamic. InSAR results show that this deep-seated landslide is currently (2017–2019) characterized by very slow displacement rates (2–3 cm/year maximum). Yet, the substantial deformation observed both in the field and on aerial/satellite photographs suggests that the acceleration occurred during the road-widening work which caused major changes to the natural topography in the period (2009–2012). This deformation phase was manifested by local shoreline advancement at the landslide foot area. Such results show that studying historic shoreline variations can be an effective low-cost time-saving tool allowing the reconstruction of active landslide kinematics in coastal areas. On a regional scale, findings of this study highlight the resemblance between the coasts of Southern Spain and Northern Morocco in terms of (i) the geomorphological processes controlling the coastal slope dynamics at the region; (ii) the displacement rates measured in Tamegaret compared to other unstable slopes in the Northern shore of the Alboran Sea and (iii) the bad-engineering on old dormant landslides which compromises their stability. Therefore, we suggest limiting construction work on coastal hillslopes of Northern Morocco in order to prevent bad construction practices from causing economic losses in the Southern shoreline of the Alboran Sea as well.
Landslide susceptibility indices were calculated and landslide susceptibility maps were generated... more Landslide susceptibility indices were calculated and landslide susceptibility maps were generated for the Oudka, Morocco, study area using a geographic information system. The spatial database included current landslide location, topography, soil, hydrology, and lithology, and the eight factors related to landslides (elevation, slope, aspect, distance to streams, distance to roads, distance to faults, lithology, and Normalized Difference Vegetation Index [NDVI]) were calculated or extracted. Logistic regression (LR), multivariate adaptive regression spline (MARSpline), and Artificial Neural Networks (ANN) were the methods used in this study to generate landslide susceptibility indices. Before the calculation, the study area was randomly divided into two parts, the first for the establishment of the model and the second for its validation. The results of the landslide susceptibility analysis were verified using success and prediction rates. The MARSpline model gave a higher success r...
El objetivo del proyecto es la mejora del aprendizaje de la asignatura Mecánica del Suelo y Rocas... more El objetivo del proyecto es la mejora del aprendizaje de la asignatura Mecánica del Suelo y Rocas. Geotecnia de 2º curso del Grado en Ingeniería Civil mediante la resolución de problemas y el uso de las NTIC. Se han realizado las siguientes tareas: 1. Revisión de información y formación, 2. Selección de un conjunto representativo de problemas demostrativos y de evaluación sobre fundamentos de Mecánica del Suelo y Rocas. Geotecnia. 3. Adaptación del material docente al espacio web. El resultado es una página web con material didáctico que facilite el aprendizaje autónomo y la autoevaluación mediante la resolución de problemas.
ABSTRACT estabilidad. Los datos del análisis reflejan que el 15% de la zona estudiada muestra una... more ABSTRACT estabilidad. Los datos del análisis reflejan que el 15% de la zona estudiada muestra una susceptibilidad a los movimientos de moderada a muy alta que, a su vez, coincide con lugares donde se encuentran la mayoría de las infraestructuras públicas de la región. Además, los valores registrados en la validación mediante el grado de ajuste están por encima del 83% para las zonas de susceptibilidad alta y muy alta.
ABSTRACT This paper presents a new, fast and economical method for digitizing a rock surface prof... more ABSTRACT This paper presents a new, fast and economical method for digitizing a rock surface profile to determine its joint roughness coefficient (JRC) value (Barton and Choubey, Rock Mech Rock Eng 10:1–54, 1977) using a set of existing parameters, the appropriateness of which has been tested. The new procedure was applied to four rock road cuts in the Alpujarra area of Granada province (Andalusia, Spain), supported by 117 digitized profiles. The method avoids any personal subjectivity bias. The usual subjectivity in the visualization and assessment of the JRC value is estimated here by a survey test answered by 90 trained users. The survey test consisted of a set of JRC visual comparisons of 12 roughness profiles, selected from the 117 profiles surveyed during the field research in the Alpujarra region, with the Barton typical profiles. The results of the survey clearly show systematic inaccuracies in the traditional procedure that are reduced if the advice presented in the conclusions of this paper is taken in account when performing the visual estimation.
In order to characterise the influence of the heavyrains on the observed landslides during the 19... more In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations,
Uploads