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Discontinuity interpretation and identification of potential rockfalls for high-steep slopes based on UAV nap-of-the-object photogrammetry / Wei Wang in Computers & geosciences, vol 166 (September 2022)  

Public [article]  inComputers & geosciences > vol 166 (September 2022) . - n° 105191 Titre : Discontinuity interpretation and identification of potential rockfalls for high-steep slopes based on UAV nap-of-the-object photogrammetry Type de document : Article/Communication Auteurs : Wei Wang ; Wenbo Zhao, Auteur ; Bo Chai, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 105191 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] Chine [Termes IGN] discontinuité [Termes IGN] éboulement [Termes IGN] extraction de données [Termes IGN] front rocheux [Termes IGN] image à haute résolution [Termes IGN] image captée par drone [Termes IGN] matrice [Termes IGN] pente [Termes IGN] photogrammétrie aérienne [Termes IGN] profondeur [Termes IGN] risque naturel [Termes IGN] semis de points [Termes IGN] texture d'image Résumé : (auteur) Discontinuity extraction and interpretation of fractured masses is of high importance when analyzing rock slope stability. Regarding high-steep slopes, which are areas that are difficult to reach, traditional methods to obtain discontinuities, such as the sample window method (SWM), are unlikely to be implemented, resulting in challenges for the identification of potential rockfalls. With the development of the unmanned ariel vehicle (UAV) technology, discontinuity extraction can overcome by noncontact photogrammetry. However, there is still a lack of comprehensive and practical solutions to fulfill rockfall identification from field investigation to in-door analysis. For this purpose, a practical case study was carried out in Wanzhou, Chongqing, China, where a 400 m vertical rock slope prone to rockfall was collected as a typical example. The centimeter-level 3D Textured Digital Outcrop Model (TDOM) and dense Point Cloud (PC) were established using high-resolution photos acquired by nap-of-the-object photogrammetry. The discontinuity of the fractured mass was interpreted by fully taking advantage of both 2D images (texture information-dominated) and 3D PCs (depth information-dominated). Furthermore, a new parameter rock cavity rate (RCR) and the corresponding semiautomatic extraction method based on point clouds are proposed. Subsequently, the possibility of various failure modes and their joint combinations were determined by kinematic analysis. Finally, the rock slope stability was determined using a matrix that considers the slope mass rating (SMR) value and the parameter RCR. The proposed process flow and relevant techniques in this study provide an operable and practical solution for further application regarding discontinuity interpretation and potential rockfall identification on high-steep slopes. Numéro de notice : A2022-655 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1016/j.cageo.2022.105191 Date de publication en ligne : 08/07/2022 En ligne : https://doi.org/10.1016/j.cageo.2022.105191 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101504 [article]

Multi-method monitoring of rockfall activity along the classic route up Mont Blanc (4809 m a.s.l.) to encourage adaptation by mountaineers / Jacques Mourey in Natural Hazards and Earth System Sciences, vol 22 n° 2 (February 2022)  

Public [article]  inNatural Hazards and Earth System Sciences > vol 22 n° 2 (February 2022) . - pp 445 - 460 Titre : Multi-method monitoring of rockfall activity along the classic route up Mont Blanc (4809 m a.s.l.) to encourage adaptation by mountaineers Type de document : Article/Communication Auteurs : Jacques Mourey, Auteur ; Pascal Lacroix, Auteur ; Pierre-Allain Duvillard, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : pp 445 - 460 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] capteur actif [Termes IGN] capteur non-imageur [Termes IGN] carte thématique [Termes IGN] détection de changement [Termes IGN] éboulement [Termes IGN] modèle numérique de terrain [Termes IGN] Mont-Blanc, massif du [Termes IGN] onde sismique [Termes IGN] pergélisol [Termes IGN] prévention des risques [Termes IGN] risque naturel [Termes IGN] saison [Termes IGN] sismologie [Termes IGN] surveillance géologique [Termes IGN] température de l'air Résumé : (auteur) There are on average 35 fatal mountaineering accidents per summer in France. On average, since 1990, 3.7 of them have occurred every summer in the Grand Couloir du Goûter, on the classic route up Mont Blanc (4809 m a.s.l.). Rockfall is one of the main factors that explain this high accident rate and contribute to making it one of the most accident-prone areas in the Alps for mountaineers. In this particular context, the objective of this study is to document the rockfall activity and its triggering factors in the Grand Couloir du Goûter in order to disseminate the results to mountaineers and favour their adaptation to the local rockfall hazard. Using a multi-method monitoring system (five seismic sensors, an automatic digital camera, three rock subsurface temperature sensors, a traffic sensor, a high-resolution topographical survey, two weather stations and a rain gauge), we acquired a continuous database on rockfalls during a period of 68 d in 2019 and some of their potential triggering factors (precipitation, ground and air temperatures, snow cover, frequentation by climbers). At the seasonal scale, our results confirm previous studies showing that rockfalls are most frequent during the snowmelt period in permafrost-affected rockwalls. Furthermore, the unprecedented time precision and completeness of our rockfall database at high elevation thanks to seismic sensors allowed us to investigate the factors triggering rockfalls. We found a clear correlation between rockfall frequency and air temperature, with a 2 h delay between peak air temperature and peak rockfall activity. A small number of rockfalls seem to be triggered by mountaineers. Our data set shows that climbers are not aware of the variations in rockfall frequency and/or cannot/will not adapt their behaviour to this hazard. These results should help to define an adaptation strategy for climbers. Therefore, we disseminated our results within the mountaineering community thanks to the full integration of our results into the management of the route by local actors. Knowledge built during this experiment has already been used for the definition and implementation of management measures for the attendance in summer 2020. Numéro de notice : A2022-181 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : 10.5194/nhess-22-445-2022 En ligne : https://doi.org/10.5194/nhess-22-445-2022 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99859 [article]

Shining light on danger / Anonyme in GEO: Geoconnexion international, Vol 20 n° 5 (Autumn 2021)

Public [article]  inGEO: Geoconnexion international > Vol 20 n° 5 (Autumn 2021) . - pp 41 - 42 Titre : Shining light on danger Type de document : Article/Communication Auteurs : Anonyme, Auteur Année de publication : 2021 Article en page(s) : pp 41 - 42 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] Alpes [Termes IGN] Bavière (Allemagne) [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] éboulement [Termes IGN] glacier Résumé : (éditeur) A project at the University of Bayreuth is using laser scanners to support rockfall detection in the Alps, as glaciers retreat. Numéro de notice : A2021-905 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99255 [article]

A quantitative assessment of rockfall influence on forest structure in the Swiss Alps / Christine Moos in European Journal of Forest Research, vol 140 n° 1 (February 2021)  

Public [article]  inEuropean Journal of Forest Research > vol 140 n° 1 (February 2021) . - pp 91 - 104 Titre : A quantitative assessment of rockfall influence on forest structure in the Swiss Alps Type de document : Article/Communication Auteurs : Christine Moos, Auteur ; Nora Khelidj, Auteur ; Antoine Guisan, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : pp 91 - 104 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation [Termes IGN] Alpes [Termes IGN] croissance végétale [Termes IGN] diamètre à hauteur de poitrine [Termes IGN] dynamique de la végétation [Termes IGN] éboulement [Termes IGN] modèle de simulation [Termes IGN] structure d'un peuplement forestier [Termes IGN] Suisse Résumé : (auteur) Forests below rocky cliffs often play a very important role in protecting settlements against rockfall. The structure and development of these forests are expected to be substantially affected by the disturbance of the falling rocks. Knowing about this effect is important to predict the development of protection forests and consider potential effects of the falling blocks in management strategies. The goal of this study is to quantify differences in forest structure depending on rockfall activity in four different sites in the Swiss Alps. For this, we collected data on forest structure in zones of different rockfall activity and derived rockfall impact probabilities based on rockfall simulations. We assessed whether differences in forest structure and signs of rockfall disturbance could be observed between the rockfall zones. We additionally built mixed-effects models to identify the key variables explaining the forest characteristics described by diameter (DBH) and basal area (bA). The forest structure differs between the rockfall zones, however, with varying effects amongst the sites. DBH tends to decrease with increasing rockfall activity, whereas tree density appears to be little impacted by rockfall. For most sites, the number of deposited blocks and the simulated tree impact probability have a significant effect in the models along with the species, whereas for one site, hardly any effect of rockfall was found. Our results, obtained either from direct measurements or modelling, show that rockfall can locally influence the structure of forests, whereas the influence depends on the frequency and intensity of the rockfall disturbance. Impact probabilities obtained by simulations can serve as a good proxy for rockfall disturbances. Numéro de notice : A2021-256 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10342-020-01317-0 Date de publication en ligne : 18/09/2020 En ligne : https://doi.org/10.1007/s10342-020-01317-0 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97290 [article]

Rockfalls multi-methods detection and characterization / Gaëlle Le Roy (2020)  

Public Titre : Rockfalls multi-methods detection and characterization Type de document : Thèse/HDR Auteurs : Gaëlle Le Roy, Auteur ; David Amitrano, Directeur de thèse ; Agnès Helmstetter, Directeur de thèse Editeur : Grenoble [France] : Université Grenoble Alpes Année de publication : 2020 Importance : 186 p. Format : 21 x 30 cm Note générale : bibliographie Thèse pour obtenir le grade de Docteur de l'Université de Grenoble Alpes Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] Chartreuse, massif de la (Préalpes ; France) [Termes IGN] éboulement [Termes IGN] fréquence [Termes IGN] modèle numérique de surface [Termes IGN] modèle numérique de terrain [Termes IGN] pente [Termes IGN] photogrammétrie numérique [Termes IGN] roche [Termes IGN] sismologie [Termes IGN] surveillance géologique Résumé : (auteur) Amongst mass wasting events, rockfalls remain the most unpredictable and the most frequent hazard in the alpine region. In a context of growing urbanization in mountainous regions, rockfalls represent an increasing risk for local communities and infrastructures. This thesis aims to develop an association of relevant methods for rockfall monitoring. One objective of this thesis is to associate topography measurement and seismological monitoring in order to improve significantly in understanding rockfalls dynamics. This work was mainly carried out in the Chartreuse massif (Isère, French Alps), and in particular two cliffs, Mount Saint-Eynard and Mount Granier. Using photogrammetry, we acquired diachronic Digital Elevation Models (DEMs) of the cliffs. Such monitoring enables us to carry out rockfall inventories and occurrence frequency analysis. It also provides us information on rockfall locations and their structural configurations. Combining DEMs and rockfall seismic monitoring allowed us to study relations between rockfall properties (location, volume, geometry, propagation, etc.) and the induced seismic signal. Characteristics of the seismic signal (duration and energy, frequency content, envelope shape) vary depending on the event propagation mode (mass-flow, free-fall, sliding, bouncing …). Selecting events with the same propagation type provides a more accurate characterization of rockfalls properties than when mixing different types of events. For free-falling rockfalls, we analyze the seismic signal of the detachment phases and first impacts. We found relations between seismic signals parameters and rockfalls potential energy, free-fall heights, and volumes. For mass-flow type events, we found a scaling law between rockfalls seismic energy and their volumes. By coupling DEMs and seismic records, we can reconstruct rockfall sequence with accurate timing and correct volume estimations. Controlled block releases were realized in laboratory and on-site to widen our observations on rockfall events. Note de contenu : 1- Slopes dynamics and weathering 2- Rockfall hazard in the Alps 3- Rockfall monitoring techniques 4- Methodological biases on rockfall inventories and empirical volume distributions 5- Morpho-structural analysis of rockfalls 6- Seismic analysis of free-falling rockfalls 7- Controlled block release experiment of free fall type events 8- Controlled block release experiment of free fall type events 9- Thermography of block impacts 10- Development outlook Numéro de notice : 25998 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Thèse française Note de thèse : Thèse de Doctorat : Terre Solide : Université Grenoble Alpes : 2020 Organisme de stage : Laboratoire Institut des Sciences de la Terre nature-HAL : Thèse DOI : sans En ligne : https://tel.archives-ouvertes.fr/tel-02921764/document Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96892

Test du potentiel de l’imagerie satellite haute résolution pour le suivi des mouvements gravitaires des falaises crayeuses de Seine-Maritime / Zoé Stroebele (2020) 

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Méthode de comparaison de nuages de points acquis par scanner laser mobile pour caractériser les éboulements des falaises côtières / Baptiste Feldmann in XYZ, n° 156 (septembre - novembre 2018)

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Littoral, "Ricochet" ausculte / Marielle Mayo in Géomètre, n° 2155 (février 2018)

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The protective effect of forests against rockfalls across the French Alps: Influence of forest diversity / S. Dupire in Forest ecology and management, vol 382 (15 December 2016)  

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Prise en compte des forêts à fonction de protection dans les cartographies réglementaires de prévention des risques naturels : Tour d’horizon européen et recommandations pour la France / Jérôme Liévois in Rendez-vous techniques, n° 51-52 (printemps - été 2016) 

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Spatial analysis of coastal chalk cliff falls in upper Normandy (France). From Veules-les-Roses to Le Treport (2002-2009) / Pauline Letortu in Revue internationale de géomatique, vol 24 n° 3 (septembre - novembre 2014)  

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Change detection and deformation analysis in point clouds: Application to rock face monitoring / Marco Scaioni in Photogrammetric Engineering & Remote Sensing, PERS, vol 79 n° 5 (May 2013)  

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Digital terrain model resolution and its influence on estimating the extent of rockfall areas / T. Zieher in Transactions in GIS, vol 16 n° 5 (October 2012)  

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Analysis of importance of road networks exposed to natural hazards / Jean-Marc Tacnet (2012) 

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SIG et LiDAR pour la réalisation de plans de prévention du risque de chute de blocs : Application dans les alpes françaises / Nicolas Clouet in Géomatique expert, n° 82 (01/09/2011)

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