Analyse diachronique par photogrammétrie du glacier rocheux Roc Noir en cours de déstabilisation en Vanoise

• Main Author: Obregon Gonzalez, Renée Alejandra
• Other Authors: Université Grenoble Alpes - Institut d'urbanisme et de géographie alpine (IUGA), Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ), Marco Marcer
• Format: Master Thesis
• Language: French
• Published: HAL CCSD 2018
• Subjects: Glaciers rocheux; Télédétection; Déstabilisation de terrain; Photogrammétrie; [SHS.GEO]Humanities and Social Sciences/Geography; permafrost; pergélisol
• Online Access: https://dumas.ccsd.cnrs.fr/dumas-02138875; https://dumas.ccsd.cnrs.fr/dumas-02138875/document; https://dumas.ccsd.cnrs.fr/dumas-02138875/file/memoire_Obregon_Renee_2018.pdf

Inventoried in the French Alps and elsewhere in Europe, rock glaciers and alpine permafrost are being studied the more and more. According to the latest climate projections, it is estimated that the French Alps will be strongly affected by rising temperatures in the coming years. This could lead to an increased destabilization of active rock glaciers and to the unfolding of other risks related to this type of phenomena such as landslides and debris flows. During the last decades, several aerial images were taken on the French territory, which has allowed to carry out remote field analyses with the help of geomatics and remote sensing. In order to better understand the dynamics of destabilized rock glaciers during the last six decades, a study in the field of remote sensing has been carried out. The main objective of this study was to quantify the movement speed qrsztkof the "Roc Noir" rock glacier (in Vanoise) by using photogrammetric tools and aerial imagery processing tools to obtain 3D digital models and orthophotographs. Thus, in order to produce statistical and visual analyses of the site of study. The partial results of this methodology show that the kinematics of the rock glacier Roc Noir have changed a lot since the 1950's. The most important displacements were encountered between 2010 and 2013 followed by those between 2013 and 2017. Thanks to this analysis, it was possible to observe the movement of surface landforms associated with destabilized rock glaciers and to calculate a movement speed ranging from 0.9 meters per year (my-1) to 7.85 my-1 +/- 0.16my-1 on the Roc Noir surface. The downstream central area of the rock glacier showed a faster movement compared to the rest of its body. These figures have not been yet validated with field data; therefore, the reliability of these results is still uncertain. However, the orthophotos are very clear and reflect an accelerated evolution in recent decades. Répertoriés dans les Alpes françaises et ailleurs en Europe, les glaciers rocheux et le pergélisol ...