Apport des données de LiDAR terrestre pour le suivi et l'analyse du déplacement d'un glacier rocheux (glacier du Laurichard, Hautes Alpes, France)

Abstract

Rock glaciers are a common landform in mountain areas with few or no glacier, which morphology reflects the deformation of an ice and debris mixture, and which response to climate changes raises many questions. Indeed, in a recent context of observed rock glacier destabilization or even collapse, the flow of the ice-rich permafrost on slope is the subject of various studies and surveys, especially with respect to the natural hazard they might represent. This paper presents the main results of the analysis of two terrestrial LiDAR surveys of the Laurichard rock glacier (French Alps), performed at a one year time lapse (2005-2006). This technique has allowed to acquire, at a sub-decimeter resolution, models of the rock glacier surface, which have been afterward compared together through two complementary approaches, in order i) to extract the small scale topography ; ii) to quantify the inter-annual surface changes ; iii) to determine the main characteristics of the rock glacier flow. The LiDAR-derived datasets were also compared to a digital terrain model of 1975 and to a geodetic data-sets of annual block position.