Modelling and characterizing glacier-bed overdeepenings as sites for potential future lakes in the deglaciating French Alps

Glacier retreat results in major landscape changes including the formation of new lakes in Glacier-Bed Overdeepenings (GBOs) that can provoke catastrophic Glacial Lake Outburst Flood (GLOF) hazards, but could also provide economic opportunities. This study aims to identify and characterize the location of potential GBOs in the French Alps as possible sites for future lakes. We first ran GlabTop (Glacier-bed Topography) and GlabTop2 models, two GIS schemes calculating glacier ice thickness and mapping potential GBOs. Their level of confidence is estimated using morphological analysis based on slope angle, crevasse fields and lateral narrowing at bedrock thresholds. 139 GBOs (>0.01km²) were predicted among which 59 have medium to very high confidence. 20 lakes are already forming at the snout of retreating glaciers, including four lakes at predicted GBOs 0,01 km²) ont été détectés, dont 59 qui ont un niveau de confiance moyen à très élevé. L’approche utilisée est limitée pour les calottes glaciaires, ce qui explique certains faibles niveaux de confiance en Vanoise. 19 lacs se forment déjà au front de certains glaciers, dont deux dans des surcreusements dont la superficie estimée est