Physical and institutional vulnerability assessment method applied in Alpine communities. Preliminary Results of the SAMCO-ANR Project in the Guil Valley (French Southern Alps)

International audience; In the frame of the SAMCO project designed for mountain risk assessment, our goal is to estimate specific form of vulnerability for communities living in the Upper Guil catchment in order to provide useful documentation for a better management of the valley bottom and the implementation of adequate mitigation measures. Here we present preliminary results on three municipalities of the upper Guil catchment: Aiguilles, Abriès, and Ristolas. We propose an empirical semi-quantitative indicator of potential hazards consequences on element at risk (based on GIS) with an application to different (local and regional scale) scales. This indicator, called Potential Damage Index, enable us to describe, quantify, and visualize direct (physical injury, structural and functional damage on buildings, lifelines and land cover) and indirect (socio-economic impacts) consequences. The method allows estimating the possible damage caused by torrential and gravitational hazards by combining weighted indicators (age, state, land use, number of occupied floors, etc.) reflecting the exposure of elements at risk (land cover, buildings, and lifelines) to obtain different maps of total consequences. Besides, this method allows introducing temporality by modifying the weight and the combination of variables. For example, we can operate the distinction between day and night or between the off-season and the touristic season. Another benefit of this method is to permit the visualization of the vulnerability evolution producing diachronic maps. All these maps, combined with adequate hazards map, will contribute to a better assessment of vulnerability in the Queyras and must help the development of better land use and evacuation plans, and thus are important tools for local authorities. This study will be completed by an analysis of social and institutional vulnerability realized on the basis of interview with local councillors and risk perception survey led with the local populations and the tourists.