Analysis of the debris-flow hazard on the Rioulong torrent (Hautes-Pyrénées, France) alluvial fan using a scenario-based approach

Abstract

A method of debris-flow hazard analysis, based on the use of the Cemagref LAVE2D model, within the framework of a scenario-based approach, is applied to the Rioulong torrent. A preliminary analysis of the watershed leads to conclude that some risk of debris-flow occurrence is present and to specify scenarios accordingly. Numerical simulations are carried out based on these scenarios. They make it possible to specify the maximum extension of debris-flows for different probabilities of occurence characterised qualitatively. These simulations also provide some useful information for the design of a protection dam. Finally, they allow an analysis of the maximum extension of debris-flows resulting from the installation of this dam