Torrential activity facing global change in Southern French Alps
Résumé
In mountainous areas, especially in large river catchments with torrential tributaries, the sediment supply significantly increases the flood impacts in the valley bottoms. Within the framework of the SAMCO (ANR) project, dealing with the potential impacts of global changes (climate, ecosystem e.g. land use, socioeconomic system) on mountain hazards, we aim to a better understanding of Alpine river systems through the analysis of the sediment budgets. For estimating these budgets it implies the analysis of geomorphic processes contribution in the sediment production and transfers, and the identification of different sources, pathways and sinks. In the study area (Guil catchment, Southwest France), remobilisation of sediment accumulated in hillslope storage are largely determined by geomorphic extreme events (debris flow, shallow landslides, runoff). The contribution of these processes in sediment delivery to channel is the main objective of this poster. We propose a compartment analysis modelling in order to quantifying sediments fluxes and stores using system dynamics modelling. Our study aims at analysing the temporal composition of sediment cascade in the Peynin sub-catchement which highly contributes to sediment budget of the Guil river catchment. The initial phase of our study consists in identifying sediment sources and storage through geomorphological analysis and mapping. Then a conceptual model of the cascade can be generated (Schrott et al., 2003, Heckmann et al., 2008). Then we provide a stock & flow modeling based on System Dynamics to modelize sedimentary signals through time considering processes and storages interactions or connections.
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