The contribution of geomorphological mapping to sediment transfer evaluation in small alpine catchments

The assessment of sediment transfer processes is necessary to understand the hydro-geomorphological functioning of small alpine watersheds prone to channelised debris flows because their occurrence often depends on the amount of debris available in the gully systems. Therefore, sediment budgets should be studied through the identification of erosion, transport and deposition processes. Sediment transfer processes were investigated in a small catchment by field measurements and, more specifically, through the application of a process-based geomorphological mapping method. The proposed methodology is based on data directly derived from GIS analysis using high-resolution DEM, field measurements and aerial photograph interpretations. It has been conceived to estimate sediment transfer dynamics, taking into account the role of different sediment stores in the torrential system. The proposed geomorphological mapping methodology is quite innovative in comparison with most legend systems that are not adequate for mapping comprehensively active and complex geomorphological systems such as debris-flow catchments. Maps representing the various sediment storages and their relationships can be used for hydro-geomorphological hazard mitigation.