Runout modelling and extension of the threatened area associated with muddy debris flows
Résumé
Debris flows are common in mountainous areas comprising clay-shale outcrops. They can cause severe damage to the environment, life and property. A methodology based on a debris flow runout modelling analysis is presented and discussed. Two watersheds of the Bar- celonnette Basin (Southeast French Alps), considered to be prone to debris flows have been investigated and hazard zones on alluvial fans defined. Geomorphological surveys and various geomechanical and rheological
tests were undertaken in order to provide data for calibrating a one-dimensional numerical runout model. Calibration of the model against deposit thickness and runout distance allows simulation of several runout scenarii for different properties of the source material and of the flowing sediment-water mixtures