Author(s): Dominique Laigle
Linked Author(s): Dominique Laigle
Keywords: Debris-flows; Mudflows; Torrents; Hydraulics; Numerical Modeling; Natural Hazards; Rheology; Risk Assessment
Abstract: The Pousset torrent is a tributary of the Arc river in the Maurienne valley (Savoie, France). This torrent has produced frequent and large debris-flow events for a long time and many historical events are referenced. Concerning debris-flow triggering, the main active mechanisms are bed erosion and bank failures which can build temporary dams that afterwards collapse under the action of water. This torrent produces essentially muddy debris-flows for which a theoretical approach and numerical tools have been previouly developed. Risk analysis in general and mapping of debris-flow induced risk in particular are difficult tasks. Defining a unique reference flood is often impossible and working on the basis of scenarios often appears as a fruitful and at least promising methodology of investigation. Thus, it is proposed to take advantage of existing numerical tools for a practical estimation of risk on the Pousset torrent. Numerical tools are shortly presented. Attention is focused on interactions between a one-dimensional model computing channelized flows and a two-dimensional model computing the spreading of material. Main assumptions are discussed. Different methods enabling the definition of possible flood scenarios (debris-flow volume, discharge and rheological parameters) are presented. The use of existing numerical tools on the basis of scenarios is exemplified, leading to estimations of the maximum extent area for a given debris-flow event.
Year: 1999