Operative approaches for debris flow modelling and hazard assessment, Laures watershed, Valle d'Aosta, Italy

Abstract

Here is presented a comparative application of different simple methods for preliminary hazard mapping in debris flow prone areas. The analysis is carried out in the Laures fan, a 17.2 km2 basin in the Western Italian Alps. The applied methods support increasing complexities, starting from the use of a simplified hydraulic approach for the identification of the critical cross-sections and the overflow volume to the use of a 2-D model that provides a hazard map from the overlay of maximum flow thickness and velocity maps. If integrated with a deep knowledge of the fan area, the first approach allows a reasonable preliminary debris flow hazard mapping. The use of a 2-D hydrodynamic model is recommended if inhabited area or important communications are located in the fan, thus a more accurate hazard mapping is required.