Assessment of debris flow magnitude in small catchments of the lombardy alps: the val gola case study

Debris flows are among the most destructive of all water-related disasters. They mainly affect mountain areas in a wide range of morphoclimatic environments. Therefore, accurate prediction of their run out distances, magnitudes and velocities plays a role of paramount importance, in order to plan and design appropriate structural and non-structural defence measures. In this context, a number of Authors have developed methods feasible to evaluate the tendency of a catchment to generate debris flow, without giving an estimation of the magnitude. Other empirical procedures are based on the analysis of historical series of debris flow, occurred in similar environments, to assess the relationship between the catchment characteristics and the maximum movable debris volumes. In this paper, and with reference to Val Gola—a small catchment in the North-East Lombardy where debris flows frequently occur—a number of methods, belonging to each of the above mentioned categories, have been briefly reviewed and applied in order to evaluate their effectiveness and consistency.