Modelli idraulici per la ricostruzione dell’evento del Luglio 1987 in Valtellina

The purpose of this paper is to model July 1987 flooding event occurred in Valtellina (central Alps, northern Italy): at that time, a set of meteo-hydrogeological phenomena affected the study area causing huge direct and indirect physical and socio-economic consequences. The methodology proposed in this study combines GIS and CAD systems to model the geometric and structural features of the morphological and anthropic elements and HEC - RAS to model depth and velocity of the flow. A crucial input for the simulations is the Digital Terrain Model (DTM) of the study area at the time of event that was not initially available. So, a complex methodology for its realization has been designed and applied. Then, a sensitivity analysis on the Manning's coefficients was performed in order to obtain the best correspondence between observed and modeled flooded area.