Improving flash flood risk assessment using a simple approach for extreme rainfall scaling and storms transposition

Flash flood risk management is among the key topics of European Flood Directive. Design hydrographs small river basins could underestimate hydraulic in case intense and short-duration events because intensification hourly rainfall design depths uncertainty often ungauged basins. The use synthetic hyetographs obtained from past observed can be useful for a better evaluation flash hazard at basin scale. For this reason, simple approach based on scaling storms transposition occurred presented to identify areas where discharges risk. methodology considers spatial distribution over specific zone areal reduction factors scale different extensions. Hyetographs are used as input hydrological model set located Northern Tuscany (Italy). results show how peak usually greater than floods with an area generally less 30 km2.