Debris flow hazard evaluation and mitigation measures in Cortina d'Ampezzo (North-Eastern Italy).

An active debris flow scree seriously threatens the urbanized area of Fiames, near Cortina d'Ampezzo (Dolomites, Italy) and the state road; events up to 30.000 m3 occurred with an almost yearly frequency. Following a 25.000 m3 magnitude debris flow that temporarily dammed the river, a retention basin with a storage capacity of about 15000 m3, was built upstream the state road in 1997. In this study, the effectiveness of the debris basin has been evaluated and new mitigation measures are proposed, regarding to the magnitude of the design debris flow (30000 m3) and the associated hazard and risk.