Debris Flow Hazard Assessment (Cave del Predil—NE Italy)

Debris flows are one of the most frequent mass movement processes which develop on the mountain river network. With high flow velocity, long run-out, and high impacts, they are one of the most hazardous types of landslide. The material involved is heterometric debris with an extremely heterogeneous grain size distribution. The present research is focused on the interaction between the potential debris flow deposits from Rio Conzen and Canalone Andrea rivers with one of the four settling slag basins created during mining operations in the Cave del Predil mine (Tarvisio, Friuli Venezia Giulia, NE Italy). The mine is historical, the first written record of its existence dates back to 800BC. It remained active for a long period, and was the cause of dispute between the Italians and Austrians during WWI when the Austrians used a tunnel to transport troops and war material. After 1991 when the mine was closed, some levels were partially flooded in order to grant stability to the mine. The latter was later converted into a touristic area that along with the whole Val Canale valley was hit by an extremely intense alluvial event in August 2003 when more than 100 debris flows occurred. The valley is orthogonal to Val Canale where more intense damages occurred, but the possibility of the occurrence of new events (return period of 300y) is still high. The aim of this study was to create a possible scenario of the event, using FLO-2D software. The scenario obtained allow to study the interactions between debris flow deposits and the slag basins, and provide an understanding of the possibility of a river interruption. Scenarios can be considered extremely useful data to assist in informed future territorial planning of the area providing a good indication for hazard definition.