Mud and debris flows are natural phenomena representing serious hazard for population and structures in mountain zones, because of their rapid occurrence and the diffi culty in forecasting the phenomena initiation. Numerical models can however be useful in predicting the peak discharge and the strength of flowing mass, helping administrations in preparing risk mitigation measures. In this work, a numerical model for hyperconcentrated flows is presented. It is based on shallow water equations, with a particular source terms treatment which translates into an increased numerical stability and makes the model highly versatile. The test case applications focus on some fundamental characteristics necessary for debris- and mud-flow representation. In particular, classic dam-break problems have been used to test wave celerity and wet-dry fronts propagation, while a mud-flow dam-break problem has been chosen to investigate model sensibility to different rheological schemes. Then, the model has been applied to two real events that occurred in Northern Italy. The first one is a debris flow which took place at Acquabona, near Cortina d’Ampezzo. This event is extensively documented, since it has been observed by a monitoring station prepared by the University of Padua. The second one is a tragic event, during which the little town of Stava has been stricken by a destructive mud flow caused by the collapse of two earth dams.
debris flow, mud flow, numerical simulation, source terms
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