Development of a numerical model for predicting the effect of defence structures on debris flow

The flow of highly concentrated mixtures of sediment and water, commonly known as debris flow, is an important geomorphologic process in many mountainous watersheds. The debris flow occurs when, because of alluvial events, a large volume of sediments is mobilized forming a sediment flood that spreads downstream along preferential paths. It is characterized by a high mean velocity that can reach the order of tenths of meters per second; finally the debris flow stops where the slope is low enough to cause the separation of water from the solids. The hazards of a debris flow event are due to the extreme rapidity of its development, to the lack of foretelling signs, to the high erosion capacity and to the high mobility of the flow that can cover remarkable distances and can provoke damages in areas very far from the triggering zones.