Modeling debris flow propagation and deposition

A mathematical model is applied to simulate two debris flows occurred in 19 97 and 1998 in Italian Alpine valleys. The flows caused a casualty and sign ificant damages to buildings and roads. The model considers a two-phase mix ture of coarse sediments and interstitial fluid. The concentration of the f iner solid fraction in the interstitial fluid is assumed to be negligible, so that this fluid acts as clean water. Assuming that the solids and the in terstitial fluid move downstream with the same velocity, the flow of the mi xture is described using a two dimensional depth averaged model with a uniq ue 2D momentum equation and two mass balance equations for the mixture and the sediments, respectively. Erosion and deposition rates are computed with a modified version of the relationship developed by Egashira-Ashida. Diffe rential equations are integrated with art upwind explicit finite-difference scheme. The total discharge hydrograph at the upstream sections of the all uvial fans was estimated by assuming equilibrium solid concentration values . (C) 2001 Elsevier Science Ltd. All rights reserved.