Debris-flow propagation on urbanized alluvial fans

The paper discusses the mathematical modeling of real world catastrophic debris flows that occuned in Italy in 1998. Two unsteady, 2-D flow models are used; both are based on a single momentum equation and two distinct continuity equations for the mixture and for the solid phase, respectively. The first model allows for temporal evolution of the bed, and computes erosion and deposition rates; the second model does not simulate erosion and deposition and therefore the bed elevation is constant through time. We found that the first model produced a better correlation with the observed thickness of sediments. Moreover, model results are closer to the observed event if the digital terrain model (DTM) is enhanced using information gained by direct observation of the site and of the debris flow.