On the Use of Numerical Models for Flow-like Landslide Simulation

Abstract

In the last years, numerical modelling has emerged as a useful tool for landslide runout analysis and risk assessment. Several of the developed models have included innovations that have significantly advanced both the ability to simulate real events and the understanding of rapid landslide processes. However, it is here evidenced that in both interpreting run-out results and evaluating numerical model performances a particular care is necessary. To this aim, the continuum-mechanics based code RASH3D is used to back-analyse the case of the Baio Dora debris flow. Carried-out analyses are intended to highlight the influence that some factors like (1) Digital Elevation Model (DEM) resolution; (2) rheological law; and (3) entrainment process can have on numerical results. In particular, it is observed that a low resolution DEM can make fail all the attempts of selecting and calibrating the more appropriate rheology. On the other side, the selection of a wrong rheology can give a unrealistic run-out path, that is the moving mass can go as far taking a completely incorrect flowing direction. Finally, it emerges that the entrainment of channel path material can significantly change the mobility of a flow, through rapid changes of both the flow volume and rheology.