A two-layer model for simulating landslide dam over mobile river beds

Landslides can block mountainous streams and form landslide dams to threaten downstream residents. It is necessary for reliable methods to predict landslide dam dynamic for risk assessment. In this paper, we present a two-layer model of Savage–Hutter type to simulate the dynamic evolution of landslide dam which take account of the erosion of river bed. The two-layer shallow water system is derived by depth-averaging the incompressible Navier–Stokes equations with the hydrostatic assumption integrated of the erosion model of river bed. The effect of excess pore water pressure is considered in the erosion process. A high order accuracy scheme based on Roe-type solver is used to discretize the present model. Finally, several numerical tests are performed to verify the stability of the algorithm and reliability of the model. Numerical results indicate that the erosion effect enhances the huge destructiveness of landslide and increase the possibility of river blocked by landslides. The impact of excess pore water pressure on erosion process should be considered.