3D simulation of overtopping erosion on embankments by shallow-water approximation

Recently, the failure of embankments, such as levees and small embankment dams for irrigation reservoirs, has occurred more frequently because of a greater chance of severe typhoons and localized heavy rains. Overflow, a phenomenon in which the water level exceeds the height of the embankments, is known as a primary cause of embankment breaks. The purpose of this study is to develop a numerical method which can predict the breach process of an embankment caused by overflow. This paper presents the three-dimensional numerical analysis of embankment breaching. The finite volume method, with a Riemann solver, is applied to numerically solve shallow water equations for computing the overflow onto the embankments and the changes in configuration of the embankment profiles are successively calculated in accordance with the erosion rates of the embankment materials as a function of the bed shear stress exerted onto the embankment surface. In order to achieve a stable computation, the surface gradient method is incorporated into the finite volume discretization. The proposed method has enabled three dimensional breaching of embankments to be stablely computed.