Depth-Averaged Two-Dimensional Model of Unsteady Flow and Sediment Transport due to Noncohesive Embankment Break/Breaching

AbstractA depth-averaged two-dimensional model has been developed in this study to simulate the unsteady flow and noncohesive sediment transport due to embankment break and overtopping breaching. The model adopts the generalized shallow-water equations that consider the effects of sediment transport and bed change on the flow, thus leading to coupled calculations of these processes. It computes the non-equilibrium total-load sediment transport and considers the noncohesive embankment slope avalanching. The model solves the governing equations using an explicit finite-volume method on a rectangular grid, with the Harten, Lax and van Leer (HLL) approximate Riemann solver to handle the mixed-regime flows generated by embankment break/breaching and the monotonic upstream scheme for conservation laws (MUSCL) piecewise reconstruction method to reach second-order accuracy in space. It uses a varying time step length that satisfies both the Courant-Friedrichs-Lewy condition and the limitation that the bed change ...