A multi-purpose, intra-wave, shallow water hydro-morphodynamic solver

A hydro-morphodynamic numerical model is illustrated as a novel contribution to the investigation and prediction of nearshore and riverine flows and seabed changes forced by waves and currents. The model includes a robust hydrodynamic solver for the integration of the nonlinear shallow water equations (NSWE) and a rather flexible solver for the resolution of the Exner equation (used to evaluate the morphological evolution of the seabed). A detailed analysis is given of existing and novel procedures for the solution of the morphodynamic problem. Coupling of NSWE and Exner equations and updating of the solution is made by means of a sequential splitting scheme. The model has been validated by reproducing both analytical and numerical solutions, available in the recent literature, as well as an in-house laboratory experiment. The simulation of existing theoretical solutions has revealed the model performs well, especially in the prediction of the seabed evolution due to either bed-load or suspended-load transport forced by dam-break and swash-type events. The latter ones are seen to force both erosion and accretion despite the weak hydro-morphodynamic coupling. The comparison between solver results and experimental data is also encouraging, the solver reproducing well the main seabed features forced by irregular waves.