A Process-Based Unsteady Model for Wave-Current-Morphodynamic Changes in Two-Dimensions

A process-based two-dimensional model for simulating coastal wave, tide- and wave-induced currents, and coastal morphodynamic change is presented. The integrated model includes three different submodels: (1) wave model, (2) wave-induced current model and (3) sediment transport model. A phase-averaged wave model based on linear wave theory is used to simulate wave transformation, deformation and to calculate radiation stresses. The current model is based on the solution of the conservative form of the nonlinear shallow water equations and effects of the Coriolis force, wind stress, bottom irregularities and short wave-averaged radiation stresses are included. The forward Euler discretization is used for the unsteady term and the convective term is discretized using Godunov-type shock capturing method on non-uniform rectilinear grids. The hydrostatic flux is calculated using an equivalent water depth at each cell interface and the bed slope source term is treated in such a way that exact balance between hydrostatic flux and bed slope source terms is achieved under still water condition. The morphodynamic change is modeled by considering local sediment balance and anisotropic downstream gravitational effect. The three submodels are operated systematically and required parameter values are transferred to the respective submodels. This sequential computations are carried forward in a cyclic order till simulation time reaches to the end time. In order to test the applicability of the model, a severe storm attack on an ideal coast is simulated. The preliminary results show that the developed model can be applied to simulate wave-current-morphodynamic processes in coastal and estuarine zones.