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A recently developed compound 1DH numerical model for simulating coastal sediment transport and bed morphology evolution is extended and validated in two horizontal dimensions. The wave module is a higher-order Boussinesq-type model. The bed load in the surf zone is computed from an advanced semi-empirical formula while the suspended load can be calculated through the solution of the advection-diffusion equation for the sediment or alternatively from a simplified formula. The estimation of the sediment transport in the swash zone is based on the ballistic theory. Extended simulation time is achieved through the application of the morphological accelerator factor technique. The validation tests showed a good response of the model with regard to longshore sediment transport under the combined action of waves and currents. A similarly good behaviour of the said model in the cross-shore direction was presented in a previous paper. In addition, the formation of a tombolo behind a detached breakwater is...

A two horizontal dimensional compound model is developed to simulate coastal sediment transport and bed morphology evolution due to wave action. The wave module is a higher-order Boussinesq-type model. The bed load in the surf zone is computed from an advanced semi-empirical formula while the suspended load can be calculated through the solution of the advection-diffusion equation for the sediment or alternatively from a simplified formula. The estimation of the sediment transport in the swash zone is based on the ballistic theory. The unified sediment transport module is valid under combined waves and currents including the wave asymmetry and phase-lag effects. The bathymetry is updated through the sediment conservation equation and the morphological accelerator factor technique accounts for extended simulation time. The model is validated against a number of short-term tests in one horizontal dimension. The response is generally good with most of the morphological features being reproduced in the cross-shore direction. A comparison between various sediment transport formulae and a sensitivity analysis are also performed illustrating the need for inclusion of the phase-lag effects.