Quasi-2D sediment transport model combined with Bagnold-type bed load transport

Suspended load and bed load sediment transport are important component for the sediment transport in surf zone. The purpose of this study is to obtain a good model for sediment transport in surf zone by combining a quasi-2D sediment transport model and the Bagnold-type sediment transport model. The quasi-2D sediment transport model is used to simulate the suspended load transport, while the Bagnold-type for the bedload transport. A quasi-2D numerical wave model called Funwave was expanded to accommodate the sediment transport model. The model is validated by the published data for sediment transport in a wave flume. Two mode of morphological change is compared to evaluate the influence of wave-current (mode A) and instantaneous bottom velocity (mode B) in the third and forth velocity moment of Bagnold-type sediment transport model. Four sets of bed load transport parameters are evaluated to calculate bed level change. The evaluation shows that although e_B exceeds one, it can produce bed level change similar to that by using the parameters proposed by Bailard. Parameters proposed by van der Molen calculated very high bed level change, while Gallagher's parameter produced relatively small bed level change. The performance of two modes of morphological change shows that mode A produce much better morphological change than mode B in surf zone for the bedload transport component. While for the suspended load component, mode B produces very high erosion in surf zone. Coupling of mode B and a wave motion-induced suspended load transport gives comparable morphological change to the experimental data.