The Effects of Bed Slope and Wave Skewness on Sediment Transport and Morphology

The potential relevance of wave skewness and sloping beds on morphodynamic predictions is investigated. Based on a comparison with measurements it was shown that the phase lag is potentially important for modeling nearshore bar dynamics as it influences the suspended wave related transports (magnitude and direction). Velocity skewness results in a phase shift between the orbital motion and the instantaneous bed shear stress increasing onshore bed load transport. It was seen that its influence is relatively small but does affect bar migration and helps to predict the observed asymmetric bar shape. The bed slope affecting the initiation of motion and sediment bed-load transport magnitude and direction are investigated by comparing scour hole predictions. The initiation of motion, which is also included on the suspended transports, only has an effect for somewhat steeper slopes. The modifications of bed-load direction and magnitude significantly affect the horizontal and vertical scour hole equilibrium dimensions.