Simple Models For Surfzone Sediment Transport

Energetics-based longshore and on-offshore transport models have been developed for the surfzone. The longshore transport model describes the distribution of the longshore transport rate across the surfzone. Spatial integration of this distribution produces an equation similar in form to the wave powere equation but with a wave power coefficient which is a function of the breaker angle, the beach slope, and the ratio of the orbital velocity magnitude at the breakpoint divided by the fall velocity of the sediment. The on-offshore transport model describes the magnitude and direction of the spatially averaged on-offshore sediment transport rate in the surfzone. These parameters were found to be functions of the incident wave height and the mean beach slope. Both the longshore transport and the on-offshore transport models have been incorporated into a simple tow-line shoreline evolution model.