A Formula for Longshore Sediment Transport in the Swash

A formula is proposed for the longshore sediment transport in the swash based on the study by Larson et al. on swash-zone transport and foreshore evolution. Hydrodynamics needed to predict the local transport rate were derived from ballistics theory, where both the cases with and without friction were investigated. The formula was validated with data from two experiments carried out in the Large-scale Sediment Transport Facility (LSTF) of the Coastal and Hydraulics Laboratory. In total five experimental cases were reproduced using a typical value on the transport rate coefficient from Larson et al. A simple exponential decay with distance offshore was employed to model the transition between the swash zone and the inner part of the surf zone. The LSTF data on transport rates measured in this region supported such a simplified model.