Nearshore wave and current predictions compared with field observations

Both the effects of alongshore non-uniformities in the bathymetry and the importance of a roller dissipation mechanism in the modeling of longshore currents are examined and compared with measurements from a barred beach during the Delilah experiment. Comparisons are made with predictions from Delft3D, a depth-averaged two-dimensional hydrodynamic model. Measured cross-shore and alongshore variations of the mean longshore current are compared with the model for both uniform and measured bathymetry with and without a roller dissipation mechanism. It is demonstrated that the longshore current maximum in the trough measured during Delilah is the result of both the roller advecting momentum into the trough and alongshore pressure gradients associated with non-uniform bathymetry.