Rip currents and rip channel morphodynamics under quasi-steady conditions

We developed a realistic test case for morphodynamic predictions of short-term bathymetry evolution associated with quasi-steady rip currents. Assuming stationary forcing, predictions made by the coupled wave-hydrodynamic-morphodynamic model Delft3D are compared with surf zone morphological change inferred from quarterly in-situ bathymetric surveys. The model gives plausible two-dimensional hydrodynamic predictions with offshore currents being strongest in the rip channels. When the default wave-induced bed-load transport is included the model predicts accretion on the bar similar to the observations but the predicted sandbar amplitude grows unrealistically. Both with and without wave-induced transport, the model underestimates the erosion in the rip channels.