Resumen
Sandy coasts evolve as a result of sand transport by waves and tides. Wave-generated flows near the seabed stir the sand into the water column, which can subsequently be transported in cross-shore and alongshore directions. As waves move shoreward into shallower depth, the shape of the near-bed flow changes, which affects the magnitude of sand transport. Until now, computer simulations of decadal coastal development did not contain this shape change adequately and, as a consequence, modelled coasts were predicted to erode or accrete too rapidly. Therefore, we implemented a novel wave shape module based on field data and tested its performance in predicting the decadal evolution of typical, well-monitored sites on sandy Dutch and US East coasts. The modified model now predicts realistic cross-shore profile evolution at both sites without excessive shoreline erosion or accretion. Also, the sand transport rates along the coast are better represented. This opens up the possibility to realistically model coastal evolution on the timescale of decades to a century.