Numerical experiments on interactions between wave motion and variable-density coastal aquifers

► Nearshore hydrodynamics are combined with density-dependent groundwater flow and bed morphology changes into a single model. ► The 2D model describes details of coastal sea and aquifer interactions at the field scale. ► Wave characteristics and watertable elevations are critical to beach profile prediction. ► The model predicts, in agreement with observations, that coarse-grained beach tends to be steeper than fine-grained beach. ► Coarse- and fine-grained beaches differ in their erosive characteristics, as manifested in the locations of bars and berms.