Radar Estimates of Surfzone Dissipation Drive a Morphological Evolution Model

Abstract The dissipation of wave energy is important to nearshore circulation and beach profile evolution. Here, radar measurements of wave dissipation at the water surface across the surfzone are used to estimate water velocities and sediment transport in the lower water column to drive an energetics model for morphological change. The radar‐driven model accurately simulates both the 25‐m onshore and the 50‐m offshore migration of a sand bar observed on an Atlantic Ocean beach with a single set of calibration coefficients. Similar to previous studies, wave asymmetry dominated during mild wave conditions when the bar migrated shoreward, and undertow dominated during energetic conditions when the bar migrated seaward. Model results were improved by accounting for both wave bottom boundary layer effects near the sand bar (especially during onshore migration) and the vertical extent of sediment suspension in the undertow transport (especially during offshore migration).