ALONGSHORE SWASH FLOW VARIABILITY

The swash zone, where broken waves run up and down the beach face, connects the nearshore ocean with the land. Swash zone waves and currents are important to beach morphological evolution (e.g., erosion and accretion), overtopping and flooding, and forcing on coastal infrastructure. However, the understanding of swash hydrodynamics is hindered in part by the challenges of obtaining measurements in the thin sediment-laden flows and bubbly bores that intermittently wet and dry the shoreline, and thus there are few spatially extensive observations of swash in the field. Here, cross- and alongshore currents in the swash zone along 100 m of the coast are estimated with remote sensing and particle image velocimetry (PIV) foam- tracking techniques for a wide range of incident wave conditions and nearshore bathymetry. Currents are compared with environmental conditions to analyze swash flow drivers.