Nearshore Flow Dynamics Over Shore-Oblique Bathymetric Features During Storm Wave Conditions

Abstract

Shore-oblique bathymetric features occur around the world and have been statistically correlated with enhanced shoreline retreat on sandy beaches. However, the physical mechanisms that explain a causal relationship are not well understood. In this study, radar remote sensing observations and results from a phase-resolved numerical model explore how complex morphology alters nearshore hydrodynamics. Observations at selected times during high-energy storm events as well as a suite of idealized simulations indicate that shore-oblique features induce strong spatial variations in the water surface elevation, wave breaking patterns, and mean current pathways. Re-emergent offshore flows and longshore current accelerations occur near the shoreward apex of the oblique nearshore features. The results suggest that complex bathymetric morphology exerts a powerful control on nearshore hydrodynamics and increases the potential for enhanced cross-shore and alongshore sediment transport.