Surf zone flushing on embayed beaches

Using a numerical model, we show that the surf zone of embayed beaches systematically flushes out more floating material (simulated using passive tracers) than on open beaches, with most exits occurring through the headland rips. For obliquely incident waves, a headland rip acts as a persistent conduit for transporting floating material out of the surf zone and into the inner shelf region. Wave angle and embayment size determine which headland rip (upwave or downwave) flushes out more the surf zone material. For narrow embayed beaches, passive drifters exit the surf zone through the upwave headland rip. For wider embayed beaches, the longshore current has enough room to develop and is further deflected against the downwave headland where most drifters exit the surf zone. Our results indicate that wave-exposed rugged coasts strongly enhance exchange of floating matter (e.g., pollutants and nutrients) at the ocean/continent interface.