Longshore Current

A longshore current is a wave-driven flow running parallel to the shore inside the surf zone, generated when waves break at an angle to the beach. The alongshore component of the radiation stress from breaking waves forces water along the coast, with speeds typically tens of centimeters per second up to about 1 m per second in energetic surf. The current carries suspended and bed-load sand, so it is the engine of longshore sediment transport and beach rotation. Its strength scales with breaker height and the breaking angle, which is why oblique storm waves drive the most rapid littoral drift and downdrift erosion.