Bar (Coastal)

A coastal bar is a submerged or intertidal ridge of sand or gravel that lies roughly parallel to the shore in the nearshore zone. It forms where breaking waves and the offshore-directed undertow deposit sediment at the break point, so the bar marks the line of most active wave breaking. Bars migrate offshore under storm waves and onshore under low swell, driving the seasonal cycle of beach erosion and accretion. Multiple bars can occur across the surf zone. Bars dissipate wave energy before it reaches the beach and are mapped in nearshore bathymetric profiles, where they read as elevation maxima between troughs.