Longshore Sediment Transport

Longshore sediment transport is the movement of sand and gravel along a coast by the longshore current that breaking waves set up when they approach the shore at an angle. The net annual drift can move hundreds of thousands of cubic meters past a point. Interrupting it (with a harbor breakwater, a groyne, or a jetty) starves the down-drift coast and causes erosion while building accretion up-drift, the root of many engineered shoreline disputes.