Erosion and accretion waves from Oceanside Harbor

Coastal structures that interrupt the longshore transport of sand along beaches cause erosion. The erosion "event" travels downcoast as an erosion wave with speeds of about 2 km/yr (1.2 mi/yr). Alternatively, the placement of large quantities of dredge spoil on the beach, and the natural deposition of flood deposits from rivers, initiate accretion waves that also travel downcoast. The presence of erosion/accretion waves traveling down the coast causes local cycles of erosion/accretion on downcoast beaches.