ll coasts are divided into natural compartments called littoral cells. Each cell contains a complete cycle of sedimentation including sources, transport paths, and sinks. The presence of sand on any particular beach depends on the transport of sand within the cell. When structures such as dams or harbors interfere with sand transport, downcoast beaches will erode. Therefore, the littoral cell and its budget of sediment are essential planning tools for regional and coastal management.
Typical littoral cell (Santa Monica Cell) - Sediment sources are commonly streams, sea cliff erosion, gully and bluffland erosion. Fine suspended sediment is carried offshore in turbid plumes and deposited in deeper water. Sand is transported along the shore by waves and currents to nourish beaches. Transport rates along open ocean coasts average 150,000-600,000 cubic meters (200,000-800,000 cubic yards) per year (by comparison, a large moving van has a volume of about 200 cubic yards). Sediment sinks are usually offshore losses at submarine canyons.
5 major southern California littoral cells. Each cell is bounded by rocky headlands. Other sections of the coast are rocky promentories (Palos Verdes, Point Loma) or pocket beaches (Malibu, Orange County). Based on a diagram by Doug Inman.
Click on individual cells for more details.
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Last modifed Friday, June 25, 2003