314 



Economic Aspects 



Angeles populate the 75 km of beaches be- 

 tween Point Dume and Newport Beach. 

 Others from Santa Barbara and San Diego 

 use beaches near those cities for the most 

 part. Where the beaches receive no care, 

 they soon become unsightly, as exemplified 

 by "tin can beach" south of Long Beach. 

 Recognizing the public interest in beaches 

 and the need for public access and contin- 

 uous maintenance, the State of California 

 has estabhshed 31 State Park Beaches along 

 the coast with an aggregate length of about 

 64 km, about 15 per cent of the mainland 

 shore. This property alone had an original 

 purchase value of about $17 million. Still 

 other public beaches are maintained by 

 various counties and coastal cities. Main- 

 tenance includes mechanical raking up of 

 cans and bottles, protection by lifeguards 

 and police, and for some of them the pro- 

 viding of fireplaces, toilets, and showers. 

 Most are free except for parking charges, 

 and they are supported by taxes. 



In addition to their recreational value 

 beaches serve as barriers to attack of shore 

 installations by waves. Where beaches 

 have become narrowed through man's in- 

 terference with natural beach processes, 

 waves have cut into the shore behind them. 

 At Santa Barbara, Port Hueneme, Malibu, 

 Santa Monica, Redondo Beach, and Surf- 

 side (east of Seal Beach), and possibly else- 

 where damage to shore structures has re- 

 sulted from loss of beaches. At Venice, 

 Newport Beach, Oceanside, and other places 

 the beaches have become alarmingly nar- 

 rowed. The cause of narrowing can be seen 

 in an examination of the sand budget and 

 of longshore movements of sand. 



Beaches along the 480 km mainland shore 

 of southern California average about 55 

 meters wide. At an assumed average thick- 

 ness of 4 meters the total volume of sand 

 landward of the low tide line is thus about 

 100,000,000 cu meters. By assuming an 

 equal volume of sand beyond the low tide 

 line, the total amount of beach sand is 

 about 200,000,000 cu meters. At the esti- 

 mated annual rate of supply of sand by 

 streams, 2.4 million cu meters, the entire 

 beach could be replaced in only 85 years if 



there were no losses from it. That natural 

 losses do occur is indicated by the fact that 

 beaches have not widened greatly during 

 historical time and by the known movements 

 of beach sand down submarine canyons to 

 basin floors. Longshore movement of beach 

 sand amounts to more than 200,000 cu 

 meters per year at Santa Barbara, Port 

 Hueneme, and Santa Monica. If no sand 

 passed these breakwaters and the sand at 

 their lee sides continued to move, the an- 

 nual loss would be equivalent to a complete 

 disappearance of beach for an average dis- 

 tance of about 0.5 km leeward of each 

 obstacle. In practice, of course, depletion 

 occurs in a long tapering wedge that reaches 

 a far greater distance. 



The damage to property and loss of recrea- 

 tional areas produced by narrowing of 

 beaches down-coast from breakwaters have 

 been remedied in two ways, replenishment 

 of sand and protection of what remains. 

 Replenishment has frequently consisted of 

 pumping sediment from the harbors that 

 had intercepted it, where it was not wanted. 

 This procedure is advantageous to both har- 

 bor and beach. It has been done at least 

 eight times at Santa Barbara since construc- 

 tion of the harbor there in 1929 (Johnson, 

 1953) with a total dredging of perhaps 

 6,000.000 cu meters. About 310,000 cu 

 meters were pumped from the harbor at 

 Port Hueneme in 1953. Plans have been 

 made to establish permanent and continu- 

 ous by-pass sand pumps at the entrances of 

 both harbors. Sand from the artificial small 

 boat harbor at Santa Monica has been re- 

 leased three times: 46,000 cu meters in 1940, 

 76,000 cu meters in 1950, and 420,000 cu 

 meters in 1958. In 1947 about 920,000 cu 

 meters were pumped to the beach at Surf- 

 side from between the nearby jetties at 

 Anaheim Bay constructed in 1944. At 

 Oceanside 610,000 cu meters were pumped 

 from the boat basin at the nearby Camp 

 Pendleton in 1957. Another source of sand 

 was tapped for Santa Monica Bay when in 

 1947-1948 about 11,000,000 cu meters of 

 dune sand was sluiced to the beaches to 

 provide space in the dune area for the 

 Hyperion Sewage Treatment Plant. In other 



