LITTORAL DRIFT STUDY 

 LOS ANGELES, CALIFORNIA 



A complete knowledge of the mechanics of the littoral movement of 

 beach material is of primary importance in planning beach improvement pro- 

 jects o This fact has long been recognized by the Beach Erosion Board but 

 little work has been done in this field due to the large expenditures re- 

 quired in providing sufficient material for a controlled field testo 



Early in 194-8 it was found that artificial beach filling at Surf side 

 near Anaheim Bay, California , and at Santa Monica Bay near the Los Angeles 

 sewer outfall at El Segundo, provided suitable areas for controlled tests, 

 in two adjacent embayed areas separated by a rocky hsadlando See Figure 

 1. 



In the Anaheim Bay area approximately 1,100,000 cubic yards of 

 material were dredged from the harbor entrance and deposited on the beach 

 in front of the Surf side and Sunset Beach colonies to be distributed 

 down-drift by the natural forces „ 



In the EL Segundo area 14.,000,000 cubic yards of material are being 

 supplied to the beach through a construction project which required the 

 removal of sand dunes to provide a site for a new sewage treatment plant. 



The situation and characteristics of the two artificial beaches are 

 considerably differento 



The shore line in the Anaheim Bay area runs in an east-west direction, 

 is partially protected from wave action by Catalina Island and has relative- 

 ly flat bottom slope s„ The shore line in the Santa Monica Bay area runs 

 in a north-south direction, is less protected by offshore islands and has 

 a relatively steeper bottom slope. 



In these two adjacent yet relatively different natural laboratories 

 the Beach Erosion Board hopes to obtain information leading to the correla- 

 tion of the volumetric littoral movement of sand deposited on these beaches 

 with the natural forces producing this movement . 



In the Anaheim Bay area, hydrographic profiles are being taken at 

 approximately one-half mile intervals, with more frequent profiles where 

 the shore line is irregular or where the sand is in rapid movements, 

 These profiles extend to a depth of thirty feet mean lower low water, 

 with four profiles spaced through the area extended to a depth of sixty 

 feet to detect any deep water movement of sand that might be presento A 

 topographic survey has been made of the shore area,, The profile surveys 

 will be repeated at monthly intervals, or as frequently as may be necessary 

 to detect and measure sand movemento Extensive sand sampling is in pro- 

 gress, both on the beach and offshore, as an aid in tracing the source and 

 rate of sand movemento Studies will also be made of sand in suspension, 

 currents, and rate of littoral drift in the surf zone A recording gage of 

 the step-resistance type to record wave amplitude and period, along with a 



