d. Ilindcust uj Severe Storms. Wave statistics were compiled by Iiindcasting techniques 

 for the 10 most severe storms for three selected stations off the Northern California coast 

 during the period 1951-1960. (National Marine Consultants, 1960b.) Station 3 (37.6°N, 

 123.5°W) is representative of severe wave conditions offshore in deep water from the 

 Golden Gate. For each storm the significant heights and periods and direction of waves are 

 tabulated for four times each day for the duration of the storm. 



e. Bolinas Bay Wave Recorder. A pressure-type wave recorder was installed in 18 feet of 

 water in Bolinas Bay by the Bolinas Harbor District in February 1969. Except for a few 

 days, when the recorder was inoperative due to power or other failures, continuous records 

 were obtained from 20 February to 23 August 1969. Significant heights and dominant 

 periods at the wave gage were compiled and plotted against time. (Gilroy, 1970a, App. 

 No. 3.) No data were available on wave direction. 



/. Stinson Beach State Park and Bolinas, California. Surf observations at Stinson Beach 

 by State Park personnel and at Bolinas by personnel of the Bolinas Harbor District were 

 instituted in May 1968 following procedures prescribed by the Coastal Engineering Research 

 Center (CERC). (Darling, 1968: Berg, 1968.) Visual observations (twice daily) were made 

 and recorded on wave period, height, and direction: breaker type; wind speed and direction; 

 littoral current speed and direction; berm height; and beach slope. A report on the 

 observations at Bolinas and Stinson Beach State Park for the period February— December 

 1968 has been published by CERC. (Szuwalski, 1970.) Computer readouts for the entire 

 period of record are available upon request from CERC. 



3. Wave Refraction. Wave data from the San Francisco Light Ship and the three hindcast 

 summaries (items a, b, c, and d in the above section) refer to deepwater conditions. When 

 waves move from deep water into shallow water, changes in the wave heights usually occur 

 as a result of refraction and diffraction. The characteristics of the bottom topography, the 

 wave period, and the direction in deep water determine the pattern of the wave crests, and 

 consequently the wave heights, in shallow water. 



Refraction diagrams prepared by the San Francisco District, Corps of Engineers (Table 1) 

 show how the waves from deep water transform while approaching the central California 

 coastline. 



Table 1. Corps of Engineers Refraction Diagrams for the Central California Coast 



Location 



Wave 



(sec) 



Wave Direction 



Scale 



Point Reyes to Santa Cruz 



8 



NW 



1:210,000 



Golden Gate north to Fort Ross 



8 



W 



1:210,000 





8 



SW 



1:210,000 





12 



WNW 



not given 





12 



W 



1:210,000 





12 



SW 



1:210,000 





16 



NW 



not given 





16 



WNW 



not given 





16 



W 



1:210,000 





16 



SW 



not given 



10 



