The refraction diagrams listed in Table 1 are on so small a scale that the orthogonals 

 terminate at about the 10-fathom contour; hence, no information is given on the refraction 

 of the waves as they move into the shallow water of Bolinas Bay. To provide such 

 information, a few refraction diagrams at a large scale have been prepared for waves of the 

 average period of 12 seconds approaching from the critical directions of west-northwest, 

 west, and south-southwest. (Gilroy, 1970a, App. No. 3.) 



4. Wave Power. In certain coastal sedimentation processes, such as the possible closure of 

 tidal inlets, the wave power at the shoreline appears to be important. Wave data compiled by 

 the hindcast technique for 10 deepwater stations along the California, Oregon, and 

 Washington coasts (National Marine Consultants, 1960a, 1961) have been used in the 

 preparation of a summary of annual wave power for these 10 Pacific Coast stations. 

 (Johnson, Moore, and Orrett, 1971.) This summary also contains wave power data by 

 months for Station 3 off the California coast at Lat. 37.6°N and Long. 123. 5°W. The wave 

 power, P, in deep water is given as follows: 



E 



P = 



2T 



where 



yKK 



E = Energy per unit width of crest = — 



8 



H Q = Deepwater wave height 



L = Deepwater wave length 



T = Wave period 



7 = Unit weight of water 



or the power in ft -lbs per sec per unit width of crest is 



P oc H* T 



The total power for a month would equal the product of the average power per second for 

 that month times the number of seconds in the month. Since the compilation of statistical 

 data (National Marine Consultants, 1960a) gives the percentage of time that waves of 

 various heights and period occur, the total power for each month has been computed for 

 both sea and swell, and is discussed in Section III. 



5. Longshore Currents. When waves break at an angle to the shore, a longshore current is 

 induced, and is effective in moving water and sediment along the shore. Observations of the 



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