PROGRESS REPORTS ON RESEARCH SPONSORED BY 

 THE BEACH EROSICW BOARD 



Summaries of progress made during Fiscal Year 1958 on the several 

 research contracts in force between universities or other institutions 

 and the Beach Erosion Board, together with brief statements as to the 

 status of some research projects being prosecuted in the laboratory of 

 the Beach Erosion Board, are presented below. These summaries supple- 

 ment and continue those contained in prior issues of the Bulletin. 



I. University of California. Contract DA-49-055-eng-8, Sources of 

 Beach Sand. 



Seasonal sampling of Point Reyes beach and other beaches in the 

 San Francisco area was continued. In addition to Point Reyes Beach, 

 two other beaches north of San Francisco Harbor entrance (the beach at 

 Drakes Bay and Stintson Beach opposite Bolinas Bay) are being studied. 

 Four beaches south of San Francisco Harbor are being occupied. These 

 are the beaches off Golden Gate Park, Fleischacker Zoo, Sharps Point, 

 and Rockaway Beach. These beaches have been occupied at from 2 to 6 

 week periods during the last two years, and a report is now being pre- 

 pared on the data obtained. Fairly abrupt changes occur at times on 

 these beaches and consideration is now being given to an intensive 

 study of the ranges over a much shorter time interval. 



II. Massachusetts Institute of Technology, Contract DA-49-055-eng-16 , 

 Sorting of Beach Sand by Waves . 



A report entitled "The Mechanics of the Motion of Discrete Bottom 

 Sediment Particles Due to Shoaling Waves" was published as Technical 

 Memorandum No. 104 of the Board. This report is an explanation of the 

 sorting caused by shallow water waves in an experimental wave channel. 

 A series of experiments concerning wave-induced incipient and established 

 net motion of discrete spherical particles was made on both smooth and 

 artificially roughened slopes. An equation of net sediment motion is 

 derived, and applied to field data from natural beaches. Additionally, 

 some tests were carried out involving the direct measurement of bottom 

 shear stresses in oscillatory waves. These measurements were made by 

 inserting a thin plate suspended from a force balance in a false bottom 

 in the wave channel. Bottom shearing stresses on this plate were 

 measured under a wide range of waves. These data are now being analyzed 

 and a report is being prepared. 



III. University of California, Contract DA-49-055-eng-17, Fundamental 

 Mechanics of Sand Movement by Waves . 



Additional data on the velocity pattern near the bed were gathered 

 with a revised pitot tube type of gage. Measurements were first made 

 with a smooth plate to check data previously obtained. Measurements 

 have been made with both two-dimensional and three-dimensional rough- 



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