shown a large areal and seasonal variation in sand and beach parameters. 

 Three preliminary reports have been prepared, one by Trask and Johnson 

 (a summary of the sample data) having been published as Technical Memo- 

 randum No. 65 of the Board, one by Chien being abstracted in this 

 issue of the Bulletin, and one by Trask, Johnson, and Scott "Cut and 

 Fill on Pt. Reyes Beach" being given only limited distribution as 

 University of California, Institute Engineering Research, Series 14, 

 Issue 19. 



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

 Principal Investigator, A. T. Ippen 



A report, by Ippen and Eagleson, summarizing the work through 

 about June 1955 was issued as Technical Memorandum 63 of the Board. 

 The data indicated a null point to exist separating zones of net on- 

 shore and offshore particle motion. Net onshore particle velocities 

 were related to the indicated mass transport velocity. A theoretical 

 analysis was presented yielding a general expression for the net par- 

 ticle velocities in terms of wave and particle parameters, and the 

 boundary layer thickness. 



Additional data has now been gathered, particularly on incipient 

 motion, for both smooth and (sand) rough bottoms and for a horizontal 

 as well as sloping bottom. The data obtained seem to indicate particle 

 velocities in excess of the bottom mass transport velocities indicated 

 by Stokes. Instrumentation for measurement of instantaneous boundary 

 layer velocity distributions under waves has been initiated. Rows of 

 tiny hydrogen bubbles are to be released by pulsing a wire probe; 

 synchronized photographs will be taken of the bubbles to indicate speed. 



IV. University of California, Contract DA-49-055-eng-17. Principal 

 Investigator, H. A. Einstein 



The velocity distribution and turbulence pattern in the turbulent 

 boundary layer near the oscillatory bottom at Reynolds Numbers higher 

 than critical are being investigated - primarily to try to obtain a 

 rational method for predicting bed motion in analogy to the theory for 

 stream traction in unidirectional flow. The flow pattern has been ob- 

 tained in a general way by introducing dye at various points, and by 

 introducing solid particles having equal density with the water. 

 Difficulties in obtaining exact positions (as two simultaneous views 

 are required) restrict usage of the method however. A recording pitot- 

 tube is now being tried in an attempt to measure more exactly the local 

 velocity in the boundary layer. 



V. University of California, Contract DA-49-055-eng-31. Principal 

 Investigator, J. W. Johnson and . Sibul . 



Experimental work on wave run-up and overtopping for levee slopes 

 of 1 on 3 and 1 on 6 was carried out in a wind-wave flume to study the 

 effect of actually generating the waves by wind action rather than 



62 



