3o The results of the first test indicate that the rate of 

 littoral drift produced by the combined forces of waves and littoral 

 cxirrents was so great that no inlet could be maintained without dredging 

 or protective workSo It was tlierefore decided to repeat the test, using 

 the same wave heights., lengths j, and directions , but elirainating the pumped 

 littoral current. Operation of the model to stability for the unbroken 

 beach was completed for test 2<, Observations of the rate of littoral 

 drift for the first phase of this test indicate that the rate of drift 

 is greater than for test 1« This increase is probably attributable to the 

 elimination of counter currents^ within the breaker zone, which were caused 

 by the pumped littoral drift during test !» 



Work planned for July 195^ 



iio All inlet identical to that for test 1 will be cut through the 

 beach J and test 2 will be oompletedo Inasmuch as the rate of littoral drift 

 for test 2 conditions is greater than for test 1, it appears certain that 

 the inlet will again be closed completelyc If so, it is planned to eliminate 

 the 10-cycle period of waves from downbeach for test 3, and if complete 

 closure of the inlet again takes place, to substitute wave angles of 10° 

 and 15° for the present angles of l5° and 30° for test U. 



71. Beach Erosion Boards Research Division, Project Status Report 

 for Quarter end in g 30 September 1952. « 



In addition to the research projects under contract to the various 

 institutions which are reported on above, the Research Division of the 

 Beach Erosion Board is carrying out certain projects with its own facilities. 

 A short description of the main projects and the work accomplished through 

 the last quarter is given below. 



Equilibrium Profile of Beaches - Tests were conducted in the 

 laboratory wave tanks to investigate the effects of the characteristics 

 of waves and beach material on a beach profile shaped by uniform wave 

 action. The foreshore and offshore profile slopes, along with other 

 measures of the profile shape, are empirically correlated with wave and 

 sand size variables. The report on this study has been completed and is 

 under review by the staff. 



Study of Effects on Beach Profile of Varying Wave Periods - The 

 purpose of this study was to determine the magnitude and frequency of 

 , variation of the wave period, necessary in laboratory wave tank tests, in 

 order to eliminate profile irregularities encountered with the use of 

 a fixed or constant period. Four tests were run to study a short period 

 wave and four tests to study a long period wave. The results of this 

 investigation indicate, for the limits studied, very little change in 

 general slopes of the resultant beach profiles but also indicate a general 

 smoothing of the profiles. The report on this study has been completed 

 and is under review by the staff., 



