identical wave conditions during the tests. Therefore, the test 

 widths o£ the slopes reported in this study are approximately 1 foot 

 wide. 



The wave height and profile elevations were measured in centimeters 

 with a point gage mounted on an overhead trolley. Horizontal measure- 

 ments were made in feet. 



The wave height was determined by searching for a maximum and minimum 

 height ahead of the beach. These occur one-half wavelength apart. The 

 incident wave is the mean of the measurements and the reflected wave is 

 one-half of the difference. 



Profiles were taken initially and after reaching equilibrium 

 (or close to equilibrium). Equilibrium was determined by periodically 

 placing tape on the glass wall along the profile and continuing the runs 

 until no further change occurred. Equilibrium was reached in most tests 

 after 23 or 24 hours. Intermediate profile surveys were taken after 1 

 and 5 hours for most of the experiments. Water temperatures were monitored 

 and recorded. 



It was difficult to isolate the effects of size distribution and 

 particle shape with the practical materials available. The materials used 

 in the experimental program were quartz sand, glass, polyvinyl chloride 

 (PVC) , pumice, and "rocklite." 



2. Results. 



The conditions for all the tests are given in Table 2. 



Table 3 summarizes the experiments by purpose. Tabulated data on all 

 profiles are given in Appendix B; plots of the profiles are in Appendix C. 



IV. DISCUSSION OF RESULTS 



1. Effects of Size Distribution . 



Comparative tests were made with materials having equal median 

 diameters but different size distributions (Table 4). Tests IIB and 

 12B repeat the conditions of tests 5B and 6B, but with the materials 

 crossed over between the two subdivided channels. The results of this 

 comparison, as an indication of possible channel effects, are discussed 

 later. 



Selected pairs from Table 4 are shown as Figures 7 to 14. Little 

 difference was found in most profiles; however, profiles with sediment 

 having the bimodal distributions show marked differences. 



Figures 7, 8, and 14 show that the size distribution does not play a 

 major part in determining beach profiles. However, Figures 9 to 13 show 

 profiles comparing equilibrium profiles obtained with a bimodal and a 



26 



