experiment 72D-06 the flat inshore developed quickly and then a large 

 trough was scoured at the shoreward end of the inshore. In contrast to 

 experiments 70X-06 and 71Y-06, the lateral variations in the position of 

 the -0.6-foot contour in experiment 72D-06 (Fig. 44) occurred while the 

 inshore was a flat shelf, perhaps because of the differences in initial 

 slope. 



Contour maps of the final profile shape for the three experiments are 

 in Figure 45. The profile shape obviously varied laterally, particularly 

 in the foreshore and inshore, but in the offshore zone the variations 

 were less than in the wider tank. 



c. 2.35-Second Wave . 



(1) L/W =1.86 (Experiment 72B-10) . In experiment 72B-10, the 

 L/W ratio was less than the three experiments in the 6- foot tank with 

 the shorter 1.90-second wave. The profile in this experiment was affec- 

 ted by the transverse wave, generated by the gap at the end of the gene- 

 rator blade. Thus, the width effects identified here are the result of 

 the "generator gap effect," which is another special case of width 

 effects. 



The foreshore slope and position varied laterally and with time, as 

 a result of the three-dimensional swash movement. The slope varied from 

 0.10 to 0.54. During the first 100 hours and between 130 and 150 hours, 

 the shoreline position was skewed across the tank, with up to a 1.2-foot 

 difference in shoreline position between range 1 (seawardmost) and range 

 9 (landwardmost) (Fig. 46). Between 100 and 130 hours the shoreline 

 position was not skewed. 



In the inshore a longshore bar developed near station 2 and later 

 eroded, and a flat area developed near station 5 and later developed into 

 a bar. The above changes occurred at different times along each range, 

 as shown by the variation in movement of the different contours in Figure 

 47, and as discussed in Volume VII. 



Flat areas developed in the offshore zone near stations 8 and 16, but 

 in each case the elevation of this flat area increased from the range 1 

 side to the range 9 side. Sand deposited at the toe of the slope along 

 ranges 1 and 3, but not along ranges 5, 7, and 9. The lateral variation 

 of contours in each of the three areas is shown in Figure 48. 



The final profile shape is shown in Figure 49 with lateral variations 

 in the areas discussed above. 



(2) L/W = 3.10 (Experiment 72B-06) . In experiment 72B-06 the 

 lateral variations in profile shape were minimal. The foreshore slope 

 varied from 0.10 to 0.46 as a result of lateral variations in swash move- 

 ment, but the shoreline position varied as much as 0.5 foot only once and 

 was generally uniform (Fig. 50). 



92 



