4. Breaker Characteristics. 
A plot of breaker position (dashline) superimposed on a plot of con- 
tour movement along range 3 for experiment 72B-06 is shown in Figure 37. 
The waves broke by plunging and mainly at depths of 0.3 to 0.4 foot. 
A similar plot of breaker position along range 5 for experiment 
72B-10 is shown in Figure 38. The waves broke by plunging before 115 
hours and by spilling after 115 hours, at depths of 0.2 to 0.4 foot. 
A plot (Fig. 39) of breaker position superimposed on a plot of contour 
movement in the inshore zone along ranges 1 and 9 of experiment 72B-10 
shows that the waves broke by plunging (except at 110 and 140 hours 
along range 1) at depths of 0.3 to 0.5 foot. 
5. Water Temperature. 
Figure 40 gives data on daily average water temperature versus both 
cumulative test time and dates for experiments 72B-06 and 72B-10. 
6. Wave-Generated Currents. 
Wave- generated bottom and surface currents were observed throughout 
the two experiments. In experiment 72B-06, no discernible pattern of 
circulation developed in the surface currents; however, if a bob moved 
inside the breaker zone it stayed between the breaker and the shoreline. 
Although no apparent pattern of bottom currents was observed, all 
neutrally buoyant bobs eventually moved offshore to the area between 
stations 30 and 32, even if the bobs started inside the breaker zone. 
The pathlines of surface current bobs indicate as many pathlines in one 
direction as in the opposite direction (Fig. 41). Although surface cur- 
rents were observed throughout, no regular pattern ever developed. The 
average velocity was 0.037 foot (1.128 centimeters) per second. 
No apparent circulation pattern developed in the surface currents of 
experiment 72B-10; however, surface bobs dropped shoreward of station +15 
moved shoreward, and any bob that moved into the breaker zone stayed be- 
tween the breaker and the shoreline. The area between stations +7 and 
+9 was the dividing line for bottom currents; a bob went either direction 
from within this area, and a bob placed seaward or shoreward of the area 
moved away from the area. The current bobs and organic matter (leaves, 
debris) accumulated in the area bounded by ranges 0 and 1 and stations 
0 and +3 and in the area bounded by ranges 0 and 10 (the tank walls) and 
stations +19 and +22. Other than the limits of general directions dis- 
cussed, no patterns or regular pathlines of circulation developed in 
this experiment either. The average velocity was 0.046 foot (1.402 
centimeters) per second. 
III. PROFILE DEVELOPMENT AND REFLECTIVITY 
Results are analyzed by: (a) Profile development, in which the inter- 
dependence of the changes in profile shape, sediment-size distribution, 
67 
