After 25 hours the only profile changes were a slight general increase 
in the foreshore slope and a gradual increase in the foreshore berm 
crest elevation. The Kp continued to increase, but at a slower rate. 
The variation in Kp after 35 hours was +0.03, on the order of +0.025 
variation in the fixed-bed tank. 
Throughout the experiment the foreshore slope was slightly flatter 
and the Kp was significantly lower along the outside ranges. 
Other than the minor changes in the foreshore shape after 25 hours, 
the profile appeared to be quite close to equilibrium (Fig. 42). 
The range of median grain sizes increased in the coarser fractions 
in the foreshore zone and increased in the finer fractions in the offshore 
zone. 
The temperature did not vary significantly and the shoreline (and the 
profile) reached equilibrium within 25 hours (see Fig. 40). 
3. Comparison of the Two Experiments. 
Although the general shape of the profiles and the sequence of events 
during the development of the profiles were similar, there were signifi- 
cant differences between the two tanks. 
a. Foreshore Zone. The foreshore zone in experiment 72A-06 was 
dominated by the counterclockwise circulation of the swash, forming a 
steep beach face (0.197) along range 5 and a flat beach face (0.123) 
along range 1. This circulation pattern did not develop in experiment 
72A-10 where the foreshore shape was more uniform laterally, varying from 
0.171 to 0.209. There were slightly flatter slopes along the outside 
ranges than along the center ranges. 
Although the shoreline advanced 0.5 foot and became stationary in the 
10-foot tank, the shoreline in the 6-foot tank retreated at an average 
rate of 0.015 foot per hour after the initial development. 
b. Inner Offshore Zone. In experiment 72A-06, a clockwise circulation 
pattern developed over the inner offshore shelf between the first two anti- 
nodes of the standing wave. This circulation pattern did not develop in 
the wider tank. After the inner offshore shelf developed in the 10-foot 
tank, the boundaries remained fixed and a bar and trough developed. A 
Similar shelf developed in the narrower tank, but was later eroded and 
transformed into a gently sloping area while the circulation pattern 
disintegrated. 
c. Outer Offshore Zone. The slope of the outer offshore became quite 
steep in experiment 72A-06, with the steepest part between elevations -1.2 
and -2.2 feet. In the wider tank (experiment 72A-10) the area between 
elevations -1.1 and -1.8 feet became slightly steeper (than 0.10), but no 
change occurred below -1.9 feet. The strong circulation pattern in the 
narrower tank is the most likely cause of these differences. 
76 
