of 0.09 foot. Part of that variation (0.03 foot) was due to measurement 
and other errors; the remainder of the variation (0.06 foot) was due to 
variation in the height and phase (at the generator) of the re-reflected 
wave. 
2. Profile Equilibrium. 
The profile in experiment 72C-10 appeared to be approaching an equilib- 
rium shape after 33,600 waves. The shoreline and foreshore had stopped 
retreating along three of the five ranges and the rate of retreat had 
slowed along the other two ranges. The offshore zone also showed signs 
of approaching equilibrium, i.e., deposition had apparently ceased at 
elevations from -0.9 to -1.3 feet. Experiment 71Y-10, which was most 
Similar to this experiment, did not appear close to equilibrium after 
63,474 waves. 
Although the experiment was not run long enough to prove that equilib- 
rium had been reached, it appeared that equilibrium was close (at least 
closer than tests with the 1.90-second wave). Also little change occurred 
in the breaker type and position or in the reflection coefficient, further 
indicating that equilibrium may have been close. 
3. Other Laboratory Effects. 
a. Water Temperature. Chesnutt and Galvin (1974), Chesnutt (1975), 
and Chesnutt and Stafford (1977a) pointed out possible temperature effects 
in the profile development in other LEBS experiments. They observed that 
with lower water temperatures (higher viscosities) the shoreline recession 
rate was greater. In this experiment, the water temperature decreased 
throughout, while the shoreline recession rate decreased from a high rate 
to near zero. Thus, this experiment does not support the suggested tem- 
perature effect found in the earlier tests, although it is not ruled out. 
b. Tank Width. Volume III pointed out greater lateral variation in 
the development of the profile in the 10-foot tank than in the 6-foot tank | 
for the 1.9-second wave. In this experiment in the 10-foot tank with the 
shorter 1.5-second wave, even greater three-dimensional effects were ob- 
served in the foreshore and inshore regions than in the 10-foot tank with 
the 1.9-second wave. 
V. CONCLUSIONS AND RECOMMENDATIONS 
le Conclusions: 
(a) In experiment 72C-10 with a water depth of 2.33 feet (0.71 meter), 
a wave period of 1.50 seconds, and a generator stroke of 0.325 foot (9.9 
centimeters), the nominal generated wave height was 0.41 foot (12.5 centi- 
meters) and the average incident wave height was 0.43 foot. Reflection 
measurements in the control tank with a fixed-bed profile varied from 
0.01 to 0.03, indicating that the wave generators were operating uniform- 
ly and that the measurement error in determining Kp was +0.01 (Tables 5 
and 6). 4 
(b) Kp varied from 0 to 0.15. The variations were possibly caused 
by the change in phase difference between the waves reflected from the 
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