d. Sand-Size Distribution. In experiment 72A-06, with the strong 
circulation pattern over the profile, the sediment sizes remained well 
mixed and basically unchanged. In experiment 72A-10, where no circulation 
pattern was observed, the sediment sizes became more sorted. 
IV. DISCUSSION OF RESULTS 
1. Wave Height Variability. 
Three probable causes of wave height variability in experiments 72A-06 
and 72A-10 are (a) wave reflection from the changing profile, (b) re- 
reflection from the wave generator, and (c) secondary waves. These experi- 
ments were designed primarily to quantify the amount of variability due to 
reflection. 
a. Wave Reflection from the Profile. The Kp in the fixed-bed tank 
of experiment 72A-06 was 0.07 + 0.01; the Kp in the fixed-bed tank of 
experiment 72A-10 decreased from initial values near 0.05 to 0.02 and 
then increased to approximately 0.07. 
The Kp in the movable-bed tanks varied from 0.17 to 0.31 in experi- 
ment 72A-06 (Fig. 5) and from 0.24 to 0.37 for the average of three ranges 
in experiment 72A-10 (Fig. 6). The Kp in the center of the 10-foot tank 
was consistently higher than the Kp along the outside ranges (Fig. 6). 
The variations in Kp appear to be related to changes in the profile. 
In both experiments the Kp increased at the greatest rate as the profile 
developed initially. The wave broke in the foreshore, so most wave energy 
reached the foreshore. Later, the Kp variations in the narrow tank may 
have been caused by phase difference in the wave reflected from the off- 
shore and foreshore slopes as they separated farther. As the offshore 
Slope became more gently sloping in the narrower tank, the Kp decreased. 
The Kp was greater in the wider tank. The difference could have 
been caused by the slightly steeper slope and higher berm crest in the 
foreshore zone. The lower Kp in the narrow tank may have been due to 
more energy being consumed in driving the strong circulation currents. 
However, this is difficult to prove since the currents decreased simultane- 
ously with significant changes in the shape of the offshore zone. 
b. Re-Reflection from the Generator. The reflected wave advanced to 
the generator and was re-reflected. As the height of the reflected wave 
varied, the height of the re-reflected wave varied. As the phase differ- 
ence between the re-reflected wave and the generator motion varied with 
changes in the profile, the height and phase of the incident wave varied. 
The height of the wave incident to the profile, which was measured by 
averaging wave heights along the full tank length, varied from 0.33 to 
0.43 foot (10.1 to 13.1 centimeters) in experiment 72A-06 and from 0.30 
to 0.42 foot (9.1 to 12.8 centimeters) in experiment 72A-10 (Table 5). 
Part of that variation (0.07 foot in experiment 72A-06 and 0.03 foot in 
experiment 72A-10) can be attributed to measurement errors, variations in 
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