formed a longshore bar in the inner inshore. A shelf developed in the 
outer inshore as sand was deposited just seaward of the breaker position. 
Between 5 and 15 hours the breaker moved seaward with the development 
of the outer inshore shelf and the longshore bar in the inner inshore 
eroded. Longshore currents developed at the base of the foreshore as 
three-dimensional changes in the foreshore occurred. 
At 30 hours the breaker began moving shoreward, and between 50 and 
85 hours the breaker type varied between plunging and spilling and the 
breaker position varied across the inshore zone. The foreshore and 
shoreward edge of the inner inshore moved landward, and the offshore and 
seaward edge of the outer inshore moved seaward, at rates which varied 
from high (initially) to almost zero near the end of the experiment. 
At 85 hours, the length of the shelf in the outer inshore had 
increased enough for the wave to break twice, by spilling at the outer 
edge of the outer inshore and by plunging at the outer edge of the inner 
inshore. The erosion of the trough in the outer inshore started along 
the sides and progressed toward the center. 
The movement of the shoreline with the change in water temperature is 
compared in Figure 26. The water temperature dropped throughout the ex- 
periment. The shoreline recession rate gradually decreased, indicating 
that the volume rate of erosion was fairly constant. 
2s Profile) Ret llectavalty.. 
The profile shapes which evolved during the profile development are 
shown in Figure 6. Steep foreshore and offshore slopes developed almost 
immediately and then began to separate. The distance between the two 
slopes increased as the: foreshore retreated landward with the erosion of 
sand from the foreshore and backshore, and the offshore advanced seaward 
with the deposition of the sand seaward of the breaker. 
Figure 3 shows the variability of the reflection coefficient in this 
experiment. At 1.5, 25, 55, and 105 hours, maximum values. occurred; at 
35, 60, 90, 95, and 120 hours, minimum values occurred. No long-term 
increase or decrease is apparent. 
With the development of the two reflecting zones separated by a 
growing distance of fairly gradual slope, the measured reflected wave may 
have been composed of two reflected waves. A change in phase or amplitude 
of either reflected wave would change the phase and amplitude of the 
measured wave. Perhaps the Kp variability can be attributed to the 
change in phase difference between these two reflected waves as the fore- 
shore retreated landward and the offshore advanced seaward. 
With the depth over the inshore zone an average of 0.6 foot, the 
average wavelength was 6.23 feet (1.90 meters). An increase of 3.12 feet 
(0.95 meter) in the distance between the two reflecting zones would cause 
a change in phase difference of 360°. The distance between the 0- and 
-1.0-foot contours increased from 10 to 28.5 feet (3.0 to 8.7 meters), 
DZ 
