action on the movable bed due to development of the steeper foreshore. 

 The reflection decreased as the inshore widened. Later increases in K^ 

 occurred when the offshore steepened (Figs. 2, 3, 38, and 39). 



(c) Profiles in the two experiments developed in the same sequence, 

 but did not reach equilibrium (Figs. 10 to 17). 



(d) Within the first hour of testing the foreshore developed a shape 

 which was in dynamic equilibrium. During the time before the shoreline 

 stabilization, the position of the foreshore retreated at average rates 

 which varied from 0.06 to 0.14 foot per hour (Figs. 10 to 19; Table 8). 



(e) Changes in the sediment-size distribution along the profile appear 

 to be measurable, even in the laboratory with the use of fine sand (Table 

 11). 



(f) Lateral variations in the development and the shape of the in- 

 shore zone in the 10-foot tank did not occur in the narrower tank, indica- 

 ting that the tank width may have affected the profile development (Figs. 

 10 to 17 and 40). 



(g) Differences in the rate of shoreline erosion and profile develop- 

 ment may have been caused by the difference in initial test length, which 

 affects secondary waves and re-reflection from the wave generator ffig. 21). 



(h) The increase in the rate of shoreline recession at 22 hours in 



experiment 70X-06 occurred coincidentally with a 10°-Celsius drop in water 



temperature. This supports the hypothesis that colder, more viscous water 

 will transport more sediment (Fig. 37). 



2. Recommendations . 



(a) Because of varying reflectivity of the profiles, incident wave 

 measurements to characterize a three-dimensional coastal engineering 

 experiment should be based on calibration of the wave generator rather 

 than isolated wave measurements during the experiment. 



(b) Experimenters should be cautious in defining equilibrium profile 

 conditions. 



(c) When conducting movable-bed experiments, water temperature should 

 be kept near constant. 



84 



