95 hours, K^ was lower and varied between 0,09 and 0.14; after 95 hours,. 

 K^ fluctuated between 0.12 and 0.20 and, in general, increased. The 

 largest values of K^ occurred at 124 and 164 hours. 



(2) Experiment 70X-10 . Figure 3 shows K^ versus time for 

 experiment 70X-10 for all time and for the first 10 hours at a larger 

 horizontal scale. During the first 20 hours, K^ varied from 0.10 to 

 0.16, and between 21 and 89 hours, % ranged from 0.04 to 0.12. From 

 89 to 184 hours, K^ increased from 0.08 to 0.19 and after 184 hours, 

 Kj^ decreased to as low as 0.10 at 204 hours. The maximum values occurred 

 at 139, 174, and 184 hours. 



c. Evaluation of Automated Method for Determining K^. The reflection 



coefficient versus time data for experiments 70X-06 and 70X-10 as deter- 

 mined by the automated method are shown in Table 7. Volume I discusses 

 the procedure and the programs used in the automated method. Plots of 

 reflection coefficient versus time from the movable-bed profile for the 

 two experiments, as determined by both manual and automated methods, are 

 shown in Figures 4 and 5. The automated method gave consistently lower 

 values, but the time variation in reflection was similar. Manual values 

 versus automated values for the two experiments are shown in a scatter 

 plot of the Kj^ data (Fig. 6). Lines through the data points lie above 

 and parallel to the perfect correlation line, indicating that the auto- 

 mated method gives consistently lower values and that the difference was 

 not a function of the magnitude of the reflection coefficient. The auto- 

 mated K^ values averaged 0.05 lower in experiment 70X-06 and 0.04 lower 

 in experiment 70X-10. 



d. Reflection from the Fixed-Bed Profile . The average K^ from the 

 fixed-bed profile was 0.05 in experiment 70X-06 and the values varied from 

 0.05 to 0.06 (Table 7). In experiment 70X-10, the values ranged from 0.03 

 to 0.07 and the average was 0.04. The small variation in the K^ for 

 the fixed-bed profile indicates that the wave generator was performing 

 consistently. The variation also indicates that the measurement of K^ 

 from a wave envelope recorded by a slow-moving wave gage can vary by ±0.02. 

 The large values of K^ from the movable bed were not the result of any 

 change in the generator, because the K^ values from the fixed bed 

 remained at their usual values (Table 7). 



2. Profile Surveys . 



a. Interpretation of Contour Movement Plots . The profile surveys 

 (discussed in Vol. I) measured the three space variables of onshore- 

 offshore distance (station) , alongshore distance (range) , and elevation 

 at fixed times (Table 2) during the experiment. The CONPLT method (Fig. 

 7,b) for presenting the data involves fixing the alongshore distance by 

 selecting data from a given range and analyzing the surveys along that 

 range. The surveyed distance-elevation pairs along that range are used 

 to obtain the interpolated position of equally spaced depths; e.g., -0.1, 

 -0.2, and -0.3 on the hypothetical profile in Figure 7(a). These contour 

 positions from each survey are then plotted against time (Fig. 7,b). 



22 



