impression of a stronger correlation between parameters than is the case. 



270. In the present study, the CRIEPI data set, which contains compre- 

 hensive wave information, was used to determine the distance i^c between the 

 break point and the maximum trough depth normalized by the deepwater wave- 

 length. This quantity was best correlated with the ratio of the breaking wave 

 height to the deepwater wave height and to the local slope just prior to 

 breaking. Evaluation of the slope was somewhat subjective, and it was defined 

 as the average for the region of approximately one -half the local wavelength 

 seaward of the break point. Consideration was also given to characteristics 

 of the cross -shore distribution of wave height to determine the region of 

 considerable shoaling and thus where wave properties were greatly influenced 

 by profile shape. The regression relationship derived is 



0.12 (tan/3)'°'''' 



Hv, 



(16) 



271. The coefficient of determination for Equation 15 is 65 percent for 

 110 values. Only profiles having a distinct trough were used in the analysis. 

 Figure 24 displays predicted normalized plunge point distances (subscript p) 

 and measurements (subscript m) . The location of the maximum trough depth was 

 inferred to be closely related to the location of the maximum cross -shore 

 transport rate. A bar typically formed immediately seaward of the trough as 

 an accretionary feature resulting from the seaward decrease in cross -shore 

 transport rate. 



Bar slopes 



272. The growth of a bar is ultimately restricted by the maximum slope 

 that sand grains can maintain without moving under the action of gravity. If 

 this limiting slope is exceeded, avalanching will occur and the sand will be 

 redistributed to attain a more gentle slope which is stable. Allen (1970) 

 recognized these two different slopes and called them the angle of initial 

 yield and residual angle after shearing, respectively. From his experiments 

 with natural sand (diameters ranging from 0.27 to 3.17 mm in the experiments), 

 he obtained an angle of about 48 deg to cause avalanching and an angle of 

 about 33 deg as the stable slope after avalanching had ceased. 



100 



