131. When regular wave conditions in the model were increased 10 percent, better profile reproduction 

 was observed with increased movement of nearshore sediment to the offshore region of the model. An 

 explanation for this behavior was found by examining the ratio of the Xie parameter between prototype 

 and model. Model test T04, with wave height increased 10 percent, showed better similarity of Xie's 

 parameter in the offshore region than did test T03, as shown in Table 4. This supports the contention that 

 the offshore bar has a sediment capacity for a given regular wave condition, and it suggests that the scaled 

 wave height determined by application of the movable-bed modeling criteria given by Equation 6 should be 

 augmented for uniform regular waves so that closer similarity between prototype and model values of Xie's 

 parameter is achieved. 



132. Verification of the scaling guidance under irregular wave conditions was highly successful (test 

 T14). Profile development in the model closely followed that of the prototype-scale experiment and did not 

 require altering the model significant wave height to provide closer correspondence to the Xie parameter. 

 Based on these results, it appears that the irregularity of the wave train extends the region of sediment 

 transport dominated by turbulence and hence moves the sediment farther offshore before transitioning into 

 a bed-load-dominated mode. 



133. Experimented repeatability was shown to be quite satisfactory at midscale under regular wave 

 conditions, and overall, the verification of movable-bed scaling guidance based on undistorted Froude 

 models preserving the sediment fall speed parameter has been achieved for the specific case of 

 turbulence-induced profile development of regions characterized by noncohesive sediments. However, bear 

 in mind that these results are encouraging to the extent that prototype-scale wave tanks can reproduce 

 natural beach response without adverse laboratory effects. 



55 



