advantage of a priori knowledge of the ultimate outcome of the experiment). 



122. In the prototype-scale experiments, irregular waves were run in bursts for durations up to 12 min. 

 The same duration sequence as was used in the prototype tests was scaled and followed in the model tests. 

 As in the regular wave tests, time was allowed between wave bursts for the tank seiching to subside. 



123. Two irregular wave tests were conducted as described above. The first (test T13) began with an 

 erroneous command sending long period (10 sec) waves onto the initially plane-sloping beach. This error 

 contaminated the experiment; however, the test was continued to gain experience and to assure that 

 sufficient quantities of sand had been placed to avoid exposure of the concrete revetment. Profile data and 

 wave data were obtained, but only a few wave records were analyzed, and none of the profile or wave data 

 are reported herein. The second test (T14) was conducted as designed and is reported below. 



T14 Results 



124. Test T14 reproduced most aspects of the prototype irregular wave experiment in accordance with 

 the selected scaling criteria. Summary wave statistics resulting from analysis of water level fluctuations 

 recorded at the two gaging locations are given for test T14 on Table B14 in Appendix B. (Note that the 

 addition of sand required movement of the nearshore wave gages to maintain the same distance between 

 gage and beach as existed for the regular wave experiments). 



125. Figure 15 shows the developmental response of the center-line profile in the model. The solid line 

 is the model profile mesisured after the specified number of waves, and the dashed line is a model profile 

 measured at an earlier point in the experiment. Figure 15 illustrates the relative change of the center-line 

 profile as it evolved. A complete set of profiles for test T14 is given in Figure D12 in Appendix D, and the 

 profile measurements are given in Table C14 in Appendix C. 



126. Unlike the regular wave tests (where the revetment was exposed), the profile under irregular 

 waves continued to evolve throughout the duration of the test. Toward the end of the test, the flatter 

 portion of the profile within the surf zone maintained a constant depth; and the only profile changes were 

 due to relocation of sediment from the berm to a region offshore of the slight bar feature. Bar formation 

 was virtually absent with only a slight crest-trough feature appearing near the end of the test series. No 

 significant cross-tank variations were evident throughout the test. This can be attributed to the 

 irregularity of the wave train and to the fact that the revetment was never exposed. No sidewaU profiles 

 were recorded to document this observation. (However, previous irregular wave tests had exhibited similar 

 cross-tank profile uniformity, and sidewall profiles were recorded to document the fact. These tests are 

 discussed in Part VI of this report.) 



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