188. Beginning with the usual plane-sloping beach, irregular waves were run in the physical model for 

 approximately the same time spans as the regular wave experiments, with stops in between to allow water 

 motions in the tank to settle and to survey the intermediate profiles. At the stopping points of the 

 experiment, long-period seiching motions, with largest amplitudes estimated visually to be about 5 to 



7 cm, were present in the wave tank. Suppression of spurious long-wave motions in the wave tank was not 

 implemented at the time of the test; therefore, it is not possible to determine how much of the long-wave 

 energy was associated with spurious long waves and how much could be attributed to reflection of the 

 naturally occurring bound long wave of the irregular wave train. Nevertheless, long-period motions were 

 allowed to subside before continuation of the test. 



189. Figure 26 compares representative profiles from irregular test T09 with the corresponding profiles 

 from the base test T03 after approximately the same number of waves (equal elapsed time of wave action). 

 The complete set of comparisons is given in Figure E15 in Appendix E, profiles showing the evolution of 

 test T09 profile are given in Figure D9 in Appendix D, and wave analysis results and profile soundings are 

 in Appendices B and C (Tables B9 and C9), respectively. 



190. Generally, the irregular wave condition (solid line) produced similar erosional history as the 

 regular wave case (dcished line), but at a slower rate. The initial adjustment of the plane-sloping berm 

 occurred over about the same time span in both cases (regular and irregular waves). After the initial 

 adjustment, evolution of the profile under irregular wave action was less than in the regular wave case, with 

 the most noticeable region of difference being the berm recession. This observation follows the same trend 

 as reported by Mimura, Otsuka, and Watanabe (1986) and Uliczka and Dette (1987). The irregular 

 wave-induced profile reached a near-equilibrium state at the 1,650 wave-profiling stop (see comparative 

 profiles in Figure D9 in Appendix D), which corresponds to the same response of the profile under regular 

 wave action. 



191. Comparison of the regular and irregular wave profiles after 1,650 waves shows a close 

 correspondence between profiles, indicating that the regular wave condition was well matched by the 

 irregular wave condition where i/1/3 equals the monochromatic wave height. Cross-tank variation in the 

 profile after 1,850 waves was minimal compared with that observed in the regular wave case. (See 

 center-line profile 1850-P versus sidewall profiles 1850-G and 1850-C for test T09 in Appendix D.) It is 

 presumed that the irregularity of the wave field helped to subdue whatever mechanism was responsible for 

 the cross-tank variations in the regular wave tests. 



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