surf zone is characterized by a strong gradient, typical of steep slopes. 

 Test 8 was conducted using a stepped beach. The model reproduces the same 

 general wave height variation exhibited by the data but not as accurately as 

 in the plane beach cases. The data show a more rapid decay immediately inside 

 the break point, and the decay seems to be toward a stable height less than 

 that predicted by the model. Some oscillations appear in the data, possibly 

 from reflections, which make an estimation of the stable height difficult. 

 The values of k and y used in the model's breaking scheme were selected to 

 provide a "best" fit to both data sets. Better agreement could have been ob- 

 tained for individual data sets by using some other values. There is also 

 evidence that the values of k and y are dependent upon the beach slope 

 (Dally, Dean, and Dalrymple 1984). For simplicity, a constant value for both 

 parameters is used in the model. The final comparison is for the barred beach 

 case. Again, good agreement is obtained for the overall shape of the wave 

 height decay. The model miscalculates the location of the second break point 

 by about 0.3 m, but the simulated decay after this point closely parallels the 

 data. 



59. A second series of comparisons, using the same laboratory data, 

 were made. Results from these comparisons are provided to show the capability 

 of the model to simulate the entire shoaling and breaking process, including a 

 determination of the break point. Previously, only the accuracy of the decay 

 mechanism was examined. RCPWAVE was used to simulate wave propagation from 

 generation through to breaking. These simulations were performed for those 

 cases in which the deepwater wave height was given by the authors or could be 

 computed. The deepwater wave height is used as model input. Figure C10 shows 

 the model results from Horikawa and Kuo Test 5. The model could not shoal the 

 wave up to the observed incipient breaking height; however, the simulated surf 

 zone transformation matches well with observed data. 



60. Results from similar comparisons between model results and labora- 

 tory data for the Izumiya Tests 7, 8, and 9 are shown in Figures C11 through 

 C13. In all cases the model failed to reproduce the wave shoaling peak imme- 

 diately prior to breaking. The model does decay the wave correctly for Tests 

 7 and 8. In Test 9 the model misses the first break point entirely. This 

 case was included to illustrate the dependency of accurate surf zone simula- 

 tions on the validity of the incipient breaking criterion used. 



61. For the monochromatic wave conditions considered in this 



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