-p"' 



K)^ (42) 



in which the superscripts m and c refer to measured and calculated profile 

 depths, respectively, and Np is the number of data points. Values of 

 different model parameters were varied to minimize the sum of the squares. In 

 the calibration process, equal weight was placed on all measurement points 

 along the profile without bias toward bars or eroded areas on the foreshore. 

 Furthermore, the model was restricted to generating one breakpoint bar to 

 limit the effort to reproducing the main breakpoint bar in the calibration. 

 The volume of the main breakpoint bar was always at least ten times greater 

 than that of any secondary inshore bar, thus being significantly more 

 important for determining the wave height distribution across shore. 



431. In simulation of beach and dune erosion, it is considered most 

 important to predict the evolution of the main breakpoint bar, since this 

 feature serves as a natural defensive response for reducing incident wave 

 energy that would otherwise arrive at the beach face. Only a small amount of 

 information was available from the LWT data set to quantify the net cross - 

 shore transport rate in zones of wave reformation. As an exercise of the 

 model, simulations to reproduce the inshore bar are presented below. It was 

 necessary to make assumptions on the net transport rate between zones of fully 

 broken waves for these simulations. 



432. It is desirable to relate empirical parameters in the model 

 directly to physical quantities or assign them a constant value to minimize 

 the degrees of freedom in the calibration process. For instance, values 

 recommended by Dally (1980) were used in the breaker decay model, i.e., a 

 stable wave height coefficient of F = 0.40 and a wave decay coefficient of 

 K = 0.17. (The optimum value of the wave decay coefficient was modified 

 slightly by Dally, Dean, and Dalrymple (1985a) to 0.15.) Although parameters 

 in the breaker decay model showed a qualitative dependence on average beach 

 slope in breaking wave data from the CRIEPI experiments, the above-mentioned 

 constant values were used in the calibration. The number of parameters 

 available for adjustment in the calibration process was thereby reduced with 



176 



