The wave model is presented in Part VI , where the analytic solution which was 

 used in the least-square fit is given (Equation 29). It is noted that a 

 change in broken wave height is not completely indicative of wave energy 

 dissipation; energy reordering may also occur, as discussed by Svendsen, 

 Madsen, and Buhr Hansen (1979). 



360. The empirical coefficient relating stable wave height to water 

 depth employed in the Dally model (still -water depth without setup) was 

 determined from wave height measurements by examining the ratio between wave 

 height and water depth in the proximity of areas of wave reformation. An 

 average stable wave height coefficient was calculated for each case and values 

 ranged from 0.3-0.5, showing a marked dependence on the beach slope (compare 

 with Dally, Dean, and Dalrymple 1985b). Steeper beach slopes yielded larger 

 values of the stable wave height coefficient. The wave decay coefficient was 

 then least-squares estimated, giving values in the range of 0.15-0.3. In most 

 cases , there was a tendency for the wave decay coefficient to decrease with 

 time as the inshore slope became more gentle. 



361. At first, both empirical parameters in the wave decay model 

 (stable wave height and wave decay coefficient) were least-squares estimated 

 (cf. Part VI). However, the minima of the sum of squares were located in a 

 very flat region, causing differences between optimum parameter combinations 

 and neighboring values to be small. To achieve a certain increase in the 

 energy dissipation, either the wave decay coefficient could be increased or 

 the stable wave height coefficient decreased (or a combination of these 

 adjustments). Thus, in the optimization process, since the region surrounding 

 the minimum was very flat, almost the same agreement could be obtained with a 

 small value of the stable wave height coefficient and a large value of the 

 wave decay coefficient, or the opposite situation. In some cases the optimum 

 parameter values gave unrealistically low coefficients of stable wave height, 

 such as 0.2. For this reason, the stable wave height was fixed as described 

 in the previous paragraph and only a least- squares estimate of the wave decay 

 coefficient was made, giving a sum of squares deviating only slightly from the 

 mathematically optimum value. 



362. Dissipation in wave energy flux was determined from the wave decay 

 model, calculated starting at the location of the maximum transport rate. 



148 



