breaker decay model allows for wave reformation to occur, which is an essen- 

 tial feature for modeling profiles with multiple bars. The governing equation 

 for the breaker decay model is written in its general form as 



i=--i-(F-F,) (26) 



where 



K = empirical wave decay coefficient 

 Fg = stable wave energy flux 

 In this equation, the cross-shore coordinate x has its origin at the break 

 point and is directed positive shoreward. 



396. The assumption behind Equation 26 is that the energy dissipation 

 per unit plan beach area is proportional to the difference between the 

 existing energy flux and a stable energy flux below which a wave will not 

 decay. By using linear wave theory, the energy flux in shallow water is 



F = i pgH2 fTh" (27) 



I pgH^ Jih" 



397. The stable energy flux is generally considered to be a function of 

 the water depth (Horikawa and Kuo 1967), and a coefficient T is used to 

 express the ratio between the local wave height and water depth at stable 

 conditions according to 



H3 = rh (28) 



398. Measurements of the wave height distribution from the CRIEPI 

 experiments were used to evaluate performance of the breaker decay model and 

 to estimate values of the two empirical parameters (ac and F) in the model. As 

 described in Part V, the breaker decay model was least- squares fitted to wave 

 height data from the breakpoint shoreward to the end of the surf zone . The 

 solution of Equation 26 for a beach with an arbitrary shape, applying linear 

 wave theory, is given by 



163 



