K 

 £ = — (F - F s ) (45) 



in which 



pgT z h% 

 F s (46) 



where K is a dimensionless decay coefficient, and T is an empirical stable 

 wave factor equal to the ratio of the stable wave height to water depth. 



65. Ebersole (1987) compared the models of Dally (1980); Dally, Dean, 

 and Dalrymple (1985a, 1985b); and Svendsen (1984) to field data collected at 

 Duck, North Carolina. Both models predicted wave height well, especially in 

 the inner surf zone . 



66. Mizuguchi (1981) developed a model that allowed for wave deforma- 

 tion on complex beach profiles, as does models of Dally (1980); Svendsen 

 (1984, 1985); and Dally, Dean, and Dalrymple (1985a, 1985b). The approach in 

 modeling the surf zone energy dissipation, which Mizuguchi states is "physi- 

 cally obscure," is to replace molecular viscosity with turbulent eddy viscos- 

 ity in solving for internal energy dissipation due to viscosity. Model pre- 

 dictions compared well with laboratory data collected on a horizontal beach, a 

 1/10 plane slope, and a step -type beach. 



67. A simpler and more traditional method of estimating wave height in 

 the surf zone is by the expression suggested by Longuet-Higgins and Stewart 

 (1964). 



H = y h h (47) 



Bowen, Inman, and Simmons (1969) supported the relationship with laboratory 

 data conducted on a 1/12 slope. Equation 47 implies wave height decay is 

 linear; however, laboratory data by Horikawa and Kuo (1967), Street and 

 Camfield (1967), and Van Dorn (1977) indicate decay is steeper than predicted 

 by Equation 47 on gentler bottom slopes . 



68. Noting the concave form of the broken wave profile and motivated by 

 analytical studies to use a simple but more accurate prediction of the broken 



38 



