bh, 

 H. = (37) 



b 



ba 

 gT 2 



where 



:.«3.re[i - e ( - ,9m) ] 



5. 1.56/[f e<- 19 - 5m> ] 



33. All of these empirical methods give reasonable approximations of 

 the incipient breaking wave height. In choosing a criterion for inclusion 

 into RCPWAVE, the following factors were considered. The criterion should ac- 

 count for bottom slope and wave period since field and laboratory tests show 

 these parameters to be important (Iwata and Sawaragi 1982). It should not 

 depend on deepwater parameters alone because the transformation algorithm must 

 be capable of modeling multiple breaking and reformation. The Weggel (1972) 

 and Goda (1970) criteria satisfy both requirements. The former was selected 

 for inclusion into RCPWAVE. 



34. Once the incipient breaking point is defined, a mechanism is needed 

 to transform the breaking wave across the surf zone. Historically the wave 

 height has been assumed to be proportional to the local water depth throughout 

 the surf zone. The constant of proportionality was assumed to be about 0.8. 

 Field and laboratory data have shown that this approximation consistently 

 overestimates actual wave heights within the surf zone (Dally 1980 and Thorn- 

 ton and Guza 1982). Other formulations have been developed and applied suc- 

 cessfully by researchers to calculate surf zone wave heights. Most are of the 

 following form: 



3(Ec ) 



3x 



(38) 



where Ec g is the energy flux associated with the breaking wave and 6 is a 

 term representing the rate of energy lost due to bottom friction, turbulence, 

 and other dissipative processes. 



35. Divoky, Le Mehaute, and Lin (1970) considered the dissipation in a 

 breaking wave to resemble that in a hydraulic jump. They assumed that the 

 change in energy flux could be approximated by 



20 



