where 



|F (n)| = modulus of the complex amplitude spectra of wave 

 elevation above mean surface at gage site 



C (n) = group wave speed at gage site 



0(n) = = angle of wave direction (see Fig. 1) 



y = specific weight of seawater 



The onshore energy flux is then summed to obtain the total onshore 

 energy flux. In the program, onshore energy flux/y = HG2. 



(8) Breaking wave height at the shoreline is determined from the 

 mean square onshore energy flux via a linear theory wave transforma- 

 tion formula which can be simplified to 



Hu = 



N/2 

 I 16|F n (n)| 2 C CT (n) cos 0(n) 

 |_n=l 



n 



X 0.2 

 IT) 



(?) 



where GB is the wave height-to-water depth ratio at breaking and g 

 the acceleration of gravity. 



The choice of GB is up to the user although a value of GB = 

 1.42 has been found by Komar and Gaughan (1972) to best fit wave tank 

 data for breaking wave heights for monochromatic waves. In the pres- 

 ent program, GB has been set equal to 0.78 but can be readily 

 changed . 



The breaking wave water depth is calculated from the equation 



— - = GBP 

 d b 



where dv is the wave breaking water depth and GBP the ratio of 

 wave height to water depth at breaking. 



In this case a different value of the ratio of breaking wave 

 height to water depth can be used in the program for obtaining the 

 proper water depth. An assumed value of GBP = 0.78 from the solitary 

 wave theory in the SPM is used . 



Linear wave celerity is assumed and breaking wave celerity is 

 estimated as 



0.5 



\ GBP/ 



The breaking wave height and celerity calculated in this approach 

 apply to all frequencies. 



21 



