d = local mean water depth 



g = acceleration due to gravity 



H = local wave height 



L = local wavelength 



T = wave period 



p = fluid density 



Wavelength in deep water is Lq = (gT^/Zir) and the dimensionless local wave- 

 length, d/L, is the solution of 



r tanh 



M- 



(1) 



which is presented in Table C-1 of the SPM. The average wave energy flux per 

 unit crest width is 



P=-^pgH'^cn 



(2) 



where c = (L/T) is wave celerity and n the ratio of group velocity to wave 

 celerity: 



1 + 



sinh 



t-rrd/L 1 



(4TTd/L) J 



(3) 



With no wave refraction, and provided no energy has been added to or removed- 

 from the wave train, it is convenient to express wave height changes by the 

 factor 



H' 

 o 



/2n tanh (2Trd/L) 



= K= 



(4) 



where H^ is equivalent wave height in deep water (ignoring refraction) , and 

 Kg the shoaling coefficient. The dimensionless quantities n and Kg are 

 provided for specific values of (d/Lg) in Table C-1 of the SPM. In situations 

 considered here, a nearshore wave measurement at water depth d^ is to be 

 converted into the corresponding wave condition at another relatively shallow 

 depth, d j . The wave period is presumed constant during propagation so that 

 (•^i/Lq) and (dj/L^) are known, and equation (4) would give the ratio of wave 

 heights as 





SI 



(5) 



if energy dissipation were to be ignored, 



