A14 



Dalrymple et al. (1984a,b) presented the corrected form of the mild slope 

 equation including the influence of strong currents, wave amplitude 

 nonlinearities, and islands/structures. This model is valid for waves propagat- 

 ing within the ±70-deg sector to the principal assumed wave direction used for 

 input The mild slope equation, in terms of the horizontal gradient operator, is 

 given by 



V • CC;^A + G^-±A = 



^ c 



where 



C = wave celerity 

 C = group velocity 



A = wave amplitude 



a = angular frequency 

 and the linear dispersion relationship is 



o^ = gk tanh kh (^^^ 



where 



g = gravitational constant 



k = wave number 



h = water depth 



The model is based on Stokes' perturbation expansion. In order to have a 

 model that is valid in shallow water outside the Stoices range of validity, a 

 dispersion relationship which accounts for the nonlinear effects of amplitude is 

 included in REFDIF. This relationship, developed by Hedges (1976), is 



o^ = ^/t tanh(/:/j(l + |>i|//!)) ^^^^ 



The Hedges form is coupled to the Stokes relationship to form a hybrid model 

 valid in shallow and deep water. The model can be operated in three different 

 modes: (a) hnear, (b) Stokes-to-Hedges nonlinear, and (c) Stokes weakly 

 nonlinear. The linear mode was used in this study since wave breaking along 

 TR 3 (wave generator location) was not of concern. Model predictions 



Appendix A Saco Bay Nearshore Wave Estimates 



