onshore corresponded to a shape governed by a power law with an exponent of 

 2/3 (Equation 1). The relationship between excess energy dissipation per unit 

 volume and transport rate in zones of broken waves was verified in Part V 

 using wave and profile change data from the CRIEPI experiments. 



405. In the profile change model, a transport relationship similar to 

 that used by Moore (1982) and Kriebel (1982) is applied in a region of fully 

 broken waves (Zone III) with a term added to account for the effect of local 

 slope. A steeper slope is expected to increase the transport rate down the 

 slope. The modified relationship for the transport rate q is written 



., / „ „ £ dh . T, ^ „ c dh 



(33) 



D < D„ 



1 dh 

 K dx 



where 



K = empirical transport rate coefficient 



D = wave energy dissipation per unit volume 

 D = equilibrium energy dissipation per unit volume 



€ = transport rate coefficient for the slope -dependent term 

 The energy dissipation per unit volume is given from the change in wave energy 

 flux (Equation 27) as 



D = i ^ (34) 



h dx 



406. Equation 33 indicates that no transport will occur if D becomes 

 less than D , corrected with a slope -dependent term. D can become less 

 than Dgq due to a variation in water level. For example, if a well -devel- 

 oped bar forms, waves will break seaward of the bar crest, but a water level 

 increase would make the depth inshore sufficiently large to decrease D below 

 D without wave reformation occurring. In this case, q becomes zero. 



407. As previously described, the transport direction is determined by 

 an empirical criterion (Equation 2) and the magnitude by Equation 33. If D 

 were allowed to become less than D , Equation 33 would predict a reversal 



167 



