h^Ay" (2) 



By applying the least squares fit to each of the profiles, Dean (1977) 

 found ranges of the values for the parameters A and n {A ranged from 

 0.0025 to 6.31; n ranged from 0.1 to 1.4 with an average of 0.67, thus 

 agreeing with Equation 1 of Bruun (1962)). 



For Dean's (1977) model, he assigned a value of « = 2/3 when the rate 

 of wave energy dissipation per unit volume of the water column is equal 

 over the profile and n = 2/5 when the rate of wave energy dissipation per 

 unit area of the sea bed is equal over the profile. Since the n value of 2/3 

 matched the average n for the 504 profiles (0.67), Dean (1977) stated that 

 the critical factor in developing a profile of equilibrium must be the rate 

 of wave energy dissipation per unit water column volume. Dean (1977) 

 left the sediment scale parameter A as the only free variable. This 

 resulted in a much smaller range of A values between 0.0 and 0.3. 



Moore (1982), Dean (1987), and Kriebel, Kraus, and Larson (1991) 

 related A to the sediment fall velocity using a single grain size for an 

 entire profile. 



Dean and Maurmeyer (1983) review several profile response models 

 including those of Bruun (1962) and Edelman (1968, 1970), as well as sev- 

 eral evaluations of Bruun 's model including those of Schwartz (1965, 

 1967), Dubois (1975, 1976, 1977) and Rosen (1978). Dean and Maur- 

 meyer found that: 



a. Existing shore response models are useful for predicting long-term 

 evolution due to relative sea-level rise. Better methods and field 

 data are required to improve the capability of predicting depth of 

 effective sand motion and the associated width of this zone. 



b. The Bruun rule has been validated qualitatively and, to the limit of 

 our knowledge of the relevant processes, quantitatively for the case 

 of nonbarrier island systems. Dean and Maurmeyer (1983) state 

 that for barrier island systems which migrate landward, their own 

 model is more appropriate. 



c. Of the existing models of the Bruun type, the Edelman (1970) model 

 represents profile evolution as a continuing process and is therefore 

 probably more representative of long-term response. 



d. There is a need for application of improved profile response models 

 that incorporate the effects of noncompatible sediment eroded and 

 gradients in longshore sediment transport. 



e. There is a need for improved definition of the detailed dynamics of 

 beach profile response. This will probably require laboratory and 

 field measurements under long-term and short-term (storm) events. 



Chapter 2 Inner Shelf Concepts 



