per unit length of shoreline needed to reestablish the bottom elevation 

 over a distance, B, seaward from the shoreline is AB. The length, B, 

 is the distance measured perpendicular to the shoreline out to the depth 

 contour beyond which there is no significant sediment motion. The volume 

 of sand per unit length of beach, AB, must be derived from the active 

 profile by a recession of the profile. The amount of the recession, Ax, 

 is determined by balancing the volume AB with the area between the two 

 profiles. This area, given simply by Ax(h + d) , represents the volume 

 of sand per unit length of beach needed to reestablish the beach to the 

 original shoreline. Equating the two volumes gives 



AB = Ax(h + d) , 



CD 



or upon solving for Ax, 



Ax = 



AB 



(h + d) 



(•2) 



Application of equation 2 requires that the depth, d, and hence the 

 distance, B, be known. Using the values of the trend of sea level at 

 various U.S. coastal locations (App.) given by Hicks (1973), A can be 

 determined. The following section provides a procedure for establishing 

 d, and thus B. 



jTSWL, 



shifted 

 profile 



Figure 1. Similarity of profiles, Bruun's method. 

 III. SEAWARD LIMIT OF SEDIMENT TRANSPORT 



Limited observations of offshore profiles indicate that they can 

 frequently be described to a certain depth by a simple exponential decay 

 equation. Small- to moderate-scale beach features such as bed forms and 

 offshore bars tend to be perturbations on this general trend. Everts 

 (1978) describes the geometric characteristics of profiles across the 



