modeling the reduction of sand transport with time into the modeling domain. 

 (The longshore transport rate at the boundar)- is reduced as the shoreline angle 

 becomes less oblique to the incident waves.) 



A similar boundaiy condition was applied to the north boundary, but the 

 difference between the prefill and postfill condition is much smaller at that 

 location. The transport coefficient. A'/, was then adjusted to achieve sand 

 transport rates at the boundaries on the order of values computed by Caldwell 

 (1966) and Cravens, Scheffner, and Hubertz (1989). Final calibration was 

 achieved using A'/ = 0.55 and A^ = 0.25. Longshore sand transport rates ranged 

 from 130,000 to 260,000 cu yd/year (99,000 to 199,000 cu m/year) to the north at 

 the south boundary and 525.000 to 650,000 cu yd/year (401,000 to 497,000 cu ml 

 year) to the north at the north boundary. These transport rates are comparable in 

 magnitude, but slightly larger (and therefore conservative) than the values of 

 Caldwell ( 1 966) and Cravens, Scheffner, and Hubertz ( 1 989). Net transport rates 

 for the sediment-rich condition of the nourished beach are expected to be some- 

 what larger than the rates for the sediment-starved prefill shoreline. 



Initial shoreline position. The construction template shoreline is inappro- 

 priate to use as an initial shoreline for the CENESIS shoreline evolution simula- 

 tions. The construction template is typically placed with considerably steeper 

 slopes than the equilibrium profile, and the resultant cross-shore adjustment of 

 the profile is not accounted for by CENESIS. Therefore, an equilibrium profile 

 shape was developed for representing the initial condition (expected shoreline 

 position after adjustment to equilibrium). An analytical method was developed 

 to translate the construction-template shoreline position, accounting for equili- 

 brium profile adjustment. Figure 19 illustrates the concepts of the method 

 developed. First, the construction template is superimposed upon the prefill 

 beach profile. An equilibrium beach profile is constructed through the inter- 

 section of the construction template and prefill beach profile. The shoreline 

 advance because of the added volume between equilibrium beach profile 1 

 (denoted as EBPl in Figure 19) and the construction template is given by 

 Equation 2. 



A, = ^^ (2) 



(k+B) 



where 



Av = shoreline advance 



AF= volume between construction template and EBPl 



h* = depth of closure 



B = berm height 



Equation 3 is then applied to determine the cross-shore distance between the 

 construction template and the adjusted equilibrium beach profile 2, EPB2, 



22 Chapter 3 Functional Design 



