In all these simulations, the following variables were held constant: (a) a 

 time-step of 3 hours, (b) a shoreline length of 10,000 feet, (c) a longshore 

 space-step of 200 feet, (d) an A value of 0.15 foot^/-^ for the equilibrium 

 profile (see Fig. 11), (e) a berm height of 5.3 feet with a beach face slope 

 of 0.05, and (f) a duration of 1 year. The wave climate was provided by 

 the U.S. Army Engineer Waterways Experiment Station Wave Information Study 

 (WIS) 1975 data and was initiated at different times of the year as indi- 

 cated in the specific cases below. All simulations, prior to any addition 

 of sediment, used the bathymetry shown in Figure 12. The shoreline 

 (relative to mean low water, MLW) was scaled from a bathymetry-topography 

 survey provided by the U. S. Army Engineer District, Wilmington. The initial 

 offshore bathymetry was computed according to the equilibrium profile and the 

 0-foot contour; i.e., the profile was shifted seaward or landward, 

 accordingly, (see App. C.) The boundary profiles were fixed throughout the 

 simulations. The variation of COFF outside the surf zone was used because of 

 the importance of the time rate of change in this simulation. Table 1 

 presents the percentage of sediment which moves out of the control volume 

 (i.e., imaginary boundaries around the area where sediment was added) 

 directly onshore and the percentage of sediment remaining in the control 

 volume at the conclusion of the simulation for each of the cases. In 

 addition, a seventh (case 3) and eighth (case 4) were modeled. In Case 3, 

 the only difference was that sediment was placed at the 11- and 14-foot 

 contours. Case 4, however, was quite different and will be described in 

 detail later. It has a 20,000-foot shoreline, a longshore space-step of 400 

 feet, and sediment was added on a weekly basis. Also, the resolution in the 

 profile was better. 



a . Specific Cases . 



(1) Case 2. a . In order to provide insight for the interpretation of the 

 other modeling efforts, a simulation of the shoreline evolution using the 

 January to December WIS time series, with no addition of sediment, was 

 carried out. As expected, the contours almost attain an equilibrium planform 

 shape (i.e., straight and parallel between the fixed end profiles; they do 

 not, however, become aligned parallel to the base line because of the end 

 conditions). Because of the scales involved, alongshore versus 

 onshore-offshore, plotting the contours without distortion does not yield 

 much information. Appendix C provides a listing of the final contours for 

 all the cases modeled. 



(2) Case 2.b . The only difference between cases 2. a and 2.b is the 

 suppression of the WIS wave angle which was set equal to zero (i.e., wave 

 crest approach is shore-parallel at the offshore boundary of the model). 

 This does not cause the longshore sediment transport to vanish completely. 

 There are still local gradients in the contours which cause refraction and 

 relative angles between wave crest and contour, thereby driving the longshore 

 sediment transport (even if refraction was not considered, the local angle 

 between the wave crest and contour would cause sediment transport). Note the 

 larger onshore transport (Table 1) for this case compared with Case 2. a. 

 This is due to the reduction in longshore transport caused by the wave angle 

 of 0°. The model still tries to smooth the contour lines; however, more of 

 the smoothing for the present case must be done by onshore-offshore transport. 



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