depending on the particular model simulation, as shown in Table 4. The model 

 simulations were performed assuming that the proposed entrance channel and 

 detached breakwater were constructed in 1983. Hence, the predicted 1988 and 

 1993 shoreline positions represent the expected shoreline positions after 5 

 and 10 years. As in the preliminary study, the ocean entrance channel was 

 again modeled as a sand sink. 



The model results of design Alternative 2, simulation code WP2A 

 (without-project design alternative), are given in Figures 6 and 7. Figure 6 

 shows the predicted 5- and 10-year shoreline positions as well as the seaward- 

 most and landward-most calculated shoreline positions, whereas Figure 7 shows 

 the calculated average annual net and gross longshore sand transport rates. 

 Again, a reversal in the average net longshore transport direction in the 

 vicinity of the proposed entrance system occurs. 



The model results of design Alternative 4, simulation code PR02A 

 (preferred alternative), are presented in Figures 8 and 9. Figure 8 shows the 

 predicted shoreline positions in which shoreline progradation is observed on 

 both sides of the entrance system. The data in Figure 9 provides the explana- 

 tion for progradation of shorelines adjacent to the proposed entrance system. 

 The average net longshore sand transport rates northwest of the entrance are 

 negative, indicating sand transport in a southeasterly direction, whereas on 

 the southeast side of the entrance the transport rates are positive indicating 

 northwesterly sand transport. Net and gross longshore sand transport rates at 

 the jetties of the proposed entrance are zero. This interruption of the 

 littoral drift in a region of converging net longshore transport directions 

 results in sand accumulation on both sides of the entrance. 



In order to isolate the shoreline impacts directly attributable to the 

 proposed navigable ocean entrance system, the results of the without-project 

 simulations (Alternatives 1 and 2) were compared to the results of the 

 preferred alternative simulations (Alternatives 3 and 4) . The comparisons 

 were made based on shoreline change from the 1983 surveyed shoreline posi- 

 tions. Figure 10 shows the shoreline change from the initial (Jan 1983) 

 shoreline position to the predicted 10-year (Jan 1993) shoreline position for 

 alternatives 2 and 4 presented in Figures 6 and 8. 



In all the preferred alternative simulations, there is a narrow region 

 of shoreline accretion adjacent the entrance jetties on both sides of the 



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