Figure 37. Current vector map for proposed GIWW relocation 



Comparing time series of currents calculated at the western island locations, the 

 average peak current at the existing island was about 50.0 cm/sec, whereas the average 

 peak current at the proposed island was 17.5 cm/sec, or 32.5 cm/sec weaker (Figure 38). 

 The differences in currents are presented in Figure 39, which were computed by 

 subtracting, for each entry in the time series, the existing-configuration current from the 

 proposed-configuration current; negative values of the current contained in this plot 

 correspond to the existing-condition current being greater than the proposed- 

 configuration current. The current is reduced because the water flows over an 

 increasingly wider area. Time-averaged currents at these locations were 22.7 cm/sec for 

 the existing site as opposed to 13.3 cm/sec for the numerical station. 



Comparing time series of currents computed at the MSC-GIWW intersection, 

 presented in Figure 40, the average-peak current at the existing intersection was about 

 30.0 cm/sec, whereas the average-peak current at the proposed intersection was 

 20.0 cm/sec, or about 20 cm/sec less. Weaker currents at the proposed site can be 

 expected because it is simated about 13,000 ft from the bay side of the MSC entrance, or 

 approximately 7,000 ft to the north-northwest from the existing intersection. Time- 

 average currents at the existing and proposed sites were 20.3 and 15.3 cm/sec, 

 respectively, and differences in currents are presented in Figure 41. The MSC is an 

 efficient conduit for water flow because of its depth. The predominant component of the 

 current in the MSC is along its axis, which plays a major role for moving sediment into 

 the channel. 



For the pair of stations residing between the GIWW and the islands, the average-peak 

 current north of the existing island was about 35.0 cm/sec, whereas the average-peak 

 current for the complementary site south of the proposed island was 17.5 cm/sec, or 

 17.5 cm/sec weaker (Figure 42). Differences in current are presented in Figure 43. 



Chapter 3 Circulation Modeling 



41 



