Similar observations can be made with the pair of stations with positions 

 corresponding to the sta 1 current meter location, where the average-peak current at the 

 acmal site was approximately 25 cm/sec, versus 15 cm/sec at its complementary site in 

 the proposed GIWW (Figure 44). Time-averaged velocities at these locations were 



13.7 cm/sec for the existing sta 1 site as opposed to 10.8 cm/sec for the numerical station. 



At the eastern island locations, the average-peak water velocity computed off the 

 existing island was approximately 35 cm/sec (Figure 45). The average-peak current 

 experienced at its complementary site at the proposed Simdown Island was 

 approximately 25 cm/sec, or 10 cm/sec less than at the existing island. Time-averaged 

 velocities at these locations were 18.5 cm/sec for the existing site as opposed to 



12.8 cm/sec for the numerical station. 



The last pair of sites Ue on the opposite side of their respective islands from the 

 waterways. The peak current computed south of the existing island was approximately 

 60 cm/sec, whereas peak velocity was approximately 12 cm/sec at its complementary 

 station located south of the proposed island (Figure 46). Time-averaged velocity for the 

 existing site was 18.1 cm/sec, whereas the average velocity for the proposed site was 

 7.8 cm/sec. 



ImpUcations of these calculations are very favorable for relocating the GIWW 

 northward to its pre-1942 route. The sediment transport rate, whatever type of formula 

 appUed, is a nonlinear function of the magnitude of current velocity. A typical value 

 would be velocity raised to the power of three, or velocity cubed. From the above 

 figures, current velocity at complementary points adjacent to the GIWW indicate a 

 decrease in peak current of more than half, giving an estimated reduction in the transport 

 rate by the crosscurrent of one-eighth. In general, the magnimde of the crosscurrent 

 along the relocated route of the GIWW is significantly less than at the present location of 

 the GIWW near the corresponding MSC-GIWW intersection. Thus, based on 

 calculations of the current, the sediment transport rate and shoaling rates in the relocated 

 GIWW wiU be approximately an order of magnitude less than at the present location. 



Chapter 3 Circulation Modeling 45 



