^ 





Bay 







^1 ^^°°^ 

 \ Shoal 







J 





Ocean 







Ebb .,'' 

 Shoal 





Figure 47. Idealized flood-shoal development 



Flow 



Shoal 



Side View 



Flow 



■"'•ghannel 



Plan View 



Figure 48. Idealized channel infilling pattern by a current with 

 predominant flow direction 



In summary, long-term morphologic evidence indicates that both the GIWW and 

 Sundown Island are located too close to the MSC entrance and are in the range of a 

 strong, sediment-transporting flood current. 



Dredging record 



Analysis of dredging records for 1966 to 1995 indicated that the stretch of GIWW 

 north to northeast of Sundown Island (sta 612+000 to 616+000) is experiencing sediment 

 shoaUng that is increasing nonlinearly with time as approximately t . This and 

 neighboring sections of the GfWW had much increased shoaUng rates as compared 

 sections more distant from the MSC-GIWW intersection. The shoaling pattern is 

 consistent with previous inferences of sediment transport by the tidal flood jet; with 



Chapter 4 Summary and Recommendations 



49 



