KINGS BAY COASTAL PROCESSES NUMERICAL MODEL 



PART I: INTRODUCTION 

 Background 



1. St. Marys Inlet is a large jettied tidal inlet through the barrier 

 island system of Georgia and Florida. It is the main entrance to Kings Bay 

 Naval Submarine Base located at Kings Bay, Georgia. The inlet is located 

 approximately 30 miles* north of Jacksonville, Florida (Figure I). The 

 Georgia-Florida state line runs through the inlet. To the north of the inlet 

 is Cumberland Island administered by the National Park Service, and to the 

 south is Amelia Island. Fort Clinch State Park surrounding historic Fort 

 Clinch is located on Amelia Island. 



2. At present, Kings Bay is home to Poseidon-class submarines. The 

 present entrance and offshore channels are trapezoidal in cross section with a 

 bottom width of 400 ft, a project depth of 40 ft mean low water (mlw**) , and 

 side slopes of 4H:1V. As a part of the upgrading of the submarine base to 

 receive the larger Trident-class submarines, it became necessary to widen and 

 deepen both the interior and exterior navigation channels. Simultaneously, it 

 is proposed to sand-tighten a 1,500-ft segment of the south jetty. This study 

 is mainly concerned with the exterior (entrance and offshore) channels. Here- 

 after the term "entrance channel" will be used to refer to the part of the 

 exterior navigation channel between the jetties, and the term "offshore chan- 

 nel" will be used to denote the part of the navigation channel offshore of 

 jetty tips. A companion study (Granat, et al., in preparation) considers the 

 interior channels. 



Purpose 



3. The purpose of this study is to determine the effect of the project 

 on coastal processes near St. Marys Inlet. The processes studied include 



* A table of factors for converting non-SI to SI (metric) units is presented 

 on page 6. 

 ** Abbreviations and acronyms are listed in Appendix B. 



