Cumberland Sound and Kings Bay Pre-Trident and Basic Trident Channel Hydrodynamicand Sediment Transport Hybrid Modeling. Volume 1. Main Text and Appendixes A, C, and D

摘要

A previously verified hybrid modeling system (coupled physical and numericalmodels) of the Kings Bay/Cumberland Sound Georgia estuarine system was used to investigate hydrodynamic and sedimentation variations associated with Trident channel expansion. The models generally demonstrated small velocity differences between the pre-Trident base channel condition and the enlarged Trident channel condition tested. Reduced velocity magnitudes in the deepened upper Kings Bay turning basin demonstrated the largest base-to-plan velocity differences. The deepened and widened Trident plan channel increased flood and ebb volume transport efficiency of the submarine channel through St. Marys Inlet into Cumberland Sound and Kings Bay. Increased discharge through and past Kings Bay changed phasing relationships north of Kings Bay. Although not an explicit objective of the modeling efforts, Tidal effects were also examines. The tested plan condition resulted in higher high-water and midtide level elevations in both the physical models. It was concluded that tide range will probably not change as a result of the Trident channel improvements. Subtle base-to-plan hydrodynamic differences and increased plan channel area resulted in dramatic sedimentation responses. The typical annual plan channel maintenance dredging requirement is predicted to vary form a low of about 0.9 million cu. yds per year to a high of about 4.9 million cu. yds/year. The long-term average submarine channel maintenance is predicted to increase from approximately 1.0 million cu. yd/year for pre-Trident channel conditions to approximately 2.5. million cu. yd/year for the Trident channel condition.