Kings Bay, Cumberland Sound, Georgia part II : numerical modeling

Abstract

As a complement to field measurements of waves, surface tides, currents, and sediment transport, numerical modeling of King's Bay/ Cumberland Sound was initiated. Diagnostic numerical models 1 (both 1- and 2-dimensional) were applied to determine their applicability to estuaries of the same scale as King's Bay. One-dimensional models showed the estuarine system to be ebb-dominant, in accord with observations. This model did not reveal any extreme system sensitivity to changes in channel geometry on the scale expected from maintenance dredging. The two-dimensional model (a finite element model having a moving boundary formulation) was run to examine its applicability for diagnostic modeling of these systems. Preliminary results indicate the method is promising, but some model developments are indicated. Suggested model developments include: semi-implicit algorithm to reduce run-time: mass-conserving boundary conditions at tidal boundaries: implementation of a two-level momentum equation: algorithm development to extend the deforming element concept for smaller estuarine space scales: and formulation of a comprehensive interactive graphical package to facilitate model formulation, boundary and domain gridding, and presentation of results. This latter graphical task is essential for successful application of these numerical models. Results from these studies suggest that diagnostic models of shallow estuaries will be a valuable tool to be used in conjunction with more expensive "predictive" models, to understand circulation and transport processes under natural and impacted conditions.