Horizontal Salinity Gradient Effects in Apalachicola Bay

Abstract

This research demonstrates that horizontal density gradients approximated by salinity gradient represent an additional forcing term in the equations of motion, which have a significant effect in certain portions of a well‐mixed estuary. The horizontal density gradient terms have been added to a two‐dimensional depth‐averaged hydrodynamic and salinity model that is applied to Apalachicola Bay, Florida. A variable‐size finite difference cell is used in the model to allow more efficient resolution of physical details. The estuary system is assumed to be well mixed and boundary conditions are satisfied at the bottom and top of the water column but vertical components of velocity are neglected. A high‐resolution numerical model is desirable with particular emphasis on areas near passes, channels, and other critical features. This is accomplished by applying a smoothly varying grid technique. Results from the numerical model are presented and compared with prototype data. Calibration and verification of the improved numerical model is accomplished with available prototype data.