Geomorphological and Meteorological Control of Estuarine Processes: A Three-Dimensional Modeling Analysis

Abstract

The proper timing, duration, and direction of wind events interacting with the geometry of an estuarine system can control the intensity of stratification. A three-dimensional, time-dependent hydrodynamic model was used to examine this process. Intense mixing is closely tied with wind-generated internal velocity shear. A south wind generates up-estuary directed surface currents, which eventually leads to downwelling movements of water. This downwelling process in the upper bay region accelerates the bottom current in a down-estuary direction. A vertical instability occurs, especially in the upper bay region, due to the generation of shear across the pycnocline, causing mixing sufficient to destratify the entire water column. On the other hand, strong stratification occurs when a north wind advects fresher upper bay surface water into the lower bay. A downwelling movement of water is produced, which in turn drives bottom saline water in the up-estuary direction.