Imperial River and Estero Bay Circulation: Estimation of Pressure Gradient and Frictional Forcing Based on Flow Monitoring

Estuaries are dynamic water bodies with numerous physical and chemical influences dominated by estuarine circulation. The ecosystem is highly sensitive to circulation changes, which itself is controlled by tides, wind, and river hydrology (Geyer 2010). Frictional drag and barotropic and baroclinic pressure gradient forces were quantified to determine the tidal dominance in driving circulation within Estero Bay, Florida and the lower reaches of the Imperial River that joins into the estuary. As freshwater input for this estuary is seasonal in nature, tides control the estuarine dynamics, particularly during the dry season. The study made an attempt to evaluate the tidal circulation characteristics of this shallow estuary during spring and neap tidal conditions. The study concluded that the lower reaches of the Imperial River and the southern end of the Estero Bay experience low salinity due to their remoteness from the tidal inlets. Barotropic pressure gradient force is at least 2 orders of magnitude higher than the baroclinic pressure gradient in this section of the bay, indicating that the water column is more mixed. Additionally, bottom frictional drag was higher during the late ebbing phase of the spring tide, when the water level was at the lowest.