Hillsborough bay inflow modification study: An application of the Tampa Bay Coastal Ocean Model

Abstract

With a large salinity gradient existing between the rivers and the ocean, the saline environment of an estuary is crucial to its ecosystem functionality. For Tampa Bay, the Howard F. Curren Advanced Wastewater Treatment Plant (HFCAWTP) presently yields an outflow of nearly freshwater to the Hillsborough Bay portion of Tampa Bay. In order to estimate the potential impact that the removal of this outflow may have on the salinity and flow fields of Hillsborough Bay, as part of the Tampa Augmentation Project, both numerical circulation model and Knudsen theorem applications are made. The numerical model study compares the instantaneous and nontidal, mean estuarine circulation and salinity distributions for the Hillsborough Bay on the basis of the HFCAWTP outflow being either included with, or excluded from, the freshwater inflows. It is found that the potential reduction of the treated reclaimed water inflow to the bay from the HFCAWTP will not significantly affect the circulation or the salinity distributions of Hillsborough Bay or of the larger Tampa Bay. The estimation through a Knudsen theorem application shows an 0.13 psu increase of salinity after removing the HFCAWTP outflow when averaged within Hillsborough Bay. Thus, both approaches demonstrate that the effects of HFCAWTP outflow removal are very small when compared with variations that occur naturally.