Integrated modeling of the Tampa Bay Estuarine System is conducted in an attempt to further the understanding of estuaries as integrated systems, and to provide quantitative assessment of various management practices. The primary objective is to use models and field data to produce a detailed characterization of the hydrodynamics and water quality dynamics within the system. To test the hypothesis that seagrass is a bioindicator of the overall health state of the estuarine system, a conceptual seagrass model is coupled to the hydrodynamics and water quality models. The integrated model is then used to study the effect of anthropogenic inputs to the estuarine system.

The hydrodynamics component of this integrated model has been successfully calibrated and verified using Tampa Bay data provided by the National Oceanic and Atmospheric Administration (NOAA) and the United States Geological Survey (USGS). The effects of hydrodynamics have been incorporated into the water quality model by using the same grid spacing and time step, hence eliminating the need for ad-hoc tuning of advective fluxes and dispersion coefficients. The water quality component has been tested using monthly water quality data provided by the Hillsborough County Environmental Protection Commission (EPC), although a more comprehensive data set is needed to fully validate the water quality model. Results of previous statistical and mass-balance models were used to determine the relevant biogeochemical processes, and to test causal relationships among state variables. These simple models also proved to be useful tools for calibration of the water quality model coefficients in the absence of process-specific data (e.g., remineralization, nitrification, and denitrification). Incident-light data provided by USGS allowed the calibration of a light model. The seagrass model has been used to investigate the ecological relationships between nutrient loading, water quality dynamics, and the response of seagrass.

Once validated, this integrated model can be used to determine nutrient loading reduction targets required to maintain and expand seagrass meadows in Tampa Bay. Simulated load reduction scenarios indicate that water quality can respond quickly (within 2 months), while seagrass responds more slowly (more than 6 months) to load reduction. Nevertheless, the results indicate that integrated modeling is a viable approach to provide quantitative assessment of various management practices for restoring estuarine systems.