A Tidal Prism Water Quality Model for Small Coastal Basins

Abstract

A tidal prism water quality model (TPWQM) was developed to provide a tool for government agencies for water quality management of small coastal basins. It simulates physical transport using the concept of tidal flushing, includes one of the most sophisticated representations of eutrophication processes in water column and benthic sediment, and employs an innovative solution scheme that is simple, accurate, and computationally efficient. The predictive capability of the water column portion of TPWQM was demonstrated through successful calibration and validation of the model with extensive data sets collected from Lynnhaven Bay, Virginia. The model's general applicability was examined for four other Virginia coastal basins. One value (0.3) of the returning ratio, the only calibration parameter for physical transport, is applicable to all five coastal basins and probably would be adequate for other Virginia coastal basins without further calibration. The values of kinetic parameters determined for Lynnhaven Bay are applicable to at least two of the other four coastal basins. The model underpredicts chlorophyll-a, total carbon, and total phosphorus in two of the tested basins, which is more likely the result of underpredicted nonpoint source loads than the inaccuracy of the kinetic coefficients. Therefore, the set of kinetic coefficients may be applicable to all the Virginia coastal basins with basin-specific refinement in the estimation of nonpoint source loads.