A time-varying three-dimensional numerical hydrodynamic model of Chesapeake Bay in Maryland has been developed to provide flow fields to a 3-D water quality model of the bay. The water surface, 3-D velocity field, salinity, and temperature are computed. Major physical processes affecting bay circulation and vertical mixing are modeled. A particular feature of the model is the solution of transformed equations on a boundary-fitted grid in the horizontal plane. The 3-D model has been validated through application to six data sets. The first three were about one month long each and represented a dry summer condition, a spring runoff, and a fall wind-mixing event. The last three applications were yearlong simulations for 1984, 1985, and 1986. These years represent a wet, dry, and average freshwater inflow year, respectively. A major storm in November 1985 over the lower portion of the bay resulted in a 200-year flood on the James River and served to demonstrate the ability of the model to simulate extreme events. Selected results from application to the fall 1983 data and from the yearlong simulations are presented here. These results demonstrate that the model is a good representation of the hydrodynamics of the Chesapeake Bay and its major tributaries.
