Comparison of one- and two-dimensional models for simulation of hydrodynamics and water quality in shallow bays

A two-dimensional (2-D) vertically-averaged finite element model suite was adapted to investigate the hydrodynamics, water quality (WQ), and sediment-toxicant transport in San Diego Bay. The hydrodynamic model was calibrated and verified with two sets of observed data. Model predictions were also compared with the results from a previous study wherein a one-dimensional (1-D) finite difference approach was used. The 2-D model predictions of water surface elevations and velocities at specified locations in the bay were generally superior. The results of simulation of WQ constituents (temperature, nitrate-nitrogen, algae, and dissolved oxygen) using the 2-D WQ model compared well with the results from the I-D WQ model, both in the general trend as well as the specific distribution of constituent concentrations. Investigations were also carried out to determine the spatial and temporal distribution of sediments and a hypothetical sediment-borne toxicant in the bay. Results were found to be in general agreement with conclusions drawn from the hydrodynamic study.