Wetting and drying simulation of estuarine processes

To simulate transport and thermal processes in shallow estuaries, a hydrodynamic model within the framework of the Environmental Fluid Dynamics Code (EFDC) has been developed and applied to Morro Bay, California. For this modelling study, comprehensive field samplings were conducted to record the wetting and drying processes in detail. The bay features a shipping channel with localized rapid topography variations, and flat and shallow topography in the rest of the area. At low tide, more than 60% of the bay area emerges and becomes dry. The Morro Bay Model contains 1609 curvilinear grid cells with resolution varying from 50 to 110 metres. The bay is well mixed vertically and is represented using a single vertical model layer. For computational efficiency, a wet cell mapping technique is implemented in the model. The primary model hydrodynamic forcings included open boundary tidal elevations, freshwater inflows from two creeks, and surface wind stresses. The measured data for model calibration include tidal elevation, current velocity, water temperature, and salinity at six locations for 31 days, from March 9 to April 10, 1998. Comparison between model results and data indicates that the model results match the data reasonably well. The model also simulates the wet and dry processes in Morro Bay realistically. As an application of this calibrated model, a flushing analysis is conducted to determine which areas in Morro Bay are susceptible to poor flushing. It is concluded that the hydrodynamic model presented in this paper can be a useful tool for studying the wetting and drying processes in shallow estuaries. (C) 2001 Academic Press.