DIFFUSION HYDRODYNAMIC MODEL OF SHALLOW ESTUARY

Many of the hydrodynamic models used for estuary tidal flows and storm surges are based on a set of coupled two-dimensional hydrodynamic equ ations, which are obtained from the full three-dimensional flow equati ons by averaging the vertical coordinates. Various numerical technique s, such as finite difference, finite element, and the method of charac teristics, have been used to solve these equations. The diffusion hydr odynamic model (DHM) has been developed to simulate two-dimensional su rface-water and channelized flows. In a prior study, the DHM was appli ed to a deep-water estuary with computational results, comparable to t hose obtained using the St. Venant equations and the method of charact eristics. In this paper, the DHM is applied to a shallow estuary locat ed in southern California. The main objective is to determine local fl ow velocities and circulation patterns in the shallow estuary caused b y the incoming and the outgoing tide. Verification of the DHM is provi ded by comparison of tidal gage measurements and computed flow depths.