A semi-implicit three-dimensional hydrodynamic model incorporating the influence of flow-dependent eddy viscosity, bottom topography and wave-current interaction

A semi-implicit finite difference three-dimensional hydrodynamic model taking into account the effects of wave-current interaction through the bottom boundary layer and the influence of flow-dependent eddy viscosity and bottom topography is developed. The σ-coordinate system in the vertical direction is introduced for the accurate definition of the bed and surface boundary conditions. The effectiveness of the model is verified by comparing the computed circulation in an idealized estuary with that by others. Application of the model to the northern South China Sea is also carried out for the hindcasting of a storm surge event. It is found that the inclusion of constant wave effects in the hydrodynamic model cannot improve the prediction of surge levels. A wind wave model should be used in conjunction with the hydrodynamic model if prediction is to be improved.