A Coupled Wave-Current Numerical Model In The Storm Surge Process

The wave, tide and storm surge are the most important dynamic processes in nearshore zone, these three dynamic factors interact in different ways in the storm surge process. To simulate the current and wave conditions accurately for further studies such as sediment transport and pollutant movement, the interactions between the three factors should be taken into account. To complete this goal, a coupled numerical model of waves, tide and storm surge is developed in this thesis. The model is used to study the mechanism of wind wave evolution and wave-tide-surge interaction on the very mild slope.In order to simulate and predict the wind wave generation and evolution on very mild slope accurately, many runs of the SWAN model are performed to understand its sensitivity to temporal, directional and frequency resolution. The sensitivity of the SWAN model results to various energy dissipation formulae and control parameters are analyzed in this thesis. Based on the simulated results, more suitable sets are recommended for very mild slope according to field data. The results computed with the tuned sets are in good agreement with measured data.To simulate the wave-current interaction on surge, a wind drag coefficient formula and a bottom drag coefficient formula, taking into account the wave-current interaction, are introduced to the ADCIRC model. Then, the improved ADCIRC model is coupled with the SWAN model to establish a wave-current coupled numerical model that considering all wave-tide-surge interactions.Through simulation of two extratropical storm surge processes with the coupled numerical model, the mechanisms and magnitude of wave-tide-surge interaction are studied in this thesis. The comparison between computed and measured wave height and tide-surge elevation indicates that the coupled model is more accurate than the uncoupled one.