| Because of the limitation of observing conditions and availible data, the previous research about characteristics of tidal current has been emphasized on two aspects. The first one is the calculation and discussion on the tidal harmonic constant, and the other is the comprehension of characteristics of tidal current in local sea area. However, both of them are lack of systemic inspection about the characteristics of tidal current in the whole sea area. Based on numerical models for the tidal wave of Bohai Sea, the characteristics of real tidal flow field in the whole Bohai Sea are analyzed and a tidal forecasting system for Bohai Sea is designed, which will provide a valuble data for applicated simulation of port and coastal engineering in Bohai Sea. The main contents and conclusions are as followings.1. Firstly, a numerical model for the tidal wave of margin seas near China coasts is constructed for trying to provide an exact boundary condition for the numerical model of the tidal wave in Bohai Sea. The numerical model of margin seas near China coasts is developed in this paper based on the 2-D depth-averaged tidal wave motion equation in spherical coordinates, and region in study included the Bohai Sea, the Yellow Sea, the East China Sea, the South China Sea, Thailand Bay and waters around Taiwan Island. The computational grid is generated as triangular grid base on finite volume method. The model simulated the compound tidal wave movement of margin seas near China coasts. However, because of the inaccurate data on the bathymetry in the shallow water, the result is not satisfying. The surface elevation of M2 tide components dominated by semidiumal tide in Bohai Sea seems to be smaller than actual value, but the surface elevation of K1 tide components dominated by diurnal tide in Nanhai Sea seems to be larger than actual value. Therefore the surface elevations obtained from global tidal forecasting system are taken as the driving boundary for numerical models of the tidal wave in the Bohai Sea.2. For the simulation of the tidal wave in Bohai Sea, two models are employed: 2D-hydrodynamic numerical model in the software of MIKE21 based on the finite volume method and ADCIRC model base on finite element method. The results tend to be consistent with each other. The amplitude and phase of M2 and K1 tide components fit well with actual observed value. Based on the result, the cotidal charts for the main tide components including the shallow water tide components (M4 as an examle) are drawn, and a comparative analysis about the surface elevation, current speed and current direction in 12 tidal forecasting stations and 13 tidal current forecasting stations listed on the Bohai Sea tide table is carried out. Also the results and observations of the tide in Bohai Bay and Laizhouwan are respectively analyzed in detail. A systemic discussion on the distribution of tide and current in Bohai Sea is made, which is consistent with the previous researches. In the analysis about the flow field in Bohai Bay, it is found that the direction of current curl and spring-ebb tide in the northern top of Bohai Bay is different from other sea area in Bohai Bay.3. Finally, the tide forecasting system of Bohai Sea is designed based on the result of tidal wave numerical model of Bohai Sea. The comparison between the simulated and measured data during two years further validates the practicability of the forecasting system with high accuracy in shallow water.
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