Abstract: In this paper, we established a three dimensional hydrostatic equilibrium airsoil coupling model in G―Chen coordinates system which fully contained the thermal and dynamic process of terrain, vegetation and water surface in detail. The unique characteristis of this model are that the influence of terrain had been considered in the radiation and energy balance equations of forest crown canopy and land surface. The observation showed that the daily variation of river surface temperature is below 3℃. The rushing water of Three Gorges of Yangzi River is full of turbulence. The depth of the river is different everywhere. These make the simulation of thermal and dynamic process of water very difficult. We neglected the daily variation of river temperature. In our study the changes produced by the formation of the reservoir is only the elevation of water surface and the extent of its water surface area. The water surface temperature is a constant.We use this model to simulate the diurnal variation of meteorological elements field before and after the formation of the Three Gorges Reservoir. Then we calculated their differences and analyzed the microclimate Produced by the formation of of the reservoir. The result shows that the temperature, wind and humidity field will be changed in the near area within ten kilometers away from Three Gorges Reservoir, but with a rather limited degree.

Key words: quasistatic equilibrium, Three dimensional air soil coupling model, Three Gorges Reservoir, microclimate effect