On The Spatial And Temporal Variation Of The Recession Zone And Other Parameters Of The TGP Reservoir

After the reservoir impoundment of the Three-Gorges Project (TGP), a fluctuating zone, named as recession zone, shifting up and down to the pool surface along the edge of the reservoir will be formed, because of the adjustment of the pool levels for flood control. The vertical range of this area will be more than 30 meters. Consequently, eco-environmental problems may be brought about to this area due to sediment deposition, geologic disaster, soil loss and water pollutions. This area covers a large region of land and many people may depend upon it for their life. In order to protect environment and water quality of this area and the reservoir as a whole, and to guide the people to utilize the land within this area in a better way, advanced management becomes very important. For this purpose, the spatial distribution and temporal variation of this area are very important information.Based on 1:5000 and 1:250,000 DEM data and a hydrodynamic model of TGP reservoir, an information management system for the recession zone of TGP is preliminarily developed by applying the Arcengine tool, a Component Object Model technique of GIS. In this system, some common control functions in GIS are contained, such as zoom in, zoom out, and pan, etc., and the characteristics and distributions of the recession zone caused by the water level variation can be analyzed. This report analyzes the characteristics and distributions of the recession zone in two different operation schemes including optimized operation scheme and the current scheme. As a result, it is concluded that the optimized operation can reduce the recession zone for about 14 percents compared to the current scheme, which is meaningful for a better eco-conditions of the TGP reservoir.The capacity of TGP reservoir is a essential parameter for flood defense and power generation. The reservoir capacity and the representation of the cross-sections of the reservoir based on which the hydrodynamic model is founded are verified based on the 1:5000 DEM data. It shows that the reservoir capacity used in the design stage is smaller than it should be and the representation of the cross-sections need further adjustment in future development of mathematical models.