Research On Approximate Calculation Method Of Dynamic Storage Volume Of The Three Gorges Reservoir

The construction of the Three Gorges Reservoir is pivotal project to management and exploitation of the Yangtze River,which plays an important role in socioeconomic development of China.Since it was initially built and applied in 2003,the intents of flood control generate electricity and shipping was achieved progressively.The Three Gorges Reservoir is typical large river-channel type reservoir in mountainous area with narrow reservoir,obvious gradient of backwater's water line caused by flow and much higher water level of reservoir tail than dam front,therefore storage capacity can't be calculated by the static storage method,but backwater storage which can reflect changes of water line.As the primary objective of the Three Gorges Reservoir,flood control plays an important role in safety and construction of the Yangtze River plain,and storage is a critical factor in reservoir flood control,which directly influences the development of flood control scheme.What's more,the Three Gorges Reservoir has area of 700 km with complex terrain and water condition;so many factors could influence the calculation of backwater storage,which can't be determined accurately.Therefore,it has significant theoretical and practical significance to find a method of calculating the backwater storage of the Three Gorges Reservoir exactly.Here,we studied the calculation method of backwater storage for the Three Gorges Reservoir with the mathematical model of one-dimensional flow,theoretical analysis and mathematical analysis.The major contents and results are as follows:Collected topographic and hydrological data of the Three Gorges Reservoir,studied its hydrological characteristics,such as overview of the reservoir,flood situation and changes of inflow discharges and water level.Identified two factors affecting the backwater storage of the Three Gorges Reservoir,dam water level and traffic,by analyzing changes of water level since it run and literature.Built a one-dimensional mathematical model of the flow according to the measured data,and compared calculated water line and the measured values,which matches well and can be used in the backwater storage study below.According to the hydrological and topographical data of the Three Gorges Reservoir,developed reservoir segmentation scheme,analyzed and compared,and ultimately determined to divide the reservoir area into six sections.Combined segmentation scheme with mathematical models,and calculated the backwater storage values under different water flow,then fitted the calculation formula of each segment via mathematical analysis of calculated backwater storage value.Ultimately obtained simplified formulas of backwater storage for the mainstream of the Three Gorges Reservoir.Based on the obtained calculation formula of backwater storage for the Three Gorges Reservoir mainstream,studied its discipline of dynamic flood control capacity,and analyzed the relationship between backwater storage and storage capacity under different conditions.According to the obtained calculation formula of backwater storage for the Three Gorges Reservoir mainstream,calculated its dynamic flood control capacity in the actual scheduling when suffer different frequency flood,and studied changes of dynamic flood control capacity.