Research On The Dynamic Flood Control Capacity And Flood Control Operation Of The Three Gorges Reservoir

The flood control capacity of the Three Gorges Reservoir has important influence on the flood control safety of the middle and lower reaches of the Yangtze River.It is a typical river type reservoir,so it is more close to the actual situation to fully consider the effect of the total capacity(i.e.dynamic capacity)of the reservoir below the water line on flood regulation during the flood period.The flood control capacity of the Three Gorges Reservoir is in accordance with the method of considering the effect of static capacity on flood regulation in the preliminary design phase.Later many experts and scholars study the method of considering the effect of dynamic capacity on flood regulation,but there is no unanimous conclusion.The Three Gorges Reservoir has an important role in flood control,so further studying its actual flood control capacity by using one dimensional unsteady flow dynamics model,the monitoring data of the normal operation period of the Three Gorges Reservoir and the high precision terrain data is of great significance for flood control operation in the case of catastrophic flood.This paper studies a one-dimensional unsteady flow dynamics model based on Saint Venant equation and researches the method of considering the effect of dynamic capacity of the Three Gorges Reservoir on flood regulation.By enlarging the flood in 1954 as a design flood,analyzing the actual flood control capacity of the Three Gorges Reservoir and discussing its flood control operation in the case of catastrophic flood.The main work and conclusions are as follows:(1)Establishing a one-dimensional unsteady flow mathematical model and applying it to the flood regulation calculation of the Three Gorges Reservoir by using the method of considering the effect of dynamic capacity on flood regulation.Calculating the reservoir capacity curve according to the high precision DEM data and correcting the effect of the actual terrain on the model calculation,so improving the accuracy of the model in the calculation of flood regulation by considering the natural reservoir capacity in the flood regulating calculation.The model is verified by the measured data and the result shows that it has higher accuracy and can meet the requirements of flood regulating calculation.(2)Obtaining the design floods which frequency are respectively 1% and 0.1% by enlarging the flood in 1954 and using the model to simulate the flood regulation process according to the Three Gorges flood control dispatching rules.The calculation results show that the actual flood control capacity is 22.446 billion cubic meters,so it is largely the same as the design flood control capacity which is 22.150 billion cubic meters and can meet the requirements of the Three Gorges flood control task.And the influences of roughness and actual terrain on the calculation results are studied,and the research results indicate that the error caused by roughness has the very small impact on the dynamic flood control capacity and the influence of actual terrain must be considered in the calculation process.(3)Studying the water level discharge relationship in Shashi and the flood diversion caused by Songzi,Taiping and Ouchi.And designing two different ways of flood control operation for the design flood which frequency is 0.1% to ensure the highest water level of Shashi is less than 45.0 m so as to ensure the safety of Jingjiang dike.Flood control operation scheme 1: the highest water level in front of the dam is 175 m and using the Three Gorges Reservoir and the Jingjiang Flood Diversion Area to ensure the safety of water level in Shashi.Flood control operation scheme 2: improving the water level in front of the dam(not higher than the check flood water level)to ensure the safety of water level in Shashi without using the Jingjiang Flood Diversion Area.Through the analysis of the results of the two flood control operation schemes,it can be known that the flood control task can be completed independently by the reasonable regulation of the Three Gorges Reservoir in the case of some catastrophic floods so that to avoid loss caused by using the flood diversion area.