The Research On Risk Operation Of Intercepting And Storing The Flood Tail For Shiquan Reservoir

The conventional flood control operation manner applied in Shiquan reservoir, i.e. the operation manner according to the flood control level, that is with lesser consideration on the telemetering technique of water and rainfall regime and the function of flood forecasting and operation system. The inflow volume of Shiquan reservoir from July to September is about 75～80 % of the annual runoff volume. If missing the chance of storing water in the major flood period, the reservoir water level will have difficulty in storing in normal storage level. With the change of upstream natural characteristics affected by the human behavior, the runoff and the characteristics of flood and reservoir and power station have already changed. Owing to the causes, the risk operation manner of Shiquan reservoir is studied. It is based on the forecasting information of rainfall and runoff and the reservoir safety, by intercepting and storing some water in the flood tail and reducing the water level to the flood control level by means of the power generation. So the flood resources are fully utilized and seasonal power energy is gained. The operation scheme in major flood period for Shiquan reservoir is esTablished. The main contents and conclusions are as follows in the paper:(1) By collecting the status of flood forecasting and operation system of Shiquan reservoir, the reservoir characteristics data, discharging capacity curve of the flood discharging structures, the time of runoff generation and concentration and the downstream maximum allowable safety flow, the storage capacity and flood discharging capacity are analyzed. Whether the over-impoundment operation for Shiquand reservoir by intercepting and storing the flood tail is necessary and feasible is discussed.(2) Using the mathematics and statistics theory, the probability of flood times, the flood statistical characteristics and law in the year, the probability distribution of the magnitude of flood, intervals probability between flood peaks, intervals laws between floods and the peaks characteristics and drawdown characteristics of floods are analyzed respectively.(3) The Least variance fitting period method is used to diagnose and distill the period component of the time series of hydrological factors. The Diagnose-Distill-Prove model is esTablished and the prediction model of runoff year type and flood indices are presented in the paper.