Effect of Zhangfeng Reservoir to the Design Flood of Hekoucun Reservoir

As the key flood control project of the Qinhe River and an important part of the Yellow River flood control system,it is critical for the size of the reservoir and dam security to analyze and determine the design flood.The paper analyzed the natural design flood and the design flood combined with Zhangfeng on the Hekoucun Reservoir dam.The results of calculation show that when the flood composition of Wulongkou and Zhangfeng has the same frequency and Zhang-Wu reach is correspondence,the function of Zhangfeng Reservoir is increasing to the volume of design flood at dam site of Hekoucun Reservoir under the conditions of 2000-year flood and 500-year flood according to the operation order of flood detention first and then discharging by Zhangfeng Reservoir.The reduction of flood volume in 3 days of the inflow of Hekoucun Reservoir combined with the operation of Zhangfeng Reservoir under the conditions of 100-year flood and 50-year flood is 4% and 1% respectively.As for the composition of Wulongkou and Zhang-Wu reach having the same frequency and Zhangfeng correspondence,the Zhangfeng Reservoir has a certain reduction function on design flood peak of the dam site of Hekoucun Reservoir and there is no influence to the 3-day and 5-day flood volumes.