Reservoir regulation techniques for hyperconcentrated flows in the Lower Yellow River
Erosion and deposition in the Lower Yellow River is closely related to the incoming sediment coefficient of hyperconcentrated flood events.The average incoming sediment coefficient of typical hyperconcentrated floods entering the Lower Yellow River was in the range of 0.093 and 0.105.In flood seasons,the sediment deposition in lower reaches can reach 59％ ～62％ of the incoming sediment load if no reservoir regulation and no water diversion along the channel.Therefore,it is necessary to impound hyperconcentrated floods in order to reduce sediment deposition in the Lower Yellow River.But the consequences of increased deposition in the Xiaolangdi reservoir and reduced sediment load into the sea must be considered.A control index Y expressed by reservoir sediment release ratio was proposed.Calculation for representative flood series in the range of incoming sediment coefficients of the flood records indicated that a value of Y =2/3 can be adopted for normal reservoir operation.This may reduce deposition in the lower reaches (ensuring a sedimentation reduction ratio above 40％)and increase sediment load delivered to the sea,while reducing deposition in the Xiaolangdi reservoir as much as possible.In practice,the Xiaolangdi reservoir should be operated according to the control index depending on the value of incoming sediment coefficient prediction for floods.So far,sediment deposition in the Xiaolangdi reservoir already reached 30％ of the original design capacity of sediment deposition.The water level in flood seasons should be lowered in order to increase the sediment release ratio to a value of Y =2/3 in flood seasons,and to restrain the fast storage loss due to sedimentation.
Lower Yellow Riverhyperconcentrated floodincoming sediment coefficientreservoir regulationcontrol index
国家科技期刊平台
NSTL
万方数据
维普
