Study On Optimization Of Operation Mode Of Silting Basin For The Project Of Yellow River Diversion Into Hebei

Downstream of Yellow River has more sediment and higher sediment concentration.With the operation of water diversion and the sedimentation of sedimentation basin,the discharge capacity and sedimentation effect of sedimentation basin decrease.which is not conducive to the implementation of water diversion task of the project of diverting Yellow River into Hebei.Therefore,it is necessary to take measures to improve the current situation of difficult water diversion and poor sediment settling effect.In this paper,taking the sediment basin of Yellow River Diversion Project as the research object,the relationship between supply and demand is obtained through the analysis of the water supply capacity of Yellow River diversion mouth and the water demand of the receiving area.In order to determine the water and sediment combination and diversion time under different schemes.This paper mainly uses Mike21 software.By comparing the characteristics of flow field distribution,sediment concentration change and sediment deposition law of each scheme,the sediment settling effect of different schemes is analyzed.The reasonable optimization scheme is put forward to provide scientific basis for the operation mode of desilting basin in the future.The main research results of this paper are summarized as follows:1)With the increase of the operation time of the desilting basin,there are different degrees of siltation in the channel.The sediment is mainly deposited in the middle and upper reaches.The maximum deposition thickness of about 3.5 m.The siltation on the left side is slight.Under the condition of actual water and sediment diversion in 2019,the annual deposition of one channel in the desilting basin is about 3.32 million m~3.And the service life of a single channel is less than one year;2)According to the analysis of water supply and demand balance of water supply area and water receiving area,the water sediment combination and water diversion time in wet year,normal year and dry year are determined.In the case of single channel operation,the amount of sediment deposition in wet year and dry year increases by180,000 m~3and 150,000 m~3 respectively in the case of high outlet water level operation(scheme 1)compared with that in the case of low outlet water level operation(scheme3).When the outlet water level is low,the deposition distribution in wet year and dry year is improved.In the case of double channel operation,the amount of sediment deposition in wet year and dry year is increased by 190,000 m~3 in the case of high outlet water level operation(scheme 1)compared with that in the case of low outlet water level operation(scheme 3);3)Determine the optimal operation plan.In wet year,normal year and dry year,single channel operation mode of desilting basin is recommended under different incoming water and sediment and diversion time.Within the scope of the design scheme,lowering the outlet operating water level can improve the sediment settling effect.