| Haibowan Reservoir is located on the main stream of the Yellow River in Inner Mongolia.It plays an important role in preventing flooding and generating electricity.Since the operation of the reservoir,the problem of sedimentation has been serious,which has brought a series of impacts on the flood prevention,flood control and ecology of the reservoir and the Inner Mongolia section of the Yellow River.Reservoir water and sediment dispatching is an important means to control sediment deposition and maintain effective storage capacity.This thesis is based on the hydrological data of Haibowan Reservoir from2014 to 2021 and the measured water and sediment processes from 1960 to 2021 at four main stations in the Inner Mongolia main stream of the Yellow River.The characteristics of sediment deposition and sediment discharge in reservoir were explored by using the cross section topography method and correlation analysis.The improved Makaviev method,flat beach water level method and geomorphological method are used to calculate the bed-forming discharge of the Inner Mongolia section of the Yellow River,and then the discharge of the reservoir is proposed.The two-dimensional water and sediment model of reservoir plane was established based on MIKE21FM,three proposed water and sediment dispatching schemes were simulated and analyzed,and the optimal operation mode of reservoir water and sediment dispatching was proposed after comprehensive comparison.The main research results are as follows:1.Shizuishan Station has the characteristics of uneven distribution of water and sediment,uncoordinated relationship between water and sediment,and decreasing amount of water and sediment.Since the operation of the reservoir,212 million m~3 of sediment has been accumulated,accounting for 43.5%of the total storage capacity,mainly occupying the storage capacity below 1073m elevation.95%of the sediment is deposited in the range of0～18km from the dam,and the sedimentation form is mainly"silt trough".The average annual discharge ratio of the reservoir is 19.35%,which is much lower than the design value of 45.5%～53.6%.2.Considering the annual distribution characteristics of the water and sediment and the discharge time of the upstream cascade reservoir,the discharge time of the reservoir is selected from July to September.The bedmaking discharge of the Inner Mongolia section of the Yellow River ranged from 2,100 to 3,540 m~3/s from 1960 to 1989 and from 2010 to 2019,and the mean-water channel erosion was from 740 to 1,300 m~3/s from 1990 to 2009.The bedmaking discharge of 2620m~3/s from 2010 to 2019 was selected as the upper limit of discharge of reservoir water and sediment dispatching.Based on the occurrence days of multi-year water and sediment characteristic values and the proportion of sediment in Shizuishan Station,it is proposed that the discharge of water and sediment dispatching in the reservoir is graded with 1500m~3/s and 2760m~3/s as nodes,and the discharge sediment content is graded with 3kg/m~3,5kg/m~3 and 10kg/m~3 as nodes.3.The simulation results of reservoir water and sediment model are in good agreement with the measured data,and can simulate the process of reservoir sediment erosion and deposition.By comprehensive comparison of the remaining effective storage capacity and power generation of the three schemes,it is concluded that when the inflow flow is1500～2760m~3/s and the sediment concentration is 5～10kg/m~3,the effective storage capacity of the scheme which reduces the water level to 1072m for sediment discharge is 97 million m~3 after 15 years of operation,and the average annual power generation is 389.5 million k W·h,which is superior to the existing sediment discharge scheme.It is recommended to be the water and sand dispatching mode of Haibowan Reservoir. |
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