Study On High-Efficiency Sediment Discharge Of The Santou Section Of The Inner Mongolia Reach Of Yellow River

In the current situation of water resources shortage,it is necessary to solve the problem of high efficient sediment transport and discharge in river channels in order to reduce siltation and discharge sediment in river channels or diversion channels.However,because the sediment transport in the river is the result of the complex process under the action of many kinds of factors,it is a difficult problem to understand the regulation of sediment transport in the river,which also hinders the study of the high efficient sediment transport in the river.In this paper,based on the calculation model of sediment transport based on the parameters of bed making discharge proposed by Qin Yi and Li Ziwen,it is analyzed and determined that the river reaches will not be silted up under the condition of different bed making flow from Sanhu Estuary to Toutou River reach(Santou reach).Water and sediment conditions and flood duration with large sediment transport and high efficiency,which is favorable condition of sediment transport and High-Efficiency Sediment Discharge.In addition,from the point of view of the randomness of sediment transport in river,the probability analysis of variable factors related to sediment transport is carried out by Copula function theory.A joint Copula function is established and based on the condition probability analysis,the sediment transport capacity,unit sediment transport volume and the sediment yield of the river are analyzed by conditional probability analysis.The results obtained by the above two methods,are consistent,and are consistent with the actual sediment transport and the river bed evolution under the same conditions.The main conclusions obtained are as folllows.1)Based on the analysis of sediment transport model based on the bed-making flow rate,there is the most efficient and unique sediment transport flow for each bed-making flow,and the channel is most likely to be scoured at this flow rate.Under the condition of high efficient sediment transport flow,the amount of sediment coming from the upper station determines the situation of river channel scouring and silting.The higher the sediment content of the upper station is,the more easy it is to silt,otherwise,the more easy it is to scour.Based on the analysis of the sediment transport model,it is possible to calculate the high efficient sediment transport discharge and the conditions of water and sediment collocation in the future Santou river under the condition of various bed making discharge.The test results show that the results of sediment transport and riverbed evolution are in good agreement with the actual conditions,and the model has good prediction ability.2)Based on the Copulas function theory,a two-dimensional Copula function for sediment transport and unit sediment transport is established.Three dimensional Copulas function between sediment transport and discharge and sediment content at upper station.Based on the maximum probability of sediment transport and the amount of water per unit of sediment transport,the maximum discharge under the condition probability is obtained,and the sediment content at the upper station is the combination condition of favorable channel and high efficient sediment transport.In comparison with the actual sediment transport under the same conditions,it is found that the maximum probability per unit of sediment transport is high efficiency in the Santou reach.3)The analysis of high efficiency sediment transport condition based on sediment transport model is consistent with the maximum probability theory analysis based on Copulas function.And consistent with the actual sediment transport that has occurred.The conclusion is reasonable and credible.The two methods mentioned above can be used to calculate the high efficient sediment transport flow in the channel.However,based on Copulas function analysis,the actual data should be used as the basis,and the situation under the condition of non-occurrence inconsistency(multiple bed flow)can not be forecasted.That is to say,it is impossible to analyze the high efficient sediment transport flow of river bed with different bed-making flow.The sediment transport model can solve the prediction problem.4)The conditions of high efficiency sediment transport in the river are as follows:using 15 days of flood to transport sediment,the current bed-making discharge Qc=1500m3/s,the high efficiency sediment transport flow is 900 m3/s?1000 m3/s,the sediment content of the upper station is 5 kg/m3?6 kg/m3,the sediment output of the reach is about 6 million t,and the unit sediment transport capacity is about 170?200m3/t.With the adjustment of the river bed,the future bed making flow will increase.When the bed making flow increases to 2500 m3/s,the high efficiency sediment transport flow will be about 1500 m3/s,the sediment content of the upper station will be about 8 kg/m3,the sediment output of the reach will be about 15 million t,the unit sediment transport capacity will be about 128 m3/t.When Qc=3500 m3/s,the flow rate is 2000 m3/s?2200 m3/s,the sediment content at the upper station is 7?10 kg/m3,the sediment output of the reach is about 27 million t,and the unit sediment transport capacity is 90 m3/t?100 m3/t.As the river bed adjusts,the more efficient sediment flow is needed,the more efficient sediment transport is required.The upstream reservoir can be adjusted to maintain the health of Santou reach.