Research On Joint Operation And Spatial Equilibrium Allocation Of Water Resources In The Three Source Reservoir Group Of The Tarim River

Tarim River is the longest inland river in China.The natural precipitation in the basin is scarce,evaporation is large,and the spatial distribution of water resources is extremely uneven.With the rapid growth of population in the basin,the continuous expansion of cultivated land,the disordered development and inefficient utilization of water resources,and the long-term lack of rational allocation of water resources by controlled water conservancy projects,the contradiction of water resources utilization between the upper and lower reaches of the basin and between the left and right banks has become increasingly prominent,and the amount of water transported from the source to the main stream of the Tarim River has decreased year by year.Therefore,it is of great significance to study the joint operation of reservoirs in the Tarim River basin and the spatial balanced allocation of water resources.This article selects 2020 as the current year and 2030 as the planning year to jointly dispatch mountainous reservoirs,plain reservoirs,river water systems,etc.in different level years of the basin,establish hydraulic connections between surface water bodies in the basin,achieve water volume mutual aid between rivers and reservoirs,water volume mutual adjustment between rivers,and water resource complementarity between rich and dry seasons.By setting up a plan to consider the upstream and downstream of the basin All water users on the left and right banks can equally enjoy the water supply scheme set of water resources use rights,realize the balance of water supply for all water users in the basin,and improve the water volume of the three source streams discharging into the main stream of Tarim River.The main research content and achievements are as follows:(1)Based on the existing research results,analyze the basic situation of reservoirs in mountainous areas and plain areas in the three source streams of Tarim River,Yarkand River,Hotan River and Aksu River basins in the current year and planning year,and collect relevant data of reservoirs;Draw node maps of three source streams based on the distribution of water systems and water conservancy projects in the watershed;Collect and organize monthly scale data on watershed runoff,irrigation area water demand,ecological water demand inside and outside the river channel,and discharge of the main water volume of the Tahe River.(2)Based on the actual situation of each watershed in the current and planned years,a twolayer model is constructed with the outer layer being the joint operation of reservoir groups and the inner layer being the spatial equilibrium allocation of water resources.Among them,the construction of the outer model includes determining the decision variables for joint operation of reservoir groups,setting appropriate objective functions,and clarifying constraint conditions;The construction of the inner model includes determining water supply failure rules,calculating river channel losses,setting objective functions,and developing a reasonable set of water supply plans.(3)The results of the joint operation of three source water reservoirs and the spatial balanced allocation of water resources in the current year show that the duration assurance rate of water supply in the irrigation area of the Yarkand River basin is 83.7%,and the other two source streams are below 50%;The assurance rate of ecological water supply duration in Hotan River and Aksu River basins is lower than that in irrigation areas;The plain reservoirs in the Yarkand River basin participate in the allocation of water resources most frequently,with more than 50%on both tributaries,and less than 20%in the Hotan River basin;The proportion of water resources in Yarkand River,Hotan River and Aksu River basins entering the mainstream of Tahe River is 100%,68%and 93%respectively.(4)Compared with the results of the current year,the joint operation of three source water reservoirs in the planning year increases the water supply and duration assurance rate of the irrigation area in the Yarkand River basin;The water supply of irrigation area and ecology in Hotan River basin decreased,but the duration assurance rate increased by 9%;The water supply in the Aksu River Basin irrigation area has increased,while the ecological water supply has decreased,but the duration guarantee rate has increased by about 20%;The average annual abandoned water volume of the three source streams decreased,and the flow rate of water resources at the most nodes in the Hotan River basin increased by 20%;The frequency of participating in water resource allocation in the three source streams of the Upper Plain Reservoir has increased,with the Aksu River Basin increasing by 22%.(5)In the planning year,there will be more reservoirs in the mountainous area of the three source streams.Under the effective storage capacity of three different plain reservoirs,the average annual dry inflow and duration assurance rate of the Yarkand River basin meet the discharge requirements,and the irrigation area will have the smallest water shortage when the plain reservoir is abolished;The average annual dry inflow of Hotan River basin also meets the requirement of 900 million m~3,but the duration assurance rate is less than 50%.After the effective storage capacity of plain reservoir is halved or abolished,the water supply and duration assurance rate of irrigation area and ecology are reduced;The guarantee rate for the duration of discharge from the Aksu River Basin to the Tahe River is greater than 50%,but only after the abolition of the plain reservoir can the average annual discharge volume meet the requirement of 3.42 billion m~3.When the effective storage capacity is reduced by half,the guarantee rate for the duration of each water department in the basin is the highest.(6)Construct a joint scheduling model for three source streams,and analyze the discharge of the three source streams into the Tahe River during separate and joint scheduling at different levels of year.The average annual inflow and duration guarantee rate during the current and planned years of joint scheduling are higher than those under the scenario of individual scheduling.The inflow and duration guarantee rate of the Alar section calculated by the two scheduling modes are higher than the measured values.In the planning year,after the effective storage capacity of the plain reservoir is reduced by half or abolished under both scheduling modes,the guarantee rate for the discharge of the Tahe River can meet the requirement of 50%,and the average annual inflow of water also exceeds 4.65 billion m~3.