Research On Optimal Allocation Of Ecological Water In The Main Stream Of Tarim

Since ancient times,the Tarim River has been hailed as the mother river of the people of all ethnic groups in Xinjiang.There are many water diversion gates along the main stream with agricultural irrigation and ecological water replenishment functions.So how to distribute ecological make-up water flow among the gates and obtain the maximum water supply benefit is an important issue facing the ecology and water resources management of the Tarim main stream.Then,due to the lack of systematic planning and scientific water resources allocation,the water intake of each gate cannot be controlled by specific policies,and there is no clear difference between agricultural and ecological water use;in addition,due to the inefficient use of water intake,water resources in some regions have been caused.Redundancy,severe water shortage in some areas.All these have further hindered the process of efficient utilization of water resources in the main stream of the Tarim River,and further deepened the degree of deterioration of the ecological environment.In this paper,the 87 diversion flows along the main river of the Tarim River are used as decision variables,and the goal is to maximize the benefits of agriculture and ecological water supply.The water distribution rules that take into account the ecological characteristics of the water supply areas of each diversion are used to establish the optimal allocation model of ecological compensation for the main stream;The ecological characteristics of each ecological gate control area are set up with three schemes for grading the control area,and then set up water distribution rules in combination with the different inflow conditions of the main stream of the Tarim River at ten-day scale.The calculation results of the ecological replenishment of various gates under various incoming water scenarios show that,on the premise of ensuring the agricultural water use along the coast and the ecological water use in the river,the configuration model established in this paper takes into account the ecological replenishment flow distribution between the various gates,taking into account the upstream and downstream banks The demand for ecological water use has improved the level of ecological water security in important areas,and the comparison of annual optimization results at different levels shows that the model optimization scheme is better than the previous water distribution scheme,which provides a useful decisionmaking reference for the management practice of ecological water replenishment in the main stream of the Tarim River.The main research contents and results of this article are as follows:(1)Starting from ecological sensitivity,establish a gate priority evaluation system based on ecological characteristics.In this paper,56 ecological gates along the Tarim River are used as the main basis for prioritizing ecological gates according to the multiyear vegetation coverage(NDVI),ecological sensitivity(|α|)and water demand satisfaction(WSDA)of the gate control area.Then,set three schemes for NDVI single index,single ecological sensitivity single index and comprehensive three major indexes respectively,and divide the water distribution priority levels of 56 ecological gates.(2)Aiming at maximizing the benefits of agricultural water distribution and maximizing the benefits of ecological water use,the optimal allocation model for ecological water use in the main stream of the Tarim River was constructed.The model constraint conditions are mainly agricultural and ecological water distribution index constraints,water supply constraints,water balance constraints,and sluice gate capacity constraints.Among them,the upper and lower parameters a and b in the water gate capacity constraint of the ecological gate set three schemes according to the gate priority,model the simulation of the Aral water flow process from 2009 to 2018,and aim at the flow process of each control section and the actual comparison results of the flow process verify the feasibility of the parameters.(3)A targeted scenario analysis was carried out,and the ecological water dispatching rules for the main stream of Tarim River were extracted from this.In this paper,the comparative analysis of the model optimization schemes for the four scenarios of extremely dry,partial dry,partial rich and extremely abundant water years is carried out.It is obtained that the ecological water allocation plan for the main stream of the Tarim River has the best performance in dry year plan 1(based on NDVI single index gate priority classification).Excellent,and the rest of the year is the best performance of scheme three(combination of three major indicators gate priority).Finally,the analysis summarizes the gate opening rules for the optimal allocation of ecological water in the main stream of the Tarim River under different design frequencies.When the inflow of the main stream of the Tarim River is WAlaer≥ΣWagr,i/1-βi+ΣWeco,j/1-βj,all ecological gates are opened 100%,and the water distribution of the ecological gates is greater than or equal to the ecological water demand;when the inflow of water is ΣWagr,i/1-βi≤WAlaer<ΣWagr,i/1-βi+ΣWeco,j/1-βj,the ecological gates of type Ⅰ are opened 80%,and the q≥0.4qd is guaranteed;Open 60%of the ecological gate,and ensure its q≥0.2qd;open 40%of the type Ⅲ ecological gate;open 20%of the type Ⅳ ecological gate;when the water flow is C,open the type Ⅰ ecological gate 40%;open the type Ⅱ ecological gate 20%;the rest The gate is closed.