| The problem of water shortage has long been concerned by the world,so the research on the optimal allocation of water resources has been carried out for many years,and the relevant theories have been gradually improved.In recent years,China has vigorously promoted the most stringent water resources management system,namely the“three red lines”requirements.For the study of the optimal distribution of water resources in arid areas,the current theory is not mature,but also lack of corresponding holistic research.Therefore,how to solve the problem of optimal allocation of water resources in arid areas under the"three red lines"is of great significance to its economy,ecology and even sustainable development.In this paper,the main stream region of the Tarim River with typical drought characteristics is selected as the research object.The characteristics of precipitation and drought and flood in the whole region of Xinjiang are analyzed.Based on the artificial decision,the preliminary allocation of water resources is carried out by using the coefficient matrix method.Finally,the optimal allocation model of water resources with the objective function of maximizing agriculture and ecological benefits and the total amount of mainstream water resources,the highest agricultural irrigation water consumption,the lowest ecological water demand and the highest pollutant concentration are established.The non-dominated sorting NSGA-II genetic algorithm is used to solve the problem;the relevant conclusions are as follows:(1)The rainfall in Xinjiang is unevenly distributed,and precipitation is concentrated in summer and winter,and precipitation decreases from north to south.In the 1970s,the PCD in Xinjiang was relatively small,that is,the precipitation was relatively dispersed and prone to drought.The PCP occurred earlier in the 1970s,that is,the rainy season occurred earlier,and then occurred later.The PCI shows two stages of change over the years.The PCI value before the 1980s was 12.08 higher than that after the 1980s.In recent years,precipitation has been low,but rainfall intensity has increased.The RAI rose overall after the 1980s,indicating that the intensity of drought and flood will increase.(2)The Xinjiang SPI was negative before the 1980s and showed a pattern of drought.After that,the overall value was positive and showed flood’s characteristics.In the 1960s and1990s,drought disasters were prone to occur,and the frequency of flood disasters occurred later,and its frequency increased year by year.The LDFAI shows the drought and flood abruption events in the 1980s,and it is more able to express the characteristics of droughts and floods.Pearson correlation coefficient was made between LDFAI and SOI and Nino3,the results show that the LDFAI and SOI are delayed by 1~4 months;In March,Nino3 is larger and LDFAI is smaller,which is prone to drought and flood abruption.(3)Based on the preliminary allocation of water resources under artificial decision-making,assuming that the runoff amount of upstream,middle and downstream are 1.1×109m~3,8×108 m~3 and 5×108 m~3 respectively,the upstream agricultural water allocation and benefits are 4.98×108m~3 and 1.035×109 yuan respectively on an annual scale;the ecological water distribution and benefits were 5.31×108m~3 and 2.83×108 yuan respectively.Similarly,the middle stream agricultural water allocation and benefits are 4.46×108m~3 and 8.74×108yuan respectively;the ecological water distribution and benefits were 3.61×108m~3 and 1.88×108 yuan respectively.the downstream agricultural water allocation and benefits are 4.53×108m~3 and 9.89×108 yuan respectively;the ecological water distribution and benefits were0.76×108m~3 and 0.31×108 yuan respectively.(4)Based on the optimal allocation of water resources in the Tarim River mainstream under the“three red lines”,the design frequency is 25%,50%,75%,90%,and the water distribution result of the NSGA-II solution in the 25%water situation:The agricultural and ecological water distribution and benefits are the largest.The water allocation of the agricultural and ecological computing units is the largest in spring and July and August in summer,and reaches 100%water supply,with the lowest water distribution in winter,especially for agriculture.At the same time,the agricultural water distribution in the Tarim irrigation area of Shaya County,Yuli County and Agricultural Second Division is larger than that of other areas,and the ecological water allocation of the ecological computing unit in the North Shore is higher than that of the South Bank.In addition,the peak annual profit of each agricultural and ecological computing unit is consistent with the peak month of water distribution,both in spring and summer.It can be seen from the proportion of annual profit of agriculture that Kuche County and Kuche farm sheep farm irrigation area can achieve annual benefits.The annual benefit ratio shows that the South Bank is more likely to achieve annual benefits than the North Shore. |
