Based On The Carrying Capacity Of Water Resources Optimal Allocation Of Agricultural Water And Land Resources In Aksu River Basin

Aksu River Basin is located in the arid area of northwest China,the contradiction between agricultural water use and ecological water use is prominent.As the largest source of Tarim River,its water resources change affects the steady development of the whole Tarim River basin.It is an important direction to optimize the allocation of agricultural water and soil resources in Aksu River Basin,so as to alleviate the contradiction between water resources and cultivated land resources and strengthen the ecological construction in response to China’s water-saving agriculture strategy.This paper comprehensively analyzes the current situation of the utilization of soil and water resources in Aksu River Basin,and on the basis of the research on the carrying capacity of water resources,establishes the optimal allocation model of agricultural soil and water resources,and uses NSGA-Ⅱ genetic algorithm to solve the problem and obtain the optimal scheme.The main research results are as follows:(1)The mean value of spatial equilibrium coefficient of water resources in Aksu River Basin from 2015 to 2019 is 0.65,which belongs to moderate imbalance(level 4).Under the condition that the distribution of natural water resources in Aksu River Basin is unbalanced and the agricultural water consumption accounts for more than 95% of the total water consumption,the annual increase of water use efficiency has been difficult to meet the increasing demand for water resources.The main reason for the moderate imbalance is the uncoordinated planting proportion of grain,feed and feed crops.(2)The total water consumption/index value of Aksu River Basin was 1.03,indicating that the carrying capacity of water resources in the basin was overloaded.Wushi County and Keping County are seriously overloaded,Wenshu County,Awati County,Aksu City are overloaded,Nongyi Division is the only area in the whole basin is not overloaded;The carrying population of Aksu River basin is 1,415,100 people,and the actual population is1,788,800 people,which is 26.4% overloaded.Population overload ranking: Aksu City >Wensu County > Agricultural Division > Awati County > Wushi County > Keping County.High salinity and unreasonable agricultural planting structure are the main reasons for water resources overload in the basin.(3)The total value of various types of crops in Aksu River Basin is ranked from large to small as follows: cash crop > food crop > forage crop.The indexes of farmland ecosystem service value in the watershed were as follows: carbon fixation and oxygen release >,soil conservation>biodiversity>waste consumption>air purification;The order of ecosystem service value of different crop types was: alfalfa > potato > corn > beet > cotton > wheat >oil > beans > vegetable > melon fruit > rice.The total value of farmland ecosystem services in the basin was 7.961 billion yuan.Primary productivity,straw/grain ratio and cover index were the main factors affecting the farmland ecosystem service value in Aksu River Basin.(4)Based on the optimal allocation of agricultural soil and water resources in Aksu River Basin,the objective of water resource carrying capacity and ecological benefit are not in conflict.The optimal results of the water resource carrying capacity dominant scheme and the ecological benefit dominant scheme are almost identical.At the same time,compared with the current water resource carrying capacity,the water resource carrying capacity dominant scheme and the ecological benefit dominant scheme have the largest improvement effect,increasing by 10.30%.The economic benefit dominant scheme increased by 8.98%;The unpreferred scheme increased by 9.69%.The decision maker should choose the corresponding optimization scheme according to different preferences.