| The Manas River Basin is located in the northern part of Xinjiang,my country.It is located in an inland arid and semi-arid area,far away from the ocean.The climate is dry throughout the year,with little precipitation and a large amount of evaporation.Agricultural irrigation has long been the main source of water in the basin,and the proportion of agricultural water consumption is as high as 88%.The unreasonable water use structure leads to a prominent contradiction between water supply and demand during the peak period of agricultural irrigation,which affects the further sustainable utilization of water resources in irrigation areas.This study takes Manas River Irrigation Area as the research area,takes 2020 as the status quo year,and takes 2025 and 2030 as the planned level years.Set up a comprehensive benefit model including economic value,social attributes and ecological contribution.The optimal planting structure and water distribution scheme of Shihezi,Xiayedi and Mosuowan irrigation area under Manas River irrigation area are obtained by solving the linear comprehensive benefit planning model with "three red lines" as the constraint of water consumption by lingo.The research results can effectively improve the comprehensive benefit and water resource utilization rate of the Manas River irrigation area,and provide a theoretical basis for the efficient and rational allocation of water resources in the irrigation area.The main results of the thesis are as follows:(1)Prediction and analysis of the balance of water supply and demand in Manas River Irrigation District.The total amount of water available in Manas River Irrigation Area in 2025 is 1.055 billion m~3,of which surface water can supply 831 million m~3,groundwater can supply 195 million m~3,and other water sources can supply 29 million m~3.The total water demand in Manas River Irrigation District is 1.155 billion m~3,of which Shihezi Irrigation District requires 406 million m~3,Mosuowan Irrigation District requires 284 million m~3,and Xiayedi Irrigation District requires 465 million m~3.The water shortage in the Manas River Irrigation District is 101 million m~3,of which the Shihezi Irrigation District has a water shortage of 28.17 million m~3,with a water shortage ratio of 7.46%,and the Mosuowan Irrigation District has a water shortage of 29.57 million m~3,with a water shortage ratio of 11.6%.The water shortage is 43.13 million m~3,and the water shortage ratio is 10.2%.(2)Based on fuzzy set theory,this thesis constructs an optimization model of crop planting structure in Manas River irrigation area including crop economic,social and ecological benefits,and proposes the optimal planting structure plan for the irrigation area in 2025 and 2030.In 2025,the planting area of the Manas River Irrigation Area will be reduced by 309,500 mu.Among them,the area of wheat decreased from 58,600 mu to 56,500 mu,a decrease of 3.6%.The cotton planting area was reduced from 3.105 million mu to 2.8319 million mu,a decrease of 8.8%.The corn area decreased from 58,500 mu to 51,300 mu,a decrease of 12.3%.Grape planting area decreased from 119,500 mu to 92,300 mu,a decrease of 22.8%.In 2025,the economic benefit of unilateral water in Mahe Irrigation Area will decrease by 0.072 yuan,the social benefit will increase by 0.41%,the ecological benefit will increase by 0.28%,and the comprehensive benefit will increase by0.18%.In 2030,the planting area of the Manas River Irrigation Area will decrease by 599,000 mu.Among them,the area of wheat has increased to 61,700 mu,the area of cotton planting has been reduced to 2.568 million mu,the area of corn has been reduced to 43,800 mu,and the area of grape cultivation has been reduced to 69,200 mu.In 2030,the economic benefit of agricultural unilateral water in the irrigation area will increase by 0.853 yuan,the social benefit will increase by 0.94%,the ecological benefit will increase by1.13%,and the comprehensive benefit will increase by 9.84%.The optimization effect of planting structure is obvious.(3)After analyzing the improvement of the water use coefficient of the canal system and the optimization of the planting structure in the Manas River Irrigation District,the water-saving potential of the irrigation area was analyzed and calculated according to the calculation formula of the agricultural watersaving potential.In 2025,the water-saving potential of agricultural irrigation water in the Manas River Irrigation Area is 128.6 million m~3,of which the water-saving potential of Shihezi Irrigation Area is 37.2million m~3,the water-saving potential of Xiayedi Irrigation Area is 32.6 million m~3,and the water-saving potential of Mosuowan Irrigation Area is 58.8 million m~3.In 2030,the irrigation water saving potential of Manas River Irrigation Area is 223.6 million m3,of which Shihezi Irrigation Area has a water saving potential of 59.2 million m3,Xiayedi Irrigation Area has a water saving potential of 63.4 million m3,and Mosuowan Irrigation Area has a water saving potential of 101 million m3.The calculation of agricultural water-saving potential is of great significance to the allocation and management of water resources in irrigation areas. |
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