| Xinjiang is located in inland arid zone,and the problem of water shortages is serious.In recent years,the water resource of the Kaidu-kongqi River Basin has become a highlight issue.The traditional utilization of water research which is based on humanity's need has been strengthened.The proportion of agricultural water is too large,resulting in the sharp decrease of ecological water.This has led to the weakened stability of oasis system,its abnormal development and the contribution to numerous ecological and environmental issues.This paper takes the Kaidu-kongqi River Basin as the research area,and uses the MODIS EVI data in 2000,2005,2010 and 2017 combined with the decision tree classification algorithm to extract the main crop planting structure.On the basis of it,using the daily meteorological data of 2000,2005,2010 and 2017,the crop coefficient method was used to obtain the water requirement of crops and the changes have been analyzed.Finally,based on the thirteenth FiveYear Plan,the research on the optimization of crop planting structure is carried out.The preliminary results are as follows:(1)The crop planting structure in the alluvial plain of the Kongqi River is relatively simple,mainly consisting of pear and cotton.The crop planting structure in the Yanqi Basin is relatively complicated.Before 2005,there are mainly wheat and corn;but after 2010,the planting area of industrial pepper and tomato is the largest and the phenomenon at Bohu and Yanqi county is remarkable.Sugar beets are mainly grown in Hejing County.Wheat acreage has a steady decline between 2000 and 2017,while the planting area of cotton,pepper,tomato and sugar beet has an increase.(2)In the initial growth period,the crop water requirement is less than 80 mm.During the period of rapid development,pear > cotton > tomato > corn > beet > pepper > wheat.In the mid-fertility stage,the crop water requirement is higher than 300mm;the water demand of pear and beet is basically the same,which is higher than the other five crops,and followed by wheat.Among the remaining crops,cotton and corn require more water than peppers and tomatoes.At the maturity stage,the water requirement of pears is much lower than that of other crops,and the water demand of other crops is higher than 100 mm.(3)Average annual water requirement of different crops: The average annual water requirement of 7 crops is higher than 600 mm.Among them,sugar beet has the highest water demand,followed by pear,cotton,pepper,tomato,corn and wheat.In general,the average annual water demand for cash crops is higher than that of food crops.(4)Inter-annual variation of water demand for different crops: The annual variation trend of water demand per unit area for seven crops is basically the same,showing a rising-decreasing-increasing fluctuation trend.In addition to wheat,the total water demand for crops from 2000 to 2017 was affected by the expansion of crop planting area,and the overall trend was on the rise.Inter-annual variation of total water demand for crops: From 2000 to 2017,the total amount of crop water demand has been increasing,and the rate of increase has decreased step by step.(5)Spatial distribution of total water demand for crops: On the whole,the spatial variation of crop water demand in the Kongqi River Basin is smal,and the regional water demand of crops in the Kaidu River Basin is quite different.In 2005,the water demand of crops in the northwest of HeJing County,the eastern of Heshuo County and the southeast of Bohu County was higher,and the water demand of crops in Yanqi County was lower.In 2010,except the eastern of Heshuo County,the water demand of crops in the Kaidu River Basin was lower than that in 2005.The crop water demand in 2017 has picked up again.(6)From the results of crop planting structure adjustment: in addition to the increase in the total area of corn,pear and pepper crops,the remaining crop area has decreased.From the perspective of optimization results: Results 2 has a better watersaving benefits,with a rate of 30.39%.Results 1 has the highest net income which is 113.23%.The water use income of crops has increased significantly. |
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