Coupling Analysis Between Urban Expansion And Cultivated Land Use Change In AKesu City

Urbanization is the symbol to measure the degree of regional development and the only way in the process of human development.The development of the city has brought comfortable living conditions to the people,at the same time has changed the land use structure,people's biochemical way,the construction land expansion has occupied the surrounding cultivated land unceasingly,the cultivated land is the human survival guarantee.How to rationally adjust urbanization and protect cultivated land in the process of urbanization is an important problem to be solved.Akesu is a typical oasis city,located in southern Xinjiang.The characteristics,driving factors and existing problems of construction land expansion in Akesu are discussed in this paper,which provides a basis for the development and construction ofthis Oasis City.This study in 1990,2000,2010 and 2015,using Landsat TM/ETM+satellite remote sensing image as the data source and using ENVI supervised classification,concluded four periods of Akesu City construction land,cultivated land,forest land,water,unused land and other information.The change rule of construction land in Akesu is studied by using the index of expansion strength,velocity,center of gravity coordinate transfer,compact degree and elastic coefficient.Analysis through field observations and relevant socio-economic data,drivers of expansion of construction land and change of cultivated land area;Calculation of urbanization level and cultivated Land use level in Aksu City by Multi-objective Linear weighted function method;The coordination degree function is introduced to evaluate the coupling relationship between urbanization level and cultivated land use level.(1)In 1990,the land area of construction land was 18.34 km~2,and the total area of construction land in 2015 was 91.61 km~2.The total expansion area in the 25 years was 73.24 km~2,and the net increase was four times that of 1990.The land types mainly occupied in the expansion of construction land were unused land and arable land,with an area of 43.84 km~2 and 28.04 km~2 respectively;with construction land barycentric coordinates in the NE and SW,there was SW direction migration,similar to traffic routes.From 1990—2000 the barycentric coordinates distance moved little,with amobile distance of 243.7 m.There was a moving distance of 832.2 m in2000—2010,and 2010—2015 had the largest mobile distance of 1568.2 m.There was an extension then for the planar shape and ribbon;the density of the perimeter of the construction site has been declining,from 0.201 in 1990 to 0.066 in 2015,and the urban space is increasingly complex.[Conclusion]The construction land of Akesu City expanded continuously and rapidly from 1990 to 2015.The Akesu City construction land expansion speed during the study period was higher than the rate of population growth,with an expanding gap between the two.The elastic coefficient was 2.3 in 1990—2000 and 10.13 in 2010—2015,so the urban expansion and population growth were not reasonable.Through the expansion of the urban construction land influence factors analysis,non-agricultural population factor,economic factors,policy factors,and traffic factorsin Akesu City are the main driving factors of land use change.(2)The acreage of cultivated land in Aksu City has been increasing by and large from 1990 to 2015.While the cultivated land is occupied by various non-agricultural land,the newly reclaimed cultivated land has exceeded the occupied cultivated land area.The area of cultivated land in the later stage of the study was more than twice that in the early stage of the study.During the research period,the newly reclaimed cultivated land was distributed in the southwest and southeast,and the total cultivated land in the upper part of the study was the most.The driving factors of cultivated land area change are social and economic development factors,agricultural production level factors,political factors and so on.(3)The level of urbanization and utilization of cultivated land in Aksu City shows an increasing trend,but because of the development stage,the level of urbanization and the level of cultivated land use are not high,the fluctuation is relatively large,and the area of cultivated land is growing rapidly.Therefore,the level of cultivated land use is in a lower state.(4)According to the calculation results of coordination degree of urbanization level and cultivated land utilization level in Aksu City,the degree of coordination showed a steady upward trend,but the degree of coordinated development advanced first to good coordination development,then to uncoordinated direction.