Study On Spatio-temporal Characteristics And Driving Forces Of Urban Land Expansion In Kaifeng

China is a country characterized by its scantly land resources per capita and sharp conflicts betweenpopulation and land resources.In recent years,the rapid increased needs of land resources with social andeconomic development,accelerated pace of urbanization and ecological environment improvement,not onlyled to a widespread expansion of urban land,but also invaded the urban fringe of agricultural land,includinghigh quality cultivated land.Therefore,a lot of problems appeared in the aspect of urban land utilization inour country,such as waste,idle and pollution of land resources and many other aspects.Moreover,this issuehas been the core content of their research for the land management,urban planning and citymanagement.So,to study Spatio-temporal Characteristics and Driving Forces of Urban Land Expansion willbe helpful for monitoring dynamic change of urban land utilization in the process of urbanization,in orderto carry out macro-control and management of land resources.In this study,it based on multi-temporal Landsat TM remote sensing data,five administrative districtsof Kaifeng city as the research area,combined with ERDAS9.0and ArcGIS10.0software,using maximumlikelihood and man-computer interactive method to supervised classification of remote sensing images andinterpreted land utilization data of Kaifeng city in four periods,and extract the map of city built-uparea,based on this date to analyze temporal dynamic characteristics of land expansion in Kaifeng city from1989to2010. This paper takes an analysis with the date about population、economics、transportation inKaifeng in order to find the driving forces of urban land expansion.(1) To extract thematic information of urban land expansion. Using the method of maximumlikelihood to supervised classification and interpretation of the four remote sensing images by ERDAS9.0software,and then in the ArcGIS10.0operating environment to spatial statistical analysis the inpterpretedimages.The paper respectively obtained land-use change information of six types in different periods,whichis construction land,cultivated land,forest land,water,Yellow River and other unused land.To draw fourmaps of land-use types in Kaifeng,extract the map of city built-up area through man-computer interactivemethod。(2) To analyze the temporal characteristics of urban expansion. According to the TM remote sensing image to map out the area of city built-up in Kaifeng,in order to calculate its area in the year of1989,1995,2004,2010,the results were38.63km2,43.89km2,62.12km2,121.59km2.According to theappropriate criteria,the study calculates the expansion rate,intensity and dynamic index of city built-uparea,in order to determine the expansion type of Kaiofeng buit-up area changed from low rate to high-speedbased on the previous calculated result.Especially,the change in the third period is significant.(3) To determine the dynamic changes of urban land center.First,calculating by the city center ofgravity transfer model shows that the study area’s city center of gravity has changed little from1989to1995,only moved to northwest53.95meters.But the distance shifted dramatically from1995to2004,whichmoved to the northwest793.3meters.Moreover, the city center of gravity moved to west670.36metersfrom2004to2010,which indicating the city center of gravity in study area sifted from northwest towest.Then, by making the geometric center of Kaifeng built-up area as a dot,to divide the study area intofour quadrants and eight azimuth,each represents a different direction by using the method of quadrantazimuth analysis.After the comparative analysis,we know that the urban land expansion in Kaifeng hasincreased,the expansion intensity mainly concentrated in the third,four or five quadrant,and the directionfocused on the northwest and west.Meanwhile based on the city center of gravity in1989,the study alsocombines with the buffer analysis to divide the study area into10buffer zones which each zone is1km.After calculation shows that the expansion maximum peak of city built-up area in Kaifeng is in therange of4～6km.The radiation area of city center is constantly moving outward.Overall,the main directionof urban land expansion is in the west of Kaifeng,and it along the traffic axle of Zhengzhou-Kaifeng cityexpressway to expand outward,fills the blank area on the axis continuely and forms new industrial groupand transportation network.Surrounding residential,commercial centers and supporting infrastructure is alsobeing improved,all these factors driving the region’s land utilization.(4) To analyze the driving forces by the combination of quantitative and qualitative analysis.The studyselects the socio-economic statistical data,uses SPSS19.0statistical analysis software and combinesquantitative and qualitative analysis,it councludes that the driving forces of urban land expansion inKaifeng is mainly on population growth,economic development and transport infrastructure improvement.