无锡市城市扩张的空间特征及驱动力分析

以无锡市1991、1996、2001和2005年的Landsat TM/ETM+影像为数据源，采用改进后的波段组合阈值提取法对无锡市城市建成区空间信息进行提取，并参照太湖流域土地利用分类图对提取的信息进行修正；通过影像叠加分析，研究 1991~2005年无锡市城市扩张的空间分布规律，认为无锡市城市总体扩张呈现出不断增加的态势，尤其是2000年以后，城市扩展出现快速发展。同时无锡市城市空间扩张呈现出不均匀性，主要包括集中连片发展和轴向扩展两种典型的扩展模式，而城市扩展方向主要集中在常州 无锡 苏州城市中心线沿线和环太湖方向，其中以东南部和东部扩展最为迅速；结合无锡市 1991~2005年社会经济以及人文数据，分析了人口及经济发展对城市扩张的影响，结果表明：人口的增加和城市的经济发展是影响无锡市城市扩展的两个重要因素。

SPATIAL FEATURE OF URBAN EXPANSION IN WUXI CITY AND ITS DRIVING FORCES

Taking the Landsat TM/ETM+images of Wuxi City in 1991,1996,2001 and 2005 as the data source,this paper used the improved band combination threshold extraction to extract the spatial information of urban built-up in Wuxi City.Then the result was corrected referring to the land use classification map in drainage area of Lake Taihu.By overlaying of four classified images,the law of spatial distribution of urban expansion in Wuxi City from 1991 to 2005 were researched.Result indicates that the overall expansion of Wuxi has increased continually since 1991.In particularly,after 2000,urban expansion had a rapid development.At the same time,Wuxi showed an uneven development of spatial expansion.The spatial expansion mainly included two typical expansion modes which were centralized flaky development and axial expansion.The mostly direction of urban expansion in Wuxi was along the centerline of Changzhou-Wuxi-Suzhou and encircle the Lake Taihu.Meanwhile,the speed of expansion in south-east and east was the fastest.Combining with the data of socio-economic and humanities,the impact of urban expansion by population and economic development was analyzed too.The results show that population growth and economic developments are two important factors which impact on the urban expansion of Wuxi City.