苏南沿江城镇扩展的空间模式及其测度

定义了城镇边界的划分规则, 通过卫星遥感影像获取了苏南沿江地区1984 年、1991 年、2000 年和2005 年的城镇边界, 利用分形维数(半径维数、网格维数、相关维数、边界维数)、紧凑度指数以及空间自相关指数(Global Moran I、Local Moran I), 定量揭示了区域城镇扩展的空间模式。结果表明: 分形度量可以定量揭示区域城镇的空间分布特征以及空间组织 结构, 空间自相关可以定量揭示城镇的空间扩展过程、聚簇模式, 二者相互结合, 可以测度区域内城镇扩展的空间模式, 揭示城市群/ 城市连绵区的形成过程; 苏南沿江地区城镇扩展从改革开放初期自发的以大城市为中心的点状扩展模式, 经历了由政策驱动下以融合填充为主导的点- 轴延伸模式, 发展到以经济辐射联系为策动力基于区域产业空间组织的城镇连绵集聚模式, 一个大的城市群正在形成。特别自2000 年以来, 城市群的空间结构特征日益显现。区域内城市的多中心现象始终存在, 但空间极化作用逐渐削弱。

Urban Spatial Sprawl Pattern and Metr ics in South of Jiangsu Province along the Yangtze River

Satellite images acquired in 1984, 1991, 2000 and 2005, respectively, were used to interpret the boundaries of cities and towns in the south of Jiangsu province along the Yangtze River on the basis of our boundary definition. And then regional urban spatial sprawl pattern was uncovered quantificationally by some indexes, such as fractal dimensions including radius dimension, grid dimension, correlation dimension, boundary dimension, compactness index, and spatial autocorrelation index including global Moran I and local Moran I. The result shows that:(1) fractal dimension metrics and spatial autocorrelation index, respectively, can quantificationally reveal regional urban spatial distribution features and spatial sprawl process and cluster pattern, and their fuse can measure regional urban spatial sprawl pattern and uncover the process of how to form the urban cluster;and (2) at the initial stage of reform and open-up policy, the urban sprawl in the south of Jiangsu province along the Yangtze River was spontaneously point-pattern centered around big cities, and then point-axis-pattern dominated by policy-driven urban spatial fuse and fill, at present cluster-stretched pattern based on regional industry spatial organization driven by economical radiation and contact, and a big urban group is coming into being. Especially since 2000, spatial structure features of an urban group are more and more evident with time elapsing. Additionally, the main feature of urbanization in the study area is that industrialization pushes urbanization based on the background of global economy. In the study area three centric cities have existed since the 1980s, however, their spatial polarizations have a less and less effect on others.