不同规模城镇的扩展过程分析——以北京为例

Expanding process of urban areas at different scales:a case study in Beijing region

基于遥感和地理信息系统技术,利用Landsat系列遥感图像的解译成果,分析了北京地区1984～2002年不同规模城镇的扩展过程。研究表明,(1)北京近18a来,各区县城镇规模对其扩展度具有较大的正面影响,且随着城市化的进程其影响程度日益增长。(2)北京近18a来,各区县的城镇用地的扩展强度是以城区为中心,四周辐射逐渐变慢,且对扩展度起到重要作用的是空间位置和地形条件,也就是说地形条件越趋向于平原,空间位置越接近于市中心,城镇用地扩展机会将越大。(3)北京近18a来,大部分区(县)城镇用地不断向外扩张,迅速侵占、同化周边其他土地利用类型(以农业用地、草地、其他用地为主),原有城镇扩展迅速,城镇分布局部集中,范围也不断扩大。

Urbanization is an important topic in modem ecology, there are abundant studies conducted on many aspects of it in the past. However, the effect of city scale on urbanization process and the spatial relationships of urban areas in region received little attention. Based on Landsat TM data, the expanding process of urban areas at different scales in Beijing region was described during 1984 -2002. The calculation of the expansion degree of built-up lands in the periods of 1984 - 1991, 1991 -1997, and 1997- 2001 respectively, and the contribution ratios and annual contribution ratios of the other six land use types to built-up lands showed that, （ 1 ） city scale positively affected on the expansion degree of built-up lands in Beijing region in the past 18 years, and the effect was progressively increasing with the process of urbanization. （2） the spatial position and topographical condition also greatly impacted on the expansion degree of urban areas, the nearer the place to Beijing city （the urban center） , and the smoother the urban topography, the more expanding opportunity the urban area. （3） The built-up lands mainly assimilated the surrounding farmlands, grasslands and unused lands, which process had resulted in the rapid concentration and sustaining expansion of urban areas at different scales and in different parts of Beijing region.