改革开放30年来中国主要城市扩展时空动态变化研究

改革开放30年来，城市化速度明显加快，城市扩展是城市化空间上表现最明显的特征之一。论文选取我国大陆地区直辖市、省和自治区政府所在地及其他50万人口以上共135个城市作为研究对象，利用2007年北京一号小卫星多光谱数据，结合20世纪70年代、80年代和21世纪初的美国陆地卫星数据，采用面向对象分割和人机交互的信息提取方法对城市的主建成区进行动态监测，采用扩展面积、扩展强度、分维数、聚集度等指标分析城市扩展的规模、程度及形态等空间格局的变化，同时根据我国区域发展特点选取7个典型区进行扩展动态分析比较，并且结合社会经济统计数据等，概括分析了中国城市扩展的主要驱动因子。

The Spatio-temporal Dynamic Characteristics in Expansion of Major Cities in China in 30 Years since the Reform and Opening-up

In 30 years since China's reform and opening-up, the speed of the urbanization increased significantly, the extension of urban construction land is one of the obvious characteristics of urbanization in the space domain and one of the important measurement indexes, has increasingly become main features of land use change.In this paper, a total of 135 cities with a population over 500000 each from provinces and autonomous regions, municipalities and others in Chinese mainland are selected as the research object. By using Beijing-1 microsatellite multispectral images with a spatial resolution of 32 m acquired in 2007 and Landsat MSS data with a spatial resolution of 79 m acquired in the 1970s, Landsat TM data with 28 m in the 1990s and the 2000s, we monitored urban expansion with 135 central built-up areas based on segment of object-oriented method and human-computer interaction method from three aspects. Firstly, by using the index of expanding area, expansion rate, fractal dimension, compactness index and so on, we analyzed the dynamic characteristics of central built-up areas including city size and spatial pattern, quantity and morphology of expansion since the reform and opening-up. Secondly, seven typical areas were selected based on 30 years of reform and opening-up's policies and regional geographic characteristics, and compared with features of urban expansion. Thirdly, we made a generalization analysis of driving force of urban expansion combined with socio-economic statistic data and macro policies. Meanwhile, taking advantage of the Beijing-1 microsatellite panchromatic data with 4 m which covers a scope of 80% of 135 cities and 1: 1000000 topographic map in the 1980s, we undertook the precision control and quality assessment for four-period images and classified results of the central built-up areas.The results showed that the total area of 135 urban built-up areas had 4 folds to expand, the area of most cities in the 1970s from 50 km~2 extended to more than 200 km~2 in 2007. The cities having highly growth rate are concentrated on the Pearl River Delta and Huang-Huai River Basin. On the basis of different directions and morphologies, the 131 cities were classified into four types according to radiation around, obvious direction, span and aggregation, the percentage is 54%, 37%, 7% and 2% respectively. The urban regions in the Pearl River Delta and Yangtze River Delta have expanded significantly, much larger than the northeast, west and central regions. Except for the influence of traffic and macro policies, population increase and economic growth are the chief driving factors of urban expansion and the relativity between the growth rates of urban expansion is good.