长沙市区建设用地扩张的时空特征

A study on spatial-temporal features of construction land expansion in Changsha urban area

以不同时段的遥感影像资料为数据源，借助GIS技术对空间数据的统计及分析功能，提取出6个时期长沙市建成区变化的相关数据信息。在此基础上，利用扩张速度、扩张弹性、分维数、玫瑰图等方法分析长沙市区1986-2004年建设用地扩张的时空特征。结果表明，近20年来，长沙城市建设用地扩张了将近1倍，尤其是2002-2004年，建设用地扩张趋势最为明显。现阶段城市的扩张主要表现为低密度填充式的蔓延，城区扩张方向的主要方位是NW270°～295°和SE165°～180°。建设用地扩张的驱动因素除经济发展及人口增长因素之外，政策也是重要的影响因素，尤其是近年来政策因素的作用更为突出。未来长沙城市的空间发展将是多中心组团式的扩张，城市扩张方向日趋合理化。

Construction land expansion is one of the notable features of urbanization. Analyzing the spatial-temporal features of construction land expansion can enhance the understanding of the nature of urbanization and provide with the grounds of decisionmaking for urban sustainable development. Based on the review of related research on construction land expansion at home and abroad, this paper takes Changsha urban area as an example, which is one of the most important cities in Central China. First, data on the variation of construction land in Changsha are obtained by employing the statistic and analytic function of GIS on the spatial data from remote sensing image data in different periods. Then the characteristics of construction land expansion are identified by using several methods in analyzing the spatial-temporal features of Changsha urban area from 1986 to 2004, which include expansion speed, expansion elasticity, fractal dimension, and rose map. The results obtained show .that, during the last 20 years, the area of construction land has almost doubled, which is more obvious during the 2002-2004 period. Considering the relationship between the construction land area and population, the expansion speed of the construction land is far beyond that of the population, of which the erosion of arable land is most prominent. At present, the city sprawls by the way of low-density fill and the main direction of city expansion is NW270°-295° and SE165°-280°. Besides economic development and population growth, policy is also one of the important driving forces in construction land expansion. Especially in recent years, policy factor turns out to be the most determinant factor. In the future, the expansion mode of Changsha city will be that of mono-centric groups, and the direction of expansion will be more rational.