A study on spatial-temporal features of construction land expansion in Changsha urban area
长沙市区建设用地扩张的时空特征

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 decision-making 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.