Study on the Spatial-expanding Characteristics of Urban Construction Land-use in Karst Mountain Area Based on GIS——A Case of Dahua Yao Autonomous County of Guangxi
利用1988、1999年Landsat影像和1996年土地利用图，分析广西大化县城市建设用地的空间扩展特征，发现81%的增长来自耕地、林地和草地，主要沿交通线扩展，驱动因素包括经济发展、交通改善和人口增长。
Three different temporal spatial information of urban construction land_use in Dahua county of Guangxi was extracted respectively from two Landsat TM/ETM~+ images of 1988 and 1999 and from map of Land Use Actuality about Dahua county of Guangxi in 1996 respectively. Then the spatial_expanding Characteristics of urban construction Land use in Dahua county of Guangxi from 1988 to 1999 were analyzed by geography information system. The result showed that the spatial_expanding Characteristics of urban construction Land use in Dahua was distinct since 1988 to 1999. 81% of urban land_use growth was from farmland, woodland and lawn, which increased the environmental pressure in ecosystem. The spatial characteristic of urban land_use in Dahua is main transportation routes line_expending model. The main driving forces of urban land-use growth in Dahua included the development of national economy, administration factor ,the improvement of transportation, the population increasing and the exploitation of natural resources etc. hydropower, mineral.