基于RS和GIS的郑州市城市扩展研究

Dynamic monitoring of urban expansion based on RS and GIS technology-a case study of Zhengzhou city

以1988年和2001年的TM/ETM+遥感影像作为主要数据源,将RS与GIS技术相结合,对郑州市城市扩展进行动态监测.首先利用ENVI软件构造三指数波段,即归一化建筑指数(NDBI)、归一化水体指数(NDWI)和土壤调节植被指数(SAVI),用来代表郑州市最主要的土地覆盖类型:城镇用地、水体和植被.然后对3个指数波段进行假彩色合成,采用最大似然监督分类法对假彩色合成影像进行分类,利用ENVI的掩膜技术从分类结果图中提取出城镇用地信息,再利用GIS的空间叠加分析功能提取出城市用地扩展信息,包括城市扩展的面积、方向及速率等,最后对城市扩展模式进行分析.研究结果表明,郑州市1988—2001年间城市建成区面积共扩展61.33 km2,平均每年扩展4.7 km2,城市扩展模式可近似看作是以二七广场为中心向四周呈同心圆式蔓延扩展.

TM/ETM ＋ RS images of May 14, 1988 and May 10, 2001 are adopted as main data sources, and three indexes which are normalized difference builtup index （NDBI）, normalized difference water in- dex （NDWI） and soil adjusted vegetation inde （SAVI） to represent three main land cover types （i. e. building, water body and vegetation） are constructed based on data - dimension compression technique. The pseudo - color composite image of the three index - bands is made, and the maximum likelihood supervised classification for the pseudo - color composite image is carried out. Then extract out urban land information from the classification result maps of the pseudo - color composite image by using masking technology of ENVI software. The spatial overlay analysis technique of GIS is used to extract out urban expansion information of Zhengzhou city from 1988 to 2001, which includes urban expansion area, rate and direction, etc. Finally, the urban expansion pattern of Zhengzhou city is analyzed. The results indicate that： the urban expansion area of Zhengzhou city is 109.80 km2 from 1988 to 2001, the average annual urban growth rate is 8.98% , the main urban expansion directions are Northeast, West, North, South and Southeast. It is approximately con- sidered that the urban expansion pattern of Zhengzhou city is the concentric circle pattern taking Two - seven Square as its city center.