Quantitative Analysis of Urban Expansion Using RS and GIS, A Case Study in Lanzhou

Abstract

Urbanization has changed the pattern of urban landscapes and the natural landscape. Evaluations of the spatial and temporal changes of the urban landscape pattern could support the urban expansion analysis commendably. This study has two objectives: (1) to present methods to characterize the spatial behavioral features and the corridor effect of urban expansion by using geographical information system (GIS) and remote sensing (RS) images and (2) to apply the methods to Lanzhou as an example. In this study, ERDAS IMAGINE was used to process and prepare RS images and digital land-use maps. In addition, information on urban expansion was extracted by using the man-machine interactive interpretation method under the ArcTools model of ArcInfo. The landscape indexes were calculated by FRAGSTATS, which is a spatial pattern analysis program utilized to evaluate categorical maps. All other indexes were calculated and displayed by using the grid model, spatial analysis model, and network analysis module of ArcInfo. The landscape transition matrix, landscape index of the urban construction area, urbanization gradient, and corridor effect of urban expansion in Lanzhou were then studied. Landscape transition matrix analysis revealed that the urban construction area in Lanzhou expanded rapidly and considerably between 1986 and 2006. Analysis of the urbanization gradient revealed that there was isolated urbanization in the suburban area, amalgamated urbanization in the rural urban fringe area, and peripheral urbanization in the main built area. On the basis of the module that provides a comprehensive effect between the artificial corridors and natural corridors during the urban expansion process, Lanzhou will develop into a network city with a multicore structure, network shape, and compounded function. Overall, the results of this study demonstrated that RS integrated with GIS technique is an effective approach to the analysis of urban expansion.