Urban expansion analysis based on multi-temporal remote sensing and GIS in Wujiang, a typical desakota in Sunan, China (1978-2004)

Abstract

Rapid economic development during the last three decades has caused a large urban expansion in China, especially in the eastern and coastal areas of China. In these areas, a special urban expansion mode, Desakota (Semi-urbanization), is very popular. Wujiang, a typical Desakota are in Sunan, is chose as the research area to study the special urban expansion based on multi-temporal Remote Sensing and GIS. In this study, maximum likelihood supervised classification and post-classification change detection techniques were applied to Landsat MSS/TM images acquired in 1978, 1986, 1993, 2000, and 2004, respectively, to map land cover changes in the Wujiang, China. A supervised classification was carried out on the five images individually with the aid of ground truth data. Ground truth information collected during two field trips conducted between 2005, 2007 and land use map of 1997, 2004 were used to assess the accuracy of the classification results. Using ancillary data, visual interpretation and expert knowledge of the area through GIS further refined the classification results. Post-classification change detection technique was used to produce change image through cross-tabulation calculation. Changes among different land cover classes were assessed. During the study period, a very severe land cover change has taken place as a result of industrial and urban development projects. These changes in land cover led to cropland degradation in the study area. Result indicates the environmental impacts of urban sprawl of Wujiang. The research suggests that human activities, such as urbanization and industrialization, were playing a much more significant role in the change of land cover and landscape pattern during the last 30 years from 1978.