Extraction and Spatial-Temporal Analysis of Impervious Surfaces Expansion in Dianchi Lake Basin

With the development of economy, growth of population and urbanization, urban land is increasing and the speed of urban expansion is speeding up. Mastering the spatial-temporal process of urban expansion is of great significance for natural environment and human development. In this paper, taking the Dianchi Lake Basin as an example, based on the TM and OLI image data from 1990 to 2015, every five years as a time node, the decision tree classification method is used to extract and analyze the urban land for each period of image data. The results showed that the area of urban land in Dianchi Lake Basin increased from 1990 to 2015 with 462km², with an average annual growth rate of 5.9%, of which the fastest expansion rate has occurred from 2010 to 2015. The impervious surface expansion is radiation-like growth centered around the urban area of Kunming, mainly in the eastern and northern parts of Dianchi.