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Monitoring the seasonal bare soil areas in Beijing using multitemporal TM images

Recently, there were many strong sandstorms occurred in North China, which became a severely economical, social and environmental problem, especially for Beijing City. The bare soil is an important source of sandstorm, and the croplands naked in winter in 55 counties around Beijing City became the main source of the sandstorm. It is very important to monitor the seasonal bare soil areas using remote sensing data. The multitemporal TM images of Beijing area in May 16, 1997, April 7, 2003, May 25, 2003, October 24, 2003 and January 28, 2004 were selected. Firstly, the smoothing filter-based intensity modulation (SFIM) completed the image fusion. Secondly, the multistage classification approach was adopted. The multisource data, such as DEM, NDVI, bare soil index (BI), shadow index (SI), were integrated and applied in classification, and the seasonal bare soil areas, such as wasteland, cropland, were successfully extracted. Thirdly, the seasonal and inter-annual dynamic changes of the bare soil areas were also analyzed.