Changes of Impervious Surface Area within Fifth Ring Road in Beijing

Based on ETM+in 2000 and TM in 2010 of Beijing,the spatial distribution of urban impervious surface proportion was obtained by using sub-pixel based on linearity spectral mixture analysis model. Combined with the land use map and field investigation,this paper analyzed the dynamic change pattern of impervious surface proportion during the past 10 years in Beijing by using normalized difference building index and spectra mixing model,and the changes of urban impervious surface was studied. The results show that the information extraction method of impervious surface change based on mixed pixel analysis is effective. During the past 10 years,the coverage of impervious surface appeared as radial expansion within the fifth ring road of Beijing with development of urbanization. City construction is one of the important drivers of impervious surface formation.