Research on Expansion of Built-up Area in Zhengzhou during 1999—2007 based on Multi-original Remote Sensing Images

The expansion of Zhengzhou urban area in the period from 1999 to 2007 was obtained by using remote sensing images.The spatial-temporal features of the urban expansion and the relationship between urban expansion and population growth in the period were analyzed by using some indexes on three aspects of quanity,shape, and rationality.The research shows that the built-up area has increased 211.802 km2,extend velocity is 26.475 km2,and extend intension is 27.222% in the period. The urban space shape becomes more and more scatter.The important feature of Zhengzhou urban expansion is the high speed extension outside pattern.The urban sprawl rate of Zhengzhou did not match urban population growth during the study years.