Monitoring urban expansion with remote sensing in China

The Open Policy and Economic Reform has imposed a profound impact on dynamic changes of land-use patterns in many areas of China over the last two decades. Rapid urbanization and industrialization have resulted in a sharp reduction in arable land acreage. A project was carried out in 1997 under the auspices of the China State Land Administration to monitor the dynamics of urban expansion in 100 municipalities throughout China. This paper describes the implementation of the project and reports on some of the results obtained. Landsat Thematic Mapper (TM) images acquired for 1989/1992 and 1996/1997 were used to examine the scope and the speed of urban expansion in this period. Change detection techniques were employed to identify the areas of urban encroachment. Statistics on preceding states of the expanded urban areas were generated and various thematic maps were produced. The results showed that urban development in southern and coastal areas is the fastest, and the highest speed of urban expansion is as much as 30% per year. Urban growth is estimated at 1.2 million hectares for the whole country during this period, and 0.867 million hectares of arable land have been lost due to urban expansion.