Regional differences of China's urban expansion from late 20th to early 21st century based on remote sensing information

This study investigated the regional differences of China's urban land expansion from the late 1980s to the year of 2008, based on the spatio-temporal analysis of CLCD (China's land cover/land use database) datasets which were mainly produced from remote sensing imagery data. A newly defined urbanization level index (UI), based on urban land area, is proposed to describe Chinese urban expansion process at 1 kilometer, provincial, regional, and national scales, together with the absolute urban expansion index (UEa) and the relative urbanization expansion index (UEr). The results indicate that the percentages of total land area occupied by urban in the late 1980s, 1995, 2000, 2005, and 2008 were approximately 0.25%, 0.32%, 0.33%, 0.43% and 0.52% of China's total land area, respectively. Between the late 1980s and 2008, the total urban expansion in the mainland of China was 2.645 x 10(4) km(2), resulting in an annual urban expansion area of about 1322.7 km(2)/yr, with the UEr of 111.9%. This study also finds that there has been an obvious spatial gradient of urbanization ratio running from the east coast to the west inland, and the urbanization gaps among different regions have persisted over the past two decades. The study also reveals obvious temporal variations of the urbanization rates. There was very little urban growth during the period of 1995-2000 due to the governmental policy factors.