Analysis on urban expansion and its driving forces of Tai'an from 1979 to 2005 based on RS and GIS techniques

The objective of this paper is aimed to measure and analyze urban expansion and its driving forces of Tai'an from 1979 to 2005. The research work depended on interpreting multitemporal satellite images and made use of GIS analysis. Using various data of Landsat MSS (1979), Landsat TM (1987, 1997), QuickBird (2005), urban spatial information was classified and extracted by a decision tree algorithm, which is an effective and efficient approach to obtain urban expansion map. Meanwhile, intensity index of expansion is brought in to study the urban expansion problem. The laws of the expansion intensity, direction and tendency are discovered by area statistic and overlay analysis, the expansion rate was distinct in different time and direction, and the built-up area expanded basically along with the newly built road. The results show that the area of Tai'an has expanded by 540% in the period 1979-2005 with an annual growth rate of approximately 20%. At the same time, combined with the historical statistic data of society and economy, the main driving forces of the urban expansion including natural resources and environment, population and economy, national policy, transport and historical culture are all obtained and analyzed. Urban expansion is an important indicator for studying urbanization level, land use situation and urban heat island. The method and results above have important implications for the sustainable development of Tai'an and other cities.