Spatial-temporal differentiation of urban land area expansion intensity and the influence factors in Guizhou

The land use data are acquired from the TM images of 1995, 2000, 2007 with the aid of Erdas and Arcview software. The urban expansion intensity index in every county of Guizhou are calculated and the influence factors to the expansion of urban and town involving transportation, economy and natural conditions are analyzed. The results show that:1)there are16 cities and towns with high expansion speed from 2001 to 2007,butin the period of 1995 - 2000 there are only 5 cities and towns with high expansion speed; 2)big cities on the North-South traffic axis (Zun-Chong Expressway, Gui-Zun Expressway, Gui-Xin Expressway, State Road 210) and East-West traffic axis (Kai-Ma Expressway, Gui-Huang Expressway, State Road 320) expand faster, and the rapidly expanding locations appear near the center of traffic intersection and this trend gets more and more obvious; 3)in view of the expansion intensity grade, the expansion intensity gradually increases, from low speed, low-medium speed, medium speed, medium-high speed to high speed. There is a direct proportion between the grade of road and the urban expansion intensity, in other words, the high the grade of road, the larger the urban land area expansion intensity along the road. Economy is an important factor to urban expansion, high speed development of economy strengthens urban expansion. Flat landform is beneficial to urban expansion, while uneven land can impede urban expansion.