Spatiotemporal Analysis of Built-up Area Sprawl in a Typical Hilly City in the Recent 30Year

As a typical hilly city,Chongqing experienced a dramatic expansion about its built-up area in the recent 30years after the implement of the open-door-policy.It′s necessary for us to understand the expansion of its built-up area.A method about how to divide the built-up area expansion considering the spatial topological relations between 2built-up area objects was conceived and the the sprawl of built-up area in the horizontal and vertical direction was analyzed.The result of this study indicated that:(1)the built-up area expanded from 5 885.69hm2 to 29 347.47hm2 in the study region;(2)outlying sprawl was the main sprawl type;(3)the built-up area centroids of different periods elevated from 250.40mto 284.61min the vertical direction from 1978to 2007.The conclusion was that the built-up area of a typical mountain city expanded dramatically afar the implementing of open door policy in Chongqing city,the dramatic transform of land use may affect the regional ecology security,it is also very important to guide the urban expansion from the plan perspective.