Study on Urban Spatial Morphology with RS Fractal - the Case of Wuwei in Arid Region of Northwest China from 1967 to 2004

摘要

Based on the analysis of RS data and fractal in modeling the spatial-temporal changes of urban spatial morphology in the study area during the 38 years from 1967 to 2004, we reached the following main conclusions. First, three fractal dimensions of urban form of Wuwei in 1967, 1998 and 2004 were 1.5397, 1.7086 and 1.7717 respectively (all less than 2), which indicated the land use density of Wuwei decreased from centre to margin. Second, these fractal dimensions, greater than the mean of experiential urban fractal dimensions, were increasing gradually from 1967 to 2004, which showed the urban form was in a more compact state at present. Third, urban form fractal dimension variation of Wuwei consisted of two stages: urban form changed rapidly from 1967 to 1987 while grew slowly from 1987 to 2004. Fourth, the analysis of urban spatial form based on Allometric Growth Model showed that fractal dimension of urban population was greater than urban land use. So the abnormal urban form should be modified by transforming the state of the population concentration. As the given results, it can be concluded that urban expansion in undeveloped arid regions was not in a linear trend but among coupled interactions. Water resource available for utilization and land resource suitable for development are the two most dominant control factors for expansion of mountain-oasis-desert urban region. This paper indicates the implementation of the urban plans and policies is not very good in Wuwei, that is to say, there are still many problems in urban planning and decision-making in China.