County Town Spatial Extension Characteristics And Influence Factors Analysis

Urbanization is an important economic and social phenomenon; urban spatial expansion is the most obvious feature of urbanization. Therefore, it is of important realistic significance to study the evolution of urban spatial morphology. This paper takes Lishui as an example, explored the characteristics of space and time of urban spatial expansion since1978, revealed drive mechanism of urban spatial expansion, proposed strategy about optimization of urban expansion.On the basis of reviewing present study situation of domestic and international urban spatial expansion, this paper defines the specific content of this study. Firstly, by six periods remote sensing image data sources of Lishui form1978to2008, based on ERDAS, interpreted land use status chart; secondly, based on GIS, form time process, space differentiation, morphology evolution three perspectives, analysed spatial-temporal characteristics of urban spatial expansion; thirdly, form six aspects, this paper revealed influence factors of urban spatial expansion; lastly, this paper puts forward reasonable suggestions and measures of urban spatial expansion.Conclusions of this paper are as follows:1)all urban land expansion presented a "stepped-weir" evolution rule, urban town land expansion presented a "Z glyph" evolution rule, general towns presented a "straight line glyph" evolution rule; based on expanding speed and expanding strength, divided into urban spatial expansion of the "low speed period (1978-1989)","growth speed period (1989-2001)" and "rapid speed period (2001-2008)" three stages, and this paper analysed the rationality of the urban spatial expansion, got basic unanimous conclusion;2) town domain scale, urban spatial expansion showed four concentric circular from the county to outside; envelops scale, urban land use presented a "distance from the city centre more far, urban spatial expansion strength more weak" rule; azimuth scale, urban spatial expansion direction is the north and east since1978;3) urban use fractal dimension has been in the rising state, urban use compact degrees presents declining trend, it showed that urban spatial expansion model is "outside postpone type" since the reform and opening up;4)this paper preliminary analyses the comprehensive effect relations between urban spatial expansion and planning policy, industrial agglomeration, the third industry development, the population factors, traffic organization, social and cultural factors and so on;5)from making the rational urban and land planning, setting up the border of urban growth, optimizing urban use space structure, the paper proposes optimization control strategy for urban spatial expansion, guiding urban spatial expansion toward more reasonable scientific development road.