The Study On The Spatial-temporal Patterns Of Urban Expansion In Shenzhen

With the development of economy,cities around the world enter the period of rapid development.The process of urban expansion is accelerating.The study of urban expansion is helpful to analyze the current situation of urban development and provide a favorable basis for sustainable urban development.At present,the study of urban expansion is mainly focused on the expansion of urban space,which ignores the analysis of the degree of urbanization.The study takes the typical city of rapid urbanization-Shenzhen as the research area,uses the technology of linear spectral separation to extract the impermeable surface of the year of 2000,2006 and 2010 in Shenzhen,combines with DMSP/OLS,studies the spatial and temporal pattern of urban expansion and the change of urban expansion type in Shenzhen and analyzes the difference between planning area and non-planning area,explores the reasons for the change of urban expansion.The results of the study are as follows:(1)Based on the technology of linear spectral separation to extract impermeable surface of the year of 2000,2006 and 2010 in Shenzhen to express the spatial characteristics of urban expansion.The average value of impermeable surface index were 0.47,0.54,0.63,according to the results of the extraction,the urban expansion of Shenzhen has been deepened with time.(2)Selecting the impervious surface index and the DMSO/OLS as the index of the urban expansion type,the study area is divided into three types of urban expansion as high,medium and low class,from 2000 to 2010,the main types of urban expansion exchange from the "low-low" class to the "high-medium" class to "high-high" class.The area of low class turns out a large-scale reduction,the area of medium and high class both have expansion,which the trend high-class type of regional expansion is obvious,each type has a change of transfering-in and transfering-out,the type of low-class mainly represents changing of transfering-out,the type of high-class mainly represents changing of transfering-in.(3)In order to distinguish the differences of urban expansion between government-led planning areas and collective economic organizations in the non-planning areas,urban expansion,according to the land use type and ownership survey,the study area is divided into planning area and non-planning area.The analysis of impermeable surface index and spatial autocorrelation Moran’s I shows that the urban development of non-planning area is more intensive,the spatial autocorrelation degree of the planning area is higher than the area of non– planning,the relationship between the city is close,conform with the regular of urban expansion.The degree of autocorrelation of the non-planning area is relatively low,the spatial distribution of urban is less relevant,the Moran’s I of the impervious surface of the planning area is increasing,the distribution of urban areas within the planning area is more and more regular,the non-planning area of Moran’s I is decreasing with time,the degree of autocorrelation is getting lower and lower,the regularity of urban distribution is worse,the non-planning area has the trend of rapid irregular distribution.(4)The factors that affect the urban expansion in Shenzhen include three aspects of nature,society and policy.Adjacent to Hong Kong’s unique geographical advantages,the establishment of the Shenzhen Special Economic Zone and the support of a series of preferential policies of country,make the city of Shenzhen a greater development in a short period of time,while the existence of the differences of policy also makes the expansion of urban space is different.