Integrated Identification and Spatial Differentiation Mechanism of Urban Built-up Area in Changsha-Zhuzhou-Xiangtan Urban Agglomeration Based on the Multi-source Big Data
Taking Changsha-Zhuzhou-Xiangtan urban agglomeration as the study area,this paper carries out the integrated identification of urban built-up areas of Changsha-Zhuzhou-Xiangtan urban agglomeration based on the multi-source big data such as Luojia-1 night light,POI and OSM road network,and uses Geodetector to analyzes the spatial differentiation mechanism of built-up areas'density and efficiency from six major aspects.The results show that:1)Eight combination types It portrays the functional spatial layout of cities and towns in Changsha-Zhuzhou-Xiangtan urban agglomeration based on eight combination types from different dimensions.According to the integrated identification of multi-source data A1∪B1∪C1,it better realizes the complete and accurate extraction of built-up area information,which makes up for the shortcomings of single data identification or pairwise integration.The area of built-up area is 1890.19 km2,accounting for 6.73%of the total land area,and the spatial information is more comprehensive and suitable for the actual situation relative to the surface coverage remote sensing image interpretation.2)The built-up area in cities and towns of Changsha-Zhuzhou-Xiangtan is characterized by the structure of"one main district and two sub-districts,multiple clusters and multiple nodes,axis-belt expanding",with obvious regional differences and spatial differentiation.The density differentiation at district and county scales shows an irregular circle structure,with low-value areas in the eastern,southern and western hilly areas of the urban agglomeration,the efficiency gradient shows the distribution pattern of"concentric circles+high in the north and low in the south".3)The spatial differentiation mechanism of density and efficiency of urban built-up areas in Changsha-Zhuzhou-Xiangtan is complicated.Density differentiation is mainly affected by natural and transportation conditions,population and urbanization,economic development,investment and consumption.Efficiency differentiation is mainly affected by urbanization,economic structure and level,real estate development and investment,and people's livelihood services.The factor interactions of built-up area density and efficiency have the two-factor enhancement and nonlinear enhancement effects on both built-up area density and efficiency,and the enhancement effect on efficiency differentiation is more significant.