Spatio-temporal Dynamics Monitoring And Driving Factors Analysis Of Built-up Areas In Jiangxi, China

Urbanization is an important socio-economic phenomenon in the present era.Modern cities gather population,economics and natural resources with locational advantage and its expansion represents a center transfer of regional politics,economy,technology and culture.In recent years,the rapid progress of urbanization has become a significant achievement in the development of various countries and regions.However,with the expansion of urban land,problems such as unbalanced development between regions,widening urban-rural disparity and saturation of urban resources bearing capacity become increasingly prominent,which causes more and more attention worldwide.Built-up area,as one of main types of land cover in urban,directly reflects the activities of human beings and level of urban construction.Its changes have a negligible impact on urban economic development,resource utilization,and ecological and environmental protection as well.Therefore,the dynamic monitoring of urban built-up areas at regional scale is of great value for understanding the urban development process,assessing the level of urban land use,and formulating more reasonable urban construction strategies.Remote sensing has become one of the main technical approach in monitoring large-scale land-use dynamics,the application of remote sensing data can effectively extract urban built-up areas on a regional or larger scale,and studying the changes is of great significance for monitoring the evolution of urban spatio-temporal patterns.Taking Jiangxi Province where the terrain is complex and the urban development level is relative low as research area,the main work of this study is to monitor spatial and temporal dynamics of built-up area for 20 years(1995,2000,2005,2010 and 2015).Firstly,Landsat images were used to extract urban land with Support Vector Machine(SVM)classification algorithm.Then,the introduction of DMSP/OLS nighttime data optimized the classification result.On this basis,quantitative analysis were made to describe the changes in spatial characteristics of urban built-up areas and the driving factors of urban land expansion were explored based on multiple sources of information such as economy,population,and transportation.The research has made some explorations on the extraction methods and spatial expansion analysis of urban built-up areas on provincial scale as well as provides reference for regional and higher-scale urban research.The main contents and results of the research are presented as follows:1)Nighttime light data has unique advantages for urban information acquisition at the regional scale.In this research,morphological operations are used to identify city boundaries on nighttime light images,which can effectively filter out extraneous noises outside urban areas.The overall spatial accuracy of the result extracted with combination of DMSP/OLS and Landsat data reached 92%,which is 13%higher than that with Landsat alone.In addition,there was a significant positive correlation between the extracted results and statistical data(R2=0.795).It shows that this method has good applicability in Jiangxi Province,and the extraction results can be used for quantitative analysis of spatio-temporal dynamics of urban expansion in Jiangxi Province later.2)Based on the built-up extraction result,the spatio-temporal characteristics of the expansion of built-up areas in Jiangxi Province in the past 20 years were analyzed.It shows that the expansion of built-up area in Jiangxi Province has accelerated after 2005.However,the overall expansion intensity was low,and the intensity of urban expansion in North is stronger than in South.In addition,the expansion direction of the built-up areas in Jiangxi Province is mainly concentrated on north,east,and southwest,and the built-up areas expansion in the west and the northwest are intensified after 2010.Landscape metrics of built-up areas in each city of Jiangxi Province were calculated and it concluded that the urban structure in Jiangxi Province is relatively dispersed and the main urban area expand more rapidly.At the same time,the spatial connection between the built-up areas in the city is gradually strengthened.3)Analysis of the driving factors of urban expansion in Jiangxi Province reveals that the expansion of urban built-up areas in Jiangxi Province is guided by the government's development plans and strategies.The establishment of city group and economic zone effectively promotes the development of related cities.Newly constructed built-up areas in Jiangxi Province are mainly concentrated in the low-lying plains and the scale of built-up area has a significant positive correlation with the population and economic development level.Transportation lines such as railways and highways outside the city can lead to the expansion of urban land use,and the density of road network within the city is in line with the expansion intensity of urban built-up areas.In addition,multi-centered urban structure betterly promotes the overall development of city.