Study On The Spatiotemporal Evolution And Driving Forces Of Urban Expansion In Anhui Province Based On Nighttime Light Remote Sensing Data

With the rapid economic development,the size and number of cities in China have increased rapidly,and the process of urban expansion in various regions has also been accelerating.However,in the process of urban land expansion,a series of urban problems have also arisen,such as increasing urban population,uneven regional development,and deteriorating urban environment,which have caused more and more attention and thinking.Because the changes in built-up areas directly reflect the urban spatial form and human concentration,they have a huge impact on urban land use efficiency,social and economic development,and the natural ecological environment.Therefore,the use of relevant technical means to dynamically monitor and analyze the expansion of urban built-up areas and the study of driving factors for urban expansion is particularly important for making decisions about sustainable urban development.The use of remote sensing technology can quickly and effectively obtain the boundary of the urban built-up area,which provides data support for the analysis of urban expansion spatial changes.This article takes Anhui Province as the research object,using the nighttime lighting data of DMSP/OLS in 2007,2012 and NPP/VIIRS in 2017 to extract the information of urban built-up areas of 16 prefecture-level cities in Anhui Province.Quantitatively analyze the changes and regional differences in the expansion time,space and structural form of cities in Anhui Province,and qualitatively and quantitatively analyze the socio-economic,transportation,and environmental factors that affect urban expansion in Anhui Province Finally,the corresponding countermeasures and suggestions are put forward for the problems and driving factors of urban expansion in Anhui Province.The main research contents and conclusions of this article are as follows:(1)Nighttime lighting data can quickly and effectively extract information on urban built-up areas on a regional scale.In this paper,the nighttime light data are processed by mutual correction,continuity correction,desaturation correction and noise removal.Based on this,combined with statistical data,threshold dichotomy is used to extract the urban builtup areas of various cities in Anhui Province in the past 10 years.The overall error of the extraction results and statistical data is within 10%;the high precision images of Google Earth are used to verify the spatial accuracy of the extraction results,and the average accuracy reaches 90.8%,which meets the data accuracy requirements for the analysis of the expansion and change of urban built-up areas in Anhui Province.(2)On the basis of extracting the built-up area with remote sensing data,the expansion speed,expansion dynamics,compactness,fractal dimension,urban first degree and other indicators are used to analyze the expansion time,spatial shape and urban structure of the urban built-up area in Anhui Province in the past 10 years.The research shows that the overall expansion speed of cities in Anhui Province is relatively fast,but there are obvious differences in time and space.From 2007 to 2017,the expansion intensity and expansion dynamics of cities in Anhui Province generally showed an increasing trend,and the city coordination was The situation has improved,but the degree of disorder is still relatively high.In addition,the inter-annual differences in the compactness and fractal dimensions of the cities are large,indicating that the urban expansion patterns are different;from 2007 to2012,the centers of gravity of the cities mainly moved to the southeast,and from 2012 to2017 The number of cities migrating to the southwest and northeast has increased;the economic agglomeration effect of Anhui Province is higher than the population agglomeration in the past 10 years,and the overall urban scale is more balanced.The gap is obvious.(3)The qualitative and quantitative analysis of the driving factors of urban spatial expansion in Anhui Province.Combined with the city characteristics and statistical data of Anhui Province,a qualitative analysis of socio-economic,transportation,environment,population,policy and other factors affecting urban expansion was carried out,and on this basis,a driving force indicator system was constructed,through principal component analysis and stepwise regression The analysis concludes that the gross output value of GDP and the per capita housing area of urban residents are the leading drivers of urban expansion in Anhui Province.(4)According to the problems and driving factors of urban expansion in Anhui Province,Anhui Province should formulate a reasonable urban development plan in the future urban development,give play to the economic driving role of the central city,promote regional coordinated development,improve the transportation network,and continuously optimize the spatial layout.Strengthen the degree of urban land intensive,and build a reasonable relationship between land and population urbanization.