| The Yangtze River Delta is one of the most developed regions of China's economy and an important node of the Yangtze River Economic Belt.It has a pivotal strategic position in the overall situation of national modernization and an all-round opening pattern.Since the 1990 s,urbanization in the Yangtze River Delta has gradually accelerated,and the urban land area has been increasing.This paper uses the seven series of Landsat remote sensing images in 1990,1995,2000,2005,2010,2015 and 2017 as the main data source to extract urban land use information in the Yangtze River Delta.With the support of remote sensing and mapping geographic information technology,the spatial and temporal evolution of urban expansion in the past 30 years was analyzed,including the characteristics of area change,expansion intensity and difference,directional characteristics,heat distribution and spatial pattern index,etc.;Analyze the driving factors that affect the expansion of cities and towns,further establish an evaluation index system for urban development quality,and conduct multi-angle analysis of urban development quality.This study provides basic data on urban development quality for urban expansion,driving force,and spatiotemporal response in the Yangtze River Delta region,and provides a scientific basis for sustainable social and economic development in the region.It is expected to promote basic research on urban development quality in the Yangtze River Delta region.The main conclusions of this study are:(1)The area of urban land in the Yangtze River Delta has increased significantly from 1990 to 2017.Urban expansion has significant spatial characteristics,and the overall trend of continuous expansion has been shown.The urban land area in the Yangtze River Delta region showed a steady increase.There are stage differences in the direction of expansion.Before 2010,towns in the northwest-southeast direction expanded violently.After 2010,towns in the northeast-southwest direction expanded gradually.The spatial distribution of expansion heat gradually developed into a continuous pattern with time.Among them,the central region of the Yangtze River Delta is typical.It not only has extremely high heat distribution,but also radiates the surrounding areas,which in turn leads to the spread of urban expansion heat spread to the surrounding areas,and promotes the integration of urban development in the Yangtze River Delta.(2)The driving factors include economic and investment factors,population and labor factors,social development and education factors,municipal and medical factors,and service and transportation factors in the Yangtze River Delta The spatio-temporal evolution of urban expansion in the Yangtze River Delta is affected by factors such as policy,society,and economy,and the driving factors are also included to reveal the changes in urban driving influence.The driving factors for urban expansion in different periods are different,but the most dramatic changes in the intensity of the effect are economic and investment.Drivers and population and labor drivers.(3)A quality index system for urban development in the Yangtze River Delta has been established.Based on the principles of scientificity,comprehensiveness and feasibility,combined with existing research,incorporating remotely monitorable indicators,specifically covering economic,social and ecological aspects,a quality indicator system for urban development in the Yangtze River Delta region was constructed Based on the TOPSIS idea,a multi-segment function urban development quality evaluation model has been established,which evaluates the urban economic development,social development and ecological development quality,and comprehensively reflects the urban development quality.(4)From 1990 to 2017,the quality of urban development in the northwestern region of the Yangtze River Delta was low,and the urban development quality in the eastern coastal region of the Yangtze River Delta was relatively high.Regional differentiation still exists.At the municipal level,Shanghai has the highest urban development quality in the Yangtze River Delta,followed by Hangzhou,Nanjing,Suzhou,Hefei and other regions,while regions with lower urban development quality are Fuyang and Liuan.In the process of the continuous expansion of cities and towns,attention should be paid to the construction of the ecological environment to promote the coordinated development of economy,society and ecology;and in order to reduce the regional differentiation of the quality of urban development,Shanghai development should be the core,and each provincial capital and important city should be the node Accelerate the integration process of the Yangtze River Delta,and radiate the high-quality development of cities and towns in the Yangtze River Delta. |
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