Spatial Aggregation And Relationship Of Urban Land Use Intensity And Urban Vitality

During the rapid urbanization process,improving the intensity of urban land use has become one of the important measures to alleviate the unrestricted spread of urban land.However,without considering the level of urban social and economic vitality development,blindly improving the height of buildings and urban land density will have a certain negative impact on sustainable development.Urban land use intensity and urban vitality are two systems that influence and depend on each other.A deep understanding of their spatial matching and coordination relationship can provide theoretical basis for optimizing urban spatial planning,which is of great significance for improving the quality of urbanization and realizing the sustainable development of cities.In this study,impervious surface density and building volume density are used to represent urban land use intensity,nightlight radiance density and catering POI density are used to represent urban vitality.Taking 20 fast-growing cities in China as examples,the spatial agglomeration characteristics,matching and coordination relationship between urban land use intensity and urban vitality are explored.First of all,the center of 20 cities is determined by multi-source data,and the structure of center circle is constructed.On this basis,the absolute index value of each circle of 20 cities is compared by circle analysis method,and the distribution of indicators and systems are simulated by the inverse S-shape function.The differences of central aggregation between urban land use intensity and urban vitality are explored by concentration degree index.Secondly,using global and local Moran's I,the spatial correlation and local mismatch relationship between urban land use intensity and urban vitality are analyzed on the grid scale.Finally,the coupling relationship and coordination relationship between land use intensity and urban vitality are analyzed by coupling degree model and coupling coordination degree model,and the overall level of various spatial relationships in 20 cities is compared.The main conclusions of this paper are as follows:(1)In general,the distribution of impervious surface density,building volume density,nightlight radiance density and poi density conforms to the law of decreasing from the city center to the outside.Among the four indexes,the difference of nightlight radiance density values in different cities is the largest.The attenuation speed of each indicators in Beijing,Shanghai and Guangzhou is relatively slow among 20 cities.(2)The inverse S-curve of urban density can well fit the circle distribution of the two systems and four indicators in this study,but it is not suitable for the multi cluster structure of Shenzhen.Compared with the urban land use intensity,the urban vitality of Dalian and Wuhan is at a low concentration level,which of Shanghai is at a high concentration level.(3)The spatial correlation between land use intensity and urban vitality is positive.The spatial correlation between Xi'an and Jinan is relatively strong,while the spatial correlation between Dalian and Qingdao is relatively weak.The spatial distribution of agglomeration types in different cities is similar.The "L-H" cluster type is mostly distributed at the outer boundary of the "H-H" type,while the "H-L" cluster type is mostly distributed at the inner boundary of "L-L" type.The area with advanced land use intensity is relatively large,which indicates that it may be necessary to further optimize the regional structure and stimulate the growth of urban vitality(4)The distribution of coupling grade and coordination grade all meet the rule of decreasing from the city center to the outside,but the structure of grade composition is quite different.The spatial correlation,matching relationship,coupling relationship and coordination relationship of land use intensity and urban vitality rank relatively high in Changchun,Jinan,Shenzhen,Shijiazhuang and Tianjin.