Study On Urban Spatial Multidimensional Expansion Of Nanjing Based On Land Use Perspective

Since reform and opening up,China has entered into a period of rapid urbanization.While many large and medium-sized cities are expanding in a two-dimensional and sprawling way,the trend of urban vertical stretch is more and more obvious.Currently only from the two-dimensional perspective to study the expansion of cities and the evolution of urban morphology but ignore vertical stretch of cities and the intensity of land use,which to some extent influences the understanding of the rules on urban spatial expansion,land use change and urban spatial form change.This dissertation expands the research methods of urban spatial two-dimensional expansion and forms the research methods of urban spatial multidimensional expansion based on relative studies.It selects Nanjing as the object of empirical study,gives a comprehensive analysis on the process,mechanism and pattern of urban spatial expansion and the evolution of urban spatial morphology with land use perspective based on multidimensional angle,deepens the understanding of the rules of urban spatial multidimensional expansion,analyzes the rationality of urban multidimensional expansion by evaluating the intensive degree of urban land after expansion,and gives some advice on urban spatial multidimensional expansion in the future.This research will help to expand the horizon of urban spatial expansion,have a comprehensive command of the laws of urban spatial expansion and provide the scientific basis for city planning and land use planning.In order to solve scientific problems of urban spatial multidimensional expansion,this dissertation builds the methodology of urban spatial multidimensional expansion analysis.The main conclusions are as below:(1)Method and procedure which accord with the fact of study area to extract the information of land use category fast and accurately from a large scale is put forward by applying layered information extraction method based on knowledge and rules and by adopting medium resolution remote sensing image;(2)Based on high resolution remote sensing image,this dissertation improves the technical method which obtains building outline and building height,proposes a digital reconstruction method on the land use spatial structure of inner urban built-up area based on the method of hierarchical classification and object segmentation and the vertical structure of Nanjing urban built-up area is digitally reconstructed;(3)In the study of urban two-dimensional space expansion,integrates GIS two-dimensional space analysis model and method and delves into application methods of transfer matrix in the analysis of land use evolution;Broadens the research method of urban focus shift,urban fractal dimension and land use transfer matrix from two-dimension to multi-dimension and builds three dimensional urban morphology change quantitative analysis index system and analysis method based on the grid;(4)In the study on the relationship of multidimensional spatial expansion,limited voronoi diagram and building area-building height diagram is introduced and volume growth contribution rate is put forward to divide the stage which urban spatial multidimensional expansion is in;(5)Introduces Neural Network Model into the intensive use appraisement of urban land based on function area of land use.On the support of research method of urban spatial multidimensional expansion,this dissertation analyzes the urban spatial multidimensional expansion of Nanjing,and main results are as follows:(1)The characteristic of time variation and spatial differentiation of Nanjing is obvious,and the city is in the transition from rapid spread way to the internal expansion way of internal structure optimization and integration;(2)From 1980 to 2012,Nanjing urban built-up area is in rapid expansion,and the main transfer method of land use type in this period is from farm land to urban construction land;The disorder degree of land use type transfer is small except urban inner land use type,and land use evolution is relatively in good order,land use structure is toward balanced development gradually;(3)Nanjing is in a process of constant update and reconstruction,and in the evolution from two-dimension to three-dimension.High rise buildings of Nanjing keep a high construction speed after 2000 and the fluctuation of urban skyline is obvious.In recent 12 years the three-dimensional focus has transformed from southeast to west;(4)By using remote sensing classification method of multidimensional feature space,three-dimensional quantitative indicators of urban morphology is analyzed comprehensively,urban three-dimensional morphology is divided into 6 zones.The square of every zone is expanded distinctively and these zones are evolving from circle layer structure to mutual interpenetration;(5)Land use type is related to intensity of land use to some degree.The plot ratio of residential land and commercial land increases most rapidly and the plot ratio of new construction land in the process of urban expansion also keeps in a relatively good level in recent 12 years;(6)From 2000 to 2012,the urban morphology of Nanjing has been in the transition from weak pyramid stage to dome top stage.In recent 12 years,urban sprawl expansion experienced the different stages of accelerate,fast and slowdown,urban internal potential mining experienced the different stages of moderate,slowdown and accelerate;(7)Nanjing has been in multidimensional expansion for more than 30 years.Currently the status of land intensive use is good in general,and has the trend that land intensive use degree is gradually decreased from the urban core to outside.On the whole commercial land has a status of high intensive use,residential land and education land have the status of intensive use,while the intensive degree of industry land is relatively low;(8)The land use potential is larger in Nanjing.The scale potential is mainly distributed in Pukou District,Qixia District and Jiangning District,while the scale potential of main urban built-up area is low.The dissertation sets the temporal development sequence of urban land use,and puts forward some control measures.The innovations of the dissertation are as follows:(1)Based on multidimensional perspective,puts forward the study methods of urban sptial multidimensional expansion,broadens the study models of urban extension from two-dimension to three-dimension,and improves the application of some study methods;(2)Deeply analyzes the pattern,process,mechanism and benefit of urban spatial multidimensional expansion;(3)Carries on technology innovation on urban multidimensional spatial and temporal information digital reconstruction.