Response Mode,Mechanism And Strategies Of Urban Spatial Expansion In The Process Of Urbanization

The response modes,mechanism and development strategies of urban spatial expansion in the process of urbanization are of great significance to the healthy development of urban agglomeration.Taking Guanzhong Plain urban agglomeration as the research object,based on national statistical yearbook,various statistical data and night lights data,this study uses mathematical quantitative model,GIS spatial analysis and methods of empirical case studies,to explore the response of urban spatial modes,mechanism and development strategies from the perspective of the internal correlation between urbanization and urban spatial expansion.Firstly,after sorting out the background and literature,the comprehensive index evaluation method and entropy value method are used to determine the urbanization development index,then analyze its evolution characteristics.Secondly,the built-up areas are extracted from the night light data to characterize the urban spatial expansion,and the relevant indexes are used to interpret the evolution characteristics of them.Then it comprehensively uses the coupling coordination model and the allometric growth model to explore the inner relationship between urbanization and urban spatial expansion,then identify the spatial expansion response mode of each city.Finally,the stepwise regression analysis is used to clarify the response mechanism of urban spatial expansion in the process of urbanization.Combined with the response mode,the characteristics of different types of cities are analyzed and appropriate development strategies are proposed.The main research conclusions are as follows:(1)Based on the theoretical connotation of urbanization,an evaluation system of 14 indicators in the four subsystems of population aggregation,economic development,social security and ecological environment is constructed,and then the urbanization development index of each city in different research years is calculated by means of weighted summation using the entropy method.According to the analysis,the urbanization development of Guanzhong Plain urban agglomeration from 1992 to 2017 has three significant characteristics: continuous growth,spatial differentiation and systematic bias.(2)Urban spatial expansion is characterized by the built-up area of each city extracted from night light data,and then the speed and intensity of spatial expansion in different research periods are calculated.The analysis shows that the urban spatial expansion in Guanzhong Plain urban agglomeration from 1992 to 2017 has three significant characteristics: continuous growth,intensity stage and urban difference.In order to properly grasp the development opportunities and avoid the waste of land resources,different cities should adopt appropriate spatial development strategies.(3)Urbanization and urban spatial expansion in the Guanzhong Plain urban agglomeration are characterized by "high coupling and low coordination".Therefore,spatial development mode should be reasonably divided to promote healthy development.The slope k value of the trend line in the double logarithmic growth model effectively reflects the coordination and development priority of the two,then becomes the basis for the identification of the response mode of urban spatial expansion.According to this,it can be divided into four types: urbanization leading,balanced development,spatial expansion leading and spatial expansion imbalance.Compared with the urban agglomerations in coastal areas,the urban spatial expansion in Guanzhong Plain urban agglomeration,which is still in the gestation and development stage,has not yet fully stepped into the transformation stage from "increment-led" to "revitalization-oriented".(4)According to the response mechanism,urban spatial expansion is affected by many factors such as population,economy,society,and ecological environment in the process of urbanization.It is a comprehensive reflection of the long-term effects of factors such as the per capita GDP level,the number of students in middle school per 10,000 people,the ratio of tertiary industry to GDP,the proportion of urban population,the green coverage of built-up areas,and urban population density,etc.Based on the response mechanism and urban characteristics,the appropriate spatial development strategies of "revitalization-oriented","increment-led" or "dual-track approach" can be selected for the four urban spatial expansion response modes.And the planning enlightenment with universal applicability to other urban agglomerations in Northwestern China is proposed.