Research On The Spatial-Temporal Features And Driving Forces Of Urban Spatial Expansion In Chongqing Yubei District

More population with less land and the lack of farming resources have always been China's basic national conditions.With the rapid development of social economy,the speed up industrialization and the rapid increase of population,urbanization in China has also been accelerated since reform and opening.The most important manifestation of urbanization is the expansion of urban space.And over this stage,urban space and sprawl is one of the main factors of the increasing acute contradiction between population and land resources.Through the analysis on urban expansion,we can provide effective spatial decision support for the sustainable development of urban.In this dissertation,Yubei District is taken as the research object.We extract the information of regional land use by using RS and GIS technology on the basis of four remote sensing images in 1996,2002,2008 and 2014;in order to research and analyze the spatial and temporal characteristics of urban spatial expansion,we obtain the scope of urban physical area of Yubei District by using the index model of integrated land use on the basis of classification of land use;last,we find the key driving factors of the urban space expansion in Yubei District and put forward reasonable and scientific countermeasures and suggestions for the sustainable development of the city of Yubei District in the future.The main research conclusions are as follows:(1)The rate of Yubei District urban expansion showed a trend of first increase and then drop.This city expanded faster during 1996-2002 and 2002-2008 with the types of rapid expansion and high speed expansion;while the rate of urban expansion has dropped slightly and changed to the type of medium extended in the period of 2008-2014.Generally speaking,the speed of urban spatial expansion of Yubei District is very fast and the elasticity coefficient value of urban area-population is much larger than the reasonable coefficient of urban spatial expansion,which needs to be adjusted in the future development of the speed of the urban expansion.(2)With the rapid expansion of urban space in Yubei District,the discrete level of its urban entity distribution has been increasing continuously.Although the degree of irregular urban morphology is also growing,the trend is slowing down and the outer contour line of the city is increasingly complex.The dominant direction of urban spatial extension is always in its southwest and northeast,but the east-southeast and northwest urban space expansion efforts are growing,too.In the process of urban spatial extension,Yubei District has been severely affected by the urban expansion axis from the Jiangbei Airport to the central districts of Chongqing,which results the mode of main urban expansion of Yubei District transformed into the axial extended mode and compact spatial expansion mode in the period of 1996-2008.However,due to decrease of gland resources,the main mode of urban expansion of Yubei District transformed into the mode of intensive expansion and multi-core jump expansion in the period of 2008-2014.(3)The expansion of Yubei District urban space is restricted by the natural and geographical factors to some extent.However,the social and economic factors are the main driving force of city spatial expansion and government policies not only promote the development of the city,but also guide the expansion of urban space.After the quantitative analysis of the social and economic factors,we find that the two common factors that influence the expansion of Yubei District urban spatial mainly are both population-economy(extensive)factor and transportation-economy(intensive)factor.The main factor of promoting the expansion of urban space in Yubei District is population-economy(extensive)factor which represents the growth of population and others extensive economic like construction and manufacturing industry and heavy industry.(4)In the future development of the city,Yubei District should establish the scientific concept of development and start actively using the land of low mountains and hills;control the city size scientifically and reasonably and improve the degree of intensive use of land;optimize the structure of urban industrial and transform the model of urban expansion;continue to deepen reform and further improve the land management system.