Spatial-temporal Differences Of Urban Land Use Efficiency And Its Influencing Factors In Yangtze River Economic Belt

Urban land is the space carrier of urban construction and development,and it is also the material basis of urban economic and social activities.Since the reform and opening up,China's economy has been developing rapidly,and industrialization and urbanization have been rapidly promoted.The rapid expansion of urban land has become an important feature of land use in China.According to statistics,from 2003 to2015,the area of urban construction land increased from 23267km~2 to 51584.1km~2,the annual growth area was 2178.23km~2,the annual growth rate was 9.36%.The elastic coefficient of urban land growth was much higher than the reasonable value,and the contradiction between the demand of urban development and the limited supply of urban construction land has become sharper.Under the background of rapid urbanization,the problem of extensive use and inefficient use of land have been gradually highlighted,and the constraints of land resources on urban economic growth have gradually emerged.In the case of the increasingly strict policy of the national cultivated land protection,the extension mode of urban extension has been difficult to continue.To maximize the economic output with minimum land input and improve the efficiency of land use is an urgent task for China in achieving sustainable utilization of land resources and promoting the process of urbanization.The economic belt of the Yangtze River which is an inland river economic belt across the three major regions of East and West in China contains different types of cities.Although China had put forward a series of strategic policies,such as the development of the west and the rise of the central,the imbalance of economic development,the irrational allocation of resources and the large difference in land use level were still the main problems at this stage.Since the 19th National People's Congress,China has entered a new era of socialism with Chinese characteristics.The main contradiction of society has been transformed into the contradiction between people's growing demand for better life and imbalance and inadequate development.Narrowing the gap and coordinating development have become the meaning of development.In 2016,with"the development plan outline of Yangtze River economic belt"formally issued,the construction of Yangtze River economic belt has risen to a major national strategy,the significance of this strategy was not only to build inland river economic belt,but also to strengthen complementarity between upstream,middle and lower reaches,narrow the gap between eastern and central and western regions,achieve regional coordinated development,and provide new support for the coordinated development of the whole country.As the main carrier of the development of the city of the Yangtze River economic belt,to study the existing land use problems and the level of land use efficiency in the economic belt cities was of great theoretical and practical significance in improving the level of intensive land use and achieving sustainable development of population,economy and society in every region of the Yangtze River economic belt.This paper took data of 126 cities in the Yangtze River economic belt from 2003 to2015 as data samples,and constructed a comprehensive evaluation index system from three angles of input,expected output and unexpected output,used the super efficiency SBM model which considered unexpected output to calculate and analyze the spatial and temporal characteristics of the urban land use efficiency of the Yangtze River economic belt.At the same time,based on the GTWR model,paper discussed the influencing factors and mechanism of urban land use efficiency in the Yangtze River economic belt,and proposed the paths to improve urban land use efficiency.The main conclusions are as follows:(1)In terms of time change,from 2003 to 2015,the urban land use efficiency in the Yangtze River economic belt increased step by step,and the efficiency level changed from relatively inefficient to relatively efficient one.The ratio of input and output increased and the redundancy decreased.Scale efficiency was greater than technical efficiency and productive efficiency,the level of the allocation of resource elements was not high.The urban land use efficiency of the economic belt was in a convergent trend,and the regional difference had been narrowed.The difference between the three major urban agglomeration was less than that in the group,and in the group differences,the Yangtze River Delta urban agglomeration was greater than the middle reaches of the Yangtze River and Chengdu-Chongqing urban agglomeration.With the coordinated development of the economic belt,the absolute difference and relative difference of urban land use efficiency were decreasing.(2)In terms of spatial evolution,the relatively inefficient cities were dominant,showing a trend of contraction from both sides to the middle,the relatively efficient cities were gradually expanding from the eastern coast to the inland.The center of gravity showed the reciprocating characteristics of"westward-eastward-westward"movement,the absolute moving distance was small,and the spatial pattern maintained stable trend of"northeast to southwest".The cities with similar efficiency had obvious trend of agglomeration in space,and there were two hotspots in the two ends of the economic belt.Besides coastal areas,the spillover effect of land use efficiency in the central cities was not fully reflected.(3)In terms of influencing factors,there were some differences in the direction and extent of force between the 11 factors in the eastern and western regions.The economic level contributed most to the time changes and spatial differences of urban land use efficiency,and the influence of the science and technology had not been exerted.The efficiency of urban land use was positively correlated with economic level and environmental level,and negatively correlated with the output value of the secondary industry.