| Under the background of the steady growth of the national economy and the rapid advancement of new urbanization,the rapid expansion of urban construction land is an important feature of current urban development in China.Urban construction land is used as the main carrier of urban development and economic activities which affects all kinds of production activities and is affected by various aspects.The fact that there are more people and less land is the basic national condition of China.The contradiction between the limited supply of urban construction land and the land needed for urban development is prominent.The introduction of the policy of cultivated land protection and the expansion urban of“big cake”style are also difficult to sustain,strengthen supply-Side structural reforms,how to rationally allocate urban construction land,obtain maximum output with minimum input,and improve land use efficiency are issues that need to be solved in today's urban development.This paper takes the cities of Sichuan Province as the research object.Firstly,it uses the information entropy model and the offset-share model to measure the temporal and spatial characteristics of land use change in prefecture-level cities and county-level cities.Secondly,it is based on the measurement and analysis of super-efficient SBM models with undesired outputs to measure,the changed law of urban land use efficiency.Finally,based on the STIRPAT model,an extended model of the impact of land use structure on land use efficiency is constructed,and the impact of structure on efficiency is analyzed.This paper has the following research conclusions:(1)The scale of urban construction land is expanding continuously,and the land use structure is becoming more and more perfect.From the perspective of the scale of urban construction land,the total amount of urban construction land in Sichuan Province shows a growing trend,which is relatively consistent with China's economic development and urbanization process.From the initial 1101.31km~2 to the final 2694.48km~2,the total area increased by 2.24 times,with an average annual growth rate of 8.28%,higher than the average annual growth rate of urban construction land in the same period.From the perspective of the urban construction land structure,In terms of time series changes,the information entropy of urban construction land structure is generally characterized as periodic fluctuation rising trend.Compared with 2002,the information entropy value increased by 0.0116 Nat in2016,with an average annual growth rate of 0.045%.The disorder of land use structure is enhanced,and the diversity is obvious.The structural information entropy in the city is characterized by two trends:fluctuation rise and fluctuation drop.In terms of spatial change,the structural offset of urban construction land is consistent,the land for growth structure is public facilities land and green land,and the rest is for degraded structural land.The recharge effect of prefecture-level cities is significant,and the crowding effect of county-level cities is significant.(2)The three efficiency values of urban construction land show a trend of“fluctuation rising”.From the perspective of the efficiency of urban construction land,the comprehensive technical efficiency,pure technical efficiency and scale efficiency respectively increased from 0.441,0.697,and 0.691 to 0.859,0.890,and 0.969 from2002 to 2016,which the comprehensive technical efficiency fluctuated the most.And the performance is scale efficiency>pure technical efficiency>comprehensive technical efficiency,the contribution of scale efficiency to comprehensive technical efficiency is greater,and the pure technical efficiency has a greater impact on the efficiency of the integrated technology.The intensive degree of urban construction land has been improved,and the allocation level of input and output has improved.The three efficiency values of land use of cities in prefecture-level cities and county-level cities fluctuated,and fluctuated in the average level of Sichuan Province.50%of urban land use efficiency is effective,and a few cities are in an inefficient state,the heterogeneity of urban land use efficiency is obvious.(3)The impact of changes in the proportion of urban construction land on land use efficiency is significantly different.From the perspective of the impact of the land use on land use efficiency,the land for daily use is the main factor affecting the efficiency of urban construction land,and it has significant impact on different levels of cities;production land is the direct factor affecting the improvement efficiency of urban construction land;ecological land is an indispensable factor affecting the improvement efficiency of urban construction land.Land for public facilities and industrial land can directly generate economic benefits,while residential land and green space play an important role in urban economic development and land use efficiency.The interaction of the construction land structure within each city and the mutual restraint will jointly affect the efficiency of land use.According to the respective development orientation of each city,it is necessary to differentiate and rationally optimize urban land use. |
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