Efficiency Estimation Of Urban Metabolism Via Emergy,DEA Of Time-series In Changsha City

With the progress of urbanization in the world,the urban system is increasingly becoming the center of the engine of human habitation,commercial activities and economic growth in the globalized world.Large population i nto the city,the city of human activities will be more frequently,the resulting problems of environmental pollution,human relationship problem,resource depletion will continue profoundly affects the advance of urbanization.In recent decades,with the rapid advancement of urbanization and industrialization in China,regional economy has developed rapidly.At the same time,regional environment and sustainable development have been greatly impacted.In "total catch big protection,don’t make big developm ent" as the guidance to promote the development of the Yangtze river economic belt,go the way of ecological green development priority is one of the important development of hunan province,the current and future tasks.And changsha city as the capital ci ty and at the heart of the city of changsha-zhuzhou-xiangtan urban agglomeration is an important economic growth pole and even the central province of hunan,the social and economic rapid development,but also accompanied by the increasing deterioration of the environment pollution and urban sustainable development capacity of weakening.So choose in changsha city as the study area,on the one hand,to enrich the urban metabolism theory research and case analysis,at the same time it also for changsha city "two type society" first try to provide theoretical basis and empirical references,and also for the other area of the city of hunan province sustainable development,green development demonstration and reference significance.This paper proposed an integrated value theory,principal component analysis(pca)and time sequence DEA evaluation method of urban metabolism,by the method can value theory,the social economic system and ecological system,at the same time,based on time sequence DEA model to fully consider the factor of the technological changes every year,more to consider in evaluating urban metabolism changes in technology,factors exerting influence on metabolic efficiency made up for the inadequacy of traditional DEA model calculation efficien cy.This article main research content is to be a more comprehensive study of urban metabolism of changsha,through the study of energy flow in changsha city ecological system can determine the related indexes,and establish the value evaluation system,an d through value analysis to evaluate the metabolism of changsha city pattern,characteristic and evolution.Meanwhile,the metabolic efficiency of changsha city from 2000 to 2014 was estimated based on the time series DEA model,and its metabolic results w ere evaluated.Results show that in late 2009 to 2009 years ago there was a short fall,overall efficiency index during 2011-2011 after it is comparatively steady upward trend and basic to maintain,and all four years of resource utilization is very effici ent.This is because in the wake of the financial crisis,industrial structure optimization,changsha,started in 2009,with the deepening of the adjustment of industrial structure and the country’s fiscal power input,and changsha play itself in the test area "two type society" policy advantage,changsha began to accelerate the construction of the urbanization,especially to strengthen the urban infrastructure construction,focus on strengthening the reform in logistics transportation,the main,urban comp lex construction investment.From the overall,overall efficiency index declined between 2003 and 2004,fell to the bottom in 2004,during this period,mainly considering the domestic by SARS disease,natural disasters,caused by inflation,coal oil supply remains tense,drag on the development of the economy.The main problems existing in the metabolism of changsha city are unreasonable utilization of urban resources and heavy load of ecological environment.The level of urban sustainable development needs to be improved.In this regard,changsha needs to improve from the following four aspects: 1.2.Strengthen environmental governance and incorporate environmental protection into urban planning;3.All departments should pay attention to the joint management and work together to improve the urban environmental management level;4.Improve relevant laws and regulations on the environment and strengthen the mechanism of environmental supervision and restraint.