Study Of Metabolism Characteristics And Its Driving Factors In Oasis Cities

Urban area is the region where has the strongest interactions in the human-earth system.With the rapid development of large-scale urbanization,the contradiction among economic development,resource utilization,and the ecological environment has become increasingly prominent in cities.Therefore,to promote urban sustainable development,it is essential to construct the mode of urban development by integrating the resources,the ecological environment,and the economy.Urban metabolism provides a new prospective for exploring the sustainability of urban development.Urban metabolism regards the city as an organism,and the interrelationship among urban society,the economy,and the natural environment are examined in terms of resource utilization to identify the impact of the external environment on the city,which is an effective method for evaluating the utilization of resources and the problems of ecological environment in cities.Oasis city,with features of drought,diversity,closure,and vulnerability,which is a typical urban type mainly distributed in arid and semi-arid areas.The sustainable development of Oasis cities is of great importance to regional sustainable development and national security.Therefore,from the perspective of urban metabolism,exploration of the sustainability of development of cities plays significant roles in the formulation of urban development strategies and the promotion of the efficient utilization of resources.Based on the theory of urban metabolism,this dissertation constructs the analytical framework of the study of metabolism for Oasis city based on the “scale-efficiencystructure-influence” as the main research logic.This dissertation takes the typical Oasis cities in Xinjiang as examples,the metabolism characteristics and its driving factors of Oasis cities in 2002,2007,2012 and 2017 were studied by using the material flow analysis,data envelopment analysis model,input-output analysis,ecological network analysis,and the extended STIRPAT model.This study firstly analysis the changes of the scale and structure on material resources,and the status of emissions of pollutants in Oasis cities.Afterwards,the characteristics of the metabolic efficiency of material resources and their evolution modes in Oasis cities are explored.Then,this study identifies the internal relationships between various departments in the urban metabolic system.At last,this study explores the main driving factors of Oasis cities' metabolism.The main contents and the results of this dissertation are concluded as follows:(1)The total material demand(TMR)and total material emissions(TDO)in Oasis cities both presented an increasing trend.And,local hidden flows and direct material inputs(DMI)were the main components of TMR,while fossil fuels and solid wastes were the principal components of DMI and production process emissions(DPO)respectively.The intensity of material consumption(IMC)in cities has been increasing,and the material productivity(MP)showed a steadily increasing trend.DMI per capita in Oasis cities showed an obvious increasing trend,with the values ranged from 0.52?44.67tons/person in 2002 to 2.05?89.33 tons/person in 2017,and the resource pressures of cities presented the features of agglomeration from eastern to northern Xinjiang.The resource productivity of cities presented a fluctuating expansion trend,and cities with higher resource productivity were mostly distributed in northern Xinjiang.DPO per capita in different cities varied,and the average annual growth rate is 13.85%.The scale and growth rate of DPO per capita in the regional central cities in eastern and northern of Xinjiang were relatively high,such as Hami,Turpan,Shihezi,and Fukang.The average annual growth rate of environmental efficiency of cities was 8.5%,which was lower than that of DPO per capita,and cities with the low environmental efficiency were mainly distributed in eastern Xinjiang.(2)Fossil fuels accounted for the largest proportion of DMI,and the high values of fossil fuels were mainly distributed in resource-rich areas(e.g.Karamay,Korla,and Hami).The high values of biomass were mainly concentrated in Tacheng and Wusu,while the high values of metal minerals were mainly distributed in Urumqi,Changji,and Fukang.Non-metallic minerals are widely distributed.The emissions of solid wastes accounted for the largest proportion of DPO,followed by air pollutants and dissipative substances,while water pollutants were relatively low.The growth of pollutant emissions of cities in northern and eastern Xinjiang were relatively fast,indicating that the environmental pressures for these cities were relatively high.Therefore,we should pay more attention for the city in these regions.(3)The values of the metabolic efficiency of Oasis cities experienced a steadily and slowly increasing trend overall,and the metabolic efficiency differed among cities.From2002 to 2017,the mean comprehensive efficiency of urban metabolism increased b y approximately 1.8%.The number of cities in which the pure technical efficiency reached the optimal DEA efficiency was the largest(the efficiency value was 1),and the values of scale efficiency and the number of cities with decreasing returns to scale were increased.The pure technical efficiency change in urban metabolism presented a decreasing trend,while the other indices showed increasing trend.The cities were mainly types II and III,and most were belonged in the stable mode and progressive mode.It can be seen that since the development of the western region,the development of cities has been no longer dominated by low cost of resources and high cost of resources and the environment,and its development mode is changing.However,due to a lack of technological innovation ability,strong diseconomies of scale are observed.Therefore,constantly optimizing the efficiency of local resource allocation,improving the level of technology,and forming a suitable scale effect are essential for gradually increasing the levels of metabolic efficiency of cities.(4)The manufacturing industry(MI),transportation,storage,post and telecommunication services(TSP),construction(C),and other services(Ser)were the important departments for resource management of Oasis cities,and their flow path was also the key ways for urabn resource management.There were differences in the relative flow of each department in the urban metabolic system,indicating that the flow paths in the system were increased continuously with social economic development of the city.The contribution rate of manufacturing industry(MI)and other services(Ser)were relatively high in the structure of urban metabolic system,and the average of contribution rate reached 40.29% and 29.66%,respectively.It implys that they played an important role in the normal metabolism for the whole system.The relationships among different departments were dominated by predatory and restriction,and the symbiotic indexes were greater than 1,indicating that the development of urban metabolic system was in a positive direction on the whole.The control of construction(C),transportation,storage,post and telecommunication services(TSP)and other services(Ser)on most departments showed an increasing trend in different degrees,while most departments in 2002,2007 and 2012 were dependented on production and supply of electricity,gas and water(EGW).Additionally,the values of Ascendency in the urban metabolic system were obvious increased,indicating that the urban system was still at the stage of unsustainable development.(5)The total population and per capita GDP had a significant positive impaction on the direct material inputs of cities,and the influence intensity showed a gradually strengthen trend.Among them,for each increase of 1% in total population and per capita GDP in 2002,2007,2012 and 2017,the direct material inputs of cities will significant increase by 1.054%,1.145%,1.184%,1.257% and 0.863%,0.720%,0.608%,0.950%,respectively.The proportion of tertiary industry and resource productivity had a significant negative impaction on the direct material inputs of cities.Furthermore,urbanization has a positive impact on the direct material input of cities,which presents a weakening trend,with low estimated coefficients.It can be seen that population size and economic level are the major driving forces to promote material growth in Oasis cities,the advance of tertiary industry is an important driver to promote the healthy development of material metabolism in Oasis cities,and the improvements of technical level and the efficiency of resource utilization are a key way to achieve material reduction of Oasis cities.