| Pollution space is caused by the accumulation of a large amount of waste water,waste gas and waste residue discharge during the urban development accompanied by the industrialization and population agglomeration.On the one hand,the pollution space causes a great threat on the urban environment and ecology,urban residents' health and security.On the other hand,a well geographical location provides the huge potential economic and social values for re-developing the pollution space in the new cycle of urban development.Updating the pollution space gradually attracts people's attention.Starting from the international researches on 'brownfield redevelpoment',western countries have carried out an extensive exploration about the reuse of contaminated sites and abandoned lands,which were left over after the industrial revolution.These have produced a series of worthy research theories,development modes,policies and regulations,and planning cases.However,the related domestic studies are rather late,and mainly focus on the introductions of theories abroad and calling for policies.The systematic theories and technologies for spatial regulation of pollution space update are still in vacancy.Therefore,this study took the Changsha-Zhuzhou-Xiangtan Urban Agglomeration as an example,which was one of old industrial bases since the foundation of new China,began with the pollution space identification,explored the distribution rule and causes of the pollution space,analyzed the relationship between the pollution space and the main space of urban agglomeration,measured the risks and benefits of updating these pollution spaces,excogitated the patterns and planning technologies of pollution space update,etc..In this way,a set of comprehensive rearch technical route is generated,based on which this paper designed a scheme of the spatial structure optimization at the perspective of pollution space update for Changsha-Zhuzhou-Xiangtan Urban Agglomeration.The main research points and conclusions are as follows.(1)After taking the detection data of air,water and soil pollutions from environmental testing stations in Changsha,Zhuzhou and Xiangtan City,the GIS spatial analysis software is employed to identify the pollution space in the core region of Changsha-Zhuzhou-Xiangtan Urban Agglomeration.Some interesting findings are then drawn,that is,PM10 and S02 are the main atmospheric pollutants,and the severe pollution areas exist in the central downtowns of Changsha,Zhuzhou and Xiangtan City and exhibit dots distribution;the water quality generally reaches the standard,and the main pollution sources come from ammonia,nitrogen and various kinds of heavy metals,which exhibits the significant seasonal variation;the soil pollution is relatively severe with a wide coverage.Taking Shifeng District of Zhuzhou City as an example,the Cadmium pollution is the most severe;Comprehensive pollution spaces are mainly concentrated in the center of these three cities.The polluted area is quite large in Zhuzhou City with the concentrated distribution shape,Changsha and Xiangtan has dispersed pollution plaques.(2)Inspired by the theories and methodologies of the landscape ecology,the study built the measurement index for the relation between the pollution space and the main space from two aspects of space scale structure and spatial distribution pattern difference,which aims to to analyze the spatial pollution effect of Changsha-Zhuzhou-Xiangtan Urban Agglomeration.Some important results are concluded,that is,the spatial relationship pattern of Changsha-Zhuzhou-Xiangtan Urban Agglomeration presents an obvious change law along the urban-rural gradient.Both the intensity and compact degree of development in the central urban area are significantly higher than those in the peripheral counties.The ecological fragmentation is gradually reduced from the downtown to the peripheral counties,while the change law about the ecological supply capability is just the reverse.The reinforcement effect of the spatial pollution is relatively high in downtowns of these three cities,exhibiting the fearure of concentrated distribution;the purification capability of spatial pollution is gradually weakened from the peripheral counties to the downtown.(3)Based on the lifecycle theory,this study built a comprehensive risk evaluation index system,which consists of policy and law risk,economic risk,organization risk,pollution risk,technology risk and other possible risks in the process of pollution space updating.Then,the method of multi-hierarchical grey clustering is used to evaluate the comprehensive risk of updating each type of pollution space in Changsha-Zhuzhou-Xiangtan Urban Agglomeration.Some results are summaried,that is,the comprehensive risk of updating the pollution space in this Urban Agglomeration falls in the medium level,and the risk slightly varies with the different pollution level of the pollution space.Moreover,constructing the Comprehensive Reform Pilot Area based on"Two-type Society"(Resource conservation and environment friendly)encourages the government of Changsha-Zhuzhou-Xiangtan Urban Agglomeration to pay more attention to the environmental protection and pollution abatement,which benefits to reduce the comprehensive risk of updating the pollution space.However,the inter-district restoration and update of the pollution space increases the administrative communication and overall coordination across the region,which makes the comprehensive risk increased.(4)An evaluation index system for the comprehensive benefits of updating the pollution space is built,which is from the viewpoints of environment benefits,resource benefits,economic benefits,social benefits and investment benefits.Then,the weighted multi-hierarchical grey evaluation method is applied to measure the comprehensive benefits of various ways to update the pollution space.Some meaningful conclusions are obtained,that is,the commercial land takes the highest comprehensive benefits,which is orderly followd by the green land,industrial land and living land.Under the prerequisite that the pollution space can be repaired and reused,the commercial land is the best option of development,which is due to its advantages of compact land use,high economic value and promoting the city vigor.However,usually repairing the pollution space is difficult and takes a long cycle,and most pollution spaces do not have the proper conditions of developing into the construction land.Therefore,repairing them into the green land is the development plan with the advantages of the best practice and short-term operation.(5)Based on the aforementioned results,the indexes about the pollution level,pollution effect,society and economics,risk and benefit are employed to construct a judgement formula for the pollution space update and design the classification standards.This helps set the specific update pattern for each type of region unit from the macroscopic viewpoint.Then,as for the pollution spaces,the land replacement methods,the migration distance standards,and the adjustment ways of the land use structure and land spatial layout are further summarized.After that,they are utilized to design a set of spatial optimization schemes at the perspective of pollution space update for the example of Changsha-Zhuzhou-Xiangtan Urban Agglomeration.These obtained schemes focus on the repair-renovation and relocation-transformation for the pollution space identified,and the adjustment of land use structure and spatial layout optimization,which aims to reduce the generation,spreadout and interference of the pollution space in the urban agglomeration.Meanwhile,the reasonable space reconstruction and function division are also realized from the viewpoint of strengthening the regional connection and overall coordination for the urban agglomeration. |
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