| As an inland river economic belt that supports China’s high-quality development,the Yangtze River Economic Belt accounts for half of the country’s population and economy,is the centre of gravity and vitality of China’s urbanization development,and occupies an essential position in the construction of a new pattern of green development.However,the negative impact caused by rapid urbanization cannot be ignored,resulting in risks such as ecological damage,environmental pollution and heat island effect.This short-sighted behavior of sacrificing the eco-environment in exchange for temporary development is undoubtedly poses a serious threat to the sustainable and healthy development of the Yangtze River Belt.The report of the 20 th National Congress of the Communist Party of China stated that we should resolutely safeguard national security,prevent and resolve major risks,focus on solving outstanding risk contradictions in the eco-environment field,and implement the overall national security concept.Therefore,it is necessary to conduct a systematic study on eco-environmental risks in urbanization in the Yangtze River Economic Belt,clarify the mechanism of urban development on eco-environmental risks,quantify the effect of urbanization on eco-environmental risks,and propose strategies to manage urbanization and eco-environmental risks from a synergistic perspective in response to the problems identified in the study.From the perspective of implementing the overall national security concept,this study focuses on the key issues of the impact effect and mechanism of urban development on eco-environmental risks in the Yangtze River Economic Belt,which has important theoretical significance and practical value for achieving green transformation of towns and cities in the Yangtze River Economic Belt and avoiding eco-environmental risks.According to the classic paradigm of discovering problems-proposing problemsanalyzing problems-solving problems,this thesis carried out a systematic study on the key issue of the impact of urbanization in the Yangtze River Economic Belt on ecoenvironmental risks.First,the theories,technologies and methods related to urbanization and eco-environmental risks at home and abroad are reviewed,and the shortcomings of existing literature,the nature of eco-environmental risks and their deep connection with urbanization are analyzed.This constitutes the starting point and theoretical basis of this study.Second,we construct an evaluation system of the ecoenvironmental risks index of the Yangtze River Economic Belt from the dimension of receptor-pressure-representation-response,and analyze the regional differences,spatial and temporal evolution and spatial clustering characteristics of eco-environmental risks in the Yangtze River Economic Belt;further,this thesis use the spatial durbin model to empirically test the spatial effects of urbanization on eco-environmental risks in the Yangtze River Economic Belt.Finally,the suggestions for the coordinated development of urbanization and eco-environment in the Yangtze River Economic Belt are put forward.The main research contents and results are as follows:(1)Based on the logic of current situation evaluation,risk measurement,spatial evolution and synergistic strategy,a research framework for the impact of urbanisation in the Yangtze River Economic Belt on eco-environmental risks is proposed.First,on the basis of sorting out the theories,technical methods and research conclusions related to urbanization and eco-environmental risks at home and abroad,we construct a theoretical foundation and influence mechanism supported by regional economic development,ecological environment security and collaborative governance,and make an objective evaluation of the development status of urban development and ecoenvironmental risks in the Yangtze River Economic Belt.Second,an evaluation system of eco-environmental risks index of the Yangtze River Economic Belt was constructed and quantitatively measured.Third,the Gini coefficient and its differential decomposition model,kernel density estimation and spatial analysis are applied to analyze the regional differences,spatial and temporal evolution and agglomeration characteristics of eco-environmental risks in the Yangtze River Economic Belt,and to empirically test the spatial impact effects of urbanization on eco-environmental risks in the Yangtze River Economic Belt.Fourth,combining the results of theoretical research and empirical tests,we propose relevant policy suggestions from the perspective of synergistic governance,and provide useful references for decision making related to the synergistic governance of urbanization and eco-environmental risks management in the Yangtze River Economic Belt.(2)Quantitatively measure the eco-environmental risks index of the Yangtze River Economic Belt and analyze its temporal and spatial evolution characteristics.First of all,an evaluation system of eco-environmental risks index is constructed from four aspects including receptor,pressure,representation and response,and the natural breakpoint classification method is used to classify the risk level.The result indicates that:(1)Overall,from 2000 to 2020,the eco-environmental risks index of the Yangtze River Economic Belt is between 50.25 to 92.16,with most areas along the belt at "higher risk".Among them,the eco-environmental risks level of Jiangsu is the highest in the Yangtze River Economic Belt,while Anhui is the lowest.(2)From the perspective of the river basin,the average risk value of the upstream area is 66.39,the midstream area is 71.09,and the downstream area is 69.35.It is concluded that the ecoenvironmental risks of the Yangtze River Economic Belt is in the middle reaches area >downstream area > upstream area.(3)From a regional perspective,the average ecoenvironmental risks value of Jiangsu province reached 80.11,which is the highest level of eco-environmental risks in the Yangtze River Economic Belt;the average ecoenvironmental risks value of Anhui province is 58.54,which is the lowest ecoenvironment risks area in the Yangtze River Economic Belt.Second,the spatial variability of eco-environmental risks in the Yangtze River Economic Belt was analyzed using the Gini coefficient and its decomposition model.Research results:(1)The overall Gini coefficient of eco-environmental risks in the Yangtze River Economic Belt is characterized by the evolution of "down-up-down-up-down-up-up-up-down".Among them,the largest internal differences are in the downstream area,followed by the upstream area,and the smallest differences are in the midstream area.(2)The contribution rate of hyper variable density is the main reason for the eco-environmental risks of the belt,with an average annual contribution rate of 42.61%,while the average annual contribution rate within the belt and the contribution rate between the belt are29.55% and 27.84%,respectively.Third,this paper uses the kernel density estimation method to describe the temporal and spatial evolution characteristics of the ecoenvironmental risks in the Yangtze River Economic Belt.The findings indicated that:(1)The nuclear density curve of eco-environmental risks in the Yangtze River Economic Belt shifts from the lower reaches to the middle and upper reaches,showing an "upward-declining" trend.(2)From the evolutionary pattern,the curve right trailing phenomenon is serious,and the eco-environmental risks gap within the Yangtze River Economic Belt has a tendency to further widen.(3)In terms of extension trend,the extension of eco-environmental risks in the belt shows a dynamic evolution of small narrowing,slight widening and slight converging,showing a certain degree of convergence characteristics.Fourth,according to the results of Moran’s I,there is a significant spatial autocorrelation in the Yangtze River Economic Belt,because ecoenvironmental risks value of the belt range [-0.446,0.097] under different matrices.(3)Use the SDM to measure and decompose the spatial effect of urbanization in the Yangtze River Economic Belt on eco-environmental risks.First,based on the results of Wald test,LR test and Hausman test,it is indicated that fixed effects should be selected instead of random effects to carry out the SDM analysis,and the estimation results of the SDM are more accurate than the Spatial Autoregressive(SAR)and the Spatial Error Model(SEM).Second,following the idea of economic development,population concentration,land expansion,social progress,the SDM is used to empirically test the spatial effect of urbanization in the Yangtze River Economic Belt on the eco-environmental risks.Under different matrics,the increase of variables such as pgdp,isep,pfa,pco,ppa in the local area,the eco-environmental risks in adjacent areas also increase,showing a positive correlation.However,the variables of psct and pec in this region are negatively correlated with the eco-environmental risks in the surrounding areas.Third,the spatial effect of urbanization in the Yangtze River Economic Belt affecting eco-environmental risks are decomposed from three aspects: direct effect,spillover effect and total effect.The results show that:(1)In the direct effect,the variable coefficients of pgdp,isep,pfa,pco,ppa are all positive numbers,indicating that they have a promoting effect on eco-environmental risks in the region.While the variable coefficients of isp,pd,pra,psct,pec are all negative,implying that they have a suppressive effect on the eco-environmental risks in the local.(2)Among the spillover effect,positive coefficients for the variables of pgdp,isep,pba,pec,pga,which mean that they have a positive spillover effect on eco-environmental risks in adjacent areas.But the coefficients of variables including pd,pra,psct,ppa are negative,indicating that they have a negative spillover effect on eco-environmental risks in surrounding areas.(3)As for the total effect,the positive coefficients of pgdp,pba,pga indicate their positive effect on the eco-environmental risks of the whole belt.At the same time,pd,pra,psct and other vaiables,the coefficient is negative,indicating that it has a negative effect on the eco-environmental risks of the whole belt.(4)Put forward suggestions on coordinated governance of urbanization and ecoenvironmental risks in the Yangtze River Economic Belt from the aspects of energy coordination,financial coordination,dual carbon strategy coordination,urban development coordination and industrial coordination.First,optimize the energy structure,vigorously develop clean energy,promote the interconnection of energy facilities,and achieve energy synergy.Second,give full play to the guiding role of financial funds,vigorously develop "Green+" financial products,increase investment in eco-environmental risks management through multiple channels,and achieve financial coordination.Third,we will further promote the construction of pollution reduction and carbon reduction systems and mechanisms,incentives and constraints,and policy systems to achieve the synergy of the two carbon strategies.Fourth,we will optimize the layout of urban development,promote joint prevention and control of ecoenvironmental risks,and connect transportation infrastructure,in order to achieve coordinated urban development.Fifth,improve the top-level design of industrial development,promote the orderly transfer of industries and improve the relevant policy system to achieve industrial synergy.The main innovations of this study are as follows:(1)From the perspectives of receptor,pressure,representation and response,a set of eco-environmental risks index measurement system in the Yangtze River Economic Belt is constructed,which more comprehensively describes the temporal and spatial evolution characteristics of eco-environmental risks in the Yangtze River Economic Belt.Based on the estimation of the eco-environmental risks index over a long period of time,this research analyzes the temporal and spatial evolution and extension trend of the eco-environmental risks in the Yangtze River Economic Belt.In addition,the thesis discusses the spatial differences of eco-environmental risks in the Yangtze River Economic Belt during the transition period,and reveals the evolution process and influencing factors of eco-environmental risks in the Yangtze River Economic Belt,which is conducive to further enriching the literature on eco-environmental risks.(2)Under the established top-level framework of the overall national security concept,this thesis clarifies the mutual feedback relationship and impact mechanism between urbanization and eco-environmental risks,empirically analyzes the urbanization of the Yangtze River Economic Belt from three aspects: direct effect,spillover effect and total effect.The impact on eco-environmental risks fully reflects the realistic logic and inherent needs of the high quality development and the construction of ecological civilization of the Yangtze River Economic Belt.To a certain extent,this study makes up for the lack of empirical analysis on the impact of urbanization in the Yangtze River Economic Belt on eco-environmental risks.(3)The concept of coordinated governance is introduced,and the optimization path for the coordinated development of urbanization and eco-environmental risks in the Yangtze River Economic Belt is proposed.Based on the spatial heterogeneity of ecoenvironmental risks in the process of urban development,this study analyzes a coordinated governance strategy for urban development and eco-environmental risks in the Yangtze River Economic Belt from the perspective of energy synergy,financial synergy,dual carbon strategy synergy,urban development synergy and industrial synergy,which can provide experience and reference for the coordinated governance of urbanization and eco-environmental risks in other similar regions.On the other hand,it can also provide decision support for preventing and resolving security risks in major areas and implementing major initiatives of the overall national security concept. |
