Research On The Convergence Of Water Pollution Emission Intensity In China

Water resources are the basis of human life.Since the reform and opening,China’s economy has experienced more than 40 years of rapid development,at the same time,we have also faced serious water pollution problems.The different geographical locations and economic development of China’s regions have resulted in regional differences in water pollution emissions,which is not conducive to the distribution of regional water pollution reduction tasks.Regional convergence theory can quantify regional differences and identify their core drivers.Therefore,it can provide an important basis for the reasonable allocation of regional water pollution reduction targets.According to this,this paper uses regional convergence theory to study and empirically analyze the convergence of water pollution emission intensity in China from 2008-2017.The specific research work is as follows:Firstly,as the agricultural water pollution statistics were not taken into account in China’s provincial water pollution statistics from 2008-2010,so in order to make the water pollution statistics consistent,this study uses ammonia nitrogen（NH₃-N）and chemical oxygen demand（COD）as the main analysis indicators and uses the production and discharge coefficient method to analyze and account for agricultural water pollution in China from 2008 to 2010.Based on this,we study the regional convergence of water pollution emission intensity in China qualitatively by kernel density distribution and standard deviation analysis and concludes that the provincial water pollution emission intensity in China has the same steady state trend from2008 to 2017.Secondly,considering the spatial heterogeneity and avoiding the estimation bias caused by the endogeneity of the model,this paper constructs a dynamic spatial Durbin modelanalyzes the convergence of water pollution emission intensity in China empirically by considering seven factors such as economic growth,industrial structure,technological progress and urbanization,and finds the exogenous drivers affecting water pollution emission intensity and tests its robustness.The results show that there is a positive spatial spillover effect andβconvergence of water pollution emission intensity at provincial level in China.Upgrading industrial structure and improving investment level are important factors to reduce water pollution emission intensity in China.Finally,in order to further study the regional characteristics of inter-provincial water pollution emissions in China to formulate a more scientific and reasonable regional water pollution reduction policy,this study uses K-means cluster analysis to divide China’s 30provinces and cities（excluding Tibet）into four clubs based on the qualitative and empirical analysis.This paper constructs convergence rate equations and semi-life-cycle models for each club and analyzes the convergence characteristics of the four clubs based on the absoluteβconvergence model and conditionalβconvergence model.The results of the absoluteβconvergence model show that the second club has the fastest convergence rate and the fourth club has the slowest convergence rate.Based on the principle of the fastest convergence rate and the most optimised fit,the results of the conditionalβconvergence model are used to identify the main factors influencing the convergence of the clubs.In summary,there isβconvergence of overall and regional water pollution emission intensity in China,which provides a scientific basis for the qualitative and quantitative allocation of regional water pollution reduction targets in China.