Study On The Coordinated Development Between Water Environmental Quality And Social Economy In Nansi Lake Catchment

As the largest reservoir in the South-to-North Water Diversion Project?east line?,and an important section of the Beijing-Hangzhou Grand Canal,Nansi Lake has the strategic significance for the water safety,socio-economic development and ecological civilization construction in China.However,water environmental quality is facing increasing challenges in Nansi Lake catchment in recent years,with the economic transformation and rapid urbanization process.To investigate the coordinated and sustainable development between water environment and social economy in the catchment,extensive empirical researches had been carried out between them.Previous studies on the relationship between environment and economy were limited to qualitative and quantitative analysis among indicators,lacked researches between subsystems.Although some scholars studied the coupling coordination degree of environment–economy system,most of them focused the temporal dimension analysis,lacked spatial dimension analysis.There are relatively few studies on the spatiotemporal distribution characteristics between subsystems.And the internal dynamic mechanism between subsystems throughout the evolution from uncoordinated development to coordinated development cannot be revealed well.Taking Nansi Lake catchment as a study area,this paper used water environmental quality and socio-economic development data of Nansi Lake catchment in 2001–2017.Firstly,the environment Kuznets curve?EKC?model was used to study the relationship between typical water environment indicators and socio-economy indicators.And elasticity theory in economics was applied to reveal the control of wastewater emissions and pollutant emissions in wastewater from the perspective of total quantity control.Moreover,the comprehensive level of water environmental quality and socio-economic development subsystems was calculated by using the projection pursuit model based on genetic algorithm.And the coupling coordination degree model was used to analyze the state of coupling coordination between water environmental quality and social economic development subsystems from the spatiotemporal perspective.To further reveal the internal dynamic mechanism between two subsystems in the process of coordinated development,scissors difference model was applied to explore the evolution speed difference between water environmental quality and socio-economic development subsystems from the perspective of evolution rate.Eventually,a comprehensive study from"indicators"to"systems"perspective on the water environment–economy nexus in Nansi Lake catchment will be realized,which will provide theoretical supports for exploring the coordinated development model of the water environment and economy in the catchment.The specific research results are as follows:?1?The EKC research between typical water environment indicators and GDP per capita showed that industrial water pollution emissions showed an overall downward trend with economic growth.Domestic water pollution emissions showed an upward trend with economic growth,and were still in the first half of EKC,and had not yet reached the inflection point?peak point?.If the effective control measures are not taken in time,they may pose great potential risks on water environmental quality safety for Nansi Lake catchment in the future.?2?Elasticity theory was applied to reveal the control of wastewater emissions and pollutant emissions in wastewater from the perspective of total quantity control in recent five years.Results showed that the control of industrial wastewater emissions was much better than that of domestic wastewater emissions,and the control of pollutant emissions in wastewater was generally good.Especially since 2015,a significant control effect occurred in NH₃-N and COD emissions.?3?The comprehensive level of water environmental quality and socio-economic development subsystems in the catchment was an overall upward trend,especially since the12th Five-Year plan,the comprehensive level of water environmental quality subsystem had increased significantly.Overall,socio-economic development has a promoting effect on the improvement of water environmental quality in the catchment,and good water environmental quality provides a guarantee for the sustainable socio-economy development.From the perspective of temporal dimension,the state of coupling coordination between two subsystems can be divided into four stages,including moderately uncoordinated development?2001–2009?,slightly uncoordinated development?2010–2012?,slightly coordinated development?2013–2014?and moderately coordinated development?2015–2017?.At present,the value of coupling coordination degree between two subsystems is more than 0.6,and the state of coupling coordination is at the moderately coordinated development with water environmental quality lagged.Overall,the benign interaction mechanism between subsystems is gradually formed.From the perspective of spatial dimension,the state of coupling coordination between water environmental quality and socio-economic development subsystems in three cities of Nansi Lake catchment were gradually improved,among which Zaozhuang>Jining>Heze.?4?The scissors difference between water environmental quality and socio-economic development subsystems showed a decreasing trend,and can be divided into three stages.From 2001 to 2008?the break-in stage?,a downward trend occurred,meaning the interaction between two subsystems experienced an adequate break-in stage.In 2009–2011?the transitional stage?,a rapid downtrend occurred in scissors difference,indicating that the speed differences between two subsystems declined quickly and the interaction between subsystems was gradually optimized.From 2012 to 2017?the stable stage?,the speed difference between water environmental quality and socio-economic development subsystems kept a good situation,which made the favorable interactions between two subsystems continue to be maintained.The above achievements are of great significance for promoting the coordinated development between water environmental quality and socio-economic development in Nansi Lake catchment,and for realizing the sustainable socio-economic development and improving water environmental quality.Accordingly,relevant suggestions and measures were put forward to provide reference for formulating the water pollution control measures and reasonable economic development model in the region.