Urban Water Resources Accounting And Industrial Structure Adjustment Based On Input-Output Analysis

With the urbanization,such problems as water shortage and water pollution have occurred in most of cities,which hinder the sustainable development of cities.At the same time,the emergence of such problems is closely related to the industrial structure adjustment.Industrial structure adjustment is a key way to promote urban sustainability,but its specific impact on the alleviation of urban water shortage and pollution is still unknown.In this context,it is necessary to make a systematic accounting of urban water resources and explore the best plan of industrial structure adjustment from the perspective of water resources saving and water environmental protection,so as to promote the coordinated management of urban social economy,water resources and water environment.At present,considering the correlation between industrial sectors,urban water resources accounting using IOA（Input-Output Analysis）is a research hotspot.Since the method relies on IO（Input-Output）table,which is lacking in most of prefecture-level cities,the water resources accounting of such cities is fuzzy.In view of the above research gap,we firstly proposed an urban water resources accounting method based on the perspective of industrial interaction,including data acquisition based on IO table,multidimensional accounting framework construction and index calculation.Secondly,on the basis of systematic accounting and comprehensive analysis of urban water resources,the multi-objective planning model of industrial structure adjustment was constructed,and the optimal mode of industrial structure adjustment was explored by different scenarios.Specifically,first,for a city without IO tables,we constructed a method to compile noncompetitive IO tables based on city-level multi-regional input-output（MRIO）tables.Then,taking the compiled IO table as core data,an urban water resources accounting framework was established for the three dimensions of the entire city,sectoral level,and intersectoral interactions to calculate indicators and to quantitatively analyze the characteristics of urban water resources consumption and water pollution.Thirdly,the economic correlation,water consumption coefficients and water pollutant discharge correlation coefficients were calculated,based on which the industry types were divided.Finally,the target was set as increasing economic income by 5%,reducing total industrial water consumption by 5%,reducing COD（chemical oxygen demand）emission in industrial wastewater by 20%,and reducing NH₃-N emission by 18%.Based on the principle of input-output balance,the industrial structure adjustment models of economic growth-the constraint of water resources,economic growth-the constraint of water environment,economic growth-the constraint of water resources and water environment were constructed respectively to explore industrial structure adjustment schemes that can promote urban economic growth,water resources conservation and wastewater mission reduction.Dongguan,a prefecture-level city in Guangdong Province（China）with developed manufacturing industries but water resource shortages was chosen as a case study.The results of water resources accounting and industrial structure adjustment were introduced in details as follows.（1）The accounting results of the whole city show that the total water consumption decreased by 109.96 million m³ during 2012～2017 when the city’s economy was growing steadily.Meanwhile,the total discharge of COD,TP,TN and NH₃-N in urban wastewater was estimated to be 8600 m³in 2017.Among them,COD discharge accounts for 78%.（2）The calculation results of sector show that the direct water consumption associated with the electronic information manufacturing industry was the largest,and the gray water footprint with the service industry was the largest.However,the direct water consumption coefficient and gray water discharge coefficient of agriculture were much higher than that of other sectors.In 2017,agriculture was the key sector of virtual water and virtual water pollution outflow,service was the key sector of virtual water inflow and virtual water pollution outflow,while electronic information manufacturing（electrical machinery and equipment manufacturing and communication equipment manufacturing）was the key sector of virtual water inflow and virtual water pollution inflow.（3）The calculation results of virtual water transfer matrix between sectors and virtual water pollution transfer matrix show that virtual water flowed from agriculture to food processing and manufacturing industry,and from electricity,gas and water production and supply industry to electronic information manufacturing industry.At the same time,the flow of virtual water pollution from service industry to industrial sub-sectors,especially to electronic information manufacturing,textile and other manufacturing industries,might hinder the reduction of urban water pollution emission.（4）The results of industrial structure adjustment under the constraints of water resource and water environment show that industrial structure adjustment can achieve the target of5%growth of economic income and promote the reduction of total industrial water consumption,but cannot reduce industrial COD and NH₃-N emissions,and have a negative impact on the target of reducing water pollution in 2017.In scenario 1,the industrial structure adjustment effect is the best,in which the total input of encouraging development industries increase by 5%and the total input of restricting development industries decrease by 5%,and the total input of food processing and manufacturing industry and electronic information manufacturing industry is moderately reduced.Moderately increasing the total input of textiles,wood processing and furniture manufacturing,paper manufacturing,chemical manufacturing,other manufacturing industries,electricity,gas and water production and supply industries may be conducive to healthy urban development.The established urban water resources accounting method and the industrial structure adjustment model under the constraints of water resources and water environment in this work provides a baseline for the urban water resources accounting and industrial transformation research.The results of Dongguan can provide reference for the future industrial development direction of Dongguan and the solution of the collaborative problem of water resources and water pollution.Moreover,it also reminders other cities that urban collaborative management should consider both water resources consumption and urban water pollution discharge.